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 "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12
  13 #ifndef O_NOATIME
  14 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  15 #define O_NOATIME 01000000
  16 #else
  17 #define O_NOATIME 0
  18 #endif
  19 #endif
  20
  21 const unsigned char null_sha1[20] = { 0, };
  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 int adjust_shared_perm(const char *path)
  50 {
  51         struct stat st;
  52         int mode;
  53
  54         if (!shared_repository)
  55                 return 0;
  56         if (lstat(path, &st) < 0)
  57                 return -1;
  58         mode = st.st_mode;
  59         if (mode & S_IRUSR)
  60                 mode |= S_IRGRP;
  61         if (mode & S_IWUSR)
  62                 mode |= S_IWGRP;
  63         if (mode & S_IXUSR)
  64                 mode |= S_IXGRP;
  65         if (S_ISDIR(mode))
  66                 mode |= S_ISGID;
  67         if (chmod(path, mode) < 0)
  68                 return -2;
  69         return 0;
  70 }
  71
  72 int safe_create_leading_directories(char *path)
  73 {
  74         char *pos = path;
  75         struct stat st;
  76
  77         if (*pos == '/')
  78                 pos++;
  79
  80         while (pos) {
  81                 pos = strchr(pos, '/');
  82                 if (!pos)
  83                         break;
  84                 *pos = 0;
  85                 if (!stat(path, &st)) {
  86                         /* path exists */
  87                         if (!S_ISDIR(st.st_mode)) {
  88                                 *pos = '/';
  89                                 return -3;
  90                         }
  91                 }
  92                 else if (mkdir(path, 0777)) {
  93                         *pos = '/';
  94                         return -1;
  95                 }
  96                 else if (adjust_shared_perm(path)) {
  97                         *pos = '/';
  98                         return -2;
  99                 }
 100                 *pos++ = '/';
 101         }
 102         return 0;
 103 }
 104
 105 char * sha1_to_hex(const unsigned char *sha1)
 106 {
 107         static char buffer[50];
 108         static const char hex[] = "0123456789abcdef";
 109         char *buf = buffer;
 110         int i;
 111
 112         for (i = 0; i < 20; i++) {
 113                 unsigned int val = *sha1++;
 114                 *buf++ = hex[val >> 4];
 115                 *buf++ = hex[val & 0xf];
 116         }
 117         *buf = '\0';
 118
 119         return buffer;
 120 }
 121
 122 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 123 {
 124         int i;
 125         for (i = 0; i < 20; i++) {
 126                 static char hex[] = "0123456789abcdef";
 127                 unsigned int val = sha1[i];
 128                 char *pos = pathbuf + i*2 + (i > 0);
 129                 *pos++ = hex[val >> 4];
 130                 *pos = hex[val & 0xf];
 131         }
 132 }
 133
 134 /*
 135  * NOTE! This returns a statically allocated buffer, so you have to be
 136  * careful about using it. Do a "strdup()" if you need to save the
 137  * filename.
 138  *
 139  * Also note that this returns the location for creating.  Reading
 140  * SHA1 file can happen from any alternate directory listed in the
 141  * DB_ENVIRONMENT environment variable if it is not found in
 142  * the primary object database.
 143  */
 144 char *sha1_file_name(const unsigned char *sha1)
 145 {
 146         static char *name, *base;
 147
 148         if (!base) {
 149                 const char *sha1_file_directory = get_object_directory();
 150                 int len = strlen(sha1_file_directory);
 151                 base = xmalloc(len + 60);
 152                 memcpy(base, sha1_file_directory, len);
 153                 memset(base+len, 0, 60);
 154                 base[len] = '/';
 155                 base[len+3] = '/';
 156                 name = base + len + 1;
 157         }
 158         fill_sha1_path(name, sha1);
 159         return base;
 160 }
 161
 162 char *sha1_pack_name(const unsigned char *sha1)
 163 {
 164         static const char hex[] = "0123456789abcdef";
 165         static char *name, *base, *buf;
 166         int i;
 167
 168         if (!base) {
 169                 const char *sha1_file_directory = get_object_directory();
 170                 int len = strlen(sha1_file_directory);
 171                 base = xmalloc(len + 60);
 172                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 173                 name = base + len + 11;
 174         }
 175
 176         buf = name;
 177
 178         for (i = 0; i < 20; i++) {
 179                 unsigned int val = *sha1++;
 180                 *buf++ = hex[val >> 4];
 181                 *buf++ = hex[val & 0xf];
 182         }
 183
 184         return base;
 185 }
 186
 187 char *sha1_pack_index_name(const unsigned char *sha1)
 188 {
 189         static const char hex[] = "0123456789abcdef";
 190         static char *name, *base, *buf;
 191         int i;
 192
 193         if (!base) {
 194                 const char *sha1_file_directory = get_object_directory();
 195                 int len = strlen(sha1_file_directory);
 196                 base = xmalloc(len + 60);
 197                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 198                 name = base + len + 11;
 199         }
 200
 201         buf = name;
 202
 203         for (i = 0; i < 20; i++) {
 204                 unsigned int val = *sha1++;
 205                 *buf++ = hex[val >> 4];
 206                 *buf++ = hex[val & 0xf];
 207         }
 208
 209         return base;
 210 }
 211
 212 struct alternate_object_database *alt_odb_list;
 213 static struct alternate_object_database **alt_odb_tail;
 214
 215 /*
 216  * Prepare alternate object database registry.
 217  *
 218  * The variable alt_odb_list points at the list of struct
 219  * alternate_object_database.  The elements on this list come from
 220  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 221  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 222  * whose contents is similar to that environment variable but can be
 223  * LF separated.  Its base points at a statically allocated buffer that
 224  * contains "/the/directory/corresponding/to/.git/objects/...", while
 225  * its name points just after the slash at the end of ".git/objects/"
 226  * in the example above, and has enough space to hold 40-byte hex
 227  * SHA1, an extra slash for the first level indirection, and the
 228  * terminating NUL.
 229  */
 230 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 231                                  const char *relative_base)
 232 {
 233         const char *cp, *last;
 234         struct alternate_object_database *ent;
 235         const char *objdir = get_object_directory();
 236         int base_len = -1;
 237
 238         last = alt;
 239         while (last < ep) {
 240                 cp = last;
 241                 if (cp < ep && *cp == '#') {
 242                         while (cp < ep && *cp != sep)
 243                                 cp++;
 244                         last = cp + 1;
 245                         continue;
 246                 }
 247                 for ( ; cp < ep && *cp != sep; cp++)
 248                         ;
 249                 if (last != cp) {
 250                         struct alternate_object_database *alt;
 251                         /* 43 = 40-byte + 2 '/' + terminating NUL */
 252                         int pfxlen = cp - last;
 253                         int entlen = pfxlen + 43;
 254
 255                         if (*last != '/' && relative_base) {
 256                                 /* Relative alt-odb */
 257                                 if (base_len < 0)
 258                                         base_len = strlen(relative_base) + 1;
 259                                 entlen += base_len;
 260                                 pfxlen += base_len;
 261                         }
 262                         ent = xmalloc(sizeof(*ent) + entlen);
 263
 264                         if (*last != '/' && relative_base) {
 265                                 memcpy(ent->base, relative_base, base_len - 1);
 266                                 ent->base[base_len - 1] = '/';
 267                                 memcpy(ent->base + base_len,
 268                                        last, cp - last);
 269                         }
 270                         else
 271                                 memcpy(ent->base, last, pfxlen);
 272                         ent->name = ent->base + pfxlen + 1;
 273                         ent->base[pfxlen] = ent->base[pfxlen + 3] = '/';
 274                         ent->base[entlen-1] = 0;
 275
 276                         /* Prevent the common mistake of listing the same
 277                          * thing twice, or object directory itself.
 278                          */
 279                         for (alt = alt_odb_list; alt; alt = alt->next)
 280                                 if (!memcmp(ent->base, alt->base, pfxlen))
 281                                         goto bad;
 282                         if (!memcmp(ent->base, objdir, pfxlen)) {
 283                         bad:
 284                                 free(ent);
 285                         }
 286                         else {
 287                                 *alt_odb_tail = ent;
 288                                 alt_odb_tail = &(ent->next);
 289                                 ent->next = NULL;
 290                         }
 291                 }
 292                 while (cp < ep && *cp == sep)
 293                         cp++;
 294                 last = cp;
 295         }
 296 }
 297
 298 void prepare_alt_odb(void)
 299 {
 300         char path[PATH_MAX];
 301         char *map;
 302         int fd;
 303         struct stat st;
 304         char *alt;
 305
 306         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 307         if (!alt) alt = "";
 308
 309         if (alt_odb_tail)
 310                 return;
 311         alt_odb_tail = &alt_odb_list;
 312         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL);
 313
 314         sprintf(path, "%s/info/alternates", get_object_directory());
 315         fd = open(path, O_RDONLY);
 316         if (fd < 0)
 317                 return;
 318         if (fstat(fd, &st) || (st.st_size == 0)) {
 319                 close(fd);
 320                 return;
 321         }
 322         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 323         close(fd);
 324         if (map == MAP_FAILED)
 325                 return;
 326
 327         link_alt_odb_entries(map, map + st.st_size, '\n',
 328                              get_object_directory());
 329         munmap(map, st.st_size);
 330 }
 331
 332 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 333 {
 334         char *name = sha1_file_name(sha1);
 335         struct alternate_object_database *alt;
 336
 337         if (!stat(name, st))
 338                 return name;
 339         prepare_alt_odb();
 340         for (alt = alt_odb_list; alt; alt = alt->next) {
 341                 name = alt->name;
 342                 fill_sha1_path(name, sha1);
 343                 if (!stat(alt->base, st))
 344                         return alt->base;
 345         }
 346         return NULL;
 347 }
 348
 349 #define PACK_MAX_SZ (1<<26)
 350 static int pack_used_ctr;
 351 static unsigned long pack_mapped;
 352 struct packed_git *packed_git;
 353
 354 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 355                                 void **idx_map_)
 356 {
 357         void *idx_map;
 358         unsigned int *index;
 359         unsigned long idx_size;
 360         int nr, i;
 361         int fd = open(path, O_RDONLY);
 362         struct stat st;
 363         if (fd < 0)
 364                 return -1;
 365         if (fstat(fd, &st)) {
 366                 close(fd);
 367                 return -1;
 368         }
 369         idx_size = st.st_size;
 370         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 371         close(fd);
 372         if (idx_map == MAP_FAILED)
 373                 return -1;
 374
 375         index = idx_map;
 376         *idx_map_ = idx_map;
 377         *idx_size_ = idx_size;
 378
 379         /* check index map */
 380         if (idx_size < 4*256 + 20 + 20)
 381                 return error("index file too small");
 382         nr = 0;
 383         for (i = 0; i < 256; i++) {
 384                 unsigned int n = ntohl(index[i]);
 385                 if (n < nr)
 386                         return error("non-monotonic index");
 387                 nr = n;
 388         }
 389
 390         /*
 391          * Total size:
 392          *  - 256 index entries 4 bytes each
 393          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 394          *  - 20-byte SHA1 of the packfile
 395          *  - 20-byte SHA1 file checksum
 396          */
 397         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 398                 return error("wrong index file size");
 399
 400         return 0;
 401 }
 402
 403 static int unuse_one_packed_git(void)
 404 {
 405         struct packed_git *p, *lru = NULL;
 406
 407         for (p = packed_git; p; p = p->next) {
 408                 if (p->pack_use_cnt || !p->pack_base)
 409                         continue;
 410                 if (!lru || p->pack_last_used < lru->pack_last_used)
 411                         lru = p;
 412         }
 413         if (!lru)
 414                 return 0;
 415         munmap(lru->pack_base, lru->pack_size);
 416         lru->pack_base = NULL;
 417         return 1;
 418 }
 419
 420 void unuse_packed_git(struct packed_git *p)
 421 {
 422         p->pack_use_cnt--;
 423 }
 424
 425 int use_packed_git(struct packed_git *p)
 426 {
 427         if (!p->pack_size) {
 428                 struct stat st;
 429                 // We created the struct before we had the pack
 430                 stat(p->pack_name, &st);
 431                 if (!S_ISREG(st.st_mode))
 432                         die("packfile %s not a regular file", p->pack_name);
 433                 p->pack_size = st.st_size;
 434         }
 435         if (!p->pack_base) {
 436                 int fd;
 437                 struct stat st;
 438                 void *map;
 439
 440                 pack_mapped += p->pack_size;
 441                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 442                         ; /* nothing */
 443                 fd = open(p->pack_name, O_RDONLY);
 444                 if (fd < 0)
 445                         die("packfile %s cannot be opened", p->pack_name);
 446                 if (fstat(fd, &st)) {
 447                         close(fd);
 448                         die("packfile %s cannot be opened", p->pack_name);
 449                 }
 450                 if (st.st_size != p->pack_size)
 451                         die("packfile %s size mismatch.", p->pack_name);
 452                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 453                 close(fd);
 454                 if (map == MAP_FAILED)
 455                         die("packfile %s cannot be mapped.", p->pack_name);
 456                 p->pack_base = map;
 457
 458                 /* Check if the pack file matches with the index file.
 459                  * this is cheap.
 460                  */
 461                 if (memcmp((char*)(p->index_base) + p->index_size - 40,
 462                            p->pack_base + p->pack_size - 20, 20)) {
 463
 464                         die("packfile %s does not match index.", p->pack_name);
 465                 }
 466         }
 467         p->pack_last_used = pack_used_ctr++;
 468         p->pack_use_cnt++;
 469         return 0;
 470 }
 471
 472 struct packed_git *add_packed_git(char *path, int path_len, int local)
 473 {
 474         struct stat st;
 475         struct packed_git *p;
 476         unsigned long idx_size;
 477         void *idx_map;
 478         unsigned char sha1[20];
 479
 480         if (check_packed_git_idx(path, &idx_size, &idx_map))
 481                 return NULL;
 482
 483         /* do we have a corresponding .pack file? */
 484         strcpy(path + path_len - 4, ".pack");
 485         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 486                 munmap(idx_map, idx_size);
 487                 return NULL;
 488         }
 489         /* ok, it looks sane as far as we can check without
 490          * actually mapping the pack file.
 491          */
 492         p = xmalloc(sizeof(*p) + path_len + 2);
 493         strcpy(p->pack_name, path);
 494         p->index_size = idx_size;
 495         p->pack_size = st.st_size;
 496         p->index_base = idx_map;
 497         p->next = NULL;
 498         p->pack_base = NULL;
 499         p->pack_last_used = 0;
 500         p->pack_use_cnt = 0;
 501         p->pack_local = local;
 502         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 503                 memcpy(p->sha1, sha1, 20);
 504         return p;
 505 }
 506
 507 struct packed_git *parse_pack_index(unsigned char *sha1)
 508 {
 509         char *path = sha1_pack_index_name(sha1);
 510         return parse_pack_index_file(sha1, path);
 511 }
 512
 513 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 514 {
 515         struct packed_git *p;
 516         unsigned long idx_size;
 517         void *idx_map;
 518         char *path;
 519
 520         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 521                 return NULL;
 522
 523         path = sha1_pack_name(sha1);
 524
 525         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 526         strcpy(p->pack_name, path);
 527         p->index_size = idx_size;
 528         p->pack_size = 0;
 529         p->index_base = idx_map;
 530         p->next = NULL;
 531         p->pack_base = NULL;
 532         p->pack_last_used = 0;
 533         p->pack_use_cnt = 0;
 534         memcpy(p->sha1, sha1, 20);
 535         return p;
 536 }
 537
 538 void install_packed_git(struct packed_git *pack)
 539 {
 540         pack->next = packed_git;
 541         packed_git = pack;
 542 }
 543
 544 static void prepare_packed_git_one(char *objdir, int local)
 545 {
 546         char path[PATH_MAX];
 547         int len;
 548         DIR *dir;
 549         struct dirent *de;
 550
 551         sprintf(path, "%s/pack", objdir);
 552         len = strlen(path);
 553         dir = opendir(path);
 554         if (!dir) {
 555                 fprintf(stderr, "unable to open object pack directory: %s: %s\n", path, strerror(errno));
 556                 return;
 557         }
 558         path[len++] = '/';
 559         while ((de = readdir(dir)) != NULL) {
 560                 int namelen = strlen(de->d_name);
 561                 struct packed_git *p;
 562
 563                 if (strcmp(de->d_name + namelen - 4, ".idx"))
 564                         continue;
 565
 566                 /* we have .idx.  Is it a file we can map? */
 567                 strcpy(path + len, de->d_name);
 568                 p = add_packed_git(path, len + namelen, local);
 569                 if (!p)
 570                         continue;
 571                 p->next = packed_git;
 572                 packed_git = p;
 573         }
 574         closedir(dir);
 575 }
 576
 577 void prepare_packed_git(void)
 578 {
 579         static int run_once = 0;
 580         struct alternate_object_database *alt;
 581
 582         if (run_once)
 583                 return;
 584         prepare_packed_git_one(get_object_directory(), 1);
 585         prepare_alt_odb();
 586         for (alt = alt_odb_list; alt; alt = alt->next) {
 587                 alt->name[-1] = 0;
 588                 prepare_packed_git_one(alt->base, 0);
 589                 alt->name[-1] = '/';
 590         }
 591         run_once = 1;
 592 }
 593
 594 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 595 {
 596         char header[100];
 597         unsigned char real_sha1[20];
 598         SHA_CTX c;
 599
 600         SHA1_Init(&c);
 601         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 602         SHA1_Update(&c, map, size);
 603         SHA1_Final(real_sha1, &c);
 604         return memcmp(sha1, real_sha1, 20) ? -1 : 0;
 605 }
 606
 607 static void *map_sha1_file_internal(const unsigned char *sha1,
 608                                     unsigned long *size)
 609 {
 610         struct stat st;
 611         void *map;
 612         int fd;
 613         char *filename = find_sha1_file(sha1, &st);
 614
 615         if (!filename) {
 616                 return NULL;
 617         }
 618
 619         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 620         if (fd < 0) {
 621                 /* See if it works without O_NOATIME */
 622                 switch (sha1_file_open_flag) {
 623                 default:
 624                         fd = open(filename, O_RDONLY);
 625                         if (fd >= 0)
 626                                 break;
 627                 /* Fallthrough */
 628                 case 0:
 629                         return NULL;
 630                 }
 631
 632                 /* If it failed once, it will probably fail again.
 633                  * Stop using O_NOATIME
 634                  */
 635                 sha1_file_open_flag = 0;
 636         }
 637         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 638         close(fd);
 639         if (map == MAP_FAILED)
 640                 return NULL;
 641         *size = st.st_size;
 642         return map;
 643 }
 644
 645 int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
 646 {
 647         /* Get the data stream */
 648         memset(stream, 0, sizeof(*stream));
 649         stream->next_in = map;
 650         stream->avail_in = mapsize;
 651         stream->next_out = buffer;
 652         stream->avail_out = size;
 653
 654         inflateInit(stream);
 655         return inflate(stream, 0);
 656 }
 657
 658 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 659 {
 660         int bytes = strlen(buffer) + 1;
 661         unsigned char *buf = xmalloc(1+size);
 662
 663         memcpy(buf, buffer + bytes, stream->total_out - bytes);
 664         bytes = stream->total_out - bytes;
 665         if (bytes < size) {
 666                 stream->next_out = buf + bytes;
 667                 stream->avail_out = size - bytes;
 668                 while (inflate(stream, Z_FINISH) == Z_OK)
 669                         /* nothing */;
 670         }
 671         buf[size] = 0;
 672         inflateEnd(stream);
 673         return buf;
 674 }
 675
 676 /*
 677  * We used to just use "sscanf()", but that's actually way
 678  * too permissive for what we want to check. So do an anal
 679  * object header parse by hand.
 680  */
 681 int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 682 {
 683         int i;
 684         unsigned long size;
 685
 686         /*
 687          * The type can be at most ten bytes (including the
 688          * terminating '\0' that we add), and is followed by
 689          * a space.
 690          */
 691         i = 10;
 692         for (;;) {
 693                 char c = *hdr++;
 694                 if (c == ' ')
 695                         break;
 696                 if (!--i)
 697                         return -1;
 698                 *type++ = c;
 699         }
 700         *type = 0;
 701
 702         /*
 703          * The length must follow immediately, and be in canonical
 704          * decimal format (ie "010" is not valid).
 705          */
 706         size = *hdr++ - '0';
 707         if (size > 9)
 708                 return -1;
 709         if (size) {
 710                 for (;;) {
 711                         unsigned long c = *hdr - '0';
 712                         if (c > 9)
 713                                 break;
 714                         hdr++;
 715                         size = size * 10 + c;
 716                 }
 717         }
 718         *sizep = size;
 719
 720         /*
 721          * The length must be followed by a zero byte
 722          */
 723         return *hdr ? -1 : 0;
 724 }
 725
 726 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 727 {
 728         int ret;
 729         z_stream stream;
 730         char hdr[8192];
 731
 732         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 733         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 734                 return NULL;
 735
 736         return unpack_sha1_rest(&stream, hdr, *size);
 737 }
 738
 739 /* forward declaration for a mutually recursive function */
 740 static int packed_object_info(struct pack_entry *entry,
 741                               char *type, unsigned long *sizep);
 742
 743 static int packed_delta_info(unsigned char *base_sha1,
 744                              unsigned long delta_size,
 745                              unsigned long left,
 746                              char *type,
 747                              unsigned long *sizep,
 748                              struct packed_git *p)
 749 {
 750         struct pack_entry base_ent;
 751
 752         if (left < 20)
 753                 die("truncated pack file");
 754
 755         /* The base entry _must_ be in the same pack */
 756         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 757                 die("failed to find delta-pack base object %s",
 758                     sha1_to_hex(base_sha1));
 759
 760         /* We choose to only get the type of the base object and
 761          * ignore potentially corrupt pack file that expects the delta
 762          * based on a base with a wrong size.  This saves tons of
 763          * inflate() calls.
 764          */
 765
 766         if (packed_object_info(&base_ent, type, NULL))
 767                 die("cannot get info for delta-pack base");
 768
 769         if (sizep) {
 770                 const unsigned char *data;
 771                 unsigned char delta_head[64];
 772                 unsigned long result_size;
 773                 z_stream stream;
 774                 int st;
 775
 776                 memset(&stream, 0, sizeof(stream));
 777
 778                 data = stream.next_in = base_sha1 + 20;
 779                 stream.avail_in = left - 20;
 780                 stream.next_out = delta_head;
 781                 stream.avail_out = sizeof(delta_head);
 782
 783                 inflateInit(&stream);
 784                 st = inflate(&stream, Z_FINISH);
 785                 inflateEnd(&stream);
 786                 if ((st != Z_STREAM_END) &&
 787                     stream.total_out != sizeof(delta_head))
 788                         die("delta data unpack-initial failed");
 789
 790                 /* Examine the initial part of the delta to figure out
 791                  * the result size.
 792                  */
 793                 data = delta_head;
 794                 get_delta_hdr_size(&data); /* ignore base size */
 795
 796                 /* Read the result size */
 797                 result_size = get_delta_hdr_size(&data);
 798                 *sizep = result_size;
 799         }
 800         return 0;
 801 }
 802
 803 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 804         enum object_type *type, unsigned long *sizep)
 805 {
 806         unsigned shift;
 807         unsigned char *pack, c;
 808         unsigned long size;
 809
 810         if (offset >= p->pack_size)
 811                 die("object offset outside of pack file");
 812
 813         pack =  p->pack_base + offset;
 814         c = *pack++;
 815         offset++;
 816         *type = (c >> 4) & 7;
 817         size = c & 15;
 818         shift = 4;
 819         while (c & 0x80) {
 820                 if (offset >= p->pack_size)
 821                         die("object offset outside of pack file");
 822                 c = *pack++;
 823                 offset++;
 824                 size += (c & 0x7f) << shift;
 825                 shift += 7;
 826         }
 827         *sizep = size;
 828         return offset;
 829 }
 830
 831 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 832                            unsigned char *base, unsigned long *sizep,
 833                            enum object_type *kindp)
 834 {
 835         unsigned long ptr;
 836         int status = -1;
 837
 838         use_packed_git(p);
 839         ptr = offset;
 840         ptr = unpack_object_header(p, ptr, kindp, sizep);
 841         if (*kindp != OBJ_DELTA)
 842                 goto done;
 843         memcpy(base, p->pack_base + ptr, 20);
 844         status = 0;
 845  done:
 846         unuse_packed_git(p);
 847         return status;
 848 }
 849
 850 void packed_object_info_detail(struct pack_entry *e,
 851                                char *type,
 852                                unsigned long *size,
 853                                unsigned long *store_size,
 854                                unsigned int *delta_chain_length,
 855                                unsigned char *base_sha1)
 856 {
 857         struct packed_git *p = e->p;
 858         unsigned long offset, left;
 859         unsigned char *pack;
 860         enum object_type kind;
 861
 862         offset = unpack_object_header(p, e->offset, &kind, size);
 863         pack = p->pack_base + offset;
 864         left = p->pack_size - offset;
 865         if (kind != OBJ_DELTA)
 866                 *delta_chain_length = 0;
 867         else {
 868                 unsigned int chain_length = 0;
 869                 memcpy(base_sha1, pack, 20);
 870                 do {
 871                         struct pack_entry base_ent;
 872                         unsigned long junk;
 873
 874                         find_pack_entry_one(pack, &base_ent, p);
 875                         offset = unpack_object_header(p, base_ent.offset,
 876                                                       &kind, &junk);
 877                         pack = p->pack_base + offset;
 878                         chain_length++;
 879                 } while (kind == OBJ_DELTA);
 880                 *delta_chain_length = chain_length;
 881         }
 882         switch (kind) {
 883         case OBJ_COMMIT:
 884                 strcpy(type, "commit");
 885                 break;
 886         case OBJ_TREE:
 887                 strcpy(type, "tree");
 888                 break;
 889         case OBJ_BLOB:
 890                 strcpy(type, "blob");
 891                 break;
 892         case OBJ_TAG:
 893                 strcpy(type, "tag");
 894                 break;
 895         default:
 896                 die("corrupted pack file %s containing object of kind %d",
 897                     p->pack_name, kind);
 898         }
 899         *store_size = 0; /* notyet */
 900 }
 901
 902 static int packed_object_info(struct pack_entry *entry,
 903                               char *type, unsigned long *sizep)
 904 {
 905         struct packed_git *p = entry->p;
 906         unsigned long offset, size, left;
 907         unsigned char *pack;
 908         enum object_type kind;
 909         int retval;
 910
 911         if (use_packed_git(p))
 912                 die("cannot map packed file");
 913
 914         offset = unpack_object_header(p, entry->offset, &kind, &size);
 915         pack = p->pack_base + offset;
 916         left = p->pack_size - offset;
 917
 918         switch (kind) {
 919         case OBJ_DELTA:
 920                 retval = packed_delta_info(pack, size, left, type, sizep, p);
 921                 unuse_packed_git(p);
 922                 return retval;
 923         case OBJ_COMMIT:
 924                 strcpy(type, "commit");
 925                 break;
 926         case OBJ_TREE:
 927                 strcpy(type, "tree");
 928                 break;
 929         case OBJ_BLOB:
 930                 strcpy(type, "blob");
 931                 break;
 932         case OBJ_TAG:
 933                 strcpy(type, "tag");
 934                 break;
 935         default:
 936                 die("corrupted pack file %s containing object of kind %d",
 937                     p->pack_name, kind);
 938         }
 939         if (sizep)
 940                 *sizep = size;
 941         unuse_packed_git(p);
 942         return 0;
 943 }
 944
 945 /* forward declaration for a mutually recursive function */
 946 static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
 947
 948 static void *unpack_delta_entry(unsigned char *base_sha1,
 949                                 unsigned long delta_size,
 950                                 unsigned long left,
 951                                 char *type,
 952                                 unsigned long *sizep,
 953                                 struct packed_git *p)
 954 {
 955         struct pack_entry base_ent;
 956         void *data, *delta_data, *result, *base;
 957         unsigned long data_size, result_size, base_size;
 958         z_stream stream;
 959         int st;
 960
 961         if (left < 20)
 962                 die("truncated pack file");
 963         data = base_sha1 + 20;
 964         data_size = left - 20;
 965         delta_data = xmalloc(delta_size);
 966
 967         memset(&stream, 0, sizeof(stream));
 968
 969         stream.next_in = data;
 970         stream.avail_in = data_size;
 971         stream.next_out = delta_data;
 972         stream.avail_out = delta_size;
 973
 974         inflateInit(&stream);
 975         st = inflate(&stream, Z_FINISH);
 976         inflateEnd(&stream);
 977         if ((st != Z_STREAM_END) || stream.total_out != delta_size)
 978                 die("delta data unpack failed");
 979
 980         /* The base entry _must_ be in the same pack */
 981         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 982                 die("failed to find delta-pack base object %s",
 983                     sha1_to_hex(base_sha1));
 984         base = unpack_entry_gently(&base_ent, type, &base_size);
 985         if (!base)
 986                 die("failed to read delta-pack base object %s",
 987                     sha1_to_hex(base_sha1));
 988         result = patch_delta(base, base_size,
 989                              delta_data, delta_size,
 990                              &result_size);
 991         if (!result)
 992                 die("failed to apply delta");
 993         free(delta_data);
 994         free(base);
 995         *sizep = result_size;
 996         return result;
 997 }
 998
 999 static void *unpack_non_delta_entry(unsigned char *data,
1000                                     unsigned long size,
1001                                     unsigned long left)
1002 {
1003         int st;
1004         z_stream stream;
1005         unsigned char *buffer;
1006
1007         buffer = xmalloc(size + 1);
1008         buffer[size] = 0;
1009         memset(&stream, 0, sizeof(stream));
1010         stream.next_in = data;
1011         stream.avail_in = left;
1012         stream.next_out = buffer;
1013         stream.avail_out = size;
1014
1015         inflateInit(&stream);
1016         st = inflate(&stream, Z_FINISH);
1017         inflateEnd(&stream);
1018         if ((st != Z_STREAM_END) || stream.total_out != size) {
1019                 free(buffer);
1020                 return NULL;
1021         }
1022
1023         return buffer;
1024 }
1025
1026 static void *unpack_entry(struct pack_entry *entry,
1027                           char *type, unsigned long *sizep)
1028 {
1029         struct packed_git *p = entry->p;
1030         void *retval;
1031
1032         if (use_packed_git(p))
1033                 die("cannot map packed file");
1034         retval = unpack_entry_gently(entry, type, sizep);
1035         unuse_packed_git(p);
1036         if (!retval)
1037                 die("corrupted pack file %s", p->pack_name);
1038         return retval;
1039 }
1040
1041 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1042 void *unpack_entry_gently(struct pack_entry *entry,
1043                           char *type, unsigned long *sizep)
1044 {
1045         struct packed_git *p = entry->p;
1046         unsigned long offset, size, left;
1047         unsigned char *pack;
1048         enum object_type kind;
1049         void *retval;
1050
1051         offset = unpack_object_header(p, entry->offset, &kind, &size);
1052         pack = p->pack_base + offset;
1053         left = p->pack_size - offset;
1054         switch (kind) {
1055         case OBJ_DELTA:
1056                 retval = unpack_delta_entry(pack, size, left, type, sizep, p);
1057                 return retval;
1058         case OBJ_COMMIT:
1059                 strcpy(type, "commit");
1060                 break;
1061         case OBJ_TREE:
1062                 strcpy(type, "tree");
1063                 break;
1064         case OBJ_BLOB:
1065                 strcpy(type, "blob");
1066                 break;
1067         case OBJ_TAG:
1068                 strcpy(type, "tag");
1069                 break;
1070         default:
1071                 return NULL;
1072         }
1073         *sizep = size;
1074         retval = unpack_non_delta_entry(pack, size, left);
1075         return retval;
1076 }
1077
1078 int num_packed_objects(const struct packed_git *p)
1079 {
1080         /* See check_packed_git_idx() */
1081         return (p->index_size - 20 - 20 - 4*256) / 24;
1082 }
1083
1084 int nth_packed_object_sha1(const struct packed_git *p, int n,
1085                            unsigned char* sha1)
1086 {
1087         void *index = p->index_base + 256;
1088         if (n < 0 || num_packed_objects(p) <= n)
1089                 return -1;
1090         memcpy(sha1, (index + 24 * n + 4), 20);
1091         return 0;
1092 }
1093
1094 int find_pack_entry_one(const unsigned char *sha1,
1095                         struct pack_entry *e, struct packed_git *p)
1096 {
1097         unsigned int *level1_ofs = p->index_base;
1098         int hi = ntohl(level1_ofs[*sha1]);
1099         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1100         void *index = p->index_base + 256;
1101
1102         do {
1103                 int mi = (lo + hi) / 2;
1104                 int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
1105                 if (!cmp) {
1106                         e->offset = ntohl(*((int*)(index + 24 * mi)));
1107                         memcpy(e->sha1, sha1, 20);
1108                         e->p = p;
1109                         return 1;
1110                 }
1111                 if (cmp > 0)
1112                         hi = mi;
1113                 else
1114                         lo = mi+1;
1115         } while (lo < hi);
1116         return 0;
1117 }
1118
1119 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1120 {
1121         struct packed_git *p;
1122         prepare_packed_git();
1123
1124         for (p = packed_git; p; p = p->next) {
1125                 if (find_pack_entry_one(sha1, e, p))
1126                         return 1;
1127         }
1128         return 0;
1129 }
1130
1131 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1132                                   struct packed_git *packs)
1133 {
1134         struct packed_git *p;
1135         struct pack_entry e;
1136
1137         for (p = packs; p; p = p->next) {
1138                 if (find_pack_entry_one(sha1, &e, p))
1139                         return p;
1140         }
1141         return NULL;
1142
1143 }
1144
1145 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1146 {
1147         int status;
1148         unsigned long mapsize, size;
1149         void *map;
1150         z_stream stream;
1151         char hdr[128];
1152
1153         map = map_sha1_file_internal(sha1, &mapsize);
1154         if (!map) {
1155                 struct pack_entry e;
1156
1157                 if (!find_pack_entry(sha1, &e))
1158                         return error("unable to find %s", sha1_to_hex(sha1));
1159                 return packed_object_info(&e, type, sizep);
1160         }
1161         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1162                 status = error("unable to unpack %s header",
1163                                sha1_to_hex(sha1));
1164         if (parse_sha1_header(hdr, type, &size) < 0)
1165                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1166         else {
1167                 status = 0;
1168                 if (sizep)
1169                         *sizep = size;
1170         }
1171         inflateEnd(&stream);
1172         munmap(map, mapsize);
1173         return status;
1174 }
1175
1176 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1177 {
1178         struct pack_entry e;
1179
1180         if (!find_pack_entry(sha1, &e)) {
1181                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1182                 return NULL;
1183         }
1184         return unpack_entry(&e, type, size);
1185 }
1186
1187 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1188 {
1189         unsigned long mapsize;
1190         void *map, *buf;
1191         struct pack_entry e;
1192
1193         if (find_pack_entry(sha1, &e))
1194                 return read_packed_sha1(sha1, type, size);
1195         map = map_sha1_file_internal(sha1, &mapsize);
1196         if (map) {
1197                 buf = unpack_sha1_file(map, mapsize, type, size);
1198                 munmap(map, mapsize);
1199                 return buf;
1200         }
1201         return NULL;
1202 }
1203
1204 void *read_object_with_reference(const unsigned char *sha1,
1205                                  const char *required_type,
1206                                  unsigned long *size,
1207                                  unsigned char *actual_sha1_return)
1208 {
1209         char type[20];
1210         void *buffer;
1211         unsigned long isize;
1212         unsigned char actual_sha1[20];
1213
1214         memcpy(actual_sha1, sha1, 20);
1215         while (1) {
1216                 int ref_length = -1;
1217                 const char *ref_type = NULL;
1218
1219                 buffer = read_sha1_file(actual_sha1, type, &isize);
1220                 if (!buffer)
1221                         return NULL;
1222                 if (!strcmp(type, required_type)) {
1223                         *size = isize;
1224                         if (actual_sha1_return)
1225                                 memcpy(actual_sha1_return, actual_sha1, 20);
1226                         return buffer;
1227                 }
1228                 /* Handle references */
1229                 else if (!strcmp(type, "commit"))
1230                         ref_type = "tree ";
1231                 else if (!strcmp(type, "tag"))
1232                         ref_type = "object ";
1233                 else {
1234                         free(buffer);
1235                         return NULL;
1236                 }
1237                 ref_length = strlen(ref_type);
1238
1239                 if (memcmp(buffer, ref_type, ref_length) ||
1240                     get_sha1_hex(buffer + ref_length, actual_sha1)) {
1241                         free(buffer);
1242                         return NULL;
1243                 }
1244                 free(buffer);
1245                 /* Now we have the ID of the referred-to object in
1246                  * actual_sha1.  Check again. */
1247         }
1248 }
1249
1250 char *write_sha1_file_prepare(void *buf,
1251                               unsigned long len,
1252                               const char *type,
1253                               unsigned char *sha1,
1254                               unsigned char *hdr,
1255                               int *hdrlen)
1256 {
1257         SHA_CTX c;
1258
1259         /* Generate the header */
1260         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1261
1262         /* Sha1.. */
1263         SHA1_Init(&c);
1264         SHA1_Update(&c, hdr, *hdrlen);
1265         SHA1_Update(&c, buf, len);
1266         SHA1_Final(sha1, &c);
1267
1268         return sha1_file_name(sha1);
1269 }
1270
1271 /*
1272  * Link the tempfile to the final place, possibly creating the
1273  * last directory level as you do so.
1274  *
1275  * Returns the errno on failure, 0 on success.
1276  */
1277 static int link_temp_to_file(const char *tmpfile, char *filename)
1278 {
1279         int ret;
1280
1281         if (!link(tmpfile, filename))
1282                 return 0;
1283
1284         /*
1285          * Try to mkdir the last path component if that failed
1286          * with an ENOENT.
1287          *
1288          * Re-try the "link()" regardless of whether the mkdir
1289          * succeeds, since a race might mean that somebody
1290          * else succeeded.
1291          */
1292         ret = errno;
1293         if (ret == ENOENT) {
1294                 char *dir = strrchr(filename, '/');
1295                 if (dir) {
1296                         *dir = 0;
1297                         mkdir(filename, 0777);
1298                         if (adjust_shared_perm(filename))
1299                                 return -2;
1300                         *dir = '/';
1301                         if (!link(tmpfile, filename))
1302                                 return 0;
1303                         ret = errno;
1304                 }
1305         }
1306         return ret;
1307 }
1308
1309 /*
1310  * Move the just written object into its final resting place
1311  */
1312 int move_temp_to_file(const char *tmpfile, char *filename)
1313 {
1314         int ret = link_temp_to_file(tmpfile, filename);
1315
1316         /*
1317          * Coda hack - coda doesn't like cross-directory links,
1318          * so we fall back to a rename, which will mean that it
1319          * won't be able to check collisions, but that's not a
1320          * big deal.
1321          *
1322          * The same holds for FAT formatted media.
1323          *
1324          * When this succeeds, we just return 0. We have nothing
1325          * left to unlink.
1326          */
1327         if (ret && ret != EEXIST) {
1328                 if (!rename(tmpfile, filename))
1329                         return 0;
1330                 ret = errno;
1331         }
1332         unlink(tmpfile);
1333         if (ret) {
1334                 if (ret != EEXIST) {
1335                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1336                         return -1;
1337                 }
1338                 /* FIXME!!! Collision check here ? */
1339         }
1340
1341         return 0;
1342 }
1343
1344 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1345 {
1346         int size;
1347         unsigned char *compressed;
1348         z_stream stream;
1349         unsigned char sha1[20];
1350         char *filename;
1351         static char tmpfile[PATH_MAX];
1352         unsigned char hdr[50];
1353         int fd, hdrlen;
1354
1355         /* Normally if we have it in the pack then we do not bother writing
1356          * it out into .git/objects/??/?{38} file.
1357          */
1358         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1359         if (returnsha1)
1360                 memcpy(returnsha1, sha1, 20);
1361         if (has_sha1_file(sha1))
1362                 return 0;
1363         fd = open(filename, O_RDONLY);
1364         if (fd >= 0) {
1365                 /*
1366                  * FIXME!!! We might do collision checking here, but we'd
1367                  * need to uncompress the old file and check it. Later.
1368                  */
1369                 close(fd);
1370                 return 0;
1371         }
1372
1373         if (errno != ENOENT) {
1374                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1375                 return -1;
1376         }
1377
1378         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1379
1380         fd = mkstemp(tmpfile);
1381         if (fd < 0) {
1382                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1383                 return -1;
1384         }
1385
1386         /* Set it up */
1387         memset(&stream, 0, sizeof(stream));
1388         deflateInit(&stream, Z_BEST_COMPRESSION);
1389         size = deflateBound(&stream, len+hdrlen);
1390         compressed = xmalloc(size);
1391
1392         /* Compress it */
1393         stream.next_out = compressed;
1394         stream.avail_out = size;
1395
1396         /* First header.. */
1397         stream.next_in = hdr;
1398         stream.avail_in = hdrlen;
1399         while (deflate(&stream, 0) == Z_OK)
1400                 /* nothing */;
1401
1402         /* Then the data itself.. */
1403         stream.next_in = buf;
1404         stream.avail_in = len;
1405         while (deflate(&stream, Z_FINISH) == Z_OK)
1406                 /* nothing */;
1407         deflateEnd(&stream);
1408         size = stream.total_out;
1409
1410         if (write(fd, compressed, size) != size)
1411                 die("unable to write file");
1412         fchmod(fd, 0444);
1413         close(fd);
1414         free(compressed);
1415
1416         return move_temp_to_file(tmpfile, filename);
1417 }
1418
1419 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1420 {
1421         ssize_t size;
1422         unsigned long objsize;
1423         int posn = 0;
1424         void *map = map_sha1_file_internal(sha1, &objsize);
1425         void *buf = map;
1426         void *temp_obj = NULL;
1427         z_stream stream;
1428
1429         if (!buf) {
1430                 unsigned char *unpacked;
1431                 unsigned long len;
1432                 char type[20];
1433                 char hdr[50];
1434                 int hdrlen;
1435                 // need to unpack and recompress it by itself
1436                 unpacked = read_packed_sha1(sha1, type, &len);
1437
1438                 hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1439
1440                 /* Set it up */
1441                 memset(&stream, 0, sizeof(stream));
1442                 deflateInit(&stream, Z_BEST_COMPRESSION);
1443                 size = deflateBound(&stream, len + hdrlen);
1444                 temp_obj = buf = xmalloc(size);
1445
1446                 /* Compress it */
1447                 stream.next_out = buf;
1448                 stream.avail_out = size;
1449
1450                 /* First header.. */
1451                 stream.next_in = (void *)hdr;
1452                 stream.avail_in = hdrlen;
1453                 while (deflate(&stream, 0) == Z_OK)
1454                         /* nothing */;
1455
1456                 /* Then the data itself.. */
1457                 stream.next_in = unpacked;
1458                 stream.avail_in = len;
1459                 while (deflate(&stream, Z_FINISH) == Z_OK)
1460                         /* nothing */;
1461                 deflateEnd(&stream);
1462                 free(unpacked);
1463
1464                 objsize = stream.total_out;
1465         }
1466
1467         do {
1468                 size = write(fd, buf + posn, objsize - posn);
1469                 if (size <= 0) {
1470                         if (!size) {
1471                                 fprintf(stderr, "write closed\n");
1472                         } else {
1473                                 perror("write ");
1474                         }
1475                         return -1;
1476                 }
1477                 posn += size;
1478         } while (posn < objsize);
1479
1480         if (map)
1481                 munmap(map, objsize);
1482         if (temp_obj)
1483                 free(temp_obj);
1484
1485         return 0;
1486 }
1487
1488 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1489                        size_t bufsize, size_t *bufposn)
1490 {
1491         char tmpfile[PATH_MAX];
1492         int local;
1493         z_stream stream;
1494         unsigned char real_sha1[20];
1495         unsigned char discard[4096];
1496         int ret;
1497         SHA_CTX c;
1498
1499         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1500
1501         local = mkstemp(tmpfile);
1502         if (local < 0)
1503                 return error("Couldn't open %s for %s\n", tmpfile, sha1_to_hex(sha1));
1504
1505         memset(&stream, 0, sizeof(stream));
1506
1507         inflateInit(&stream);
1508
1509         SHA1_Init(&c);
1510
1511         do {
1512                 ssize_t size;
1513                 if (*bufposn) {
1514                         stream.avail_in = *bufposn;
1515                         stream.next_in = (unsigned char *) buffer;
1516                         do {
1517                                 stream.next_out = discard;
1518                                 stream.avail_out = sizeof(discard);
1519                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1520                                 SHA1_Update(&c, discard, sizeof(discard) -
1521                                             stream.avail_out);
1522                         } while (stream.avail_in && ret == Z_OK);
1523                         write(local, buffer, *bufposn - stream.avail_in);
1524                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1525                                 stream.avail_in);
1526                         *bufposn = stream.avail_in;
1527                         if (ret != Z_OK)
1528                                 break;
1529                 }
1530                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1531                 if (size <= 0) {
1532                         close(local);
1533                         unlink(tmpfile);
1534                         if (!size)
1535                                 return error("Connection closed?");
1536                         perror("Reading from connection");
1537                         return -1;
1538                 }
1539                 *bufposn += size;
1540         } while (1);
1541         inflateEnd(&stream);
1542
1543         close(local);
1544         SHA1_Final(real_sha1, &c);
1545         if (ret != Z_STREAM_END) {
1546                 unlink(tmpfile);
1547                 return error("File %s corrupted", sha1_to_hex(sha1));
1548         }
1549         if (memcmp(sha1, real_sha1, 20)) {
1550                 unlink(tmpfile);
1551                 return error("File %s has bad hash\n", sha1_to_hex(sha1));
1552         }
1553
1554         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1555 }
1556
1557 int has_pack_index(const unsigned char *sha1)
1558 {
1559         struct stat st;
1560         if (stat(sha1_pack_index_name(sha1), &st))
1561                 return 0;
1562         return 1;
1563 }
1564
1565 int has_pack_file(const unsigned char *sha1)
1566 {
1567         struct stat st;
1568         if (stat(sha1_pack_name(sha1), &st))
1569                 return 0;
1570         return 1;
1571 }
1572
1573 int has_sha1_pack(const unsigned char *sha1)
1574 {
1575         struct pack_entry e;
1576         return find_pack_entry(sha1, &e);
1577 }
1578
1579 int has_sha1_file(const unsigned char *sha1)
1580 {
1581         struct stat st;
1582         struct pack_entry e;
1583
1584         if (find_pack_entry(sha1, &e))
1585                 return 1;
1586         return find_sha1_file(sha1, &st) ? 1 : 0;
1587 }
1588
1589 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1590 {
1591         unsigned long size = 4096;
1592         char *buf = malloc(size);
1593         int iret, ret;
1594         unsigned long off = 0;
1595         unsigned char hdr[50];
1596         int hdrlen;
1597         do {
1598                 iret = read(fd, buf + off, size - off);
1599                 if (iret > 0) {
1600                         off += iret;
1601                         if (off == size) {
1602                                 size *= 2;
1603                                 buf = realloc(buf, size);
1604                         }
1605                 }
1606         } while (iret > 0);
1607         if (iret < 0) {
1608                 free(buf);
1609                 return -1;
1610         }
1611         if (!type)
1612                 type = "blob";
1613         if (write_object)
1614                 ret = write_sha1_file(buf, off, type, sha1);
1615         else {
1616                 write_sha1_file_prepare(buf, off, type, sha1, hdr, &hdrlen);
1617                 ret = 0;
1618         }
1619         free(buf);
1620         return ret;
1621 }
1622
1623 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1624 {
1625         unsigned long size = st->st_size;
1626         void *buf;
1627         int ret;
1628         unsigned char hdr[50];
1629         int hdrlen;
1630
1631         buf = "";
1632         if (size)
1633                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1634         close(fd);
1635         if (buf == MAP_FAILED)
1636                 return -1;
1637
1638         if (!type)
1639                 type = "blob";
1640         if (write_object)
1641                 ret = write_sha1_file(buf, size, type, sha1);
1642         else {
1643                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1644                 ret = 0;
1645         }
1646         if (size)
1647                 munmap(buf, size);
1648         return ret;
1649 }
1650
1651 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1652 {
1653         int fd;
1654         char *target;
1655
1656         switch (st->st_mode & S_IFMT) {
1657         case S_IFREG:
1658                 fd = open(path, O_RDONLY);
1659                 if (fd < 0)
1660                         return error("open(\"%s\"): %s", path,
1661                                      strerror(errno));
1662                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1663                         return error("%s: failed to insert into database",
1664                                      path);
1665                 break;
1666         case S_IFLNK:
1667                 target = xmalloc(st->st_size+1);
1668                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1669                         char *errstr = strerror(errno);
1670                         free(target);
1671                         return error("readlink(\"%s\"): %s", path,
1672                                      errstr);
1673                 }
1674                 if (!write_object) {
1675                         unsigned char hdr[50];
1676                         int hdrlen;
1677                         write_sha1_file_prepare(target, st->st_size, "blob",
1678                                                 sha1, hdr, &hdrlen);
1679                 } else if (write_sha1_file(target, st->st_size, "blob", sha1))
1680                         return error("%s: failed to insert into database",
1681                                      path);
1682                 free(target);
1683                 break;
1684         default:
1685                 return error("%s: unsupported file type", path);
1686         }
1687         return 0;
1688 }