git.oblomov.eu Git - git/blob - 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 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 const unsigned char null_sha1[20];
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 static unsigned hexval(char c)
  30 {
  31         if (c >= '0' && c <= '9')
  32                 return c - '0';
  33         if (c >= 'a' && c <= 'f')
  34                 return c - 'a' + 10;
  35         if (c >= 'A' && c <= 'F')
  36                 return c - 'A' + 10;
  37         return ~0;
  38 }
  39
  40 int get_sha1_hex(const char *hex, unsigned char *sha1)
  41 {
  42         int i;
  43         for (i = 0; i < 20; i++) {
  44                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  45                 if (val & ~0xff)
  46                         return -1;
  47                 *sha1++ = val;
  48                 hex += 2;
  49         }
  50         return 0;
  51 }
  52
  53 int safe_create_leading_directories(char *path)
  54 {
  55         char *pos = path;
  56         struct stat st;
  57
  58         if (*pos == '/')
  59                 pos++;
  60
  61         while (pos) {
  62                 pos = strchr(pos, '/');
  63                 if (!pos)
  64                         break;
  65                 *pos = 0;
  66                 if (!stat(path, &st)) {
  67                         /* path exists */
  68                         if (!S_ISDIR(st.st_mode)) {
  69                                 *pos = '/';
  70                                 return -3;
  71                         }
  72                 }
  73                 else if (mkdir(path, 0777)) {
  74                         *pos = '/';
  75                         return -1;
  76                 }
  77                 else if (adjust_shared_perm(path)) {
  78                         *pos = '/';
  79                         return -2;
  80                 }
  81                 *pos++ = '/';
  82         }
  83         return 0;
  84 }
  85
  86 char * sha1_to_hex(const unsigned char *sha1)
  87 {
  88         static int bufno;
  89         static char hexbuffer[4][50];
  90         static const char hex[] = "0123456789abcdef";
  91         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
  92         int i;
  93
  94         for (i = 0; i < 20; i++) {
  95                 unsigned int val = *sha1++;
  96                 *buf++ = hex[val >> 4];
  97                 *buf++ = hex[val & 0xf];
  98         }
  99         *buf = '\0';
 100
 101         return buffer;
 102 }
 103
 104 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 105 {
 106         int i;
 107         for (i = 0; i < 20; i++) {
 108                 static char hex[] = "0123456789abcdef";
 109                 unsigned int val = sha1[i];
 110                 char *pos = pathbuf + i*2 + (i > 0);
 111                 *pos++ = hex[val >> 4];
 112                 *pos = hex[val & 0xf];
 113         }
 114 }
 115
 116 /*
 117  * NOTE! This returns a statically allocated buffer, so you have to be
 118  * careful about using it. Do a "strdup()" if you need to save the
 119  * filename.
 120  *
 121  * Also note that this returns the location for creating.  Reading
 122  * SHA1 file can happen from any alternate directory listed in the
 123  * DB_ENVIRONMENT environment variable if it is not found in
 124  * the primary object database.
 125  */
 126 char *sha1_file_name(const unsigned char *sha1)
 127 {
 128         static char *name, *base;
 129
 130         if (!base) {
 131                 const char *sha1_file_directory = get_object_directory();
 132                 int len = strlen(sha1_file_directory);
 133                 base = xmalloc(len + 60);
 134                 memcpy(base, sha1_file_directory, len);
 135                 memset(base+len, 0, 60);
 136                 base[len] = '/';
 137                 base[len+3] = '/';
 138                 name = base + len + 1;
 139         }
 140         fill_sha1_path(name, sha1);
 141         return base;
 142 }
 143
 144 char *sha1_pack_name(const unsigned char *sha1)
 145 {
 146         static const char hex[] = "0123456789abcdef";
 147         static char *name, *base, *buf;
 148         int i;
 149
 150         if (!base) {
 151                 const char *sha1_file_directory = get_object_directory();
 152                 int len = strlen(sha1_file_directory);
 153                 base = xmalloc(len + 60);
 154                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 155                 name = base + len + 11;
 156         }
 157
 158         buf = name;
 159
 160         for (i = 0; i < 20; i++) {
 161                 unsigned int val = *sha1++;
 162                 *buf++ = hex[val >> 4];
 163                 *buf++ = hex[val & 0xf];
 164         }
 165
 166         return base;
 167 }
 168
 169 char *sha1_pack_index_name(const unsigned char *sha1)
 170 {
 171         static const char hex[] = "0123456789abcdef";
 172         static char *name, *base, *buf;
 173         int i;
 174
 175         if (!base) {
 176                 const char *sha1_file_directory = get_object_directory();
 177                 int len = strlen(sha1_file_directory);
 178                 base = xmalloc(len + 60);
 179                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 180                 name = base + len + 11;
 181         }
 182
 183         buf = name;
 184
 185         for (i = 0; i < 20; i++) {
 186                 unsigned int val = *sha1++;
 187                 *buf++ = hex[val >> 4];
 188                 *buf++ = hex[val & 0xf];
 189         }
 190
 191         return base;
 192 }
 193
 194 struct alternate_object_database *alt_odb_list;
 195 static struct alternate_object_database **alt_odb_tail;
 196
 197 static void read_info_alternates(const char * alternates, int depth);
 198
 199 /*
 200  * Prepare alternate object database registry.
 201  *
 202  * The variable alt_odb_list points at the list of struct
 203  * alternate_object_database.  The elements on this list come from
 204  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 205  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 206  * whose contents is similar to that environment variable but can be
 207  * LF separated.  Its base points at a statically allocated buffer that
 208  * contains "/the/directory/corresponding/to/.git/objects/...", while
 209  * its name points just after the slash at the end of ".git/objects/"
 210  * in the example above, and has enough space to hold 40-byte hex
 211  * SHA1, an extra slash for the first level indirection, and the
 212  * terminating NUL.
 213  */
 214 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 215 {
 216         struct stat st;
 217         const char *objdir = get_object_directory();
 218         struct alternate_object_database *ent;
 219         struct alternate_object_database *alt;
 220         /* 43 = 40-byte + 2 '/' + terminating NUL */
 221         int pfxlen = len;
 222         int entlen = pfxlen + 43;
 223         int base_len = -1;
 224
 225         if (*entry != '/' && relative_base) {
 226                 /* Relative alt-odb */
 227                 if (base_len < 0)
 228                         base_len = strlen(relative_base) + 1;
 229                 entlen += base_len;
 230                 pfxlen += base_len;
 231         }
 232         ent = xmalloc(sizeof(*ent) + entlen);
 233
 234         if (*entry != '/' && relative_base) {
 235                 memcpy(ent->base, relative_base, base_len - 1);
 236                 ent->base[base_len - 1] = '/';
 237                 memcpy(ent->base + base_len, entry, len);
 238         }
 239         else
 240                 memcpy(ent->base, entry, pfxlen);
 241
 242         ent->name = ent->base + pfxlen + 1;
 243         ent->base[pfxlen + 3] = '/';
 244         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 245
 246         /* Detect cases where alternate disappeared */
 247         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 248                 error("object directory %s does not exist; "
 249                       "check .git/objects/info/alternates.",
 250                       ent->base);
 251                 free(ent);
 252                 return -1;
 253         }
 254
 255         /* Prevent the common mistake of listing the same
 256          * thing twice, or object directory itself.
 257          */
 258         for (alt = alt_odb_list; alt; alt = alt->next) {
 259                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 260                         free(ent);
 261                         return -1;
 262                 }
 263         }
 264         if (!memcmp(ent->base, objdir, pfxlen)) {
 265                 free(ent);
 266                 return -1;
 267         }
 268
 269         /* add the alternate entry */
 270         *alt_odb_tail = ent;
 271         alt_odb_tail = &(ent->next);
 272         ent->next = NULL;
 273
 274         /* recursively add alternates */
 275         read_info_alternates(ent->base, depth + 1);
 276
 277         ent->base[pfxlen] = '/';
 278
 279         return 0;
 280 }
 281
 282 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 283                                  const char *relative_base, int depth)
 284 {
 285         const char *cp, *last;
 286
 287         if (depth > 5) {
 288                 error("%s: ignoring alternate object stores, nesting too deep.",
 289                                 relative_base);
 290                 return;
 291         }
 292
 293         last = alt;
 294         while (last < ep) {
 295                 cp = last;
 296                 if (cp < ep && *cp == '#') {
 297                         while (cp < ep && *cp != sep)
 298                                 cp++;
 299                         last = cp + 1;
 300                         continue;
 301                 }
 302                 while (cp < ep && *cp != sep)
 303                         cp++;
 304                 if (last != cp) {
 305                         if ((*last != '/') && depth) {
 306                                 error("%s: ignoring relative alternate object store %s",
 307                                                 relative_base, last);
 308                         } else {
 309                                 link_alt_odb_entry(last, cp - last,
 310                                                 relative_base, depth);
 311                         }
 312                 }
 313                 while (cp < ep && *cp == sep)
 314                         cp++;
 315                 last = cp;
 316         }
 317 }
 318
 319 static void read_info_alternates(const char * relative_base, int depth)
 320 {
 321         char *map;
 322         struct stat st;
 323         char path[PATH_MAX];
 324         int fd;
 325
 326         sprintf(path, "%s/info/alternates", relative_base);
 327         fd = open(path, O_RDONLY);
 328         if (fd < 0)
 329                 return;
 330         if (fstat(fd, &st) || (st.st_size == 0)) {
 331                 close(fd);
 332                 return;
 333         }
 334         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 335         close(fd);
 336         if (map == MAP_FAILED)
 337                 return;
 338
 339         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 340
 341         munmap(map, st.st_size);
 342 }
 343
 344 void prepare_alt_odb(void)
 345 {
 346         const char *alt;
 347
 348         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 349         if (!alt) alt = "";
 350
 351         if (alt_odb_tail)
 352                 return;
 353         alt_odb_tail = &alt_odb_list;
 354         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 355
 356         read_info_alternates(get_object_directory(), 0);
 357 }
 358
 359 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 360 {
 361         char *name = sha1_file_name(sha1);
 362         struct alternate_object_database *alt;
 363
 364         if (!stat(name, st))
 365                 return name;
 366         prepare_alt_odb();
 367         for (alt = alt_odb_list; alt; alt = alt->next) {
 368                 name = alt->name;
 369                 fill_sha1_path(name, sha1);
 370                 if (!stat(alt->base, st))
 371                         return alt->base;
 372         }
 373         return NULL;
 374 }
 375
 376 #define PACK_MAX_SZ (1<<26)
 377 static int pack_used_ctr;
 378 static unsigned long pack_mapped;
 379 struct packed_git *packed_git;
 380
 381 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 382                                 void **idx_map_)
 383 {
 384         void *idx_map;
 385         unsigned int *index;
 386         unsigned long idx_size;
 387         int nr, i;
 388         int fd = open(path, O_RDONLY);
 389         struct stat st;
 390         if (fd < 0)
 391                 return -1;
 392         if (fstat(fd, &st)) {
 393                 close(fd);
 394                 return -1;
 395         }
 396         idx_size = st.st_size;
 397         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 398         close(fd);
 399         if (idx_map == MAP_FAILED)
 400                 return -1;
 401
 402         index = idx_map;
 403         *idx_map_ = idx_map;
 404         *idx_size_ = idx_size;
 405
 406         /* check index map */
 407         if (idx_size < 4*256 + 20 + 20)
 408                 return error("index file too small");
 409         nr = 0;
 410         for (i = 0; i < 256; i++) {
 411                 unsigned int n = ntohl(index[i]);
 412                 if (n < nr)
 413                         return error("non-monotonic index");
 414                 nr = n;
 415         }
 416
 417         /*
 418          * Total size:
 419          *  - 256 index entries 4 bytes each
 420          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 421          *  - 20-byte SHA1 of the packfile
 422          *  - 20-byte SHA1 file checksum
 423          */
 424         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 425                 return error("wrong index file size");
 426
 427         return 0;
 428 }
 429
 430 static int unuse_one_packed_git(void)
 431 {
 432         struct packed_git *p, *lru = NULL;
 433
 434         for (p = packed_git; p; p = p->next) {
 435                 if (p->pack_use_cnt || !p->pack_base)
 436                         continue;
 437                 if (!lru || p->pack_last_used < lru->pack_last_used)
 438                         lru = p;
 439         }
 440         if (!lru)
 441                 return 0;
 442         munmap(lru->pack_base, lru->pack_size);
 443         lru->pack_base = NULL;
 444         return 1;
 445 }
 446
 447 void unuse_packed_git(struct packed_git *p)
 448 {
 449         p->pack_use_cnt--;
 450 }
 451
 452 int use_packed_git(struct packed_git *p)
 453 {
 454         if (!p->pack_size) {
 455                 struct stat st;
 456                 /* We created the struct before we had the pack */
 457                 stat(p->pack_name, &st);
 458                 if (!S_ISREG(st.st_mode))
 459                         die("packfile %s not a regular file", p->pack_name);
 460                 p->pack_size = st.st_size;
 461         }
 462         if (!p->pack_base) {
 463                 int fd;
 464                 struct stat st;
 465                 void *map;
 466                 struct pack_header *hdr;
 467
 468                 pack_mapped += p->pack_size;
 469                 while (PACK_MAX_SZ < pack_mapped && unuse_one_packed_git())
 470                         ; /* nothing */
 471                 fd = open(p->pack_name, O_RDONLY);
 472                 if (fd < 0)
 473                         die("packfile %s cannot be opened", p->pack_name);
 474                 if (fstat(fd, &st)) {
 475                         close(fd);
 476                         die("packfile %s cannot be opened", p->pack_name);
 477                 }
 478                 if (st.st_size != p->pack_size)
 479                         die("packfile %s size mismatch.", p->pack_name);
 480                 map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
 481                 close(fd);
 482                 if (map == MAP_FAILED)
 483                         die("packfile %s cannot be mapped.", p->pack_name);
 484                 p->pack_base = map;
 485
 486                 /* Check if we understand this pack file.  If we don't we're
 487                  * likely too old to handle it.
 488                  */
 489                 hdr = map;
 490                 if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 491                         die("packfile %s isn't actually a pack.", p->pack_name);
 492                 if (!pack_version_ok(hdr->hdr_version))
 493                         die("packfile %s is version %i and not supported"
 494                                 " (try upgrading GIT to a newer version)",
 495                                 p->pack_name, ntohl(hdr->hdr_version));
 496
 497                 /* Check if the pack file matches with the index file.
 498                  * this is cheap.
 499                  */
 500                 if (hashcmp((unsigned char *)(p->index_base) +
 501                             p->index_size - 40,
 502                             (unsigned char *)p->pack_base +
 503                             p->pack_size - 20)) {
 504                         die("packfile %s does not match index.", p->pack_name);
 505                 }
 506         }
 507         p->pack_last_used = pack_used_ctr++;
 508         p->pack_use_cnt++;
 509         return 0;
 510 }
 511
 512 struct packed_git *add_packed_git(char *path, int path_len, int local)
 513 {
 514         struct stat st;
 515         struct packed_git *p;
 516         unsigned long idx_size;
 517         void *idx_map;
 518         unsigned char sha1[20];
 519
 520         if (check_packed_git_idx(path, &idx_size, &idx_map))
 521                 return NULL;
 522
 523         /* do we have a corresponding .pack file? */
 524         strcpy(path + path_len - 4, ".pack");
 525         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 526                 munmap(idx_map, idx_size);
 527                 return NULL;
 528         }
 529         /* ok, it looks sane as far as we can check without
 530          * actually mapping the pack file.
 531          */
 532         p = xmalloc(sizeof(*p) + path_len + 2);
 533         strcpy(p->pack_name, path);
 534         p->index_size = idx_size;
 535         p->pack_size = st.st_size;
 536         p->index_base = idx_map;
 537         p->next = NULL;
 538         p->pack_base = NULL;
 539         p->pack_last_used = 0;
 540         p->pack_use_cnt = 0;
 541         p->pack_local = local;
 542         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 543                 hashcpy(p->sha1, sha1);
 544         return p;
 545 }
 546
 547 struct packed_git *parse_pack_index(unsigned char *sha1)
 548 {
 549         char *path = sha1_pack_index_name(sha1);
 550         return parse_pack_index_file(sha1, path);
 551 }
 552
 553 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 554 {
 555         struct packed_git *p;
 556         unsigned long idx_size;
 557         void *idx_map;
 558         char *path;
 559
 560         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 561                 return NULL;
 562
 563         path = sha1_pack_name(sha1);
 564
 565         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 566         strcpy(p->pack_name, path);
 567         p->index_size = idx_size;
 568         p->pack_size = 0;
 569         p->index_base = idx_map;
 570         p->next = NULL;
 571         p->pack_base = NULL;
 572         p->pack_last_used = 0;
 573         p->pack_use_cnt = 0;
 574         hashcpy(p->sha1, sha1);
 575         return p;
 576 }
 577
 578 void install_packed_git(struct packed_git *pack)
 579 {
 580         pack->next = packed_git;
 581         packed_git = pack;
 582 }
 583
 584 static void prepare_packed_git_one(char *objdir, int local)
 585 {
 586         char path[PATH_MAX];
 587         int len;
 588         DIR *dir;
 589         struct dirent *de;
 590
 591         sprintf(path, "%s/pack", objdir);
 592         len = strlen(path);
 593         dir = opendir(path);
 594         if (!dir) {
 595                 if (errno != ENOENT)
 596                         error("unable to open object pack directory: %s: %s",
 597                               path, strerror(errno));
 598                 return;
 599         }
 600         path[len++] = '/';
 601         while ((de = readdir(dir)) != NULL) {
 602                 int namelen = strlen(de->d_name);
 603                 struct packed_git *p;
 604
 605                 if (!has_extension(de->d_name, ".idx"))
 606                         continue;
 607
 608                 /* we have .idx.  Is it a file we can map? */
 609                 strcpy(path + len, de->d_name);
 610                 for (p = packed_git; p; p = p->next) {
 611                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 612                                 break;
 613                 }
 614                 if (p)
 615                         continue;
 616                 p = add_packed_git(path, len + namelen, local);
 617                 if (!p)
 618                         continue;
 619                 p->next = packed_git;
 620                 packed_git = p;
 621         }
 622         closedir(dir);
 623 }
 624
 625 static int prepare_packed_git_run_once = 0;
 626 void prepare_packed_git(void)
 627 {
 628         struct alternate_object_database *alt;
 629
 630         if (prepare_packed_git_run_once)
 631                 return;
 632         prepare_packed_git_one(get_object_directory(), 1);
 633         prepare_alt_odb();
 634         for (alt = alt_odb_list; alt; alt = alt->next) {
 635                 alt->name[-1] = 0;
 636                 prepare_packed_git_one(alt->base, 0);
 637                 alt->name[-1] = '/';
 638         }
 639         prepare_packed_git_run_once = 1;
 640 }
 641
 642 static void reprepare_packed_git(void)
 643 {
 644         prepare_packed_git_run_once = 0;
 645         prepare_packed_git();
 646 }
 647
 648 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 649 {
 650         char header[100];
 651         unsigned char real_sha1[20];
 652         SHA_CTX c;
 653
 654         SHA1_Init(&c);
 655         SHA1_Update(&c, header, 1+sprintf(header, "%s %lu", type, size));
 656         SHA1_Update(&c, map, size);
 657         SHA1_Final(real_sha1, &c);
 658         return hashcmp(sha1, real_sha1) ? -1 : 0;
 659 }
 660
 661 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 662 {
 663         struct stat st;
 664         void *map;
 665         int fd;
 666         char *filename = find_sha1_file(sha1, &st);
 667
 668         if (!filename) {
 669                 return NULL;
 670         }
 671
 672         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 673         if (fd < 0) {
 674                 /* See if it works without O_NOATIME */
 675                 switch (sha1_file_open_flag) {
 676                 default:
 677                         fd = open(filename, O_RDONLY);
 678                         if (fd >= 0)
 679                                 break;
 680                 /* Fallthrough */
 681                 case 0:
 682                         return NULL;
 683                 }
 684
 685                 /* If it failed once, it will probably fail again.
 686                  * Stop using O_NOATIME
 687                  */
 688                 sha1_file_open_flag = 0;
 689         }
 690         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 691         close(fd);
 692         if (map == MAP_FAILED)
 693                 return NULL;
 694         *size = st.st_size;
 695         return map;
 696 }
 697
 698 int legacy_loose_object(unsigned char *map)
 699 {
 700         unsigned int word;
 701
 702         /*
 703          * Is it a zlib-compressed buffer? If so, the first byte
 704          * must be 0x78 (15-bit window size, deflated), and the
 705          * first 16-bit word is evenly divisible by 31
 706          */
 707         word = (map[0] << 8) + map[1];
 708         if (map[0] == 0x78 && !(word % 31))
 709                 return 1;
 710         else
 711                 return 0;
 712 }
 713
 714 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 715 {
 716         unsigned char c;
 717         unsigned int bits;
 718         unsigned long size;
 719         static const char *typename[8] = {
 720                 NULL,   /* OBJ_EXT */
 721                 "commit", "tree", "blob", "tag",
 722                 NULL, NULL, NULL
 723         };
 724         const char *type;
 725
 726         /* Get the data stream */
 727         memset(stream, 0, sizeof(*stream));
 728         stream->next_in = map;
 729         stream->avail_in = mapsize;
 730         stream->next_out = buffer;
 731         stream->avail_out = bufsiz;
 732
 733         if (legacy_loose_object(map)) {
 734                 inflateInit(stream);
 735                 return inflate(stream, 0);
 736         }
 737
 738         c = *map++;
 739         mapsize--;
 740         type = typename[(c >> 4) & 7];
 741         if (!type)
 742                 return -1;
 743
 744         bits = 4;
 745         size = c & 0xf;
 746         while ((c & 0x80)) {
 747                 if (bits >= 8*sizeof(long))
 748                         return -1;
 749                 c = *map++;
 750                 size += (c & 0x7f) << bits;
 751                 bits += 7;
 752                 mapsize--;
 753         }
 754
 755         /* Set up the stream for the rest.. */
 756         stream->next_in = map;
 757         stream->avail_in = mapsize;
 758         inflateInit(stream);
 759
 760         /* And generate the fake traditional header */
 761         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu", type, size);
 762         return 0;
 763 }
 764
 765 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 766 {
 767         int bytes = strlen(buffer) + 1;
 768         unsigned char *buf = xmalloc(1+size);
 769         unsigned long n;
 770
 771         n = stream->total_out - bytes;
 772         if (n > size)
 773                 n = size;
 774         memcpy(buf, (char *) buffer + bytes, n);
 775         bytes = n;
 776         if (bytes < size) {
 777                 stream->next_out = buf + bytes;
 778                 stream->avail_out = size - bytes;
 779                 while (inflate(stream, Z_FINISH) == Z_OK)
 780                         /* nothing */;
 781         }
 782         buf[size] = 0;
 783         inflateEnd(stream);
 784         return buf;
 785 }
 786
 787 /*
 788  * We used to just use "sscanf()", but that's actually way
 789  * too permissive for what we want to check. So do an anal
 790  * object header parse by hand.
 791  */
 792 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 793 {
 794         int i;
 795         unsigned long size;
 796
 797         /*
 798          * The type can be at most ten bytes (including the
 799          * terminating '\0' that we add), and is followed by
 800          * a space.
 801          */
 802         i = 10;
 803         for (;;) {
 804                 char c = *hdr++;
 805                 if (c == ' ')
 806                         break;
 807                 if (!--i)
 808                         return -1;
 809                 *type++ = c;
 810         }
 811         *type = 0;
 812
 813         /*
 814          * The length must follow immediately, and be in canonical
 815          * decimal format (ie "010" is not valid).
 816          */
 817         size = *hdr++ - '0';
 818         if (size > 9)
 819                 return -1;
 820         if (size) {
 821                 for (;;) {
 822                         unsigned long c = *hdr - '0';
 823                         if (c > 9)
 824                                 break;
 825                         hdr++;
 826                         size = size * 10 + c;
 827                 }
 828         }
 829         *sizep = size;
 830
 831         /*
 832          * The length must be followed by a zero byte
 833          */
 834         return *hdr ? -1 : 0;
 835 }
 836
 837 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 838 {
 839         int ret;
 840         z_stream stream;
 841         char hdr[8192];
 842
 843         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 844         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 845                 return NULL;
 846
 847         return unpack_sha1_rest(&stream, hdr, *size);
 848 }
 849
 850 /* forward declaration for a mutually recursive function */
 851 static int packed_object_info(struct pack_entry *entry,
 852                               char *type, unsigned long *sizep);
 853
 854 static int packed_delta_info(unsigned char *base_sha1,
 855                              unsigned long delta_size,
 856                              unsigned long left,
 857                              char *type,
 858                              unsigned long *sizep,
 859                              struct packed_git *p)
 860 {
 861         struct pack_entry base_ent;
 862
 863         if (left < 20)
 864                 die("truncated pack file");
 865
 866         /* The base entry _must_ be in the same pack */
 867         if (!find_pack_entry_one(base_sha1, &base_ent, p))
 868                 die("failed to find delta-pack base object %s",
 869                     sha1_to_hex(base_sha1));
 870
 871         /* We choose to only get the type of the base object and
 872          * ignore potentially corrupt pack file that expects the delta
 873          * based on a base with a wrong size.  This saves tons of
 874          * inflate() calls.
 875          */
 876
 877         if (packed_object_info(&base_ent, type, NULL))
 878                 die("cannot get info for delta-pack base");
 879
 880         if (sizep) {
 881                 const unsigned char *data;
 882                 unsigned char delta_head[64];
 883                 unsigned long result_size;
 884                 z_stream stream;
 885                 int st;
 886
 887                 memset(&stream, 0, sizeof(stream));
 888
 889                 data = stream.next_in = base_sha1 + 20;
 890                 stream.avail_in = left - 20;
 891                 stream.next_out = delta_head;
 892                 stream.avail_out = sizeof(delta_head);
 893
 894                 inflateInit(&stream);
 895                 st = inflate(&stream, Z_FINISH);
 896                 inflateEnd(&stream);
 897                 if ((st != Z_STREAM_END) &&
 898                     stream.total_out != sizeof(delta_head))
 899                         die("delta data unpack-initial failed");
 900
 901                 /* Examine the initial part of the delta to figure out
 902                  * the result size.
 903                  */
 904                 data = delta_head;
 905
 906                 /* ignore base size */
 907                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 908
 909                 /* Read the result size */
 910                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 911                 *sizep = result_size;
 912         }
 913         return 0;
 914 }
 915
 916 static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
 917         enum object_type *type, unsigned long *sizep)
 918 {
 919         unsigned shift;
 920         unsigned char *pack, c;
 921         unsigned long size;
 922
 923         if (offset >= p->pack_size)
 924                 die("object offset outside of pack file");
 925
 926         pack =  (unsigned char *) p->pack_base + offset;
 927         c = *pack++;
 928         offset++;
 929         *type = (c >> 4) & 7;
 930         size = c & 15;
 931         shift = 4;
 932         while (c & 0x80) {
 933                 if (offset >= p->pack_size)
 934                         die("object offset outside of pack file");
 935                 c = *pack++;
 936                 offset++;
 937                 size += (c & 0x7f) << shift;
 938                 shift += 7;
 939         }
 940         *sizep = size;
 941         return offset;
 942 }
 943
 944 int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
 945                            unsigned char *base, unsigned long *sizep,
 946                            enum object_type *kindp)
 947 {
 948         unsigned long ptr;
 949         int status = -1;
 950
 951         use_packed_git(p);
 952         ptr = offset;
 953         ptr = unpack_object_header(p, ptr, kindp, sizep);
 954         if (*kindp != OBJ_DELTA)
 955                 goto done;
 956         hashcpy(base, (unsigned char *) p->pack_base + ptr);
 957         status = 0;
 958  done:
 959         unuse_packed_git(p);
 960         return status;
 961 }
 962
 963 void packed_object_info_detail(struct pack_entry *e,
 964                                char *type,
 965                                unsigned long *size,
 966                                unsigned long *store_size,
 967                                unsigned int *delta_chain_length,
 968                                unsigned char *base_sha1)
 969 {
 970         struct packed_git *p = e->p;
 971         unsigned long offset;
 972         unsigned char *pack;
 973         enum object_type kind;
 974
 975         offset = unpack_object_header(p, e->offset, &kind, size);
 976         pack = (unsigned char *) p->pack_base + offset;
 977         if (kind != OBJ_DELTA)
 978                 *delta_chain_length = 0;
 979         else {
 980                 unsigned int chain_length = 0;
 981                 if (p->pack_size <= offset + 20)
 982                         die("pack file %s records an incomplete delta base",
 983                             p->pack_name);
 984                 hashcpy(base_sha1, pack);
 985                 do {
 986                         struct pack_entry base_ent;
 987                         unsigned long junk;
 988
 989                         find_pack_entry_one(pack, &base_ent, p);
 990                         offset = unpack_object_header(p, base_ent.offset,
 991                                                       &kind, &junk);
 992                         pack = (unsigned char *) p->pack_base + offset;
 993                         chain_length++;
 994                 } while (kind == OBJ_DELTA);
 995                 *delta_chain_length = chain_length;
 996         }
 997         switch (kind) {
 998         case OBJ_COMMIT:
 999         case OBJ_TREE:
1000         case OBJ_BLOB:
1001         case OBJ_TAG:
1002                 strcpy(type, type_names[kind]);
1003                 break;
1004         default:
1005                 die("corrupted pack file %s containing object of kind %d",
1006                     p->pack_name, kind);
1007         }
1008         *store_size = 0; /* notyet */
1009 }
1010
1011 static int packed_object_info(struct pack_entry *entry,
1012                               char *type, unsigned long *sizep)
1013 {
1014         struct packed_git *p = entry->p;
1015         unsigned long offset, size, left;
1016         unsigned char *pack;
1017         enum object_type kind;
1018         int retval;
1019
1020         if (use_packed_git(p))
1021                 die("cannot map packed file");
1022
1023         offset = unpack_object_header(p, entry->offset, &kind, &size);
1024         pack = (unsigned char *) p->pack_base + offset;
1025         left = p->pack_size - offset;
1026
1027         switch (kind) {
1028         case OBJ_DELTA:
1029                 retval = packed_delta_info(pack, size, left, type, sizep, p);
1030                 unuse_packed_git(p);
1031                 return retval;
1032         case OBJ_COMMIT:
1033         case OBJ_TREE:
1034         case OBJ_BLOB:
1035         case OBJ_TAG:
1036                 strcpy(type, type_names[kind]);
1037                 break;
1038         default:
1039                 die("corrupted pack file %s containing object of kind %d",
1040                     p->pack_name, kind);
1041         }
1042         if (sizep)
1043                 *sizep = size;
1044         unuse_packed_git(p);
1045         return 0;
1046 }
1047
1048 static void *unpack_compressed_entry(unsigned char *data,
1049                                     unsigned long size,
1050                                     unsigned long left)
1051 {
1052         int st;
1053         z_stream stream;
1054         unsigned char *buffer;
1055
1056         buffer = xmalloc(size + 1);
1057         buffer[size] = 0;
1058         memset(&stream, 0, sizeof(stream));
1059         stream.next_in = data;
1060         stream.avail_in = left;
1061         stream.next_out = buffer;
1062         stream.avail_out = size;
1063
1064         inflateInit(&stream);
1065         st = inflate(&stream, Z_FINISH);
1066         inflateEnd(&stream);
1067         if ((st != Z_STREAM_END) || stream.total_out != size) {
1068                 free(buffer);
1069                 return NULL;
1070         }
1071
1072         return buffer;
1073 }
1074
1075 static void *unpack_delta_entry(unsigned char *base_sha1,
1076                                 unsigned long delta_size,
1077                                 unsigned long left,
1078                                 char *type,
1079                                 unsigned long *sizep,
1080                                 struct packed_git *p)
1081 {
1082         struct pack_entry base_ent;
1083         void *delta_data, *result, *base;
1084         unsigned long result_size, base_size;
1085
1086         if (left < 20)
1087                 die("truncated pack file");
1088
1089         /* The base entry _must_ be in the same pack */
1090         if (!find_pack_entry_one(base_sha1, &base_ent, p))
1091                 die("failed to find delta-pack base object %s",
1092                     sha1_to_hex(base_sha1));
1093         base = unpack_entry_gently(&base_ent, type, &base_size);
1094         if (!base)
1095                 die("failed to read delta-pack base object %s",
1096                     sha1_to_hex(base_sha1));
1097
1098         delta_data = unpack_compressed_entry(base_sha1 + 20,
1099                              delta_size, left - 20);
1100         result = patch_delta(base, base_size,
1101                              delta_data, delta_size,
1102                              &result_size);
1103         if (!result)
1104                 die("failed to apply delta");
1105         free(delta_data);
1106         free(base);
1107         *sizep = result_size;
1108         return result;
1109 }
1110
1111 static void *unpack_entry(struct pack_entry *entry,
1112                           char *type, unsigned long *sizep)
1113 {
1114         struct packed_git *p = entry->p;
1115         void *retval;
1116
1117         if (use_packed_git(p))
1118                 die("cannot map packed file");
1119         retval = unpack_entry_gently(entry, type, sizep);
1120         unuse_packed_git(p);
1121         if (!retval)
1122                 die("corrupted pack file %s", p->pack_name);
1123         return retval;
1124 }
1125
1126 /* The caller is responsible for use_packed_git()/unuse_packed_git() pair */
1127 void *unpack_entry_gently(struct pack_entry *entry,
1128                           char *type, unsigned long *sizep)
1129 {
1130         struct packed_git *p = entry->p;
1131         unsigned long offset, size, left;
1132         unsigned char *pack;
1133         enum object_type kind;
1134
1135         offset = unpack_object_header(p, entry->offset, &kind, &size);
1136         pack = (unsigned char *) p->pack_base + offset;
1137         left = p->pack_size - offset;
1138         switch (kind) {
1139         case OBJ_DELTA:
1140                 return unpack_delta_entry(pack, size, left, type, sizep, p);
1141         case OBJ_COMMIT:
1142         case OBJ_TREE:
1143         case OBJ_BLOB:
1144         case OBJ_TAG:
1145                 strcpy(type, type_names[kind]);
1146                 *sizep = size;
1147                 return unpack_compressed_entry(pack, size, left);
1148         default:
1149                 return NULL;
1150         }
1151 }
1152
1153 int num_packed_objects(const struct packed_git *p)
1154 {
1155         /* See check_packed_git_idx() */
1156         return (p->index_size - 20 - 20 - 4*256) / 24;
1157 }
1158
1159 int nth_packed_object_sha1(const struct packed_git *p, int n,
1160                            unsigned char* sha1)
1161 {
1162         void *index = p->index_base + 256;
1163         if (n < 0 || num_packed_objects(p) <= n)
1164                 return -1;
1165         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1166         return 0;
1167 }
1168
1169 int find_pack_entry_one(const unsigned char *sha1,
1170                         struct pack_entry *e, struct packed_git *p)
1171 {
1172         unsigned int *level1_ofs = p->index_base;
1173         int hi = ntohl(level1_ofs[*sha1]);
1174         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1175         void *index = p->index_base + 256;
1176
1177         do {
1178                 int mi = (lo + hi) / 2;
1179                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1180                 if (!cmp) {
1181                         e->offset = ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1182                         hashcpy(e->sha1, sha1);
1183                         e->p = p;
1184                         return 1;
1185                 }
1186                 if (cmp > 0)
1187                         hi = mi;
1188                 else
1189                         lo = mi+1;
1190         } while (lo < hi);
1191         return 0;
1192 }
1193
1194 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1195 {
1196         struct packed_git *p;
1197         prepare_packed_git();
1198
1199         for (p = packed_git; p; p = p->next) {
1200                 if (find_pack_entry_one(sha1, e, p))
1201                         return 1;
1202         }
1203         return 0;
1204 }
1205
1206 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1207                                   struct packed_git *packs)
1208 {
1209         struct packed_git *p;
1210         struct pack_entry e;
1211
1212         for (p = packs; p; p = p->next) {
1213                 if (find_pack_entry_one(sha1, &e, p))
1214                         return p;
1215         }
1216         return NULL;
1217
1218 }
1219
1220 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1221 {
1222         int status;
1223         unsigned long mapsize, size;
1224         void *map;
1225         z_stream stream;
1226         char hdr[128];
1227
1228         map = map_sha1_file(sha1, &mapsize);
1229         if (!map) {
1230                 struct pack_entry e;
1231
1232                 if (find_pack_entry(sha1, &e))
1233                         return packed_object_info(&e, type, sizep);
1234                 reprepare_packed_git();
1235                 if (find_pack_entry(sha1, &e))
1236                         return packed_object_info(&e, type, sizep);
1237                 return error("unable to find %s", sha1_to_hex(sha1));
1238         }
1239         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1240                 status = error("unable to unpack %s header",
1241                                sha1_to_hex(sha1));
1242         if (parse_sha1_header(hdr, type, &size) < 0)
1243                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1244         else {
1245                 status = 0;
1246                 if (sizep)
1247                         *sizep = size;
1248         }
1249         inflateEnd(&stream);
1250         munmap(map, mapsize);
1251         return status;
1252 }
1253
1254 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1255 {
1256         struct pack_entry e;
1257
1258         if (!find_pack_entry(sha1, &e)) {
1259                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1260                 return NULL;
1261         }
1262         return unpack_entry(&e, type, size);
1263 }
1264
1265 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1266 {
1267         unsigned long mapsize;
1268         void *map, *buf;
1269         struct pack_entry e;
1270
1271         if (find_pack_entry(sha1, &e))
1272                 return read_packed_sha1(sha1, type, size);
1273         map = map_sha1_file(sha1, &mapsize);
1274         if (map) {
1275                 buf = unpack_sha1_file(map, mapsize, type, size);
1276                 munmap(map, mapsize);
1277                 return buf;
1278         }
1279         reprepare_packed_git();
1280         if (find_pack_entry(sha1, &e))
1281                 return read_packed_sha1(sha1, type, size);
1282         return NULL;
1283 }
1284
1285 void *read_object_with_reference(const unsigned char *sha1,
1286                                  const char *required_type,
1287                                  unsigned long *size,
1288                                  unsigned char *actual_sha1_return)
1289 {
1290         char type[20];
1291         void *buffer;
1292         unsigned long isize;
1293         unsigned char actual_sha1[20];
1294
1295         hashcpy(actual_sha1, sha1);
1296         while (1) {
1297                 int ref_length = -1;
1298                 const char *ref_type = NULL;
1299
1300                 buffer = read_sha1_file(actual_sha1, type, &isize);
1301                 if (!buffer)
1302                         return NULL;
1303                 if (!strcmp(type, required_type)) {
1304                         *size = isize;
1305                         if (actual_sha1_return)
1306                                 hashcpy(actual_sha1_return, actual_sha1);
1307                         return buffer;
1308                 }
1309                 /* Handle references */
1310                 else if (!strcmp(type, commit_type))
1311                         ref_type = "tree ";
1312                 else if (!strcmp(type, tag_type))
1313                         ref_type = "object ";
1314                 else {
1315                         free(buffer);
1316                         return NULL;
1317                 }
1318                 ref_length = strlen(ref_type);
1319
1320                 if (memcmp(buffer, ref_type, ref_length) ||
1321                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1322                         free(buffer);
1323                         return NULL;
1324                 }
1325                 free(buffer);
1326                 /* Now we have the ID of the referred-to object in
1327                  * actual_sha1.  Check again. */
1328         }
1329 }
1330
1331 char *write_sha1_file_prepare(void *buf,
1332                               unsigned long len,
1333                               const char *type,
1334                               unsigned char *sha1,
1335                               unsigned char *hdr,
1336                               int *hdrlen)
1337 {
1338         SHA_CTX c;
1339
1340         /* Generate the header */
1341         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1342
1343         /* Sha1.. */
1344         SHA1_Init(&c);
1345         SHA1_Update(&c, hdr, *hdrlen);
1346         SHA1_Update(&c, buf, len);
1347         SHA1_Final(sha1, &c);
1348
1349         return sha1_file_name(sha1);
1350 }
1351
1352 /*
1353  * Link the tempfile to the final place, possibly creating the
1354  * last directory level as you do so.
1355  *
1356  * Returns the errno on failure, 0 on success.
1357  */
1358 static int link_temp_to_file(const char *tmpfile, char *filename)
1359 {
1360         int ret;
1361         char *dir;
1362
1363         if (!link(tmpfile, filename))
1364                 return 0;
1365
1366         /*
1367          * Try to mkdir the last path component if that failed.
1368          *
1369          * Re-try the "link()" regardless of whether the mkdir
1370          * succeeds, since a race might mean that somebody
1371          * else succeeded.
1372          */
1373         ret = errno;
1374         dir = strrchr(filename, '/');
1375         if (dir) {
1376                 *dir = 0;
1377                 mkdir(filename, 0777);
1378                 if (adjust_shared_perm(filename))
1379                         return -2;
1380                 *dir = '/';
1381                 if (!link(tmpfile, filename))
1382                         return 0;
1383                 ret = errno;
1384         }
1385         return ret;
1386 }
1387
1388 /*
1389  * Move the just written object into its final resting place
1390  */
1391 int move_temp_to_file(const char *tmpfile, char *filename)
1392 {
1393         int ret = link_temp_to_file(tmpfile, filename);
1394
1395         /*
1396          * Coda hack - coda doesn't like cross-directory links,
1397          * so we fall back to a rename, which will mean that it
1398          * won't be able to check collisions, but that's not a
1399          * big deal.
1400          *
1401          * The same holds for FAT formatted media.
1402          *
1403          * When this succeeds, we just return 0. We have nothing
1404          * left to unlink.
1405          */
1406         if (ret && ret != EEXIST) {
1407                 if (!rename(tmpfile, filename))
1408                         return 0;
1409                 ret = errno;
1410         }
1411         unlink(tmpfile);
1412         if (ret) {
1413                 if (ret != EEXIST) {
1414                         fprintf(stderr, "unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1415                         return -1;
1416                 }
1417                 /* FIXME!!! Collision check here ? */
1418         }
1419
1420         return 0;
1421 }
1422
1423 static int write_buffer(int fd, const void *buf, size_t len)
1424 {
1425         while (len) {
1426                 ssize_t size;
1427
1428                 size = write(fd, buf, len);
1429                 if (!size)
1430                         return error("file write: disk full");
1431                 if (size < 0) {
1432                         if (errno == EINTR || errno == EAGAIN)
1433                                 continue;
1434                         return error("file write error (%s)", strerror(errno));
1435                 }
1436                 len -= size;
1437                 buf = (char *) buf + size;
1438         }
1439         return 0;
1440 }
1441
1442 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1443 {
1444         int hdr_len;
1445         unsigned char c;
1446
1447         c = (type << 4) | (len & 15);
1448         len >>= 4;
1449         hdr_len = 1;
1450         while (len) {
1451                 *hdr++ = c | 0x80;
1452                 hdr_len++;
1453                 c = (len & 0x7f);
1454                 len >>= 7;
1455         }
1456         *hdr = c;
1457         return hdr_len;
1458 }
1459
1460 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1461 {
1462         int obj_type, hdr;
1463
1464         if (use_legacy_headers) {
1465                 while (deflate(stream, 0) == Z_OK)
1466                         /* nothing */;
1467                 return;
1468         }
1469         if (!strcmp(type, blob_type))
1470                 obj_type = OBJ_BLOB;
1471         else if (!strcmp(type, tree_type))
1472                 obj_type = OBJ_TREE;
1473         else if (!strcmp(type, commit_type))
1474                 obj_type = OBJ_COMMIT;
1475         else if (!strcmp(type, tag_type))
1476                 obj_type = OBJ_TAG;
1477         else
1478                 die("trying to generate bogus object of type '%s'", type);
1479         hdr = write_binary_header(stream->next_out, obj_type, len);
1480         stream->total_out = hdr;
1481         stream->next_out += hdr;
1482         stream->avail_out -= hdr;
1483 }
1484
1485 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1486 {
1487         int size;
1488         unsigned char *compressed;
1489         z_stream stream;
1490         unsigned char sha1[20];
1491         char *filename;
1492         static char tmpfile[PATH_MAX];
1493         unsigned char hdr[50];
1494         int fd, hdrlen;
1495
1496         /* Normally if we have it in the pack then we do not bother writing
1497          * it out into .git/objects/??/?{38} file.
1498          */
1499         filename = write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1500         if (returnsha1)
1501                 hashcpy(returnsha1, sha1);
1502         if (has_sha1_file(sha1))
1503                 return 0;
1504         fd = open(filename, O_RDONLY);
1505         if (fd >= 0) {
1506                 /*
1507                  * FIXME!!! We might do collision checking here, but we'd
1508                  * need to uncompress the old file and check it. Later.
1509                  */
1510                 close(fd);
1511                 return 0;
1512         }
1513
1514         if (errno != ENOENT) {
1515                 fprintf(stderr, "sha1 file %s: %s\n", filename, strerror(errno));
1516                 return -1;
1517         }
1518
1519         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1520
1521         fd = mkstemp(tmpfile);
1522         if (fd < 0) {
1523                 fprintf(stderr, "unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1524                 return -1;
1525         }
1526
1527         /* Set it up */
1528         memset(&stream, 0, sizeof(stream));
1529         deflateInit(&stream, zlib_compression_level);
1530         size = 8 + deflateBound(&stream, len+hdrlen);
1531         compressed = xmalloc(size);
1532
1533         /* Compress it */
1534         stream.next_out = compressed;
1535         stream.avail_out = size;
1536
1537         /* First header.. */
1538         stream.next_in = hdr;
1539         stream.avail_in = hdrlen;
1540         setup_object_header(&stream, type, len);
1541
1542         /* Then the data itself.. */
1543         stream.next_in = buf;
1544         stream.avail_in = len;
1545         while (deflate(&stream, Z_FINISH) == Z_OK)
1546                 /* nothing */;
1547         deflateEnd(&stream);
1548         size = stream.total_out;
1549
1550         if (write_buffer(fd, compressed, size) < 0)
1551                 die("unable to write sha1 file");
1552         fchmod(fd, 0444);
1553         close(fd);
1554         free(compressed);
1555
1556         return move_temp_to_file(tmpfile, filename);
1557 }
1558
1559 /*
1560  * We need to unpack and recompress the object for writing
1561  * it out to a different file.
1562  */
1563 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1564 {
1565         size_t size;
1566         z_stream stream;
1567         unsigned char *unpacked;
1568         unsigned long len;
1569         char type[20];
1570         char hdr[50];
1571         int hdrlen;
1572         void *buf;
1573
1574         /* need to unpack and recompress it by itself */
1575         unpacked = read_packed_sha1(sha1, type, &len);
1576
1577         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1578
1579         /* Set it up */
1580         memset(&stream, 0, sizeof(stream));
1581         deflateInit(&stream, zlib_compression_level);
1582         size = deflateBound(&stream, len + hdrlen);
1583         buf = xmalloc(size);
1584
1585         /* Compress it */
1586         stream.next_out = buf;
1587         stream.avail_out = size;
1588
1589         /* First header.. */
1590         stream.next_in = (void *)hdr;
1591         stream.avail_in = hdrlen;
1592         while (deflate(&stream, 0) == Z_OK)
1593                 /* nothing */;
1594
1595         /* Then the data itself.. */
1596         stream.next_in = unpacked;
1597         stream.avail_in = len;
1598         while (deflate(&stream, Z_FINISH) == Z_OK)
1599                 /* nothing */;
1600         deflateEnd(&stream);
1601         free(unpacked);
1602
1603         *objsize = stream.total_out;
1604         return buf;
1605 }
1606
1607 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1608 {
1609         int retval;
1610         unsigned long objsize;
1611         void *buf = map_sha1_file(sha1, &objsize);
1612
1613         if (buf) {
1614                 retval = write_buffer(fd, buf, objsize);
1615                 munmap(buf, objsize);
1616                 return retval;
1617         }
1618
1619         buf = repack_object(sha1, &objsize);
1620         retval = write_buffer(fd, buf, objsize);
1621         free(buf);
1622         return retval;
1623 }
1624
1625 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1626                        size_t bufsize, size_t *bufposn)
1627 {
1628         char tmpfile[PATH_MAX];
1629         int local;
1630         z_stream stream;
1631         unsigned char real_sha1[20];
1632         unsigned char discard[4096];
1633         int ret;
1634         SHA_CTX c;
1635
1636         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1637
1638         local = mkstemp(tmpfile);
1639         if (local < 0)
1640                 return error("Couldn't open %s for %s",
1641                              tmpfile, sha1_to_hex(sha1));
1642
1643         memset(&stream, 0, sizeof(stream));
1644
1645         inflateInit(&stream);
1646
1647         SHA1_Init(&c);
1648
1649         do {
1650                 ssize_t size;
1651                 if (*bufposn) {
1652                         stream.avail_in = *bufposn;
1653                         stream.next_in = (unsigned char *) buffer;
1654                         do {
1655                                 stream.next_out = discard;
1656                                 stream.avail_out = sizeof(discard);
1657                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1658                                 SHA1_Update(&c, discard, sizeof(discard) -
1659                                             stream.avail_out);
1660                         } while (stream.avail_in && ret == Z_OK);
1661                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1662                                 die("unable to write sha1 file");
1663                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1664                                 stream.avail_in);
1665                         *bufposn = stream.avail_in;
1666                         if (ret != Z_OK)
1667                                 break;
1668                 }
1669                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1670                 if (size <= 0) {
1671                         close(local);
1672                         unlink(tmpfile);
1673                         if (!size)
1674                                 return error("Connection closed?");
1675                         perror("Reading from connection");
1676                         return -1;
1677                 }
1678                 *bufposn += size;
1679         } while (1);
1680         inflateEnd(&stream);
1681
1682         close(local);
1683         SHA1_Final(real_sha1, &c);
1684         if (ret != Z_STREAM_END) {
1685                 unlink(tmpfile);
1686                 return error("File %s corrupted", sha1_to_hex(sha1));
1687         }
1688         if (hashcmp(sha1, real_sha1)) {
1689                 unlink(tmpfile);
1690                 return error("File %s has bad hash", sha1_to_hex(sha1));
1691         }
1692
1693         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1694 }
1695
1696 int has_pack_index(const unsigned char *sha1)
1697 {
1698         struct stat st;
1699         if (stat(sha1_pack_index_name(sha1), &st))
1700                 return 0;
1701         return 1;
1702 }
1703
1704 int has_pack_file(const unsigned char *sha1)
1705 {
1706         struct stat st;
1707         if (stat(sha1_pack_name(sha1), &st))
1708                 return 0;
1709         return 1;
1710 }
1711
1712 int has_sha1_pack(const unsigned char *sha1)
1713 {
1714         struct pack_entry e;
1715         return find_pack_entry(sha1, &e);
1716 }
1717
1718 int has_sha1_file(const unsigned char *sha1)
1719 {
1720         struct stat st;
1721         struct pack_entry e;
1722
1723         if (find_pack_entry(sha1, &e))
1724                 return 1;
1725         return find_sha1_file(sha1, &st) ? 1 : 0;
1726 }
1727
1728 /*
1729  * reads from fd as long as possible into a supplied buffer of size bytes.
1730  * If necessary the buffer's size is increased using realloc()
1731  *
1732  * returns 0 if anything went fine and -1 otherwise
1733  *
1734  * NOTE: both buf and size may change, but even when -1 is returned
1735  * you still have to free() it yourself.
1736  */
1737 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1738 {
1739         char* buf = *return_buf;
1740         unsigned long size = *return_size;
1741         int iret;
1742         unsigned long off = 0;
1743
1744         do {
1745                 iret = xread(fd, buf + off, size - off);
1746                 if (iret > 0) {
1747                         off += iret;
1748                         if (off == size) {
1749                                 size *= 2;
1750                                 buf = realloc(buf, size);
1751                         }
1752                 }
1753         } while (iret > 0);
1754
1755         *return_buf = buf;
1756         *return_size = off;
1757
1758         if (iret < 0)
1759                 return -1;
1760         return 0;
1761 }
1762
1763 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1764 {
1765         unsigned long size = 4096;
1766         char *buf = malloc(size);
1767         int ret;
1768         unsigned char hdr[50];
1769         int hdrlen;
1770
1771         if (read_pipe(fd, &buf, &size)) {
1772                 free(buf);
1773                 return -1;
1774         }
1775
1776         if (!type)
1777                 type = blob_type;
1778         if (write_object)
1779                 ret = write_sha1_file(buf, size, type, sha1);
1780         else {
1781                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1782                 ret = 0;
1783         }
1784         free(buf);
1785         return ret;
1786 }
1787
1788 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1789 {
1790         unsigned long size = st->st_size;
1791         void *buf;
1792         int ret;
1793         unsigned char hdr[50];
1794         int hdrlen;
1795
1796         buf = "";
1797         if (size)
1798                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1799         close(fd);
1800         if (buf == MAP_FAILED)
1801                 return -1;
1802
1803         if (!type)
1804                 type = blob_type;
1805         if (write_object)
1806                 ret = write_sha1_file(buf, size, type, sha1);
1807         else {
1808                 write_sha1_file_prepare(buf, size, type, sha1, hdr, &hdrlen);
1809                 ret = 0;
1810         }
1811         if (size)
1812                 munmap(buf, size);
1813         return ret;
1814 }
1815
1816 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1817 {
1818         int fd;
1819         char *target;
1820
1821         switch (st->st_mode & S_IFMT) {
1822         case S_IFREG:
1823                 fd = open(path, O_RDONLY);
1824                 if (fd < 0)
1825                         return error("open(\"%s\"): %s", path,
1826                                      strerror(errno));
1827                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1828                         return error("%s: failed to insert into database",
1829                                      path);
1830                 break;
1831         case S_IFLNK:
1832                 target = xmalloc(st->st_size+1);
1833                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1834                         char *errstr = strerror(errno);
1835                         free(target);
1836                         return error("readlink(\"%s\"): %s", path,
1837                                      errstr);
1838                 }
1839                 if (!write_object) {
1840                         unsigned char hdr[50];
1841                         int hdrlen;
1842                         write_sha1_file_prepare(target, st->st_size, blob_type,
1843                                                 sha1, hdr, &hdrlen);
1844                 } else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1845                         return error("%s: failed to insert into database",
1846                                      path);
1847                 free(target);
1848                 break;
1849         default:
1850                 return error("%s: unsupported file type", path);
1851         }
1852         return 0;
1853 }