Make "write_cache()" and friends available as generic routines.
[git/git.git] / cache.h
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 <string.h>
11 #include <errno.h>
12 #include <sys/mman.h>
13
14 #include <openssl/sha.h>
15 #include <zlib.h>
16
17 /*
18 * Basic data structures for the directory cache
19 *
20 * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
21 * not even trying to be portable. It's trying to be efficient. It's
22 * just a cache, after all.
23 */
24
25 #define CACHE_SIGNATURE 0x44495243 /* "DIRC" */
26 struct cache_header {
27 unsigned int signature;
28 unsigned int version;
29 unsigned int entries;
30 unsigned char sha1[20];
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 */
38 struct 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.
47 */
48 struct cache_entry {
49 struct cache_time ctime;
50 struct cache_time mtime;
51 unsigned int st_dev;
52 unsigned int st_ino;
53 unsigned int st_mode;
54 unsigned int st_uid;
55 unsigned int st_gid;
56 unsigned int st_size;
57 unsigned char sha1[20];
58 unsigned short namelen;
59 char name[0];
60 };
61
62 const char *sha1_file_directory;
63 struct cache_entry **active_cache;
64 unsigned int active_nr, active_alloc;
65
66 #define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
67 #define DEFAULT_DB_ENVIRONMENT ".dircache/objects"
68
69 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
70 #define ce_size(ce) cache_entry_size((ce)->namelen)
71
72 #define alloc_nr(x) (((x)+16)*3/2)
73
74 /* Initialize and use the cache information */
75 extern int read_cache(void);
76 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
77 extern int cache_name_pos(const char *name, int namelen);
78 extern int add_cache_entry(struct cache_entry *ce);
79 extern int remove_file_from_cache(char *path);
80 extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
81
82 #define MTIME_CHANGED 0x0001
83 #define CTIME_CHANGED 0x0002
84 #define OWNER_CHANGED 0x0004
85 #define MODE_CHANGED 0x0008
86 #define INODE_CHANGED 0x0010
87 #define DATA_CHANGED 0x0020
88
89 /* Return a statically allocated filename matching the sha1 signature */
90 extern char *sha1_file_name(unsigned char *sha1);
91
92 /* Write a memory buffer out to the sha file */
93 extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size);
94
95 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
96 extern void * map_sha1_file(unsigned char *sha1, unsigned long *size);
97 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
98 extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size);
99 extern int write_sha1_file(char *buf, unsigned len);
100 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size);
101
102 /* Convert to/from hex/sha1 representation */
103 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
104 extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */
105
106 /* General helper functions */
107 extern void usage(const char *err);
108
109 #endif /* CACHE_H */