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         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  */
  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 cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  76
  77 const char *sha1_file_directory;
  78 struct cache_entry **active_cache;
  79 unsigned 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 */
  87 extern int read_cache(void);
  88 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
  89 extern int cache_name_pos(const char *name, int namelen);
  90 extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
  91 extern int remove_file_from_cache(char *path);
  92 extern 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 */
 102 extern char *sha1_file_name(const unsigned char *sha1);
 103
 104 /* Write a memory buffer out to the sha file */
 105 extern 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 */
 108 extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 109 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 110 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 111 extern int write_sha1_file(char *buf, unsigned len, unsigned char *return_sha1);
 112 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size);
 113
 114 /* Convert to/from hex/sha1 representation */
 115 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 116 extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 117
 118 /* General helper functions */
 119 extern void usage(const char *err);
 120 extern void die(const char *err, ...);
 121 extern int error(const char *err, ...);
 122
 123 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 124
 125 #endif /* CACHE_H */