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