write_idx_file: introduce a struct to hold idx customization options
[git/git.git] / pack.h
... / ...
CommitLineData
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
37struct pack_idx_option {
38 uint32_t version;
39 uint32_t off32_limit;
40};
41
42extern void reset_pack_idx_option(struct pack_idx_option *);
43
44/*
45 * Packed object index header
46 */
47struct 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 */
55struct pack_idx_entry {
56 unsigned char sha1[20];
57 uint32_t crc32;
58 off_t offset;
59};
60
61extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, const struct pack_idx_option *, unsigned char *sha1);
62extern int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, off_t offset, off_t len, unsigned int nr);
63extern int verify_pack_index(struct packed_git *);
64extern int verify_pack(struct packed_git *);
65extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t, unsigned char *, off_t);
66extern char *index_pack_lockfile(int fd);
67extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned char *);
68
69#define PH_ERROR_EOF (-1)
70#define PH_ERROR_PACK_SIGNATURE (-2)
71#define PH_ERROR_PROTOCOL (-3)
72extern int read_pack_header(int fd, struct pack_header *);
73#endif