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#include <netinet/in.h>
  14
  15#include <openssl/sha.h>
  16#include <zlib.h>
  17
  18/*
  19 * Basic data structures for the directory cache
  20 *
  21 * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
  22 * not even trying to be portable. It's trying to be efficient. It's
  23 * just a cache, after all.
  24 */
  25
  26#define CACHE_SIGNATURE 0x44495243      /* "DIRC" */
  27struct cache_header {
  28        unsigned int hdr_signature;
  29        unsigned int hdr_version;
  30        unsigned int hdr_entries;
  31        unsigned char sha1[20];
  32};
  33
  34/*
  35 * The "cache_time" is just the low 32 bits of the
  36 * time. It doesn't matter if it overflows - we only
  37 * check it for equality in the 32 bits we save.
  38 */
  39struct cache_time {
  40        unsigned int sec;
  41        unsigned int nsec;
  42};
  43
  44/*
  45 * dev/ino/uid/gid/size are also just tracked to the low 32 bits
  46 * Again - this is just a (very strong in practice) heuristic that
  47 * the inode hasn't changed.
  48 *
  49 * We save the fields in big-endian order to allow using the
  50 * index file over NFS transparently.
  51 */
  52struct cache_entry {
  53        struct cache_time ce_ctime;
  54        struct cache_time ce_mtime;
  55        unsigned int ce_dev;
  56        unsigned int ce_ino;
  57        unsigned int ce_mode;
  58        unsigned int ce_uid;
  59        unsigned int ce_gid;
  60        unsigned int ce_size;
  61        unsigned char sha1[20];
  62        unsigned short ce_flags;
  63        char name[0];
  64};
  65
  66#define CE_NAMEMASK  (0x0fff)
  67#define CE_STAGEMASK (0x3000)
  68#define CE_STAGESHIFT 12
  69
  70#define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
  71#define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
  72#define ce_size(ce) cache_entry_size(ce_namelen(ce))
  73#define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
  74
  75#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  76
  77const char *sha1_file_directory;
  78struct cache_entry **active_cache;
  79unsigned int active_nr, active_alloc;
  80
  81#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  82#define DEFAULT_DB_ENVIRONMENT ".git/objects"
  83
  84#define alloc_nr(x) (((x)+16)*3/2)
  85
  86/* Initialize and use the cache information */
  87extern int read_cache(void);
  88extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  89extern int cache_name_pos(const char *name, int namelen);
  90extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  91extern int remove_file_from_cache(char *path);
  92extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
  93
  94#define MTIME_CHANGED   0x0001
  95#define CTIME_CHANGED   0x0002
  96#define OWNER_CHANGED   0x0004
  97#define MODE_CHANGED    0x0008
  98#define INODE_CHANGED   0x0010
  99#define DATA_CHANGED    0x0020
 100
 101/* Return a statically allocated filename matching the sha1 signature */
 102extern char *sha1_file_name(const unsigned char *sha1);
 103
 104/* Write a memory buffer out to the sha file */
 105extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
 106
 107/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 108extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 109extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 110extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 111extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 112extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size);
 113
 114/* Convert to/from hex/sha1 representation */
 115extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 116extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 117
 118/* General helper functions */
 119extern void usage(const char *err);
 120extern void die(const char *err, ...);
 121extern int error(const char *err, ...);
 122
 123extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 124
 125#endif /* CACHE_H */