Initial revision of "git", the information manager from hell
[git/git.git] / cache.h
CommitLineData
e83c5163
LT
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>
10#include <errno.h>
11#include <sys/mman.h>
12
13#include <openssl/sha.h>
14#include <zlib.h>
15
16/*
17 * Basic data structures for the directory cache
18 *
19 * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
20 * not even trying to be portable. It's trying to be efficient. It's
21 * just a cache, after all.
22 */
23
24#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
25struct cache_header {
26 unsigned int signature;
27 unsigned int version;
28 unsigned int entries;
29 unsigned char sha1[20];
30};
31
32/*
33 * The "cache_time" is just the low 32 bits of the
34 * time. It doesn't matter if it overflows - we only
35 * check it for equality in the 32 bits we save.
36 */
37struct cache_time {
38 unsigned int sec;
39 unsigned int nsec;
40};
41
42/*
43 * dev/ino/uid/gid/size are also just tracked to the low 32 bits
44 * Again - this is just a (very strong in practice) heuristic that
45 * the inode hasn't changed.
46 */
47struct cache_entry {
48 struct cache_time ctime;
49 struct cache_time mtime;
50 unsigned int st_dev;
51 unsigned int st_ino;
52 unsigned int st_mode;
53 unsigned int st_uid;
54 unsigned int st_gid;
55 unsigned int st_size;
56 unsigned char sha1[20];
57 unsigned short namelen;
58 unsigned char name[0];
59};
60
61const char *sha1_file_directory;
62struct cache_entry **active_cache;
63unsigned int active_nr, active_alloc;
64
65#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
66#define DEFAULT_DB_ENVIRONMENT ".dircache/objects"
67
68#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
69#define ce_size(ce) cache_entry_size((ce)->namelen)
70
71#define alloc_nr(x) (((x)+16)*3/2)
72
73/* Initialize the cache information */
74extern int read_cache(void);
75
76/* Return a statically allocated filename matching the sha1 signature */
77extern char *sha1_file_name(unsigned char *sha1);
78
79/* Write a memory buffer out to the sha file */
80extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size);
81
82/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
83extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size);
84extern int write_sha1_file(char *buf, unsigned len);
85
86/* Convert to/from hex/sha1 representation */
87extern int get_sha1_hex(char *hex, unsigned char *sha1);
88extern char *sha1_to_hex(unsigned char *sha1); /* static buffer! */
89
90/* General helper functions */
91extern void usage(const char *err);
92
93#endif /* CACHE_H */