git.oblomov.eu Git - git/blob - sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "config.h"
  11 #include "string-list.h"
  12 #include "lockfile.h"
  13 #include "delta.h"
  14 #include "pack.h"
  15 #include "blob.h"
  16 #include "commit.h"
  17 #include "run-command.h"
  18 #include "tag.h"
  19 #include "tree.h"
  20 #include "tree-walk.h"
  21 #include "refs.h"
  22 #include "pack-revindex.h"
  23 #include "sha1-lookup.h"
  24 #include "bulk-checkin.h"
  25 #include "repository.h"
  26 #include "streaming.h"
  27 #include "dir.h"
  28 #include "list.h"
  29 #include "mergesort.h"
  30 #include "quote.h"
  31 #include "packfile.h"
  32 #include "fetch-object.h"
  33 #include "object-store.h"
  34
  35 /* The maximum size for an object header. */
  36 #define MAX_HEADER_LEN 32
  37
  38 const unsigned char null_sha1[GIT_MAX_RAWSZ];
  39 const struct object_id null_oid;
  40 const struct object_id empty_tree_oid = {
  41         EMPTY_TREE_SHA1_BIN_LITERAL
  42 };
  43 const struct object_id empty_blob_oid = {
  44         EMPTY_BLOB_SHA1_BIN_LITERAL
  45 };
  46
  47 static void git_hash_sha1_init(git_hash_ctx *ctx)
  48 {
  49         git_SHA1_Init(&ctx->sha1);
  50 }
  51
  52 static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
  53 {
  54         git_SHA1_Update(&ctx->sha1, data, len);
  55 }
  56
  57 static void git_hash_sha1_final(unsigned char *hash, git_hash_ctx *ctx)
  58 {
  59         git_SHA1_Final(hash, &ctx->sha1);
  60 }
  61
  62 static void git_hash_unknown_init(git_hash_ctx *ctx)
  63 {
  64         die("trying to init unknown hash");
  65 }
  66
  67 static void git_hash_unknown_update(git_hash_ctx *ctx, const void *data, size_t len)
  68 {
  69         die("trying to update unknown hash");
  70 }
  71
  72 static void git_hash_unknown_final(unsigned char *hash, git_hash_ctx *ctx)
  73 {
  74         die("trying to finalize unknown hash");
  75 }
  76
  77 const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
  78         {
  79                 NULL,
  80                 0x00000000,
  81                 0,
  82                 0,
  83                 git_hash_unknown_init,
  84                 git_hash_unknown_update,
  85                 git_hash_unknown_final,
  86                 NULL,
  87                 NULL,
  88         },
  89         {
  90                 "sha-1",
  91                 /* "sha1", big-endian */
  92                 0x73686131,
  93                 GIT_SHA1_RAWSZ,
  94                 GIT_SHA1_HEXSZ,
  95                 git_hash_sha1_init,
  96                 git_hash_sha1_update,
  97                 git_hash_sha1_final,
  98                 &empty_tree_oid,
  99                 &empty_blob_oid,
 100         },
 101 };
 102
 103 /*
 104  * This is meant to hold a *small* number of objects that you would
 105  * want read_sha1_file() to be able to return, but yet you do not want
 106  * to write them into the object store (e.g. a browse-only
 107  * application).
 108  */
 109 static struct cached_object {
 110         unsigned char sha1[20];
 111         enum object_type type;
 112         void *buf;
 113         unsigned long size;
 114 } *cached_objects;
 115 static int cached_object_nr, cached_object_alloc;
 116
 117 static struct cached_object empty_tree = {
 118         EMPTY_TREE_SHA1_BIN_LITERAL,
 119         OBJ_TREE,
 120         "",
 121         0
 122 };
 123
 124 static struct cached_object *find_cached_object(const unsigned char *sha1)
 125 {
 126         int i;
 127         struct cached_object *co = cached_objects;
 128
 129         for (i = 0; i < cached_object_nr; i++, co++) {
 130                 if (!hashcmp(co->sha1, sha1))
 131                         return co;
 132         }
 133         if (!hashcmp(sha1, empty_tree.sha1))
 134                 return &empty_tree;
 135         return NULL;
 136 }
 137
 138
 139 static int get_conv_flags(unsigned flags)
 140 {
 141         if (flags & HASH_RENORMALIZE)
 142                 return CONV_EOL_RENORMALIZE;
 143         else if (flags & HASH_WRITE_OBJECT)
 144           return global_conv_flags_eol;
 145         else
 146                 return 0;
 147 }
 148
 149
 150 int mkdir_in_gitdir(const char *path)
 151 {
 152         if (mkdir(path, 0777)) {
 153                 int saved_errno = errno;
 154                 struct stat st;
 155                 struct strbuf sb = STRBUF_INIT;
 156
 157                 if (errno != EEXIST)
 158                         return -1;
 159                 /*
 160                  * Are we looking at a path in a symlinked worktree
 161                  * whose original repository does not yet have it?
 162                  * e.g. .git/rr-cache pointing at its original
 163                  * repository in which the user hasn't performed any
 164                  * conflict resolution yet?
 165                  */
 166                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 167                     strbuf_readlink(&sb, path, st.st_size) ||
 168                     !is_absolute_path(sb.buf) ||
 169                     mkdir(sb.buf, 0777)) {
 170                         strbuf_release(&sb);
 171                         errno = saved_errno;
 172                         return -1;
 173                 }
 174                 strbuf_release(&sb);
 175         }
 176         return adjust_shared_perm(path);
 177 }
 178
 179 enum scld_error safe_create_leading_directories(char *path)
 180 {
 181         char *next_component = path + offset_1st_component(path);
 182         enum scld_error ret = SCLD_OK;
 183
 184         while (ret == SCLD_OK && next_component) {
 185                 struct stat st;
 186                 char *slash = next_component, slash_character;
 187
 188                 while (*slash && !is_dir_sep(*slash))
 189                         slash++;
 190
 191                 if (!*slash)
 192                         break;
 193
 194                 next_component = slash + 1;
 195                 while (is_dir_sep(*next_component))
 196                         next_component++;
 197                 if (!*next_component)
 198                         break;
 199
 200                 slash_character = *slash;
 201                 *slash = '\0';
 202                 if (!stat(path, &st)) {
 203                         /* path exists */
 204                         if (!S_ISDIR(st.st_mode)) {
 205                                 errno = ENOTDIR;
 206                                 ret = SCLD_EXISTS;
 207                         }
 208                 } else if (mkdir(path, 0777)) {
 209                         if (errno == EEXIST &&
 210                             !stat(path, &st) && S_ISDIR(st.st_mode))
 211                                 ; /* somebody created it since we checked */
 212                         else if (errno == ENOENT)
 213                                 /*
 214                                  * Either mkdir() failed because
 215                                  * somebody just pruned the containing
 216                                  * directory, or stat() failed because
 217                                  * the file that was in our way was
 218                                  * just removed.  Either way, inform
 219                                  * the caller that it might be worth
 220                                  * trying again:
 221                                  */
 222                                 ret = SCLD_VANISHED;
 223                         else
 224                                 ret = SCLD_FAILED;
 225                 } else if (adjust_shared_perm(path)) {
 226                         ret = SCLD_PERMS;
 227                 }
 228                 *slash = slash_character;
 229         }
 230         return ret;
 231 }
 232
 233 enum scld_error safe_create_leading_directories_const(const char *path)
 234 {
 235         int save_errno;
 236         /* path points to cache entries, so xstrdup before messing with it */
 237         char *buf = xstrdup(path);
 238         enum scld_error result = safe_create_leading_directories(buf);
 239
 240         save_errno = errno;
 241         free(buf);
 242         errno = save_errno;
 243         return result;
 244 }
 245
 246 int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 247 {
 248         /*
 249          * The number of times we will try to remove empty directories
 250          * in the way of path. This is only 1 because if another
 251          * process is racily creating directories that conflict with
 252          * us, we don't want to fight against them.
 253          */
 254         int remove_directories_remaining = 1;
 255
 256         /*
 257          * The number of times that we will try to create the
 258          * directories containing path. We are willing to attempt this
 259          * more than once, because another process could be trying to
 260          * clean up empty directories at the same time as we are
 261          * trying to create them.
 262          */
 263         int create_directories_remaining = 3;
 264
 265         /* A scratch copy of path, filled lazily if we need it: */
 266         struct strbuf path_copy = STRBUF_INIT;
 267
 268         int ret, save_errno;
 269
 270         /* Sanity check: */
 271         assert(*path);
 272
 273 retry_fn:
 274         ret = fn(path, cb);
 275         save_errno = errno;
 276         if (!ret)
 277                 goto out;
 278
 279         if (errno == EISDIR && remove_directories_remaining-- > 0) {
 280                 /*
 281                  * A directory is in the way. Maybe it is empty; try
 282                  * to remove it:
 283                  */
 284                 if (!path_copy.len)
 285                         strbuf_addstr(&path_copy, path);
 286
 287                 if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 288                         goto retry_fn;
 289         } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 290                 /*
 291                  * Maybe the containing directory didn't exist, or
 292                  * maybe it was just deleted by a process that is
 293                  * racing with us to clean up empty directories. Try
 294                  * to create it:
 295                  */
 296                 enum scld_error scld_result;
 297
 298                 if (!path_copy.len)
 299                         strbuf_addstr(&path_copy, path);
 300
 301                 do {
 302                         scld_result = safe_create_leading_directories(path_copy.buf);
 303                         if (scld_result == SCLD_OK)
 304                                 goto retry_fn;
 305                 } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 306         }
 307
 308 out:
 309         strbuf_release(&path_copy);
 310         errno = save_errno;
 311         return ret;
 312 }
 313
 314 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 315 {
 316         int i;
 317         for (i = 0; i < 20; i++) {
 318                 static char hex[] = "0123456789abcdef";
 319                 unsigned int val = sha1[i];
 320                 strbuf_addch(buf, hex[val >> 4]);
 321                 strbuf_addch(buf, hex[val & 0xf]);
 322                 if (!i)
 323                         strbuf_addch(buf, '/');
 324         }
 325 }
 326
 327 void sha1_file_name(struct repository *r, struct strbuf *buf, const unsigned char *sha1)
 328 {
 329         strbuf_addstr(buf, r->objects->objectdir);
 330         strbuf_addch(buf, '/');
 331         fill_sha1_path(buf, sha1);
 332 }
 333
 334 struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 335 {
 336         strbuf_setlen(&alt->scratch, alt->base_len);
 337         return &alt->scratch;
 338 }
 339
 340 static const char *alt_sha1_path(struct alternate_object_database *alt,
 341                                  const unsigned char *sha1)
 342 {
 343         struct strbuf *buf = alt_scratch_buf(alt);
 344         fill_sha1_path(buf, sha1);
 345         return buf->buf;
 346 }
 347
 348 /*
 349  * Return non-zero iff the path is usable as an alternate object database.
 350  */
 351 static int alt_odb_usable(struct raw_object_store *o,
 352                           struct strbuf *path,
 353                           const char *normalized_objdir)
 354 {
 355         struct alternate_object_database *alt;
 356
 357         /* Detect cases where alternate disappeared */
 358         if (!is_directory(path->buf)) {
 359                 error("object directory %s does not exist; "
 360                       "check .git/objects/info/alternates.",
 361                       path->buf);
 362                 return 0;
 363         }
 364
 365         /*
 366          * Prevent the common mistake of listing the same
 367          * thing twice, or object directory itself.
 368          */
 369         for (alt = o->alt_odb_list; alt; alt = alt->next) {
 370                 if (!fspathcmp(path->buf, alt->path))
 371                         return 0;
 372         }
 373         if (!fspathcmp(path->buf, normalized_objdir))
 374                 return 0;
 375
 376         return 1;
 377 }
 378
 379 /*
 380  * Prepare alternate object database registry.
 381  *
 382  * The variable alt_odb_list points at the list of struct
 383  * alternate_object_database.  The elements on this list come from
 384  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 385  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 386  * whose contents is similar to that environment variable but can be
 387  * LF separated.  Its base points at a statically allocated buffer that
 388  * contains "/the/directory/corresponding/to/.git/objects/...", while
 389  * its name points just after the slash at the end of ".git/objects/"
 390  * in the example above, and has enough space to hold 40-byte hex
 391  * SHA1, an extra slash for the first level indirection, and the
 392  * terminating NUL.
 393  */
 394 static void read_info_alternates(struct repository *r,
 395                                  const char *relative_base,
 396                                  int depth);
 397 static int link_alt_odb_entry(struct repository *r, const char *entry,
 398         const char *relative_base, int depth, const char *normalized_objdir)
 399 {
 400         struct alternate_object_database *ent;
 401         struct strbuf pathbuf = STRBUF_INIT;
 402
 403         if (!is_absolute_path(entry) && relative_base) {
 404                 strbuf_realpath(&pathbuf, relative_base, 1);
 405                 strbuf_addch(&pathbuf, '/');
 406         }
 407         strbuf_addstr(&pathbuf, entry);
 408
 409         if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 410                 error("unable to normalize alternate object path: %s",
 411                       pathbuf.buf);
 412                 strbuf_release(&pathbuf);
 413                 return -1;
 414         }
 415
 416         /*
 417          * The trailing slash after the directory name is given by
 418          * this function at the end. Remove duplicates.
 419          */
 420         while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 421                 strbuf_setlen(&pathbuf, pathbuf.len - 1);
 422
 423         if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir)) {
 424                 strbuf_release(&pathbuf);
 425                 return -1;
 426         }
 427
 428         ent = alloc_alt_odb(pathbuf.buf);
 429
 430         /* add the alternate entry */
 431         *r->objects->alt_odb_tail = ent;
 432         r->objects->alt_odb_tail = &(ent->next);
 433         ent->next = NULL;
 434
 435         /* recursively add alternates */
 436         read_info_alternates(r, pathbuf.buf, depth + 1);
 437
 438         strbuf_release(&pathbuf);
 439         return 0;
 440 }
 441
 442 static const char *parse_alt_odb_entry(const char *string,
 443                                        int sep,
 444                                        struct strbuf *out)
 445 {
 446         const char *end;
 447
 448         strbuf_reset(out);
 449
 450         if (*string == '#') {
 451                 /* comment; consume up to next separator */
 452                 end = strchrnul(string, sep);
 453         } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 454                 /*
 455                  * quoted path; unquote_c_style has copied the
 456                  * data for us and set "end". Broken quoting (e.g.,
 457                  * an entry that doesn't end with a quote) falls
 458                  * back to the unquoted case below.
 459                  */
 460         } else {
 461                 /* normal, unquoted path */
 462                 end = strchrnul(string, sep);
 463                 strbuf_add(out, string, end - string);
 464         }
 465
 466         if (*end)
 467                 end++;
 468         return end;
 469 }
 470
 471 static void link_alt_odb_entries(struct repository *r, const char *alt,
 472                                  int sep, const char *relative_base, int depth)
 473 {
 474         struct strbuf objdirbuf = STRBUF_INIT;
 475         struct strbuf entry = STRBUF_INIT;
 476
 477         if (!alt || !*alt)
 478                 return;
 479
 480         if (depth > 5) {
 481                 error("%s: ignoring alternate object stores, nesting too deep.",
 482                                 relative_base);
 483                 return;
 484         }
 485
 486         strbuf_add_absolute_path(&objdirbuf, r->objects->objectdir);
 487         if (strbuf_normalize_path(&objdirbuf) < 0)
 488                 die("unable to normalize object directory: %s",
 489                     objdirbuf.buf);
 490
 491         while (*alt) {
 492                 alt = parse_alt_odb_entry(alt, sep, &entry);
 493                 if (!entry.len)
 494                         continue;
 495                 link_alt_odb_entry(r, entry.buf,
 496                                    relative_base, depth, objdirbuf.buf);
 497         }
 498         strbuf_release(&entry);
 499         strbuf_release(&objdirbuf);
 500 }
 501
 502 static void read_info_alternates(struct repository *r,
 503                                  const char *relative_base,
 504                                  int depth)
 505 {
 506         char *path;
 507         struct strbuf buf = STRBUF_INIT;
 508
 509         path = xstrfmt("%s/info/alternates", relative_base);
 510         if (strbuf_read_file(&buf, path, 1024) < 0) {
 511                 warn_on_fopen_errors(path);
 512                 free(path);
 513                 return;
 514         }
 515
 516         link_alt_odb_entries(r, buf.buf, '\n', relative_base, depth);
 517         strbuf_release(&buf);
 518         free(path);
 519 }
 520
 521 struct alternate_object_database *alloc_alt_odb(const char *dir)
 522 {
 523         struct alternate_object_database *ent;
 524
 525         FLEX_ALLOC_STR(ent, path, dir);
 526         strbuf_init(&ent->scratch, 0);
 527         strbuf_addf(&ent->scratch, "%s/", dir);
 528         ent->base_len = ent->scratch.len;
 529
 530         return ent;
 531 }
 532
 533 void add_to_alternates_file(const char *reference)
 534 {
 535         struct lock_file lock = LOCK_INIT;
 536         char *alts = git_pathdup("objects/info/alternates");
 537         FILE *in, *out;
 538         int found = 0;
 539
 540         hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 541         out = fdopen_lock_file(&lock, "w");
 542         if (!out)
 543                 die_errno("unable to fdopen alternates lockfile");
 544
 545         in = fopen(alts, "r");
 546         if (in) {
 547                 struct strbuf line = STRBUF_INIT;
 548
 549                 while (strbuf_getline(&line, in) != EOF) {
 550                         if (!strcmp(reference, line.buf)) {
 551                                 found = 1;
 552                                 break;
 553                         }
 554                         fprintf_or_die(out, "%s\n", line.buf);
 555                 }
 556
 557                 strbuf_release(&line);
 558                 fclose(in);
 559         }
 560         else if (errno != ENOENT)
 561                 die_errno("unable to read alternates file");
 562
 563         if (found) {
 564                 rollback_lock_file(&lock);
 565         } else {
 566                 fprintf_or_die(out, "%s\n", reference);
 567                 if (commit_lock_file(&lock))
 568                         die_errno("unable to move new alternates file into place");
 569                 if (the_repository->objects->alt_odb_tail)
 570                         link_alt_odb_entries(the_repository, reference,
 571                                              '\n', NULL, 0);
 572         }
 573         free(alts);
 574 }
 575
 576 void add_to_alternates_memory(const char *reference)
 577 {
 578         /*
 579          * Make sure alternates are initialized, or else our entry may be
 580          * overwritten when they are.
 581          */
 582         prepare_alt_odb(the_repository);
 583
 584         link_alt_odb_entries(the_repository, reference,
 585                              '\n', NULL, 0);
 586 }
 587
 588 /*
 589  * Compute the exact path an alternate is at and returns it. In case of
 590  * error NULL is returned and the human readable error is added to `err`
 591  * `path` may be relative and should point to $GITDIR.
 592  * `err` must not be null.
 593  */
 594 char *compute_alternate_path(const char *path, struct strbuf *err)
 595 {
 596         char *ref_git = NULL;
 597         const char *repo, *ref_git_s;
 598         int seen_error = 0;
 599
 600         ref_git_s = real_path_if_valid(path);
 601         if (!ref_git_s) {
 602                 seen_error = 1;
 603                 strbuf_addf(err, _("path '%s' does not exist"), path);
 604                 goto out;
 605         } else
 606                 /*
 607                  * Beware: read_gitfile(), real_path() and mkpath()
 608                  * return static buffer
 609                  */
 610                 ref_git = xstrdup(ref_git_s);
 611
 612         repo = read_gitfile(ref_git);
 613         if (!repo)
 614                 repo = read_gitfile(mkpath("%s/.git", ref_git));
 615         if (repo) {
 616                 free(ref_git);
 617                 ref_git = xstrdup(repo);
 618         }
 619
 620         if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 621                 char *ref_git_git = mkpathdup("%s/.git", ref_git);
 622                 free(ref_git);
 623                 ref_git = ref_git_git;
 624         } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 625                 struct strbuf sb = STRBUF_INIT;
 626                 seen_error = 1;
 627                 if (get_common_dir(&sb, ref_git)) {
 628                         strbuf_addf(err,
 629                                     _("reference repository '%s' as a linked "
 630                                       "checkout is not supported yet."),
 631                                     path);
 632                         goto out;
 633                 }
 634
 635                 strbuf_addf(err, _("reference repository '%s' is not a "
 636                                         "local repository."), path);
 637                 goto out;
 638         }
 639
 640         if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 641                 strbuf_addf(err, _("reference repository '%s' is shallow"),
 642                             path);
 643                 seen_error = 1;
 644                 goto out;
 645         }
 646
 647         if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 648                 strbuf_addf(err,
 649                             _("reference repository '%s' is grafted"),
 650                             path);
 651                 seen_error = 1;
 652                 goto out;
 653         }
 654
 655 out:
 656         if (seen_error) {
 657                 FREE_AND_NULL(ref_git);
 658         }
 659
 660         return ref_git;
 661 }
 662
 663 int foreach_alt_odb(alt_odb_fn fn, void *cb)
 664 {
 665         struct alternate_object_database *ent;
 666         int r = 0;
 667
 668         prepare_alt_odb(the_repository);
 669         for (ent = the_repository->objects->alt_odb_list; ent; ent = ent->next) {
 670                 r = fn(ent, cb);
 671                 if (r)
 672                         break;
 673         }
 674         return r;
 675 }
 676
 677 void prepare_alt_odb(struct repository *r)
 678 {
 679         if (r->objects->alt_odb_tail)
 680                 return;
 681
 682         r->objects->alt_odb_tail = &r->objects->alt_odb_list;
 683         link_alt_odb_entries(r, r->objects->alternate_db, PATH_SEP, NULL, 0);
 684
 685         read_info_alternates(r, r->objects->objectdir, 0);
 686 }
 687
 688 /* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 689 static int freshen_file(const char *fn)
 690 {
 691         struct utimbuf t;
 692         t.actime = t.modtime = time(NULL);
 693         return !utime(fn, &t);
 694 }
 695
 696 /*
 697  * All of the check_and_freshen functions return 1 if the file exists and was
 698  * freshened (if freshening was requested), 0 otherwise. If they return
 699  * 0, you should not assume that it is safe to skip a write of the object (it
 700  * either does not exist on disk, or has a stale mtime and may be subject to
 701  * pruning).
 702  */
 703 int check_and_freshen_file(const char *fn, int freshen)
 704 {
 705         if (access(fn, F_OK))
 706                 return 0;
 707         if (freshen && !freshen_file(fn))
 708                 return 0;
 709         return 1;
 710 }
 711
 712 static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 713 {
 714         static struct strbuf buf = STRBUF_INIT;
 715
 716         strbuf_reset(&buf);
 717         sha1_file_name(the_repository, &buf, sha1);
 718
 719         return check_and_freshen_file(buf.buf, freshen);
 720 }
 721
 722 static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 723 {
 724         struct alternate_object_database *alt;
 725         prepare_alt_odb(the_repository);
 726         for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 727                 const char *path = alt_sha1_path(alt, sha1);
 728                 if (check_and_freshen_file(path, freshen))
 729                         return 1;
 730         }
 731         return 0;
 732 }
 733
 734 static int check_and_freshen(const unsigned char *sha1, int freshen)
 735 {
 736         return check_and_freshen_local(sha1, freshen) ||
 737                check_and_freshen_nonlocal(sha1, freshen);
 738 }
 739
 740 int has_loose_object_nonlocal(const unsigned char *sha1)
 741 {
 742         return check_and_freshen_nonlocal(sha1, 0);
 743 }
 744
 745 static int has_loose_object(const unsigned char *sha1)
 746 {
 747         return check_and_freshen(sha1, 0);
 748 }
 749
 750 static void mmap_limit_check(size_t length)
 751 {
 752         static size_t limit = 0;
 753         if (!limit) {
 754                 limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 755                 if (!limit)
 756                         limit = SIZE_MAX;
 757         }
 758         if (length > limit)
 759                 die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 760                     (uintmax_t)length, (uintmax_t)limit);
 761 }
 762
 763 void *xmmap_gently(void *start, size_t length,
 764                   int prot, int flags, int fd, off_t offset)
 765 {
 766         void *ret;
 767
 768         mmap_limit_check(length);
 769         ret = mmap(start, length, prot, flags, fd, offset);
 770         if (ret == MAP_FAILED) {
 771                 if (!length)
 772                         return NULL;
 773                 release_pack_memory(length);
 774                 ret = mmap(start, length, prot, flags, fd, offset);
 775         }
 776         return ret;
 777 }
 778
 779 void *xmmap(void *start, size_t length,
 780         int prot, int flags, int fd, off_t offset)
 781 {
 782         void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 783         if (ret == MAP_FAILED)
 784                 die_errno("mmap failed");
 785         return ret;
 786 }
 787
 788 /*
 789  * With an in-core object data in "map", rehash it to make sure the
 790  * object name actually matches "sha1" to detect object corruption.
 791  * With "map" == NULL, try reading the object named with "sha1" using
 792  * the streaming interface and rehash it to do the same.
 793  */
 794 int check_object_signature(const struct object_id *oid, void *map,
 795                            unsigned long size, const char *type)
 796 {
 797         struct object_id real_oid;
 798         enum object_type obj_type;
 799         struct git_istream *st;
 800         git_hash_ctx c;
 801         char hdr[MAX_HEADER_LEN];
 802         int hdrlen;
 803
 804         if (map) {
 805                 hash_object_file(map, size, type, &real_oid);
 806                 return oidcmp(oid, &real_oid) ? -1 : 0;
 807         }
 808
 809         st = open_istream(oid, &obj_type, &size, NULL);
 810         if (!st)
 811                 return -1;
 812
 813         /* Generate the header */
 814         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(obj_type), size) + 1;
 815
 816         /* Sha1.. */
 817         the_hash_algo->init_fn(&c);
 818         the_hash_algo->update_fn(&c, hdr, hdrlen);
 819         for (;;) {
 820                 char buf[1024 * 16];
 821                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 822
 823                 if (readlen < 0) {
 824                         close_istream(st);
 825                         return -1;
 826                 }
 827                 if (!readlen)
 828                         break;
 829                 the_hash_algo->update_fn(&c, buf, readlen);
 830         }
 831         the_hash_algo->final_fn(real_oid.hash, &c);
 832         close_istream(st);
 833         return oidcmp(oid, &real_oid) ? -1 : 0;
 834 }
 835
 836 int git_open_cloexec(const char *name, int flags)
 837 {
 838         int fd;
 839         static int o_cloexec = O_CLOEXEC;
 840
 841         fd = open(name, flags | o_cloexec);
 842         if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 843                 /* Try again w/o O_CLOEXEC: the kernel might not support it */
 844                 o_cloexec &= ~O_CLOEXEC;
 845                 fd = open(name, flags | o_cloexec);
 846         }
 847
 848 #if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 849         {
 850                 static int fd_cloexec = FD_CLOEXEC;
 851
 852                 if (!o_cloexec && 0 <= fd && fd_cloexec) {
 853                         /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 854                         int flags = fcntl(fd, F_GETFD);
 855                         if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 856                                 fd_cloexec = 0;
 857                 }
 858         }
 859 #endif
 860         return fd;
 861 }
 862
 863 /*
 864  * Find "sha1" as a loose object in the local repository or in an alternate.
 865  * Returns 0 on success, negative on failure.
 866  *
 867  * The "path" out-parameter will give the path of the object we found (if any).
 868  * Note that it may point to static storage and is only valid until another
 869  * call to sha1_file_name(), etc.
 870  */
 871 static int stat_sha1_file(struct repository *r, const unsigned char *sha1,
 872                           struct stat *st, const char **path)
 873 {
 874         struct alternate_object_database *alt;
 875         static struct strbuf buf = STRBUF_INIT;
 876
 877         strbuf_reset(&buf);
 878         sha1_file_name(r, &buf, sha1);
 879         *path = buf.buf;
 880
 881         if (!lstat(*path, st))
 882                 return 0;
 883
 884         prepare_alt_odb(r);
 885         errno = ENOENT;
 886         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 887                 *path = alt_sha1_path(alt, sha1);
 888                 if (!lstat(*path, st))
 889                         return 0;
 890         }
 891
 892         return -1;
 893 }
 894
 895 /*
 896  * Like stat_sha1_file(), but actually open the object and return the
 897  * descriptor. See the caveats on the "path" parameter above.
 898  */
 899 static int open_sha1_file(struct repository *r,
 900                           const unsigned char *sha1, const char **path)
 901 {
 902         int fd;
 903         struct alternate_object_database *alt;
 904         int most_interesting_errno;
 905         static struct strbuf buf = STRBUF_INIT;
 906
 907         strbuf_reset(&buf);
 908         sha1_file_name(r, &buf, sha1);
 909         *path = buf.buf;
 910
 911         fd = git_open(*path);
 912         if (fd >= 0)
 913                 return fd;
 914         most_interesting_errno = errno;
 915
 916         prepare_alt_odb(r);
 917         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 918                 *path = alt_sha1_path(alt, sha1);
 919                 fd = git_open(*path);
 920                 if (fd >= 0)
 921                         return fd;
 922                 if (most_interesting_errno == ENOENT)
 923                         most_interesting_errno = errno;
 924         }
 925         errno = most_interesting_errno;
 926         return -1;
 927 }
 928
 929 /*
 930  * Map the loose object at "path" if it is not NULL, or the path found by
 931  * searching for a loose object named "sha1".
 932  */
 933 static void *map_sha1_file_1(struct repository *r, const char *path,
 934                              const unsigned char *sha1, unsigned long *size)
 935 {
 936         void *map;
 937         int fd;
 938
 939         if (path)
 940                 fd = git_open(path);
 941         else
 942                 fd = open_sha1_file(r, sha1, &path);
 943         map = NULL;
 944         if (fd >= 0) {
 945                 struct stat st;
 946
 947                 if (!fstat(fd, &st)) {
 948                         *size = xsize_t(st.st_size);
 949                         if (!*size) {
 950                                 /* mmap() is forbidden on empty files */
 951                                 error("object file %s is empty", path);
 952                                 return NULL;
 953                         }
 954                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 955                 }
 956                 close(fd);
 957         }
 958         return map;
 959 }
 960
 961 void *map_sha1_file(struct repository *r,
 962                     const unsigned char *sha1, unsigned long *size)
 963 {
 964         return map_sha1_file_1(r, NULL, sha1, size);
 965 }
 966
 967 static int unpack_sha1_short_header(git_zstream *stream,
 968                                     unsigned char *map, unsigned long mapsize,
 969                                     void *buffer, unsigned long bufsiz)
 970 {
 971         /* Get the data stream */
 972         memset(stream, 0, sizeof(*stream));
 973         stream->next_in = map;
 974         stream->avail_in = mapsize;
 975         stream->next_out = buffer;
 976         stream->avail_out = bufsiz;
 977
 978         git_inflate_init(stream);
 979         return git_inflate(stream, 0);
 980 }
 981
 982 int unpack_sha1_header(git_zstream *stream,
 983                        unsigned char *map, unsigned long mapsize,
 984                        void *buffer, unsigned long bufsiz)
 985 {
 986         int status = unpack_sha1_short_header(stream, map, mapsize,
 987                                               buffer, bufsiz);
 988
 989         if (status < Z_OK)
 990                 return status;
 991
 992         /* Make sure we have the terminating NUL */
 993         if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 994                 return -1;
 995         return 0;
 996 }
 997
 998 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
 999                                         unsigned long mapsize, void *buffer,
1000                                         unsigned long bufsiz, struct strbuf *header)
1001 {
1002         int status;
1003
1004         status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
1005         if (status < Z_OK)
1006                 return -1;
1007
1008         /*
1009          * Check if entire header is unpacked in the first iteration.
1010          */
1011         if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1012                 return 0;
1013
1014         /*
1015          * buffer[0..bufsiz] was not large enough.  Copy the partial
1016          * result out to header, and then append the result of further
1017          * reading the stream.
1018          */
1019         strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1020         stream->next_out = buffer;
1021         stream->avail_out = bufsiz;
1022
1023         do {
1024                 status = git_inflate(stream, 0);
1025                 strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1026                 if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1027                         return 0;
1028                 stream->next_out = buffer;
1029                 stream->avail_out = bufsiz;
1030         } while (status != Z_STREAM_END);
1031         return -1;
1032 }
1033
1034 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1035 {
1036         int bytes = strlen(buffer) + 1;
1037         unsigned char *buf = xmallocz(size);
1038         unsigned long n;
1039         int status = Z_OK;
1040
1041         n = stream->total_out - bytes;
1042         if (n > size)
1043                 n = size;
1044         memcpy(buf, (char *) buffer + bytes, n);
1045         bytes = n;
1046         if (bytes <= size) {
1047                 /*
1048                  * The above condition must be (bytes <= size), not
1049                  * (bytes < size).  In other words, even though we
1050                  * expect no more output and set avail_out to zero,
1051                  * the input zlib stream may have bytes that express
1052                  * "this concludes the stream", and we *do* want to
1053                  * eat that input.
1054                  *
1055                  * Otherwise we would not be able to test that we
1056                  * consumed all the input to reach the expected size;
1057                  * we also want to check that zlib tells us that all
1058                  * went well with status == Z_STREAM_END at the end.
1059                  */
1060                 stream->next_out = buf + bytes;
1061                 stream->avail_out = size - bytes;
1062                 while (status == Z_OK)
1063                         status = git_inflate(stream, Z_FINISH);
1064         }
1065         if (status == Z_STREAM_END && !stream->avail_in) {
1066                 git_inflate_end(stream);
1067                 return buf;
1068         }
1069
1070         if (status < 0)
1071                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1072         else if (stream->avail_in)
1073                 error("garbage at end of loose object '%s'",
1074                       sha1_to_hex(sha1));
1075         free(buf);
1076         return NULL;
1077 }
1078
1079 /*
1080  * We used to just use "sscanf()", but that's actually way
1081  * too permissive for what we want to check. So do an anal
1082  * object header parse by hand.
1083  */
1084 static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1085                                unsigned int flags)
1086 {
1087         const char *type_buf = hdr;
1088         unsigned long size;
1089         int type, type_len = 0;
1090
1091         /*
1092          * The type can be of any size but is followed by
1093          * a space.
1094          */
1095         for (;;) {
1096                 char c = *hdr++;
1097                 if (!c)
1098                         return -1;
1099                 if (c == ' ')
1100                         break;
1101                 type_len++;
1102         }
1103
1104         type = type_from_string_gently(type_buf, type_len, 1);
1105         if (oi->type_name)
1106                 strbuf_add(oi->type_name, type_buf, type_len);
1107         /*
1108          * Set type to 0 if its an unknown object and
1109          * we're obtaining the type using '--allow-unknown-type'
1110          * option.
1111          */
1112         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
1113                 type = 0;
1114         else if (type < 0)
1115                 die("invalid object type");
1116         if (oi->typep)
1117                 *oi->typep = type;
1118
1119         /*
1120          * The length must follow immediately, and be in canonical
1121          * decimal format (ie "010" is not valid).
1122          */
1123         size = *hdr++ - '0';
1124         if (size > 9)
1125                 return -1;
1126         if (size) {
1127                 for (;;) {
1128                         unsigned long c = *hdr - '0';
1129                         if (c > 9)
1130                                 break;
1131                         hdr++;
1132                         size = size * 10 + c;
1133                 }
1134         }
1135
1136         if (oi->sizep)
1137                 *oi->sizep = size;
1138
1139         /*
1140          * The length must be followed by a zero byte
1141          */
1142         return *hdr ? -1 : type;
1143 }
1144
1145 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1146 {
1147         struct object_info oi = OBJECT_INFO_INIT;
1148
1149         oi.sizep = sizep;
1150         return parse_sha1_header_extended(hdr, &oi, 0);
1151 }
1152
1153 static int sha1_loose_object_info(struct repository *r,
1154                                   const unsigned char *sha1,
1155                                   struct object_info *oi, int flags)
1156 {
1157         int status = 0;
1158         unsigned long mapsize;
1159         void *map;
1160         git_zstream stream;
1161         char hdr[MAX_HEADER_LEN];
1162         struct strbuf hdrbuf = STRBUF_INIT;
1163         unsigned long size_scratch;
1164
1165         if (oi->delta_base_sha1)
1166                 hashclr(oi->delta_base_sha1);
1167
1168         /*
1169          * If we don't care about type or size, then we don't
1170          * need to look inside the object at all. Note that we
1171          * do not optimize out the stat call, even if the
1172          * caller doesn't care about the disk-size, since our
1173          * return value implicitly indicates whether the
1174          * object even exists.
1175          */
1176         if (!oi->typep && !oi->type_name && !oi->sizep && !oi->contentp) {
1177                 const char *path;
1178                 struct stat st;
1179                 if (stat_sha1_file(r, sha1, &st, &path) < 0)
1180                         return -1;
1181                 if (oi->disk_sizep)
1182                         *oi->disk_sizep = st.st_size;
1183                 return 0;
1184         }
1185
1186         map = map_sha1_file(r, sha1, &mapsize);
1187         if (!map)
1188                 return -1;
1189
1190         if (!oi->sizep)
1191                 oi->sizep = &size_scratch;
1192
1193         if (oi->disk_sizep)
1194                 *oi->disk_sizep = mapsize;
1195         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
1196                 if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
1197                         status = error("unable to unpack %s header with --allow-unknown-type",
1198                                        sha1_to_hex(sha1));
1199         } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1200                 status = error("unable to unpack %s header",
1201                                sha1_to_hex(sha1));
1202         if (status < 0)
1203                 ; /* Do nothing */
1204         else if (hdrbuf.len) {
1205                 if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
1206                         status = error("unable to parse %s header with --allow-unknown-type",
1207                                        sha1_to_hex(sha1));
1208         } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
1209                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1210
1211         if (status >= 0 && oi->contentp) {
1212                 *oi->contentp = unpack_sha1_rest(&stream, hdr,
1213                                                  *oi->sizep, sha1);
1214                 if (!*oi->contentp) {
1215                         git_inflate_end(&stream);
1216                         status = -1;
1217                 }
1218         } else
1219                 git_inflate_end(&stream);
1220
1221         munmap(map, mapsize);
1222         if (status && oi->typep)
1223                 *oi->typep = status;
1224         if (oi->sizep == &size_scratch)
1225                 oi->sizep = NULL;
1226         strbuf_release(&hdrbuf);
1227         oi->whence = OI_LOOSE;
1228         return (status < 0) ? status : 0;
1229 }
1230
1231 int fetch_if_missing = 1;
1232
1233 int oid_object_info_extended(const struct object_id *oid, struct object_info *oi, unsigned flags)
1234 {
1235         static struct object_info blank_oi = OBJECT_INFO_INIT;
1236         struct pack_entry e;
1237         int rtype;
1238         const struct object_id *real = oid;
1239         int already_retried = 0;
1240
1241         if (flags & OBJECT_INFO_LOOKUP_REPLACE)
1242                 real = lookup_replace_object(oid);
1243
1244         if (is_null_oid(real))
1245                 return -1;
1246
1247         if (!oi)
1248                 oi = &blank_oi;
1249
1250         if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
1251                 struct cached_object *co = find_cached_object(real->hash);
1252                 if (co) {
1253                         if (oi->typep)
1254                                 *(oi->typep) = co->type;
1255                         if (oi->sizep)
1256                                 *(oi->sizep) = co->size;
1257                         if (oi->disk_sizep)
1258                                 *(oi->disk_sizep) = 0;
1259                         if (oi->delta_base_sha1)
1260                                 hashclr(oi->delta_base_sha1);
1261                         if (oi->type_name)
1262                                 strbuf_addstr(oi->type_name, type_name(co->type));
1263                         if (oi->contentp)
1264                                 *oi->contentp = xmemdupz(co->buf, co->size);
1265                         oi->whence = OI_CACHED;
1266                         return 0;
1267                 }
1268         }
1269
1270         while (1) {
1271                 if (find_pack_entry(the_repository, real->hash, &e))
1272                         break;
1273
1274                 if (flags & OBJECT_INFO_IGNORE_LOOSE)
1275                         return -1;
1276
1277                 /* Most likely it's a loose object. */
1278                 if (!sha1_loose_object_info(the_repository, real->hash, oi, flags))
1279                         return 0;
1280
1281                 /* Not a loose object; someone else may have just packed it. */
1282                 if (!(flags & OBJECT_INFO_QUICK)) {
1283                         reprepare_packed_git(the_repository);
1284                         if (find_pack_entry(the_repository, real->hash, &e))
1285                                 break;
1286                 }
1287
1288                 /* Check if it is a missing object */
1289                 if (fetch_if_missing && repository_format_partial_clone &&
1290                     !already_retried) {
1291                         /*
1292                          * TODO Investigate haveing fetch_object() return
1293                          * TODO error/success and stopping the music here.
1294                          */
1295                         fetch_object(repository_format_partial_clone, real->hash);
1296                         already_retried = 1;
1297                         continue;
1298                 }
1299
1300                 return -1;
1301         }
1302
1303         if (oi == &blank_oi)
1304                 /*
1305                  * We know that the caller doesn't actually need the
1306                  * information below, so return early.
1307                  */
1308                 return 0;
1309         rtype = packed_object_info(e.p, e.offset, oi);
1310         if (rtype < 0) {
1311                 mark_bad_packed_object(e.p, real->hash);
1312                 return oid_object_info_extended(real, oi, 0);
1313         } else if (oi->whence == OI_PACKED) {
1314                 oi->u.packed.offset = e.offset;
1315                 oi->u.packed.pack = e.p;
1316                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
1317                                          rtype == OBJ_OFS_DELTA);
1318         }
1319
1320         return 0;
1321 }
1322
1323 /* returns enum object_type or negative */
1324 int oid_object_info(const struct object_id *oid, unsigned long *sizep)
1325 {
1326         enum object_type type;
1327         struct object_info oi = OBJECT_INFO_INIT;
1328
1329         oi.typep = &type;
1330         oi.sizep = sizep;
1331         if (oid_object_info_extended(oid, &oi,
1332                                      OBJECT_INFO_LOOKUP_REPLACE) < 0)
1333                 return -1;
1334         return type;
1335 }
1336
1337 static void *read_object(const unsigned char *sha1, enum object_type *type,
1338                          unsigned long *size)
1339 {
1340         struct object_id oid;
1341         struct object_info oi = OBJECT_INFO_INIT;
1342         void *content;
1343         oi.typep = type;
1344         oi.sizep = size;
1345         oi.contentp = &content;
1346
1347         hashcpy(oid.hash, sha1);
1348
1349         if (oid_object_info_extended(&oid, &oi, 0) < 0)
1350                 return NULL;
1351         return content;
1352 }
1353
1354 int pretend_object_file(void *buf, unsigned long len, enum object_type type,
1355                         struct object_id *oid)
1356 {
1357         struct cached_object *co;
1358
1359         hash_object_file(buf, len, type_name(type), oid);
1360         if (has_sha1_file(oid->hash) || find_cached_object(oid->hash))
1361                 return 0;
1362         ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
1363         co = &cached_objects[cached_object_nr++];
1364         co->size = len;
1365         co->type = type;
1366         co->buf = xmalloc(len);
1367         memcpy(co->buf, buf, len);
1368         hashcpy(co->sha1, oid->hash);
1369         return 0;
1370 }
1371
1372 /*
1373  * This function dies on corrupt objects; the callers who want to
1374  * deal with them should arrange to call read_object() and give error
1375  * messages themselves.
1376  */
1377 void *read_object_file_extended(const struct object_id *oid,
1378                                 enum object_type *type,
1379                                 unsigned long *size,
1380                                 int lookup_replace)
1381 {
1382         void *data;
1383         const struct packed_git *p;
1384         const char *path;
1385         struct stat st;
1386         const struct object_id *repl = lookup_replace ? lookup_replace_object(oid)
1387                                                       : oid;
1388
1389         errno = 0;
1390         data = read_object(repl->hash, type, size);
1391         if (data)
1392                 return data;
1393
1394         if (errno && errno != ENOENT)
1395                 die_errno("failed to read object %s", oid_to_hex(oid));
1396
1397         /* die if we replaced an object with one that does not exist */
1398         if (repl != oid)
1399                 die("replacement %s not found for %s",
1400                     oid_to_hex(repl), oid_to_hex(oid));
1401
1402         if (!stat_sha1_file(the_repository, repl->hash, &st, &path))
1403                 die("loose object %s (stored in %s) is corrupt",
1404                     oid_to_hex(repl), path);
1405
1406         if ((p = has_packed_and_bad(repl->hash)) != NULL)
1407                 die("packed object %s (stored in %s) is corrupt",
1408                     oid_to_hex(repl), p->pack_name);
1409
1410         return NULL;
1411 }
1412
1413 void *read_object_with_reference(const struct object_id *oid,
1414                                  const char *required_type_name,
1415                                  unsigned long *size,
1416                                  struct object_id *actual_oid_return)
1417 {
1418         enum object_type type, required_type;
1419         void *buffer;
1420         unsigned long isize;
1421         struct object_id actual_oid;
1422
1423         required_type = type_from_string(required_type_name);
1424         oidcpy(&actual_oid, oid);
1425         while (1) {
1426                 int ref_length = -1;
1427                 const char *ref_type = NULL;
1428
1429                 buffer = read_object_file(&actual_oid, &type, &isize);
1430                 if (!buffer)
1431                         return NULL;
1432                 if (type == required_type) {
1433                         *size = isize;
1434                         if (actual_oid_return)
1435                                 oidcpy(actual_oid_return, &actual_oid);
1436                         return buffer;
1437                 }
1438                 /* Handle references */
1439                 else if (type == OBJ_COMMIT)
1440                         ref_type = "tree ";
1441                 else if (type == OBJ_TAG)
1442                         ref_type = "object ";
1443                 else {
1444                         free(buffer);
1445                         return NULL;
1446                 }
1447                 ref_length = strlen(ref_type);
1448
1449                 if (ref_length + GIT_SHA1_HEXSZ > isize ||
1450                     memcmp(buffer, ref_type, ref_length) ||
1451                     get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
1452                         free(buffer);
1453                         return NULL;
1454                 }
1455                 free(buffer);
1456                 /* Now we have the ID of the referred-to object in
1457                  * actual_oid.  Check again. */
1458         }
1459 }
1460
1461 static void write_object_file_prepare(const void *buf, unsigned long len,
1462                                       const char *type, struct object_id *oid,
1463                                       char *hdr, int *hdrlen)
1464 {
1465         git_hash_ctx c;
1466
1467         /* Generate the header */
1468         *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
1469
1470         /* Sha1.. */
1471         the_hash_algo->init_fn(&c);
1472         the_hash_algo->update_fn(&c, hdr, *hdrlen);
1473         the_hash_algo->update_fn(&c, buf, len);
1474         the_hash_algo->final_fn(oid->hash, &c);
1475 }
1476
1477 /*
1478  * Move the just written object into its final resting place.
1479  */
1480 int finalize_object_file(const char *tmpfile, const char *filename)
1481 {
1482         int ret = 0;
1483
1484         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
1485                 goto try_rename;
1486         else if (link(tmpfile, filename))
1487                 ret = errno;
1488
1489         /*
1490          * Coda hack - coda doesn't like cross-directory links,
1491          * so we fall back to a rename, which will mean that it
1492          * won't be able to check collisions, but that's not a
1493          * big deal.
1494          *
1495          * The same holds for FAT formatted media.
1496          *
1497          * When this succeeds, we just return.  We have nothing
1498          * left to unlink.
1499          */
1500         if (ret && ret != EEXIST) {
1501         try_rename:
1502                 if (!rename(tmpfile, filename))
1503                         goto out;
1504                 ret = errno;
1505         }
1506         unlink_or_warn(tmpfile);
1507         if (ret) {
1508                 if (ret != EEXIST) {
1509                         return error_errno("unable to write sha1 filename %s", filename);
1510                 }
1511                 /* FIXME!!! Collision check here ? */
1512         }
1513
1514 out:
1515         if (adjust_shared_perm(filename))
1516                 return error("unable to set permission to '%s'", filename);
1517         return 0;
1518 }
1519
1520 static int write_buffer(int fd, const void *buf, size_t len)
1521 {
1522         if (write_in_full(fd, buf, len) < 0)
1523                 return error_errno("file write error");
1524         return 0;
1525 }
1526
1527 int hash_object_file(const void *buf, unsigned long len, const char *type,
1528                      struct object_id *oid)
1529 {
1530         char hdr[MAX_HEADER_LEN];
1531         int hdrlen = sizeof(hdr);
1532         write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
1533         return 0;
1534 }
1535
1536 /* Finalize a file on disk, and close it. */
1537 static void close_sha1_file(int fd)
1538 {
1539         if (fsync_object_files)
1540                 fsync_or_die(fd, "sha1 file");
1541         if (close(fd) != 0)
1542                 die_errno("error when closing sha1 file");
1543 }
1544
1545 /* Size of directory component, including the ending '/' */
1546 static inline int directory_size(const char *filename)
1547 {
1548         const char *s = strrchr(filename, '/');
1549         if (!s)
1550                 return 0;
1551         return s - filename + 1;
1552 }
1553
1554 /*
1555  * This creates a temporary file in the same directory as the final
1556  * 'filename'
1557  *
1558  * We want to avoid cross-directory filename renames, because those
1559  * can have problems on various filesystems (FAT, NFS, Coda).
1560  */
1561 static int create_tmpfile(struct strbuf *tmp, const char *filename)
1562 {
1563         int fd, dirlen = directory_size(filename);
1564
1565         strbuf_reset(tmp);
1566         strbuf_add(tmp, filename, dirlen);
1567         strbuf_addstr(tmp, "tmp_obj_XXXXXX");
1568         fd = git_mkstemp_mode(tmp->buf, 0444);
1569         if (fd < 0 && dirlen && errno == ENOENT) {
1570                 /*
1571                  * Make sure the directory exists; note that the contents
1572                  * of the buffer are undefined after mkstemp returns an
1573                  * error, so we have to rewrite the whole buffer from
1574                  * scratch.
1575                  */
1576                 strbuf_reset(tmp);
1577                 strbuf_add(tmp, filename, dirlen - 1);
1578                 if (mkdir(tmp->buf, 0777) && errno != EEXIST)
1579                         return -1;
1580                 if (adjust_shared_perm(tmp->buf))
1581                         return -1;
1582
1583                 /* Try again */
1584                 strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
1585                 fd = git_mkstemp_mode(tmp->buf, 0444);
1586         }
1587         return fd;
1588 }
1589
1590 static int write_loose_object(const struct object_id *oid, char *hdr,
1591                               int hdrlen, const void *buf, unsigned long len,
1592                               time_t mtime)
1593 {
1594         int fd, ret;
1595         unsigned char compressed[4096];
1596         git_zstream stream;
1597         git_hash_ctx c;
1598         struct object_id parano_oid;
1599         static struct strbuf tmp_file = STRBUF_INIT;
1600         static struct strbuf filename = STRBUF_INIT;
1601
1602         strbuf_reset(&filename);
1603         sha1_file_name(the_repository, &filename, oid->hash);
1604
1605         fd = create_tmpfile(&tmp_file, filename.buf);
1606         if (fd < 0) {
1607                 if (errno == EACCES)
1608                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
1609                 else
1610                         return error_errno("unable to create temporary file");
1611         }
1612
1613         /* Set it up */
1614         git_deflate_init(&stream, zlib_compression_level);
1615         stream.next_out = compressed;
1616         stream.avail_out = sizeof(compressed);
1617         the_hash_algo->init_fn(&c);
1618
1619         /* First header.. */
1620         stream.next_in = (unsigned char *)hdr;
1621         stream.avail_in = hdrlen;
1622         while (git_deflate(&stream, 0) == Z_OK)
1623                 ; /* nothing */
1624         the_hash_algo->update_fn(&c, hdr, hdrlen);
1625
1626         /* Then the data itself.. */
1627         stream.next_in = (void *)buf;
1628         stream.avail_in = len;
1629         do {
1630                 unsigned char *in0 = stream.next_in;
1631                 ret = git_deflate(&stream, Z_FINISH);
1632                 the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
1633                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
1634                         die("unable to write sha1 file");
1635                 stream.next_out = compressed;
1636                 stream.avail_out = sizeof(compressed);
1637         } while (ret == Z_OK);
1638
1639         if (ret != Z_STREAM_END)
1640                 die("unable to deflate new object %s (%d)", oid_to_hex(oid),
1641                     ret);
1642         ret = git_deflate_end_gently(&stream);
1643         if (ret != Z_OK)
1644                 die("deflateEnd on object %s failed (%d)", oid_to_hex(oid),
1645                     ret);
1646         the_hash_algo->final_fn(parano_oid.hash, &c);
1647         if (oidcmp(oid, &parano_oid) != 0)
1648                 die("confused by unstable object source data for %s",
1649                     oid_to_hex(oid));
1650
1651         close_sha1_file(fd);
1652
1653         if (mtime) {
1654                 struct utimbuf utb;
1655                 utb.actime = mtime;
1656                 utb.modtime = mtime;
1657                 if (utime(tmp_file.buf, &utb) < 0)
1658                         warning_errno("failed utime() on %s", tmp_file.buf);
1659         }
1660
1661         return finalize_object_file(tmp_file.buf, filename.buf);
1662 }
1663
1664 static int freshen_loose_object(const unsigned char *sha1)
1665 {
1666         return check_and_freshen(sha1, 1);
1667 }
1668
1669 static int freshen_packed_object(const unsigned char *sha1)
1670 {
1671         struct pack_entry e;
1672         if (!find_pack_entry(the_repository, sha1, &e))
1673                 return 0;
1674         if (e.p->freshened)
1675                 return 1;
1676         if (!freshen_file(e.p->pack_name))
1677                 return 0;
1678         e.p->freshened = 1;
1679         return 1;
1680 }
1681
1682 int write_object_file(const void *buf, unsigned long len, const char *type,
1683                       struct object_id *oid)
1684 {
1685         char hdr[MAX_HEADER_LEN];
1686         int hdrlen = sizeof(hdr);
1687
1688         /* Normally if we have it in the pack then we do not bother writing
1689          * it out into .git/objects/??/?{38} file.
1690          */
1691         write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
1692         if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1693                 return 0;
1694         return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
1695 }
1696
1697 int hash_object_file_literally(const void *buf, unsigned long len,
1698                                const char *type, struct object_id *oid,
1699                                unsigned flags)
1700 {
1701         char *header;
1702         int hdrlen, status = 0;
1703
1704         /* type string, SP, %lu of the length plus NUL must fit this */
1705         hdrlen = strlen(type) + MAX_HEADER_LEN;
1706         header = xmalloc(hdrlen);
1707         write_object_file_prepare(buf, len, type, oid, header, &hdrlen);
1708
1709         if (!(flags & HASH_WRITE_OBJECT))
1710                 goto cleanup;
1711         if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1712                 goto cleanup;
1713         status = write_loose_object(oid, header, hdrlen, buf, len, 0);
1714
1715 cleanup:
1716         free(header);
1717         return status;
1718 }
1719
1720 int force_object_loose(const struct object_id *oid, time_t mtime)
1721 {
1722         void *buf;
1723         unsigned long len;
1724         enum object_type type;
1725         char hdr[MAX_HEADER_LEN];
1726         int hdrlen;
1727         int ret;
1728
1729         if (has_loose_object(oid->hash))
1730                 return 0;
1731         buf = read_object(oid->hash, &type, &len);
1732         if (!buf)
1733                 return error("cannot read sha1_file for %s", oid_to_hex(oid));
1734         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(type), len) + 1;
1735         ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
1736         free(buf);
1737
1738         return ret;
1739 }
1740
1741 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
1742 {
1743         struct object_id oid;
1744         if (!startup_info->have_repository)
1745                 return 0;
1746         hashcpy(oid.hash, sha1);
1747         return oid_object_info_extended(&oid, NULL,
1748                                         flags | OBJECT_INFO_SKIP_CACHED) >= 0;
1749 }
1750
1751 int has_object_file(const struct object_id *oid)
1752 {
1753         return has_sha1_file(oid->hash);
1754 }
1755
1756 int has_object_file_with_flags(const struct object_id *oid, int flags)
1757 {
1758         return has_sha1_file_with_flags(oid->hash, flags);
1759 }
1760
1761 static void check_tree(const void *buf, size_t size)
1762 {
1763         struct tree_desc desc;
1764         struct name_entry entry;
1765
1766         init_tree_desc(&desc, buf, size);
1767         while (tree_entry(&desc, &entry))
1768                 /* do nothing
1769                  * tree_entry() will die() on malformed entries */
1770                 ;
1771 }
1772
1773 static void check_commit(const void *buf, size_t size)
1774 {
1775         struct commit c;
1776         memset(&c, 0, sizeof(c));
1777         if (parse_commit_buffer(&c, buf, size))
1778                 die("corrupt commit");
1779 }
1780
1781 static void check_tag(const void *buf, size_t size)
1782 {
1783         struct tag t;
1784         memset(&t, 0, sizeof(t));
1785         if (parse_tag_buffer(&t, buf, size))
1786                 die("corrupt tag");
1787 }
1788
1789 static int index_mem(struct object_id *oid, void *buf, size_t size,
1790                      enum object_type type,
1791                      const char *path, unsigned flags)
1792 {
1793         int ret, re_allocated = 0;
1794         int write_object = flags & HASH_WRITE_OBJECT;
1795
1796         if (!type)
1797                 type = OBJ_BLOB;
1798
1799         /*
1800          * Convert blobs to git internal format
1801          */
1802         if ((type == OBJ_BLOB) && path) {
1803                 struct strbuf nbuf = STRBUF_INIT;
1804                 if (convert_to_git(&the_index, path, buf, size, &nbuf,
1805                                    get_conv_flags(flags))) {
1806                         buf = strbuf_detach(&nbuf, &size);
1807                         re_allocated = 1;
1808                 }
1809         }
1810         if (flags & HASH_FORMAT_CHECK) {
1811                 if (type == OBJ_TREE)
1812                         check_tree(buf, size);
1813                 if (type == OBJ_COMMIT)
1814                         check_commit(buf, size);
1815                 if (type == OBJ_TAG)
1816                         check_tag(buf, size);
1817         }
1818
1819         if (write_object)
1820                 ret = write_object_file(buf, size, type_name(type), oid);
1821         else
1822                 ret = hash_object_file(buf, size, type_name(type), oid);
1823         if (re_allocated)
1824                 free(buf);
1825         return ret;
1826 }
1827
1828 static int index_stream_convert_blob(struct object_id *oid, int fd,
1829                                      const char *path, unsigned flags)
1830 {
1831         int ret;
1832         const int write_object = flags & HASH_WRITE_OBJECT;
1833         struct strbuf sbuf = STRBUF_INIT;
1834
1835         assert(path);
1836         assert(would_convert_to_git_filter_fd(path));
1837
1838         convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
1839                                  get_conv_flags(flags));
1840
1841         if (write_object)
1842                 ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1843                                         oid);
1844         else
1845                 ret = hash_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1846                                        oid);
1847         strbuf_release(&sbuf);
1848         return ret;
1849 }
1850
1851 static int index_pipe(struct object_id *oid, int fd, enum object_type type,
1852                       const char *path, unsigned flags)
1853 {
1854         struct strbuf sbuf = STRBUF_INIT;
1855         int ret;
1856
1857         if (strbuf_read(&sbuf, fd, 4096) >= 0)
1858                 ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
1859         else
1860                 ret = -1;
1861         strbuf_release(&sbuf);
1862         return ret;
1863 }
1864
1865 #define SMALL_FILE_SIZE (32*1024)
1866
1867 static int index_core(struct object_id *oid, int fd, size_t size,
1868                       enum object_type type, const char *path,
1869                       unsigned flags)
1870 {
1871         int ret;
1872
1873         if (!size) {
1874                 ret = index_mem(oid, "", size, type, path, flags);
1875         } else if (size <= SMALL_FILE_SIZE) {
1876                 char *buf = xmalloc(size);
1877                 ssize_t read_result = read_in_full(fd, buf, size);
1878                 if (read_result < 0)
1879                         ret = error_errno("read error while indexing %s",
1880                                           path ? path : "<unknown>");
1881                 else if (read_result != size)
1882                         ret = error("short read while indexing %s",
1883                                     path ? path : "<unknown>");
1884                 else
1885                         ret = index_mem(oid, buf, size, type, path, flags);
1886                 free(buf);
1887         } else {
1888                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1889                 ret = index_mem(oid, buf, size, type, path, flags);
1890                 munmap(buf, size);
1891         }
1892         return ret;
1893 }
1894
1895 /*
1896  * This creates one packfile per large blob unless bulk-checkin
1897  * machinery is "plugged".
1898  *
1899  * This also bypasses the usual "convert-to-git" dance, and that is on
1900  * purpose. We could write a streaming version of the converting
1901  * functions and insert that before feeding the data to fast-import
1902  * (or equivalent in-core API described above). However, that is
1903  * somewhat complicated, as we do not know the size of the filter
1904  * result, which we need to know beforehand when writing a git object.
1905  * Since the primary motivation for trying to stream from the working
1906  * tree file and to avoid mmaping it in core is to deal with large
1907  * binary blobs, they generally do not want to get any conversion, and
1908  * callers should avoid this code path when filters are requested.
1909  */
1910 static int index_stream(struct object_id *oid, int fd, size_t size,
1911                         enum object_type type, const char *path,
1912                         unsigned flags)
1913 {
1914         return index_bulk_checkin(oid, fd, size, type, path, flags);
1915 }
1916
1917 int index_fd(struct object_id *oid, int fd, struct stat *st,
1918              enum object_type type, const char *path, unsigned flags)
1919 {
1920         int ret;
1921
1922         /*
1923          * Call xsize_t() only when needed to avoid potentially unnecessary
1924          * die() for large files.
1925          */
1926         if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
1927                 ret = index_stream_convert_blob(oid, fd, path, flags);
1928         else if (!S_ISREG(st->st_mode))
1929                 ret = index_pipe(oid, fd, type, path, flags);
1930         else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
1931                  (path && would_convert_to_git(&the_index, path)))
1932                 ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
1933                                  flags);
1934         else
1935                 ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
1936                                    flags);
1937         close(fd);
1938         return ret;
1939 }
1940
1941 int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
1942 {
1943         int fd;
1944         struct strbuf sb = STRBUF_INIT;
1945         int rc = 0;
1946
1947         switch (st->st_mode & S_IFMT) {
1948         case S_IFREG:
1949                 fd = open(path, O_RDONLY);
1950                 if (fd < 0)
1951                         return error_errno("open(\"%s\")", path);
1952                 if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
1953                         return error("%s: failed to insert into database",
1954                                      path);
1955                 break;
1956         case S_IFLNK:
1957                 if (strbuf_readlink(&sb, path, st->st_size))
1958                         return error_errno("readlink(\"%s\")", path);
1959                 if (!(flags & HASH_WRITE_OBJECT))
1960                         hash_object_file(sb.buf, sb.len, blob_type, oid);
1961                 else if (write_object_file(sb.buf, sb.len, blob_type, oid))
1962                         rc = error("%s: failed to insert into database", path);
1963                 strbuf_release(&sb);
1964                 break;
1965         case S_IFDIR:
1966                 return resolve_gitlink_ref(path, "HEAD", oid);
1967         default:
1968                 return error("%s: unsupported file type", path);
1969         }
1970         return rc;
1971 }
1972
1973 int read_pack_header(int fd, struct pack_header *header)
1974 {
1975         if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
1976                 /* "eof before pack header was fully read" */
1977                 return PH_ERROR_EOF;
1978
1979         if (header->hdr_signature != htonl(PACK_SIGNATURE))
1980                 /* "protocol error (pack signature mismatch detected)" */
1981                 return PH_ERROR_PACK_SIGNATURE;
1982         if (!pack_version_ok(header->hdr_version))
1983                 /* "protocol error (pack version unsupported)" */
1984                 return PH_ERROR_PROTOCOL;
1985         return 0;
1986 }
1987
1988 void assert_oid_type(const struct object_id *oid, enum object_type expect)
1989 {
1990         enum object_type type = oid_object_info(oid, NULL);
1991         if (type < 0)
1992                 die("%s is not a valid object", oid_to_hex(oid));
1993         if (type != expect)
1994                 die("%s is not a valid '%s' object", oid_to_hex(oid),
1995                     type_name(expect));
1996 }
1997
1998 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
1999                                 struct strbuf *path,
2000                                 each_loose_object_fn obj_cb,
2001                                 each_loose_cruft_fn cruft_cb,
2002                                 each_loose_subdir_fn subdir_cb,
2003                                 void *data)
2004 {
2005         size_t origlen, baselen;
2006         DIR *dir;
2007         struct dirent *de;
2008         int r = 0;
2009         struct object_id oid;
2010
2011         if (subdir_nr > 0xff)
2012                 BUG("invalid loose object subdirectory: %x", subdir_nr);
2013
2014         origlen = path->len;
2015         strbuf_complete(path, '/');
2016         strbuf_addf(path, "%02x", subdir_nr);
2017
2018         dir = opendir(path->buf);
2019         if (!dir) {
2020                 if (errno != ENOENT)
2021                         r = error_errno("unable to open %s", path->buf);
2022                 strbuf_setlen(path, origlen);
2023                 return r;
2024         }
2025
2026         oid.hash[0] = subdir_nr;
2027         strbuf_addch(path, '/');
2028         baselen = path->len;
2029
2030         while ((de = readdir(dir))) {
2031                 size_t namelen;
2032                 if (is_dot_or_dotdot(de->d_name))
2033                         continue;
2034
2035                 namelen = strlen(de->d_name);
2036                 strbuf_setlen(path, baselen);
2037                 strbuf_add(path, de->d_name, namelen);
2038                 if (namelen == GIT_SHA1_HEXSZ - 2 &&
2039                     !hex_to_bytes(oid.hash + 1, de->d_name,
2040                                   GIT_SHA1_RAWSZ - 1)) {
2041                         if (obj_cb) {
2042                                 r = obj_cb(&oid, path->buf, data);
2043                                 if (r)
2044                                         break;
2045                         }
2046                         continue;
2047                 }
2048
2049                 if (cruft_cb) {
2050                         r = cruft_cb(de->d_name, path->buf, data);
2051                         if (r)
2052                                 break;
2053                 }
2054         }
2055         closedir(dir);
2056
2057         strbuf_setlen(path, baselen - 1);
2058         if (!r && subdir_cb)
2059                 r = subdir_cb(subdir_nr, path->buf, data);
2060
2061         strbuf_setlen(path, origlen);
2062
2063         return r;
2064 }
2065
2066 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
2067                             each_loose_object_fn obj_cb,
2068                             each_loose_cruft_fn cruft_cb,
2069                             each_loose_subdir_fn subdir_cb,
2070                             void *data)
2071 {
2072         int r = 0;
2073         int i;
2074
2075         for (i = 0; i < 256; i++) {
2076                 r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
2077                                                 subdir_cb, data);
2078                 if (r)
2079                         break;
2080         }
2081
2082         return r;
2083 }
2084
2085 int for_each_loose_file_in_objdir(const char *path,
2086                                   each_loose_object_fn obj_cb,
2087                                   each_loose_cruft_fn cruft_cb,
2088                                   each_loose_subdir_fn subdir_cb,
2089                                   void *data)
2090 {
2091         struct strbuf buf = STRBUF_INIT;
2092         int r;
2093
2094         strbuf_addstr(&buf, path);
2095         r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
2096                                               subdir_cb, data);
2097         strbuf_release(&buf);
2098
2099         return r;
2100 }
2101
2102 struct loose_alt_odb_data {
2103         each_loose_object_fn *cb;
2104         void *data;
2105 };
2106
2107 static int loose_from_alt_odb(struct alternate_object_database *alt,
2108                               void *vdata)
2109 {
2110         struct loose_alt_odb_data *data = vdata;
2111         struct strbuf buf = STRBUF_INIT;
2112         int r;
2113
2114         strbuf_addstr(&buf, alt->path);
2115         r = for_each_loose_file_in_objdir_buf(&buf,
2116                                               data->cb, NULL, NULL,
2117                                               data->data);
2118         strbuf_release(&buf);
2119         return r;
2120 }
2121
2122 int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
2123 {
2124         struct loose_alt_odb_data alt;
2125         int r;
2126
2127         r = for_each_loose_file_in_objdir(get_object_directory(),
2128                                           cb, NULL, NULL, data);
2129         if (r)
2130                 return r;
2131
2132         if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
2133                 return 0;
2134
2135         alt.cb = cb;
2136         alt.data = data;
2137         return foreach_alt_odb(loose_from_alt_odb, &alt);
2138 }
2139
2140 static int check_stream_sha1(git_zstream *stream,
2141                              const char *hdr,
2142                              unsigned long size,
2143                              const char *path,
2144                              const unsigned char *expected_sha1)
2145 {
2146         git_hash_ctx c;
2147         unsigned char real_sha1[GIT_MAX_RAWSZ];
2148         unsigned char buf[4096];
2149         unsigned long total_read;
2150         int status = Z_OK;
2151
2152         the_hash_algo->init_fn(&c);
2153         the_hash_algo->update_fn(&c, hdr, stream->total_out);
2154
2155         /*
2156          * We already read some bytes into hdr, but the ones up to the NUL
2157          * do not count against the object's content size.
2158          */
2159         total_read = stream->total_out - strlen(hdr) - 1;
2160
2161         /*
2162          * This size comparison must be "<=" to read the final zlib packets;
2163          * see the comment in unpack_sha1_rest for details.
2164          */
2165         while (total_read <= size &&
2166                (status == Z_OK || status == Z_BUF_ERROR)) {
2167                 stream->next_out = buf;
2168                 stream->avail_out = sizeof(buf);
2169                 if (size - total_read < stream->avail_out)
2170                         stream->avail_out = size - total_read;
2171                 status = git_inflate(stream, Z_FINISH);
2172                 the_hash_algo->update_fn(&c, buf, stream->next_out - buf);
2173                 total_read += stream->next_out - buf;
2174         }
2175         git_inflate_end(stream);
2176
2177         if (status != Z_STREAM_END) {
2178                 error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
2179                 return -1;
2180         }
2181         if (stream->avail_in) {
2182                 error("garbage at end of loose object '%s'",
2183                       sha1_to_hex(expected_sha1));
2184                 return -1;
2185         }
2186
2187         the_hash_algo->final_fn(real_sha1, &c);
2188         if (hashcmp(expected_sha1, real_sha1)) {
2189                 error("sha1 mismatch for %s (expected %s)", path,
2190                       sha1_to_hex(expected_sha1));
2191                 return -1;
2192         }
2193
2194         return 0;
2195 }
2196
2197 int read_loose_object(const char *path,
2198                       const struct object_id *expected_oid,
2199                       enum object_type *type,
2200                       unsigned long *size,
2201                       void **contents)
2202 {
2203         int ret = -1;
2204         void *map = NULL;
2205         unsigned long mapsize;
2206         git_zstream stream;
2207         char hdr[MAX_HEADER_LEN];
2208
2209         *contents = NULL;
2210
2211         map = map_sha1_file_1(the_repository, path, NULL, &mapsize);
2212         if (!map) {
2213                 error_errno("unable to mmap %s", path);
2214                 goto out;
2215         }
2216
2217         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
2218                 error("unable to unpack header of %s", path);
2219                 goto out;
2220         }
2221
2222         *type = parse_sha1_header(hdr, size);
2223         if (*type < 0) {
2224                 error("unable to parse header of %s", path);
2225                 git_inflate_end(&stream);
2226                 goto out;
2227         }
2228
2229         if (*type == OBJ_BLOB) {
2230                 if (check_stream_sha1(&stream, hdr, *size, path, expected_oid->hash) < 0)
2231                         goto out;
2232         } else {
2233                 *contents = unpack_sha1_rest(&stream, hdr, *size, expected_oid->hash);
2234                 if (!*contents) {
2235                         error("unable to unpack contents of %s", path);
2236                         git_inflate_end(&stream);
2237                         goto out;
2238                 }
2239                 if (check_object_signature(expected_oid, *contents,
2240                                          *size, type_name(*type))) {
2241                         error("sha1 mismatch for %s (expected %s)", path,
2242                               oid_to_hex(expected_oid));
2243                         free(*contents);
2244                         goto out;
2245                 }
2246         }
2247
2248         ret = 0; /* everything checks out */
2249
2250 out:
2251         if (map)
2252                 munmap(map, mapsize);
2253         return ret;
2254 }