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