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 <sys/param.h>
  15 #include <netinet/in.h>
  16
  17 #include SHA1_HEADER
  18 #include <zlib.h>
  19
  20 /*
  21  * Basic data structures for the directory cache
  22  *
  23  * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
  24  * not even trying to be portable. It's trying to be efficient. It's
  25  * just a cache, after all.
  26  */
  27
  28 #define CACHE_SIGNATURE 0x44495243      /* "DIRC" */
  29 struct cache_header {
  30         unsigned int hdr_signature;
  31         unsigned int hdr_version;
  32         unsigned int hdr_entries;
  33 };
  34
  35 /*
  36  * The "cache_time" is just the low 32 bits of the
  37  * time. It doesn't matter if it overflows - we only
  38  * check it for equality in the 32 bits we save.
  39  */
  40 struct cache_time {
  41         unsigned int sec;
  42         unsigned int nsec;
  43 };
  44
  45 /*
  46  * dev/ino/uid/gid/size are also just tracked to the low 32 bits
  47  * Again - this is just a (very strong in practice) heuristic that
  48  * the inode hasn't changed.
  49  *
  50  * We save the fields in big-endian order to allow using the
  51  * index file over NFS transparently.
  52  */
  53 struct cache_entry {
  54         struct cache_time ce_ctime;
  55         struct cache_time ce_mtime;
  56         unsigned int ce_dev;
  57         unsigned int ce_ino;
  58         unsigned int ce_mode;
  59         unsigned int ce_uid;
  60         unsigned int ce_gid;
  61         unsigned int ce_size;
  62         unsigned char sha1[20];
  63         unsigned short ce_flags;
  64         char name[0];
  65 };
  66
  67 #define CE_NAMEMASK  (0x0fff)
  68 #define CE_STAGEMASK (0x3000)
  69 #define CE_STAGESHIFT 12
  70
  71 #define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
  72 #define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
  73 #define ce_size(ce) cache_entry_size(ce_namelen(ce))
  74 #define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
  75
  76 #define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
  77 #define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
  78
  79 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  80
  81 const char *sha1_file_directory;
  82 struct cache_entry **active_cache;
  83 unsigned int active_nr, active_alloc;
  84
  85 #define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  86 #define DEFAULT_DB_ENVIRONMENT ".git/objects"
  87
  88 #define get_object_directory() (getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT)
  89
  90 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
  91 #define DEFAULT_INDEX_ENVIRONMENT ".git/index"
  92
  93 #define get_index_file() (getenv(INDEX_ENVIRONMENT) ? : DEFAULT_INDEX_ENVIRONMENT)
  94
  95 #define alloc_nr(x) (((x)+16)*3/2)
  96
  97 /* Initialize and use the cache information */
  98 extern int read_cache(void);
  99 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
 100 extern int cache_name_pos(const char *name, int namelen);
 101 extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
 102 extern int remove_entry_at(int pos);
 103 extern int remove_file_from_cache(char *path);
 104 extern int same_name(struct cache_entry *a, struct cache_entry *b);
 105 extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
 106
 107 #define MTIME_CHANGED   0x0001
 108 #define CTIME_CHANGED   0x0002
 109 #define OWNER_CHANGED   0x0004
 110 #define MODE_CHANGED    0x0008
 111 #define INODE_CHANGED   0x0010
 112 #define DATA_CHANGED    0x0020
 113
 114 /* Return a statically allocated filename matching the sha1 signature */
 115 extern char *sha1_file_name(const unsigned char *sha1);
 116
 117 /* Write a memory buffer out to the sha file */
 118 extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
 119
 120 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 121 extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 122 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 123 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 124 extern int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *return_sha1);
 125
 126 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
 127
 128 /* Read a tree into the cache */
 129 extern int read_tree(void *buffer, unsigned long size, int stage);
 130
 131 extern int write_sha1_from_fd(const unsigned char *sha1, int fd);
 132
 133 extern int has_sha1_file(const unsigned char *sha1);
 134
 135 /* Convert to/from hex/sha1 representation */
 136 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 137 extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 138
 139 /* General helper functions */
 140 extern void usage(const char *err);
 141 extern void die(const char *err, ...);
 142 extern int error(const char *err, ...);
 143
 144 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 145
 146 extern void *read_tree_with_tree_or_commit_sha1(const unsigned char *sha1,
 147                                                 unsigned long *size,
 148                                                 unsigned char *tree_sha1_ret);
 149
 150 static inline void *xmalloc(int size)
 151 {
 152         void *ret = malloc(size);
 153         if (!ret)
 154                 die("Out of memory, malloc failed");
 155         return ret;
 156 }
 157
 158 static inline void *xrealloc(void *ptr, int size)
 159 {
 160         void *ret = realloc(ptr, size);
 161         if (!ret)
 162                 die("Out of memory, realloc failed");
 163         return ret;
 164 }
 165
 166 #endif /* CACHE_H */