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                 void *map;
 221                 static int error(const char * string);
 222
 223                 if (errno != EEXIST)
 224                         return -1;
 225 #ifndef COLLISION_CHECK
 226                 fd = open(filename, O_RDONLY);
 227                 if (fd < 0)
 228                         return -1;
 229                 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 230                 if (map == MAP_FAILED)
 231                         return -1;
 232                 if (memcmp(buf, map, size))
 233                         return error("SHA1 collision detected!"
 234                                         " This is bad, bad, BAD!\a\n");
 235 #endif
 236                 return 0;
 237         }
 238         write(fd, buf, size);
 239         close(fd);
 240         return 0;
 241 }
 242
 243 static int error(const char * string)
 244 {
 245         fprintf(stderr, "error: %s\n", string);
 246         return -1;
 247 }
 248
 249 int cache_match_stat(struct cache_entry *ce, struct stat *st)
 250 {
 251         unsigned int changed = 0;
 252
 253         /* nsec seems unreliable - not all filesystems support it, so
 254          * as long as it is in the inode cache you get right nsec
 255          * but after it gets flushed, you get zero nsec. */
 256         if (ce->mtime.sec  != (unsigned int)st->st_mtim.tv_sec
 257 #ifdef NSEC
 258             || ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec
 259 #endif
 260             )
 261                 changed |= MTIME_CHANGED;
 262         if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec
 263 #ifdef NSEC
 264             || ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec
 265 #endif
 266             )
 267                 changed |= CTIME_CHANGED;
 268         if (ce->st_uid != (unsigned int)st->st_uid ||
 269             ce->st_gid != (unsigned int)st->st_gid)
 270                 changed |= OWNER_CHANGED;
 271         if (ce->st_mode != (unsigned int)st->st_mode)
 272                 changed |= MODE_CHANGED;
 273         if (ce->st_dev != (unsigned int)st->st_dev ||
 274             ce->st_ino != (unsigned int)st->st_ino)
 275                 changed |= INODE_CHANGED;
 276         if (ce->st_size != (unsigned int)st->st_size)
 277                 changed |= DATA_CHANGED;
 278         return changed;
 279 }
 280
 281 int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
 282 {
 283         int len = len1 < len2 ? len1 : len2;
 284         int cmp;
 285
 286         cmp = memcmp(name1, name2, len);
 287         if (cmp)
 288                 return cmp;
 289         if (len1 < len2)
 290                 return -1;
 291         if (len1 > len2)
 292                 return 1;
 293         return 0;
 294 }
 295
 296 int cache_name_pos(const char *name, int namelen)
 297 {
 298         int first, last;
 299
 300         first = 0;
 301         last = active_nr;
 302         while (last > first) {
 303                 int next = (last + first) >> 1;
 304                 struct cache_entry *ce = active_cache[next];
 305                 int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen);
 306                 if (!cmp)
 307                         return next;
 308                 if (cmp < 0) {
 309                         last = next;
 310                         continue;
 311                 }
 312                 first = next+1;
 313         }
 314         return -first-1;
 315 }
 316
 317 int remove_file_from_cache(char *path)
 318 {
 319         int pos = cache_name_pos(path, strlen(path));
 320         if (pos >= 0) {
 321                 active_nr--;
 322                 if (pos < active_nr)
 323                         memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 324         }
 325         return 0;
 326 }
 327
 328 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 329 {
 330         int pos;
 331
 332         pos = cache_name_pos(ce->name, ce->namelen);
 333
 334         /* existing match? Just replace it */
 335         if (pos >= 0) {
 336                 active_cache[pos] = ce;
 337                 return 0;
 338         }
 339         pos = -pos-1;
 340
 341         if (!ok_to_add)
 342                 return -1;
 343
 344         /* Make sure the array is big enough .. */
 345         if (active_nr == active_alloc) {
 346                 active_alloc = alloc_nr(active_alloc);
 347                 active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 348         }
 349
 350         /* Add it in.. */
 351         active_nr++;
 352         if (active_nr > pos)
 353                 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 354         active_cache[pos] = ce;
 355         return 0;
 356 }
 357
 358 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 359 {
 360         SHA_CTX c;
 361         unsigned char sha1[20];
 362
 363         if (hdr->signature != CACHE_SIGNATURE)
 364                 return error("bad signature");
 365         if (hdr->version != 1)
 366                 return error("bad version");
 367         SHA1_Init(&c);
 368         SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
 369         SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
 370         SHA1_Final(sha1, &c);
 371         if (memcmp(sha1, hdr->sha1, 20))
 372                 return error("bad header sha1");
 373         return 0;
 374 }
 375
 376 int read_cache(void)
 377 {
 378         int fd, i;
 379         struct stat st;
 380         unsigned long size, offset;
 381         void *map;
 382         struct cache_header *hdr;
 383
 384         errno = EBUSY;
 385         if (active_cache)
 386                 return error("more than one cachefile");
 387         errno = ENOENT;
 388         sha1_file_directory = getenv(DB_ENVIRONMENT);
 389         if (!sha1_file_directory)
 390                 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 391         if (access(sha1_file_directory, X_OK) < 0)
 392                 return error("no access to SHA1 file directory");
 393         fd = open(".git/index", O_RDONLY);
 394         if (fd < 0)
 395                 return (errno == ENOENT) ? 0 : error("open failed");
 396
 397         size = 0; // avoid gcc warning
 398         map = (void *)-1;
 399         if (!fstat(fd, &st)) {
 400                 size = st.st_size;
 401                 errno = EINVAL;
 402                 if (size >= sizeof(struct cache_header))
 403                         map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 404         }
 405         close(fd);
 406         if (-1 == (int)(long)map)
 407                 return error("mmap failed");
 408
 409         hdr = map;
 410         if (verify_hdr(hdr, size) < 0)
 411                 goto unmap;
 412
 413         active_nr = hdr->entries;
 414         active_alloc = alloc_nr(active_nr);
 415         active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 416
 417         offset = sizeof(*hdr);
 418         for (i = 0; i < hdr->entries; i++) {
 419                 struct cache_entry *ce = map + offset;
 420                 offset = offset + ce_size(ce);
 421                 active_cache[i] = ce;
 422         }
 423         return active_nr;
 424
 425 unmap:
 426         munmap(map, size);
 427         errno = EINVAL;
 428         return error("verify header failed");
 429 }
 430
 431 int write_cache(int newfd, struct cache_entry **cache, int entries)
 432 {
 433         SHA_CTX c;
 434         struct cache_header hdr;
 435         int i;
 436
 437         hdr.signature = CACHE_SIGNATURE;
 438         hdr.version = 1;
 439         hdr.entries = entries;
 440
 441         SHA1_Init(&c);
 442         SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
 443         for (i = 0; i < entries; i++) {
 444                 struct cache_entry *ce = cache[i];
 445                 int size = ce_size(ce);
 446                 SHA1_Update(&c, ce, size);
 447         }
 448         SHA1_Final(hdr.sha1, &c);
 449
 450         if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
 451                 return -1;
 452
 453         for (i = 0; i < entries; i++) {
 454                 struct cache_entry *ce = cache[i];
 455                 int size = ce_size(ce);
 456                 if (write(newfd, ce, size) != size)
 457                         return -1;
 458         }
 459         return 0;
 460 }