src/pack.h

   1 /*
   2  * Copyright (C) 2009-2012 the libgit2 contributors
   3  *
   4  * This file is part of libgit2, distributed under the GNU GPL v2 with
   5  * a Linking Exception. For full terms see the included COPYING file.
   6  */
   7
   8 #ifndef INCLUDE_pack_h__
   9 #define INCLUDE_pack_h__
  10
  11 #include <zlib.h>
  12
  13 #include "git2/oid.h"
  14
  15 #include "common.h"
  16 #include "map.h"
  17 #include "mwindow.h"
  18 #include "odb.h"
  19
  20 #define GIT_PACK_FILE_MODE 0444
  21
  22 #define PACK_SIGNATURE 0x5041434b       /* "PACK" */
  23 #define PACK_VERSION 2
  24 #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  25 struct git_pack_header {
  26         uint32_t hdr_signature;
  27         uint32_t hdr_version;
  28         uint32_t hdr_entries;
  29 };
  30
  31 /*
  32  * The first four bytes of index formats later than version 1 should
  33  * start with this signature, as all older git binaries would find this
  34  * value illegal and abort reading the file.
  35  *
  36  * This is the case because the number of objects in a packfile
  37  * cannot exceed 1,431,660,000 as every object would need at least
  38  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  39  * version 1 of the index file due to the offsets limited to 32 bits.
  40  * Clearly the signature exceeds this maximum.
  41  *
  42  * Very old git binaries will also compare the first 4 bytes to the
  43  * next 4 bytes in the index and abort with a "non-monotonic index"
  44  * error if the second 4 byte word is smaller than the first 4
  45  * byte word. This would be true in the proposed future index
  46  * format as idx_signature would be greater than idx_version.
  47  */
  48
  49 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  50
  51 struct git_pack_idx_header {
  52         uint32_t idx_signature;
  53         uint32_t idx_version;
  54 };
  55
  56 struct git_pack_file {
  57         git_mwindow_file mwf;
  58         git_map index_map;
  59
  60         uint32_t num_objects;
  61         uint32_t num_bad_objects;
  62         git_oid *bad_object_sha1; /* array of git_oid */
  63
  64         int index_version;
  65         git_time_t mtime;
  66         unsigned pack_local:1, pack_keep:1, has_cache:1;
  67         git_oid sha1;
  68         git_vector cache;
  69         git_oid **oids;
  70
  71         /* something like ".git/objects/pack/xxxxx.pack" */
  72         char pack_name[GIT_FLEX_ARRAY]; /* more */
  73 };
  74
  75 struct git_pack_entry {
  76         git_off_t offset;
  77         git_oid sha1;
  78         struct git_pack_file *p;
  79 };
  80
  81 typedef struct git_packfile_stream {
  82         git_off_t curpos;
  83         int done;
  84         z_stream zstream;
  85         struct git_pack_file *p;
  86         git_mwindow *mw;
  87 } git_packfile_stream;
  88
  89 int git_packfile_unpack_header(
  90                 size_t *size_p,
  91                 git_otype *type_p,
  92                 git_mwindow_file *mwf,
  93                 git_mwindow **w_curs,
  94                 git_off_t *curpos);
  95
  96 int git_packfile_resolve_header(
  97                 size_t *size_p,
  98                 git_otype *type_p,
  99                 struct git_pack_file *p,
 100                 git_off_t offset);
 101
 102 int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, git_off_t *obj_offset);
 103 int packfile_unpack_compressed(
 104         git_rawobj *obj,
 105         struct git_pack_file *p,
 106         git_mwindow **w_curs,
 107         git_off_t *curpos,
 108         size_t size,
 109         git_otype type);
 110
 111 int git_packfile_stream_open(git_packfile_stream *obj, struct git_pack_file *p, git_off_t curpos);
 112 ssize_t git_packfile_stream_read(git_packfile_stream *obj, void *buffer, size_t len);
 113 void git_packfile_stream_free(git_packfile_stream *obj);
 114
 115 git_off_t get_delta_base(struct git_pack_file *p, git_mwindow **w_curs,
 116                 git_off_t *curpos, git_otype type,
 117                 git_off_t delta_obj_offset);
 118
 119 void packfile_free(struct git_pack_file *p);
 120 int git_packfile_check(struct git_pack_file **pack_out, const char *path);
 121 int git_pack_entry_find(
 122                 struct git_pack_entry *e,
 123                 struct git_pack_file *p,
 124                 const git_oid *short_oid,
 125                 size_t len);
 126 int git_pack_foreach_entry(
 127                 struct git_pack_file *p,
 128                 git_odb_foreach_cb cb,
 129                 void *data);
 130
 131 #endif