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_ok(v) ( \
  11            (v) == htonl(2)  \
  12         || (v) == htonl(3)  \
  13         || (v) == htonl(4)  \
  14         )
  15 struct pack_header {
  16         uint32_t hdr_signature;
  17         uint32_t hdr_version;
  18         uint32_t hdr_entries;
  19 };
  20
  21 /*
  22  * The first four bytes of index formats later than version 1 should
  23  * start with this signature, as all older git binaries would find this
  24  * value illegal and abort reading the file.
  25  *
  26  * This is the case because the number of objects in a packfile
  27  * cannot exceed 1,431,660,000 as every object would need at least
  28  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  29  * version 1 of the index file due to the offsets limited to 32 bits.
  30  * Clearly the signature exceeds this maximum.
  31  *
  32  * Very old git binaries will also compare the first 4 bytes to the
  33  * next 4 bytes in the index and abort with a "non-monotonic index"
  34  * error if the second 4 byte word is smaller than the first 4
  35  * byte word.  This would be true in the proposed future index
  36  * format as idx_signature would be greater than idx_version.
  37  */
  38 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  39
  40 /* These may be overridden by command-line parameters */
  41 extern uint32_t pack_idx_default_version;
  42 extern uint32_t pack_idx_off32_limit;
  43
  44 /*
  45  * Packed object index header
  46  */
  47 struct pack_idx_header {
  48         uint32_t idx_signature;
  49         uint32_t idx_version;
  50 };
  51
  52 /*
  53  * Common part of object structure used for write_idx_file
  54  */
  55 struct pack_idx_entry {
  56         unsigned char sha1[20];
  57         uint32_t crc32;
  58         off_t offset;
  59 };
  60
  61 extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, unsigned char *sha1);
  62
  63 extern int verify_pack(struct packed_git *, int);
  64 extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t);
  65
  66 #define PH_ERROR_EOF            (-1)
  67 #define PH_ERROR_PACK_SIGNATURE (-2)
  68 #define PH_ERROR_PROTOCOL       (-3)
  69 extern int read_pack_header(int fd, struct pack_header *);
  70 #endif