pack.h

   1 #ifndef PACK_H
   2 #define PACK_H
   3
   4 #include "object.h"
   5
   6 /*
   7  * Packed object header
   8  */
   9 #define PACK_SIGNATURE 0x5041434b       /* "PACK" */
  10 #define PACK_VERSION 2
  11 #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  12 struct pack_header {
  13         uint32_t hdr_signature;
  14         uint32_t hdr_version;
  15         uint32_t hdr_entries;
  16 };
  17
  18 /*
  19  * Packed object index header
  20  *
  21  * struct pack_idx_header {
  22  *      uint32_t idx_signature;
  23  *      uint32_t idx_version;
  24  * };
  25  *
  26  * Note: this header isn't active yet.  In future versions of git
  27  * we may change the index file format.  At that time we would start
  28  * the first four bytes of the new index format with this signature,
  29  * as all older git binaries would find this value illegal and abort
  30  * reading the file.
  31  *
  32  * This is the case because the number of objects in a packfile
  33  * cannot exceed 1,431,660,000 as every object would need at least
  34  * 3 bytes of data and the overall packfile cannot exceed 4 GiB due
  35  * to the 32 bit offsets used by the index.  Clearly the signature
  36  * exceeds this maximum.
  37  *
  38  * Very old git binaries will also compare the first 4 bytes to the
  39  * next 4 bytes in the index and abort with a "non-monotonic index"
  40  * error if the second 4 byte word is smaller than the first 4
  41  * byte word.  This would be true in the proposed future index
  42  * format as idx_signature would be greater than idx_version.
  43  */
  44 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  45
  46 extern int verify_pack(struct packed_git *, int);
  47 #endif