/* inflate.c -- zlib interface to inflate modules
 * Copyright (C) 1995-1996 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

#include "zutil.h"
#include "infblock.h"

struct inflate_blocks_state {int dummy;}; /* for buggy compilers */

/* inflate private state */
struct internal_state {

  /* mode */
  enum {
      METHOD,   /* waiting for method byte */
      FLAG,     /* waiting for flag byte */
      DICT4,    /* four dictionary check bytes to go */
      DICT3,    /* three dictionary check bytes to go */
      DICT2,    /* two dictionary check bytes to go */
      DICT1,    /* one dictionary check byte to go */
      DICT0,    /* waiting for inflateSetDictionary */
      BLOCKS,   /* decompressing blocks */
      CHECK4,   /* four check bytes to go */
      CHECK3,   /* three check bytes to go */
      CHECK2,   /* two check bytes to go */
      CHECK1,   /* one check byte to go */
      DONE,     /* finished check, done */
      BAD}      /* got an error--stay here */
    mode;               /* current inflate mode */

  /* mode dependent information */
  union {
    uInt method;        /* if FLAGS, method byte */
    struct {
      uLong was;                /* computed check value */
      uLong need;               /* stream check value */
    } check;            /* if CHECK, check values to compare */
    uInt marker;        /* if BAD, inflateSync's marker bytes count */
  } sub;        /* submode */

  /* mode independent information */
  int  nowrap;          /* flag for no wrapper */
  uInt wbits;           /* log2(window size)  (8..15, defaults to 15) */
  inflate_blocks_statef 
    *blocks;            /* current inflate_blocks state */

};


int inflateReset(z)
z_streamp z;
{
  uLong c;

  if (z == Z_NULL || z->state == Z_NULL)
    return Z_STREAM_ERROR;
  z->total_in = z->total_out = 0;
  z->msg = Z_NULL;
  z->state->mode = z->state->nowrap ? BLOCKS : METHOD;
  inflate_blocks_reset(z->state->blocks, z, &c);
  Trace((stderr, "inflate: reset\n"));
  return Z_OK;
}


int inflateEnd(z)
z_streamp z;
{
  uLong c;

  if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL)
    return Z_STREAM_ERROR;
  if (z->state->blocks != Z_NULL)
    inflate_blocks_free(z->state->blocks, z, &c);
  ZFREE(z, z->state);
  z->state = Z_NULL;
  Trace((stderr, "inflate: end\n"));
  return Z_OK;
}


int inflateInit2_(z, w, version, stream_size)
z_streamp z;
int w;
const char *version;
int stream_size;
{
  if (version == Z_NULL || version[0] != ZLIB_VERSION[0] ||
      stream_size != sizeof(z_stream))
      return Z_VERSION_ERROR;

  /* initialize state */
  if (z == Z_NULL)
    return Z_STREAM_ERROR;
  z->msg = Z_NULL;
  if (z->zalloc == Z_NULL)
  {
    z->zalloc = zcalloc;
    z->opaque = (voidpf)0;
  }
  if (z->zfree == Z_NULL) z->zfree = zcfree;
  if ((z->state = (struct internal_state FAR *)
       ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL)
    return Z_MEM_ERROR;
  z->state->blocks = Z_NULL;

  /* handle undocumented nowrap option (no zlib header or check) */
  z->state->nowrap = 0;
  if (w < 0)
  {
    w = - w;
    z->state->nowrap = 1;
  }

  /* set window size */
  if (w < 8 || w > 15)
  {
    inflateEnd(z);
    return Z_STREAM_ERROR;
  }
  z->state->wbits = (uInt)w;

  /* create inflate_blocks state */
  if ((z->state->blocks =
      inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w))
      == Z_NULL)
  {
    inflateEnd(z);
    return Z_MEM_ERROR;
  }
  Trace((stderr, "inflate: allocated\n"));

  /* reset state */
  inflateReset(z);
  return Z_OK;
}


int inflateInit_(z, version, stream_size)
z_streamp z;
const char *version;
int stream_size;
{
  return inflateInit2_(z, DEF_WBITS, version, stream_size);
}


#define NEEDBYTE {if(z->avail_in==0)return r;r=Z_OK;}
#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++)

int inflate(z, f)
z_streamp z;
int f;
{
    int r;
    uInt b;

    if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL || f < 0)
	return Z_STREAM_ERROR;
    r = Z_BUF_ERROR;
    while (1) 
	switch (z->state->mode)
	{
	case METHOD:
	    NEEDBYTE
		if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED)
		{
		    z->state->mode = BAD;
		    z->msg = (char*)"unknown compression method";
		    z->state->sub.marker = 5;       /* can't try inflateSync */
		    break;
		}
	    if ((z->state->sub.method >> 4) + 8 > z->state->wbits)
	    {
		z->state->mode = BAD;
		z->msg = (char*)"invalid window size";
		z->state->sub.marker = 5;       /* can't try inflateSync */
		break;
	    }
	    z->state->mode = FLAG;
	case FLAG:
	    NEEDBYTE
		b = NEXTBYTE;
	    if (((z->state->sub.method << 8) + b) % 31)
	    {
		z->state->mode = BAD;
		z->msg = (char*)"incorrect header check";
		z->state->sub.marker = 5;       /* can't try inflateSync */
		break;
	    }
	    Trace((stderr, "inflate: zlib header ok\n"));
	    if (!(b & PRESET_DICT))
	    {
		z->state->mode = BLOCKS;
		break;
	    }
	    z->state->mode = DICT4;
	case DICT4:
	    NEEDBYTE
		z->state->sub.check.need = (uLong)NEXTBYTE << 24;
	    z->state->mode = DICT3;
	case DICT3:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE << 16;
	    z->state->mode = DICT2;
	case DICT2:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE << 8;
	    z->state->mode = DICT1;
	case DICT1:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE;
	    z->adler = z->state->sub.check.need;
	    z->state->mode = DICT0;
	    return Z_NEED_DICT;
	case DICT0:
	    z->state->mode = BAD;
	    z->msg = (char*)"need dictionary";
	    z->state->sub.marker = 0;       /* can try inflateSync */
	    return Z_STREAM_ERROR;
	case BLOCKS:
	    r = inflate_blocks(z->state->blocks, z, r);
	    if (r == Z_DATA_ERROR)
	    {
		z->state->mode = BAD;
		z->state->sub.marker = 0;       /* can try inflateSync */
		break;
	    }
	    if (r != Z_STREAM_END)
		return r;
	    r = Z_OK;
	    inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was);
	    if (z->state->nowrap)
	    {
		z->state->mode = DONE;
		break;
	    }
	    z->state->mode = CHECK4;
	case CHECK4:
	    NEEDBYTE
		z->state->sub.check.need = (uLong)NEXTBYTE << 24;
	    z->state->mode = CHECK3;
	case CHECK3:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE << 16;
	    z->state->mode = CHECK2;
	case CHECK2:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE << 8;
	    z->state->mode = CHECK1;
	case CHECK1:
	    NEEDBYTE
		z->state->sub.check.need += (uLong)NEXTBYTE;

	    if (z->state->sub.check.was != z->state->sub.check.need)
	    {
		z->state->mode = BAD;
		z->msg = (char*)"incorrect data check";
		z->state->sub.marker = 5;       /* can't try inflateSync */
		break;
	    }
	    Trace((stderr, "inflate: zlib check ok\n"));
	    z->state->mode = DONE;
	case DONE:
	    return Z_STREAM_END;
	case BAD:
	    return Z_DATA_ERROR;
	default:
	    return Z_STREAM_ERROR;
	}
}


int inflateSetDictionary(z, dictionary, dictLength)
z_streamp z;
const Bytef *dictionary;
uInt  dictLength;
{
  uInt length = dictLength;

  if (z == Z_NULL || z->state == Z_NULL || z->state->mode != DICT0)
    return Z_STREAM_ERROR;

  if (adler32(1L, dictionary, dictLength) != z->adler) return Z_DATA_ERROR;
  z->adler = 1L;

  if (length >= ((uInt)1<<z->state->wbits))
  {
    length = (1<<z->state->wbits)-1;
    dictionary += dictLength - length;
  }
  inflate_set_dictionary(z->state->blocks, dictionary, length);
  z->state->mode = BLOCKS;
  return Z_OK;
}


int inflateSync(z)
z_streamp z;
{
  uInt n;       /* number of bytes to look at */
  Bytef *p;     /* pointer to bytes */
  uInt m;       /* number of marker bytes found in a row */
  uLong r, w;   /* temporaries to save total_in and total_out */

  /* set up */
  if (z == Z_NULL || z->state == Z_NULL)
    return Z_STREAM_ERROR;
  if (z->state->mode != BAD)
  {
    z->state->mode = BAD;
    z->state->sub.marker = 0;
  }
  if ((n = z->avail_in) == 0)
    return Z_BUF_ERROR;
  p = z->next_in;
  m = z->state->sub.marker;

  /* search */
  while (n && m < 4)
  {
    if (*p == (Byte)(m < 2 ? 0 : 0xff))
      m++;
    else if (*p)
      m = 0;
    else
      m = 4 - m;
    p++, n--;
  }

  /* restore */
  z->total_in += p - z->next_in;
  z->next_in = p;
  z->avail_in = n;
  z->state->sub.marker = m;

  /* return no joy or set up to restart on a new block */
  if (m != 4)
    return Z_DATA_ERROR;
  r = z->total_in;  w = z->total_out;
  inflateReset(z);
  z->total_in = r;  z->total_out = w;
  z->state->mode = BLOCKS;
  return Z_OK;
}
