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(git_hash_ctx *ctx)
  43 {
  44         git_SHA1_Init(&ctx->sha1);
  45 }
  46
  47 static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
  48 {
  49         git_SHA1_Update(&ctx->sha1, data, len);
  50 }
  51
  52 static void git_hash_sha1_final(unsigned char *hash, git_hash_ctx *ctx)
  53 {
  54         git_SHA1_Final(hash, &ctx->sha1);
  55 }
  56
  57 static void git_hash_unknown_init(git_hash_ctx *ctx)
  58 {
  59         die("trying to init unknown hash");
  60 }
  61
  62 static void git_hash_unknown_update(git_hash_ctx *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, git_hash_ctx *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                 git_hash_unknown_init,
  79                 git_hash_unknown_update,
  80                 git_hash_unknown_final,
  81                 NULL,
  82                 NULL,
  83         },
  84         {
  85                 "sha-1",
  86                 /* "sha1", big-endian */
  87                 0x73686131,
  88                 GIT_SHA1_RAWSZ,
  89                 GIT_SHA1_HEXSZ,
  90                 git_hash_sha1_init,
  91                 git_hash_sha1_update,
  92                 git_hash_sha1_final,
  93                 &empty_tree_oid,
  94                 &empty_blob_oid,
  95         },
  96 };
  97
  98 /*
  99  * This is meant to hold a *small* number of objects that you would
 100  * want read_sha1_file() to be able to return, but yet you do not want
 101  * to write them into the object store (e.g. a browse-only
 102  * application).
 103  */
 104 static struct cached_object {
 105         unsigned char sha1[20];
 106         enum object_type type;
 107         void *buf;
 108         unsigned long size;
 109 } *cached_objects;
 110 static int cached_object_nr, cached_object_alloc;
 111
 112 static struct cached_object empty_tree = {
 113         EMPTY_TREE_SHA1_BIN_LITERAL,
 114         OBJ_TREE,
 115         "",
 116         0
 117 };
 118
 119 static struct cached_object *find_cached_object(const unsigned char *sha1)
 120 {
 121         int i;
 122         struct cached_object *co = cached_objects;
 123
 124         for (i = 0; i < cached_object_nr; i++, co++) {
 125                 if (!hashcmp(co->sha1, sha1))
 126                         return co;
 127         }
 128         if (!hashcmp(sha1, empty_tree.sha1))
 129                 return &empty_tree;
 130         return NULL;
 131 }
 132
 133
 134 static int get_conv_flags(unsigned flags)
 135 {
 136         if (flags & HASH_RENORMALIZE)
 137                 return CONV_EOL_RENORMALIZE;
 138         else if (flags & HASH_WRITE_OBJECT)
 139           return global_conv_flags_eol;
 140         else
 141                 return 0;
 142 }
 143
 144
 145 int mkdir_in_gitdir(const char *path)
 146 {
 147         if (mkdir(path, 0777)) {
 148                 int saved_errno = errno;
 149                 struct stat st;
 150                 struct strbuf sb = STRBUF_INIT;
 151
 152                 if (errno != EEXIST)
 153                         return -1;
 154                 /*
 155                  * Are we looking at a path in a symlinked worktree
 156                  * whose original repository does not yet have it?
 157                  * e.g. .git/rr-cache pointing at its original
 158                  * repository in which the user hasn't performed any
 159                  * conflict resolution yet?
 160                  */
 161                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 162                     strbuf_readlink(&sb, path, st.st_size) ||
 163                     !is_absolute_path(sb.buf) ||
 164                     mkdir(sb.buf, 0777)) {
 165                         strbuf_release(&sb);
 166                         errno = saved_errno;
 167                         return -1;
 168                 }
 169                 strbuf_release(&sb);
 170         }
 171         return adjust_shared_perm(path);
 172 }
 173
 174 enum scld_error safe_create_leading_directories(char *path)
 175 {
 176         char *next_component = path + offset_1st_component(path);
 177         enum scld_error ret = SCLD_OK;
 178
 179         while (ret == SCLD_OK && next_component) {
 180                 struct stat st;
 181                 char *slash = next_component, slash_character;
 182
 183                 while (*slash && !is_dir_sep(*slash))
 184                         slash++;
 185
 186                 if (!*slash)
 187                         break;
 188
 189                 next_component = slash + 1;
 190                 while (is_dir_sep(*next_component))
 191                         next_component++;
 192                 if (!*next_component)
 193                         break;
 194
 195                 slash_character = *slash;
 196                 *slash = '\0';
 197                 if (!stat(path, &st)) {
 198                         /* path exists */
 199                         if (!S_ISDIR(st.st_mode)) {
 200                                 errno = ENOTDIR;
 201                                 ret = SCLD_EXISTS;
 202                         }
 203                 } else if (mkdir(path, 0777)) {
 204                         if (errno == EEXIST &&
 205                             !stat(path, &st) && S_ISDIR(st.st_mode))
 206                                 ; /* somebody created it since we checked */
 207                         else if (errno == ENOENT)
 208                                 /*
 209                                  * Either mkdir() failed because
 210                                  * somebody just pruned the containing
 211                                  * directory, or stat() failed because
 212                                  * the file that was in our way was
 213                                  * just removed.  Either way, inform
 214                                  * the caller that it might be worth
 215                                  * trying again:
 216                                  */
 217                                 ret = SCLD_VANISHED;
 218                         else
 219                                 ret = SCLD_FAILED;
 220                 } else if (adjust_shared_perm(path)) {
 221                         ret = SCLD_PERMS;
 222                 }
 223                 *slash = slash_character;
 224         }
 225         return ret;
 226 }
 227
 228 enum scld_error safe_create_leading_directories_const(const char *path)
 229 {
 230         int save_errno;
 231         /* path points to cache entries, so xstrdup before messing with it */
 232         char *buf = xstrdup(path);
 233         enum scld_error result = safe_create_leading_directories(buf);
 234
 235         save_errno = errno;
 236         free(buf);
 237         errno = save_errno;
 238         return result;
 239 }
 240
 241 int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 242 {
 243         /*
 244          * The number of times we will try to remove empty directories
 245          * in the way of path. This is only 1 because if another
 246          * process is racily creating directories that conflict with
 247          * us, we don't want to fight against them.
 248          */
 249         int remove_directories_remaining = 1;
 250
 251         /*
 252          * The number of times that we will try to create the
 253          * directories containing path. We are willing to attempt this
 254          * more than once, because another process could be trying to
 255          * clean up empty directories at the same time as we are
 256          * trying to create them.
 257          */
 258         int create_directories_remaining = 3;
 259
 260         /* A scratch copy of path, filled lazily if we need it: */
 261         struct strbuf path_copy = STRBUF_INIT;
 262
 263         int ret, save_errno;
 264
 265         /* Sanity check: */
 266         assert(*path);
 267
 268 retry_fn:
 269         ret = fn(path, cb);
 270         save_errno = errno;
 271         if (!ret)
 272                 goto out;
 273
 274         if (errno == EISDIR && remove_directories_remaining-- > 0) {
 275                 /*
 276                  * A directory is in the way. Maybe it is empty; try
 277                  * to remove it:
 278                  */
 279                 if (!path_copy.len)
 280                         strbuf_addstr(&path_copy, path);
 281
 282                 if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 283                         goto retry_fn;
 284         } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 285                 /*
 286                  * Maybe the containing directory didn't exist, or
 287                  * maybe it was just deleted by a process that is
 288                  * racing with us to clean up empty directories. Try
 289                  * to create it:
 290                  */
 291                 enum scld_error scld_result;
 292
 293                 if (!path_copy.len)
 294                         strbuf_addstr(&path_copy, path);
 295
 296                 do {
 297                         scld_result = safe_create_leading_directories(path_copy.buf);
 298                         if (scld_result == SCLD_OK)
 299                                 goto retry_fn;
 300                 } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 301         }
 302
 303 out:
 304         strbuf_release(&path_copy);
 305         errno = save_errno;
 306         return ret;
 307 }
 308
 309 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 310 {
 311         int i;
 312         for (i = 0; i < 20; i++) {
 313                 static char hex[] = "0123456789abcdef";
 314                 unsigned int val = sha1[i];
 315                 strbuf_addch(buf, hex[val >> 4]);
 316                 strbuf_addch(buf, hex[val & 0xf]);
 317                 if (!i)
 318                         strbuf_addch(buf, '/');
 319         }
 320 }
 321
 322 void sha1_file_name(struct strbuf *buf, const unsigned char *sha1)
 323 {
 324         strbuf_addstr(buf, get_object_directory());
 325         strbuf_addch(buf, '/');
 326         fill_sha1_path(buf, sha1);
 327 }
 328
 329 struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 330 {
 331         strbuf_setlen(&alt->scratch, alt->base_len);
 332         return &alt->scratch;
 333 }
 334
 335 static const char *alt_sha1_path(struct alternate_object_database *alt,
 336                                  const unsigned char *sha1)
 337 {
 338         struct strbuf *buf = alt_scratch_buf(alt);
 339         fill_sha1_path(buf, sha1);
 340         return buf->buf;
 341 }
 342
 343 struct alternate_object_database *alt_odb_list;
 344 static struct alternate_object_database **alt_odb_tail;
 345
 346 /*
 347  * Return non-zero iff the path is usable as an alternate object database.
 348  */
 349 static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
 350 {
 351         struct alternate_object_database *alt;
 352
 353         /* Detect cases where alternate disappeared */
 354         if (!is_directory(path->buf)) {
 355                 error("object directory %s does not exist; "
 356                       "check .git/objects/info/alternates.",
 357                       path->buf);
 358                 return 0;
 359         }
 360
 361         /*
 362          * Prevent the common mistake of listing the same
 363          * thing twice, or object directory itself.
 364          */
 365         for (alt = alt_odb_list; alt; alt = alt->next) {
 366                 if (!fspathcmp(path->buf, alt->path))
 367                         return 0;
 368         }
 369         if (!fspathcmp(path->buf, normalized_objdir))
 370                 return 0;
 371
 372         return 1;
 373 }
 374
 375 /*
 376  * Prepare alternate object database registry.
 377  *
 378  * The variable alt_odb_list points at the list of struct
 379  * alternate_object_database.  The elements on this list come from
 380  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 381  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 382  * whose contents is similar to that environment variable but can be
 383  * LF separated.  Its base points at a statically allocated buffer that
 384  * contains "/the/directory/corresponding/to/.git/objects/...", while
 385  * its name points just after the slash at the end of ".git/objects/"
 386  * in the example above, and has enough space to hold 40-byte hex
 387  * SHA1, an extra slash for the first level indirection, and the
 388  * terminating NUL.
 389  */
 390 static void read_info_alternates(const char * relative_base, int depth);
 391 static int link_alt_odb_entry(const char *entry, const char *relative_base,
 392         int depth, const char *normalized_objdir)
 393 {
 394         struct alternate_object_database *ent;
 395         struct strbuf pathbuf = STRBUF_INIT;
 396
 397         if (!is_absolute_path(entry) && relative_base) {
 398                 strbuf_realpath(&pathbuf, relative_base, 1);
 399                 strbuf_addch(&pathbuf, '/');
 400         }
 401         strbuf_addstr(&pathbuf, entry);
 402
 403         if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 404                 error("unable to normalize alternate object path: %s",
 405                       pathbuf.buf);
 406                 strbuf_release(&pathbuf);
 407                 return -1;
 408         }
 409
 410         /*
 411          * The trailing slash after the directory name is given by
 412          * this function at the end. Remove duplicates.
 413          */
 414         while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 415                 strbuf_setlen(&pathbuf, pathbuf.len - 1);
 416
 417         if (!alt_odb_usable(&pathbuf, normalized_objdir)) {
 418                 strbuf_release(&pathbuf);
 419                 return -1;
 420         }
 421
 422         ent = alloc_alt_odb(pathbuf.buf);
 423
 424         /* add the alternate entry */
 425         *alt_odb_tail = ent;
 426         alt_odb_tail = &(ent->next);
 427         ent->next = NULL;
 428
 429         /* recursively add alternates */
 430         read_info_alternates(pathbuf.buf, depth + 1);
 431
 432         strbuf_release(&pathbuf);
 433         return 0;
 434 }
 435
 436 static const char *parse_alt_odb_entry(const char *string,
 437                                        int sep,
 438                                        struct strbuf *out)
 439 {
 440         const char *end;
 441
 442         strbuf_reset(out);
 443
 444         if (*string == '#') {
 445                 /* comment; consume up to next separator */
 446                 end = strchrnul(string, sep);
 447         } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 448                 /*
 449                  * quoted path; unquote_c_style has copied the
 450                  * data for us and set "end". Broken quoting (e.g.,
 451                  * an entry that doesn't end with a quote) falls
 452                  * back to the unquoted case below.
 453                  */
 454         } else {
 455                 /* normal, unquoted path */
 456                 end = strchrnul(string, sep);
 457                 strbuf_add(out, string, end - string);
 458         }
 459
 460         if (*end)
 461                 end++;
 462         return end;
 463 }
 464
 465 static void link_alt_odb_entries(const char *alt, int sep,
 466                                  const char *relative_base, int depth)
 467 {
 468         struct strbuf objdirbuf = STRBUF_INIT;
 469         struct strbuf entry = STRBUF_INIT;
 470
 471         if (!alt || !*alt)
 472                 return;
 473
 474         if (depth > 5) {
 475                 error("%s: ignoring alternate object stores, nesting too deep.",
 476                                 relative_base);
 477                 return;
 478         }
 479
 480         strbuf_add_absolute_path(&objdirbuf, get_object_directory());
 481         if (strbuf_normalize_path(&objdirbuf) < 0)
 482                 die("unable to normalize object directory: %s",
 483                     objdirbuf.buf);
 484
 485         while (*alt) {
 486                 alt = parse_alt_odb_entry(alt, sep, &entry);
 487                 if (!entry.len)
 488                         continue;
 489                 link_alt_odb_entry(entry.buf, relative_base, depth, objdirbuf.buf);
 490         }
 491         strbuf_release(&entry);
 492         strbuf_release(&objdirbuf);
 493 }
 494
 495 static void read_info_alternates(const char * relative_base, int depth)
 496 {
 497         char *path;
 498         struct strbuf buf = STRBUF_INIT;
 499
 500         path = xstrfmt("%s/info/alternates", relative_base);
 501         if (strbuf_read_file(&buf, path, 1024) < 0) {
 502                 warn_on_fopen_errors(path);
 503                 free(path);
 504                 return;
 505         }
 506
 507         link_alt_odb_entries(buf.buf, '\n', relative_base, depth);
 508         strbuf_release(&buf);
 509         free(path);
 510 }
 511
 512 struct alternate_object_database *alloc_alt_odb(const char *dir)
 513 {
 514         struct alternate_object_database *ent;
 515
 516         FLEX_ALLOC_STR(ent, path, dir);
 517         strbuf_init(&ent->scratch, 0);
 518         strbuf_addf(&ent->scratch, "%s/", dir);
 519         ent->base_len = ent->scratch.len;
 520
 521         return ent;
 522 }
 523
 524 void add_to_alternates_file(const char *reference)
 525 {
 526         struct lock_file lock = LOCK_INIT;
 527         char *alts = git_pathdup("objects/info/alternates");
 528         FILE *in, *out;
 529         int found = 0;
 530
 531         hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 532         out = fdopen_lock_file(&lock, "w");
 533         if (!out)
 534                 die_errno("unable to fdopen alternates lockfile");
 535
 536         in = fopen(alts, "r");
 537         if (in) {
 538                 struct strbuf line = STRBUF_INIT;
 539
 540                 while (strbuf_getline(&line, in) != EOF) {
 541                         if (!strcmp(reference, line.buf)) {
 542                                 found = 1;
 543                                 break;
 544                         }
 545                         fprintf_or_die(out, "%s\n", line.buf);
 546                 }
 547
 548                 strbuf_release(&line);
 549                 fclose(in);
 550         }
 551         else if (errno != ENOENT)
 552                 die_errno("unable to read alternates file");
 553
 554         if (found) {
 555                 rollback_lock_file(&lock);
 556         } else {
 557                 fprintf_or_die(out, "%s\n", reference);
 558                 if (commit_lock_file(&lock))
 559                         die_errno("unable to move new alternates file into place");
 560                 if (alt_odb_tail)
 561                         link_alt_odb_entries(reference, '\n', NULL, 0);
 562         }
 563         free(alts);
 564 }
 565
 566 void add_to_alternates_memory(const char *reference)
 567 {
 568         /*
 569          * Make sure alternates are initialized, or else our entry may be
 570          * overwritten when they are.
 571          */
 572         prepare_alt_odb();
 573
 574         link_alt_odb_entries(reference, '\n', NULL, 0);
 575 }
 576
 577 /*
 578  * Compute the exact path an alternate is at and returns it. In case of
 579  * error NULL is returned and the human readable error is added to `err`
 580  * `path` may be relative and should point to $GITDIR.
 581  * `err` must not be null.
 582  */
 583 char *compute_alternate_path(const char *path, struct strbuf *err)
 584 {
 585         char *ref_git = NULL;
 586         const char *repo, *ref_git_s;
 587         int seen_error = 0;
 588
 589         ref_git_s = real_path_if_valid(path);
 590         if (!ref_git_s) {
 591                 seen_error = 1;
 592                 strbuf_addf(err, _("path '%s' does not exist"), path);
 593                 goto out;
 594         } else
 595                 /*
 596                  * Beware: read_gitfile(), real_path() and mkpath()
 597                  * return static buffer
 598                  */
 599                 ref_git = xstrdup(ref_git_s);
 600
 601         repo = read_gitfile(ref_git);
 602         if (!repo)
 603                 repo = read_gitfile(mkpath("%s/.git", ref_git));
 604         if (repo) {
 605                 free(ref_git);
 606                 ref_git = xstrdup(repo);
 607         }
 608
 609         if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 610                 char *ref_git_git = mkpathdup("%s/.git", ref_git);
 611                 free(ref_git);
 612                 ref_git = ref_git_git;
 613         } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 614                 struct strbuf sb = STRBUF_INIT;
 615                 seen_error = 1;
 616                 if (get_common_dir(&sb, ref_git)) {
 617                         strbuf_addf(err,
 618                                     _("reference repository '%s' as a linked "
 619                                       "checkout is not supported yet."),
 620                                     path);
 621                         goto out;
 622                 }
 623
 624                 strbuf_addf(err, _("reference repository '%s' is not a "
 625                                         "local repository."), path);
 626                 goto out;
 627         }
 628
 629         if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 630                 strbuf_addf(err, _("reference repository '%s' is shallow"),
 631                             path);
 632                 seen_error = 1;
 633                 goto out;
 634         }
 635
 636         if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 637                 strbuf_addf(err,
 638                             _("reference repository '%s' is grafted"),
 639                             path);
 640                 seen_error = 1;
 641                 goto out;
 642         }
 643
 644 out:
 645         if (seen_error) {
 646                 FREE_AND_NULL(ref_git);
 647         }
 648
 649         return ref_git;
 650 }
 651
 652 int foreach_alt_odb(alt_odb_fn fn, void *cb)
 653 {
 654         struct alternate_object_database *ent;
 655         int r = 0;
 656
 657         prepare_alt_odb();
 658         for (ent = alt_odb_list; ent; ent = ent->next) {
 659                 r = fn(ent, cb);
 660                 if (r)
 661                         break;
 662         }
 663         return r;
 664 }
 665
 666 void prepare_alt_odb(void)
 667 {
 668         const char *alt;
 669
 670         if (alt_odb_tail)
 671                 return;
 672
 673         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 674
 675         alt_odb_tail = &alt_odb_list;
 676         link_alt_odb_entries(alt, PATH_SEP, NULL, 0);
 677
 678         read_info_alternates(get_object_directory(), 0);
 679 }
 680
 681 /* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 682 static int freshen_file(const char *fn)
 683 {
 684         struct utimbuf t;
 685         t.actime = t.modtime = time(NULL);
 686         return !utime(fn, &t);
 687 }
 688
 689 /*
 690  * All of the check_and_freshen functions return 1 if the file exists and was
 691  * freshened (if freshening was requested), 0 otherwise. If they return
 692  * 0, you should not assume that it is safe to skip a write of the object (it
 693  * either does not exist on disk, or has a stale mtime and may be subject to
 694  * pruning).
 695  */
 696 int check_and_freshen_file(const char *fn, int freshen)
 697 {
 698         if (access(fn, F_OK))
 699                 return 0;
 700         if (freshen && !freshen_file(fn))
 701                 return 0;
 702         return 1;
 703 }
 704
 705 static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 706 {
 707         static struct strbuf buf = STRBUF_INIT;
 708
 709         strbuf_reset(&buf);
 710         sha1_file_name(&buf, sha1);
 711
 712         return check_and_freshen_file(buf.buf, freshen);
 713 }
 714
 715 static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 716 {
 717         struct alternate_object_database *alt;
 718         prepare_alt_odb();
 719         for (alt = alt_odb_list; alt; alt = alt->next) {
 720                 const char *path = alt_sha1_path(alt, sha1);
 721                 if (check_and_freshen_file(path, freshen))
 722                         return 1;
 723         }
 724         return 0;
 725 }
 726
 727 static int check_and_freshen(const unsigned char *sha1, int freshen)
 728 {
 729         return check_and_freshen_local(sha1, freshen) ||
 730                check_and_freshen_nonlocal(sha1, freshen);
 731 }
 732
 733 int has_loose_object_nonlocal(const unsigned char *sha1)
 734 {
 735         return check_and_freshen_nonlocal(sha1, 0);
 736 }
 737
 738 static int has_loose_object(const unsigned char *sha1)
 739 {
 740         return check_and_freshen(sha1, 0);
 741 }
 742
 743 static void mmap_limit_check(size_t length)
 744 {
 745         static size_t limit = 0;
 746         if (!limit) {
 747                 limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 748                 if (!limit)
 749                         limit = SIZE_MAX;
 750         }
 751         if (length > limit)
 752                 die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 753                     (uintmax_t)length, (uintmax_t)limit);
 754 }
 755
 756 void *xmmap_gently(void *start, size_t length,
 757                   int prot, int flags, int fd, off_t offset)
 758 {
 759         void *ret;
 760
 761         mmap_limit_check(length);
 762         ret = mmap(start, length, prot, flags, fd, offset);
 763         if (ret == MAP_FAILED) {
 764                 if (!length)
 765                         return NULL;
 766                 release_pack_memory(length);
 767                 ret = mmap(start, length, prot, flags, fd, offset);
 768         }
 769         return ret;
 770 }
 771
 772 void *xmmap(void *start, size_t length,
 773         int prot, int flags, int fd, off_t offset)
 774 {
 775         void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 776         if (ret == MAP_FAILED)
 777                 die_errno("mmap failed");
 778         return ret;
 779 }
 780
 781 /*
 782  * With an in-core object data in "map", rehash it to make sure the
 783  * object name actually matches "sha1" to detect object corruption.
 784  * With "map" == NULL, try reading the object named with "sha1" using
 785  * the streaming interface and rehash it to do the same.
 786  */
 787 int check_sha1_signature(const unsigned char *sha1, void *map,
 788                          unsigned long size, const char *type)
 789 {
 790         struct object_id real_oid;
 791         enum object_type obj_type;
 792         struct git_istream *st;
 793         git_hash_ctx c;
 794         char hdr[32];
 795         int hdrlen;
 796
 797         if (map) {
 798                 hash_object_file(map, size, type, &real_oid);
 799                 return hashcmp(sha1, real_oid.hash) ? -1 : 0;
 800         }
 801
 802         st = open_istream(sha1, &obj_type, &size, NULL);
 803         if (!st)
 804                 return -1;
 805
 806         /* Generate the header */
 807         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(obj_type), size) + 1;
 808
 809         /* Sha1.. */
 810         the_hash_algo->init_fn(&c);
 811         the_hash_algo->update_fn(&c, hdr, hdrlen);
 812         for (;;) {
 813                 char buf[1024 * 16];
 814                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 815
 816                 if (readlen < 0) {
 817                         close_istream(st);
 818                         return -1;
 819                 }
 820                 if (!readlen)
 821                         break;
 822                 the_hash_algo->update_fn(&c, buf, readlen);
 823         }
 824         the_hash_algo->final_fn(real_oid.hash, &c);
 825         close_istream(st);
 826         return hashcmp(sha1, real_oid.hash) ? -1 : 0;
 827 }
 828
 829 int git_open_cloexec(const char *name, int flags)
 830 {
 831         int fd;
 832         static int o_cloexec = O_CLOEXEC;
 833
 834         fd = open(name, flags | o_cloexec);
 835         if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 836                 /* Try again w/o O_CLOEXEC: the kernel might not support it */
 837                 o_cloexec &= ~O_CLOEXEC;
 838                 fd = open(name, flags | o_cloexec);
 839         }
 840
 841 #if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 842         {
 843                 static int fd_cloexec = FD_CLOEXEC;
 844
 845                 if (!o_cloexec && 0 <= fd && fd_cloexec) {
 846                         /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 847                         int flags = fcntl(fd, F_GETFD);
 848                         if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 849                                 fd_cloexec = 0;
 850                 }
 851         }
 852 #endif
 853         return fd;
 854 }
 855
 856 /*
 857  * Find "sha1" as a loose object in the local repository or in an alternate.
 858  * Returns 0 on success, negative on failure.
 859  *
 860  * The "path" out-parameter will give the path of the object we found (if any).
 861  * Note that it may point to static storage and is only valid until another
 862  * call to sha1_file_name(), etc.
 863  */
 864 static int stat_sha1_file(const unsigned char *sha1, struct stat *st,
 865                           const char **path)
 866 {
 867         struct alternate_object_database *alt;
 868         static struct strbuf buf = STRBUF_INIT;
 869
 870         strbuf_reset(&buf);
 871         sha1_file_name(&buf, sha1);
 872         *path = buf.buf;
 873
 874         if (!lstat(*path, st))
 875                 return 0;
 876
 877         prepare_alt_odb();
 878         errno = ENOENT;
 879         for (alt = alt_odb_list; alt; alt = alt->next) {
 880                 *path = alt_sha1_path(alt, sha1);
 881                 if (!lstat(*path, st))
 882                         return 0;
 883         }
 884
 885         return -1;
 886 }
 887
 888 /*
 889  * Like stat_sha1_file(), but actually open the object and return the
 890  * descriptor. See the caveats on the "path" parameter above.
 891  */
 892 static int open_sha1_file(const unsigned char *sha1, const char **path)
 893 {
 894         int fd;
 895         struct alternate_object_database *alt;
 896         int most_interesting_errno;
 897         static struct strbuf buf = STRBUF_INIT;
 898
 899         strbuf_reset(&buf);
 900         sha1_file_name(&buf, sha1);
 901         *path = buf.buf;
 902
 903         fd = git_open(*path);
 904         if (fd >= 0)
 905                 return fd;
 906         most_interesting_errno = errno;
 907
 908         prepare_alt_odb();
 909         for (alt = alt_odb_list; alt; alt = alt->next) {
 910                 *path = alt_sha1_path(alt, sha1);
 911                 fd = git_open(*path);
 912                 if (fd >= 0)
 913                         return fd;
 914                 if (most_interesting_errno == ENOENT)
 915                         most_interesting_errno = errno;
 916         }
 917         errno = most_interesting_errno;
 918         return -1;
 919 }
 920
 921 /*
 922  * Map the loose object at "path" if it is not NULL, or the path found by
 923  * searching for a loose object named "sha1".
 924  */
 925 static void *map_sha1_file_1(const char *path,
 926                              const unsigned char *sha1,
 927                              unsigned long *size)
 928 {
 929         void *map;
 930         int fd;
 931
 932         if (path)
 933                 fd = git_open(path);
 934         else
 935                 fd = open_sha1_file(sha1, &path);
 936         map = NULL;
 937         if (fd >= 0) {
 938                 struct stat st;
 939
 940                 if (!fstat(fd, &st)) {
 941                         *size = xsize_t(st.st_size);
 942                         if (!*size) {
 943                                 /* mmap() is forbidden on empty files */
 944                                 error("object file %s is empty", path);
 945                                 return NULL;
 946                         }
 947                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 948                 }
 949                 close(fd);
 950         }
 951         return map;
 952 }
 953
 954 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 955 {
 956         return map_sha1_file_1(NULL, sha1, size);
 957 }
 958
 959 static int unpack_sha1_short_header(git_zstream *stream,
 960                                     unsigned char *map, unsigned long mapsize,
 961                                     void *buffer, unsigned long bufsiz)
 962 {
 963         /* Get the data stream */
 964         memset(stream, 0, sizeof(*stream));
 965         stream->next_in = map;
 966         stream->avail_in = mapsize;
 967         stream->next_out = buffer;
 968         stream->avail_out = bufsiz;
 969
 970         git_inflate_init(stream);
 971         return git_inflate(stream, 0);
 972 }
 973
 974 int unpack_sha1_header(git_zstream *stream,
 975                        unsigned char *map, unsigned long mapsize,
 976                        void *buffer, unsigned long bufsiz)
 977 {
 978         int status = unpack_sha1_short_header(stream, map, mapsize,
 979                                               buffer, bufsiz);
 980
 981         if (status < Z_OK)
 982                 return status;
 983
 984         /* Make sure we have the terminating NUL */
 985         if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 986                 return -1;
 987         return 0;
 988 }
 989
 990 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
 991                                         unsigned long mapsize, void *buffer,
 992                                         unsigned long bufsiz, struct strbuf *header)
 993 {
 994         int status;
 995
 996         status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
 997         if (status < Z_OK)
 998                 return -1;
 999
1000         /*
1001          * Check if entire header is unpacked in the first iteration.
1002          */
1003         if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1004                 return 0;
1005
1006         /*
1007          * buffer[0..bufsiz] was not large enough.  Copy the partial
1008          * result out to header, and then append the result of further
1009          * reading the stream.
1010          */
1011         strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1012         stream->next_out = buffer;
1013         stream->avail_out = bufsiz;
1014
1015         do {
1016                 status = git_inflate(stream, 0);
1017                 strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1018                 if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1019                         return 0;
1020                 stream->next_out = buffer;
1021                 stream->avail_out = bufsiz;
1022         } while (status != Z_STREAM_END);
1023         return -1;
1024 }
1025
1026 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1027 {
1028         int bytes = strlen(buffer) + 1;
1029         unsigned char *buf = xmallocz(size);
1030         unsigned long n;
1031         int status = Z_OK;
1032
1033         n = stream->total_out - bytes;
1034         if (n > size)
1035                 n = size;
1036         memcpy(buf, (char *) buffer + bytes, n);
1037         bytes = n;
1038         if (bytes <= size) {
1039                 /*
1040                  * The above condition must be (bytes <= size), not
1041                  * (bytes < size).  In other words, even though we
1042                  * expect no more output and set avail_out to zero,
1043                  * the input zlib stream may have bytes that express
1044                  * "this concludes the stream", and we *do* want to
1045                  * eat that input.
1046                  *
1047                  * Otherwise we would not be able to test that we
1048                  * consumed all the input to reach the expected size;
1049                  * we also want to check that zlib tells us that all
1050                  * went well with status == Z_STREAM_END at the end.
1051                  */
1052                 stream->next_out = buf + bytes;
1053                 stream->avail_out = size - bytes;
1054                 while (status == Z_OK)
1055                         status = git_inflate(stream, Z_FINISH);
1056         }
1057         if (status == Z_STREAM_END && !stream->avail_in) {
1058                 git_inflate_end(stream);
1059                 return buf;
1060         }
1061
1062         if (status < 0)
1063                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1064         else if (stream->avail_in)
1065                 error("garbage at end of loose object '%s'",
1066                       sha1_to_hex(sha1));
1067         free(buf);
1068         return NULL;
1069 }
1070
1071 /*
1072  * We used to just use "sscanf()", but that's actually way
1073  * too permissive for what we want to check. So do an anal
1074  * object header parse by hand.
1075  */
1076 static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1077                                unsigned int flags)
1078 {
1079         const char *type_buf = hdr;
1080         unsigned long size;
1081         int type, type_len = 0;
1082
1083         /*
1084          * The type can be of any size but is followed by
1085          * a space.
1086          */
1087         for (;;) {
1088                 char c = *hdr++;
1089                 if (!c)
1090                         return -1;
1091                 if (c == ' ')
1092                         break;
1093                 type_len++;
1094         }
1095
1096         type = type_from_string_gently(type_buf, type_len, 1);
1097         if (oi->type_name)
1098                 strbuf_add(oi->type_name, type_buf, type_len);
1099         /*
1100          * Set type to 0 if its an unknown object and
1101          * we're obtaining the type using '--allow-unknown-type'
1102          * option.
1103          */
1104         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
1105                 type = 0;
1106         else if (type < 0)
1107                 die("invalid object type");
1108         if (oi->typep)
1109                 *oi->typep = type;
1110
1111         /*
1112          * The length must follow immediately, and be in canonical
1113          * decimal format (ie "010" is not valid).
1114          */
1115         size = *hdr++ - '0';
1116         if (size > 9)
1117                 return -1;
1118         if (size) {
1119                 for (;;) {
1120                         unsigned long c = *hdr - '0';
1121                         if (c > 9)
1122                                 break;
1123                         hdr++;
1124                         size = size * 10 + c;
1125                 }
1126         }
1127
1128         if (oi->sizep)
1129                 *oi->sizep = size;
1130
1131         /*
1132          * The length must be followed by a zero byte
1133          */
1134         return *hdr ? -1 : type;
1135 }
1136
1137 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1138 {
1139         struct object_info oi = OBJECT_INFO_INIT;
1140
1141         oi.sizep = sizep;
1142         return parse_sha1_header_extended(hdr, &oi, 0);
1143 }
1144
1145 static int sha1_loose_object_info(const unsigned char *sha1,
1146                                   struct object_info *oi,
1147                                   int flags)
1148 {
1149         int status = 0;
1150         unsigned long mapsize;
1151         void *map;
1152         git_zstream stream;
1153         char hdr[32];
1154         struct strbuf hdrbuf = STRBUF_INIT;
1155         unsigned long size_scratch;
1156
1157         if (oi->delta_base_sha1)
1158                 hashclr(oi->delta_base_sha1);
1159
1160         /*
1161          * If we don't care about type or size, then we don't
1162          * need to look inside the object at all. Note that we
1163          * do not optimize out the stat call, even if the
1164          * caller doesn't care about the disk-size, since our
1165          * return value implicitly indicates whether the
1166          * object even exists.
1167          */
1168         if (!oi->typep && !oi->type_name && !oi->sizep && !oi->contentp) {
1169                 const char *path;
1170                 struct stat st;
1171                 if (stat_sha1_file(sha1, &st, &path) < 0)
1172                         return -1;
1173                 if (oi->disk_sizep)
1174                         *oi->disk_sizep = st.st_size;
1175                 return 0;
1176         }
1177
1178         map = map_sha1_file(sha1, &mapsize);
1179         if (!map)
1180                 return -1;
1181
1182         if (!oi->sizep)
1183                 oi->sizep = &size_scratch;
1184
1185         if (oi->disk_sizep)
1186                 *oi->disk_sizep = mapsize;
1187         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
1188                 if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
1189                         status = error("unable to unpack %s header with --allow-unknown-type",
1190                                        sha1_to_hex(sha1));
1191         } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1192                 status = error("unable to unpack %s header",
1193                                sha1_to_hex(sha1));
1194         if (status < 0)
1195                 ; /* Do nothing */
1196         else if (hdrbuf.len) {
1197                 if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
1198                         status = error("unable to parse %s header with --allow-unknown-type",
1199                                        sha1_to_hex(sha1));
1200         } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
1201                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1202
1203         if (status >= 0 && oi->contentp) {
1204                 *oi->contentp = unpack_sha1_rest(&stream, hdr,
1205                                                  *oi->sizep, sha1);
1206                 if (!*oi->contentp) {
1207                         git_inflate_end(&stream);
1208                         status = -1;
1209                 }
1210         } else
1211                 git_inflate_end(&stream);
1212
1213         munmap(map, mapsize);
1214         if (status && oi->typep)
1215                 *oi->typep = status;
1216         if (oi->sizep == &size_scratch)
1217                 oi->sizep = NULL;
1218         strbuf_release(&hdrbuf);
1219         oi->whence = OI_LOOSE;
1220         return (status < 0) ? status : 0;
1221 }
1222
1223 int fetch_if_missing = 1;
1224
1225 int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
1226 {
1227         static struct object_info blank_oi = OBJECT_INFO_INIT;
1228         struct pack_entry e;
1229         int rtype;
1230         const unsigned char *real = (flags & OBJECT_INFO_LOOKUP_REPLACE) ?
1231                                     lookup_replace_object(sha1) :
1232                                     sha1;
1233         int already_retried = 0;
1234
1235         if (is_null_sha1(real))
1236                 return -1;
1237
1238         if (!oi)
1239                 oi = &blank_oi;
1240
1241         if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
1242                 struct cached_object *co = find_cached_object(real);
1243                 if (co) {
1244                         if (oi->typep)
1245                                 *(oi->typep) = co->type;
1246                         if (oi->sizep)
1247                                 *(oi->sizep) = co->size;
1248                         if (oi->disk_sizep)
1249                                 *(oi->disk_sizep) = 0;
1250                         if (oi->delta_base_sha1)
1251                                 hashclr(oi->delta_base_sha1);
1252                         if (oi->type_name)
1253                                 strbuf_addstr(oi->type_name, type_name(co->type));
1254                         if (oi->contentp)
1255                                 *oi->contentp = xmemdupz(co->buf, co->size);
1256                         oi->whence = OI_CACHED;
1257                         return 0;
1258                 }
1259         }
1260
1261         while (1) {
1262                 if (find_pack_entry(real, &e))
1263                         break;
1264
1265                 /* Most likely it's a loose object. */
1266                 if (!sha1_loose_object_info(real, oi, flags))
1267                         return 0;
1268
1269                 /* Not a loose object; someone else may have just packed it. */
1270                 if (!(flags & OBJECT_INFO_QUICK)) {
1271                         reprepare_packed_git();
1272                         if (find_pack_entry(real, &e))
1273                                 break;
1274                 }
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_object_file(void *buf, unsigned long len, enum object_type type,
1340                         struct object_id *oid)
1341 {
1342         struct cached_object *co;
1343
1344         hash_object_file(buf, len, type_name(type), oid);
1345         if (has_sha1_file(oid->hash) || find_cached_object(oid->hash))
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, oid->hash);
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_object_file_prepare(const void *buf, unsigned long len,
1447                                       const char *type, struct object_id *oid,
1448                                       char *hdr, int *hdrlen)
1449 {
1450         git_hash_ctx c;
1451
1452         /* Generate the header */
1453         *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
1454
1455         /* Sha1.. */
1456         the_hash_algo->init_fn(&c);
1457         the_hash_algo->update_fn(&c, hdr, *hdrlen);
1458         the_hash_algo->update_fn(&c, buf, len);
1459         the_hash_algo->final_fn(oid->hash, &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_object_file(const void *buf, unsigned long len, const char *type,
1513                      struct object_id *oid)
1514 {
1515         char hdr[32];
1516         int hdrlen = sizeof(hdr);
1517         write_object_file_prepare(buf, len, type, oid, 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 struct object_id *oid, char *hdr,
1576                               int hdrlen, const void *buf, unsigned long len,
1577                               time_t mtime)
1578 {
1579         int fd, ret;
1580         unsigned char compressed[4096];
1581         git_zstream stream;
1582         git_hash_ctx c;
1583         struct object_id parano_oid;
1584         static struct strbuf tmp_file = STRBUF_INIT;
1585         static struct strbuf filename = STRBUF_INIT;
1586
1587         strbuf_reset(&filename);
1588         sha1_file_name(&filename, oid->hash);
1589
1590         fd = create_tmpfile(&tmp_file, filename.buf);
1591         if (fd < 0) {
1592                 if (errno == EACCES)
1593                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
1594                 else
1595                         return error_errno("unable to create temporary file");
1596         }
1597
1598         /* Set it up */
1599         git_deflate_init(&stream, zlib_compression_level);
1600         stream.next_out = compressed;
1601         stream.avail_out = sizeof(compressed);
1602         the_hash_algo->init_fn(&c);
1603
1604         /* First header.. */
1605         stream.next_in = (unsigned char *)hdr;
1606         stream.avail_in = hdrlen;
1607         while (git_deflate(&stream, 0) == Z_OK)
1608                 ; /* nothing */
1609         the_hash_algo->update_fn(&c, hdr, hdrlen);
1610
1611         /* Then the data itself.. */
1612         stream.next_in = (void *)buf;
1613         stream.avail_in = len;
1614         do {
1615                 unsigned char *in0 = stream.next_in;
1616                 ret = git_deflate(&stream, Z_FINISH);
1617                 the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
1618                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
1619                         die("unable to write sha1 file");
1620                 stream.next_out = compressed;
1621                 stream.avail_out = sizeof(compressed);
1622         } while (ret == Z_OK);
1623
1624         if (ret != Z_STREAM_END)
1625                 die("unable to deflate new object %s (%d)", oid_to_hex(oid),
1626                     ret);
1627         ret = git_deflate_end_gently(&stream);
1628         if (ret != Z_OK)
1629                 die("deflateEnd on object %s failed (%d)", oid_to_hex(oid),
1630                     ret);
1631         the_hash_algo->final_fn(parano_oid.hash, &c);
1632         if (oidcmp(oid, &parano_oid) != 0)
1633                 die("confused by unstable object source data for %s",
1634                     oid_to_hex(oid));
1635
1636         close_sha1_file(fd);
1637
1638         if (mtime) {
1639                 struct utimbuf utb;
1640                 utb.actime = mtime;
1641                 utb.modtime = mtime;
1642                 if (utime(tmp_file.buf, &utb) < 0)
1643                         warning_errno("failed utime() on %s", tmp_file.buf);
1644         }
1645
1646         return finalize_object_file(tmp_file.buf, filename.buf);
1647 }
1648
1649 static int freshen_loose_object(const unsigned char *sha1)
1650 {
1651         return check_and_freshen(sha1, 1);
1652 }
1653
1654 static int freshen_packed_object(const unsigned char *sha1)
1655 {
1656         struct pack_entry e;
1657         if (!find_pack_entry(sha1, &e))
1658                 return 0;
1659         if (e.p->freshened)
1660                 return 1;
1661         if (!freshen_file(e.p->pack_name))
1662                 return 0;
1663         e.p->freshened = 1;
1664         return 1;
1665 }
1666
1667 int write_object_file(const void *buf, unsigned long len, const char *type,
1668                       struct object_id *oid)
1669 {
1670         char hdr[32];
1671         int hdrlen = sizeof(hdr);
1672
1673         /* Normally if we have it in the pack then we do not bother writing
1674          * it out into .git/objects/??/?{38} file.
1675          */
1676         write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
1677         if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1678                 return 0;
1679         return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
1680 }
1681
1682 int hash_object_file_literally(const void *buf, unsigned long len,
1683                                const char *type, struct object_id *oid,
1684                                unsigned flags)
1685 {
1686         char *header;
1687         int hdrlen, status = 0;
1688
1689         /* type string, SP, %lu of the length plus NUL must fit this */
1690         hdrlen = strlen(type) + 32;
1691         header = xmalloc(hdrlen);
1692         write_object_file_prepare(buf, len, type, oid, header, &hdrlen);
1693
1694         if (!(flags & HASH_WRITE_OBJECT))
1695                 goto cleanup;
1696         if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1697                 goto cleanup;
1698         status = write_loose_object(oid, header, hdrlen, buf, len, 0);
1699
1700 cleanup:
1701         free(header);
1702         return status;
1703 }
1704
1705 int force_object_loose(const struct object_id *oid, time_t mtime)
1706 {
1707         void *buf;
1708         unsigned long len;
1709         enum object_type type;
1710         char hdr[32];
1711         int hdrlen;
1712         int ret;
1713
1714         if (has_loose_object(oid->hash))
1715                 return 0;
1716         buf = read_object(oid->hash, &type, &len);
1717         if (!buf)
1718                 return error("cannot read sha1_file for %s", oid_to_hex(oid));
1719         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(type), len) + 1;
1720         ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
1721         free(buf);
1722
1723         return ret;
1724 }
1725
1726 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
1727 {
1728         if (!startup_info->have_repository)
1729                 return 0;
1730         return sha1_object_info_extended(sha1, NULL,
1731                                          flags | OBJECT_INFO_SKIP_CACHED) >= 0;
1732 }
1733
1734 int has_object_file(const struct object_id *oid)
1735 {
1736         return has_sha1_file(oid->hash);
1737 }
1738
1739 int has_object_file_with_flags(const struct object_id *oid, int flags)
1740 {
1741         return has_sha1_file_with_flags(oid->hash, flags);
1742 }
1743
1744 static void check_tree(const void *buf, size_t size)
1745 {
1746         struct tree_desc desc;
1747         struct name_entry entry;
1748
1749         init_tree_desc(&desc, buf, size);
1750         while (tree_entry(&desc, &entry))
1751                 /* do nothing
1752                  * tree_entry() will die() on malformed entries */
1753                 ;
1754 }
1755
1756 static void check_commit(const void *buf, size_t size)
1757 {
1758         struct commit c;
1759         memset(&c, 0, sizeof(c));
1760         if (parse_commit_buffer(&c, buf, size))
1761                 die("corrupt commit");
1762 }
1763
1764 static void check_tag(const void *buf, size_t size)
1765 {
1766         struct tag t;
1767         memset(&t, 0, sizeof(t));
1768         if (parse_tag_buffer(&t, buf, size))
1769                 die("corrupt tag");
1770 }
1771
1772 static int index_mem(struct object_id *oid, void *buf, size_t size,
1773                      enum object_type type,
1774                      const char *path, unsigned flags)
1775 {
1776         int ret, re_allocated = 0;
1777         int write_object = flags & HASH_WRITE_OBJECT;
1778
1779         if (!type)
1780                 type = OBJ_BLOB;
1781
1782         /*
1783          * Convert blobs to git internal format
1784          */
1785         if ((type == OBJ_BLOB) && path) {
1786                 struct strbuf nbuf = STRBUF_INIT;
1787                 if (convert_to_git(&the_index, path, buf, size, &nbuf,
1788                                    get_conv_flags(flags))) {
1789                         buf = strbuf_detach(&nbuf, &size);
1790                         re_allocated = 1;
1791                 }
1792         }
1793         if (flags & HASH_FORMAT_CHECK) {
1794                 if (type == OBJ_TREE)
1795                         check_tree(buf, size);
1796                 if (type == OBJ_COMMIT)
1797                         check_commit(buf, size);
1798                 if (type == OBJ_TAG)
1799                         check_tag(buf, size);
1800         }
1801
1802         if (write_object)
1803                 ret = write_object_file(buf, size, type_name(type), oid);
1804         else
1805                 ret = hash_object_file(buf, size, type_name(type), oid);
1806         if (re_allocated)
1807                 free(buf);
1808         return ret;
1809 }
1810
1811 static int index_stream_convert_blob(struct object_id *oid, int fd,
1812                                      const char *path, unsigned flags)
1813 {
1814         int ret;
1815         const int write_object = flags & HASH_WRITE_OBJECT;
1816         struct strbuf sbuf = STRBUF_INIT;
1817
1818         assert(path);
1819         assert(would_convert_to_git_filter_fd(path));
1820
1821         convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
1822                                  get_conv_flags(flags));
1823
1824         if (write_object)
1825                 ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1826                                         oid);
1827         else
1828                 ret = hash_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1829                                        oid);
1830         strbuf_release(&sbuf);
1831         return ret;
1832 }
1833
1834 static int index_pipe(struct object_id *oid, int fd, enum object_type type,
1835                       const char *path, unsigned flags)
1836 {
1837         struct strbuf sbuf = STRBUF_INIT;
1838         int ret;
1839
1840         if (strbuf_read(&sbuf, fd, 4096) >= 0)
1841                 ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
1842         else
1843                 ret = -1;
1844         strbuf_release(&sbuf);
1845         return ret;
1846 }
1847
1848 #define SMALL_FILE_SIZE (32*1024)
1849
1850 static int index_core(struct object_id *oid, int fd, size_t size,
1851                       enum object_type type, const char *path,
1852                       unsigned flags)
1853 {
1854         int ret;
1855
1856         if (!size) {
1857                 ret = index_mem(oid, "", size, type, path, flags);
1858         } else if (size <= SMALL_FILE_SIZE) {
1859                 char *buf = xmalloc(size);
1860                 ssize_t read_result = read_in_full(fd, buf, size);
1861                 if (read_result < 0)
1862                         ret = error_errno("read error while indexing %s",
1863                                           path ? path : "<unknown>");
1864                 else if (read_result != size)
1865                         ret = error("short read while indexing %s",
1866                                     path ? path : "<unknown>");
1867                 else
1868                         ret = index_mem(oid, buf, size, type, path, flags);
1869                 free(buf);
1870         } else {
1871                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1872                 ret = index_mem(oid, buf, size, type, path, flags);
1873                 munmap(buf, size);
1874         }
1875         return ret;
1876 }
1877
1878 /*
1879  * This creates one packfile per large blob unless bulk-checkin
1880  * machinery is "plugged".
1881  *
1882  * This also bypasses the usual "convert-to-git" dance, and that is on
1883  * purpose. We could write a streaming version of the converting
1884  * functions and insert that before feeding the data to fast-import
1885  * (or equivalent in-core API described above). However, that is
1886  * somewhat complicated, as we do not know the size of the filter
1887  * result, which we need to know beforehand when writing a git object.
1888  * Since the primary motivation for trying to stream from the working
1889  * tree file and to avoid mmaping it in core is to deal with large
1890  * binary blobs, they generally do not want to get any conversion, and
1891  * callers should avoid this code path when filters are requested.
1892  */
1893 static int index_stream(struct object_id *oid, int fd, size_t size,
1894                         enum object_type type, const char *path,
1895                         unsigned flags)
1896 {
1897         return index_bulk_checkin(oid->hash, fd, size, type, path, flags);
1898 }
1899
1900 int index_fd(struct object_id *oid, int fd, struct stat *st,
1901              enum object_type type, const char *path, unsigned flags)
1902 {
1903         int ret;
1904
1905         /*
1906          * Call xsize_t() only when needed to avoid potentially unnecessary
1907          * die() for large files.
1908          */
1909         if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
1910                 ret = index_stream_convert_blob(oid, fd, path, flags);
1911         else if (!S_ISREG(st->st_mode))
1912                 ret = index_pipe(oid, fd, type, path, flags);
1913         else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
1914                  (path && would_convert_to_git(&the_index, path)))
1915                 ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
1916                                  flags);
1917         else
1918                 ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
1919                                    flags);
1920         close(fd);
1921         return ret;
1922 }
1923
1924 int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
1925 {
1926         int fd;
1927         struct strbuf sb = STRBUF_INIT;
1928         int rc = 0;
1929
1930         switch (st->st_mode & S_IFMT) {
1931         case S_IFREG:
1932                 fd = open(path, O_RDONLY);
1933                 if (fd < 0)
1934                         return error_errno("open(\"%s\")", path);
1935                 if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
1936                         return error("%s: failed to insert into database",
1937                                      path);
1938                 break;
1939         case S_IFLNK:
1940                 if (strbuf_readlink(&sb, path, st->st_size))
1941                         return error_errno("readlink(\"%s\")", path);
1942                 if (!(flags & HASH_WRITE_OBJECT))
1943                         hash_object_file(sb.buf, sb.len, blob_type, oid);
1944                 else if (write_object_file(sb.buf, sb.len, blob_type, oid))
1945                         rc = error("%s: failed to insert into database", path);
1946                 strbuf_release(&sb);
1947                 break;
1948         case S_IFDIR:
1949                 return resolve_gitlink_ref(path, "HEAD", oid);
1950         default:
1951                 return error("%s: unsupported file type", path);
1952         }
1953         return rc;
1954 }
1955
1956 int read_pack_header(int fd, struct pack_header *header)
1957 {
1958         if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
1959                 /* "eof before pack header was fully read" */
1960                 return PH_ERROR_EOF;
1961
1962         if (header->hdr_signature != htonl(PACK_SIGNATURE))
1963                 /* "protocol error (pack signature mismatch detected)" */
1964                 return PH_ERROR_PACK_SIGNATURE;
1965         if (!pack_version_ok(header->hdr_version))
1966                 /* "protocol error (pack version unsupported)" */
1967                 return PH_ERROR_PROTOCOL;
1968         return 0;
1969 }
1970
1971 void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
1972 {
1973         enum object_type type = sha1_object_info(sha1, NULL);
1974         if (type < 0)
1975                 die("%s is not a valid object", sha1_to_hex(sha1));
1976         if (type != expect)
1977                 die("%s is not a valid '%s' object", sha1_to_hex(sha1),
1978                     type_name(expect));
1979 }
1980
1981 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
1982                                 struct strbuf *path,
1983                                 each_loose_object_fn obj_cb,
1984                                 each_loose_cruft_fn cruft_cb,
1985                                 each_loose_subdir_fn subdir_cb,
1986                                 void *data)
1987 {
1988         size_t origlen, baselen;
1989         DIR *dir;
1990         struct dirent *de;
1991         int r = 0;
1992         struct object_id oid;
1993
1994         if (subdir_nr > 0xff)
1995                 BUG("invalid loose object subdirectory: %x", subdir_nr);
1996
1997         origlen = path->len;
1998         strbuf_complete(path, '/');
1999         strbuf_addf(path, "%02x", subdir_nr);
2000
2001         dir = opendir(path->buf);
2002         if (!dir) {
2003                 if (errno != ENOENT)
2004                         r = error_errno("unable to open %s", path->buf);
2005                 strbuf_setlen(path, origlen);
2006                 return r;
2007         }
2008
2009         oid.hash[0] = subdir_nr;
2010         strbuf_addch(path, '/');
2011         baselen = path->len;
2012
2013         while ((de = readdir(dir))) {
2014                 size_t namelen;
2015                 if (is_dot_or_dotdot(de->d_name))
2016                         continue;
2017
2018                 namelen = strlen(de->d_name);
2019                 strbuf_setlen(path, baselen);
2020                 strbuf_add(path, de->d_name, namelen);
2021                 if (namelen == GIT_SHA1_HEXSZ - 2 &&
2022                     !hex_to_bytes(oid.hash + 1, de->d_name,
2023                                   GIT_SHA1_RAWSZ - 1)) {
2024                         if (obj_cb) {
2025                                 r = obj_cb(&oid, path->buf, data);
2026                                 if (r)
2027                                         break;
2028                         }
2029                         continue;
2030                 }
2031
2032                 if (cruft_cb) {
2033                         r = cruft_cb(de->d_name, path->buf, data);
2034                         if (r)
2035                                 break;
2036                 }
2037         }
2038         closedir(dir);
2039
2040         strbuf_setlen(path, baselen - 1);
2041         if (!r && subdir_cb)
2042                 r = subdir_cb(subdir_nr, path->buf, data);
2043
2044         strbuf_setlen(path, origlen);
2045
2046         return r;
2047 }
2048
2049 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
2050                             each_loose_object_fn obj_cb,
2051                             each_loose_cruft_fn cruft_cb,
2052                             each_loose_subdir_fn subdir_cb,
2053                             void *data)
2054 {
2055         int r = 0;
2056         int i;
2057
2058         for (i = 0; i < 256; i++) {
2059                 r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
2060                                                 subdir_cb, data);
2061                 if (r)
2062                         break;
2063         }
2064
2065         return r;
2066 }
2067
2068 int for_each_loose_file_in_objdir(const char *path,
2069                                   each_loose_object_fn obj_cb,
2070                                   each_loose_cruft_fn cruft_cb,
2071                                   each_loose_subdir_fn subdir_cb,
2072                                   void *data)
2073 {
2074         struct strbuf buf = STRBUF_INIT;
2075         int r;
2076
2077         strbuf_addstr(&buf, path);
2078         r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
2079                                               subdir_cb, data);
2080         strbuf_release(&buf);
2081
2082         return r;
2083 }
2084
2085 struct loose_alt_odb_data {
2086         each_loose_object_fn *cb;
2087         void *data;
2088 };
2089
2090 static int loose_from_alt_odb(struct alternate_object_database *alt,
2091                               void *vdata)
2092 {
2093         struct loose_alt_odb_data *data = vdata;
2094         struct strbuf buf = STRBUF_INIT;
2095         int r;
2096
2097         strbuf_addstr(&buf, alt->path);
2098         r = for_each_loose_file_in_objdir_buf(&buf,
2099                                               data->cb, NULL, NULL,
2100                                               data->data);
2101         strbuf_release(&buf);
2102         return r;
2103 }
2104
2105 int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
2106 {
2107         struct loose_alt_odb_data alt;
2108         int r;
2109
2110         r = for_each_loose_file_in_objdir(get_object_directory(),
2111                                           cb, NULL, NULL, data);
2112         if (r)
2113                 return r;
2114
2115         if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
2116                 return 0;
2117
2118         alt.cb = cb;
2119         alt.data = data;
2120         return foreach_alt_odb(loose_from_alt_odb, &alt);
2121 }
2122
2123 static int check_stream_sha1(git_zstream *stream,
2124                              const char *hdr,
2125                              unsigned long size,
2126                              const char *path,
2127                              const unsigned char *expected_sha1)
2128 {
2129         git_hash_ctx c;
2130         unsigned char real_sha1[GIT_MAX_RAWSZ];
2131         unsigned char buf[4096];
2132         unsigned long total_read;
2133         int status = Z_OK;
2134
2135         the_hash_algo->init_fn(&c);
2136         the_hash_algo->update_fn(&c, hdr, stream->total_out);
2137
2138         /*
2139          * We already read some bytes into hdr, but the ones up to the NUL
2140          * do not count against the object's content size.
2141          */
2142         total_read = stream->total_out - strlen(hdr) - 1;
2143
2144         /*
2145          * This size comparison must be "<=" to read the final zlib packets;
2146          * see the comment in unpack_sha1_rest for details.
2147          */
2148         while (total_read <= size &&
2149                (status == Z_OK || status == Z_BUF_ERROR)) {
2150                 stream->next_out = buf;
2151                 stream->avail_out = sizeof(buf);
2152                 if (size - total_read < stream->avail_out)
2153                         stream->avail_out = size - total_read;
2154                 status = git_inflate(stream, Z_FINISH);
2155                 the_hash_algo->update_fn(&c, buf, stream->next_out - buf);
2156                 total_read += stream->next_out - buf;
2157         }
2158         git_inflate_end(stream);
2159
2160         if (status != Z_STREAM_END) {
2161                 error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
2162                 return -1;
2163         }
2164         if (stream->avail_in) {
2165                 error("garbage at end of loose object '%s'",
2166                       sha1_to_hex(expected_sha1));
2167                 return -1;
2168         }
2169
2170         the_hash_algo->final_fn(real_sha1, &c);
2171         if (hashcmp(expected_sha1, real_sha1)) {
2172                 error("sha1 mismatch for %s (expected %s)", path,
2173                       sha1_to_hex(expected_sha1));
2174                 return -1;
2175         }
2176
2177         return 0;
2178 }
2179
2180 int read_loose_object(const char *path,
2181                       const unsigned char *expected_sha1,
2182                       enum object_type *type,
2183                       unsigned long *size,
2184                       void **contents)
2185 {
2186         int ret = -1;
2187         void *map = NULL;
2188         unsigned long mapsize;
2189         git_zstream stream;
2190         char hdr[32];
2191
2192         *contents = NULL;
2193
2194         map = map_sha1_file_1(path, NULL, &mapsize);
2195         if (!map) {
2196                 error_errno("unable to mmap %s", path);
2197                 goto out;
2198         }
2199
2200         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
2201                 error("unable to unpack header of %s", path);
2202                 goto out;
2203         }
2204
2205         *type = parse_sha1_header(hdr, size);
2206         if (*type < 0) {
2207                 error("unable to parse header of %s", path);
2208                 git_inflate_end(&stream);
2209                 goto out;
2210         }
2211
2212         if (*type == OBJ_BLOB && *size > big_file_threshold) {
2213                 if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
2214                         goto out;
2215         } else {
2216                 *contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
2217                 if (!*contents) {
2218                         error("unable to unpack contents of %s", path);
2219                         git_inflate_end(&stream);
2220                         goto out;
2221                 }
2222                 if (check_sha1_signature(expected_sha1, *contents,
2223                                          *size, type_name(*type))) {
2224                         error("sha1 mismatch for %s (expected %s)", path,
2225                               sha1_to_hex(expected_sha1));
2226                         free(*contents);
2227                         goto out;
2228                 }
2229         }
2230
2231         ret = 0; /* everything checks out */
2232
2233 out:
2234         if (map)
2235                 munmap(map, mapsize);
2236         return ret;
2237 }