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 "replace-object.h"
  27 #include "streaming.h"
  28 #include "dir.h"
  29 #include "list.h"
  30 #include "mergesort.h"
  31 #include "quote.h"
  32 #include "packfile.h"
  33 #include "fetch-object.h"
  34 #include "object-store.h"
  35
  36 /* The maximum size for an object header. */
  37 #define MAX_HEADER_LEN 32
  38
  39
  40 #define EMPTY_TREE_SHA1_BIN_LITERAL \
  41          "\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
  42          "\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
  43
  44 #define EMPTY_BLOB_SHA1_BIN_LITERAL \
  45         "\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
  46         "\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
  47
  48 const unsigned char null_sha1[GIT_MAX_RAWSZ];
  49 const struct object_id null_oid;
  50 static const struct object_id empty_tree_oid = {
  51         EMPTY_TREE_SHA1_BIN_LITERAL
  52 };
  53 static const struct object_id empty_blob_oid = {
  54         EMPTY_BLOB_SHA1_BIN_LITERAL
  55 };
  56
  57 static void git_hash_sha1_init(git_hash_ctx *ctx)
  58 {
  59         git_SHA1_Init(&ctx->sha1);
  60 }
  61
  62 static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
  63 {
  64         git_SHA1_Update(&ctx->sha1, data, len);
  65 }
  66
  67 static void git_hash_sha1_final(unsigned char *hash, git_hash_ctx *ctx)
  68 {
  69         git_SHA1_Final(hash, &ctx->sha1);
  70 }
  71
  72 static void git_hash_unknown_init(git_hash_ctx *ctx)
  73 {
  74         die("trying to init unknown hash");
  75 }
  76
  77 static void git_hash_unknown_update(git_hash_ctx *ctx, const void *data, size_t len)
  78 {
  79         die("trying to update unknown hash");
  80 }
  81
  82 static void git_hash_unknown_final(unsigned char *hash, git_hash_ctx *ctx)
  83 {
  84         die("trying to finalize unknown hash");
  85 }
  86
  87 const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
  88         {
  89                 NULL,
  90                 0x00000000,
  91                 0,
  92                 0,
  93                 git_hash_unknown_init,
  94                 git_hash_unknown_update,
  95                 git_hash_unknown_final,
  96                 NULL,
  97                 NULL,
  98         },
  99         {
 100                 "sha-1",
 101                 /* "sha1", big-endian */
 102                 0x73686131,
 103                 GIT_SHA1_RAWSZ,
 104                 GIT_SHA1_HEXSZ,
 105                 git_hash_sha1_init,
 106                 git_hash_sha1_update,
 107                 git_hash_sha1_final,
 108                 &empty_tree_oid,
 109                 &empty_blob_oid,
 110         },
 111 };
 112
 113 const char *empty_tree_oid_hex(void)
 114 {
 115         static char buf[GIT_MAX_HEXSZ + 1];
 116         return oid_to_hex_r(buf, the_hash_algo->empty_tree);
 117 }
 118
 119 const char *empty_blob_oid_hex(void)
 120 {
 121         static char buf[GIT_MAX_HEXSZ + 1];
 122         return oid_to_hex_r(buf, the_hash_algo->empty_blob);
 123 }
 124
 125 /*
 126  * This is meant to hold a *small* number of objects that you would
 127  * want read_sha1_file() to be able to return, but yet you do not want
 128  * to write them into the object store (e.g. a browse-only
 129  * application).
 130  */
 131 static struct cached_object {
 132         struct object_id oid;
 133         enum object_type type;
 134         void *buf;
 135         unsigned long size;
 136 } *cached_objects;
 137 static int cached_object_nr, cached_object_alloc;
 138
 139 static struct cached_object empty_tree = {
 140         { EMPTY_TREE_SHA1_BIN_LITERAL },
 141         OBJ_TREE,
 142         "",
 143         0
 144 };
 145
 146 static struct cached_object *find_cached_object(const struct object_id *oid)
 147 {
 148         int i;
 149         struct cached_object *co = cached_objects;
 150
 151         for (i = 0; i < cached_object_nr; i++, co++) {
 152                 if (!oidcmp(&co->oid, oid))
 153                         return co;
 154         }
 155         if (!oidcmp(oid, the_hash_algo->empty_tree))
 156                 return &empty_tree;
 157         return NULL;
 158 }
 159
 160
 161 static int get_conv_flags(unsigned flags)
 162 {
 163         if (flags & HASH_RENORMALIZE)
 164                 return CONV_EOL_RENORMALIZE;
 165         else if (flags & HASH_WRITE_OBJECT)
 166                 return global_conv_flags_eol | CONV_WRITE_OBJECT;
 167         else
 168                 return 0;
 169 }
 170
 171
 172 int mkdir_in_gitdir(const char *path)
 173 {
 174         if (mkdir(path, 0777)) {
 175                 int saved_errno = errno;
 176                 struct stat st;
 177                 struct strbuf sb = STRBUF_INIT;
 178
 179                 if (errno != EEXIST)
 180                         return -1;
 181                 /*
 182                  * Are we looking at a path in a symlinked worktree
 183                  * whose original repository does not yet have it?
 184                  * e.g. .git/rr-cache pointing at its original
 185                  * repository in which the user hasn't performed any
 186                  * conflict resolution yet?
 187                  */
 188                 if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 189                     strbuf_readlink(&sb, path, st.st_size) ||
 190                     !is_absolute_path(sb.buf) ||
 191                     mkdir(sb.buf, 0777)) {
 192                         strbuf_release(&sb);
 193                         errno = saved_errno;
 194                         return -1;
 195                 }
 196                 strbuf_release(&sb);
 197         }
 198         return adjust_shared_perm(path);
 199 }
 200
 201 enum scld_error safe_create_leading_directories(char *path)
 202 {
 203         char *next_component = path + offset_1st_component(path);
 204         enum scld_error ret = SCLD_OK;
 205
 206         while (ret == SCLD_OK && next_component) {
 207                 struct stat st;
 208                 char *slash = next_component, slash_character;
 209
 210                 while (*slash && !is_dir_sep(*slash))
 211                         slash++;
 212
 213                 if (!*slash)
 214                         break;
 215
 216                 next_component = slash + 1;
 217                 while (is_dir_sep(*next_component))
 218                         next_component++;
 219                 if (!*next_component)
 220                         break;
 221
 222                 slash_character = *slash;
 223                 *slash = '\0';
 224                 if (!stat(path, &st)) {
 225                         /* path exists */
 226                         if (!S_ISDIR(st.st_mode)) {
 227                                 errno = ENOTDIR;
 228                                 ret = SCLD_EXISTS;
 229                         }
 230                 } else if (mkdir(path, 0777)) {
 231                         if (errno == EEXIST &&
 232                             !stat(path, &st) && S_ISDIR(st.st_mode))
 233                                 ; /* somebody created it since we checked */
 234                         else if (errno == ENOENT)
 235                                 /*
 236                                  * Either mkdir() failed because
 237                                  * somebody just pruned the containing
 238                                  * directory, or stat() failed because
 239                                  * the file that was in our way was
 240                                  * just removed.  Either way, inform
 241                                  * the caller that it might be worth
 242                                  * trying again:
 243                                  */
 244                                 ret = SCLD_VANISHED;
 245                         else
 246                                 ret = SCLD_FAILED;
 247                 } else if (adjust_shared_perm(path)) {
 248                         ret = SCLD_PERMS;
 249                 }
 250                 *slash = slash_character;
 251         }
 252         return ret;
 253 }
 254
 255 enum scld_error safe_create_leading_directories_const(const char *path)
 256 {
 257         int save_errno;
 258         /* path points to cache entries, so xstrdup before messing with it */
 259         char *buf = xstrdup(path);
 260         enum scld_error result = safe_create_leading_directories(buf);
 261
 262         save_errno = errno;
 263         free(buf);
 264         errno = save_errno;
 265         return result;
 266 }
 267
 268 int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 269 {
 270         /*
 271          * The number of times we will try to remove empty directories
 272          * in the way of path. This is only 1 because if another
 273          * process is racily creating directories that conflict with
 274          * us, we don't want to fight against them.
 275          */
 276         int remove_directories_remaining = 1;
 277
 278         /*
 279          * The number of times that we will try to create the
 280          * directories containing path. We are willing to attempt this
 281          * more than once, because another process could be trying to
 282          * clean up empty directories at the same time as we are
 283          * trying to create them.
 284          */
 285         int create_directories_remaining = 3;
 286
 287         /* A scratch copy of path, filled lazily if we need it: */
 288         struct strbuf path_copy = STRBUF_INIT;
 289
 290         int ret, save_errno;
 291
 292         /* Sanity check: */
 293         assert(*path);
 294
 295 retry_fn:
 296         ret = fn(path, cb);
 297         save_errno = errno;
 298         if (!ret)
 299                 goto out;
 300
 301         if (errno == EISDIR && remove_directories_remaining-- > 0) {
 302                 /*
 303                  * A directory is in the way. Maybe it is empty; try
 304                  * to remove it:
 305                  */
 306                 if (!path_copy.len)
 307                         strbuf_addstr(&path_copy, path);
 308
 309                 if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 310                         goto retry_fn;
 311         } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 312                 /*
 313                  * Maybe the containing directory didn't exist, or
 314                  * maybe it was just deleted by a process that is
 315                  * racing with us to clean up empty directories. Try
 316                  * to create it:
 317                  */
 318                 enum scld_error scld_result;
 319
 320                 if (!path_copy.len)
 321                         strbuf_addstr(&path_copy, path);
 322
 323                 do {
 324                         scld_result = safe_create_leading_directories(path_copy.buf);
 325                         if (scld_result == SCLD_OK)
 326                                 goto retry_fn;
 327                 } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 328         }
 329
 330 out:
 331         strbuf_release(&path_copy);
 332         errno = save_errno;
 333         return ret;
 334 }
 335
 336 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 337 {
 338         int i;
 339         for (i = 0; i < 20; i++) {
 340                 static char hex[] = "0123456789abcdef";
 341                 unsigned int val = sha1[i];
 342                 strbuf_addch(buf, hex[val >> 4]);
 343                 strbuf_addch(buf, hex[val & 0xf]);
 344                 if (!i)
 345                         strbuf_addch(buf, '/');
 346         }
 347 }
 348
 349 void sha1_file_name(struct repository *r, struct strbuf *buf, const unsigned char *sha1)
 350 {
 351         strbuf_addstr(buf, r->objects->objectdir);
 352         strbuf_addch(buf, '/');
 353         fill_sha1_path(buf, sha1);
 354 }
 355
 356 struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 357 {
 358         strbuf_setlen(&alt->scratch, alt->base_len);
 359         return &alt->scratch;
 360 }
 361
 362 static const char *alt_sha1_path(struct alternate_object_database *alt,
 363                                  const unsigned char *sha1)
 364 {
 365         struct strbuf *buf = alt_scratch_buf(alt);
 366         fill_sha1_path(buf, sha1);
 367         return buf->buf;
 368 }
 369
 370 /*
 371  * Return non-zero iff the path is usable as an alternate object database.
 372  */
 373 static int alt_odb_usable(struct raw_object_store *o,
 374                           struct strbuf *path,
 375                           const char *normalized_objdir)
 376 {
 377         struct alternate_object_database *alt;
 378
 379         /* Detect cases where alternate disappeared */
 380         if (!is_directory(path->buf)) {
 381                 error("object directory %s does not exist; "
 382                       "check .git/objects/info/alternates.",
 383                       path->buf);
 384                 return 0;
 385         }
 386
 387         /*
 388          * Prevent the common mistake of listing the same
 389          * thing twice, or object directory itself.
 390          */
 391         for (alt = o->alt_odb_list; alt; alt = alt->next) {
 392                 if (!fspathcmp(path->buf, alt->path))
 393                         return 0;
 394         }
 395         if (!fspathcmp(path->buf, normalized_objdir))
 396                 return 0;
 397
 398         return 1;
 399 }
 400
 401 /*
 402  * Prepare alternate object database registry.
 403  *
 404  * The variable alt_odb_list points at the list of struct
 405  * alternate_object_database.  The elements on this list come from
 406  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 407  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 408  * whose contents is similar to that environment variable but can be
 409  * LF separated.  Its base points at a statically allocated buffer that
 410  * contains "/the/directory/corresponding/to/.git/objects/...", while
 411  * its name points just after the slash at the end of ".git/objects/"
 412  * in the example above, and has enough space to hold 40-byte hex
 413  * SHA1, an extra slash for the first level indirection, and the
 414  * terminating NUL.
 415  */
 416 static void read_info_alternates(struct repository *r,
 417                                  const char *relative_base,
 418                                  int depth);
 419 static int link_alt_odb_entry(struct repository *r, const char *entry,
 420         const char *relative_base, int depth, const char *normalized_objdir)
 421 {
 422         struct alternate_object_database *ent;
 423         struct strbuf pathbuf = STRBUF_INIT;
 424
 425         if (!is_absolute_path(entry) && relative_base) {
 426                 strbuf_realpath(&pathbuf, relative_base, 1);
 427                 strbuf_addch(&pathbuf, '/');
 428         }
 429         strbuf_addstr(&pathbuf, entry);
 430
 431         if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 432                 error("unable to normalize alternate object path: %s",
 433                       pathbuf.buf);
 434                 strbuf_release(&pathbuf);
 435                 return -1;
 436         }
 437
 438         /*
 439          * The trailing slash after the directory name is given by
 440          * this function at the end. Remove duplicates.
 441          */
 442         while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 443                 strbuf_setlen(&pathbuf, pathbuf.len - 1);
 444
 445         if (!alt_odb_usable(r->objects, &pathbuf, normalized_objdir)) {
 446                 strbuf_release(&pathbuf);
 447                 return -1;
 448         }
 449
 450         ent = alloc_alt_odb(pathbuf.buf);
 451
 452         /* add the alternate entry */
 453         *r->objects->alt_odb_tail = ent;
 454         r->objects->alt_odb_tail = &(ent->next);
 455         ent->next = NULL;
 456
 457         /* recursively add alternates */
 458         read_info_alternates(r, pathbuf.buf, depth + 1);
 459
 460         strbuf_release(&pathbuf);
 461         return 0;
 462 }
 463
 464 static const char *parse_alt_odb_entry(const char *string,
 465                                        int sep,
 466                                        struct strbuf *out)
 467 {
 468         const char *end;
 469
 470         strbuf_reset(out);
 471
 472         if (*string == '#') {
 473                 /* comment; consume up to next separator */
 474                 end = strchrnul(string, sep);
 475         } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 476                 /*
 477                  * quoted path; unquote_c_style has copied the
 478                  * data for us and set "end". Broken quoting (e.g.,
 479                  * an entry that doesn't end with a quote) falls
 480                  * back to the unquoted case below.
 481                  */
 482         } else {
 483                 /* normal, unquoted path */
 484                 end = strchrnul(string, sep);
 485                 strbuf_add(out, string, end - string);
 486         }
 487
 488         if (*end)
 489                 end++;
 490         return end;
 491 }
 492
 493 static void link_alt_odb_entries(struct repository *r, const char *alt,
 494                                  int sep, const char *relative_base, int depth)
 495 {
 496         struct strbuf objdirbuf = STRBUF_INIT;
 497         struct strbuf entry = STRBUF_INIT;
 498
 499         if (!alt || !*alt)
 500                 return;
 501
 502         if (depth > 5) {
 503                 error("%s: ignoring alternate object stores, nesting too deep.",
 504                                 relative_base);
 505                 return;
 506         }
 507
 508         strbuf_add_absolute_path(&objdirbuf, r->objects->objectdir);
 509         if (strbuf_normalize_path(&objdirbuf) < 0)
 510                 die("unable to normalize object directory: %s",
 511                     objdirbuf.buf);
 512
 513         while (*alt) {
 514                 alt = parse_alt_odb_entry(alt, sep, &entry);
 515                 if (!entry.len)
 516                         continue;
 517                 link_alt_odb_entry(r, entry.buf,
 518                                    relative_base, depth, objdirbuf.buf);
 519         }
 520         strbuf_release(&entry);
 521         strbuf_release(&objdirbuf);
 522 }
 523
 524 static void read_info_alternates(struct repository *r,
 525                                  const char *relative_base,
 526                                  int depth)
 527 {
 528         char *path;
 529         struct strbuf buf = STRBUF_INIT;
 530
 531         path = xstrfmt("%s/info/alternates", relative_base);
 532         if (strbuf_read_file(&buf, path, 1024) < 0) {
 533                 warn_on_fopen_errors(path);
 534                 free(path);
 535                 return;
 536         }
 537
 538         link_alt_odb_entries(r, buf.buf, '\n', relative_base, depth);
 539         strbuf_release(&buf);
 540         free(path);
 541 }
 542
 543 struct alternate_object_database *alloc_alt_odb(const char *dir)
 544 {
 545         struct alternate_object_database *ent;
 546
 547         FLEX_ALLOC_STR(ent, path, dir);
 548         strbuf_init(&ent->scratch, 0);
 549         strbuf_addf(&ent->scratch, "%s/", dir);
 550         ent->base_len = ent->scratch.len;
 551
 552         return ent;
 553 }
 554
 555 void add_to_alternates_file(const char *reference)
 556 {
 557         struct lock_file lock = LOCK_INIT;
 558         char *alts = git_pathdup("objects/info/alternates");
 559         FILE *in, *out;
 560         int found = 0;
 561
 562         hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 563         out = fdopen_lock_file(&lock, "w");
 564         if (!out)
 565                 die_errno("unable to fdopen alternates lockfile");
 566
 567         in = fopen(alts, "r");
 568         if (in) {
 569                 struct strbuf line = STRBUF_INIT;
 570
 571                 while (strbuf_getline(&line, in) != EOF) {
 572                         if (!strcmp(reference, line.buf)) {
 573                                 found = 1;
 574                                 break;
 575                         }
 576                         fprintf_or_die(out, "%s\n", line.buf);
 577                 }
 578
 579                 strbuf_release(&line);
 580                 fclose(in);
 581         }
 582         else if (errno != ENOENT)
 583                 die_errno("unable to read alternates file");
 584
 585         if (found) {
 586                 rollback_lock_file(&lock);
 587         } else {
 588                 fprintf_or_die(out, "%s\n", reference);
 589                 if (commit_lock_file(&lock))
 590                         die_errno("unable to move new alternates file into place");
 591                 if (the_repository->objects->alt_odb_tail)
 592                         link_alt_odb_entries(the_repository, reference,
 593                                              '\n', NULL, 0);
 594         }
 595         free(alts);
 596 }
 597
 598 void add_to_alternates_memory(const char *reference)
 599 {
 600         /*
 601          * Make sure alternates are initialized, or else our entry may be
 602          * overwritten when they are.
 603          */
 604         prepare_alt_odb(the_repository);
 605
 606         link_alt_odb_entries(the_repository, reference,
 607                              '\n', NULL, 0);
 608 }
 609
 610 /*
 611  * Compute the exact path an alternate is at and returns it. In case of
 612  * error NULL is returned and the human readable error is added to `err`
 613  * `path` may be relative and should point to $GIT_DIR.
 614  * `err` must not be null.
 615  */
 616 char *compute_alternate_path(const char *path, struct strbuf *err)
 617 {
 618         char *ref_git = NULL;
 619         const char *repo, *ref_git_s;
 620         int seen_error = 0;
 621
 622         ref_git_s = real_path_if_valid(path);
 623         if (!ref_git_s) {
 624                 seen_error = 1;
 625                 strbuf_addf(err, _("path '%s' does not exist"), path);
 626                 goto out;
 627         } else
 628                 /*
 629                  * Beware: read_gitfile(), real_path() and mkpath()
 630                  * return static buffer
 631                  */
 632                 ref_git = xstrdup(ref_git_s);
 633
 634         repo = read_gitfile(ref_git);
 635         if (!repo)
 636                 repo = read_gitfile(mkpath("%s/.git", ref_git));
 637         if (repo) {
 638                 free(ref_git);
 639                 ref_git = xstrdup(repo);
 640         }
 641
 642         if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 643                 char *ref_git_git = mkpathdup("%s/.git", ref_git);
 644                 free(ref_git);
 645                 ref_git = ref_git_git;
 646         } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 647                 struct strbuf sb = STRBUF_INIT;
 648                 seen_error = 1;
 649                 if (get_common_dir(&sb, ref_git)) {
 650                         strbuf_addf(err,
 651                                     _("reference repository '%s' as a linked "
 652                                       "checkout is not supported yet."),
 653                                     path);
 654                         goto out;
 655                 }
 656
 657                 strbuf_addf(err, _("reference repository '%s' is not a "
 658                                         "local repository."), path);
 659                 goto out;
 660         }
 661
 662         if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 663                 strbuf_addf(err, _("reference repository '%s' is shallow"),
 664                             path);
 665                 seen_error = 1;
 666                 goto out;
 667         }
 668
 669         if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 670                 strbuf_addf(err,
 671                             _("reference repository '%s' is grafted"),
 672                             path);
 673                 seen_error = 1;
 674                 goto out;
 675         }
 676
 677 out:
 678         if (seen_error) {
 679                 FREE_AND_NULL(ref_git);
 680         }
 681
 682         return ref_git;
 683 }
 684
 685 int foreach_alt_odb(alt_odb_fn fn, void *cb)
 686 {
 687         struct alternate_object_database *ent;
 688         int r = 0;
 689
 690         prepare_alt_odb(the_repository);
 691         for (ent = the_repository->objects->alt_odb_list; ent; ent = ent->next) {
 692                 r = fn(ent, cb);
 693                 if (r)
 694                         break;
 695         }
 696         return r;
 697 }
 698
 699 void prepare_alt_odb(struct repository *r)
 700 {
 701         if (r->objects->alt_odb_tail)
 702                 return;
 703
 704         r->objects->alt_odb_tail = &r->objects->alt_odb_list;
 705         link_alt_odb_entries(r, r->objects->alternate_db, PATH_SEP, NULL, 0);
 706
 707         read_info_alternates(r, r->objects->objectdir, 0);
 708 }
 709
 710 /* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 711 static int freshen_file(const char *fn)
 712 {
 713         struct utimbuf t;
 714         t.actime = t.modtime = time(NULL);
 715         return !utime(fn, &t);
 716 }
 717
 718 /*
 719  * All of the check_and_freshen functions return 1 if the file exists and was
 720  * freshened (if freshening was requested), 0 otherwise. If they return
 721  * 0, you should not assume that it is safe to skip a write of the object (it
 722  * either does not exist on disk, or has a stale mtime and may be subject to
 723  * pruning).
 724  */
 725 int check_and_freshen_file(const char *fn, int freshen)
 726 {
 727         if (access(fn, F_OK))
 728                 return 0;
 729         if (freshen && !freshen_file(fn))
 730                 return 0;
 731         return 1;
 732 }
 733
 734 static int check_and_freshen_local(const struct object_id *oid, int freshen)
 735 {
 736         static struct strbuf buf = STRBUF_INIT;
 737
 738         strbuf_reset(&buf);
 739         sha1_file_name(the_repository, &buf, oid->hash);
 740
 741         return check_and_freshen_file(buf.buf, freshen);
 742 }
 743
 744 static int check_and_freshen_nonlocal(const struct object_id *oid, int freshen)
 745 {
 746         struct alternate_object_database *alt;
 747         prepare_alt_odb(the_repository);
 748         for (alt = the_repository->objects->alt_odb_list; alt; alt = alt->next) {
 749                 const char *path = alt_sha1_path(alt, oid->hash);
 750                 if (check_and_freshen_file(path, freshen))
 751                         return 1;
 752         }
 753         return 0;
 754 }
 755
 756 static int check_and_freshen(const struct object_id *oid, int freshen)
 757 {
 758         return check_and_freshen_local(oid, freshen) ||
 759                check_and_freshen_nonlocal(oid, freshen);
 760 }
 761
 762 int has_loose_object_nonlocal(const struct object_id *oid)
 763 {
 764         return check_and_freshen_nonlocal(oid, 0);
 765 }
 766
 767 static int has_loose_object(const struct object_id *oid)
 768 {
 769         return check_and_freshen(oid, 0);
 770 }
 771
 772 static void mmap_limit_check(size_t length)
 773 {
 774         static size_t limit = 0;
 775         if (!limit) {
 776                 limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 777                 if (!limit)
 778                         limit = SIZE_MAX;
 779         }
 780         if (length > limit)
 781                 die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 782                     (uintmax_t)length, (uintmax_t)limit);
 783 }
 784
 785 void *xmmap_gently(void *start, size_t length,
 786                   int prot, int flags, int fd, off_t offset)
 787 {
 788         void *ret;
 789
 790         mmap_limit_check(length);
 791         ret = mmap(start, length, prot, flags, fd, offset);
 792         if (ret == MAP_FAILED) {
 793                 if (!length)
 794                         return NULL;
 795                 release_pack_memory(length);
 796                 ret = mmap(start, length, prot, flags, fd, offset);
 797         }
 798         return ret;
 799 }
 800
 801 void *xmmap(void *start, size_t length,
 802         int prot, int flags, int fd, off_t offset)
 803 {
 804         void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 805         if (ret == MAP_FAILED)
 806                 die_errno("mmap failed");
 807         return ret;
 808 }
 809
 810 /*
 811  * With an in-core object data in "map", rehash it to make sure the
 812  * object name actually matches "sha1" to detect object corruption.
 813  * With "map" == NULL, try reading the object named with "sha1" using
 814  * the streaming interface and rehash it to do the same.
 815  */
 816 int check_object_signature(const struct object_id *oid, void *map,
 817                            unsigned long size, const char *type)
 818 {
 819         struct object_id real_oid;
 820         enum object_type obj_type;
 821         struct git_istream *st;
 822         git_hash_ctx c;
 823         char hdr[MAX_HEADER_LEN];
 824         int hdrlen;
 825
 826         if (map) {
 827                 hash_object_file(map, size, type, &real_oid);
 828                 return oidcmp(oid, &real_oid) ? -1 : 0;
 829         }
 830
 831         st = open_istream(oid, &obj_type, &size, NULL);
 832         if (!st)
 833                 return -1;
 834
 835         /* Generate the header */
 836         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(obj_type), size) + 1;
 837
 838         /* Sha1.. */
 839         the_hash_algo->init_fn(&c);
 840         the_hash_algo->update_fn(&c, hdr, hdrlen);
 841         for (;;) {
 842                 char buf[1024 * 16];
 843                 ssize_t readlen = read_istream(st, buf, sizeof(buf));
 844
 845                 if (readlen < 0) {
 846                         close_istream(st);
 847                         return -1;
 848                 }
 849                 if (!readlen)
 850                         break;
 851                 the_hash_algo->update_fn(&c, buf, readlen);
 852         }
 853         the_hash_algo->final_fn(real_oid.hash, &c);
 854         close_istream(st);
 855         return oidcmp(oid, &real_oid) ? -1 : 0;
 856 }
 857
 858 int git_open_cloexec(const char *name, int flags)
 859 {
 860         int fd;
 861         static int o_cloexec = O_CLOEXEC;
 862
 863         fd = open(name, flags | o_cloexec);
 864         if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 865                 /* Try again w/o O_CLOEXEC: the kernel might not support it */
 866                 o_cloexec &= ~O_CLOEXEC;
 867                 fd = open(name, flags | o_cloexec);
 868         }
 869
 870 #if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 871         {
 872                 static int fd_cloexec = FD_CLOEXEC;
 873
 874                 if (!o_cloexec && 0 <= fd && fd_cloexec) {
 875                         /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 876                         int flags = fcntl(fd, F_GETFD);
 877                         if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 878                                 fd_cloexec = 0;
 879                 }
 880         }
 881 #endif
 882         return fd;
 883 }
 884
 885 /*
 886  * Find "sha1" as a loose object in the local repository or in an alternate.
 887  * Returns 0 on success, negative on failure.
 888  *
 889  * The "path" out-parameter will give the path of the object we found (if any).
 890  * Note that it may point to static storage and is only valid until another
 891  * call to sha1_file_name(), etc.
 892  */
 893 static int stat_sha1_file(struct repository *r, const unsigned char *sha1,
 894                           struct stat *st, const char **path)
 895 {
 896         struct alternate_object_database *alt;
 897         static struct strbuf buf = STRBUF_INIT;
 898
 899         strbuf_reset(&buf);
 900         sha1_file_name(r, &buf, sha1);
 901         *path = buf.buf;
 902
 903         if (!lstat(*path, st))
 904                 return 0;
 905
 906         prepare_alt_odb(r);
 907         errno = ENOENT;
 908         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 909                 *path = alt_sha1_path(alt, sha1);
 910                 if (!lstat(*path, st))
 911                         return 0;
 912         }
 913
 914         return -1;
 915 }
 916
 917 /*
 918  * Like stat_sha1_file(), but actually open the object and return the
 919  * descriptor. See the caveats on the "path" parameter above.
 920  */
 921 static int open_sha1_file(struct repository *r,
 922                           const unsigned char *sha1, const char **path)
 923 {
 924         int fd;
 925         struct alternate_object_database *alt;
 926         int most_interesting_errno;
 927         static struct strbuf buf = STRBUF_INIT;
 928
 929         strbuf_reset(&buf);
 930         sha1_file_name(r, &buf, sha1);
 931         *path = buf.buf;
 932
 933         fd = git_open(*path);
 934         if (fd >= 0)
 935                 return fd;
 936         most_interesting_errno = errno;
 937
 938         prepare_alt_odb(r);
 939         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 940                 *path = alt_sha1_path(alt, sha1);
 941                 fd = git_open(*path);
 942                 if (fd >= 0)
 943                         return fd;
 944                 if (most_interesting_errno == ENOENT)
 945                         most_interesting_errno = errno;
 946         }
 947         errno = most_interesting_errno;
 948         return -1;
 949 }
 950
 951 /*
 952  * Map the loose object at "path" if it is not NULL, or the path found by
 953  * searching for a loose object named "sha1".
 954  */
 955 static void *map_sha1_file_1(struct repository *r, const char *path,
 956                              const unsigned char *sha1, unsigned long *size)
 957 {
 958         void *map;
 959         int fd;
 960
 961         if (path)
 962                 fd = git_open(path);
 963         else
 964                 fd = open_sha1_file(r, sha1, &path);
 965         map = NULL;
 966         if (fd >= 0) {
 967                 struct stat st;
 968
 969                 if (!fstat(fd, &st)) {
 970                         *size = xsize_t(st.st_size);
 971                         if (!*size) {
 972                                 /* mmap() is forbidden on empty files */
 973                                 error("object file %s is empty", path);
 974                                 return NULL;
 975                         }
 976                         map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 977                 }
 978                 close(fd);
 979         }
 980         return map;
 981 }
 982
 983 void *map_sha1_file(struct repository *r,
 984                     const unsigned char *sha1, unsigned long *size)
 985 {
 986         return map_sha1_file_1(r, NULL, sha1, size);
 987 }
 988
 989 static int unpack_sha1_short_header(git_zstream *stream,
 990                                     unsigned char *map, unsigned long mapsize,
 991                                     void *buffer, unsigned long bufsiz)
 992 {
 993         /* Get the data stream */
 994         memset(stream, 0, sizeof(*stream));
 995         stream->next_in = map;
 996         stream->avail_in = mapsize;
 997         stream->next_out = buffer;
 998         stream->avail_out = bufsiz;
 999
1000         git_inflate_init(stream);
1001         return git_inflate(stream, 0);
1002 }
1003
1004 int unpack_sha1_header(git_zstream *stream,
1005                        unsigned char *map, unsigned long mapsize,
1006                        void *buffer, unsigned long bufsiz)
1007 {
1008         int status = unpack_sha1_short_header(stream, map, mapsize,
1009                                               buffer, bufsiz);
1010
1011         if (status < Z_OK)
1012                 return status;
1013
1014         /* Make sure we have the terminating NUL */
1015         if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1016                 return -1;
1017         return 0;
1018 }
1019
1020 static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
1021                                         unsigned long mapsize, void *buffer,
1022                                         unsigned long bufsiz, struct strbuf *header)
1023 {
1024         int status;
1025
1026         status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
1027         if (status < Z_OK)
1028                 return -1;
1029
1030         /*
1031          * Check if entire header is unpacked in the first iteration.
1032          */
1033         if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1034                 return 0;
1035
1036         /*
1037          * buffer[0..bufsiz] was not large enough.  Copy the partial
1038          * result out to header, and then append the result of further
1039          * reading the stream.
1040          */
1041         strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1042         stream->next_out = buffer;
1043         stream->avail_out = bufsiz;
1044
1045         do {
1046                 status = git_inflate(stream, 0);
1047                 strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1048                 if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1049                         return 0;
1050                 stream->next_out = buffer;
1051                 stream->avail_out = bufsiz;
1052         } while (status != Z_STREAM_END);
1053         return -1;
1054 }
1055
1056 static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1057 {
1058         int bytes = strlen(buffer) + 1;
1059         unsigned char *buf = xmallocz(size);
1060         unsigned long n;
1061         int status = Z_OK;
1062
1063         n = stream->total_out - bytes;
1064         if (n > size)
1065                 n = size;
1066         memcpy(buf, (char *) buffer + bytes, n);
1067         bytes = n;
1068         if (bytes <= size) {
1069                 /*
1070                  * The above condition must be (bytes <= size), not
1071                  * (bytes < size).  In other words, even though we
1072                  * expect no more output and set avail_out to zero,
1073                  * the input zlib stream may have bytes that express
1074                  * "this concludes the stream", and we *do* want to
1075                  * eat that input.
1076                  *
1077                  * Otherwise we would not be able to test that we
1078                  * consumed all the input to reach the expected size;
1079                  * we also want to check that zlib tells us that all
1080                  * went well with status == Z_STREAM_END at the end.
1081                  */
1082                 stream->next_out = buf + bytes;
1083                 stream->avail_out = size - bytes;
1084                 while (status == Z_OK)
1085                         status = git_inflate(stream, Z_FINISH);
1086         }
1087         if (status == Z_STREAM_END && !stream->avail_in) {
1088                 git_inflate_end(stream);
1089                 return buf;
1090         }
1091
1092         if (status < 0)
1093                 error("corrupt loose object '%s'", sha1_to_hex(sha1));
1094         else if (stream->avail_in)
1095                 error("garbage at end of loose object '%s'",
1096                       sha1_to_hex(sha1));
1097         free(buf);
1098         return NULL;
1099 }
1100
1101 /*
1102  * We used to just use "sscanf()", but that's actually way
1103  * too permissive for what we want to check. So do an anal
1104  * object header parse by hand.
1105  */
1106 static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1107                                unsigned int flags)
1108 {
1109         const char *type_buf = hdr;
1110         unsigned long size;
1111         int type, type_len = 0;
1112
1113         /*
1114          * The type can be of any size but is followed by
1115          * a space.
1116          */
1117         for (;;) {
1118                 char c = *hdr++;
1119                 if (!c)
1120                         return -1;
1121                 if (c == ' ')
1122                         break;
1123                 type_len++;
1124         }
1125
1126         type = type_from_string_gently(type_buf, type_len, 1);
1127         if (oi->type_name)
1128                 strbuf_add(oi->type_name, type_buf, type_len);
1129         /*
1130          * Set type to 0 if its an unknown object and
1131          * we're obtaining the type using '--allow-unknown-type'
1132          * option.
1133          */
1134         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
1135                 type = 0;
1136         else if (type < 0)
1137                 die("invalid object type");
1138         if (oi->typep)
1139                 *oi->typep = type;
1140
1141         /*
1142          * The length must follow immediately, and be in canonical
1143          * decimal format (ie "010" is not valid).
1144          */
1145         size = *hdr++ - '0';
1146         if (size > 9)
1147                 return -1;
1148         if (size) {
1149                 for (;;) {
1150                         unsigned long c = *hdr - '0';
1151                         if (c > 9)
1152                                 break;
1153                         hdr++;
1154                         size = size * 10 + c;
1155                 }
1156         }
1157
1158         if (oi->sizep)
1159                 *oi->sizep = size;
1160
1161         /*
1162          * The length must be followed by a zero byte
1163          */
1164         return *hdr ? -1 : type;
1165 }
1166
1167 int parse_sha1_header(const char *hdr, unsigned long *sizep)
1168 {
1169         struct object_info oi = OBJECT_INFO_INIT;
1170
1171         oi.sizep = sizep;
1172         return parse_sha1_header_extended(hdr, &oi, 0);
1173 }
1174
1175 static int sha1_loose_object_info(struct repository *r,
1176                                   const unsigned char *sha1,
1177                                   struct object_info *oi, int flags)
1178 {
1179         int status = 0;
1180         unsigned long mapsize;
1181         void *map;
1182         git_zstream stream;
1183         char hdr[MAX_HEADER_LEN];
1184         struct strbuf hdrbuf = STRBUF_INIT;
1185         unsigned long size_scratch;
1186
1187         if (oi->delta_base_sha1)
1188                 hashclr(oi->delta_base_sha1);
1189
1190         /*
1191          * If we don't care about type or size, then we don't
1192          * need to look inside the object at all. Note that we
1193          * do not optimize out the stat call, even if the
1194          * caller doesn't care about the disk-size, since our
1195          * return value implicitly indicates whether the
1196          * object even exists.
1197          */
1198         if (!oi->typep && !oi->type_name && !oi->sizep && !oi->contentp) {
1199                 const char *path;
1200                 struct stat st;
1201                 if (stat_sha1_file(r, sha1, &st, &path) < 0)
1202                         return -1;
1203                 if (oi->disk_sizep)
1204                         *oi->disk_sizep = st.st_size;
1205                 return 0;
1206         }
1207
1208         map = map_sha1_file(r, sha1, &mapsize);
1209         if (!map)
1210                 return -1;
1211
1212         if (!oi->sizep)
1213                 oi->sizep = &size_scratch;
1214
1215         if (oi->disk_sizep)
1216                 *oi->disk_sizep = mapsize;
1217         if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
1218                 if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
1219                         status = error("unable to unpack %s header with --allow-unknown-type",
1220                                        sha1_to_hex(sha1));
1221         } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1222                 status = error("unable to unpack %s header",
1223                                sha1_to_hex(sha1));
1224         if (status < 0)
1225                 ; /* Do nothing */
1226         else if (hdrbuf.len) {
1227                 if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
1228                         status = error("unable to parse %s header with --allow-unknown-type",
1229                                        sha1_to_hex(sha1));
1230         } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
1231                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1232
1233         if (status >= 0 && oi->contentp) {
1234                 *oi->contentp = unpack_sha1_rest(&stream, hdr,
1235                                                  *oi->sizep, sha1);
1236                 if (!*oi->contentp) {
1237                         git_inflate_end(&stream);
1238                         status = -1;
1239                 }
1240         } else
1241                 git_inflate_end(&stream);
1242
1243         munmap(map, mapsize);
1244         if (status && oi->typep)
1245                 *oi->typep = status;
1246         if (oi->sizep == &size_scratch)
1247                 oi->sizep = NULL;
1248         strbuf_release(&hdrbuf);
1249         oi->whence = OI_LOOSE;
1250         return (status < 0) ? status : 0;
1251 }
1252
1253 int fetch_if_missing = 1;
1254
1255 int oid_object_info_extended(struct repository *r, const struct object_id *oid,
1256                              struct object_info *oi, unsigned flags)
1257 {
1258         static struct object_info blank_oi = OBJECT_INFO_INIT;
1259         struct pack_entry e;
1260         int rtype;
1261         const struct object_id *real = oid;
1262         int already_retried = 0;
1263
1264         if (flags & OBJECT_INFO_LOOKUP_REPLACE)
1265                 real = lookup_replace_object(r, oid);
1266
1267         if (is_null_oid(real))
1268                 return -1;
1269
1270         if (!oi)
1271                 oi = &blank_oi;
1272
1273         if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
1274                 struct cached_object *co = find_cached_object(real);
1275                 if (co) {
1276                         if (oi->typep)
1277                                 *(oi->typep) = co->type;
1278                         if (oi->sizep)
1279                                 *(oi->sizep) = co->size;
1280                         if (oi->disk_sizep)
1281                                 *(oi->disk_sizep) = 0;
1282                         if (oi->delta_base_sha1)
1283                                 hashclr(oi->delta_base_sha1);
1284                         if (oi->type_name)
1285                                 strbuf_addstr(oi->type_name, type_name(co->type));
1286                         if (oi->contentp)
1287                                 *oi->contentp = xmemdupz(co->buf, co->size);
1288                         oi->whence = OI_CACHED;
1289                         return 0;
1290                 }
1291         }
1292
1293         while (1) {
1294                 if (find_pack_entry(r, real, &e))
1295                         break;
1296
1297                 if (flags & OBJECT_INFO_IGNORE_LOOSE)
1298                         return -1;
1299
1300                 /* Most likely it's a loose object. */
1301                 if (!sha1_loose_object_info(r, real->hash, oi, flags))
1302                         return 0;
1303
1304                 /* Not a loose object; someone else may have just packed it. */
1305                 if (!(flags & OBJECT_INFO_QUICK)) {
1306                         reprepare_packed_git(r);
1307                         if (find_pack_entry(r, real, &e))
1308                                 break;
1309                 }
1310
1311                 /* Check if it is a missing object */
1312                 if (fetch_if_missing && repository_format_partial_clone &&
1313                     !already_retried && r == the_repository) {
1314                         /*
1315                          * TODO Investigate having fetch_object() return
1316                          * TODO error/success and stopping the music here.
1317                          * TODO Pass a repository struct through fetch_object,
1318                          * such that arbitrary repositories work.
1319                          */
1320                         fetch_object(repository_format_partial_clone, real->hash);
1321                         already_retried = 1;
1322                         continue;
1323                 }
1324
1325                 return -1;
1326         }
1327
1328         if (oi == &blank_oi)
1329                 /*
1330                  * We know that the caller doesn't actually need the
1331                  * information below, so return early.
1332                  */
1333                 return 0;
1334         rtype = packed_object_info(r, e.p, e.offset, oi);
1335         if (rtype < 0) {
1336                 mark_bad_packed_object(e.p, real->hash);
1337                 return oid_object_info_extended(r, real, oi, 0);
1338         } else if (oi->whence == OI_PACKED) {
1339                 oi->u.packed.offset = e.offset;
1340                 oi->u.packed.pack = e.p;
1341                 oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
1342                                          rtype == OBJ_OFS_DELTA);
1343         }
1344
1345         return 0;
1346 }
1347
1348 /* returns enum object_type or negative */
1349 int oid_object_info(struct repository *r,
1350                     const struct object_id *oid,
1351                     unsigned long *sizep)
1352 {
1353         enum object_type type;
1354         struct object_info oi = OBJECT_INFO_INIT;
1355
1356         oi.typep = &type;
1357         oi.sizep = sizep;
1358         if (oid_object_info_extended(r, oid, &oi,
1359                                       OBJECT_INFO_LOOKUP_REPLACE) < 0)
1360                 return -1;
1361         return type;
1362 }
1363
1364 static void *read_object(const unsigned char *sha1, enum object_type *type,
1365                          unsigned long *size)
1366 {
1367         struct object_id oid;
1368         struct object_info oi = OBJECT_INFO_INIT;
1369         void *content;
1370         oi.typep = type;
1371         oi.sizep = size;
1372         oi.contentp = &content;
1373
1374         hashcpy(oid.hash, sha1);
1375
1376         if (oid_object_info_extended(the_repository, &oid, &oi, 0) < 0)
1377                 return NULL;
1378         return content;
1379 }
1380
1381 int pretend_object_file(void *buf, unsigned long len, enum object_type type,
1382                         struct object_id *oid)
1383 {
1384         struct cached_object *co;
1385
1386         hash_object_file(buf, len, type_name(type), oid);
1387         if (has_sha1_file(oid->hash) || find_cached_object(oid))
1388                 return 0;
1389         ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
1390         co = &cached_objects[cached_object_nr++];
1391         co->size = len;
1392         co->type = type;
1393         co->buf = xmalloc(len);
1394         memcpy(co->buf, buf, len);
1395         oidcpy(&co->oid, oid);
1396         return 0;
1397 }
1398
1399 /*
1400  * This function dies on corrupt objects; the callers who want to
1401  * deal with them should arrange to call read_object() and give error
1402  * messages themselves.
1403  */
1404 void *read_object_file_extended(const struct object_id *oid,
1405                                 enum object_type *type,
1406                                 unsigned long *size,
1407                                 int lookup_replace)
1408 {
1409         void *data;
1410         const struct packed_git *p;
1411         const char *path;
1412         struct stat st;
1413         const struct object_id *repl = lookup_replace ?
1414                 lookup_replace_object(the_repository, oid) : oid;
1415
1416         errno = 0;
1417         data = read_object(repl->hash, type, size);
1418         if (data)
1419                 return data;
1420
1421         if (errno && errno != ENOENT)
1422                 die_errno("failed to read object %s", oid_to_hex(oid));
1423
1424         /* die if we replaced an object with one that does not exist */
1425         if (repl != oid)
1426                 die("replacement %s not found for %s",
1427                     oid_to_hex(repl), oid_to_hex(oid));
1428
1429         if (!stat_sha1_file(the_repository, repl->hash, &st, &path))
1430                 die("loose object %s (stored in %s) is corrupt",
1431                     oid_to_hex(repl), path);
1432
1433         if ((p = has_packed_and_bad(repl->hash)) != NULL)
1434                 die("packed object %s (stored in %s) is corrupt",
1435                     oid_to_hex(repl), p->pack_name);
1436
1437         return NULL;
1438 }
1439
1440 void *read_object_with_reference(const struct object_id *oid,
1441                                  const char *required_type_name,
1442                                  unsigned long *size,
1443                                  struct object_id *actual_oid_return)
1444 {
1445         enum object_type type, required_type;
1446         void *buffer;
1447         unsigned long isize;
1448         struct object_id actual_oid;
1449
1450         required_type = type_from_string(required_type_name);
1451         oidcpy(&actual_oid, oid);
1452         while (1) {
1453                 int ref_length = -1;
1454                 const char *ref_type = NULL;
1455
1456                 buffer = read_object_file(&actual_oid, &type, &isize);
1457                 if (!buffer)
1458                         return NULL;
1459                 if (type == required_type) {
1460                         *size = isize;
1461                         if (actual_oid_return)
1462                                 oidcpy(actual_oid_return, &actual_oid);
1463                         return buffer;
1464                 }
1465                 /* Handle references */
1466                 else if (type == OBJ_COMMIT)
1467                         ref_type = "tree ";
1468                 else if (type == OBJ_TAG)
1469                         ref_type = "object ";
1470                 else {
1471                         free(buffer);
1472                         return NULL;
1473                 }
1474                 ref_length = strlen(ref_type);
1475
1476                 if (ref_length + GIT_SHA1_HEXSZ > isize ||
1477                     memcmp(buffer, ref_type, ref_length) ||
1478                     get_oid_hex((char *) buffer + ref_length, &actual_oid)) {
1479                         free(buffer);
1480                         return NULL;
1481                 }
1482                 free(buffer);
1483                 /* Now we have the ID of the referred-to object in
1484                  * actual_oid.  Check again. */
1485         }
1486 }
1487
1488 static void write_object_file_prepare(const void *buf, unsigned long len,
1489                                       const char *type, struct object_id *oid,
1490                                       char *hdr, int *hdrlen)
1491 {
1492         git_hash_ctx c;
1493
1494         /* Generate the header */
1495         *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
1496
1497         /* Sha1.. */
1498         the_hash_algo->init_fn(&c);
1499         the_hash_algo->update_fn(&c, hdr, *hdrlen);
1500         the_hash_algo->update_fn(&c, buf, len);
1501         the_hash_algo->final_fn(oid->hash, &c);
1502 }
1503
1504 /*
1505  * Move the just written object into its final resting place.
1506  */
1507 int finalize_object_file(const char *tmpfile, const char *filename)
1508 {
1509         int ret = 0;
1510
1511         if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
1512                 goto try_rename;
1513         else if (link(tmpfile, filename))
1514                 ret = errno;
1515
1516         /*
1517          * Coda hack - coda doesn't like cross-directory links,
1518          * so we fall back to a rename, which will mean that it
1519          * won't be able to check collisions, but that's not a
1520          * big deal.
1521          *
1522          * The same holds for FAT formatted media.
1523          *
1524          * When this succeeds, we just return.  We have nothing
1525          * left to unlink.
1526          */
1527         if (ret && ret != EEXIST) {
1528         try_rename:
1529                 if (!rename(tmpfile, filename))
1530                         goto out;
1531                 ret = errno;
1532         }
1533         unlink_or_warn(tmpfile);
1534         if (ret) {
1535                 if (ret != EEXIST) {
1536                         return error_errno("unable to write sha1 filename %s", filename);
1537                 }
1538                 /* FIXME!!! Collision check here ? */
1539         }
1540
1541 out:
1542         if (adjust_shared_perm(filename))
1543                 return error("unable to set permission to '%s'", filename);
1544         return 0;
1545 }
1546
1547 static int write_buffer(int fd, const void *buf, size_t len)
1548 {
1549         if (write_in_full(fd, buf, len) < 0)
1550                 return error_errno("file write error");
1551         return 0;
1552 }
1553
1554 int hash_object_file(const void *buf, unsigned long len, const char *type,
1555                      struct object_id *oid)
1556 {
1557         char hdr[MAX_HEADER_LEN];
1558         int hdrlen = sizeof(hdr);
1559         write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
1560         return 0;
1561 }
1562
1563 /* Finalize a file on disk, and close it. */
1564 static void close_sha1_file(int fd)
1565 {
1566         if (fsync_object_files)
1567                 fsync_or_die(fd, "sha1 file");
1568         if (close(fd) != 0)
1569                 die_errno("error when closing sha1 file");
1570 }
1571
1572 /* Size of directory component, including the ending '/' */
1573 static inline int directory_size(const char *filename)
1574 {
1575         const char *s = strrchr(filename, '/');
1576         if (!s)
1577                 return 0;
1578         return s - filename + 1;
1579 }
1580
1581 /*
1582  * This creates a temporary file in the same directory as the final
1583  * 'filename'
1584  *
1585  * We want to avoid cross-directory filename renames, because those
1586  * can have problems on various filesystems (FAT, NFS, Coda).
1587  */
1588 static int create_tmpfile(struct strbuf *tmp, const char *filename)
1589 {
1590         int fd, dirlen = directory_size(filename);
1591
1592         strbuf_reset(tmp);
1593         strbuf_add(tmp, filename, dirlen);
1594         strbuf_addstr(tmp, "tmp_obj_XXXXXX");
1595         fd = git_mkstemp_mode(tmp->buf, 0444);
1596         if (fd < 0 && dirlen && errno == ENOENT) {
1597                 /*
1598                  * Make sure the directory exists; note that the contents
1599                  * of the buffer are undefined after mkstemp returns an
1600                  * error, so we have to rewrite the whole buffer from
1601                  * scratch.
1602                  */
1603                 strbuf_reset(tmp);
1604                 strbuf_add(tmp, filename, dirlen - 1);
1605                 if (mkdir(tmp->buf, 0777) && errno != EEXIST)
1606                         return -1;
1607                 if (adjust_shared_perm(tmp->buf))
1608                         return -1;
1609
1610                 /* Try again */
1611                 strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
1612                 fd = git_mkstemp_mode(tmp->buf, 0444);
1613         }
1614         return fd;
1615 }
1616
1617 static int write_loose_object(const struct object_id *oid, char *hdr,
1618                               int hdrlen, const void *buf, unsigned long len,
1619                               time_t mtime)
1620 {
1621         int fd, ret;
1622         unsigned char compressed[4096];
1623         git_zstream stream;
1624         git_hash_ctx c;
1625         struct object_id parano_oid;
1626         static struct strbuf tmp_file = STRBUF_INIT;
1627         static struct strbuf filename = STRBUF_INIT;
1628
1629         strbuf_reset(&filename);
1630         sha1_file_name(the_repository, &filename, oid->hash);
1631
1632         fd = create_tmpfile(&tmp_file, filename.buf);
1633         if (fd < 0) {
1634                 if (errno == EACCES)
1635                         return error("insufficient permission for adding an object to repository database %s", get_object_directory());
1636                 else
1637                         return error_errno("unable to create temporary file");
1638         }
1639
1640         /* Set it up */
1641         git_deflate_init(&stream, zlib_compression_level);
1642         stream.next_out = compressed;
1643         stream.avail_out = sizeof(compressed);
1644         the_hash_algo->init_fn(&c);
1645
1646         /* First header.. */
1647         stream.next_in = (unsigned char *)hdr;
1648         stream.avail_in = hdrlen;
1649         while (git_deflate(&stream, 0) == Z_OK)
1650                 ; /* nothing */
1651         the_hash_algo->update_fn(&c, hdr, hdrlen);
1652
1653         /* Then the data itself.. */
1654         stream.next_in = (void *)buf;
1655         stream.avail_in = len;
1656         do {
1657                 unsigned char *in0 = stream.next_in;
1658                 ret = git_deflate(&stream, Z_FINISH);
1659                 the_hash_algo->update_fn(&c, in0, stream.next_in - in0);
1660                 if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
1661                         die("unable to write sha1 file");
1662                 stream.next_out = compressed;
1663                 stream.avail_out = sizeof(compressed);
1664         } while (ret == Z_OK);
1665
1666         if (ret != Z_STREAM_END)
1667                 die("unable to deflate new object %s (%d)", oid_to_hex(oid),
1668                     ret);
1669         ret = git_deflate_end_gently(&stream);
1670         if (ret != Z_OK)
1671                 die("deflateEnd on object %s failed (%d)", oid_to_hex(oid),
1672                     ret);
1673         the_hash_algo->final_fn(parano_oid.hash, &c);
1674         if (oidcmp(oid, &parano_oid) != 0)
1675                 die("confused by unstable object source data for %s",
1676                     oid_to_hex(oid));
1677
1678         close_sha1_file(fd);
1679
1680         if (mtime) {
1681                 struct utimbuf utb;
1682                 utb.actime = mtime;
1683                 utb.modtime = mtime;
1684                 if (utime(tmp_file.buf, &utb) < 0)
1685                         warning_errno("failed utime() on %s", tmp_file.buf);
1686         }
1687
1688         return finalize_object_file(tmp_file.buf, filename.buf);
1689 }
1690
1691 static int freshen_loose_object(const struct object_id *oid)
1692 {
1693         return check_and_freshen(oid, 1);
1694 }
1695
1696 static int freshen_packed_object(const struct object_id *oid)
1697 {
1698         struct pack_entry e;
1699         if (!find_pack_entry(the_repository, oid, &e))
1700                 return 0;
1701         if (e.p->freshened)
1702                 return 1;
1703         if (!freshen_file(e.p->pack_name))
1704                 return 0;
1705         e.p->freshened = 1;
1706         return 1;
1707 }
1708
1709 int write_object_file(const void *buf, unsigned long len, const char *type,
1710                       struct object_id *oid)
1711 {
1712         char hdr[MAX_HEADER_LEN];
1713         int hdrlen = sizeof(hdr);
1714
1715         /* Normally if we have it in the pack then we do not bother writing
1716          * it out into .git/objects/??/?{38} file.
1717          */
1718         write_object_file_prepare(buf, len, type, oid, hdr, &hdrlen);
1719         if (freshen_packed_object(oid) || freshen_loose_object(oid))
1720                 return 0;
1721         return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
1722 }
1723
1724 int hash_object_file_literally(const void *buf, unsigned long len,
1725                                const char *type, struct object_id *oid,
1726                                unsigned flags)
1727 {
1728         char *header;
1729         int hdrlen, status = 0;
1730
1731         /* type string, SP, %lu of the length plus NUL must fit this */
1732         hdrlen = strlen(type) + MAX_HEADER_LEN;
1733         header = xmalloc(hdrlen);
1734         write_object_file_prepare(buf, len, type, oid, header, &hdrlen);
1735
1736         if (!(flags & HASH_WRITE_OBJECT))
1737                 goto cleanup;
1738         if (freshen_packed_object(oid) || freshen_loose_object(oid))
1739                 goto cleanup;
1740         status = write_loose_object(oid, header, hdrlen, buf, len, 0);
1741
1742 cleanup:
1743         free(header);
1744         return status;
1745 }
1746
1747 int force_object_loose(const struct object_id *oid, time_t mtime)
1748 {
1749         void *buf;
1750         unsigned long len;
1751         enum object_type type;
1752         char hdr[MAX_HEADER_LEN];
1753         int hdrlen;
1754         int ret;
1755
1756         if (has_loose_object(oid))
1757                 return 0;
1758         buf = read_object(oid->hash, &type, &len);
1759         if (!buf)
1760                 return error("cannot read sha1_file for %s", oid_to_hex(oid));
1761         hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", type_name(type), len) + 1;
1762         ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
1763         free(buf);
1764
1765         return ret;
1766 }
1767
1768 int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
1769 {
1770         struct object_id oid;
1771         if (!startup_info->have_repository)
1772                 return 0;
1773         hashcpy(oid.hash, sha1);
1774         return oid_object_info_extended(the_repository, &oid, NULL,
1775                                         flags | OBJECT_INFO_SKIP_CACHED) >= 0;
1776 }
1777
1778 int has_object_file(const struct object_id *oid)
1779 {
1780         return has_sha1_file(oid->hash);
1781 }
1782
1783 int has_object_file_with_flags(const struct object_id *oid, int flags)
1784 {
1785         return has_sha1_file_with_flags(oid->hash, flags);
1786 }
1787
1788 static void check_tree(const void *buf, size_t size)
1789 {
1790         struct tree_desc desc;
1791         struct name_entry entry;
1792
1793         init_tree_desc(&desc, buf, size);
1794         while (tree_entry(&desc, &entry))
1795                 /* do nothing
1796                  * tree_entry() will die() on malformed entries */
1797                 ;
1798 }
1799
1800 static void check_commit(const void *buf, size_t size)
1801 {
1802         struct commit c;
1803         memset(&c, 0, sizeof(c));
1804         if (parse_commit_buffer(&c, buf, size))
1805                 die("corrupt commit");
1806 }
1807
1808 static void check_tag(const void *buf, size_t size)
1809 {
1810         struct tag t;
1811         memset(&t, 0, sizeof(t));
1812         if (parse_tag_buffer(&t, buf, size))
1813                 die("corrupt tag");
1814 }
1815
1816 static int index_mem(struct object_id *oid, void *buf, size_t size,
1817                      enum object_type type,
1818                      const char *path, unsigned flags)
1819 {
1820         int ret, re_allocated = 0;
1821         int write_object = flags & HASH_WRITE_OBJECT;
1822
1823         if (!type)
1824                 type = OBJ_BLOB;
1825
1826         /*
1827          * Convert blobs to git internal format
1828          */
1829         if ((type == OBJ_BLOB) && path) {
1830                 struct strbuf nbuf = STRBUF_INIT;
1831                 if (convert_to_git(&the_index, path, buf, size, &nbuf,
1832                                    get_conv_flags(flags))) {
1833                         buf = strbuf_detach(&nbuf, &size);
1834                         re_allocated = 1;
1835                 }
1836         }
1837         if (flags & HASH_FORMAT_CHECK) {
1838                 if (type == OBJ_TREE)
1839                         check_tree(buf, size);
1840                 if (type == OBJ_COMMIT)
1841                         check_commit(buf, size);
1842                 if (type == OBJ_TAG)
1843                         check_tag(buf, size);
1844         }
1845
1846         if (write_object)
1847                 ret = write_object_file(buf, size, type_name(type), oid);
1848         else
1849                 ret = hash_object_file(buf, size, type_name(type), oid);
1850         if (re_allocated)
1851                 free(buf);
1852         return ret;
1853 }
1854
1855 static int index_stream_convert_blob(struct object_id *oid, int fd,
1856                                      const char *path, unsigned flags)
1857 {
1858         int ret;
1859         const int write_object = flags & HASH_WRITE_OBJECT;
1860         struct strbuf sbuf = STRBUF_INIT;
1861
1862         assert(path);
1863         assert(would_convert_to_git_filter_fd(path));
1864
1865         convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
1866                                  get_conv_flags(flags));
1867
1868         if (write_object)
1869                 ret = write_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1870                                         oid);
1871         else
1872                 ret = hash_object_file(sbuf.buf, sbuf.len, type_name(OBJ_BLOB),
1873                                        oid);
1874         strbuf_release(&sbuf);
1875         return ret;
1876 }
1877
1878 static int index_pipe(struct object_id *oid, int fd, enum object_type type,
1879                       const char *path, unsigned flags)
1880 {
1881         struct strbuf sbuf = STRBUF_INIT;
1882         int ret;
1883
1884         if (strbuf_read(&sbuf, fd, 4096) >= 0)
1885                 ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
1886         else
1887                 ret = -1;
1888         strbuf_release(&sbuf);
1889         return ret;
1890 }
1891
1892 #define SMALL_FILE_SIZE (32*1024)
1893
1894 static int index_core(struct object_id *oid, int fd, size_t size,
1895                       enum object_type type, const char *path,
1896                       unsigned flags)
1897 {
1898         int ret;
1899
1900         if (!size) {
1901                 ret = index_mem(oid, "", size, type, path, flags);
1902         } else if (size <= SMALL_FILE_SIZE) {
1903                 char *buf = xmalloc(size);
1904                 ssize_t read_result = read_in_full(fd, buf, size);
1905                 if (read_result < 0)
1906                         ret = error_errno("read error while indexing %s",
1907                                           path ? path : "<unknown>");
1908                 else if (read_result != size)
1909                         ret = error("short read while indexing %s",
1910                                     path ? path : "<unknown>");
1911                 else
1912                         ret = index_mem(oid, buf, size, type, path, flags);
1913                 free(buf);
1914         } else {
1915                 void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1916                 ret = index_mem(oid, buf, size, type, path, flags);
1917                 munmap(buf, size);
1918         }
1919         return ret;
1920 }
1921
1922 /*
1923  * This creates one packfile per large blob unless bulk-checkin
1924  * machinery is "plugged".
1925  *
1926  * This also bypasses the usual "convert-to-git" dance, and that is on
1927  * purpose. We could write a streaming version of the converting
1928  * functions and insert that before feeding the data to fast-import
1929  * (or equivalent in-core API described above). However, that is
1930  * somewhat complicated, as we do not know the size of the filter
1931  * result, which we need to know beforehand when writing a git object.
1932  * Since the primary motivation for trying to stream from the working
1933  * tree file and to avoid mmaping it in core is to deal with large
1934  * binary blobs, they generally do not want to get any conversion, and
1935  * callers should avoid this code path when filters are requested.
1936  */
1937 static int index_stream(struct object_id *oid, int fd, size_t size,
1938                         enum object_type type, const char *path,
1939                         unsigned flags)
1940 {
1941         return index_bulk_checkin(oid, fd, size, type, path, flags);
1942 }
1943
1944 int index_fd(struct object_id *oid, int fd, struct stat *st,
1945              enum object_type type, const char *path, unsigned flags)
1946 {
1947         int ret;
1948
1949         /*
1950          * Call xsize_t() only when needed to avoid potentially unnecessary
1951          * die() for large files.
1952          */
1953         if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
1954                 ret = index_stream_convert_blob(oid, fd, path, flags);
1955         else if (!S_ISREG(st->st_mode))
1956                 ret = index_pipe(oid, fd, type, path, flags);
1957         else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
1958                  (path && would_convert_to_git(&the_index, path)))
1959                 ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
1960                                  flags);
1961         else
1962                 ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
1963                                    flags);
1964         close(fd);
1965         return ret;
1966 }
1967
1968 int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
1969 {
1970         int fd;
1971         struct strbuf sb = STRBUF_INIT;
1972         int rc = 0;
1973
1974         switch (st->st_mode & S_IFMT) {
1975         case S_IFREG:
1976                 fd = open(path, O_RDONLY);
1977                 if (fd < 0)
1978                         return error_errno("open(\"%s\")", path);
1979                 if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
1980                         return error("%s: failed to insert into database",
1981                                      path);
1982                 break;
1983         case S_IFLNK:
1984                 if (strbuf_readlink(&sb, path, st->st_size))
1985                         return error_errno("readlink(\"%s\")", path);
1986                 if (!(flags & HASH_WRITE_OBJECT))
1987                         hash_object_file(sb.buf, sb.len, blob_type, oid);
1988                 else if (write_object_file(sb.buf, sb.len, blob_type, oid))
1989                         rc = error("%s: failed to insert into database", path);
1990                 strbuf_release(&sb);
1991                 break;
1992         case S_IFDIR:
1993                 return resolve_gitlink_ref(path, "HEAD", oid);
1994         default:
1995                 return error("%s: unsupported file type", path);
1996         }
1997         return rc;
1998 }
1999
2000 int read_pack_header(int fd, struct pack_header *header)
2001 {
2002         if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
2003                 /* "eof before pack header was fully read" */
2004                 return PH_ERROR_EOF;
2005
2006         if (header->hdr_signature != htonl(PACK_SIGNATURE))
2007                 /* "protocol error (pack signature mismatch detected)" */
2008                 return PH_ERROR_PACK_SIGNATURE;
2009         if (!pack_version_ok(header->hdr_version))
2010                 /* "protocol error (pack version unsupported)" */
2011                 return PH_ERROR_PROTOCOL;
2012         return 0;
2013 }
2014
2015 void assert_oid_type(const struct object_id *oid, enum object_type expect)
2016 {
2017         enum object_type type = oid_object_info(the_repository, oid, NULL);
2018         if (type < 0)
2019                 die("%s is not a valid object", oid_to_hex(oid));
2020         if (type != expect)
2021                 die("%s is not a valid '%s' object", oid_to_hex(oid),
2022                     type_name(expect));
2023 }
2024
2025 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
2026                                 struct strbuf *path,
2027                                 each_loose_object_fn obj_cb,
2028                                 each_loose_cruft_fn cruft_cb,
2029                                 each_loose_subdir_fn subdir_cb,
2030                                 void *data)
2031 {
2032         size_t origlen, baselen;
2033         DIR *dir;
2034         struct dirent *de;
2035         int r = 0;
2036         struct object_id oid;
2037
2038         if (subdir_nr > 0xff)
2039                 BUG("invalid loose object subdirectory: %x", subdir_nr);
2040
2041         origlen = path->len;
2042         strbuf_complete(path, '/');
2043         strbuf_addf(path, "%02x", subdir_nr);
2044
2045         dir = opendir(path->buf);
2046         if (!dir) {
2047                 if (errno != ENOENT)
2048                         r = error_errno("unable to open %s", path->buf);
2049                 strbuf_setlen(path, origlen);
2050                 return r;
2051         }
2052
2053         oid.hash[0] = subdir_nr;
2054         strbuf_addch(path, '/');
2055         baselen = path->len;
2056
2057         while ((de = readdir(dir))) {
2058                 size_t namelen;
2059                 if (is_dot_or_dotdot(de->d_name))
2060                         continue;
2061
2062                 namelen = strlen(de->d_name);
2063                 strbuf_setlen(path, baselen);
2064                 strbuf_add(path, de->d_name, namelen);
2065                 if (namelen == GIT_SHA1_HEXSZ - 2 &&
2066                     !hex_to_bytes(oid.hash + 1, de->d_name,
2067                                   GIT_SHA1_RAWSZ - 1)) {
2068                         if (obj_cb) {
2069                                 r = obj_cb(&oid, path->buf, data);
2070                                 if (r)
2071                                         break;
2072                         }
2073                         continue;
2074                 }
2075
2076                 if (cruft_cb) {
2077                         r = cruft_cb(de->d_name, path->buf, data);
2078                         if (r)
2079                                 break;
2080                 }
2081         }
2082         closedir(dir);
2083
2084         strbuf_setlen(path, baselen - 1);
2085         if (!r && subdir_cb)
2086                 r = subdir_cb(subdir_nr, path->buf, data);
2087
2088         strbuf_setlen(path, origlen);
2089
2090         return r;
2091 }
2092
2093 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
2094                             each_loose_object_fn obj_cb,
2095                             each_loose_cruft_fn cruft_cb,
2096                             each_loose_subdir_fn subdir_cb,
2097                             void *data)
2098 {
2099         int r = 0;
2100         int i;
2101
2102         for (i = 0; i < 256; i++) {
2103                 r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
2104                                                 subdir_cb, data);
2105                 if (r)
2106                         break;
2107         }
2108
2109         return r;
2110 }
2111
2112 int for_each_loose_file_in_objdir(const char *path,
2113                                   each_loose_object_fn obj_cb,
2114                                   each_loose_cruft_fn cruft_cb,
2115                                   each_loose_subdir_fn subdir_cb,
2116                                   void *data)
2117 {
2118         struct strbuf buf = STRBUF_INIT;
2119         int r;
2120
2121         strbuf_addstr(&buf, path);
2122         r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
2123                                               subdir_cb, data);
2124         strbuf_release(&buf);
2125
2126         return r;
2127 }
2128
2129 struct loose_alt_odb_data {
2130         each_loose_object_fn *cb;
2131         void *data;
2132 };
2133
2134 static int loose_from_alt_odb(struct alternate_object_database *alt,
2135                               void *vdata)
2136 {
2137         struct loose_alt_odb_data *data = vdata;
2138         struct strbuf buf = STRBUF_INIT;
2139         int r;
2140
2141         strbuf_addstr(&buf, alt->path);
2142         r = for_each_loose_file_in_objdir_buf(&buf,
2143                                               data->cb, NULL, NULL,
2144                                               data->data);
2145         strbuf_release(&buf);
2146         return r;
2147 }
2148
2149 int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
2150 {
2151         struct loose_alt_odb_data alt;
2152         int r;
2153
2154         r = for_each_loose_file_in_objdir(get_object_directory(),
2155                                           cb, NULL, NULL, data);
2156         if (r)
2157                 return r;
2158
2159         if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
2160                 return 0;
2161
2162         alt.cb = cb;
2163         alt.data = data;
2164         return foreach_alt_odb(loose_from_alt_odb, &alt);
2165 }
2166
2167 static int check_stream_sha1(git_zstream *stream,
2168                              const char *hdr,
2169                              unsigned long size,
2170                              const char *path,
2171                              const unsigned char *expected_sha1)
2172 {
2173         git_hash_ctx c;
2174         unsigned char real_sha1[GIT_MAX_RAWSZ];
2175         unsigned char buf[4096];
2176         unsigned long total_read;
2177         int status = Z_OK;
2178
2179         the_hash_algo->init_fn(&c);
2180         the_hash_algo->update_fn(&c, hdr, stream->total_out);
2181
2182         /*
2183          * We already read some bytes into hdr, but the ones up to the NUL
2184          * do not count against the object's content size.
2185          */
2186         total_read = stream->total_out - strlen(hdr) - 1;
2187
2188         /*
2189          * This size comparison must be "<=" to read the final zlib packets;
2190          * see the comment in unpack_sha1_rest for details.
2191          */
2192         while (total_read <= size &&
2193                (status == Z_OK || status == Z_BUF_ERROR)) {
2194                 stream->next_out = buf;
2195                 stream->avail_out = sizeof(buf);
2196                 if (size - total_read < stream->avail_out)
2197                         stream->avail_out = size - total_read;
2198                 status = git_inflate(stream, Z_FINISH);
2199                 the_hash_algo->update_fn(&c, buf, stream->next_out - buf);
2200                 total_read += stream->next_out - buf;
2201         }
2202         git_inflate_end(stream);
2203
2204         if (status != Z_STREAM_END) {
2205                 error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
2206                 return -1;
2207         }
2208         if (stream->avail_in) {
2209                 error("garbage at end of loose object '%s'",
2210                       sha1_to_hex(expected_sha1));
2211                 return -1;
2212         }
2213
2214         the_hash_algo->final_fn(real_sha1, &c);
2215         if (hashcmp(expected_sha1, real_sha1)) {
2216                 error("sha1 mismatch for %s (expected %s)", path,
2217                       sha1_to_hex(expected_sha1));
2218                 return -1;
2219         }
2220
2221         return 0;
2222 }
2223
2224 int read_loose_object(const char *path,
2225                       const struct object_id *expected_oid,
2226                       enum object_type *type,
2227                       unsigned long *size,
2228                       void **contents)
2229 {
2230         int ret = -1;
2231         void *map = NULL;
2232         unsigned long mapsize;
2233         git_zstream stream;
2234         char hdr[MAX_HEADER_LEN];
2235
2236         *contents = NULL;
2237
2238         map = map_sha1_file_1(the_repository, path, NULL, &mapsize);
2239         if (!map) {
2240                 error_errno("unable to mmap %s", path);
2241                 goto out;
2242         }
2243
2244         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
2245                 error("unable to unpack header of %s", path);
2246                 goto out;
2247         }
2248
2249         *type = parse_sha1_header(hdr, size);
2250         if (*type < 0) {
2251                 error("unable to parse header of %s", path);
2252                 git_inflate_end(&stream);
2253                 goto out;
2254         }
2255
2256         if (*type == OBJ_BLOB && *size > big_file_threshold) {
2257                 if (check_stream_sha1(&stream, hdr, *size, path, expected_oid->hash) < 0)
2258                         goto out;
2259         } else {
2260                 *contents = unpack_sha1_rest(&stream, hdr, *size, expected_oid->hash);
2261                 if (!*contents) {
2262                         error("unable to unpack contents of %s", path);
2263                         git_inflate_end(&stream);
2264                         goto out;
2265                 }
2266                 if (check_object_signature(expected_oid, *contents,
2267                                          *size, type_name(*type))) {
2268                         error("sha1 mismatch for %s (expected %s)", path,
2269                               oid_to_hex(expected_oid));
2270                         free(*contents);
2271                         goto out;
2272                 }
2273         }
2274
2275         ret = 0; /* everything checks out */
2276
2277 out:
2278         if (map)
2279                 munmap(map, mapsize);
2280         return ret;
2281 }