bd0f8f7c8db5731ef4e808ceff536860e97f6746
   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
  27#ifndef O_NOATIME
  28#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  29#define O_NOATIME 01000000
  30#else
  31#define O_NOATIME 0
  32#endif
  33#endif
  34
  35#define SZ_FMT PRIuMAX
  36static inline uintmax_t sz_fmt(size_t s) { return s; }
  37
  38const unsigned char null_sha1[20];
  39
  40/*
  41 * This is meant to hold a *small* number of objects that you would
  42 * want read_sha1_file() to be able to return, but yet you do not want
  43 * to write them into the object store (e.g. a browse-only
  44 * application).
  45 */
  46static struct cached_object {
  47        unsigned char sha1[20];
  48        enum object_type type;
  49        void *buf;
  50        unsigned long size;
  51} *cached_objects;
  52static int cached_object_nr, cached_object_alloc;
  53
  54static struct cached_object empty_tree = {
  55        EMPTY_TREE_SHA1_BIN_LITERAL,
  56        OBJ_TREE,
  57        "",
  58        0
  59};
  60
  61/*
  62 * A pointer to the last packed_git in which an object was found.
  63 * When an object is sought, we look in this packfile first, because
  64 * objects that are looked up at similar times are often in the same
  65 * packfile as one another.
  66 */
  67static struct packed_git *last_found_pack;
  68
  69static struct cached_object *find_cached_object(const unsigned char *sha1)
  70{
  71        int i;
  72        struct cached_object *co = cached_objects;
  73
  74        for (i = 0; i < cached_object_nr; i++, co++) {
  75                if (!hashcmp(co->sha1, sha1))
  76                        return co;
  77        }
  78        if (!hashcmp(sha1, empty_tree.sha1))
  79                return &empty_tree;
  80        return NULL;
  81}
  82
  83int mkdir_in_gitdir(const char *path)
  84{
  85        if (mkdir(path, 0777)) {
  86                int saved_errno = errno;
  87                struct stat st;
  88                struct strbuf sb = STRBUF_INIT;
  89
  90                if (errno != EEXIST)
  91                        return -1;
  92                /*
  93                 * Are we looking at a path in a symlinked worktree
  94                 * whose original repository does not yet have it?
  95                 * e.g. .git/rr-cache pointing at its original
  96                 * repository in which the user hasn't performed any
  97                 * conflict resolution yet?
  98                 */
  99                if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
 100                    strbuf_readlink(&sb, path, st.st_size) ||
 101                    !is_absolute_path(sb.buf) ||
 102                    mkdir(sb.buf, 0777)) {
 103                        strbuf_release(&sb);
 104                        errno = saved_errno;
 105                        return -1;
 106                }
 107                strbuf_release(&sb);
 108        }
 109        return adjust_shared_perm(path);
 110}
 111
 112enum scld_error safe_create_leading_directories(char *path)
 113{
 114        char *next_component = path + offset_1st_component(path);
 115        enum scld_error ret = SCLD_OK;
 116
 117        while (ret == SCLD_OK && next_component) {
 118                struct stat st;
 119                char *slash = next_component, slash_character;
 120
 121                while (*slash && !is_dir_sep(*slash))
 122                        slash++;
 123
 124                if (!*slash)
 125                        break;
 126
 127                next_component = slash + 1;
 128                while (is_dir_sep(*next_component))
 129                        next_component++;
 130                if (!*next_component)
 131                        break;
 132
 133                slash_character = *slash;
 134                *slash = '\0';
 135                if (!stat(path, &st)) {
 136                        /* path exists */
 137                        if (!S_ISDIR(st.st_mode))
 138                                ret = SCLD_EXISTS;
 139                } else if (mkdir(path, 0777)) {
 140                        if (errno == EEXIST &&
 141                            !stat(path, &st) && S_ISDIR(st.st_mode))
 142                                ; /* somebody created it since we checked */
 143                        else if (errno == ENOENT)
 144                                /*
 145                                 * Either mkdir() failed because
 146                                 * somebody just pruned the containing
 147                                 * directory, or stat() failed because
 148                                 * the file that was in our way was
 149                                 * just removed.  Either way, inform
 150                                 * the caller that it might be worth
 151                                 * trying again:
 152                                 */
 153                                ret = SCLD_VANISHED;
 154                        else
 155                                ret = SCLD_FAILED;
 156                } else if (adjust_shared_perm(path)) {
 157                        ret = SCLD_PERMS;
 158                }
 159                *slash = slash_character;
 160        }
 161        return ret;
 162}
 163
 164enum scld_error safe_create_leading_directories_const(const char *path)
 165{
 166        /* path points to cache entries, so xstrdup before messing with it */
 167        char *buf = xstrdup(path);
 168        enum scld_error result = safe_create_leading_directories(buf);
 169        free(buf);
 170        return result;
 171}
 172
 173static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 174{
 175        int i;
 176        for (i = 0; i < 20; i++) {
 177                static char hex[] = "0123456789abcdef";
 178                unsigned int val = sha1[i];
 179                char *pos = pathbuf + i*2 + (i > 0);
 180                *pos++ = hex[val >> 4];
 181                *pos = hex[val & 0xf];
 182        }
 183}
 184
 185const char *sha1_file_name(const unsigned char *sha1)
 186{
 187        static char buf[PATH_MAX];
 188        const char *objdir;
 189        int len;
 190
 191        objdir = get_object_directory();
 192        len = strlen(objdir);
 193
 194        /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 195        if (len + 43 > PATH_MAX)
 196                die("insanely long object directory %s", objdir);
 197        memcpy(buf, objdir, len);
 198        buf[len] = '/';
 199        buf[len+3] = '/';
 200        buf[len+42] = '\0';
 201        fill_sha1_path(buf + len + 1, sha1);
 202        return buf;
 203}
 204
 205/*
 206 * Return the name of the pack or index file with the specified sha1
 207 * in its filename.  *base and *name are scratch space that must be
 208 * provided by the caller.  which should be "pack" or "idx".
 209 */
 210static char *sha1_get_pack_name(const unsigned char *sha1,
 211                                char **name, char **base, const char *which)
 212{
 213        static const char hex[] = "0123456789abcdef";
 214        char *buf;
 215        int i;
 216
 217        if (!*base) {
 218                const char *sha1_file_directory = get_object_directory();
 219                int len = strlen(sha1_file_directory);
 220                *base = xmalloc(len + 60);
 221                sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 222                        sha1_file_directory, which);
 223                *name = *base + len + 11;
 224        }
 225
 226        buf = *name;
 227
 228        for (i = 0; i < 20; i++) {
 229                unsigned int val = *sha1++;
 230                *buf++ = hex[val >> 4];
 231                *buf++ = hex[val & 0xf];
 232        }
 233
 234        return *base;
 235}
 236
 237char *sha1_pack_name(const unsigned char *sha1)
 238{
 239        static char *name, *base;
 240
 241        return sha1_get_pack_name(sha1, &name, &base, "pack");
 242}
 243
 244char *sha1_pack_index_name(const unsigned char *sha1)
 245{
 246        static char *name, *base;
 247
 248        return sha1_get_pack_name(sha1, &name, &base, "idx");
 249}
 250
 251struct alternate_object_database *alt_odb_list;
 252static struct alternate_object_database **alt_odb_tail;
 253
 254/*
 255 * Prepare alternate object database registry.
 256 *
 257 * The variable alt_odb_list points at the list of struct
 258 * alternate_object_database.  The elements on this list come from
 259 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 260 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 261 * whose contents is similar to that environment variable but can be
 262 * LF separated.  Its base points at a statically allocated buffer that
 263 * contains "/the/directory/corresponding/to/.git/objects/...", while
 264 * its name points just after the slash at the end of ".git/objects/"
 265 * in the example above, and has enough space to hold 40-byte hex
 266 * SHA1, an extra slash for the first level indirection, and the
 267 * terminating NUL.
 268 */
 269static int link_alt_odb_entry(const char *entry, const char *relative_base,
 270        int depth, const char *normalized_objdir)
 271{
 272        struct alternate_object_database *ent;
 273        struct alternate_object_database *alt;
 274        int pfxlen, entlen;
 275        struct strbuf pathbuf = STRBUF_INIT;
 276
 277        if (!is_absolute_path(entry) && relative_base) {
 278                strbuf_addstr(&pathbuf, real_path(relative_base));
 279                strbuf_addch(&pathbuf, '/');
 280        }
 281        strbuf_addstr(&pathbuf, entry);
 282
 283        normalize_path_copy(pathbuf.buf, pathbuf.buf);
 284
 285        pfxlen = strlen(pathbuf.buf);
 286
 287        /*
 288         * The trailing slash after the directory name is given by
 289         * this function at the end. Remove duplicates.
 290         */
 291        while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
 292                pfxlen -= 1;
 293
 294        entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
 295        ent = xmalloc(sizeof(*ent) + entlen);
 296        memcpy(ent->base, pathbuf.buf, pfxlen);
 297        strbuf_release(&pathbuf);
 298
 299        ent->name = ent->base + pfxlen + 1;
 300        ent->base[pfxlen + 3] = '/';
 301        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 302
 303        /* Detect cases where alternate disappeared */
 304        if (!is_directory(ent->base)) {
 305                error("object directory %s does not exist; "
 306                      "check .git/objects/info/alternates.",
 307                      ent->base);
 308                free(ent);
 309                return -1;
 310        }
 311
 312        /* Prevent the common mistake of listing the same
 313         * thing twice, or object directory itself.
 314         */
 315        for (alt = alt_odb_list; alt; alt = alt->next) {
 316                if (pfxlen == alt->name - alt->base - 1 &&
 317                    !memcmp(ent->base, alt->base, pfxlen)) {
 318                        free(ent);
 319                        return -1;
 320                }
 321        }
 322        if (!strcmp_icase(ent->base, normalized_objdir)) {
 323                free(ent);
 324                return -1;
 325        }
 326
 327        /* add the alternate entry */
 328        *alt_odb_tail = ent;
 329        alt_odb_tail = &(ent->next);
 330        ent->next = NULL;
 331
 332        /* recursively add alternates */
 333        read_info_alternates(ent->base, depth + 1);
 334
 335        ent->base[pfxlen] = '/';
 336
 337        return 0;
 338}
 339
 340static void link_alt_odb_entries(const char *alt, int len, int sep,
 341                                 const char *relative_base, int depth)
 342{
 343        struct string_list entries = STRING_LIST_INIT_NODUP;
 344        char *alt_copy;
 345        int i;
 346        struct strbuf objdirbuf = STRBUF_INIT;
 347
 348        if (depth > 5) {
 349                error("%s: ignoring alternate object stores, nesting too deep.",
 350                                relative_base);
 351                return;
 352        }
 353
 354        strbuf_add_absolute_path(&objdirbuf, get_object_directory());
 355        normalize_path_copy(objdirbuf.buf, objdirbuf.buf);
 356
 357        alt_copy = xmemdupz(alt, len);
 358        string_list_split_in_place(&entries, alt_copy, sep, -1);
 359        for (i = 0; i < entries.nr; i++) {
 360                const char *entry = entries.items[i].string;
 361                if (entry[0] == '\0' || entry[0] == '#')
 362                        continue;
 363                if (!is_absolute_path(entry) && depth) {
 364                        error("%s: ignoring relative alternate object store %s",
 365                                        relative_base, entry);
 366                } else {
 367                        link_alt_odb_entry(entry, relative_base, depth, objdirbuf.buf);
 368                }
 369        }
 370        string_list_clear(&entries, 0);
 371        free(alt_copy);
 372        strbuf_release(&objdirbuf);
 373}
 374
 375void read_info_alternates(const char * relative_base, int depth)
 376{
 377        char *map;
 378        size_t mapsz;
 379        struct stat st;
 380        char *path;
 381        int fd;
 382
 383        path = xstrfmt("%s/info/alternates", relative_base);
 384        fd = git_open_noatime(path);
 385        free(path);
 386        if (fd < 0)
 387                return;
 388        if (fstat(fd, &st) || (st.st_size == 0)) {
 389                close(fd);
 390                return;
 391        }
 392        mapsz = xsize_t(st.st_size);
 393        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 394        close(fd);
 395
 396        link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
 397
 398        munmap(map, mapsz);
 399}
 400
 401void add_to_alternates_file(const char *reference)
 402{
 403        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 404        int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 405        char *alt = mkpath("%s\n", reference);
 406        write_or_die(fd, alt, strlen(alt));
 407        if (commit_lock_file(lock))
 408                die("could not close alternates file");
 409        if (alt_odb_tail)
 410                link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
 411}
 412
 413int foreach_alt_odb(alt_odb_fn fn, void *cb)
 414{
 415        struct alternate_object_database *ent;
 416        int r = 0;
 417
 418        prepare_alt_odb();
 419        for (ent = alt_odb_list; ent; ent = ent->next) {
 420                r = fn(ent, cb);
 421                if (r)
 422                        break;
 423        }
 424        return r;
 425}
 426
 427void prepare_alt_odb(void)
 428{
 429        const char *alt;
 430
 431        if (alt_odb_tail)
 432                return;
 433
 434        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 435        if (!alt) alt = "";
 436
 437        alt_odb_tail = &alt_odb_list;
 438        link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
 439
 440        read_info_alternates(get_object_directory(), 0);
 441}
 442
 443/* Returns 1 if we have successfully freshened the file, 0 otherwise. */
 444static int freshen_file(const char *fn)
 445{
 446        struct utimbuf t;
 447        t.actime = t.modtime = time(NULL);
 448        return !utime(fn, &t);
 449}
 450
 451/*
 452 * All of the check_and_freshen functions return 1 if the file exists and was
 453 * freshened (if freshening was requested), 0 otherwise. If they return
 454 * 0, you should not assume that it is safe to skip a write of the object (it
 455 * either does not exist on disk, or has a stale mtime and may be subject to
 456 * pruning).
 457 */
 458static int check_and_freshen_file(const char *fn, int freshen)
 459{
 460        if (access(fn, F_OK))
 461                return 0;
 462        if (freshen && !freshen_file(fn))
 463                return 0;
 464        return 1;
 465}
 466
 467static int check_and_freshen_local(const unsigned char *sha1, int freshen)
 468{
 469        return check_and_freshen_file(sha1_file_name(sha1), freshen);
 470}
 471
 472static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 473{
 474        struct alternate_object_database *alt;
 475        prepare_alt_odb();
 476        for (alt = alt_odb_list; alt; alt = alt->next) {
 477                fill_sha1_path(alt->name, sha1);
 478                if (check_and_freshen_file(alt->base, freshen))
 479                        return 1;
 480        }
 481        return 0;
 482}
 483
 484static int check_and_freshen(const unsigned char *sha1, int freshen)
 485{
 486        return check_and_freshen_local(sha1, freshen) ||
 487               check_and_freshen_nonlocal(sha1, freshen);
 488}
 489
 490int has_loose_object_nonlocal(const unsigned char *sha1)
 491{
 492        return check_and_freshen_nonlocal(sha1, 0);
 493}
 494
 495static int has_loose_object(const unsigned char *sha1)
 496{
 497        return check_and_freshen(sha1, 0);
 498}
 499
 500static unsigned int pack_used_ctr;
 501static unsigned int pack_mmap_calls;
 502static unsigned int peak_pack_open_windows;
 503static unsigned int pack_open_windows;
 504static unsigned int pack_open_fds;
 505static unsigned int pack_max_fds;
 506static size_t peak_pack_mapped;
 507static size_t pack_mapped;
 508struct packed_git *packed_git;
 509
 510void pack_report(void)
 511{
 512        fprintf(stderr,
 513                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 514                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 515                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 516                sz_fmt(getpagesize()),
 517                sz_fmt(packed_git_window_size),
 518                sz_fmt(packed_git_limit));
 519        fprintf(stderr,
 520                "pack_report: pack_used_ctr            = %10u\n"
 521                "pack_report: pack_mmap_calls          = %10u\n"
 522                "pack_report: pack_open_windows        = %10u / %10u\n"
 523                "pack_report: pack_mapped              = "
 524                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 525                pack_used_ctr,
 526                pack_mmap_calls,
 527                pack_open_windows, peak_pack_open_windows,
 528                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 529}
 530
 531/*
 532 * Open and mmap the index file at path, perform a couple of
 533 * consistency checks, then record its information to p.  Return 0 on
 534 * success.
 535 */
 536static int check_packed_git_idx(const char *path, struct packed_git *p)
 537{
 538        void *idx_map;
 539        struct pack_idx_header *hdr;
 540        size_t idx_size;
 541        uint32_t version, nr, i, *index;
 542        int fd = git_open_noatime(path);
 543        struct stat st;
 544
 545        if (fd < 0)
 546                return -1;
 547        if (fstat(fd, &st)) {
 548                close(fd);
 549                return -1;
 550        }
 551        idx_size = xsize_t(st.st_size);
 552        if (idx_size < 4 * 256 + 20 + 20) {
 553                close(fd);
 554                return error("index file %s is too small", path);
 555        }
 556        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 557        close(fd);
 558
 559        hdr = idx_map;
 560        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 561                version = ntohl(hdr->idx_version);
 562                if (version < 2 || version > 2) {
 563                        munmap(idx_map, idx_size);
 564                        return error("index file %s is version %"PRIu32
 565                                     " and is not supported by this binary"
 566                                     " (try upgrading GIT to a newer version)",
 567                                     path, version);
 568                }
 569        } else
 570                version = 1;
 571
 572        nr = 0;
 573        index = idx_map;
 574        if (version > 1)
 575                index += 2;  /* skip index header */
 576        for (i = 0; i < 256; i++) {
 577                uint32_t n = ntohl(index[i]);
 578                if (n < nr) {
 579                        munmap(idx_map, idx_size);
 580                        return error("non-monotonic index %s", path);
 581                }
 582                nr = n;
 583        }
 584
 585        if (version == 1) {
 586                /*
 587                 * Total size:
 588                 *  - 256 index entries 4 bytes each
 589                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 590                 *  - 20-byte SHA1 of the packfile
 591                 *  - 20-byte SHA1 file checksum
 592                 */
 593                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 594                        munmap(idx_map, idx_size);
 595                        return error("wrong index v1 file size in %s", path);
 596                }
 597        } else if (version == 2) {
 598                /*
 599                 * Minimum size:
 600                 *  - 8 bytes of header
 601                 *  - 256 index entries 4 bytes each
 602                 *  - 20-byte sha1 entry * nr
 603                 *  - 4-byte crc entry * nr
 604                 *  - 4-byte offset entry * nr
 605                 *  - 20-byte SHA1 of the packfile
 606                 *  - 20-byte SHA1 file checksum
 607                 * And after the 4-byte offset table might be a
 608                 * variable sized table containing 8-byte entries
 609                 * for offsets larger than 2^31.
 610                 */
 611                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 612                unsigned long max_size = min_size;
 613                if (nr)
 614                        max_size += (nr - 1)*8;
 615                if (idx_size < min_size || idx_size > max_size) {
 616                        munmap(idx_map, idx_size);
 617                        return error("wrong index v2 file size in %s", path);
 618                }
 619                if (idx_size != min_size &&
 620                    /*
 621                     * make sure we can deal with large pack offsets.
 622                     * 31-bit signed offset won't be enough, neither
 623                     * 32-bit unsigned one will be.
 624                     */
 625                    (sizeof(off_t) <= 4)) {
 626                        munmap(idx_map, idx_size);
 627                        return error("pack too large for current definition of off_t in %s", path);
 628                }
 629        }
 630
 631        p->index_version = version;
 632        p->index_data = idx_map;
 633        p->index_size = idx_size;
 634        p->num_objects = nr;
 635        return 0;
 636}
 637
 638int open_pack_index(struct packed_git *p)
 639{
 640        char *idx_name;
 641        int ret;
 642
 643        if (p->index_data)
 644                return 0;
 645
 646        idx_name = xstrdup(p->pack_name);
 647        strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 648        ret = check_packed_git_idx(idx_name, p);
 649        free(idx_name);
 650        return ret;
 651}
 652
 653static void scan_windows(struct packed_git *p,
 654        struct packed_git **lru_p,
 655        struct pack_window **lru_w,
 656        struct pack_window **lru_l)
 657{
 658        struct pack_window *w, *w_l;
 659
 660        for (w_l = NULL, w = p->windows; w; w = w->next) {
 661                if (!w->inuse_cnt) {
 662                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 663                                *lru_p = p;
 664                                *lru_w = w;
 665                                *lru_l = w_l;
 666                        }
 667                }
 668                w_l = w;
 669        }
 670}
 671
 672static int unuse_one_window(struct packed_git *current)
 673{
 674        struct packed_git *p, *lru_p = NULL;
 675        struct pack_window *lru_w = NULL, *lru_l = NULL;
 676
 677        if (current)
 678                scan_windows(current, &lru_p, &lru_w, &lru_l);
 679        for (p = packed_git; p; p = p->next)
 680                scan_windows(p, &lru_p, &lru_w, &lru_l);
 681        if (lru_p) {
 682                munmap(lru_w->base, lru_w->len);
 683                pack_mapped -= lru_w->len;
 684                if (lru_l)
 685                        lru_l->next = lru_w->next;
 686                else
 687                        lru_p->windows = lru_w->next;
 688                free(lru_w);
 689                pack_open_windows--;
 690                return 1;
 691        }
 692        return 0;
 693}
 694
 695void release_pack_memory(size_t need)
 696{
 697        size_t cur = pack_mapped;
 698        while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 699                ; /* nothing */
 700}
 701
 702static void mmap_limit_check(size_t length)
 703{
 704        static size_t limit = 0;
 705        if (!limit) {
 706                limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
 707                if (!limit)
 708                        limit = SIZE_MAX;
 709        }
 710        if (length > limit)
 711                die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
 712                    (uintmax_t)length, (uintmax_t)limit);
 713}
 714
 715void *xmmap_gently(void *start, size_t length,
 716                  int prot, int flags, int fd, off_t offset)
 717{
 718        void *ret;
 719
 720        mmap_limit_check(length);
 721        ret = mmap(start, length, prot, flags, fd, offset);
 722        if (ret == MAP_FAILED) {
 723                if (!length)
 724                        return NULL;
 725                release_pack_memory(length);
 726                ret = mmap(start, length, prot, flags, fd, offset);
 727        }
 728        return ret;
 729}
 730
 731void *xmmap(void *start, size_t length,
 732        int prot, int flags, int fd, off_t offset)
 733{
 734        void *ret = xmmap_gently(start, length, prot, flags, fd, offset);
 735        if (ret == MAP_FAILED)
 736                die_errno("mmap failed");
 737        return ret;
 738}
 739
 740void close_pack_windows(struct packed_git *p)
 741{
 742        while (p->windows) {
 743                struct pack_window *w = p->windows;
 744
 745                if (w->inuse_cnt)
 746                        die("pack '%s' still has open windows to it",
 747                            p->pack_name);
 748                munmap(w->base, w->len);
 749                pack_mapped -= w->len;
 750                pack_open_windows--;
 751                p->windows = w->next;
 752                free(w);
 753        }
 754}
 755
 756/*
 757 * The LRU pack is the one with the oldest MRU window, preferring packs
 758 * with no used windows, or the oldest mtime if it has no windows allocated.
 759 */
 760static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 761{
 762        struct pack_window *w, *this_mru_w;
 763        int has_windows_inuse = 0;
 764
 765        /*
 766         * Reject this pack if it has windows and the previously selected
 767         * one does not.  If this pack does not have windows, reject
 768         * it if the pack file is newer than the previously selected one.
 769         */
 770        if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 771                return;
 772
 773        for (w = this_mru_w = p->windows; w; w = w->next) {
 774                /*
 775                 * Reject this pack if any of its windows are in use,
 776                 * but the previously selected pack did not have any
 777                 * inuse windows.  Otherwise, record that this pack
 778                 * has windows in use.
 779                 */
 780                if (w->inuse_cnt) {
 781                        if (*accept_windows_inuse)
 782                                has_windows_inuse = 1;
 783                        else
 784                                return;
 785                }
 786
 787                if (w->last_used > this_mru_w->last_used)
 788                        this_mru_w = w;
 789
 790                /*
 791                 * Reject this pack if it has windows that have been
 792                 * used more recently than the previously selected pack.
 793                 * If the previously selected pack had windows inuse and
 794                 * we have not encountered a window in this pack that is
 795                 * inuse, skip this check since we prefer a pack with no
 796                 * inuse windows to one that has inuse windows.
 797                 */
 798                if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 799                    this_mru_w->last_used > (*mru_w)->last_used)
 800                        return;
 801        }
 802
 803        /*
 804         * Select this pack.
 805         */
 806        *mru_w = this_mru_w;
 807        *lru_p = p;
 808        *accept_windows_inuse = has_windows_inuse;
 809}
 810
 811static int close_one_pack(void)
 812{
 813        struct packed_git *p, *lru_p = NULL;
 814        struct pack_window *mru_w = NULL;
 815        int accept_windows_inuse = 1;
 816
 817        for (p = packed_git; p; p = p->next) {
 818                if (p->pack_fd == -1)
 819                        continue;
 820                find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 821        }
 822
 823        if (lru_p) {
 824                close(lru_p->pack_fd);
 825                pack_open_fds--;
 826                lru_p->pack_fd = -1;
 827                return 1;
 828        }
 829
 830        return 0;
 831}
 832
 833void unuse_pack(struct pack_window **w_cursor)
 834{
 835        struct pack_window *w = *w_cursor;
 836        if (w) {
 837                w->inuse_cnt--;
 838                *w_cursor = NULL;
 839        }
 840}
 841
 842void close_pack_index(struct packed_git *p)
 843{
 844        if (p->index_data) {
 845                munmap((void *)p->index_data, p->index_size);
 846                p->index_data = NULL;
 847        }
 848}
 849
 850/*
 851 * This is used by git-repack in case a newly created pack happens to
 852 * contain the same set of objects as an existing one.  In that case
 853 * the resulting file might be different even if its name would be the
 854 * same.  It is best to close any reference to the old pack before it is
 855 * replaced on disk.  Of course no index pointers or windows for given pack
 856 * must subsist at this point.  If ever objects from this pack are requested
 857 * again, the new version of the pack will be reinitialized through
 858 * reprepare_packed_git().
 859 */
 860void free_pack_by_name(const char *pack_name)
 861{
 862        struct packed_git *p, **pp = &packed_git;
 863
 864        while (*pp) {
 865                p = *pp;
 866                if (strcmp(pack_name, p->pack_name) == 0) {
 867                        clear_delta_base_cache();
 868                        close_pack_windows(p);
 869                        if (p->pack_fd != -1) {
 870                                close(p->pack_fd);
 871                                pack_open_fds--;
 872                        }
 873                        close_pack_index(p);
 874                        free(p->bad_object_sha1);
 875                        *pp = p->next;
 876                        if (last_found_pack == p)
 877                                last_found_pack = NULL;
 878                        free(p);
 879                        return;
 880                }
 881                pp = &p->next;
 882        }
 883}
 884
 885static unsigned int get_max_fd_limit(void)
 886{
 887#ifdef RLIMIT_NOFILE
 888        {
 889                struct rlimit lim;
 890
 891                if (!getrlimit(RLIMIT_NOFILE, &lim))
 892                        return lim.rlim_cur;
 893        }
 894#endif
 895
 896#ifdef _SC_OPEN_MAX
 897        {
 898                long open_max = sysconf(_SC_OPEN_MAX);
 899                if (0 < open_max)
 900                        return open_max;
 901                /*
 902                 * Otherwise, we got -1 for one of the two
 903                 * reasons:
 904                 *
 905                 * (1) sysconf() did not understand _SC_OPEN_MAX
 906                 *     and signaled an error with -1; or
 907                 * (2) sysconf() said there is no limit.
 908                 *
 909                 * We _could_ clear errno before calling sysconf() to
 910                 * tell these two cases apart and return a huge number
 911                 * in the latter case to let the caller cap it to a
 912                 * value that is not so selfish, but letting the
 913                 * fallback OPEN_MAX codepath take care of these cases
 914                 * is a lot simpler.
 915                 */
 916        }
 917#endif
 918
 919#ifdef OPEN_MAX
 920        return OPEN_MAX;
 921#else
 922        return 1; /* see the caller ;-) */
 923#endif
 924}
 925
 926/*
 927 * Do not call this directly as this leaks p->pack_fd on error return;
 928 * call open_packed_git() instead.
 929 */
 930static int open_packed_git_1(struct packed_git *p)
 931{
 932        struct stat st;
 933        struct pack_header hdr;
 934        unsigned char sha1[20];
 935        unsigned char *idx_sha1;
 936        long fd_flag;
 937
 938        if (!p->index_data && open_pack_index(p))
 939                return error("packfile %s index unavailable", p->pack_name);
 940
 941        if (!pack_max_fds) {
 942                unsigned int max_fds = get_max_fd_limit();
 943
 944                /* Save 3 for stdin/stdout/stderr, 22 for work */
 945                if (25 < max_fds)
 946                        pack_max_fds = max_fds - 25;
 947                else
 948                        pack_max_fds = 1;
 949        }
 950
 951        while (pack_max_fds <= pack_open_fds && close_one_pack())
 952                ; /* nothing */
 953
 954        p->pack_fd = git_open_noatime(p->pack_name);
 955        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 956                return -1;
 957        pack_open_fds++;
 958
 959        /* If we created the struct before we had the pack we lack size. */
 960        if (!p->pack_size) {
 961                if (!S_ISREG(st.st_mode))
 962                        return error("packfile %s not a regular file", p->pack_name);
 963                p->pack_size = st.st_size;
 964        } else if (p->pack_size != st.st_size)
 965                return error("packfile %s size changed", p->pack_name);
 966
 967        /* We leave these file descriptors open with sliding mmap;
 968         * there is no point keeping them open across exec(), though.
 969         */
 970        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 971        if (fd_flag < 0)
 972                return error("cannot determine file descriptor flags");
 973        fd_flag |= FD_CLOEXEC;
 974        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 975                return error("cannot set FD_CLOEXEC");
 976
 977        /* Verify we recognize this pack file format. */
 978        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 979                return error("file %s is far too short to be a packfile", p->pack_name);
 980        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 981                return error("file %s is not a GIT packfile", p->pack_name);
 982        if (!pack_version_ok(hdr.hdr_version))
 983                return error("packfile %s is version %"PRIu32" and not"
 984                        " supported (try upgrading GIT to a newer version)",
 985                        p->pack_name, ntohl(hdr.hdr_version));
 986
 987        /* Verify the pack matches its index. */
 988        if (p->num_objects != ntohl(hdr.hdr_entries))
 989                return error("packfile %s claims to have %"PRIu32" objects"
 990                             " while index indicates %"PRIu32" objects",
 991                             p->pack_name, ntohl(hdr.hdr_entries),
 992                             p->num_objects);
 993        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 994                return error("end of packfile %s is unavailable", p->pack_name);
 995        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 996                return error("packfile %s signature is unavailable", p->pack_name);
 997        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 998        if (hashcmp(sha1, idx_sha1))
 999                return error("packfile %s does not match index", p->pack_name);
1000        return 0;
1001}
1002
1003static int open_packed_git(struct packed_git *p)
1004{
1005        if (!open_packed_git_1(p))
1006                return 0;
1007        if (p->pack_fd != -1) {
1008                close(p->pack_fd);
1009                pack_open_fds--;
1010                p->pack_fd = -1;
1011        }
1012        return -1;
1013}
1014
1015static int in_window(struct pack_window *win, off_t offset)
1016{
1017        /* We must promise at least 20 bytes (one hash) after the
1018         * offset is available from this window, otherwise the offset
1019         * is not actually in this window and a different window (which
1020         * has that one hash excess) must be used.  This is to support
1021         * the object header and delta base parsing routines below.
1022         */
1023        off_t win_off = win->offset;
1024        return win_off <= offset
1025                && (offset + 20) <= (win_off + win->len);
1026}
1027
1028unsigned char *use_pack(struct packed_git *p,
1029                struct pack_window **w_cursor,
1030                off_t offset,
1031                unsigned long *left)
1032{
1033        struct pack_window *win = *w_cursor;
1034
1035        /* Since packfiles end in a hash of their content and it's
1036         * pointless to ask for an offset into the middle of that
1037         * hash, and the in_window function above wouldn't match
1038         * don't allow an offset too close to the end of the file.
1039         */
1040        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
1041                die("packfile %s cannot be accessed", p->pack_name);
1042        if (offset > (p->pack_size - 20))
1043                die("offset beyond end of packfile (truncated pack?)");
1044
1045        if (!win || !in_window(win, offset)) {
1046                if (win)
1047                        win->inuse_cnt--;
1048                for (win = p->windows; win; win = win->next) {
1049                        if (in_window(win, offset))
1050                                break;
1051                }
1052                if (!win) {
1053                        size_t window_align = packed_git_window_size / 2;
1054                        off_t len;
1055
1056                        if (p->pack_fd == -1 && open_packed_git(p))
1057                                die("packfile %s cannot be accessed", p->pack_name);
1058
1059                        win = xcalloc(1, sizeof(*win));
1060                        win->offset = (offset / window_align) * window_align;
1061                        len = p->pack_size - win->offset;
1062                        if (len > packed_git_window_size)
1063                                len = packed_git_window_size;
1064                        win->len = (size_t)len;
1065                        pack_mapped += win->len;
1066                        while (packed_git_limit < pack_mapped
1067                                && unuse_one_window(p))
1068                                ; /* nothing */
1069                        win->base = xmmap(NULL, win->len,
1070                                PROT_READ, MAP_PRIVATE,
1071                                p->pack_fd, win->offset);
1072                        if (win->base == MAP_FAILED)
1073                                die("packfile %s cannot be mapped: %s",
1074                                        p->pack_name,
1075                                        strerror(errno));
1076                        if (!win->offset && win->len == p->pack_size
1077                                && !p->do_not_close) {
1078                                close(p->pack_fd);
1079                                pack_open_fds--;
1080                                p->pack_fd = -1;
1081                        }
1082                        pack_mmap_calls++;
1083                        pack_open_windows++;
1084                        if (pack_mapped > peak_pack_mapped)
1085                                peak_pack_mapped = pack_mapped;
1086                        if (pack_open_windows > peak_pack_open_windows)
1087                                peak_pack_open_windows = pack_open_windows;
1088                        win->next = p->windows;
1089                        p->windows = win;
1090                }
1091        }
1092        if (win != *w_cursor) {
1093                win->last_used = pack_used_ctr++;
1094                win->inuse_cnt++;
1095                *w_cursor = win;
1096        }
1097        offset -= win->offset;
1098        if (left)
1099                *left = win->len - xsize_t(offset);
1100        return win->base + offset;
1101}
1102
1103static struct packed_git *alloc_packed_git(int extra)
1104{
1105        struct packed_git *p = xmalloc(sizeof(*p) + extra);
1106        memset(p, 0, sizeof(*p));
1107        p->pack_fd = -1;
1108        return p;
1109}
1110
1111static void try_to_free_pack_memory(size_t size)
1112{
1113        release_pack_memory(size);
1114}
1115
1116struct packed_git *add_packed_git(const char *path, int path_len, int local)
1117{
1118        static int have_set_try_to_free_routine;
1119        struct stat st;
1120        struct packed_git *p = alloc_packed_git(path_len + 2);
1121
1122        if (!have_set_try_to_free_routine) {
1123                have_set_try_to_free_routine = 1;
1124                set_try_to_free_routine(try_to_free_pack_memory);
1125        }
1126
1127        /*
1128         * Make sure a corresponding .pack file exists and that
1129         * the index looks sane.
1130         */
1131        path_len -= strlen(".idx");
1132        if (path_len < 1) {
1133                free(p);
1134                return NULL;
1135        }
1136        memcpy(p->pack_name, path, path_len);
1137
1138        strcpy(p->pack_name + path_len, ".keep");
1139        if (!access(p->pack_name, F_OK))
1140                p->pack_keep = 1;
1141
1142        strcpy(p->pack_name + path_len, ".pack");
1143        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
1144                free(p);
1145                return NULL;
1146        }
1147
1148        /* ok, it looks sane as far as we can check without
1149         * actually mapping the pack file.
1150         */
1151        p->pack_size = st.st_size;
1152        p->pack_local = local;
1153        p->mtime = st.st_mtime;
1154        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
1155                hashclr(p->sha1);
1156        return p;
1157}
1158
1159struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
1160{
1161        const char *path = sha1_pack_name(sha1);
1162        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
1163
1164        strcpy(p->pack_name, path);
1165        hashcpy(p->sha1, sha1);
1166        if (check_packed_git_idx(idx_path, p)) {
1167                free(p);
1168                return NULL;
1169        }
1170
1171        return p;
1172}
1173
1174void install_packed_git(struct packed_git *pack)
1175{
1176        if (pack->pack_fd != -1)
1177                pack_open_fds++;
1178
1179        pack->next = packed_git;
1180        packed_git = pack;
1181}
1182
1183void (*report_garbage)(const char *desc, const char *path);
1184
1185static void report_helper(const struct string_list *list,
1186                          int seen_bits, int first, int last)
1187{
1188        const char *msg;
1189        switch (seen_bits) {
1190        case 0:
1191                msg = "no corresponding .idx or .pack";
1192                break;
1193        case 1:
1194                msg = "no corresponding .idx";
1195                break;
1196        case 2:
1197                msg = "no corresponding .pack";
1198                break;
1199        default:
1200                return;
1201        }
1202        for (; first < last; first++)
1203                report_garbage(msg, list->items[first].string);
1204}
1205
1206static void report_pack_garbage(struct string_list *list)
1207{
1208        int i, baselen = -1, first = 0, seen_bits = 0;
1209
1210        if (!report_garbage)
1211                return;
1212
1213        string_list_sort(list);
1214
1215        for (i = 0; i < list->nr; i++) {
1216                const char *path = list->items[i].string;
1217                if (baselen != -1 &&
1218                    strncmp(path, list->items[first].string, baselen)) {
1219                        report_helper(list, seen_bits, first, i);
1220                        baselen = -1;
1221                        seen_bits = 0;
1222                }
1223                if (baselen == -1) {
1224                        const char *dot = strrchr(path, '.');
1225                        if (!dot) {
1226                                report_garbage("garbage found", path);
1227                                continue;
1228                        }
1229                        baselen = dot - path + 1;
1230                        first = i;
1231                }
1232                if (!strcmp(path + baselen, "pack"))
1233                        seen_bits |= 1;
1234                else if (!strcmp(path + baselen, "idx"))
1235                        seen_bits |= 2;
1236        }
1237        report_helper(list, seen_bits, first, list->nr);
1238}
1239
1240static void prepare_packed_git_one(char *objdir, int local)
1241{
1242        struct strbuf path = STRBUF_INIT;
1243        size_t dirnamelen;
1244        DIR *dir;
1245        struct dirent *de;
1246        struct string_list garbage = STRING_LIST_INIT_DUP;
1247
1248        strbuf_addstr(&path, objdir);
1249        strbuf_addstr(&path, "/pack");
1250        dir = opendir(path.buf);
1251        if (!dir) {
1252                if (errno != ENOENT)
1253                        error("unable to open object pack directory: %s: %s",
1254                              path.buf, strerror(errno));
1255                strbuf_release(&path);
1256                return;
1257        }
1258        strbuf_addch(&path, '/');
1259        dirnamelen = path.len;
1260        while ((de = readdir(dir)) != NULL) {
1261                struct packed_git *p;
1262                size_t base_len;
1263
1264                if (is_dot_or_dotdot(de->d_name))
1265                        continue;
1266
1267                strbuf_setlen(&path, dirnamelen);
1268                strbuf_addstr(&path, de->d_name);
1269
1270                base_len = path.len;
1271                if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
1272                        /* Don't reopen a pack we already have. */
1273                        for (p = packed_git; p; p = p->next) {
1274                                size_t len;
1275                                if (strip_suffix(p->pack_name, ".pack", &len) &&
1276                                    len == base_len &&
1277                                    !memcmp(p->pack_name, path.buf, len))
1278                                        break;
1279                        }
1280                        if (p == NULL &&
1281                            /*
1282                             * See if it really is a valid .idx file with
1283                             * corresponding .pack file that we can map.
1284                             */
1285                            (p = add_packed_git(path.buf, path.len, local)) != NULL)
1286                                install_packed_git(p);
1287                }
1288
1289                if (!report_garbage)
1290                        continue;
1291
1292                if (ends_with(de->d_name, ".idx") ||
1293                    ends_with(de->d_name, ".pack") ||
1294                    ends_with(de->d_name, ".bitmap") ||
1295                    ends_with(de->d_name, ".keep"))
1296                        string_list_append(&garbage, path.buf);
1297                else
1298                        report_garbage("garbage found", path.buf);
1299        }
1300        closedir(dir);
1301        report_pack_garbage(&garbage);
1302        string_list_clear(&garbage, 0);
1303        strbuf_release(&path);
1304}
1305
1306static int sort_pack(const void *a_, const void *b_)
1307{
1308        struct packed_git *a = *((struct packed_git **)a_);
1309        struct packed_git *b = *((struct packed_git **)b_);
1310        int st;
1311
1312        /*
1313         * Local packs tend to contain objects specific to our
1314         * variant of the project than remote ones.  In addition,
1315         * remote ones could be on a network mounted filesystem.
1316         * Favor local ones for these reasons.
1317         */
1318        st = a->pack_local - b->pack_local;
1319        if (st)
1320                return -st;
1321
1322        /*
1323         * Younger packs tend to contain more recent objects,
1324         * and more recent objects tend to get accessed more
1325         * often.
1326         */
1327        if (a->mtime < b->mtime)
1328                return 1;
1329        else if (a->mtime == b->mtime)
1330                return 0;
1331        return -1;
1332}
1333
1334static void rearrange_packed_git(void)
1335{
1336        struct packed_git **ary, *p;
1337        int i, n;
1338
1339        for (n = 0, p = packed_git; p; p = p->next)
1340                n++;
1341        if (n < 2)
1342                return;
1343
1344        /* prepare an array of packed_git for easier sorting */
1345        ary = xcalloc(n, sizeof(struct packed_git *));
1346        for (n = 0, p = packed_git; p; p = p->next)
1347                ary[n++] = p;
1348
1349        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1350
1351        /* link them back again */
1352        for (i = 0; i < n - 1; i++)
1353                ary[i]->next = ary[i + 1];
1354        ary[n - 1]->next = NULL;
1355        packed_git = ary[0];
1356
1357        free(ary);
1358}
1359
1360static int prepare_packed_git_run_once = 0;
1361void prepare_packed_git(void)
1362{
1363        struct alternate_object_database *alt;
1364
1365        if (prepare_packed_git_run_once)
1366                return;
1367        prepare_packed_git_one(get_object_directory(), 1);
1368        prepare_alt_odb();
1369        for (alt = alt_odb_list; alt; alt = alt->next) {
1370                alt->name[-1] = 0;
1371                prepare_packed_git_one(alt->base, 0);
1372                alt->name[-1] = '/';
1373        }
1374        rearrange_packed_git();
1375        prepare_packed_git_run_once = 1;
1376}
1377
1378void reprepare_packed_git(void)
1379{
1380        prepare_packed_git_run_once = 0;
1381        prepare_packed_git();
1382}
1383
1384static void mark_bad_packed_object(struct packed_git *p,
1385                                   const unsigned char *sha1)
1386{
1387        unsigned i;
1388        for (i = 0; i < p->num_bad_objects; i++)
1389                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1390                        return;
1391        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1392        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1393        p->num_bad_objects++;
1394}
1395
1396static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1397{
1398        struct packed_git *p;
1399        unsigned i;
1400
1401        for (p = packed_git; p; p = p->next)
1402                for (i = 0; i < p->num_bad_objects; i++)
1403                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1404                                return p;
1405        return NULL;
1406}
1407
1408/*
1409 * With an in-core object data in "map", rehash it to make sure the
1410 * object name actually matches "sha1" to detect object corruption.
1411 * With "map" == NULL, try reading the object named with "sha1" using
1412 * the streaming interface and rehash it to do the same.
1413 */
1414int check_sha1_signature(const unsigned char *sha1, void *map,
1415                         unsigned long size, const char *type)
1416{
1417        unsigned char real_sha1[20];
1418        enum object_type obj_type;
1419        struct git_istream *st;
1420        git_SHA_CTX c;
1421        char hdr[32];
1422        int hdrlen;
1423
1424        if (map) {
1425                hash_sha1_file(map, size, type, real_sha1);
1426                return hashcmp(sha1, real_sha1) ? -1 : 0;
1427        }
1428
1429        st = open_istream(sha1, &obj_type, &size, NULL);
1430        if (!st)
1431                return -1;
1432
1433        /* Generate the header */
1434        hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
1435
1436        /* Sha1.. */
1437        git_SHA1_Init(&c);
1438        git_SHA1_Update(&c, hdr, hdrlen);
1439        for (;;) {
1440                char buf[1024 * 16];
1441                ssize_t readlen = read_istream(st, buf, sizeof(buf));
1442
1443                if (readlen < 0) {
1444                        close_istream(st);
1445                        return -1;
1446                }
1447                if (!readlen)
1448                        break;
1449                git_SHA1_Update(&c, buf, readlen);
1450        }
1451        git_SHA1_Final(real_sha1, &c);
1452        close_istream(st);
1453        return hashcmp(sha1, real_sha1) ? -1 : 0;
1454}
1455
1456int git_open_noatime(const char *name)
1457{
1458        static int sha1_file_open_flag = O_NOATIME;
1459
1460        for (;;) {
1461                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1462                if (fd >= 0)
1463                        return fd;
1464
1465                /* Might the failure be due to O_NOATIME? */
1466                if (errno != ENOENT && sha1_file_open_flag) {
1467                        sha1_file_open_flag = 0;
1468                        continue;
1469                }
1470
1471                return -1;
1472        }
1473}
1474
1475static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
1476{
1477        struct alternate_object_database *alt;
1478
1479        if (!lstat(sha1_file_name(sha1), st))
1480                return 0;
1481
1482        prepare_alt_odb();
1483        errno = ENOENT;
1484        for (alt = alt_odb_list; alt; alt = alt->next) {
1485                fill_sha1_path(alt->name, sha1);
1486                if (!lstat(alt->base, st))
1487                        return 0;
1488        }
1489
1490        return -1;
1491}
1492
1493static int open_sha1_file(const unsigned char *sha1)
1494{
1495        int fd;
1496        struct alternate_object_database *alt;
1497        int most_interesting_errno;
1498
1499        fd = git_open_noatime(sha1_file_name(sha1));
1500        if (fd >= 0)
1501                return fd;
1502        most_interesting_errno = errno;
1503
1504        prepare_alt_odb();
1505        for (alt = alt_odb_list; alt; alt = alt->next) {
1506                fill_sha1_path(alt->name, sha1);
1507                fd = git_open_noatime(alt->base);
1508                if (fd >= 0)
1509                        return fd;
1510                if (most_interesting_errno == ENOENT)
1511                        most_interesting_errno = errno;
1512        }
1513        errno = most_interesting_errno;
1514        return -1;
1515}
1516
1517void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1518{
1519        void *map;
1520        int fd;
1521
1522        fd = open_sha1_file(sha1);
1523        map = NULL;
1524        if (fd >= 0) {
1525                struct stat st;
1526
1527                if (!fstat(fd, &st)) {
1528                        *size = xsize_t(st.st_size);
1529                        if (!*size) {
1530                                /* mmap() is forbidden on empty files */
1531                                error("object file %s is empty", sha1_file_name(sha1));
1532                                return NULL;
1533                        }
1534                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1535                }
1536                close(fd);
1537        }
1538        return map;
1539}
1540
1541unsigned long unpack_object_header_buffer(const unsigned char *buf,
1542                unsigned long len, enum object_type *type, unsigned long *sizep)
1543{
1544        unsigned shift;
1545        unsigned long size, c;
1546        unsigned long used = 0;
1547
1548        c = buf[used++];
1549        *type = (c >> 4) & 7;
1550        size = c & 15;
1551        shift = 4;
1552        while (c & 0x80) {
1553                if (len <= used || bitsizeof(long) <= shift) {
1554                        error("bad object header");
1555                        size = used = 0;
1556                        break;
1557                }
1558                c = buf[used++];
1559                size += (c & 0x7f) << shift;
1560                shift += 7;
1561        }
1562        *sizep = size;
1563        return used;
1564}
1565
1566int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1567{
1568        /* Get the data stream */
1569        memset(stream, 0, sizeof(*stream));
1570        stream->next_in = map;
1571        stream->avail_in = mapsize;
1572        stream->next_out = buffer;
1573        stream->avail_out = bufsiz;
1574
1575        git_inflate_init(stream);
1576        return git_inflate(stream, 0);
1577}
1578
1579static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1580{
1581        int bytes = strlen(buffer) + 1;
1582        unsigned char *buf = xmallocz(size);
1583        unsigned long n;
1584        int status = Z_OK;
1585
1586        n = stream->total_out - bytes;
1587        if (n > size)
1588                n = size;
1589        memcpy(buf, (char *) buffer + bytes, n);
1590        bytes = n;
1591        if (bytes <= size) {
1592                /*
1593                 * The above condition must be (bytes <= size), not
1594                 * (bytes < size).  In other words, even though we
1595                 * expect no more output and set avail_out to zero,
1596                 * the input zlib stream may have bytes that express
1597                 * "this concludes the stream", and we *do* want to
1598                 * eat that input.
1599                 *
1600                 * Otherwise we would not be able to test that we
1601                 * consumed all the input to reach the expected size;
1602                 * we also want to check that zlib tells us that all
1603                 * went well with status == Z_STREAM_END at the end.
1604                 */
1605                stream->next_out = buf + bytes;
1606                stream->avail_out = size - bytes;
1607                while (status == Z_OK)
1608                        status = git_inflate(stream, Z_FINISH);
1609        }
1610        if (status == Z_STREAM_END && !stream->avail_in) {
1611                git_inflate_end(stream);
1612                return buf;
1613        }
1614
1615        if (status < 0)
1616                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1617        else if (stream->avail_in)
1618                error("garbage at end of loose object '%s'",
1619                      sha1_to_hex(sha1));
1620        free(buf);
1621        return NULL;
1622}
1623
1624/*
1625 * We used to just use "sscanf()", but that's actually way
1626 * too permissive for what we want to check. So do an anal
1627 * object header parse by hand.
1628 */
1629int parse_sha1_header(const char *hdr, unsigned long *sizep)
1630{
1631        char type[10];
1632        int i;
1633        unsigned long size;
1634
1635        /*
1636         * The type can be at most ten bytes (including the
1637         * terminating '\0' that we add), and is followed by
1638         * a space.
1639         */
1640        i = 0;
1641        for (;;) {
1642                char c = *hdr++;
1643                if (c == ' ')
1644                        break;
1645                type[i++] = c;
1646                if (i >= sizeof(type))
1647                        return -1;
1648        }
1649        type[i] = 0;
1650
1651        /*
1652         * The length must follow immediately, and be in canonical
1653         * decimal format (ie "010" is not valid).
1654         */
1655        size = *hdr++ - '0';
1656        if (size > 9)
1657                return -1;
1658        if (size) {
1659                for (;;) {
1660                        unsigned long c = *hdr - '0';
1661                        if (c > 9)
1662                                break;
1663                        hdr++;
1664                        size = size * 10 + c;
1665                }
1666        }
1667        *sizep = size;
1668
1669        /*
1670         * The length must be followed by a zero byte
1671         */
1672        return *hdr ? -1 : type_from_string(type);
1673}
1674
1675static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1676{
1677        int ret;
1678        git_zstream stream;
1679        char hdr[8192];
1680
1681        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1682        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1683                return NULL;
1684
1685        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1686}
1687
1688unsigned long get_size_from_delta(struct packed_git *p,
1689                                  struct pack_window **w_curs,
1690                                  off_t curpos)
1691{
1692        const unsigned char *data;
1693        unsigned char delta_head[20], *in;
1694        git_zstream stream;
1695        int st;
1696
1697        memset(&stream, 0, sizeof(stream));
1698        stream.next_out = delta_head;
1699        stream.avail_out = sizeof(delta_head);
1700
1701        git_inflate_init(&stream);
1702        do {
1703                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1704                stream.next_in = in;
1705                st = git_inflate(&stream, Z_FINISH);
1706                curpos += stream.next_in - in;
1707        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1708                 stream.total_out < sizeof(delta_head));
1709        git_inflate_end(&stream);
1710        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1711                error("delta data unpack-initial failed");
1712                return 0;
1713        }
1714
1715        /* Examine the initial part of the delta to figure out
1716         * the result size.
1717         */
1718        data = delta_head;
1719
1720        /* ignore base size */
1721        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1722
1723        /* Read the result size */
1724        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1725}
1726
1727static off_t get_delta_base(struct packed_git *p,
1728                                    struct pack_window **w_curs,
1729                                    off_t *curpos,
1730                                    enum object_type type,
1731                                    off_t delta_obj_offset)
1732{
1733        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1734        off_t base_offset;
1735
1736        /* use_pack() assured us we have [base_info, base_info + 20)
1737         * as a range that we can look at without walking off the
1738         * end of the mapped window.  Its actually the hash size
1739         * that is assured.  An OFS_DELTA longer than the hash size
1740         * is stupid, as then a REF_DELTA would be smaller to store.
1741         */
1742        if (type == OBJ_OFS_DELTA) {
1743                unsigned used = 0;
1744                unsigned char c = base_info[used++];
1745                base_offset = c & 127;
1746                while (c & 128) {
1747                        base_offset += 1;
1748                        if (!base_offset || MSB(base_offset, 7))
1749                                return 0;  /* overflow */
1750                        c = base_info[used++];
1751                        base_offset = (base_offset << 7) + (c & 127);
1752                }
1753                base_offset = delta_obj_offset - base_offset;
1754                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1755                        return 0;  /* out of bound */
1756                *curpos += used;
1757        } else if (type == OBJ_REF_DELTA) {
1758                /* The base entry _must_ be in the same pack */
1759                base_offset = find_pack_entry_one(base_info, p);
1760                *curpos += 20;
1761        } else
1762                die("I am totally screwed");
1763        return base_offset;
1764}
1765
1766/*
1767 * Like get_delta_base above, but we return the sha1 instead of the pack
1768 * offset. This means it is cheaper for REF deltas (we do not have to do
1769 * the final object lookup), but more expensive for OFS deltas (we
1770 * have to load the revidx to convert the offset back into a sha1).
1771 */
1772static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1773                                                struct pack_window **w_curs,
1774                                                off_t curpos,
1775                                                enum object_type type,
1776                                                off_t delta_obj_offset)
1777{
1778        if (type == OBJ_REF_DELTA) {
1779                unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1780                return base;
1781        } else if (type == OBJ_OFS_DELTA) {
1782                struct revindex_entry *revidx;
1783                off_t base_offset = get_delta_base(p, w_curs, &curpos,
1784                                                   type, delta_obj_offset);
1785
1786                if (!base_offset)
1787                        return NULL;
1788
1789                revidx = find_pack_revindex(p, base_offset);
1790                if (!revidx)
1791                        return NULL;
1792
1793                return nth_packed_object_sha1(p, revidx->nr);
1794        } else
1795                return NULL;
1796}
1797
1798int unpack_object_header(struct packed_git *p,
1799                         struct pack_window **w_curs,
1800                         off_t *curpos,
1801                         unsigned long *sizep)
1802{
1803        unsigned char *base;
1804        unsigned long left;
1805        unsigned long used;
1806        enum object_type type;
1807
1808        /* use_pack() assures us we have [base, base + 20) available
1809         * as a range that we can look at.  (Its actually the hash
1810         * size that is assured.)  With our object header encoding
1811         * the maximum deflated object size is 2^137, which is just
1812         * insane, so we know won't exceed what we have been given.
1813         */
1814        base = use_pack(p, w_curs, *curpos, &left);
1815        used = unpack_object_header_buffer(base, left, &type, sizep);
1816        if (!used) {
1817                type = OBJ_BAD;
1818        } else
1819                *curpos += used;
1820
1821        return type;
1822}
1823
1824static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1825{
1826        int type;
1827        struct revindex_entry *revidx;
1828        const unsigned char *sha1;
1829        revidx = find_pack_revindex(p, obj_offset);
1830        if (!revidx)
1831                return OBJ_BAD;
1832        sha1 = nth_packed_object_sha1(p, revidx->nr);
1833        mark_bad_packed_object(p, sha1);
1834        type = sha1_object_info(sha1, NULL);
1835        if (type <= OBJ_NONE)
1836                return OBJ_BAD;
1837        return type;
1838}
1839
1840#define POI_STACK_PREALLOC 64
1841
1842static enum object_type packed_to_object_type(struct packed_git *p,
1843                                              off_t obj_offset,
1844                                              enum object_type type,
1845                                              struct pack_window **w_curs,
1846                                              off_t curpos)
1847{
1848        off_t small_poi_stack[POI_STACK_PREALLOC];
1849        off_t *poi_stack = small_poi_stack;
1850        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1851
1852        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1853                off_t base_offset;
1854                unsigned long size;
1855                /* Push the object we're going to leave behind */
1856                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1857                        poi_stack_alloc = alloc_nr(poi_stack_nr);
1858                        poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1859                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1860                } else {
1861                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1862                }
1863                poi_stack[poi_stack_nr++] = obj_offset;
1864                /* If parsing the base offset fails, just unwind */
1865                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1866                if (!base_offset)
1867                        goto unwind;
1868                curpos = obj_offset = base_offset;
1869                type = unpack_object_header(p, w_curs, &curpos, &size);
1870                if (type <= OBJ_NONE) {
1871                        /* If getting the base itself fails, we first
1872                         * retry the base, otherwise unwind */
1873                        type = retry_bad_packed_offset(p, base_offset);
1874                        if (type > OBJ_NONE)
1875                                goto out;
1876                        goto unwind;
1877                }
1878        }
1879
1880        switch (type) {
1881        case OBJ_BAD:
1882        case OBJ_COMMIT:
1883        case OBJ_TREE:
1884        case OBJ_BLOB:
1885        case OBJ_TAG:
1886                break;
1887        default:
1888                error("unknown object type %i at offset %"PRIuMAX" in %s",
1889                      type, (uintmax_t)obj_offset, p->pack_name);
1890                type = OBJ_BAD;
1891        }
1892
1893out:
1894        if (poi_stack != small_poi_stack)
1895                free(poi_stack);
1896        return type;
1897
1898unwind:
1899        while (poi_stack_nr) {
1900                obj_offset = poi_stack[--poi_stack_nr];
1901                type = retry_bad_packed_offset(p, obj_offset);
1902                if (type > OBJ_NONE)
1903                        goto out;
1904        }
1905        type = OBJ_BAD;
1906        goto out;
1907}
1908
1909static int packed_object_info(struct packed_git *p, off_t obj_offset,
1910                              struct object_info *oi)
1911{
1912        struct pack_window *w_curs = NULL;
1913        unsigned long size;
1914        off_t curpos = obj_offset;
1915        enum object_type type;
1916
1917        /*
1918         * We always get the representation type, but only convert it to
1919         * a "real" type later if the caller is interested.
1920         */
1921        type = unpack_object_header(p, &w_curs, &curpos, &size);
1922
1923        if (oi->sizep) {
1924                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1925                        off_t tmp_pos = curpos;
1926                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1927                                                           type, obj_offset);
1928                        if (!base_offset) {
1929                                type = OBJ_BAD;
1930                                goto out;
1931                        }
1932                        *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1933                        if (*oi->sizep == 0) {
1934                                type = OBJ_BAD;
1935                                goto out;
1936                        }
1937                } else {
1938                        *oi->sizep = size;
1939                }
1940        }
1941
1942        if (oi->disk_sizep) {
1943                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1944                *oi->disk_sizep = revidx[1].offset - obj_offset;
1945        }
1946
1947        if (oi->typep) {
1948                *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
1949                if (*oi->typep < 0) {
1950                        type = OBJ_BAD;
1951                        goto out;
1952                }
1953        }
1954
1955        if (oi->delta_base_sha1) {
1956                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1957                        const unsigned char *base;
1958
1959                        base = get_delta_base_sha1(p, &w_curs, curpos,
1960                                                   type, obj_offset);
1961                        if (!base) {
1962                                type = OBJ_BAD;
1963                                goto out;
1964                        }
1965
1966                        hashcpy(oi->delta_base_sha1, base);
1967                } else
1968                        hashclr(oi->delta_base_sha1);
1969        }
1970
1971out:
1972        unuse_pack(&w_curs);
1973        return type;
1974}
1975
1976static void *unpack_compressed_entry(struct packed_git *p,
1977                                    struct pack_window **w_curs,
1978                                    off_t curpos,
1979                                    unsigned long size)
1980{
1981        int st;
1982        git_zstream stream;
1983        unsigned char *buffer, *in;
1984
1985        buffer = xmallocz_gently(size);
1986        if (!buffer)
1987                return NULL;
1988        memset(&stream, 0, sizeof(stream));
1989        stream.next_out = buffer;
1990        stream.avail_out = size + 1;
1991
1992        git_inflate_init(&stream);
1993        do {
1994                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1995                stream.next_in = in;
1996                st = git_inflate(&stream, Z_FINISH);
1997                if (!stream.avail_out)
1998                        break; /* the payload is larger than it should be */
1999                curpos += stream.next_in - in;
2000        } while (st == Z_OK || st == Z_BUF_ERROR);
2001        git_inflate_end(&stream);
2002        if ((st != Z_STREAM_END) || stream.total_out != size) {
2003                free(buffer);
2004                return NULL;
2005        }
2006
2007        return buffer;
2008}
2009
2010#define MAX_DELTA_CACHE (256)
2011
2012static size_t delta_base_cached;
2013
2014static struct delta_base_cache_lru_list {
2015        struct delta_base_cache_lru_list *prev;
2016        struct delta_base_cache_lru_list *next;
2017} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
2018
2019static struct delta_base_cache_entry {
2020        struct delta_base_cache_lru_list lru;
2021        void *data;
2022        struct packed_git *p;
2023        off_t base_offset;
2024        unsigned long size;
2025        enum object_type type;
2026} delta_base_cache[MAX_DELTA_CACHE];
2027
2028static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
2029{
2030        unsigned long hash;
2031
2032        hash = (unsigned long)p + (unsigned long)base_offset;
2033        hash += (hash >> 8) + (hash >> 16);
2034        return hash % MAX_DELTA_CACHE;
2035}
2036
2037static struct delta_base_cache_entry *
2038get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
2039{
2040        unsigned long hash = pack_entry_hash(p, base_offset);
2041        return delta_base_cache + hash;
2042}
2043
2044static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
2045                                     struct packed_git *p, off_t base_offset)
2046{
2047        return (ent->data && ent->p == p && ent->base_offset == base_offset);
2048}
2049
2050static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
2051{
2052        struct delta_base_cache_entry *ent;
2053        ent = get_delta_base_cache_entry(p, base_offset);
2054        return eq_delta_base_cache_entry(ent, p, base_offset);
2055}
2056
2057static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
2058{
2059        ent->data = NULL;
2060        ent->lru.next->prev = ent->lru.prev;
2061        ent->lru.prev->next = ent->lru.next;
2062        delta_base_cached -= ent->size;
2063}
2064
2065static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
2066        unsigned long *base_size, enum object_type *type, int keep_cache)
2067{
2068        struct delta_base_cache_entry *ent;
2069        void *ret;
2070
2071        ent = get_delta_base_cache_entry(p, base_offset);
2072
2073        if (!eq_delta_base_cache_entry(ent, p, base_offset))
2074                return unpack_entry(p, base_offset, type, base_size);
2075
2076        ret = ent->data;
2077
2078        if (!keep_cache)
2079                clear_delta_base_cache_entry(ent);
2080        else
2081                ret = xmemdupz(ent->data, ent->size);
2082        *type = ent->type;
2083        *base_size = ent->size;
2084        return ret;
2085}
2086
2087static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
2088{
2089        if (ent->data) {
2090                free(ent->data);
2091                ent->data = NULL;
2092                ent->lru.next->prev = ent->lru.prev;
2093                ent->lru.prev->next = ent->lru.next;
2094                delta_base_cached -= ent->size;
2095        }
2096}
2097
2098void clear_delta_base_cache(void)
2099{
2100        unsigned long p;
2101        for (p = 0; p < MAX_DELTA_CACHE; p++)
2102                release_delta_base_cache(&delta_base_cache[p]);
2103}
2104
2105static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
2106        void *base, unsigned long base_size, enum object_type type)
2107{
2108        unsigned long hash = pack_entry_hash(p, base_offset);
2109        struct delta_base_cache_entry *ent = delta_base_cache + hash;
2110        struct delta_base_cache_lru_list *lru;
2111
2112        release_delta_base_cache(ent);
2113        delta_base_cached += base_size;
2114
2115        for (lru = delta_base_cache_lru.next;
2116             delta_base_cached > delta_base_cache_limit
2117             && lru != &delta_base_cache_lru;
2118             lru = lru->next) {
2119                struct delta_base_cache_entry *f = (void *)lru;
2120                if (f->type == OBJ_BLOB)
2121                        release_delta_base_cache(f);
2122        }
2123        for (lru = delta_base_cache_lru.next;
2124             delta_base_cached > delta_base_cache_limit
2125             && lru != &delta_base_cache_lru;
2126             lru = lru->next) {
2127                struct delta_base_cache_entry *f = (void *)lru;
2128                release_delta_base_cache(f);
2129        }
2130
2131        ent->p = p;
2132        ent->base_offset = base_offset;
2133        ent->type = type;
2134        ent->data = base;
2135        ent->size = base_size;
2136        ent->lru.next = &delta_base_cache_lru;
2137        ent->lru.prev = delta_base_cache_lru.prev;
2138        delta_base_cache_lru.prev->next = &ent->lru;
2139        delta_base_cache_lru.prev = &ent->lru;
2140}
2141
2142static void *read_object(const unsigned char *sha1, enum object_type *type,
2143                         unsigned long *size);
2144
2145static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
2146{
2147        static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
2148        trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
2149                         p->pack_name, (uintmax_t)obj_offset);
2150}
2151
2152int do_check_packed_object_crc;
2153
2154#define UNPACK_ENTRY_STACK_PREALLOC 64
2155struct unpack_entry_stack_ent {
2156        off_t obj_offset;
2157        off_t curpos;
2158        unsigned long size;
2159};
2160
2161void *unpack_entry(struct packed_git *p, off_t obj_offset,
2162                   enum object_type *final_type, unsigned long *final_size)
2163{
2164        struct pack_window *w_curs = NULL;
2165        off_t curpos = obj_offset;
2166        void *data = NULL;
2167        unsigned long size;
2168        enum object_type type;
2169        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2170        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2171        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2172        int base_from_cache = 0;
2173
2174        write_pack_access_log(p, obj_offset);
2175
2176        /* PHASE 1: drill down to the innermost base object */
2177        for (;;) {
2178                off_t base_offset;
2179                int i;
2180                struct delta_base_cache_entry *ent;
2181
2182                ent = get_delta_base_cache_entry(p, curpos);
2183                if (eq_delta_base_cache_entry(ent, p, curpos)) {
2184                        type = ent->type;
2185                        data = ent->data;
2186                        size = ent->size;
2187                        clear_delta_base_cache_entry(ent);
2188                        base_from_cache = 1;
2189                        break;
2190                }
2191
2192                if (do_check_packed_object_crc && p->index_version > 1) {
2193                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2194                        unsigned long len = revidx[1].offset - obj_offset;
2195                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2196                                const unsigned char *sha1 =
2197                                        nth_packed_object_sha1(p, revidx->nr);
2198                                error("bad packed object CRC for %s",
2199                                      sha1_to_hex(sha1));
2200                                mark_bad_packed_object(p, sha1);
2201                                unuse_pack(&w_curs);
2202                                return NULL;
2203                        }
2204                }
2205
2206                type = unpack_object_header(p, &w_curs, &curpos, &size);
2207                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2208                        break;
2209
2210                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2211                if (!base_offset) {
2212                        error("failed to validate delta base reference "
2213                              "at offset %"PRIuMAX" from %s",
2214                              (uintmax_t)curpos, p->pack_name);
2215                        /* bail to phase 2, in hopes of recovery */
2216                        data = NULL;
2217                        break;
2218                }
2219
2220                /* push object, proceed to base */
2221                if (delta_stack_nr >= delta_stack_alloc
2222                    && delta_stack == small_delta_stack) {
2223                        delta_stack_alloc = alloc_nr(delta_stack_nr);
2224                        delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2225                        memcpy(delta_stack, small_delta_stack,
2226                               sizeof(*delta_stack)*delta_stack_nr);
2227                } else {
2228                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2229                }
2230                i = delta_stack_nr++;
2231                delta_stack[i].obj_offset = obj_offset;
2232                delta_stack[i].curpos = curpos;
2233                delta_stack[i].size = size;
2234
2235                curpos = obj_offset = base_offset;
2236        }
2237
2238        /* PHASE 2: handle the base */
2239        switch (type) {
2240        case OBJ_OFS_DELTA:
2241        case OBJ_REF_DELTA:
2242                if (data)
2243                        die("BUG in unpack_entry: left loop at a valid delta");
2244                break;
2245        case OBJ_COMMIT:
2246        case OBJ_TREE:
2247        case OBJ_BLOB:
2248        case OBJ_TAG:
2249                if (!base_from_cache)
2250                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
2251                break;
2252        default:
2253                data = NULL;
2254                error("unknown object type %i at offset %"PRIuMAX" in %s",
2255                      type, (uintmax_t)obj_offset, p->pack_name);
2256        }
2257
2258        /* PHASE 3: apply deltas in order */
2259
2260        /* invariants:
2261         *   'data' holds the base data, or NULL if there was corruption
2262         */
2263        while (delta_stack_nr) {
2264                void *delta_data;
2265                void *base = data;
2266                unsigned long delta_size, base_size = size;
2267                int i;
2268
2269                data = NULL;
2270
2271                if (base)
2272                        add_delta_base_cache(p, obj_offset, base, base_size, type);
2273
2274                if (!base) {
2275                        /*
2276                         * We're probably in deep shit, but let's try to fetch
2277                         * the required base anyway from another pack or loose.
2278                         * This is costly but should happen only in the presence
2279                         * of a corrupted pack, and is better than failing outright.
2280                         */
2281                        struct revindex_entry *revidx;
2282                        const unsigned char *base_sha1;
2283                        revidx = find_pack_revindex(p, obj_offset);
2284                        if (revidx) {
2285                                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2286                                error("failed to read delta base object %s"
2287                                      " at offset %"PRIuMAX" from %s",
2288                                      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2289                                      p->pack_name);
2290                                mark_bad_packed_object(p, base_sha1);
2291                                base = read_object(base_sha1, &type, &base_size);
2292                        }
2293                }
2294
2295                i = --delta_stack_nr;
2296                obj_offset = delta_stack[i].obj_offset;
2297                curpos = delta_stack[i].curpos;
2298                delta_size = delta_stack[i].size;
2299
2300                if (!base)
2301                        continue;
2302
2303                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2304
2305                if (!delta_data) {
2306                        error("failed to unpack compressed delta "
2307                              "at offset %"PRIuMAX" from %s",
2308                              (uintmax_t)curpos, p->pack_name);
2309                        data = NULL;
2310                        continue;
2311                }
2312
2313                data = patch_delta(base, base_size,
2314                                   delta_data, delta_size,
2315                                   &size);
2316
2317                /*
2318                 * We could not apply the delta; warn the user, but keep going.
2319                 * Our failure will be noticed either in the next iteration of
2320                 * the loop, or if this is the final delta, in the caller when
2321                 * we return NULL. Those code paths will take care of making
2322                 * a more explicit warning and retrying with another copy of
2323                 * the object.
2324                 */
2325                if (!data)
2326                        error("failed to apply delta");
2327
2328                free(delta_data);
2329        }
2330
2331        *final_type = type;
2332        *final_size = size;
2333
2334        unuse_pack(&w_curs);
2335
2336        if (delta_stack != small_delta_stack)
2337                free(delta_stack);
2338
2339        return data;
2340}
2341
2342const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2343                                            uint32_t n)
2344{
2345        const unsigned char *index = p->index_data;
2346        if (!index) {
2347                if (open_pack_index(p))
2348                        return NULL;
2349                index = p->index_data;
2350        }
2351        if (n >= p->num_objects)
2352                return NULL;
2353        index += 4 * 256;
2354        if (p->index_version == 1) {
2355                return index + 24 * n + 4;
2356        } else {
2357                index += 8;
2358                return index + 20 * n;
2359        }
2360}
2361
2362void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
2363{
2364        const unsigned char *ptr = vptr;
2365        const unsigned char *start = p->index_data;
2366        const unsigned char *end = start + p->index_size;
2367        if (ptr < start)
2368                die("offset before start of pack index for %s (corrupt index?)",
2369                    p->pack_name);
2370        /* No need to check for underflow; .idx files must be at least 8 bytes */
2371        if (ptr >= end - 8)
2372                die("offset beyond end of pack index for %s (truncated index?)",
2373                    p->pack_name);
2374}
2375
2376off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2377{
2378        const unsigned char *index = p->index_data;
2379        index += 4 * 256;
2380        if (p->index_version == 1) {
2381                return ntohl(*((uint32_t *)(index + 24 * n)));
2382        } else {
2383                uint32_t off;
2384                index += 8 + p->num_objects * (20 + 4);
2385                off = ntohl(*((uint32_t *)(index + 4 * n)));
2386                if (!(off & 0x80000000))
2387                        return off;
2388                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2389                check_pack_index_ptr(p, index);
2390                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2391                                   ntohl(*((uint32_t *)(index + 4)));
2392        }
2393}
2394
2395off_t find_pack_entry_one(const unsigned char *sha1,
2396                                  struct packed_git *p)
2397{
2398        const uint32_t *level1_ofs = p->index_data;
2399        const unsigned char *index = p->index_data;
2400        unsigned hi, lo, stride;
2401        static int use_lookup = -1;
2402        static int debug_lookup = -1;
2403
2404        if (debug_lookup < 0)
2405                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2406
2407        if (!index) {
2408                if (open_pack_index(p))
2409                        return 0;
2410                level1_ofs = p->index_data;
2411                index = p->index_data;
2412        }
2413        if (p->index_version > 1) {
2414                level1_ofs += 2;
2415                index += 8;
2416        }
2417        index += 4 * 256;
2418        hi = ntohl(level1_ofs[*sha1]);
2419        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2420        if (p->index_version > 1) {
2421                stride = 20;
2422        } else {
2423                stride = 24;
2424                index += 4;
2425        }
2426
2427        if (debug_lookup)
2428                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2429                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2430
2431        if (use_lookup < 0)
2432                use_lookup = !!getenv("GIT_USE_LOOKUP");
2433        if (use_lookup) {
2434                int pos = sha1_entry_pos(index, stride, 0,
2435                                         lo, hi, p->num_objects, sha1);
2436                if (pos < 0)
2437                        return 0;
2438                return nth_packed_object_offset(p, pos);
2439        }
2440
2441        do {
2442                unsigned mi = (lo + hi) / 2;
2443                int cmp = hashcmp(index + mi * stride, sha1);
2444
2445                if (debug_lookup)
2446                        printf("lo %u hi %u rg %u mi %u\n",
2447                               lo, hi, hi - lo, mi);
2448                if (!cmp)
2449                        return nth_packed_object_offset(p, mi);
2450                if (cmp > 0)
2451                        hi = mi;
2452                else
2453                        lo = mi+1;
2454        } while (lo < hi);
2455        return 0;
2456}
2457
2458int is_pack_valid(struct packed_git *p)
2459{
2460        /* An already open pack is known to be valid. */
2461        if (p->pack_fd != -1)
2462                return 1;
2463
2464        /* If the pack has one window completely covering the
2465         * file size, the pack is known to be valid even if
2466         * the descriptor is not currently open.
2467         */
2468        if (p->windows) {
2469                struct pack_window *w = p->windows;
2470
2471                if (!w->offset && w->len == p->pack_size)
2472                        return 1;
2473        }
2474
2475        /* Force the pack to open to prove its valid. */
2476        return !open_packed_git(p);
2477}
2478
2479static int fill_pack_entry(const unsigned char *sha1,
2480                           struct pack_entry *e,
2481                           struct packed_git *p)
2482{
2483        off_t offset;
2484
2485        if (p->num_bad_objects) {
2486                unsigned i;
2487                for (i = 0; i < p->num_bad_objects; i++)
2488                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2489                                return 0;
2490        }
2491
2492        offset = find_pack_entry_one(sha1, p);
2493        if (!offset)
2494                return 0;
2495
2496        /*
2497         * We are about to tell the caller where they can locate the
2498         * requested object.  We better make sure the packfile is
2499         * still here and can be accessed before supplying that
2500         * answer, as it may have been deleted since the index was
2501         * loaded!
2502         */
2503        if (!is_pack_valid(p))
2504                return 0;
2505        e->offset = offset;
2506        e->p = p;
2507        hashcpy(e->sha1, sha1);
2508        return 1;
2509}
2510
2511/*
2512 * Iff a pack file contains the object named by sha1, return true and
2513 * store its location to e.
2514 */
2515static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2516{
2517        struct packed_git *p;
2518
2519        prepare_packed_git();
2520        if (!packed_git)
2521                return 0;
2522
2523        if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2524                return 1;
2525
2526        for (p = packed_git; p; p = p->next) {
2527                if (p == last_found_pack)
2528                        continue; /* we already checked this one */
2529
2530                if (fill_pack_entry(sha1, e, p)) {
2531                        last_found_pack = p;
2532                        return 1;
2533                }
2534        }
2535        return 0;
2536}
2537
2538struct packed_git *find_sha1_pack(const unsigned char *sha1,
2539                                  struct packed_git *packs)
2540{
2541        struct packed_git *p;
2542
2543        for (p = packs; p; p = p->next) {
2544                if (find_pack_entry_one(sha1, p))
2545                        return p;
2546        }
2547        return NULL;
2548
2549}
2550
2551static int sha1_loose_object_info(const unsigned char *sha1,
2552                                  struct object_info *oi)
2553{
2554        int status;
2555        unsigned long mapsize, size;
2556        void *map;
2557        git_zstream stream;
2558        char hdr[32];
2559
2560        if (oi->delta_base_sha1)
2561                hashclr(oi->delta_base_sha1);
2562
2563        /*
2564         * If we don't care about type or size, then we don't
2565         * need to look inside the object at all. Note that we
2566         * do not optimize out the stat call, even if the
2567         * caller doesn't care about the disk-size, since our
2568         * return value implicitly indicates whether the
2569         * object even exists.
2570         */
2571        if (!oi->typep && !oi->sizep) {
2572                struct stat st;
2573                if (stat_sha1_file(sha1, &st) < 0)
2574                        return -1;
2575                if (oi->disk_sizep)
2576                        *oi->disk_sizep = st.st_size;
2577                return 0;
2578        }
2579
2580        map = map_sha1_file(sha1, &mapsize);
2581        if (!map)
2582                return -1;
2583        if (oi->disk_sizep)
2584                *oi->disk_sizep = mapsize;
2585        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2586                status = error("unable to unpack %s header",
2587                               sha1_to_hex(sha1));
2588        else if ((status = parse_sha1_header(hdr, &size)) < 0)
2589                status = error("unable to parse %s header", sha1_to_hex(sha1));
2590        else if (oi->sizep)
2591                *oi->sizep = size;
2592        git_inflate_end(&stream);
2593        munmap(map, mapsize);
2594        if (oi->typep)
2595                *oi->typep = status;
2596        return 0;
2597}
2598
2599int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
2600{
2601        struct cached_object *co;
2602        struct pack_entry e;
2603        int rtype;
2604        const unsigned char *real = lookup_replace_object_extended(sha1, flags);
2605
2606        co = find_cached_object(real);
2607        if (co) {
2608                if (oi->typep)
2609                        *(oi->typep) = co->type;
2610                if (oi->sizep)
2611                        *(oi->sizep) = co->size;
2612                if (oi->disk_sizep)
2613                        *(oi->disk_sizep) = 0;
2614                if (oi->delta_base_sha1)
2615                        hashclr(oi->delta_base_sha1);
2616                oi->whence = OI_CACHED;
2617                return 0;
2618        }
2619
2620        if (!find_pack_entry(real, &e)) {
2621                /* Most likely it's a loose object. */
2622                if (!sha1_loose_object_info(real, oi)) {
2623                        oi->whence = OI_LOOSE;
2624                        return 0;
2625                }
2626
2627                /* Not a loose object; someone else may have just packed it. */
2628                reprepare_packed_git();
2629                if (!find_pack_entry(real, &e))
2630                        return -1;
2631        }
2632
2633        rtype = packed_object_info(e.p, e.offset, oi);
2634        if (rtype < 0) {
2635                mark_bad_packed_object(e.p, real);
2636                return sha1_object_info_extended(real, oi, 0);
2637        } else if (in_delta_base_cache(e.p, e.offset)) {
2638                oi->whence = OI_DBCACHED;
2639        } else {
2640                oi->whence = OI_PACKED;
2641                oi->u.packed.offset = e.offset;
2642                oi->u.packed.pack = e.p;
2643                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2644                                         rtype == OBJ_OFS_DELTA);
2645        }
2646
2647        return 0;
2648}
2649
2650/* returns enum object_type or negative */
2651int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2652{
2653        enum object_type type;
2654        struct object_info oi = {NULL};
2655
2656        oi.typep = &type;
2657        oi.sizep = sizep;
2658        if (sha1_object_info_extended(sha1, &oi, LOOKUP_REPLACE_OBJECT) < 0)
2659                return -1;
2660        return type;
2661}
2662
2663static void *read_packed_sha1(const unsigned char *sha1,
2664                              enum object_type *type, unsigned long *size)
2665{
2666        struct pack_entry e;
2667        void *data;
2668
2669        if (!find_pack_entry(sha1, &e))
2670                return NULL;
2671        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2672        if (!data) {
2673                /*
2674                 * We're probably in deep shit, but let's try to fetch
2675                 * the required object anyway from another pack or loose.
2676                 * This should happen only in the presence of a corrupted
2677                 * pack, and is better than failing outright.
2678                 */
2679                error("failed to read object %s at offset %"PRIuMAX" from %s",
2680                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2681                mark_bad_packed_object(e.p, sha1);
2682                data = read_object(sha1, type, size);
2683        }
2684        return data;
2685}
2686
2687int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2688                      unsigned char *sha1)
2689{
2690        struct cached_object *co;
2691
2692        hash_sha1_file(buf, len, typename(type), sha1);
2693        if (has_sha1_file(sha1) || find_cached_object(sha1))
2694                return 0;
2695        ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
2696        co = &cached_objects[cached_object_nr++];
2697        co->size = len;
2698        co->type = type;
2699        co->buf = xmalloc(len);
2700        memcpy(co->buf, buf, len);
2701        hashcpy(co->sha1, sha1);
2702        return 0;
2703}
2704
2705static void *read_object(const unsigned char *sha1, enum object_type *type,
2706                         unsigned long *size)
2707{
2708        unsigned long mapsize;
2709        void *map, *buf;
2710        struct cached_object *co;
2711
2712        co = find_cached_object(sha1);
2713        if (co) {
2714                *type = co->type;
2715                *size = co->size;
2716                return xmemdupz(co->buf, co->size);
2717        }
2718
2719        buf = read_packed_sha1(sha1, type, size);
2720        if (buf)
2721                return buf;
2722        map = map_sha1_file(sha1, &mapsize);
2723        if (map) {
2724                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2725                munmap(map, mapsize);
2726                return buf;
2727        }
2728        reprepare_packed_git();
2729        return read_packed_sha1(sha1, type, size);
2730}
2731
2732/*
2733 * This function dies on corrupt objects; the callers who want to
2734 * deal with them should arrange to call read_object() and give error
2735 * messages themselves.
2736 */
2737void *read_sha1_file_extended(const unsigned char *sha1,
2738                              enum object_type *type,
2739                              unsigned long *size,
2740                              unsigned flag)
2741{
2742        void *data;
2743        const struct packed_git *p;
2744        const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
2745
2746        errno = 0;
2747        data = read_object(repl, type, size);
2748        if (data)
2749                return data;
2750
2751        if (errno && errno != ENOENT)
2752                die_errno("failed to read object %s", sha1_to_hex(sha1));
2753
2754        /* die if we replaced an object with one that does not exist */
2755        if (repl != sha1)
2756                die("replacement %s not found for %s",
2757                    sha1_to_hex(repl), sha1_to_hex(sha1));
2758
2759        if (has_loose_object(repl)) {
2760                const char *path = sha1_file_name(sha1);
2761
2762                die("loose object %s (stored in %s) is corrupt",
2763                    sha1_to_hex(repl), path);
2764        }
2765
2766        if ((p = has_packed_and_bad(repl)) != NULL)
2767                die("packed object %s (stored in %s) is corrupt",
2768                    sha1_to_hex(repl), p->pack_name);
2769
2770        return NULL;
2771}
2772
2773void *read_object_with_reference(const unsigned char *sha1,
2774                                 const char *required_type_name,
2775                                 unsigned long *size,
2776                                 unsigned char *actual_sha1_return)
2777{
2778        enum object_type type, required_type;
2779        void *buffer;
2780        unsigned long isize;
2781        unsigned char actual_sha1[20];
2782
2783        required_type = type_from_string(required_type_name);
2784        hashcpy(actual_sha1, sha1);
2785        while (1) {
2786                int ref_length = -1;
2787                const char *ref_type = NULL;
2788
2789                buffer = read_sha1_file(actual_sha1, &type, &isize);
2790                if (!buffer)
2791                        return NULL;
2792                if (type == required_type) {
2793                        *size = isize;
2794                        if (actual_sha1_return)
2795                                hashcpy(actual_sha1_return, actual_sha1);
2796                        return buffer;
2797                }
2798                /* Handle references */
2799                else if (type == OBJ_COMMIT)
2800                        ref_type = "tree ";
2801                else if (type == OBJ_TAG)
2802                        ref_type = "object ";
2803                else {
2804                        free(buffer);
2805                        return NULL;
2806                }
2807                ref_length = strlen(ref_type);
2808
2809                if (ref_length + 40 > isize ||
2810                    memcmp(buffer, ref_type, ref_length) ||
2811                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2812                        free(buffer);
2813                        return NULL;
2814                }
2815                free(buffer);
2816                /* Now we have the ID of the referred-to object in
2817                 * actual_sha1.  Check again. */
2818        }
2819}
2820
2821static void write_sha1_file_prepare(const void *buf, unsigned long len,
2822                                    const char *type, unsigned char *sha1,
2823                                    char *hdr, int *hdrlen)
2824{
2825        git_SHA_CTX c;
2826
2827        /* Generate the header */
2828        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2829
2830        /* Sha1.. */
2831        git_SHA1_Init(&c);
2832        git_SHA1_Update(&c, hdr, *hdrlen);
2833        git_SHA1_Update(&c, buf, len);
2834        git_SHA1_Final(sha1, &c);
2835}
2836
2837/*
2838 * Move the just written object into its final resting place.
2839 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2840 * "moving" is only a part of what it does, when no patch between
2841 * master to pu changes the call sites of this function.
2842 */
2843int move_temp_to_file(const char *tmpfile, const char *filename)
2844{
2845        int ret = 0;
2846
2847        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2848                goto try_rename;
2849        else if (link(tmpfile, filename))
2850                ret = errno;
2851
2852        /*
2853         * Coda hack - coda doesn't like cross-directory links,
2854         * so we fall back to a rename, which will mean that it
2855         * won't be able to check collisions, but that's not a
2856         * big deal.
2857         *
2858         * The same holds for FAT formatted media.
2859         *
2860         * When this succeeds, we just return.  We have nothing
2861         * left to unlink.
2862         */
2863        if (ret && ret != EEXIST) {
2864        try_rename:
2865                if (!rename(tmpfile, filename))
2866                        goto out;
2867                ret = errno;
2868        }
2869        unlink_or_warn(tmpfile);
2870        if (ret) {
2871                if (ret != EEXIST) {
2872                        return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2873                }
2874                /* FIXME!!! Collision check here ? */
2875        }
2876
2877out:
2878        if (adjust_shared_perm(filename))
2879                return error("unable to set permission to '%s'", filename);
2880        return 0;
2881}
2882
2883static int write_buffer(int fd, const void *buf, size_t len)
2884{
2885        if (write_in_full(fd, buf, len) < 0)
2886                return error("file write error (%s)", strerror(errno));
2887        return 0;
2888}
2889
2890int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2891                   unsigned char *sha1)
2892{
2893        char hdr[32];
2894        int hdrlen;
2895        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2896        return 0;
2897}
2898
2899/* Finalize a file on disk, and close it. */
2900static void close_sha1_file(int fd)
2901{
2902        if (fsync_object_files)
2903                fsync_or_die(fd, "sha1 file");
2904        if (close(fd) != 0)
2905                die_errno("error when closing sha1 file");
2906}
2907
2908/* Size of directory component, including the ending '/' */
2909static inline int directory_size(const char *filename)
2910{
2911        const char *s = strrchr(filename, '/');
2912        if (!s)
2913                return 0;
2914        return s - filename + 1;
2915}
2916
2917/*
2918 * This creates a temporary file in the same directory as the final
2919 * 'filename'
2920 *
2921 * We want to avoid cross-directory filename renames, because those
2922 * can have problems on various filesystems (FAT, NFS, Coda).
2923 */
2924static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2925{
2926        int fd, dirlen = directory_size(filename);
2927
2928        if (dirlen + 20 > bufsiz) {
2929                errno = ENAMETOOLONG;
2930                return -1;
2931        }
2932        memcpy(buffer, filename, dirlen);
2933        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2934        fd = git_mkstemp_mode(buffer, 0444);
2935        if (fd < 0 && dirlen && errno == ENOENT) {
2936                /* Make sure the directory exists */
2937                memcpy(buffer, filename, dirlen);
2938                buffer[dirlen-1] = 0;
2939                if (mkdir(buffer, 0777) && errno != EEXIST)
2940                        return -1;
2941                if (adjust_shared_perm(buffer))
2942                        return -1;
2943
2944                /* Try again */
2945                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2946                fd = git_mkstemp_mode(buffer, 0444);
2947        }
2948        return fd;
2949}
2950
2951static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2952                              const void *buf, unsigned long len, time_t mtime)
2953{
2954        int fd, ret;
2955        unsigned char compressed[4096];
2956        git_zstream stream;
2957        git_SHA_CTX c;
2958        unsigned char parano_sha1[20];
2959        static char tmp_file[PATH_MAX];
2960        const char *filename = sha1_file_name(sha1);
2961
2962        fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2963        if (fd < 0) {
2964                if (errno == EACCES)
2965                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
2966                else
2967                        return error("unable to create temporary file: %s", strerror(errno));
2968        }
2969
2970        /* Set it up */
2971        git_deflate_init(&stream, zlib_compression_level);
2972        stream.next_out = compressed;
2973        stream.avail_out = sizeof(compressed);
2974        git_SHA1_Init(&c);
2975
2976        /* First header.. */
2977        stream.next_in = (unsigned char *)hdr;
2978        stream.avail_in = hdrlen;
2979        while (git_deflate(&stream, 0) == Z_OK)
2980                ; /* nothing */
2981        git_SHA1_Update(&c, hdr, hdrlen);
2982
2983        /* Then the data itself.. */
2984        stream.next_in = (void *)buf;
2985        stream.avail_in = len;
2986        do {
2987                unsigned char *in0 = stream.next_in;
2988                ret = git_deflate(&stream, Z_FINISH);
2989                git_SHA1_Update(&c, in0, stream.next_in - in0);
2990                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2991                        die("unable to write sha1 file");
2992                stream.next_out = compressed;
2993                stream.avail_out = sizeof(compressed);
2994        } while (ret == Z_OK);
2995
2996        if (ret != Z_STREAM_END)
2997                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2998        ret = git_deflate_end_gently(&stream);
2999        if (ret != Z_OK)
3000                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
3001        git_SHA1_Final(parano_sha1, &c);
3002        if (hashcmp(sha1, parano_sha1) != 0)
3003                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
3004
3005        close_sha1_file(fd);
3006
3007        if (mtime) {
3008                struct utimbuf utb;
3009                utb.actime = mtime;
3010                utb.modtime = mtime;
3011                if (utime(tmp_file, &utb) < 0)
3012                        warning("failed utime() on %s: %s",
3013                                tmp_file, strerror(errno));
3014        }
3015
3016        return move_temp_to_file(tmp_file, filename);
3017}
3018
3019static int freshen_loose_object(const unsigned char *sha1)
3020{
3021        return check_and_freshen(sha1, 1);
3022}
3023
3024static int freshen_packed_object(const unsigned char *sha1)
3025{
3026        struct pack_entry e;
3027        if (!find_pack_entry(sha1, &e))
3028                return 0;
3029        if (e.p->freshened)
3030                return 1;
3031        if (!freshen_file(e.p->pack_name))
3032                return 0;
3033        e.p->freshened = 1;
3034        return 1;
3035}
3036
3037int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
3038{
3039        char hdr[32];
3040        int hdrlen;
3041
3042        /* Normally if we have it in the pack then we do not bother writing
3043         * it out into .git/objects/??/?{38} file.
3044         */
3045        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
3046        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3047                return 0;
3048        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
3049}
3050
3051int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
3052                             unsigned char *sha1, unsigned flags)
3053{
3054        char *header;
3055        int hdrlen, status = 0;
3056
3057        /* type string, SP, %lu of the length plus NUL must fit this */
3058        header = xmalloc(strlen(type) + 32);
3059        write_sha1_file_prepare(buf, len, type, sha1, header, &hdrlen);
3060
3061        if (!(flags & HASH_WRITE_OBJECT))
3062                goto cleanup;
3063        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3064                goto cleanup;
3065        status = write_loose_object(sha1, header, hdrlen, buf, len, 0);
3066
3067cleanup:
3068        free(header);
3069        return status;
3070}
3071
3072int force_object_loose(const unsigned char *sha1, time_t mtime)
3073{
3074        void *buf;
3075        unsigned long len;
3076        enum object_type type;
3077        char hdr[32];
3078        int hdrlen;
3079        int ret;
3080
3081        if (has_loose_object(sha1))
3082                return 0;
3083        buf = read_packed_sha1(sha1, &type, &len);
3084        if (!buf)
3085                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
3086        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
3087        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
3088        free(buf);
3089
3090        return ret;
3091}
3092
3093int has_pack_index(const unsigned char *sha1)
3094{
3095        struct stat st;
3096        if (stat(sha1_pack_index_name(sha1), &st))
3097                return 0;
3098        return 1;
3099}
3100
3101int has_sha1_pack(const unsigned char *sha1)
3102{
3103        struct pack_entry e;
3104        return find_pack_entry(sha1, &e);
3105}
3106
3107int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
3108{
3109        struct pack_entry e;
3110
3111        if (find_pack_entry(sha1, &e))
3112                return 1;
3113        if (has_loose_object(sha1))
3114                return 1;
3115        if (flags & HAS_SHA1_QUICK)
3116                return 0;
3117        reprepare_packed_git();
3118        return find_pack_entry(sha1, &e);
3119}
3120
3121static void check_tree(const void *buf, size_t size)
3122{
3123        struct tree_desc desc;
3124        struct name_entry entry;
3125
3126        init_tree_desc(&desc, buf, size);
3127        while (tree_entry(&desc, &entry))
3128                /* do nothing
3129                 * tree_entry() will die() on malformed entries */
3130                ;
3131}
3132
3133static void check_commit(const void *buf, size_t size)
3134{
3135        struct commit c;
3136        memset(&c, 0, sizeof(c));
3137        if (parse_commit_buffer(&c, buf, size))
3138                die("corrupt commit");
3139}
3140
3141static void check_tag(const void *buf, size_t size)
3142{
3143        struct tag t;
3144        memset(&t, 0, sizeof(t));
3145        if (parse_tag_buffer(&t, buf, size))
3146                die("corrupt tag");
3147}
3148
3149static int index_mem(unsigned char *sha1, void *buf, size_t size,
3150                     enum object_type type,
3151                     const char *path, unsigned flags)
3152{
3153        int ret, re_allocated = 0;
3154        int write_object = flags & HASH_WRITE_OBJECT;
3155
3156        if (!type)
3157                type = OBJ_BLOB;
3158
3159        /*
3160         * Convert blobs to git internal format
3161         */
3162        if ((type == OBJ_BLOB) && path) {
3163                struct strbuf nbuf = STRBUF_INIT;
3164                if (convert_to_git(path, buf, size, &nbuf,
3165                                   write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
3166                        buf = strbuf_detach(&nbuf, &size);
3167                        re_allocated = 1;
3168                }
3169        }
3170        if (flags & HASH_FORMAT_CHECK) {
3171                if (type == OBJ_TREE)
3172                        check_tree(buf, size);
3173                if (type == OBJ_COMMIT)
3174                        check_commit(buf, size);
3175                if (type == OBJ_TAG)
3176                        check_tag(buf, size);
3177        }
3178
3179        if (write_object)
3180                ret = write_sha1_file(buf, size, typename(type), sha1);
3181        else
3182                ret = hash_sha1_file(buf, size, typename(type), sha1);
3183        if (re_allocated)
3184                free(buf);
3185        return ret;
3186}
3187
3188static int index_stream_convert_blob(unsigned char *sha1, int fd,
3189                                     const char *path, unsigned flags)
3190{
3191        int ret;
3192        const int write_object = flags & HASH_WRITE_OBJECT;
3193        struct strbuf sbuf = STRBUF_INIT;
3194
3195        assert(path);
3196        assert(would_convert_to_git_filter_fd(path));
3197
3198        convert_to_git_filter_fd(path, fd, &sbuf,
3199                                 write_object ? safe_crlf : SAFE_CRLF_FALSE);
3200
3201        if (write_object)
3202                ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3203                                      sha1);
3204        else
3205                ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3206                                     sha1);
3207        strbuf_release(&sbuf);
3208        return ret;
3209}
3210
3211static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
3212                      const char *path, unsigned flags)
3213{
3214        struct strbuf sbuf = STRBUF_INIT;
3215        int ret;
3216
3217        if (strbuf_read(&sbuf, fd, 4096) >= 0)
3218                ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
3219        else
3220                ret = -1;
3221        strbuf_release(&sbuf);
3222        return ret;
3223}
3224
3225#define SMALL_FILE_SIZE (32*1024)
3226
3227static int index_core(unsigned char *sha1, int fd, size_t size,
3228                      enum object_type type, const char *path,
3229                      unsigned flags)
3230{
3231        int ret;
3232
3233        if (!size) {
3234                ret = index_mem(sha1, "", size, type, path, flags);
3235        } else if (size <= SMALL_FILE_SIZE) {
3236                char *buf = xmalloc(size);
3237                if (size == read_in_full(fd, buf, size))
3238                        ret = index_mem(sha1, buf, size, type, path, flags);
3239                else
3240                        ret = error("short read %s", strerror(errno));
3241                free(buf);
3242        } else {
3243                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3244                ret = index_mem(sha1, buf, size, type, path, flags);
3245                munmap(buf, size);
3246        }
3247        return ret;
3248}
3249
3250/*
3251 * This creates one packfile per large blob unless bulk-checkin
3252 * machinery is "plugged".
3253 *
3254 * This also bypasses the usual "convert-to-git" dance, and that is on
3255 * purpose. We could write a streaming version of the converting
3256 * functions and insert that before feeding the data to fast-import
3257 * (or equivalent in-core API described above). However, that is
3258 * somewhat complicated, as we do not know the size of the filter
3259 * result, which we need to know beforehand when writing a git object.
3260 * Since the primary motivation for trying to stream from the working
3261 * tree file and to avoid mmaping it in core is to deal with large
3262 * binary blobs, they generally do not want to get any conversion, and
3263 * callers should avoid this code path when filters are requested.
3264 */
3265static int index_stream(unsigned char *sha1, int fd, size_t size,
3266                        enum object_type type, const char *path,
3267                        unsigned flags)
3268{
3269        return index_bulk_checkin(sha1, fd, size, type, path, flags);
3270}
3271
3272int index_fd(unsigned char *sha1, int fd, struct stat *st,
3273             enum object_type type, const char *path, unsigned flags)
3274{
3275        int ret;
3276
3277        /*
3278         * Call xsize_t() only when needed to avoid potentially unnecessary
3279         * die() for large files.
3280         */
3281        if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
3282                ret = index_stream_convert_blob(sha1, fd, path, flags);
3283        else if (!S_ISREG(st->st_mode))
3284                ret = index_pipe(sha1, fd, type, path, flags);
3285        else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
3286                 (path && would_convert_to_git(path)))
3287                ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
3288                                 flags);
3289        else
3290                ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
3291                                   flags);
3292        close(fd);
3293        return ret;
3294}
3295
3296int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3297{
3298        int fd;
3299        struct strbuf sb = STRBUF_INIT;
3300
3301        switch (st->st_mode & S_IFMT) {
3302        case S_IFREG:
3303                fd = open(path, O_RDONLY);
3304                if (fd < 0)
3305                        return error("open(\"%s\"): %s", path,
3306                                     strerror(errno));
3307                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3308                        return error("%s: failed to insert into database",
3309                                     path);
3310                break;
3311        case S_IFLNK:
3312                if (strbuf_readlink(&sb, path, st->st_size)) {
3313                        char *errstr = strerror(errno);
3314                        return error("readlink(\"%s\"): %s", path,
3315                                     errstr);
3316                }
3317                if (!(flags & HASH_WRITE_OBJECT))
3318                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3319                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3320                        return error("%s: failed to insert into database",
3321                                     path);
3322                strbuf_release(&sb);
3323                break;
3324        case S_IFDIR:
3325                return resolve_gitlink_ref(path, "HEAD", sha1);
3326        default:
3327                return error("%s: unsupported file type", path);
3328        }
3329        return 0;
3330}
3331
3332int read_pack_header(int fd, struct pack_header *header)
3333{
3334        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3335                /* "eof before pack header was fully read" */
3336                return PH_ERROR_EOF;
3337
3338        if (header->hdr_signature != htonl(PACK_SIGNATURE))
3339                /* "protocol error (pack signature mismatch detected)" */
3340                return PH_ERROR_PACK_SIGNATURE;
3341        if (!pack_version_ok(header->hdr_version))
3342                /* "protocol error (pack version unsupported)" */
3343                return PH_ERROR_PROTOCOL;
3344        return 0;
3345}
3346
3347void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3348{
3349        enum object_type type = sha1_object_info(sha1, NULL);
3350        if (type < 0)
3351                die("%s is not a valid object", sha1_to_hex(sha1));
3352        if (type != expect)
3353                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3354                    typename(expect));
3355}
3356
3357static int for_each_file_in_obj_subdir(int subdir_nr,
3358                                       struct strbuf *path,
3359                                       each_loose_object_fn obj_cb,
3360                                       each_loose_cruft_fn cruft_cb,
3361                                       each_loose_subdir_fn subdir_cb,
3362                                       void *data)
3363{
3364        size_t baselen = path->len;
3365        DIR *dir = opendir(path->buf);
3366        struct dirent *de;
3367        int r = 0;
3368
3369        if (!dir) {
3370                if (errno == ENOENT)
3371                        return 0;
3372                return error("unable to open %s: %s", path->buf, strerror(errno));
3373        }
3374
3375        while ((de = readdir(dir))) {
3376                if (is_dot_or_dotdot(de->d_name))
3377                        continue;
3378
3379                strbuf_setlen(path, baselen);
3380                strbuf_addf(path, "/%s", de->d_name);
3381
3382                if (strlen(de->d_name) == 38)  {
3383                        char hex[41];
3384                        unsigned char sha1[20];
3385
3386                        snprintf(hex, sizeof(hex), "%02x%s",
3387                                 subdir_nr, de->d_name);
3388                        if (!get_sha1_hex(hex, sha1)) {
3389                                if (obj_cb) {
3390                                        r = obj_cb(sha1, path->buf, data);
3391                                        if (r)
3392                                                break;
3393                                }
3394                                continue;
3395                        }
3396                }
3397
3398                if (cruft_cb) {
3399                        r = cruft_cb(de->d_name, path->buf, data);
3400                        if (r)
3401                                break;
3402                }
3403        }
3404        strbuf_setlen(path, baselen);
3405
3406        if (!r && subdir_cb)
3407                r = subdir_cb(subdir_nr, path->buf, data);
3408
3409        closedir(dir);
3410        return r;
3411}
3412
3413int for_each_loose_file_in_objdir_buf(struct strbuf *path,
3414                            each_loose_object_fn obj_cb,
3415                            each_loose_cruft_fn cruft_cb,
3416                            each_loose_subdir_fn subdir_cb,
3417                            void *data)
3418{
3419        size_t baselen = path->len;
3420        int r = 0;
3421        int i;
3422
3423        for (i = 0; i < 256; i++) {
3424                strbuf_addf(path, "/%02x", i);
3425                r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
3426                                                subdir_cb, data);
3427                strbuf_setlen(path, baselen);
3428                if (r)
3429                        break;
3430        }
3431
3432        return r;
3433}
3434
3435int for_each_loose_file_in_objdir(const char *path,
3436                                  each_loose_object_fn obj_cb,
3437                                  each_loose_cruft_fn cruft_cb,
3438                                  each_loose_subdir_fn subdir_cb,
3439                                  void *data)
3440{
3441        struct strbuf buf = STRBUF_INIT;
3442        int r;
3443
3444        strbuf_addstr(&buf, path);
3445        r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
3446                                              subdir_cb, data);
3447        strbuf_release(&buf);
3448
3449        return r;
3450}
3451
3452struct loose_alt_odb_data {
3453        each_loose_object_fn *cb;
3454        void *data;
3455};
3456
3457static int loose_from_alt_odb(struct alternate_object_database *alt,
3458                              void *vdata)
3459{
3460        struct loose_alt_odb_data *data = vdata;
3461        struct strbuf buf = STRBUF_INIT;
3462        int r;
3463
3464        /* copy base not including trailing '/' */
3465        strbuf_add(&buf, alt->base, alt->name - alt->base - 1);
3466        r = for_each_loose_file_in_objdir_buf(&buf,
3467                                              data->cb, NULL, NULL,
3468                                              data->data);
3469        strbuf_release(&buf);
3470        return r;
3471}
3472
3473int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
3474{
3475        struct loose_alt_odb_data alt;
3476        int r;
3477
3478        r = for_each_loose_file_in_objdir(get_object_directory(),
3479                                          cb, NULL, NULL, data);
3480        if (r)
3481                return r;
3482
3483        if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
3484                return 0;
3485
3486        alt.cb = cb;
3487        alt.data = data;
3488        return foreach_alt_odb(loose_from_alt_odb, &alt);
3489}
3490
3491static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
3492{
3493        uint32_t i;
3494        int r = 0;
3495
3496        for (i = 0; i < p->num_objects; i++) {
3497                const unsigned char *sha1 = nth_packed_object_sha1(p, i);
3498
3499                if (!sha1)
3500                        return error("unable to get sha1 of object %u in %s",
3501                                     i, p->pack_name);
3502
3503                r = cb(sha1, p, i, data);
3504                if (r)
3505                        break;
3506        }
3507        return r;
3508}
3509
3510int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
3511{
3512        struct packed_git *p;
3513        int r = 0;
3514
3515        prepare_packed_git();
3516        for (p = packed_git; p; p = p->next) {
3517                if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
3518                        continue;
3519                r = for_each_object_in_pack(p, cb, data);
3520                if (r)
3521                        break;
3522        }
3523        return r;
3524}