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 "config.h"
  11 #include "string-list.h"
  12 #include "lockfile.h"
  13 #include "delta.h"
  14 #include "pack.h"
  15 #include "blob.h"
  16 #include "commit.h"
  17 #include "run-command.h"
  18 #include "tag.h"
  19 #include "tree.h"
  20 #include "tree-walk.h"
  21 #include "refs.h"
  22 #include "pack-revindex.h"
  23 #include "sha1-lookup.h"
  24 #include "bulk-checkin.h"
  25 #include "repository.h"
  26 #include "streaming.h"
  27 #include "dir.h"
  28 #include "list.h"
  29 #include "mergesort.h"
  30 #include "quote.h"
  31 #include "packfile.h"
  32 #include "fetch-object.h"
  33 #include "object-store.h"
  34
  35 const unsigned char null_sha1[GIT_MAX_RAWSZ];
  36 const struct object_id null_oid;
  37 const struct object_id empty_tree_oid = {
  38         EMPTY_TREE_SHA1_BIN_LITERAL
  39 };
  40 const struct object_id empty_blob_oid = {
  41         EMPTY_BLOB_SHA1_BIN_LITERAL
  42 };
  43
  44 static void git_hash_sha1_init(void *ctx)
  45 {
  46         git_SHA1_Init((git_SHA_CTX *)ctx);
  47 }
  48
  49 static void git_hash_sha1_update(void *ctx, const void *data, size_t len)
  50 {
  51         git_SHA1_Update((git_SHA_CTX *)ctx, data, len);
  52 }
  53
  54 static void git_hash_sha1_final(unsigned char *hash, void *ctx)
  55 {
  56         git_SHA1_Final(hash, (git_SHA_CTX *)ctx);
  57 }
  58
  59 static void git_hash_unknown_init(void *ctx)
  60 {
  61         die("trying to init unknown hash");
  62 }
  63
  64 static void git_hash_unknown_update(void *ctx, const void *data, size_t len)
  65 {
  66         die("trying to update unknown hash");
  67 }
  68
  69 static void git_hash_unknown_final(unsigned char *hash, void *ctx)
  70 {
  71         die("trying to finalize unknown hash");
  72 }
  73
  74 const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
  75         {
  76                 NULL,
  77                 0x00000000,
  78                 0,
  79                 0,
  80                 0,
  81                 git_hash_unknown_init,
  82                 git_hash_unknown_update,
  83                 git_hash_unknown_final,
  84                 NULL,
  85                 NULL,
  86         },
  87         {
  88                 "sha-1",
  89                 /* "sha1", big-endian */
  90                 0x73686131,
  91                 sizeof(git_SHA_CTX),
  92                 GIT_SHA1_RAWSZ,
  93                 GIT_SHA1_HEXSZ,
  94                 git_hash_sha1_init,
  95                 git_hash_sha1_update,
  96                 git_hash_sha1_final,
  97                 &empty_tree_oid,
  98                 &empty_blob_oid,
  99         },
 100 };
 101
 102 /*
 103  * This is meant to hold a *small* number of objects that you would
 104  * want read_sha1_file() to be able to return, but yet you do not want
 105  * to write them into the object store (e.g. a browse-only
 106  * application).
 107  */
 108 static struct cached_object {
 109         unsigned char sha1[20];
 110         enum object_type type;
 111         void *buf;
 112         unsigned long size;
 113 } *cached_objects;
 114 static int cached_object_nr, cached_object_alloc;
 115
 116 static struct cached_object empty_tree = {
 117         EMPTY_TREE_SHA1_BIN_LITERAL,
 118         OBJ_TREE,
 119         "",
 120         0
 121 };
 122
 123 static struct cached_object *find_cached_object(const unsigned char *sha1)
 124 {
 125         int i;
 126         struct cached_object *co = cached_objects;
 127
 128         for (i = 0; i < cached_object_nr; i++, co++) {
 129                 if (!hashcmp(co->sha1, sha1))
 130                         return co;
 131         }
 132         if (!hashcmp(sha1, empty_tree.sha1))
 133                 return &empty_tree;
 134         return NULL;
 135 }
 136
 137
 138 static int get_conv_flags(unsigned flags)
 139 {
 140         if (flags & HASH_RENORMALIZE)
 141                 return CONV_EOL_RENORMALIZE;
 142         else if (flags & HASH_WRITE_OBJECT)
 143           return global_conv_flags_eol;
 144         else
 145                 return 0;
 146 }
 147
 148
 149 int mkdir_in_gitdir(const char *path)
 150 {
 151         if (mkdir(path, 0777)) {
 152                 int saved_errno = errno;
 153                 struct stat st;
 154                 struct strbuf sb = STRBUF_INIT;
 155
 156                 if (errno != EEXIST)
 157                         return -1;
 158                 /*
 159                  * Are we looking at a path in a symlinked worktree
 160                  * whose original repository does not yet have it?
 161                  * e.g. .git/rr-cache pointing at its original
 162                  * repository in which the user hasn't performed any
 163                  * conflict resolution yet?
 164                  */
 165                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 166                     strbuf_readlink(&sb, path, st.st_size) ||
 167                     !is_absolute_path(sb.buf) ||
 168                     mkdir(sb.buf, 0777)) {
 169                         strbuf_release(&sb);
 170                         errno = saved_errno;
 171                         return -1;
 172                 }
 173                 strbuf_release(&sb);
 174         }
 175         return adjust_shared_perm(path);
 176 }
 177
 178 enum scld_error safe_create_leading_directories(char *path)
 179 {
 180         char *next_component = path + offset_1st_component(path);
 181         enum scld_error ret = SCLD_OK;
 182
 183         while (ret == SCLD_OK && next_component) {
 184                 struct stat st;
 185                 char *slash = next_component, slash_character;
 186
 187                 while (*slash && !is_dir_sep(*slash))
 188                         slash++;
 189
 190                 if (!*slash)
 191                         break;
 192
 193                 next_component = slash + 1;
 194                 while (is_dir_sep(*next_component))
 195                         next_component++;
 196                 if (!*next_component)
 197                         break;
 198
 199                 slash_character = *slash;
 200                 *slash = '\0';
 201                 if (!stat(path, &st)) {
 202                         /* path exists */
 203                         if (!S_ISDIR(st.st_mode)) {
 204                                 errno = ENOTDIR;
 205                                 ret = SCLD_EXISTS;
 206                         }
 207                 } else if (mkdir(path, 0777)) {
 208                         if (errno == EEXIST &&
 209                             !stat(path, &st) && S_ISDIR(st.st_mode))
 210                                 ; /* somebody created it since we checked */
 211                         else if (errno == ENOENT)
 212                                 /*
 213                                  * Either mkdir() failed because
 214                                  * somebody just pruned the containing
 215                                  * directory, or stat() failed because
 216                                  * the file that was in our way was
 217                                  * just removed.  Either way, inform
 218                                  * the caller that it might be worth
 219                                  * trying again:
 220                                  */
 221                                 ret = SCLD_VANISHED;
 222                         else
 223                                 ret = SCLD_FAILED;
 224                 } else if (adjust_shared_perm(path)) {
 225                         ret = SCLD_PERMS;
 226                 }
 227                 *slash = slash_character;
 228         }
 229         return ret;
 230 }
 231
 232 enum scld_error safe_create_leading_directories_const(const char *path)
 233 {
 234         int save_errno;
 235         /* path points to cache entries, so xstrdup before messing with it */
 236         char *buf = xstrdup(path);
 237         enum scld_error result = safe_create_leading_directories(buf);
 238
 239         save_errno = errno;
 240         free(buf);
 241         errno = save_errno;
 242         return result;
 243 }
 244
 245 int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 246 {
 247         /*
 248          * The number of times we will try to remove empty directories
 249          * in the way of path. This is only 1 because if another
 250          * process is racily creating directories that conflict with
 251          * us, we don't want to fight against them.
 252          */
 253         int remove_directories_remaining = 1;
 254
 255         /*
 256          * The number of times that we will try to create the
 257          * directories containing path. We are willing to attempt this
 258          * more than once, because another process could be trying to
 259          * clean up empty directories at the same time as we are
 260          * trying to create them.
 261          */
 262         int create_directories_remaining = 3;
 263
 264         /* A scratch copy of path, filled lazily if we need it: */
 265         struct strbuf path_copy = STRBUF_INIT;
 266
 267         int ret, save_errno;
 268
 269         /* Sanity check: */
 270         assert(*path);
 271
 272 retry_fn:
 273         ret = fn(path, cb);
 274         save_errno = errno;
 275         if (!ret)
 276                 goto out;
 277
 278         if (errno == EISDIR && remove_directories_remaining-- > 0) {
 279                 /*
 280                  * A directory is in the way. Maybe it is empty; try
 281                  * to remove it:
 282                  */
 283                 if (!path_copy.len)
 284                         strbuf_addstr(&path_copy, path);
 285
 286                 if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 287                         goto retry_fn;
 288         } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 289                 /*
 290                  * Maybe the containing directory didn't exist, or
 291                  * maybe it was just deleted by a process that is
 292                  * racing with us to clean up empty directories. Try
 293                  * to create it:
 294                  */
 295                 enum scld_error scld_result;
 296
 297                 if (!path_copy.len)
 298                         strbuf_addstr(&path_copy, path);
 299
 300                 do {
 301                         scld_result = safe_create_leading_directories(path_copy.buf);
 302                         if (scld_result == SCLD_OK)
 303                                 goto retry_fn;
 304                 } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 305         }
 306
 307 out:
 308         strbuf_release(&path_copy);
 309         errno = save_errno;
 310         return ret;
 311 }
 312
 313 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 314 {
 315         int i;
 316         for (i = 0; i < 20; i++) {
 317                 static char hex[] = "0123456789abcdef";
 318                 unsigned int val = sha1[i];
 319                 strbuf_addch(buf, hex[val >> 4]);
 320                 strbuf_addch(buf, hex[val & 0xf]);
 321                 if (!i)
 322                         strbuf_addch(buf, '/');
 323         }
 324 }
 325
 326 void sha1_file_name(struct strbuf *buf, const unsigned char *sha1)
 327 {
 328         strbuf_addstr(buf, get_object_directory());
 329         strbuf_addch(buf, '/');
 330         fill_sha1_path(buf, sha1);
 331 }
 332
 333 struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 334 {
 335         strbuf_setlen(&alt->scratch, alt->base_len);
 336         return &alt->scratch;
 337 }
 338
 339 static const char *alt_sha1_path(struct alternate_object_database *alt,
 340                                  const unsigned char *sha1)
 341 {
 342         struct strbuf *buf = alt_scratch_buf(alt);
 343         fill_sha1_path(buf, sha1);
 344         return buf->buf;
 345 }
 346
 347 /*
 348  * Return non-zero iff the path is usable as an alternate object database.
 349  */
 350 static int alt_odb_usable(struct raw_object_store *o,
 351                           struct strbuf *path,
 352                           const char *normalized_objdir)
 353 {
 354         struct alternate_object_database *alt;
 355
 356         /* Detect cases where alternate disappeared */
 357         if (!is_directory(path->buf)) {
 358                 error("object directory %s does not exist; "
 359                       "check .git/objects/info/alternates.",
 360                       path->buf);
 361                 return 0;
 362         }
 363
 364         /*
 365          * Prevent the common mistake of listing the same
 366          * thing twice, or object directory itself.
 367          */
 368         for (alt = o->alt_odb_list; alt; alt = alt->next) {
 369                 if (!fspathcmp(path->buf, alt->path))
 370                         return 0;
 371         }
 372         if (!fspathcmp(path->buf, normalized_objdir))
 373                 return 0;
 374
 375         return 1;
 376 }
 377
 378 /*
 379  * Prepare alternate object database registry.
 380  *
 381  * The variable alt_odb_list points at the list of struct
 382  * alternate_object_database.  The elements on this list come from
 383  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 384  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 385  * whose contents is similar to that environment variable but can be
 386  * LF separated.  Its base points at a statically allocated buffer that
 387  * contains "/the/directory/corresponding/to/.git/objects/...", while
 388  * its name points just after the slash at the end of ".git/objects/"
 389  * in the example above, and has enough space to hold 40-byte hex
 390  * SHA1, an extra slash for the first level indirection, and the
 391  * terminating NUL.
 392  */
 393 static void read_info_alternates(const char * relative_base, int depth);
 394 #define link_alt_odb_entry(r, e, rb, d, n) link_alt_odb_entry_##r(e, rb, d, n)
 395 static int link_alt_odb_entry_the_repository(const char *entry,
 396         const char *relative_base, int depth, const char *normalized_objdir)
 397 {
 398         struct alternate_object_database *ent;
 399         struct strbuf pathbuf = STRBUF_INIT;
 400
 401         if (!is_absolute_path(entry) && relative_base) {
 402                 strbuf_realpath(&pathbuf, relative_base, 1);
 403                 strbuf_addch(&pathbuf, '/');
 404         }
 405         strbuf_addstr(&pathbuf, entry);
 406
 407         if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 408                 error("unable to normalize alternate object path: %s",
 409                       pathbuf.buf);
 410                 strbuf_release(&pathbuf);
 411                 return -1;
 412         }
 413
 414         /*
 415          * The trailing slash after the directory name is given by
 416          * this function at the end. Remove duplicates.
 417          */
 418         while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 419                 strbuf_setlen(&pathbuf, pathbuf.len - 1);
 420
 421         if (!alt_odb_usable(the_repository->objects, &pathbuf, normalized_objdir)) {
 422                 strbuf_release(&pathbuf);
 423                 return -1;
 424         }
 425
 426         ent = alloc_alt_odb(pathbuf.buf);
 427
 428         /* add the alternate entry */
 429         *the_repository->objects->alt_odb_tail = ent;
 430         the_repository->objects->alt_odb_tail = &(ent->next);
 431         ent->next = NULL;
 432
 433         /* recursively add alternates */
 434         read_info_alternates(pathbuf.buf, depth + 1);
 435
 436         strbuf_release(&pathbuf);
 437         return 0;
 438 }
 439
 440 static const char *parse_alt_odb_entry(const char *string,
 441                                        int sep,
 442                                        struct strbuf *out)
 443 {
 444         const char *end;
 445
 446         strbuf_reset(out);
 447
 448         if (*string == '#') {
 449                 /* comment; consume up to next separator */
 450                 end = strchrnul(string, sep);
 451         } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 452                 /*
 453                  * quoted path; unquote_c_style has copied the
 454                  * data for us and set "end". Broken quoting (e.g.,
 455                  * an entry that doesn't end with a quote) falls
 456                  * back to the unquoted case below.
 457                  */
 458         } else {
 459                 /* normal, unquoted path */
 460                 end = strchrnul(string, sep);
 461                 strbuf_add(out, string, end - string);
 462         }
 463
 464         if (*end)
 465                 end++;
 466         return end;
 467 }
 468
 469 static void link_alt_odb_entries(const char *alt, int sep,
 470                                  const char *relative_base, int depth)
 471 {
 472         struct strbuf objdirbuf = STRBUF_INIT;
 473         struct strbuf entry = STRBUF_INIT;
 474
 475         if (!alt || !*alt)
 476                 return;
 477
 478         if (depth > 5) {
 479                 error("%s: ignoring alternate object stores, nesting too deep.",
 480                                 relative_base);
 481                 return;
 482         }
 483
 484         strbuf_add_absolute_path(&objdirbuf, get_object_directory());
 485         if (strbuf_normalize_path(&objdirbuf) < 0)
 486                 die("unable to normalize object directory: %s",
 487                     objdirbuf.buf);
 488
 489         while (*alt) {
 490                 alt = parse_alt_odb_entry(alt, sep, &entry);
 491                 if (!entry.len)
 492                         continue;
 493                 link_alt_odb_entry(the_repository, entry.buf,
 494                                    relative_base, depth, objdirbuf.buf);
 495         }
 496         strbuf_release(&entry);
 497         strbuf_release(&objdirbuf);
 498 }
 499
 500 static void read_info_alternates(const char * relative_base, int depth)
 501 {
 502         char *path;
 503         struct strbuf buf = STRBUF_INIT;
 504
 505         path = xstrfmt("%s/info/alternates", relative_base);
 506         if (strbuf_read_file(&buf, path, 1024) < 0) {
 507                 warn_on_fopen_errors(path);
 508                 free(path);
 509                 return;
 510         }
 511
 512         link_alt_odb_entries(buf.buf, '\n', relative_base, depth);
 513         strbuf_release(&buf);
 514         free(path);
 515 }
 516
 517 struct alternate_object_database *alloc_alt_odb(const char *dir)
 518 {
 519         struct alternate_object_database *ent;
 520
 521         FLEX_ALLOC_STR(ent, path, dir);
 522         strbuf_init(&ent->scratch, 0);
 523         strbuf_addf(&ent->scratch, "%s/", dir);
 524         ent->base_len = ent->scratch.len;
 525
 526         return ent;
 527 }
 528
 529 void add_to_alternates_file(const char *reference)
 530 {
 531         struct lock_file lock = LOCK_INIT;
 532         char *alts = git_pathdup("objects/info/alternates");
 533         FILE *in, *out;
 534         int found = 0;
 535
 536         hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 537         out = fdopen_lock_file(&lock, "w");
 538         if (!out)
 539                 die_errno("unable to fdopen alternates lockfile");
 540
 541         in = fopen(alts, "r");
 542         if (in) {
 543                 struct strbuf line = STRBUF_INIT;
 544
 545                 while (strbuf_getline(&line, in) != EOF) {
 546                         if (!strcmp(reference, line.buf)) {
 547                                 found = 1;
 548                                 break;
 549                         }
 550                         fprintf_or_die(out, "%s\n", line.buf);
 551                 }
 552
 553                 strbuf_release(&line);
 554                 fclose(in);
 555         }
 556         else if (errno != ENOENT)
 557                 die_errno("unable to read alternates file");
 558
 559         if (found) {
 560                 rollback_lock_file(&lock);
 561         } else {
 562                 fprintf_or_die(out, "%s\n", reference);
 563                 if (commit_lock_file(&lock))
 564                         die_errno("unable to move new alternates file into place");
 565                 if (the_repository->objects->alt_odb_tail)
 566                         link_alt_odb_entries(reference, '\n', NULL, 0);
 567         }
 568         free(alts);
 569 }
 570
 571 void add_to_alternates_memory(const char *reference)
 572 {
 573         /*
 574          * Make sure alternates are initialized, or else our entry may be
 575          * overwritten when they are.
 576          */
 577         prepare_alt_odb();
 578
 579         link_alt_odb_entries(reference, '\n', NULL, 0);
 580 }
 581
 582 /*
 583  * Compute the exact path an alternate is at and returns it. In case of
 584  * error NULL is returned and the human readable error is added to `err`
 585  * `path` may be relative and should point to $GITDIR.
 586  * `err` must not be null.
 587  */
 588 char *compute_alternate_path(const char *path, struct strbuf *err)
 589 {
 590         char *ref_git = NULL;
 591         const char *repo, *ref_git_s;
 592         int seen_error = 0;
 593
 594         ref_git_s = real_path_if_valid(path);
 595         if (!ref_git_s) {
 596                 seen_error = 1;
 597                 strbuf_addf(err, _("path '%s' does not exist"), path);
 598                 goto out;
 599         } else
 600                 /*
 601                  * Beware: read_gitfile(), real_path() and mkpath()
 602                  * return static buffer
 603                  */
 604                 ref_git = xstrdup(ref_git_s);
 605
 606         repo = read_gitfile(ref_git);
 607         if (!repo)
 608                 repo = read_gitfile(mkpath("%s/.git", ref_git));
 609         if (repo) {
 610                 free(ref_git);
 611                 ref_git = xstrdup(repo);
 612         }
 613
 614         if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 615                 char *ref_git_git = mkpathdup("%s/.git", ref_git);
 616                 free(ref_git);
 617                 ref_git = ref_git_git;
 618         } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 619                 struct strbuf sb = STRBUF_INIT;
 620                 seen_error = 1;
 621                 if (get_common_dir(&sb, ref_git)) {
 622                         strbuf_addf(err,
 623                                     _("reference repository '%s' as a linked "
 624                                       "checkout is not supported yet."),
 625                                     path);
 626                         goto out;
 627                 }
 628
 629                 strbuf_addf(err, _("reference repository '%s' is not a "
 630                                         "local repository."), path);
 631                 goto out;
 632         }
 633
 634         if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 635                 strbuf_addf(err, _("reference repository '%s' is shallow"),
 636                             path);
 637                 seen_error = 1;
 638                 goto out;
 639         }
 640
 641         if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 642                 strbuf_addf(err,
 643                             _("reference repository '%s' is grafted"),
 644                             path);
 645                 seen_error = 1;
 646                 goto out;
 647         }
 648
 649 out:
 650         if (seen_error) {
 651                 FREE_AND_NULL(ref_git);
 652         }
 653
 654         return ref_git;
 655 }
 656
 657 int foreach_alt_odb(alt_odb_fn fn, void *cb)
 658 {
 659         struct alternate_object_database *ent;
 660         int r = 0;
 661
 662         prepare_alt_odb();
 663         for (ent = the_repository->objects->alt_odb_list; ent; ent = ent->next) {
 664                 r = fn(ent, cb);
 665                 if (r)
 666                         break;
 667         }
 668         return r;
 669 }
 670
 671 void prepare_alt_odb(void)
 672 {
 673         if (the_repository->objects->alt_odb_tail)
 674                 return;
 675
 676         the_repository->objects->alt_odb_tail =
 677                         &the_repository->objects->alt_odb_list;
 678         link_alt_odb_entries(the_repository->objects->alternate_db,
 679                              PATH_SEP, NULL, 0);
 680
 681         read_info_alternates(get_object_directory(), 0);
 682 }
 683
 684 /* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 685 static int freshen_file(const char *fn)
 686 {
 687         struct utimbuf t;
 688         t.actime = t.modtime = time(NULL);
 689         return !utime(fn, &t);
 690 }
 691
 692 /*
 693  * All of the check_and_freshen functions return 1 if the file exists and was
 694  * freshened (if freshening was requested), 0 otherwise. If they return
 695  * 0, you should not assume that it is safe to skip a write of the object (it
 696  * either does not exist on disk, or has a stale mtime and may be subject to
 697  * pruning).
 698  */
 699 int check_and_freshen_file(const char *fn, int freshen)
 700 {
 701         if (access(fn, F_OK))
 702                 return 0;
 703         if (freshen && !freshen_file(fn))
 704                 return 0;
 705         return 1;
 706 }
 707
 708 static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 709 {
 710         static struct strbuf buf = STRBUF_INIT;
 711
 712         strbuf_reset(&buf);
 713         sha1_file_name(&buf, sha1);
 714
 715         return check_and_freshen_file(buf.buf, freshen);
 716 }
 717
 718 static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 719 {
 720         struct alternate_object_database *alt;
 721         prepare_alt_odb();
 722         for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 723                 const char *path = alt_sha1_path(alt, sha1);
 724                 if (check_and_freshen_file(path, freshen))
 725                         return 1;
 726         }
 727         return 0;
 728 }
 729
 730 static int check_and_freshen(const unsigned char *sha1, int freshen)
 731 {
 732         return check_and_freshen_local(sha1, freshen) ||
 733                check_and_freshen_nonlocal(sha1, freshen);
 734 }
 735
 736 int has_loose_object_nonlocal(const unsigned char *sha1)
 737 {
 738         return check_and_freshen_nonlocal(sha1, 0);
 739 }
 740
 741 static int has_loose_object(const unsigned char *sha1)
 742 {
 743         return check_and_freshen(sha1, 0);
 744 }
 745
 746 static void mmap_limit_check(size_t length)
 747 {
 748         static size_t limit = 0;
 749         if (!limit) {
 750                 limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 751                 if (!limit)
 752                         limit = SIZE_MAX;
 753         }
 754         if (length > limit)
 755                 die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 756                     (uintmax_t)length, (uintmax_t)limit);
 757 }
 758
 759 void *xmmap_gently(void *start, size_t length,
 760                   int prot, int flags, int fd, off_t offset)
 761 {
 762         void *ret;
 763
 764         mmap_limit_check(length);
 765         ret = mmap(start, length, prot, flags, fd, offset);
 766         if (ret == MAP_FAILED) {
 767                 if (!length)
 768                         return NULL;
 769                 release_pack_memory(length);
 770                 ret = mmap(start, length, prot, flags, fd, offset);
 771         }
 772         return ret;
 773 }
 774
 775 void *xmmap(void *start, size_t length,
 776         int prot, int flags, int fd, off_t offset)
 777 {
 778         void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 779         if (ret == MAP_FAILED)
 780                 die_errno("mmap failed");
 781         return ret;
 782 }
 783
 784 /*
 785  * With an in-core object data in "map", rehash it to make sure the
 786  * object name actually matches "sha1" to detect object corruption.
 787  * With "map" == NULL, try reading the object named with "sha1" using
 788  * the streaming interface and rehash it to do the same.
 789  */
 790 int check_sha1_signature(const unsigned char *sha1, void *map,
 791                          unsigned long size, const char *type)
 792 {
 793         unsigned char real_sha1[20];
 794         enum object_type obj_type;
 795         struct git_istream *st;
 796         git_SHA_CTX c;
 797         char hdr[32];
 798         int hdrlen;
 799
 800         if (map) {
 801                 hash_sha1_file(map, size, type, real_sha1);
 802                 return hashcmp(sha1, real_sha1) ? -1 : 0;
 803         }
 804
 805         st = open_istream(sha1, &obj_type, &size, NULL);
 806         if (!st)
 807                 return -1;
 808
 809         /* Generate the header */
 810         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(obj_type), size) + 1;
 811
 812         /* Sha1.. */
 813         git_SHA1_Init(&c);
 814         git_SHA1_Update(&c, hdr, hdrlen);
 815         for (;;) {
 816                 char buf[1024 * 16];
 817                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 818
 819                 if (readlen < 0) {
 820                         close_istream(st);
 821                         return -1;
 822                 }
 823                 if (!readlen)
 824                         break;
 825                 git_SHA1_Update(&c, buf, readlen);
 826         }
 827         git_SHA1_Final(real_sha1, &c);
 828         close_istream(st);
 829         return hashcmp(sha1, real_sha1) ? -1 : 0;
 830 }
 831
 832 int git_open_cloexec(const char *name, int flags)
 833 {
 834         int fd;
 835         static int o_cloexec = O_CLOEXEC;
 836
 837         fd = open(name, flags | o_cloexec);
 838         if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 839                 /* Try again w/o O_CLOEXEC: the kernel might not support it */
 840                 o_cloexec &= ~O_CLOEXEC;
 841                 fd = open(name, flags | o_cloexec);
 842         }
 843
 844 #if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 845         {
 846                 static int fd_cloexec = FD_CLOEXEC;
 847
 848                 if (!o_cloexec && 0 <= fd && fd_cloexec) {
 849                         /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 850                         int flags = fcntl(fd, F_GETFD);
 851                         if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 852                                 fd_cloexec = 0;
 853                 }
 854         }
 855 #endif
 856         return fd;
 857 }
 858
 859 /*
 860  * Find "sha1" as a loose object in the local repository or in an alternate.
 861  * Returns 0 on success, negative on failure.
 862  *
 863  * The "path" out-parameter will give the path of the object we found (if any).
 864  * Note that it may point to static storage and is only valid until another
 865  * call to sha1_file_name(), etc.
 866  */
 867 static int stat_sha1_file(const unsigned char *sha1, struct stat *st,
 868                           const char **path)
 869 {
 870         struct alternate_object_database *alt;
 871         static struct strbuf buf = STRBUF_INIT;
 872
 873         strbuf_reset(&buf);
 874         sha1_file_name(&buf, sha1);
 875         *path = buf.buf;
 876
 877         if (!lstat(*path, st))
 878                 return 0;
 879
 880         prepare_alt_odb();
 881         errno = ENOENT;
 882         for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 883                 *path = alt_sha1_path(alt, sha1);
 884                 if (!lstat(*path, st))
 885                         return 0;
 886         }
 887
 888         return -1;
 889 }
 890
 891 /*
 892  * Like stat_sha1_file(), but actually open the object and return the
 893  * descriptor. See the caveats on the "path" parameter above.
 894  */
 895 static int open_sha1_file(const unsigned char *sha1, const char **path)
 896 {
 897         int fd;
 898         struct alternate_object_database *alt;
 899         int most_interesting_errno;
 900         static struct strbuf buf = STRBUF_INIT;
 901
 902         strbuf_reset(&buf);
 903         sha1_file_name(&buf, sha1);
 904         *path = buf.buf;
 905
 906         fd = git_open(*path);
 907         if (fd >= 0)
 908                 return fd;
 909         most_interesting_errno = errno;
 910
 911         prepare_alt_odb();
 912         for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 913                 *path = alt_sha1_path(alt, sha1);
 914                 fd = git_open(*path);
 915                 if (fd >= 0)
 916                         return fd;
 917                 if (most_interesting_errno == ENOENT)
 918                         most_interesting_errno = errno;
 919         }
 920         errno = most_interesting_errno;
 921         return -1;
 922 }
 923
 924 /*
 925  * Map the loose object at "path" if it is not NULL, or the path found by
 926  * searching for a loose object named "sha1".
 927  */
 928 static void *map_sha1_file_1(const char *path,
 929                              const unsigned char *sha1,
 930                              unsigned long *size)
 931 {
 932         void *map;
 933         int fd;
 934
 935         if (path)
 936                 fd = git_open(path);
 937         else
 938                 fd = open_sha1_file(sha1, &path);
 939         map = NULL;
 940         if (fd >= 0) {
 941                 struct stat st;
 942
 943                 if (!fstat(fd, &st)) {
 944                         *size = xsize_t(st.st_size);
 945                         if (!*size) {
 946                                 /* mmap() is forbidden on empty files */
 947                                 error("object file %s is empty", path);
 948                                 return NULL;
 949                         }
 950                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 951                 }
 952                 close(fd);
 953         }
 954         return map;
 955 }
 956
 957 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 958 {
 959         return map_sha1_file_1(NULL, sha1, size);
 960 }
 961
 962 static int unpack_sha1_short_header(git_zstream *stream,
 963                                     unsigned char *map, unsigned long mapsize,
 964                                     void *buffer, unsigned long bufsiz)
 965 {
 966         /* Get the data stream */
 967         memset(stream, 0, sizeof(*stream));
 968         stream->next_in = map;
 969         stream->avail_in = mapsize;
 970         stream->next_out = buffer;
 971         stream->avail_out = bufsiz;
 972
 973         git_inflate_init(stream);
 974         return git_inflate(stream, 0);
 975 }
 976
 977 int unpack_sha1_header(git_zstream *stream,
 978                        unsigned char *map, unsigned long mapsize,
 979                        void *buffer, unsigned long bufsiz)
 980 {
 981         int status = unpack_sha1_short_header(stream, map, mapsize,
 982                                               buffer, bufsiz);
 983
 984         if (status < Z_OK)
 985                 return status;
 986
 987         /* Make sure we have the terminating NUL */
 988         if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 989                 return -1;
 990         return 0;
 991 }
 992
 993 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
 994                                         unsigned long mapsize, void *buffer,
 995                                         unsigned long bufsiz, struct strbuf *header)
 996 {
 997         int status;
 998
 999         status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
1000         if (status < Z_OK)
1001                 return -1;
1002
1003         /*
1004          * Check if entire header is unpacked in the first iteration.
1005          */
1006         if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1007                 return 0;
1008
1009         /*
1010          * buffer[0..bufsiz] was not large enough.  Copy the partial
1011          * result out to header, and then append the result of further
1012          * reading the stream.
1013          */
1014         strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1015         stream->next_out = buffer;
1016         stream->avail_out = bufsiz;
1017
1018         do {
1019                 status = git_inflate(stream, 0);
1020                 strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1021                 if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1022                         return 0;
1023                 stream->next_out = buffer;
1024                 stream->avail_out = bufsiz;
1025         } while (status != Z_STREAM_END);
1026         return -1;
1027 }
1028
1029 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1030 {
1031         int bytes = strlen(buffer) + 1;
1032         unsigned char *buf = xmallocz(size);
1033         unsigned long n;
1034         int status = Z_OK;
1035
1036         n = stream->total_out - bytes;
1037         if (n > size)
1038                 n = size;
1039         memcpy(buf, (char *) buffer + bytes, n);
1040         bytes = n;
1041         if (bytes <= size) {
1042                 /*
1043                  * The above condition must be (bytes <= size), not
1044                  * (bytes < size).  In other words, even though we
1045                  * expect no more output and set avail_out to zero,
1046                  * the input zlib stream may have bytes that express
1047                  * "this concludes the stream", and we *do* want to
1048                  * eat that input.
1049                  *
1050                  * Otherwise we would not be able to test that we
1051                  * consumed all the input to reach the expected size;
1052                  * we also want to check that zlib tells us that all
1053                  * went well with status == Z_STREAM_END at the end.
1054                  */
1055                 stream->next_out = buf + bytes;
1056                 stream->avail_out = size - bytes;
1057                 while (status == Z_OK)
1058                         status = git_inflate(stream, Z_FINISH);
1059         }
1060         if (status == Z_STREAM_END && !stream->avail_in) {
1061                 git_inflate_end(stream);
1062                 return buf;
1063         }
1064
1065         if (status < 0)
1066                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1067         else if (stream->avail_in)
1068                 error("garbage at end of loose object '%s'",
1069                       sha1_to_hex(sha1));
1070         free(buf);
1071         return NULL;
1072 }
1073
1074 /*
1075  * We used to just use "sscanf()", but that's actually way
1076  * too permissive for what we want to check. So do an anal
1077  * object header parse by hand.
1078  */
1079 static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1080                                unsigned int flags)
1081 {
1082         const char *type_buf = hdr;
1083         unsigned long size;
1084         int type, type_len = 0;
1085
1086         /*
1087          * The type can be of any size but is followed by
1088          * a space.
1089          */
1090         for (;;) {
1091                 char c = *hdr++;
1092                 if (!c)
1093                         return -1;
1094                 if (c == ' ')
1095                         break;
1096                 type_len++;
1097         }
1098
1099         type = type_from_string_gently(type_buf, type_len, 1);
1100         if (oi->typename)
1101                 strbuf_add(oi->typename, type_buf, type_len);
1102         /*
1103          * Set type to 0 if its an unknown object and
1104          * we're obtaining the type using '--allow-unknown-type'
1105          * option.
1106          */
1107         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
1108                 type = 0;
1109         else if (type < 0)
1110                 die("invalid object type");
1111         if (oi->typep)
1112                 *oi->typep = type;
1113
1114         /*
1115          * The length must follow immediately, and be in canonical
1116          * decimal format (ie "010" is not valid).
1117          */
1118         size = *hdr++ - '0';
1119         if (size > 9)
1120                 return -1;
1121         if (size) {
1122                 for (;;) {
1123                         unsigned long c = *hdr - '0';
1124                         if (c > 9)
1125                                 break;
1126                         hdr++;
1127                         size = size * 10 + c;
1128                 }
1129         }
1130
1131         if (oi->sizep)
1132                 *oi->sizep = size;
1133
1134         /*
1135          * The length must be followed by a zero byte
1136          */
1137         return *hdr ? -1 : type;
1138 }
1139
1140 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1141 {
1142         struct object_info oi = OBJECT_INFO_INIT;
1143
1144         oi.sizep = sizep;
1145         return parse_sha1_header_extended(hdr, &oi, 0);
1146 }
1147
1148 static int sha1_loose_object_info(const unsigned char *sha1,
1149                                   struct object_info *oi,
1150                                   int flags)
1151 {
1152         int status = 0;
1153         unsigned long mapsize;
1154         void *map;
1155         git_zstream stream;
1156         char hdr[32];
1157         struct strbuf hdrbuf = STRBUF_INIT;
1158         unsigned long size_scratch;
1159
1160         if (oi->delta_base_sha1)
1161                 hashclr(oi->delta_base_sha1);
1162
1163         /*
1164          * If we don't care about type or size, then we don't
1165          * need to look inside the object at all. Note that we
1166          * do not optimize out the stat call, even if the
1167          * caller doesn't care about the disk-size, since our
1168          * return value implicitly indicates whether the
1169          * object even exists.
1170          */
1171         if (!oi->typep && !oi->typename && !oi->sizep && !oi->contentp) {
1172                 const char *path;
1173                 struct stat st;
1174                 if (stat_sha1_file(sha1, &st, &path) < 0)
1175                         return -1;
1176                 if (oi->disk_sizep)
1177                         *oi->disk_sizep = st.st_size;
1178                 return 0;
1179         }
1180
1181         map = map_sha1_file(sha1, &mapsize);
1182         if (!map)
1183                 return -1;
1184
1185         if (!oi->sizep)
1186                 oi->sizep = &size_scratch;
1187
1188         if (oi->disk_sizep)
1189                 *oi->disk_sizep = mapsize;
1190         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
1191                 if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
1192                         status = error("unable to unpack %s header with --allow-unknown-type",
1193                                        sha1_to_hex(sha1));
1194         } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1195                 status = error("unable to unpack %s header",
1196                                sha1_to_hex(sha1));
1197         if (status < 0)
1198                 ; /* Do nothing */
1199         else if (hdrbuf.len) {
1200                 if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
1201                         status = error("unable to parse %s header with --allow-unknown-type",
1202                                        sha1_to_hex(sha1));
1203         } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
1204                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1205
1206         if (status >= 0 && oi->contentp) {
1207                 *oi->contentp = unpack_sha1_rest(&stream, hdr,
1208                                                  *oi->sizep, sha1);
1209                 if (!*oi->contentp) {
1210                         git_inflate_end(&stream);
1211                         status = -1;
1212                 }
1213         } else
1214                 git_inflate_end(&stream);
1215
1216         munmap(map, mapsize);
1217         if (status && oi->typep)
1218                 *oi->typep = status;
1219         if (oi->sizep == &size_scratch)
1220                 oi->sizep = NULL;
1221         strbuf_release(&hdrbuf);
1222         oi->whence = OI_LOOSE;
1223         return (status < 0) ? status : 0;
1224 }
1225
1226 int fetch_if_missing = 1;
1227
1228 int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
1229 {
1230         static struct object_info blank_oi = OBJECT_INFO_INIT;
1231         struct pack_entry e;
1232         int rtype;
1233         const unsigned char *real = (flags & OBJECT_INFO_LOOKUP_REPLACE) ?
1234                                     lookup_replace_object(sha1) :
1235                                     sha1;
1236         int already_retried = 0;
1237
1238         if (is_null_sha1(real))
1239                 return -1;
1240
1241         if (!oi)
1242                 oi = &blank_oi;
1243
1244         if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
1245                 struct cached_object *co = find_cached_object(real);
1246                 if (co) {
1247                         if (oi->typep)
1248                                 *(oi->typep) = co->type;
1249                         if (oi->sizep)
1250                                 *(oi->sizep) = co->size;
1251                         if (oi->disk_sizep)
1252                                 *(oi->disk_sizep) = 0;
1253                         if (oi->delta_base_sha1)
1254                                 hashclr(oi->delta_base_sha1);
1255                         if (oi->typename)
1256                                 strbuf_addstr(oi->typename, typename(co->type));
1257                         if (oi->contentp)
1258                                 *oi->contentp = xmemdupz(co->buf, co->size);
1259                         oi->whence = OI_CACHED;
1260                         return 0;
1261                 }
1262         }
1263
1264         while (1) {
1265                 if (find_pack_entry(real, &e))
1266                         break;
1267
1268                 /* Most likely it's a loose object. */
1269                 if (!sha1_loose_object_info(real, oi, flags))
1270                         return 0;
1271
1272                 /* Not a loose object; someone else may have just packed it. */
1273                 reprepare_packed_git();
1274                 if (find_pack_entry(real, &e))
1275                         break;
1276
1277                 /* Check if it is a missing object */
1278                 if (fetch_if_missing && repository_format_partial_clone &&
1279                     !already_retried) {
1280                         /*
1281                          * TODO Investigate haveing fetch_object() return
1282                          * TODO error/success and stopping the music here.
1283                          */
1284                         fetch_object(repository_format_partial_clone, real);
1285                         already_retried = 1;
1286                         continue;
1287                 }
1288
1289                 return -1;
1290         }
1291
1292         if (oi == &blank_oi)
1293                 /*
1294                  * We know that the caller doesn't actually need the
1295                  * information below, so return early.
1296                  */
1297                 return 0;
1298         rtype = packed_object_info(e.p, e.offset, oi);
1299         if (rtype < 0) {
1300                 mark_bad_packed_object(e.p, real);
1301                 return sha1_object_info_extended(real, oi, 0);
1302         } else if (oi->whence == OI_PACKED) {
1303                 oi->u.packed.offset = e.offset;
1304                 oi->u.packed.pack = e.p;
1305                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
1306                                          rtype == OBJ_OFS_DELTA);
1307         }
1308
1309         return 0;
1310 }
1311
1312 /* returns enum object_type or negative */
1313 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1314 {
1315         enum object_type type;
1316         struct object_info oi = OBJECT_INFO_INIT;
1317
1318         oi.typep = &type;
1319         oi.sizep = sizep;
1320         if (sha1_object_info_extended(sha1, &oi,
1321                                       OBJECT_INFO_LOOKUP_REPLACE) < 0)
1322                 return -1;
1323         return type;
1324 }
1325
1326 static void *read_object(const unsigned char *sha1, enum object_type *type,
1327                          unsigned long *size)
1328 {
1329         struct object_info oi = OBJECT_INFO_INIT;
1330         void *content;
1331         oi.typep = type;
1332         oi.sizep = size;
1333         oi.contentp = &content;
1334
1335         if (sha1_object_info_extended(sha1, &oi, 0) < 0)
1336                 return NULL;
1337         return content;
1338 }
1339
1340 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
1341                       unsigned char *sha1)
1342 {
1343         struct cached_object *co;
1344
1345         hash_sha1_file(buf, len, typename(type), sha1);
1346         if (has_sha1_file(sha1) || find_cached_object(sha1))
1347                 return 0;
1348         ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
1349         co = &cached_objects[cached_object_nr++];
1350         co->size = len;
1351         co->type = type;
1352         co->buf = xmalloc(len);
1353         memcpy(co->buf, buf, len);
1354         hashcpy(co->sha1, sha1);
1355         return 0;
1356 }
1357
1358 /*
1359  * This function dies on corrupt objects; the callers who want to
1360  * deal with them should arrange to call read_object() and give error
1361  * messages themselves.
1362  */
1363 void *read_sha1_file_extended(const unsigned char *sha1,
1364                               enum object_type *type,
1365                               unsigned long *size,
1366                               int lookup_replace)
1367 {
1368         void *data;
1369         const struct packed_git *p;
1370         const char *path;
1371         struct stat st;
1372         const unsigned char *repl = lookup_replace ? lookup_replace_object(sha1)
1373                                                    : sha1;
1374
1375         errno = 0;
1376         data = read_object(repl, type, size);
1377         if (data)
1378                 return data;
1379
1380         if (errno && errno != ENOENT)
1381                 die_errno("failed to read object %s", sha1_to_hex(sha1));
1382
1383         /* die if we replaced an object with one that does not exist */
1384         if (repl != sha1)
1385                 die("replacement %s not found for %s",
1386                     sha1_to_hex(repl), sha1_to_hex(sha1));
1387
1388         if (!stat_sha1_file(repl, &st, &path))
1389                 die("loose object %s (stored in %s) is corrupt",
1390                     sha1_to_hex(repl), path);
1391
1392         if ((p = has_packed_and_bad(repl)) != NULL)
1393                 die("packed object %s (stored in %s) is corrupt",
1394                     sha1_to_hex(repl), p->pack_name);
1395
1396         return NULL;
1397 }
1398
1399 void *read_object_with_reference(const unsigned char *sha1,
1400                                  const char *required_type_name,
1401                                  unsigned long *size,
1402                                  unsigned char *actual_sha1_return)
1403 {
1404         enum object_type type, required_type;
1405         void *buffer;
1406         unsigned long isize;
1407         unsigned char actual_sha1[20];
1408
1409         required_type = type_from_string(required_type_name);
1410         hashcpy(actual_sha1, sha1);
1411         while (1) {
1412                 int ref_length = -1;
1413                 const char *ref_type = NULL;
1414
1415                 buffer = read_sha1_file(actual_sha1, &type, &isize);
1416                 if (!buffer)
1417                         return NULL;
1418                 if (type == required_type) {
1419                         *size = isize;
1420                         if (actual_sha1_return)
1421                                 hashcpy(actual_sha1_return, actual_sha1);
1422                         return buffer;
1423                 }
1424                 /* Handle references */
1425                 else if (type == OBJ_COMMIT)
1426                         ref_type = "tree ";
1427                 else if (type == OBJ_TAG)
1428                         ref_type = "object ";
1429                 else {
1430                         free(buffer);
1431                         return NULL;
1432                 }
1433                 ref_length = strlen(ref_type);
1434
1435                 if (ref_length + 40 > isize ||
1436                     memcmp(buffer, ref_type, ref_length) ||
1437                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1438                         free(buffer);
1439                         return NULL;
1440                 }
1441                 free(buffer);
1442                 /* Now we have the ID of the referred-to object in
1443                  * actual_sha1.  Check again. */
1444         }
1445 }
1446
1447 static void write_sha1_file_prepare(const void *buf, unsigned long len,
1448                                     const char *type, unsigned char *sha1,
1449                                     char *hdr, int *hdrlen)
1450 {
1451         git_SHA_CTX c;
1452
1453         /* Generate the header */
1454         *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
1455
1456         /* Sha1.. */
1457         git_SHA1_Init(&c);
1458         git_SHA1_Update(&c, hdr, *hdrlen);
1459         git_SHA1_Update(&c, buf, len);
1460         git_SHA1_Final(sha1, &c);
1461 }
1462
1463 /*
1464  * Move the just written object into its final resting place.
1465  */
1466 int finalize_object_file(const char *tmpfile, const char *filename)
1467 {
1468         int ret = 0;
1469
1470         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
1471                 goto try_rename;
1472         else if (link(tmpfile, filename))
1473                 ret = errno;
1474
1475         /*
1476          * Coda hack - coda doesn't like cross-directory links,
1477          * so we fall back to a rename, which will mean that it
1478          * won't be able to check collisions, but that's not a
1479          * big deal.
1480          *
1481          * The same holds for FAT formatted media.
1482          *
1483          * When this succeeds, we just return.  We have nothing
1484          * left to unlink.
1485          */
1486         if (ret && ret != EEXIST) {
1487         try_rename:
1488                 if (!rename(tmpfile, filename))
1489                         goto out;
1490                 ret = errno;
1491         }
1492         unlink_or_warn(tmpfile);
1493         if (ret) {
1494                 if (ret != EEXIST) {
1495                         return error_errno("unable to write sha1 filename %s", filename);
1496                 }
1497                 /* FIXME!!! Collision check here ? */
1498         }
1499
1500 out:
1501         if (adjust_shared_perm(filename))
1502                 return error("unable to set permission to '%s'", filename);
1503         return 0;
1504 }
1505
1506 static int write_buffer(int fd, const void *buf, size_t len)
1507 {
1508         if (write_in_full(fd, buf, len) < 0)
1509                 return error_errno("file write error");
1510         return 0;
1511 }
1512
1513 int hash_sha1_file(const void *buf, unsigned long len, const char *type,
1514                    unsigned char *sha1)
1515 {
1516         char hdr[32];
1517         int hdrlen = sizeof(hdr);
1518         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1519         return 0;
1520 }
1521
1522 /* Finalize a file on disk, and close it. */
1523 static void close_sha1_file(int fd)
1524 {
1525         if (fsync_object_files)
1526                 fsync_or_die(fd, "sha1 file");
1527         if (close(fd) != 0)
1528                 die_errno("error when closing sha1 file");
1529 }
1530
1531 /* Size of directory component, including the ending '/' */
1532 static inline int directory_size(const char *filename)
1533 {
1534         const char *s = strrchr(filename, '/');
1535         if (!s)
1536                 return 0;
1537         return s - filename + 1;
1538 }
1539
1540 /*
1541  * This creates a temporary file in the same directory as the final
1542  * 'filename'
1543  *
1544  * We want to avoid cross-directory filename renames, because those
1545  * can have problems on various filesystems (FAT, NFS, Coda).
1546  */
1547 static int create_tmpfile(struct strbuf *tmp, const char *filename)
1548 {
1549         int fd, dirlen = directory_size(filename);
1550
1551         strbuf_reset(tmp);
1552         strbuf_add(tmp, filename, dirlen);
1553         strbuf_addstr(tmp, "tmp_obj_XXXXXX");
1554         fd = git_mkstemp_mode(tmp->buf, 0444);
1555         if (fd < 0 && dirlen && errno == ENOENT) {
1556                 /*
1557                  * Make sure the directory exists; note that the contents
1558                  * of the buffer are undefined after mkstemp returns an
1559                  * error, so we have to rewrite the whole buffer from
1560                  * scratch.
1561                  */
1562                 strbuf_reset(tmp);
1563                 strbuf_add(tmp, filename, dirlen - 1);
1564                 if (mkdir(tmp->buf, 0777) && errno != EEXIST)
1565                         return -1;
1566                 if (adjust_shared_perm(tmp->buf))
1567                         return -1;
1568
1569                 /* Try again */
1570                 strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
1571                 fd = git_mkstemp_mode(tmp->buf, 0444);
1572         }
1573         return fd;
1574 }
1575
1576 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
1577                               const void *buf, unsigned long len, time_t mtime)
1578 {
1579         int fd, ret;
1580         unsigned char compressed[4096];
1581         git_zstream stream;
1582         git_SHA_CTX c;
1583         unsigned char parano_sha1[20];
1584         static struct strbuf tmp_file = STRBUF_INIT;
1585         static struct strbuf filename = STRBUF_INIT;
1586
1587         strbuf_reset(&filename);
1588         sha1_file_name(&filename, sha1);
1589
1590         fd = create_tmpfile(&tmp_file, filename.buf);
1591         if (fd < 0) {
1592                 if (errno == EACCES)
1593                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
1594                 else
1595                         return error_errno("unable to create temporary file");
1596         }
1597
1598         /* Set it up */
1599         git_deflate_init(&stream, zlib_compression_level);
1600         stream.next_out = compressed;
1601         stream.avail_out = sizeof(compressed);
1602         git_SHA1_Init(&c);
1603
1604         /* First header.. */
1605         stream.next_in = (unsigned char *)hdr;
1606         stream.avail_in = hdrlen;
1607         while (git_deflate(&stream, 0) == Z_OK)
1608                 ; /* nothing */
1609         git_SHA1_Update(&c, hdr, hdrlen);
1610
1611         /* Then the data itself.. */
1612         stream.next_in = (void *)buf;
1613         stream.avail_in = len;
1614         do {
1615                 unsigned char *in0 = stream.next_in;
1616                 ret = git_deflate(&stream, Z_FINISH);
1617                 git_SHA1_Update(&c, in0, stream.next_in - in0);
1618                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
1619                         die("unable to write sha1 file");
1620                 stream.next_out = compressed;
1621                 stream.avail_out = sizeof(compressed);
1622         } while (ret == Z_OK);
1623
1624         if (ret != Z_STREAM_END)
1625                 die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
1626         ret = git_deflate_end_gently(&stream);
1627         if (ret != Z_OK)
1628                 die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
1629         git_SHA1_Final(parano_sha1, &c);
1630         if (hashcmp(sha1, parano_sha1) != 0)
1631                 die("confused by unstable object source data for %s", sha1_to_hex(sha1));
1632
1633         close_sha1_file(fd);
1634
1635         if (mtime) {
1636                 struct utimbuf utb;
1637                 utb.actime = mtime;
1638                 utb.modtime = mtime;
1639                 if (utime(tmp_file.buf, &utb) < 0)
1640                         warning_errno("failed utime() on %s", tmp_file.buf);
1641         }
1642
1643         return finalize_object_file(tmp_file.buf, filename.buf);
1644 }
1645
1646 static int freshen_loose_object(const unsigned char *sha1)
1647 {
1648         return check_and_freshen(sha1, 1);
1649 }
1650
1651 static int freshen_packed_object(const unsigned char *sha1)
1652 {
1653         struct pack_entry e;
1654         if (!find_pack_entry(sha1, &e))
1655                 return 0;
1656         if (e.p->freshened)
1657                 return 1;
1658         if (!freshen_file(e.p->pack_name))
1659                 return 0;
1660         e.p->freshened = 1;
1661         return 1;
1662 }
1663
1664 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
1665 {
1666         char hdr[32];
1667         int hdrlen = sizeof(hdr);
1668
1669         /* Normally if we have it in the pack then we do not bother writing
1670          * it out into .git/objects/??/?{38} file.
1671          */
1672         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1673         if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
1674                 return 0;
1675         return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
1676 }
1677
1678 int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
1679                              struct object_id *oid, unsigned flags)
1680 {
1681         char *header;
1682         int hdrlen, status = 0;
1683
1684         /* type string, SP, %lu of the length plus NUL must fit this */
1685         hdrlen = strlen(type) + 32;
1686         header = xmalloc(hdrlen);
1687         write_sha1_file_prepare(buf, len, type, oid->hash, header, &hdrlen);
1688
1689         if (!(flags & HASH_WRITE_OBJECT))
1690                 goto cleanup;
1691         if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1692                 goto cleanup;
1693         status = write_loose_object(oid->hash, header, hdrlen, buf, len, 0);
1694
1695 cleanup:
1696         free(header);
1697         return status;
1698 }
1699
1700 int force_object_loose(const unsigned char *sha1, time_t mtime)
1701 {
1702         void *buf;
1703         unsigned long len;
1704         enum object_type type;
1705         char hdr[32];
1706         int hdrlen;
1707         int ret;
1708
1709         if (has_loose_object(sha1))
1710                 return 0;
1711         buf = read_object(sha1, &type, &len);
1712         if (!buf)
1713                 return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1714         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(type), len) + 1;
1715         ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
1716         free(buf);
1717
1718         return ret;
1719 }
1720
1721 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
1722 {
1723         if (!startup_info->have_repository)
1724                 return 0;
1725         return sha1_object_info_extended(sha1, NULL,
1726                                          flags | OBJECT_INFO_SKIP_CACHED) >= 0;
1727 }
1728
1729 int has_object_file(const struct object_id *oid)
1730 {
1731         return has_sha1_file(oid->hash);
1732 }
1733
1734 int has_object_file_with_flags(const struct object_id *oid, int flags)
1735 {
1736         return has_sha1_file_with_flags(oid->hash, flags);
1737 }
1738
1739 static void check_tree(const void *buf, size_t size)
1740 {
1741         struct tree_desc desc;
1742         struct name_entry entry;
1743
1744         init_tree_desc(&desc, buf, size);
1745         while (tree_entry(&desc, &entry))
1746                 /* do nothing
1747                  * tree_entry() will die() on malformed entries */
1748                 ;
1749 }
1750
1751 static void check_commit(const void *buf, size_t size)
1752 {
1753         struct commit c;
1754         memset(&c, 0, sizeof(c));
1755         if (parse_commit_buffer(&c, buf, size))
1756                 die("corrupt commit");
1757 }
1758
1759 static void check_tag(const void *buf, size_t size)
1760 {
1761         struct tag t;
1762         memset(&t, 0, sizeof(t));
1763         if (parse_tag_buffer(&t, buf, size))
1764                 die("corrupt tag");
1765 }
1766
1767 static int index_mem(struct object_id *oid, void *buf, size_t size,
1768                      enum object_type type,
1769                      const char *path, unsigned flags)
1770 {
1771         int ret, re_allocated = 0;
1772         int write_object = flags & HASH_WRITE_OBJECT;
1773
1774         if (!type)
1775                 type = OBJ_BLOB;
1776
1777         /*
1778          * Convert blobs to git internal format
1779          */
1780         if ((type == OBJ_BLOB) && path) {
1781                 struct strbuf nbuf = STRBUF_INIT;
1782                 if (convert_to_git(&the_index, path, buf, size, &nbuf,
1783                                    get_conv_flags(flags))) {
1784                         buf = strbuf_detach(&nbuf, &size);
1785                         re_allocated = 1;
1786                 }
1787         }
1788         if (flags & HASH_FORMAT_CHECK) {
1789                 if (type == OBJ_TREE)
1790                         check_tree(buf, size);
1791                 if (type == OBJ_COMMIT)
1792                         check_commit(buf, size);
1793                 if (type == OBJ_TAG)
1794                         check_tag(buf, size);
1795         }
1796
1797         if (write_object)
1798                 ret = write_sha1_file(buf, size, typename(type), oid->hash);
1799         else
1800                 ret = hash_sha1_file(buf, size, typename(type), oid->hash);
1801         if (re_allocated)
1802                 free(buf);
1803         return ret;
1804 }
1805
1806 static int index_stream_convert_blob(struct object_id *oid, int fd,
1807                                      const char *path, unsigned flags)
1808 {
1809         int ret;
1810         const int write_object = flags & HASH_WRITE_OBJECT;
1811         struct strbuf sbuf = STRBUF_INIT;
1812
1813         assert(path);
1814         assert(would_convert_to_git_filter_fd(path));
1815
1816         convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
1817                                  get_conv_flags(flags));
1818
1819         if (write_object)
1820                 ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
1821                                       oid->hash);
1822         else
1823                 ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
1824                                      oid->hash);
1825         strbuf_release(&sbuf);
1826         return ret;
1827 }
1828
1829 static int index_pipe(struct object_id *oid, int fd, enum object_type type,
1830                       const char *path, unsigned flags)
1831 {
1832         struct strbuf sbuf = STRBUF_INIT;
1833         int ret;
1834
1835         if (strbuf_read(&sbuf, fd, 4096) >= 0)
1836                 ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
1837         else
1838                 ret = -1;
1839         strbuf_release(&sbuf);
1840         return ret;
1841 }
1842
1843 #define SMALL_FILE_SIZE (32*1024)
1844
1845 static int index_core(struct object_id *oid, int fd, size_t size,
1846                       enum object_type type, const char *path,
1847                       unsigned flags)
1848 {
1849         int ret;
1850
1851         if (!size) {
1852                 ret = index_mem(oid, "", size, type, path, flags);
1853         } else if (size <= SMALL_FILE_SIZE) {
1854                 char *buf = xmalloc(size);
1855                 ssize_t read_result = read_in_full(fd, buf, size);
1856                 if (read_result < 0)
1857                         ret = error_errno("read error while indexing %s",
1858                                           path ? path : "<unknown>");
1859                 else if (read_result != size)
1860                         ret = error("short read while indexing %s",
1861                                     path ? path : "<unknown>");
1862                 else
1863                         ret = index_mem(oid, buf, size, type, path, flags);
1864                 free(buf);
1865         } else {
1866                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1867                 ret = index_mem(oid, buf, size, type, path, flags);
1868                 munmap(buf, size);
1869         }
1870         return ret;
1871 }
1872
1873 /*
1874  * This creates one packfile per large blob unless bulk-checkin
1875  * machinery is "plugged".
1876  *
1877  * This also bypasses the usual "convert-to-git" dance, and that is on
1878  * purpose. We could write a streaming version of the converting
1879  * functions and insert that before feeding the data to fast-import
1880  * (or equivalent in-core API described above). However, that is
1881  * somewhat complicated, as we do not know the size of the filter
1882  * result, which we need to know beforehand when writing a git object.
1883  * Since the primary motivation for trying to stream from the working
1884  * tree file and to avoid mmaping it in core is to deal with large
1885  * binary blobs, they generally do not want to get any conversion, and
1886  * callers should avoid this code path when filters are requested.
1887  */
1888 static int index_stream(struct object_id *oid, int fd, size_t size,
1889                         enum object_type type, const char *path,
1890                         unsigned flags)
1891 {
1892         return index_bulk_checkin(oid->hash, fd, size, type, path, flags);
1893 }
1894
1895 int index_fd(struct object_id *oid, int fd, struct stat *st,
1896              enum object_type type, const char *path, unsigned flags)
1897 {
1898         int ret;
1899
1900         /*
1901          * Call xsize_t() only when needed to avoid potentially unnecessary
1902          * die() for large files.
1903          */
1904         if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
1905                 ret = index_stream_convert_blob(oid, fd, path, flags);
1906         else if (!S_ISREG(st->st_mode))
1907                 ret = index_pipe(oid, fd, type, path, flags);
1908         else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
1909                  (path && would_convert_to_git(&the_index, path)))
1910                 ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
1911                                  flags);
1912         else
1913                 ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
1914                                    flags);
1915         close(fd);
1916         return ret;
1917 }
1918
1919 int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
1920 {
1921         int fd;
1922         struct strbuf sb = STRBUF_INIT;
1923         int rc = 0;
1924
1925         switch (st->st_mode & S_IFMT) {
1926         case S_IFREG:
1927                 fd = open(path, O_RDONLY);
1928                 if (fd < 0)
1929                         return error_errno("open(\"%s\")", path);
1930                 if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
1931                         return error("%s: failed to insert into database",
1932                                      path);
1933                 break;
1934         case S_IFLNK:
1935                 if (strbuf_readlink(&sb, path, st->st_size))
1936                         return error_errno("readlink(\"%s\")", path);
1937                 if (!(flags & HASH_WRITE_OBJECT))
1938                         hash_sha1_file(sb.buf, sb.len, blob_type, oid->hash);
1939                 else if (write_sha1_file(sb.buf, sb.len, blob_type, oid->hash))
1940                         rc = error("%s: failed to insert into database", path);
1941                 strbuf_release(&sb);
1942                 break;
1943         case S_IFDIR:
1944                 return resolve_gitlink_ref(path, "HEAD", oid);
1945         default:
1946                 return error("%s: unsupported file type", path);
1947         }
1948         return rc;
1949 }
1950
1951 int read_pack_header(int fd, struct pack_header *header)
1952 {
1953         if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
1954                 /* "eof before pack header was fully read" */
1955                 return PH_ERROR_EOF;
1956
1957         if (header->hdr_signature != htonl(PACK_SIGNATURE))
1958                 /* "protocol error (pack signature mismatch detected)" */
1959                 return PH_ERROR_PACK_SIGNATURE;
1960         if (!pack_version_ok(header->hdr_version))
1961                 /* "protocol error (pack version unsupported)" */
1962                 return PH_ERROR_PROTOCOL;
1963         return 0;
1964 }
1965
1966 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
1967 {
1968         enum object_type type = sha1_object_info(sha1, NULL);
1969         if (type < 0)
1970                 die("%s is not a valid object", sha1_to_hex(sha1));
1971         if (type != expect)
1972                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
1973                     typename(expect));
1974 }
1975
1976 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
1977                                 struct strbuf *path,
1978                                 each_loose_object_fn obj_cb,
1979                                 each_loose_cruft_fn cruft_cb,
1980                                 each_loose_subdir_fn subdir_cb,
1981                                 void *data)
1982 {
1983         size_t origlen, baselen;
1984         DIR *dir;
1985         struct dirent *de;
1986         int r = 0;
1987         struct object_id oid;
1988
1989         if (subdir_nr > 0xff)
1990                 BUG("invalid loose object subdirectory: %x", subdir_nr);
1991
1992         origlen = path->len;
1993         strbuf_complete(path, '/');
1994         strbuf_addf(path, "%02x", subdir_nr);
1995
1996         dir = opendir(path->buf);
1997         if (!dir) {
1998                 if (errno != ENOENT)
1999                         r = error_errno("unable to open %s", path->buf);
2000                 strbuf_setlen(path, origlen);
2001                 return r;
2002         }
2003
2004         oid.hash[0] = subdir_nr;
2005         strbuf_addch(path, '/');
2006         baselen = path->len;
2007
2008         while ((de = readdir(dir))) {
2009                 size_t namelen;
2010                 if (is_dot_or_dotdot(de->d_name))
2011                         continue;
2012
2013                 namelen = strlen(de->d_name);
2014                 strbuf_setlen(path, baselen);
2015                 strbuf_add(path, de->d_name, namelen);
2016                 if (namelen == GIT_SHA1_HEXSZ - 2 &&
2017                     !hex_to_bytes(oid.hash + 1, de->d_name,
2018                                   GIT_SHA1_RAWSZ - 1)) {
2019                         if (obj_cb) {
2020                                 r = obj_cb(&oid, path->buf, data);
2021                                 if (r)
2022                                         break;
2023                         }
2024                         continue;
2025                 }
2026
2027                 if (cruft_cb) {
2028                         r = cruft_cb(de->d_name, path->buf, data);
2029                         if (r)
2030                                 break;
2031                 }
2032         }
2033         closedir(dir);
2034
2035         strbuf_setlen(path, baselen - 1);
2036         if (!r && subdir_cb)
2037                 r = subdir_cb(subdir_nr, path->buf, data);
2038
2039         strbuf_setlen(path, origlen);
2040
2041         return r;
2042 }
2043
2044 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
2045                             each_loose_object_fn obj_cb,
2046                             each_loose_cruft_fn cruft_cb,
2047                             each_loose_subdir_fn subdir_cb,
2048                             void *data)
2049 {
2050         int r = 0;
2051         int i;
2052
2053         for (i = 0; i < 256; i++) {
2054                 r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
2055                                                 subdir_cb, data);
2056                 if (r)
2057                         break;
2058         }
2059
2060         return r;
2061 }
2062
2063 int for_each_loose_file_in_objdir(const char *path,
2064                                   each_loose_object_fn obj_cb,
2065                                   each_loose_cruft_fn cruft_cb,
2066                                   each_loose_subdir_fn subdir_cb,
2067                                   void *data)
2068 {
2069         struct strbuf buf = STRBUF_INIT;
2070         int r;
2071
2072         strbuf_addstr(&buf, path);
2073         r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
2074                                               subdir_cb, data);
2075         strbuf_release(&buf);
2076
2077         return r;
2078 }
2079
2080 struct loose_alt_odb_data {
2081         each_loose_object_fn *cb;
2082         void *data;
2083 };
2084
2085 static int loose_from_alt_odb(struct alternate_object_database *alt,
2086                               void *vdata)
2087 {
2088         struct loose_alt_odb_data *data = vdata;
2089         struct strbuf buf = STRBUF_INIT;
2090         int r;
2091
2092         strbuf_addstr(&buf, alt->path);
2093         r = for_each_loose_file_in_objdir_buf(&buf,
2094                                               data->cb, NULL, NULL,
2095                                               data->data);
2096         strbuf_release(&buf);
2097         return r;
2098 }
2099
2100 int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
2101 {
2102         struct loose_alt_odb_data alt;
2103         int r;
2104
2105         r = for_each_loose_file_in_objdir(get_object_directory(),
2106                                           cb, NULL, NULL, data);
2107         if (r)
2108                 return r;
2109
2110         if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
2111                 return 0;
2112
2113         alt.cb = cb;
2114         alt.data = data;
2115         return foreach_alt_odb(loose_from_alt_odb, &alt);
2116 }
2117
2118 static int check_stream_sha1(git_zstream *stream,
2119                              const char *hdr,
2120                              unsigned long size,
2121                              const char *path,
2122                              const unsigned char *expected_sha1)
2123 {
2124         git_SHA_CTX c;
2125         unsigned char real_sha1[GIT_MAX_RAWSZ];
2126         unsigned char buf[4096];
2127         unsigned long total_read;
2128         int status = Z_OK;
2129
2130         git_SHA1_Init(&c);
2131         git_SHA1_Update(&c, hdr, stream->total_out);
2132
2133         /*
2134          * We already read some bytes into hdr, but the ones up to the NUL
2135          * do not count against the object's content size.
2136          */
2137         total_read = stream->total_out - strlen(hdr) - 1;
2138
2139         /*
2140          * This size comparison must be "<=" to read the final zlib packets;
2141          * see the comment in unpack_sha1_rest for details.
2142          */
2143         while (total_read <= size &&
2144                (status == Z_OK || status == Z_BUF_ERROR)) {
2145                 stream->next_out = buf;
2146                 stream->avail_out = sizeof(buf);
2147                 if (size - total_read < stream->avail_out)
2148                         stream->avail_out = size - total_read;
2149                 status = git_inflate(stream, Z_FINISH);
2150                 git_SHA1_Update(&c, buf, stream->next_out - buf);
2151                 total_read += stream->next_out - buf;
2152         }
2153         git_inflate_end(stream);
2154
2155         if (status != Z_STREAM_END) {
2156                 error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
2157                 return -1;
2158         }
2159         if (stream->avail_in) {
2160                 error("garbage at end of loose object '%s'",
2161                       sha1_to_hex(expected_sha1));
2162                 return -1;
2163         }
2164
2165         git_SHA1_Final(real_sha1, &c);
2166         if (hashcmp(expected_sha1, real_sha1)) {
2167                 error("sha1 mismatch for %s (expected %s)", path,
2168                       sha1_to_hex(expected_sha1));
2169                 return -1;
2170         }
2171
2172         return 0;
2173 }
2174
2175 int read_loose_object(const char *path,
2176                       const unsigned char *expected_sha1,
2177                       enum object_type *type,
2178                       unsigned long *size,
2179                       void **contents)
2180 {
2181         int ret = -1;
2182         void *map = NULL;
2183         unsigned long mapsize;
2184         git_zstream stream;
2185         char hdr[32];
2186
2187         *contents = NULL;
2188
2189         map = map_sha1_file_1(path, NULL, &mapsize);
2190         if (!map) {
2191                 error_errno("unable to mmap %s", path);
2192                 goto out;
2193         }
2194
2195         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
2196                 error("unable to unpack header of %s", path);
2197                 goto out;
2198         }
2199
2200         *type = parse_sha1_header(hdr, size);
2201         if (*type < 0) {
2202                 error("unable to parse header of %s", path);
2203                 git_inflate_end(&stream);
2204                 goto out;
2205         }
2206
2207         if (*type == OBJ_BLOB) {
2208                 if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
2209                         goto out;
2210         } else {
2211                 *contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
2212                 if (!*contents) {
2213                         error("unable to unpack contents of %s", path);
2214                         git_inflate_end(&stream);
2215                         goto out;
2216                 }
2217                 if (check_sha1_signature(expected_sha1, *contents,
2218                                          *size, typename(*type))) {
2219                         error("sha1 mismatch for %s (expected %s)", path,
2220                               sha1_to_hex(expected_sha1));
2221                         free(*contents);
2222                         goto out;
2223                 }
2224         }
2225
2226         ret = 0; /* everything checks out */
2227
2228 out:
2229         if (map)
2230                 munmap(map, mapsize);
2231         return ret;
2232 }