af5aa83db51a460581c86f82ca293de1b84d09e2
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include "cache.h"
  10#include "config.h"
  11#include "string-list.h"
  12#include "lockfile.h"
  13#include "delta.h"
  14#include "pack.h"
  15#include "blob.h"
  16#include "commit.h"
  17#include "run-command.h"
  18#include "tag.h"
  19#include "tree.h"
  20#include "tree-walk.h"
  21#include "refs.h"
  22#include "pack-revindex.h"
  23#include "sha1-lookup.h"
  24#include "bulk-checkin.h"
  25#include "streaming.h"
  26#include "dir.h"
  27#include "list.h"
  28#include "mergesort.h"
  29#include "quote.h"
  30#include "packfile.h"
  31#include "fetch-object.h"
  32#include "object-store.h"
  33
  34const unsigned char null_sha1[GIT_MAX_RAWSZ];
  35const struct object_id null_oid;
  36const struct object_id empty_tree_oid = {
  37        EMPTY_TREE_SHA1_BIN_LITERAL
  38};
  39const struct object_id empty_blob_oid = {
  40        EMPTY_BLOB_SHA1_BIN_LITERAL
  41};
  42
  43static void git_hash_sha1_init(void *ctx)
  44{
  45        git_SHA1_Init((git_SHA_CTX *)ctx);
  46}
  47
  48static void git_hash_sha1_update(void *ctx, const void *data, size_t len)
  49{
  50        git_SHA1_Update((git_SHA_CTX *)ctx, data, len);
  51}
  52
  53static void git_hash_sha1_final(unsigned char *hash, void *ctx)
  54{
  55        git_SHA1_Final(hash, (git_SHA_CTX *)ctx);
  56}
  57
  58static void git_hash_unknown_init(void *ctx)
  59{
  60        die("trying to init unknown hash");
  61}
  62
  63static void git_hash_unknown_update(void *ctx, const void *data, size_t len)
  64{
  65        die("trying to update unknown hash");
  66}
  67
  68static void git_hash_unknown_final(unsigned char *hash, void *ctx)
  69{
  70        die("trying to finalize unknown hash");
  71}
  72
  73const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
  74        {
  75                NULL,
  76                0x00000000,
  77                0,
  78                0,
  79                0,
  80                git_hash_unknown_init,
  81                git_hash_unknown_update,
  82                git_hash_unknown_final,
  83                NULL,
  84                NULL,
  85        },
  86        {
  87                "sha-1",
  88                /* "sha1", big-endian */
  89                0x73686131,
  90                sizeof(git_SHA_CTX),
  91                GIT_SHA1_RAWSZ,
  92                GIT_SHA1_HEXSZ,
  93                git_hash_sha1_init,
  94                git_hash_sha1_update,
  95                git_hash_sha1_final,
  96                &empty_tree_oid,
  97                &empty_blob_oid,
  98        },
  99};
 100
 101/*
 102 * This is meant to hold a *small* number of objects that you would
 103 * want read_sha1_file() to be able to return, but yet you do not want
 104 * to write them into the object store (e.g. a browse-only
 105 * application).
 106 */
 107static struct cached_object {
 108        unsigned char sha1[20];
 109        enum object_type type;
 110        void *buf;
 111        unsigned long size;
 112} *cached_objects;
 113static int cached_object_nr, cached_object_alloc;
 114
 115static struct cached_object empty_tree = {
 116        EMPTY_TREE_SHA1_BIN_LITERAL,
 117        OBJ_TREE,
 118        "",
 119        0
 120};
 121
 122static struct cached_object *find_cached_object(const unsigned char *sha1)
 123{
 124        int i;
 125        struct cached_object *co = cached_objects;
 126
 127        for (i = 0; i < cached_object_nr; i++, co++) {
 128                if (!hashcmp(co->sha1, sha1))
 129                        return co;
 130        }
 131        if (!hashcmp(sha1, empty_tree.sha1))
 132                return &empty_tree;
 133        return NULL;
 134}
 135
 136
 137static int get_conv_flags(unsigned flags)
 138{
 139        if (flags & HASH_RENORMALIZE)
 140                return CONV_EOL_RENORMALIZE;
 141        else if (flags & HASH_WRITE_OBJECT)
 142          return global_conv_flags_eol;
 143        else
 144                return 0;
 145}
 146
 147
 148int mkdir_in_gitdir(const char *path)
 149{
 150        if (mkdir(path, 0777)) {
 151                int saved_errno = errno;
 152                struct stat st;
 153                struct strbuf sb = STRBUF_INIT;
 154
 155                if (errno != EEXIST)
 156                        return -1;
 157                /*
 158                 * Are we looking at a path in a symlinked worktree
 159                 * whose original repository does not yet have it?
 160                 * e.g. .git/rr-cache pointing at its original
 161                 * repository in which the user hasn't performed any
 162                 * conflict resolution yet?
 163                 */
 164                if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 165                    strbuf_readlink(&sb, path, st.st_size) ||
 166                    !is_absolute_path(sb.buf) ||
 167                    mkdir(sb.buf, 0777)) {
 168                        strbuf_release(&sb);
 169                        errno = saved_errno;
 170                        return -1;
 171                }
 172                strbuf_release(&sb);
 173        }
 174        return adjust_shared_perm(path);
 175}
 176
 177enum scld_error safe_create_leading_directories(char *path)
 178{
 179        char *next_component = path + offset_1st_component(path);
 180        enum scld_error ret = SCLD_OK;
 181
 182        while (ret == SCLD_OK && next_component) {
 183                struct stat st;
 184                char *slash = next_component, slash_character;
 185
 186                while (*slash && !is_dir_sep(*slash))
 187                        slash++;
 188
 189                if (!*slash)
 190                        break;
 191
 192                next_component = slash + 1;
 193                while (is_dir_sep(*next_component))
 194                        next_component++;
 195                if (!*next_component)
 196                        break;
 197
 198                slash_character = *slash;
 199                *slash = '\0';
 200                if (!stat(path, &st)) {
 201                        /* path exists */
 202                        if (!S_ISDIR(st.st_mode)) {
 203                                errno = ENOTDIR;
 204                                ret = SCLD_EXISTS;
 205                        }
 206                } else if (mkdir(path, 0777)) {
 207                        if (errno == EEXIST &&
 208                            !stat(path, &st) && S_ISDIR(st.st_mode))
 209                                ; /* somebody created it since we checked */
 210                        else if (errno == ENOENT)
 211                                /*
 212                                 * Either mkdir() failed because
 213                                 * somebody just pruned the containing
 214                                 * directory, or stat() failed because
 215                                 * the file that was in our way was
 216                                 * just removed.  Either way, inform
 217                                 * the caller that it might be worth
 218                                 * trying again:
 219                                 */
 220                                ret = SCLD_VANISHED;
 221                        else
 222                                ret = SCLD_FAILED;
 223                } else if (adjust_shared_perm(path)) {
 224                        ret = SCLD_PERMS;
 225                }
 226                *slash = slash_character;
 227        }
 228        return ret;
 229}
 230
 231enum scld_error safe_create_leading_directories_const(const char *path)
 232{
 233        int save_errno;
 234        /* path points to cache entries, so xstrdup before messing with it */
 235        char *buf = xstrdup(path);
 236        enum scld_error result = safe_create_leading_directories(buf);
 237
 238        save_errno = errno;
 239        free(buf);
 240        errno = save_errno;
 241        return result;
 242}
 243
 244int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
 245{
 246        /*
 247         * The number of times we will try to remove empty directories
 248         * in the way of path. This is only 1 because if another
 249         * process is racily creating directories that conflict with
 250         * us, we don't want to fight against them.
 251         */
 252        int remove_directories_remaining = 1;
 253
 254        /*
 255         * The number of times that we will try to create the
 256         * directories containing path. We are willing to attempt this
 257         * more than once, because another process could be trying to
 258         * clean up empty directories at the same time as we are
 259         * trying to create them.
 260         */
 261        int create_directories_remaining = 3;
 262
 263        /* A scratch copy of path, filled lazily if we need it: */
 264        struct strbuf path_copy = STRBUF_INIT;
 265
 266        int ret, save_errno;
 267
 268        /* Sanity check: */
 269        assert(*path);
 270
 271retry_fn:
 272        ret = fn(path, cb);
 273        save_errno = errno;
 274        if (!ret)
 275                goto out;
 276
 277        if (errno == EISDIR && remove_directories_remaining-- > 0) {
 278                /*
 279                 * A directory is in the way. Maybe it is empty; try
 280                 * to remove it:
 281                 */
 282                if (!path_copy.len)
 283                        strbuf_addstr(&path_copy, path);
 284
 285                if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
 286                        goto retry_fn;
 287        } else if (errno == ENOENT && create_directories_remaining-- > 0) {
 288                /*
 289                 * Maybe the containing directory didn't exist, or
 290                 * maybe it was just deleted by a process that is
 291                 * racing with us to clean up empty directories. Try
 292                 * to create it:
 293                 */
 294                enum scld_error scld_result;
 295
 296                if (!path_copy.len)
 297                        strbuf_addstr(&path_copy, path);
 298
 299                do {
 300                        scld_result = safe_create_leading_directories(path_copy.buf);
 301                        if (scld_result == SCLD_OK)
 302                                goto retry_fn;
 303                } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
 304        }
 305
 306out:
 307        strbuf_release(&path_copy);
 308        errno = save_errno;
 309        return ret;
 310}
 311
 312static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 313{
 314        int i;
 315        for (i = 0; i < 20; i++) {
 316                static char hex[] = "0123456789abcdef";
 317                unsigned int val = sha1[i];
 318                strbuf_addch(buf, hex[val >> 4]);
 319                strbuf_addch(buf, hex[val & 0xf]);
 320                if (!i)
 321                        strbuf_addch(buf, '/');
 322        }
 323}
 324
 325void sha1_file_name(struct strbuf *buf, const unsigned char *sha1)
 326{
 327        strbuf_addstr(buf, get_object_directory());
 328        strbuf_addch(buf, '/');
 329        fill_sha1_path(buf, sha1);
 330}
 331
 332struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 333{
 334        strbuf_setlen(&alt->scratch, alt->base_len);
 335        return &alt->scratch;
 336}
 337
 338static const char *alt_sha1_path(struct alternate_object_database *alt,
 339                                 const unsigned char *sha1)
 340{
 341        struct strbuf *buf = alt_scratch_buf(alt);
 342        fill_sha1_path(buf, sha1);
 343        return buf->buf;
 344}
 345
 346struct alternate_object_database *alt_odb_list;
 347static struct alternate_object_database **alt_odb_tail;
 348
 349/*
 350 * Return non-zero iff the path is usable as an alternate object database.
 351 */
 352static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
 353{
 354        struct alternate_object_database *alt;
 355
 356        /* Detect cases where alternate disappeared */
 357        if (!is_directory(path->buf)) {
 358                error("object directory %s does not exist; "
 359                      "check .git/objects/info/alternates.",
 360                      path->buf);
 361                return 0;
 362        }
 363
 364        /*
 365         * Prevent the common mistake of listing the same
 366         * thing twice, or object directory itself.
 367         */
 368        for (alt = alt_odb_list; alt; alt = alt->next) {
 369                if (!fspathcmp(path->buf, alt->path))
 370                        return 0;
 371        }
 372        if (!fspathcmp(path->buf, normalized_objdir))
 373                return 0;
 374
 375        return 1;
 376}
 377
 378/*
 379 * Prepare alternate object database registry.
 380 *
 381 * The variable alt_odb_list points at the list of struct
 382 * alternate_object_database.  The elements on this list come from
 383 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 384 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 385 * whose contents is similar to that environment variable but can be
 386 * LF separated.  Its base points at a statically allocated buffer that
 387 * contains "/the/directory/corresponding/to/.git/objects/...", while
 388 * its name points just after the slash at the end of ".git/objects/"
 389 * in the example above, and has enough space to hold 40-byte hex
 390 * SHA1, an extra slash for the first level indirection, and the
 391 * terminating NUL.
 392 */
 393static void read_info_alternates(const char * relative_base, int depth);
 394static int link_alt_odb_entry(const char *entry, const char *relative_base,
 395        int depth, const char *normalized_objdir)
 396{
 397        struct alternate_object_database *ent;
 398        struct strbuf pathbuf = STRBUF_INIT;
 399
 400        if (!is_absolute_path(entry) && relative_base) {
 401                strbuf_realpath(&pathbuf, relative_base, 1);
 402                strbuf_addch(&pathbuf, '/');
 403        }
 404        strbuf_addstr(&pathbuf, entry);
 405
 406        if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 407                error("unable to normalize alternate object path: %s",
 408                      pathbuf.buf);
 409                strbuf_release(&pathbuf);
 410                return -1;
 411        }
 412
 413        /*
 414         * The trailing slash after the directory name is given by
 415         * this function at the end. Remove duplicates.
 416         */
 417        while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 418                strbuf_setlen(&pathbuf, pathbuf.len - 1);
 419
 420        if (!alt_odb_usable(&pathbuf, normalized_objdir)) {
 421                strbuf_release(&pathbuf);
 422                return -1;
 423        }
 424
 425        ent = alloc_alt_odb(pathbuf.buf);
 426
 427        /* add the alternate entry */
 428        *alt_odb_tail = ent;
 429        alt_odb_tail = &(ent->next);
 430        ent->next = NULL;
 431
 432        /* recursively add alternates */
 433        read_info_alternates(pathbuf.buf, depth + 1);
 434
 435        strbuf_release(&pathbuf);
 436        return 0;
 437}
 438
 439static const char *parse_alt_odb_entry(const char *string,
 440                                       int sep,
 441                                       struct strbuf *out)
 442{
 443        const char *end;
 444
 445        strbuf_reset(out);
 446
 447        if (*string == '#') {
 448                /* comment; consume up to next separator */
 449                end = strchrnul(string, sep);
 450        } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 451                /*
 452                 * quoted path; unquote_c_style has copied the
 453                 * data for us and set "end". Broken quoting (e.g.,
 454                 * an entry that doesn't end with a quote) falls
 455                 * back to the unquoted case below.
 456                 */
 457        } else {
 458                /* normal, unquoted path */
 459                end = strchrnul(string, sep);
 460                strbuf_add(out, string, end - string);
 461        }
 462
 463        if (*end)
 464                end++;
 465        return end;
 466}
 467
 468static void link_alt_odb_entries(const char *alt, int sep,
 469                                 const char *relative_base, int depth)
 470{
 471        struct strbuf objdirbuf = STRBUF_INIT;
 472        struct strbuf entry = STRBUF_INIT;
 473
 474        if (!alt || !*alt)
 475                return;
 476
 477        if (depth > 5) {
 478                error("%s: ignoring alternate object stores, nesting too deep.",
 479                                relative_base);
 480                return;
 481        }
 482
 483        strbuf_add_absolute_path(&objdirbuf, get_object_directory());
 484        if (strbuf_normalize_path(&objdirbuf) < 0)
 485                die("unable to normalize object directory: %s",
 486                    objdirbuf.buf);
 487
 488        while (*alt) {
 489                alt = parse_alt_odb_entry(alt, sep, &entry);
 490                if (!entry.len)
 491                        continue;
 492                link_alt_odb_entry(entry.buf, relative_base, depth, objdirbuf.buf);
 493        }
 494        strbuf_release(&entry);
 495        strbuf_release(&objdirbuf);
 496}
 497
 498static void read_info_alternates(const char * relative_base, int depth)
 499{
 500        char *path;
 501        struct strbuf buf = STRBUF_INIT;
 502
 503        path = xstrfmt("%s/info/alternates", relative_base);
 504        if (strbuf_read_file(&buf, path, 1024) < 0) {
 505                warn_on_fopen_errors(path);
 506                free(path);
 507                return;
 508        }
 509
 510        link_alt_odb_entries(buf.buf, '\n', relative_base, depth);
 511        strbuf_release(&buf);
 512        free(path);
 513}
 514
 515struct alternate_object_database *alloc_alt_odb(const char *dir)
 516{
 517        struct alternate_object_database *ent;
 518
 519        FLEX_ALLOC_STR(ent, path, dir);
 520        strbuf_init(&ent->scratch, 0);
 521        strbuf_addf(&ent->scratch, "%s/", dir);
 522        ent->base_len = ent->scratch.len;
 523
 524        return ent;
 525}
 526
 527void add_to_alternates_file(const char *reference)
 528{
 529        struct lock_file lock = LOCK_INIT;
 530        char *alts = git_pathdup("objects/info/alternates");
 531        FILE *in, *out;
 532        int found = 0;
 533
 534        hold_lock_file_for_update(&lock, alts, LOCK_DIE_ON_ERROR);
 535        out = fdopen_lock_file(&lock, "w");
 536        if (!out)
 537                die_errno("unable to fdopen alternates lockfile");
 538
 539        in = fopen(alts, "r");
 540        if (in) {
 541                struct strbuf line = STRBUF_INIT;
 542
 543                while (strbuf_getline(&line, in) != EOF) {
 544                        if (!strcmp(reference, line.buf)) {
 545                                found = 1;
 546                                break;
 547                        }
 548                        fprintf_or_die(out, "%s\n", line.buf);
 549                }
 550
 551                strbuf_release(&line);
 552                fclose(in);
 553        }
 554        else if (errno != ENOENT)
 555                die_errno("unable to read alternates file");
 556
 557        if (found) {
 558                rollback_lock_file(&lock);
 559        } else {
 560                fprintf_or_die(out, "%s\n", reference);
 561                if (commit_lock_file(&lock))
 562                        die_errno("unable to move new alternates file into place");
 563                if (alt_odb_tail)
 564                        link_alt_odb_entries(reference, '\n', NULL, 0);
 565        }
 566        free(alts);
 567}
 568
 569void add_to_alternates_memory(const char *reference)
 570{
 571        /*
 572         * Make sure alternates are initialized, or else our entry may be
 573         * overwritten when they are.
 574         */
 575        prepare_alt_odb();
 576
 577        link_alt_odb_entries(reference, '\n', NULL, 0);
 578}
 579
 580/*
 581 * Compute the exact path an alternate is at and returns it. In case of
 582 * error NULL is returned and the human readable error is added to `err`
 583 * `path` may be relative and should point to $GITDIR.
 584 * `err` must not be null.
 585 */
 586char *compute_alternate_path(const char *path, struct strbuf *err)
 587{
 588        char *ref_git = NULL;
 589        const char *repo, *ref_git_s;
 590        int seen_error = 0;
 591
 592        ref_git_s = real_path_if_valid(path);
 593        if (!ref_git_s) {
 594                seen_error = 1;
 595                strbuf_addf(err, _("path '%s' does not exist"), path);
 596                goto out;
 597        } else
 598                /*
 599                 * Beware: read_gitfile(), real_path() and mkpath()
 600                 * return static buffer
 601                 */
 602                ref_git = xstrdup(ref_git_s);
 603
 604        repo = read_gitfile(ref_git);
 605        if (!repo)
 606                repo = read_gitfile(mkpath("%s/.git", ref_git));
 607        if (repo) {
 608                free(ref_git);
 609                ref_git = xstrdup(repo);
 610        }
 611
 612        if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 613                char *ref_git_git = mkpathdup("%s/.git", ref_git);
 614                free(ref_git);
 615                ref_git = ref_git_git;
 616        } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 617                struct strbuf sb = STRBUF_INIT;
 618                seen_error = 1;
 619                if (get_common_dir(&sb, ref_git)) {
 620                        strbuf_addf(err,
 621                                    _("reference repository '%s' as a linked "
 622                                      "checkout is not supported yet."),
 623                                    path);
 624                        goto out;
 625                }
 626
 627                strbuf_addf(err, _("reference repository '%s' is not a "
 628                                        "local repository."), path);
 629                goto out;
 630        }
 631
 632        if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 633                strbuf_addf(err, _("reference repository '%s' is shallow"),
 634                            path);
 635                seen_error = 1;
 636                goto out;
 637        }
 638
 639        if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 640                strbuf_addf(err,
 641                            _("reference repository '%s' is grafted"),
 642                            path);
 643                seen_error = 1;
 644                goto out;
 645        }
 646
 647out:
 648        if (seen_error) {
 649                FREE_AND_NULL(ref_git);
 650        }
 651
 652        return ref_git;
 653}
 654
 655int foreach_alt_odb(alt_odb_fn fn, void *cb)
 656{
 657        struct alternate_object_database *ent;
 658        int r = 0;
 659
 660        prepare_alt_odb();
 661        for (ent = alt_odb_list; ent; ent = ent->next) {
 662                r = fn(ent, cb);
 663                if (r)
 664                        break;
 665        }
 666        return r;
 667}
 668
 669void prepare_alt_odb(void)
 670{
 671        if (alt_odb_tail)
 672                return;
 673
 674        alt_odb_tail = &alt_odb_list;
 675        link_alt_odb_entries(the_repository->objects->alternate_db,
 676                             PATH_SEP, NULL, 0);
 677
 678        read_info_alternates(get_object_directory(), 0);
 679}
 680
 681/* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 682static int freshen_file(const char *fn)
 683{
 684        struct utimbuf t;
 685        t.actime = t.modtime = time(NULL);
 686        return !utime(fn, &t);
 687}
 688
 689/*
 690 * All of the check_and_freshen functions return 1 if the file exists and was
 691 * freshened (if freshening was requested), 0 otherwise. If they return
 692 * 0, you should not assume that it is safe to skip a write of the object (it
 693 * either does not exist on disk, or has a stale mtime and may be subject to
 694 * pruning).
 695 */
 696int check_and_freshen_file(const char *fn, int freshen)
 697{
 698        if (access(fn, F_OK))
 699                return 0;
 700        if (freshen && !freshen_file(fn))
 701                return 0;
 702        return 1;
 703}
 704
 705static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 706{
 707        static struct strbuf buf = STRBUF_INIT;
 708
 709        strbuf_reset(&buf);
 710        sha1_file_name(&buf, sha1);
 711
 712        return check_and_freshen_file(buf.buf, freshen);
 713}
 714
 715static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 716{
 717        struct alternate_object_database *alt;
 718        prepare_alt_odb();
 719        for (alt = alt_odb_list; alt; alt = alt->next) {
 720                const char *path = alt_sha1_path(alt, sha1);
 721                if (check_and_freshen_file(path, freshen))
 722                        return 1;
 723        }
 724        return 0;
 725}
 726
 727static int check_and_freshen(const unsigned char *sha1, int freshen)
 728{
 729        return check_and_freshen_local(sha1, freshen) ||
 730               check_and_freshen_nonlocal(sha1, freshen);
 731}
 732
 733int has_loose_object_nonlocal(const unsigned char *sha1)
 734{
 735        return check_and_freshen_nonlocal(sha1, 0);
 736}
 737
 738static int has_loose_object(const unsigned char *sha1)
 739{
 740        return check_and_freshen(sha1, 0);
 741}
 742
 743static void mmap_limit_check(size_t length)
 744{
 745        static size_t limit = 0;
 746        if (!limit) {
 747                limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 748                if (!limit)
 749                        limit = SIZE_MAX;
 750        }
 751        if (length > limit)
 752                die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 753                    (uintmax_t)length, (uintmax_t)limit);
 754}
 755
 756void *xmmap_gently(void *start, size_t length,
 757                  int prot, int flags, int fd, off_t offset)
 758{
 759        void *ret;
 760
 761        mmap_limit_check(length);
 762        ret = mmap(start, length, prot, flags, fd, offset);
 763        if (ret == MAP_FAILED) {
 764                if (!length)
 765                        return NULL;
 766                release_pack_memory(length);
 767                ret = mmap(start, length, prot, flags, fd, offset);
 768        }
 769        return ret;
 770}
 771
 772void *xmmap(void *start, size_t length,
 773        int prot, int flags, int fd, off_t offset)
 774{
 775        void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 776        if (ret == MAP_FAILED)
 777                die_errno("mmap failed");
 778        return ret;
 779}
 780
 781/*
 782 * With an in-core object data in "map", rehash it to make sure the
 783 * object name actually matches "sha1" to detect object corruption.
 784 * With "map" == NULL, try reading the object named with "sha1" using
 785 * the streaming interface and rehash it to do the same.
 786 */
 787int check_sha1_signature(const unsigned char *sha1, void *map,
 788                         unsigned long size, const char *type)
 789{
 790        unsigned char real_sha1[20];
 791        enum object_type obj_type;
 792        struct git_istream *st;
 793        git_SHA_CTX c;
 794        char hdr[32];
 795        int hdrlen;
 796
 797        if (map) {
 798                hash_sha1_file(map, size, type, real_sha1);
 799                return hashcmp(sha1, real_sha1) ? -1 : 0;
 800        }
 801
 802        st = open_istream(sha1, &obj_type, &size, NULL);
 803        if (!st)
 804                return -1;
 805
 806        /* Generate the header */
 807        hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(obj_type), size) + 1;
 808
 809        /* Sha1.. */
 810        git_SHA1_Init(&c);
 811        git_SHA1_Update(&c, hdr, hdrlen);
 812        for (;;) {
 813                char buf[1024 * 16];
 814                ssize_t readlen = read_istream(st, buf, sizeof(buf));
 815
 816                if (readlen < 0) {
 817                        close_istream(st);
 818                        return -1;
 819                }
 820                if (!readlen)
 821                        break;
 822                git_SHA1_Update(&c, buf, readlen);
 823        }
 824        git_SHA1_Final(real_sha1, &c);
 825        close_istream(st);
 826        return hashcmp(sha1, real_sha1) ? -1 : 0;
 827}
 828
 829int git_open_cloexec(const char *name, int flags)
 830{
 831        int fd;
 832        static int o_cloexec = O_CLOEXEC;
 833
 834        fd = open(name, flags | o_cloexec);
 835        if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
 836                /* Try again w/o O_CLOEXEC: the kernel might not support it */
 837                o_cloexec &= ~O_CLOEXEC;
 838                fd = open(name, flags | o_cloexec);
 839        }
 840
 841#if defined(F_GETFD) && defined(F_SETFD) && defined(FD_CLOEXEC)
 842        {
 843                static int fd_cloexec = FD_CLOEXEC;
 844
 845                if (!o_cloexec && 0 <= fd && fd_cloexec) {
 846                        /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
 847                        int flags = fcntl(fd, F_GETFD);
 848                        if (fcntl(fd, F_SETFD, flags | fd_cloexec))
 849                                fd_cloexec = 0;
 850                }
 851        }
 852#endif
 853        return fd;
 854}
 855
 856/*
 857 * Find "sha1" as a loose object in the local repository or in an alternate.
 858 * Returns 0 on success, negative on failure.
 859 *
 860 * The "path" out-parameter will give the path of the object we found (if any).
 861 * Note that it may point to static storage and is only valid until another
 862 * call to sha1_file_name(), etc.
 863 */
 864static int stat_sha1_file(const unsigned char *sha1, struct stat *st,
 865                          const char **path)
 866{
 867        struct alternate_object_database *alt;
 868        static struct strbuf buf = STRBUF_INIT;
 869
 870        strbuf_reset(&buf);
 871        sha1_file_name(&buf, sha1);
 872        *path = buf.buf;
 873
 874        if (!lstat(*path, st))
 875                return 0;
 876
 877        prepare_alt_odb();
 878        errno = ENOENT;
 879        for (alt = alt_odb_list; alt; alt = alt->next) {
 880                *path = alt_sha1_path(alt, sha1);
 881                if (!lstat(*path, st))
 882                        return 0;
 883        }
 884
 885        return -1;
 886}
 887
 888/*
 889 * Like stat_sha1_file(), but actually open the object and return the
 890 * descriptor. See the caveats on the "path" parameter above.
 891 */
 892static int open_sha1_file(const unsigned char *sha1, const char **path)
 893{
 894        int fd;
 895        struct alternate_object_database *alt;
 896        int most_interesting_errno;
 897        static struct strbuf buf = STRBUF_INIT;
 898
 899        strbuf_reset(&buf);
 900        sha1_file_name(&buf, sha1);
 901        *path = buf.buf;
 902
 903        fd = git_open(*path);
 904        if (fd >= 0)
 905                return fd;
 906        most_interesting_errno = errno;
 907
 908        prepare_alt_odb();
 909        for (alt = alt_odb_list; alt; alt = alt->next) {
 910                *path = alt_sha1_path(alt, sha1);
 911                fd = git_open(*path);
 912                if (fd >= 0)
 913                        return fd;
 914                if (most_interesting_errno == ENOENT)
 915                        most_interesting_errno = errno;
 916        }
 917        errno = most_interesting_errno;
 918        return -1;
 919}
 920
 921/*
 922 * Map the loose object at "path" if it is not NULL, or the path found by
 923 * searching for a loose object named "sha1".
 924 */
 925static void *map_sha1_file_1(const char *path,
 926                             const unsigned char *sha1,
 927                             unsigned long *size)
 928{
 929        void *map;
 930        int fd;
 931
 932        if (path)
 933                fd = git_open(path);
 934        else
 935                fd = open_sha1_file(sha1, &path);
 936        map = NULL;
 937        if (fd >= 0) {
 938                struct stat st;
 939
 940                if (!fstat(fd, &st)) {
 941                        *size = xsize_t(st.st_size);
 942                        if (!*size) {
 943                                /* mmap() is forbidden on empty files */
 944                                error("object file %s is empty", path);
 945                                return NULL;
 946                        }
 947                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 948                }
 949                close(fd);
 950        }
 951        return map;
 952}
 953
 954void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 955{
 956        return map_sha1_file_1(NULL, sha1, size);
 957}
 958
 959static int unpack_sha1_short_header(git_zstream *stream,
 960                                    unsigned char *map, unsigned long mapsize,
 961                                    void *buffer, unsigned long bufsiz)
 962{
 963        /* Get the data stream */
 964        memset(stream, 0, sizeof(*stream));
 965        stream->next_in = map;
 966        stream->avail_in = mapsize;
 967        stream->next_out = buffer;
 968        stream->avail_out = bufsiz;
 969
 970        git_inflate_init(stream);
 971        return git_inflate(stream, 0);
 972}
 973
 974int unpack_sha1_header(git_zstream *stream,
 975                       unsigned char *map, unsigned long mapsize,
 976                       void *buffer, unsigned long bufsiz)
 977{
 978        int status = unpack_sha1_short_header(stream, map, mapsize,
 979                                              buffer, bufsiz);
 980
 981        if (status < Z_OK)
 982                return status;
 983
 984        /* Make sure we have the terminating NUL */
 985        if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
 986                return -1;
 987        return 0;
 988}
 989
 990static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
 991                                        unsigned long mapsize, void *buffer,
 992                                        unsigned long bufsiz, struct strbuf *header)
 993{
 994        int status;
 995
 996        status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
 997        if (status < Z_OK)
 998                return -1;
 999
1000        /*
1001         * Check if entire header is unpacked in the first iteration.
1002         */
1003        if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1004                return 0;
1005
1006        /*
1007         * buffer[0..bufsiz] was not large enough.  Copy the partial
1008         * result out to header, and then append the result of further
1009         * reading the stream.
1010         */
1011        strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1012        stream->next_out = buffer;
1013        stream->avail_out = bufsiz;
1014
1015        do {
1016                status = git_inflate(stream, 0);
1017                strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1018                if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1019                        return 0;
1020                stream->next_out = buffer;
1021                stream->avail_out = bufsiz;
1022        } while (status != Z_STREAM_END);
1023        return -1;
1024}
1025
1026static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1027{
1028        int bytes = strlen(buffer) + 1;
1029        unsigned char *buf = xmallocz(size);
1030        unsigned long n;
1031        int status = Z_OK;
1032
1033        n = stream->total_out - bytes;
1034        if (n > size)
1035                n = size;
1036        memcpy(buf, (char *) buffer + bytes, n);
1037        bytes = n;
1038        if (bytes <= size) {
1039                /*
1040                 * The above condition must be (bytes <= size), not
1041                 * (bytes < size).  In other words, even though we
1042                 * expect no more output and set avail_out to zero,
1043                 * the input zlib stream may have bytes that express
1044                 * "this concludes the stream", and we *do* want to
1045                 * eat that input.
1046                 *
1047                 * Otherwise we would not be able to test that we
1048                 * consumed all the input to reach the expected size;
1049                 * we also want to check that zlib tells us that all
1050                 * went well with status == Z_STREAM_END at the end.
1051                 */
1052                stream->next_out = buf + bytes;
1053                stream->avail_out = size - bytes;
1054                while (status == Z_OK)
1055                        status = git_inflate(stream, Z_FINISH);
1056        }
1057        if (status == Z_STREAM_END && !stream->avail_in) {
1058                git_inflate_end(stream);
1059                return buf;
1060        }
1061
1062        if (status < 0)
1063                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1064        else if (stream->avail_in)
1065                error("garbage at end of loose object '%s'",
1066                      sha1_to_hex(sha1));
1067        free(buf);
1068        return NULL;
1069}
1070
1071/*
1072 * We used to just use "sscanf()", but that's actually way
1073 * too permissive for what we want to check. So do an anal
1074 * object header parse by hand.
1075 */
1076static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1077                               unsigned int flags)
1078{
1079        const char *type_buf = hdr;
1080        unsigned long size;
1081        int type, type_len = 0;
1082
1083        /*
1084         * The type can be of any size but is followed by
1085         * a space.
1086         */
1087        for (;;) {
1088                char c = *hdr++;
1089                if (!c)
1090                        return -1;
1091                if (c == ' ')
1092                        break;
1093                type_len++;
1094        }
1095
1096        type = type_from_string_gently(type_buf, type_len, 1);
1097        if (oi->typename)
1098                strbuf_add(oi->typename, type_buf, type_len);
1099        /*
1100         * Set type to 0 if its an unknown object and
1101         * we're obtaining the type using '--allow-unknown-type'
1102         * option.
1103         */
1104        if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
1105                type = 0;
1106        else if (type < 0)
1107                die("invalid object type");
1108        if (oi->typep)
1109                *oi->typep = type;
1110
1111        /*
1112         * The length must follow immediately, and be in canonical
1113         * decimal format (ie "010" is not valid).
1114         */
1115        size = *hdr++ - '0';
1116        if (size > 9)
1117                return -1;
1118        if (size) {
1119                for (;;) {
1120                        unsigned long c = *hdr - '0';
1121                        if (c > 9)
1122                                break;
1123                        hdr++;
1124                        size = size * 10 + c;
1125                }
1126        }
1127
1128        if (oi->sizep)
1129                *oi->sizep = size;
1130
1131        /*
1132         * The length must be followed by a zero byte
1133         */
1134        return *hdr ? -1 : type;
1135}
1136
1137int parse_sha1_header(const char *hdr, unsigned long *sizep)
1138{
1139        struct object_info oi = OBJECT_INFO_INIT;
1140
1141        oi.sizep = sizep;
1142        return parse_sha1_header_extended(hdr, &oi, 0);
1143}
1144
1145static int sha1_loose_object_info(const unsigned char *sha1,
1146                                  struct object_info *oi,
1147                                  int flags)
1148{
1149        int status = 0;
1150        unsigned long mapsize;
1151        void *map;
1152        git_zstream stream;
1153        char hdr[32];
1154        struct strbuf hdrbuf = STRBUF_INIT;
1155        unsigned long size_scratch;
1156
1157        if (oi->delta_base_sha1)
1158                hashclr(oi->delta_base_sha1);
1159
1160        /*
1161         * If we don't care about type or size, then we don't
1162         * need to look inside the object at all. Note that we
1163         * do not optimize out the stat call, even if the
1164         * caller doesn't care about the disk-size, since our
1165         * return value implicitly indicates whether the
1166         * object even exists.
1167         */
1168        if (!oi->typep && !oi->typename && !oi->sizep && !oi->contentp) {
1169                const char *path;
1170                struct stat st;
1171                if (stat_sha1_file(sha1, &st, &path) < 0)
1172                        return -1;
1173                if (oi->disk_sizep)
1174                        *oi->disk_sizep = st.st_size;
1175                return 0;
1176        }
1177
1178        map = map_sha1_file(sha1, &mapsize);
1179        if (!map)
1180                return -1;
1181
1182        if (!oi->sizep)
1183                oi->sizep = &size_scratch;
1184
1185        if (oi->disk_sizep)
1186                *oi->disk_sizep = mapsize;
1187        if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE)) {
1188                if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
1189                        status = error("unable to unpack %s header with --allow-unknown-type",
1190                                       sha1_to_hex(sha1));
1191        } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1192                status = error("unable to unpack %s header",
1193                               sha1_to_hex(sha1));
1194        if (status < 0)
1195                ; /* Do nothing */
1196        else if (hdrbuf.len) {
1197                if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
1198                        status = error("unable to parse %s header with --allow-unknown-type",
1199                                       sha1_to_hex(sha1));
1200        } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
1201                status = error("unable to parse %s header", sha1_to_hex(sha1));
1202
1203        if (status >= 0 && oi->contentp) {
1204                *oi->contentp = unpack_sha1_rest(&stream, hdr,
1205                                                 *oi->sizep, sha1);
1206                if (!*oi->contentp) {
1207                        git_inflate_end(&stream);
1208                        status = -1;
1209                }
1210        } else
1211                git_inflate_end(&stream);
1212
1213        munmap(map, mapsize);
1214        if (status && oi->typep)
1215                *oi->typep = status;
1216        if (oi->sizep == &size_scratch)
1217                oi->sizep = NULL;
1218        strbuf_release(&hdrbuf);
1219        oi->whence = OI_LOOSE;
1220        return (status < 0) ? status : 0;
1221}
1222
1223int fetch_if_missing = 1;
1224
1225int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
1226{
1227        static struct object_info blank_oi = OBJECT_INFO_INIT;
1228        struct pack_entry e;
1229        int rtype;
1230        const unsigned char *real = (flags & OBJECT_INFO_LOOKUP_REPLACE) ?
1231                                    lookup_replace_object(sha1) :
1232                                    sha1;
1233        int already_retried = 0;
1234
1235        if (is_null_sha1(real))
1236                return -1;
1237
1238        if (!oi)
1239                oi = &blank_oi;
1240
1241        if (!(flags & OBJECT_INFO_SKIP_CACHED)) {
1242                struct cached_object *co = find_cached_object(real);
1243                if (co) {
1244                        if (oi->typep)
1245                                *(oi->typep) = co->type;
1246                        if (oi->sizep)
1247                                *(oi->sizep) = co->size;
1248                        if (oi->disk_sizep)
1249                                *(oi->disk_sizep) = 0;
1250                        if (oi->delta_base_sha1)
1251                                hashclr(oi->delta_base_sha1);
1252                        if (oi->typename)
1253                                strbuf_addstr(oi->typename, typename(co->type));
1254                        if (oi->contentp)
1255                                *oi->contentp = xmemdupz(co->buf, co->size);
1256                        oi->whence = OI_CACHED;
1257                        return 0;
1258                }
1259        }
1260
1261        while (1) {
1262                if (find_pack_entry(real, &e))
1263                        break;
1264
1265                /* Most likely it's a loose object. */
1266                if (!sha1_loose_object_info(real, oi, flags))
1267                        return 0;
1268
1269                /* Not a loose object; someone else may have just packed it. */
1270                reprepare_packed_git();
1271                if (find_pack_entry(real, &e))
1272                        break;
1273
1274                /* Check if it is a missing object */
1275                if (fetch_if_missing && repository_format_partial_clone &&
1276                    !already_retried) {
1277                        /*
1278                         * TODO Investigate haveing fetch_object() return
1279                         * TODO error/success and stopping the music here.
1280                         */
1281                        fetch_object(repository_format_partial_clone, real);
1282                        already_retried = 1;
1283                        continue;
1284                }
1285
1286                return -1;
1287        }
1288
1289        if (oi == &blank_oi)
1290                /*
1291                 * We know that the caller doesn't actually need the
1292                 * information below, so return early.
1293                 */
1294                return 0;
1295        rtype = packed_object_info(e.p, e.offset, oi);
1296        if (rtype < 0) {
1297                mark_bad_packed_object(e.p, real);
1298                return sha1_object_info_extended(real, oi, 0);
1299        } else if (oi->whence == OI_PACKED) {
1300                oi->u.packed.offset = e.offset;
1301                oi->u.packed.pack = e.p;
1302                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
1303                                         rtype == OBJ_OFS_DELTA);
1304        }
1305
1306        return 0;
1307}
1308
1309/* returns enum object_type or negative */
1310int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1311{
1312        enum object_type type;
1313        struct object_info oi = OBJECT_INFO_INIT;
1314
1315        oi.typep = &type;
1316        oi.sizep = sizep;
1317        if (sha1_object_info_extended(sha1, &oi,
1318                                      OBJECT_INFO_LOOKUP_REPLACE) < 0)
1319                return -1;
1320        return type;
1321}
1322
1323static void *read_object(const unsigned char *sha1, enum object_type *type,
1324                         unsigned long *size)
1325{
1326        struct object_info oi = OBJECT_INFO_INIT;
1327        void *content;
1328        oi.typep = type;
1329        oi.sizep = size;
1330        oi.contentp = &content;
1331
1332        if (sha1_object_info_extended(sha1, &oi, 0) < 0)
1333                return NULL;
1334        return content;
1335}
1336
1337int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
1338                      unsigned char *sha1)
1339{
1340        struct cached_object *co;
1341
1342        hash_sha1_file(buf, len, typename(type), sha1);
1343        if (has_sha1_file(sha1) || find_cached_object(sha1))
1344                return 0;
1345        ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
1346        co = &cached_objects[cached_object_nr++];
1347        co->size = len;
1348        co->type = type;
1349        co->buf = xmalloc(len);
1350        memcpy(co->buf, buf, len);
1351        hashcpy(co->sha1, sha1);
1352        return 0;
1353}
1354
1355/*
1356 * This function dies on corrupt objects; the callers who want to
1357 * deal with them should arrange to call read_object() and give error
1358 * messages themselves.
1359 */
1360void *read_sha1_file_extended(const unsigned char *sha1,
1361                              enum object_type *type,
1362                              unsigned long *size,
1363                              int lookup_replace)
1364{
1365        void *data;
1366        const struct packed_git *p;
1367        const char *path;
1368        struct stat st;
1369        const unsigned char *repl = lookup_replace ? lookup_replace_object(sha1)
1370                                                   : sha1;
1371
1372        errno = 0;
1373        data = read_object(repl, type, size);
1374        if (data)
1375                return data;
1376
1377        if (errno && errno != ENOENT)
1378                die_errno("failed to read object %s", sha1_to_hex(sha1));
1379
1380        /* die if we replaced an object with one that does not exist */
1381        if (repl != sha1)
1382                die("replacement %s not found for %s",
1383                    sha1_to_hex(repl), sha1_to_hex(sha1));
1384
1385        if (!stat_sha1_file(repl, &st, &path))
1386                die("loose object %s (stored in %s) is corrupt",
1387                    sha1_to_hex(repl), path);
1388
1389        if ((p = has_packed_and_bad(repl)) != NULL)
1390                die("packed object %s (stored in %s) is corrupt",
1391                    sha1_to_hex(repl), p->pack_name);
1392
1393        return NULL;
1394}
1395
1396void *read_object_with_reference(const unsigned char *sha1,
1397                                 const char *required_type_name,
1398                                 unsigned long *size,
1399                                 unsigned char *actual_sha1_return)
1400{
1401        enum object_type type, required_type;
1402        void *buffer;
1403        unsigned long isize;
1404        unsigned char actual_sha1[20];
1405
1406        required_type = type_from_string(required_type_name);
1407        hashcpy(actual_sha1, sha1);
1408        while (1) {
1409                int ref_length = -1;
1410                const char *ref_type = NULL;
1411
1412                buffer = read_sha1_file(actual_sha1, &type, &isize);
1413                if (!buffer)
1414                        return NULL;
1415                if (type == required_type) {
1416                        *size = isize;
1417                        if (actual_sha1_return)
1418                                hashcpy(actual_sha1_return, actual_sha1);
1419                        return buffer;
1420                }
1421                /* Handle references */
1422                else if (type == OBJ_COMMIT)
1423                        ref_type = "tree ";
1424                else if (type == OBJ_TAG)
1425                        ref_type = "object ";
1426                else {
1427                        free(buffer);
1428                        return NULL;
1429                }
1430                ref_length = strlen(ref_type);
1431
1432                if (ref_length + 40 > isize ||
1433                    memcmp(buffer, ref_type, ref_length) ||
1434                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1435                        free(buffer);
1436                        return NULL;
1437                }
1438                free(buffer);
1439                /* Now we have the ID of the referred-to object in
1440                 * actual_sha1.  Check again. */
1441        }
1442}
1443
1444static void write_sha1_file_prepare(const void *buf, unsigned long len,
1445                                    const char *type, unsigned char *sha1,
1446                                    char *hdr, int *hdrlen)
1447{
1448        git_SHA_CTX c;
1449
1450        /* Generate the header */
1451        *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
1452
1453        /* Sha1.. */
1454        git_SHA1_Init(&c);
1455        git_SHA1_Update(&c, hdr, *hdrlen);
1456        git_SHA1_Update(&c, buf, len);
1457        git_SHA1_Final(sha1, &c);
1458}
1459
1460/*
1461 * Move the just written object into its final resting place.
1462 */
1463int finalize_object_file(const char *tmpfile, const char *filename)
1464{
1465        int ret = 0;
1466
1467        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
1468                goto try_rename;
1469        else if (link(tmpfile, filename))
1470                ret = errno;
1471
1472        /*
1473         * Coda hack - coda doesn't like cross-directory links,
1474         * so we fall back to a rename, which will mean that it
1475         * won't be able to check collisions, but that's not a
1476         * big deal.
1477         *
1478         * The same holds for FAT formatted media.
1479         *
1480         * When this succeeds, we just return.  We have nothing
1481         * left to unlink.
1482         */
1483        if (ret && ret != EEXIST) {
1484        try_rename:
1485                if (!rename(tmpfile, filename))
1486                        goto out;
1487                ret = errno;
1488        }
1489        unlink_or_warn(tmpfile);
1490        if (ret) {
1491                if (ret != EEXIST) {
1492                        return error_errno("unable to write sha1 filename %s", filename);
1493                }
1494                /* FIXME!!! Collision check here ? */
1495        }
1496
1497out:
1498        if (adjust_shared_perm(filename))
1499                return error("unable to set permission to '%s'", filename);
1500        return 0;
1501}
1502
1503static int write_buffer(int fd, const void *buf, size_t len)
1504{
1505        if (write_in_full(fd, buf, len) < 0)
1506                return error_errno("file write error");
1507        return 0;
1508}
1509
1510int hash_sha1_file(const void *buf, unsigned long len, const char *type,
1511                   unsigned char *sha1)
1512{
1513        char hdr[32];
1514        int hdrlen = sizeof(hdr);
1515        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1516        return 0;
1517}
1518
1519/* Finalize a file on disk, and close it. */
1520static void close_sha1_file(int fd)
1521{
1522        if (fsync_object_files)
1523                fsync_or_die(fd, "sha1 file");
1524        if (close(fd) != 0)
1525                die_errno("error when closing sha1 file");
1526}
1527
1528/* Size of directory component, including the ending '/' */
1529static inline int directory_size(const char *filename)
1530{
1531        const char *s = strrchr(filename, '/');
1532        if (!s)
1533                return 0;
1534        return s - filename + 1;
1535}
1536
1537/*
1538 * This creates a temporary file in the same directory as the final
1539 * 'filename'
1540 *
1541 * We want to avoid cross-directory filename renames, because those
1542 * can have problems on various filesystems (FAT, NFS, Coda).
1543 */
1544static int create_tmpfile(struct strbuf *tmp, const char *filename)
1545{
1546        int fd, dirlen = directory_size(filename);
1547
1548        strbuf_reset(tmp);
1549        strbuf_add(tmp, filename, dirlen);
1550        strbuf_addstr(tmp, "tmp_obj_XXXXXX");
1551        fd = git_mkstemp_mode(tmp->buf, 0444);
1552        if (fd < 0 && dirlen && errno == ENOENT) {
1553                /*
1554                 * Make sure the directory exists; note that the contents
1555                 * of the buffer are undefined after mkstemp returns an
1556                 * error, so we have to rewrite the whole buffer from
1557                 * scratch.
1558                 */
1559                strbuf_reset(tmp);
1560                strbuf_add(tmp, filename, dirlen - 1);
1561                if (mkdir(tmp->buf, 0777) && errno != EEXIST)
1562                        return -1;
1563                if (adjust_shared_perm(tmp->buf))
1564                        return -1;
1565
1566                /* Try again */
1567                strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
1568                fd = git_mkstemp_mode(tmp->buf, 0444);
1569        }
1570        return fd;
1571}
1572
1573static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
1574                              const void *buf, unsigned long len, time_t mtime)
1575{
1576        int fd, ret;
1577        unsigned char compressed[4096];
1578        git_zstream stream;
1579        git_SHA_CTX c;
1580        unsigned char parano_sha1[20];
1581        static struct strbuf tmp_file = STRBUF_INIT;
1582        static struct strbuf filename = STRBUF_INIT;
1583
1584        strbuf_reset(&filename);
1585        sha1_file_name(&filename, sha1);
1586
1587        fd = create_tmpfile(&tmp_file, filename.buf);
1588        if (fd < 0) {
1589                if (errno == EACCES)
1590                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
1591                else
1592                        return error_errno("unable to create temporary file");
1593        }
1594
1595        /* Set it up */
1596        git_deflate_init(&stream, zlib_compression_level);
1597        stream.next_out = compressed;
1598        stream.avail_out = sizeof(compressed);
1599        git_SHA1_Init(&c);
1600
1601        /* First header.. */
1602        stream.next_in = (unsigned char *)hdr;
1603        stream.avail_in = hdrlen;
1604        while (git_deflate(&stream, 0) == Z_OK)
1605                ; /* nothing */
1606        git_SHA1_Update(&c, hdr, hdrlen);
1607
1608        /* Then the data itself.. */
1609        stream.next_in = (void *)buf;
1610        stream.avail_in = len;
1611        do {
1612                unsigned char *in0 = stream.next_in;
1613                ret = git_deflate(&stream, Z_FINISH);
1614                git_SHA1_Update(&c, in0, stream.next_in - in0);
1615                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
1616                        die("unable to write sha1 file");
1617                stream.next_out = compressed;
1618                stream.avail_out = sizeof(compressed);
1619        } while (ret == Z_OK);
1620
1621        if (ret != Z_STREAM_END)
1622                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
1623        ret = git_deflate_end_gently(&stream);
1624        if (ret != Z_OK)
1625                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
1626        git_SHA1_Final(parano_sha1, &c);
1627        if (hashcmp(sha1, parano_sha1) != 0)
1628                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
1629
1630        close_sha1_file(fd);
1631
1632        if (mtime) {
1633                struct utimbuf utb;
1634                utb.actime = mtime;
1635                utb.modtime = mtime;
1636                if (utime(tmp_file.buf, &utb) < 0)
1637                        warning_errno("failed utime() on %s", tmp_file.buf);
1638        }
1639
1640        return finalize_object_file(tmp_file.buf, filename.buf);
1641}
1642
1643static int freshen_loose_object(const unsigned char *sha1)
1644{
1645        return check_and_freshen(sha1, 1);
1646}
1647
1648static int freshen_packed_object(const unsigned char *sha1)
1649{
1650        struct pack_entry e;
1651        if (!find_pack_entry(sha1, &e))
1652                return 0;
1653        if (e.p->freshened)
1654                return 1;
1655        if (!freshen_file(e.p->pack_name))
1656                return 0;
1657        e.p->freshened = 1;
1658        return 1;
1659}
1660
1661int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
1662{
1663        char hdr[32];
1664        int hdrlen = sizeof(hdr);
1665
1666        /* Normally if we have it in the pack then we do not bother writing
1667         * it out into .git/objects/??/?{38} file.
1668         */
1669        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1670        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
1671                return 0;
1672        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
1673}
1674
1675int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
1676                             struct object_id *oid, unsigned flags)
1677{
1678        char *header;
1679        int hdrlen, status = 0;
1680
1681        /* type string, SP, %lu of the length plus NUL must fit this */
1682        hdrlen = strlen(type) + 32;
1683        header = xmalloc(hdrlen);
1684        write_sha1_file_prepare(buf, len, type, oid->hash, header, &hdrlen);
1685
1686        if (!(flags & HASH_WRITE_OBJECT))
1687                goto cleanup;
1688        if (freshen_packed_object(oid->hash) || freshen_loose_object(oid->hash))
1689                goto cleanup;
1690        status = write_loose_object(oid->hash, header, hdrlen, buf, len, 0);
1691
1692cleanup:
1693        free(header);
1694        return status;
1695}
1696
1697int force_object_loose(const unsigned char *sha1, time_t mtime)
1698{
1699        void *buf;
1700        unsigned long len;
1701        enum object_type type;
1702        char hdr[32];
1703        int hdrlen;
1704        int ret;
1705
1706        if (has_loose_object(sha1))
1707                return 0;
1708        buf = read_object(sha1, &type, &len);
1709        if (!buf)
1710                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1711        hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(type), len) + 1;
1712        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
1713        free(buf);
1714
1715        return ret;
1716}
1717
1718int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
1719{
1720        if (!startup_info->have_repository)
1721                return 0;
1722        return sha1_object_info_extended(sha1, NULL,
1723                                         flags | OBJECT_INFO_SKIP_CACHED) >= 0;
1724}
1725
1726int has_object_file(const struct object_id *oid)
1727{
1728        return has_sha1_file(oid->hash);
1729}
1730
1731int has_object_file_with_flags(const struct object_id *oid, int flags)
1732{
1733        return has_sha1_file_with_flags(oid->hash, flags);
1734}
1735
1736static void check_tree(const void *buf, size_t size)
1737{
1738        struct tree_desc desc;
1739        struct name_entry entry;
1740
1741        init_tree_desc(&desc, buf, size);
1742        while (tree_entry(&desc, &entry))
1743                /* do nothing
1744                 * tree_entry() will die() on malformed entries */
1745                ;
1746}
1747
1748static void check_commit(const void *buf, size_t size)
1749{
1750        struct commit c;
1751        memset(&c, 0, sizeof(c));
1752        if (parse_commit_buffer(&c, buf, size))
1753                die("corrupt commit");
1754}
1755
1756static void check_tag(const void *buf, size_t size)
1757{
1758        struct tag t;
1759        memset(&t, 0, sizeof(t));
1760        if (parse_tag_buffer(&t, buf, size))
1761                die("corrupt tag");
1762}
1763
1764static int index_mem(struct object_id *oid, void *buf, size_t size,
1765                     enum object_type type,
1766                     const char *path, unsigned flags)
1767{
1768        int ret, re_allocated = 0;
1769        int write_object = flags & HASH_WRITE_OBJECT;
1770
1771        if (!type)
1772                type = OBJ_BLOB;
1773
1774        /*
1775         * Convert blobs to git internal format
1776         */
1777        if ((type == OBJ_BLOB) && path) {
1778                struct strbuf nbuf = STRBUF_INIT;
1779                if (convert_to_git(&the_index, path, buf, size, &nbuf,
1780                                   get_conv_flags(flags))) {
1781                        buf = strbuf_detach(&nbuf, &size);
1782                        re_allocated = 1;
1783                }
1784        }
1785        if (flags & HASH_FORMAT_CHECK) {
1786                if (type == OBJ_TREE)
1787                        check_tree(buf, size);
1788                if (type == OBJ_COMMIT)
1789                        check_commit(buf, size);
1790                if (type == OBJ_TAG)
1791                        check_tag(buf, size);
1792        }
1793
1794        if (write_object)
1795                ret = write_sha1_file(buf, size, typename(type), oid->hash);
1796        else
1797                ret = hash_sha1_file(buf, size, typename(type), oid->hash);
1798        if (re_allocated)
1799                free(buf);
1800        return ret;
1801}
1802
1803static int index_stream_convert_blob(struct object_id *oid, int fd,
1804                                     const char *path, unsigned flags)
1805{
1806        int ret;
1807        const int write_object = flags & HASH_WRITE_OBJECT;
1808        struct strbuf sbuf = STRBUF_INIT;
1809
1810        assert(path);
1811        assert(would_convert_to_git_filter_fd(path));
1812
1813        convert_to_git_filter_fd(&the_index, path, fd, &sbuf,
1814                                 get_conv_flags(flags));
1815
1816        if (write_object)
1817                ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
1818                                      oid->hash);
1819        else
1820                ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
1821                                     oid->hash);
1822        strbuf_release(&sbuf);
1823        return ret;
1824}
1825
1826static int index_pipe(struct object_id *oid, int fd, enum object_type type,
1827                      const char *path, unsigned flags)
1828{
1829        struct strbuf sbuf = STRBUF_INIT;
1830        int ret;
1831
1832        if (strbuf_read(&sbuf, fd, 4096) >= 0)
1833                ret = index_mem(oid, sbuf.buf, sbuf.len, type, path, flags);
1834        else
1835                ret = -1;
1836        strbuf_release(&sbuf);
1837        return ret;
1838}
1839
1840#define SMALL_FILE_SIZE (32*1024)
1841
1842static int index_core(struct object_id *oid, int fd, size_t size,
1843                      enum object_type type, const char *path,
1844                      unsigned flags)
1845{
1846        int ret;
1847
1848        if (!size) {
1849                ret = index_mem(oid, "", size, type, path, flags);
1850        } else if (size <= SMALL_FILE_SIZE) {
1851                char *buf = xmalloc(size);
1852                ssize_t read_result = read_in_full(fd, buf, size);
1853                if (read_result < 0)
1854                        ret = error_errno("read error while indexing %s",
1855                                          path ? path : "<unknown>");
1856                else if (read_result != size)
1857                        ret = error("short read while indexing %s",
1858                                    path ? path : "<unknown>");
1859                else
1860                        ret = index_mem(oid, buf, size, type, path, flags);
1861                free(buf);
1862        } else {
1863                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1864                ret = index_mem(oid, buf, size, type, path, flags);
1865                munmap(buf, size);
1866        }
1867        return ret;
1868}
1869
1870/*
1871 * This creates one packfile per large blob unless bulk-checkin
1872 * machinery is "plugged".
1873 *
1874 * This also bypasses the usual "convert-to-git" dance, and that is on
1875 * purpose. We could write a streaming version of the converting
1876 * functions and insert that before feeding the data to fast-import
1877 * (or equivalent in-core API described above). However, that is
1878 * somewhat complicated, as we do not know the size of the filter
1879 * result, which we need to know beforehand when writing a git object.
1880 * Since the primary motivation for trying to stream from the working
1881 * tree file and to avoid mmaping it in core is to deal with large
1882 * binary blobs, they generally do not want to get any conversion, and
1883 * callers should avoid this code path when filters are requested.
1884 */
1885static int index_stream(struct object_id *oid, int fd, size_t size,
1886                        enum object_type type, const char *path,
1887                        unsigned flags)
1888{
1889        return index_bulk_checkin(oid->hash, fd, size, type, path, flags);
1890}
1891
1892int index_fd(struct object_id *oid, int fd, struct stat *st,
1893             enum object_type type, const char *path, unsigned flags)
1894{
1895        int ret;
1896
1897        /*
1898         * Call xsize_t() only when needed to avoid potentially unnecessary
1899         * die() for large files.
1900         */
1901        if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
1902                ret = index_stream_convert_blob(oid, fd, path, flags);
1903        else if (!S_ISREG(st->st_mode))
1904                ret = index_pipe(oid, fd, type, path, flags);
1905        else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
1906                 (path && would_convert_to_git(&the_index, path)))
1907                ret = index_core(oid, fd, xsize_t(st->st_size), type, path,
1908                                 flags);
1909        else
1910                ret = index_stream(oid, fd, xsize_t(st->st_size), type, path,
1911                                   flags);
1912        close(fd);
1913        return ret;
1914}
1915
1916int index_path(struct object_id *oid, const char *path, struct stat *st, unsigned flags)
1917{
1918        int fd;
1919        struct strbuf sb = STRBUF_INIT;
1920        int rc = 0;
1921
1922        switch (st->st_mode & S_IFMT) {
1923        case S_IFREG:
1924                fd = open(path, O_RDONLY);
1925                if (fd < 0)
1926                        return error_errno("open(\"%s\")", path);
1927                if (index_fd(oid, fd, st, OBJ_BLOB, path, flags) < 0)
1928                        return error("%s: failed to insert into database",
1929                                     path);
1930                break;
1931        case S_IFLNK:
1932                if (strbuf_readlink(&sb, path, st->st_size))
1933                        return error_errno("readlink(\"%s\")", path);
1934                if (!(flags & HASH_WRITE_OBJECT))
1935                        hash_sha1_file(sb.buf, sb.len, blob_type, oid->hash);
1936                else if (write_sha1_file(sb.buf, sb.len, blob_type, oid->hash))
1937                        rc = error("%s: failed to insert into database", path);
1938                strbuf_release(&sb);
1939                break;
1940        case S_IFDIR:
1941                return resolve_gitlink_ref(path, "HEAD", oid);
1942        default:
1943                return error("%s: unsupported file type", path);
1944        }
1945        return rc;
1946}
1947
1948int read_pack_header(int fd, struct pack_header *header)
1949{
1950        if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header))
1951                /* "eof before pack header was fully read" */
1952                return PH_ERROR_EOF;
1953
1954        if (header->hdr_signature != htonl(PACK_SIGNATURE))
1955                /* "protocol error (pack signature mismatch detected)" */
1956                return PH_ERROR_PACK_SIGNATURE;
1957        if (!pack_version_ok(header->hdr_version))
1958                /* "protocol error (pack version unsupported)" */
1959                return PH_ERROR_PROTOCOL;
1960        return 0;
1961}
1962
1963void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
1964{
1965        enum object_type type = sha1_object_info(sha1, NULL);
1966        if (type < 0)
1967                die("%s is not a valid object", sha1_to_hex(sha1));
1968        if (type != expect)
1969                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
1970                    typename(expect));
1971}
1972
1973int for_each_file_in_obj_subdir(unsigned int subdir_nr,
1974                                struct strbuf *path,
1975                                each_loose_object_fn obj_cb,
1976                                each_loose_cruft_fn cruft_cb,
1977                                each_loose_subdir_fn subdir_cb,
1978                                void *data)
1979{
1980        size_t origlen, baselen;
1981        DIR *dir;
1982        struct dirent *de;
1983        int r = 0;
1984        struct object_id oid;
1985
1986        if (subdir_nr > 0xff)
1987                BUG("invalid loose object subdirectory: %x", subdir_nr);
1988
1989        origlen = path->len;
1990        strbuf_complete(path, '/');
1991        strbuf_addf(path, "%02x", subdir_nr);
1992
1993        dir = opendir(path->buf);
1994        if (!dir) {
1995                if (errno != ENOENT)
1996                        r = error_errno("unable to open %s", path->buf);
1997                strbuf_setlen(path, origlen);
1998                return r;
1999        }
2000
2001        oid.hash[0] = subdir_nr;
2002        strbuf_addch(path, '/');
2003        baselen = path->len;
2004
2005        while ((de = readdir(dir))) {
2006                size_t namelen;
2007                if (is_dot_or_dotdot(de->d_name))
2008                        continue;
2009
2010                namelen = strlen(de->d_name);
2011                strbuf_setlen(path, baselen);
2012                strbuf_add(path, de->d_name, namelen);
2013                if (namelen == GIT_SHA1_HEXSZ - 2 &&
2014                    !hex_to_bytes(oid.hash + 1, de->d_name,
2015                                  GIT_SHA1_RAWSZ - 1)) {
2016                        if (obj_cb) {
2017                                r = obj_cb(&oid, path->buf, data);
2018                                if (r)
2019                                        break;
2020                        }
2021                        continue;
2022                }
2023
2024                if (cruft_cb) {
2025                        r = cruft_cb(de->d_name, path->buf, data);
2026                        if (r)
2027                                break;
2028                }
2029        }
2030        closedir(dir);
2031
2032        strbuf_setlen(path, baselen - 1);
2033        if (!r && subdir_cb)
2034                r = subdir_cb(subdir_nr, path->buf, data);
2035
2036        strbuf_setlen(path, origlen);
2037
2038        return r;
2039}
2040
2041int for_each_loose_file_in_objdir_buf(struct strbuf *path,
2042                            each_loose_object_fn obj_cb,
2043                            each_loose_cruft_fn cruft_cb,
2044                            each_loose_subdir_fn subdir_cb,
2045                            void *data)
2046{
2047        int r = 0;
2048        int i;
2049
2050        for (i = 0; i < 256; i++) {
2051                r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
2052                                                subdir_cb, data);
2053                if (r)
2054                        break;
2055        }
2056
2057        return r;
2058}
2059
2060int for_each_loose_file_in_objdir(const char *path,
2061                                  each_loose_object_fn obj_cb,
2062                                  each_loose_cruft_fn cruft_cb,
2063                                  each_loose_subdir_fn subdir_cb,
2064                                  void *data)
2065{
2066        struct strbuf buf = STRBUF_INIT;
2067        int r;
2068
2069        strbuf_addstr(&buf, path);
2070        r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
2071                                              subdir_cb, data);
2072        strbuf_release(&buf);
2073
2074        return r;
2075}
2076
2077struct loose_alt_odb_data {
2078        each_loose_object_fn *cb;
2079        void *data;
2080};
2081
2082static int loose_from_alt_odb(struct alternate_object_database *alt,
2083                              void *vdata)
2084{
2085        struct loose_alt_odb_data *data = vdata;
2086        struct strbuf buf = STRBUF_INIT;
2087        int r;
2088
2089        strbuf_addstr(&buf, alt->path);
2090        r = for_each_loose_file_in_objdir_buf(&buf,
2091                                              data->cb, NULL, NULL,
2092                                              data->data);
2093        strbuf_release(&buf);
2094        return r;
2095}
2096
2097int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
2098{
2099        struct loose_alt_odb_data alt;
2100        int r;
2101
2102        r = for_each_loose_file_in_objdir(get_object_directory(),
2103                                          cb, NULL, NULL, data);
2104        if (r)
2105                return r;
2106
2107        if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
2108                return 0;
2109
2110        alt.cb = cb;
2111        alt.data = data;
2112        return foreach_alt_odb(loose_from_alt_odb, &alt);
2113}
2114
2115static int check_stream_sha1(git_zstream *stream,
2116                             const char *hdr,
2117                             unsigned long size,
2118                             const char *path,
2119                             const unsigned char *expected_sha1)
2120{
2121        git_SHA_CTX c;
2122        unsigned char real_sha1[GIT_MAX_RAWSZ];
2123        unsigned char buf[4096];
2124        unsigned long total_read;
2125        int status = Z_OK;
2126
2127        git_SHA1_Init(&c);
2128        git_SHA1_Update(&c, hdr, stream->total_out);
2129
2130        /*
2131         * We already read some bytes into hdr, but the ones up to the NUL
2132         * do not count against the object's content size.
2133         */
2134        total_read = stream->total_out - strlen(hdr) - 1;
2135
2136        /*
2137         * This size comparison must be "<=" to read the final zlib packets;
2138         * see the comment in unpack_sha1_rest for details.
2139         */
2140        while (total_read <= size &&
2141               (status == Z_OK || status == Z_BUF_ERROR)) {
2142                stream->next_out = buf;
2143                stream->avail_out = sizeof(buf);
2144                if (size - total_read < stream->avail_out)
2145                        stream->avail_out = size - total_read;
2146                status = git_inflate(stream, Z_FINISH);
2147                git_SHA1_Update(&c, buf, stream->next_out - buf);
2148                total_read += stream->next_out - buf;
2149        }
2150        git_inflate_end(stream);
2151
2152        if (status != Z_STREAM_END) {
2153                error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
2154                return -1;
2155        }
2156        if (stream->avail_in) {
2157                error("garbage at end of loose object '%s'",
2158                      sha1_to_hex(expected_sha1));
2159                return -1;
2160        }
2161
2162        git_SHA1_Final(real_sha1, &c);
2163        if (hashcmp(expected_sha1, real_sha1)) {
2164                error("sha1 mismatch for %s (expected %s)", path,
2165                      sha1_to_hex(expected_sha1));
2166                return -1;
2167        }
2168
2169        return 0;
2170}
2171
2172int read_loose_object(const char *path,
2173                      const unsigned char *expected_sha1,
2174                      enum object_type *type,
2175                      unsigned long *size,
2176                      void **contents)
2177{
2178        int ret = -1;
2179        void *map = NULL;
2180        unsigned long mapsize;
2181        git_zstream stream;
2182        char hdr[32];
2183
2184        *contents = NULL;
2185
2186        map = map_sha1_file_1(path, NULL, &mapsize);
2187        if (!map) {
2188                error_errno("unable to mmap %s", path);
2189                goto out;
2190        }
2191
2192        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
2193                error("unable to unpack header of %s", path);
2194                goto out;
2195        }
2196
2197        *type = parse_sha1_header(hdr, size);
2198        if (*type < 0) {
2199                error("unable to parse header of %s", path);
2200                git_inflate_end(&stream);
2201                goto out;
2202        }
2203
2204        if (*type == OBJ_BLOB) {
2205                if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
2206                        goto out;
2207        } else {
2208                *contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
2209                if (!*contents) {
2210                        error("unable to unpack contents of %s", path);
2211                        git_inflate_end(&stream);
2212                        goto out;
2213                }
2214                if (check_sha1_signature(expected_sha1, *contents,
2215                                         *size, typename(*type))) {
2216                        error("sha1 mismatch for %s (expected %s)", path,
2217                              sha1_to_hex(expected_sha1));
2218                        free(*contents);
2219                        goto out;
2220                }
2221        }
2222
2223        ret = 0; /* everything checks out */
2224
2225out:
2226        if (map)
2227                munmap(map, mapsize);
2228        return ret;
2229}