18922b435ebd82f95b495a40b76c4ceb15416dc0
   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
 756static int close_pack_fd(struct packed_git *p)
 757{
 758        if (p->pack_fd < 0)
 759                return 0;
 760
 761        close(p->pack_fd);
 762        pack_open_fds--;
 763        p->pack_fd = -1;
 764
 765        return 1;
 766}
 767
 768/*
 769 * The LRU pack is the one with the oldest MRU window, preferring packs
 770 * with no used windows, or the oldest mtime if it has no windows allocated.
 771 */
 772static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 773{
 774        struct pack_window *w, *this_mru_w;
 775        int has_windows_inuse = 0;
 776
 777        /*
 778         * Reject this pack if it has windows and the previously selected
 779         * one does not.  If this pack does not have windows, reject
 780         * it if the pack file is newer than the previously selected one.
 781         */
 782        if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 783                return;
 784
 785        for (w = this_mru_w = p->windows; w; w = w->next) {
 786                /*
 787                 * Reject this pack if any of its windows are in use,
 788                 * but the previously selected pack did not have any
 789                 * inuse windows.  Otherwise, record that this pack
 790                 * has windows in use.
 791                 */
 792                if (w->inuse_cnt) {
 793                        if (*accept_windows_inuse)
 794                                has_windows_inuse = 1;
 795                        else
 796                                return;
 797                }
 798
 799                if (w->last_used > this_mru_w->last_used)
 800                        this_mru_w = w;
 801
 802                /*
 803                 * Reject this pack if it has windows that have been
 804                 * used more recently than the previously selected pack.
 805                 * If the previously selected pack had windows inuse and
 806                 * we have not encountered a window in this pack that is
 807                 * inuse, skip this check since we prefer a pack with no
 808                 * inuse windows to one that has inuse windows.
 809                 */
 810                if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 811                    this_mru_w->last_used > (*mru_w)->last_used)
 812                        return;
 813        }
 814
 815        /*
 816         * Select this pack.
 817         */
 818        *mru_w = this_mru_w;
 819        *lru_p = p;
 820        *accept_windows_inuse = has_windows_inuse;
 821}
 822
 823static int close_one_pack(void)
 824{
 825        struct packed_git *p, *lru_p = NULL;
 826        struct pack_window *mru_w = NULL;
 827        int accept_windows_inuse = 1;
 828
 829        for (p = packed_git; p; p = p->next) {
 830                if (p->pack_fd == -1)
 831                        continue;
 832                find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 833        }
 834
 835        if (lru_p)
 836                return close_pack_fd(lru_p);
 837
 838        return 0;
 839}
 840
 841void unuse_pack(struct pack_window **w_cursor)
 842{
 843        struct pack_window *w = *w_cursor;
 844        if (w) {
 845                w->inuse_cnt--;
 846                *w_cursor = NULL;
 847        }
 848}
 849
 850void close_pack_index(struct packed_git *p)
 851{
 852        if (p->index_data) {
 853                munmap((void *)p->index_data, p->index_size);
 854                p->index_data = NULL;
 855        }
 856}
 857
 858/*
 859 * This is used by git-repack in case a newly created pack happens to
 860 * contain the same set of objects as an existing one.  In that case
 861 * the resulting file might be different even if its name would be the
 862 * same.  It is best to close any reference to the old pack before it is
 863 * replaced on disk.  Of course no index pointers or windows for given pack
 864 * must subsist at this point.  If ever objects from this pack are requested
 865 * again, the new version of the pack will be reinitialized through
 866 * reprepare_packed_git().
 867 */
 868void free_pack_by_name(const char *pack_name)
 869{
 870        struct packed_git *p, **pp = &packed_git;
 871
 872        while (*pp) {
 873                p = *pp;
 874                if (strcmp(pack_name, p->pack_name) == 0) {
 875                        clear_delta_base_cache();
 876                        close_pack_windows(p);
 877                        close_pack_fd(p);
 878                        close_pack_index(p);
 879                        free(p->bad_object_sha1);
 880                        *pp = p->next;
 881                        if (last_found_pack == p)
 882                                last_found_pack = NULL;
 883                        free(p);
 884                        return;
 885                }
 886                pp = &p->next;
 887        }
 888}
 889
 890static unsigned int get_max_fd_limit(void)
 891{
 892#ifdef RLIMIT_NOFILE
 893        {
 894                struct rlimit lim;
 895
 896                if (!getrlimit(RLIMIT_NOFILE, &lim))
 897                        return lim.rlim_cur;
 898        }
 899#endif
 900
 901#ifdef _SC_OPEN_MAX
 902        {
 903                long open_max = sysconf(_SC_OPEN_MAX);
 904                if (0 < open_max)
 905                        return open_max;
 906                /*
 907                 * Otherwise, we got -1 for one of the two
 908                 * reasons:
 909                 *
 910                 * (1) sysconf() did not understand _SC_OPEN_MAX
 911                 *     and signaled an error with -1; or
 912                 * (2) sysconf() said there is no limit.
 913                 *
 914                 * We _could_ clear errno before calling sysconf() to
 915                 * tell these two cases apart and return a huge number
 916                 * in the latter case to let the caller cap it to a
 917                 * value that is not so selfish, but letting the
 918                 * fallback OPEN_MAX codepath take care of these cases
 919                 * is a lot simpler.
 920                 */
 921        }
 922#endif
 923
 924#ifdef OPEN_MAX
 925        return OPEN_MAX;
 926#else
 927        return 1; /* see the caller ;-) */
 928#endif
 929}
 930
 931/*
 932 * Do not call this directly as this leaks p->pack_fd on error return;
 933 * call open_packed_git() instead.
 934 */
 935static int open_packed_git_1(struct packed_git *p)
 936{
 937        struct stat st;
 938        struct pack_header hdr;
 939        unsigned char sha1[20];
 940        unsigned char *idx_sha1;
 941        long fd_flag;
 942
 943        if (!p->index_data && open_pack_index(p))
 944                return error("packfile %s index unavailable", p->pack_name);
 945
 946        if (!pack_max_fds) {
 947                unsigned int max_fds = get_max_fd_limit();
 948
 949                /* Save 3 for stdin/stdout/stderr, 22 for work */
 950                if (25 < max_fds)
 951                        pack_max_fds = max_fds - 25;
 952                else
 953                        pack_max_fds = 1;
 954        }
 955
 956        while (pack_max_fds <= pack_open_fds && close_one_pack())
 957                ; /* nothing */
 958
 959        p->pack_fd = git_open_noatime(p->pack_name);
 960        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 961                return -1;
 962        pack_open_fds++;
 963
 964        /* If we created the struct before we had the pack we lack size. */
 965        if (!p->pack_size) {
 966                if (!S_ISREG(st.st_mode))
 967                        return error("packfile %s not a regular file", p->pack_name);
 968                p->pack_size = st.st_size;
 969        } else if (p->pack_size != st.st_size)
 970                return error("packfile %s size changed", p->pack_name);
 971
 972        /* We leave these file descriptors open with sliding mmap;
 973         * there is no point keeping them open across exec(), though.
 974         */
 975        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 976        if (fd_flag < 0)
 977                return error("cannot determine file descriptor flags");
 978        fd_flag |= FD_CLOEXEC;
 979        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 980                return error("cannot set FD_CLOEXEC");
 981
 982        /* Verify we recognize this pack file format. */
 983        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 984                return error("file %s is far too short to be a packfile", p->pack_name);
 985        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 986                return error("file %s is not a GIT packfile", p->pack_name);
 987        if (!pack_version_ok(hdr.hdr_version))
 988                return error("packfile %s is version %"PRIu32" and not"
 989                        " supported (try upgrading GIT to a newer version)",
 990                        p->pack_name, ntohl(hdr.hdr_version));
 991
 992        /* Verify the pack matches its index. */
 993        if (p->num_objects != ntohl(hdr.hdr_entries))
 994                return error("packfile %s claims to have %"PRIu32" objects"
 995                             " while index indicates %"PRIu32" objects",
 996                             p->pack_name, ntohl(hdr.hdr_entries),
 997                             p->num_objects);
 998        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 999                return error("end of packfile %s is unavailable", p->pack_name);
1000        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
1001                return error("packfile %s signature is unavailable", p->pack_name);
1002        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
1003        if (hashcmp(sha1, idx_sha1))
1004                return error("packfile %s does not match index", p->pack_name);
1005        return 0;
1006}
1007
1008static int open_packed_git(struct packed_git *p)
1009{
1010        if (!open_packed_git_1(p))
1011                return 0;
1012        close_pack_fd(p);
1013        return -1;
1014}
1015
1016static int in_window(struct pack_window *win, off_t offset)
1017{
1018        /* We must promise at least 20 bytes (one hash) after the
1019         * offset is available from this window, otherwise the offset
1020         * is not actually in this window and a different window (which
1021         * has that one hash excess) must be used.  This is to support
1022         * the object header and delta base parsing routines below.
1023         */
1024        off_t win_off = win->offset;
1025        return win_off <= offset
1026                && (offset + 20) <= (win_off + win->len);
1027}
1028
1029unsigned char *use_pack(struct packed_git *p,
1030                struct pack_window **w_cursor,
1031                off_t offset,
1032                unsigned long *left)
1033{
1034        struct pack_window *win = *w_cursor;
1035
1036        /* Since packfiles end in a hash of their content and it's
1037         * pointless to ask for an offset into the middle of that
1038         * hash, and the in_window function above wouldn't match
1039         * don't allow an offset too close to the end of the file.
1040         */
1041        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
1042                die("packfile %s cannot be accessed", p->pack_name);
1043        if (offset > (p->pack_size - 20))
1044                die("offset beyond end of packfile (truncated pack?)");
1045
1046        if (!win || !in_window(win, offset)) {
1047                if (win)
1048                        win->inuse_cnt--;
1049                for (win = p->windows; win; win = win->next) {
1050                        if (in_window(win, offset))
1051                                break;
1052                }
1053                if (!win) {
1054                        size_t window_align = packed_git_window_size / 2;
1055                        off_t len;
1056
1057                        if (p->pack_fd == -1 && open_packed_git(p))
1058                                die("packfile %s cannot be accessed", p->pack_name);
1059
1060                        win = xcalloc(1, sizeof(*win));
1061                        win->offset = (offset / window_align) * window_align;
1062                        len = p->pack_size - win->offset;
1063                        if (len > packed_git_window_size)
1064                                len = packed_git_window_size;
1065                        win->len = (size_t)len;
1066                        pack_mapped += win->len;
1067                        while (packed_git_limit < pack_mapped
1068                                && unuse_one_window(p))
1069                                ; /* nothing */
1070                        win->base = xmmap(NULL, win->len,
1071                                PROT_READ, MAP_PRIVATE,
1072                                p->pack_fd, win->offset);
1073                        if (win->base == MAP_FAILED)
1074                                die("packfile %s cannot be mapped: %s",
1075                                        p->pack_name,
1076                                        strerror(errno));
1077                        if (!win->offset && win->len == p->pack_size
1078                                && !p->do_not_close)
1079                                close_pack_fd(p);
1080                        pack_mmap_calls++;
1081                        pack_open_windows++;
1082                        if (pack_mapped > peak_pack_mapped)
1083                                peak_pack_mapped = pack_mapped;
1084                        if (pack_open_windows > peak_pack_open_windows)
1085                                peak_pack_open_windows = pack_open_windows;
1086                        win->next = p->windows;
1087                        p->windows = win;
1088                }
1089        }
1090        if (win != *w_cursor) {
1091                win->last_used = pack_used_ctr++;
1092                win->inuse_cnt++;
1093                *w_cursor = win;
1094        }
1095        offset -= win->offset;
1096        if (left)
1097                *left = win->len - xsize_t(offset);
1098        return win->base + offset;
1099}
1100
1101static struct packed_git *alloc_packed_git(int extra)
1102{
1103        struct packed_git *p = xmalloc(sizeof(*p) + extra);
1104        memset(p, 0, sizeof(*p));
1105        p->pack_fd = -1;
1106        return p;
1107}
1108
1109static void try_to_free_pack_memory(size_t size)
1110{
1111        release_pack_memory(size);
1112}
1113
1114struct packed_git *add_packed_git(const char *path, int path_len, int local)
1115{
1116        static int have_set_try_to_free_routine;
1117        struct stat st;
1118        struct packed_git *p = alloc_packed_git(path_len + 2);
1119
1120        if (!have_set_try_to_free_routine) {
1121                have_set_try_to_free_routine = 1;
1122                set_try_to_free_routine(try_to_free_pack_memory);
1123        }
1124
1125        /*
1126         * Make sure a corresponding .pack file exists and that
1127         * the index looks sane.
1128         */
1129        path_len -= strlen(".idx");
1130        if (path_len < 1) {
1131                free(p);
1132                return NULL;
1133        }
1134        memcpy(p->pack_name, path, path_len);
1135
1136        strcpy(p->pack_name + path_len, ".keep");
1137        if (!access(p->pack_name, F_OK))
1138                p->pack_keep = 1;
1139
1140        strcpy(p->pack_name + path_len, ".pack");
1141        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
1142                free(p);
1143                return NULL;
1144        }
1145
1146        /* ok, it looks sane as far as we can check without
1147         * actually mapping the pack file.
1148         */
1149        p->pack_size = st.st_size;
1150        p->pack_local = local;
1151        p->mtime = st.st_mtime;
1152        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
1153                hashclr(p->sha1);
1154        return p;
1155}
1156
1157struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
1158{
1159        const char *path = sha1_pack_name(sha1);
1160        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
1161
1162        strcpy(p->pack_name, path);
1163        hashcpy(p->sha1, sha1);
1164        if (check_packed_git_idx(idx_path, p)) {
1165                free(p);
1166                return NULL;
1167        }
1168
1169        return p;
1170}
1171
1172void install_packed_git(struct packed_git *pack)
1173{
1174        if (pack->pack_fd != -1)
1175                pack_open_fds++;
1176
1177        pack->next = packed_git;
1178        packed_git = pack;
1179}
1180
1181void (*report_garbage)(const char *desc, const char *path);
1182
1183static void report_helper(const struct string_list *list,
1184                          int seen_bits, int first, int last)
1185{
1186        const char *msg;
1187        switch (seen_bits) {
1188        case 0:
1189                msg = "no corresponding .idx or .pack";
1190                break;
1191        case 1:
1192                msg = "no corresponding .idx";
1193                break;
1194        case 2:
1195                msg = "no corresponding .pack";
1196                break;
1197        default:
1198                return;
1199        }
1200        for (; first < last; first++)
1201                report_garbage(msg, list->items[first].string);
1202}
1203
1204static void report_pack_garbage(struct string_list *list)
1205{
1206        int i, baselen = -1, first = 0, seen_bits = 0;
1207
1208        if (!report_garbage)
1209                return;
1210
1211        string_list_sort(list);
1212
1213        for (i = 0; i < list->nr; i++) {
1214                const char *path = list->items[i].string;
1215                if (baselen != -1 &&
1216                    strncmp(path, list->items[first].string, baselen)) {
1217                        report_helper(list, seen_bits, first, i);
1218                        baselen = -1;
1219                        seen_bits = 0;
1220                }
1221                if (baselen == -1) {
1222                        const char *dot = strrchr(path, '.');
1223                        if (!dot) {
1224                                report_garbage("garbage found", path);
1225                                continue;
1226                        }
1227                        baselen = dot - path + 1;
1228                        first = i;
1229                }
1230                if (!strcmp(path + baselen, "pack"))
1231                        seen_bits |= 1;
1232                else if (!strcmp(path + baselen, "idx"))
1233                        seen_bits |= 2;
1234        }
1235        report_helper(list, seen_bits, first, list->nr);
1236}
1237
1238static void prepare_packed_git_one(char *objdir, int local)
1239{
1240        struct strbuf path = STRBUF_INIT;
1241        size_t dirnamelen;
1242        DIR *dir;
1243        struct dirent *de;
1244        struct string_list garbage = STRING_LIST_INIT_DUP;
1245
1246        strbuf_addstr(&path, objdir);
1247        strbuf_addstr(&path, "/pack");
1248        dir = opendir(path.buf);
1249        if (!dir) {
1250                if (errno != ENOENT)
1251                        error("unable to open object pack directory: %s: %s",
1252                              path.buf, strerror(errno));
1253                strbuf_release(&path);
1254                return;
1255        }
1256        strbuf_addch(&path, '/');
1257        dirnamelen = path.len;
1258        while ((de = readdir(dir)) != NULL) {
1259                struct packed_git *p;
1260                size_t base_len;
1261
1262                if (is_dot_or_dotdot(de->d_name))
1263                        continue;
1264
1265                strbuf_setlen(&path, dirnamelen);
1266                strbuf_addstr(&path, de->d_name);
1267
1268                base_len = path.len;
1269                if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
1270                        /* Don't reopen a pack we already have. */
1271                        for (p = packed_git; p; p = p->next) {
1272                                size_t len;
1273                                if (strip_suffix(p->pack_name, ".pack", &len) &&
1274                                    len == base_len &&
1275                                    !memcmp(p->pack_name, path.buf, len))
1276                                        break;
1277                        }
1278                        if (p == NULL &&
1279                            /*
1280                             * See if it really is a valid .idx file with
1281                             * corresponding .pack file that we can map.
1282                             */
1283                            (p = add_packed_git(path.buf, path.len, local)) != NULL)
1284                                install_packed_git(p);
1285                }
1286
1287                if (!report_garbage)
1288                        continue;
1289
1290                if (ends_with(de->d_name, ".idx") ||
1291                    ends_with(de->d_name, ".pack") ||
1292                    ends_with(de->d_name, ".bitmap") ||
1293                    ends_with(de->d_name, ".keep"))
1294                        string_list_append(&garbage, path.buf);
1295                else
1296                        report_garbage("garbage found", path.buf);
1297        }
1298        closedir(dir);
1299        report_pack_garbage(&garbage);
1300        string_list_clear(&garbage, 0);
1301        strbuf_release(&path);
1302}
1303
1304static int sort_pack(const void *a_, const void *b_)
1305{
1306        struct packed_git *a = *((struct packed_git **)a_);
1307        struct packed_git *b = *((struct packed_git **)b_);
1308        int st;
1309
1310        /*
1311         * Local packs tend to contain objects specific to our
1312         * variant of the project than remote ones.  In addition,
1313         * remote ones could be on a network mounted filesystem.
1314         * Favor local ones for these reasons.
1315         */
1316        st = a->pack_local - b->pack_local;
1317        if (st)
1318                return -st;
1319
1320        /*
1321         * Younger packs tend to contain more recent objects,
1322         * and more recent objects tend to get accessed more
1323         * often.
1324         */
1325        if (a->mtime < b->mtime)
1326                return 1;
1327        else if (a->mtime == b->mtime)
1328                return 0;
1329        return -1;
1330}
1331
1332static void rearrange_packed_git(void)
1333{
1334        struct packed_git **ary, *p;
1335        int i, n;
1336
1337        for (n = 0, p = packed_git; p; p = p->next)
1338                n++;
1339        if (n < 2)
1340                return;
1341
1342        /* prepare an array of packed_git for easier sorting */
1343        ary = xcalloc(n, sizeof(struct packed_git *));
1344        for (n = 0, p = packed_git; p; p = p->next)
1345                ary[n++] = p;
1346
1347        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1348
1349        /* link them back again */
1350        for (i = 0; i < n - 1; i++)
1351                ary[i]->next = ary[i + 1];
1352        ary[n - 1]->next = NULL;
1353        packed_git = ary[0];
1354
1355        free(ary);
1356}
1357
1358static int prepare_packed_git_run_once = 0;
1359void prepare_packed_git(void)
1360{
1361        struct alternate_object_database *alt;
1362
1363        if (prepare_packed_git_run_once)
1364                return;
1365        prepare_packed_git_one(get_object_directory(), 1);
1366        prepare_alt_odb();
1367        for (alt = alt_odb_list; alt; alt = alt->next) {
1368                alt->name[-1] = 0;
1369                prepare_packed_git_one(alt->base, 0);
1370                alt->name[-1] = '/';
1371        }
1372        rearrange_packed_git();
1373        prepare_packed_git_run_once = 1;
1374}
1375
1376void reprepare_packed_git(void)
1377{
1378        prepare_packed_git_run_once = 0;
1379        prepare_packed_git();
1380}
1381
1382static void mark_bad_packed_object(struct packed_git *p,
1383                                   const unsigned char *sha1)
1384{
1385        unsigned i;
1386        for (i = 0; i < p->num_bad_objects; i++)
1387                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1388                        return;
1389        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1390        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1391        p->num_bad_objects++;
1392}
1393
1394static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1395{
1396        struct packed_git *p;
1397        unsigned i;
1398
1399        for (p = packed_git; p; p = p->next)
1400                for (i = 0; i < p->num_bad_objects; i++)
1401                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1402                                return p;
1403        return NULL;
1404}
1405
1406/*
1407 * With an in-core object data in "map", rehash it to make sure the
1408 * object name actually matches "sha1" to detect object corruption.
1409 * With "map" == NULL, try reading the object named with "sha1" using
1410 * the streaming interface and rehash it to do the same.
1411 */
1412int check_sha1_signature(const unsigned char *sha1, void *map,
1413                         unsigned long size, const char *type)
1414{
1415        unsigned char real_sha1[20];
1416        enum object_type obj_type;
1417        struct git_istream *st;
1418        git_SHA_CTX c;
1419        char hdr[32];
1420        int hdrlen;
1421
1422        if (map) {
1423                hash_sha1_file(map, size, type, real_sha1);
1424                return hashcmp(sha1, real_sha1) ? -1 : 0;
1425        }
1426
1427        st = open_istream(sha1, &obj_type, &size, NULL);
1428        if (!st)
1429                return -1;
1430
1431        /* Generate the header */
1432        hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
1433
1434        /* Sha1.. */
1435        git_SHA1_Init(&c);
1436        git_SHA1_Update(&c, hdr, hdrlen);
1437        for (;;) {
1438                char buf[1024 * 16];
1439                ssize_t readlen = read_istream(st, buf, sizeof(buf));
1440
1441                if (readlen < 0) {
1442                        close_istream(st);
1443                        return -1;
1444                }
1445                if (!readlen)
1446                        break;
1447                git_SHA1_Update(&c, buf, readlen);
1448        }
1449        git_SHA1_Final(real_sha1, &c);
1450        close_istream(st);
1451        return hashcmp(sha1, real_sha1) ? -1 : 0;
1452}
1453
1454int git_open_noatime(const char *name)
1455{
1456        static int sha1_file_open_flag = O_NOATIME;
1457
1458        for (;;) {
1459                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1460                if (fd >= 0)
1461                        return fd;
1462
1463                /* Might the failure be due to O_NOATIME? */
1464                if (errno != ENOENT && sha1_file_open_flag) {
1465                        sha1_file_open_flag = 0;
1466                        continue;
1467                }
1468
1469                return -1;
1470        }
1471}
1472
1473static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
1474{
1475        struct alternate_object_database *alt;
1476
1477        if (!lstat(sha1_file_name(sha1), st))
1478                return 0;
1479
1480        prepare_alt_odb();
1481        errno = ENOENT;
1482        for (alt = alt_odb_list; alt; alt = alt->next) {
1483                fill_sha1_path(alt->name, sha1);
1484                if (!lstat(alt->base, st))
1485                        return 0;
1486        }
1487
1488        return -1;
1489}
1490
1491static int open_sha1_file(const unsigned char *sha1)
1492{
1493        int fd;
1494        struct alternate_object_database *alt;
1495        int most_interesting_errno;
1496
1497        fd = git_open_noatime(sha1_file_name(sha1));
1498        if (fd >= 0)
1499                return fd;
1500        most_interesting_errno = errno;
1501
1502        prepare_alt_odb();
1503        for (alt = alt_odb_list; alt; alt = alt->next) {
1504                fill_sha1_path(alt->name, sha1);
1505                fd = git_open_noatime(alt->base);
1506                if (fd >= 0)
1507                        return fd;
1508                if (most_interesting_errno == ENOENT)
1509                        most_interesting_errno = errno;
1510        }
1511        errno = most_interesting_errno;
1512        return -1;
1513}
1514
1515void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1516{
1517        void *map;
1518        int fd;
1519
1520        fd = open_sha1_file(sha1);
1521        map = NULL;
1522        if (fd >= 0) {
1523                struct stat st;
1524
1525                if (!fstat(fd, &st)) {
1526                        *size = xsize_t(st.st_size);
1527                        if (!*size) {
1528                                /* mmap() is forbidden on empty files */
1529                                error("object file %s is empty", sha1_file_name(sha1));
1530                                return NULL;
1531                        }
1532                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1533                }
1534                close(fd);
1535        }
1536        return map;
1537}
1538
1539unsigned long unpack_object_header_buffer(const unsigned char *buf,
1540                unsigned long len, enum object_type *type, unsigned long *sizep)
1541{
1542        unsigned shift;
1543        unsigned long size, c;
1544        unsigned long used = 0;
1545
1546        c = buf[used++];
1547        *type = (c >> 4) & 7;
1548        size = c & 15;
1549        shift = 4;
1550        while (c & 0x80) {
1551                if (len <= used || bitsizeof(long) <= shift) {
1552                        error("bad object header");
1553                        size = used = 0;
1554                        break;
1555                }
1556                c = buf[used++];
1557                size += (c & 0x7f) << shift;
1558                shift += 7;
1559        }
1560        *sizep = size;
1561        return used;
1562}
1563
1564int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1565{
1566        /* Get the data stream */
1567        memset(stream, 0, sizeof(*stream));
1568        stream->next_in = map;
1569        stream->avail_in = mapsize;
1570        stream->next_out = buffer;
1571        stream->avail_out = bufsiz;
1572
1573        git_inflate_init(stream);
1574        return git_inflate(stream, 0);
1575}
1576
1577static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1578{
1579        int bytes = strlen(buffer) + 1;
1580        unsigned char *buf = xmallocz(size);
1581        unsigned long n;
1582        int status = Z_OK;
1583
1584        n = stream->total_out - bytes;
1585        if (n > size)
1586                n = size;
1587        memcpy(buf, (char *) buffer + bytes, n);
1588        bytes = n;
1589        if (bytes <= size) {
1590                /*
1591                 * The above condition must be (bytes <= size), not
1592                 * (bytes < size).  In other words, even though we
1593                 * expect no more output and set avail_out to zero,
1594                 * the input zlib stream may have bytes that express
1595                 * "this concludes the stream", and we *do* want to
1596                 * eat that input.
1597                 *
1598                 * Otherwise we would not be able to test that we
1599                 * consumed all the input to reach the expected size;
1600                 * we also want to check that zlib tells us that all
1601                 * went well with status == Z_STREAM_END at the end.
1602                 */
1603                stream->next_out = buf + bytes;
1604                stream->avail_out = size - bytes;
1605                while (status == Z_OK)
1606                        status = git_inflate(stream, Z_FINISH);
1607        }
1608        if (status == Z_STREAM_END && !stream->avail_in) {
1609                git_inflate_end(stream);
1610                return buf;
1611        }
1612
1613        if (status < 0)
1614                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1615        else if (stream->avail_in)
1616                error("garbage at end of loose object '%s'",
1617                      sha1_to_hex(sha1));
1618        free(buf);
1619        return NULL;
1620}
1621
1622/*
1623 * We used to just use "sscanf()", but that's actually way
1624 * too permissive for what we want to check. So do an anal
1625 * object header parse by hand.
1626 */
1627int parse_sha1_header(const char *hdr, unsigned long *sizep)
1628{
1629        char type[10];
1630        int i;
1631        unsigned long size;
1632
1633        /*
1634         * The type can be at most ten bytes (including the
1635         * terminating '\0' that we add), and is followed by
1636         * a space.
1637         */
1638        i = 0;
1639        for (;;) {
1640                char c = *hdr++;
1641                if (c == ' ')
1642                        break;
1643                type[i++] = c;
1644                if (i >= sizeof(type))
1645                        return -1;
1646        }
1647        type[i] = 0;
1648
1649        /*
1650         * The length must follow immediately, and be in canonical
1651         * decimal format (ie "010" is not valid).
1652         */
1653        size = *hdr++ - '0';
1654        if (size > 9)
1655                return -1;
1656        if (size) {
1657                for (;;) {
1658                        unsigned long c = *hdr - '0';
1659                        if (c > 9)
1660                                break;
1661                        hdr++;
1662                        size = size * 10 + c;
1663                }
1664        }
1665        *sizep = size;
1666
1667        /*
1668         * The length must be followed by a zero byte
1669         */
1670        return *hdr ? -1 : type_from_string(type);
1671}
1672
1673static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1674{
1675        int ret;
1676        git_zstream stream;
1677        char hdr[8192];
1678
1679        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1680        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1681                return NULL;
1682
1683        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1684}
1685
1686unsigned long get_size_from_delta(struct packed_git *p,
1687                                  struct pack_window **w_curs,
1688                                  off_t curpos)
1689{
1690        const unsigned char *data;
1691        unsigned char delta_head[20], *in;
1692        git_zstream stream;
1693        int st;
1694
1695        memset(&stream, 0, sizeof(stream));
1696        stream.next_out = delta_head;
1697        stream.avail_out = sizeof(delta_head);
1698
1699        git_inflate_init(&stream);
1700        do {
1701                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1702                stream.next_in = in;
1703                st = git_inflate(&stream, Z_FINISH);
1704                curpos += stream.next_in - in;
1705        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1706                 stream.total_out < sizeof(delta_head));
1707        git_inflate_end(&stream);
1708        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1709                error("delta data unpack-initial failed");
1710                return 0;
1711        }
1712
1713        /* Examine the initial part of the delta to figure out
1714         * the result size.
1715         */
1716        data = delta_head;
1717
1718        /* ignore base size */
1719        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1720
1721        /* Read the result size */
1722        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1723}
1724
1725static off_t get_delta_base(struct packed_git *p,
1726                                    struct pack_window **w_curs,
1727                                    off_t *curpos,
1728                                    enum object_type type,
1729                                    off_t delta_obj_offset)
1730{
1731        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1732        off_t base_offset;
1733
1734        /* use_pack() assured us we have [base_info, base_info + 20)
1735         * as a range that we can look at without walking off the
1736         * end of the mapped window.  Its actually the hash size
1737         * that is assured.  An OFS_DELTA longer than the hash size
1738         * is stupid, as then a REF_DELTA would be smaller to store.
1739         */
1740        if (type == OBJ_OFS_DELTA) {
1741                unsigned used = 0;
1742                unsigned char c = base_info[used++];
1743                base_offset = c & 127;
1744                while (c & 128) {
1745                        base_offset += 1;
1746                        if (!base_offset || MSB(base_offset, 7))
1747                                return 0;  /* overflow */
1748                        c = base_info[used++];
1749                        base_offset = (base_offset << 7) + (c & 127);
1750                }
1751                base_offset = delta_obj_offset - base_offset;
1752                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1753                        return 0;  /* out of bound */
1754                *curpos += used;
1755        } else if (type == OBJ_REF_DELTA) {
1756                /* The base entry _must_ be in the same pack */
1757                base_offset = find_pack_entry_one(base_info, p);
1758                *curpos += 20;
1759        } else
1760                die("I am totally screwed");
1761        return base_offset;
1762}
1763
1764/*
1765 * Like get_delta_base above, but we return the sha1 instead of the pack
1766 * offset. This means it is cheaper for REF deltas (we do not have to do
1767 * the final object lookup), but more expensive for OFS deltas (we
1768 * have to load the revidx to convert the offset back into a sha1).
1769 */
1770static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1771                                                struct pack_window **w_curs,
1772                                                off_t curpos,
1773                                                enum object_type type,
1774                                                off_t delta_obj_offset)
1775{
1776        if (type == OBJ_REF_DELTA) {
1777                unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1778                return base;
1779        } else if (type == OBJ_OFS_DELTA) {
1780                struct revindex_entry *revidx;
1781                off_t base_offset = get_delta_base(p, w_curs, &curpos,
1782                                                   type, delta_obj_offset);
1783
1784                if (!base_offset)
1785                        return NULL;
1786
1787                revidx = find_pack_revindex(p, base_offset);
1788                if (!revidx)
1789                        return NULL;
1790
1791                return nth_packed_object_sha1(p, revidx->nr);
1792        } else
1793                return NULL;
1794}
1795
1796int unpack_object_header(struct packed_git *p,
1797                         struct pack_window **w_curs,
1798                         off_t *curpos,
1799                         unsigned long *sizep)
1800{
1801        unsigned char *base;
1802        unsigned long left;
1803        unsigned long used;
1804        enum object_type type;
1805
1806        /* use_pack() assures us we have [base, base + 20) available
1807         * as a range that we can look at.  (Its actually the hash
1808         * size that is assured.)  With our object header encoding
1809         * the maximum deflated object size is 2^137, which is just
1810         * insane, so we know won't exceed what we have been given.
1811         */
1812        base = use_pack(p, w_curs, *curpos, &left);
1813        used = unpack_object_header_buffer(base, left, &type, sizep);
1814        if (!used) {
1815                type = OBJ_BAD;
1816        } else
1817                *curpos += used;
1818
1819        return type;
1820}
1821
1822static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1823{
1824        int type;
1825        struct revindex_entry *revidx;
1826        const unsigned char *sha1;
1827        revidx = find_pack_revindex(p, obj_offset);
1828        if (!revidx)
1829                return OBJ_BAD;
1830        sha1 = nth_packed_object_sha1(p, revidx->nr);
1831        mark_bad_packed_object(p, sha1);
1832        type = sha1_object_info(sha1, NULL);
1833        if (type <= OBJ_NONE)
1834                return OBJ_BAD;
1835        return type;
1836}
1837
1838#define POI_STACK_PREALLOC 64
1839
1840static enum object_type packed_to_object_type(struct packed_git *p,
1841                                              off_t obj_offset,
1842                                              enum object_type type,
1843                                              struct pack_window **w_curs,
1844                                              off_t curpos)
1845{
1846        off_t small_poi_stack[POI_STACK_PREALLOC];
1847        off_t *poi_stack = small_poi_stack;
1848        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1849
1850        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1851                off_t base_offset;
1852                unsigned long size;
1853                /* Push the object we're going to leave behind */
1854                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1855                        poi_stack_alloc = alloc_nr(poi_stack_nr);
1856                        poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1857                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1858                } else {
1859                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1860                }
1861                poi_stack[poi_stack_nr++] = obj_offset;
1862                /* If parsing the base offset fails, just unwind */
1863                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1864                if (!base_offset)
1865                        goto unwind;
1866                curpos = obj_offset = base_offset;
1867                type = unpack_object_header(p, w_curs, &curpos, &size);
1868                if (type <= OBJ_NONE) {
1869                        /* If getting the base itself fails, we first
1870                         * retry the base, otherwise unwind */
1871                        type = retry_bad_packed_offset(p, base_offset);
1872                        if (type > OBJ_NONE)
1873                                goto out;
1874                        goto unwind;
1875                }
1876        }
1877
1878        switch (type) {
1879        case OBJ_BAD:
1880        case OBJ_COMMIT:
1881        case OBJ_TREE:
1882        case OBJ_BLOB:
1883        case OBJ_TAG:
1884                break;
1885        default:
1886                error("unknown object type %i at offset %"PRIuMAX" in %s",
1887                      type, (uintmax_t)obj_offset, p->pack_name);
1888                type = OBJ_BAD;
1889        }
1890
1891out:
1892        if (poi_stack != small_poi_stack)
1893                free(poi_stack);
1894        return type;
1895
1896unwind:
1897        while (poi_stack_nr) {
1898                obj_offset = poi_stack[--poi_stack_nr];
1899                type = retry_bad_packed_offset(p, obj_offset);
1900                if (type > OBJ_NONE)
1901                        goto out;
1902        }
1903        type = OBJ_BAD;
1904        goto out;
1905}
1906
1907static int packed_object_info(struct packed_git *p, off_t obj_offset,
1908                              struct object_info *oi)
1909{
1910        struct pack_window *w_curs = NULL;
1911        unsigned long size;
1912        off_t curpos = obj_offset;
1913        enum object_type type;
1914
1915        /*
1916         * We always get the representation type, but only convert it to
1917         * a "real" type later if the caller is interested.
1918         */
1919        type = unpack_object_header(p, &w_curs, &curpos, &size);
1920
1921        if (oi->sizep) {
1922                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1923                        off_t tmp_pos = curpos;
1924                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1925                                                           type, obj_offset);
1926                        if (!base_offset) {
1927                                type = OBJ_BAD;
1928                                goto out;
1929                        }
1930                        *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1931                        if (*oi->sizep == 0) {
1932                                type = OBJ_BAD;
1933                                goto out;
1934                        }
1935                } else {
1936                        *oi->sizep = size;
1937                }
1938        }
1939
1940        if (oi->disk_sizep) {
1941                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1942                *oi->disk_sizep = revidx[1].offset - obj_offset;
1943        }
1944
1945        if (oi->typep) {
1946                *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
1947                if (*oi->typep < 0) {
1948                        type = OBJ_BAD;
1949                        goto out;
1950                }
1951        }
1952
1953        if (oi->delta_base_sha1) {
1954                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1955                        const unsigned char *base;
1956
1957                        base = get_delta_base_sha1(p, &w_curs, curpos,
1958                                                   type, obj_offset);
1959                        if (!base) {
1960                                type = OBJ_BAD;
1961                                goto out;
1962                        }
1963
1964                        hashcpy(oi->delta_base_sha1, base);
1965                } else
1966                        hashclr(oi->delta_base_sha1);
1967        }
1968
1969out:
1970        unuse_pack(&w_curs);
1971        return type;
1972}
1973
1974static void *unpack_compressed_entry(struct packed_git *p,
1975                                    struct pack_window **w_curs,
1976                                    off_t curpos,
1977                                    unsigned long size)
1978{
1979        int st;
1980        git_zstream stream;
1981        unsigned char *buffer, *in;
1982
1983        buffer = xmallocz_gently(size);
1984        if (!buffer)
1985                return NULL;
1986        memset(&stream, 0, sizeof(stream));
1987        stream.next_out = buffer;
1988        stream.avail_out = size + 1;
1989
1990        git_inflate_init(&stream);
1991        do {
1992                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1993                stream.next_in = in;
1994                st = git_inflate(&stream, Z_FINISH);
1995                if (!stream.avail_out)
1996                        break; /* the payload is larger than it should be */
1997                curpos += stream.next_in - in;
1998        } while (st == Z_OK || st == Z_BUF_ERROR);
1999        git_inflate_end(&stream);
2000        if ((st != Z_STREAM_END) || stream.total_out != size) {
2001                free(buffer);
2002                return NULL;
2003        }
2004
2005        return buffer;
2006}
2007
2008#define MAX_DELTA_CACHE (256)
2009
2010static size_t delta_base_cached;
2011
2012static struct delta_base_cache_lru_list {
2013        struct delta_base_cache_lru_list *prev;
2014        struct delta_base_cache_lru_list *next;
2015} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
2016
2017static struct delta_base_cache_entry {
2018        struct delta_base_cache_lru_list lru;
2019        void *data;
2020        struct packed_git *p;
2021        off_t base_offset;
2022        unsigned long size;
2023        enum object_type type;
2024} delta_base_cache[MAX_DELTA_CACHE];
2025
2026static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
2027{
2028        unsigned long hash;
2029
2030        hash = (unsigned long)p + (unsigned long)base_offset;
2031        hash += (hash >> 8) + (hash >> 16);
2032        return hash % MAX_DELTA_CACHE;
2033}
2034
2035static struct delta_base_cache_entry *
2036get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
2037{
2038        unsigned long hash = pack_entry_hash(p, base_offset);
2039        return delta_base_cache + hash;
2040}
2041
2042static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
2043                                     struct packed_git *p, off_t base_offset)
2044{
2045        return (ent->data && ent->p == p && ent->base_offset == base_offset);
2046}
2047
2048static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
2049{
2050        struct delta_base_cache_entry *ent;
2051        ent = get_delta_base_cache_entry(p, base_offset);
2052        return eq_delta_base_cache_entry(ent, p, base_offset);
2053}
2054
2055static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
2056{
2057        ent->data = NULL;
2058        ent->lru.next->prev = ent->lru.prev;
2059        ent->lru.prev->next = ent->lru.next;
2060        delta_base_cached -= ent->size;
2061}
2062
2063static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
2064        unsigned long *base_size, enum object_type *type, int keep_cache)
2065{
2066        struct delta_base_cache_entry *ent;
2067        void *ret;
2068
2069        ent = get_delta_base_cache_entry(p, base_offset);
2070
2071        if (!eq_delta_base_cache_entry(ent, p, base_offset))
2072                return unpack_entry(p, base_offset, type, base_size);
2073
2074        ret = ent->data;
2075
2076        if (!keep_cache)
2077                clear_delta_base_cache_entry(ent);
2078        else
2079                ret = xmemdupz(ent->data, ent->size);
2080        *type = ent->type;
2081        *base_size = ent->size;
2082        return ret;
2083}
2084
2085static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
2086{
2087        if (ent->data) {
2088                free(ent->data);
2089                ent->data = NULL;
2090                ent->lru.next->prev = ent->lru.prev;
2091                ent->lru.prev->next = ent->lru.next;
2092                delta_base_cached -= ent->size;
2093        }
2094}
2095
2096void clear_delta_base_cache(void)
2097{
2098        unsigned long p;
2099        for (p = 0; p < MAX_DELTA_CACHE; p++)
2100                release_delta_base_cache(&delta_base_cache[p]);
2101}
2102
2103static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
2104        void *base, unsigned long base_size, enum object_type type)
2105{
2106        unsigned long hash = pack_entry_hash(p, base_offset);
2107        struct delta_base_cache_entry *ent = delta_base_cache + hash;
2108        struct delta_base_cache_lru_list *lru;
2109
2110        release_delta_base_cache(ent);
2111        delta_base_cached += base_size;
2112
2113        for (lru = delta_base_cache_lru.next;
2114             delta_base_cached > delta_base_cache_limit
2115             && lru != &delta_base_cache_lru;
2116             lru = lru->next) {
2117                struct delta_base_cache_entry *f = (void *)lru;
2118                if (f->type == OBJ_BLOB)
2119                        release_delta_base_cache(f);
2120        }
2121        for (lru = delta_base_cache_lru.next;
2122             delta_base_cached > delta_base_cache_limit
2123             && lru != &delta_base_cache_lru;
2124             lru = lru->next) {
2125                struct delta_base_cache_entry *f = (void *)lru;
2126                release_delta_base_cache(f);
2127        }
2128
2129        ent->p = p;
2130        ent->base_offset = base_offset;
2131        ent->type = type;
2132        ent->data = base;
2133        ent->size = base_size;
2134        ent->lru.next = &delta_base_cache_lru;
2135        ent->lru.prev = delta_base_cache_lru.prev;
2136        delta_base_cache_lru.prev->next = &ent->lru;
2137        delta_base_cache_lru.prev = &ent->lru;
2138}
2139
2140static void *read_object(const unsigned char *sha1, enum object_type *type,
2141                         unsigned long *size);
2142
2143static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
2144{
2145        static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
2146        trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
2147                         p->pack_name, (uintmax_t)obj_offset);
2148}
2149
2150int do_check_packed_object_crc;
2151
2152#define UNPACK_ENTRY_STACK_PREALLOC 64
2153struct unpack_entry_stack_ent {
2154        off_t obj_offset;
2155        off_t curpos;
2156        unsigned long size;
2157};
2158
2159void *unpack_entry(struct packed_git *p, off_t obj_offset,
2160                   enum object_type *final_type, unsigned long *final_size)
2161{
2162        struct pack_window *w_curs = NULL;
2163        off_t curpos = obj_offset;
2164        void *data = NULL;
2165        unsigned long size;
2166        enum object_type type;
2167        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2168        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2169        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2170        int base_from_cache = 0;
2171
2172        write_pack_access_log(p, obj_offset);
2173
2174        /* PHASE 1: drill down to the innermost base object */
2175        for (;;) {
2176                off_t base_offset;
2177                int i;
2178                struct delta_base_cache_entry *ent;
2179
2180                ent = get_delta_base_cache_entry(p, curpos);
2181                if (eq_delta_base_cache_entry(ent, p, curpos)) {
2182                        type = ent->type;
2183                        data = ent->data;
2184                        size = ent->size;
2185                        clear_delta_base_cache_entry(ent);
2186                        base_from_cache = 1;
2187                        break;
2188                }
2189
2190                if (do_check_packed_object_crc && p->index_version > 1) {
2191                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2192                        unsigned long len = revidx[1].offset - obj_offset;
2193                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2194                                const unsigned char *sha1 =
2195                                        nth_packed_object_sha1(p, revidx->nr);
2196                                error("bad packed object CRC for %s",
2197                                      sha1_to_hex(sha1));
2198                                mark_bad_packed_object(p, sha1);
2199                                unuse_pack(&w_curs);
2200                                return NULL;
2201                        }
2202                }
2203
2204                type = unpack_object_header(p, &w_curs, &curpos, &size);
2205                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2206                        break;
2207
2208                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2209                if (!base_offset) {
2210                        error("failed to validate delta base reference "
2211                              "at offset %"PRIuMAX" from %s",
2212                              (uintmax_t)curpos, p->pack_name);
2213                        /* bail to phase 2, in hopes of recovery */
2214                        data = NULL;
2215                        break;
2216                }
2217
2218                /* push object, proceed to base */
2219                if (delta_stack_nr >= delta_stack_alloc
2220                    && delta_stack == small_delta_stack) {
2221                        delta_stack_alloc = alloc_nr(delta_stack_nr);
2222                        delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2223                        memcpy(delta_stack, small_delta_stack,
2224                               sizeof(*delta_stack)*delta_stack_nr);
2225                } else {
2226                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2227                }
2228                i = delta_stack_nr++;
2229                delta_stack[i].obj_offset = obj_offset;
2230                delta_stack[i].curpos = curpos;
2231                delta_stack[i].size = size;
2232
2233                curpos = obj_offset = base_offset;
2234        }
2235
2236        /* PHASE 2: handle the base */
2237        switch (type) {
2238        case OBJ_OFS_DELTA:
2239        case OBJ_REF_DELTA:
2240                if (data)
2241                        die("BUG in unpack_entry: left loop at a valid delta");
2242                break;
2243        case OBJ_COMMIT:
2244        case OBJ_TREE:
2245        case OBJ_BLOB:
2246        case OBJ_TAG:
2247                if (!base_from_cache)
2248                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
2249                break;
2250        default:
2251                data = NULL;
2252                error("unknown object type %i at offset %"PRIuMAX" in %s",
2253                      type, (uintmax_t)obj_offset, p->pack_name);
2254        }
2255
2256        /* PHASE 3: apply deltas in order */
2257
2258        /* invariants:
2259         *   'data' holds the base data, or NULL if there was corruption
2260         */
2261        while (delta_stack_nr) {
2262                void *delta_data;
2263                void *base = data;
2264                unsigned long delta_size, base_size = size;
2265                int i;
2266
2267                data = NULL;
2268
2269                if (base)
2270                        add_delta_base_cache(p, obj_offset, base, base_size, type);
2271
2272                if (!base) {
2273                        /*
2274                         * We're probably in deep shit, but let's try to fetch
2275                         * the required base anyway from another pack or loose.
2276                         * This is costly but should happen only in the presence
2277                         * of a corrupted pack, and is better than failing outright.
2278                         */
2279                        struct revindex_entry *revidx;
2280                        const unsigned char *base_sha1;
2281                        revidx = find_pack_revindex(p, obj_offset);
2282                        if (revidx) {
2283                                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2284                                error("failed to read delta base object %s"
2285                                      " at offset %"PRIuMAX" from %s",
2286                                      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2287                                      p->pack_name);
2288                                mark_bad_packed_object(p, base_sha1);
2289                                base = read_object(base_sha1, &type, &base_size);
2290                        }
2291                }
2292
2293                i = --delta_stack_nr;
2294                obj_offset = delta_stack[i].obj_offset;
2295                curpos = delta_stack[i].curpos;
2296                delta_size = delta_stack[i].size;
2297
2298                if (!base)
2299                        continue;
2300
2301                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2302
2303                if (!delta_data) {
2304                        error("failed to unpack compressed delta "
2305                              "at offset %"PRIuMAX" from %s",
2306                              (uintmax_t)curpos, p->pack_name);
2307                        data = NULL;
2308                        continue;
2309                }
2310
2311                data = patch_delta(base, base_size,
2312                                   delta_data, delta_size,
2313                                   &size);
2314
2315                /*
2316                 * We could not apply the delta; warn the user, but keep going.
2317                 * Our failure will be noticed either in the next iteration of
2318                 * the loop, or if this is the final delta, in the caller when
2319                 * we return NULL. Those code paths will take care of making
2320                 * a more explicit warning and retrying with another copy of
2321                 * the object.
2322                 */
2323                if (!data)
2324                        error("failed to apply delta");
2325
2326                free(delta_data);
2327        }
2328
2329        *final_type = type;
2330        *final_size = size;
2331
2332        unuse_pack(&w_curs);
2333
2334        if (delta_stack != small_delta_stack)
2335                free(delta_stack);
2336
2337        return data;
2338}
2339
2340const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2341                                            uint32_t n)
2342{
2343        const unsigned char *index = p->index_data;
2344        if (!index) {
2345                if (open_pack_index(p))
2346                        return NULL;
2347                index = p->index_data;
2348        }
2349        if (n >= p->num_objects)
2350                return NULL;
2351        index += 4 * 256;
2352        if (p->index_version == 1) {
2353                return index + 24 * n + 4;
2354        } else {
2355                index += 8;
2356                return index + 20 * n;
2357        }
2358}
2359
2360off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2361{
2362        const unsigned char *index = p->index_data;
2363        index += 4 * 256;
2364        if (p->index_version == 1) {
2365                return ntohl(*((uint32_t *)(index + 24 * n)));
2366        } else {
2367                uint32_t off;
2368                index += 8 + p->num_objects * (20 + 4);
2369                off = ntohl(*((uint32_t *)(index + 4 * n)));
2370                if (!(off & 0x80000000))
2371                        return off;
2372                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2373                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2374                                   ntohl(*((uint32_t *)(index + 4)));
2375        }
2376}
2377
2378off_t find_pack_entry_one(const unsigned char *sha1,
2379                                  struct packed_git *p)
2380{
2381        const uint32_t *level1_ofs = p->index_data;
2382        const unsigned char *index = p->index_data;
2383        unsigned hi, lo, stride;
2384        static int use_lookup = -1;
2385        static int debug_lookup = -1;
2386
2387        if (debug_lookup < 0)
2388                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2389
2390        if (!index) {
2391                if (open_pack_index(p))
2392                        return 0;
2393                level1_ofs = p->index_data;
2394                index = p->index_data;
2395        }
2396        if (p->index_version > 1) {
2397                level1_ofs += 2;
2398                index += 8;
2399        }
2400        index += 4 * 256;
2401        hi = ntohl(level1_ofs[*sha1]);
2402        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2403        if (p->index_version > 1) {
2404                stride = 20;
2405        } else {
2406                stride = 24;
2407                index += 4;
2408        }
2409
2410        if (debug_lookup)
2411                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2412                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2413
2414        if (use_lookup < 0)
2415                use_lookup = !!getenv("GIT_USE_LOOKUP");
2416        if (use_lookup) {
2417                int pos = sha1_entry_pos(index, stride, 0,
2418                                         lo, hi, p->num_objects, sha1);
2419                if (pos < 0)
2420                        return 0;
2421                return nth_packed_object_offset(p, pos);
2422        }
2423
2424        do {
2425                unsigned mi = (lo + hi) / 2;
2426                int cmp = hashcmp(index + mi * stride, sha1);
2427
2428                if (debug_lookup)
2429                        printf("lo %u hi %u rg %u mi %u\n",
2430                               lo, hi, hi - lo, mi);
2431                if (!cmp)
2432                        return nth_packed_object_offset(p, mi);
2433                if (cmp > 0)
2434                        hi = mi;
2435                else
2436                        lo = mi+1;
2437        } while (lo < hi);
2438        return 0;
2439}
2440
2441int is_pack_valid(struct packed_git *p)
2442{
2443        /* An already open pack is known to be valid. */
2444        if (p->pack_fd != -1)
2445                return 1;
2446
2447        /* If the pack has one window completely covering the
2448         * file size, the pack is known to be valid even if
2449         * the descriptor is not currently open.
2450         */
2451        if (p->windows) {
2452                struct pack_window *w = p->windows;
2453
2454                if (!w->offset && w->len == p->pack_size)
2455                        return 1;
2456        }
2457
2458        /* Force the pack to open to prove its valid. */
2459        return !open_packed_git(p);
2460}
2461
2462static int fill_pack_entry(const unsigned char *sha1,
2463                           struct pack_entry *e,
2464                           struct packed_git *p)
2465{
2466        off_t offset;
2467
2468        if (p->num_bad_objects) {
2469                unsigned i;
2470                for (i = 0; i < p->num_bad_objects; i++)
2471                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2472                                return 0;
2473        }
2474
2475        offset = find_pack_entry_one(sha1, p);
2476        if (!offset)
2477                return 0;
2478
2479        /*
2480         * We are about to tell the caller where they can locate the
2481         * requested object.  We better make sure the packfile is
2482         * still here and can be accessed before supplying that
2483         * answer, as it may have been deleted since the index was
2484         * loaded!
2485         */
2486        if (!is_pack_valid(p))
2487                return 0;
2488        e->offset = offset;
2489        e->p = p;
2490        hashcpy(e->sha1, sha1);
2491        return 1;
2492}
2493
2494/*
2495 * Iff a pack file contains the object named by sha1, return true and
2496 * store its location to e.
2497 */
2498static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2499{
2500        struct packed_git *p;
2501
2502        prepare_packed_git();
2503        if (!packed_git)
2504                return 0;
2505
2506        if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2507                return 1;
2508
2509        for (p = packed_git; p; p = p->next) {
2510                if (p == last_found_pack)
2511                        continue; /* we already checked this one */
2512
2513                if (fill_pack_entry(sha1, e, p)) {
2514                        last_found_pack = p;
2515                        return 1;
2516                }
2517        }
2518        return 0;
2519}
2520
2521struct packed_git *find_sha1_pack(const unsigned char *sha1,
2522                                  struct packed_git *packs)
2523{
2524        struct packed_git *p;
2525
2526        for (p = packs; p; p = p->next) {
2527                if (find_pack_entry_one(sha1, p))
2528                        return p;
2529        }
2530        return NULL;
2531
2532}
2533
2534static int sha1_loose_object_info(const unsigned char *sha1,
2535                                  struct object_info *oi)
2536{
2537        int status;
2538        unsigned long mapsize, size;
2539        void *map;
2540        git_zstream stream;
2541        char hdr[32];
2542
2543        if (oi->delta_base_sha1)
2544                hashclr(oi->delta_base_sha1);
2545
2546        /*
2547         * If we don't care about type or size, then we don't
2548         * need to look inside the object at all. Note that we
2549         * do not optimize out the stat call, even if the
2550         * caller doesn't care about the disk-size, since our
2551         * return value implicitly indicates whether the
2552         * object even exists.
2553         */
2554        if (!oi->typep && !oi->sizep) {
2555                struct stat st;
2556                if (stat_sha1_file(sha1, &st) < 0)
2557                        return -1;
2558                if (oi->disk_sizep)
2559                        *oi->disk_sizep = st.st_size;
2560                return 0;
2561        }
2562
2563        map = map_sha1_file(sha1, &mapsize);
2564        if (!map)
2565                return -1;
2566        if (oi->disk_sizep)
2567                *oi->disk_sizep = mapsize;
2568        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2569                status = error("unable to unpack %s header",
2570                               sha1_to_hex(sha1));
2571        else if ((status = parse_sha1_header(hdr, &size)) < 0)
2572                status = error("unable to parse %s header", sha1_to_hex(sha1));
2573        else if (oi->sizep)
2574                *oi->sizep = size;
2575        git_inflate_end(&stream);
2576        munmap(map, mapsize);
2577        if (oi->typep)
2578                *oi->typep = status;
2579        return 0;
2580}
2581
2582int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
2583{
2584        struct cached_object *co;
2585        struct pack_entry e;
2586        int rtype;
2587        const unsigned char *real = lookup_replace_object_extended(sha1, flags);
2588
2589        co = find_cached_object(real);
2590        if (co) {
2591                if (oi->typep)
2592                        *(oi->typep) = co->type;
2593                if (oi->sizep)
2594                        *(oi->sizep) = co->size;
2595                if (oi->disk_sizep)
2596                        *(oi->disk_sizep) = 0;
2597                if (oi->delta_base_sha1)
2598                        hashclr(oi->delta_base_sha1);
2599                oi->whence = OI_CACHED;
2600                return 0;
2601        }
2602
2603        if (!find_pack_entry(real, &e)) {
2604                /* Most likely it's a loose object. */
2605                if (!sha1_loose_object_info(real, oi)) {
2606                        oi->whence = OI_LOOSE;
2607                        return 0;
2608                }
2609
2610                /* Not a loose object; someone else may have just packed it. */
2611                reprepare_packed_git();
2612                if (!find_pack_entry(real, &e))
2613                        return -1;
2614        }
2615
2616        rtype = packed_object_info(e.p, e.offset, oi);
2617        if (rtype < 0) {
2618                mark_bad_packed_object(e.p, real);
2619                return sha1_object_info_extended(real, oi, 0);
2620        } else if (in_delta_base_cache(e.p, e.offset)) {
2621                oi->whence = OI_DBCACHED;
2622        } else {
2623                oi->whence = OI_PACKED;
2624                oi->u.packed.offset = e.offset;
2625                oi->u.packed.pack = e.p;
2626                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2627                                         rtype == OBJ_OFS_DELTA);
2628        }
2629
2630        return 0;
2631}
2632
2633/* returns enum object_type or negative */
2634int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2635{
2636        enum object_type type;
2637        struct object_info oi = {NULL};
2638
2639        oi.typep = &type;
2640        oi.sizep = sizep;
2641        if (sha1_object_info_extended(sha1, &oi, LOOKUP_REPLACE_OBJECT) < 0)
2642                return -1;
2643        return type;
2644}
2645
2646static void *read_packed_sha1(const unsigned char *sha1,
2647                              enum object_type *type, unsigned long *size)
2648{
2649        struct pack_entry e;
2650        void *data;
2651
2652        if (!find_pack_entry(sha1, &e))
2653                return NULL;
2654        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2655        if (!data) {
2656                /*
2657                 * We're probably in deep shit, but let's try to fetch
2658                 * the required object anyway from another pack or loose.
2659                 * This should happen only in the presence of a corrupted
2660                 * pack, and is better than failing outright.
2661                 */
2662                error("failed to read object %s at offset %"PRIuMAX" from %s",
2663                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2664                mark_bad_packed_object(e.p, sha1);
2665                data = read_object(sha1, type, size);
2666        }
2667        return data;
2668}
2669
2670int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2671                      unsigned char *sha1)
2672{
2673        struct cached_object *co;
2674
2675        hash_sha1_file(buf, len, typename(type), sha1);
2676        if (has_sha1_file(sha1) || find_cached_object(sha1))
2677                return 0;
2678        ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
2679        co = &cached_objects[cached_object_nr++];
2680        co->size = len;
2681        co->type = type;
2682        co->buf = xmalloc(len);
2683        memcpy(co->buf, buf, len);
2684        hashcpy(co->sha1, sha1);
2685        return 0;
2686}
2687
2688static void *read_object(const unsigned char *sha1, enum object_type *type,
2689                         unsigned long *size)
2690{
2691        unsigned long mapsize;
2692        void *map, *buf;
2693        struct cached_object *co;
2694
2695        co = find_cached_object(sha1);
2696        if (co) {
2697                *type = co->type;
2698                *size = co->size;
2699                return xmemdupz(co->buf, co->size);
2700        }
2701
2702        buf = read_packed_sha1(sha1, type, size);
2703        if (buf)
2704                return buf;
2705        map = map_sha1_file(sha1, &mapsize);
2706        if (map) {
2707                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2708                munmap(map, mapsize);
2709                return buf;
2710        }
2711        reprepare_packed_git();
2712        return read_packed_sha1(sha1, type, size);
2713}
2714
2715/*
2716 * This function dies on corrupt objects; the callers who want to
2717 * deal with them should arrange to call read_object() and give error
2718 * messages themselves.
2719 */
2720void *read_sha1_file_extended(const unsigned char *sha1,
2721                              enum object_type *type,
2722                              unsigned long *size,
2723                              unsigned flag)
2724{
2725        void *data;
2726        const struct packed_git *p;
2727        const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
2728
2729        errno = 0;
2730        data = read_object(repl, type, size);
2731        if (data)
2732                return data;
2733
2734        if (errno && errno != ENOENT)
2735                die_errno("failed to read object %s", sha1_to_hex(sha1));
2736
2737        /* die if we replaced an object with one that does not exist */
2738        if (repl != sha1)
2739                die("replacement %s not found for %s",
2740                    sha1_to_hex(repl), sha1_to_hex(sha1));
2741
2742        if (has_loose_object(repl)) {
2743                const char *path = sha1_file_name(sha1);
2744
2745                die("loose object %s (stored in %s) is corrupt",
2746                    sha1_to_hex(repl), path);
2747        }
2748
2749        if ((p = has_packed_and_bad(repl)) != NULL)
2750                die("packed object %s (stored in %s) is corrupt",
2751                    sha1_to_hex(repl), p->pack_name);
2752
2753        return NULL;
2754}
2755
2756void *read_object_with_reference(const unsigned char *sha1,
2757                                 const char *required_type_name,
2758                                 unsigned long *size,
2759                                 unsigned char *actual_sha1_return)
2760{
2761        enum object_type type, required_type;
2762        void *buffer;
2763        unsigned long isize;
2764        unsigned char actual_sha1[20];
2765
2766        required_type = type_from_string(required_type_name);
2767        hashcpy(actual_sha1, sha1);
2768        while (1) {
2769                int ref_length = -1;
2770                const char *ref_type = NULL;
2771
2772                buffer = read_sha1_file(actual_sha1, &type, &isize);
2773                if (!buffer)
2774                        return NULL;
2775                if (type == required_type) {
2776                        *size = isize;
2777                        if (actual_sha1_return)
2778                                hashcpy(actual_sha1_return, actual_sha1);
2779                        return buffer;
2780                }
2781                /* Handle references */
2782                else if (type == OBJ_COMMIT)
2783                        ref_type = "tree ";
2784                else if (type == OBJ_TAG)
2785                        ref_type = "object ";
2786                else {
2787                        free(buffer);
2788                        return NULL;
2789                }
2790                ref_length = strlen(ref_type);
2791
2792                if (ref_length + 40 > isize ||
2793                    memcmp(buffer, ref_type, ref_length) ||
2794                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2795                        free(buffer);
2796                        return NULL;
2797                }
2798                free(buffer);
2799                /* Now we have the ID of the referred-to object in
2800                 * actual_sha1.  Check again. */
2801        }
2802}
2803
2804static void write_sha1_file_prepare(const void *buf, unsigned long len,
2805                                    const char *type, unsigned char *sha1,
2806                                    char *hdr, int *hdrlen)
2807{
2808        git_SHA_CTX c;
2809
2810        /* Generate the header */
2811        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2812
2813        /* Sha1.. */
2814        git_SHA1_Init(&c);
2815        git_SHA1_Update(&c, hdr, *hdrlen);
2816        git_SHA1_Update(&c, buf, len);
2817        git_SHA1_Final(sha1, &c);
2818}
2819
2820/*
2821 * Move the just written object into its final resting place.
2822 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2823 * "moving" is only a part of what it does, when no patch between
2824 * master to pu changes the call sites of this function.
2825 */
2826int move_temp_to_file(const char *tmpfile, const char *filename)
2827{
2828        int ret = 0;
2829
2830        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2831                goto try_rename;
2832        else if (link(tmpfile, filename))
2833                ret = errno;
2834
2835        /*
2836         * Coda hack - coda doesn't like cross-directory links,
2837         * so we fall back to a rename, which will mean that it
2838         * won't be able to check collisions, but that's not a
2839         * big deal.
2840         *
2841         * The same holds for FAT formatted media.
2842         *
2843         * When this succeeds, we just return.  We have nothing
2844         * left to unlink.
2845         */
2846        if (ret && ret != EEXIST) {
2847        try_rename:
2848                if (!rename(tmpfile, filename))
2849                        goto out;
2850                ret = errno;
2851        }
2852        unlink_or_warn(tmpfile);
2853        if (ret) {
2854                if (ret != EEXIST) {
2855                        return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2856                }
2857                /* FIXME!!! Collision check here ? */
2858        }
2859
2860out:
2861        if (adjust_shared_perm(filename))
2862                return error("unable to set permission to '%s'", filename);
2863        return 0;
2864}
2865
2866static int write_buffer(int fd, const void *buf, size_t len)
2867{
2868        if (write_in_full(fd, buf, len) < 0)
2869                return error("file write error (%s)", strerror(errno));
2870        return 0;
2871}
2872
2873int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2874                   unsigned char *sha1)
2875{
2876        char hdr[32];
2877        int hdrlen;
2878        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2879        return 0;
2880}
2881
2882/* Finalize a file on disk, and close it. */
2883static void close_sha1_file(int fd)
2884{
2885        if (fsync_object_files)
2886                fsync_or_die(fd, "sha1 file");
2887        if (close(fd) != 0)
2888                die_errno("error when closing sha1 file");
2889}
2890
2891/* Size of directory component, including the ending '/' */
2892static inline int directory_size(const char *filename)
2893{
2894        const char *s = strrchr(filename, '/');
2895        if (!s)
2896                return 0;
2897        return s - filename + 1;
2898}
2899
2900/*
2901 * This creates a temporary file in the same directory as the final
2902 * 'filename'
2903 *
2904 * We want to avoid cross-directory filename renames, because those
2905 * can have problems on various filesystems (FAT, NFS, Coda).
2906 */
2907static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2908{
2909        int fd, dirlen = directory_size(filename);
2910
2911        if (dirlen + 20 > bufsiz) {
2912                errno = ENAMETOOLONG;
2913                return -1;
2914        }
2915        memcpy(buffer, filename, dirlen);
2916        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2917        fd = git_mkstemp_mode(buffer, 0444);
2918        if (fd < 0 && dirlen && errno == ENOENT) {
2919                /* Make sure the directory exists */
2920                memcpy(buffer, filename, dirlen);
2921                buffer[dirlen-1] = 0;
2922                if (mkdir(buffer, 0777) && errno != EEXIST)
2923                        return -1;
2924                if (adjust_shared_perm(buffer))
2925                        return -1;
2926
2927                /* Try again */
2928                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2929                fd = git_mkstemp_mode(buffer, 0444);
2930        }
2931        return fd;
2932}
2933
2934static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2935                              const void *buf, unsigned long len, time_t mtime)
2936{
2937        int fd, ret;
2938        unsigned char compressed[4096];
2939        git_zstream stream;
2940        git_SHA_CTX c;
2941        unsigned char parano_sha1[20];
2942        static char tmp_file[PATH_MAX];
2943        const char *filename = sha1_file_name(sha1);
2944
2945        fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2946        if (fd < 0) {
2947                if (errno == EACCES)
2948                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
2949                else
2950                        return error("unable to create temporary file: %s", strerror(errno));
2951        }
2952
2953        /* Set it up */
2954        git_deflate_init(&stream, zlib_compression_level);
2955        stream.next_out = compressed;
2956        stream.avail_out = sizeof(compressed);
2957        git_SHA1_Init(&c);
2958
2959        /* First header.. */
2960        stream.next_in = (unsigned char *)hdr;
2961        stream.avail_in = hdrlen;
2962        while (git_deflate(&stream, 0) == Z_OK)
2963                ; /* nothing */
2964        git_SHA1_Update(&c, hdr, hdrlen);
2965
2966        /* Then the data itself.. */
2967        stream.next_in = (void *)buf;
2968        stream.avail_in = len;
2969        do {
2970                unsigned char *in0 = stream.next_in;
2971                ret = git_deflate(&stream, Z_FINISH);
2972                git_SHA1_Update(&c, in0, stream.next_in - in0);
2973                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2974                        die("unable to write sha1 file");
2975                stream.next_out = compressed;
2976                stream.avail_out = sizeof(compressed);
2977        } while (ret == Z_OK);
2978
2979        if (ret != Z_STREAM_END)
2980                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2981        ret = git_deflate_end_gently(&stream);
2982        if (ret != Z_OK)
2983                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2984        git_SHA1_Final(parano_sha1, &c);
2985        if (hashcmp(sha1, parano_sha1) != 0)
2986                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2987
2988        close_sha1_file(fd);
2989
2990        if (mtime) {
2991                struct utimbuf utb;
2992                utb.actime = mtime;
2993                utb.modtime = mtime;
2994                if (utime(tmp_file, &utb) < 0)
2995                        warning("failed utime() on %s: %s",
2996                                tmp_file, strerror(errno));
2997        }
2998
2999        return move_temp_to_file(tmp_file, filename);
3000}
3001
3002static int freshen_loose_object(const unsigned char *sha1)
3003{
3004        return check_and_freshen(sha1, 1);
3005}
3006
3007static int freshen_packed_object(const unsigned char *sha1)
3008{
3009        struct pack_entry e;
3010        if (!find_pack_entry(sha1, &e))
3011                return 0;
3012        if (e.p->freshened)
3013                return 1;
3014        if (!freshen_file(e.p->pack_name))
3015                return 0;
3016        e.p->freshened = 1;
3017        return 1;
3018}
3019
3020int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
3021{
3022        char hdr[32];
3023        int hdrlen;
3024
3025        /* Normally if we have it in the pack then we do not bother writing
3026         * it out into .git/objects/??/?{38} file.
3027         */
3028        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
3029        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3030                return 0;
3031        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
3032}
3033
3034int hash_sha1_file_literally(const void *buf, unsigned long len, const char *type,
3035                             unsigned char *sha1, unsigned flags)
3036{
3037        char *header;
3038        int hdrlen, status = 0;
3039
3040        /* type string, SP, %lu of the length plus NUL must fit this */
3041        header = xmalloc(strlen(type) + 32);
3042        write_sha1_file_prepare(buf, len, type, sha1, header, &hdrlen);
3043
3044        if (!(flags & HASH_WRITE_OBJECT))
3045                goto cleanup;
3046        if (freshen_packed_object(sha1) || freshen_loose_object(sha1))
3047                goto cleanup;
3048        status = write_loose_object(sha1, header, hdrlen, buf, len, 0);
3049
3050cleanup:
3051        free(header);
3052        return status;
3053}
3054
3055int force_object_loose(const unsigned char *sha1, time_t mtime)
3056{
3057        void *buf;
3058        unsigned long len;
3059        enum object_type type;
3060        char hdr[32];
3061        int hdrlen;
3062        int ret;
3063
3064        if (has_loose_object(sha1))
3065                return 0;
3066        buf = read_packed_sha1(sha1, &type, &len);
3067        if (!buf)
3068                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
3069        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
3070        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
3071        free(buf);
3072
3073        return ret;
3074}
3075
3076int has_pack_index(const unsigned char *sha1)
3077{
3078        struct stat st;
3079        if (stat(sha1_pack_index_name(sha1), &st))
3080                return 0;
3081        return 1;
3082}
3083
3084int has_sha1_pack(const unsigned char *sha1)
3085{
3086        struct pack_entry e;
3087        return find_pack_entry(sha1, &e);
3088}
3089
3090int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
3091{
3092        struct pack_entry e;
3093
3094        if (find_pack_entry(sha1, &e))
3095                return 1;
3096        if (has_loose_object(sha1))
3097                return 1;
3098        if (flags & HAS_SHA1_QUICK)
3099                return 0;
3100        reprepare_packed_git();
3101        return find_pack_entry(sha1, &e);
3102}
3103
3104static void check_tree(const void *buf, size_t size)
3105{
3106        struct tree_desc desc;
3107        struct name_entry entry;
3108
3109        init_tree_desc(&desc, buf, size);
3110        while (tree_entry(&desc, &entry))
3111                /* do nothing
3112                 * tree_entry() will die() on malformed entries */
3113                ;
3114}
3115
3116static void check_commit(const void *buf, size_t size)
3117{
3118        struct commit c;
3119        memset(&c, 0, sizeof(c));
3120        if (parse_commit_buffer(&c, buf, size))
3121                die("corrupt commit");
3122}
3123
3124static void check_tag(const void *buf, size_t size)
3125{
3126        struct tag t;
3127        memset(&t, 0, sizeof(t));
3128        if (parse_tag_buffer(&t, buf, size))
3129                die("corrupt tag");
3130}
3131
3132static int index_mem(unsigned char *sha1, void *buf, size_t size,
3133                     enum object_type type,
3134                     const char *path, unsigned flags)
3135{
3136        int ret, re_allocated = 0;
3137        int write_object = flags & HASH_WRITE_OBJECT;
3138
3139        if (!type)
3140                type = OBJ_BLOB;
3141
3142        /*
3143         * Convert blobs to git internal format
3144         */
3145        if ((type == OBJ_BLOB) && path) {
3146                struct strbuf nbuf = STRBUF_INIT;
3147                if (convert_to_git(path, buf, size, &nbuf,
3148                                   write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
3149                        buf = strbuf_detach(&nbuf, &size);
3150                        re_allocated = 1;
3151                }
3152        }
3153        if (flags & HASH_FORMAT_CHECK) {
3154                if (type == OBJ_TREE)
3155                        check_tree(buf, size);
3156                if (type == OBJ_COMMIT)
3157                        check_commit(buf, size);
3158                if (type == OBJ_TAG)
3159                        check_tag(buf, size);
3160        }
3161
3162        if (write_object)
3163                ret = write_sha1_file(buf, size, typename(type), sha1);
3164        else
3165                ret = hash_sha1_file(buf, size, typename(type), sha1);
3166        if (re_allocated)
3167                free(buf);
3168        return ret;
3169}
3170
3171static int index_stream_convert_blob(unsigned char *sha1, int fd,
3172                                     const char *path, unsigned flags)
3173{
3174        int ret;
3175        const int write_object = flags & HASH_WRITE_OBJECT;
3176        struct strbuf sbuf = STRBUF_INIT;
3177
3178        assert(path);
3179        assert(would_convert_to_git_filter_fd(path));
3180
3181        convert_to_git_filter_fd(path, fd, &sbuf,
3182                                 write_object ? safe_crlf : SAFE_CRLF_FALSE);
3183
3184        if (write_object)
3185                ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3186                                      sha1);
3187        else
3188                ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
3189                                     sha1);
3190        strbuf_release(&sbuf);
3191        return ret;
3192}
3193
3194static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
3195                      const char *path, unsigned flags)
3196{
3197        struct strbuf sbuf = STRBUF_INIT;
3198        int ret;
3199
3200        if (strbuf_read(&sbuf, fd, 4096) >= 0)
3201                ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
3202        else
3203                ret = -1;
3204        strbuf_release(&sbuf);
3205        return ret;
3206}
3207
3208#define SMALL_FILE_SIZE (32*1024)
3209
3210static int index_core(unsigned char *sha1, int fd, size_t size,
3211                      enum object_type type, const char *path,
3212                      unsigned flags)
3213{
3214        int ret;
3215
3216        if (!size) {
3217                ret = index_mem(sha1, "", size, type, path, flags);
3218        } else if (size <= SMALL_FILE_SIZE) {
3219                char *buf = xmalloc(size);
3220                if (size == read_in_full(fd, buf, size))
3221                        ret = index_mem(sha1, buf, size, type, path, flags);
3222                else
3223                        ret = error("short read %s", strerror(errno));
3224                free(buf);
3225        } else {
3226                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3227                ret = index_mem(sha1, buf, size, type, path, flags);
3228                munmap(buf, size);
3229        }
3230        return ret;
3231}
3232
3233/*
3234 * This creates one packfile per large blob unless bulk-checkin
3235 * machinery is "plugged".
3236 *
3237 * This also bypasses the usual "convert-to-git" dance, and that is on
3238 * purpose. We could write a streaming version of the converting
3239 * functions and insert that before feeding the data to fast-import
3240 * (or equivalent in-core API described above). However, that is
3241 * somewhat complicated, as we do not know the size of the filter
3242 * result, which we need to know beforehand when writing a git object.
3243 * Since the primary motivation for trying to stream from the working
3244 * tree file and to avoid mmaping it in core is to deal with large
3245 * binary blobs, they generally do not want to get any conversion, and
3246 * callers should avoid this code path when filters are requested.
3247 */
3248static int index_stream(unsigned char *sha1, int fd, size_t size,
3249                        enum object_type type, const char *path,
3250                        unsigned flags)
3251{
3252        return index_bulk_checkin(sha1, fd, size, type, path, flags);
3253}
3254
3255int index_fd(unsigned char *sha1, int fd, struct stat *st,
3256             enum object_type type, const char *path, unsigned flags)
3257{
3258        int ret;
3259
3260        /*
3261         * Call xsize_t() only when needed to avoid potentially unnecessary
3262         * die() for large files.
3263         */
3264        if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
3265                ret = index_stream_convert_blob(sha1, fd, path, flags);
3266        else if (!S_ISREG(st->st_mode))
3267                ret = index_pipe(sha1, fd, type, path, flags);
3268        else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
3269                 (path && would_convert_to_git(path)))
3270                ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
3271                                 flags);
3272        else
3273                ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
3274                                   flags);
3275        close(fd);
3276        return ret;
3277}
3278
3279int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3280{
3281        int fd;
3282        struct strbuf sb = STRBUF_INIT;
3283
3284        switch (st->st_mode & S_IFMT) {
3285        case S_IFREG:
3286                fd = open(path, O_RDONLY);
3287                if (fd < 0)
3288                        return error("open(\"%s\"): %s", path,
3289                                     strerror(errno));
3290                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3291                        return error("%s: failed to insert into database",
3292                                     path);
3293                break;
3294        case S_IFLNK:
3295                if (strbuf_readlink(&sb, path, st->st_size)) {
3296                        char *errstr = strerror(errno);
3297                        return error("readlink(\"%s\"): %s", path,
3298                                     errstr);
3299                }
3300                if (!(flags & HASH_WRITE_OBJECT))
3301                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3302                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3303                        return error("%s: failed to insert into database",
3304                                     path);
3305                strbuf_release(&sb);
3306                break;
3307        case S_IFDIR:
3308                return resolve_gitlink_ref(path, "HEAD", sha1);
3309        default:
3310                return error("%s: unsupported file type", path);
3311        }
3312        return 0;
3313}
3314
3315int read_pack_header(int fd, struct pack_header *header)
3316{
3317        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3318                /* "eof before pack header was fully read" */
3319                return PH_ERROR_EOF;
3320
3321        if (header->hdr_signature != htonl(PACK_SIGNATURE))
3322                /* "protocol error (pack signature mismatch detected)" */
3323                return PH_ERROR_PACK_SIGNATURE;
3324        if (!pack_version_ok(header->hdr_version))
3325                /* "protocol error (pack version unsupported)" */
3326                return PH_ERROR_PROTOCOL;
3327        return 0;
3328}
3329
3330void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3331{
3332        enum object_type type = sha1_object_info(sha1, NULL);
3333        if (type < 0)
3334                die("%s is not a valid object", sha1_to_hex(sha1));
3335        if (type != expect)
3336                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3337                    typename(expect));
3338}
3339
3340static int for_each_file_in_obj_subdir(int subdir_nr,
3341                                       struct strbuf *path,
3342                                       each_loose_object_fn obj_cb,
3343                                       each_loose_cruft_fn cruft_cb,
3344                                       each_loose_subdir_fn subdir_cb,
3345                                       void *data)
3346{
3347        size_t baselen = path->len;
3348        DIR *dir = opendir(path->buf);
3349        struct dirent *de;
3350        int r = 0;
3351
3352        if (!dir) {
3353                if (errno == ENOENT)
3354                        return 0;
3355                return error("unable to open %s: %s", path->buf, strerror(errno));
3356        }
3357
3358        while ((de = readdir(dir))) {
3359                if (is_dot_or_dotdot(de->d_name))
3360                        continue;
3361
3362                strbuf_setlen(path, baselen);
3363                strbuf_addf(path, "/%s", de->d_name);
3364
3365                if (strlen(de->d_name) == 38)  {
3366                        char hex[41];
3367                        unsigned char sha1[20];
3368
3369                        snprintf(hex, sizeof(hex), "%02x%s",
3370                                 subdir_nr, de->d_name);
3371                        if (!get_sha1_hex(hex, sha1)) {
3372                                if (obj_cb) {
3373                                        r = obj_cb(sha1, path->buf, data);
3374                                        if (r)
3375                                                break;
3376                                }
3377                                continue;
3378                        }
3379                }
3380
3381                if (cruft_cb) {
3382                        r = cruft_cb(de->d_name, path->buf, data);
3383                        if (r)
3384                                break;
3385                }
3386        }
3387        strbuf_setlen(path, baselen);
3388
3389        if (!r && subdir_cb)
3390                r = subdir_cb(subdir_nr, path->buf, data);
3391
3392        closedir(dir);
3393        return r;
3394}
3395
3396int for_each_loose_file_in_objdir_buf(struct strbuf *path,
3397                            each_loose_object_fn obj_cb,
3398                            each_loose_cruft_fn cruft_cb,
3399                            each_loose_subdir_fn subdir_cb,
3400                            void *data)
3401{
3402        size_t baselen = path->len;
3403        int r = 0;
3404        int i;
3405
3406        for (i = 0; i < 256; i++) {
3407                strbuf_addf(path, "/%02x", i);
3408                r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
3409                                                subdir_cb, data);
3410                strbuf_setlen(path, baselen);
3411                if (r)
3412                        break;
3413        }
3414
3415        return r;
3416}
3417
3418int for_each_loose_file_in_objdir(const char *path,
3419                                  each_loose_object_fn obj_cb,
3420                                  each_loose_cruft_fn cruft_cb,
3421                                  each_loose_subdir_fn subdir_cb,
3422                                  void *data)
3423{
3424        struct strbuf buf = STRBUF_INIT;
3425        int r;
3426
3427        strbuf_addstr(&buf, path);
3428        r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
3429                                              subdir_cb, data);
3430        strbuf_release(&buf);
3431
3432        return r;
3433}
3434
3435struct loose_alt_odb_data {
3436        each_loose_object_fn *cb;
3437        void *data;
3438};
3439
3440static int loose_from_alt_odb(struct alternate_object_database *alt,
3441                              void *vdata)
3442{
3443        struct loose_alt_odb_data *data = vdata;
3444        struct strbuf buf = STRBUF_INIT;
3445        int r;
3446
3447        /* copy base not including trailing '/' */
3448        strbuf_add(&buf, alt->base, alt->name - alt->base - 1);
3449        r = for_each_loose_file_in_objdir_buf(&buf,
3450                                              data->cb, NULL, NULL,
3451                                              data->data);
3452        strbuf_release(&buf);
3453        return r;
3454}
3455
3456int for_each_loose_object(each_loose_object_fn cb, void *data, unsigned flags)
3457{
3458        struct loose_alt_odb_data alt;
3459        int r;
3460
3461        r = for_each_loose_file_in_objdir(get_object_directory(),
3462                                          cb, NULL, NULL, data);
3463        if (r)
3464                return r;
3465
3466        if (flags & FOR_EACH_OBJECT_LOCAL_ONLY)
3467                return 0;
3468
3469        alt.cb = cb;
3470        alt.data = data;
3471        return foreach_alt_odb(loose_from_alt_odb, &alt);
3472}
3473
3474static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
3475{
3476        uint32_t i;
3477        int r = 0;
3478
3479        for (i = 0; i < p->num_objects; i++) {
3480                const unsigned char *sha1 = nth_packed_object_sha1(p, i);
3481
3482                if (!sha1)
3483                        return error("unable to get sha1 of object %u in %s",
3484                                     i, p->pack_name);
3485
3486                r = cb(sha1, p, i, data);
3487                if (r)
3488                        break;
3489        }
3490        return r;
3491}
3492
3493int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
3494{
3495        struct packed_git *p;
3496        int r = 0;
3497
3498        prepare_packed_git();
3499        for (p = packed_git; p; p = p->next) {
3500                if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
3501                        continue;
3502                r = for_each_object_in_pack(p, cb, data);
3503                if (r)
3504                        break;
3505        }
3506        return r;
3507}