Andrew's git - gitweb.git/blob

eab355da5d2f6595053f28f0cca61181ac314ee9
   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};
  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 *
  48 * We save the fields in big-endian order to allow using the
  49 * index file over NFS transparently.
  50 */
  51struct cache_entry {
  52        struct cache_time ce_ctime;
  53        struct cache_time ce_mtime;
  54        unsigned int ce_dev;
  55        unsigned int ce_ino;
  56        unsigned int ce_mode;
  57        unsigned int ce_uid;
  58        unsigned int ce_gid;
  59        unsigned int ce_size;
  60        unsigned char sha1[20];
  61        unsigned short ce_flags;
  62        char name[0];
  63};
  64
  65#define CE_NAMEMASK  (0x0fff)
  66#define CE_STAGEMASK (0x3000)
  67#define CE_STAGESHIFT 12
  68
  69#define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
  70#define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
  71#define ce_size(ce) cache_entry_size(ce_namelen(ce))
  72#define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
  73
  74#define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
  75#define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
  76
  77#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  78
  79const char *sha1_file_directory;
  80struct cache_entry **active_cache;
  81unsigned int active_nr, active_alloc;
  82
  83#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  84#define DEFAULT_DB_ENVIRONMENT ".git/objects"
  85
  86#define alloc_nr(x) (((x)+16)*3/2)
  87
  88/* Initialize and use the cache information */
  89extern int read_cache(void);
  90extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  91extern int cache_name_pos(const char *name, int namelen);
  92extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  93extern int remove_file_from_cache(char *path);
  94extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
  95
  96#define MTIME_CHANGED   0x0001
  97#define CTIME_CHANGED   0x0002
  98#define OWNER_CHANGED   0x0004
  99#define MODE_CHANGED    0x0008
 100#define INODE_CHANGED   0x0010
 101#define DATA_CHANGED    0x0020
 102
 103/* Return a statically allocated filename matching the sha1 signature */
 104extern char *sha1_file_name(const unsigned char *sha1);
 105
 106/* Write a memory buffer out to the sha file */
 107extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
 108
 109/* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 110extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 111extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 112extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 113extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 114extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
 115
 116/* Convert to/from hex/sha1 representation */
 117extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 118extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 119
 120/* General helper functions */
 121extern void usage(const char *err);
 122extern void die(const char *err, ...);
 123extern int error(const char *err, ...);
 124
 125extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 126
 127#endif /* CACHE_H */