Andrew's git - gitweb.git/blob

   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))
  12struct 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 */
  40struct pack_idx_header {
  41        uint32_t idx_signature;
  42        uint32_t idx_version;
  43};
  44
  45
  46extern 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)
  51extern int read_pack_header(int fd, struct pack_header *);
  52#endif