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 ".git/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, int ok_to_add);
  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(const unsigned char *sha1);
  91
  92 /* Write a memory buffer out to the sha file */
  93 extern int write_sha1_buffer(const 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(const 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(const unsigned char *sha1, char *type, unsigned long *size);
  99 extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 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 extern void die(const char *err, ...);
 109 extern int error(const char *err, ...);
 110
 111 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 112
 113 #endif /* CACHE_H */