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 <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 */