Make the sha1 of the index file go at the very end of the file.
[git/git.git] / cache.h
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e83c5163
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1#ifndef CACHE_H
2#define CACHE_H
3
4#include <stdio.h>
5#include <sys/stat.h>
6#include <fcntl.h>
7#include <stddef.h>
8#include <stdlib.h>
9#include <stdarg.h>
bf0c6e83 10#include <string.h>
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11#include <errno.h>
12#include <sys/mman.h>
ccc4feb5 13#include <netinet/in.h>
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14
15#include <openssl/sha.h>
16#include <zlib.h>
17
18/*
19 * Basic data structures for the directory cache
20 *
21 * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
22 * not even trying to be portable. It's trying to be efficient. It's
23 * just a cache, after all.
24 */
25
26#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
27struct cache_header {
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28 unsigned int hdr_signature;
29 unsigned int hdr_version;
30 unsigned int hdr_entries;
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31};
32
33/*
34 * The "cache_time" is just the low 32 bits of the
35 * time. It doesn't matter if it overflows - we only
36 * check it for equality in the 32 bits we save.
37 */
38struct cache_time {
39 unsigned int sec;
40 unsigned int nsec;
41};
42
43/*
44 * dev/ino/uid/gid/size are also just tracked to the low 32 bits
45 * Again - this is just a (very strong in practice) heuristic that
46 * the inode hasn't changed.
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47 *
48 * We save the fields in big-endian order to allow using the
49 * index file over NFS transparently.
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50 */
51struct cache_entry {
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52 struct cache_time ce_ctime;
53 struct cache_time ce_mtime;
54 unsigned int ce_dev;
55 unsigned int ce_ino;
56 unsigned int ce_mode;
57 unsigned int ce_uid;
58 unsigned int ce_gid;
59 unsigned int ce_size;
e83c5163 60 unsigned char sha1[20];
f5cabd13 61 unsigned short ce_flags;
59c1e249 62 char name[0];
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63};
64
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65#define CE_NAMEMASK (0x0fff)
66#define CE_STAGEMASK (0x3000)
aee46198 67#define CE_STAGESHIFT 12
95fd5bf8 68
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69#define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
70#define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
71#define ce_size(ce) cache_entry_size(ce_namelen(ce))
72#define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
73
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74#define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
75#define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
76
aee46198 77#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
f5cabd13 78
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79const char *sha1_file_directory;
80struct cache_entry **active_cache;
81unsigned int active_nr, active_alloc;
82
83#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
4bb04f21 84#define DEFAULT_DB_ENVIRONMENT ".git/objects"
e83c5163 85
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86#define alloc_nr(x) (((x)+16)*3/2)
87
734aab75 88/* Initialize and use the cache information */
e83c5163 89extern int read_cache(void);
197ee8c9 90extern int write_cache(int newfd, struct cache_entry **cache, int entries);
eb38c22f 91extern int cache_name_pos(const char *name, int namelen);
121481ab 92extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
197ee8c9 93extern int remove_file_from_cache(char *path);
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94extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
95
96#define MTIME_CHANGED 0x0001
97#define CTIME_CHANGED 0x0002
98#define OWNER_CHANGED 0x0004
99#define MODE_CHANGED 0x0008
100#define INODE_CHANGED 0x0010
101#define DATA_CHANGED 0x0020
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102
103/* Return a statically allocated filename matching the sha1 signature */
73134b6d 104extern char *sha1_file_name(const unsigned char *sha1);
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105
106/* Write a memory buffer out to the sha file */
73134b6d 107extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
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108
109/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
73134b6d 110extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
2ade9340 111extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
73134b6d 112extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
d6d3f9d0 113extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
d98b46f8 114extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
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115
116/* Convert to/from hex/sha1 representation */
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117extern int get_sha1_hex(const char *hex, unsigned char *sha1);
118extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */
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119
120/* General helper functions */
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121extern void usage(const char *err);
122extern void die(const char *err, ...);
123extern int error(const char *err, ...);
124
79517a06 125extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
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126
127#endif /* CACHE_H */