sha1_file.con commit Merge branch 'js/mingw-hooks-with-exe-suffix' (cddbda4)
   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 "string-list.h"
  11#include "lockfile.h"
  12#include "delta.h"
  13#include "pack.h"
  14#include "blob.h"
  15#include "commit.h"
  16#include "run-command.h"
  17#include "tag.h"
  18#include "tree.h"
  19#include "tree-walk.h"
  20#include "refs.h"
  21#include "pack-revindex.h"
  22#include "sha1-lookup.h"
  23#include "bulk-checkin.h"
  24#include "streaming.h"
  25#include "dir.h"
  26#include "mru.h"
  27#include "list.h"
  28#include "mergesort.h"
  29#include "quote.h"
  30
  31#define SZ_FMT PRIuMAX
  32static inline uintmax_t sz_fmt(size_t s) { return s; }
  33
  34const unsigned char null_sha1[20];
  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
  43/*
  44 * This is meant to hold a *small* number of objects that you would
  45 * want read_sha1_file() to be able to return, but yet you do not want
  46 * to write them into the object store (e.g. a browse-only
  47 * application).
  48 */
  49static struct cached_object {
  50        unsigned char sha1[20];
  51        enum object_type type;
  52        void *buf;
  53        unsigned long size;
  54} *cached_objects;
  55static int cached_object_nr, cached_object_alloc;
  56
  57static struct cached_object empty_tree = {
  58        EMPTY_TREE_SHA1_BIN_LITERAL,
  59        OBJ_TREE,
  60        "",
  61        0
  62};
  63
  64static struct cached_object *find_cached_object(const unsigned char *sha1)
  65{
  66        int i;
  67        struct cached_object *co = cached_objects;
  68
  69        for (i = 0; i < cached_object_nr; i++, co++) {
  70                if (!hashcmp(co->sha1, sha1))
  71                        return co;
  72        }
  73        if (!hashcmp(sha1, empty_tree.sha1))
  74                return &empty_tree;
  75        return NULL;
  76}
  77
  78int mkdir_in_gitdir(const char *path)
  79{
  80        if (mkdir(path, 0777)) {
  81                int saved_errno = errno;
  82                struct stat st;
  83                struct strbuf sb = STRBUF_INIT;
  84
  85                if (errno != EEXIST)
  86                        return -1;
  87                /*
  88                 * Are we looking at a path in a symlinked worktree
  89                 * whose original repository does not yet have it?
  90                 * e.g. .git/rr-cache pointing at its original
  91                 * repository in which the user hasn't performed any
  92                 * conflict resolution yet?
  93                 */
  94                if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
  95                    strbuf_readlink(&sb, path, st.st_size) ||
  96                    !is_absolute_path(sb.buf) ||
  97                    mkdir(sb.buf, 0777)) {
  98                        strbuf_release(&sb);
  99                        errno = saved_errno;
 100                        return -1;
 101                }
 102                strbuf_release(&sb);
 103        }
 104        return adjust_shared_perm(path);
 105}
 106
 107enum scld_error safe_create_leading_directories(char *path)
 108{
 109        char *next_component = path + offset_1st_component(path);
 110        enum scld_error ret = SCLD_OK;
 111
 112        while (ret == SCLD_OK && next_component) {
 113                struct stat st;
 114                char *slash = next_component, slash_character;
 115
 116                while (*slash && !is_dir_sep(*slash))
 117                        slash++;
 118
 119                if (!*slash)
 120                        break;
 121
 122                next_component = slash + 1;
 123                while (is_dir_sep(*next_component))
 124                        next_component++;
 125                if (!*next_component)
 126                        break;
 127
 128                slash_character = *slash;
 129                *slash = '\0';
 130                if (!stat(path, &st)) {
 131                        /* path exists */
 132                        if (!S_ISDIR(st.st_mode))
 133                                ret = SCLD_EXISTS;
 134                } else if (mkdir(path, 0777)) {
 135                        if (errno == EEXIST &&
 136                            !stat(path, &st) && S_ISDIR(st.st_mode))
 137                                ; /* somebody created it since we checked */
 138                        else if (errno == ENOENT)
 139                                /*
 140                                 * Either mkdir() failed because
 141                                 * somebody just pruned the containing
 142                                 * directory, or stat() failed because
 143                                 * the file that was in our way was
 144                                 * just removed.  Either way, inform
 145                                 * the caller that it might be worth
 146                                 * trying again:
 147                                 */
 148                                ret = SCLD_VANISHED;
 149                        else
 150                                ret = SCLD_FAILED;
 151                } else if (adjust_shared_perm(path)) {
 152                        ret = SCLD_PERMS;
 153                }
 154                *slash = slash_character;
 155        }
 156        return ret;
 157}
 158
 159enum scld_error safe_create_leading_directories_const(const char *path)
 160{
 161        /* path points to cache entries, so xstrdup before messing with it */
 162        char *buf = xstrdup(path);
 163        enum scld_error result = safe_create_leading_directories(buf);
 164        free(buf);
 165        return result;
 166}
 167
 168static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 169{
 170        int i;
 171        for (i = 0; i < 20; i++) {
 172                static char hex[] = "0123456789abcdef";
 173                unsigned int val = sha1[i];
 174                strbuf_addch(buf, hex[val >> 4]);
 175                strbuf_addch(buf, hex[val & 0xf]);
 176                if (!i)
 177                        strbuf_addch(buf, '/');
 178        }
 179}
 180
 181const char *sha1_file_name(const unsigned char *sha1)
 182{
 183        static struct strbuf buf = STRBUF_INIT;
 184
 185        strbuf_reset(&buf);
 186        strbuf_addf(&buf, "%s/", get_object_directory());
 187
 188        fill_sha1_path(&buf, sha1);
 189        return buf.buf;
 190}
 191
 192struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
 193{
 194        strbuf_setlen(&alt->scratch, alt->base_len);
 195        return &alt->scratch;
 196}
 197
 198static const char *alt_sha1_path(struct alternate_object_database *alt,
 199                                 const unsigned char *sha1)
 200{
 201        struct strbuf *buf = alt_scratch_buf(alt);
 202        fill_sha1_path(buf, sha1);
 203        return buf->buf;
 204}
 205
 206/*
 207 * Return the name of the pack or index file with the specified sha1
 208 * in its filename.  *base and *name are scratch space that must be
 209 * provided by the caller.  which should be "pack" or "idx".
 210 */
 211static char *sha1_get_pack_name(const unsigned char *sha1,
 212                                struct strbuf *buf,
 213                                const char *which)
 214{
 215        strbuf_reset(buf);
 216        strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
 217                    sha1_to_hex(sha1), which);
 218        return buf->buf;
 219}
 220
 221char *sha1_pack_name(const unsigned char *sha1)
 222{
 223        static struct strbuf buf = STRBUF_INIT;
 224        return sha1_get_pack_name(sha1, &buf, "pack");
 225}
 226
 227char *sha1_pack_index_name(const unsigned char *sha1)
 228{
 229        static struct strbuf buf = STRBUF_INIT;
 230        return sha1_get_pack_name(sha1, &buf, "idx");
 231}
 232
 233struct alternate_object_database *alt_odb_list;
 234static struct alternate_object_database **alt_odb_tail;
 235
 236/*
 237 * Return non-zero iff the path is usable as an alternate object database.
 238 */
 239static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
 240{
 241        struct alternate_object_database *alt;
 242
 243        /* Detect cases where alternate disappeared */
 244        if (!is_directory(path->buf)) {
 245                error("object directory %s does not exist; "
 246                      "check .git/objects/info/alternates.",
 247                      path->buf);
 248                return 0;
 249        }
 250
 251        /*
 252         * Prevent the common mistake of listing the same
 253         * thing twice, or object directory itself.
 254         */
 255        for (alt = alt_odb_list; alt; alt = alt->next) {
 256                if (!fspathcmp(path->buf, alt->path))
 257                        return 0;
 258        }
 259        if (!fspathcmp(path->buf, normalized_objdir))
 260                return 0;
 261
 262        return 1;
 263}
 264
 265/*
 266 * Prepare alternate object database registry.
 267 *
 268 * The variable alt_odb_list points at the list of struct
 269 * alternate_object_database.  The elements on this list come from
 270 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 271 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 272 * whose contents is similar to that environment variable but can be
 273 * LF separated.  Its base points at a statically allocated buffer that
 274 * contains "/the/directory/corresponding/to/.git/objects/...", while
 275 * its name points just after the slash at the end of ".git/objects/"
 276 * in the example above, and has enough space to hold 40-byte hex
 277 * SHA1, an extra slash for the first level indirection, and the
 278 * terminating NUL.
 279 */
 280static int link_alt_odb_entry(const char *entry, const char *relative_base,
 281        int depth, const char *normalized_objdir)
 282{
 283        struct alternate_object_database *ent;
 284        struct strbuf pathbuf = STRBUF_INIT;
 285
 286        if (!is_absolute_path(entry) && relative_base) {
 287                strbuf_realpath(&pathbuf, relative_base, 1);
 288                strbuf_addch(&pathbuf, '/');
 289        }
 290        strbuf_addstr(&pathbuf, entry);
 291
 292        if (strbuf_normalize_path(&pathbuf) < 0 && relative_base) {
 293                error("unable to normalize alternate object path: %s",
 294                      pathbuf.buf);
 295                strbuf_release(&pathbuf);
 296                return -1;
 297        }
 298
 299        /*
 300         * The trailing slash after the directory name is given by
 301         * this function at the end. Remove duplicates.
 302         */
 303        while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
 304                strbuf_setlen(&pathbuf, pathbuf.len - 1);
 305
 306        if (!alt_odb_usable(&pathbuf, normalized_objdir)) {
 307                strbuf_release(&pathbuf);
 308                return -1;
 309        }
 310
 311        ent = alloc_alt_odb(pathbuf.buf);
 312
 313        /* add the alternate entry */
 314        *alt_odb_tail = ent;
 315        alt_odb_tail = &(ent->next);
 316        ent->next = NULL;
 317
 318        /* recursively add alternates */
 319        read_info_alternates(pathbuf.buf, depth + 1);
 320
 321        strbuf_release(&pathbuf);
 322        return 0;
 323}
 324
 325static const char *parse_alt_odb_entry(const char *string,
 326                                       int sep,
 327                                       struct strbuf *out)
 328{
 329        const char *end;
 330
 331        strbuf_reset(out);
 332
 333        if (*string == '#') {
 334                /* comment; consume up to next separator */
 335                end = strchrnul(string, sep);
 336        } else if (*string == '"' && !unquote_c_style(out, string, &end)) {
 337                /*
 338                 * quoted path; unquote_c_style has copied the
 339                 * data for us and set "end". Broken quoting (e.g.,
 340                 * an entry that doesn't end with a quote) falls
 341                 * back to the unquoted case below.
 342                 */
 343        } else {
 344                /* normal, unquoted path */
 345                end = strchrnul(string, sep);
 346                strbuf_add(out, string, end - string);
 347        }
 348
 349        if (*end)
 350                end++;
 351        return end;
 352}
 353
 354static void link_alt_odb_entries(const char *alt, int len, int sep,
 355                                 const char *relative_base, int depth)
 356{
 357        struct strbuf objdirbuf = STRBUF_INIT;
 358        struct strbuf entry = STRBUF_INIT;
 359
 360        if (depth > 5) {
 361                error("%s: ignoring alternate object stores, nesting too deep.",
 362                                relative_base);
 363                return;
 364        }
 365
 366        strbuf_add_absolute_path(&objdirbuf, get_object_directory());
 367        if (strbuf_normalize_path(&objdirbuf) < 0)
 368                die("unable to normalize object directory: %s",
 369                    objdirbuf.buf);
 370
 371        while (*alt) {
 372                alt = parse_alt_odb_entry(alt, sep, &entry);
 373                if (!entry.len)
 374                        continue;
 375                link_alt_odb_entry(entry.buf, relative_base, depth, objdirbuf.buf);
 376        }
 377        strbuf_release(&entry);
 378        strbuf_release(&objdirbuf);
 379}
 380
 381void read_info_alternates(const char * relative_base, int depth)
 382{
 383        char *map;
 384        size_t mapsz;
 385        struct stat st;
 386        char *path;
 387        int fd;
 388
 389        path = xstrfmt("%s/info/alternates", relative_base);
 390        fd = git_open(path);
 391        free(path);
 392        if (fd < 0)
 393                return;
 394        if (fstat(fd, &st) || (st.st_size == 0)) {
 395                close(fd);
 396                return;
 397        }
 398        mapsz = xsize_t(st.st_size);
 399        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 400        close(fd);
 401
 402        link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
 403
 404        munmap(map, mapsz);
 405}
 406
 407struct alternate_object_database *alloc_alt_odb(const char *dir)
 408{
 409        struct alternate_object_database *ent;
 410
 411        FLEX_ALLOC_STR(ent, path, dir);
 412        strbuf_init(&ent->scratch, 0);
 413        strbuf_addf(&ent->scratch, "%s/", dir);
 414        ent->base_len = ent->scratch.len;
 415
 416        return ent;
 417}
 418
 419void add_to_alternates_file(const char *reference)
 420{
 421        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 422        char *alts = git_pathdup("objects/info/alternates");
 423        FILE *in, *out;
 424
 425        hold_lock_file_for_update(lock, alts, LOCK_DIE_ON_ERROR);
 426        out = fdopen_lock_file(lock, "w");
 427        if (!out)
 428                die_errno("unable to fdopen alternates lockfile");
 429
 430        in = fopen(alts, "r");
 431        if (in) {
 432                struct strbuf line = STRBUF_INIT;
 433                int found = 0;
 434
 435                while (strbuf_getline(&line, in) != EOF) {
 436                        if (!strcmp(reference, line.buf)) {
 437                                found = 1;
 438                                break;
 439                        }
 440                        fprintf_or_die(out, "%s\n", line.buf);
 441                }
 442
 443                strbuf_release(&line);
 444                fclose(in);
 445
 446                if (found) {
 447                        rollback_lock_file(lock);
 448                        lock = NULL;
 449                }
 450        }
 451        else if (errno != ENOENT)
 452                die_errno("unable to read alternates file");
 453
 454        if (lock) {
 455                fprintf_or_die(out, "%s\n", reference);
 456                if (commit_lock_file(lock))
 457                        die_errno("unable to move new alternates file into place");
 458                if (alt_odb_tail)
 459                        link_alt_odb_entries(reference, strlen(reference), '\n', NULL, 0);
 460        }
 461        free(alts);
 462}
 463
 464void add_to_alternates_memory(const char *reference)
 465{
 466        /*
 467         * Make sure alternates are initialized, or else our entry may be
 468         * overwritten when they are.
 469         */
 470        prepare_alt_odb();
 471
 472        link_alt_odb_entries(reference, strlen(reference), '\n', NULL, 0);
 473}
 474
 475/*
 476 * Compute the exact path an alternate is at and returns it. In case of
 477 * error NULL is returned and the human readable error is added to `err`
 478 * `path` may be relative and should point to $GITDIR.
 479 * `err` must not be null.
 480 */
 481char *compute_alternate_path(const char *path, struct strbuf *err)
 482{
 483        char *ref_git = NULL;
 484        const char *repo, *ref_git_s;
 485        int seen_error = 0;
 486
 487        ref_git_s = real_path_if_valid(path);
 488        if (!ref_git_s) {
 489                seen_error = 1;
 490                strbuf_addf(err, _("path '%s' does not exist"), path);
 491                goto out;
 492        } else
 493                /*
 494                 * Beware: read_gitfile(), real_path() and mkpath()
 495                 * return static buffer
 496                 */
 497                ref_git = xstrdup(ref_git_s);
 498
 499        repo = read_gitfile(ref_git);
 500        if (!repo)
 501                repo = read_gitfile(mkpath("%s/.git", ref_git));
 502        if (repo) {
 503                free(ref_git);
 504                ref_git = xstrdup(repo);
 505        }
 506
 507        if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
 508                char *ref_git_git = mkpathdup("%s/.git", ref_git);
 509                free(ref_git);
 510                ref_git = ref_git_git;
 511        } else if (!is_directory(mkpath("%s/objects", ref_git))) {
 512                struct strbuf sb = STRBUF_INIT;
 513                seen_error = 1;
 514                if (get_common_dir(&sb, ref_git)) {
 515                        strbuf_addf(err,
 516                                    _("reference repository '%s' as a linked "
 517                                      "checkout is not supported yet."),
 518                                    path);
 519                        goto out;
 520                }
 521
 522                strbuf_addf(err, _("reference repository '%s' is not a "
 523                                        "local repository."), path);
 524                goto out;
 525        }
 526
 527        if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
 528                strbuf_addf(err, _("reference repository '%s' is shallow"),
 529                            path);
 530                seen_error = 1;
 531                goto out;
 532        }
 533
 534        if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
 535                strbuf_addf(err,
 536                            _("reference repository '%s' is grafted"),
 537                            path);
 538                seen_error = 1;
 539                goto out;
 540        }
 541
 542out:
 543        if (seen_error) {
 544                free(ref_git);
 545                ref_git = NULL;
 546        }
 547
 548        return ref_git;
 549}
 550
 551int foreach_alt_odb(alt_odb_fn fn, void *cb)
 552{
 553        struct alternate_object_database *ent;
 554        int r = 0;
 555
 556        prepare_alt_odb();
 557        for (ent = alt_odb_list; ent; ent = ent->next) {
 558                r = fn(ent, cb);
 559                if (r)
 560                        break;
 561        }
 562        return r;
 563}
 564
 565void prepare_alt_odb(void)
 566{
 567        const char *alt;
 568
 569        if (alt_odb_tail)
 570                return;
 571
 572        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 573        if (!alt) alt = "";
 574
 575        alt_odb_tail = &alt_odb_list;
 576        link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
 577
 578        read_info_alternates(get_object_directory(), 0);
 579}
 580
 581/* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 582static int freshen_file(const char *fn)
 583{
 584        struct utimbuf t;
 585        t.actime = t.modtime = time(NULL);
 586        return !utime(fn, &t);
 587}
 588
 589/*
 590 * All of the check_and_freshen functions return 1 if the file exists and was
 591 * freshened (if freshening was requested), 0 otherwise. If they return
 592 * 0, you should not assume that it is safe to skip a write of the object (it
 593 * either does not exist on disk, or has a stale mtime and may be subject to
 594 * pruning).
 595 */
 596static int check_and_freshen_file(const char *fn, int freshen)
 597{
 598        if (access(fn, F_OK))
 599                return 0;
 600        if (freshen && !freshen_file(fn))
 601                return 0;
 602        return 1;
 603}
 604
 605static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 606{
 607        return check_and_freshen_file(sha1_file_name(sha1), freshen);
 608}
 609
 610static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 611{
 612        struct alternate_object_database *alt;
 613        prepare_alt_odb();
 614        for (alt = alt_odb_list; alt; alt = alt->next) {
 615                const char *path = alt_sha1_path(alt, sha1);
 616                if (check_and_freshen_file(path, freshen))
 617                        return 1;
 618        }
 619        return 0;
 620}
 621
 622static int check_and_freshen(const unsigned char *sha1, int freshen)
 623{
 624        return check_and_freshen_local(sha1, freshen) ||
 625               check_and_freshen_nonlocal(sha1, freshen);
 626}
 627
 628int has_loose_object_nonlocal(const unsigned char *sha1)
 629{
 630        return check_and_freshen_nonlocal(sha1, 0);
 631}
 632
 633static int has_loose_object(const unsigned char *sha1)
 634{
 635        return check_and_freshen(sha1, 0);
 636}
 637
 638static unsigned int pack_used_ctr;
 639static unsigned int pack_mmap_calls;
 640static unsigned int peak_pack_open_windows;
 641static unsigned int pack_open_windows;
 642static unsigned int pack_open_fds;
 643static unsigned int pack_max_fds;
 644static size_t peak_pack_mapped;
 645static size_t pack_mapped;
 646struct packed_git *packed_git;
 647
 648static struct mru packed_git_mru_storage;
 649struct mru *packed_git_mru = &packed_git_mru_storage;
 650
 651void pack_report(void)
 652{
 653        fprintf(stderr,
 654                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 655                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 656                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 657                sz_fmt(getpagesize()),
 658                sz_fmt(packed_git_window_size),
 659                sz_fmt(packed_git_limit));
 660        fprintf(stderr,
 661                "pack_report: pack_used_ctr            = %10u\n"
 662                "pack_report: pack_mmap_calls          = %10u\n"
 663                "pack_report: pack_open_windows        = %10u / %10u\n"
 664                "pack_report: pack_mapped              = "
 665                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 666                pack_used_ctr,
 667                pack_mmap_calls,
 668                pack_open_windows, peak_pack_open_windows,
 669                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 670}
 671
 672/*
 673 * Open and mmap the index file at path, perform a couple of
 674 * consistency checks, then record its information to p.  Return 0 on
 675 * success.
 676 */
 677static int check_packed_git_idx(const char *path, struct packed_git *p)
 678{
 679        void *idx_map;
 680        struct pack_idx_header *hdr;
 681        size_t idx_size;
 682        uint32_t version, nr, i, *index;
 683        int fd = git_open(path);
 684        struct stat st;
 685
 686        if (fd < 0)
 687                return -1;
 688        if (fstat(fd, &st)) {
 689                close(fd);
 690                return -1;
 691        }
 692        idx_size = xsize_t(st.st_size);
 693        if (idx_size < 4 * 256 + 20 + 20) {
 694                close(fd);
 695                return error("index file %s is too small", path);
 696        }
 697        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 698        close(fd);
 699
 700        hdr = idx_map;
 701        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 702                version = ntohl(hdr->idx_version);
 703                if (version < 2 || version > 2) {
 704                        munmap(idx_map, idx_size);
 705                        return error("index file %s is version %"PRIu32
 706                                     " and is not supported by this binary"
 707                                     " (try upgrading GIT to a newer version)",
 708                                     path, version);
 709                }
 710        } else
 711                version = 1;
 712
 713        nr = 0;
 714        index = idx_map;
 715        if (version > 1)
 716                index += 2;  /* skip index header */
 717        for (i = 0; i < 256; i++) {
 718                uint32_t n = ntohl(index[i]);
 719                if (n < nr) {
 720                        munmap(idx_map, idx_size);
 721                        return error("non-monotonic index %s", path);
 722                }
 723                nr = n;
 724        }
 725
 726        if (version == 1) {
 727                /*
 728                 * Total size:
 729                 *  - 256 index entries 4 bytes each
 730                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 731                 *  - 20-byte SHA1 of the packfile
 732                 *  - 20-byte SHA1 file checksum
 733                 */
 734                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 735                        munmap(idx_map, idx_size);
 736                        return error("wrong index v1 file size in %s", path);
 737                }
 738        } else if (version == 2) {
 739                /*
 740                 * Minimum size:
 741                 *  - 8 bytes of header
 742                 *  - 256 index entries 4 bytes each
 743                 *  - 20-byte sha1 entry * nr
 744                 *  - 4-byte crc entry * nr
 745                 *  - 4-byte offset entry * nr
 746                 *  - 20-byte SHA1 of the packfile
 747                 *  - 20-byte SHA1 file checksum
 748                 * And after the 4-byte offset table might be a
 749                 * variable sized table containing 8-byte entries
 750                 * for offsets larger than 2^31.
 751                 */
 752                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 753                unsigned long max_size = min_size;
 754                if (nr)
 755                        max_size += (nr - 1)*8;
 756                if (idx_size < min_size || idx_size > max_size) {
 757                        munmap(idx_map, idx_size);
 758                        return error("wrong index v2 file size in %s", path);
 759                }
 760                if (idx_size != min_size &&
 761                    /*
 762                     * make sure we can deal with large pack offsets.
 763                     * 31-bit signed offset won't be enough, neither
 764                     * 32-bit unsigned one will be.
 765                     */
 766                    (sizeof(off_t) <= 4)) {
 767                        munmap(idx_map, idx_size);
 768                        return error("pack too large for current definition of off_t in %s", path);
 769                }
 770        }
 771
 772        p->index_version = version;
 773        p->index_data = idx_map;
 774        p->index_size = idx_size;
 775        p->num_objects = nr;
 776        return 0;
 777}
 778
 779int open_pack_index(struct packed_git *p)
 780{
 781        char *idx_name;
 782        size_t len;
 783        int ret;
 784
 785        if (p->index_data)
 786                return 0;
 787
 788        if (!strip_suffix(p->pack_name, ".pack", &len))
 789                die("BUG: pack_name does not end in .pack");
 790        idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
 791        ret = check_packed_git_idx(idx_name, p);
 792        free(idx_name);
 793        return ret;
 794}
 795
 796static void scan_windows(struct packed_git *p,
 797        struct packed_git **lru_p,
 798        struct pack_window **lru_w,
 799        struct pack_window **lru_l)
 800{
 801        struct pack_window *w, *w_l;
 802
 803        for (w_l = NULL, w = p->windows; w; w = w->next) {
 804                if (!w->inuse_cnt) {
 805                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 806                                *lru_p = p;
 807                                *lru_w = w;
 808                                *lru_l = w_l;
 809                        }
 810                }
 811                w_l = w;
 812        }
 813}
 814
 815static int unuse_one_window(struct packed_git *current)
 816{
 817        struct packed_git *p, *lru_p = NULL;
 818        struct pack_window *lru_w = NULL, *lru_l = NULL;
 819
 820        if (current)
 821                scan_windows(current, &lru_p, &lru_w, &lru_l);
 822        for (p = packed_git; p; p = p->next)
 823                scan_windows(p, &lru_p, &lru_w, &lru_l);
 824        if (lru_p) {
 825                munmap(lru_w->base, lru_w->len);
 826                pack_mapped -= lru_w->len;
 827                if (lru_l)
 828                        lru_l->next = lru_w->next;
 829                else
 830                        lru_p->windows = lru_w->next;
 831                free(lru_w);
 832                pack_open_windows--;
 833                return 1;
 834        }
 835        return 0;
 836}
 837
 838void release_pack_memory(size_t need)
 839{
 840        size_t cur = pack_mapped;
 841        while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 842                ; /* nothing */
 843}
 844
 845static void mmap_limit_check(size_t length)
 846{
 847        static size_t limit = 0;
 848        if (!limit) {
 849                limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 850                if (!limit)
 851                        limit = SIZE_MAX;
 852        }
 853        if (length > limit)
 854                die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 855                    (uintmax_t)length, (uintmax_t)limit);
 856}
 857
 858void *xmmap_gently(void *start, size_t length,
 859                  int prot, int flags, int fd, off_t offset)
 860{
 861        void *ret;
 862
 863        mmap_limit_check(length);
 864        ret = mmap(start, length, prot, flags, fd, offset);
 865        if (ret == MAP_FAILED) {
 866                if (!length)
 867                        return NULL;
 868                release_pack_memory(length);
 869                ret = mmap(start, length, prot, flags, fd, offset);
 870        }
 871        return ret;
 872}
 873
 874void *xmmap(void *start, size_t length,
 875        int prot, int flags, int fd, off_t offset)
 876{
 877        void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 878        if (ret == MAP_FAILED)
 879                die_errno("mmap failed");
 880        return ret;
 881}
 882
 883void close_pack_windows(struct packed_git *p)
 884{
 885        while (p->windows) {
 886                struct pack_window *w = p->windows;
 887
 888                if (w->inuse_cnt)
 889                        die("pack '%s' still has open windows to it",
 890                            p->pack_name);
 891                munmap(w->base, w->len);
 892                pack_mapped -= w->len;
 893                pack_open_windows--;
 894                p->windows = w->next;
 895                free(w);
 896        }
 897}
 898
 899static int close_pack_fd(struct packed_git *p)
 900{
 901        if (p->pack_fd < 0)
 902                return 0;
 903
 904        close(p->pack_fd);
 905        pack_open_fds--;
 906        p->pack_fd = -1;
 907
 908        return 1;
 909}
 910
 911static void close_pack(struct packed_git *p)
 912{
 913        close_pack_windows(p);
 914        close_pack_fd(p);
 915        close_pack_index(p);
 916}
 917
 918void close_all_packs(void)
 919{
 920        struct packed_git *p;
 921
 922        for (p = packed_git; p; p = p->next)
 923                if (p->do_not_close)
 924                        die("BUG: want to close pack marked 'do-not-close'");
 925                else
 926                        close_pack(p);
 927}
 928
 929
 930/*
 931 * The LRU pack is the one with the oldest MRU window, preferring packs
 932 * with no used windows, or the oldest mtime if it has no windows allocated.
 933 */
 934static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 935{
 936        struct pack_window *w, *this_mru_w;
 937        int has_windows_inuse = 0;
 938
 939        /*
 940         * Reject this pack if it has windows and the previously selected
 941         * one does not.  If this pack does not have windows, reject
 942         * it if the pack file is newer than the previously selected one.
 943         */
 944        if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 945                return;
 946
 947        for (w = this_mru_w = p->windows; w; w = w->next) {
 948                /*
 949                 * Reject this pack if any of its windows are in use,
 950                 * but the previously selected pack did not have any
 951                 * inuse windows.  Otherwise, record that this pack
 952                 * has windows in use.
 953                 */
 954                if (w->inuse_cnt) {
 955                        if (*accept_windows_inuse)
 956                                has_windows_inuse = 1;
 957                        else
 958                                return;
 959                }
 960
 961                if (w->last_used > this_mru_w->last_used)
 962                        this_mru_w = w;
 963
 964                /*
 965                 * Reject this pack if it has windows that have been
 966                 * used more recently than the previously selected pack.
 967                 * If the previously selected pack had windows inuse and
 968                 * we have not encountered a window in this pack that is
 969                 * inuse, skip this check since we prefer a pack with no
 970                 * inuse windows to one that has inuse windows.
 971                 */
 972                if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 973                    this_mru_w->last_used > (*mru_w)->last_used)
 974                        return;
 975        }
 976
 977        /*
 978         * Select this pack.
 979         */
 980        *mru_w = this_mru_w;
 981        *lru_p = p;
 982        *accept_windows_inuse = has_windows_inuse;
 983}
 984
 985static int close_one_pack(void)
 986{
 987        struct packed_git *p, *lru_p = NULL;
 988        struct pack_window *mru_w = NULL;
 989        int accept_windows_inuse = 1;
 990
 991        for (p = packed_git; p; p = p->next) {
 992                if (p->pack_fd == -1)
 993                        continue;
 994                find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 995        }
 996
 997        if (lru_p)
 998                return close_pack_fd(lru_p);
 999
1000        return 0;
1001}
1002
1003void unuse_pack(struct pack_window **w_cursor)
1004{
1005        struct pack_window *w = *w_cursor;
1006        if (w) {
1007                w->inuse_cnt--;
1008                *w_cursor = NULL;
1009        }
1010}
1011
1012void close_pack_index(struct packed_git *p)
1013{
1014        if (p->index_data) {
1015                munmap((void *)p->index_data, p->index_size);
1016                p->index_data = NULL;
1017        }
1018}
1019
1020static unsigned int get_max_fd_limit(void)
1021{
1022#ifdef RLIMIT_NOFILE
1023        {
1024                struct rlimit lim;
1025
1026                if (!getrlimit(RLIMIT_NOFILE, &lim))
1027                        return lim.rlim_cur;
1028        }
1029#endif
1030
1031#ifdef _SC_OPEN_MAX
1032        {
1033                long open_max = sysconf(_SC_OPEN_MAX);
1034                if (0 < open_max)
1035                        return open_max;
1036                /*
1037                 * Otherwise, we got -1 for one of the two
1038                 * reasons:
1039                 *
1040                 * (1) sysconf() did not understand _SC_OPEN_MAX
1041                 *     and signaled an error with -1; or
1042                 * (2) sysconf() said there is no limit.
1043                 *
1044                 * We _could_ clear errno before calling sysconf() to
1045                 * tell these two cases apart and return a huge number
1046                 * in the latter case to let the caller cap it to a
1047                 * value that is not so selfish, but letting the
1048                 * fallback OPEN_MAX codepath take care of these cases
1049                 * is a lot simpler.
1050                 */
1051        }
1052#endif
1053
1054#ifdef OPEN_MAX
1055        return OPEN_MAX;
1056#else
1057        return 1; /* see the caller ;-) */
1058#endif
1059}
1060
1061/*
1062 * Do not call this directly as this leaks p->pack_fd on error return;
1063 * call open_packed_git() instead.
1064 */
1065static int open_packed_git_1(struct packed_git *p)
1066{
1067        struct stat st;
1068        struct pack_header hdr;
1069        unsigned char sha1[20];
1070        unsigned char *idx_sha1;
1071        long fd_flag;
1072
1073        if (!p->index_data && open_pack_index(p))
1074                return error("packfile %s index unavailable", p->pack_name);
1075
1076        if (!pack_max_fds) {
1077                unsigned int max_fds = get_max_fd_limit();
1078
1079                /* Save 3 for stdin/stdout/stderr, 22 for work */
1080                if (25 < max_fds)
1081                        pack_max_fds = max_fds - 25;
1082                else
1083                        pack_max_fds = 1;
1084        }
1085
1086        while (pack_max_fds <= pack_open_fds && close_one_pack())
1087                ; /* nothing */
1088
1089        p->pack_fd = git_open(p->pack_name);
1090        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
1091                return -1;
1092        pack_open_fds++;
1093
1094        /* If we created the struct before we had the pack we lack size. */
1095        if (!p->pack_size) {
1096                if (!S_ISREG(st.st_mode))
1097                        return error("packfile %s not a regular file", p->pack_name);
1098                p->pack_size = st.st_size;
1099        } else if (p->pack_size != st.st_size)
1100                return error("packfile %s size changed", p->pack_name);
1101
1102        /* We leave these file descriptors open with sliding mmap;
1103         * there is no point keeping them open across exec(), though.
1104         */
1105        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
1106        if (fd_flag < 0)
1107                return error("cannot determine file descriptor flags");
1108        fd_flag |= FD_CLOEXEC;
1109        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
1110                return error("cannot set FD_CLOEXEC");
1111
1112        /* Verify we recognize this pack file format. */
1113        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
1114                return error("file %s is far too short to be a packfile", p->pack_name);
1115        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
1116                return error("file %s is not a GIT packfile", p->pack_name);
1117        if (!pack_version_ok(hdr.hdr_version))
1118                return error("packfile %s is version %"PRIu32" and not"
1119                        " supported (try upgrading GIT to a newer version)",
1120                        p->pack_name, ntohl(hdr.hdr_version));
1121
1122        /* Verify the pack matches its index. */
1123        if (p->num_objects != ntohl(hdr.hdr_entries))
1124                return error("packfile %s claims to have %"PRIu32" objects"
1125                             " while index indicates %"PRIu32" objects",
1126                             p->pack_name, ntohl(hdr.hdr_entries),
1127                             p->num_objects);
1128        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
1129                return error("end of packfile %s is unavailable", p->pack_name);
1130        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
1131                return error("packfile %s signature is unavailable", p->pack_name);
1132        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
1133        if (hashcmp(sha1, idx_sha1))
1134                return error("packfile %s does not match index", p->pack_name);
1135        return 0;
1136}
1137
1138static int open_packed_git(struct packed_git *p)
1139{
1140        if (!open_packed_git_1(p))
1141                return 0;
1142        close_pack_fd(p);
1143        return -1;
1144}
1145
1146static int in_window(struct pack_window *win, off_t offset)
1147{
1148        /* We must promise at least 20 bytes (one hash) after the
1149         * offset is available from this window, otherwise the offset
1150         * is not actually in this window and a different window (which
1151         * has that one hash excess) must be used.  This is to support
1152         * the object header and delta base parsing routines below.
1153         */
1154        off_t win_off = win->offset;
1155        return win_off <= offset
1156                && (offset + 20) <= (win_off + win->len);
1157}
1158
1159unsigned char *use_pack(struct packed_git *p,
1160                struct pack_window **w_cursor,
1161                off_t offset,
1162                unsigned long *left)
1163{
1164        struct pack_window *win = *w_cursor;
1165
1166        /* Since packfiles end in a hash of their content and it's
1167         * pointless to ask for an offset into the middle of that
1168         * hash, and the in_window function above wouldn't match
1169         * don't allow an offset too close to the end of the file.
1170         */
1171        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
1172                die("packfile %s cannot be accessed", p->pack_name);
1173        if (offset > (p->pack_size - 20))
1174                die("offset beyond end of packfile (truncated pack?)");
1175        if (offset < 0)
1176                die(_("offset before end of packfile (broken .idx?)"));
1177
1178        if (!win || !in_window(win, offset)) {
1179                if (win)
1180                        win->inuse_cnt--;
1181                for (win = p->windows; win; win = win->next) {
1182                        if (in_window(win, offset))
1183                                break;
1184                }
1185                if (!win) {
1186                        size_t window_align = packed_git_window_size / 2;
1187                        off_t len;
1188
1189                        if (p->pack_fd == -1 && open_packed_git(p))
1190                                die("packfile %s cannot be accessed", p->pack_name);
1191
1192                        win = xcalloc(1, sizeof(*win));
1193                        win->offset = (offset / window_align) * window_align;
1194                        len = p->pack_size - win->offset;
1195                        if (len > packed_git_window_size)
1196                                len = packed_git_window_size;
1197                        win->len = (size_t)len;
1198                        pack_mapped += win->len;
1199                        while (packed_git_limit < pack_mapped
1200                                && unuse_one_window(p))
1201                                ; /* nothing */
1202                        win->base = xmmap(NULL, win->len,
1203                                PROT_READ, MAP_PRIVATE,
1204                                p->pack_fd, win->offset);
1205                        if (win->base == MAP_FAILED)
1206                                die_errno("packfile %s cannot be mapped",
1207                                          p->pack_name);
1208                        if (!win->offset && win->len == p->pack_size
1209                                && !p->do_not_close)
1210                                close_pack_fd(p);
1211                        pack_mmap_calls++;
1212                        pack_open_windows++;
1213                        if (pack_mapped > peak_pack_mapped)
1214                                peak_pack_mapped = pack_mapped;
1215                        if (pack_open_windows > peak_pack_open_windows)
1216                                peak_pack_open_windows = pack_open_windows;
1217                        win->next = p->windows;
1218                        p->windows = win;
1219                }
1220        }
1221        if (win != *w_cursor) {
1222                win->last_used = pack_used_ctr++;
1223                win->inuse_cnt++;
1224                *w_cursor = win;
1225        }
1226        offset -= win->offset;
1227        if (left)
1228                *left = win->len - xsize_t(offset);
1229        return win->base + offset;
1230}
1231
1232static struct packed_git *alloc_packed_git(int extra)
1233{
1234        struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
1235        memset(p, 0, sizeof(*p));
1236        p->pack_fd = -1;
1237        return p;
1238}
1239
1240static void try_to_free_pack_memory(size_t size)
1241{
1242        release_pack_memory(size);
1243}
1244
1245struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
1246{
1247        static int have_set_try_to_free_routine;
1248        struct stat st;
1249        size_t alloc;
1250        struct packed_git *p;
1251
1252        if (!have_set_try_to_free_routine) {
1253                have_set_try_to_free_routine = 1;
1254                set_try_to_free_routine(try_to_free_pack_memory);
1255        }
1256
1257        /*
1258         * Make sure a corresponding .pack file exists and that
1259         * the index looks sane.
1260         */
1261        if (!strip_suffix_mem(path, &path_len, ".idx"))
1262                return NULL;
1263
1264        /*
1265         * ".pack" is long enough to hold any suffix we're adding (and
1266         * the use xsnprintf double-checks that)
1267         */
1268        alloc = st_add3(path_len, strlen(".pack"), 1);
1269        p = alloc_packed_git(alloc);
1270        memcpy(p->pack_name, path, path_len);
1271
1272        xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
1273        if (!access(p->pack_name, F_OK))
1274                p->pack_keep = 1;
1275
1276        xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
1277        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
1278                free(p);
1279                return NULL;
1280        }
1281
1282        /* ok, it looks sane as far as we can check without
1283         * actually mapping the pack file.
1284         */
1285        p->pack_size = st.st_size;
1286        p->pack_local = local;
1287        p->mtime = st.st_mtime;
1288        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
1289                hashclr(p->sha1);
1290        return p;
1291}
1292
1293struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
1294{
1295        const char *path = sha1_pack_name(sha1);
1296        size_t alloc = st_add(strlen(path), 1);
1297        struct packed_git *p = alloc_packed_git(alloc);
1298
1299        memcpy(p->pack_name, path, alloc); /* includes NUL */
1300        hashcpy(p->sha1, sha1);
1301        if (check_packed_git_idx(idx_path, p)) {
1302                free(p);
1303                return NULL;
1304        }
1305
1306        return p;
1307}
1308
1309void install_packed_git(struct packed_git *pack)
1310{
1311        if (pack->pack_fd != -1)
1312                pack_open_fds++;
1313
1314        pack->next = packed_git;
1315        packed_git = pack;
1316}
1317
1318void (*report_garbage)(unsigned seen_bits, const char *path);
1319
1320static void report_helper(const struct string_list *list,
1321                          int seen_bits, int first, int last)
1322{
1323        if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
1324                return;
1325
1326        for (; first < last; first++)
1327                report_garbage(seen_bits, list->items[first].string);
1328}
1329
1330static void report_pack_garbage(struct string_list *list)
1331{
1332        int i, baselen = -1, first = 0, seen_bits = 0;
1333
1334        if (!report_garbage)
1335                return;
1336
1337        string_list_sort(list);
1338
1339        for (i = 0; i < list->nr; i++) {
1340                const char *path = list->items[i].string;
1341                if (baselen != -1 &&
1342                    strncmp(path, list->items[first].string, baselen)) {
1343                        report_helper(list, seen_bits, first, i);
1344                        baselen = -1;
1345                        seen_bits = 0;
1346                }
1347                if (baselen == -1) {
1348                        const char *dot = strrchr(path, '.');
1349                        if (!dot) {
1350                                report_garbage(PACKDIR_FILE_GARBAGE, path);
1351                                continue;
1352                        }
1353                        baselen = dot - path + 1;
1354                        first = i;
1355                }
1356                if (!strcmp(path + baselen, "pack"))
1357                        seen_bits |= 1;
1358                else if (!strcmp(path + baselen, "idx"))
1359                        seen_bits |= 2;
1360        }
1361        report_helper(list, seen_bits, first, list->nr);
1362}
1363
1364static void prepare_packed_git_one(char *objdir, int local)
1365{
1366        struct strbuf path = STRBUF_INIT;
1367        size_t dirnamelen;
1368        DIR *dir;
1369        struct dirent *de;
1370        struct string_list garbage = STRING_LIST_INIT_DUP;
1371
1372        strbuf_addstr(&path, objdir);
1373        strbuf_addstr(&path, "/pack");
1374        dir = opendir(path.buf);
1375        if (!dir) {
1376                if (errno != ENOENT)
1377                        error_errno("unable to open object pack directory: %s",
1378                                    path.buf);
1379                strbuf_release(&path);
1380                return;
1381        }
1382        strbuf_addch(&path, '/');
1383        dirnamelen = path.len;
1384        while ((de = readdir(dir)) != NULL) {
1385                struct packed_git *p;
1386                size_t base_len;
1387
1388                if (is_dot_or_dotdot(de->d_name))
1389                        continue;
1390
1391                strbuf_setlen(&path, dirnamelen);
1392                strbuf_addstr(&path, de->d_name);
1393
1394                base_len = path.len;
1395                if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
1396                        /* Don't reopen a pack we already have. */
1397                        for (p = packed_git; p; p = p->next) {
1398                                size_t len;
1399                                if (strip_suffix(p->pack_name, ".pack", &len) &&
1400                                    len == base_len &&
1401                                    !memcmp(p->pack_name, path.buf, len))
1402                                        break;
1403                        }
1404                        if (p == NULL &&
1405                            /*
1406                             * See if it really is a valid .idx file with
1407                             * corresponding .pack file that we can map.
1408                             */
1409                            (p = add_packed_git(path.buf, path.len, local)) != NULL)
1410                                install_packed_git(p);
1411                }
1412
1413                if (!report_garbage)
1414                        continue;
1415
1416                if (ends_with(de->d_name, ".idx") ||
1417                    ends_with(de->d_name, ".pack") ||
1418                    ends_with(de->d_name, ".bitmap") ||
1419                    ends_with(de->d_name, ".keep"))
1420                        string_list_append(&garbage, path.buf);
1421                else
1422                        report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
1423        }
1424        closedir(dir);
1425        report_pack_garbage(&garbage);
1426        string_list_clear(&garbage, 0);
1427        strbuf_release(&path);
1428}
1429
1430static int approximate_object_count_valid;
1431
1432/*
1433 * Give a fast, rough count of the number of objects in the repository. This
1434 * ignores loose objects completely. If you have a lot of them, then either
1435 * you should repack because your performance will be awful, or they are
1436 * all unreachable objects about to be pruned, in which case they're not really
1437 * interesting as a measure of repo size in the first place.
1438 */
1439unsigned long approximate_object_count(void)
1440{
1441        static unsigned long count;
1442        if (!approximate_object_count_valid) {
1443                struct packed_git *p;
1444
1445                prepare_packed_git();
1446                count = 0;
1447                for (p = packed_git; p; p = p->next) {
1448                        if (open_pack_index(p))
1449                                continue;
1450                        count += p->num_objects;
1451                }
1452        }
1453        return count;
1454}
1455
1456static void *get_next_packed_git(const void *p)
1457{
1458        return ((const struct packed_git *)p)->next;
1459}
1460
1461static void set_next_packed_git(void *p, void *next)
1462{
1463        ((struct packed_git *)p)->next = next;
1464}
1465
1466static int sort_pack(const void *a_, const void *b_)
1467{
1468        const struct packed_git *a = a_;
1469        const struct packed_git *b = b_;
1470        int st;
1471
1472        /*
1473         * Local packs tend to contain objects specific to our
1474         * variant of the project than remote ones.  In addition,
1475         * remote ones could be on a network mounted filesystem.
1476         * Favor local ones for these reasons.
1477         */
1478        st = a->pack_local - b->pack_local;
1479        if (st)
1480                return -st;
1481
1482        /*
1483         * Younger packs tend to contain more recent objects,
1484         * and more recent objects tend to get accessed more
1485         * often.
1486         */
1487        if (a->mtime < b->mtime)
1488                return 1;
1489        else if (a->mtime == b->mtime)
1490                return 0;
1491        return -1;
1492}
1493
1494static void rearrange_packed_git(void)
1495{
1496        packed_git = llist_mergesort(packed_git, get_next_packed_git,
1497                                     set_next_packed_git, sort_pack);
1498}
1499
1500static void prepare_packed_git_mru(void)
1501{
1502        struct packed_git *p;
1503
1504        mru_clear(packed_git_mru);
1505        for (p = packed_git; p; p = p->next)
1506                mru_append(packed_git_mru, p);
1507}
1508
1509static int prepare_packed_git_run_once = 0;
1510void prepare_packed_git(void)
1511{
1512        struct alternate_object_database *alt;
1513
1514        if (prepare_packed_git_run_once)
1515                return;
1516        prepare_packed_git_one(get_object_directory(), 1);
1517        prepare_alt_odb();
1518        for (alt = alt_odb_list; alt; alt = alt->next)
1519                prepare_packed_git_one(alt->path, 0);
1520        rearrange_packed_git();
1521        prepare_packed_git_mru();
1522        prepare_packed_git_run_once = 1;
1523}
1524
1525void reprepare_packed_git(void)
1526{
1527        approximate_object_count_valid = 0;
1528        prepare_packed_git_run_once = 0;
1529        prepare_packed_git();
1530}
1531
1532static void mark_bad_packed_object(struct packed_git *p,
1533                                   const unsigned char *sha1)
1534{
1535        unsigned i;
1536        for (i = 0; i < p->num_bad_objects; i++)
1537                if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
1538                        return;
1539        p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1540                                      st_mult(GIT_SHA1_RAWSZ,
1541                                              st_add(p->num_bad_objects, 1)));
1542        hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
1543        p->num_bad_objects++;
1544}
1545
1546static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1547{
1548        struct packed_git *p;
1549        unsigned i;
1550
1551        for (p = packed_git; p; p = p->next)
1552                for (i = 0; i < p->num_bad_objects; i++)
1553                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1554                                return p;
1555        return NULL;
1556}
1557
1558/*
1559 * With an in-core object data in "map", rehash it to make sure the
1560 * object name actually matches "sha1" to detect object corruption.
1561 * With "map" == NULL, try reading the object named with "sha1" using
1562 * the streaming interface and rehash it to do the same.
1563 */
1564int check_sha1_signature(const unsigned char *sha1, void *map,
1565                         unsigned long size, const char *type)
1566{
1567        unsigned char real_sha1[20];
1568        enum object_type obj_type;
1569        struct git_istream *st;
1570        git_SHA_CTX c;
1571        char hdr[32];
1572        int hdrlen;
1573
1574        if (map) {
1575                hash_sha1_file(map, size, type, real_sha1);
1576                return hashcmp(sha1, real_sha1) ? -1 : 0;
1577        }
1578
1579        st = open_istream(sha1, &obj_type, &size, NULL);
1580        if (!st)
1581                return -1;
1582
1583        /* Generate the header */
1584        hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(obj_type), size) + 1;
1585
1586        /* Sha1.. */
1587        git_SHA1_Init(&c);
1588        git_SHA1_Update(&c, hdr, hdrlen);
1589        for (;;) {
1590                char buf[1024 * 16];
1591                ssize_t readlen = read_istream(st, buf, sizeof(buf));
1592
1593                if (readlen < 0) {
1594                        close_istream(st);
1595                        return -1;
1596                }
1597                if (!readlen)
1598                        break;
1599                git_SHA1_Update(&c, buf, readlen);
1600        }
1601        git_SHA1_Final(real_sha1, &c);
1602        close_istream(st);
1603        return hashcmp(sha1, real_sha1) ? -1 : 0;
1604}
1605
1606int git_open_cloexec(const char *name, int flags)
1607{
1608        int fd;
1609        static int o_cloexec = O_CLOEXEC;
1610
1611        fd = open(name, flags | o_cloexec);
1612        if ((o_cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
1613                /* Try again w/o O_CLOEXEC: the kernel might not support it */
1614                o_cloexec &= ~O_CLOEXEC;
1615                fd = open(name, flags | o_cloexec);
1616        }
1617
1618#if defined(F_GETFL) && defined(F_SETFL) && defined(FD_CLOEXEC)
1619        {
1620                static int fd_cloexec = FD_CLOEXEC;
1621
1622                if (!o_cloexec && 0 <= fd && fd_cloexec) {
1623                        /* Opened w/o O_CLOEXEC?  try with fcntl(2) to add it */
1624                        int flags = fcntl(fd, F_GETFL);
1625                        if (fcntl(fd, F_SETFL, flags | fd_cloexec))
1626                                fd_cloexec = 0;
1627                }
1628        }
1629#endif
1630        return fd;
1631}
1632
1633/*
1634 * Find "sha1" as a loose object in the local repository or in an alternate.
1635 * Returns 0 on success, negative on failure.
1636 *
1637 * The "path" out-parameter will give the path of the object we found (if any).
1638 * Note that it may point to static storage and is only valid until another
1639 * call to sha1_file_name(), etc.
1640 */
1641static int stat_sha1_file(const unsigned char *sha1, struct stat *st,
1642                          const char **path)
1643{
1644        struct alternate_object_database *alt;
1645
1646        *path = sha1_file_name(sha1);
1647        if (!lstat(*path, st))
1648                return 0;
1649
1650        prepare_alt_odb();
1651        errno = ENOENT;
1652        for (alt = alt_odb_list; alt; alt = alt->next) {
1653                *path = alt_sha1_path(alt, sha1);
1654                if (!lstat(*path, st))
1655                        return 0;
1656        }
1657
1658        return -1;
1659}
1660
1661/*
1662 * Like stat_sha1_file(), but actually open the object and return the
1663 * descriptor. See the caveats on the "path" parameter above.
1664 */
1665static int open_sha1_file(const unsigned char *sha1, const char **path)
1666{
1667        int fd;
1668        struct alternate_object_database *alt;
1669        int most_interesting_errno;
1670
1671        *path = sha1_file_name(sha1);
1672        fd = git_open(*path);
1673        if (fd >= 0)
1674                return fd;
1675        most_interesting_errno = errno;
1676
1677        prepare_alt_odb();
1678        for (alt = alt_odb_list; alt; alt = alt->next) {
1679                *path = alt_sha1_path(alt, sha1);
1680                fd = git_open(*path);
1681                if (fd >= 0)
1682                        return fd;
1683                if (most_interesting_errno == ENOENT)
1684                        most_interesting_errno = errno;
1685        }
1686        errno = most_interesting_errno;
1687        return -1;
1688}
1689
1690/*
1691 * Map the loose object at "path" if it is not NULL, or the path found by
1692 * searching for a loose object named "sha1".
1693 */
1694static void *map_sha1_file_1(const char *path,
1695                             const unsigned char *sha1,
1696                             unsigned long *size)
1697{
1698        void *map;
1699        int fd;
1700
1701        if (path)
1702                fd = git_open(path);
1703        else
1704                fd = open_sha1_file(sha1, &path);
1705        map = NULL;
1706        if (fd >= 0) {
1707                struct stat st;
1708
1709                if (!fstat(fd, &st)) {
1710                        *size = xsize_t(st.st_size);
1711                        if (!*size) {
1712                                /* mmap() is forbidden on empty files */
1713                                error("object file %s is empty", path);
1714                                return NULL;
1715                        }
1716                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1717                }
1718                close(fd);
1719        }
1720        return map;
1721}
1722
1723void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1724{
1725        return map_sha1_file_1(NULL, sha1, size);
1726}
1727
1728unsigned long unpack_object_header_buffer(const unsigned char *buf,
1729                unsigned long len, enum object_type *type, unsigned long *sizep)
1730{
1731        unsigned shift;
1732        unsigned long size, c;
1733        unsigned long used = 0;
1734
1735        c = buf[used++];
1736        *type = (c >> 4) & 7;
1737        size = c & 15;
1738        shift = 4;
1739        while (c & 0x80) {
1740                if (len <= used || bitsizeof(long) <= shift) {
1741                        error("bad object header");
1742                        size = used = 0;
1743                        break;
1744                }
1745                c = buf[used++];
1746                size += (c & 0x7f) << shift;
1747                shift += 7;
1748        }
1749        *sizep = size;
1750        return used;
1751}
1752
1753static int unpack_sha1_short_header(git_zstream *stream,
1754                                    unsigned char *map, unsigned long mapsize,
1755                                    void *buffer, unsigned long bufsiz)
1756{
1757        /* Get the data stream */
1758        memset(stream, 0, sizeof(*stream));
1759        stream->next_in = map;
1760        stream->avail_in = mapsize;
1761        stream->next_out = buffer;
1762        stream->avail_out = bufsiz;
1763
1764        git_inflate_init(stream);
1765        return git_inflate(stream, 0);
1766}
1767
1768int unpack_sha1_header(git_zstream *stream,
1769                       unsigned char *map, unsigned long mapsize,
1770                       void *buffer, unsigned long bufsiz)
1771{
1772        int status = unpack_sha1_short_header(stream, map, mapsize,
1773                                              buffer, bufsiz);
1774
1775        if (status < Z_OK)
1776                return status;
1777
1778        /* Make sure we have the terminating NUL */
1779        if (!memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1780                return -1;
1781        return 0;
1782}
1783
1784static int unpack_sha1_header_to_strbuf(git_zstream *stream, unsigned char *map,
1785                                        unsigned long mapsize, void *buffer,
1786                                        unsigned long bufsiz, struct strbuf *header)
1787{
1788        int status;
1789
1790        status = unpack_sha1_short_header(stream, map, mapsize, buffer, bufsiz);
1791        if (status < Z_OK)
1792                return -1;
1793
1794        /*
1795         * Check if entire header is unpacked in the first iteration.
1796         */
1797        if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1798                return 0;
1799
1800        /*
1801         * buffer[0..bufsiz] was not large enough.  Copy the partial
1802         * result out to header, and then append the result of further
1803         * reading the stream.
1804         */
1805        strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1806        stream->next_out = buffer;
1807        stream->avail_out = bufsiz;
1808
1809        do {
1810                status = git_inflate(stream, 0);
1811                strbuf_add(header, buffer, stream->next_out - (unsigned char *)buffer);
1812                if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
1813                        return 0;
1814                stream->next_out = buffer;
1815                stream->avail_out = bufsiz;
1816        } while (status != Z_STREAM_END);
1817        return -1;
1818}
1819
1820static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1821{
1822        int bytes = strlen(buffer) + 1;
1823        unsigned char *buf = xmallocz(size);
1824        unsigned long n;
1825        int status = Z_OK;
1826
1827        n = stream->total_out - bytes;
1828        if (n > size)
1829                n = size;
1830        memcpy(buf, (char *) buffer + bytes, n);
1831        bytes = n;
1832        if (bytes <= size) {
1833                /*
1834                 * The above condition must be (bytes <= size), not
1835                 * (bytes < size).  In other words, even though we
1836                 * expect no more output and set avail_out to zero,
1837                 * the input zlib stream may have bytes that express
1838                 * "this concludes the stream", and we *do* want to
1839                 * eat that input.
1840                 *
1841                 * Otherwise we would not be able to test that we
1842                 * consumed all the input to reach the expected size;
1843                 * we also want to check that zlib tells us that all
1844                 * went well with status == Z_STREAM_END at the end.
1845                 */
1846                stream->next_out = buf + bytes;
1847                stream->avail_out = size - bytes;
1848                while (status == Z_OK)
1849                        status = git_inflate(stream, Z_FINISH);
1850        }
1851        if (status == Z_STREAM_END && !stream->avail_in) {
1852                git_inflate_end(stream);
1853                return buf;
1854        }
1855
1856        if (status < 0)
1857                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1858        else if (stream->avail_in)
1859                error("garbage at end of loose object '%s'",
1860                      sha1_to_hex(sha1));
1861        free(buf);
1862        return NULL;
1863}
1864
1865/*
1866 * We used to just use "sscanf()", but that's actually way
1867 * too permissive for what we want to check. So do an anal
1868 * object header parse by hand.
1869 */
1870static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
1871                               unsigned int flags)
1872{
1873        const char *type_buf = hdr;
1874        unsigned long size;
1875        int type, type_len = 0;
1876
1877        /*
1878         * The type can be of any size but is followed by
1879         * a space.
1880         */
1881        for (;;) {
1882                char c = *hdr++;
1883                if (!c)
1884                        return -1;
1885                if (c == ' ')
1886                        break;
1887                type_len++;
1888        }
1889
1890        type = type_from_string_gently(type_buf, type_len, 1);
1891        if (oi->typename)
1892                strbuf_add(oi->typename, type_buf, type_len);
1893        /*
1894         * Set type to 0 if its an unknown object and
1895         * we're obtaining the type using '--allow-unknown-type'
1896         * option.
1897         */
1898        if ((flags & LOOKUP_UNKNOWN_OBJECT) && (type < 0))
1899                type = 0;
1900        else if (type < 0)
1901                die("invalid object type");
1902        if (oi->typep)
1903                *oi->typep = type;
1904
1905        /*
1906         * The length must follow immediately, and be in canonical
1907         * decimal format (ie "010" is not valid).
1908         */
1909        size = *hdr++ - '0';
1910        if (size > 9)
1911                return -1;
1912        if (size) {
1913                for (;;) {
1914                        unsigned long c = *hdr - '0';
1915                        if (c > 9)
1916                                break;
1917                        hdr++;
1918                        size = size * 10 + c;
1919                }
1920        }
1921
1922        if (oi->sizep)
1923                *oi->sizep = size;
1924
1925        /*
1926         * The length must be followed by a zero byte
1927         */
1928        return *hdr ? -1 : type;
1929}
1930
1931int parse_sha1_header(const char *hdr, unsigned long *sizep)
1932{
1933        struct object_info oi = OBJECT_INFO_INIT;
1934
1935        oi.sizep = sizep;
1936        return parse_sha1_header_extended(hdr, &oi, LOOKUP_REPLACE_OBJECT);
1937}
1938
1939static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1940{
1941        int ret;
1942        git_zstream stream;
1943        char hdr[8192];
1944
1945        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1946        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1947                return NULL;
1948
1949        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1950}
1951
1952unsigned long get_size_from_delta(struct packed_git *p,
1953                                  struct pack_window **w_curs,
1954                                  off_t curpos)
1955{
1956        const unsigned char *data;
1957        unsigned char delta_head[20], *in;
1958        git_zstream stream;
1959        int st;
1960
1961        memset(&stream, 0, sizeof(stream));
1962        stream.next_out = delta_head;
1963        stream.avail_out = sizeof(delta_head);
1964
1965        git_inflate_init(&stream);
1966        do {
1967                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1968                stream.next_in = in;
1969                st = git_inflate(&stream, Z_FINISH);
1970                curpos += stream.next_in - in;
1971        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1972                 stream.total_out < sizeof(delta_head));
1973        git_inflate_end(&stream);
1974        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1975                error("delta data unpack-initial failed");
1976                return 0;
1977        }
1978
1979        /* Examine the initial part of the delta to figure out
1980         * the result size.
1981         */
1982        data = delta_head;
1983
1984        /* ignore base size */
1985        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1986
1987        /* Read the result size */
1988        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1989}
1990
1991static off_t get_delta_base(struct packed_git *p,
1992                                    struct pack_window **w_curs,
1993                                    off_t *curpos,
1994                                    enum object_type type,
1995                                    off_t delta_obj_offset)
1996{
1997        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1998        off_t base_offset;
1999
2000        /* use_pack() assured us we have [base_info, base_info + 20)
2001         * as a range that we can look at without walking off the
2002         * end of the mapped window.  Its actually the hash size
2003         * that is assured.  An OFS_DELTA longer than the hash size
2004         * is stupid, as then a REF_DELTA would be smaller to store.
2005         */
2006        if (type == OBJ_OFS_DELTA) {
2007                unsigned used = 0;
2008                unsigned char c = base_info[used++];
2009                base_offset = c & 127;
2010                while (c & 128) {
2011                        base_offset += 1;
2012                        if (!base_offset || MSB(base_offset, 7))
2013                                return 0;  /* overflow */
2014                        c = base_info[used++];
2015                        base_offset = (base_offset << 7) + (c & 127);
2016                }
2017                base_offset = delta_obj_offset - base_offset;
2018                if (base_offset <= 0 || base_offset >= delta_obj_offset)
2019                        return 0;  /* out of bound */
2020                *curpos += used;
2021        } else if (type == OBJ_REF_DELTA) {
2022                /* The base entry _must_ be in the same pack */
2023                base_offset = find_pack_entry_one(base_info, p);
2024                *curpos += 20;
2025        } else
2026                die("I am totally screwed");
2027        return base_offset;
2028}
2029
2030/*
2031 * Like get_delta_base above, but we return the sha1 instead of the pack
2032 * offset. This means it is cheaper for REF deltas (we do not have to do
2033 * the final object lookup), but more expensive for OFS deltas (we
2034 * have to load the revidx to convert the offset back into a sha1).
2035 */
2036static const unsigned char *get_delta_base_sha1(struct packed_git *p,
2037                                                struct pack_window **w_curs,
2038                                                off_t curpos,
2039                                                enum object_type type,
2040                                                off_t delta_obj_offset)
2041{
2042        if (type == OBJ_REF_DELTA) {
2043                unsigned char *base = use_pack(p, w_curs, curpos, NULL);
2044                return base;
2045        } else if (type == OBJ_OFS_DELTA) {
2046                struct revindex_entry *revidx;
2047                off_t base_offset = get_delta_base(p, w_curs, &curpos,
2048                                                   type, delta_obj_offset);
2049
2050                if (!base_offset)
2051                        return NULL;
2052
2053                revidx = find_pack_revindex(p, base_offset);
2054                if (!revidx)
2055                        return NULL;
2056
2057                return nth_packed_object_sha1(p, revidx->nr);
2058        } else
2059                return NULL;
2060}
2061
2062int unpack_object_header(struct packed_git *p,
2063                         struct pack_window **w_curs,
2064                         off_t *curpos,
2065                         unsigned long *sizep)
2066{
2067        unsigned char *base;
2068        unsigned long left;
2069        unsigned long used;
2070        enum object_type type;
2071
2072        /* use_pack() assures us we have [base, base + 20) available
2073         * as a range that we can look at.  (Its actually the hash
2074         * size that is assured.)  With our object header encoding
2075         * the maximum deflated object size is 2^137, which is just
2076         * insane, so we know won't exceed what we have been given.
2077         */
2078        base = use_pack(p, w_curs, *curpos, &left);
2079        used = unpack_object_header_buffer(base, left, &type, sizep);
2080        if (!used) {
2081                type = OBJ_BAD;
2082        } else
2083                *curpos += used;
2084
2085        return type;
2086}
2087
2088static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
2089{
2090        int type;
2091        struct revindex_entry *revidx;
2092        const unsigned char *sha1;
2093        revidx = find_pack_revindex(p, obj_offset);
2094        if (!revidx)
2095                return OBJ_BAD;
2096        sha1 = nth_packed_object_sha1(p, revidx->nr);
2097        mark_bad_packed_object(p, sha1);
2098        type = sha1_object_info(sha1, NULL);
2099        if (type <= OBJ_NONE)
2100                return OBJ_BAD;
2101        return type;
2102}
2103
2104#define POI_STACK_PREALLOC 64
2105
2106static enum object_type packed_to_object_type(struct packed_git *p,
2107                                              off_t obj_offset,
2108                                              enum object_type type,
2109                                              struct pack_window **w_curs,
2110                                              off_t curpos)
2111{
2112        off_t small_poi_stack[POI_STACK_PREALLOC];
2113        off_t *poi_stack = small_poi_stack;
2114        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
2115
2116        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
2117                off_t base_offset;
2118                unsigned long size;
2119                /* Push the object we're going to leave behind */
2120                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
2121                        poi_stack_alloc = alloc_nr(poi_stack_nr);
2122                        ALLOC_ARRAY(poi_stack, poi_stack_alloc);
2123                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
2124                } else {
2125                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
2126                }
2127                poi_stack[poi_stack_nr++] = obj_offset;
2128                /* If parsing the base offset fails, just unwind */
2129                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
2130                if (!base_offset)
2131                        goto unwind;
2132                curpos = obj_offset = base_offset;
2133                type = unpack_object_header(p, w_curs, &curpos, &size);
2134                if (type <= OBJ_NONE) {
2135                        /* If getting the base itself fails, we first
2136                         * retry the base, otherwise unwind */
2137                        type = retry_bad_packed_offset(p, base_offset);
2138                        if (type > OBJ_NONE)
2139                                goto out;
2140                        goto unwind;
2141                }
2142        }
2143
2144        switch (type) {
2145        case OBJ_BAD:
2146        case OBJ_COMMIT:
2147        case OBJ_TREE:
2148        case OBJ_BLOB:
2149        case OBJ_TAG:
2150                break;
2151        default:
2152                error("unknown object type %i at offset %"PRIuMAX" in %s",
2153                      type, (uintmax_t)obj_offset, p->pack_name);
2154                type = OBJ_BAD;
2155        }
2156
2157out:
2158        if (poi_stack != small_poi_stack)
2159                free(poi_stack);
2160        return type;
2161
2162unwind:
2163        while (poi_stack_nr) {
2164                obj_offset = poi_stack[--poi_stack_nr];
2165                type = retry_bad_packed_offset(p, obj_offset);
2166                if (type > OBJ_NONE)
2167                        goto out;
2168        }
2169        type = OBJ_BAD;
2170        goto out;
2171}
2172
2173int packed_object_info(struct packed_git *p, off_t obj_offset,
2174                       struct object_info *oi)
2175{
2176        struct pack_window *w_curs = NULL;
2177        unsigned long size;
2178        off_t curpos = obj_offset;
2179        enum object_type type;
2180
2181        /*
2182         * We always get the representation type, but only convert it to
2183         * a "real" type later if the caller is interested.
2184         */
2185        type = unpack_object_header(p, &w_curs, &curpos, &size);
2186
2187        if (oi->sizep) {
2188                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
2189                        off_t tmp_pos = curpos;
2190                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
2191                                                           type, obj_offset);
2192                        if (!base_offset) {
2193                                type = OBJ_BAD;
2194                                goto out;
2195                        }
2196                        *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
2197                        if (*oi->sizep == 0) {
2198                                type = OBJ_BAD;
2199                                goto out;
2200                        }
2201                } else {
2202                        *oi->sizep = size;
2203                }
2204        }
2205
2206        if (oi->disk_sizep) {
2207                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2208                *oi->disk_sizep = revidx[1].offset - obj_offset;
2209        }
2210
2211        if (oi->typep) {
2212                *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
2213                if (*oi->typep < 0) {
2214                        type = OBJ_BAD;
2215                        goto out;
2216                }
2217        }
2218
2219        if (oi->delta_base_sha1) {
2220                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
2221                        const unsigned char *base;
2222
2223                        base = get_delta_base_sha1(p, &w_curs, curpos,
2224                                                   type, obj_offset);
2225                        if (!base) {
2226                                type = OBJ_BAD;
2227                                goto out;
2228                        }
2229
2230                        hashcpy(oi->delta_base_sha1, base);
2231                } else
2232                        hashclr(oi->delta_base_sha1);
2233        }
2234
2235out:
2236        unuse_pack(&w_curs);
2237        return type;
2238}
2239
2240static void *unpack_compressed_entry(struct packed_git *p,
2241                                    struct pack_window **w_curs,
2242                                    off_t curpos,
2243                                    unsigned long size)
2244{
2245        int st;
2246        git_zstream stream;
2247        unsigned char *buffer, *in;
2248
2249        buffer = xmallocz_gently(size);
2250        if (!buffer)
2251                return NULL;
2252        memset(&stream, 0, sizeof(stream));
2253        stream.next_out = buffer;
2254        stream.avail_out = size + 1;
2255
2256        git_inflate_init(&stream);
2257        do {
2258                in = use_pack(p, w_curs, curpos, &stream.avail_in);
2259                stream.next_in = in;
2260                st = git_inflate(&stream, Z_FINISH);
2261                if (!stream.avail_out)
2262                        break; /* the payload is larger than it should be */
2263                curpos += stream.next_in - in;
2264        } while (st == Z_OK || st == Z_BUF_ERROR);
2265        git_inflate_end(&stream);
2266        if ((st != Z_STREAM_END) || stream.total_out != size) {
2267                free(buffer);
2268                return NULL;
2269        }
2270
2271        return buffer;
2272}
2273
2274static struct hashmap delta_base_cache;
2275static size_t delta_base_cached;
2276
2277static LIST_HEAD(delta_base_cache_lru);
2278
2279struct delta_base_cache_key {
2280        struct packed_git *p;
2281        off_t base_offset;
2282};
2283
2284struct delta_base_cache_entry {
2285        struct hashmap hash;
2286        struct delta_base_cache_key key;
2287        struct list_head lru;
2288        void *data;
2289        unsigned long size;
2290        enum object_type type;
2291};
2292
2293static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
2294{
2295        unsigned int hash;
2296
2297        hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
2298        hash += (hash >> 8) + (hash >> 16);
2299        return hash;
2300}
2301
2302static struct delta_base_cache_entry *
2303get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
2304{
2305        struct hashmap_entry entry;
2306        struct delta_base_cache_key key;
2307
2308        if (!delta_base_cache.cmpfn)
2309                return NULL;
2310
2311        hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
2312        key.p = p;
2313        key.base_offset = base_offset;
2314        return hashmap_get(&delta_base_cache, &entry, &key);
2315}
2316
2317static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
2318                                   const struct delta_base_cache_key *b)
2319{
2320        return a->p == b->p && a->base_offset == b->base_offset;
2321}
2322
2323static int delta_base_cache_hash_cmp(const void *va, const void *vb,
2324                                     const void *vkey)
2325{
2326        const struct delta_base_cache_entry *a = va, *b = vb;
2327        const struct delta_base_cache_key *key = vkey;
2328        if (key)
2329                return !delta_base_cache_key_eq(&a->key, key);
2330        else
2331                return !delta_base_cache_key_eq(&a->key, &b->key);
2332}
2333
2334static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
2335{
2336        return !!get_delta_base_cache_entry(p, base_offset);
2337}
2338
2339/*
2340 * Remove the entry from the cache, but do _not_ free the associated
2341 * entry data. The caller takes ownership of the "data" buffer, and
2342 * should copy out any fields it wants before detaching.
2343 */
2344static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
2345{
2346        hashmap_remove(&delta_base_cache, ent, &ent->key);
2347        list_del(&ent->lru);
2348        delta_base_cached -= ent->size;
2349        free(ent);
2350}
2351
2352static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
2353        unsigned long *base_size, enum object_type *type)
2354{
2355        struct delta_base_cache_entry *ent;
2356
2357        ent = get_delta_base_cache_entry(p, base_offset);
2358        if (!ent)
2359                return unpack_entry(p, base_offset, type, base_size);
2360
2361        *type = ent->type;
2362        *base_size = ent->size;
2363        return xmemdupz(ent->data, ent->size);
2364}
2365
2366static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
2367{
2368        free(ent->data);
2369        detach_delta_base_cache_entry(ent);
2370}
2371
2372void clear_delta_base_cache(void)
2373{
2374        struct list_head *lru, *tmp;
2375        list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
2376                struct delta_base_cache_entry *entry =
2377                        list_entry(lru, struct delta_base_cache_entry, lru);
2378                release_delta_base_cache(entry);
2379        }
2380}
2381
2382static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
2383        void *base, unsigned long base_size, enum object_type type)
2384{
2385        struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
2386        struct list_head *lru, *tmp;
2387
2388        delta_base_cached += base_size;
2389
2390        list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
2391                struct delta_base_cache_entry *f =
2392                        list_entry(lru, struct delta_base_cache_entry, lru);
2393                if (delta_base_cached <= delta_base_cache_limit)
2394                        break;
2395                release_delta_base_cache(f);
2396        }
2397
2398        ent->key.p = p;
2399        ent->key.base_offset = base_offset;
2400        ent->type = type;
2401        ent->data = base;
2402        ent->size = base_size;
2403        list_add_tail(&ent->lru, &delta_base_cache_lru);
2404
2405        if (!delta_base_cache.cmpfn)
2406                hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, 0);
2407        hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
2408        hashmap_add(&delta_base_cache, ent);
2409}
2410
2411static void *read_object(const unsigned char *sha1, enum object_type *type,
2412                         unsigned long *size);
2413
2414static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
2415{
2416        static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
2417        trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
2418                         p->pack_name, (uintmax_t)obj_offset);
2419}
2420
2421int do_check_packed_object_crc;
2422
2423#define UNPACK_ENTRY_STACK_PREALLOC 64
2424struct unpack_entry_stack_ent {
2425        off_t obj_offset;
2426        off_t curpos;
2427        unsigned long size;
2428};
2429
2430void *unpack_entry(struct packed_git *p, off_t obj_offset,
2431                   enum object_type *final_type, unsigned long *final_size)
2432{
2433        struct pack_window *w_curs = NULL;
2434        off_t curpos = obj_offset;
2435        void *data = NULL;
2436        unsigned long size;
2437        enum object_type type;
2438        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2439        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2440        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2441        int base_from_cache = 0;
2442
2443        write_pack_access_log(p, obj_offset);
2444
2445        /* PHASE 1: drill down to the innermost base object */
2446        for (;;) {
2447                off_t base_offset;
2448                int i;
2449                struct delta_base_cache_entry *ent;
2450
2451                ent = get_delta_base_cache_entry(p, curpos);
2452                if (ent) {
2453                        type = ent->type;
2454                        data = ent->data;
2455                        size = ent->size;
2456                        detach_delta_base_cache_entry(ent);
2457                        base_from_cache = 1;
2458                        break;
2459                }
2460
2461                if (do_check_packed_object_crc && p->index_version > 1) {
2462                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2463                        off_t len = revidx[1].offset - obj_offset;
2464                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2465                                const unsigned char *sha1 =
2466                                        nth_packed_object_sha1(p, revidx->nr);
2467                                error("bad packed object CRC for %s",
2468                                      sha1_to_hex(sha1));
2469                                mark_bad_packed_object(p, sha1);
2470                                unuse_pack(&w_curs);
2471                                return NULL;
2472                        }
2473                }
2474
2475                type = unpack_object_header(p, &w_curs, &curpos, &size);
2476                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2477                        break;
2478
2479                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2480                if (!base_offset) {
2481                        error("failed to validate delta base reference "
2482                              "at offset %"PRIuMAX" from %s",
2483                              (uintmax_t)curpos, p->pack_name);
2484                        /* bail to phase 2, in hopes of recovery */
2485                        data = NULL;
2486                        break;
2487                }
2488
2489                /* push object, proceed to base */
2490                if (delta_stack_nr >= delta_stack_alloc
2491                    && delta_stack == small_delta_stack) {
2492                        delta_stack_alloc = alloc_nr(delta_stack_nr);
2493                        ALLOC_ARRAY(delta_stack, delta_stack_alloc);
2494                        memcpy(delta_stack, small_delta_stack,
2495                               sizeof(*delta_stack)*delta_stack_nr);
2496                } else {
2497                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2498                }
2499                i = delta_stack_nr++;
2500                delta_stack[i].obj_offset = obj_offset;
2501                delta_stack[i].curpos = curpos;
2502                delta_stack[i].size = size;
2503
2504                curpos = obj_offset = base_offset;
2505        }
2506
2507        /* PHASE 2: handle the base */
2508        switch (type) {
2509        case OBJ_OFS_DELTA:
2510        case OBJ_REF_DELTA:
2511                if (data)
2512                        die("BUG: unpack_entry: left loop at a valid delta");
2513                break;
2514        case OBJ_COMMIT:
2515        case OBJ_TREE:
2516        case OBJ_BLOB:
2517        case OBJ_TAG:
2518                if (!base_from_cache)
2519                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
2520                break;
2521        default:
2522                data = NULL;
2523                error("unknown object type %i at offset %"PRIuMAX" in %s",
2524                      type, (uintmax_t)obj_offset, p->pack_name);
2525        }
2526
2527        /* PHASE 3: apply deltas in order */
2528
2529        /* invariants:
2530         *   'data' holds the base data, or NULL if there was corruption
2531         */
2532        while (delta_stack_nr) {
2533                void *delta_data;
2534                void *base = data;
2535                unsigned long delta_size, base_size = size;
2536                int i;
2537
2538                data = NULL;
2539
2540                if (base)
2541                        add_delta_base_cache(p, obj_offset, base, base_size, type);
2542
2543                if (!base) {
2544                        /*
2545                         * We're probably in deep shit, but let's try to fetch
2546                         * the required base anyway from another pack or loose.
2547                         * This is costly but should happen only in the presence
2548                         * of a corrupted pack, and is better than failing outright.
2549                         */
2550                        struct revindex_entry *revidx;
2551                        const unsigned char *base_sha1;
2552                        revidx = find_pack_revindex(p, obj_offset);
2553                        if (revidx) {
2554                                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2555                                error("failed to read delta base object %s"
2556                                      " at offset %"PRIuMAX" from %s",
2557                                      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2558                                      p->pack_name);
2559                                mark_bad_packed_object(p, base_sha1);
2560                                base = read_object(base_sha1, &type, &base_size);
2561                        }
2562                }
2563
2564                i = --delta_stack_nr;
2565                obj_offset = delta_stack[i].obj_offset;
2566                curpos = delta_stack[i].curpos;
2567                delta_size = delta_stack[i].size;
2568
2569                if (!base)
2570                        continue;
2571
2572                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2573
2574                if (!delta_data) {
2575                        error("failed to unpack compressed delta "
2576                              "at offset %"PRIuMAX" from %s",
2577                              (uintmax_t)curpos, p->pack_name);
2578                        data = NULL;
2579                        continue;
2580                }
2581
2582                data = patch_delta(base, base_size,
2583                                   delta_data, delta_size,
2584                                   &size);
2585
2586                /*
2587                 * We could not apply the delta; warn the user, but keep going.
2588                 * Our failure will be noticed either in the next iteration of
2589                 * the loop, or if this is the final delta, in the caller when
2590                 * we return NULL. Those code paths will take care of making
2591                 * a more explicit warning and retrying with another copy of
2592                 * the object.
2593                 */
2594                if (!data)
2595                        error("failed to apply delta");
2596
2597                free(delta_data);
2598        }
2599
2600        *final_type = type;
2601        *final_size = size;
2602
2603        unuse_pack(&w_curs);
2604
2605        if (delta_stack != small_delta_stack)
2606                free(delta_stack);
2607
2608        return data;
2609}
2610
2611const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2612                                            uint32_t n)
2613{
2614        const unsigned char *index = p->index_data;
2615        if (!index) {
2616                if (open_pack_index(p))
2617                        return NULL;
2618                index = p->index_data;
2619        }
2620        if (n >= p->num_objects)
2621                return NULL;
2622        index += 4 * 256;
2623        if (p->index_version == 1) {
2624                return index + 24 * n + 4;
2625        } else {
2626                index += 8;
2627                return index + 20 * n;
2628        }
2629}
2630
2631void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
2632{
2633        const unsigned char *ptr = vptr;
2634        const unsigned char *start = p->index_data;
2635        const unsigned char *end = start + p->index_size;
2636        if (ptr < start)
2637                die(_("offset before start of pack index for %s (corrupt index?)"),
2638                    p->pack_name);
2639        /* No need to check for underflow; .idx files must be at least 8 bytes */
2640        if (ptr >= end - 8)
2641                die(_("offset beyond end of pack index for %s (truncated index?)"),
2642                    p->pack_name);
2643}
2644
2645off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2646{
2647        const unsigned char *index = p->index_data;
2648        index += 4 * 256;
2649        if (p->index_version == 1) {
2650                return ntohl(*((uint32_t *)(index + 24 * n)));
2651        } else {
2652                uint32_t off;
2653                index += 8 + p->num_objects * (20 + 4);
2654                off = ntohl(*((uint32_t *)(index + 4 * n)));
2655                if (!(off & 0x80000000))
2656                        return off;
2657                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2658                check_pack_index_ptr(p, index);
2659                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2660                                   ntohl(*((uint32_t *)(index + 4)));
2661        }
2662}
2663
2664off_t find_pack_entry_one(const unsigned char *sha1,
2665                                  struct packed_git *p)
2666{
2667        const uint32_t *level1_ofs = p->index_data;
2668        const unsigned char *index = p->index_data;
2669        unsigned hi, lo, stride;
2670        static int use_lookup = -1;
2671        static int debug_lookup = -1;
2672
2673        if (debug_lookup < 0)
2674                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2675
2676        if (!index) {
2677                if (open_pack_index(p))
2678                        return 0;
2679                level1_ofs = p->index_data;
2680                index = p->index_data;
2681        }
2682        if (p->index_version > 1) {
2683                level1_ofs += 2;
2684                index += 8;
2685        }
2686        index += 4 * 256;
2687        hi = ntohl(level1_ofs[*sha1]);
2688        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2689        if (p->index_version > 1) {
2690                stride = 20;
2691        } else {
2692                stride = 24;
2693                index += 4;
2694        }
2695
2696        if (debug_lookup)
2697                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2698                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2699
2700        if (use_lookup < 0)
2701                use_lookup = !!getenv("GIT_USE_LOOKUP");
2702        if (use_lookup) {
2703                int pos = sha1_entry_pos(index, stride, 0,
2704                                         lo, hi, p->num_objects, sha1);
2705                if (pos < 0)
2706                        return 0;
2707                return nth_packed_object_offset(p, pos);
2708        }
2709
2710        do {
2711                unsigned mi = (lo + hi) / 2;
2712                int cmp = hashcmp(index + mi * stride, sha1);
2713
2714                if (debug_lookup)
2715                        printf("lo %u hi %u rg %u mi %u\n",
2716                               lo, hi, hi - lo, mi);
2717                if (!cmp)
2718                        return nth_packed_object_offset(p, mi);
2719                if (cmp > 0)
2720                        hi = mi;
2721                else
2722                        lo = mi+1;
2723        } while (lo < hi);
2724        return 0;
2725}
2726
2727int is_pack_valid(struct packed_git *p)
2728{
2729        /* An already open pack is known to be valid. */
2730        if (p->pack_fd != -1)
2731                return 1;
2732
2733        /* If the pack has one window completely covering the
2734         * file size, the pack is known to be valid even if
2735         * the descriptor is not currently open.
2736         */
2737        if (p->windows) {
2738                struct pack_window *w = p->windows;
2739
2740                if (!w->offset && w->len == p->pack_size)
2741                        return 1;
2742        }
2743
2744        /* Force the pack to open to prove its valid. */
2745        return !open_packed_git(p);
2746}
2747
2748static int fill_pack_entry(const unsigned char *sha1,
2749                           struct pack_entry *e,
2750                           struct packed_git *p)
2751{
2752        off_t offset;
2753
2754        if (p->num_bad_objects) {
2755                unsigned i;
2756                for (i = 0; i < p->num_bad_objects; i++)
2757                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2758                                return 0;
2759        }
2760
2761        offset = find_pack_entry_one(sha1, p);
2762        if (!offset)
2763                return 0;
2764
2765        /*
2766         * We are about to tell the caller where they can locate the
2767         * requested object.  We better make sure the packfile is
2768         * still here and can be accessed before supplying that
2769         * answer, as it may have been deleted since the index was
2770         * loaded!
2771         */
2772        if (!is_pack_valid(p))
2773                return 0;
2774        e->offset = offset;
2775        e->p = p;
2776        hashcpy(e->sha1, sha1);
2777        return 1;
2778}
2779
2780/*
2781 * Iff a pack file contains the object named by sha1, return true and
2782 * store its location to e.
2783 */
2784static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2785{
2786        struct mru_entry *p;
2787
2788        prepare_packed_git();
2789        if (!packed_git)
2790                return 0;
2791
2792        for (p = packed_git_mru->head; p; p = p->next) {
2793                if (fill_pack_entry(sha1, e, p->item)) {
2794                        mru_mark(packed_git_mru, p);
2795                        return 1;
2796                }
2797        }
2798        return 0;
2799}
2800
2801struct packed_git *find_sha1_pack(const unsigned char *sha1,
2802                                  struct packed_git *packs)
2803{
2804        struct packed_git *p;
2805
2806        for (p = packs; p; p = p->next) {
2807                if (find_pack_entry_one(sha1, p))
2808                        return p;
2809        }
2810        return NULL;
2811
2812}
2813
2814static int sha1_loose_object_info(const unsigned char *sha1,
2815                                  struct object_info *oi,
2816                                  int flags)
2817{
2818        int status = 0;
2819        unsigned long mapsize;
2820        void *map;
2821        git_zstream stream;
2822        char hdr[32];
2823        struct strbuf hdrbuf = STRBUF_INIT;
2824
2825        if (oi->delta_base_sha1)
2826                hashclr(oi->delta_base_sha1);
2827
2828        /*
2829         * If we don't care about type or size, then we don't
2830         * need to look inside the object at all. Note that we
2831         * do not optimize out the stat call, even if the
2832         * caller doesn't care about the disk-size, since our
2833         * return value implicitly indicates whether the
2834         * object even exists.
2835         */
2836        if (!oi->typep && !oi->typename && !oi->sizep) {
2837                const char *path;
2838                struct stat st;
2839                if (stat_sha1_file(sha1, &st, &path) < 0)
2840                        return -1;
2841                if (oi->disk_sizep)
2842                        *oi->disk_sizep = st.st_size;
2843                return 0;
2844        }
2845
2846        map = map_sha1_file(sha1, &mapsize);
2847        if (!map)
2848                return -1;
2849        if (oi->disk_sizep)
2850                *oi->disk_sizep = mapsize;
2851        if ((flags & LOOKUP_UNKNOWN_OBJECT)) {
2852                if (unpack_sha1_header_to_strbuf(&stream, map, mapsize, hdr, sizeof(hdr), &hdrbuf) < 0)
2853                        status = error("unable to unpack %s header with --allow-unknown-type",
2854                                       sha1_to_hex(sha1));
2855        } else if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2856                status = error("unable to unpack %s header",
2857                               sha1_to_hex(sha1));
2858        if (status < 0)
2859                ; /* Do nothing */
2860        else if (hdrbuf.len) {
2861                if ((status = parse_sha1_header_extended(hdrbuf.buf, oi, flags)) < 0)
2862                        status = error("unable to parse %s header with --allow-unknown-type",
2863                                       sha1_to_hex(sha1));
2864        } else if ((status = parse_sha1_header_extended(hdr, oi, flags)) < 0)
2865                status = error("unable to parse %s header", sha1_to_hex(sha1));
2866        git_inflate_end(&stream);
2867        munmap(map, mapsize);
2868        if (status && oi->typep)
2869                *oi->typep = status;
2870        strbuf_release(&hdrbuf);
2871        return 0;
2872}
2873
2874int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
2875{
2876        struct cached_object *co;
2877        struct pack_entry e;
2878        int rtype;
2879        enum object_type real_type;
2880        const unsigned char *real = lookup_replace_object_extended(sha1, flags);
2881
2882        co = find_cached_object(real);
2883        if (co) {
2884                if (oi->typep)
2885                        *(oi->typep) = co->type;
2886                if (oi->sizep)
2887                        *(oi->sizep) = co->size;
2888                if (oi->disk_sizep)
2889                        *(oi->disk_sizep) = 0;
2890                if (oi->delta_base_sha1)
2891                        hashclr(oi->delta_base_sha1);
2892                if (oi->typename)
2893                        strbuf_addstr(oi->typename, typename(co->type));
2894                oi->whence = OI_CACHED;
2895                return 0;
2896        }
2897
2898        if (!find_pack_entry(real, &e)) {
2899                /* Most likely it's a loose object. */
2900                if (!sha1_loose_object_info(real, oi, flags)) {
2901                        oi->whence = OI_LOOSE;
2902                        return 0;
2903                }
2904
2905                /* Not a loose object; someone else may have just packed it. */
2906                reprepare_packed_git();
2907                if (!find_pack_entry(real, &e))
2908                        return -1;
2909        }
2910
2911        /*
2912         * packed_object_info() does not follow the delta chain to
2913         * find out the real type, unless it is given oi->typep.
2914         */
2915        if (oi->typename && !oi->typep)
2916                oi->typep = &real_type;
2917
2918        rtype = packed_object_info(e.p, e.offset, oi);
2919        if (rtype < 0) {
2920                mark_bad_packed_object(e.p, real);
2921                if (oi->typep == &real_type)
2922                        oi->typep = NULL;
2923                return sha1_object_info_extended(real, oi, 0);
2924        } else if (in_delta_base_cache(e.p, e.offset)) {
2925                oi->whence = OI_DBCACHED;
2926        } else {
2927                oi->whence = OI_PACKED;
2928                oi->u.packed.offset = e.offset;
2929                oi->u.packed.pack = e.p;
2930                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2931                                         rtype == OBJ_OFS_DELTA);
2932        }
2933        if (oi->typename)
2934                strbuf_addstr(oi->typename, typename(*oi->typep));
2935        if (oi->typep == &real_type)
2936                oi->typep = NULL;
2937
2938        return 0;
2939}
2940
2941/* returns enum object_type or negative */
2942int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2943{
2944        enum object_type type;
2945        struct object_info oi = OBJECT_INFO_INIT;
2946
2947        oi.typep = &type;
2948        oi.sizep = sizep;
2949        if (sha1_object_info_extended(sha1, &oi, LOOKUP_REPLACE_OBJECT) < 0)
2950                return -1;
2951        return type;
2952}
2953
2954static void *read_packed_sha1(const unsigned char *sha1,
2955                              enum object_type *type, unsigned long *size)
2956{
2957        struct pack_entry e;
2958        void *data;
2959
2960        if (!find_pack_entry(sha1, &e))
2961                return NULL;
2962        data = cache_or_unpack_entry(e.p, e.offset, size, type);
2963        if (!data) {
2964                /*
2965                 * We're probably in deep shit, but let's try to fetch
2966                 * the required object anyway from another pack or loose.
2967                 * This should happen only in the presence of a corrupted
2968                 * pack, and is better than failing outright.
2969                 */
2970                error("failed to read object %s at offset %"PRIuMAX" from %s",
2971                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2972                mark_bad_packed_object(e.p, sha1);
2973                data = read_object(sha1, type, size);
2974        }
2975        return data;
2976}
2977
2978int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2979                      unsigned char *sha1)
2980{
2981        struct cached_object *co;
2982
2983        hash_sha1_file(buf, len, typename(type), sha1);
2984        if (has_sha1_file(sha1) || find_cached_object(sha1))
2985                return 0;
2986        ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
2987        co = &cached_objects[cached_object_nr++];
2988        co->size = len;
2989        co->type = type;
2990        co->buf = xmalloc(len);
2991        memcpy(co->buf, buf, len);
2992        hashcpy(co->sha1, sha1);
2993        return 0;
2994}
2995
2996static void *read_object(const unsigned char *sha1, enum object_type *type,
2997                         unsigned long *size)
2998{
2999        unsigned long mapsize;
3000        void *map, *buf;
3001        struct cached_object *co;
3002
3003        co = find_cached_object(sha1);
3004        if (co) {
3005                *type = co->type;
3006                *size = co->size;
3007                return xmemdupz(co->buf, co->size);
3008        }
3009
3010        buf = read_packed_sha1(sha1, type, size);
3011        if (buf)
3012                return buf;
3013        map = map_sha1_file(sha1, &mapsize);
3014        if (map) {
3015                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
3016                munmap(map, mapsize);
3017                return buf;
3018        }
3019        reprepare_packed_git();
3020        return read_packed_sha1(sha1, type, size);
3021}
3022
3023/*
3024 * This function dies on corrupt objects; the callers who want to
3025 * deal with them should arrange to call read_object() and give error
3026 * messages themselves.
3027 */
3028void *read_sha1_file_extended(const unsigned char *sha1,
3029                              enum object_type *type,
3030                              unsigned long *size,
3031                              unsigned flag)
3032{
3033        void *data;
3034        const struct packed_git *p;
3035        const char *path;
3036        struct stat st;
3037        const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
3038
3039        errno = 0;
3040        data = read_object(repl, type, size);
3041        if (data)
3042                return data;
3043
3044        if (errno && errno != ENOENT)
3045                die_errno("failed to read object %s", sha1_to_hex(sha1));
3046
3047        /* die if we replaced an object with one that does not exist */
3048        if (repl != sha1)
3049                die("replacement %s not found for %s",
3050                    sha1_to_hex(repl), sha1_to_hex(sha1));
3051
3052        if (!stat_sha1_file(repl, &st, &path))
3053                die("loose object %s (stored in %s) is corrupt",
3054                    sha1_to_hex(repl), path);
3055
3056        if ((p = has_packed_and_bad(repl)) != NULL)
3057                die("packed object %s (stored in %s) is corrupt",
3058                    sha1_to_hex(repl), p->pack_name);
3059
3060        return NULL;
3061}
3062
3063void *read_object_with_reference(const unsigned char *sha1,
3064                                 const char *required_type_name,
3065                                 unsigned long *size,
3066                                 unsigned char *actual_sha1_return)
3067{
3068        enum object_type type, required_type;
3069        void *buffer;
3070        unsigned long isize;
3071        unsigned char actual_sha1[20];
3072
3073        required_type = type_from_string(required_type_name);
3074        hashcpy(actual_sha1, sha1);
3075        while (1) {
3076                int ref_length = -1;
3077                const char *ref_type = NULL;
3078
3079                buffer = read_sha1_file(actual_sha1, &type, &isize);
3080                if (!buffer)
3081                        return NULL;
3082                if (type == required_type) {
3083                        *size = isize;
3084                        if (actual_sha1_return)
3085                                hashcpy(actual_sha1_return, actual_sha1);
3086                        return buffer;
3087                }
3088                /* Handle references */
3089                else if (type == OBJ_COMMIT)
3090                        ref_type = "tree ";
3091                else if (type == OBJ_TAG)
3092                        ref_type = "object ";
3093                else {
3094                        free(buffer);
3095                        return NULL;
3096                }
3097                ref_length = strlen(ref_type);
3098
3099                if (ref_length + 40 > isize ||
3100                    memcmp(buffer, ref_type, ref_length) ||
3101                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
3102                        free(buffer);
3103                        return NULL;
3104                }
3105                free(buffer);
3106                /* Now we have the ID of the referred-to object in
3107                 * actual_sha1.  Check again. */
3108        }
3109}
3110
3111static void write_sha1_file_prepare(const void *buf, unsigned long len,
3112                                    const char *type, unsigned char *sha1,
3113                                    char *hdr, int *hdrlen)
3114{
3115        git_SHA_CTX c;
3116
3117        /* Generate the header */
3118        *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
3119
3120        /* Sha1.. */
3121        git_SHA1_Init(&c);
3122        git_SHA1_Update(&c, hdr, *hdrlen);
3123        git_SHA1_Update(&c, buf, len);
3124        git_SHA1_Final(sha1, &c);
3125}
3126
3127/*
3128 * Move the just written object into its final resting place.
3129 */
3130int finalize_object_file(const char *tmpfile, const char *filename)
3131{
3132        int ret = 0;
3133
3134        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
3135                goto try_rename;
3136        else if (link(tmpfile, filename))
3137                ret = errno;
3138
3139        /*
3140         * Coda hack - coda doesn't like cross-directory links,
3141         * so we fall back to a rename, which will mean that it
3142         * won't be able to check collisions, but that's not a
3143         * big deal.
3144         *
3145         * The same holds for FAT formatted media.
3146         *
3147         * When this succeeds, we just return.  We have nothing
3148         * left to unlink.
3149         */
3150        if (ret && ret != EEXIST) {
3151        try_rename:
3152                if (!rename(tmpfile, filename))
3153                        goto out;
3154                ret = errno;
3155        }
3156        unlink_or_warn(tmpfile);
3157        if (ret) {
3158                if (ret != EEXIST) {
3159                        return error_errno("unable to write sha1 filename %s", filename);
3160                }
3161                /* FIXME!!! Collision check here ? */
3162        }
3163
3164out:
3165        if (adjust_shared_perm(filename))
3166                return error("unable to set permission to '%s'", filename);
3167        return 0;
3168}
3169
3170static int write_buffer(int fd, const void *buf, size_t len)
3171{
3172        if (write_in_full(fd, buf, len) < 0)
3173                return error_errno("file write error");
3174        return 0;
3175}
3176
3177int hash_sha1_file(const void *buf, unsigned long len, const char *type,
3178                   unsigned char *sha1)
3179{
3180        char hdr[32];
3181        int hdrlen = sizeof(hdr);
3182        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
3183        return 0;
3184}
3185
3186/* Finalize a file on disk, and close it. */
3187static void close_sha1_file(int fd)
3188{
3189        if (fsync_object_files)
3190                fsync_or_die(fd, "sha1 file");
3191        if (close(fd) != 0)
3192                die_errno("error when closing sha1 file");
3193}
3194
3195/* Size of directory component, including the ending '/' */
3196static inline int directory_size(const char *filename)
3197{
3198        const char *s = strrchr(filename, '/');
3199        if (!s)
3200                return 0;
3201        return s - filename + 1;
3202}
3203
3204/*
3205 * This creates a temporary file in the same directory as the final
3206 * 'filename'
3207 *
3208 * We want to avoid cross-directory filename renames, because those
3209 * can have problems on various filesystems (FAT, NFS, Coda).
3210 */
3211static int create_tmpfile(struct strbuf *tmp, const char *filename)
3212{
3213        int fd, dirlen = directory_size(filename);
3214
3215        strbuf_reset(tmp);
3216        strbuf_add(tmp, filename, dirlen);
3217        strbuf_addstr(tmp, "tmp_obj_XXXXXX");
3218        fd = git_mkstemp_mode(tmp->buf, 0444);
3219        if (fd < 0 && dirlen && errno == ENOENT) {
3220                /*
3221                 * Make sure the directory exists; note that the contents
3222                 * of the buffer are undefined after mkstemp returns an
3223                 * error, so we have to rewrite the whole buffer from
3224                 * scratch.
3225                 */
3226                strbuf_reset(tmp);
3227                strbuf_add(tmp, filename, dirlen - 1);
3228                if (mkdir(tmp->buf, 0777) && errno != EEXIST)
3229                        return -1;
3230                if (adjust_shared_perm(tmp->buf))
3231                        return -1;
3232
3233                /* Try again */
3234                strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
3235                fd = git_mkstemp_mode(tmp->buf, 0444);
3236        }
3237        return fd;
3238}
3239
3240static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
3241                              const void *buf, unsigned long len, time_t mtime)
3242{
3243        int fd, ret;
3244        unsigned char compressed[4096];
3245        git_zstream stream;
3246        git_SHA_CTX c;
3247        unsigned char parano_sha1[20];
3248        static struct strbuf tmp_file = STRBUF_INIT;
3249        const char *filename = sha1_file_name(sha1);
3250
3251        fd = create_tmpfile(&tmp_file, filename);
3252        if (fd < 0) {
3253                if (errno == EACCES)
3254                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
3255                else
3256                        return error_errno("unable to create temporary file");
3257        }
3258
3259        /* Set it up */
3260        git_deflate_init(&stream, zlib_compression_level);
3261        stream.next_out = compressed;
3262        stream.avail_out = sizeof(compressed);
3263        git_SHA1_Init(&c);
3264
3265        /* First header.. */
3266        stream.next_in = (unsigned char *)hdr;
3267        stream.avail_in = hdrlen;
3268        while (git_deflate(&stream, 0) == Z_OK)
3269                ; /* nothing */
3270        git_SHA1_Update(&c, hdr, hdrlen);
3271
3272        /* Then the data itself.. */
3273        stream.next_in = (void *)buf;
3274        stream.avail_in = len;
3275        do {
3276                unsigned char *in0 = stream.next_in;
3277                ret = git_deflate(&stream, Z_FINISH);
3278                git_SHA1_Update(&c, in0, stream.next_in - in0);
3279                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
3280                        die("unable to write sha1 file");
3281                stream.next_out = compressed;
3282                stream.avail_out = sizeof(compressed);
3283        } while (ret == Z_OK);
3284
3285        if (ret != Z_STREAM_END)
3286                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
3287        ret = git_deflate_end_gently(&stream);
3288        if (ret != Z_OK)
3289                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
3290        git_SHA1_Final(parano_sha1, &c);
3291        if (hashcmp(sha1, parano_sha1) != 0)
3292                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
3293
3294        close_sha1_file(fd);
3295
3296        if (mtime) {
3297                struct utimbuf utb;
3298                utb.actime = mtime;
3299                utb.modtime = mtime;
3300                if (utime(tmp_file.buf, &utb) < 0)
3301                        warning_errno("failed utime() on %s", tmp_file.buf);
3302        }
3303
3304        return finalize_object_file(tmp_file.buf, filename);
3305}
3306
3307static int freshen_loose_object(const unsigned char *sha1)
3308{
3309        return check_and_freshen(sha1, 1);
3310}
3311
3312static int freshen_packed_object(const unsigned char *sha1)
3313{
3314        struct pack_entry e;
3315        if (!find_pack_entry(sha1, &e))
3316                return 0;
3317        if (e.p->freshened)
3318                return 1;
3319        if (!freshen_file(e.p->pack_name))
3320                return 0;
3321        e.p->freshened = 1;
3322        return 1;
3323}
3324
3325int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
3326{
3327        char hdr[32];
3328        int hdrlen = sizeof(hdr);
3329
3330        /* Normally if we have it in the pack then we do not bother writing
3331         * it out into .git/objects/??/?{38} file.
3332         */
3333        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
3334        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3335                return 0;
3336        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
3337}
3338
3339int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
3340                             unsigned char *sha1, unsigned flags)
3341{
3342        char *header;
3343        int hdrlen, status = 0;
3344
3345        /* type string, SP, %lu of the length plus NUL must fit this */
3346        hdrlen = strlen(type) + 32;
3347        header = xmalloc(hdrlen);
3348        write_sha1_file_prepare(buf, len, type, sha1, header, &hdrlen);
3349
3350        if (!(flags & HASH_WRITE_OBJECT))
3351                goto cleanup;
3352        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3353                goto cleanup;
3354        status = write_loose_object(sha1, header, hdrlen, buf, len, 0);
3355
3356cleanup:
3357        free(header);
3358        return status;
3359}
3360
3361int force_object_loose(const unsigned char *sha1, time_t mtime)
3362{
3363        void *buf;
3364        unsigned long len;
3365        enum object_type type;
3366        char hdr[32];
3367        int hdrlen;
3368        int ret;
3369
3370        if (has_loose_object(sha1))
3371                return 0;
3372        buf = read_packed_sha1(sha1, &type, &len);
3373        if (!buf)
3374                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
3375        hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(type), len) + 1;
3376        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
3377        free(buf);
3378
3379        return ret;
3380}
3381
3382int has_pack_index(const unsigned char *sha1)
3383{
3384        struct stat st;
3385        if (stat(sha1_pack_index_name(sha1), &st))
3386                return 0;
3387        return 1;
3388}
3389
3390int has_sha1_pack(const unsigned char *sha1)
3391{
3392        struct pack_entry e;
3393        return find_pack_entry(sha1, &e);
3394}
3395
3396int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
3397{
3398        struct pack_entry e;
3399
3400        if (find_pack_entry(sha1, &e))
3401                return 1;
3402        if (has_loose_object(sha1))
3403                return 1;
3404        if (flags & HAS_SHA1_QUICK)
3405                return 0;
3406        reprepare_packed_git();
3407        return find_pack_entry(sha1, &e);
3408}
3409
3410int has_object_file(const struct object_id *oid)
3411{
3412        return has_sha1_file(oid->hash);
3413}
3414
3415int has_object_file_with_flags(const struct object_id *oid, int flags)
3416{
3417        return has_sha1_file_with_flags(oid->hash, flags);
3418}
3419
3420static void check_tree(const void *buf, size_t size)
3421{
3422        struct tree_desc desc;
3423        struct name_entry entry;
3424
3425        init_tree_desc(&desc, buf, size);
3426        while (tree_entry(&desc, &entry))
3427                /* do nothing
3428                 * tree_entry() will die() on malformed entries */
3429                ;
3430}
3431
3432static void check_commit(const void *buf, size_t size)
3433{
3434        struct commit c;
3435        memset(&c, 0, sizeof(c));
3436        if (parse_commit_buffer(&c, buf, size))
3437                die("corrupt commit");
3438}
3439
3440static void check_tag(const void *buf, size_t size)
3441{
3442        struct tag t;
3443        memset(&t, 0, sizeof(t));
3444        if (parse_tag_buffer(&t, buf, size))
3445                die("corrupt tag");
3446}
3447
3448static int index_mem(unsigned char *sha1, void *buf, size_t size,
3449                     enum object_type type,
3450                     const char *path, unsigned flags)
3451{
3452        int ret, re_allocated = 0;
3453        int write_object = flags & HASH_WRITE_OBJECT;
3454
3455        if (!type)
3456                type = OBJ_BLOB;
3457
3458        /*
3459         * Convert blobs to git internal format
3460         */
3461        if ((type == OBJ_BLOB) && path) {
3462                struct strbuf nbuf = STRBUF_INIT;
3463                if (convert_to_git(path, buf, size, &nbuf,
3464                                   write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
3465                        buf = strbuf_detach(&nbuf, &size);
3466                        re_allocated = 1;
3467                }
3468        }
3469        if (flags & HASH_FORMAT_CHECK) {
3470                if (type == OBJ_TREE)
3471                        check_tree(buf, size);
3472                if (type == OBJ_COMMIT)
3473                        check_commit(buf, size);
3474                if (type == OBJ_TAG)
3475                        check_tag(buf, size);
3476        }
3477
3478        if (write_object)
3479                ret = write_sha1_file(buf, size, typename(type), sha1);
3480        else
3481                ret = hash_sha1_file(buf, size, typename(type), sha1);
3482        if (re_allocated)
3483                free(buf);
3484        return ret;
3485}
3486
3487static int index_stream_convert_blob(unsigned char *sha1, int fd,
3488                                     const char *path, unsigned flags)
3489{
3490        int ret;
3491        const int write_object = flags & HASH_WRITE_OBJECT;
3492        struct strbuf sbuf = STRBUF_INIT;
3493
3494        assert(path);
3495        assert(would_convert_to_git_filter_fd(path));
3496
3497        convert_to_git_filter_fd(path, fd, &sbuf,
3498                                 write_object ? safe_crlf : SAFE_CRLF_FALSE);
3499
3500        if (write_object)
3501                ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3502                                      sha1);
3503        else
3504                ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3505                                     sha1);
3506        strbuf_release(&sbuf);
3507        return ret;
3508}
3509
3510static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
3511                      const char *path, unsigned flags)
3512{
3513        struct strbuf sbuf = STRBUF_INIT;
3514        int ret;
3515
3516        if (strbuf_read(&sbuf, fd, 4096) >= 0)
3517                ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
3518        else
3519                ret = -1;
3520        strbuf_release(&sbuf);
3521        return ret;
3522}
3523
3524#define SMALL_FILE_SIZE (32*1024)
3525
3526static int index_core(unsigned char *sha1, int fd, size_t size,
3527                      enum object_type type, const char *path,
3528                      unsigned flags)
3529{
3530        int ret;
3531
3532        if (!size) {
3533                ret = index_mem(sha1, "", size, type, path, flags);
3534        } else if (size <= SMALL_FILE_SIZE) {
3535                char *buf = xmalloc(size);
3536                if (size == read_in_full(fd, buf, size))
3537                        ret = index_mem(sha1, buf, size, type, path, flags);
3538                else
3539                        ret = error_errno("short read");
3540                free(buf);
3541        } else {
3542                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3543                ret = index_mem(sha1, buf, size, type, path, flags);
3544                munmap(buf, size);
3545        }
3546        return ret;
3547}
3548
3549/*
3550 * This creates one packfile per large blob unless bulk-checkin
3551 * machinery is "plugged".
3552 *
3553 * This also bypasses the usual "convert-to-git" dance, and that is on
3554 * purpose. We could write a streaming version of the converting
3555 * functions and insert that before feeding the data to fast-import
3556 * (or equivalent in-core API described above). However, that is
3557 * somewhat complicated, as we do not know the size of the filter
3558 * result, which we need to know beforehand when writing a git object.
3559 * Since the primary motivation for trying to stream from the working
3560 * tree file and to avoid mmaping it in core is to deal with large
3561 * binary blobs, they generally do not want to get any conversion, and
3562 * callers should avoid this code path when filters are requested.
3563 */
3564static int index_stream(unsigned char *sha1, int fd, size_t size,
3565                        enum object_type type, const char *path,
3566                        unsigned flags)
3567{
3568        return index_bulk_checkin(sha1, fd, size, type, path, flags);
3569}
3570
3571int index_fd(unsigned char *sha1, int fd, struct stat *st,
3572             enum object_type type, const char *path, unsigned flags)
3573{
3574        int ret;
3575
3576        /*
3577         * Call xsize_t() only when needed to avoid potentially unnecessary
3578         * die() for large files.
3579         */
3580        if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
3581                ret = index_stream_convert_blob(sha1, fd, path, flags);
3582        else if (!S_ISREG(st->st_mode))
3583                ret = index_pipe(sha1, fd, type, path, flags);
3584        else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
3585                 (path && would_convert_to_git(path)))
3586                ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
3587                                 flags);
3588        else
3589                ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
3590                                   flags);
3591        close(fd);
3592        return ret;
3593}
3594
3595int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3596{
3597        int fd;
3598        struct strbuf sb = STRBUF_INIT;
3599
3600        switch (st->st_mode & S_IFMT) {
3601        case S_IFREG:
3602                fd = open(path, O_RDONLY);
3603                if (fd < 0)
3604                        return error_errno("open(\"%s\")", path);
3605                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3606                        return error("%s: failed to insert into database",
3607                                     path);
3608                break;
3609        case S_IFLNK:
3610                if (strbuf_readlink(&sb, path, st->st_size))
3611                        return error_errno("readlink(\"%s\")", path);
3612                if (!(flags & HASH_WRITE_OBJECT))
3613                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3614                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3615                        return error("%s: failed to insert into database",
3616                                     path);
3617                strbuf_release(&sb);
3618                break;
3619        case S_IFDIR:
3620                return resolve_gitlink_ref(path, "HEAD", sha1);
3621        default:
3622                return error("%s: unsupported file type", path);
3623        }
3624        return 0;
3625}
3626
3627int read_pack_header(int fd, struct pack_header *header)
3628{
3629        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3630                /* "eof before pack header was fully read" */
3631                return PH_ERROR_EOF;
3632
3633        if (header->hdr_signature != htonl(PACK_SIGNATURE))
3634                /* "protocol error (pack signature mismatch detected)" */
3635                return PH_ERROR_PACK_SIGNATURE;
3636        if (!pack_version_ok(header->hdr_version))
3637                /* "protocol error (pack version unsupported)" */
3638                return PH_ERROR_PROTOCOL;
3639        return 0;
3640}
3641
3642void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3643{
3644        enum object_type type = sha1_object_info(sha1, NULL);
3645        if (type < 0)
3646                die("%s is not a valid object", sha1_to_hex(sha1));
3647        if (type != expect)
3648                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3649                    typename(expect));
3650}
3651
3652static int for_each_file_in_obj_subdir(int subdir_nr,
3653                                       struct strbuf *path,
3654                                       each_loose_object_fn obj_cb,
3655                                       each_loose_cruft_fn cruft_cb,
3656                                       each_loose_subdir_fn subdir_cb,
3657                                       void *data)
3658{
3659        size_t baselen = path->len;
3660        DIR *dir = opendir(path->buf);
3661        struct dirent *de;
3662        int r = 0;
3663
3664        if (!dir) {
3665                if (errno == ENOENT)
3666                        return 0;
3667                return error_errno("unable to open %s", path->buf);
3668        }
3669
3670        while ((de = readdir(dir))) {
3671                if (is_dot_or_dotdot(de->d_name))
3672                        continue;
3673
3674                strbuf_setlen(path, baselen);
3675                strbuf_addf(path, "/%s", de->d_name);
3676
3677                if (strlen(de->d_name) == 38)  {
3678                        char hex[41];
3679                        unsigned char sha1[20];
3680
3681                        snprintf(hex, sizeof(hex), "%02x%s",
3682                                 subdir_nr, de->d_name);
3683                        if (!get_sha1_hex(hex, sha1)) {
3684                                if (obj_cb) {
3685                                        r = obj_cb(sha1, path->buf, data);
3686                                        if (r)
3687                                                break;
3688                                }
3689                                continue;
3690                        }
3691                }
3692
3693                if (cruft_cb) {
3694                        r = cruft_cb(de->d_name, path->buf, data);
3695                        if (r)
3696                                break;
3697                }
3698        }
3699        closedir(dir);
3700
3701        strbuf_setlen(path, baselen);
3702        if (!r && subdir_cb)
3703                r = subdir_cb(subdir_nr, path->buf, data);
3704
3705        return r;
3706}
3707
3708int for_each_loose_file_in_objdir_buf(struct strbuf *path,
3709                            each_loose_object_fn obj_cb,
3710                            each_loose_cruft_fn cruft_cb,
3711                            each_loose_subdir_fn subdir_cb,
3712                            void *data)
3713{
3714        size_t baselen = path->len;
3715        int r = 0;
3716        int i;
3717
3718        for (i = 0; i < 256; i++) {
3719                strbuf_addf(path, "/%02x", i);
3720                r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
3721                                                subdir_cb, data);
3722                strbuf_setlen(path, baselen);
3723                if (r)
3724                        break;
3725        }
3726
3727        return r;
3728}
3729
3730int for_each_loose_file_in_objdir(const char *path,
3731                                  each_loose_object_fn obj_cb,
3732                                  each_loose_cruft_fn cruft_cb,
3733                                  each_loose_subdir_fn subdir_cb,
3734                                  void *data)
3735{
3736        struct strbuf buf = STRBUF_INIT;
3737        int r;
3738
3739        strbuf_addstr(&buf, path);
3740        r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
3741                                              subdir_cb, data);
3742        strbuf_release(&buf);
3743
3744        return r;
3745}
3746
3747struct loose_alt_odb_data {
3748        each_loose_object_fn *cb;
3749        void *data;
3750};
3751
3752static int loose_from_alt_odb(struct alternate_object_database *alt,
3753                              void *vdata)
3754{
3755        struct loose_alt_odb_data *data = vdata;
3756        struct strbuf buf = STRBUF_INIT;
3757        int r;
3758
3759        strbuf_addstr(&buf, alt->path);
3760        r = for_each_loose_file_in_objdir_buf(&buf,
3761                                              data->cb, NULL, NULL,
3762                                              data->data);
3763        strbuf_release(&buf);
3764        return r;
3765}
3766
3767int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
3768{
3769        struct loose_alt_odb_data alt;
3770        int r;
3771
3772        r = for_each_loose_file_in_objdir(get_object_directory(),
3773                                          cb, NULL, NULL, data);
3774        if (r)
3775                return r;
3776
3777        if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
3778                return 0;
3779
3780        alt.cb = cb;
3781        alt.data = data;
3782        return foreach_alt_odb(loose_from_alt_odb, &alt);
3783}
3784
3785static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
3786{
3787        uint32_t i;
3788        int r = 0;
3789
3790        for (i = 0; i < p->num_objects; i++) {
3791                const unsigned char *sha1 = nth_packed_object_sha1(p, i);
3792
3793                if (!sha1)
3794                        return error("unable to get sha1 of object %u in %s",
3795                                     i, p->pack_name);
3796
3797                r = cb(sha1, p, i, data);
3798                if (r)
3799                        break;
3800        }
3801        return r;
3802}
3803
3804int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
3805{
3806        struct packed_git *p;
3807        int r = 0;
3808        int pack_errors = 0;
3809
3810        prepare_packed_git();
3811        for (p = packed_git; p; p = p->next) {
3812                if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
3813                        continue;
3814                if (open_pack_index(p)) {
3815                        pack_errors = 1;
3816                        continue;
3817                }
3818                r = for_each_object_in_pack(p, cb, data);
3819                if (r)
3820                        break;
3821        }
3822        return r ? r : pack_errors;
3823}
3824
3825static int check_stream_sha1(git_zstream *stream,
3826                             const char *hdr,
3827                             unsigned long size,
3828                             const char *path,
3829                             const unsigned char *expected_sha1)
3830{
3831        git_SHA_CTX c;
3832        unsigned char real_sha1[GIT_SHA1_RAWSZ];
3833        unsigned char buf[4096];
3834        unsigned long total_read;
3835        int status = Z_OK;
3836
3837        git_SHA1_Init(&c);
3838        git_SHA1_Update(&c, hdr, stream->total_out);
3839
3840        /*
3841         * We already read some bytes into hdr, but the ones up to the NUL
3842         * do not count against the object's content size.
3843         */
3844        total_read = stream->total_out - strlen(hdr) - 1;
3845
3846        /*
3847         * This size comparison must be "<=" to read the final zlib packets;
3848         * see the comment in unpack_sha1_rest for details.
3849         */
3850        while (total_read <= size &&
3851               (status == Z_OK || status == Z_BUF_ERROR)) {
3852                stream->next_out = buf;
3853                stream->avail_out = sizeof(buf);
3854                if (size - total_read < stream->avail_out)
3855                        stream->avail_out = size - total_read;
3856                status = git_inflate(stream, Z_FINISH);
3857                git_SHA1_Update(&c, buf, stream->next_out - buf);
3858                total_read += stream->next_out - buf;
3859        }
3860        git_inflate_end(stream);
3861
3862        if (status != Z_STREAM_END) {
3863                error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
3864                return -1;
3865        }
3866        if (stream->avail_in) {
3867                error("garbage at end of loose object '%s'",
3868                      sha1_to_hex(expected_sha1));
3869                return -1;
3870        }
3871
3872        git_SHA1_Final(real_sha1, &c);
3873        if (hashcmp(expected_sha1, real_sha1)) {
3874                error("sha1 mismatch for %s (expected %s)", path,
3875                      sha1_to_hex(expected_sha1));
3876                return -1;
3877        }
3878
3879        return 0;
3880}
3881
3882int read_loose_object(const char *path,
3883                      const unsigned char *expected_sha1,
3884                      enum object_type *type,
3885                      unsigned long *size,
3886                      void **contents)
3887{
3888        int ret = -1;
3889        int fd = -1;
3890        void *map = NULL;
3891        unsigned long mapsize;
3892        git_zstream stream;
3893        char hdr[32];
3894
3895        *contents = NULL;
3896
3897        map = map_sha1_file_1(path, NULL, &mapsize);
3898        if (!map) {
3899                error_errno("unable to mmap %s", path);
3900                goto out;
3901        }
3902
3903        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
3904                error("unable to unpack header of %s", path);
3905                goto out;
3906        }
3907
3908        *type = parse_sha1_header(hdr, size);
3909        if (*type < 0) {
3910                error("unable to parse header of %s", path);
3911                git_inflate_end(&stream);
3912                goto out;
3913        }
3914
3915        if (*type == OBJ_BLOB) {
3916                if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
3917                        goto out;
3918        } else {
3919                *contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
3920                if (!*contents) {
3921                        error("unable to unpack contents of %s", path);
3922                        git_inflate_end(&stream);
3923                        goto out;
3924                }
3925                if (check_sha1_signature(expected_sha1, *contents,
3926                                         *size, typename(*type))) {
3927                        error("sha1 mismatch for %s (expected %s)", path,
3928                              sha1_to_hex(expected_sha1));
3929                        free(*contents);
3930                        goto out;
3931                }
3932        }
3933
3934        ret = 0; /* everything checks out */
3935
3936out:
3937        if (map)
3938                munmap(map, mapsize);
3939        if (fd >= 0)
3940                close(fd);
3941        return ret;
3942}