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