src/pack.h

   1 /*
   2  * Copyright (C) the libgit2 contributors. All rights reserved.
   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 #include "oidmap.h"
  20
  21 #define GIT_PACK_FILE_MODE 0444
  22
  23 #define PACK_SIGNATURE 0x5041434b       /* "PACK" */
  24 #define PACK_VERSION 2
  25 #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  26 struct git_pack_header {
  27         uint32_t hdr_signature;
  28         uint32_t hdr_version;
  29         uint32_t hdr_entries;
  30 };
  31
  32 /*
  33  * The first four bytes of index formats later than version 1 should
  34  * start with this signature, as all older git binaries would find this
  35  * value illegal and abort reading the file.
  36  *
  37  * This is the case because the number of objects in a packfile
  38  * cannot exceed 1,431,660,000 as every object would need at least
  39  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  40  * version 1 of the index file due to the offsets limited to 32 bits.
  41  * Clearly the signature exceeds this maximum.
  42  *
  43  * Very old git binaries will also compare the first 4 bytes to the
  44  * next 4 bytes in the index and abort with a "non-monotonic index"
  45  * error if the second 4 byte word is smaller than the first 4
  46  * byte word. This would be true in the proposed future index
  47  * format as idx_signature would be greater than idx_version.
  48  */
  49
  50 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  51
  52 struct git_pack_idx_header {
  53         uint32_t idx_signature;
  54         uint32_t idx_version;
  55 };
  56
  57 typedef struct git_pack_cache_entry {
  58         size_t last_usage; /* enough? */
  59         git_atomic refcount;
  60         git_rawobj raw;
  61 } git_pack_cache_entry;
  62
  63 #include "offmap.h"
  64
  65 GIT__USE_OFFMAP;
  66 GIT__USE_OIDMAP;
  67
  68 #define GIT_PACK_CACHE_MEMORY_LIMIT 16 * 1024 * 1024
  69 #define GIT_PACK_CACHE_SIZE_LIMIT 1024 * 1024 /* don't bother caching anything over 1MB */
  70
  71 typedef struct {
  72         size_t memory_used;
  73         size_t memory_limit;
  74         size_t use_ctr;
  75         git_mutex lock;
  76         git_offmap *entries;
  77 } git_pack_cache;
  78
  79 struct git_pack_file {
  80         git_mwindow_file mwf;
  81         git_map index_map;
  82         git_mutex lock; /* protect updates to mwf and index_map */
  83
  84         uint32_t num_objects;
  85         uint32_t num_bad_objects;
  86         git_oid *bad_object_sha1; /* array of git_oid */
  87
  88         int index_version;
  89         git_time_t mtime;
  90         unsigned pack_local:1, pack_keep:1, has_cache:1;
  91         git_oid sha1;
  92         git_oidmap *idx_cache;
  93         git_oid **oids;
  94
  95         git_pack_cache bases; /* delta base cache */
  96
  97         /* something like ".git/objects/pack/xxxxx.pack" */
  98         char pack_name[GIT_FLEX_ARRAY]; /* more */
  99 };
 100
 101 struct git_pack_entry {
 102         git_off_t offset;
 103         git_oid sha1;
 104         struct git_pack_file *p;
 105 };
 106
 107 typedef struct git_packfile_stream {
 108         git_off_t curpos;
 109         int done;
 110         z_stream zstream;
 111         struct git_pack_file *p;
 112         git_mwindow *mw;
 113 } git_packfile_stream;
 114
 115 int git_packfile_unpack_header(
 116                 size_t *size_p,
 117                 git_otype *type_p,
 118                 git_mwindow_file *mwf,
 119                 git_mwindow **w_curs,
 120                 git_off_t *curpos);
 121
 122 int git_packfile_resolve_header(
 123                 size_t *size_p,
 124                 git_otype *type_p,
 125                 struct git_pack_file *p,
 126                 git_off_t offset);
 127
 128 int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, git_off_t *obj_offset);
 129 int packfile_unpack_compressed(
 130         git_rawobj *obj,
 131         struct git_pack_file *p,
 132         git_mwindow **w_curs,
 133         git_off_t *curpos,
 134         size_t size,
 135         git_otype type);
 136
 137 int git_packfile_stream_open(git_packfile_stream *obj, struct git_pack_file *p, git_off_t curpos);
 138 ssize_t git_packfile_stream_read(git_packfile_stream *obj, void *buffer, size_t len);
 139 void git_packfile_stream_free(git_packfile_stream *obj);
 140
 141 git_off_t get_delta_base(struct git_pack_file *p, git_mwindow **w_curs,
 142                 git_off_t *curpos, git_otype type,
 143                 git_off_t delta_obj_offset);
 144
 145 void git_packfile_free(struct git_pack_file *p);
 146 int git_packfile_alloc(struct git_pack_file **pack_out, const char *path);
 147
 148 int git_pack_entry_find(
 149                 struct git_pack_entry *e,
 150                 struct git_pack_file *p,
 151                 const git_oid *short_oid,
 152                 size_t len);
 153 int git_pack_foreach_entry(
 154                 struct git_pack_file *p,
 155                 git_odb_foreach_cb cb,
 156                 void *data);
 157
 158 #endif