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/* These may be overridden by command-line parameters */
  38extern uint32_t pack_idx_default_version;
  39extern uint32_t pack_idx_off32_limit;
  40
  41/*
  42 * Packed object index header
  43 */
  44struct pack_idx_header {
  45        uint32_t idx_signature;
  46        uint32_t idx_version;
  47};
  48
  49/*
  50 * Common part of object structure used for write_idx_file
  51 */
  52struct pack_idx_entry {
  53        unsigned char sha1[20];
  54        uint32_t crc32;
  55        off_t offset;
  56};
  57
  58extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, unsigned char *sha1);
  59extern int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, off_t offset, off_t len, unsigned int nr);
  60extern int verify_pack_index(struct packed_git *);
  61extern int verify_pack(struct packed_git *);
  62extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t, unsigned char *, off_t);
  63extern char *index_pack_lockfile(int fd);
  64extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned char *);
  65
  66#define PH_ERROR_EOF            (-1)
  67#define PH_ERROR_PACK_SIGNATURE (-2)
  68#define PH_ERROR_PROTOCOL       (-3)
  69extern int read_pack_header(int fd, struct pack_header *);
  70#endif