src/pack.h

   1 /*
   2  * This file is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License, version 2,
   4  * as published by the Free Software Foundation.
   5  *
   6  * In addition to the permissions in the GNU General Public License,
   7  * the authors give you unlimited permission to link the compiled
   8  * version of this file into combinations with other programs,
   9  * and to distribute those combinations without any restriction
  10  * coming from the use of this file.  (The General Public License
  11  * restrictions do apply in other respects; for example, they cover
  12  * modification of the file, and distribution when not linked into
  13  * a combined executable.)
  14  *
  15  * This file is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; see the file COPYING.  If not, write to
  22  * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  23  * Boston, MA 02110-1301, USA.
  24  */
  25
  26 #ifndef INCLUDE_pack_h__
  27 #define INCLUDE_pack_h__
  28
  29 #include "git2/oid.h"
  30
  31 #include "common.h"
  32 #include "map.h"
  33 #include "mwindow.h"
  34 #include "odb.h"
  35
  36 #define PACK_SIGNATURE 0x5041434b       /* "PACK" */
  37 #define PACK_VERSION 2
  38 #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  39 struct git_pack_header {
  40         uint32_t hdr_signature;
  41         uint32_t hdr_version;
  42         uint32_t hdr_entries;
  43 };
  44
  45 /*
  46  * The first four bytes of index formats later than version 1 should
  47  * start with this signature, as all older git binaries would find this
  48  * value illegal and abort reading the file.
  49  *
  50  * This is the case because the number of objects in a packfile
  51  * cannot exceed 1,431,660,000 as every object would need at least
  52  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  53  * version 1 of the index file due to the offsets limited to 32 bits.
  54  * Clearly the signature exceeds this maximum.
  55  *
  56  * Very old git binaries will also compare the first 4 bytes to the
  57  * next 4 bytes in the index and abort with a "non-monotonic index"
  58  * error if the second 4 byte word is smaller than the first 4
  59  * byte word.  This would be true in the proposed future index
  60  * format as idx_signature would be greater than idx_version.
  61  */
  62
  63 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  64
  65 struct git_pack_idx_header {
  66         uint32_t idx_signature;
  67         uint32_t idx_version;
  68 };
  69
  70 struct git_pack_file {
  71         git_mwindow_file mwf;
  72         git_map index_map;
  73
  74         uint32_t num_objects;
  75         uint32_t num_bad_objects;
  76         git_oid *bad_object_sha1; /* array of git_oid */
  77
  78         int index_version;
  79         git_time_t mtime;
  80         unsigned pack_local:1, pack_keep:1;
  81         git_oid sha1;
  82
  83         /* something like ".git/objects/pack/xxxxx.pack" */
  84         char pack_name[GIT_FLEX_ARRAY]; /* more */
  85 };
  86
  87 struct git_pack_entry {
  88         off_t offset;
  89         git_oid sha1;
  90         struct git_pack_file *p;
  91 };
  92
  93 int git_packfile_unpack_header(
  94                 size_t *size_p,
  95                 git_otype *type_p,
  96                 git_mwindow_file *mwf,
  97                 git_mwindow **w_curs,
  98                 off_t *curpos);
  99
 100 int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, off_t *obj_offset);
 101
 102 off_t get_delta_base(struct git_pack_file *p, git_mwindow **w_curs,
 103                 off_t *curpos, git_otype type,
 104                 off_t delta_obj_offset);
 105
 106 void packfile_free(struct git_pack_file *p);
 107 int git_packfile_check(struct git_pack_file **pack_out, const char *path);
 108 int git_pack_entry_find(
 109                 struct git_pack_entry *e,
 110                 struct git_pack_file *p,
 111                 const git_oid *short_oid,
 112                 unsigned int len);
 113
 114 #endif