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 <errno.h>
  11 #include <sys/mman.h>
  12
  13 #include <openssl/sha.h>
  14 #include <zlib.h>
  15
  16 /*
  17  * Basic data structures for the directory cache
  18  *
  19  * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
  20  * not even trying to be portable. It's trying to be efficient. It's
  21  * just a cache, after all.
  22  */
  23
  24 #define CACHE_SIGNATURE 0x44495243      /* "DIRC" */
  25 struct cache_header {
  26         unsigned int signature;
  27         unsigned int version;
  28         unsigned int entries;
  29         unsigned char sha1[20];
  30 };
  31
  32 /*
  33  * The "cache_time" is just the low 32 bits of the
  34  * time. It doesn't matter if it overflows - we only
  35  * check it for equality in the 32 bits we save.
  36  */
  37 struct cache_time {
  38         unsigned int sec;
  39         unsigned int nsec;
  40 };
  41
  42 /*
  43  * dev/ino/uid/gid/size are also just tracked to the low 32 bits
  44  * Again - this is just a (very strong in practice) heuristic that
  45  * the inode hasn't changed.
  46  */
  47 struct cache_entry {
  48         struct cache_time ctime;
  49         struct cache_time mtime;
  50         unsigned int st_dev;
  51         unsigned int st_ino;
  52         unsigned int st_mode;
  53         unsigned int st_uid;
  54         unsigned int st_gid;
  55         unsigned int st_size;
  56         unsigned char sha1[20];
  57         unsigned short namelen;
  58         unsigned char name[0];
  59 };
  60
  61 const char *sha1_file_directory;
  62 struct cache_entry **active_cache;
  63 unsigned int active_nr, active_alloc;
  64
  65 #define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  66 #define DEFAULT_DB_ENVIRONMENT ".dircache/objects"
  67
  68 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  69 #define ce_size(ce) cache_entry_size((ce)->namelen)
  70
  71 #define alloc_nr(x) (((x)+16)*3/2)
  72
  73 /* Initialize the cache information */
  74 extern int read_cache(void);
  75
  76 /* Return a statically allocated filename matching the sha1 signature */
  77 extern char *sha1_file_name(unsigned char *sha1);
  78
  79 /* Write a memory buffer out to the sha file */
  80 extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size);
  81
  82 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
  83 extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size);
  84 extern int write_sha1_file(char *buf, unsigned len);
  85
  86 /* Convert to/from hex/sha1 representation */
  87 extern int get_sha1_hex(char *hex, unsigned char *sha1);
  88 extern char *sha1_to_hex(unsigned char *sha1);  /* static buffer! */
  89
  90 /* General helper functions */
  91 extern void usage(const char *err);
  92
  93 #endif /* CACHE_H */