read-cache.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include "cache.h"
   7
   8 const char *sha1_file_directory = NULL;
   9 struct cache_entry **active_cache = NULL;
  10 unsigned int active_nr = 0, active_alloc = 0;
  11
  12 void usage(const char *err, ...)
  13 {
  14         va_list args;
  15         char string[200];
  16
  17         va_start(args, err);
  18         vsnprintf(string, sizeof(string), err, args);
  19         va_end(args);
  20         fprintf(stderr, "%s\n", string);
  21         exit(1);
  22 }
  23
  24 static unsigned hexval(char c)
  25 {
  26         if (c >= '0' && c <= '9')
  27                 return c - '0';
  28         if (c >= 'a' && c <= 'f')
  29                 return c - 'a' + 10;
  30         if (c >= 'A' && c <= 'F')
  31                 return c - 'A' + 10;
  32         return ~0;
  33 }
  34
  35 int get_sha1_hex(const char *hex, unsigned char *sha1)
  36 {
  37         int i;
  38         for (i = 0; i < 20; i++) {
  39                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  40                 if (val & ~0xff)
  41                         return -1;
  42                 *sha1++ = val;
  43                 hex += 2;
  44         }
  45         return 0;
  46 }
  47
  48 char * sha1_to_hex(const unsigned char *sha1)
  49 {
  50         static char buffer[50];
  51         static const char hex[] = "0123456789abcdef";
  52         char *buf = buffer;
  53         int i;
  54
  55         for (i = 0; i < 20; i++) {
  56                 unsigned int val = *sha1++;
  57                 *buf++ = hex[val >> 4];
  58                 *buf++ = hex[val & 0xf];
  59         }
  60         return buffer;
  61 }
  62
  63 /*
  64  * NOTE! This returns a statically allocated buffer, so you have to be
  65  * careful about using it. Do a "strdup()" if you need to save the
  66  * filename.
  67  */
  68 char *sha1_file_name(const unsigned char *sha1)
  69 {
  70         int i;
  71         static char *name, *base;
  72
  73         if (!base) {
  74                 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
  75                 int len = strlen(sha1_file_directory);
  76                 base = malloc(len + 60);
  77                 memcpy(base, sha1_file_directory, len);
  78                 memset(base+len, 0, 60);
  79                 base[len] = '/';
  80                 base[len+3] = '/';
  81                 name = base + len + 1;
  82         }
  83         for (i = 0; i < 20; i++) {
  84                 static char hex[] = "0123456789abcdef";
  85                 unsigned int val = sha1[i];
  86                 char *pos = name + i*2 + (i > 0);
  87                 *pos++ = hex[val >> 4];
  88                 *pos = hex[val & 0xf];
  89         }
  90         return base;
  91 }
  92
  93 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
  94 {
  95         unsigned char real_sha1[20];
  96         SHA_CTX c;
  97
  98         SHA1_Init(&c);
  99         SHA1_Update(&c, map, size);
 100         SHA1_Final(real_sha1, &c);
 101         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 102 }
 103
 104 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 105 {
 106         char *filename = sha1_file_name(sha1);
 107         int fd = open(filename, O_RDONLY);
 108         struct stat st;
 109         void *map;
 110
 111         if (fd < 0) {
 112                 perror(filename);
 113                 return NULL;
 114         }
 115         if (fstat(fd, &st) < 0) {
 116                 close(fd);
 117                 return NULL;
 118         }
 119         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 120         close(fd);
 121         if (-1 == (int)(long)map)
 122                 return NULL;
 123         *size = st.st_size;
 124         return map;
 125 }
 126
 127 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 128 {
 129         int ret, bytes;
 130         z_stream stream;
 131         char buffer[8192];
 132         char *buf;
 133
 134         /* Get the data stream */
 135         memset(&stream, 0, sizeof(stream));
 136         stream.next_in = map;
 137         stream.avail_in = mapsize;
 138         stream.next_out = buffer;
 139         stream.avail_out = sizeof(buffer);
 140
 141         inflateInit(&stream);
 142         ret = inflate(&stream, 0);
 143         if (sscanf(buffer, "%10s %lu", type, size) != 2)
 144                 return NULL;
 145
 146         bytes = strlen(buffer) + 1;
 147         buf = malloc(*size);
 148         if (!buf)
 149                 return NULL;
 150
 151         memcpy(buf, buffer + bytes, stream.total_out - bytes);
 152         bytes = stream.total_out - bytes;
 153         if (bytes < *size && ret == Z_OK) {
 154                 stream.next_out = buf + bytes;
 155                 stream.avail_out = *size - bytes;
 156                 while (inflate(&stream, Z_FINISH) == Z_OK)
 157                         /* nothing */;
 158         }
 159         inflateEnd(&stream);
 160         return buf;
 161 }
 162
 163 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 164 {
 165         unsigned long mapsize;
 166         void *map, *buf;
 167
 168         map = map_sha1_file(sha1, &mapsize);
 169         if (map) {
 170                 buf = unpack_sha1_file(map, mapsize, type, size);
 171                 munmap(map, mapsize);
 172                 return buf;
 173         }
 174         return NULL;
 175 }
 176
 177 int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 178 {
 179         int size;
 180         char *compressed;
 181         z_stream stream;
 182         unsigned char sha1[20];
 183         SHA_CTX c;
 184
 185         /* Set it up */
 186         memset(&stream, 0, sizeof(stream));
 187         deflateInit(&stream, Z_BEST_COMPRESSION);
 188         size = deflateBound(&stream, len);
 189         compressed = malloc(size);
 190
 191         /* Compress it */
 192         stream.next_in = buf;
 193         stream.avail_in = len;
 194         stream.next_out = compressed;
 195         stream.avail_out = size;
 196         while (deflate(&stream, Z_FINISH) == Z_OK)
 197                 /* nothing */;
 198         deflateEnd(&stream);
 199         size = stream.total_out;
 200
 201         /* Sha1.. */
 202         SHA1_Init(&c);
 203         SHA1_Update(&c, compressed, size);
 204         SHA1_Final(sha1, &c);
 205
 206         if (write_sha1_buffer(sha1, compressed, size) < 0)
 207                 return -1;
 208         if (returnsha1)
 209                 memcpy(returnsha1, sha1, 20);
 210         return 0;
 211 }
 212
 213 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 214 {
 215         char *filename = sha1_file_name(sha1);
 216         int fd;
 217
 218         fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 219         if (fd < 0)
 220                 return (errno == EEXIST) ? 0 : -1;
 221         write(fd, buf, size);
 222         close(fd);
 223         return 0;
 224 }
 225
 226 static int error(const char * string)
 227 {
 228         fprintf(stderr, "error: %s\n", string);
 229         return -1;
 230 }
 231
 232 int cache_match_stat(struct cache_entry *ce, struct stat *st)
 233 {
 234         unsigned int changed = 0;
 235
 236         if (ce->mtime.sec  != (unsigned int)st->st_mtim.tv_sec ||
 237             ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec)
 238                 changed |= MTIME_CHANGED;
 239         if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec ||
 240             ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec)
 241                 changed |= CTIME_CHANGED;
 242         if (ce->st_uid != (unsigned int)st->st_uid ||
 243             ce->st_gid != (unsigned int)st->st_gid)
 244                 changed |= OWNER_CHANGED;
 245         if (ce->st_mode != (unsigned int)st->st_mode)
 246                 changed |= MODE_CHANGED;
 247         if (ce->st_dev != (unsigned int)st->st_dev ||
 248             ce->st_ino != (unsigned int)st->st_ino)
 249                 changed |= INODE_CHANGED;
 250         if (ce->st_size != (unsigned int)st->st_size)
 251                 changed |= DATA_CHANGED;
 252         return changed;
 253 }
 254
 255 int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
 256 {
 257         int len = len1 < len2 ? len1 : len2;
 258         int cmp;
 259
 260         cmp = memcmp(name1, name2, len);
 261         if (cmp)
 262                 return cmp;
 263         if (len1 < len2)
 264                 return -1;
 265         if (len1 > len2)
 266                 return 1;
 267         return 0;
 268 }
 269
 270 int cache_name_pos(const char *name, int namelen)
 271 {
 272         int first, last;
 273
 274         first = 0;
 275         last = active_nr;
 276         while (last > first) {
 277                 int next = (last + first) >> 1;
 278                 struct cache_entry *ce = active_cache[next];
 279                 int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
 280                 if (!cmp)
 281                         return next;
 282                 if (cmp < 0) {
 283                         last = next;
 284                         continue;
 285                 }
 286                 first = next+1;
 287         }
 288         return -first-1;
 289 }
 290
 291 int remove_file_from_cache(char *path)
 292 {
 293         int pos = cache_name_pos(path, strlen(path));
 294         if (pos >= 0) {
 295                 active_nr--;
 296                 if (pos < active_nr)
 297                         memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 298         }
 299         return 0;
 300 }
 301
 302 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 303 {
 304         int pos;
 305
 306         pos = cache_name_pos(ce->name, ce->namelen);
 307
 308         /* existing match? Just replace it */
 309         if (pos >= 0) {
 310                 active_cache[pos] = ce;
 311                 return 0;
 312         }
 313         pos = -pos-1;
 314
 315         if (!ok_to_add)
 316                 return -1;
 317
 318         /* Make sure the array is big enough .. */
 319         if (active_nr == active_alloc) {
 320                 active_alloc = alloc_nr(active_alloc);
 321                 active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 322         }
 323
 324         /* Add it in.. */
 325         active_nr++;
 326         if (active_nr > pos)
 327                 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 328         active_cache[pos] = ce;
 329         return 0;
 330 }
 331
 332 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 333 {
 334         SHA_CTX c;
 335         unsigned char sha1[20];
 336
 337         if (hdr->signature != CACHE_SIGNATURE)
 338                 return error("bad signature");
 339         if (hdr->version != 1)
 340                 return error("bad version");
 341         SHA1_Init(&c);
 342         SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
 343         SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
 344         SHA1_Final(sha1, &c);
 345         if (memcmp(sha1, hdr->sha1, 20))
 346                 return error("bad header sha1");
 347         return 0;
 348 }
 349
 350 int read_cache(void)
 351 {
 352         int fd, i;
 353         struct stat st;
 354         unsigned long size, offset;
 355         void *map;
 356         struct cache_header *hdr;
 357
 358         errno = EBUSY;
 359         if (active_cache)
 360                 return error("more than one cachefile");
 361         errno = ENOENT;
 362         sha1_file_directory = getenv(DB_ENVIRONMENT);
 363         if (!sha1_file_directory)
 364                 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 365         if (access(sha1_file_directory, X_OK) < 0)
 366                 return error("no access to SHA1 file directory");
 367         fd = open(".git/index", O_RDONLY);
 368         if (fd < 0)
 369                 return (errno == ENOENT) ? 0 : error("open failed");
 370
 371         size = 0; // avoid gcc warning
 372         map = (void *)-1;
 373         if (!fstat(fd, &st)) {
 374                 size = st.st_size;
 375                 errno = EINVAL;
 376                 if (size >= sizeof(struct cache_header))
 377                         map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 378         }
 379         close(fd);
 380         if (-1 == (int)(long)map)
 381                 return error("mmap failed");
 382
 383         hdr = map;
 384         if (verify_hdr(hdr, size) < 0)
 385                 goto unmap;
 386
 387         active_nr = hdr->entries;
 388         active_alloc = alloc_nr(active_nr);
 389         active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 390
 391         offset = sizeof(*hdr);
 392         for (i = 0; i < hdr->entries; i++) {
 393                 struct cache_entry *ce = map + offset;
 394                 offset = offset + ce_size(ce);
 395                 active_cache[i] = ce;
 396         }
 397         return active_nr;
 398
 399 unmap:
 400         munmap(map, size);
 401         errno = EINVAL;
 402         return error("verify header failed");
 403 }
 404
 405 int write_cache(int newfd, struct cache_entry **cache, int entries)
 406 {
 407         SHA_CTX c;
 408         struct cache_header hdr;
 409         int i;
 410
 411         hdr.signature = CACHE_SIGNATURE;
 412         hdr.version = 1;
 413         hdr.entries = entries;
 414
 415         SHA1_Init(&c);
 416         SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
 417         for (i = 0; i < entries; i++) {
 418                 struct cache_entry *ce = cache[i];
 419                 int size = ce_size(ce);
 420                 SHA1_Update(&c, ce, size);
 421         }
 422         SHA1_Final(hdr.sha1, &c);
 423
 424         if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
 425                 return -1;
 426
 427         for (i = 0; i < entries; i++) {
 428                 struct cache_entry *ce = cache[i];
 429                 int size = ce_size(ce);
 430                 if (write(newfd, ce, size) != size)
 431                         return -1;
 432         }
 433         return 0;
 434 }