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  * The first four bytes of index formats later than version 1 should
  20  * start with this signature, as all older git binaries would find this
  21  * value illegal and abort reading the file.
  22  *
  23  * This is the case because the number of objects in a packfile
  24  * cannot exceed 1,431,660,000 as every object would need at least
  25  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  26  * version 1 of the index file due to the offsets limited to 32 bits.
  27  * Clearly the signature exceeds this maximum.
  28  *
  29  * Very old git binaries will also compare the first 4 bytes to the
  30  * next 4 bytes in the index and abort with a "non-monotonic index"
  31  * error if the second 4 byte word is smaller than the first 4
  32  * byte word.  This would be true in the proposed future index
  33  * format as idx_signature would be greater than idx_version.
  34  */
  35 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  36
  37 /*
  38  * Packed object index header
  39  */
  40 struct pack_idx_header {
  41         uint32_t idx_signature;
  42         uint32_t idx_version;
  43 };
  44
  45
  46 extern int verify_pack(struct packed_git *, int);
  47
  48 #define PH_ERROR_EOF            (-1)
  49 #define PH_ERROR_PACK_SIGNATURE (-2)
  50 #define PH_ERROR_PROTOCOL       (-3)
  51 extern int read_pack_header(int fd, struct pack_header *);
  52 #endif