cache.h

   1 #ifndef CACHE_H
   2 #define CACHE_H
   3
   4 #include <unistd.h>
   5 #include <stdio.h>
   6 #include <sys/stat.h>
   7 #include <fcntl.h>
   8 #include <stddef.h>
   9 #include <stdlib.h>
  10 #include <stdarg.h>
  11 #include <string.h>
  12 #include <errno.h>
  13 #include <sys/mman.h>
  14 #include <netinet/in.h>
  15
  16 #include <openssl/sha.h>
  17 #include <zlib.h>
  18
  19 /*
  20  * Basic data structures for the directory cache
  21  *
  22  * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
  23  * not even trying to be portable. It's trying to be efficient. It's
  24  * just a cache, after all.
  25  */
  26
  27 #define CACHE_SIGNATURE 0x44495243      /* "DIRC" */
  28 struct cache_header {
  29         unsigned int hdr_signature;
  30         unsigned int hdr_version;
  31         unsigned int hdr_entries;
  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  */
  39 struct 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  */
  52 struct 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 ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
  76 #define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
  77
  78 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  79
  80 const char *sha1_file_directory;
  81 struct cache_entry **active_cache;
  82 unsigned int active_nr, active_alloc;
  83
  84 #define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  85 #define DEFAULT_DB_ENVIRONMENT ".git/objects"
  86
  87 #define alloc_nr(x) (((x)+16)*3/2)
  88
  89 /* Initialize and use the cache information */
  90 extern int read_cache(void);
  91 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  92 extern int cache_name_pos(const char *name, int namelen);
  93 extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  94 extern int remove_file_from_cache(char *path);
  95 extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
  96
  97 #define MTIME_CHANGED   0x0001
  98 #define CTIME_CHANGED   0x0002
  99 #define OWNER_CHANGED   0x0004
 100 #define MODE_CHANGED    0x0008
 101 #define INODE_CHANGED   0x0010
 102 #define DATA_CHANGED    0x0020
 103
 104 /* Return a statically allocated filename matching the sha1 signature */
 105 extern char *sha1_file_name(const unsigned char *sha1);
 106
 107 /* Write a memory buffer out to the sha file */
 108 extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
 109
 110 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 111 extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 112 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 113 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 114 extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 115 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
 116
 117 /* Convert to/from hex/sha1 representation */
 118 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 119 extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 120
 121 /* General helper functions */
 122 extern void usage(const char *err);
 123 extern void die(const char *err, ...);
 124 extern int error(const char *err, ...);
 125
 126 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 127
 128 #endif /* CACHE_H */