read-cache.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include <stdarg.h>
   7 #include "cache.h"
   8
   9 const char *sha1_file_directory = NULL;
  10 struct cache_entry **active_cache = NULL;
  11 unsigned int active_nr = 0, active_alloc = 0;
  12
  13 void usage(const char *err)
  14 {
  15         fprintf(stderr, "usage: %s\n", err);
  16         exit(1);
  17 }
  18
  19 static void report(const char *prefix, const char *err, va_list params)
  20 {
  21         fputs(prefix, stderr);
  22         vfprintf(stderr, err, params);
  23         fputs("\n", stderr);
  24 }
  25
  26 void die(const char *err, ...)
  27 {
  28         va_list params;
  29
  30         va_start(params, err);
  31         report("fatal: ", err, params);
  32         va_end(params);
  33         exit(1);
  34 }
  35
  36 int error(const char *err, ...)
  37 {
  38         va_list params;
  39
  40         va_start(params, err);
  41         report("error: ", err, params);
  42         va_end(params);
  43         return -1;
  44 }
  45
  46
  47 static unsigned hexval(char c)
  48 {
  49         if (c >= '0' && c <= '9')
  50                 return c - '0';
  51         if (c >= 'a' && c <= 'f')
  52                 return c - 'a' + 10;
  53         if (c >= 'A' && c <= 'F')
  54                 return c - 'A' + 10;
  55         return ~0;
  56 }
  57
  58 int get_sha1_hex(const char *hex, unsigned char *sha1)
  59 {
  60         int i;
  61         for (i = 0; i < 20; i++) {
  62                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  63                 if (val & ~0xff)
  64                         return -1;
  65                 *sha1++ = val;
  66                 hex += 2;
  67         }
  68         return 0;
  69 }
  70
  71 char * sha1_to_hex(const unsigned char *sha1)
  72 {
  73         static char buffer[50];
  74         static const char hex[] = "0123456789abcdef";
  75         char *buf = buffer;
  76         int i;
  77
  78         for (i = 0; i < 20; i++) {
  79                 unsigned int val = *sha1++;
  80                 *buf++ = hex[val >> 4];
  81                 *buf++ = hex[val & 0xf];
  82         }
  83         return buffer;
  84 }
  85
  86 /*
  87  * NOTE! This returns a statically allocated buffer, so you have to be
  88  * careful about using it. Do a "strdup()" if you need to save the
  89  * filename.
  90  */
  91 char *sha1_file_name(const unsigned char *sha1)
  92 {
  93         int i;
  94         static char *name, *base;
  95
  96         if (!base) {
  97                 char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
  98                 int len = strlen(sha1_file_directory);
  99                 base = malloc(len + 60);
 100                 memcpy(base, sha1_file_directory, len);
 101                 memset(base+len, 0, 60);
 102                 base[len] = '/';
 103                 base[len+3] = '/';
 104                 name = base + len + 1;
 105         }
 106         for (i = 0; i < 20; i++) {
 107                 static char hex[] = "0123456789abcdef";
 108                 unsigned int val = sha1[i];
 109                 char *pos = name + i*2 + (i > 0);
 110                 *pos++ = hex[val >> 4];
 111                 *pos = hex[val & 0xf];
 112         }
 113         return base;
 114 }
 115
 116 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
 117 {
 118         unsigned char real_sha1[20];
 119         SHA_CTX c;
 120
 121         SHA1_Init(&c);
 122         SHA1_Update(&c, map, size);
 123         SHA1_Final(real_sha1, &c);
 124         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 125 }
 126
 127 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 128 {
 129         char *filename = sha1_file_name(sha1);
 130         int fd = open(filename, O_RDONLY);
 131         struct stat st;
 132         void *map;
 133
 134         if (fd < 0) {
 135                 perror(filename);
 136                 return NULL;
 137         }
 138         if (fstat(fd, &st) < 0) {
 139                 close(fd);
 140                 return NULL;
 141         }
 142         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 143         close(fd);
 144         if (-1 == (int)(long)map)
 145                 return NULL;
 146         *size = st.st_size;
 147         return map;
 148 }
 149
 150 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 151 {
 152         int ret, bytes;
 153         z_stream stream;
 154         char buffer[8192];
 155         char *buf;
 156
 157         /* Get the data stream */
 158         memset(&stream, 0, sizeof(stream));
 159         stream.next_in = map;
 160         stream.avail_in = mapsize;
 161         stream.next_out = buffer;
 162         stream.avail_out = sizeof(buffer);
 163
 164         inflateInit(&stream);
 165         ret = inflate(&stream, 0);
 166         if (sscanf(buffer, "%10s %lu", type, size) != 2)
 167                 return NULL;
 168
 169         bytes = strlen(buffer) + 1;
 170         buf = malloc(*size);
 171         if (!buf)
 172                 return NULL;
 173
 174         memcpy(buf, buffer + bytes, stream.total_out - bytes);
 175         bytes = stream.total_out - bytes;
 176         if (bytes < *size && ret == Z_OK) {
 177                 stream.next_out = buf + bytes;
 178                 stream.avail_out = *size - bytes;
 179                 while (inflate(&stream, Z_FINISH) == Z_OK)
 180                         /* nothing */;
 181         }
 182         inflateEnd(&stream);
 183         return buf;
 184 }
 185
 186 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 187 {
 188         unsigned long mapsize;
 189         void *map, *buf;
 190
 191         map = map_sha1_file(sha1, &mapsize);
 192         if (map) {
 193                 buf = unpack_sha1_file(map, mapsize, type, size);
 194                 munmap(map, mapsize);
 195                 return buf;
 196         }
 197         return NULL;
 198 }
 199
 200 int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 201 {
 202         int size;
 203         char *compressed;
 204         z_stream stream;
 205         unsigned char sha1[20];
 206         SHA_CTX c;
 207
 208         /* Set it up */
 209         memset(&stream, 0, sizeof(stream));
 210         deflateInit(&stream, Z_BEST_COMPRESSION);
 211         size = deflateBound(&stream, len);
 212         compressed = malloc(size);
 213
 214         /* Compress it */
 215         stream.next_in = buf;
 216         stream.avail_in = len;
 217         stream.next_out = compressed;
 218         stream.avail_out = size;
 219         while (deflate(&stream, Z_FINISH) == Z_OK)
 220                 /* nothing */;
 221         deflateEnd(&stream);
 222         size = stream.total_out;
 223
 224         /* Sha1.. */
 225         SHA1_Init(&c);
 226         SHA1_Update(&c, compressed, size);
 227         SHA1_Final(sha1, &c);
 228
 229         if (write_sha1_buffer(sha1, compressed, size) < 0)
 230                 return -1;
 231         if (returnsha1)
 232                 memcpy(returnsha1, sha1, 20);
 233         return 0;
 234 }
 235
 236 static inline int collision_check(char *filename, void *buf, unsigned int size)
 237 {
 238 #ifdef COLLISION_CHECK
 239         void *map;
 240         int fd = open(filename, O_RDONLY);
 241         struct stat st;
 242         int cmp;
 243
 244         /* Unreadable object, or object went away? Strange. */
 245         if (fd < 0)
 246                 return -1;
 247
 248         if (fstat(fd, &st) < 0 || size != st.st_size)
 249                 return -1;
 250
 251         map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 252         close(fd);
 253         if (map == MAP_FAILED)
 254                 return -1;
 255         cmp = memcmp(buf, map, size);
 256         munmap(map, size);
 257         if (cmp)
 258                 return -1;
 259 #endif
 260         return 0;
 261 }
 262
 263 int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
 264 {
 265         char *filename = sha1_file_name(sha1);
 266         int fd;
 267
 268         fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 269         if (fd < 0) {
 270                 if (errno != EEXIST)
 271                         return -1;
 272                 if (collision_check(filename, buf, size))
 273                         return error("SHA1 collision detected!"
 274                                         " This is bad, bad, BAD!\a\n");
 275                 return 0;
 276         }
 277         write(fd, buf, size);
 278         close(fd);
 279         return 0;
 280 }
 281
 282 int cache_match_stat(struct cache_entry *ce, struct stat *st)
 283 {
 284         unsigned int changed = 0;
 285
 286         if (ce->ce_mtime.sec != htonl(st->st_mtime))
 287                 changed |= MTIME_CHANGED;
 288         if (ce->ce_ctime.sec != htonl(st->st_ctime))
 289                 changed |= CTIME_CHANGED;
 290
 291 #ifdef NSEC
 292         /*
 293          * nsec seems unreliable - not all filesystems support it, so
 294          * as long as it is in the inode cache you get right nsec
 295          * but after it gets flushed, you get zero nsec.
 296          */
 297         if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)
 298                 changed |= MTIME_CHANGED;
 299         if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)
 300                 changed |= CTIME_CHANGED;
 301 #endif
 302
 303         if (ce->ce_uid != htonl(st->st_uid) ||
 304             ce->ce_gid != htonl(st->st_gid))
 305                 changed |= OWNER_CHANGED;
 306         /* We consider only the owner x bit to be relevant for "mode changes" */
 307         if (0100 & (ntohs(ce->ce_mode) ^ st->st_mode))
 308                 changed |= MODE_CHANGED;
 309         if (ce->ce_dev != htonl(st->st_dev) ||
 310             ce->ce_ino != htonl(st->st_ino))
 311                 changed |= INODE_CHANGED;
 312         if (ce->ce_size != htonl(st->st_size))
 313                 changed |= DATA_CHANGED;
 314         return changed;
 315 }
 316
 317 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
 318 {
 319         int len1 = flags1 & CE_NAMEMASK;
 320         int len2 = flags2 & CE_NAMEMASK;
 321         int len = len1 < len2 ? len1 : len2;
 322         int cmp;
 323
 324         cmp = memcmp(name1, name2, len);
 325         if (cmp)
 326                 return cmp;
 327         if (len1 < len2)
 328                 return -1;
 329         if (len1 > len2)
 330                 return 1;
 331         if (flags1 < flags2)
 332                 return -1;
 333         if (flags1 > flags2)
 334                 return 1;
 335         return 0;
 336 }
 337
 338 int cache_name_pos(const char *name, int namelen)
 339 {
 340         int first, last;
 341
 342         first = 0;
 343         last = active_nr;
 344         while (last > first) {
 345                 int next = (last + first) >> 1;
 346                 struct cache_entry *ce = active_cache[next];
 347                 int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
 348                 if (!cmp)
 349                         return next;
 350                 if (cmp < 0) {
 351                         last = next;
 352                         continue;
 353                 }
 354                 first = next+1;
 355         }
 356         return -first-1;
 357 }
 358
 359 /* Remove entry, return true if there are more entries to go.. */
 360 static int remove_entry_at(int pos)
 361 {
 362         active_nr--;
 363         if (pos >= active_nr)
 364                 return 0;
 365         memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
 366         return 1;
 367 }
 368
 369 int remove_file_from_cache(char *path)
 370 {
 371         int pos = cache_name_pos(path, strlen(path));
 372         if (pos < 0)
 373                 pos = -pos-1;
 374         while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
 375                 remove_entry_at(pos);
 376         return 0;
 377 }
 378
 379 static int same_name(struct cache_entry *a, struct cache_entry *b)
 380 {
 381         int len = ce_namelen(a);
 382         return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 383 }
 384
 385 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 386 {
 387         int pos;
 388
 389         pos = cache_name_pos(ce->name, htons(ce->ce_flags));
 390
 391         /* existing match? Just replace it */
 392         if (pos >= 0) {
 393                 active_cache[pos] = ce;
 394                 return 0;
 395         }
 396         pos = -pos-1;
 397
 398         /*
 399          * Inserting a merged entry ("stage 0") into the index
 400          * will always replace all non-merged entries..
 401          */
 402         if (pos < active_nr && ce_stage(ce) == 0) {
 403                 while (same_name(active_cache[pos], ce)) {
 404                         ok_to_add = 1;
 405                         active_nr--;
 406                         if (!remove_entry_at(pos))
 407                                 break;
 408                 }
 409         }
 410
 411         if (!ok_to_add)
 412                 return -1;
 413
 414         /* Make sure the array is big enough .. */
 415         if (active_nr == active_alloc) {
 416                 active_alloc = alloc_nr(active_alloc);
 417                 active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 418         }
 419
 420         /* Add it in.. */
 421         active_nr++;
 422         if (active_nr > pos)
 423                 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 424         active_cache[pos] = ce;
 425         return 0;
 426 }
 427
 428 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 429 {
 430         SHA_CTX c;
 431         unsigned char sha1[20];
 432
 433         if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 434                 return error("bad signature");
 435         if (hdr->hdr_version != htonl(1))
 436                 return error("bad version");
 437         SHA1_Init(&c);
 438         SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
 439         SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
 440         SHA1_Final(sha1, &c);
 441         if (memcmp(sha1, hdr->sha1, 20))
 442                 return error("bad header sha1");
 443         return 0;
 444 }
 445
 446 int read_cache(void)
 447 {
 448         int fd, i;
 449         struct stat st;
 450         unsigned long size, offset;
 451         void *map;
 452         struct cache_header *hdr;
 453
 454         errno = EBUSY;
 455         if (active_cache)
 456                 return error("more than one cachefile");
 457         errno = ENOENT;
 458         sha1_file_directory = getenv(DB_ENVIRONMENT);
 459         if (!sha1_file_directory)
 460                 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
 461         if (access(sha1_file_directory, X_OK) < 0)
 462                 return error("no access to SHA1 file directory");
 463         fd = open(".git/index", O_RDONLY);
 464         if (fd < 0)
 465                 return (errno == ENOENT) ? 0 : error("open failed");
 466
 467         size = 0; // avoid gcc warning
 468         map = (void *)-1;
 469         if (!fstat(fd, &st)) {
 470                 size = st.st_size;
 471                 errno = EINVAL;
 472                 if (size >= sizeof(struct cache_header))
 473                         map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 474         }
 475         close(fd);
 476         if (-1 == (int)(long)map)
 477                 return error("mmap failed");
 478
 479         hdr = map;
 480         if (verify_hdr(hdr, size) < 0)
 481                 goto unmap;
 482
 483         active_nr = ntohl(hdr->hdr_entries);
 484         active_alloc = alloc_nr(active_nr);
 485         active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 486
 487         offset = sizeof(*hdr);
 488         for (i = 0; i < active_nr; i++) {
 489                 struct cache_entry *ce = map + offset;
 490                 offset = offset + ce_size(ce);
 491                 active_cache[i] = ce;
 492         }
 493         return active_nr;
 494
 495 unmap:
 496         munmap(map, size);
 497         errno = EINVAL;
 498         return error("verify header failed");
 499 }
 500
 501 int write_cache(int newfd, struct cache_entry **cache, int entries)
 502 {
 503         SHA_CTX c;
 504         struct cache_header hdr;
 505         int i;
 506
 507         hdr.hdr_signature = htonl(CACHE_SIGNATURE);
 508         hdr.hdr_version = htonl(1);
 509         hdr.hdr_entries = htonl(entries);
 510
 511         SHA1_Init(&c);
 512         SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
 513         for (i = 0; i < entries; i++) {
 514                 struct cache_entry *ce = cache[i];
 515                 int size = ce_size(ce);
 516                 SHA1_Update(&c, ce, size);
 517         }
 518         SHA1_Final(hdr.sha1, &c);
 519
 520         if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
 521                 return -1;
 522
 523         for (i = 0; i < entries; i++) {
 524                 struct cache_entry *ce = cache[i];
 525                 int size = ce_size(ce);
 526                 if (write(newfd, ce, size) != size)
 527                         return -1;
 528         }
 529         return 0;
 530 }