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 #if ZLIB_VERNUM < 0x1200
  21 #define deflateBound(c,s)  ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
  22 #endif
  23
  24 /*
  25  * Basic data structures for the directory cache
  26  *
  27  * NOTE NOTE NOTE! This is all in the native CPU byte format. It's
  28  * not even trying to be portable. It's trying to be efficient. It's
  29  * just a cache, after all.
  30  */
  31
  32 #define CACHE_SIGNATURE 0x44495243      /* "DIRC" */
  33 struct cache_header {
  34         unsigned int hdr_signature;
  35         unsigned int hdr_version;
  36         unsigned int hdr_entries;
  37 };
  38
  39 /*
  40  * The "cache_time" is just the low 32 bits of the
  41  * time. It doesn't matter if it overflows - we only
  42  * check it for equality in the 32 bits we save.
  43  */
  44 struct cache_time {
  45         unsigned int sec;
  46         unsigned int nsec;
  47 };
  48
  49 /*
  50  * dev/ino/uid/gid/size are also just tracked to the low 32 bits
  51  * Again - this is just a (very strong in practice) heuristic that
  52  * the inode hasn't changed.
  53  *
  54  * We save the fields in big-endian order to allow using the
  55  * index file over NFS transparently.
  56  */
  57 struct cache_entry {
  58         struct cache_time ce_ctime;
  59         struct cache_time ce_mtime;
  60         unsigned int ce_dev;
  61         unsigned int ce_ino;
  62         unsigned int ce_mode;
  63         unsigned int ce_uid;
  64         unsigned int ce_gid;
  65         unsigned int ce_size;
  66         unsigned char sha1[20];
  67         unsigned short ce_flags;
  68         char name[0];
  69 };
  70
  71 #define CE_NAMEMASK  (0x0fff)
  72 #define CE_STAGEMASK (0x3000)
  73 #define CE_STAGESHIFT 12
  74
  75 #define create_ce_flags(len, stage) htons((len) | ((stage) << CE_STAGESHIFT))
  76 #define ce_namelen(ce) (CE_NAMEMASK & ntohs((ce)->ce_flags))
  77 #define ce_size(ce) cache_entry_size(ce_namelen(ce))
  78 #define ce_stage(ce) ((CE_STAGEMASK & ntohs((ce)->ce_flags)) >> CE_STAGESHIFT)
  79
  80 #define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
  81 #define create_ce_mode(mode) htonl(S_IFREG | ce_permissions(mode))
  82
  83 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
  84
  85 const char *sha1_file_directory;
  86 struct cache_entry **active_cache;
  87 unsigned int active_nr, active_alloc;
  88
  89 #define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY"
  90 #define DEFAULT_DB_ENVIRONMENT ".git/objects"
  91
  92 #define get_object_directory() (getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT)
  93
  94 #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
  95 #define DEFAULT_INDEX_ENVIRONMENT ".git/index"
  96
  97 #define get_index_file() (getenv(INDEX_ENVIRONMENT) ? : DEFAULT_INDEX_ENVIRONMENT)
  98
  99 #define alloc_nr(x) (((x)+16)*3/2)
 100
 101 /* Initialize and use the cache information */
 102 extern int read_cache(void);
 103 extern int write_cache(int newfd, struct cache_entry **cache, int entries);
 104 extern int cache_name_pos(const char *name, int namelen);
 105 extern int add_cache_entry(struct cache_entry *ce, int ok_to_add);
 106 extern int remove_entry_at(int pos);
 107 extern int remove_file_from_cache(char *path);
 108 extern int same_name(struct cache_entry *a, struct cache_entry *b);
 109 extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
 110
 111 #define MTIME_CHANGED   0x0001
 112 #define CTIME_CHANGED   0x0002
 113 #define OWNER_CHANGED   0x0004
 114 #define MODE_CHANGED    0x0008
 115 #define INODE_CHANGED   0x0010
 116 #define DATA_CHANGED    0x0020
 117
 118 /* Return a statically allocated filename matching the sha1 signature */
 119 extern char *sha1_file_name(const unsigned char *sha1);
 120
 121 /* Write a memory buffer out to the sha file */
 122 extern int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size);
 123
 124 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 125 extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
 126 extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
 127 extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);
 128 extern int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *return_sha1);
 129
 130 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size, const char *type);
 131
 132 /* Read a tree into the cache */
 133 extern int read_tree(void *buffer, unsigned long size, int stage);
 134
 135 extern int write_sha1_from_fd(const unsigned char *sha1, int fd);
 136
 137 extern int has_sha1_file(const unsigned char *sha1);
 138
 139 /* Convert to/from hex/sha1 representation */
 140 extern int get_sha1_hex(const char *hex, unsigned char *sha1);
 141 extern char *sha1_to_hex(const unsigned char *sha1);    /* static buffer result! */
 142
 143 /* General helper functions */
 144 extern void usage(const char *err);
 145 extern void die(const char *err, ...);
 146 extern int error(const char *err, ...);
 147
 148 extern int cache_name_compare(const char *name1, int len1, const char *name2, int len2);
 149
 150 extern void *read_object_with_reference(const unsigned char *sha1,
 151                                         const unsigned char *required_type,
 152                                         unsigned long *size,
 153                                         unsigned char *sha1_ret);
 154
 155 void parse_date(char *date, char *buf, int bufsize);
 156 void datestamp(char *buf, int bufsize);
 157
 158 static inline void *xmalloc(int size)
 159 {
 160         void *ret = malloc(size);
 161         if (!ret)
 162                 die("Out of memory, malloc failed");
 163         return ret;
 164 }
 165
 166 static inline void *xrealloc(void *ptr, int size)
 167 {
 168         void *ret = realloc(ptr, size);
 169         if (!ret)
 170                 die("Out of memory, realloc failed");
 171         return ret;
 172 }
 173
 174 #endif /* CACHE_H */