libjte internals
~~~~~~~~~~~~~~~~
See API file for the public interface.


Jigdo options for xorriso/libisoburn
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Implemented are :
-jigdo-jigdo FILE           Produce a jigdo .jigdo file as well as the .iso
-jigdo-template FILE        Produce a jigdo .template file as well as the .iso
-jigdo-min-file-size SIZE   Minimum size for a file to be listed in the jigdo file
-jigdo-force-md5 PATTERN    Pattern(s) where files MUST match an externally-supplied MD5sum
-jigdo-exclude PATTERN      Pattern(s) to exclude from the jigdo file
-jigdo-map PATTERN1=PATTERN2 Pattern(s) to map paths (e.g. Debian=/mirror/debian)
-md5-list FILE              File containing MD5 sums of the files that should be checked
-jigdo-template-compress ALGORITHM Choose to use gzip or bzip2 compression for template data; default is gzip

Not yet implemented:
-checksum_algorithm_iso alg1,alg2,... Specify the checksum types desired for the output image
-checksum_algorithm_template alg1,alg2,... Specify the checksum types desired for the output jigdo template

Example: xorriso/genisoimage -J -r -o /home/steve/test1.iso \
     -jigdo-jigdo /home/steve/test1.jigdo \
     -jigdo-template /home/steve/test1.template \
     -jigdo-min-file-size 16384 \
     -jigdo-exclude "README*" \
     -jigdo-force-md5 "/pool/" \
     -jigdo-map Debian=/mirror/debian \
     -md5-list /home/steve/md5.list \
     /mirror/jigdo-test

Global variables from application POV (declated in jte.h)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- extern char *jtemplate_out;
  XORRISO: -jigdo-template filepath

- extern char *jjigdo_out;
  XORRISO: -jigdo-jigdo filepath

- extern char *jmd5_list;
  XORRISO: -md5-list filepath

- extern FILE *jtjigdo;
  XORRISO: handle initialized with -jigdo-jigdo filepath

- extern FILE *jttemplate;
  XORRISO: resp. handle for template

- int  jte_min_size; 
  XORRISO: -jigdo-min-file-size

- int checksum_algo_iso;
  XORRISO: -checksum_algorithm_iso alg1,alg2,...

- int checksum_algo_tmpl;
  XORRISO: -checksum_algorithm_template alg1,alg2,... 

- jtc_t jte_template_compression (type declated in jte.h)
  XORRISO: -jigdo-template-compress
  

Callers from the application POV (genisoimage as example)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(all of these are called if jigdo representation is requested by the
user, i.e. path to .jigdo and .template were given via options):

- void write_jt_header(FILE *template_file, FILE *jigdo_file);
  DESCRIPTION: call after .jigdo and .template file handles are opened.
  PARAMETERS: obvious
  XORRISO: to provide -jigdo-jigdo and -jigdo-template

- void write_jt_footer(void);
  DESCRIPTION: call after image and .jigdo and .template files are complated
               also do close file handles for .jigdo and .template.
  PARAMETERS: none
  XORRISO: calls that somewhere in finalization code?

- void jtwrite(void *buffer, int size, int count, int submode, BOOL islast);
  DESCRIPTION: call that on each place where data is written to the image,
               after list_file_in_jigdo() and write_jt_match_record() are called.
  PARAMETERS: fairly obvious
  LIBISOFS: see below in list_file_in_jigdo() section

- void write_jt_match_record(char *filename, char *mirror_name, int sector_size, off_t size, unsigned char md5[16]);
  DESCRIPTION: to be called after list_file_in_jigdo() call:
               int include_in_jigdo = list_file_in_jigdo()
               if (include_in_jigdo)
                   write_jt_match_record();
               ...
               call_to_write_data_to_image();
               if (!include_in_jigdo)
                   jtwrite();
  PARAMETERS: filename - disk file path
              mirror_name - as returned previously by list_file_in_jigdo()
  LIBISOFS:   see below in list_file_in_jigdo() section

- int  list_file_in_jigdo(char *filename, off_t size, char **realname, unsigned char md5[16]);
  DESCRIPTION: decides whether a file should be placed in .jigdo
  PARAMETERS: filename - disk file path
              mirror_name - to be returned and given to write_jt_match_record()
	      md5[16] - We have the MD5. But ok. If it works that way then we should not 
	      change it without need. Eventually write a new function without calling 
	      calculate_md5sum(), but supply the md5sum instead as we already have it on that
              libisofs spot.
  LIBISOFS: libisofs/filesrc.c:filesrc_writer_write_data() has a loop which iterates over the 
            array of IsoFileSrc of all data files and writes their data content to the output stream.

- int  jte_add_exclude(char *pattern);
  DESCRIPTION: files matching patterns to be included in .jigdo
  PARAMETERS: pattern string
  XORRISO: -jigdo-exclude "README*"

- int  jte_add_include(char *pattern);
  DESCTIPRITON: files matching patterns to be included in .jigdo
  PARAMETERS: pattern string
  XORRISO: -jigdo-force-md5 "/pool/"

- int  jte_add_mapping(char *arg);
  DESCRIPTION: provides String:/a/b/c mappings for [Parts] section .jigdo file
  PARAMETERS: arg - Debian=/mirror/debian
  XORRISO: -jigdo-map Debian=/mirror/debian


>>> Where are the argument parsers of algorithm setters ?

- libjte: MD5, size, and basename of the path have to match MD5, size,
  and basename of the data file.

- libjte: The directory part of path is just a literal string that shall be
  checked for the address mapping
     -jigdo-map Debian=literal_md5_path_start

-jigit-mkimage: The directory part of the path is of importance when producing
  the payload image from template file.
  - If the payload image gets generated by option -j jigdo_file, then
    the disk file address of a data file gets composed from the reverse
    mapping
      -m Debian=/really/usable/path/for/fopen
    and the parts of the path, that was not consumed by the genisoimage
    mapping.
  - If the payload image gets generated by option -f md5_file, then the
    paths in the md5_file have to be usable for fopen().

If we follow the mainstream and ignore the case of jigit-mkimage -f md5_file,
then we can reduce the constraint for paths in .md5 to the advise to use
absolute paths in a literally coordinated way with the jigdo generator.



