Andrew's git - gitweb.git/blob

   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" */
  26struct 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 */
  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.
  47 */
  48struct 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
  62const char *sha1_file_directory;
  63struct cache_entry **active_cache;
  64unsigned 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 */
  75extern int read_cache(void);
  76extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  77extern int cache_name_pos(const char *name, int namelen);
  78extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  79extern int remove_file_from_cache(char *path);
  80extern 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 */
  90extern char *sha1_file_name(const unsigned char *sha1);
  91
  92/* Write a memory buffer out to the sha file */
  93extern 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 */
  96extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
  97extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
  98extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
  99extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 100extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size);
 101
 102/* Convert to/from hex/sha1 representation */
 103extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 104extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 105
 106/* General helper functions */
 107extern void usage(const char *err, ...);
 108extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 109
 110#endif /* CACHE_H */