/*************************************************
*      Perl-Compatible Regular Expressions       *
*************************************************/


/* This is a library of functions to support regular expressions whose syntax
and semantics are as close as possible to those of the Perl 5 language. See
the file Tech.Notes for some information on the internals.

Written by: Philip Hazel <ph10@cam.ac.uk>

           Copyright (c) 1997-2003 University of Cambridge

-----------------------------------------------------------------------------
Permission is granted to anyone to use this software for any purpose on any
computer system, and to redistribute it freely, subject to the following
restrictions:

1. This software is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

2. The origin of this software must not be misrepresented, either by
   explicit claim or by omission.

3. Altered versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

4. If PCRE is embedded in any software that is released under the GNU
   General Purpose Licence (GPL), then the terms of that licence shall
   supersede any condition above with which it is incompatible.
-----------------------------------------------------------------------------
*/

/* Modified by Shawn Wagner for MUX to fit in one file and remove
   things we don't use, like a bunch of API functions and utf-8
   support. If you want the full thing, see http://www.pcre.org.

   Patched by Alierak to protect against integer overflow in repeat
   counts.
 */

#include "autoconf.h"
#include "config.h"

#include <limits.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <stddef.h>
#include "pcre.h"

#include "externs.h"
#include "timeutil.h"

/* Bits of PCRE's config.h */
#define LINK_SIZE 2
#define MATCH_LIMIT 100000
#define NEWLINE '\n'

/* Bits of internal.h */
/* This header contains definitions that are shared between the different
modules, but which are not relevant to the outside. */


/* PCRE keeps offsets in its compiled code as 2-byte quantities by default.
These are used, for example, to link from the start of a subpattern to its
alternatives and its end. The use of 2 bytes per offset limits the size of the
compiled regex to around 64K, which is big enough for almost everybody.
However, I received a request for an even bigger limit. For this reason, and
also to make the code easier to maintain, the storing and loading of offsets
from the byte string is now handled by the macros that are defined here.

The macros are controlled by the value of LINK_SIZE. This defaults to 2 in
the config.h file, but can be overridden by using -D on the command line. This
is automated on Unix systems via the "configure" command. */

#define PUT(a,n,d)   \
  (a[n] = static_cast<uschar>((d) >> 8)), \
  (a[(n)+1] = static_cast<uschar>((d) & 255))

#define GET(a,n) \
  (((a)[n] << 8) | (a)[(n)+1])

#define MAX_PATTERN_SIZE (1 << 16)


/* Convenience macro defined in terms of the others */

#define PUTINC(a,n,d)   PUT(a,n,d), a += LINK_SIZE


/* PCRE uses some other 2-byte quantities that do not change when the size of
offsets changes. There are used for repeat counts and for other things such as
capturing parenthesis numbers in back references. */

#define PUT2(a,n,d)   \
  a[n] = static_cast<uschar>((d) >> 8); \
  a[(n)+1] = static_cast<uschar>((d) & 255)

#define GET2(a,n) \
  (((a)[n] << 8) | (a)[(n)+1])

#define PUT2INC(a,n,d)  PUT2(a,n,d), a += 2

/* These are the public options that can change during matching. */

#define PCRE_IMS (PCRE_CASELESS|PCRE_MULTILINE|PCRE_DOTALL)

/* Private options flags start at the most significant end of the four bytes,
but skip the top bit so we can use ints for convenience without getting tangled
with negative values. The public options defined in pcre.h start at the least
significant end. Make sure they don't overlap, though now that we have expanded
to four bytes there is plenty of space. */

#define PCRE_FIRSTSET      0x40000000  /* first_byte is set */
#define PCRE_REQCHSET      0x20000000  /* req_byte is set */
#define PCRE_STARTLINE     0x10000000  /* start after \n for multiline */
#define PCRE_ICHANGED      0x08000000  /* i option changes within regex */

/* Options for the "extra" block produced by pcre_study(). */

#define PCRE_STUDY_MAPPED   0x01     /* a map of starting chars exists */

/* Masks for identifying the public options which are permitted at compile
time, run time or study time, respectively. */

#define PUBLIC_OPTIONS \
  (PCRE_CASELESS|PCRE_EXTENDED|PCRE_ANCHORED|PCRE_MULTILINE| \
   PCRE_DOTALL|PCRE_DOLLAR_ENDONLY|PCRE_EXTRA|PCRE_UNGREEDY|PCRE_UTF8| \
   PCRE_NO_AUTO_CAPTURE|PCRE_NO_UTF8_CHECK)

#define PUBLIC_EXEC_OPTIONS \
  (PCRE_ANCHORED|PCRE_NOTBOL|PCRE_NOTEOL|PCRE_NOTEMPTY|PCRE_NO_UTF8_CHECK)

#define PUBLIC_STUDY_OPTIONS 0   /* None defined */

/* Magic number to provide a small check against being handed junk. */

#define MAGIC_NUMBER  0x50435245UL   /* 'PCRE' */

/* Negative values for the firstchar and reqchar variables */

#define REQ_UNSET (-2)
#define REQ_NONE  (-1)

/* Flags added to firstbyte or reqbyte; a "non-literal" item is either a
variable-length repeat, or a anything other than literal characters. */

#define REQ_CASELESS 0x0100    /* indicates caselessness */
#define REQ_VARY     0x0200    /* reqbyte followed non-literal item */

/* Miscellaneous definitions */

/* Escape items that are just an encoding of a particular data value. Note that
ESC_n is defined as yet another macro, which is set in config.h to either \n
(the default) or \r (which some people want). */

#ifndef ESC_e
#define ESC_e 27
#endif

#ifndef ESC_f
#define ESC_f '\f'
#endif

#ifndef ESC_n
#define ESC_n NEWLINE
#endif

#ifndef ESC_r
#define ESC_r '\r'
#endif

/* We can't officially use ESC_t because it is a POSIX reserved identifier
(presumably because of all the others like size_t). */

#ifndef ESC_tee
#define ESC_tee '\t'
#endif

/* These are escaped items that aren't just an encoding of a particular data
value such as \n. They must have non-zero values, as check_escape() returns
their negation. Also, they must appear in the same order as in the opcode
definitions below, up to ESC_z. There's a dummy for OP_ANY because it
corresponds to "." rather than an escape sequence. The final one must be
ESC_REF as subsequent values are used for \1, \2, \3, etc. There is are two
tests in the code for an escape greater than ESC_b and less than ESC_Z to
detect the types that may be repeated. These are the types that consume a
character. If any new escapes are put in between that don't consume a
character, that code will have to change. */

enum { ESC_A = 1, ESC_G, ESC_B, ESC_b, ESC_D, ESC_d, ESC_S, ESC_s, ESC_W,
       ESC_w, ESC_dum1, ESC_C, ESC_Z, ESC_z, ESC_E, ESC_Q, ESC_REF };

/* Flag bits and data types for the extended class (OP_XCLASS) for classes that
contain UTF-8 characters with values greater than 255. */

#define XCL_NOT    0x01    /* Flag: this is a negative class */
#define XCL_MAP    0x02    /* Flag: a 32-byte map is present */

#define XCL_END       0    /* Marks end of individual items */
#define XCL_SINGLE    1    /* Single item (one multibyte char) follows */
#define XCL_RANGE     2    /* A range (two multibyte chars) follows */


/* Opcode table: OP_BRA must be last, as all values >= it are used for brackets
that extract substrings. Starting from 1 (i.e. after OP_END), the values up to
OP_EOD must correspond in order to the list of escapes immediately above.
Note that whenever this list is updated, the two macro definitions that follow
must also be updated to match. */

enum {
  OP_END,            /* 0 End of pattern */

  /* Values corresponding to backslashed metacharacters */

  OP_SOD,            /* 1 Start of data: \A */
  OP_SOM,            /* 2 Start of match (subject + offset): \G */
  OP_NOT_WORD_BOUNDARY,  /*  3 \B */
  OP_WORD_BOUNDARY,      /*  4 \b */
  OP_NOT_DIGIT,          /*  5 \D */
  OP_DIGIT,              /*  6 \d */
  OP_NOT_WHITESPACE,     /*  7 \S */
  OP_WHITESPACE,         /*  8 \s */
  OP_NOT_WORDCHAR,       /*  9 \W */
  OP_WORDCHAR,           /* 10 \w */
  OP_ANY,            /* 11 Match any character */
  OP_ANYBYTE,        /* 12 Match any byte (\C); different to OP_ANY for UTF-8 */
  OP_EODN,           /* 13 End of data or \n at end of data: \Z. */
  OP_EOD,            /* 14 End of data: \z */

  OP_OPT,            /* 15 Set runtime options */
  OP_CIRC,           /* 16 Start of line - varies with multiline switch */
  OP_DOLL,           /* 17 End of line - varies with multiline switch */
  OP_CHARS,          /* 18 Match string of characters */
  OP_NOT,            /* 19 Match anything but the following char */

  OP_STAR,           /* 20 The maximizing and minimizing versions of */
  OP_MINSTAR,        /* 21 all these opcodes must come in pairs, with */
  OP_PLUS,           /* 22 the minimizing one second. */
  OP_MINPLUS,        /* 23 This first set applies to single characters */
  OP_QUERY,          /* 24 */
  OP_MINQUERY,       /* 25 */
  OP_UPTO,           /* 26 From 0 to n matches */
  OP_MINUPTO,        /* 27 */
  OP_EXACT,          /* 28 Exactly n matches */

  OP_NOTSTAR,        /* 29 The maximizing and minimizing versions of */
  OP_NOTMINSTAR,     /* 30 all these opcodes must come in pairs, with */
  OP_NOTPLUS,        /* 31 the minimizing one second. */
  OP_NOTMINPLUS,     /* 32 This set applies to "not" single characters */
  OP_NOTQUERY,       /* 33 */
  OP_NOTMINQUERY,    /* 34 */
  OP_NOTUPTO,        /* 35 From 0 to n matches */
  OP_NOTMINUPTO,     /* 36 */
  OP_NOTEXACT,       /* 37 Exactly n matches */

  OP_TYPESTAR,       /* 38 The maximizing and minimizing versions of */
  OP_TYPEMINSTAR,    /* 39 all these opcodes must come in pairs, with */
  OP_TYPEPLUS,       /* 40 the minimizing one second. These codes must */
  OP_TYPEMINPLUS,    /* 41 be in exactly the same order as those above. */
  OP_TYPEQUERY,      /* 42 This set applies to character types such as \d */
  OP_TYPEMINQUERY,   /* 43 */
  OP_TYPEUPTO,       /* 44 From 0 to n matches */
  OP_TYPEMINUPTO,    /* 45 */
  OP_TYPEEXACT,      /* 46 Exactly n matches */

  OP_CRSTAR,         /* 47 The maximizing and minimizing versions of */
  OP_CRMINSTAR,      /* 48 all these opcodes must come in pairs, with */
  OP_CRPLUS,         /* 49 the minimizing one second. These codes must */
  OP_CRMINPLUS,      /* 50 be in exactly the same order as those above. */
  OP_CRQUERY,        /* 51 These are for character classes and back refs */
  OP_CRMINQUERY,     /* 52 */
  OP_CRRANGE,        /* 53 These are different to the three seta above. */
  OP_CRMINRANGE,     /* 54 */

  OP_CLASS,          /* 55 Match a character class, chars < 256 only */
  OP_NCLASS,         /* 56 Same, but the bitmap was created from a negative
                           class - the difference is relevant only when a UTF-8
                           character > 255 is encountered. */

  OP_XCLASS,         /* 57 Extended class for handling UTF-8 chars within the
                           class. This does both positive and negative. */

  OP_REF,            /* 58 Match a back reference */
  OP_RECURSE,        /* 59 Match a numbered subpattern (possibly recursive) */
  OP_CALLOUT,        /* 60 Call out to external function if provided */

  OP_ALT,            /* 61 Start of alternation */
  OP_KET,            /* 62 End of group that doesn't have an unbounded repeat */
  OP_KETRMAX,        /* 63 These two must remain together and in this */
  OP_KETRMIN,        /* 64 order. They are for groups the repeat for ever. */

  /* The assertions must come before ONCE and COND */

  OP_ASSERT,         /* 65 Positive lookahead */
  OP_ASSERT_NOT,     /* 66 Negative lookahead */
  OP_ASSERTBACK,     /* 67 Positive lookbehind */
  OP_ASSERTBACK_NOT, /* 68 Negative lookbehind */
  OP_REVERSE,        /* 69 Move pointer back - used in lookbehind assertions */

  /* ONCE and COND must come after the assertions, with ONCE first, as there's
  a test for >= ONCE for a subpattern that isn't an assertion. */

  OP_ONCE,           /* 70 Once matched, don't back up into the subpattern */
  OP_COND,           /* 71 Conditional group */
  OP_CREF,           /* 72 Used to hold an extraction string number (cond ref) */

  OP_BRAZERO,        /* 73 These two must remain together and in this */
  OP_BRAMINZERO,     /* 74 order. */

  OP_BRANUMBER,      /* 75 Used for extracting brackets whose number is greater
                           than can fit into an opcode. */

  OP_BRA             /* 76 This and greater values are used for brackets that
                           extract substrings up to a basic limit. After that,
                           use is made of OP_BRANUMBER. */
};

/* WARNING: There is an implicit assumption in study.c that all opcodes are
less than 128 in value. This makes handling UTF-8 character sequences easier.
*/


/* This macro defines textual names for all the opcodes. There are used only
for debugging, in pcre.c when DEBUG is defined, and also in pcretest.c. The
macro is referenced only in printint.c. */

#define OP_NAME_LIST \
  "End", "\\A", "\\G", "\\B", "\\b", "\\D", "\\d",                \
  "\\S", "\\s", "\\W", "\\w", "Any", "Anybyte", "\\Z", "\\z",     \
  "Opt", "^", "$", "chars", "not",                                \
  "*", "*?", "+", "+?", "?", "??", "{", "{", "{",                 \
  "*", "*?", "+", "+?", "?", "??", "{", "{", "{",                 \
  "*", "*?", "+", "+?", "?", "??", "{", "{", "{",                 \
  "*", "*?", "+", "+?", "?", "??", "{", "{",                      \
  "class", "nclass", "xclass", "Ref", "Recurse", "Callout",       \
  "Alt", "Ket", "KetRmax", "KetRmin", "Assert", "Assert not",     \
  "AssertB", "AssertB not", "Reverse", "Once", "Cond", "Cond ref",\
  "Brazero", "Braminzero", "Branumber", "Bra"


/* This macro defines the length of fixed length operations in the compiled
regex. The lengths are used when searching for specific things, and also in the
debugging printing of a compiled regex. We use a macro so that it can be
incorporated both into pcre.c and pcretest.c without being publicly exposed.

As things have been extended, some of these are no longer fixed lenths, but are
minima instead. For example, the length of a single-character repeat may vary
in UTF-8 mode. The code that uses this table must know about such things. */

#define OP_LENGTHS \
  1,                             /* End                                    */ \
  1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* \A, \G, \B, \B, \D, \d, \S, \s, \W, \w */ \
  1, 1, 1, 1, 2, 1, 1,           /* Any, Anybyte, \Z, \z, Opt, ^, $        */ \
  2,                             /* Chars - the minimum length             */ \
  2,                             /* not                                    */ \
  /* Positive single-char repeats                            ** These are  */ \
  2, 2, 2, 2, 2, 2,              /* *, *?, +, +?, ?, ??      ** minima in  */ \
  4, 4, 4,                       /* upto, minupto, exact     ** UTF-8 mode */ \
  /* Negative single-char repeats - only for chars < 256                   */ \
  2, 2, 2, 2, 2, 2,              /* NOT *, *?, +, +?, ?, ??                */ \
  4, 4, 4,                       /* NOT upto, minupto, exact               */ \
  /* Positive type repeats                                                 */ \
  2, 2, 2, 2, 2, 2,              /* Type *, *?, +, +?, ?, ??               */ \
  4, 4, 4,                       /* Type upto, minupto, exact              */ \
  /* Character class & ref repeats                                         */ \
  1, 1, 1, 1, 1, 1,              /* *, *?, +, +?, ?, ??                    */ \
  5, 5,                          /* CRRANGE, CRMINRANGE                    */ \
 33,                             /* CLASS                                  */ \
 33,                             /* NCLASS                                 */ \
  0,                             /* XCLASS - variable length               */ \
  3,                             /* REF                                    */ \
  1+LINK_SIZE,                   /* RECURSE                                */ \
  2,                             /* CALLOUT                                */ \
  1+LINK_SIZE,                   /* Alt                                    */ \
  1+LINK_SIZE,                   /* Ket                                    */ \
  1+LINK_SIZE,                   /* KetRmax                                */ \
  1+LINK_SIZE,                   /* KetRmin                                */ \
  1+LINK_SIZE,                   /* Assert                                 */ \
  1+LINK_SIZE,                   /* Assert not                             */ \
  1+LINK_SIZE,                   /* Assert behind                          */ \
  1+LINK_SIZE,                   /* Assert behind not                      */ \
  1+LINK_SIZE,                   /* Reverse                                */ \
  1+LINK_SIZE,                   /* Once                                   */ \
  1+LINK_SIZE,                   /* COND                                   */ \
  3,                             /* CREF                                   */ \
  1, 1,                          /* BRAZERO, BRAMINZERO                    */ \
  3,                             /* BRANUMBER                              */ \
  1+LINK_SIZE                    /* BRA                                    */ \


/* The highest extraction number before we have to start using additional
bytes. (Originally PCRE didn't have support for extraction counts highter than
this number.) The value is limited by the number of opcodes left after OP_BRA,
i.e. 255 - OP_BRA. We actually set it a bit lower to leave room for additional
opcodes. */

#define EXTRACT_BASIC_MAX  150

/* A magic value for OP_CREF to indicate the "in recursion" condition. */

#define CREF_RECURSE  0xffff

/* The texts of compile-time error messages are defined as macros here so that
they can be accessed by the POSIX wrapper and converted into error codes.  Yes,
I could have used error codes in the first place, but didn't feel like changing
just to accommodate the POSIX wrapper. */

#define ERR1  "\\ at end of pattern"
#define ERR2  "\\c at end of pattern"
#define ERR3  "unrecognized character follows \\"
#define ERR4  "numbers out of order in {} quantifier"
#define ERR5  "number too big in {} quantifier"
#define ERR6  "missing terminating ] for character class"
#define ERR7  "invalid escape sequence in character class"
#define ERR8  "range out of order in character class"
#define ERR9  "nothing to repeat"
#define ERR10 "operand of unlimited repeat could match the empty string"
#define ERR11 "internal error: unexpected repeat"
#define ERR12 "unrecognized character after (?"
#define ERR13 "POSIX named classes are supported only within a class"
#define ERR14 "missing )"
#define ERR15 "reference to non-existent subpattern"
#define ERR16 "erroffset passed as NULL"
#define ERR17 "unknown option bit(s) set"
#define ERR18 "missing ) after comment"
#define ERR19 "parentheses nested too deeply"
#define ERR20 "regular expression too large"
#define ERR21 "failed to get memory"
#define ERR22 "unmatched parentheses"
#define ERR23 "internal error: code overflow"
#define ERR24 "unrecognized character after (?<"
#define ERR25 "lookbehind assertion is not fixed length"
#define ERR26 "malformed number after (?("
#define ERR27 "conditional group contains more than two branches"
#define ERR28 "assertion expected after (?("
#define ERR29 "(?R or (?digits must be followed by )"
#define ERR30 "unknown POSIX class name"
#define ERR31 "POSIX collating elements are not supported"
#define ERR32 "this version of PCRE is not compiled with PCRE_UTF8 support"
#define ERR33 "spare error"
#define ERR34 "character value in \\x{...} sequence is too large"
#define ERR35 "invalid condition (?(0)"
#define ERR36 "\\C not allowed in lookbehind assertion"
#define ERR37 "PCRE does not support \\L, \\l, \\N, \\P, \\p, \\U, \\u, or \\X"
#define ERR38 "number after (?C is > 255"
#define ERR39 "closing ) for (?C expected"
#define ERR40 "recursive call could loop indefinitely"
#define ERR41 "unrecognized character after (?P"
#define ERR42 "syntax error after (?P"
#define ERR43 "two named groups have the same name"
#define ERR44 "invalid UTF-8 string"

/* All character handling must be done as unsigned characters. Otherwise there
are problems with top-bit-set characters and functions such as isspace().
However, we leave the interface to the outside world as char *, because that
should make things easier for callers. We define a short type for unsigned char
to save lots of typing. I tried "uchar", but it causes problems on Digital
Unix, where it is defined in sys/types, so use "uschar" instead. */

typedef unsigned char uschar;

/* The real format of the start of the pcre block; the index of names and the
code vector run on as long as necessary after the end. */

typedef struct real_pcre {
  unsigned long int magic_number;
  size_t size;                        /* Total that was malloced */
  const unsigned char *tables;        /* Pointer to tables */
  unsigned long int options;
  unsigned short int top_bracket;
  unsigned short int top_backref;
  unsigned short int first_byte;
  unsigned short int req_byte;
  unsigned short int name_entry_size; /* Size of any name items; 0 => none */
  unsigned short int name_count;      /* Number of name items */
} real_pcre;

/* The format of the block used to store data from pcre_study(). */

typedef struct pcre_study_data {
  size_t size;                        /* Total that was malloced */
  uschar options;
  uschar start_bits[32];
} pcre_study_data;

/* Structure for passing "static" information around between the functions
doing the compiling, so that they are thread-safe. */

typedef struct compile_data {
  const uschar *lcc;            /* Points to lower casing table */
  const uschar *fcc;            /* Points to case-flipping table */
  const uschar *cbits;          /* Points to character type table */
  const uschar *ctypes;         /* Points to table of type maps */
  const uschar *start_code;     /* The start of the compiled code */
  uschar *name_table;           /* The name/number table */
  int  names_found;             /* Number of entries so far */
  int  name_entry_size;         /* Size of each entry */
  int  top_backref;             /* Maximum back reference */
  unsigned int backref_map;     /* Bitmap of low back refs */
  int  req_varyopt;             /* "After variable item" flag for reqbyte */
} compile_data;

/* Structure for maintaining a chain of pointers to the currently incomplete
branches, for testing for left recursion. */

typedef struct branch_chain {
  struct branch_chain *outer;
  uschar *current;
} branch_chain;

/* Structure for items in a linked list that represents an explicit recursive
call within the pattern. */

typedef struct recursion_info {
  struct recursion_info *prevrec; /* Previous recursion record (or NULL) */
  int group_num;                /* Number of group that was called */
  const uschar *after_call;     /* "Return value": points after the call in the expr */
  const uschar *save_start;     /* Old value of md->start_match */
  int *offset_save;             /* Pointer to start of saved offsets */
  int saved_max;                /* Number of saved offsets */
} recursion_info;

/* When compiling in a mode that doesn't use recursive calls to match(),
a structure is used to remember local variables on the heap. It is defined in
pcre.c, close to the match() function, so that it is easy to keep it in step
with any changes of local variable. However, the pointer to the current frame
must be saved in some "static" place over a longjmp(). We declare the
structure here so that we can put a pointer in the match_data structure.
NOTE: This isn't used for a "normal" compilation of pcre. */

/* Structure for passing "static" information around between the functions
doing the matching, so that they are thread-safe. */

typedef struct match_data {
  unsigned long int match_call_count; /* As it says */
  unsigned long int match_limit;/* As it says */
  int   *offset_vector;         /* Offset vector */
  int    offset_end;            /* One past the end */
  int    offset_max;            /* The maximum usable for return data */
  const uschar *lcc;            /* Points to lower casing table */
  const uschar *ctypes;         /* Points to table of type maps */
  bool   offset_overflow;       /* Set if too many extractions */
  bool   notbol;                /* NOTBOL flag */
  bool   noteol;                /* NOTEOL flag */
  bool   utf8;                  /* UTF8 flag */
  bool   endonly;               /* Dollar not before final \n */
  bool   notempty;              /* Empty string match not wanted */
  const uschar *start_code;     /* For use when recursing */
  const uschar *start_subject;  /* Start of the subject string */
  const uschar *end_subject;    /* End of the subject string */
  const uschar *start_match;    /* Start of this match attempt */
  const uschar *end_match_ptr;  /* Subject position at end match */
  int    end_offset_top;        /* Highwater mark at end of match */
  int    capture_last;          /* Most recent capture number */
  int    start_offset;          /* The start offset value */
  recursion_info *recursive;    /* Linked list of recursion data */
  void  *callout_data;          /* To pass back to callouts */
} match_data;

/* Bit definitions for entries in the pcre_ctypes table. */

#define ctype_space   0x01
#define ctype_letter  0x02
#define ctype_digit   0x04
#define ctype_xdigit  0x08
#define ctype_word    0x10   /* alphameric or '_' */
#define ctype_meta    0x80   /* regexp meta char or zero (end pattern) */

/* Offsets for the bitmap tables in pcre_cbits. Each table contains a set
of bits for a class map. Some classes are built by combining these tables. */

#define cbit_space     0      /* [:space:] or \s */
#define cbit_xdigit   32      /* [:xdigit:] */
#define cbit_digit    64      /* [:digit:] or \d */
#define cbit_upper    96      /* [:upper:] */
#define cbit_lower   128      /* [:lower:] */
#define cbit_word    160      /* [:word:] or \w */
#define cbit_graph   192      /* [:graph:] */
#define cbit_print   224      /* [:print:] */
#define cbit_punct   256      /* [:punct:] */
#define cbit_cntrl   288      /* [:cntrl:] */
#define cbit_length  320      /* Length of the cbits table */

/* Offsets of the various tables from the base tables pointer, and
total length. */

#define lcc_offset      0
#define fcc_offset    256
#define cbits_offset  512
#define ctypes_offset (cbits_offset + cbit_length)
#define tables_length (ctypes_offset + 256)

/* End of internal.h */
/* chartables.c */
/*************************************************
*      Perl-Compatible Regular Expressions       *
*************************************************/

/* This file is automatically written by the dftables auxiliary
program. If you edit it by hand, you might like to edit the Makefile to
prevent its ever being regenerated.

This file is #included in the compilation of pcre.c to build the default
character tables which are used when no tables are passed to the compile
function. */

static unsigned char pcre_default_tables[] = {

/* This table is a lower casing table. */

    0,  1,  2,  3,  4,  5,  6,  7,
    8,  9, 10, 11, 12, 13, 14, 15,
   16, 17, 18, 19, 20, 21, 22, 23,
   24, 25, 26, 27, 28, 29, 30, 31,
   32, 33, 34, 35, 36, 37, 38, 39,
   40, 41, 42, 43, 44, 45, 46, 47,
   48, 49, 50, 51, 52, 53, 54, 55,
   56, 57, 58, 59, 60, 61, 62, 63,
   64, 97, 98, 99,100,101,102,103,
  104,105,106,107,108,109,110,111,
  112,113,114,115,116,117,118,119,
  120,121,122, 91, 92, 93, 94, 95,
   96, 97, 98, 99,100,101,102,103,
  104,105,106,107,108,109,110,111,
  112,113,114,115,116,117,118,119,
  120,121,122,123,124,125,126,127,
  128,129,130,131,132,133,134,135,
  136,137,138,139,140,141,142,143,
  144,145,146,147,148,149,150,151,
  152,153,154,155,156,157,158,159,
  160,161,162,163,164,165,166,167,
  168,169,170,171,172,173,174,175,
  176,177,178,179,180,181,182,183,
  184,185,186,187,188,189,190,191,
  192,193,194,195,196,197,198,199,
  200,201,202,203,204,205,206,207,
  208,209,210,211,212,213,214,215,
  216,217,218,219,220,221,222,223,
  224,225,226,227,228,229,230,231,
  232,233,234,235,236,237,238,239,
  240,241,242,243,244,245,246,247,
  248,249,250,251,252,253,254,255,

/* This table is a case flipping table. */

    0,  1,  2,  3,  4,  5,  6,  7,
    8,  9, 10, 11, 12, 13, 14, 15,
   16, 17, 18, 19, 20, 21, 22, 23,
   24, 25, 26, 27, 28, 29, 30, 31,
   32, 33, 34, 35, 36, 37, 38, 39,
   40, 41, 42, 43, 44, 45, 46, 47,
   48, 49, 50, 51, 52, 53, 54, 55,
   56, 57, 58, 59, 60, 61, 62, 63,
   64, 97, 98, 99,100,101,102,103,
  104,105,106,107,108,109,110,111,
  112,113,114,115,116,117,118,119,
  120,121,122, 91, 92, 93, 94, 95,
   96, 65, 66, 67, 68, 69, 70, 71,
   72, 73, 74, 75, 76, 77, 78, 79,
   80, 81, 82, 83, 84, 85, 86, 87,
   88, 89, 90,123,124,125,126,127,
  128,129,130,131,132,133,134,135,
  136,137,138,139,140,141,142,143,
  144,145,146,147,148,149,150,151,
  152,153,154,155,156,157,158,159,
  160,161,162,163,164,165,166,167,
  168,169,170,171,172,173,174,175,
  176,177,178,179,180,181,182,183,
  184,185,186,187,188,189,190,191,
  192,193,194,195,196,197,198,199,
  200,201,202,203,204,205,206,207,
  208,209,210,211,212,213,214,215,
  216,217,218,219,220,221,222,223,
  224,225,226,227,228,229,230,231,
  232,233,234,235,236,237,238,239,
  240,241,242,243,244,245,246,247,
  248,249,250,251,252,253,254,255,

/* This table contains bit maps for various character classes.
Each map is 32 bytes long and the bits run from the least
significant end of each byte. The classes that have their own
maps are: space, xdigit, digit, upper, lower, word, graph
print, punct, and cntrl. Other classes are built from combinations. */

  0x00,0x3e,0x00,0x00,0x01,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0x00,0x00,0xff,0x03,
  0x7e,0x00,0x00,0x00,0x7e,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0x00,0x00,0xff,0x03,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0xfe,0xff,0xff,0x07,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0xfe,0xff,0xff,0x07,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0x00,0x00,0xff,0x03,
  0xfe,0xff,0xff,0x87,0xfe,0xff,0xff,0x07,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0xfe,0xff,0xff,0xff,
  0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x7f,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0xff,0xff,0xff,0xff,
  0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x7f,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0x00,0x00,0x00,0x00,0xfe,0xff,0x00,0xfc,
  0x01,0x00,0x00,0xf8,0x01,0x00,0x00,0x78,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

  0xff,0xff,0xff,0xff,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

/* This table identifies various classes of character by individual bits:
  0x01   white space character
  0x02   letter
  0x04   decimal digit
  0x08   hexadecimal digit
  0x10   alphanumeric or '_'
  0x80   regular expression metacharacter or binary zero
*/

  0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   0-  7 */
  0x00,0x01,0x01,0x00,0x01,0x01,0x00,0x00, /*   8- 15 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  16- 23 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  24- 31 */
  0x01,0x00,0x00,0x00,0x80,0x00,0x00,0x00, /*    - '  */
  0x80,0x80,0x80,0x80,0x00,0x00,0x80,0x00, /*  ( - /  */
  0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c,0x1c, /*  0 - 7  */
  0x1c,0x1c,0x00,0x00,0x00,0x00,0x00,0x80, /*  8 - ?  */
  0x00,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /*  @ - G  */
  0x12,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /*  H - O  */
  0x12,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /*  P - W  */
  0x12,0x12,0x12,0x80,0x00,0x00,0x80,0x10, /*  X - _  */
  0x00,0x1a,0x1a,0x1a,0x1a,0x1a,0x1a,0x12, /*  ` - g  */
  0x12,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /*  h - o  */
  0x12,0x12,0x12,0x12,0x12,0x12,0x12,0x12, /*  p - w  */
  0x12,0x12,0x12,0x80,0x80,0x00,0x00,0x00, /*  x -127 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 128-135 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 136-143 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 144-151 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 152-159 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 160-167 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 168-175 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 176-183 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 192-199 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 200-207 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 208-215 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 216-223 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 224-231 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 232-239 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 240-247 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};/* 248-255 */

/* End of chartables.c */
/* get.c */
/*************************************************
*      Copy captured string to given buffer      *
*************************************************/

/* This function copies a single captured substring into a given buffer.
Note that we use memcpy() rather than strncpy() in case there are binary zeros
in the string.

Arguments:
  subject        the subject string that was matched
  ovector        pointer to the offsets table
  stringcount    the number of substrings that were captured
                   (i.e. the yield of the pcre_exec call, unless
                   that was zero, in which case it should be 1/3
                   of the offset table size)
  stringnumber   the number of the required substring
  buffer         where to put the substring
  size           the size of the buffer

Returns:         if successful:
                   the length of the copied string, not including the zero
                   that is put on the end; can be zero
                 if not successful:
                   PCRE_ERROR_NOMEMORY (-6) buffer too small
                   PCRE_ERROR_NOSUBSTRING (-7) no such captured substring
*/

int
pcre_copy_substring(const char *subject, int *ovector, int stringcount,
  int stringnumber, char *buffer, int size)
{
int yield;
if (stringnumber < 0 || stringnumber >= stringcount)
  return PCRE_ERROR_NOSUBSTRING;
stringnumber *= 2;
yield = ovector[stringnumber+1] - ovector[stringnumber];
if (size < yield + 1) return PCRE_ERROR_NOMEMORY;
memcpy(buffer, subject + ovector[stringnumber], yield);
buffer[yield] = 0;
return yield;
}

/* End of get.c */
/* maketables.c */
/*************************************************
*           Create PCRE character tables         *
*************************************************/

/* This function builds a set of character tables for use by PCRE and returns
a pointer to them. They are build using the ctype functions, and consequently
their contents will depend upon the current locale setting. When compiled as
part of the library, the store is obtained via malloc(), but when compiled
inside dftables, use malloc().

Arguments:   none
Returns:     pointer to the contiguous block of data
*/

const unsigned char *
pcre_maketables(void)
{
    unsigned char *yield, *p;
    int i;

    yield = static_cast<unsigned char*>(malloc(tables_length));

    if (yield == NULL) return NULL;
    p = yield;

    /* First comes the lower casing table */

    for (i = 0; i < 256; i++)
    {
        *p++ = mux_tolower(i);
    }

    /* Next the case-flipping table */

    for (i = 0; i < 256; i++)
    {
        *p++ = mux_islower(i)? mux_toupper(i) : mux_tolower(i);
    }

    /* Then the character class tables. Don't try to be clever and save effort
    on exclusive ones - in some locales things may be different. Note that the
    table for "space" includes everything "isspace" gives, including VT in the
    default locale. This makes it work for the POSIX class [:space:]. */

    memset(p, 0, cbit_length);
    for (i = 0; i < 256; i++)
    {
        if (mux_isdigit(i))
        {
            p[cbit_digit  + i/8] |= 1 << (i&7);
            p[cbit_word   + i/8] |= 1 << (i&7);
        }
        if (mux_isupper(i))
        {
            p[cbit_upper  + i/8] |= 1 << (i&7);
            p[cbit_word   + i/8] |= 1 << (i&7);
        }
        if (mux_islower(i))
        {
            p[cbit_lower  + i/8] |= 1 << (i&7);
            p[cbit_word   + i/8] |= 1 << (i&7);
        }
        if (i == '_')       p[cbit_word   + i/8] |= 1 << (i&7);
        if (mux_isspace(i)) p[cbit_space  + i/8] |= 1 << (i&7);
        if (mux_isxdigit(i))p[cbit_xdigit + i/8] |= 1 << (i&7);
        if (isgraph(i))     p[cbit_graph  + i/8] |= 1 << (i&7);
        if (mux_isprint(i)) p[cbit_print  + i/8] |= 1 << (i&7);
        if (ispunct(i))     p[cbit_punct  + i/8] |= 1 << (i&7);
        if (iscntrl(i))     p[cbit_cntrl  + i/8] |= 1 << (i&7);
    }
    p += cbit_length;

    /* Finally, the character type table. In this, we exclude VT from the white
    space chars, because Perl doesn't recognize it as such for \s and for comments
    within regexes. */

    for (i = 0; i < 256; i++)
    {
        unsigned char x = 0;
        if (i != 0x0b && mux_isspace(i)) x += ctype_space;
        if (mux_isalpha(i)) x += ctype_letter;
        if (mux_isdigit(i)) x += ctype_digit;
        if (mux_isxdigit(i)) x += ctype_xdigit;
        if (mux_isalnum(i) || i == '_') x += ctype_word;
        if (strchr("*+?{^.$|()[", i) != 0) x += ctype_meta;
        *p++ = x;
    }
    return yield;
}

/* End of maketables.c */
/* study.c */

/*************************************************
*      Set a bit and maybe its alternate case    *
*************************************************/

/* Given a character, set its bit in the table, and also the bit for the other
version of a letter if we are caseless.

Arguments:
  start_bits    points to the bit map
  c             is the character
  caseless      the caseless flag
  cd            the block with char table pointers

Returns:        nothing
*/

static void
set_bit(uschar *start_bits, int c, bool caseless, compile_data *cd)
{
start_bits[c/8] |= (1 << (c&7));
if (caseless && (cd->ctypes[c] & ctype_letter) != 0)
  start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7));
}



/*************************************************
*          Create bitmap of starting chars       *
*************************************************/

/* This function scans a compiled unanchored expression and attempts to build a
bitmap of the set of initial characters. If it can't, it returns false. As time
goes by, we may be able to get more clever at doing this.

Arguments:
  code         points to an expression
  start_bits   points to a 32-byte table, initialized to 0
  caseless     the current state of the caseless flag
  utf8         true if in UTF-8 mode
  cd           the block with char table pointers

Returns:       true if table built, false otherwise
*/

static bool
set_start_bits(const uschar *code, uschar *start_bits, bool caseless,
  bool utf8, compile_data *cd)
{
register int c;

/* This next statement and the later reference to dummy are here in order to
trick the optimizer of the IBM C compiler for OS/2 into generating correct
code. Apparently IBM isn't going to fix the problem, and we would rather not
disable optimization (in this module it actually makes a big difference, and
the pcre module can use all the optimization it can get). */

volatile int dummy;

do
  {
  const uschar *tcode = code + 1 + LINK_SIZE;
  bool try_next = true;

  while (try_next)
    {
    /* If a branch starts with a bracket or a positive lookahead assertion,
    recurse to set bits from within them. That's all for this branch. */

    if ((int)*tcode >= OP_BRA || *tcode == OP_ASSERT)
      {
      if (!set_start_bits(tcode, start_bits, caseless, utf8, cd))
        return false;
      try_next = false;
      }

    else switch(*tcode)
      {
      default:
      return false;

      /* Skip over callout */

      case OP_CALLOUT:
      tcode += 2;
      break;

      /* Skip over extended extraction bracket number */

      case OP_BRANUMBER:
      tcode += 3;
      break;

      /* Skip over lookbehind and negative lookahead assertions */

      case OP_ASSERT_NOT:
      case OP_ASSERTBACK:
      case OP_ASSERTBACK_NOT:
      do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
      tcode += 1+LINK_SIZE;
      break;

      /* Skip over an option setting, changing the caseless flag */

      case OP_OPT:
      caseless = (tcode[1] & PCRE_CASELESS) != 0;
      tcode += 2;
      break;

      /* BRAZERO does the bracket, but carries on. */

      case OP_BRAZERO:
      case OP_BRAMINZERO:
      if (!set_start_bits(++tcode, start_bits, caseless, utf8, cd))
        return false;
      dummy = 1;
      do tcode += GET(tcode,1); while (*tcode == OP_ALT);
      tcode += 1+LINK_SIZE;
      break;

      /* Single-char * or ? sets the bit and tries the next item */

      case OP_STAR:
      case OP_MINSTAR:
      case OP_QUERY:
      case OP_MINQUERY:
      set_bit(start_bits, tcode[1], caseless, cd);
      tcode += 2;
      break;

      /* Single-char upto sets the bit and tries the next */

      case OP_UPTO:
      case OP_MINUPTO:
      set_bit(start_bits, tcode[3], caseless, cd);
      tcode += 4;
      break;

      /* At least one single char sets the bit and stops */

      case OP_EXACT:       /* Fall through */
      tcode++;

      case OP_CHARS:       /* Fall through */
      tcode++;

      case OP_PLUS:
      case OP_MINPLUS:
      set_bit(start_bits, tcode[1], caseless, cd);
      try_next = false;
      break;

      /* Single character type sets the bits and stops */

      case OP_NOT_DIGIT:
      for (c = 0; c < 32; c++)
        start_bits[c] |= ~cd->cbits[c+cbit_digit];
      try_next = false;
      break;

      case OP_DIGIT:
      for (c = 0; c < 32; c++)
        start_bits[c] |= cd->cbits[c+cbit_digit];
      try_next = false;
      break;

      case OP_NOT_WHITESPACE:
      for (c = 0; c < 32; c++)
        start_bits[c] |= ~cd->cbits[c+cbit_space];
      try_next = false;
      break;

      case OP_WHITESPACE:
      for (c = 0; c < 32; c++)
        start_bits[c] |= cd->cbits[c+cbit_space];
      try_next = false;
      break;

      case OP_NOT_WORDCHAR:
      for (c = 0; c < 32; c++)
        start_bits[c] |= ~cd->cbits[c+cbit_word];
      try_next = false;
      break;

      case OP_WORDCHAR:
      for (c = 0; c < 32; c++)
        start_bits[c] |= cd->cbits[c+cbit_word];
      try_next = false;
      break;

      /* One or more character type fudges the pointer and restarts, knowing
      it will hit a single character type and stop there. */

      case OP_TYPEPLUS:
      case OP_TYPEMINPLUS:
      tcode++;
      break;

      case OP_TYPEEXACT:
      tcode += 3;
      break;

      /* Zero or more repeats of character types set the bits and then
      try again. */

      case OP_TYPEUPTO:
      case OP_TYPEMINUPTO:
      tcode += 2;               /* Fall through */

      case OP_TYPESTAR:
      case OP_TYPEMINSTAR:
      case OP_TYPEQUERY:
      case OP_TYPEMINQUERY:
      switch(tcode[1])
        {
        case OP_NOT_DIGIT:
        for (c = 0; c < 32; c++)
          start_bits[c] |= ~cd->cbits[c+cbit_digit];
        break;

        case OP_DIGIT:
        for (c = 0; c < 32; c++)
          start_bits[c] |= cd->cbits[c+cbit_digit];
        break;

        case OP_NOT_WHITESPACE:
        for (c = 0; c < 32; c++)
          start_bits[c] |= ~cd->cbits[c+cbit_space];
        break;

        case OP_WHITESPACE:
        for (c = 0; c < 32; c++)
          start_bits[c] |= cd->cbits[c+cbit_space];
        break;

        case OP_NOT_WORDCHAR:
        for (c = 0; c < 32; c++)
          start_bits[c] |= ~cd->cbits[c+cbit_word];
        break;

        case OP_WORDCHAR:
        for (c = 0; c < 32; c++)
          start_bits[c] |= cd->cbits[c+cbit_word];
        break;
        }

      tcode += 2;
      break;

      /* Character class where all the information is in a bit map: set the
      bits and either carry on or not, according to the repeat count. If it was
      a negative class, and we are operating with UTF-8 characters, any byte
      with the top-bit set is a potentially valid starter because it may start
      a character with a value > 255. (This is sub-optimal in that the
      character may be in the range 128-255, and those characters might be
      unwanted, but that's as far as we go for the moment.) */

      case OP_NCLASS:
      if (utf8) memset(start_bits+16, 0xff, 16);
      /* Fall through */

      case OP_CLASS:
        {
        tcode++;
        for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
        tcode += 32;
        switch (*tcode)
          {
          case OP_CRSTAR:
          case OP_CRMINSTAR:
          case OP_CRQUERY:
          case OP_CRMINQUERY:
          tcode++;
          break;

          case OP_CRRANGE:
          case OP_CRMINRANGE:
          if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
            else try_next = false;
          break;

          default:
          try_next = false;
          break;
          }
        }
      break; /* End of bitmap class handling */

      }      /* End of switch */
    }        /* End of try_next loop */

  code += GET(code, 1);   /* Advance to next branch */
  }
while (*code == OP_ALT);
return true;
}



/*************************************************
*          Study a compiled expression           *
*************************************************/

/* This function is handed a compiled expression that it must study to produce
information that will speed up the matching. It returns a pcre_extra block
which then gets handed back to pcre_exec().

Arguments:
  re        points to the compiled expression
  options   contains option bits
  errorptr  points to where to place error messages;
            set NULL unless error

Returns:    pointer to a pcre_extra block, with study_data filled in and the
              appropriate flag set;
            NULL on error or if no optimization possible
*/

pcre_extra *
pcre_study(const pcre *external_re, int options, const char **errorptr)
{
uschar start_bits[32];
pcre_extra *extra;
pcre_study_data *study;
const real_pcre *re = (const real_pcre *)external_re;
uschar *code = (uschar *)re + sizeof(real_pcre) +
  (re->name_count * re->name_entry_size);
compile_data compile_block;

*errorptr = NULL;

if (re == NULL || re->magic_number != MAGIC_NUMBER)
  {
  *errorptr = "argument is not a compiled regular expression";
  return NULL;
  }

if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
  {
  *errorptr = "unknown or incorrect option bit(s) set";
  return NULL;
  }

/* For an anchored pattern, or an unanchored pattern that has a first char, or
a multiline pattern that matches only at "line starts", no further processing
at present. */

if ((re->options & (PCRE_ANCHORED|PCRE_FIRSTSET|PCRE_STARTLINE)) != 0)
  return NULL;

/* Set the character tables in the block which is passed around */

compile_block.lcc = re->tables + lcc_offset;
compile_block.fcc = re->tables + fcc_offset;
compile_block.cbits = re->tables + cbits_offset;
compile_block.ctypes = re->tables + ctypes_offset;

/* See if we can find a fixed set of initial characters for the pattern. */

memset(start_bits, 0, 32 * sizeof(uschar));
if (!set_start_bits(code, start_bits, (re->options & PCRE_CASELESS) != 0,
  (re->options & PCRE_UTF8) != 0, &compile_block)) return NULL;

/* Get a pcre_extra block and a pcre_study_data block. The study data is put in
the latter, which is pointed to by the former, which may also get additional
data set later by the calling program. At the moment, the size of
pcre_study_data is fixed. We nevertheless save it in a field for returning via
the pcre_fullinfo() function so that if it becomes variable in the future, we
don't have to change that code. */

extra = static_cast<pcre_extra *>(malloc(sizeof(pcre_extra) + sizeof(pcre_study_data)));

if (extra == NULL)
  {
  *errorptr = "failed to get memory";
  return NULL;
  }

// Hmm.
study = reinterpret_cast<pcre_study_data *>(reinterpret_cast<char*>(extra) + sizeof(pcre_extra));
extra->flags = PCRE_EXTRA_STUDY_DATA;
extra->study_data = study;

study->size = sizeof(pcre_study_data);
study->options = PCRE_STUDY_MAPPED;
memcpy(study->start_bits, start_bits, sizeof(start_bits));

return extra;
}

/* End of study.c */
/* pcre.c */
#define DPRINTF(p) /*nothing*/

/* Maximum number of items on the nested bracket stacks at compile time. This
applies to the nesting of all kinds of parentheses. It does not limit
un-nested, non-capturing parentheses. This number can be made bigger if
necessary - it is used to dimension one int and one unsigned char vector at
compile time. */

#define BRASTACK_SIZE 200


/* Maximum number of ints of offset to save on the stack for recursive calls.
If the offset vector is bigger, malloc is used. This should be a multiple of 3,
because the offset vector is always a multiple of 3 long. */

#define REC_STACK_SAVE_MAX 30


/* The number of bytes in a literal character string above which we can't add
any more is set at 250 in order to allow for UTF-8 characters. (In theory it
could be 255 when UTF-8 support is excluded, but that means that some of the
test output would be different, which just complicates things.) */

#define MAXLIT 250


/* The maximum remaining length of subject we are prepared to search for a
req_byte match. */

#define REQ_BYTE_MAX 1000


/* Table of sizes for the fixed-length opcodes. It's defined in a macro so that
the definition is next to the definition of the opcodes in internal.h. */

static const uschar OP_lengths[] = { OP_LENGTHS };

/* Min and max values for the common repeats; for the maxima, 0 => infinity */

static const char rep_min[] = { 0, 0, 1, 1, 0, 0 };
static const char rep_max[] = { 0, 0, 0, 0, 1, 1 };

/* Table for handling escaped characters in the range '0'-'z'. Positive returns
are simple data values; negative values are for special things like \d and so
on. Zero means further processing is needed (for things like \x), or the escape
is invalid. */

static const short int escapes[] = {
    0,      0,      0,      0,      0,      0,      0,      0,   /* 0 - 7 */
    0,      0,    ':',    ';',    '<',    '=',    '>',    '?',   /* 8 - ? */
  '@', -ESC_A, -ESC_B, -ESC_C, -ESC_D, -ESC_E,      0, -ESC_G,   /* @ - G */
    0,      0,      0,      0,      0,      0,      0,      0,   /* H - O */
    0, -ESC_Q,      0, -ESC_S,      0,      0,      0, -ESC_W,   /* P - W */
    0,      0, -ESC_Z,    '[',   '\\',    ']',    '^',    '_',   /* X - _ */
  '`',      7, -ESC_b,      0, -ESC_d,  ESC_e,  ESC_f,      0,   /* ` - g */
    0,      0,      0,      0,      0,      0,  ESC_n,      0,   /* h - o */
    0,      0,  ESC_r, -ESC_s,  ESC_tee,    0,      0, -ESC_w,   /* p - w */
    0,      0, -ESC_z                                            /* x - z */
};

/* Tables of names of POSIX character classes and their lengths. The list is
terminated by a zero length entry. The first three must be alpha, upper, lower,
as this is assumed for handling case independence. */

static const char *const posix_names[] = {
  "alpha", "lower", "upper",
  "alnum", "ascii", "blank", "cntrl", "digit", "graph",
  "print", "punct", "space", "word",  "xdigit" };

static const uschar posix_name_lengths[] = {
  5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 6, 0 };

/* Table of class bit maps for each POSIX class; up to three may be combined
to form the class. The table for [:blank:] is dynamically modified to remove
the vertical space characters. */

static const int posix_class_maps[] = {
  cbit_lower, cbit_upper, -1,             /* alpha */
  cbit_lower, -1,         -1,             /* lower */
  cbit_upper, -1,         -1,             /* upper */
  cbit_digit, cbit_lower, cbit_upper,     /* alnum */
  cbit_print, cbit_cntrl, -1,             /* ascii */
  cbit_space, -1,         -1,             /* blank - a GNU extension */
  cbit_cntrl, -1,         -1,             /* cntrl */
  cbit_digit, -1,         -1,             /* digit */
  cbit_graph, -1,         -1,             /* graph */
  cbit_print, -1,         -1,             /* print */
  cbit_punct, -1,         -1,             /* punct */
  cbit_space, -1,         -1,             /* space */
  cbit_word,  -1,         -1,             /* word - a Perl extension */
  cbit_xdigit,-1,         -1              /* xdigit */
};

/* Table to identify digits and hex digits. This is used when compiling
patterns. Note that the tables in chartables are dependent on the locale, and
may mark arbitrary characters as digits - but the PCRE compiling code expects
to handle only 0-9, a-z, and A-Z as digits when compiling. That is why we have
a private table here. It costs 256 bytes, but it is a lot faster than doing
character value tests (at least in some simple cases I timed), and in some
applications one wants PCRE to compile efficiently as well as match
efficiently.

For convenience, we use the same bit definitions as in chartables:

  0x04   decimal digit
  0x08   hexadecimal digit

Then we can use ctype_digit and ctype_xdigit in the code. */

static const unsigned char digitab[] =
  {
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   0-  7 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*   8- 15 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  16- 23 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  24- 31 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*    - '  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  ( - /  */
  0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c,0x0c, /*  0 - 7  */
  0x0c,0x0c,0x00,0x00,0x00,0x00,0x00,0x00, /*  8 - ?  */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /*  @ - G  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  H - O  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  P - W  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  X - _  */
  0x00,0x08,0x08,0x08,0x08,0x08,0x08,0x00, /*  ` - g  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  h - o  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  p - w  */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /*  x -127 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 128-135 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 136-143 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 144-151 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 152-159 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 160-167 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 168-175 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 176-183 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 184-191 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 192-199 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 200-207 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 208-215 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 216-223 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 224-231 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 232-239 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, /* 240-247 */
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};/* 248-255 */

/* Definition to allow mutual recursion */

static bool
  compile_regex(int, int, int *, uschar **, const uschar **, const char **,
    bool, int, int *, int *, branch_chain *, compile_data *);

/* Structure for building a chain of data that actually lives on the
stack, for holding the values of the subject pointer at the start of each
subpattern, so as to detect when an empty string has been matched by a
subpattern - to break infinite loops. */

typedef struct eptrblock {
  struct eptrblock *epb_prev;
  const uschar *epb_saved_eptr;
} eptrblock;

/* Flag bits for the match() function */

#define match_condassert   0x01    /* Called to check a condition assertion */
#define match_isgroup      0x02    /* Set if start of bracketed group */

/* Non-error returns from the match() function. Error returns are externally
defined PCRE_ERROR_xxx codes, which are all negative. */

#define MATCH_MATCH        1
#define MATCH_NOMATCH      0



/*************************************************
*               Global variables                 *
*************************************************/

/* PCRE is thread-clean and doesn't use any global variables in the normal
sense. However, it calls memory allocation and free functions via the four
indirections below, and it can optionally do callouts. These values can be
changed by the caller, but are shared between all threads. However, when
compiling for Virtual Pascal, things are done differently (see pcre.in). */

static int   (*pcre_callout)(pcre_callout_block *) = NULL;


/*************************************************
*    Macros and tables for character handling    *
*************************************************/

#define GETCHAR(c, eptr) c = *eptr;
#define GETCHARINC(c, eptr) c = *eptr++;
#define GETCHARINCTEST(c, eptr) c = *eptr++;
#define GETCHARLEN(c, eptr, len) c = *eptr;
#define BACKCHAR(eptr)

/*************************************************
*            Handle escapes                      *
*************************************************/

/* This function is called when a \ has been encountered. It either returns a
positive value for a simple escape such as \n, or a negative value which
encodes one of the more complicated things such as \d. When UTF-8 is enabled,
a positive value greater than 255 may be returned. On entry, ptr is pointing at
the \. On exit, it is on the final character of the escape sequence.

Arguments:
  ptrptr     points to the pattern position pointer
  errorptr   points to the pointer to the error message
  bracount   number of previous extracting brackets
  options    the options bits
  isclass    true if inside a character class

Returns:     zero or positive => a data character
             negative => a special escape sequence
             on error, errorptr is set
*/

static int
check_escape(const uschar **ptrptr, const char **errorptr, int bracount,
  int options, bool isclass)
{
const uschar *ptr = *ptrptr;
int c, i;

/* If backslash is at the end of the pattern, it's an error. */

c = *(++ptr);
if (c == 0) *errorptr = ERR1;

/* Non-alphamerics are literals. For digits or letters, do an initial lookup in
a table. A non-zero result is something that can be returned immediately.
Otherwise further processing may be required. */

else if (c < '0' || c > 'z') {}                           /* Not alphameric */
else if ((i = escapes[c - '0']) != 0) c = i;

/* Escapes that need further processing, or are illegal. */

else
  {
  const uschar *oldptr;
  switch (c)
    {
    /* A number of Perl escapes are not handled by PCRE. We give an explicit
    error. */

    case 'l':
    case 'L':
    case 'N':
    case 'p':
    case 'P':
    case 'u':
    case 'U':
    case 'X':
    *errorptr = ERR37;
    break;

    /* The handling of escape sequences consisting of a string of digits
    starting with one that is not zero is not straightforward. By experiment,
    the way Perl works seems to be as follows:

    Outside a character class, the digits are read as a decimal number. If the
    number is less than 10, or if there are that many previous extracting
    left brackets, then it is a back reference. Otherwise, up to three octal
    digits are read to form an escaped byte. Thus \123 is likely to be octal
    123 (cf \0123, which is octal 012 followed by the literal 3). If the octal
    value is greater than 377, the least significant 8 bits are taken. Inside a
    character class, \ followed by a digit is always an octal number. */

    case '1': case '2': case '3': case '4': case '5':
    case '6': case '7': case '8': case '9':

    if (!isclass)
      {
      oldptr = ptr;
      c -= '0';
      while ((digitab[ptr[1]] & ctype_digit) != 0)
        c = c * 10 + *(++ptr) - '0';
      if (c < 10 || c <= bracount)
        {
        c = -(ESC_REF + c);
        break;
        }
      ptr = oldptr;      /* Put the pointer back and fall through */
      }

    /* Handle an octal number following \. If the first digit is 8 or 9, Perl
    generates a binary zero byte and treats the digit as a following literal.
    Thus we have to pull back the pointer by one. */

    if ((c = *ptr) >= '8')
      {
      ptr--;
      c = 0;
      break;
      }

    /* \0 always starts an octal number, but we may drop through to here with a
    larger first octal digit. */

    case '0':
    c -= '0';
    while(i++ < 2 && ptr[1] >= '0' && ptr[1] <= '7')
        c = c * 8 + *(++ptr) - '0';
    c &= 255;     /* Take least significant 8 bits */
    break;

    /* \x is complicated when UTF-8 is enabled. \x{ddd} is a character number
    which can be greater than 0xff, but only if the ddd are hex digits. */

    case 'x':

    /* Read just a single hex char */

    c = 0;
    while (i++ < 2 && (digitab[ptr[1]] & ctype_xdigit) != 0)
      {
      int cc;                               /* Some compilers don't like ++ */
      cc = *(++ptr);                        /* in initializers */
      if (cc >= 'a') cc -= 32;              /* Convert to upper case */
      c = c * 16 + cc - ((cc < 'A')? '0' : ('A' - 10));
      }
    break;

    /* Other special escapes not starting with a digit are straightforward */

    case 'c':
    c = *(++ptr);
    if (c == 0)
      {
      *errorptr = ERR2;
      return 0;
      }

    /* A letter is upper-cased; then the 0x40 bit is flipped. This coding
    is ASCII-specific, but then the whole concept of \cx is ASCII-specific. */

    if (c >= 'a' && c <= 'z') c -= 32;
    c ^= 0x40;
    break;

    /* PCRE_EXTRA enables extensions to Perl in the matter of escapes. Any
    other alphameric following \ is an error if PCRE_EXTRA was set; otherwise,
    for Perl compatibility, it is a literal. This code looks a bit odd, but
    there used to be some cases other than the default, and there may be again
    in future, so I haven't "optimized" it. */

    default:
    if ((options & PCRE_EXTRA) != 0)
      {
      *errorptr = ERR3;
      }
    break;
    }
  }

*ptrptr = ptr;
return c;
}



/*************************************************
*            Check for counted repeat            *
*************************************************/

/* This function is called when a '{' is encountered in a place where it might
start a quantifier. It looks ahead to see if it really is a quantifier or not.
It is only a quantifier if it is one of the forms {ddd} {ddd,} or {ddd,ddd}
where the ddds are digits.

Arguments:
  p         pointer to the first char after '{'

Returns:    true or false
*/

static bool
is_counted_repeat(const uschar *p)
{
if ((digitab[*p++] & ctype_digit) == 0) return false;
while ((digitab[*p] & ctype_digit) != 0) p++;
if (*p == '}') return true;

if (*p++ != ',') return false;
if (*p == '}') return true;

if ((digitab[*p++] & ctype_digit) == 0) return false;
while ((digitab[*p] & ctype_digit) != 0) p++;

return (*p == '}');
}



/*************************************************
*         Read repeat counts                     *
*************************************************/

/* Read an item of the form {n,m} and return the values. This is called only
after is_counted_repeat() has confirmed that a repeat-count quantifier exists,
so the syntax is guaranteed to be correct, but we need to check the values.

Arguments:
  p          pointer to first char after '{'
  minp       pointer to int for min
  maxp       pointer to int for max
             returned as -1 if no max
  errorptr   points to pointer to error message

Returns:     pointer to '}' on success;
             current ptr on error, with errorptr set
*/

static const uschar *
read_repeat_counts(const uschar *p, int *minp, int *maxp, const char **errorptr)
{
int min = 0;
int max = -1;

while ((digitab[*p] & ctype_digit) != 0) min = min * 10 + *p++ - '0';

if (*p == '}') max = min; else
  {
  if (*(++p) != '}')
    {
    max = 0;
    while((digitab[*p] & ctype_digit) != 0) max = max * 10 + *p++ - '0';
    if (max < min)
      {
      *errorptr = ERR4;
      return p;
      }
    }
  }

/* Do paranoid checks, then fill in the required variables, and pass back the
pointer to the terminating '}'. */

if (min < 0 || 65535 < min ||
    max < -1 || 65535 < max)
  *errorptr = ERR5;
else
  {
  *minp = min;
  *maxp = max;
  }
return p;
}



/*************************************************
*      Find first significant op code            *
*************************************************/

/* This is called by several functions that scan a compiled expression looking
for a fixed first character, or an anchoring op code etc. It skips over things
that do not influence this. For some calls, a change of option is important.

Arguments:
  code       pointer to the start of the group
  options    pointer to external options
  optbit     the option bit whose changing is significant, or
               zero if none are

Returns:     pointer to the first significant opcode
*/

static const uschar*
first_significant_code(const uschar *code, int *options, int optbit)
{
for (;;)
  {
  switch ((int)*code)
    {
    case OP_OPT:
    if (optbit > 0 && ((int)code[1] & optbit) != (*options & optbit))
      *options = (int)code[1];
    code += 2;
    break;

    case OP_ASSERT_NOT:
    case OP_ASSERTBACK:
    case OP_ASSERTBACK_NOT:
    do code += GET(code, 1); while (*code == OP_ALT);
    /* Fall through */

    case OP_CALLOUT:
    case OP_CREF:
    case OP_BRANUMBER:
    case OP_WORD_BOUNDARY:
    case OP_NOT_WORD_BOUNDARY:
    code += OP_lengths[*code];
    break;

    default:
    return code;
    }
  }
/* Control never reaches here */
}




/*************************************************
*        Find the fixed length of a pattern      *
*************************************************/

/* Scan a pattern and compute the fixed length of subject that will match it,
if the length is fixed. This is needed for dealing with backward assertions.
In UTF8 mode, the result is in characters rather than bytes.

Arguments:
  code     points to the start of the pattern (the bracket)
  options  the compiling options

Returns:   the fixed length, or -1 if there is no fixed length,
             or -2 if \C was encountered
*/

static int
find_fixedlength(uschar *code, int options)
{
int length = -1;

register int branchlength = 0;
register uschar *cc = code + 1 + LINK_SIZE;

/* Scan along the opcodes for this branch. If we get to the end of the
branch, check the length against that of the other branches. */

for (;;)
  {
  int d;
  register int op = *cc;
  if (op >= OP_BRA) op = OP_BRA;

  switch (op)
    {
    case OP_BRA:
    case OP_ONCE:
    case OP_COND:
    d = find_fixedlength(cc, options);
    if (d < 0) return d;
    branchlength += d;
    do cc += GET(cc, 1); while (*cc == OP_ALT);
    cc += 1 + LINK_SIZE;
    break;

    /* Reached end of a branch; if it's a ket it is the end of a nested
    call. If it's ALT it is an alternation in a nested call. If it is
    END it's the end of the outer call. All can be handled by the same code. */

    case OP_ALT:
    case OP_KET:
    case OP_KETRMAX:
    case OP_KETRMIN:
    case OP_END:
    if (length < 0) length = branchlength;
      else if (length != branchlength) return -1;
    if (*cc != OP_ALT) return length;
    cc += 1 + LINK_SIZE;
    branchlength = 0;
    break;

    /* Skip over assertive subpatterns */

    case OP_ASSERT:
    case OP_ASSERT_NOT:
    case OP_ASSERTBACK:
    case OP_ASSERTBACK_NOT:
    do cc += GET(cc, 1); while (*cc == OP_ALT);
    /* Fall through */

    /* Skip over things that don't match chars */

    case OP_REVERSE:
    case OP_BRANUMBER:
    case OP_CREF:
    case OP_OPT:
    case OP_CALLOUT:
    case OP_SOD:
    case OP_SOM:
    case OP_EOD:
    case OP_EODN:
    case OP_CIRC:
    case OP_DOLL:
    case OP_NOT_WORD_BOUNDARY:
    case OP_WORD_BOUNDARY:
    cc += OP_lengths[*cc];
    break;

    /* Handle char strings. In UTF-8 mode we must count characters, not bytes.
    This requires a scan of the string, unfortunately. We assume valid UTF-8
    strings, so all we do is reduce the length by one for every byte whose bits
    are 10xxxxxx. */

    case OP_CHARS:
    branchlength += *(++cc);
    cc += *cc + 1;
    break;

    /* Handle exact repetitions. The count is already in characters, but we
    need to skip over a multibyte character in UTF8 mode.  */

    case OP_EXACT:
    branchlength += GET2(cc,1);
    cc += 4;
    break;

    case OP_TYPEEXACT:
    branchlength += GET2(cc,1);
    cc += 4;
    break;

    /* Handle single-char matchers */

    case OP_NOT_DIGIT:
    case OP_DIGIT:
    case OP_NOT_WHITESPACE:
    case OP_WHITESPACE:
    case OP_NOT_WORDCHAR:
    case OP_WORDCHAR:
    case OP_ANY:
    branchlength++;
    cc++;
    break;

    /* The single-byte matcher isn't allowed */

    case OP_ANYBYTE:
    return -2;

    /* Check a class for variable quantification */


    case OP_CLASS:
    case OP_NCLASS:
    cc += 33;

    switch (*cc)
      {
      case OP_CRSTAR:
      case OP_CRMINSTAR:
      case OP_CRQUERY:
      case OP_CRMINQUERY:
      return -1;

      case OP_CRRANGE:
      case OP_CRMINRANGE:
      if (GET2(cc,1) != GET2(cc,3)) return -1;
      branchlength += GET2(cc,1);
      cc += 5;
      break;

      default:
      branchlength++;
      }
    break;

    /* Anything else is variable length */

    default:
    return -1;
    }
  }
/* Control never gets here */
}




/*************************************************
*    Scan compiled regex for numbered bracket    *
*************************************************/

/* This little function scans through a compiled pattern until it finds a
capturing bracket with the given number.

Arguments:
  code        points to start of expression
  utf8        true in UTF-8 mode
  number      the required bracket number

Returns:      pointer to the opcode for the bracket, or NULL if not found
*/

static const uschar *
find_bracket(const uschar *code, int number)
{

for (;;)
  {
  register int c = *code;
  if (c == OP_END) return NULL;
  else if (c == OP_CHARS) code += code[1] + OP_lengths[c];
  else if (c > OP_BRA)
    {
    int n = c - OP_BRA;
    if (n > EXTRACT_BASIC_MAX) n = GET2(code, 2+LINK_SIZE);
    if (n == number) return (uschar *)code;
    code += OP_lengths[OP_BRA];
    }
  else
    {
    code += OP_lengths[c];

    }
  }
}



/*************************************************
*   Scan compiled regex for recursion reference  *
*************************************************/

/* This little function scans through a compiled pattern until it finds an
instance of OP_RECURSE.

Arguments:
  code        points to start of expression
  utf8        true in UTF-8 mode

Returns:      pointer to the opcode for OP_RECURSE, or NULL if not found
*/

static const uschar *
find_recurse(const uschar *code, bool utf8)
{
utf8 = utf8;               /* Stop pedantic compilers complaining */

for (;;)
  {
  register int c = *code;
  if (c == OP_END) return NULL;
  else if (c == OP_RECURSE) return code;
  else if (c == OP_CHARS) code += code[1] + OP_lengths[c];
  else if (c > OP_BRA)
    {
    code += OP_lengths[OP_BRA];
    }
  else
    {
    code += OP_lengths[c];

    }
  }
}



/*************************************************
*    Scan compiled branch for non-emptiness      *
*************************************************/

/* This function scans through a branch of a compiled pattern to see whether it
can match the empty string or not. It is called only from could_be_empty()
below. Note that first_significant_code() skips over assertions. If we hit an
unclosed bracket, we return "empty" - this means we've struck an inner bracket
whose current branch will already have been scanned.

Arguments:
  code        points to start of search
  endcode     points to where to stop
  utf8        true if in UTF8 mode

Returns:      true if what is matched could be empty
*/

static bool
could_be_empty_branch(const uschar *code, const uschar *endcode, bool utf8)
{
register int c;
for (code = first_significant_code(code + 1 + LINK_SIZE, NULL, 0);
     code < endcode;
     code = first_significant_code(code + OP_lengths[c], NULL, 0))
  {
  const uschar *ccode;

  c = *code;

  if (c >= OP_BRA)
    {
    bool empty_branch;
    if (GET(code, 1) == 0) return true;    /* Hit unclosed bracket */

    /* Scan a closed bracket */

    empty_branch = false;
    do
      {
      if (!empty_branch && could_be_empty_branch(code, endcode, utf8))
        empty_branch = true;
      code += GET(code, 1);
      }
    while (*code == OP_ALT);
    if (!empty_branch) return false;   /* All branches are non-empty */
    code += 1 + LINK_SIZE;
    c = *code;
    }

  else switch (c)
    {
    /* Check for quantifiers after a class */


    case OP_CLASS:
    case OP_NCLASS:
    ccode = code + 33;


    switch (*ccode)
      {
      case OP_CRSTAR:            /* These could be empty; continue */
      case OP_CRMINSTAR:
      case OP_CRQUERY:
      case OP_CRMINQUERY:
      break;

      default:                   /* Non-repeat => class must match */
      case OP_CRPLUS:            /* These repeats aren't empty */
      case OP_CRMINPLUS:
      return false;

      case OP_CRRANGE:
      case OP_CRMINRANGE:
      if (GET2(ccode, 1) > 0) return false;  /* Minimum > 0 */
      break;
      }
    break;

    /* Opcodes that must match a character */

    case OP_NOT_DIGIT:
    case OP_DIGIT:
    case OP_NOT_WHITESPACE:
    case OP_WHITESPACE:
    case OP_NOT_WORDCHAR:
    case OP_WORDCHAR:
    case OP_ANY:
    case OP_ANYBYTE:
    case OP_CHARS:
    case OP_NOT:
    case OP_PLUS:
    case OP_MINPLUS:
    case OP_EXACT:
    case OP_NOTPLUS:
    case OP_NOTMINPLUS:
    case OP_NOTEXACT:
    case OP_TYPEPLUS:
    case OP_TYPEMINPLUS:
    case OP_TYPEEXACT:
    return false;

    /* End of branch */

    case OP_KET:
    case OP_KETRMAX:
    case OP_KETRMIN:
    case OP_ALT:
    return true;

    }
  }

return true;
}



/*************************************************
*    Scan compiled regex for non-emptiness       *
*************************************************/

/* This function is called to check for left recursive calls. We want to check
the current branch of the current pattern to see if it could match the empty
string. If it could, we must look outwards for branches at other levels,
stopping when we pass beyond the bracket which is the subject of the recursion.

Arguments:
  code        points to start of the recursion
  endcode     points to where to stop (current RECURSE item)
  bcptr       points to the chain of current (unclosed) branch starts
  utf8        true if in UTF-8 mode

Returns:      true if what is matched could be empty
*/

static bool
could_be_empty(const uschar *code, const uschar *endcode, branch_chain *bcptr,
  bool utf8)
{
while (bcptr != NULL && bcptr->current >= code)
  {
  if (!could_be_empty_branch(bcptr->current, endcode, utf8)) return false;
  bcptr = bcptr->outer;
  }
return true;
}



/*************************************************
*           Check for POSIX class syntax         *
*************************************************/

/* This function is called when the sequence "[:" or "[." or "[=" is
encountered in a character class. It checks whether this is followed by an
optional ^ and then a sequence of letters, terminated by a matching ":]" or
".]" or "=]".

Argument:
  ptr      pointer to the initial [
  endptr   where to return the end pointer
  cd       pointer to compile data

Returns:   true or false
*/

static bool
check_posix_syntax(const uschar *ptr, const uschar **endptr, compile_data *cd)
{
int terminator;          /* Don't combine these lines; the Solaris cc */
terminator = *(++ptr);   /* compiler warns about "non-constant" initializer. */
if (*(++ptr) == '^') ptr++;
while ((cd->ctypes[*ptr] & ctype_letter) != 0) ptr++;
if (*ptr == terminator && ptr[1] == ']')
  {
  *endptr = ptr;
  return true;
  }
return false;
}




/*************************************************
*          Check POSIX class name                *
*************************************************/

/* This function is called to check the name given in a POSIX-style class entry
such as [:alnum:].

Arguments:
  ptr        points to the first letter
  len        the length of the name

Returns:     a value representing the name, or -1 if unknown
*/

static int
check_posix_name(const uschar *ptr, int len)
{
register int yield = 0;
while (posix_name_lengths[yield] != 0)
  {
  if (len == posix_name_lengths[yield] &&
    strncmp((const char *)ptr, posix_names[yield], len) == 0) return yield;
  yield++;
  }
return -1;
}


/*************************************************
*    Adjust OP_RECURSE items in repeated group   *
*************************************************/

/* OP_RECURSE items contain an offset from the start of the regex to the group
that is referenced. This means that groups can be replicated for fixed
repetition simply by copying (because the recursion is allowed to refer to
earlier groups that are outside the current group). However, when a group is
optional (i.e. the minimum quantifier is zero), OP_BRAZERO is inserted before
it, after it has been compiled. This means that any OP_RECURSE items within it
that refer to the group itself or any contained groups have to have their
offsets adjusted. That is the job of this function. Before it is called, the
partially compiled regex must be temporarily terminated with OP_END.

Arguments:
  group      points to the start of the group
  adjust     the amount by which the group is to be moved
  utf8       true in UTF-8 mode
  cd         contains pointers to tables etc.

Returns:     nothing
*/

static void
adjust_recurse(uschar *group, int adjust, bool utf8, compile_data *cd)
{
uschar *ptr = group;
while ((ptr = (uschar *)find_recurse(ptr, utf8)) != NULL)
  {
  int offset = GET(ptr, 1);
  if (cd->start_code + offset >= group) PUT(ptr, 1, offset + adjust);
  ptr += 1 + LINK_SIZE;
  }
}



/*************************************************
*           Compile one branch                   *
*************************************************/

/* Scan the pattern, compiling it into the code vector. If the options are
changed during the branch, the pointer is used to change the external options
bits.

Arguments:
  optionsptr     pointer to the option bits
  brackets       points to number of extracting brackets used
  code           points to the pointer to the current code point
  ptrptr         points to the current pattern pointer
  errorptr       points to pointer to error message
  firstbyteptr   set to initial literal character, or < 0 (REQ_UNSET, REQ_NONE)
  reqbyteptr     set to the last literal character required, else < 0
  bcptr          points to current branch chain
  cd             contains pointers to tables etc.

Returns:         true on success
                 false, with *errorptr set on error
*/

static bool
compile_branch(int *optionsptr, int *brackets, uschar **codeptr,
  const uschar **ptrptr, const char **errorptr, int *firstbyteptr,
  int *reqbyteptr, branch_chain *bcptr, compile_data *cd)
{
int repeat_type, op_type;
int repeat_min = 0, repeat_max = 0;      /* To please picky compilers */
int bravalue = 0;
int length;
int greedy_default, greedy_non_default;
int firstbyte, reqbyte;
int zeroreqbyte, zerofirstbyte;
int req_caseopt, reqvary, tempreqvary;
int condcount = 0;
int options = *optionsptr;
register int c;
register uschar *code = *codeptr;
uschar *tempcode;
bool inescq = false;
bool groupsetfirstbyte = false;
const uschar *ptr = *ptrptr;
const uschar *tempptr;
uschar *previous = NULL;
uschar classa[32];

bool utf8 = false;

/* Set up the default and non-default settings for greediness */

greedy_default = ((options & PCRE_UNGREEDY) != 0);
greedy_non_default = greedy_default ^ 1;

/* Initialize no first char, no required char. REQ_UNSET means "no char
matching encountered yet". It gets changed to REQ_NONE if we hit something that
matches a non-fixed char first char; reqbyte just remains unset if we never
find one.

When we hit a repeat whose minimum is zero, we may have to adjust these values
to take the zero repeat into account. This is implemented by setting them to
zerofirstbyte and zeroreqbyte when such a repeat is encountered. The individual
item types that can be repeated set these backoff variables appropriately. */

firstbyte = reqbyte = zerofirstbyte = zeroreqbyte = REQ_UNSET;

/* The variable req_caseopt contains either the REQ_CASELESS value or zero,
according to the current setting of the caseless flag. REQ_CASELESS is a bit
value > 255. It is added into the firstbyte or reqbyte variables to record the
case status of the value. */

req_caseopt = ((options & PCRE_CASELESS) != 0)? REQ_CASELESS : 0;

/* Switch on next character until the end of the branch */

for (;; ptr++)
  {
  bool negate_class;
  bool possessive_quantifier;
  int class_charcount;
  int class_lastchar;
  int newoptions;
  int recno;
  int skipbytes;
  int subreqbyte;
  int subfirstbyte;

  c = *ptr;
  if (inescq && c != 0) goto NORMAL_CHAR;

  if ((options & PCRE_EXTENDED) != 0)
    {
    if ((cd->ctypes[c] & ctype_space) != 0) continue;
    if (c == '#')
      {
      /* The space before the ; is to avoid a warning on a silly compiler
      on the Macintosh. */
      while ((c = *(++ptr)) != 0 && c != NEWLINE) ;
      if (c != 0) continue;   /* Else fall through to handle end of string */
      }
    }

  switch(c)
    {
    /* The branch terminates at end of string, |, or ). */

    case 0:
    case '|':
    case ')':
    *firstbyteptr = firstbyte;
    *reqbyteptr = reqbyte;
    *codeptr = code;
    *ptrptr = ptr;
    return true;

    /* Handle single-character metacharacters. In multiline mode, ^ disables
    the setting of any following char as a first character. */

    case '^':
    if ((options & PCRE_MULTILINE) != 0)
      {
      if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
      }
    previous = NULL;
    *code++ = OP_CIRC;
    break;

    case '$':
    previous = NULL;
    *code++ = OP_DOLL;
    break;

    /* There can never be a first char if '.' is first, whatever happens about
    repeats. The value of reqbyte doesn't change either. */

    case '.':
    if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
    zerofirstbyte = firstbyte;
    zeroreqbyte = reqbyte;
    previous = code;
    *code++ = OP_ANY;
    break;

    /* Character classes. If the included characters are all < 255 in value, we
    build a 32-byte bitmap of the permitted characters, except in the special
    case where there is only one such character. For negated classes, we build
    the map as usual, then invert it at the end. However, we use a different
    opcode so that data characters > 255 can be handled correctly.

    If the class contains characters outside the 0-255 range, a different
    opcode is compiled. It may optionally have a bit map for characters < 256,
    but those above are are explicitly listed afterwards. A flag byte tells
    whether the bitmap is present, and whether this is a negated class or not.
    */

    case '[':
    previous = code;

    /* PCRE supports POSIX class stuff inside a class. Perl gives an error if
    they are encountered at the top level, so we'll do that too. */

    if ((ptr[1] == ':' || ptr[1] == '.' || ptr[1] == '=') &&
        check_posix_syntax(ptr, &tempptr, cd))
      {
      *errorptr = (ptr[1] == ':')? ERR13 : ERR31;
      goto FAILED;
      }

    /* If the first character is '^', set the negation flag and skip it. */

    if ((c = *(++ptr)) == '^')
      {
      negate_class = true;
      c = *(++ptr);
      }
    else
      {
      negate_class = false;
      }

    /* Keep a count of chars with values < 256 so that we can optimize the case
    of just a single character (as long as it's < 256). For higher valued UTF-8
    characters, we don't yet do any optimization. */

    class_charcount = 0;
    class_lastchar = -1;


    /* Initialize the 32-char bit map to all zeros. We have to build the
    map in a temporary bit of store, in case the class contains only 1
    character (< 256), because in that case the compiled code doesn't use the
    bit map. */

    memset(classa, 0, 32 * sizeof(uschar));

    /* Process characters until ] is reached. By writing this as a "do" it
    means that an initial ] is taken as a data character. The first pass
    through the regex checked the overall syntax, so we don't need to be very
    strict here. At the start of the loop, c contains the first byte of the
    character. */

    do
      {

      /* Inside \Q...\E everything is literal except \E */

      if (inescq)
        {
        if (c == '\\' && ptr[1] == 'E')
          {
          inescq = false;
          ptr++;
          continue;
          }
        else goto LONE_SINGLE_CHARACTER;
        }

      /* Handle POSIX class names. Perl allows a negation extension of the
      form [:^name:]. A square bracket that doesn't match the syntax is
      treated as a literal. We also recognize the POSIX constructions
      [.ch.] and [=ch=] ("collating elements") and fault them, as Perl
      5.6 and 5.8 do. */

      if (c == '[' &&
          (ptr[1] == ':' || ptr[1] == '.' || ptr[1] == '=') &&
          check_posix_syntax(ptr, &tempptr, cd))
        {
        bool local_negate = false;
        int posix_class, i;
        register const uschar *cbits = cd->cbits;

        if (ptr[1] != ':')
          {
          *errorptr = ERR31;
          goto FAILED;
          }

        ptr += 2;
        if (*ptr == '^')
          {
          local_negate = true;
          ptr++;
          }

        posix_class = check_posix_name(ptr, tempptr - ptr);
        if (posix_class < 0)
          {
          *errorptr = ERR30;
          goto FAILED;
          }

        /* If matching is caseless, upper and lower are converted to
        alpha. This relies on the fact that the class table starts with
        alpha, lower, upper as the first 3 entries. */

        if ((options & PCRE_CASELESS) != 0 && posix_class <= 2)
          posix_class = 0;

        /* Or into the map we are building up to 3 of the static class
        tables, or their negations. The [:blank:] class sets up the same
        chars as the [:space:] class (all white space). We remove the vertical
        white space chars afterwards. */

        posix_class *= 3;
        for (i = 0; i < 3; i++)
          {
          bool blankclass = strncmp((char *)ptr, "blank", 5) == 0;
          int taboffset = posix_class_maps[posix_class + i];
          if (taboffset < 0) break;
          if (local_negate)
            {
            for (c = 0; c < 32; c++) classa[c] |= ~cbits[c+taboffset];
            if (blankclass) classa[1] |= 0x3c;
            }
          else
            {
            for (c = 0; c < 32; c++) classa[c] |= cbits[c+taboffset];
            if (blankclass) classa[1] &= ~0x3c;
            }
          }

        ptr = tempptr + 1;
        class_charcount = 10;  /* Set > 1; assumes more than 1 per class */
        continue;    /* End of POSIX syntax handling */
        }

      /* Backslash may introduce a single character, or it may introduce one
      of the specials, which just set a flag. Escaped items are checked for
      validity in the pre-compiling pass. The sequence \b is a special case.
      Inside a class (and only there) it is treated as backspace. Elsewhere
      it marks a word boundary. Other escapes have preset maps ready to
      or into the one we are building. We assume they have more than one
      character in them, so set class_charcount bigger than one. */

      if (c == '\\')
        {
        c = check_escape(&ptr, errorptr, *brackets, options, true);
        if (-c == ESC_b) c = '\b';  /* \b is backslash in a class */

        if (-c == ESC_Q)            /* Handle start of quoted string */
          {
          if (ptr[1] == '\\' && ptr[2] == 'E')
            {
            ptr += 2; /* avoid empty string */
            }
          else inescq = true;
          continue;
          }

        else if (c < 0)
          {
          register const uschar *cbits = cd->cbits;
          class_charcount = 10;     /* Greater than 1 is what matters */
          switch (-c)
            {
            case ESC_d:
            for (c = 0; c < 32; c++) classa[c] |= cbits[c+cbit_digit];
            continue;

            case ESC_D:
            for (c = 0; c < 32; c++) classa[c] |= ~cbits[c+cbit_digit];
            continue;

            case ESC_w:
            for (c = 0; c < 32; c++) classa[c] |= cbits[c+cbit_word];
            continue;

            case ESC_W:
            for (c = 0; c < 32; c++) classa[c] |= ~cbits[c+cbit_word];
            continue;

            case ESC_s:
            for (c = 0; c < 32; c++) classa[c] |= cbits[c+cbit_space];
            classa[1] &= ~0x08;   /* Perl 5.004 onwards omits VT from \s */
            continue;

            case ESC_S:
            for (c = 0; c < 32; c++) classa[c] |= ~cbits[c+cbit_space];
            classa[1] |= 0x08;    /* Perl 5.004 onwards omits VT from \s */
            continue;

            /* Unrecognized escapes are faulted if PCRE is running in its
            strict mode. By default, for compatibility with Perl, they are
            treated as literals. */

            default:
            if ((options & PCRE_EXTRA) != 0)
              {
              *errorptr = ERR7;
              goto FAILED;
              }
            c = *ptr;    /* The final character */
            }
          }

        /* Fall through if we have a single character (c >= 0). This may be
        > 256 in UTF-8 mode. */

        }   /* End of backslash handling */

      /* A single character may be followed by '-' to form a range. However,
      Perl does not permit ']' to be the end of the range. A '-' character
      here is treated as a literal. */

      if (ptr[1] == '-' && ptr[2] != ']')
        {
        int d;
        ptr += 2;

        d = *ptr;

        /* The second part of a range can be a single-character escape, but
        not any of the other escapes. Perl 5.6 treats a hyphen as a literal
        in such circumstances. */

        if (d == '\\')
          {
          const uschar *oldptr = ptr;
          d = check_escape(&ptr, errorptr, *brackets, options, true);

          /* \b is backslash; any other special means the '-' was literal */

          if (d < 0)
            {
            if (d == -ESC_b) d = '\b'; else
              {
              ptr = oldptr - 2;
              goto LONE_SINGLE_CHARACTER;  /* A few lines below */
              }
            }
          }

        /* Check that the two values are in the correct order */

        if (d < c)
          {
          *errorptr = ERR8;
          goto FAILED;
          }

        /* If d is greater than 255, we can't just use the bit map, so set up
        for the UTF-8 supporting class type. If we are not caseless, we can
        just set up a single range. If we are caseless, the characters < 256
        are handled with a bitmap, in order to get the case-insensitive
        handling. */

        /* We use the bit map if the range is entirely < 255, or if part of it
        is < 255 and matching is caseless. */

        for (; c <= d; c++)
          {
          classa[c/8] |= (1 << (c&7));
          if ((options & PCRE_CASELESS) != 0)
            {
            int uc = cd->fcc[c];           /* flip case */
            classa[uc/8] |= (1 << (uc&7));
            }
          class_charcount++;                /* in case a one-char range */
          class_lastchar = c;
          }

        continue;   /* Go get the next char in the class */
        }

      /* Handle a lone single character - we can get here for a normal
      non-escape char, or after \ that introduces a single character. */

      LONE_SINGLE_CHARACTER:

      /* Handle a single-byte character */
        {
        classa[c/8] |= (1 << (c&7));
        if ((options & PCRE_CASELESS) != 0)
          {
          c = cd->fcc[c];   /* flip case */
          classa[c/8] |= (1 << (c&7));
          }
        class_charcount++;
        class_lastchar = c;
        }
      }

    /* Loop until ']' reached; the check for end of string happens inside the
    loop. This "while" is the end of the "do" above. */

    while ((c = *(++ptr)) != ']' || inescq);

    /* If class_charcount is 1, we saw precisely one character with a value <
    256. In UTF-8 mode, we can optimize if there were no characters >= 256 and
    the one character is < 128. In non-UTF-8 mode we can always optimize.

    The optimization throws away the bit map. We turn the item into a
    1-character OP_CHARS if it's positive, or OP_NOT if it's negative. Note
    that OP_NOT does not support multibyte characters. In the positive case, it
    can cause firstbyte to be set. Otherwise, there can be no first char if
    this item is first, whatever repeat count may follow. In the case of
    reqbyte, save the previous value for reinstating. */

    if (class_charcount == 1)
      {
      zeroreqbyte = reqbyte;
      if (negate_class)
        {
        if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
        zerofirstbyte = firstbyte;
        *code++ = OP_NOT;
        }
      else
        {
        if (firstbyte == REQ_UNSET)
          {
          zerofirstbyte = REQ_NONE;
          firstbyte = class_lastchar | req_caseopt;
          }
        else
          {
          zerofirstbyte = firstbyte;
          reqbyte = class_lastchar | req_caseopt | cd->req_varyopt;
          }
        *code++ = OP_CHARS;
        *code++ = 1;
        }
      *code++ = static_cast<uschar>(class_lastchar);
      break;  /* End of class handling */
      }       /* End of 1-byte optimization */

    /* Otherwise, if this is the first thing in the branch, there can be no
    first char setting, whatever the repeat count. Any reqbyte setting must
    remain unchanged after any kind of repeat. */

    if (firstbyte == REQ_UNSET) firstbyte = REQ_NONE;
    zerofirstbyte = firstbyte;
    zeroreqbyte = reqbyte;

    /* If there are characters with values > 255, we have to compile an
    extended class, with its own opcode. If there are no characters < 256,
    we can omit the bitmap. */


    /* If there are no characters > 255, negate the 32-byte map if necessary,
    and copy it into the code vector. If this is the first thing in the branch,
    there can be no first char setting, whatever the repeat count. Any reqbyte
    setting must remain unchanged after any kind of repeat. */

    if (negate_class)
      {
      *code++ = OP_NCLASS;
      for (c = 0; c < 32; c++) code[c] = static_cast<uschar>(~classa[c]);
      }
    else
      {
      *code++ = OP_CLASS;
      memcpy(code, classa, 32);
      }
    code += 32;
    break;

    /* Various kinds of repeat */

    case '{':
    if (!is_counted_repeat(ptr+1)) goto NORMAL_CHAR;
    ptr = read_repeat_counts(ptr+1, &repeat_min, &repeat_max, errorptr);
    if (*errorptr != NULL) goto FAILED;
    goto REPEAT;

    case '*':
    repeat_min = 0;
    repeat_max = -1;
    goto REPEAT;

    case '+':
    repeat_min = 1;
    repeat_max = -1;
    goto REPEAT;

    case '?':
    repeat_min = 0;
    repeat_max = 1;

    REPEAT:
    if (previous == NULL)
      {
      *errorptr = ERR9;
      goto FAILED;
      }

    if (repeat_min == 0)
      {
      firstbyte = zerofirstbyte;    /* Adjust for zero repeat */
      reqbyte = zeroreqbyte;        /* Ditto */
      }

    /* Remember whether this is a variable length repeat */

    reqvary = (repeat_min == repeat_max)? 0 : REQ_VARY;

    op_type = 0;                    /* Default single-char op codes */
    possessive_quantifier = false;  /* Default not possessive quantifier */

    /* Save start of previous item, in case we have to move it up to make space
    for an inserted OP_ONCE for the additional '+' extension. */

    tempcode = previous;

    /* If the next character is '+', we have a possessive quantifier. This
    implies greediness, whatever the setting of the PCRE_UNGREEDY option.
    If the next character is '?' this is a minimizing repeat, by default,
    but if PCRE_UNGREEDY is set, it works the other way round. We change the
    repeat type to the non-default. */

    if (ptr[1] == '+')
      {
      repeat_type = 0;                  /* Force greedy */
      possessive_quantifier = true;
      ptr++;
      }
    else if (ptr[1] == '?')
      {
      repeat_type = greedy_non_default;
      ptr++;
      }
    else repeat_type = greedy_default;

    /* If previous was a recursion, we need to wrap it inside brackets so that
    it can be replicated if necessary. */

    if (*previous == OP_RECURSE)
      {
      memmove(previous + 1 + LINK_SIZE, previous, 1 + LINK_SIZE);
      code += 1 + LINK_SIZE;
      *previous = OP_BRA;
      PUT(previous, 1, code - previous);
      *code = OP_KET;
      PUT(code, 1, code - previous);
      code += 1 + LINK_SIZE;
      }

    /* If previous was a string of characters, chop off the last one and use it
    as the subject of the repeat. If there was only one character, we can
    abolish the previous item altogether. If a one-char item has a minumum of
    more than one, ensure that it is set in reqbyte - it might not be if a
    sequence such as x{3} is the first thing in a branch because the x will
    have gone into firstbyte instead.  */

    if (*previous == OP_CHARS)
      {
      /* Deal with UTF-8 characters that take up more than one byte. It's
      easier to write this out separately than try to macrify it. Use c to
      hold the length of the character in bytes, plus 0x80 to flag that it's a
      length rather than a small character. */


      /* Handle the case of a single byte - either with no UTF8 support, or
      with UTF-8 disabled, or for a UTF-8 character < 128. */

        {
        c = *(--code);
        if (code == previous + 2)   /* There was only one character */
          {
          code = previous;              /* Abolish the previous item */
          if (repeat_min > 1) reqbyte = c | req_caseopt | cd->req_varyopt;
          }
        else
          {
          previous[1]--;             /* adjust length */
          tempcode = code;           /* Adjust position to be moved for '+' */
          }
        }

      goto OUTPUT_SINGLE_REPEAT;   /* Code shared with single character types */
      }

    /* If previous was a single negated character ([^a] or similar), we use
    one of the special opcodes, replacing it. The code is shared with single-
    character repeats by setting opt_type to add a suitable offset into
    repeat_type. OP_NOT is currently used only for single-byte chars. */

    else if (*previous == OP_NOT)
      {
      op_type = OP_NOTSTAR - OP_STAR;  /* Use "not" opcodes */
      c = previous[1];
      code = previous;
      goto OUTPUT_SINGLE_REPEAT;
      }

    /* If previous was a character type match (\d or similar), abolish it and
    create a suitable repeat item. The code is shared with single-character
    repeats by setting op_type to add a suitable offset into repeat_type. */

    else if (*previous < OP_EODN)
      {
      op_type = OP_TYPESTAR - OP_STAR;  /* Use type opcodes */
      c = *previous;
      code = previous;

      OUTPUT_SINGLE_REPEAT:

      /* If the maximum is zero then the minimum must also be zero; Perl allows
      this case, so we do too - by simply omitting the item altogether. */

      if (repeat_max == 0) goto END_REPEAT;

      /* Combine the op_type with the repeat_type */

      repeat_type += op_type;

      /* A minimum of zero is handled either as the special case * or ?, or as
      an UPTO, with the maximum given. */

      if (repeat_min == 0)
        {
        if (repeat_max == -1) *code++ = static_cast<uschar>(OP_STAR + repeat_type);
          else if (repeat_max == 1) *code++ = static_cast<uschar>(OP_QUERY + repeat_type);
        else
          {
          *code++ = static_cast<uschar>(OP_UPTO + repeat_type);
          PUT2INC(code, 0, repeat_max);
          }
        }

      /* The case {1,} is handled as the special case + */

      else if (repeat_min == 1 && repeat_max == -1)
        *code++ = static_cast<uschar>(OP_PLUS + repeat_type);

      /* The case {n,n} is just an EXACT, while the general case {n,m} is
      handled as an EXACT followed by an UPTO. An EXACT of 1 is optimized. */

      else
        {
        if (repeat_min != 1)
          {
          *code++ = static_cast<uschar>(OP_EXACT + op_type);  /* NB EXACT doesn't have repeat_type */
          PUT2INC(code, 0, repeat_min);
          }

        /* If the mininum is 1 and the previous item was a character string,
        we either have to put back the item that got cancelled if the string
        length was 1, or add the character back onto the end of a longer
        string. For a character type nothing need be done; it will just get
        put back naturally. Note that the final character is always going to
        get added below, so we leave code ready for its insertion. */

        else if (*previous == OP_CHARS)
          {
          if (code == previous) code += 2; else

          /* In UTF-8 mode, a multibyte char has its length in c, with the 0x80
          bit set as a flag. The length will always be between 2 and 6. */

          previous[1]++;
          }

        /*  For a single negated character we also have to put back the
        item that got cancelled. At present this applies only to single byte
        characters in any mode. */

        else if (*previous == OP_NOT) code++;

        /* If the maximum is unlimited, insert an OP_STAR. Before doing so,
        we have to insert the character for the previous code. In UTF-8 mode,
        long characters have their length in c, with the 0x80 bit as a flag. */

        if (repeat_max < 0)
          {
          *code++ = static_cast<uschar>(c);
          *code++ = static_cast<uschar>(OP_STAR + repeat_type);
          }

        /* Else insert an UPTO if the max is greater than the min, again
        preceded by the character, for the previously inserted code. */

        else if (repeat_max != repeat_min)
          {
          *code++ = static_cast<uschar>(c);
          repeat_max -= repeat_min;
          *code++ = static_cast<uschar>(OP_UPTO + repeat_type);
          PUT2INC(code, 0, repeat_max);
          }
        }

      /* The character or character type itself comes last in all cases. */


      *code++ = static_cast<uschar>(c);
      }

    /* If previous was a character class or a back reference, we put the repeat
    stuff after it, but just skip the item if the repeat was {0,0}. */

    else if (*previous == OP_CLASS ||
             *previous == OP_NCLASS ||
             *previous == OP_REF)
      {
      if (repeat_max == 0)
        {
        code = previous;
        goto END_REPEAT;
        }
      if (repeat_min == 0 && repeat_max == -1)
        *code++ = static_cast<uschar>(OP_CRSTAR + repeat_type);
      else if (repeat_min == 1 && repeat_max == -1)
        *code++ = static_cast<uschar>(OP_CRPLUS + repeat_type);
      else if (repeat_min == 0 && repeat_max == 1)
        *code++ = static_cast<uschar>(OP_CRQUERY + repeat_type);
      else
        {
        *code++ = static_cast<uschar>(OP_CRRANGE + repeat_type);
        PUT2INC(code, 0, repeat_min);
        if (repeat_max == -1) repeat_max = 0;  /* 2-byte encoding for max */
        PUT2INC(code, 0, repeat_max);
        }
      }

    /* If previous was a bracket group, we may have to replicate it in certain
    cases. */

    else if (*previous >= OP_BRA || *previous == OP_ONCE ||
             *previous == OP_COND)
      {
      register int i;
      int ketoffset = 0;
      int len = code - previous;
      uschar *bralink = NULL;

      /* If the maximum repeat count is unlimited, find the end of the bracket
      by scanning through from the start, and compute the offset back to it
      from the current code pointer. There may be an OP_OPT setting following
      the final KET, so we can't find the end just by going back from the code
      pointer. */

      if (repeat_max == -1)
        {
        register uschar *ket = previous;
        do ket += GET(ket, 1); while (*ket != OP_KET);
        ketoffset = code - ket;
        }

      /* The case of a zero minimum is special because of the need to stick
      OP_BRAZERO in front of it, and because the group appears once in the
      data, whereas in other cases it appears the minimum number of times. For
      this reason, it is simplest to treat this case separately, as otherwise
      the code gets far too messy. There are several special subcases when the
      minimum is zero. */

      if (repeat_min == 0)
        {
        /* If the maximum is also zero, we just omit the group from the output
        altogether. */

        if (repeat_max == 0)
          {
          code = previous;
          goto END_REPEAT;
          }

        /* If the maximum is 1 or unlimited, we just have to stick in the
        BRAZERO and do no more at this point. However, we do need to adjust
        any OP_RECURSE calls inside the group that refer to the group itself or
        any internal group, because the offset is from the start of the whole
        regex. Temporarily terminate the pattern while doing this. */

        if (repeat_max <= 1)
          {
          *code = OP_END;
          adjust_recurse(previous, 1, utf8, cd);
          memmove(previous+1, previous, len);
          code++;
          *previous++ = static_cast<uschar>(OP_BRAZERO + repeat_type);
          }

        /* If the maximum is greater than 1 and limited, we have to replicate
        in a nested fashion, sticking OP_BRAZERO before each set of brackets.
        The first one has to be handled carefully because it's the original
        copy, which has to be moved up. The remainder can be handled by code
        that is common with the non-zero minimum case below. We have to
        adjust the value or repeat_max, since one less copy is required. Once
        again, we may have to adjust any OP_RECURSE calls inside the group. */

        else
          {
          int offset;
          *code = OP_END;
          adjust_recurse(previous, 2 + LINK_SIZE, utf8, cd);
          memmove(previous + 2 + LINK_SIZE, previous, len);
          code += 2 + LINK_SIZE;
          *previous++ = static_cast<uschar>(OP_BRAZERO + repeat_type);
          *previous++ = OP_BRA;

          /* We chain together the bracket offset fields that have to be
          filled in later when the ends of the brackets are reached. */

          offset = (bralink == NULL)? 0 : previous - bralink;
          bralink = previous;
          PUTINC(previous, 0, offset);
          }

        repeat_max--;
        }

      /* If the minimum is greater than zero, replicate the group as many
      times as necessary, and adjust the maximum to the number of subsequent
      copies that we need. If we set a first char from the group, and didn't
      set a required char, copy the latter from the former. */

      else
        {
        if (repeat_min > 1)
          {
          if (groupsetfirstbyte && reqbyte < 0) reqbyte = firstbyte;
          for (i = 1; i < repeat_min; i++)
            {
            memcpy(code, previous, len);
            code += len;
            }
          }
        if (repeat_max > 0) repeat_max -= repeat_min;
        }

      /* This code is common to both the zero and non-zero minimum cases. If
      the maximum is limited, it replicates the group in a nested fashion,
      remembering the bracket starts on a stack. In the case of a zero minimum,
      the first one was set up above. In all cases the repeat_max now specifies
      the number of additional copies needed. */

      if (repeat_max >= 0)
        {
        for (i = repeat_max - 1; i >= 0; i--)
          {
          *code++ = static_cast<uschar>(OP_BRAZERO + repeat_type);

          /* All but the final copy start a new nesting, maintaining the
          chain of brackets outstanding. */

          if (i != 0)
            {
            int offset;
            *code++ = OP_BRA;
            offset = (bralink == NULL)? 0 : code - bralink;
            bralink = code;
            PUTINC(code, 0, offset);
            }

          memcpy(code, previous, len);
          code += len;
          }

        /* Now chain through the pending brackets, and fill in their length
        fields (which are holding the chain links pro tem). */

        while (bralink != NULL)
          {
          int oldlinkoffset;
          int offset = code - bralink + 1;
          uschar *bra = code - offset;
          oldlinkoffset = GET(bra, 1);
          bralink = (oldlinkoffset == 0)? NULL : bralink - oldlinkoffset;
          *code++ = OP_KET;
          PUTINC(code, 0, offset);
          PUT(bra, 1, offset);
          }
        }

      /* If the maximum is unlimited, set a repeater in the final copy. We
      can't just offset backwards from the current code point, because we
      don't know if there's been an options resetting after the ket. The
      correct offset was computed above. */

      else code[-ketoffset] = static_cast<uschar>(OP_KETRMAX + repeat_type);
      }

    /* Else there's some kind of shambles */

    else
      {
      *errorptr = ERR11;
      goto FAILED;
      }

    /* If the character following a repeat is '+', we wrap the entire repeated
    item inside OP_ONCE brackets. This is just syntactic sugar, taken from
    Sun's Java package. The repeated item starts at tempcode, not at previous,
    which might be the first part of a string whose (former) last char we
    repeated. However, we don't support '+' after a greediness '?'. */

    if (possessive_quantifier)
      {
      int len = code - tempcode;
      memmove(tempcode + 1+LINK_SIZE, tempcode, len);
      code += 1 + LINK_SIZE;
      len += 1 + LINK_SIZE;
      tempcode[0] = OP_ONCE;
      *code++ = OP_KET;
      PUTINC(code, 0, len);
      PUT(tempcode, 1, len);
      }

    /* In all case we no longer have a previous item. We also set the
    "follows varying string" flag for subsequently encountered reqbytes if
    it isn't already set and we have just passed a varying length item. */

    END_REPEAT:
    previous = NULL;
    cd->req_varyopt |= reqvary;
    break;


    /* Start of nested bracket sub-expression, or comment or lookahead or
    lookbehind or option setting or condition. First deal with special things
    that can come after a bracket; all are introduced by ?, and the appearance
    of any of them means that this is not a referencing group. They were
    checked for validity in the first pass over the string, so we don't have to
    check for syntax errors here.  */

    case '(':
    newoptions = options;
    skipbytes = 0;

    if (*(++ptr) == '?')
      {
      int set, unset;
      int *optset;

      switch (*(++ptr))
        {
        case '#':                 /* Comment; skip to ket */
        ptr++;
        while (*ptr != ')') ptr++;
        continue;

        case ':':                 /* Non-extracting bracket */
        bravalue = OP_BRA;
        ptr++;
        break;

        case '(':
        bravalue = OP_COND;       /* Conditional group */

        /* Condition to test for recursion */

        if (ptr[1] == 'R')
          {
          code[1+LINK_SIZE] = OP_CREF;
          PUT2(code, 2+LINK_SIZE, CREF_RECURSE);
          skipbytes = 3;
          ptr += 3;
          }

        /* Condition to test for a numbered subpattern match. We know that
        if a digit follows ( then there will just be digits until ) because
        the syntax was checked in the first pass. */

        else if ((digitab[ptr[1]] && ctype_digit) != 0)
          {
          int condref;                 /* Don't amalgamate; some compilers */
          condref = *(++ptr) - '0';    /* grumble at autoincrement in declaration */
          while (*(++ptr) != ')') condref = condref*10 + *ptr - '0';
          if (condref == 0)
            {
            *errorptr = ERR35;
            goto FAILED;
            }
          ptr++;
          code[1+LINK_SIZE] = OP_CREF;
          PUT2(code, 2+LINK_SIZE, condref);
          skipbytes = 3;
          }
        /* For conditions that are assertions, we just fall through, having
        set bravalue above. */
        break;

        case '=':                 /* Positive lookahead */
        bravalue = OP_ASSERT;
        ptr++;
        break;

        case '!':                 /* Negative lookahead */
        bravalue = OP_ASSERT_NOT;
        ptr++;
        break;

        case '<':                 /* Lookbehinds */
        switch (*(++ptr))
          {
          case '=':               /* Positive lookbehind */
          bravalue = OP_ASSERTBACK;
          ptr++;
          break;

          case '!':               /* Negative lookbehind */
          bravalue = OP_ASSERTBACK_NOT;
          ptr++;
          break;
          }
        break;

        case '>':                 /* One-time brackets */
        bravalue = OP_ONCE;
        ptr++;
        break;

        case 'C':                 /* Callout - may be followed by digits */
        *code++ = OP_CALLOUT;
          {
          int n = 0;
          while ((digitab[*(++ptr)] & ctype_digit) != 0)
            n = n * 10 + *ptr - '0';
          if (n > 255)
            {
            *errorptr = ERR38;
            goto FAILED;
            }
          *code++ = static_cast<uschar>(n);
          }
        previous = NULL;
        continue;

        case 'P':                 /* Named subpattern handling */
        if (*(++ptr) == '<')      /* Definition */
          {
          int i, namelen;
          uschar *slot = cd->name_table;
          const uschar *name;     /* Don't amalgamate; some compilers */
          name = ++ptr;           /* grumble at autoincrement in declaration */

          while (*ptr++ != '>');
          namelen = ptr - name - 1;

          for (i = 0; i < cd->names_found; i++)
            {
            int crc = memcmp(name, slot+2, namelen);
            if (crc == 0)
              {
              if (slot[2+namelen] == 0)
                {
                *errorptr = ERR43;
                goto FAILED;
                }
              crc = -1;             /* Current name is substring */
              }
            if (crc < 0)
              {
              memmove(slot + cd->name_entry_size, slot,
                (cd->names_found - i) * cd->name_entry_size);
              break;
              }
            slot += cd->name_entry_size;
            }

          PUT2(slot, 0, *brackets + 1);
          memcpy(slot + 2, name, namelen);
          slot[2+namelen] = 0;
          cd->names_found++;
          goto NUMBERED_GROUP;
          }

        if (*ptr == '=' || *ptr == '>')  /* Reference or recursion */
          {
          int i, namelen;
          int type = *ptr++;
          const uschar *name = ptr;
          uschar *slot = cd->name_table;

          while (*ptr != ')') ptr++;
          namelen = ptr - name;

          for (i = 0; i < cd->names_found; i++)
            {
            if (strncmp((char *)name, (char *)slot+2, namelen) == 0) break;
            slot += cd->name_entry_size;
            }
          if (i >= cd->names_found)
            {
            *errorptr = ERR15;
            goto FAILED;
            }

          recno = GET2(slot, 0);

          if (type == '>') goto HANDLE_RECURSION;  /* A few lines below */

          /* Back reference */

          previous = code;
          *code++ = OP_REF;
          PUT2INC(code, 0, recno);
          cd->backref_map |= (recno < 32)? (1 << recno) : 1;
          if (recno > cd->top_backref) cd->top_backref = recno;
          continue;
          }

        /* Should never happen */
        break;

        case 'R':                 /* Pattern recursion */
        ptr++;                    /* Same as (?0)      */
        /* Fall through */

        /* Recursion or "subroutine" call */

        case '0': case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
          {
          const uschar *called;
          recno = 0;
          while((digitab[*ptr] & ctype_digit) != 0)
            recno = recno * 10 + *ptr++ - '0';

          /* Come here from code above that handles a named recursion */

          HANDLE_RECURSION:

          previous = code;

          /* Find the bracket that is being referenced. Temporarily end the
          regex in case it doesn't exist. */

          *code = OP_END;
          called = (recno == 0)?
            cd->start_code : find_bracket(cd->start_code, recno);

          if (called == NULL)
            {
            *errorptr = ERR15;
            goto FAILED;
            }

          /* If the subpattern is still open, this is a recursive call. We
          check to see if this is a left recursion that could loop for ever,
          and diagnose that case. */

          if (GET(called, 1) == 0 && could_be_empty(called, code, bcptr, utf8))
            {
            *errorptr = ERR40;
            goto FAILED;
            }

          /* Insert the recursion/subroutine item */

          *code = OP_RECURSE;
          PUT(code, 1, called - cd->start_code);
          code += 1 + LINK_SIZE;
          }
        continue;

        /* Character after (? not specially recognized */

        default:                  /* Option setting */
        set = unset = 0;
        optset = &set;

        while (*ptr != ')' && *ptr != ':')
          {
          switch (*ptr++)
            {
            case '-': optset = &unset; break;

            case 'i': *optset |= PCRE_CASELESS; break;
            case 'm': *optset |= PCRE_MULTILINE; break;
            case 's': *optset |= PCRE_DOTALL; break;
            case 'x': *optset |= PCRE_EXTENDED; break;
            case 'U': *optset |= PCRE_UNGREEDY; break;
            case 'X': *optset |= PCRE_EXTRA; break;
            }
          }

        /* Set up the changed option bits, but don't change anything yet. */

        newoptions = (options | set) & (~unset);

        /* If the options ended with ')' this is not the start of a nested
        group with option changes, so the options change at this level. Compile
        code to change the ims options if this setting actually changes any of
        them. We also pass the new setting back so that it can be put at the
        start of any following branches, and when this group ends (if we are in
        a group), a resetting item can be compiled.

        Note that if this item is right at the start of the pattern, the
        options will have been abstracted and made global, so there will be no
        change to compile. */

        if (*ptr == ')')
          {
          if ((options & PCRE_IMS) != (newoptions & PCRE_IMS))
            {
            *code++ = OP_OPT;
            *code++ = static_cast<uschar>(newoptions & PCRE_IMS);
            }

          /* Change options at this level, and pass them back for use
          in subsequent branches. Reset the greedy defaults and the case
          value for firstbyte and reqbyte. */

          *optionsptr = options = newoptions;
          greedy_default = ((newoptions & PCRE_UNGREEDY) != 0);
          greedy_non_default = greedy_default ^ 1;
          req_caseopt = ((options & PCRE_CASELESS) != 0)? REQ_CASELESS : 0;

          previous = NULL;       /* This item can't be repeated */
          continue;              /* It is complete */
          }

        /* If the options ended with ':' we are heading into a nested group
        with possible change of options. Such groups are non-capturing and are
        not assertions of any kind. All we need to do is skip over the ':';
        the newoptions value is handled below. */

        bravalue = OP_BRA;
        ptr++;
        }
      }

    /* If PCRE_NO_AUTO_CAPTURE is set, all unadorned brackets become
    non-capturing and behave like (?:...) brackets */

    else if ((options & PCRE_NO_AUTO_CAPTURE) != 0)
      {
      bravalue = OP_BRA;
      }

    /* Else we have a referencing group; adjust the opcode. If the bracket
    number is greater than EXTRACT_BASIC_MAX, we set the opcode one higher, and
    arrange for the true number to follow later, in an OP_BRANUMBER item. */

    else
      {
      NUMBERED_GROUP:
      if (++(*brackets) > EXTRACT_BASIC_MAX)
        {
        bravalue = OP_BRA + EXTRACT_BASIC_MAX + 1;
        code[1+LINK_SIZE] = OP_BRANUMBER;
        PUT2(code, 2+LINK_SIZE, *brackets);
        skipbytes = 3;
        }
      else bravalue = OP_BRA + *brackets;
      }

    /* Process nested bracketed re. Assertions may not be repeated, but other
    kinds can be. We copy code into a non-register variable in order to be able
    to pass its address because some compilers complain otherwise. Pass in a
    new setting for the ims options if they have changed. */

    previous = (bravalue >= OP_ONCE)? code : NULL;
    *code = static_cast<uschar>(bravalue);
    tempcode = code;
    tempreqvary = cd->req_varyopt;     /* Save value before bracket */

    if (!compile_regex(
         newoptions,                   /* The complete new option state */
         options & PCRE_IMS,           /* The previous ims option state */
         brackets,                     /* Extracting bracket count */
         &tempcode,                    /* Where to put code (updated) */
         &ptr,                         /* Input pointer (updated) */
         errorptr,                     /* Where to put an error message */
         (bravalue == OP_ASSERTBACK ||
          bravalue == OP_ASSERTBACK_NOT), /* true if back assert */
         skipbytes,                    /* Skip over OP_COND/OP_BRANUMBER */
         &subfirstbyte,                /* For possible first char */
         &subreqbyte,                  /* For possible last char */
         bcptr,                        /* Current branch chain */
         cd))                          /* Tables block */
      goto FAILED;

    /* At the end of compiling, code is still pointing to the start of the
    group, while tempcode has been updated to point past the end of the group
    and any option resetting that may follow it. The pattern pointer (ptr)
    is on the bracket. */

    /* If this is a conditional bracket, check that there are no more than
    two branches in the group. */

    else if (bravalue == OP_COND)
      {
      uschar *tc = code;
      condcount = 0;

      do {
         condcount++;
         tc += GET(tc,1);
         }
      while (*tc != OP_KET);

      if (condcount > 2)
        {
        *errorptr = ERR27;
        goto FAILED;
        }

      /* If there is just one branch, we must not make use of its firstbyte or
      reqbyte, because this is equivalent to an empty second branch. */

      if (condcount == 1) subfirstbyte = subreqbyte = REQ_NONE;
      }

    /* Handle updating of the required and first characters. Update for normal
    brackets of all kinds, and conditions with two branches (see code above).
    If the bracket is followed by a quantifier with zero repeat, we have to
    back off. Hence the definition of zeroreqbyte and zerofirstbyte outside the
    main loop so that they can be accessed for the back off. */

    zeroreqbyte = reqbyte;
    zerofirstbyte = firstbyte;
    groupsetfirstbyte = false;

    if (bravalue >= OP_BRA || bravalue == OP_ONCE || bravalue == OP_COND)
      {
      /* If we have not yet set a firstbyte in this branch, take it from the
      subpattern, remembering that it was set here so that a repeat of more
      than one can replicate it as reqbyte if necessary. If the subpattern has
      no firstbyte, set "none" for the whole branch. In both cases, a zero
      repeat forces firstbyte to "none". */

      if (firstbyte == REQ_UNSET)
        {
        if (subfirstbyte >= 0)
          {
          firstbyte = subfirstbyte;
          groupsetfirstbyte = true;
          }
        else firstbyte = REQ_NONE;
        zerofirstbyte = REQ_NONE;
        }

      /* If firstbyte was previously set, convert the subpattern's firstbyte
      into reqbyte if there wasn't one, using the vary flag that was in
      existence beforehand. */

      else if (subfirstbyte >= 0 && subreqbyte < 0)
        subreqbyte = subfirstbyte | tempreqvary;

      /* If the subpattern set a required byte (or set a first byte that isn't
      really the first byte - see above), set it. */

      if (subreqbyte >= 0) reqbyte = subreqbyte;
      }

    /* For a forward assertion, we take the reqbyte, if set. This can be
    helpful if the pattern that follows the assertion doesn't set a different
    char. For example, it's useful for /(?=abcde).+/. We can't set firstbyte
    for an assertion, however because it leads to incorrect effect for patterns
    such as /(?=a)a.+/ when the "real" "a" would then become a reqbyte instead
    of a firstbyte. This is overcome by a scan at the end if there's no
    firstbyte, looking for an asserted first char. */

    else if (bravalue == OP_ASSERT && subreqbyte >= 0) reqbyte = subreqbyte;

    /* Now update the main code pointer to the end of the group. */

    code = tempcode;

    /* Error if hit end of pattern */

    if (*ptr != ')')
      {
      *errorptr = ERR14;
      goto FAILED;
      }
    break;

    /* Check \ for being a real metacharacter; if not, fall through and handle
    it as a data character at the start of a string. Escape items are checked
    for validity in the pre-compiling pass. */

    case '\\':
    tempptr = ptr;
    c = check_escape(&ptr, errorptr, *brackets, options, false);

    /* Handle metacharacters introduced by \. For ones like \d, the ESC_ values
    are arranged to be the negation of the corresponding OP_values. For the
    back references, the values are ESC_REF plus the reference number. Only
    back references and those types that consume a character may be repeated.
    We can test for values between ESC_b and ESC_Z for the latter; this may
    have to change if any new ones are ever created. */

    if (c < 0)
      {
      if (-c == ESC_Q)            /* Handle start of quoted string */
        {
        if (ptr[1] == '\\' && ptr[2] == 'E') ptr += 2; /* avoid empty string */
          else inescq = true;
        continue;
        }

      /* For metasequences that actually match a character, we disable the
      setting of a first character if it hasn't already been set. */

      if (firstbyte == REQ_UNSET && -c > ESC_b && -c < ESC_Z)
        firstbyte = REQ_NONE;

      /* Set values to reset to if this is followed by a zero repeat. */

      zerofirstbyte = firstbyte;
      zeroreqbyte = reqbyte;

      /* Back references are handled specially */

      if (-c >= ESC_REF)
        {
        int number = -c - ESC_REF;
        previous = code;
        *code++ = OP_REF;
        PUT2INC(code, 0, number);
        }
      else
        {
        previous = (-c > ESC_b && -c < ESC_Z)? code : NULL;
        *code++ = static_cast<uschar>(-c);
        }
      continue;
      }

    /* Data character: reset and fall through */

    ptr = tempptr;
    c = '\\';

    /* Handle a run of data characters until a metacharacter is encountered.
    The first character is guaranteed not to be whitespace or # when the
    extended flag is set. */

    NORMAL_CHAR:
    default:
    previous = code;
    *code = OP_CHARS;
    code += 2;
    length = 0;

    do
      {
      /* If in \Q...\E, check for the end; if not, we always have a literal */

      if (inescq)
        {
        if (c == '\\' && ptr[1] == 'E')
          {
          inescq = false;
          ptr++;
          }
        else
          {
          *code++ = static_cast<uschar>(c);
          length++;
          }
        continue;
        }

      /* Skip white space and comments for /x patterns */

      if ((options & PCRE_EXTENDED) != 0)
        {
        if ((cd->ctypes[c] & ctype_space) != 0) continue;
        if (c == '#')
          {
          /* The space before the ; is to avoid a warning on a silly compiler
          on the Macintosh. */
          while ((c = *(++ptr)) != 0 && c != NEWLINE) ;
          if (c == 0) break;
          continue;
          }
        }

      /* Backslash may introduce a data char or a metacharacter. Escaped items
      are checked for validity in the pre-compiling pass. Stop the string
      before a metaitem. */

      if (c == '\\')
        {
        tempptr = ptr;
        c = check_escape(&ptr, errorptr, *brackets, options, false);
        if (c < 0) { ptr = tempptr; break; }

        /* If a character is > 127 in UTF-8 mode, we have to turn it into
        two or more bytes in the UTF-8 encoding. */

        }

      /* Ordinary character or single-char escape */

      *code++ = static_cast<uschar>(c);
      length++;
      }

    /* This "while" is the end of the "do" above. */

    while (length < MAXLIT && (cd->ctypes[c = *(++ptr)] & ctype_meta) == 0);

    /* Update the first and last requirements. These are always bytes, even in
    UTF-8 mode. However, there is a special case to be considered when there
    are only one or two characters. Because this gets messy in UTF-8 mode, the
    code is kept separate. When we get here "length" contains the number of
    bytes. */


    /* This is the code for non-UTF-8 operation, either without UTF-8 support,
    or when UTF-8 is not enabled. */

      {
      /* firstbyte was not previously set; take it from this string */

      if (firstbyte == REQ_UNSET)
        {
        if (length == 1)
          {
          zerofirstbyte = REQ_NONE;
          firstbyte = previous[2] | req_caseopt;
          zeroreqbyte = reqbyte;
          }
        else
          {
          zerofirstbyte = firstbyte = previous[2] | req_caseopt;
          zeroreqbyte = (length > 2)?
            (code[-2] | req_caseopt | cd->req_varyopt) : reqbyte;
          reqbyte = code[-1] | req_caseopt | cd->req_varyopt;
          }
        }

      /* firstbyte was previously set */

      else
        {
        zerofirstbyte = firstbyte;
        zeroreqbyte = (length == 1)? reqbyte :
          code[-2] | req_caseopt | cd->req_varyopt;
        reqbyte = code[-1] | req_caseopt | cd->req_varyopt;
        }
      }

    /* Set the length in the data vector, and advance to the next state. */

    previous[1] = static_cast<uschar>(length);
    if (length < MAXLIT) ptr--;
    break;
    }
  }                   /* end of big loop */

/* Control never reaches here by falling through, only by a goto for all the
error states. Pass back the position in the pattern so that it can be displayed
to the user for diagnosing the error. */

FAILED:
*ptrptr = ptr;
return false;
}




/*************************************************
*     Compile sequence of alternatives           *
*************************************************/

/* On entry, ptr is pointing past the bracket character, but on return
it points to the closing bracket, or vertical bar, or end of string.
The code variable is pointing at the byte into which the BRA operator has been
stored. If the ims options are changed at the start (for a (?ims: group) or
during any branch, we need to insert an OP_OPT item at the start of every
following branch to ensure they get set correctly at run time, and also pass
the new options into every subsequent branch compile.

Argument:
  options        option bits, including any changes for this subpattern
  oldims         previous settings of ims option bits
  brackets       -> int containing the number of extracting brackets used
  codeptr        -> the address of the current code pointer
  ptrptr         -> the address of the current pattern pointer
  errorptr       -> pointer to error message
  lookbehind     true if this is a lookbehind assertion
  skipbytes      skip this many bytes at start (for OP_COND, OP_BRANUMBER)
  firstbyteptr   place to put the first required character, or a negative number
  reqbyteptr     place to put the last required character, or a negative number
  bcptr          pointer to the chain of currently open branches
  cd             points to the data block with tables pointers etc.

Returns:      true on success
*/

static bool
compile_regex(int options, int oldims, int *brackets, uschar **codeptr,
  const uschar **ptrptr, const char **errorptr, bool lookbehind, int skipbytes,
  int *firstbyteptr, int *reqbyteptr, branch_chain *bcptr, compile_data *cd)
{
const uschar *ptr = *ptrptr;
uschar *code = *codeptr;
uschar *last_branch = code;
uschar *start_bracket = code;
uschar *reverse_count = NULL;
int firstbyte, reqbyte;
int branchfirstbyte, branchreqbyte;
branch_chain bc;

bc.outer = bcptr;
bc.current = code;

firstbyte = reqbyte = REQ_UNSET;

/* Offset is set zero to mark that this bracket is still open */

PUT(code, 1, 0);
code += 1 + LINK_SIZE + skipbytes;

/* Loop for each alternative branch */

for (;!MuxAlarm.bAlarmed;)
  {
  /* Handle a change of ims options at the start of the branch */

  if ((options & PCRE_IMS) != oldims)
    {
    *code++ = OP_OPT;
    *code++ = static_cast<uschar>(options & PCRE_IMS);
    }

  /* Set up dummy OP_REVERSE if lookbehind assertion */

  if (lookbehind)
    {
    *code++ = OP_REVERSE;
    reverse_count = code;
    PUTINC(code, 0, 0);
    }

  /* Now compile the branch */

  if (!compile_branch(&options, brackets, &code, &ptr, errorptr,
        &branchfirstbyte, &branchreqbyte, &bc, cd))
    {
    *ptrptr = ptr;
    return false;
    }

  /* If this is the first branch, the firstbyte and reqbyte values for the
  branch become the values for the regex. */

  if (*last_branch != OP_ALT)
    {
    firstbyte = branchfirstbyte;
    reqbyte = branchreqbyte;
    }

  /* If this is not the first branch, the first char and reqbyte have to
  match the values from all the previous branches, except that if the previous
  value for reqbyte didn't have REQ_VARY set, it can still match, and we set
  REQ_VARY for the regex. */

  else
    {
    /* If we previously had a firstbyte, but it doesn't match the new branch,
    we have to abandon the firstbyte for the regex, but if there was previously
    no reqbyte, it takes on the value of the old firstbyte. */

    if (firstbyte >= 0 && firstbyte != branchfirstbyte)
      {
      if (reqbyte < 0) reqbyte = firstbyte;
      firstbyte = REQ_NONE;
      }

    /* If we (now or from before) have no firstbyte, a firstbyte from the
    branch becomes a reqbyte if there isn't a branch reqbyte. */

    if (firstbyte < 0 && branchfirstbyte >= 0 && branchreqbyte < 0)
        branchreqbyte = branchfirstbyte;

    /* Now ensure that the reqbytes match */

    if ((reqbyte & ~REQ_VARY) != (branchreqbyte & ~REQ_VARY))
      reqbyte = REQ_NONE;
    else reqbyte |= branchreqbyte;   /* To "or" REQ_VARY */
    }

  /* If lookbehind, check that this branch matches a fixed-length string,
  and put the length into the OP_REVERSE item. Temporarily mark the end of
  the branch with OP_END. */

  if (lookbehind)
    {
    int length;
    *code = OP_END;
    length = find_fixedlength(last_branch, options);
    DPRINTF(("fixed length = %d\n", length));
    if (length < 0)
      {
      *errorptr = (length == -2)? ERR36 : ERR25;
      *ptrptr = ptr;
      return false;
      }
    PUT(reverse_count, 0, length);
    }

  /* Reached end of expression, either ')' or end of pattern. Go back through
  the alternative branches and reverse the chain of offsets, with the field in
  the BRA item now becoming an offset to the first alternative. If there are
  no alternatives, it points to the end of the group. The length in the
  terminating ket is always the length of the whole bracketed item. If any of
  the ims options were changed inside the group, compile a resetting op-code
  following, except at the very end of the pattern. Return leaving the pointer
  at the terminating char. */

  if (*ptr != '|')
    {
    int length = code - last_branch;
    do
      {
      int prev_length = GET(last_branch, 1);
      PUT(last_branch, 1, length);
      length = prev_length;
      last_branch -= length;
      }
    while (length > 0);

    /* Fill in the ket */

    *code = OP_KET;
    PUT(code, 1, code - start_bracket);
    code += 1 + LINK_SIZE;

    /* Resetting option if needed */

    if ((options & PCRE_IMS) != oldims && *ptr == ')')
      {
      *code++ = OP_OPT;
      *code++ = static_cast<uschar>(oldims);
      }

    /* Set values to pass back */

    *codeptr = code;
    *ptrptr = ptr;
    *firstbyteptr = firstbyte;
    *reqbyteptr = reqbyte;
    return true;
    }

  /* Another branch follows; insert an "or" node. Its length field points back
  to the previous branch while the bracket remains open. At the end the chain
  is reversed. It's done like this so that the start of the bracket has a
  zero offset until it is closed, making it possible to detect recursion. */

  *code = OP_ALT;
  PUT(code, 1, code - last_branch);
  bc.current = last_branch = code;
  code += 1 + LINK_SIZE;
  ptr++;
  }
return false;
}




/*************************************************
*          Check for anchored expression         *
*************************************************/

/* Try to find out if this is an anchored regular expression. Consider each
alternative branch. If they all start with OP_SOD or OP_CIRC, or with a bracket
all of whose alternatives start with OP_SOD or OP_CIRC (recurse ad lib), then
it's anchored. However, if this is a multiline pattern, then only OP_SOD
counts, since OP_CIRC can match in the middle.

We can also consider a regex to be anchored if OP_SOM starts all its branches.
This is the code for \G, which means "match at start of match position, taking
into account the match offset".

A branch is also implicitly anchored if it starts with .* and DOTALL is set,
because that will try the rest of the pattern at all possible matching points,
so there is no point trying again.... er ....

.... except when the .* appears inside capturing parentheses, and there is a
subsequent back reference to those parentheses. We haven't enough information
to catch that case precisely.

At first, the best we could do was to detect when .* was in capturing brackets
and the highest back reference was greater than or equal to that level.
However, by keeping a bitmap of the first 31 back references, we can catch some
of the more common cases more precisely.

Arguments:
  code           points to start of expression (the bracket)
  options        points to the options setting
  bracket_map    a bitmap of which brackets we are inside while testing; this
                  handles up to substring 31; after that we just have to take
                  the less precise approach
  backref_map    the back reference bitmap

Returns:     true or false
*/

static bool
is_anchored(register const uschar *code, int *options, unsigned int bracket_map,
  unsigned int backref_map)
{
do {
   const uschar *scode =
     first_significant_code(code + 1+LINK_SIZE, options, PCRE_MULTILINE);
   register int op = *scode;

   /* Capturing brackets */

   if (op > OP_BRA)
     {
     int new_map;
     op -= OP_BRA;
     if (op > EXTRACT_BASIC_MAX) op = GET2(scode, 2+LINK_SIZE);
     new_map = bracket_map | ((op < 32)? (1 << op) : 1);
     if (!is_anchored(scode, options, new_map, backref_map)) return false;
     }

   /* Other brackets */

   else if (op == OP_BRA || op == OP_ASSERT || op == OP_ONCE || op == OP_COND)
     {
     if (!is_anchored(scode, options, bracket_map, backref_map)) return false;
     }

   /* .* is not anchored unless DOTALL is set and it isn't in brackets that
   are or may be referenced. */

   else if ((op == OP_TYPESTAR || op == OP_TYPEMINSTAR) &&
            (*options & PCRE_DOTALL) != 0)
     {
     if (scode[1] != OP_ANY || (bracket_map & backref_map) != 0) return false;
     }

   /* Check for explicit anchoring */

   else if (op != OP_SOD && op != OP_SOM &&
           ((*options & PCRE_MULTILINE) != 0 || op != OP_CIRC))
     return false;
   code += GET(code, 1);
   }
while (*code == OP_ALT);   /* Loop for each alternative */
return true;
}



/*************************************************
*         Check for starting with ^ or .*        *
*************************************************/

/* This is called to find out if every branch starts with ^ or .* so that
"first char" processing can be done to speed things up in multiline
matching and for non-DOTALL patterns that start with .* (which must start at
the beginning or after \n). As in the case of is_anchored() (see above), we
have to take account of back references to capturing brackets that contain .*
because in that case we can't make the assumption.

Arguments:
  code           points to start of expression (the bracket)
  bracket_map    a bitmap of which brackets we are inside while testing; this
                  handles up to substring 31; after that we just have to take
                  the less precise approach
  backref_map    the back reference bitmap

Returns:         true or false
*/

static bool
is_startline(const uschar *code, unsigned int bracket_map,
  unsigned int backref_map)
{
do {
   const uschar *scode = first_significant_code(code + 1+LINK_SIZE, NULL, 0);
   register int op = *scode;

   /* Capturing brackets */

   if (op > OP_BRA)
     {
     int new_map;
     op -= OP_BRA;
     if (op > EXTRACT_BASIC_MAX) op = GET2(scode, 2+LINK_SIZE);
     new_map = bracket_map | ((op < 32)? (1 << op) : 1);
     if (!is_startline(scode, new_map, backref_map)) return false;
     }

   /* Other brackets */

   else if (op == OP_BRA || op == OP_ASSERT || op == OP_ONCE || op == OP_COND)
     { if (!is_startline(scode, bracket_map, backref_map)) return false; }

   /* .* is not anchored unless DOTALL is set and it isn't in brackets that
   may be referenced. */

   else if (op == OP_TYPESTAR || op == OP_TYPEMINSTAR)
     {
     if (scode[1] != OP_ANY || (bracket_map & backref_map) != 0) return false;
     }

   /* Check for explicit circumflex */

   else if (op != OP_CIRC) return false;
   code += GET(code, 1);
   }
while (*code == OP_ALT);  /* Loop for each alternative */
return true;
}



/*************************************************
*       Check for asserted fixed first char      *
*************************************************/

/* During compilation, the "first char" settings from forward assertions are
discarded, because they can cause conflicts with actual literals that follow.
However, if we end up without a first char setting for an unanchored pattern,
it is worth scanning the regex to see if there is an initial asserted first
char. If all branches start with the same asserted char, or with a bracket all
of whose alternatives start with the same asserted char (recurse ad lib), then
we return that char, otherwise -1.

Arguments:
  code       points to start of expression (the bracket)
  options    pointer to the options (used to check casing changes)
  inassert   true if in an assertion

Returns:     -1 or the fixed first char
*/

static int
find_firstassertedchar(const uschar *code, int *options, bool inassert)
{
register int c = -1;
do {
   int d;
   const uschar *scode =
     first_significant_code(code + 1+LINK_SIZE, options, PCRE_CASELESS);
   register int op = *scode;

   if (op >= OP_BRA) op = OP_BRA;

   switch(op)
     {
     default:
     return -1;

     case OP_BRA:
     case OP_ASSERT:
     case OP_ONCE:
     case OP_COND:
     if ((d = find_firstassertedchar(scode, options, op == OP_ASSERT)) < 0)
       return -1;
     if (c < 0) c = d; else if (c != d) return -1;
     break;

     case OP_EXACT:       /* Fall through */
     scode++;

     case OP_CHARS:       /* Fall through */
     scode++;

     case OP_PLUS:
     case OP_MINPLUS:
     if (!inassert) return -1;
     if (c < 0)
       {
       c = scode[1];
       if ((*options & PCRE_CASELESS) != 0) c |= REQ_CASELESS;
       }
     else if (c != scode[1]) return -1;
     break;
     }

   code += GET(code, 1);
   }
while (*code == OP_ALT);
return c;
}




/*************************************************
*        Compile a Regular Expression            *
*************************************************/

/* This function takes a string and returns a pointer to a block of store
holding a compiled version of the expression.

Arguments:
  pattern      the regular expression
  options      various option bits
  errorptr     pointer to pointer to error text
  erroroffset  ptr offset in pattern where error was detected
  tables       pointer to character tables or NULL

Returns:       pointer to compiled data block, or NULL on error,
               with errorptr and erroroffset set
*/

pcre *
pcre_compile(const char *pattern, int options, const char **errorptr,
  int *erroroffset, const unsigned char *tables)
{
real_pcre *re;
int length = 1 + LINK_SIZE;      /* For initial BRA plus length */
int runlength;
int c, firstbyte, reqbyte;
int bracount = 0;
int branch_extra = 0;
int branch_newextra;
int item_count = -1;
int name_count = 0;
int max_name_size = 0;
bool inescq = false;
unsigned int brastackptr = 0;
size_t size;
uschar *code;
const uschar *codestart;
const uschar *ptr;
compile_data compile_block;
int brastack[BRASTACK_SIZE];
uschar bralenstack[BRASTACK_SIZE];

/* We can't pass back an error message if errorptr is NULL; I guess the best we
can do is just return NULL. */

if (errorptr == NULL) return NULL;
*errorptr = NULL;

/* However, we can give a message for this error */

if (erroroffset == NULL)
  {
  *errorptr = ERR16;
  return NULL;
  }
*erroroffset = 0;

/* Can't support UTF8 unless PCRE has been compiled to include the code. */

if ((options & PCRE_UTF8) != 0)
  {
  *errorptr = ERR32;
  return NULL;
  }

if ((options & ~PUBLIC_OPTIONS) != 0)
  {
  *errorptr = ERR17;
  return NULL;
  }

/* Set up pointers to the individual character tables */

if (tables == NULL) tables = pcre_default_tables;
compile_block.lcc = tables + lcc_offset;
compile_block.fcc = tables + fcc_offset;
compile_block.cbits = tables + cbits_offset;
compile_block.ctypes = tables + ctypes_offset;

/* Maximum back reference and backref bitmap. This is updated for numeric
references during the first pass, but for named references during the actual
compile pass. The bitmap records up to 31 back references to help in deciding
whether (.*) can be treated as anchored or not. */

compile_block.top_backref = 0;
compile_block.backref_map = 0;

/* Reflect pattern for debugging output */

DPRINTF(("------------------------------------------------------------------\n"));
DPRINTF(("%s\n", pattern));

/* The first thing to do is to make a pass over the pattern to compute the
amount of store required to hold the compiled code. This does not have to be
perfect as long as errors are overestimates. At the same time we can detect any
flag settings right at the start, and extract them. Make an attempt to correct
for any counted white space if an "extended" flag setting appears late in the
pattern. We can't be so clever for #-comments. */

ptr = (const uschar *)(pattern - 1);
while ((c = *(++ptr)) != 0)
  {
  int min, max;
#if defined(WIN32) && (_MSC_VER == 1200) && defined(_M_IX86) && !defined(__INTEL_COMPILER)
  // The addition of 'volatile' works around a bug in Version 12.0 of
  // Microsoft's Visual C/C++ compiler (part of Visual Studio 6.0). Without
  // volatile, class_optcount is calculated properly, but the compiler
  // clobbers the EAX register before tests it as class_optcount.
  //
  // This is not a problem with the Intel Compiler.
  //
  volatile int class_optcount;
#else
  int class_optcount;
#endif
  int bracket_length;
  int duplength;

  /* If we are inside a \Q...\E sequence, all chars are literal */

  if (inescq) goto NORMAL_CHAR;

  /* Otherwise, first check for ignored whitespace and comments */

  if ((options & PCRE_EXTENDED) != 0)
    {
    if ((compile_block.ctypes[c] & ctype_space) != 0) continue;
    if (c == '#')
      {
      /* The space before the ; is to avoid a warning on a silly compiler
      on the Macintosh. */
      while ((c = *(++ptr)) != 0 && c != NEWLINE) ;
      if (c == 0) break;
      continue;
      }
    }

  item_count++;    /* Is zero for the first non-comment item */

  switch(c)
    {
    /* A backslashed item may be an escaped "normal" character or a
    character type. For a "normal" character, put the pointers and
    character back so that tests for whitespace etc. in the input
    are done correctly. */

    case '\\':
      {
      const uschar *save_ptr = ptr;
      c = check_escape(&ptr, errorptr, bracount, options, false);
      if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
      if (c >= 0)
        {
        ptr = save_ptr;
        c = '\\';
        goto NORMAL_CHAR;
        }
      }

    /* If \Q, enter "literal" mode */

    if (-c == ESC_Q)
      {
      inescq = true;
      continue;
      }

    /* Other escapes need one byte, and are of length one for repeats */

    length++;

    /* A back reference needs an additional 2 bytes, plus either one or 5
    bytes for a repeat. We also need to keep the value of the highest
    back reference. */

    if (c <= -ESC_REF)
      {
      int refnum = -c - ESC_REF;
      compile_block.backref_map |= (refnum < 32)? (1 << refnum) : 1;
      if (refnum > compile_block.top_backref)
        compile_block.top_backref = refnum;
      length += 2;   /* For single back reference */
      if (ptr[1] == '{' && is_counted_repeat(ptr+2))
        {
        ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
        if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
        if ((min == 0 && (max == 1 || max == -1)) ||
          (min == 1 && max == -1))
            length++;
        else length += 5;
        if (ptr[1] == '?') ptr++;
        }
      }
    continue;

    case '^':     /* Single-byte metacharacters */
    case '.':
    case '$':
    length++;
    continue;

    case '*':            /* These repeats won't be after brackets; */
    case '+':            /* those are handled separately */
    case '?':
    length++;
    goto POSESSIVE;      /* A few lines below */

    /* This covers the cases of braced repeats after a single char, metachar,
    class, or back reference. */

    case '{':
    if (!is_counted_repeat(ptr+1)) goto NORMAL_CHAR;
    ptr = read_repeat_counts(ptr+1, &min, &max, errorptr);
    if (*errorptr != NULL) goto PCRE_ERROR_RETURN;

    /* These special cases just insert one extra opcode */

    if ((min == 0 && (max == 1 || max == -1)) ||
      (min == 1 && max == -1))
        length++;

    /* These cases might insert additional copies of a preceding character. */

    else
      {

      /* Not UTF-8 mode: all characters are one byte */
        {
        if (min != 1)
          {
          length--;   /* Uncount the original char or metachar */
          if (min > 0) length += 4;
          }

        length += (max > 0)? 4 : 2;
        }
      }

    if (ptr[1] == '?') ptr++;      /* Needs no extra length */

    POSESSIVE:                     /* Test for possessive quantifier */
    if (ptr[1] == '+')
      {
      ptr++;
      length += 2 + 2*LINK_SIZE;   /* Allow for atomic brackets */
      }
    continue;

    /* An alternation contains an offset to the next branch or ket. If any ims
    options changed in the previous branch(es), and/or if we are in a
    lookbehind assertion, extra space will be needed at the start of the
    branch. This is handled by branch_extra. */

    case '|':
    length += 1 + LINK_SIZE + branch_extra;
    continue;

    /* A character class uses 33 characters provided that all the character
    values are less than 256. Otherwise, it uses a bit map for low valued
    characters, and individual items for others. Don't worry about character
    types that aren't allowed in classes - they'll get picked up during the
    compile. A character class that contains only one single-byte character
    uses 2 or 3 bytes, depending on whether it is negated or not. Notice this
    where we can. (In UTF-8 mode we can do this only for chars < 128.) */

    case '[':
    class_optcount = 0;

    if (*(++ptr) == '^') ptr++;

    /* Written as a "do" so that an initial ']' is taken as data */

    if (*ptr != 0) do
      {
      /* Inside \Q...\E everything is literal except \E */

      if (inescq)
        {
        if (*ptr != '\\' || ptr[1] != 'E') goto NON_SPECIAL_CHARACTER;
        inescq = false;
        ptr += 1;
        continue;
        }

      /* Outside \Q...\E, check for escapes */

      if (*ptr == '\\')
        {
        int ch = check_escape(&ptr, errorptr, bracount, options, true);
        if (*errorptr != NULL) goto PCRE_ERROR_RETURN;

        /* \b is backspace inside a class */

        if (-ch == ESC_b) ch = '\b';

        /* \Q enters quoting mode */

        if (-ch == ESC_Q)
          {
          inescq = true;
          continue;
          }

        /* Handle escapes that turn into characters */

        if (ch >= 0)
          {
          class_optcount++;            /* for possible optimization */
          }
        else class_optcount = 10;      /* \d, \s etc; make sure > 1 */
        }

      /* Check the syntax for POSIX stuff. The bits we actually handle are
      checked during the real compile phase. */

      else if (*ptr == '[' && check_posix_syntax(ptr, &ptr, &compile_block))
        {
        ptr++;
        class_optcount = 10;    /* Make sure > 1 */
        }

      /* Anything else just increments the possible optimization count. If
      there are wide characters, we are going to have to use an XCLASS. */

      else
        {
        NON_SPECIAL_CHARACTER:
        class_optcount++;

        }
      }
    while (*(++ptr) != 0 && (inescq || *ptr != ']')); /* Concludes "do" above */

    if (*ptr == 0)                          /* Missing terminating ']' */
      {
      *errorptr = ERR6;
      goto PCRE_ERROR_RETURN;
      }

    /* We can optimize when there was only one optimizable character. Repeats
    for positive and negated single one-byte chars are handled by the general
    code. Here, we handle repeats for the class opcodes. */

    if (class_optcount == 1) length += 3; else
      {
      length += 33;

      /* A repeat needs either 1 or 5 bytes. If it is a possessive quantifier,
      we also need extra for wrapping the whole thing in a sub-pattern. */

      if (*ptr != 0 && ptr[1] == '{' && is_counted_repeat(ptr+2))
        {
        ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
        if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
        if ((min == 0 && (max == 1 || max == -1)) ||
          (min == 1 && max == -1))
            length++;
        else length += 5;
        if (ptr[1] == '+')
          {
          ptr++;
          length += 2 + 2*LINK_SIZE;
          }
        else if (ptr[1] == '?') ptr++;
        }
      }
    continue;

    /* Brackets may be genuine groups or special things */

    case '(':
    branch_newextra = 0;
    bracket_length = 1 + LINK_SIZE;

    /* Handle special forms of bracket, which all start (? */

    if (ptr[1] == '?')
      {
      int set, unset;
      int *optset;

      switch (c = ptr[2])
        {
        /* Skip over comments entirely */
        case '#':
        ptr += 3;
        while (*ptr != 0 && *ptr != ')') ptr++;
        if (*ptr == 0)
          {
          *errorptr = ERR18;
          goto PCRE_ERROR_RETURN;
          }
        continue;

        /* Non-referencing groups and lookaheads just move the pointer on, and
        then behave like a non-special bracket, except that they don't increment
        the count of extracting brackets. Ditto for the "once only" bracket,
        which is in Perl from version 5.005. */

        case ':':
        case '=':
        case '!':
        case '>':
        ptr += 2;
        break;

        /* (?R) specifies a recursive call to the regex, which is an extension
        to provide the facility which can be obtained by (?p{perl-code}) in
        Perl 5.6. In Perl 5.8 this has become (??{perl-code}).

        From PCRE 4.00, items such as (?3) specify subroutine-like "calls" to
        the appropriate numbered brackets. This includes both recursive and
        non-recursive calls. (?R) is now synonymous with (?0). */

        case 'R':
        ptr++;

        case '0': case '1': case '2': case '3': case '4':
        case '5': case '6': case '7': case '8': case '9':
        ptr += 2;
        if (c != 'R')
          while ((digitab[*(++ptr)] & ctype_digit) != 0);
        if (*ptr != ')')
          {
          *errorptr = ERR29;
          goto PCRE_ERROR_RETURN;
          }
        length += 1 + LINK_SIZE;

        /* If this item is quantified, it will get wrapped inside brackets so
        as to use the code for quantified brackets. We jump down and use the
        code that handles this for real brackets. */

        if (ptr[1] == '+' || ptr[1] == '*' || ptr[1] == '?' || ptr[1] == '{')
          {
          length += 2 + 2 * LINK_SIZE;       /* to make bracketed */
          duplength = 5 + 3 * LINK_SIZE;
          goto HANDLE_QUANTIFIED_BRACKETS;
          }
        continue;

        /* (?C) is an extension which provides "callout" - to provide a bit of
        the functionality of the Perl (?{...}) feature. An optional number may
        follow (default is zero). */

        case 'C':
        ptr += 2;
        while ((digitab[*(++ptr)] & ctype_digit) != 0);
        if (*ptr != ')')
          {
          *errorptr = ERR39;
          goto PCRE_ERROR_RETURN;
          }
        length += 2;
        continue;

        /* Named subpatterns are an extension copied from Python */

        case 'P':
        ptr += 3;
        if (*ptr == '<')
          {
          const uschar *p;    /* Don't amalgamate; some compilers */
          p = ++ptr;          /* grumble at autoincrement in declaration */
          while ((compile_block.ctypes[*ptr] & ctype_word) != 0) ptr++;
          if (*ptr != '>')
            {
            *errorptr = ERR42;
            goto PCRE_ERROR_RETURN;
            }
          name_count++;
          if (ptr - p > max_name_size) max_name_size = (ptr - p);
          break;
          }

        if (*ptr == '=' || *ptr == '>')
          {
          while ((compile_block.ctypes[*(++ptr)] & ctype_word) != 0);
          if (*ptr != ')')
            {
            *errorptr = ERR42;
            goto PCRE_ERROR_RETURN;
            }
          break;
          }

        /* Unknown character after (?P */

        *errorptr = ERR41;
        goto PCRE_ERROR_RETURN;

        /* Lookbehinds are in Perl from version 5.005 */

        case '<':
        ptr += 3;
        if (*ptr == '=' || *ptr == '!')
          {
          branch_newextra = 1 + LINK_SIZE;
          length += 1 + LINK_SIZE;         /* For the first branch */
          break;
          }
        *errorptr = ERR24;
        goto PCRE_ERROR_RETURN;

        /* Conditionals are in Perl from version 5.005. The bracket must either
        be followed by a number (for bracket reference) or by an assertion
        group, or (a PCRE extension) by 'R' for a recursion test. */

        case '(':
        if (ptr[3] == 'R' && ptr[4] == ')')
          {
          ptr += 4;
          length += 3;
          }
        else if ((digitab[ptr[3]] & ctype_digit) != 0)
          {
          ptr += 4;
          length += 3;
          while ((digitab[*ptr] & ctype_digit) != 0) ptr++;
          if (*ptr != ')')
            {
            *errorptr = ERR26;
            goto PCRE_ERROR_RETURN;
            }
          }
        else   /* An assertion must follow */
          {
          ptr++;   /* Can treat like ':' as far as spacing is concerned */
          if (ptr[2] != '?' ||
             (ptr[3] != '=' && ptr[3] != '!' && ptr[3] != '<') )
            {
            ptr += 2;    /* To get right offset in message */
            *errorptr = ERR28;
            goto PCRE_ERROR_RETURN;
            }
          }
        break;

        /* Else loop checking valid options until ) is met. Anything else is an
        error. If we are without any brackets, i.e. at top level, the settings
        act as if specified in the options, so massage the options immediately.
        This is for backward compatibility with Perl 5.004. */

        default:
        set = unset = 0;
        optset = &set;
        ptr += 2;

        for (;; ptr++)
          {
          c = *ptr;
          switch (c)
            {
            case 'i':
            *optset |= PCRE_CASELESS;
            continue;

            case 'm':
            *optset |= PCRE_MULTILINE;
            continue;

            case 's':
            *optset |= PCRE_DOTALL;
            continue;

            case 'x':
            *optset |= PCRE_EXTENDED;
            continue;

            case 'X':
            *optset |= PCRE_EXTRA;
            continue;

            case 'U':
            *optset |= PCRE_UNGREEDY;
            continue;

            case '-':
            optset = &unset;
            continue;

            /* A termination by ')' indicates an options-setting-only item; if
            this is at the very start of the pattern (indicated by item_count
            being zero), we use it to set the global options. This is helpful
            when analyzing the pattern for first characters, etc. Otherwise
            nothing is done here and it is handled during the compiling
            process.

            [Historical note: Up to Perl 5.8, options settings at top level
            were always global settings, wherever they appeared in the pattern.
            That is, they were equivalent to an external setting. From 5.8
            onwards, they apply only to what follows (which is what you might
            expect).] */

            case ')':
            if (item_count == 0)
              {
              options = (options | set) & (~unset);
              set = unset = 0;     /* To save length */
              item_count--;        /* To allow for several */
              }

            /* Fall through */

            /* A termination by ':' indicates the start of a nested group with
            the given options set. This is again handled at compile time, but
            we must allow for compiled space if any of the ims options are
            set. We also have to allow for resetting space at the end of
            the group, which is why 4 is added to the length and not just 2.
            If there are several changes of options within the same group, this
            will lead to an over-estimate on the length, but this shouldn't
            matter very much. We also have to allow for resetting options at
            the start of any alternations, which we do by setting
            branch_newextra to 2. Finally, we record whether the case-dependent
            flag ever changes within the regex. This is used by the "required
            character" code. */

            case ':':
            if (((set|unset) & PCRE_IMS) != 0)
              {
              length += 4;
              branch_newextra = 2;
              if (((set|unset) & PCRE_CASELESS) != 0) options |= PCRE_ICHANGED;
              }
            goto END_OPTIONS;

            /* Unrecognized option character */

            default:
            *errorptr = ERR12;
            goto PCRE_ERROR_RETURN;
            }
          }

        /* If we hit a closing bracket, that's it - this is a freestanding
        option-setting. We need to ensure that branch_extra is updated if
        necessary. The only values branch_newextra can have here are 0 or 2.
        If the value is 2, then branch_extra must either be 2 or 5, depending
        on whether this is a lookbehind group or not. */

        END_OPTIONS:
        if (c == ')')
          {
          if (branch_newextra == 2 &&
              (branch_extra == 0 || branch_extra == 1+LINK_SIZE))
            branch_extra += branch_newextra;
          continue;
          }

        /* If options were terminated by ':' control comes here. Fall through
        to handle the group below. */
        }
      }

    /* Extracting brackets must be counted so we can process escapes in a
    Perlish way. If the number exceeds EXTRACT_BASIC_MAX we are going to
    need an additional 3 bytes of store per extracting bracket. However, if
    PCRE_NO_AUTO)CAPTURE is set, unadorned brackets become non-capturing, so we
    must leave the count alone (it will aways be zero). */

    else if ((options & PCRE_NO_AUTO_CAPTURE) == 0)
      {
      bracount++;
      if (bracount > EXTRACT_BASIC_MAX) bracket_length += 3;
      }

    /* Save length for computing whole length at end if there's a repeat that
    requires duplication of the group. Also save the current value of
    branch_extra, and start the new group with the new value. If non-zero, this
    will either be 2 for a (?imsx: group, or 3 for a lookbehind assertion. */

    if (brastackptr >= sizeof(brastack)/sizeof(int))
      {
      *errorptr = ERR19;
      goto PCRE_ERROR_RETURN;
      }

    bralenstack[brastackptr] = static_cast<uschar>(branch_extra);
    branch_extra = branch_newextra;

    brastack[brastackptr++] = length;
    length += bracket_length;
    continue;

    /* Handle ket. Look for subsequent max/min; for certain sets of values we
    have to replicate this bracket up to that many times. If brastackptr is
    0 this is an unmatched bracket which will generate an error, but take care
    not to try to access brastack[-1] when computing the length and restoring
    the branch_extra value. */

    case ')':
    length += 1 + LINK_SIZE;
    if (brastackptr > 0)
      {
      duplength = length - brastack[--brastackptr];
      branch_extra = bralenstack[brastackptr];
      }
    else duplength = 0;

    /* The following code is also used when a recursion such as (?3) is
    followed by a quantifier, because in that case, it has to be wrapped inside
    brackets so that the quantifier works. The value of duplength must be
    set before arrival. */

    HANDLE_QUANTIFIED_BRACKETS:

    /* Leave ptr at the final char; for read_repeat_counts this happens
    automatically; for the others we need an increment. */

    if ((c = ptr[1]) == '{' && is_counted_repeat(ptr+2))
      {
      ptr = read_repeat_counts(ptr+2, &min, &max, errorptr);
      if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
      }
    else if (c == '*') { min = 0; max = -1; ptr++; }
    else if (c == '+') { min = 1; max = -1; ptr++; }
    else if (c == '?') { min = 0; max = 1;  ptr++; }
    else { min = 1; max = 1; }

    /* If the minimum is zero, we have to allow for an OP_BRAZERO before the
    group, and if the maximum is greater than zero, we have to replicate
    maxval-1 times; each replication acquires an OP_BRAZERO plus a nesting
    bracket set. */

    if (min == 0)
      {
      length++;
      if (max > 0) length += (max - 1) * (duplength + 3 + 2*LINK_SIZE);
      }

    /* When the minimum is greater than zero, we have to replicate up to
    minval-1 times, with no additions required in the copies. Then, if there
    is a limited maximum we have to replicate up to maxval-1 times allowing
    for a BRAZERO item before each optional copy and nesting brackets for all
    but one of the optional copies. */

    else
      {
      length += (min - 1) * duplength;
      if (max > min)   /* Need this test as max=-1 means no limit */
        length += (max - min) * (duplength + 3 + 2*LINK_SIZE)
          - (2 + 2*LINK_SIZE);
      }

    /* Allow space for once brackets for "possessive quantifier" */

    if (ptr[1] == '+')
      {
      ptr++;
      length += 2 + 2*LINK_SIZE;
      }
    continue;

    /* Non-special character. For a run of such characters the length required
    is the number of characters + 2, except that the maximum run length is
    MAXLIT. We won't get a skipped space or a non-data escape or the start of a
    # comment as the first character, so the length can't be zero. */

    NORMAL_CHAR:
    default:
    length += 2;
    runlength = 0;
    do
      {

      /* If in a \Q...\E sequence, check for end; otherwise it's a literal */
      if (inescq)
        {
        if (c == '\\' && ptr[1] == 'E')
          {
          inescq = false;
          ptr++;
          }
        else runlength++;
        continue;
        }

      /* Skip whitespace and comments for /x */

      if ((options & PCRE_EXTENDED) != 0)
        {
        if ((compile_block.ctypes[c] & ctype_space) != 0) continue;
        if (c == '#')
          {
          /* The space before the ; is to avoid a warning on a silly compiler
          on the Macintosh. */
          while ((c = *(++ptr)) != 0 && c != NEWLINE) ;
          continue;
          }
        }

      /* Backslash may introduce a data char or a metacharacter; stop the
      string before the latter. */

      if (c == '\\')
        {
        const uschar *saveptr = ptr;
        c = check_escape(&ptr, errorptr, bracount, options, false);
        if (*errorptr != NULL) goto PCRE_ERROR_RETURN;
        if (c < 0) { ptr = saveptr; break; }

        /* In UTF-8 mode, add on the number of additional bytes needed to
        encode this character, and save the total length in case this is a
        final char that is repeated. */

        }

      /* Ordinary character or single-char escape */

      runlength++;
      }

    /* This "while" is the end of the "do" above. */

    while (runlength < MAXLIT &&
      (compile_block.ctypes[c = *(++ptr)] & ctype_meta) == 0);

    /* If we hit a meta-character, back off to point to it */

    if (runlength < MAXLIT) ptr--;

    /* If the last char in the string is a UTF-8 multibyte character, we must
    set lastcharlength correctly. If it was specified as an escape, this will
    already have been done above. However, we also have to support in-line
    UTF-8 characters, so check backwards from where we are. */


    length += runlength;
    continue;
    }
  }

length += 2 + LINK_SIZE;    /* For final KET and END */

if (length > MAX_PATTERN_SIZE)
  {
  *errorptr = ERR20;
  return NULL;
  }

/* Compute the size of data block needed and get it, either from malloc or
externally provided function. */

size = length + sizeof(real_pcre) + name_count * (max_name_size + 3);
re = static_cast<real_pcre *>(malloc(size));

if (re == NULL)
  {
  *errorptr = ERR21;
  return NULL;
  }

/* Put in the magic number, and save the size, options, and table pointer */

re->magic_number = MAGIC_NUMBER;
re->size = size;
re->options = options;
re->tables = tables;
re->name_entry_size = static_cast<unsigned short>(max_name_size + 3);
re->name_count = static_cast<unsigned short>(name_count);

/* The starting points of the name/number translation table and of the code are
passed around in the compile data block. */

compile_block.names_found = 0;
compile_block.name_entry_size = max_name_size + 3;
compile_block.name_table = (uschar *)re + sizeof(real_pcre);
codestart = compile_block.name_table + re->name_entry_size * re->name_count;
compile_block.start_code = codestart;
compile_block.req_varyopt = 0;

/* Set up a starting, non-extracting bracket, then compile the expression. On
error, *errorptr will be set non-NULL, so we don't need to look at the result
of the function here. */

ptr = (const uschar *)pattern;
code = (uschar *)codestart;
*code = OP_BRA;
bracount = 0;
(void)compile_regex(options, options & PCRE_IMS, &bracount, &code, &ptr,
  errorptr, false, 0, &firstbyte, &reqbyte, NULL, &compile_block);
re->top_bracket = static_cast<unsigned short>(bracount);
re->top_backref = static_cast<unsigned short>(compile_block.top_backref);

/* If not reached end of pattern on success, there's an excess bracket. */

if (*errorptr == NULL && *ptr != 0) *errorptr = ERR22;

/* Fill in the terminating state and check for disastrous overflow, but
if debugging, leave the test till after things are printed out. */

*code++ = OP_END;

if (code - codestart > length) *errorptr = ERR23;

/* Give an error if there's back reference to a non-existent capturing
subpattern. */

if (re->top_backref > re->top_bracket) *errorptr = ERR15;

/* Failed to compile, or error while post-processing */

if (*errorptr != NULL)
  {
  free(re);
  PCRE_ERROR_RETURN:
  *erroroffset = ptr - (const uschar *)pattern;
  return NULL;
  }

/* If the anchored option was not passed, set the flag if we can determine that
the pattern is anchored by virtue of ^ characters or \A or anything else (such
as starting with .* when DOTALL is set).

Otherwise, if we know what the first character has to be, save it, because that
speeds up unanchored matches no end. If not, see if we can set the
PCRE_STARTLINE flag. This is helpful for multiline matches when all branches
start with ^. and also when all branches start with .* for non-DOTALL matches.
*/

if ((options & PCRE_ANCHORED) == 0)
  {
  int temp_options = options;
  if (is_anchored(codestart, &temp_options, 0, compile_block.backref_map))
    re->options |= PCRE_ANCHORED;
  else
    {
    if (firstbyte < 0)
      firstbyte = find_firstassertedchar(codestart, &temp_options, false);
    if (firstbyte >= 0)   /* Remove caseless flag for non-caseable chars */
      {
      int ch = firstbyte & 255;
      re->first_byte = static_cast<unsigned short>(((firstbyte & REQ_CASELESS) != 0 &&
         compile_block.fcc[ch] == ch)? ch : firstbyte);
      re->options |= PCRE_FIRSTSET;
      }
    else if (is_startline(codestart, 0, compile_block.backref_map))
      re->options |= PCRE_STARTLINE;
    }
  }

/* For an anchored pattern, we use the "required byte" only if it follows a
variable length item in the regex. Remove the caseless flag for non-caseable
chars. */

if (reqbyte >= 0 &&
     ((re->options & PCRE_ANCHORED) == 0 || (reqbyte & REQ_VARY) != 0))
  {
  int ch = reqbyte & 255;
  re->req_byte = static_cast<unsigned short>(((reqbyte & REQ_CASELESS) != 0 &&
    compile_block.fcc[ch] == ch)? (reqbyte & ~REQ_CASELESS) : reqbyte);
  re->options |= PCRE_REQCHSET;
  }

return (pcre *)re;
}



/*************************************************
*          Match a back-reference                *
*************************************************/

/* If a back reference hasn't been set, the length that is passed is greater
than the number of characters left in the string, so the match fails.

Arguments:
  offset      index into the offset vector
  eptr        points into the subject
  length      length to be matched
  md          points to match data block
  ims         the ims flags

Returns:      true if matched
*/

static bool
match_ref
(
    int offset,
    register const uschar *eptr,
    int length,
    match_data *md,
    unsigned long int ims
)
{
    const uschar *p = md->start_subject + md->offset_vector[offset];

    /* Always fail if not enough characters left */

    if (length > md->end_subject - eptr)
    {
        return false;
    }

    /* Separate the caselesss case for speed */

    if ((ims & PCRE_CASELESS) != 0)
    {
        while (length-- > 0)
        {
            if (md->lcc[*p] != md->lcc[*eptr])
            {
                p++;
                eptr++;
                return false;
            }
            p++;
            eptr++;
        }
    }
    else
    {
        while (length-- > 0)
        {
            if (*p != *eptr)
            {
                p++;
                eptr++;
                return false;
            }
            p++;
            eptr++;
        }
    }

    return true;
}

/***************************************************************************
****************************************************************************
                   RECURSION IN THE match() FUNCTION

The match() function is highly recursive. Some regular expressions can cause
it to recurse thousands of times. I was writing for Unix, so I just let it
call itself recursively. This uses the stack for saving everything that has
to be saved for a recursive call. On Unix, the stack can be large, and this
works fine.

It turns out that on non-Unix systems there are problems with programs that
use a lot of stack. (This despite the fact that every last chip has oodles
of memory these days, and techniques for extending the stack have been known
for decades.) So....

There is a fudge, triggered by defining NO_RECURSE, which avoids recursive
calls by keeping local variables that need to be preserved in blocks of memory
obtained from malloc instead instead of on the stack. Macros are used to
achieve this so that the actual code doesn't look very different to what it
always used to.
****************************************************************************
***************************************************************************/


/* These versions of the macros use the stack, as normal */

#define REGISTER register
#define RMATCH(rx,ra,rb,rc,rd,re,rf,rg) rx = match(ra,rb,rc,rd,re,rf,rg)
#define RRETURN(ra) return ra

/***************************************************************************
***************************************************************************/


/*************************************************
*         Match from current position            *
*************************************************/

/* On entry ecode points to the first opcode, and eptr to the first character
in the subject string, while eptrb holds the value of eptr at the start of the
last bracketed group - used for breaking infinite loops matching zero-length
strings. This function is called recursively in many circumstances. Whenever it
returns a negative (error) response, the outer incarnation must also return the
same response.

Performance note: It might be tempting to extract commonly used fields from the
md structure (e.g. utf8, end_subject) into individual variables to improve
performance. Tests using gcc on a SPARC disproved this; in the first case, it
made performance worse.

Arguments:
   eptr        pointer in subject
   ecode       position in code
   offset_top  current top pointer
   md          pointer to "static" info for the match
   ims         current /i, /m, and /s options
   eptrb       pointer to chain of blocks containing eptr at start of
                 brackets - for testing for empty matches
   flags       can contain
                 match_condassert - this is an assertion condition
                 match_isgroup - this is the start of a bracketed group

Returns:       MATCH_MATCH if matched            )  these values are >= 0
               MATCH_NOMATCH if failed to match  )
               a negative PCRE_ERROR_xxx value if aborted by an error condition
                 (e.g. stopped by recursion limit)
*/

static int
match(REGISTER const uschar *eptr, REGISTER const uschar *ecode,
  int offset_top, match_data *md, unsigned long int ims, eptrblock *eptrb,
  int flags)
{
/* These variables do not need to be preserved over recursion in this function,
so they can be ordinary variables in all cases. Mark them with "register"
because they are used a lot in loops. */

register int rrc;    /* Returns from recursive calls */
register int i;      /* Used for loops not involving calls to RMATCH() */
register int c;      /* Character values not kept over RMATCH() calls */

/* When recursion is not being used, all "local" variables that have to be
preserved over calls to RMATCH() are part of a "frame" which is obtained from
heap storage. Set up the top-level frame here; others are obtained from the
heap whenever RMATCH() does a "recursion". See the macro definitions above. */

#define fi i
#define fc c

const uschar *callpat;             /* Many of these variables are used ony */
                                   /* small blocks of the code. My normal  */
const uschar *data;                /* style of coding would have declared  */
                                   /* them within each of those blocks.    */
const uschar *next;                /* However, in order to accommodate the */
const uschar *pp;                  /* version of this code that uses an    */
const uschar *prev;                /* external "stack" implemented on the  */
const uschar *saved_eptr;          /* heap, it is easier to declare them   */
                                   /* all here, so the declarations can    */
recursion_info new_recursive;      /* be cut out in a block. The only      */
                                   /* declarations within blocks below are */
bool cur_is_word;                  /* for variables that do not have to    */
bool condition;                    /* be preserved over a recursive call   */
bool minimize;                     /* to RMATCH().                         */
bool prev_is_word;

unsigned long int original_ims;

int ctype;
int length;
int max;
int min;
int number;
int offset;
int op;
int save_capture_last;
int save_offset1, save_offset2, save_offset3;
int stacksave[REC_STACK_SAVE_MAX];

eptrblock newptrb;

/* OK, now we can get on with the real code of the function. Recursion is
specified by the macros RMATCH and RRETURN. When NO_RECURSE is *not* defined,
these just turn into a recursive call to match() and a "return", respectively.
However, RMATCH isn't like a function call because it's quite a complicated
macro. It has to be used in one particular way. This shouldn't, however, impact
performance when true recursion is being used. */

if (md->match_call_count++ >= md->match_limit) RRETURN(PCRE_ERROR_MATCHLIMIT);

original_ims = ims;    /* Save for resetting on ')' */

/* At the start of a bracketed group, add the current subject pointer to the
stack of such pointers, to be re-instated at the end of the group when we hit
the closing ket. When match() is called in other circumstances, we don't add to
this stack. */

if ((flags & match_isgroup) != 0)
  {
  newptrb.epb_prev = eptrb;
  newptrb.epb_saved_eptr = eptr;
  eptrb = &newptrb;
  }

/* Now start processing the operations. */

for (;!MuxAlarm.bAlarmed;)
  {
  op = *ecode;
  minimize = false;

  /* Opening capturing bracket. If there is space in the offset vector, save
  the current subject position in the working slot at the top of the vector. We
  mustn't change the current values of the data slot, because they may be set
  from a previous iteration of this group, and be referred to by a reference
  inside the group.

  If the bracket fails to match, we need to restore this value and also the
  values of the final offsets, in case they were set by a previous iteration of
  the same bracket.

  If there isn't enough space in the offset vector, treat this as if it were a
  non-capturing bracket. Don't worry about setting the flag for the error case
  here; that is handled in the code for KET. */

  if (op > OP_BRA)
    {
    number = op - OP_BRA;

    /* For extended extraction brackets (large number), we have to fish out the
    number from a dummy opcode at the start. */

    if (number > EXTRACT_BASIC_MAX)
      number = GET2(ecode, 2+LINK_SIZE);
    offset = number << 1;

    if (offset < md->offset_max)
      {
      save_offset1 = md->offset_vector[offset];
      save_offset2 = md->offset_vector[offset+1];
      save_offset3 = md->offset_vector[md->offset_end - number];
      save_capture_last = md->capture_last;

      DPRINTF(("saving %d %d %d\n", save_offset1, save_offset2, save_offset3));
      md->offset_vector[md->offset_end - number] = eptr - md->start_subject;

      do
        {
        RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
          match_isgroup);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        md->capture_last = save_capture_last;
        ecode += GET(ecode, 1);
        }
      while (*ecode == OP_ALT);

      DPRINTF(("bracket %d failed\n", number));

      md->offset_vector[offset] = save_offset1;
      md->offset_vector[offset+1] = save_offset2;
      md->offset_vector[md->offset_end - number] = save_offset3;

      RRETURN(MATCH_NOMATCH);
      }

    /* Insufficient room for saving captured contents */

    else op = OP_BRA;
    }

  /* Other types of node can be handled by a switch */

  switch(op)
    {
    case OP_BRA:     /* Non-capturing bracket: optimized */
    DPRINTF(("start bracket 0\n"));
    do
      {
      RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
        match_isgroup);
      if (rrc != MATCH_NOMATCH) RRETURN(rrc);
      ecode += GET(ecode, 1);
      }
    while (*ecode == OP_ALT);
    DPRINTF(("bracket 0 failed\n"));
    RRETURN(MATCH_NOMATCH);

    /* Conditional group: compilation checked that there are no more than
    two branches. If the condition is false, skipping the first branch takes us
    past the end if there is only one branch, but that's OK because that is
    exactly what going to the ket would do. */

    case OP_COND:
    if (ecode[LINK_SIZE+1] == OP_CREF) /* Condition extract or recurse test */
      {
      offset = GET2(ecode, LINK_SIZE+2) << 1;  /* Doubled ref number */
      condition = (offset == CREF_RECURSE * 2)?
        (md->recursive != NULL) :
        (offset < offset_top && md->offset_vector[offset] >= 0);
      RMATCH(rrc, eptr, ecode + (condition?
        (LINK_SIZE + 4) : (LINK_SIZE + 1 + GET(ecode, 1))),
        offset_top, md, ims, eptrb, match_isgroup);
      RRETURN(rrc);
      }

    /* The condition is an assertion. Call match() to evaluate it - setting
    the final argument true causes it to stop at the end of an assertion. */

    else
      {
      RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
          match_condassert | match_isgroup);
      if (rrc == MATCH_MATCH)
        {
        ecode += 1 + LINK_SIZE + GET(ecode, LINK_SIZE+2);
        while (*ecode == OP_ALT) ecode += GET(ecode, 1);
        }
      else if (rrc != MATCH_NOMATCH)
        {
        RRETURN(rrc);         /* Need braces because of following else */
        }
      else ecode += GET(ecode, 1);
      RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb,
        match_isgroup);
      RRETURN(rrc);
      }
    /* Control never reaches here */

    /* Skip over conditional reference or large extraction number data if
    encountered. */

    case OP_CREF:
    case OP_BRANUMBER:
    ecode += 3;
    break;

    /* End of the pattern. If we are in a recursion, we should restore the
    offsets appropriately and continue from after the call. */

    case OP_END:
    if (md->recursive != NULL && md->recursive->group_num == 0)
      {
      recursion_info *rec = md->recursive;
      DPRINTF(("Hit the end in a (?0) recursion\n"));
      md->recursive = rec->prevrec;
      memmove(md->offset_vector, rec->offset_save,
        rec->saved_max * sizeof(int));
      md->start_match = rec->save_start;
      ims = original_ims;
      ecode = rec->after_call;
      break;
      }

    /* Otherwise, if PCRE_NOTEMPTY is set, fail if we have matched an empty
    string - backtracking will then try other alternatives, if any. */

    if (md->notempty && eptr == md->start_match) RRETURN(MATCH_NOMATCH);
    md->end_match_ptr = eptr;          /* Record where we ended */
    md->end_offset_top = offset_top;   /* and how many extracts were taken */
    RRETURN(MATCH_MATCH);

    /* Change option settings */

    case OP_OPT:
    ims = ecode[1];
    ecode += 2;
    DPRINTF(("ims set to %02lx\n", ims));
    break;

    /* Assertion brackets. Check the alternative branches in turn - the
    matching won't pass the KET for an assertion. If any one branch matches,
    the assertion is true. Lookbehind assertions have an OP_REVERSE item at the
    start of each branch to move the current point backwards, so the code at
    this level is identical to the lookahead case. */

    case OP_ASSERT:
    case OP_ASSERTBACK:
    do
      {
      RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
        match_isgroup);
      if (rrc == MATCH_MATCH) break;
      if (rrc != MATCH_NOMATCH) RRETURN(rrc);
      ecode += GET(ecode, 1);
      }
    while (*ecode == OP_ALT);
    if (*ecode == OP_KET) RRETURN(MATCH_NOMATCH);

    /* If checking an assertion for a condition, return MATCH_MATCH. */

    if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);

    /* Continue from after the assertion, updating the offsets high water
    mark, since extracts may have been taken during the assertion. */

    do ecode += GET(ecode,1); while (*ecode == OP_ALT);
    ecode += 1 + LINK_SIZE;
    offset_top = md->end_offset_top;
    continue;

    /* Negative assertion: all branches must fail to match */

    case OP_ASSERT_NOT:
    case OP_ASSERTBACK_NOT:
    do
      {
      RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, NULL,
        match_isgroup);
      if (rrc == MATCH_MATCH) RRETURN(MATCH_NOMATCH);
      if (rrc != MATCH_NOMATCH) RRETURN(rrc);
      ecode += GET(ecode,1);
      }
    while (*ecode == OP_ALT);

    if ((flags & match_condassert) != 0) RRETURN(MATCH_MATCH);

    ecode += 1 + LINK_SIZE;
    continue;

    /* Move the subject pointer back. This occurs only at the start of
    each branch of a lookbehind assertion. If we are too close to the start to
    move back, this match function fails. When working with UTF-8 we move
    back a number of characters, not bytes. */

    case OP_REVERSE:

    /* No UTF-8 support, or not in UTF-8 mode: count is byte count */

      {
      eptr -= GET(ecode,1);
      if (eptr < md->start_subject) RRETURN(MATCH_NOMATCH);
      }

    /* Skip to next op code */

    ecode += 1 + LINK_SIZE;
    break;

    /* The callout item calls an external function, if one is provided, passing
    details of the match so far. This is mainly for debugging, though the
    function is able to force a failure. */

    case OP_CALLOUT:
    if (pcre_callout != NULL)
      {
      pcre_callout_block cb;
      cb.version          = 0;   /* Version 0 of the callout block */
      cb.callout_number   = ecode[1];
      cb.offset_vector    = md->offset_vector;
      cb.subject          = (const char *)md->start_subject;
      cb.subject_length   = md->end_subject - md->start_subject;
      cb.start_match      = md->start_match - md->start_subject;
      cb.current_position = eptr - md->start_subject;
      cb.capture_top      = offset_top/2;
      cb.capture_last     = md->capture_last;
      cb.callout_data     = md->callout_data;
      if ((rrc = (*pcre_callout)(&cb)) > 0) RRETURN(MATCH_NOMATCH);
      if (rrc < 0) RRETURN(rrc);
      }
    ecode += 2;
    break;

    /* Recursion either matches the current regex, or some subexpression. The
    offset data is the offset to the starting bracket from the start of the
    whole pattern. (This is so that it works from duplicated subpatterns.)

    If there are any capturing brackets started but not finished, we have to
    save their starting points and reinstate them after the recursion. However,
    we don't know how many such there are (offset_top records the completed
    total) so we just have to save all the potential data. There may be up to
    65535 such values, which is too large to put on the stack, but using malloc
    for small numbers seems expensive. As a compromise, the stack is used when
    there are no more than REC_STACK_SAVE_MAX values to store; otherwise malloc
    is used. A problem is what to do if the malloc fails ... there is no way of
    returning to the top level with an error. Save the top REC_STACK_SAVE_MAX
    values on the stack, and accept that the rest may be wrong.

    There are also other values that have to be saved. We use a chained
    sequence of blocks that actually live on the stack. Thanks to Robin Houston
    for the original version of this logic. */

    case OP_RECURSE:
      {
      callpat = md->start_code + GET(ecode, 1);
      new_recursive.group_num = *callpat - OP_BRA;

      /* For extended extraction brackets (large number), we have to fish out
      the number from a dummy opcode at the start. */

      if (new_recursive.group_num > EXTRACT_BASIC_MAX)
        new_recursive.group_num = GET2(callpat, 2+LINK_SIZE);

      /* Add to "recursing stack" */

      new_recursive.prevrec = md->recursive;
      md->recursive = &new_recursive;

      /* Find where to continue from afterwards */

      ecode += 1 + LINK_SIZE;
      new_recursive.after_call = ecode;

      /* Now save the offset data. */

      new_recursive.saved_max = md->offset_end;
      if (new_recursive.saved_max <= REC_STACK_SAVE_MAX)
        new_recursive.offset_save = stacksave;
      else
        {
        new_recursive.offset_save =
          static_cast<int *>(malloc(new_recursive.saved_max * sizeof(int)));
        if (new_recursive.offset_save == NULL) RRETURN(PCRE_ERROR_NOMEMORY);
        }

      memcpy(new_recursive.offset_save, md->offset_vector,
            new_recursive.saved_max * sizeof(int));
      new_recursive.save_start = md->start_match;
      md->start_match = eptr;

      /* OK, now we can do the recursion. For each top-level alternative we
      restore the offset and recursion data. */

      DPRINTF(("Recursing into group %d\n", new_recursive.group_num));
      do
        {
        RMATCH(rrc, eptr, callpat + 1 + LINK_SIZE, offset_top, md, ims,
            eptrb, match_isgroup);
        if (rrc == MATCH_MATCH)
          {
          md->recursive = new_recursive.prevrec;
          if (new_recursive.offset_save != stacksave)
            free(new_recursive.offset_save);
          RRETURN(MATCH_MATCH);
          }
        else if (rrc != MATCH_NOMATCH) RRETURN(rrc);

        md->recursive = &new_recursive;
        memcpy(md->offset_vector, new_recursive.offset_save,
            new_recursive.saved_max * sizeof(int));
        callpat += GET(callpat, 1);
        }
      while (*callpat == OP_ALT);

      DPRINTF(("Recursion didn't match\n"));
      md->recursive = new_recursive.prevrec;
      if (new_recursive.offset_save != stacksave)
        free(new_recursive.offset_save);
      RRETURN(MATCH_NOMATCH);
      }
    /* Control never reaches here */

    /* "Once" brackets are like assertion brackets except that after a match,
    the point in the subject string is not moved back. Thus there can never be
    a move back into the brackets. Friedl calls these "atomic" subpatterns.
    Check the alternative branches in turn - the matching won't pass the KET
    for this kind of subpattern. If any one branch matches, we carry on as at
    the end of a normal bracket, leaving the subject pointer. */

    case OP_ONCE:
      {
      prev = ecode;
      saved_eptr = eptr;

      do
        {
        RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims,
          eptrb, match_isgroup);
        if (rrc == MATCH_MATCH) break;
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        ecode += GET(ecode,1);
        }
      while (*ecode == OP_ALT);

      /* If hit the end of the group (which could be repeated), fail */

      if (*ecode != OP_ONCE && *ecode != OP_ALT) RRETURN(MATCH_NOMATCH);

      /* Continue as from after the assertion, updating the offsets high water
      mark, since extracts may have been taken. */

      do ecode += GET(ecode,1); while (*ecode == OP_ALT);

      offset_top = md->end_offset_top;
      eptr = md->end_match_ptr;

      /* For a non-repeating ket, just continue at this level. This also
      happens for a repeating ket if no characters were matched in the group.
      This is the forcible breaking of infinite loops as implemented in Perl
      5.005. If there is an options reset, it will get obeyed in the normal
      course of events. */

      if (*ecode == OP_KET || eptr == saved_eptr)
        {
        ecode += 1+LINK_SIZE;
        break;
        }

      /* The repeating kets try the rest of the pattern or restart from the
      preceding bracket, in the appropriate order. We need to reset any options
      that changed within the bracket before re-running it, so check the next
      opcode. */

      if (ecode[1+LINK_SIZE] == OP_OPT)
        {
        ims = (ims & ~PCRE_IMS) | ecode[4];
        DPRINTF(("ims set to %02lx at group repeat\n", ims));
        }

      if (*ecode == OP_KETRMIN)
        {
        RMATCH(rrc, eptr, ecode + 1 + LINK_SIZE, offset_top, md, ims, eptrb, 0);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        }
      else  /* OP_KETRMAX */
        {
        RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        }
      }
    RRETURN(MATCH_NOMATCH);

    /* An alternation is the end of a branch; scan along to find the end of the
    bracketed group and go to there. */

    case OP_ALT:
    do ecode += GET(ecode,1); while (*ecode == OP_ALT);
    break;

    /* BRAZERO and BRAMINZERO occur just before a bracket group, indicating
    that it may occur zero times. It may repeat infinitely, or not at all -
    i.e. it could be ()* or ()? in the pattern. Brackets with fixed upper
    repeat limits are compiled as a number of copies, with the optional ones
    preceded by BRAZERO or BRAMINZERO. */

    case OP_BRAZERO:
      {
      next = ecode+1;
      RMATCH(rrc, eptr, next, offset_top, md, ims, eptrb, match_isgroup);
      if (rrc != MATCH_NOMATCH) RRETURN(rrc);
      do next += GET(next,1); while (*next == OP_ALT);
      ecode = next + 1+LINK_SIZE;
      }
    break;

    case OP_BRAMINZERO:
      {
      next = ecode+1;
      do next += GET(next,1); while (*next == OP_ALT);
      RMATCH(rrc, eptr, next + 1+LINK_SIZE, offset_top, md, ims, eptrb,
        match_isgroup);
      if (rrc != MATCH_NOMATCH) RRETURN(rrc);
      ecode++;
      }
    break;

    /* End of a group, repeated or non-repeating. If we are at the end of
    an assertion "group", stop matching and return MATCH_MATCH, but record the
    current high water mark for use by positive assertions. Do this also
    for the "once" (not-backup up) groups. */

    case OP_KET:
    case OP_KETRMIN:
    case OP_KETRMAX:
      {
      prev = ecode - GET(ecode, 1);
      saved_eptr = eptrb->epb_saved_eptr;

      /* Back up the stack of bracket start pointers. */

      eptrb = eptrb->epb_prev;

      if (*prev == OP_ASSERT || *prev == OP_ASSERT_NOT ||
          *prev == OP_ASSERTBACK || *prev == OP_ASSERTBACK_NOT ||
          *prev == OP_ONCE)
        {
        md->end_match_ptr = eptr;      /* For ONCE */
        md->end_offset_top = offset_top;
        RRETURN(MATCH_MATCH);
        }

      /* In all other cases except a conditional group we have to check the
      group number back at the start and if necessary complete handling an
      extraction by setting the offsets and bumping the high water mark. */

      if (*prev != OP_COND)
        {
        number = *prev - OP_BRA;

        /* For extended extraction brackets (large number), we have to fish out
        the number from a dummy opcode at the start. */

        if (number > EXTRACT_BASIC_MAX) number = GET2(prev, 2+LINK_SIZE);
        offset = number << 1;

        /* Test for a numbered group. This includes groups called as a result
        of recursion. Note that whole-pattern recursion is coded as a recurse
        into group 0, so it won't be picked up here. Instead, we catch it when
        the OP_END is reached. */

        if (number > 0)
          {
          md->capture_last = number;
          if (offset >= md->offset_max) md->offset_overflow = true; else
            {
            md->offset_vector[offset] =
              md->offset_vector[md->offset_end - number];
            md->offset_vector[offset+1] = eptr - md->start_subject;
            if (offset_top <= offset) offset_top = offset + 2;
            }

          /* Handle a recursively called group. Restore the offsets
          appropriately and continue from after the call. */

          if (md->recursive != NULL && md->recursive->group_num == number)
            {
            recursion_info *rec = md->recursive;
            DPRINTF(("Recursion (%d) succeeded - continuing\n", number));
            md->recursive = rec->prevrec;
            md->start_match = rec->save_start;
            memcpy(md->offset_vector, rec->offset_save,
              rec->saved_max * sizeof(int));
            ecode = rec->after_call;
            ims = original_ims;
            break;
            }
          }
        }

      /* Reset the value of the ims flags, in case they got changed during
      the group. */

      ims = original_ims;
      DPRINTF(("ims reset to %02lx\n", ims));

      /* For a non-repeating ket, just continue at this level. This also
      happens for a repeating ket if no characters were matched in the group.
      This is the forcible breaking of infinite loops as implemented in Perl
      5.005. If there is an options reset, it will get obeyed in the normal
      course of events. */

      if (*ecode == OP_KET || eptr == saved_eptr)
        {
        ecode += 1 + LINK_SIZE;
        break;
        }

      /* The repeating kets try the rest of the pattern or restart from the
      preceding bracket, in the appropriate order. */

      if (*ecode == OP_KETRMIN)
        {
        RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        }
      else  /* OP_KETRMAX */
        {
        RMATCH(rrc, eptr, prev, offset_top, md, ims, eptrb, match_isgroup);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        RMATCH(rrc, eptr, ecode + 1+LINK_SIZE, offset_top, md, ims, eptrb, 0);
        if (rrc != MATCH_NOMATCH) RRETURN(rrc);
        }
      }

    RRETURN(MATCH_NOMATCH);

    /* Start of subject unless notbol, or after internal newline if multiline */

    case OP_CIRC:
    if (md->notbol && eptr == md->start_subject) RRETURN(MATCH_NOMATCH);
    if ((ims & PCRE_MULTILINE) != 0)
      {
      if (eptr != md->start_subject && eptr[-1] != NEWLINE)
        RRETURN(MATCH_NOMATCH);
      ecode++;
      break;
      }
    /* ... else fall through */

    /* Start of subject assertion */

    case OP_SOD:
    if (eptr != md->start_subject) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* Start of match assertion */

    case OP_SOM:
    if (eptr != md->start_subject + md->start_offset) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* Assert before internal newline if multiline, or before a terminating
    newline unless endonly is set, else end of subject unless noteol is set. */

    case OP_DOLL:
    if ((ims & PCRE_MULTILINE) != 0)
      {
      if (eptr < md->end_subject)
        { if (*eptr != NEWLINE) RRETURN(MATCH_NOMATCH); }
      else
        { if (md->noteol) RRETURN(MATCH_NOMATCH); }
      ecode++;
      break;
      }
    else
      {
      if (md->noteol) RRETURN(MATCH_NOMATCH);
      if (!md->endonly)
        {
        if (eptr < md->end_subject - 1 ||
           (eptr == md->end_subject - 1 && *eptr != NEWLINE))
          RRETURN(MATCH_NOMATCH);
        ecode++;
        break;
        }
      }
    /* ... else fall through */

    /* End of subject assertion (\z) */

    case OP_EOD:
    if (eptr < md->end_subject) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* End of subject or ending \n assertion (\Z) */

    case OP_EODN:
    if (eptr < md->end_subject - 1 ||
       (eptr == md->end_subject - 1 && *eptr != NEWLINE)) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* Word boundary assertions */

    case OP_NOT_WORD_BOUNDARY:
    case OP_WORD_BOUNDARY:
      {

      /* Find out if the previous and current characters are "word" characters.
      It takes a bit more work in UTF-8 mode. Characters > 255 are assumed to
      be "non-word" characters. */


      /* More streamlined when not in UTF-8 mode */

        {
        prev_is_word = (eptr != md->start_subject) &&
          ((md->ctypes[eptr[-1]] & ctype_word) != 0);
        cur_is_word = (eptr < md->end_subject) &&
          ((md->ctypes[*eptr] & ctype_word) != 0);
        }

      /* Now see if the situation is what we want */

      if ((*ecode++ == OP_WORD_BOUNDARY)?
           cur_is_word == prev_is_word : cur_is_word != prev_is_word)
        RRETURN(MATCH_NOMATCH);
      }
    break;

    /* Match a single character type; inline for speed */

    case OP_ANY:
    if ((ims & PCRE_DOTALL) == 0 && eptr < md->end_subject && *eptr == NEWLINE)
      RRETURN(MATCH_NOMATCH);
    if (eptr++ >= md->end_subject) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* Match a single byte, even in UTF-8 mode. This opcode really does match
    any byte, even newline, independent of the setting of PCRE_DOTALL. */

    case OP_ANYBYTE:
    if (eptr++ >= md->end_subject) RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_NOT_DIGIT:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_digit) != 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_DIGIT:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_digit) == 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_NOT_WHITESPACE:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_space) != 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_WHITESPACE:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_space) == 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_NOT_WORDCHAR:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_word) != 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    case OP_WORDCHAR:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    GETCHARINCTEST(c, eptr);
    if (
       (md->ctypes[c] & ctype_word) == 0
       )
      RRETURN(MATCH_NOMATCH);
    ecode++;
    break;

    /* Match a back reference, possibly repeatedly. Look past the end of the
    item to see if there is repeat information following. The code is similar
    to that for character classes, but repeated for efficiency. Then obey
    similar code to character type repeats - written out again for speed.
    However, if the referenced string is the empty string, always treat
    it as matched, any number of times (otherwise there could be infinite
    loops). */

    case OP_REF:
      {
      offset = GET2(ecode, 1) << 1;               /* Doubled ref number */
      ecode += 3;                                     /* Advance past item */

      /* If the reference is unset, set the length to be longer than the amount
      of subject left; this ensures that every attempt at a match fails. We
      can't just fail here, because of the possibility of quantifiers with zero
      minima. */

      length = (offset >= offset_top || md->offset_vector[offset] < 0)?
        md->end_subject - eptr + 1 :
        md->offset_vector[offset+1] - md->offset_vector[offset];

      /* Set up for repetition, or handle the non-repeated case */

      switch (*ecode)
        {
        case OP_CRSTAR:
        case OP_CRMINSTAR:
        case OP_CRPLUS:
        case OP_CRMINPLUS:
        case OP_CRQUERY:
        case OP_CRMINQUERY:
        c = *ecode++ - OP_CRSTAR;
        minimize = (c & 1) != 0;
        min = rep_min[c];                 /* Pick up values from tables; */
        max = rep_max[c];                 /* zero for max => infinity */
        if (max == 0) max = INT_MAX;
        break;

        case OP_CRRANGE:
        case OP_CRMINRANGE:
        minimize = (*ecode == OP_CRMINRANGE);
        min = GET2(ecode, 1);
        max = GET2(ecode, 3);
        if (max == 0) max = INT_MAX;
        ecode += 5;
        break;

        default:               /* No repeat follows */
        if (!match_ref(offset, eptr, length, md, ims)) RRETURN(MATCH_NOMATCH);
        eptr += length;
        continue;              /* With the main loop */
        }

      /* If the length of the reference is zero, just continue with the
      main loop. */

      if (length == 0) continue;

      /* First, ensure the minimum number of matches are present. We get back
      the length of the reference string explicitly rather than passing the
      address of eptr, so that eptr can be a register variable. */

      for (i = 1; i <= min; i++)
        {
        if (!match_ref(offset, eptr, length, md, ims)) RRETURN(MATCH_NOMATCH);
        eptr += length;
        }

      /* If min = max, continue at the same level without recursion.
      They are not both allowed to be zero. */

      if (min == max) continue;

      /* If minimizing, keep trying and advancing the pointer */

      if (minimize)
        {
        for (fi = min;; fi++)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          if (fi >= max || !match_ref(offset, eptr, length, md, ims))
            RRETURN(MATCH_NOMATCH);
          eptr += length;
          }
        /* Control never gets here */
        }

      /* If maximizing, find the longest string and work backwards */

      else
        {
        pp = eptr;
        for (i = min; i < max; i++)
          {
          if (!match_ref(offset, eptr, length, md, ims)) break;
          eptr += length;
          }
        while (eptr >= pp)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          eptr -= length;
          }
        RRETURN(MATCH_NOMATCH);
        }
      }
    /* Control never gets here */



    /* Match a bit-mapped character class, possibly repeatedly. This op code is
    used when all the characters in the class have values in the range 0-255.
    The only difference between OP_CLASS and OP_NCLASS occurs when a data
    character outside the range is encountered.

    First, look past the end of the item to see if there is repeat information
    following. Then obey similar code to character type repeats - written out
    again for speed. */

    case OP_NCLASS:
    case OP_CLASS:
      {
      data = ecode + 1;                /* Save for matching */
      ecode += 33;                     /* Advance past the item */

      switch (*ecode)
        {
        case OP_CRSTAR:
        case OP_CRMINSTAR:
        case OP_CRPLUS:
        case OP_CRMINPLUS:
        case OP_CRQUERY:
        case OP_CRMINQUERY:
        c = *ecode++ - OP_CRSTAR;
        minimize = (c & 1) != 0;
        min = rep_min[c];                 /* Pick up values from tables; */
        max = rep_max[c];                 /* zero for max => infinity */
        if (max == 0) max = INT_MAX;
        break;

        case OP_CRRANGE:
        case OP_CRMINRANGE:
        minimize = (*ecode == OP_CRMINRANGE);
        min = GET2(ecode, 1);
        max = GET2(ecode, 3);
        if (max == 0) max = INT_MAX;
        ecode += 5;
        break;

        default:               /* No repeat follows */
        min = max = 1;
        break;
        }

      /* First, ensure the minimum number of matches are present. */

      /* Not UTF-8 mode */
        {
        for (i = 1; i <= min; i++)
          {
          if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
          c = *eptr++;
          if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
          }
        }

      /* If max == min we can continue with the main loop without the
      need to recurse. */

      if (min == max) continue;

      /* If minimizing, keep testing the rest of the expression and advancing
      the pointer while it matches the class. */

      if (minimize)
        {
        /* Not UTF-8 mode */
          {
          for (fi = min;; fi++)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
            c = *eptr++;
            if ((data[c/8] & (1 << (c&7))) == 0) RRETURN(MATCH_NOMATCH);
            }
          }
        /* Control never gets here */
        }

      /* If maximizing, find the longest possible run, then work backwards. */

      else
        {
        pp = eptr;

          /* Not UTF-8 mode */
          {
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject) break;
            c = *eptr;
            if ((data[c/8] & (1 << (c&7))) == 0) break;
            eptr++;
            }
          while (eptr >= pp)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            eptr--;
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            }
          }

        RRETURN(MATCH_NOMATCH);
        }
      }
    /* Control never gets here */


    /* Match an extended character class. This opcode is encountered only
    in UTF-8 mode, because that's the only time it is compiled. */


    /* Match a run of characters */

    case OP_CHARS:
        {
            register int slen = ecode[1];
            ecode += 2;

            if (slen > md->end_subject - eptr)
            {
                RRETURN(MATCH_NOMATCH);
            }

            if ((ims & PCRE_CASELESS) != 0)
            {
                while (slen-- > 0)
                {
                    if (md->lcc[*ecode] != md->lcc[*eptr])
                    {
                        ecode++;
                        eptr++;
                        RRETURN(MATCH_NOMATCH);
                    }
                    ecode++;
                    eptr++;
                }
            }
            else
            {
                while (slen-- > 0)
                {
                    if (*ecode != *eptr)
                    {
                        ecode++;
                        eptr++;
                        RRETURN(MATCH_NOMATCH);
                    }
                    ecode++;
                    eptr++;
                }
            }
        }
        break;

    /* Match a single character repeatedly; different opcodes share code. */

    case OP_EXACT:
    min = max = GET2(ecode, 1);
    ecode += 3;
    goto REPEATCHAR;

    case OP_UPTO:
    case OP_MINUPTO:
    min = 0;
    max = GET2(ecode, 1);
    minimize = *ecode == OP_MINUPTO;
    ecode += 3;
    goto REPEATCHAR;

    case OP_STAR:
    case OP_MINSTAR:
    case OP_PLUS:
    case OP_MINPLUS:
    case OP_QUERY:
    case OP_MINQUERY:
    c = *ecode++ - OP_STAR;
    minimize = (c & 1) != 0;
    min = rep_min[c];                 /* Pick up values from tables; */
    max = rep_max[c];                 /* zero for max => infinity */
    if (max == 0) max = INT_MAX;

    /* Common code for all repeated single-character matches. We can give
    up quickly if there are fewer than the minimum number of characters left in
    the subject. */

    REPEATCHAR:

    /* When not in UTF-8 mode, load a single-byte character. */
      {
      if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
      fc = *ecode++;
      }

    /* The value of fc at this point is always less than 256, though we may or
    may not be in UTF-8 mode. The code is duplicated for the caseless and
    caseful cases, for speed, since matching characters is likely to be quite
    common. First, ensure the minimum number of matches are present. If min =
    max, continue at the same level without recursing. Otherwise, if
    minimizing, keep trying the rest of the expression and advancing one
    matching character if failing, up to the maximum. Alternatively, if
    maximizing, find the maximum number of characters and work backwards. */

    DPRINTF(("matching %c{%d,%d} against subject %.*s\n", fc, min, max,
      max, eptr));

    if ((ims & PCRE_CASELESS) != 0)
      {
      fc = md->lcc[fc];
      for (i = 1; i <= min; i++)
        if (fc != md->lcc[*eptr++]) RRETURN(MATCH_NOMATCH);
      if (min == max) continue;
      if (minimize)
        {
        for (fi = min;; fi++)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          if (fi >= max || eptr >= md->end_subject ||
              fc != md->lcc[*eptr++])
            RRETURN(MATCH_NOMATCH);
          }
        /* Control never gets here */
        }
      else
        {
        pp = eptr;
        for (i = min; i < max; i++)
          {
          if (eptr >= md->end_subject || fc != md->lcc[*eptr]) break;
          eptr++;
          }
        while (eptr >= pp)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          eptr--;
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          }
        RRETURN(MATCH_NOMATCH);
        }
      /* Control never gets here */
      }

    /* Caseful comparisons (includes all multi-byte characters) */

    else
      {
      for (i = 1; i <= min; i++) if (fc != *eptr++) RRETURN(MATCH_NOMATCH);
      if (min == max) continue;
      if (minimize)
        {
        for (fi = min;; fi++)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          if (fi >= max || eptr >= md->end_subject || fc != *eptr++)
            RRETURN(MATCH_NOMATCH);
          }
        /* Control never gets here */
        }
      else
        {
        pp = eptr;
        for (i = min; i < max; i++)
          {
          if (eptr >= md->end_subject || fc != *eptr) break;
          eptr++;
          }
        while (eptr >= pp)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          eptr--;
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          }
        RRETURN(MATCH_NOMATCH);
        }
      }
    /* Control never gets here */

    /* Match a negated single one-byte character. The character we are
    checking can be multibyte. */

    case OP_NOT:
    if (eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
    ecode++;
    GETCHARINCTEST(c, eptr);
    if ((ims & PCRE_CASELESS) != 0)
      {
      c = md->lcc[c];
      if (md->lcc[*ecode++] == c) RRETURN(MATCH_NOMATCH);
      }
    else
      {
      if (*ecode++ == c) RRETURN(MATCH_NOMATCH);
      }
    break;

    /* Match a negated single one-byte character repeatedly. This is almost a
    repeat of the code for a repeated single character, but I haven't found a
    nice way of commoning these up that doesn't require a test of the
    positive/negative option for each character match. Maybe that wouldn't add
    very much to the time taken, but character matching *is* what this is all
    about... */

    case OP_NOTEXACT:
    min = max = GET2(ecode, 1);
    ecode += 3;
    goto REPEATNOTCHAR;

    case OP_NOTUPTO:
    case OP_NOTMINUPTO:
    min = 0;
    max = GET2(ecode, 1);
    minimize = *ecode == OP_NOTMINUPTO;
    ecode += 3;
    goto REPEATNOTCHAR;

    case OP_NOTSTAR:
    case OP_NOTMINSTAR:
    case OP_NOTPLUS:
    case OP_NOTMINPLUS:
    case OP_NOTQUERY:
    case OP_NOTMINQUERY:
    c = *ecode++ - OP_NOTSTAR;
    minimize = (c & 1) != 0;
    min = rep_min[c];                 /* Pick up values from tables; */
    max = rep_max[c];                 /* zero for max => infinity */
    if (max == 0) max = INT_MAX;

    /* Common code for all repeated single-character (less than 255) matches.
    We can give up quickly if there are fewer than the minimum number of
    characters left in the subject. */

    REPEATNOTCHAR:
    if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
    fc = *ecode++;

    /* The code is duplicated for the caseless and caseful cases, for speed,
    since matching characters is likely to be quite common. First, ensure the
    minimum number of matches are present. If min = max, continue at the same
    level without recursing. Otherwise, if minimizing, keep trying the rest of
    the expression and advancing one matching character if failing, up to the
    maximum. Alternatively, if maximizing, find the maximum number of
    characters and work backwards. */

    DPRINTF(("negative matching %c{%d,%d} against subject %.*s\n", fc, min, max,
      max, eptr));

    if ((ims & PCRE_CASELESS) != 0)
      {
      fc = md->lcc[fc];


      /* Not UTF-8 mode */
        {
        for (i = 1; i <= min; i++)
          if (fc == md->lcc[*eptr++]) RRETURN(MATCH_NOMATCH);
        }

      if (min == max) continue;

      if (minimize)
        {
        /* Not UTF-8 mode */
          {
          for (fi = min;; fi++)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            if (fi >= max || eptr >= md->end_subject || fc == md->lcc[*eptr++])
              RRETURN(MATCH_NOMATCH);
            }
          }
        /* Control never gets here */
        }

      /* Maximize case */

      else
        {
        pp = eptr;

        /* Not UTF-8 mode */
          {
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || fc == md->lcc[*eptr]) break;
            eptr++;
            }
          while (eptr >= pp)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            eptr--;
            }
          }

        RRETURN(MATCH_NOMATCH);
        }
      /* Control never gets here */
      }

    /* Caseful comparisons */

    else
      {
      /* Not UTF-8 mode */
        {
        for (i = 1; i <= min; i++)
          if (fc == *eptr++) RRETURN(MATCH_NOMATCH);
        }

      if (min == max) continue;

      if (minimize)
        {
        /* Not UTF-8 mode */
          {
          for (fi = min;; fi++)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            if (fi >= max || eptr >= md->end_subject || fc == *eptr++)
              RRETURN(MATCH_NOMATCH);
            }
          }
        /* Control never gets here */
        }

      /* Maximize case */

      else
        {
        pp = eptr;

        /* Not UTF-8 mode */
          {
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || fc == *eptr) break;
            eptr++;
            }
          while (eptr >= pp)
            {
            RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
            if (rrc != MATCH_NOMATCH) RRETURN(rrc);
            eptr--;
            }
          }

        RRETURN(MATCH_NOMATCH);
        }
      }
    /* Control never gets here */

    /* Match a single character type repeatedly; several different opcodes
    share code. This is very similar to the code for single characters, but we
    repeat it in the interests of efficiency. */

    case OP_TYPEEXACT:
    min = max = GET2(ecode, 1);
    minimize = true;
    ecode += 3;
    goto REPEATTYPE;

    case OP_TYPEUPTO:
    case OP_TYPEMINUPTO:
    min = 0;
    max = GET2(ecode, 1);
    minimize = *ecode == OP_TYPEMINUPTO;
    ecode += 3;
    goto REPEATTYPE;

    case OP_TYPESTAR:
    case OP_TYPEMINSTAR:
    case OP_TYPEPLUS:
    case OP_TYPEMINPLUS:
    case OP_TYPEQUERY:
    case OP_TYPEMINQUERY:
    c = *ecode++ - OP_TYPESTAR;
    minimize = (c & 1) != 0;
    min = rep_min[c];                 /* Pick up values from tables; */
    max = rep_max[c];                 /* zero for max => infinity */
    if (max == 0) max = INT_MAX;

    /* Common code for all repeated single character type matches. Note that
    in UTF-8 mode, '.' matches a character of any length, but for the other
    character types, the valid characters are all one-byte long. */

    REPEATTYPE:
    ctype = *ecode++;      /* Code for the character type */

    /* First, ensure the minimum number of matches are present. Use inline
    code for maximizing the speed, and do the type test once at the start
    (i.e. keep it out of the loop). Also we can test that there are at least
    the minimum number of bytes before we start. This isn't as effective in
    UTF-8 mode, but it does no harm. Separate the UTF-8 code completely as that
    is tidier. */

    if (min > md->end_subject - eptr) RRETURN(MATCH_NOMATCH);
    if (min > 0)
      {

      /* Code for the non-UTF-8 case for minimum matching */

      switch(ctype)
        {
        case OP_ANY:
        if ((ims & PCRE_DOTALL) == 0)
          {
          for (i = 1; i <= min; i++)
            if (*eptr++ == NEWLINE) RRETURN(MATCH_NOMATCH);
          }
        else eptr += min;
        break;

        case OP_ANYBYTE:
        eptr += min;
        break;

        case OP_NOT_DIGIT:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_digit) != 0) RRETURN(MATCH_NOMATCH);
        break;

        case OP_DIGIT:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_digit) == 0) RRETURN(MATCH_NOMATCH);
        break;

        case OP_NOT_WHITESPACE:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_space) != 0) RRETURN(MATCH_NOMATCH);
        break;

        case OP_WHITESPACE:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_space) == 0) RRETURN(MATCH_NOMATCH);
        break;

        case OP_NOT_WORDCHAR:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_word) != 0)
            RRETURN(MATCH_NOMATCH);
        break;

        case OP_WORDCHAR:
        for (i = 1; i <= min; i++)
          if ((md->ctypes[*eptr++] & ctype_word) == 0)
            RRETURN(MATCH_NOMATCH);
        break;
        }
      }

    /* If min = max, continue at the same level without recursing */

    if (min == max) continue;

    /* If minimizing, we have to test the rest of the pattern before each
    subsequent match. Again, separate the UTF-8 case for speed. */

    if (minimize)
      {
      /* Not UTF-8 mode */
        {
        for (fi = min;; fi++)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          if (fi >= max || eptr >= md->end_subject) RRETURN(MATCH_NOMATCH);
          c = *eptr++;
          switch(ctype)
            {
            case OP_ANY:
            if ((ims & PCRE_DOTALL) == 0 && c == NEWLINE) RRETURN(MATCH_NOMATCH);
            break;

            case OP_ANYBYTE:
            break;

            case OP_NOT_DIGIT:
            if ((md->ctypes[c] & ctype_digit) != 0) RRETURN(MATCH_NOMATCH);
            break;

            case OP_DIGIT:
            if ((md->ctypes[c] & ctype_digit) == 0) RRETURN(MATCH_NOMATCH);
            break;

            case OP_NOT_WHITESPACE:
            if ((md->ctypes[c] & ctype_space) != 0) RRETURN(MATCH_NOMATCH);
            break;

            case OP_WHITESPACE:
            if  ((md->ctypes[c] & ctype_space) == 0) RRETURN(MATCH_NOMATCH);
            break;

            case OP_NOT_WORDCHAR:
            if ((md->ctypes[c] & ctype_word) != 0) RRETURN(MATCH_NOMATCH);
            break;

            case OP_WORDCHAR:
            if ((md->ctypes[c] & ctype_word) == 0) RRETURN(MATCH_NOMATCH);
            break;
            }
          }
        }
      /* Control never gets here */
      }

    /* If maximizing it is worth using inline code for speed, doing the type
    test once at the start (i.e. keep it out of the loop). Again, keep the
    UTF-8 stuff separate. */

    else
      {
      pp = eptr;

      /* Not UTF-8 mode */
        {
        switch(ctype)
          {
          case OP_ANY:
          if ((ims & PCRE_DOTALL) == 0)
            {
            for (i = min; i < max; i++)
              {
              if (eptr >= md->end_subject || *eptr == NEWLINE) break;
              eptr++;
              }
            break;
            }
          /* For DOTALL case, fall through and treat as \C */

          case OP_ANYBYTE:
          c = max - min;
          if (c > md->end_subject - eptr) c = md->end_subject - eptr;
          eptr += c;
          break;

          case OP_NOT_DIGIT:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_digit) != 0)
              break;
            eptr++;
            }
          break;

          case OP_DIGIT:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_digit) == 0)
              break;
            eptr++;
            }
          break;

          case OP_NOT_WHITESPACE:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_space) != 0)
              break;
            eptr++;
            }
          break;

          case OP_WHITESPACE:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_space) == 0)
              break;
            eptr++;
            }
          break;

          case OP_NOT_WORDCHAR:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_word) != 0)
              break;
            eptr++;
            }
          break;

          case OP_WORDCHAR:
          for (i = min; i < max; i++)
            {
            if (eptr >= md->end_subject || (md->ctypes[*eptr] & ctype_word) == 0)
              break;
            eptr++;
            }
          break;
          }

        /* eptr is now past the end of the maximum run */

        while (eptr >= pp)
          {
          RMATCH(rrc, eptr, ecode, offset_top, md, ims, eptrb, 0);
          eptr--;
          if (rrc != MATCH_NOMATCH) RRETURN(rrc);
          }
        }

      /* Get here if we can't make it match with any permitted repetitions */

      RRETURN(MATCH_NOMATCH);
      }
    /* Control never gets here */

    /* There's been some horrible disaster. Since all codes > OP_BRA are
    for capturing brackets, and there shouldn't be any gaps between 0 and
    OP_BRA, arrival here can only mean there is something seriously wrong
    in the code above or the OP_xxx definitions. */

    default:
    DPRINTF(("Unknown opcode %d\n", *ecode));
    RRETURN(PCRE_ERROR_UNKNOWN_NODE);
    }

  /* Do not stick any code in here without much thought; it is assumed
  that "continue" in the code above comes out to here to repeat the main
  loop. */

  }             /* End of main loop */
RRETURN(MATCH_NOMATCH);
}


/***************************************************************************
****************************************************************************
                   RECURSION IN THE match() FUNCTION

Undefine all the macros that were defined above to handle this. */

/* These two are defined as macros in both cases */

#undef fc
#undef fi

/***************************************************************************
***************************************************************************/



/*************************************************
*         Execute a Regular Expression           *
*************************************************/

/* This function applies a compiled re to a subject string and picks out
portions of the string if it matches. Two elements in the vector are set for
each substring: the offsets to the start and end of the substring.

Arguments:
  external_re     points to the compiled expression
  extra_data      points to extra data or is NULL
  subject         points to the subject string
  length          length of subject string (may contain binary zeros)
  start_offset    where to start in the subject string
  options         option bits
  offsets         points to a vector of ints to be filled in with offsets
  offsetcount     the number of elements in the vector

Returns:          > 0 => success; value is the number of elements filled in
                  = 0 => success, but offsets is not big enough
                   -1 => failed to match
                 < -1 => some kind of unexpected problem
*/

int
pcre_exec(const pcre *external_re, const pcre_extra *extra_data,
  const char *subject, int length, int start_offset, int options, int *offsets,
  int offsetcount)
{
int rc, resetcount, ocount;
int first_byte = -1;
int req_byte = -1;
int req_byte2 = -1;
unsigned long int ims = 0;
bool using_temporary_offsets = false;
bool anchored;
bool startline;
bool first_byte_caseless = false;
bool req_byte_caseless = false;
match_data match_block;
const uschar *start_bits = NULL;
const uschar *start_match = (const uschar *)subject + start_offset;
const uschar *end_subject;
const uschar *req_byte_ptr = start_match - 1;
const pcre_study_data *study;
const real_pcre *re = (const real_pcre *)external_re;

/* Plausibility checks */

if ((options & ~PUBLIC_EXEC_OPTIONS) != 0) return PCRE_ERROR_BADOPTION;
if (re == NULL || subject == NULL ||
   (offsets == NULL && offsetcount > 0)) return PCRE_ERROR_NULL;

/* Fish out the optional data from the extra_data structure, first setting
the default values. */

study = NULL;
match_block.match_limit = MATCH_LIMIT;
match_block.callout_data = NULL;

if (extra_data != NULL)
  {
  register unsigned int flags = extra_data->flags;
  if ((flags & PCRE_EXTRA_STUDY_DATA) != 0)
    study = (const pcre_study_data *)extra_data->study_data;
  if ((flags & PCRE_EXTRA_MATCH_LIMIT) != 0)
    match_block.match_limit = extra_data->match_limit;
  if ((flags & PCRE_EXTRA_CALLOUT_DATA) != 0)
    match_block.callout_data = extra_data->callout_data;
  }

/* Now we have re supposedly pointing to the regex */

if (re->magic_number != MAGIC_NUMBER) return PCRE_ERROR_BADMAGIC;

anchored = ((re->options | options) & PCRE_ANCHORED) != 0;
startline = (re->options & PCRE_STARTLINE) != 0;

match_block.start_code =
  (const uschar *)re + sizeof(real_pcre) + re->name_count * re->name_entry_size;
match_block.start_subject = (const uschar *)subject;
match_block.start_offset = start_offset;
match_block.end_subject = match_block.start_subject + length;
end_subject = match_block.end_subject;

match_block.endonly = (re->options & PCRE_DOLLAR_ENDONLY) != 0;
match_block.utf8 = (re->options & PCRE_UTF8) != 0;

match_block.notbol = (options & PCRE_NOTBOL) != 0;
match_block.noteol = (options & PCRE_NOTEOL) != 0;
match_block.notempty = (options & PCRE_NOTEMPTY) != 0;

match_block.recursive = NULL;                   /* No recursion at top level */

match_block.lcc = re->tables + lcc_offset;
match_block.ctypes = re->tables + ctypes_offset;

/* Check a UTF-8 string if required. Unfortunately there's no way of passing
back the character offset. */

/* The ims options can vary during the matching as a result of the presence
of (?ims) items in the pattern. They are kept in a local variable so that
restoring at the exit of a group is easy. */

ims = re->options & (PCRE_CASELESS|PCRE_MULTILINE|PCRE_DOTALL);

/* If the expression has got more back references than the offsets supplied can
hold, we get a temporary bit of working store to use during the matching.
Otherwise, we can use the vector supplied, rounding down its size to a multiple
of 3. */

ocount = offsetcount - (offsetcount % 3);

if (re->top_backref > 0 && re->top_backref >= ocount/3)
  {
  ocount = re->top_backref * 3 + 3;
  match_block.offset_vector = static_cast<int *>(malloc(ocount * sizeof(int)));
  if (match_block.offset_vector == NULL) return PCRE_ERROR_NOMEMORY;
  using_temporary_offsets = true;
  DPRINTF(("Got memory to hold back references\n"));
  }
else match_block.offset_vector = offsets;

match_block.offset_end = ocount;
match_block.offset_max = (2*ocount)/3;
match_block.offset_overflow = false;
match_block.capture_last = -1;

/* Compute the minimum number of offsets that we need to reset each time. Doing
this makes a huge difference to execution time when there aren't many brackets
in the pattern. */

resetcount = 2 + re->top_bracket * 2;
if (resetcount > offsetcount) resetcount = ocount;

/* Reset the working variable associated with each extraction. These should
never be used unless previously set, but they get saved and restored, and so we
initialize them to avoid reading uninitialized locations. */

if (match_block.offset_vector != NULL)
  {
  register int *iptr = match_block.offset_vector + ocount;
  register int *iend = iptr - resetcount/2 + 1;
  while (--iptr >= iend) *iptr = -1;
  }

/* Set up the first character to match, if available. The first_byte value is
never set for an anchored regular expression, but the anchoring may be forced
at run time, so we have to test for anchoring. The first char may be unset for
an unanchored pattern, of course. If there's no first char and the pattern was
studied, there may be a bitmap of possible first characters. */

if (!anchored)
  {
  if ((re->options & PCRE_FIRSTSET) != 0)
    {
    first_byte = re->first_byte & 255;
    if ((first_byte_caseless = ((re->first_byte & REQ_CASELESS) != 0)) == true)
      first_byte = match_block.lcc[first_byte];
    }
  else
    if (!startline && study != NULL &&
      (study->options & PCRE_STUDY_MAPPED) != 0)
        start_bits = study->start_bits;
  }

/* For anchored or unanchored matches, there may be a "last known required
character" set. */

if ((re->options & PCRE_REQCHSET) != 0)
  {
  req_byte = re->req_byte & 255;
  req_byte_caseless = (re->req_byte & REQ_CASELESS) != 0;
  req_byte2 = (re->tables + fcc_offset)[req_byte];  /* case flipped */
  }

/* Loop for handling unanchored repeated matching attempts; for anchored regexs
the loop runs just once. */

do
  {
  register int *iptr = match_block.offset_vector;
  register int *iend = iptr + resetcount;

  /* Reset the maximum number of extractions we might see. */

  while (iptr < iend) *iptr++ = -1;

  /* Advance to a unique first char if possible */

  if (first_byte >= 0)
    {
    if (first_byte_caseless)
      while (start_match < end_subject &&
             match_block.lcc[*start_match] != first_byte)
        start_match++;
    else
      while (start_match < end_subject && *start_match != first_byte)
        start_match++;
    }

  /* Or to just after \n for a multiline match if possible */

  else if (startline)
    {
    if (start_match > match_block.start_subject + start_offset)
      {
      while (start_match < end_subject && start_match[-1] != NEWLINE)
        start_match++;
      }
    }

  /* Or to a non-unique first char after study */

  else if (start_bits != NULL)
    {
    while (start_match < end_subject)
      {
      register int c = *start_match;
      if ((start_bits[c/8] & (1 << (c&7))) == 0) start_match++; else break;
      }
    }

  /* If req_byte is set, we know that that character must appear in the subject
  for the match to succeed. If the first character is set, req_byte must be
  later in the subject; otherwise the test starts at the match point. This
  optimization can save a huge amount of backtracking in patterns with nested
  unlimited repeats that aren't going to match. Writing separate code for
  cased/caseless versions makes it go faster, as does using an autoincrement
  and backing off on a match.

  HOWEVER: when the subject string is very, very long, searching to its end can
  take a long time, and give bad performance on quite ordinary patterns. This
  showed up when somebody was matching /^C/ on a 32-megabyte string... so we
  don't do this when the string is sufficiently long. */

  if (req_byte >= 0 && end_subject - start_match < REQ_BYTE_MAX)
    {
    register const uschar *p = start_match + ((first_byte >= 0)? 1 : 0);

    /* We don't need to repeat the search if we haven't yet reached the
    place we found it at last time. */

    if (p > req_byte_ptr)
      {
      if (req_byte_caseless)
        {
        while (p < end_subject)
          {
          register int pp = *p++;
          if (pp == req_byte || pp == req_byte2) { p--; break; }
          }
        }
      else
        {
        while (p < end_subject)
          {
          if (*p++ == req_byte) { p--; break; }
          }
        }

      /* If we can't find the required character, break the matching loop */

      if (p >= end_subject) break;

      /* If we have found the required character, save the point where we
      found it, so that we don't search again next time round the loop if
      the start hasn't passed this character yet. */

      req_byte_ptr = p;
      }
    }

  /* When a match occurs, substrings will be set for all internal extractions;
  we just need to set up the whole thing as substring 0 before returning. If
  there were too many extractions, set the return code to zero. In the case
  where we had to get some local store to hold offsets for backreferences, copy
  those back references that we can. In this case there need not be overflow
  if certain parts of the pattern were not used. */

  match_block.start_match = start_match;
  match_block.match_call_count = 0;

  rc = match(start_match, match_block.start_code, 2, &match_block, ims, NULL,
    match_isgroup);

  if (rc == MATCH_NOMATCH)
    {
    start_match++;
    continue;
    }

  if (rc != MATCH_MATCH)
    {
    DPRINTF((">>>> error: returning %d\n", rc));
    return rc;
    }

  /* We have a match! Copy the offset information from temporary store if
  necessary */

  if (using_temporary_offsets)
    {
    if (offsetcount >= 4)
      {
      memcpy(offsets + 2, match_block.offset_vector + 2,
        (offsetcount - 2) * sizeof(int));
      DPRINTF(("Copied offsets from temporary memory\n"));
      }
    if (match_block.end_offset_top > offsetcount)
      match_block.offset_overflow = true;

    DPRINTF(("Freeing temporary memory\n"));
    free(match_block.offset_vector);
    }

  rc = match_block.offset_overflow? 0 : match_block.end_offset_top/2;

  if (offsetcount < 2) rc = 0; else
    {
    offsets[0] = start_match - match_block.start_subject;
    offsets[1] = match_block.end_match_ptr - match_block.start_subject;
    }

  DPRINTF((">>>> returning %d\n", rc));
  return rc;
  }

/* This "while" is the end of the "do" above */

while (!anchored && start_match <= end_subject);

if (using_temporary_offsets)
  {
  DPRINTF(("Freeing temporary memory\n"));
  free(match_block.offset_vector);
  }

DPRINTF((">>>> returning PCRE_ERROR_NOMATCH\n"));

return PCRE_ERROR_NOMATCH;
}

/* End of pcre.c */
