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 #include "pack.h"
  14
  15 #ifndef O_NOATIME
  16 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  17 #define O_NOATIME 01000000
  18 #else
  19 #define O_NOATIME 0
  20 #endif
  21 #endif
  22
  23 static unsigned int sha1_file_open_flag = O_NOATIME;
  24
  25 static unsigned hexval(char c)
  26 {
  27         if (c >= '0' && c <= '9')
  28                 return c - '0';
  29         if (c >= 'a' && c <= 'f')
  30                 return c - 'a' + 10;
  31         if (c >= 'A' && c <= 'F')
  32                 return c - 'A' + 10;
  33         return ~0;
  34 }
  35
  36 int get_sha1_hex(const char *hex, unsigned char *sha1)
  37 {
  38         int i;
  39         for (i = 0; i < 20; i++) {
  40                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  41                 if (val & ~0xff)
  42                         return -1;
  43                 *sha1++ = val;
  44                 hex += 2;
  45         }
  46         return 0;
  47 }
  48
  49 static int get_sha1_file(const char *path, unsigned char *result)
  50 {
  51         char buffer[60];
  52         int fd = open(path, O_RDONLY);
  53         int len;
  54
  55         if (fd < 0)
  56                 return -1;
  57         len = read(fd, buffer, sizeof(buffer));
  58         close(fd);
  59         if (len < 40)
  60                 return -1;
  61         return get_sha1_hex(buffer, result);
  62 }
  63
  64 static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
  65 static void setup_git_env(void)
  66 {
  67         git_dir = gitenv(GIT_DIR_ENVIRONMENT);
  68         if (!git_dir)
  69                 git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
  70         git_object_dir = gitenv(DB_ENVIRONMENT);
  71         if (!git_object_dir) {
  72                 git_object_dir = xmalloc(strlen(git_dir) + 9);
  73                 sprintf(git_object_dir, "%s/objects", git_dir);
  74         }
  75         git_refs_dir = xmalloc(strlen(git_dir) + 6);
  76         sprintf(git_refs_dir, "%s/refs", git_dir);
  77         git_index_file = gitenv(INDEX_ENVIRONMENT);
  78         if (!git_index_file) {
  79                 git_index_file = xmalloc(strlen(git_dir) + 7);
  80                 sprintf(git_index_file, "%s/index", git_dir);
  81         }
  82 }
  83
  84 char *get_object_directory(void)
  85 {
  86         if (!git_object_dir)
  87                 setup_git_env();
  88         return git_object_dir;
  89 }
  90
  91 char *get_refs_directory(void)
  92 {
  93         if (!git_refs_dir)
  94                 setup_git_env();
  95         return git_refs_dir;
  96 }
  97
  98 char *get_index_file(void)
  99 {
 100         if (!git_index_file)
 101                 setup_git_env();
 102         return git_index_file;
 103 }
 104
 105 int get_sha1(const char *str, unsigned char *sha1)
 106 {
 107         static char pathname[PATH_MAX];
 108         static const char *prefix[] = {
 109                 "",
 110                 "refs",
 111                 "refs/tags",
 112                 "refs/heads",
 113                 "refs/snap",
 114                 NULL
 115         };
 116         const char **p;
 117
 118         if (!get_sha1_hex(str, sha1))
 119                 return 0;
 120
 121         if (!git_dir)
 122                 setup_git_env();
 123         for (p = prefix; *p; p++) {
 124                 snprintf(pathname, sizeof(pathname), "%s/%s/%s",
 125                          git_dir, *p, str);
 126                 if (!get_sha1_file(pathname, sha1))
 127                         return 0;
 128         }
 129
 130         return -1;
 131 }
 132
 133 char * sha1_to_hex(const unsigned char *sha1)
 134 {
 135         static char buffer[50];
 136         static const char hex[] = "0123456789abcdef";
 137         char *buf = buffer;
 138         int i;
 139
 140         for (i = 0; i < 20; i++) {
 141                 unsigned int val = *sha1++;
 142                 *buf++ = hex[val >> 4];
 143                 *buf++ = hex[val & 0xf];
 144         }
 145         return buffer;
 146 }
 147
 148 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 149 {
 150         int i;
 151         for (i = 0; i < 20; i++) {
 152                 static char hex[] = "0123456789abcdef";
 153                 unsigned int val = sha1[i];
 154                 char *pos = pathbuf + i*2 + (i > 0);
 155                 *pos++ = hex[val >> 4];
 156                 *pos = hex[val & 0xf];
 157         }
 158 }
 159
 160 /*
 161  * NOTE! This returns a statically allocated buffer, so you have to be
 162  * careful about using it. Do a "strdup()" if you need to save the
 163  * filename.
 164  *
 165  * Also note that this returns the location for creating.  Reading
 166  * SHA1 file can happen from any alternate directory listed in the
 167  * DB_ENVIRONMENT environment variable if it is not found in
 168  * the primary object database.
 169  */
 170 char *sha1_file_name(const unsigned char *sha1)
 171 {
 172         static char *name, *base;
 173
 174         if (!base) {
 175                 const char *sha1_file_directory = get_object_directory();
 176                 int len = strlen(sha1_file_directory);
 177                 base = xmalloc(len + 60);
 178                 memcpy(base, sha1_file_directory, len);
 179                 memset(base+len, 0, 60);
 180                 base[len] = '/';
 181                 base[len+3] = '/';
 182                 name = base + len + 1;
 183         }
 184         fill_sha1_path(name, sha1);
 185         return base;
 186 }
 187
 188 struct alternate_object_database *alt_odb;
 189
 190 /*
 191  * Prepare alternate object database registry.
 192  * alt_odb points at an array of struct alternate_object_database.
 193  * This array is terminated with an element that has both its base
 194  * and name set to NULL.  alt_odb[n] comes from n'th non-empty
 195  * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
 196  * variable, and its base points at a statically allocated buffer
 197  * that contains "/the/directory/corresponding/to/.git/objects/...",
 198  * while its name points just after the slash at the end of
 199  * ".git/objects/" in the example above, and has enough space to hold
 200  * 40-byte hex SHA1, an extra slash for the first level indirection,
 201  * and the terminating NUL.
 202  * This function allocates the alt_odb array and all the strings
 203  * pointed by base fields of the array elements with one xmalloc();
 204  * the string pool immediately follows the array.
 205  */
 206 void prepare_alt_odb(void)
 207 {
 208         int pass, totlen, i;
 209         const char *cp, *last;
 210         char *op = NULL;
 211         const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
 212
 213         if (alt_odb)
 214                 return;
 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         prepare_alt_odb();
 262         for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
 263                 fill_sha1_path(name, sha1);
 264                 if (!stat(alt_odb[i].base, st))
 265                         return alt_odb[i].base;
 266         }
 267         return NULL;
 268 }
 269
 270 #define PACK_MAX_SZ (1<<26)
 271 static int pack_used_ctr;
 272 static unsigned long pack_mapped;
 273 struct packed_git *packed_git;
 274
 275 struct pack_entry {
 276         unsigned int offset;
 277         unsigned char sha1[20];
 278         struct packed_git *p;
 279 };
 280
 281 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 282                                 void **idx_map_)
 283 {
 284         void *idx_map;
 285         unsigned int *index;
 286         unsigned long idx_size;
 287         int nr, i;
 288         int fd = open(path, O_RDONLY);
 289         struct stat st;
 290         if (fd < 0)
 291                 return -1;
 292         if (fstat(fd, &st)) {
 293                 close(fd);
 294                 return -1;
 295         }
 296         idx_size = st.st_size;
 297         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 298         close(fd);
 299         if (idx_map == MAP_FAILED)
 300                 return -1;
 301
 302         index = idx_map;
 303
 304         /* check index map */
 305         if (idx_size < 4*256 + 20)
 306                 return error("index file too small");
 307         nr = 0;
 308         for (i = 0; i < 256; i++) {
 309                 unsigned int n = ntohl(index[i]);
 310                 if (n < nr)
 311                         return error("non-monotonic index");
 312                 nr = n;
 313         }
 314
 315         /*
 316          * Total size:
 317          *  - 256 index entries 4 bytes each
 318          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 319          *  - 20-byte SHA1 of the packfile
 320          *  - 20-byte SHA1 file checksum
 321          */
 322         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 323                 return error("wrong index file size");
 324
 325         *idx_map_ = idx_map;
 326         *idx_size_ = idx_size;
 327         return 0;
 328 }
 329
 330 static void unuse_one_packed_git(void)
 331 {
 332         /* NOTYET */
 333 }
 334
 335 static int use_packed_git(struct packed_git *p)
 336 {
 337         if (!p->pack_base) {
 338                 int fd;
 339                 struct stat st;
 340                 void *map;
 341
 342                 pack_mapped += p->pack_size;
 343                 while (PACK_MAX_SZ < pack_mapped)
 344                         unuse_one_packed_git();
 345                 fd = open(p->pack_name, O_RDONLY);
 346                 if (fd < 0)
 347                         return -1;
 348                 if (fstat(fd, &st)) {
 349                         close(fd);
 350                         return -1;
 351                 }
 352                 if (st.st_size != p->pack_size)
 353                         return -1;
 354                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 355                 close(fd);
 356                 if (map == MAP_FAILED)
 357                         return -1;
 358                 p->pack_base = map;
 359         }
 360         p->pack_last_used = pack_used_ctr++;
 361         return 0;
 362 }
 363
 364 static struct packed_git *add_packed_git(char *path, int path_len)
 365 {
 366         struct stat st;
 367         struct packed_git *p;
 368         unsigned long idx_size;
 369         void *idx_map;
 370
 371         if (check_packed_git_idx(path, &idx_size, &idx_map))
 372                 return NULL;
 373
 374         /* do we have a corresponding .pack file? */
 375         strcpy(path + path_len - 4, ".pack");
 376         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 377                 munmap(idx_map, idx_size);
 378                 return NULL;
 379         }
 380         /* ok, it looks sane as far as we can check without
 381          * actually mapping the pack file.
 382          */
 383         p = xmalloc(sizeof(*p) + path_len + 2);
 384         strcpy(p->pack_name, path);
 385         p->index_size = idx_size;
 386         p->pack_size = st.st_size;
 387         p->index_base = idx_map;
 388         p->next = NULL;
 389         p->pack_base = NULL;
 390         p->pack_last_used = 0;
 391         return p;
 392 }
 393
 394 static void prepare_packed_git_one(char *objdir)
 395 {
 396         char path[PATH_MAX];
 397         int len;
 398         DIR *dir;
 399         struct dirent *de;
 400
 401         sprintf(path, "%s/pack", objdir);
 402         len = strlen(path);
 403         dir = opendir(path);
 404         if (!dir)
 405                 return;
 406         path[len++] = '/';
 407         while ((de = readdir(dir)) != NULL) {
 408                 int namelen = strlen(de->d_name);
 409                 struct packed_git *p;
 410
 411                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 412                         continue;
 413
 414                 /* we have .idx.  Is it a file we can map? */
 415                 strcpy(path + len, de->d_name);
 416                 p = add_packed_git(path, len + namelen);
 417                 if (!p)
 418                         continue;
 419                 p->next = packed_git;
 420                 packed_git = p;
 421         }
 422 }
 423
 424 void prepare_packed_git(void)
 425 {
 426         int i;
 427         static int run_once = 0;
 428
 429         if (run_once++)
 430                 return;
 431
 432         prepare_packed_git_one(get_object_directory());
 433         prepare_alt_odb();
 434         for (i = 0; alt_odb[i].base != NULL; i++) {
 435                 alt_odb[i].name[0] = 0;
 436                 prepare_packed_git_one(alt_odb[i].base);
 437         }
 438 }
 439
 440 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 441 {
 442         char header[100];
 443         unsigned char real_sha1[20];
 444         SHA_CTX c;
 445
 446         SHA1_Init(&c);
 447         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 448         SHA1_Update(&c, map, size);
 449         SHA1_Final(real_sha1, &c);
 450         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 451 }
 452
 453 static void *map_sha1_file_internal(const unsigned char *sha1,
 454                                     unsigned long *size,
 455                                     int say_error)
 456 {
 457         struct stat st;
 458         void *map;
 459         int fd;
 460         char *filename = find_sha1_file(sha1, &st);
 461
 462         if (!filename) {
 463                 if (say_error)
 464                         error("cannot map sha1 file %s", sha1_to_hex(sha1));
 465                 return NULL;
 466         }
 467
 468         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 469         if (fd < 0) {
 470                 /* See if it works without O_NOATIME */
 471                 switch (sha1_file_open_flag) {
 472                 default:
 473                         fd = open(filename, O_RDONLY);
 474                         if (fd >= 0)
 475                                 break;
 476                 /* Fallthrough */
 477                 case 0:
 478                         if (say_error)
 479                                 perror(filename);
 480                         return NULL;
 481                 }
 482
 483                 /* If it failed once, it will probably fail again.
 484                  * Stop using O_NOATIME
 485                  */
 486                 sha1_file_open_flag = 0;
 487         }
 488         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 489         close(fd);
 490         if (-1 == (int)(long)map)
 491                 return NULL;
 492         *size = st.st_size;
 493         return map;
 494 }
 495
 496 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 497 {
 498         return map_sha1_file_internal(sha1, size, 1);
 499 }
 500
 501 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 502 {
 503         /* Get the data stream */
 504         memset(stream, 0, sizeof(*stream));
 505         stream->next_in = map;
 506         stream->avail_in = mapsize;
 507         stream->next_out = buffer;
 508         stream->avail_out = size;
 509
 510         inflateInit(stream);
 511         return inflate(stream, 0);
 512 }
 513
 514 void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 515 {
 516         int bytes = strlen(buffer) + 1;
 517         unsigned char *buf = xmalloc(1+size);
 518
 519         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 520         bytes = stream->total_out - bytes;
 521         if (bytes < size) {
 522                 stream->next_out = buf + bytes;
 523                 stream->avail_out = size - bytes;
 524                 while (inflate(stream, Z_FINISH) == Z_OK)
 525                         /* nothing */;
 526         }
 527         buf[size] = 0;
 528         inflateEnd(stream);
 529         return buf;
 530 }
 531
 532 /*
 533  * We used to just use "sscanf()", but that's actually way
 534  * too permissive for what we want to check. So do an anal
 535  * object header parse by hand.
 536  */
 537 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 538 {
 539         int i;
 540         unsigned long size;
 541
 542         /*
 543          * The type can be at most ten bytes (including the
 544          * terminating '\0' that we add), and is followed by
 545          * a space.
 546          */
 547         i = 10;
 548         for (;;) {
 549                 char c = *hdr++;
 550                 if (c == ' ')
 551                         break;
 552                 if (!--i)
 553                         return -1;
 554                 *type++ = c;
 555         }
 556         *type = 0;
 557
 558         /*
 559          * The length must follow immediately, and be in canonical
 560          * decimal format (ie "010" is not valid).
 561          */
 562         size = *hdr++ - '0';
 563         if (size > 9)
 564                 return -1;
 565         if (size) {
 566                 for (;;) {
 567                         unsigned long c = *hdr - '0';
 568                         if (c > 9)
 569                                 break;
 570                         hdr++;
 571                         size = size * 10 + c;
 572                 }
 573         }
 574         *sizep = size;
 575
 576         /*
 577          * The length must be followed by a zero byte
 578          */
 579         return *hdr ? -1 : 0;
 580 }
 581
 582 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 583 {
 584         int ret;
 585         z_stream stream;
 586         char hdr[8192];
 587
 588         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 589         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 590                 return NULL;
 591
 592         return unpack_sha1_rest(&stream, hdr, *size);
 593 }
 594
 595 static unsigned long parse_delta_size(unsigned char **p)
 596 {
 597         unsigned char c;
 598         unsigned long size = 0;
 599         unsigned shift = 0;
 600         unsigned char *data = *p;
 601
 602         do {
 603                 c = *data++;
 604                 size += (c & 0x7f) << shift;
 605                 shift += 7;
 606         } while (c & 0x80);
 607         *p = data;
 608         return size;
 609 }
 610
 611 static int packed_delta_info(unsigned char *base_sha1,
 612                              unsigned long delta_size,
 613                              unsigned long left,
 614                              char *type,
 615                              unsigned long *sizep)
 616 {
 617         unsigned char *data;
 618         unsigned char delta_head[64];
 619         unsigned long data_size, result_size, base_size, verify_base_size;
 620         z_stream stream;
 621         int st;
 622
 623         if (left < 20)
 624                 die("truncated pack file");
 625         if (sha1_object_info(base_sha1, type, &base_size))
 626                 die("cannot get info for delta-pack base");
 627
 628         data = base_sha1 + 20;
 629         data_size = left - 20;
 630
 631         memset(&stream, 0, sizeof(stream));
 632
 633         stream.next_in = data;
 634         stream.avail_in = data_size;
 635         stream.next_out = delta_head;
 636         stream.avail_out = sizeof(delta_head);
 637
 638         inflateInit(&stream);
 639         st = inflate(&stream, Z_FINISH);
 640         inflateEnd(&stream);
 641         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head))
 642                 die("delta data unpack-initial failed");
 643
 644         /* Examine the initial part of the delta to figure out
 645          * the result size.  Verify the base size while we are at it.
 646          */
 647         data = delta_head;
 648         verify_base_size = parse_delta_size(&data);
 649         result_size = parse_delta_size(&data);
 650         if (verify_base_size != base_size)
 651                 die("delta base size mismatch");
 652
 653         *sizep = result_size;
 654         return 0;
 655 }
 656
 657 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 658         enum object_type *type, unsigned long *sizep)
 659 {
 660         unsigned shift;
 661         unsigned char *pack, c;
 662         unsigned long size;
 663
 664         if (offset >= p->pack_size)
 665                 die("object offset outside of pack file");
 666
 667         pack =  p->pack_base + offset;
 668         c = *pack++;
 669         offset++;
 670         *type = (c >> 4) & 7;
 671         size = c & 15;
 672         shift = 4;
 673         while (c & 0x80) {
 674                 if (offset >= p->pack_size)
 675                         die("object offset outside of pack file");
 676                 c = *pack++;
 677                 offset++;
 678                 size += (c & 0x7f) << shift;
 679                 shift += 7;
 680         }
 681         *sizep = size;
 682         return offset;
 683 }
 684
 685 static int packed_object_info(struct pack_entry *entry,
 686                               char *type, unsigned long *sizep)
 687 {
 688         struct packed_git *p = entry->p;
 689         unsigned long offset, size, left;
 690         unsigned char *pack;
 691         enum object_type kind;
 692
 693         if (use_packed_git(p))
 694                 die("cannot map packed file");
 695
 696         offset = unpack_object_header(p, entry->offset, &kind, &size);
 697         pack = p->pack_base + offset;
 698         left = p->pack_size - offset;
 699
 700         switch (kind) {
 701         case OBJ_DELTA:
 702                 return packed_delta_info(pack, size, left, type, sizep);
 703                 break;
 704         case OBJ_COMMIT:
 705                 strcpy(type, "commit");
 706                 break;
 707         case OBJ_TREE:
 708                 strcpy(type, "tree");
 709                 break;
 710         case OBJ_BLOB:
 711                 strcpy(type, "blob");
 712                 break;
 713         case OBJ_TAG:
 714                 strcpy(type, "tag");
 715                 break;
 716         default:
 717                 die("corrupted pack file");
 718         }
 719         *sizep = size;
 720         return 0;
 721 }
 722
 723 /* forward declaration for a mutually recursive function */
 724 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 725
 726 static void *unpack_delta_entry(unsigned char *base_sha1,
 727                                 unsigned long delta_size,
 728                                 unsigned long left,
 729                                 char *type,
 730                                 unsigned long *sizep)
 731 {
 732         void *data, *delta_data, *result, *base;
 733         unsigned long data_size, result_size, base_size;
 734         z_stream stream;
 735         int st;
 736
 737         if (left < 20)
 738                 die("truncated pack file");
 739         data = base_sha1 + 20;
 740         data_size = left - 20;
 741         delta_data = xmalloc(delta_size);
 742
 743         memset(&stream, 0, sizeof(stream));
 744
 745         stream.next_in = data;
 746         stream.avail_in = data_size;
 747         stream.next_out = delta_data;
 748         stream.avail_out = delta_size;
 749
 750         inflateInit(&stream);
 751         st = inflate(&stream, Z_FINISH);
 752         inflateEnd(&stream);
 753         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 754                 die("delta data unpack failed");
 755
 756         /* This may recursively unpack the base, which is what we want */
 757         base = read_sha1_file(base_sha1, type, &base_size);
 758         if (!base)
 759                 die("failed to read delta-pack base object %s",
 760                     sha1_to_hex(base_sha1));
 761         result = patch_delta(base, base_size,
 762                              delta_data, delta_size,
 763                              &result_size);
 764         if (!result)
 765                 die("failed to apply delta");
 766         free(delta_data);
 767         free(base);
 768         *sizep = result_size;
 769         return result;
 770 }
 771
 772 static void *unpack_non_delta_entry(unsigned char *data,
 773                                     unsigned long size,
 774                                     unsigned long left)
 775 {
 776         int st;
 777         z_stream stream;
 778         char *buffer;
 779
 780         buffer = xmalloc(size + 1);
 781         buffer[size] = 0;
 782         memset(&stream, 0, sizeof(stream));
 783         stream.next_in = data;
 784         stream.avail_in = left;
 785         stream.next_out = buffer;
 786         stream.avail_out = size;
 787
 788         inflateInit(&stream);
 789         st = inflate(&stream, Z_FINISH);
 790         inflateEnd(&stream);
 791         if ((st != Z_STREAM_END) || stream.total_out != size) {
 792                 free(buffer);
 793                 return NULL;
 794         }
 795
 796         return buffer;
 797 }
 798
 799 static void *unpack_entry(struct pack_entry *entry,
 800                           char *type, unsigned long *sizep)
 801 {
 802         struct packed_git *p = entry->p;
 803         unsigned long offset, size, left;
 804         unsigned char *pack;
 805         enum object_type kind;
 806
 807         if (use_packed_git(p))
 808                 die("cannot map packed file");
 809
 810         offset = unpack_object_header(p, entry->offset, &kind, &size);
 811         pack = p->pack_base + offset;
 812         left = p->pack_size - offset;
 813         switch (kind) {
 814         case OBJ_DELTA:
 815                 return unpack_delta_entry(pack, size, left, type, sizep);
 816         case OBJ_COMMIT:
 817                 strcpy(type, "commit");
 818                 break;
 819         case OBJ_TREE:
 820                 strcpy(type, "tree");
 821                 break;
 822         case OBJ_BLOB:
 823                 strcpy(type, "blob");
 824                 break;
 825         case OBJ_TAG:
 826                 strcpy(type, "tag");
 827                 break;
 828         default:
 829                 die("corrupted pack file");
 830         }
 831         *sizep = size;
 832         return unpack_non_delta_entry(pack, size, left);
 833 }
 834
 835 int num_packed_objects(const struct packed_git *p)
 836 {
 837         /* See check_packed_git_idx and pack-objects.c */
 838         return (p->index_size - 20 - 20 - 4*256) / 24;
 839 }
 840
 841 int nth_packed_object_sha1(const struct packed_git *p, int n,
 842                            unsigned char* sha1)
 843 {
 844         void *index = p->index_base + 256;
 845         if (n < 0 || num_packed_objects(p) <= n)
 846                 return -1;
 847         memcpy(sha1, (index + 24 * n + 4), 20);
 848         return 0;
 849 }
 850
 851 static int find_pack_entry_1(const unsigned char *sha1,
 852                              struct pack_entry *e, struct packed_git *p)
 853 {
 854         int *level1_ofs = p->index_base;
 855         int hi = ntohl(level1_ofs[*sha1]);
 856         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
 857         void *index = p->index_base + 256;
 858
 859         do {
 860                 int mi = (lo + hi) / 2;
 861                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
 862                 if (!cmp) {
 863                         e->offset = ntohl(*((int*)(index + 24 * mi)));
 864                         memcpy(e->sha1, sha1, 20);
 865                         e->p = p;
 866                         return 1;
 867                 }
 868                 if (cmp > 0)
 869                         hi = mi;
 870                 else
 871                         lo = mi+1;
 872         } while (lo < hi);
 873         return 0;
 874 }
 875
 876 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 877 {
 878         struct packed_git *p;
 879         prepare_packed_git();
 880
 881         for (p = packed_git; p; p = p->next) {
 882                 if (find_pack_entry_1(sha1, e, p))
 883                         return 1;
 884         }
 885         return 0;
 886 }
 887
 888 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
 889 {
 890         int status;
 891         unsigned long mapsize, size;
 892         void *map;
 893         z_stream stream;
 894         char hdr[128];
 895
 896         map = map_sha1_file_internal(sha1, &mapsize, 0);
 897         if (!map) {
 898                 struct pack_entry e;
 899
 900                 if (!find_pack_entry(sha1, &e))
 901                         return error("unable to find %s", sha1_to_hex(sha1));
 902                 if (!packed_object_info(&e, type, sizep))
 903                         return 0;
 904                 /* sheesh */
 905                 map = unpack_entry(&e, type, sizep);
 906                 free(map);
 907                 return (map == NULL) ? 0 : -1;
 908         }
 909         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
 910                 status = error("unable to unpack %s header",
 911                                sha1_to_hex(sha1));
 912         if (parse_sha1_header(hdr, type, &size) < 0)
 913                 status = error("unable to parse %s header", sha1_to_hex(sha1));
 914         else {
 915                 status = 0;
 916                 *sizep = size;
 917         }
 918         inflateEnd(&stream);
 919         munmap(map, mapsize);
 920         return status;
 921 }
 922
 923 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
 924 {
 925         struct pack_entry e;
 926
 927         if (!find_pack_entry(sha1, &e)) {
 928                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
 929                 return NULL;
 930         }
 931         return unpack_entry(&e, type, size);
 932 }
 933
 934 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
 935 {
 936         unsigned long mapsize;
 937         void *map, *buf;
 938
 939         map = map_sha1_file_internal(sha1, &mapsize, 0);
 940         if (map) {
 941                 buf = unpack_sha1_file(map, mapsize, type, size);
 942                 munmap(map, mapsize);
 943                 return buf;
 944         }
 945         return read_packed_sha1(sha1, type, size);
 946 }
 947
 948 void *read_object_with_reference(const unsigned char *sha1,
 949                                  const char *required_type,
 950                                  unsigned long *size,
 951                                  unsigned char *actual_sha1_return)
 952 {
 953         char type[20];
 954         void *buffer;
 955         unsigned long isize;
 956         unsigned char actual_sha1[20];
 957
 958         memcpy(actual_sha1, sha1, 20);
 959         while (1) {
 960                 int ref_length = -1;
 961                 const char *ref_type = NULL;
 962
 963                 buffer = read_sha1_file(actual_sha1, type, &isize);
 964                 if (!buffer)
 965                         return NULL;
 966                 if (!strcmp(type, required_type)) {
 967                         *size = isize;
 968                         if (actual_sha1_return)
 969                                 memcpy(actual_sha1_return, actual_sha1, 20);
 970                         return buffer;
 971                 }
 972                 /* Handle references */
 973                 else if (!strcmp(type, "commit"))
 974                         ref_type = "tree ";
 975                 else if (!strcmp(type, "tag"))
 976                         ref_type = "object ";
 977                 else {
 978                         free(buffer);
 979                         return NULL;
 980                 }
 981                 ref_length = strlen(ref_type);
 982
 983                 if (memcmp(buffer, ref_type, ref_length) ||
 984                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
 985                         free(buffer);
 986                         return NULL;
 987                 }
 988                 /* Now we have the ID of the referred-to object in
 989                  * actual_sha1.  Check again. */
 990         }
 991 }
 992
 993 static char *write_sha1_file_prepare(void *buf,
 994                                      unsigned long len,
 995                                      const char *type,
 996                                      unsigned char *sha1,
 997                                      unsigned char *hdr,
 998                                      int *hdrlen)
 999 {
1000         SHA_CTX c;
1001
1002         /* Generate the header */
1003         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1004
1005         /* Sha1.. */
1006         SHA1_Init(&c);
1007         SHA1_Update(&c, hdr, *hdrlen);
1008         SHA1_Update(&c, buf, len);
1009         SHA1_Final(sha1, &c);
1010
1011         return sha1_file_name(sha1);
1012 }
1013
1014 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1015 {
1016         int size;
1017         unsigned char *compressed;
1018         z_stream stream;
1019         unsigned char sha1[20];
1020         char *filename;
1021         static char tmpfile[PATH_MAX];
1022         unsigned char hdr[50];
1023         int fd, hdrlen, ret;
1024
1025         /* Normally if we have it in the pack then we do not bother writing
1026          * it out into .git/objects/??/?{38} file.
1027          */
1028         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1029         if (returnsha1)
1030                 memcpy(returnsha1, sha1, 20);
1031         if (has_sha1_file(sha1))
1032                 return 0;
1033         fd = open(filename, O_RDONLY);
1034         if (fd >= 0) {
1035                 /*
1036                  * FIXME!!! We might do collision checking here, but we'd
1037                  * need to uncompress the old file and check it. Later.
1038                  */
1039                 close(fd);
1040                 return 0;
1041         }
1042
1043         if (errno != ENOENT) {
1044                 fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
1045                 return -1;
1046         }
1047
1048         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1049
1050         fd = mkstemp(tmpfile);
1051         if (fd < 0) {
1052                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
1053                 return -1;
1054         }
1055
1056         /* Set it up */
1057         memset(&stream, 0, sizeof(stream));
1058         deflateInit(&stream, Z_BEST_COMPRESSION);
1059         size = deflateBound(&stream, len+hdrlen);
1060         compressed = xmalloc(size);
1061
1062         /* Compress it */
1063         stream.next_out = compressed;
1064         stream.avail_out = size;
1065
1066         /* First header.. */
1067         stream.next_in = hdr;
1068         stream.avail_in = hdrlen;
1069         while (deflate(&stream, 0) == Z_OK)
1070                 /* nothing */;
1071
1072         /* Then the data itself.. */
1073         stream.next_in = buf;
1074         stream.avail_in = len;
1075         while (deflate(&stream, Z_FINISH) == Z_OK)
1076                 /* nothing */;
1077         deflateEnd(&stream);
1078         size = stream.total_out;
1079
1080         if (write(fd, compressed, size) != size)
1081                 die("unable to write file");
1082         fchmod(fd, 0444);
1083         close(fd);
1084         free(compressed);
1085
1086         ret = link(tmpfile, filename);
1087         if (ret < 0) {
1088                 ret = errno;
1089
1090                 /*
1091                  * Coda hack - coda doesn't like cross-directory links,
1092                  * so we fall back to a rename, which will mean that it
1093                  * won't be able to check collisions, but that's not a
1094                  * big deal.
1095                  *
1096                  * When this succeeds, we just return 0. We have nothing
1097                  * left to unlink.
1098                  */
1099                 if (ret == EXDEV && !rename(tmpfile, filename))
1100                         return 0;
1101         }
1102         unlink(tmpfile);
1103         if (ret) {
1104                 if (ret != EEXIST) {
1105                         fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
1106                         return -1;
1107                 }
1108                 /* FIXME!!! Collision check here ? */
1109         }
1110
1111         return 0;
1112 }
1113
1114 int write_sha1_from_fd(const unsigned char *sha1, int fd)
1115 {
1116         char *filename = sha1_file_name(sha1);
1117
1118         int local;
1119         z_stream stream;
1120         unsigned char real_sha1[20];
1121         unsigned char buf[4096];
1122         unsigned char discard[4096];
1123         int ret;
1124         SHA_CTX c;
1125
1126         local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
1127
1128         if (local < 0)
1129                 return error("Couldn't open %s\n", filename);
1130
1131         memset(&stream, 0, sizeof(stream));
1132
1133         inflateInit(&stream);
1134
1135         SHA1_Init(&c);
1136
1137         do {
1138                 ssize_t size;
1139                 size = read(fd, buf, 4096);
1140                 if (size <= 0) {
1141                         close(local);
1142                         unlink(filename);
1143                         if (!size)
1144                                 return error("Connection closed?");
1145                         perror("Reading from connection");
1146                         return -1;
1147                 }
1148                 write(local, buf, size);
1149                 stream.avail_in = size;
1150                 stream.next_in = buf;
1151                 do {
1152                         stream.next_out = discard;
1153                         stream.avail_out = sizeof(discard);
1154                         ret = inflate(&stream, Z_SYNC_FLUSH);
1155                         SHA1_Update(&c, discard, sizeof(discard) -
1156                                     stream.avail_out);
1157                 } while (stream.avail_in && ret == Z_OK);
1158
1159         } while (ret == Z_OK);
1160         inflateEnd(&stream);
1161
1162         close(local);
1163         SHA1_Final(real_sha1, &c);
1164         if (ret != Z_STREAM_END) {
1165                 unlink(filename);
1166                 return error("File %s corrupted", sha1_to_hex(sha1));
1167         }
1168         if (memcmp(sha1, real_sha1, 20)) {
1169                 unlink(filename);
1170                 return error("File %s has bad hash\n", sha1_to_hex(sha1));
1171         }
1172
1173         return 0;
1174 }
1175
1176 int has_sha1_file(const unsigned char *sha1)
1177 {
1178         struct stat st;
1179         struct pack_entry e;
1180
1181         if (find_sha1_file(sha1, &st))
1182                 return 1;
1183         return find_pack_entry(sha1, &e);
1184 }
1185
1186 int index_fd(unsigned char *sha1, int fd, struct stat *st)
1187 {
1188         unsigned long size = st->st_size;
1189         void *buf;
1190         int ret;
1191
1192         buf = "";
1193         if (size)
1194                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1195         close(fd);
1196         if ((int)(long)buf == -1)
1197                 return -1;
1198
1199         ret = write_sha1_file(buf, size, "blob", sha1);
1200         if (size)
1201                 munmap(buf, size);
1202         return ret;
1203 }