sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include <sys/types.h>
  10 #include <dirent.h>
  11 #include "cache.h"
  12 #include "delta.h"
  13
  14 #ifndef O_NOATIME
  15 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  16 #define O_NOATIME 01000000
  17 #else
  18 #define O_NOATIME 0
  19 #endif
  20 #endif
  21
  22 static unsigned int sha1_file_open_flag = O_NOATIME;
  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 static int get_sha1_file(const char *path, unsigned char *result)
  49 {
  50         char buffer[60];
  51         int fd = open(path, O_RDONLY);
  52         int len;
  53
  54         if (fd < 0)
  55                 return -1;
  56         len = read(fd, buffer, sizeof(buffer));
  57         close(fd);
  58         if (len < 40)
  59                 return -1;
  60         return get_sha1_hex(buffer, result);
  61 }
  62
  63 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
  64 static void setup_git_env(void)
  65 {
  66         git_dir = gitenv(GIT_DIR_ENVIRONMENT);
  67         if (!git_dir)
  68                 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  69         git_object_dir = gitenv(DB_ENVIRONMENT);
  70         if (!git_object_dir) {
  71                 git_object_dir = xmalloc(strlen(git_dir) + 9);
  72                 sprintf(git_object_dir, "%s/objects", git_dir);
  73         }
  74         git_refs_dir = xmalloc(strlen(git_dir) + 6);
  75         sprintf(git_refs_dir, "%s/refs", git_dir);
  76         git_index_file = gitenv(INDEX_ENVIRONMENT);
  77         if (!git_index_file) {
  78                 git_index_file = xmalloc(strlen(git_dir) + 7);
  79                 sprintf(git_index_file, "%s/index", git_dir);
  80         }
  81 }
  82
  83 char *get_object_directory(void)
  84 {
  85         if (!git_object_dir)
  86                 setup_git_env();
  87         return git_object_dir;
  88 }
  89
  90 char *get_refs_directory(void)
  91 {
  92         if (!git_refs_dir)
  93                 setup_git_env();
  94         return git_refs_dir;
  95 }
  96
  97 char *get_index_file(void)
  98 {
  99         if (!git_index_file)
 100                 setup_git_env();
 101         return git_index_file;
 102 }
 103
 104 int get_sha1(const char *str, unsigned char *sha1)
 105 {
 106         static char pathname[PATH_MAX];
 107         static const char *prefix[] = {
 108                 "",
 109                 "refs",
 110                 "refs/tags",
 111                 "refs/heads",
 112                 "refs/snap",
 113                 NULL
 114         };
 115         const char **p;
 116
 117         if (!get_sha1_hex(str, sha1))
 118                 return 0;
 119
 120         if (!git_dir)
 121                 setup_git_env();
 122         for (p = prefix; *p; p++) {
 123                 snprintf(pathname, sizeof(pathname), "%s/%s/%s",
 124                          git_dir, *p, str);
 125                 if (!get_sha1_file(pathname, sha1))
 126                         return 0;
 127         }
 128
 129         return -1;
 130 }
 131
 132 char * sha1_to_hex(const unsigned char *sha1)
 133 {
 134         static char buffer[50];
 135         static const char hex[] = "0123456789abcdef";
 136         char *buf = buffer;
 137         int i;
 138
 139         for (i = 0; i < 20; i++) {
 140                 unsigned int val = *sha1++;
 141                 *buf++ = hex[val >> 4];
 142                 *buf++ = hex[val & 0xf];
 143         }
 144         return buffer;
 145 }
 146
 147 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 148 {
 149         int i;
 150         for (i = 0; i < 20; i++) {
 151                 static char hex[] = "0123456789abcdef";
 152                 unsigned int val = sha1[i];
 153                 char *pos = pathbuf + i*2 + (i > 0);
 154                 *pos++ = hex[val >> 4];
 155                 *pos = hex[val & 0xf];
 156         }
 157 }
 158
 159 /*
 160  * NOTE! This returns a statically allocated buffer, so you have to be
 161  * careful about using it. Do a "strdup()" if you need to save the
 162  * filename.
 163  *
 164  * Also note that this returns the location for creating.  Reading
 165  * SHA1 file can happen from any alternate directory listed in the
 166  * DB_ENVIRONMENT environment variable if it is not found in
 167  * the primary object database.
 168  */
 169 char *sha1_file_name(const unsigned char *sha1)
 170 {
 171         static char *name, *base;
 172
 173         if (!base) {
 174                 const char *sha1_file_directory = get_object_directory();
 175                 int len = strlen(sha1_file_directory);
 176                 base = xmalloc(len + 60);
 177                 memcpy(base, sha1_file_directory, len);
 178                 memset(base+len, 0, 60);
 179                 base[len] = '/';
 180                 base[len+3] = '/';
 181                 name = base + len + 1;
 182         }
 183         fill_sha1_path(name, sha1);
 184         return base;
 185 }
 186
 187 static struct alternate_object_database {
 188         char *base;
 189         char *name;
 190 } *alt_odb;
 191
 192 /*
 193  * Prepare alternate object database registry.
 194  * alt_odb points at an array of struct alternate_object_database.
 195  * This array is terminated with an element that has both its base
 196  * and name set to NULL.  alt_odb[n] comes from n'th non-empty
 197  * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
 198  * variable, and its base points at a statically allocated buffer
 199  * that contains "/the/directory/corresponding/to/.git/objects/...",
 200  * while its name points just after the slash at the end of
 201  * ".git/objects/" in the example above, and has enough space to hold
 202  * 40-byte hex SHA1, an extra slash for the first level indirection,
 203  * and the terminating NUL.
 204  * This function allocates the alt_odb array and all the strings
 205  * pointed by base fields of the array elements with one xmalloc();
 206  * the string pool immediately follows the array.
 207  */
 208 static void prepare_alt_odb(void)
 209 {
 210         int pass, totlen, i;
 211         const char *cp, *last;
 212         char *op = NULL;
 213         const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 214
 215         /* The first pass counts how large an area to allocate to
 216          * hold the entire alt_odb structure, including array of
 217          * structs and path buffers for them.  The second pass fills
 218          * the structure and prepares the path buffers for use by
 219          * fill_sha1_path().
 220          */
 221         for (totlen = pass = 0; pass < 2; pass++) {
 222                 last = alt;
 223                 i = 0;
 224                 do {
 225                         cp = strchr(last, ':') ? : last + strlen(last);
 226                         if (last != cp) {
 227                                 /* 43 = 40-byte + 2 '/' + terminating NUL */
 228                                 int pfxlen = cp - last;
 229                                 int entlen = pfxlen + 43;
 230                                 if (pass == 0)
 231                                         totlen += entlen;
 232                                 else {
 233                                         alt_odb[i].base = op;
 234                                         alt_odb[i].name = op + pfxlen + 1;
 235                                         memcpy(op, last, pfxlen);
 236                                         op[pfxlen] = op[pfxlen + 3] = '/';
 237                                         op[entlen-1] = 0;
 238                                         op += entlen;
 239                                 }
 240                                 i++;
 241                         }
 242                         while (*cp && *cp == ':')
 243                                 cp++;
 244                         last = cp;
 245                 } while (*cp);
 246                 if (pass)
 247                         break;
 248                 alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
 249                 alt_odb[i].base = alt_odb[i].name = NULL;
 250                 op = (char*)(&alt_odb[i+1]);
 251         }
 252 }
 253
 254 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 255 {
 256         int i;
 257         char *name = sha1_file_name(sha1);
 258
 259         if (!stat(name, st))
 260                 return name;
 261         if (!alt_odb)
 262                 prepare_alt_odb();
 263         for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
 264                 fill_sha1_path(name, sha1);
 265                 if (!stat(alt_odb[i].base, st))
 266                         return alt_odb[i].base;
 267         }
 268         return NULL;
 269 }
 270
 271 #define PACK_MAX_SZ (1<<26)
 272 static int pack_used_ctr;
 273 static unsigned long pack_mapped;
 274 static struct packed_git {
 275         struct packed_git *next;
 276         unsigned long index_size;
 277         unsigned long pack_size;
 278         unsigned int *index_base;
 279         void *pack_base;
 280         unsigned int pack_last_used;
 281         char pack_name[0]; /* something like ".git/objects/pack/xxxxx.pack" */
 282 } *packed_git;
 283
 284 struct pack_entry {
 285         unsigned int offset;
 286         unsigned char sha1[20];
 287         struct packed_git *p;
 288 };
 289
 290 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 291                                 void **idx_map_)
 292 {
 293         void *idx_map;
 294         unsigned int *index;
 295         unsigned long idx_size;
 296         int nr, i;
 297         int fd = open(path, O_RDONLY);
 298         struct stat st;
 299         if (fd < 0)
 300                 return -1;
 301         if (fstat(fd, &st)) {
 302                 close(fd);
 303                 return -1;
 304         }
 305         idx_size = st.st_size;
 306         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 307         close(fd);
 308         if (idx_map == MAP_FAILED)
 309                 return -1;
 310
 311         index = idx_map;
 312
 313         /* check index map */
 314         if (idx_size < 4*256 + 20)
 315                 return error("index file too small");
 316         nr = 0;
 317         for (i = 0; i < 256; i++) {
 318                 unsigned int n = ntohl(index[i]);
 319                 if (n < nr)
 320                         return error("non-monotonic index");
 321                 nr = n;
 322         }
 323
 324         /*
 325          * Total size:
 326          *  - 256 index entries 4 bytes each
 327          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 328          *  - 20-byte SHA1 of the packfile
 329          *  - 20-byte SHA1 file checksum
 330          */
 331         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 332                 return error("wrong index file size");
 333
 334         *idx_map_ = idx_map;
 335         *idx_size_ = idx_size;
 336         return 0;
 337 }
 338
 339 static void unuse_one_packed_git(void)
 340 {
 341         /* NOTYET */
 342 }
 343
 344 static int use_packed_git(struct packed_git *p)
 345 {
 346         if (!p->pack_base) {
 347                 int fd;
 348                 struct stat st;
 349                 void *map;
 350
 351                 pack_mapped += p->pack_size;
 352                 while (PACK_MAX_SZ < pack_mapped)
 353                         unuse_one_packed_git();
 354                 fd = open(p->pack_name, O_RDONLY);
 355                 if (fd < 0)
 356                         return -1;
 357                 if (fstat(fd, &st)) {
 358                         close(fd);
 359                         return -1;
 360                 }
 361                 if (st.st_size != p->pack_size)
 362                         return -1;
 363                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 364                 close(fd);
 365                 if (map == MAP_FAILED)
 366                         return -1;
 367                 p->pack_base = map;
 368         }
 369         p->pack_last_used = pack_used_ctr++;
 370         return 0;
 371 }
 372
 373 static struct packed_git *add_packed_git(char *path, int path_len)
 374 {
 375         struct stat st;
 376         struct packed_git *p;
 377         unsigned long idx_size;
 378         void *idx_map;
 379
 380         if (check_packed_git_idx(path, &idx_size, &idx_map))
 381                 return NULL;
 382
 383         /* do we have a corresponding .pack file? */
 384         strcpy(path + path_len - 4, ".pack");
 385         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 386                 munmap(idx_map, idx_size);
 387                 return NULL;
 388         }
 389         /* ok, it looks sane as far as we can check without
 390          * actually mapping the pack file.
 391          */
 392         p = xmalloc(sizeof(*p) + path_len + 2);
 393         strcpy(p->pack_name, path);
 394         p->index_size = idx_size;
 395         p->pack_size = st.st_size;
 396         p->index_base = idx_map;
 397         p->next = NULL;
 398         p->pack_last_used = 0;
 399         return p;
 400 }
 401
 402 static void prepare_packed_git_one(char *objdir)
 403 {
 404         char path[PATH_MAX];
 405         int len;
 406         DIR *dir;
 407         struct dirent *de;
 408
 409         sprintf(path, "%s/pack", objdir);
 410         len = strlen(path);
 411         dir = opendir(path);
 412         if (!dir)
 413                 return;
 414         path[len++] = '/';
 415         while ((de = readdir(dir)) != NULL) {
 416                 int namelen = strlen(de->d_name);
 417                 struct packed_git *p;
 418
 419                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 420                         continue;
 421
 422                 /* we have .idx.  Is it a file we can map? */
 423                 strcpy(path + len, de->d_name);
 424                 p = add_packed_git(path, len + namelen);
 425                 if (!p)
 426                         continue;
 427                 p->next = packed_git;
 428                 packed_git = p;
 429         }
 430 }
 431
 432 static void prepare_packed_git(void)
 433 {
 434         int i;
 435         static int run_once = 0;
 436
 437         if (run_once++)
 438                 return;
 439
 440         prepare_packed_git_one(get_object_directory());
 441         if (!alt_odb)
 442                 prepare_alt_odb();
 443         for (i = 0; alt_odb[i].base != NULL; i++) {
 444                 alt_odb[i].name[0] = 0;
 445                 prepare_packed_git_one(alt_odb[i].base);
 446         }
 447 }
 448
 449 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 450 {
 451         char header[100];
 452         unsigned char real_sha1[20];
 453         SHA_CTX c;
 454
 455         SHA1_Init(&c);
 456         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 457         SHA1_Update(&c, map, size);
 458         SHA1_Final(real_sha1, &c);
 459         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 460 }
 461
 462 static void *map_sha1_file_internal(const unsigned char *sha1,
 463                                     unsigned long *size,
 464                                     int say_error)
 465 {
 466         struct stat st;
 467         void *map;
 468         int fd;
 469         char *filename = find_sha1_file(sha1, &st);
 470
 471         if (!filename) {
 472                 if (say_error)
 473                         error("cannot map sha1 file %s", sha1_to_hex(sha1));
 474                 return NULL;
 475         }
 476
 477         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 478         if (fd < 0) {
 479                 /* See if it works without O_NOATIME */
 480                 switch (sha1_file_open_flag) {
 481                 default:
 482                         fd = open(filename, O_RDONLY);
 483                         if (fd >= 0)
 484                                 break;
 485                 /* Fallthrough */
 486                 case 0:
 487                         if (say_error)
 488                                 perror(filename);
 489                         return NULL;
 490                 }
 491
 492                 /* If it failed once, it will probably fail again.
 493                  * Stop using O_NOATIME
 494                  */
 495                 sha1_file_open_flag = 0;
 496         }
 497         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 498         close(fd);
 499         if (-1 == (int)(long)map)
 500                 return NULL;
 501         *size = st.st_size;
 502         return map;
 503 }
 504
 505 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 506 {
 507         return map_sha1_file_internal(sha1, size, 1);
 508 }
 509
 510 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 511 {
 512         /* Get the data stream */
 513         memset(stream, 0, sizeof(*stream));
 514         stream->next_in = map;
 515         stream->avail_in = mapsize;
 516         stream->next_out = buffer;
 517         stream->avail_out = size;
 518
 519         inflateInit(stream);
 520         return inflate(stream, 0);
 521 }
 522
 523 void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 524 {
 525         int bytes = strlen(buffer) + 1;
 526         unsigned char *buf = xmalloc(1+size);
 527
 528         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 529         bytes = stream->total_out - bytes;
 530         if (bytes < size) {
 531                 stream->next_out = buf + bytes;
 532                 stream->avail_out = size - bytes;
 533                 while (inflate(stream, Z_FINISH) == Z_OK)
 534                         /* nothing */;
 535         }
 536         buf[size] = 0;
 537         inflateEnd(stream);
 538         return buf;
 539 }
 540
 541 /*
 542  * We used to just use "sscanf()", but that's actually way
 543  * too permissive for what we want to check. So do an anal
 544  * object header parse by hand.
 545  */
 546 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 547 {
 548         int i;
 549         unsigned long size;
 550
 551         /*
 552          * The type can be at most ten bytes (including the
 553          * terminating '\0' that we add), and is followed by
 554          * a space.
 555          */
 556         i = 10;
 557         for (;;) {
 558                 char c = *hdr++;
 559                 if (c == ' ')
 560                         break;
 561                 if (!--i)
 562                         return -1;
 563                 *type++ = c;
 564         }
 565         *type = 0;
 566
 567         /*
 568          * The length must follow immediately, and be in canonical
 569          * decimal format (ie "010" is not valid).
 570          */
 571         size = *hdr++ - '0';
 572         if (size > 9)
 573                 return -1;
 574         if (size) {
 575                 for (;;) {
 576                         unsigned long c = *hdr - '0';
 577                         if (c > 9)
 578                                 break;
 579                         hdr++;
 580                         size = size * 10 + c;
 581                 }
 582         }
 583         *sizep = size;
 584
 585         /*
 586          * The length must be followed by a zero byte
 587          */
 588         return *hdr ? -1 : 0;
 589 }
 590
 591 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 592 {
 593         int ret;
 594         z_stream stream;
 595         char hdr[8192];
 596
 597         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 598         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 599                 return NULL;
 600
 601         return unpack_sha1_rest(&stream, hdr, *size);
 602 }
 603
 604 /* Returns 0 on fast-path success, returns 1 on deltified
 605  * and need to unpack to see info.
 606  */
 607 static int packed_object_info(struct pack_entry *entry,
 608                               char *type, unsigned long *sizep)
 609 {
 610         struct packed_git *p = entry->p;
 611         unsigned long offset, size, left;
 612         unsigned char *pack;
 613
 614         offset = entry->offset;
 615         if (p->pack_size - 5 < offset)
 616                 die("object offset outside of pack file");
 617         pack = p->pack_base + offset;
 618         size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
 619         left = p->pack_size - offset - 5;
 620         switch (*pack) {
 621         case 'D':
 622                 return 1;
 623                 break;
 624         case 'C':
 625                 strcpy(type, "commit");
 626                 break;
 627         case 'T':
 628                 strcpy(type, "tree");
 629                 break;
 630         case 'B':
 631                 strcpy(type, "blob");
 632                 break;
 633         default:
 634                 die("corrupted pack file");
 635         }
 636         *sizep = size;
 637         return 0;
 638 }
 639
 640 /* forward declaration for a mutually recursive function */
 641 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 642
 643 static void *unpack_delta_entry(unsigned char *base_sha1,
 644                                 unsigned long delta_size,
 645                                 unsigned long left,
 646                                 char *type,
 647                                 unsigned long *sizep)
 648 {
 649         void *data, *delta_data, *result, *base;
 650         unsigned long data_size, result_size, base_size;
 651         z_stream stream;
 652         int st;
 653
 654         if (left < 20)
 655                 die("truncated pack file");
 656         data = base_sha1 + 20;
 657         data_size = left - 20;
 658         delta_data = xmalloc(delta_size);
 659
 660         memset(&stream, 0, sizeof(stream));
 661
 662         stream.next_in = data;
 663         stream.avail_in = data_size;
 664         stream.next_out = delta_data;
 665         stream.avail_out = delta_size;
 666
 667         inflateInit(&stream);
 668         st = inflate(&stream, Z_FINISH);
 669         inflateEnd(&stream);
 670         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 671                 die("delta data unpack failed");
 672
 673         /* This may recursively unpack the base, which is what we want */
 674         base = read_sha1_file(base_sha1, type, &base_size);
 675         if (!base)
 676                 die("failed to read delta-pack base object %s",
 677                     sha1_to_hex(base_sha1));
 678         result = patch_delta(base, base_size,
 679                              delta_data, delta_size,
 680                              &result_size);
 681         if (!result)
 682                 die("failed to apply delta");
 683         free(delta_data);
 684         free(base);
 685         *sizep = result_size;
 686         return result;
 687 }
 688
 689 static void *unpack_non_delta_entry(unsigned char *data,
 690                                     unsigned long size,
 691                                     unsigned long left)
 692 {
 693         int st;
 694         z_stream stream;
 695         char *buffer;
 696
 697         buffer = xmalloc(size + 1);
 698         buffer[size] = 0;
 699         memset(&stream, 0, sizeof(stream));
 700         stream.next_in = data;
 701         stream.avail_in = left;
 702         stream.next_out = buffer;
 703         stream.avail_out = size;
 704
 705         inflateInit(&stream);
 706         st = inflate(&stream, Z_FINISH);
 707         inflateEnd(&stream);
 708         if ((st != Z_STREAM_END) || stream.total_out != size) {
 709                 free(buffer);
 710                 return NULL;
 711         }
 712
 713         return buffer;
 714 }
 715
 716 static void *unpack_entry(struct pack_entry *entry,
 717                           char *type, unsigned long *sizep)
 718 {
 719         struct packed_git *p = entry->p;
 720         unsigned long offset, size, left;
 721         unsigned char *pack;
 722
 723         offset = entry->offset;
 724         if (p->pack_size - 5 < offset)
 725                 die("object offset outside of pack file");
 726
 727         if (use_packed_git(p))
 728                 die("cannot map packed file");
 729
 730         pack = p->pack_base + offset;
 731         size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
 732         left = p->pack_size - offset - 5;
 733         switch (*pack) {
 734         case 'D':
 735                 return unpack_delta_entry(pack+5, size, left, type, sizep);
 736         case 'C':
 737                 strcpy(type, "commit");
 738                 break;
 739         case 'T':
 740                 strcpy(type, "tree");
 741                 break;
 742         case 'B':
 743                 strcpy(type, "blob");
 744                 break;
 745         default:
 746                 die("corrupted pack file");
 747         }
 748         *sizep = size;
 749         return unpack_non_delta_entry(pack+5, size, left);
 750 }
 751
 752 static int find_pack_entry_1(const unsigned char *sha1,
 753                              struct pack_entry *e, struct packed_git *p)
 754 {
 755         int *level1_ofs = p->index_base;
 756         int hi = ntohl(level1_ofs[*sha1]);
 757         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
 758         void *index = p->index_base + 256;
 759
 760         do {
 761                 int mi = (lo + hi) / 2;
 762                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
 763                 if (!cmp) {
 764                         e->offset = ntohl(*((int*)(index + 24 * mi)));
 765                         memcpy(e->sha1, sha1, 20);
 766                         e->p = p;
 767                         return 1;
 768                 }
 769                 if (cmp > 0)
 770                         hi = mi;
 771                 else
 772                         lo = mi+1;
 773         } while (lo < hi);
 774         return 0;
 775 }
 776
 777 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 778 {
 779         struct packed_git *p;
 780         prepare_packed_git();
 781
 782         for (p = packed_git; p; p = p->next) {
 783                 if (find_pack_entry_1(sha1, e, p))
 784                         return 1;
 785         }
 786         return 0;
 787 }
 788
 789 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
 790 {
 791         int status;
 792         unsigned long mapsize, size;
 793         void *map;
 794         z_stream stream;
 795         char hdr[128];
 796
 797         map = map_sha1_file_internal(sha1, &mapsize, 0);
 798         if (!map) {
 799                 struct pack_entry e;
 800
 801                 if (!find_pack_entry(sha1, &e))
 802                         return error("unable to find %s", sha1_to_hex(sha1));
 803                 if (!packed_object_info(&e, type, sizep))
 804                         return 0;
 805                 /* sheesh */
 806                 map = unpack_entry(&e, type, sizep);
 807                 free(map);
 808                 return (map == NULL) ? 0 : -1;
 809         }
 810         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 811                 status = error("unable to unpack %s header",
 812                                sha1_to_hex(sha1));
 813         if (parse_sha1_header(hdr, type, &size) < 0)
 814                 status = error("unable to parse %s header", sha1_to_hex(sha1));
 815         else {
 816                 status = 0;
 817                 *sizep = size;
 818         }
 819         inflateEnd(&stream);
 820         munmap(map, mapsize);
 821         return status;
 822 }
 823
 824 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
 825 {
 826         struct pack_entry e;
 827
 828         if (!find_pack_entry(sha1, &e)) {
 829                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
 830                 return NULL;
 831         }
 832         return unpack_entry(&e, type, size);
 833 }
 834
 835 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 836 {
 837         unsigned long mapsize;
 838         void *map, *buf;
 839
 840         map = map_sha1_file_internal(sha1, &mapsize, 0);
 841         if (map) {
 842                 buf = unpack_sha1_file(map, mapsize, type, size);
 843                 munmap(map, mapsize);
 844                 return buf;
 845         }
 846         return read_packed_sha1(sha1, type, size);
 847 }
 848
 849 void *read_object_with_reference(const unsigned char *sha1,
 850                                  const char *required_type,
 851                                  unsigned long *size,
 852                                  unsigned char *actual_sha1_return)
 853 {
 854         char type[20];
 855         void *buffer;
 856         unsigned long isize;
 857         unsigned char actual_sha1[20];
 858
 859         memcpy(actual_sha1, sha1, 20);
 860         while (1) {
 861                 int ref_length = -1;
 862                 const char *ref_type = NULL;
 863
 864                 buffer = read_sha1_file(actual_sha1, type, &isize);
 865                 if (!buffer)
 866                         return NULL;
 867                 if (!strcmp(type, required_type)) {
 868                         *size = isize;
 869                         if (actual_sha1_return)
 870                                 memcpy(actual_sha1_return, actual_sha1, 20);
 871                         return buffer;
 872                 }
 873                 /* Handle references */
 874                 else if (!strcmp(type, "commit"))
 875                         ref_type = "tree ";
 876                 else if (!strcmp(type, "tag"))
 877                         ref_type = "object ";
 878                 else {
 879                         free(buffer);
 880                         return NULL;
 881                 }
 882                 ref_length = strlen(ref_type);
 883
 884                 if (memcmp(buffer, ref_type, ref_length) ||
 885                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
 886                         free(buffer);
 887                         return NULL;
 888                 }
 889                 /* Now we have the ID of the referred-to object in
 890                  * actual_sha1.  Check again. */
 891         }
 892 }
 893
 894 static char *write_sha1_file_prepare(void *buf,
 895                                      unsigned long len,
 896                                      const char *type,
 897                                      unsigned char *sha1,
 898                                      unsigned char *hdr,
 899                                      int *hdrlen)
 900 {
 901         SHA_CTX c;
 902
 903         /* Generate the header */
 904         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
 905
 906         /* Sha1.. */
 907         SHA1_Init(&c);
 908         SHA1_Update(&c, hdr, *hdrlen);
 909         SHA1_Update(&c, buf, len);
 910         SHA1_Final(sha1, &c);
 911
 912         return sha1_file_name(sha1);
 913 }
 914
 915 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 916 {
 917         int size;
 918         unsigned char *compressed;
 919         z_stream stream;
 920         unsigned char sha1[20];
 921         char *filename;
 922         static char tmpfile[PATH_MAX];
 923         unsigned char hdr[50];
 924         int fd, hdrlen, ret;
 925
 926         /* Normally if we have it in the pack then we do not bother writing
 927          * it out into .git/objects/??/?{38} file.
 928          */
 929         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
 930         if (returnsha1)
 931                 memcpy(returnsha1, sha1, 20);
 932         if (has_sha1_file(sha1))
 933                 return 0;
 934         fd = open(filename, O_RDONLY);
 935         if (fd >= 0) {
 936                 /*
 937                  * FIXME!!! We might do collision checking here, but we'd
 938                  * need to uncompress the old file and check it. Later.
 939                  */
 940                 close(fd);
 941                 return 0;
 942         }
 943
 944         if (errno != ENOENT) {
 945                 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
 946                 return -1;
 947         }
 948
 949         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
 950
 951         fd = mkstemp(tmpfile);
 952         if (fd < 0) {
 953                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
 954                 return -1;
 955         }
 956
 957         /* Set it up */
 958         memset(&stream, 0, sizeof(stream));
 959         deflateInit(&stream, Z_BEST_COMPRESSION);
 960         size = deflateBound(&stream, len+hdrlen);
 961         compressed = xmalloc(size);
 962
 963         /* Compress it */
 964         stream.next_out = compressed;
 965         stream.avail_out = size;
 966
 967         /* First header.. */
 968         stream.next_in = hdr;
 969         stream.avail_in = hdrlen;
 970         while (deflate(&stream, 0) == Z_OK)
 971                 /* nothing */;
 972
 973         /* Then the data itself.. */
 974         stream.next_in = buf;
 975         stream.avail_in = len;
 976         while (deflate(&stream, Z_FINISH) == Z_OK)
 977                 /* nothing */;
 978         deflateEnd(&stream);
 979         size = stream.total_out;
 980
 981         if (write(fd, compressed, size) != size)
 982                 die("unable to write file");
 983         fchmod(fd, 0444);
 984         close(fd);
 985         free(compressed);
 986
 987         ret = link(tmpfile, filename);
 988         if (ret < 0) {
 989                 ret = errno;
 990
 991                 /*
 992                  * Coda hack - coda doesn't like cross-directory links,
 993                  * so we fall back to a rename, which will mean that it
 994                  * won't be able to check collisions, but that's not a
 995                  * big deal.
 996                  *
 997                  * When this succeeds, we just return 0. We have nothing
 998                  * left to unlink.
 999                  */
1000                 if (ret == EXDEV && !rename(tmpfile, filename))
1001                         return 0;
1002         }
1003         unlink(tmpfile);
1004         if (ret) {
1005                 if (ret != EEXIST) {
1006                         fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1007                         return -1;
1008                 }
1009                 /* FIXME!!! Collision check here ? */
1010         }
1011
1012         return 0;
1013 }
1014
1015 int write_sha1_from_fd(const unsigned char *sha1, int fd)
1016 {
1017         char *filename = sha1_file_name(sha1);
1018
1019         int local;
1020         z_stream stream;
1021         unsigned char real_sha1[20];
1022         unsigned char buf[4096];
1023         unsigned char discard[4096];
1024         int ret;
1025         SHA_CTX c;
1026
1027         local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1028
1029         if (local < 0)
1030                 return error("Couldn't open %s\n", filename);
1031
1032         memset(&stream, 0, sizeof(stream));
1033
1034         inflateInit(&stream);
1035
1036         SHA1_Init(&c);
1037
1038         do {
1039                 ssize_t size;
1040                 size = read(fd, buf, 4096);
1041                 if (size <= 0) {
1042                         close(local);
1043                         unlink(filename);
1044                         if (!size)
1045                                 return error("Connection closed?");
1046                         perror("Reading from connection");
1047                         return -1;
1048                 }
1049                 write(local, buf, size);
1050                 stream.avail_in = size;
1051                 stream.next_in = buf;
1052                 do {
1053                         stream.next_out = discard;
1054                         stream.avail_out = sizeof(discard);
1055                         ret = inflate(&stream, Z_SYNC_FLUSH);
1056                         SHA1_Update(&c, discard, sizeof(discard) -
1057                                     stream.avail_out);
1058                 } while (stream.avail_in && ret == Z_OK);
1059
1060         } while (ret == Z_OK);
1061         inflateEnd(&stream);
1062
1063         close(local);
1064         SHA1_Final(real_sha1, &c);
1065         if (ret != Z_STREAM_END) {
1066                 unlink(filename);
1067                 return error("File %s corrupted", sha1_to_hex(sha1));
1068         }
1069         if (memcmp(sha1, real_sha1, 20)) {
1070                 unlink(filename);
1071                 return error("File %s has bad hash\n", sha1_to_hex(sha1));
1072         }
1073
1074         return 0;
1075 }
1076
1077 int has_sha1_file(const unsigned char *sha1)
1078 {
1079         struct stat st;
1080         struct pack_entry e;
1081
1082         if (find_sha1_file(sha1, &st))
1083                 return 1;
1084         return find_pack_entry(sha1, &e);
1085 }
1086
1087 int index_fd(unsigned char *sha1, int fd, struct stat *st)
1088 {
1089         unsigned long size = st->st_size;
1090         void *buf;
1091         int ret;
1092
1093         buf = "";
1094         if (size)
1095                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1096         close(fd);
1097         if ((int)(long)buf == -1)
1098                 return -1;
1099
1100         ret = write_sha1_file(buf, size, "blob", sha1);
1101         if (size)
1102                 munmap(buf, size);
1103         return ret;
1104 }