cache.h

   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" */
  27 struct 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  */
  38 struct 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  */
  51 struct 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
  79 const char *sha1_file_directory;
  80 struct cache_entry **active_cache;
  81 unsigned 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 */
  89 extern int read_cache(void);
  90 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  91 extern int cache_name_pos(const char *name, int namelen);
  92 extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  93 extern int remove_file_from_cache(char *path);
  94 extern 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 */
 104 extern char *sha1_file_name(const unsigned char *sha1);
 105
 106 /* Write a memory buffer out to the sha file */
 107 extern 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 */
 110 extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 111 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 112 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 113 extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 114 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
 115
 116 /* Convert to/from hex/sha1 representation */
 117 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 118 extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 119
 120 /* General helper functions */
 121 extern void usage(const char *err);
 122 extern void die(const char *err, ...);
 123 extern int error(const char *err, ...);
 124
 125 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 126
 127 #endif /* CACHE_H */