sha1_file.con commit Merge branch 'mz/maint-rebase-stat-config' (25756cf)
   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 "delta.h"
  11#include "pack.h"
  12#include "blob.h"
  13#include "commit.h"
  14#include "tag.h"
  15#include "tree.h"
  16#include "refs.h"
  17#include "pack-revindex.h"
  18#include "sha1-lookup.h"
  19
  20#ifndef O_NOATIME
  21#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  22#define O_NOATIME 01000000
  23#else
  24#define O_NOATIME 0
  25#endif
  26#endif
  27
  28#ifdef NO_C99_FORMAT
  29#define SZ_FMT "lu"
  30static unsigned long sz_fmt(size_t s) { return (unsigned long)s; }
  31#else
  32#define SZ_FMT "zu"
  33static size_t sz_fmt(size_t s) { return s; }
  34#endif
  35
  36const unsigned char null_sha1[20];
  37
  38static int git_open_noatime(const char *name, struct packed_git *p);
  39
  40int safe_create_leading_directories(char *path)
  41{
  42        char *pos = path + offset_1st_component(path);
  43        struct stat st;
  44
  45        while (pos) {
  46                pos = strchr(pos, '/');
  47                if (!pos)
  48                        break;
  49                while (*++pos == '/')
  50                        ;
  51                if (!*pos)
  52                        break;
  53                *--pos = '\0';
  54                if (!stat(path, &st)) {
  55                        /* path exists */
  56                        if (!S_ISDIR(st.st_mode)) {
  57                                *pos = '/';
  58                                return -3;
  59                        }
  60                }
  61                else if (mkdir(path, 0777)) {
  62                        *pos = '/';
  63                        return -1;
  64                }
  65                else if (adjust_shared_perm(path)) {
  66                        *pos = '/';
  67                        return -2;
  68                }
  69                *pos++ = '/';
  70        }
  71        return 0;
  72}
  73
  74int safe_create_leading_directories_const(const char *path)
  75{
  76        /* path points to cache entries, so xstrdup before messing with it */
  77        char *buf = xstrdup(path);
  78        int result = safe_create_leading_directories(buf);
  79        free(buf);
  80        return result;
  81}
  82
  83static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
  84{
  85        int i;
  86        for (i = 0; i < 20; i++) {
  87                static char hex[] = "0123456789abcdef";
  88                unsigned int val = sha1[i];
  89                char *pos = pathbuf + i*2 + (i > 0);
  90                *pos++ = hex[val >> 4];
  91                *pos = hex[val & 0xf];
  92        }
  93}
  94
  95/*
  96 * NOTE! This returns a statically allocated buffer, so you have to be
  97 * careful about using it. Do an "xstrdup()" if you need to save the
  98 * filename.
  99 *
 100 * Also note that this returns the location for creating.  Reading
 101 * SHA1 file can happen from any alternate directory listed in the
 102 * DB_ENVIRONMENT environment variable if it is not found in
 103 * the primary object database.
 104 */
 105char *sha1_file_name(const unsigned char *sha1)
 106{
 107        static char buf[PATH_MAX];
 108        const char *objdir;
 109        int len;
 110
 111        objdir = get_object_directory();
 112        len = strlen(objdir);
 113
 114        /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 115        if (len + 43 > PATH_MAX)
 116                die("insanely long object directory %s", objdir);
 117        memcpy(buf, objdir, len);
 118        buf[len] = '/';
 119        buf[len+3] = '/';
 120        buf[len+42] = '\0';
 121        fill_sha1_path(buf + len + 1, sha1);
 122        return buf;
 123}
 124
 125static char *sha1_get_pack_name(const unsigned char *sha1,
 126                                char **name, char **base, const char *which)
 127{
 128        static const char hex[] = "0123456789abcdef";
 129        char *buf;
 130        int i;
 131
 132        if (!*base) {
 133                const char *sha1_file_directory = get_object_directory();
 134                int len = strlen(sha1_file_directory);
 135                *base = xmalloc(len + 60);
 136                sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 137                        sha1_file_directory, which);
 138                *name = *base + len + 11;
 139        }
 140
 141        buf = *name;
 142
 143        for (i = 0; i < 20; i++) {
 144                unsigned int val = *sha1++;
 145                *buf++ = hex[val >> 4];
 146                *buf++ = hex[val & 0xf];
 147        }
 148
 149        return *base;
 150}
 151
 152char *sha1_pack_name(const unsigned char *sha1)
 153{
 154        static char *name, *base;
 155
 156        return sha1_get_pack_name(sha1, &name, &base, "pack");
 157}
 158
 159char *sha1_pack_index_name(const unsigned char *sha1)
 160{
 161        static char *name, *base;
 162
 163        return sha1_get_pack_name(sha1, &name, &base, "idx");
 164}
 165
 166struct alternate_object_database *alt_odb_list;
 167static struct alternate_object_database **alt_odb_tail;
 168
 169static void read_info_alternates(const char * alternates, int depth);
 170
 171/*
 172 * Prepare alternate object database registry.
 173 *
 174 * The variable alt_odb_list points at the list of struct
 175 * alternate_object_database.  The elements on this list come from
 176 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 177 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 178 * whose contents is similar to that environment variable but can be
 179 * LF separated.  Its base points at a statically allocated buffer that
 180 * contains "/the/directory/corresponding/to/.git/objects/...", while
 181 * its name points just after the slash at the end of ".git/objects/"
 182 * in the example above, and has enough space to hold 40-byte hex
 183 * SHA1, an extra slash for the first level indirection, and the
 184 * terminating NUL.
 185 */
 186static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 187{
 188        const char *objdir = get_object_directory();
 189        struct alternate_object_database *ent;
 190        struct alternate_object_database *alt;
 191        /* 43 = 40-byte + 2 '/' + terminating NUL */
 192        int pfxlen = len;
 193        int entlen = pfxlen + 43;
 194        int base_len = -1;
 195
 196        if (!is_absolute_path(entry) && relative_base) {
 197                /* Relative alt-odb */
 198                if (base_len < 0)
 199                        base_len = strlen(relative_base) + 1;
 200                entlen += base_len;
 201                pfxlen += base_len;
 202        }
 203        ent = xmalloc(sizeof(*ent) + entlen);
 204
 205        if (!is_absolute_path(entry) && relative_base) {
 206                memcpy(ent->base, relative_base, base_len - 1);
 207                ent->base[base_len - 1] = '/';
 208                memcpy(ent->base + base_len, entry, len);
 209        }
 210        else
 211                memcpy(ent->base, entry, pfxlen);
 212
 213        ent->name = ent->base + pfxlen + 1;
 214        ent->base[pfxlen + 3] = '/';
 215        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 216
 217        /* Detect cases where alternate disappeared */
 218        if (!is_directory(ent->base)) {
 219                error("object directory %s does not exist; "
 220                      "check .git/objects/info/alternates.",
 221                      ent->base);
 222                free(ent);
 223                return -1;
 224        }
 225
 226        /* Prevent the common mistake of listing the same
 227         * thing twice, or object directory itself.
 228         */
 229        for (alt = alt_odb_list; alt; alt = alt->next) {
 230                if (!memcmp(ent->base, alt->base, pfxlen)) {
 231                        free(ent);
 232                        return -1;
 233                }
 234        }
 235        if (!memcmp(ent->base, objdir, pfxlen)) {
 236                free(ent);
 237                return -1;
 238        }
 239
 240        /* add the alternate entry */
 241        *alt_odb_tail = ent;
 242        alt_odb_tail = &(ent->next);
 243        ent->next = NULL;
 244
 245        /* recursively add alternates */
 246        read_info_alternates(ent->base, depth + 1);
 247
 248        ent->base[pfxlen] = '/';
 249
 250        return 0;
 251}
 252
 253static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 254                                 const char *relative_base, int depth)
 255{
 256        const char *cp, *last;
 257
 258        if (depth > 5) {
 259                error("%s: ignoring alternate object stores, nesting too deep.",
 260                                relative_base);
 261                return;
 262        }
 263
 264        last = alt;
 265        while (last < ep) {
 266                cp = last;
 267                if (cp < ep && *cp == '#') {
 268                        while (cp < ep && *cp != sep)
 269                                cp++;
 270                        last = cp + 1;
 271                        continue;
 272                }
 273                while (cp < ep && *cp != sep)
 274                        cp++;
 275                if (last != cp) {
 276                        if (!is_absolute_path(last) && depth) {
 277                                error("%s: ignoring relative alternate object store %s",
 278                                                relative_base, last);
 279                        } else {
 280                                link_alt_odb_entry(last, cp - last,
 281                                                relative_base, depth);
 282                        }
 283                }
 284                while (cp < ep && *cp == sep)
 285                        cp++;
 286                last = cp;
 287        }
 288}
 289
 290static void read_info_alternates(const char * relative_base, int depth)
 291{
 292        char *map;
 293        size_t mapsz;
 294        struct stat st;
 295        const char alt_file_name[] = "info/alternates";
 296        /* Given that relative_base is no longer than PATH_MAX,
 297           ensure that "path" has enough space to append "/", the
 298           file name, "info/alternates", and a trailing NUL.  */
 299        char path[PATH_MAX + 1 + sizeof alt_file_name];
 300        int fd;
 301
 302        sprintf(path, "%s/%s", relative_base, alt_file_name);
 303        fd = git_open_noatime(path, NULL);
 304        if (fd < 0)
 305                return;
 306        if (fstat(fd, &st) || (st.st_size == 0)) {
 307                close(fd);
 308                return;
 309        }
 310        mapsz = xsize_t(st.st_size);
 311        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 312        close(fd);
 313
 314        link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 315
 316        munmap(map, mapsz);
 317}
 318
 319void add_to_alternates_file(const char *reference)
 320{
 321        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 322        int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 323        char *alt = mkpath("%s/objects\n", reference);
 324        write_or_die(fd, alt, strlen(alt));
 325        if (commit_lock_file(lock))
 326                die("could not close alternates file");
 327        if (alt_odb_tail)
 328                link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
 329}
 330
 331void foreach_alt_odb(alt_odb_fn fn, void *cb)
 332{
 333        struct alternate_object_database *ent;
 334
 335        prepare_alt_odb();
 336        for (ent = alt_odb_list; ent; ent = ent->next)
 337                if (fn(ent, cb))
 338                        return;
 339}
 340
 341void prepare_alt_odb(void)
 342{
 343        const char *alt;
 344
 345        if (alt_odb_tail)
 346                return;
 347
 348        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 349        if (!alt) alt = "";
 350
 351        alt_odb_tail = &alt_odb_list;
 352        link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
 353
 354        read_info_alternates(get_object_directory(), 0);
 355}
 356
 357static int has_loose_object_local(const unsigned char *sha1)
 358{
 359        char *name = sha1_file_name(sha1);
 360        return !access(name, F_OK);
 361}
 362
 363int has_loose_object_nonlocal(const unsigned char *sha1)
 364{
 365        struct alternate_object_database *alt;
 366        prepare_alt_odb();
 367        for (alt = alt_odb_list; alt; alt = alt->next) {
 368                fill_sha1_path(alt->name, sha1);
 369                if (!access(alt->base, F_OK))
 370                        return 1;
 371        }
 372        return 0;
 373}
 374
 375static int has_loose_object(const unsigned char *sha1)
 376{
 377        return has_loose_object_local(sha1) ||
 378               has_loose_object_nonlocal(sha1);
 379}
 380
 381static unsigned int pack_used_ctr;
 382static unsigned int pack_mmap_calls;
 383static unsigned int peak_pack_open_windows;
 384static unsigned int pack_open_windows;
 385static size_t peak_pack_mapped;
 386static size_t pack_mapped;
 387struct packed_git *packed_git;
 388
 389void pack_report(void)
 390{
 391        fprintf(stderr,
 392                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 393                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 394                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 395                sz_fmt(getpagesize()),
 396                sz_fmt(packed_git_window_size),
 397                sz_fmt(packed_git_limit));
 398        fprintf(stderr,
 399                "pack_report: pack_used_ctr            = %10u\n"
 400                "pack_report: pack_mmap_calls          = %10u\n"
 401                "pack_report: pack_open_windows        = %10u / %10u\n"
 402                "pack_report: pack_mapped              = "
 403                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 404                pack_used_ctr,
 405                pack_mmap_calls,
 406                pack_open_windows, peak_pack_open_windows,
 407                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 408}
 409
 410static int check_packed_git_idx(const char *path,  struct packed_git *p)
 411{
 412        void *idx_map;
 413        struct pack_idx_header *hdr;
 414        size_t idx_size;
 415        uint32_t version, nr, i, *index;
 416        int fd = git_open_noatime(path, p);
 417        struct stat st;
 418
 419        if (fd < 0)
 420                return -1;
 421        if (fstat(fd, &st)) {
 422                close(fd);
 423                return -1;
 424        }
 425        idx_size = xsize_t(st.st_size);
 426        if (idx_size < 4 * 256 + 20 + 20) {
 427                close(fd);
 428                return error("index file %s is too small", path);
 429        }
 430        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 431        close(fd);
 432
 433        hdr = idx_map;
 434        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 435                version = ntohl(hdr->idx_version);
 436                if (version < 2 || version > 2) {
 437                        munmap(idx_map, idx_size);
 438                        return error("index file %s is version %"PRIu32
 439                                     " and is not supported by this binary"
 440                                     " (try upgrading GIT to a newer version)",
 441                                     path, version);
 442                }
 443        } else
 444                version = 1;
 445
 446        nr = 0;
 447        index = idx_map;
 448        if (version > 1)
 449                index += 2;  /* skip index header */
 450        for (i = 0; i < 256; i++) {
 451                uint32_t n = ntohl(index[i]);
 452                if (n < nr) {
 453                        munmap(idx_map, idx_size);
 454                        return error("non-monotonic index %s", path);
 455                }
 456                nr = n;
 457        }
 458
 459        if (version == 1) {
 460                /*
 461                 * Total size:
 462                 *  - 256 index entries 4 bytes each
 463                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 464                 *  - 20-byte SHA1 of the packfile
 465                 *  - 20-byte SHA1 file checksum
 466                 */
 467                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 468                        munmap(idx_map, idx_size);
 469                        return error("wrong index v1 file size in %s", path);
 470                }
 471        } else if (version == 2) {
 472                /*
 473                 * Minimum size:
 474                 *  - 8 bytes of header
 475                 *  - 256 index entries 4 bytes each
 476                 *  - 20-byte sha1 entry * nr
 477                 *  - 4-byte crc entry * nr
 478                 *  - 4-byte offset entry * nr
 479                 *  - 20-byte SHA1 of the packfile
 480                 *  - 20-byte SHA1 file checksum
 481                 * And after the 4-byte offset table might be a
 482                 * variable sized table containing 8-byte entries
 483                 * for offsets larger than 2^31.
 484                 */
 485                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 486                unsigned long max_size = min_size;
 487                if (nr)
 488                        max_size += (nr - 1)*8;
 489                if (idx_size < min_size || idx_size > max_size) {
 490                        munmap(idx_map, idx_size);
 491                        return error("wrong index v2 file size in %s", path);
 492                }
 493                if (idx_size != min_size &&
 494                    /*
 495                     * make sure we can deal with large pack offsets.
 496                     * 31-bit signed offset won't be enough, neither
 497                     * 32-bit unsigned one will be.
 498                     */
 499                    (sizeof(off_t) <= 4)) {
 500                        munmap(idx_map, idx_size);
 501                        return error("pack too large for current definition of off_t in %s", path);
 502                }
 503        }
 504
 505        p->index_version = version;
 506        p->index_data = idx_map;
 507        p->index_size = idx_size;
 508        p->num_objects = nr;
 509        return 0;
 510}
 511
 512int open_pack_index(struct packed_git *p)
 513{
 514        char *idx_name;
 515        int ret;
 516
 517        if (p->index_data)
 518                return 0;
 519
 520        idx_name = xstrdup(p->pack_name);
 521        strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 522        ret = check_packed_git_idx(idx_name, p);
 523        free(idx_name);
 524        return ret;
 525}
 526
 527static void scan_windows(struct packed_git *p,
 528        struct packed_git **lru_p,
 529        struct pack_window **lru_w,
 530        struct pack_window **lru_l)
 531{
 532        struct pack_window *w, *w_l;
 533
 534        for (w_l = NULL, w = p->windows; w; w = w->next) {
 535                if (!w->inuse_cnt) {
 536                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 537                                *lru_p = p;
 538                                *lru_w = w;
 539                                *lru_l = w_l;
 540                        }
 541                }
 542                w_l = w;
 543        }
 544}
 545
 546static int unuse_one_window(struct packed_git *current, int keep_fd)
 547{
 548        struct packed_git *p, *lru_p = NULL;
 549        struct pack_window *lru_w = NULL, *lru_l = NULL;
 550
 551        if (current)
 552                scan_windows(current, &lru_p, &lru_w, &lru_l);
 553        for (p = packed_git; p; p = p->next)
 554                scan_windows(p, &lru_p, &lru_w, &lru_l);
 555        if (lru_p) {
 556                munmap(lru_w->base, lru_w->len);
 557                pack_mapped -= lru_w->len;
 558                if (lru_l)
 559                        lru_l->next = lru_w->next;
 560                else {
 561                        lru_p->windows = lru_w->next;
 562                        if (!lru_p->windows && lru_p->pack_fd != keep_fd) {
 563                                close(lru_p->pack_fd);
 564                                lru_p->pack_fd = -1;
 565                        }
 566                }
 567                free(lru_w);
 568                pack_open_windows--;
 569                return 1;
 570        }
 571        return 0;
 572}
 573
 574void release_pack_memory(size_t need, int fd)
 575{
 576        size_t cur = pack_mapped;
 577        while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
 578                ; /* nothing */
 579}
 580
 581void *xmmap(void *start, size_t length,
 582        int prot, int flags, int fd, off_t offset)
 583{
 584        void *ret = mmap(start, length, prot, flags, fd, offset);
 585        if (ret == MAP_FAILED) {
 586                if (!length)
 587                        return NULL;
 588                release_pack_memory(length, fd);
 589                ret = mmap(start, length, prot, flags, fd, offset);
 590                if (ret == MAP_FAILED)
 591                        die_errno("Out of memory? mmap failed");
 592        }
 593        return ret;
 594}
 595
 596void close_pack_windows(struct packed_git *p)
 597{
 598        while (p->windows) {
 599                struct pack_window *w = p->windows;
 600
 601                if (w->inuse_cnt)
 602                        die("pack '%s' still has open windows to it",
 603                            p->pack_name);
 604                munmap(w->base, w->len);
 605                pack_mapped -= w->len;
 606                pack_open_windows--;
 607                p->windows = w->next;
 608                free(w);
 609        }
 610}
 611
 612void unuse_pack(struct pack_window **w_cursor)
 613{
 614        struct pack_window *w = *w_cursor;
 615        if (w) {
 616                w->inuse_cnt--;
 617                *w_cursor = NULL;
 618        }
 619}
 620
 621void close_pack_index(struct packed_git *p)
 622{
 623        if (p->index_data) {
 624                munmap((void *)p->index_data, p->index_size);
 625                p->index_data = NULL;
 626        }
 627}
 628
 629/*
 630 * This is used by git-repack in case a newly created pack happens to
 631 * contain the same set of objects as an existing one.  In that case
 632 * the resulting file might be different even if its name would be the
 633 * same.  It is best to close any reference to the old pack before it is
 634 * replaced on disk.  Of course no index pointers nor windows for given pack
 635 * must subsist at this point.  If ever objects from this pack are requested
 636 * again, the new version of the pack will be reinitialized through
 637 * reprepare_packed_git().
 638 */
 639void free_pack_by_name(const char *pack_name)
 640{
 641        struct packed_git *p, **pp = &packed_git;
 642
 643        while (*pp) {
 644                p = *pp;
 645                if (strcmp(pack_name, p->pack_name) == 0) {
 646                        clear_delta_base_cache();
 647                        close_pack_windows(p);
 648                        if (p->pack_fd != -1)
 649                                close(p->pack_fd);
 650                        close_pack_index(p);
 651                        free(p->bad_object_sha1);
 652                        *pp = p->next;
 653                        free(p);
 654                        return;
 655                }
 656                pp = &p->next;
 657        }
 658}
 659
 660/*
 661 * Do not call this directly as this leaks p->pack_fd on error return;
 662 * call open_packed_git() instead.
 663 */
 664static int open_packed_git_1(struct packed_git *p)
 665{
 666        struct stat st;
 667        struct pack_header hdr;
 668        unsigned char sha1[20];
 669        unsigned char *idx_sha1;
 670        long fd_flag;
 671
 672        if (!p->index_data && open_pack_index(p))
 673                return error("packfile %s index unavailable", p->pack_name);
 674
 675        p->pack_fd = git_open_noatime(p->pack_name, p);
 676        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 677                return -1;
 678
 679        /* If we created the struct before we had the pack we lack size. */
 680        if (!p->pack_size) {
 681                if (!S_ISREG(st.st_mode))
 682                        return error("packfile %s not a regular file", p->pack_name);
 683                p->pack_size = st.st_size;
 684        } else if (p->pack_size != st.st_size)
 685                return error("packfile %s size changed", p->pack_name);
 686
 687        /* We leave these file descriptors open with sliding mmap;
 688         * there is no point keeping them open across exec(), though.
 689         */
 690        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 691        if (fd_flag < 0)
 692                return error("cannot determine file descriptor flags");
 693        fd_flag |= FD_CLOEXEC;
 694        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 695                return error("cannot set FD_CLOEXEC");
 696
 697        /* Verify we recognize this pack file format. */
 698        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 699                return error("file %s is far too short to be a packfile", p->pack_name);
 700        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 701                return error("file %s is not a GIT packfile", p->pack_name);
 702        if (!pack_version_ok(hdr.hdr_version))
 703                return error("packfile %s is version %"PRIu32" and not"
 704                        " supported (try upgrading GIT to a newer version)",
 705                        p->pack_name, ntohl(hdr.hdr_version));
 706
 707        /* Verify the pack matches its index. */
 708        if (p->num_objects != ntohl(hdr.hdr_entries))
 709                return error("packfile %s claims to have %"PRIu32" objects"
 710                             " while index indicates %"PRIu32" objects",
 711                             p->pack_name, ntohl(hdr.hdr_entries),
 712                             p->num_objects);
 713        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 714                return error("end of packfile %s is unavailable", p->pack_name);
 715        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 716                return error("packfile %s signature is unavailable", p->pack_name);
 717        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 718        if (hashcmp(sha1, idx_sha1))
 719                return error("packfile %s does not match index", p->pack_name);
 720        return 0;
 721}
 722
 723static int open_packed_git(struct packed_git *p)
 724{
 725        if (!open_packed_git_1(p))
 726                return 0;
 727        if (p->pack_fd != -1) {
 728                close(p->pack_fd);
 729                p->pack_fd = -1;
 730        }
 731        return -1;
 732}
 733
 734static int in_window(struct pack_window *win, off_t offset)
 735{
 736        /* We must promise at least 20 bytes (one hash) after the
 737         * offset is available from this window, otherwise the offset
 738         * is not actually in this window and a different window (which
 739         * has that one hash excess) must be used.  This is to support
 740         * the object header and delta base parsing routines below.
 741         */
 742        off_t win_off = win->offset;
 743        return win_off <= offset
 744                && (offset + 20) <= (win_off + win->len);
 745}
 746
 747unsigned char *use_pack(struct packed_git *p,
 748                struct pack_window **w_cursor,
 749                off_t offset,
 750                unsigned int *left)
 751{
 752        struct pack_window *win = *w_cursor;
 753
 754        if (p->pack_fd == -1 && open_packed_git(p))
 755                die("packfile %s cannot be accessed", p->pack_name);
 756
 757        /* Since packfiles end in a hash of their content and it's
 758         * pointless to ask for an offset into the middle of that
 759         * hash, and the in_window function above wouldn't match
 760         * don't allow an offset too close to the end of the file.
 761         */
 762        if (offset > (p->pack_size - 20))
 763                die("offset beyond end of packfile (truncated pack?)");
 764
 765        if (!win || !in_window(win, offset)) {
 766                if (win)
 767                        win->inuse_cnt--;
 768                for (win = p->windows; win; win = win->next) {
 769                        if (in_window(win, offset))
 770                                break;
 771                }
 772                if (!win) {
 773                        size_t window_align = packed_git_window_size / 2;
 774                        off_t len;
 775                        win = xcalloc(1, sizeof(*win));
 776                        win->offset = (offset / window_align) * window_align;
 777                        len = p->pack_size - win->offset;
 778                        if (len > packed_git_window_size)
 779                                len = packed_git_window_size;
 780                        win->len = (size_t)len;
 781                        pack_mapped += win->len;
 782                        while (packed_git_limit < pack_mapped
 783                                && unuse_one_window(p, p->pack_fd))
 784                                ; /* nothing */
 785                        win->base = xmmap(NULL, win->len,
 786                                PROT_READ, MAP_PRIVATE,
 787                                p->pack_fd, win->offset);
 788                        if (win->base == MAP_FAILED)
 789                                die("packfile %s cannot be mapped: %s",
 790                                        p->pack_name,
 791                                        strerror(errno));
 792                        pack_mmap_calls++;
 793                        pack_open_windows++;
 794                        if (pack_mapped > peak_pack_mapped)
 795                                peak_pack_mapped = pack_mapped;
 796                        if (pack_open_windows > peak_pack_open_windows)
 797                                peak_pack_open_windows = pack_open_windows;
 798                        win->next = p->windows;
 799                        p->windows = win;
 800                }
 801        }
 802        if (win != *w_cursor) {
 803                win->last_used = pack_used_ctr++;
 804                win->inuse_cnt++;
 805                *w_cursor = win;
 806        }
 807        offset -= win->offset;
 808        if (left)
 809                *left = win->len - xsize_t(offset);
 810        return win->base + offset;
 811}
 812
 813static struct packed_git *alloc_packed_git(int extra)
 814{
 815        struct packed_git *p = xmalloc(sizeof(*p) + extra);
 816        memset(p, 0, sizeof(*p));
 817        p->pack_fd = -1;
 818        return p;
 819}
 820
 821static void try_to_free_pack_memory(size_t size)
 822{
 823        release_pack_memory(size, -1);
 824}
 825
 826struct packed_git *add_packed_git(const char *path, int path_len, int local)
 827{
 828        static int have_set_try_to_free_routine;
 829        struct stat st;
 830        struct packed_git *p = alloc_packed_git(path_len + 2);
 831
 832        if (!have_set_try_to_free_routine) {
 833                have_set_try_to_free_routine = 1;
 834                set_try_to_free_routine(try_to_free_pack_memory);
 835        }
 836
 837        /*
 838         * Make sure a corresponding .pack file exists and that
 839         * the index looks sane.
 840         */
 841        path_len -= strlen(".idx");
 842        if (path_len < 1) {
 843                free(p);
 844                return NULL;
 845        }
 846        memcpy(p->pack_name, path, path_len);
 847
 848        strcpy(p->pack_name + path_len, ".keep");
 849        if (!access(p->pack_name, F_OK))
 850                p->pack_keep = 1;
 851
 852        strcpy(p->pack_name + path_len, ".pack");
 853        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 854                free(p);
 855                return NULL;
 856        }
 857
 858        /* ok, it looks sane as far as we can check without
 859         * actually mapping the pack file.
 860         */
 861        p->pack_size = st.st_size;
 862        p->pack_local = local;
 863        p->mtime = st.st_mtime;
 864        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 865                hashclr(p->sha1);
 866        return p;
 867}
 868
 869struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 870{
 871        const char *path = sha1_pack_name(sha1);
 872        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 873
 874        strcpy(p->pack_name, path);
 875        hashcpy(p->sha1, sha1);
 876        if (check_packed_git_idx(idx_path, p)) {
 877                free(p);
 878                return NULL;
 879        }
 880
 881        return p;
 882}
 883
 884void install_packed_git(struct packed_git *pack)
 885{
 886        pack->next = packed_git;
 887        packed_git = pack;
 888}
 889
 890static void prepare_packed_git_one(char *objdir, int local)
 891{
 892        /* Ensure that this buffer is large enough so that we can
 893           append "/pack/" without clobbering the stack even if
 894           strlen(objdir) were PATH_MAX.  */
 895        char path[PATH_MAX + 1 + 4 + 1 + 1];
 896        int len;
 897        DIR *dir;
 898        struct dirent *de;
 899
 900        sprintf(path, "%s/pack", objdir);
 901        len = strlen(path);
 902        dir = opendir(path);
 903        while (!dir && errno == EMFILE && unuse_one_window(NULL, -1))
 904                dir = opendir(path);
 905        if (!dir) {
 906                if (errno != ENOENT)
 907                        error("unable to open object pack directory: %s: %s",
 908                              path, strerror(errno));
 909                return;
 910        }
 911        path[len++] = '/';
 912        while ((de = readdir(dir)) != NULL) {
 913                int namelen = strlen(de->d_name);
 914                struct packed_git *p;
 915
 916                if (!has_extension(de->d_name, ".idx"))
 917                        continue;
 918
 919                if (len + namelen + 1 > sizeof(path))
 920                        continue;
 921
 922                /* Don't reopen a pack we already have. */
 923                strcpy(path + len, de->d_name);
 924                for (p = packed_git; p; p = p->next) {
 925                        if (!memcmp(path, p->pack_name, len + namelen - 4))
 926                                break;
 927                }
 928                if (p)
 929                        continue;
 930                /* See if it really is a valid .idx file with corresponding
 931                 * .pack file that we can map.
 932                 */
 933                p = add_packed_git(path, len + namelen, local);
 934                if (!p)
 935                        continue;
 936                install_packed_git(p);
 937        }
 938        closedir(dir);
 939}
 940
 941static int sort_pack(const void *a_, const void *b_)
 942{
 943        struct packed_git *a = *((struct packed_git **)a_);
 944        struct packed_git *b = *((struct packed_git **)b_);
 945        int st;
 946
 947        /*
 948         * Local packs tend to contain objects specific to our
 949         * variant of the project than remote ones.  In addition,
 950         * remote ones could be on a network mounted filesystem.
 951         * Favor local ones for these reasons.
 952         */
 953        st = a->pack_local - b->pack_local;
 954        if (st)
 955                return -st;
 956
 957        /*
 958         * Younger packs tend to contain more recent objects,
 959         * and more recent objects tend to get accessed more
 960         * often.
 961         */
 962        if (a->mtime < b->mtime)
 963                return 1;
 964        else if (a->mtime == b->mtime)
 965                return 0;
 966        return -1;
 967}
 968
 969static void rearrange_packed_git(void)
 970{
 971        struct packed_git **ary, *p;
 972        int i, n;
 973
 974        for (n = 0, p = packed_git; p; p = p->next)
 975                n++;
 976        if (n < 2)
 977                return;
 978
 979        /* prepare an array of packed_git for easier sorting */
 980        ary = xcalloc(n, sizeof(struct packed_git *));
 981        for (n = 0, p = packed_git; p; p = p->next)
 982                ary[n++] = p;
 983
 984        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
 985
 986        /* link them back again */
 987        for (i = 0; i < n - 1; i++)
 988                ary[i]->next = ary[i + 1];
 989        ary[n - 1]->next = NULL;
 990        packed_git = ary[0];
 991
 992        free(ary);
 993}
 994
 995static int prepare_packed_git_run_once = 0;
 996void prepare_packed_git(void)
 997{
 998        struct alternate_object_database *alt;
 999
1000        if (prepare_packed_git_run_once)
1001                return;
1002        prepare_packed_git_one(get_object_directory(), 1);
1003        prepare_alt_odb();
1004        for (alt = alt_odb_list; alt; alt = alt->next) {
1005                alt->name[-1] = 0;
1006                prepare_packed_git_one(alt->base, 0);
1007                alt->name[-1] = '/';
1008        }
1009        rearrange_packed_git();
1010        prepare_packed_git_run_once = 1;
1011}
1012
1013void reprepare_packed_git(void)
1014{
1015        discard_revindex();
1016        prepare_packed_git_run_once = 0;
1017        prepare_packed_git();
1018}
1019
1020static void mark_bad_packed_object(struct packed_git *p,
1021                                   const unsigned char *sha1)
1022{
1023        unsigned i;
1024        for (i = 0; i < p->num_bad_objects; i++)
1025                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1026                        return;
1027        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1028        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1029        p->num_bad_objects++;
1030}
1031
1032static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1033{
1034        struct packed_git *p;
1035        unsigned i;
1036
1037        for (p = packed_git; p; p = p->next)
1038                for (i = 0; i < p->num_bad_objects; i++)
1039                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1040                                return p;
1041        return NULL;
1042}
1043
1044int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1045{
1046        unsigned char real_sha1[20];
1047        hash_sha1_file(map, size, type, real_sha1);
1048        return hashcmp(sha1, real_sha1) ? -1 : 0;
1049}
1050
1051static int git_open_noatime(const char *name, struct packed_git *p)
1052{
1053        static int sha1_file_open_flag = O_NOATIME;
1054
1055        for (;;) {
1056                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1057                if (fd >= 0)
1058                        return fd;
1059
1060                /* Might the failure be insufficient file descriptors? */
1061                if (errno == EMFILE) {
1062                        if (unuse_one_window(p, -1))
1063                                continue;
1064                        else
1065                                return -1;
1066                }
1067
1068                /* Might the failure be due to O_NOATIME? */
1069                if (errno != ENOENT && sha1_file_open_flag) {
1070                        sha1_file_open_flag = 0;
1071                        continue;
1072                }
1073
1074                return -1;
1075        }
1076}
1077
1078static int open_sha1_file(const unsigned char *sha1)
1079{
1080        int fd;
1081        char *name = sha1_file_name(sha1);
1082        struct alternate_object_database *alt;
1083
1084        fd = git_open_noatime(name, NULL);
1085        if (fd >= 0)
1086                return fd;
1087
1088        prepare_alt_odb();
1089        errno = ENOENT;
1090        for (alt = alt_odb_list; alt; alt = alt->next) {
1091                name = alt->name;
1092                fill_sha1_path(name, sha1);
1093                fd = git_open_noatime(alt->base, NULL);
1094                if (fd >= 0)
1095                        return fd;
1096        }
1097        return -1;
1098}
1099
1100static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1101{
1102        void *map;
1103        int fd;
1104
1105        fd = open_sha1_file(sha1);
1106        map = NULL;
1107        if (fd >= 0) {
1108                struct stat st;
1109
1110                if (!fstat(fd, &st)) {
1111                        *size = xsize_t(st.st_size);
1112                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1113                }
1114                close(fd);
1115        }
1116        return map;
1117}
1118
1119static int legacy_loose_object(unsigned char *map)
1120{
1121        unsigned int word;
1122
1123        /*
1124         * Is it a zlib-compressed buffer? If so, the first byte
1125         * must be 0x78 (15-bit window size, deflated), and the
1126         * first 16-bit word is evenly divisible by 31
1127         */
1128        word = (map[0] << 8) + map[1];
1129        if (map[0] == 0x78 && !(word % 31))
1130                return 1;
1131        else
1132                return 0;
1133}
1134
1135unsigned long unpack_object_header_buffer(const unsigned char *buf,
1136                unsigned long len, enum object_type *type, unsigned long *sizep)
1137{
1138        unsigned shift;
1139        unsigned long size, c;
1140        unsigned long used = 0;
1141
1142        c = buf[used++];
1143        *type = (c >> 4) & 7;
1144        size = c & 15;
1145        shift = 4;
1146        while (c & 0x80) {
1147                if (len <= used || bitsizeof(long) <= shift) {
1148                        error("bad object header");
1149                        return 0;
1150                }
1151                c = buf[used++];
1152                size += (c & 0x7f) << shift;
1153                shift += 7;
1154        }
1155        *sizep = size;
1156        return used;
1157}
1158
1159static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1160{
1161        unsigned long size, used;
1162        static const char valid_loose_object_type[8] = {
1163                0, /* OBJ_EXT */
1164                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1165                0, /* "delta" and others are invalid in a loose object */
1166        };
1167        enum object_type type;
1168
1169        /* Get the data stream */
1170        memset(stream, 0, sizeof(*stream));
1171        stream->next_in = map;
1172        stream->avail_in = mapsize;
1173        stream->next_out = buffer;
1174        stream->avail_out = bufsiz;
1175
1176        if (legacy_loose_object(map)) {
1177                git_inflate_init(stream);
1178                return git_inflate(stream, 0);
1179        }
1180
1181
1182        /*
1183         * There used to be a second loose object header format which
1184         * was meant to mimic the in-pack format, allowing for direct
1185         * copy of the object data.  This format turned up not to be
1186         * really worth it and we don't write it any longer.  But we
1187         * can still read it.
1188         */
1189        used = unpack_object_header_buffer(map, mapsize, &type, &size);
1190        if (!used || !valid_loose_object_type[type])
1191                return -1;
1192        map += used;
1193        mapsize -= used;
1194
1195        /* Set up the stream for the rest.. */
1196        stream->next_in = map;
1197        stream->avail_in = mapsize;
1198        git_inflate_init(stream);
1199
1200        /* And generate the fake traditional header */
1201        stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1202                                         typename(type), size);
1203        return 0;
1204}
1205
1206static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1207{
1208        int bytes = strlen(buffer) + 1;
1209        unsigned char *buf = xmallocz(size);
1210        unsigned long n;
1211        int status = Z_OK;
1212
1213        n = stream->total_out - bytes;
1214        if (n > size)
1215                n = size;
1216        memcpy(buf, (char *) buffer + bytes, n);
1217        bytes = n;
1218        if (bytes <= size) {
1219                /*
1220                 * The above condition must be (bytes <= size), not
1221                 * (bytes < size).  In other words, even though we
1222                 * expect no more output and set avail_out to zer0,
1223                 * the input zlib stream may have bytes that express
1224                 * "this concludes the stream", and we *do* want to
1225                 * eat that input.
1226                 *
1227                 * Otherwise we would not be able to test that we
1228                 * consumed all the input to reach the expected size;
1229                 * we also want to check that zlib tells us that all
1230                 * went well with status == Z_STREAM_END at the end.
1231                 */
1232                stream->next_out = buf + bytes;
1233                stream->avail_out = size - bytes;
1234                while (status == Z_OK)
1235                        status = git_inflate(stream, Z_FINISH);
1236        }
1237        if (status == Z_STREAM_END && !stream->avail_in) {
1238                git_inflate_end(stream);
1239                return buf;
1240        }
1241
1242        if (status < 0)
1243                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1244        else if (stream->avail_in)
1245                error("garbage at end of loose object '%s'",
1246                      sha1_to_hex(sha1));
1247        free(buf);
1248        return NULL;
1249}
1250
1251/*
1252 * We used to just use "sscanf()", but that's actually way
1253 * too permissive for what we want to check. So do an anal
1254 * object header parse by hand.
1255 */
1256static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1257{
1258        char type[10];
1259        int i;
1260        unsigned long size;
1261
1262        /*
1263         * The type can be at most ten bytes (including the
1264         * terminating '\0' that we add), and is followed by
1265         * a space.
1266         */
1267        i = 0;
1268        for (;;) {
1269                char c = *hdr++;
1270                if (c == ' ')
1271                        break;
1272                type[i++] = c;
1273                if (i >= sizeof(type))
1274                        return -1;
1275        }
1276        type[i] = 0;
1277
1278        /*
1279         * The length must follow immediately, and be in canonical
1280         * decimal format (ie "010" is not valid).
1281         */
1282        size = *hdr++ - '0';
1283        if (size > 9)
1284                return -1;
1285        if (size) {
1286                for (;;) {
1287                        unsigned long c = *hdr - '0';
1288                        if (c > 9)
1289                                break;
1290                        hdr++;
1291                        size = size * 10 + c;
1292                }
1293        }
1294        *sizep = size;
1295
1296        /*
1297         * The length must be followed by a zero byte
1298         */
1299        return *hdr ? -1 : type_from_string(type);
1300}
1301
1302static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1303{
1304        int ret;
1305        z_stream stream;
1306        char hdr[8192];
1307
1308        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1309        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1310                return NULL;
1311
1312        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1313}
1314
1315unsigned long get_size_from_delta(struct packed_git *p,
1316                                  struct pack_window **w_curs,
1317                                  off_t curpos)
1318{
1319        const unsigned char *data;
1320        unsigned char delta_head[20], *in;
1321        z_stream stream;
1322        int st;
1323
1324        memset(&stream, 0, sizeof(stream));
1325        stream.next_out = delta_head;
1326        stream.avail_out = sizeof(delta_head);
1327
1328        git_inflate_init(&stream);
1329        do {
1330                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1331                stream.next_in = in;
1332                st = git_inflate(&stream, Z_FINISH);
1333                curpos += stream.next_in - in;
1334        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1335                 stream.total_out < sizeof(delta_head));
1336        git_inflate_end(&stream);
1337        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1338                error("delta data unpack-initial failed");
1339                return 0;
1340        }
1341
1342        /* Examine the initial part of the delta to figure out
1343         * the result size.
1344         */
1345        data = delta_head;
1346
1347        /* ignore base size */
1348        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1349
1350        /* Read the result size */
1351        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1352}
1353
1354static off_t get_delta_base(struct packed_git *p,
1355                                    struct pack_window **w_curs,
1356                                    off_t *curpos,
1357                                    enum object_type type,
1358                                    off_t delta_obj_offset)
1359{
1360        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1361        off_t base_offset;
1362
1363        /* use_pack() assured us we have [base_info, base_info + 20)
1364         * as a range that we can look at without walking off the
1365         * end of the mapped window.  Its actually the hash size
1366         * that is assured.  An OFS_DELTA longer than the hash size
1367         * is stupid, as then a REF_DELTA would be smaller to store.
1368         */
1369        if (type == OBJ_OFS_DELTA) {
1370                unsigned used = 0;
1371                unsigned char c = base_info[used++];
1372                base_offset = c & 127;
1373                while (c & 128) {
1374                        base_offset += 1;
1375                        if (!base_offset || MSB(base_offset, 7))
1376                                return 0;  /* overflow */
1377                        c = base_info[used++];
1378                        base_offset = (base_offset << 7) + (c & 127);
1379                }
1380                base_offset = delta_obj_offset - base_offset;
1381                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1382                        return 0;  /* out of bound */
1383                *curpos += used;
1384        } else if (type == OBJ_REF_DELTA) {
1385                /* The base entry _must_ be in the same pack */
1386                base_offset = find_pack_entry_one(base_info, p);
1387                *curpos += 20;
1388        } else
1389                die("I am totally screwed");
1390        return base_offset;
1391}
1392
1393/* forward declaration for a mutually recursive function */
1394static int packed_object_info(struct packed_git *p, off_t offset,
1395                              unsigned long *sizep);
1396
1397static int packed_delta_info(struct packed_git *p,
1398                             struct pack_window **w_curs,
1399                             off_t curpos,
1400                             enum object_type type,
1401                             off_t obj_offset,
1402                             unsigned long *sizep)
1403{
1404        off_t base_offset;
1405
1406        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1407        if (!base_offset)
1408                return OBJ_BAD;
1409        type = packed_object_info(p, base_offset, NULL);
1410        if (type <= OBJ_NONE) {
1411                struct revindex_entry *revidx;
1412                const unsigned char *base_sha1;
1413                revidx = find_pack_revindex(p, base_offset);
1414                if (!revidx)
1415                        return OBJ_BAD;
1416                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1417                mark_bad_packed_object(p, base_sha1);
1418                type = sha1_object_info(base_sha1, NULL);
1419                if (type <= OBJ_NONE)
1420                        return OBJ_BAD;
1421        }
1422
1423        /* We choose to only get the type of the base object and
1424         * ignore potentially corrupt pack file that expects the delta
1425         * based on a base with a wrong size.  This saves tons of
1426         * inflate() calls.
1427         */
1428        if (sizep) {
1429                *sizep = get_size_from_delta(p, w_curs, curpos);
1430                if (*sizep == 0)
1431                        type = OBJ_BAD;
1432        }
1433
1434        return type;
1435}
1436
1437static int unpack_object_header(struct packed_git *p,
1438                                struct pack_window **w_curs,
1439                                off_t *curpos,
1440                                unsigned long *sizep)
1441{
1442        unsigned char *base;
1443        unsigned int left;
1444        unsigned long used;
1445        enum object_type type;
1446
1447        /* use_pack() assures us we have [base, base + 20) available
1448         * as a range that we can look at at.  (Its actually the hash
1449         * size that is assured.)  With our object header encoding
1450         * the maximum deflated object size is 2^137, which is just
1451         * insane, so we know won't exceed what we have been given.
1452         */
1453        base = use_pack(p, w_curs, *curpos, &left);
1454        used = unpack_object_header_buffer(base, left, &type, sizep);
1455        if (!used) {
1456                type = OBJ_BAD;
1457        } else
1458                *curpos += used;
1459
1460        return type;
1461}
1462
1463const char *packed_object_info_detail(struct packed_git *p,
1464                                      off_t obj_offset,
1465                                      unsigned long *size,
1466                                      unsigned long *store_size,
1467                                      unsigned int *delta_chain_length,
1468                                      unsigned char *base_sha1)
1469{
1470        struct pack_window *w_curs = NULL;
1471        off_t curpos;
1472        unsigned long dummy;
1473        unsigned char *next_sha1;
1474        enum object_type type;
1475        struct revindex_entry *revidx;
1476
1477        *delta_chain_length = 0;
1478        curpos = obj_offset;
1479        type = unpack_object_header(p, &w_curs, &curpos, size);
1480
1481        revidx = find_pack_revindex(p, obj_offset);
1482        *store_size = revidx[1].offset - obj_offset;
1483
1484        for (;;) {
1485                switch (type) {
1486                default:
1487                        die("pack %s contains unknown object type %d",
1488                            p->pack_name, type);
1489                case OBJ_COMMIT:
1490                case OBJ_TREE:
1491                case OBJ_BLOB:
1492                case OBJ_TAG:
1493                        unuse_pack(&w_curs);
1494                        return typename(type);
1495                case OBJ_OFS_DELTA:
1496                        obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1497                        if (!obj_offset)
1498                                die("pack %s contains bad delta base reference of type %s",
1499                                    p->pack_name, typename(type));
1500                        if (*delta_chain_length == 0) {
1501                                revidx = find_pack_revindex(p, obj_offset);
1502                                hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
1503                        }
1504                        break;
1505                case OBJ_REF_DELTA:
1506                        next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1507                        if (*delta_chain_length == 0)
1508                                hashcpy(base_sha1, next_sha1);
1509                        obj_offset = find_pack_entry_one(next_sha1, p);
1510                        break;
1511                }
1512                (*delta_chain_length)++;
1513                curpos = obj_offset;
1514                type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1515        }
1516}
1517
1518static int packed_object_info(struct packed_git *p, off_t obj_offset,
1519                              unsigned long *sizep)
1520{
1521        struct pack_window *w_curs = NULL;
1522        unsigned long size;
1523        off_t curpos = obj_offset;
1524        enum object_type type;
1525
1526        type = unpack_object_header(p, &w_curs, &curpos, &size);
1527
1528        switch (type) {
1529        case OBJ_OFS_DELTA:
1530        case OBJ_REF_DELTA:
1531                type = packed_delta_info(p, &w_curs, curpos,
1532                                         type, obj_offset, sizep);
1533                break;
1534        case OBJ_COMMIT:
1535        case OBJ_TREE:
1536        case OBJ_BLOB:
1537        case OBJ_TAG:
1538                if (sizep)
1539                        *sizep = size;
1540                break;
1541        default:
1542                error("unknown object type %i at offset %"PRIuMAX" in %s",
1543                      type, (uintmax_t)obj_offset, p->pack_name);
1544                type = OBJ_BAD;
1545        }
1546        unuse_pack(&w_curs);
1547        return type;
1548}
1549
1550static void *unpack_compressed_entry(struct packed_git *p,
1551                                    struct pack_window **w_curs,
1552                                    off_t curpos,
1553                                    unsigned long size)
1554{
1555        int st;
1556        z_stream stream;
1557        unsigned char *buffer, *in;
1558
1559        buffer = xmallocz(size);
1560        memset(&stream, 0, sizeof(stream));
1561        stream.next_out = buffer;
1562        stream.avail_out = size + 1;
1563
1564        git_inflate_init(&stream);
1565        do {
1566                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1567                stream.next_in = in;
1568                st = git_inflate(&stream, Z_FINISH);
1569                if (!stream.avail_out)
1570                        break; /* the payload is larger than it should be */
1571                curpos += stream.next_in - in;
1572        } while (st == Z_OK || st == Z_BUF_ERROR);
1573        git_inflate_end(&stream);
1574        if ((st != Z_STREAM_END) || stream.total_out != size) {
1575                free(buffer);
1576                return NULL;
1577        }
1578
1579        return buffer;
1580}
1581
1582#define MAX_DELTA_CACHE (256)
1583
1584static size_t delta_base_cached;
1585
1586static struct delta_base_cache_lru_list {
1587        struct delta_base_cache_lru_list *prev;
1588        struct delta_base_cache_lru_list *next;
1589} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1590
1591static struct delta_base_cache_entry {
1592        struct delta_base_cache_lru_list lru;
1593        void *data;
1594        struct packed_git *p;
1595        off_t base_offset;
1596        unsigned long size;
1597        enum object_type type;
1598} delta_base_cache[MAX_DELTA_CACHE];
1599
1600static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1601{
1602        unsigned long hash;
1603
1604        hash = (unsigned long)p + (unsigned long)base_offset;
1605        hash += (hash >> 8) + (hash >> 16);
1606        return hash % MAX_DELTA_CACHE;
1607}
1608
1609static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1610        unsigned long *base_size, enum object_type *type, int keep_cache)
1611{
1612        void *ret;
1613        unsigned long hash = pack_entry_hash(p, base_offset);
1614        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1615
1616        ret = ent->data;
1617        if (!ret || ent->p != p || ent->base_offset != base_offset)
1618                return unpack_entry(p, base_offset, type, base_size);
1619
1620        if (!keep_cache) {
1621                ent->data = NULL;
1622                ent->lru.next->prev = ent->lru.prev;
1623                ent->lru.prev->next = ent->lru.next;
1624                delta_base_cached -= ent->size;
1625        } else {
1626                ret = xmemdupz(ent->data, ent->size);
1627        }
1628        *type = ent->type;
1629        *base_size = ent->size;
1630        return ret;
1631}
1632
1633static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1634{
1635        if (ent->data) {
1636                free(ent->data);
1637                ent->data = NULL;
1638                ent->lru.next->prev = ent->lru.prev;
1639                ent->lru.prev->next = ent->lru.next;
1640                delta_base_cached -= ent->size;
1641        }
1642}
1643
1644void clear_delta_base_cache(void)
1645{
1646        unsigned long p;
1647        for (p = 0; p < MAX_DELTA_CACHE; p++)
1648                release_delta_base_cache(&delta_base_cache[p]);
1649}
1650
1651static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1652        void *base, unsigned long base_size, enum object_type type)
1653{
1654        unsigned long hash = pack_entry_hash(p, base_offset);
1655        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1656        struct delta_base_cache_lru_list *lru;
1657
1658        release_delta_base_cache(ent);
1659        delta_base_cached += base_size;
1660
1661        for (lru = delta_base_cache_lru.next;
1662             delta_base_cached > delta_base_cache_limit
1663             && lru != &delta_base_cache_lru;
1664             lru = lru->next) {
1665                struct delta_base_cache_entry *f = (void *)lru;
1666                if (f->type == OBJ_BLOB)
1667                        release_delta_base_cache(f);
1668        }
1669        for (lru = delta_base_cache_lru.next;
1670             delta_base_cached > delta_base_cache_limit
1671             && lru != &delta_base_cache_lru;
1672             lru = lru->next) {
1673                struct delta_base_cache_entry *f = (void *)lru;
1674                release_delta_base_cache(f);
1675        }
1676
1677        ent->p = p;
1678        ent->base_offset = base_offset;
1679        ent->type = type;
1680        ent->data = base;
1681        ent->size = base_size;
1682        ent->lru.next = &delta_base_cache_lru;
1683        ent->lru.prev = delta_base_cache_lru.prev;
1684        delta_base_cache_lru.prev->next = &ent->lru;
1685        delta_base_cache_lru.prev = &ent->lru;
1686}
1687
1688static void *read_object(const unsigned char *sha1, enum object_type *type,
1689                         unsigned long *size);
1690
1691static void *unpack_delta_entry(struct packed_git *p,
1692                                struct pack_window **w_curs,
1693                                off_t curpos,
1694                                unsigned long delta_size,
1695                                off_t obj_offset,
1696                                enum object_type *type,
1697                                unsigned long *sizep)
1698{
1699        void *delta_data, *result, *base;
1700        unsigned long base_size;
1701        off_t base_offset;
1702
1703        base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1704        if (!base_offset) {
1705                error("failed to validate delta base reference "
1706                      "at offset %"PRIuMAX" from %s",
1707                      (uintmax_t)curpos, p->pack_name);
1708                return NULL;
1709        }
1710        unuse_pack(w_curs);
1711        base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1712        if (!base) {
1713                /*
1714                 * We're probably in deep shit, but let's try to fetch
1715                 * the required base anyway from another pack or loose.
1716                 * This is costly but should happen only in the presence
1717                 * of a corrupted pack, and is better than failing outright.
1718                 */
1719                struct revindex_entry *revidx;
1720                const unsigned char *base_sha1;
1721                revidx = find_pack_revindex(p, base_offset);
1722                if (!revidx)
1723                        return NULL;
1724                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1725                error("failed to read delta base object %s"
1726                      " at offset %"PRIuMAX" from %s",
1727                      sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1728                      p->pack_name);
1729                mark_bad_packed_object(p, base_sha1);
1730                base = read_object(base_sha1, type, &base_size);
1731                if (!base)
1732                        return NULL;
1733        }
1734
1735        delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1736        if (!delta_data) {
1737                error("failed to unpack compressed delta "
1738                      "at offset %"PRIuMAX" from %s",
1739                      (uintmax_t)curpos, p->pack_name);
1740                free(base);
1741                return NULL;
1742        }
1743        result = patch_delta(base, base_size,
1744                             delta_data, delta_size,
1745                             sizep);
1746        if (!result)
1747                die("failed to apply delta");
1748        free(delta_data);
1749        add_delta_base_cache(p, base_offset, base, base_size, *type);
1750        return result;
1751}
1752
1753int do_check_packed_object_crc;
1754
1755void *unpack_entry(struct packed_git *p, off_t obj_offset,
1756                   enum object_type *type, unsigned long *sizep)
1757{
1758        struct pack_window *w_curs = NULL;
1759        off_t curpos = obj_offset;
1760        void *data;
1761
1762        if (do_check_packed_object_crc && p->index_version > 1) {
1763                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1764                unsigned long len = revidx[1].offset - obj_offset;
1765                if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1766                        const unsigned char *sha1 =
1767                                nth_packed_object_sha1(p, revidx->nr);
1768                        error("bad packed object CRC for %s",
1769                              sha1_to_hex(sha1));
1770                        mark_bad_packed_object(p, sha1);
1771                        unuse_pack(&w_curs);
1772                        return NULL;
1773                }
1774        }
1775
1776        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1777        switch (*type) {
1778        case OBJ_OFS_DELTA:
1779        case OBJ_REF_DELTA:
1780                data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1781                                          obj_offset, type, sizep);
1782                break;
1783        case OBJ_COMMIT:
1784        case OBJ_TREE:
1785        case OBJ_BLOB:
1786        case OBJ_TAG:
1787                data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1788                break;
1789        default:
1790                data = NULL;
1791                error("unknown object type %i at offset %"PRIuMAX" in %s",
1792                      *type, (uintmax_t)obj_offset, p->pack_name);
1793        }
1794        unuse_pack(&w_curs);
1795        return data;
1796}
1797
1798const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1799                                            uint32_t n)
1800{
1801        const unsigned char *index = p->index_data;
1802        if (!index) {
1803                if (open_pack_index(p))
1804                        return NULL;
1805                index = p->index_data;
1806        }
1807        if (n >= p->num_objects)
1808                return NULL;
1809        index += 4 * 256;
1810        if (p->index_version == 1) {
1811                return index + 24 * n + 4;
1812        } else {
1813                index += 8;
1814                return index + 20 * n;
1815        }
1816}
1817
1818off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1819{
1820        const unsigned char *index = p->index_data;
1821        index += 4 * 256;
1822        if (p->index_version == 1) {
1823                return ntohl(*((uint32_t *)(index + 24 * n)));
1824        } else {
1825                uint32_t off;
1826                index += 8 + p->num_objects * (20 + 4);
1827                off = ntohl(*((uint32_t *)(index + 4 * n)));
1828                if (!(off & 0x80000000))
1829                        return off;
1830                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1831                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1832                                   ntohl(*((uint32_t *)(index + 4)));
1833        }
1834}
1835
1836off_t find_pack_entry_one(const unsigned char *sha1,
1837                                  struct packed_git *p)
1838{
1839        const uint32_t *level1_ofs = p->index_data;
1840        const unsigned char *index = p->index_data;
1841        unsigned hi, lo, stride;
1842        static int use_lookup = -1;
1843        static int debug_lookup = -1;
1844
1845        if (debug_lookup < 0)
1846                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1847
1848        if (!index) {
1849                if (open_pack_index(p))
1850                        return 0;
1851                level1_ofs = p->index_data;
1852                index = p->index_data;
1853        }
1854        if (p->index_version > 1) {
1855                level1_ofs += 2;
1856                index += 8;
1857        }
1858        index += 4 * 256;
1859        hi = ntohl(level1_ofs[*sha1]);
1860        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1861        if (p->index_version > 1) {
1862                stride = 20;
1863        } else {
1864                stride = 24;
1865                index += 4;
1866        }
1867
1868        if (debug_lookup)
1869                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1870                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1871
1872        if (use_lookup < 0)
1873                use_lookup = !!getenv("GIT_USE_LOOKUP");
1874        if (use_lookup) {
1875                int pos = sha1_entry_pos(index, stride, 0,
1876                                         lo, hi, p->num_objects, sha1);
1877                if (pos < 0)
1878                        return 0;
1879                return nth_packed_object_offset(p, pos);
1880        }
1881
1882        do {
1883                unsigned mi = (lo + hi) / 2;
1884                int cmp = hashcmp(index + mi * stride, sha1);
1885
1886                if (debug_lookup)
1887                        printf("lo %u hi %u rg %u mi %u\n",
1888                               lo, hi, hi - lo, mi);
1889                if (!cmp)
1890                        return nth_packed_object_offset(p, mi);
1891                if (cmp > 0)
1892                        hi = mi;
1893                else
1894                        lo = mi+1;
1895        } while (lo < hi);
1896        return 0;
1897}
1898
1899static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1900{
1901        static struct packed_git *last_found = (void *)1;
1902        struct packed_git *p;
1903        off_t offset;
1904
1905        prepare_packed_git();
1906        if (!packed_git)
1907                return 0;
1908        p = (last_found == (void *)1) ? packed_git : last_found;
1909
1910        do {
1911                if (p->num_bad_objects) {
1912                        unsigned i;
1913                        for (i = 0; i < p->num_bad_objects; i++)
1914                                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1915                                        goto next;
1916                }
1917
1918                offset = find_pack_entry_one(sha1, p);
1919                if (offset) {
1920                        /*
1921                         * We are about to tell the caller where they can
1922                         * locate the requested object.  We better make
1923                         * sure the packfile is still here and can be
1924                         * accessed before supplying that answer, as
1925                         * it may have been deleted since the index
1926                         * was loaded!
1927                         */
1928                        if (p->pack_fd == -1 && open_packed_git(p)) {
1929                                error("packfile %s cannot be accessed", p->pack_name);
1930                                goto next;
1931                        }
1932                        e->offset = offset;
1933                        e->p = p;
1934                        hashcpy(e->sha1, sha1);
1935                        last_found = p;
1936                        return 1;
1937                }
1938
1939                next:
1940                if (p == last_found)
1941                        p = packed_git;
1942                else
1943                        p = p->next;
1944                if (p == last_found)
1945                        p = p->next;
1946        } while (p);
1947        return 0;
1948}
1949
1950struct packed_git *find_sha1_pack(const unsigned char *sha1,
1951                                  struct packed_git *packs)
1952{
1953        struct packed_git *p;
1954
1955        for (p = packs; p; p = p->next) {
1956                if (find_pack_entry_one(sha1, p))
1957                        return p;
1958        }
1959        return NULL;
1960
1961}
1962
1963static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
1964{
1965        int status;
1966        unsigned long mapsize, size;
1967        void *map;
1968        z_stream stream;
1969        char hdr[32];
1970
1971        map = map_sha1_file(sha1, &mapsize);
1972        if (!map)
1973                return error("unable to find %s", sha1_to_hex(sha1));
1974        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1975                status = error("unable to unpack %s header",
1976                               sha1_to_hex(sha1));
1977        else if ((status = parse_sha1_header(hdr, &size)) < 0)
1978                status = error("unable to parse %s header", sha1_to_hex(sha1));
1979        else if (sizep)
1980                *sizep = size;
1981        git_inflate_end(&stream);
1982        munmap(map, mapsize);
1983        return status;
1984}
1985
1986int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1987{
1988        struct pack_entry e;
1989        int status;
1990
1991        if (!find_pack_entry(sha1, &e)) {
1992                /* Most likely it's a loose object. */
1993                status = sha1_loose_object_info(sha1, sizep);
1994                if (status >= 0)
1995                        return status;
1996
1997                /* Not a loose object; someone else may have just packed it. */
1998                reprepare_packed_git();
1999                if (!find_pack_entry(sha1, &e))
2000                        return status;
2001        }
2002
2003        status = packed_object_info(e.p, e.offset, sizep);
2004        if (status < 0) {
2005                mark_bad_packed_object(e.p, sha1);
2006                status = sha1_object_info(sha1, sizep);
2007        }
2008
2009        return status;
2010}
2011
2012static void *read_packed_sha1(const unsigned char *sha1,
2013                              enum object_type *type, unsigned long *size)
2014{
2015        struct pack_entry e;
2016        void *data;
2017
2018        if (!find_pack_entry(sha1, &e))
2019                return NULL;
2020        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2021        if (!data) {
2022                /*
2023                 * We're probably in deep shit, but let's try to fetch
2024                 * the required object anyway from another pack or loose.
2025                 * This should happen only in the presence of a corrupted
2026                 * pack, and is better than failing outright.
2027                 */
2028                error("failed to read object %s at offset %"PRIuMAX" from %s",
2029                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2030                mark_bad_packed_object(e.p, sha1);
2031                data = read_object(sha1, type, size);
2032        }
2033        return data;
2034}
2035
2036/*
2037 * This is meant to hold a *small* number of objects that you would
2038 * want read_sha1_file() to be able to return, but yet you do not want
2039 * to write them into the object store (e.g. a browse-only
2040 * application).
2041 */
2042static struct cached_object {
2043        unsigned char sha1[20];
2044        enum object_type type;
2045        void *buf;
2046        unsigned long size;
2047} *cached_objects;
2048static int cached_object_nr, cached_object_alloc;
2049
2050static struct cached_object empty_tree = {
2051        EMPTY_TREE_SHA1_BIN,
2052        OBJ_TREE,
2053        "",
2054        0
2055};
2056
2057static struct cached_object *find_cached_object(const unsigned char *sha1)
2058{
2059        int i;
2060        struct cached_object *co = cached_objects;
2061
2062        for (i = 0; i < cached_object_nr; i++, co++) {
2063                if (!hashcmp(co->sha1, sha1))
2064                        return co;
2065        }
2066        if (!hashcmp(sha1, empty_tree.sha1))
2067                return &empty_tree;
2068        return NULL;
2069}
2070
2071int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2072                      unsigned char *sha1)
2073{
2074        struct cached_object *co;
2075
2076        hash_sha1_file(buf, len, typename(type), sha1);
2077        if (has_sha1_file(sha1) || find_cached_object(sha1))
2078                return 0;
2079        if (cached_object_alloc <= cached_object_nr) {
2080                cached_object_alloc = alloc_nr(cached_object_alloc);
2081                cached_objects = xrealloc(cached_objects,
2082                                          sizeof(*cached_objects) *
2083                                          cached_object_alloc);
2084        }
2085        co = &cached_objects[cached_object_nr++];
2086        co->size = len;
2087        co->type = type;
2088        co->buf = xmalloc(len);
2089        memcpy(co->buf, buf, len);
2090        hashcpy(co->sha1, sha1);
2091        return 0;
2092}
2093
2094static void *read_object(const unsigned char *sha1, enum object_type *type,
2095                         unsigned long *size)
2096{
2097        unsigned long mapsize;
2098        void *map, *buf;
2099        struct cached_object *co;
2100
2101        co = find_cached_object(sha1);
2102        if (co) {
2103                *type = co->type;
2104                *size = co->size;
2105                return xmemdupz(co->buf, co->size);
2106        }
2107
2108        buf = read_packed_sha1(sha1, type, size);
2109        if (buf)
2110                return buf;
2111        map = map_sha1_file(sha1, &mapsize);
2112        if (map) {
2113                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2114                munmap(map, mapsize);
2115                return buf;
2116        }
2117        reprepare_packed_git();
2118        return read_packed_sha1(sha1, type, size);
2119}
2120
2121/*
2122 * This function dies on corrupt objects; the callers who want to
2123 * deal with them should arrange to call read_object() and give error
2124 * messages themselves.
2125 */
2126void *read_sha1_file_repl(const unsigned char *sha1,
2127                          enum object_type *type,
2128                          unsigned long *size,
2129                          const unsigned char **replacement)
2130{
2131        const unsigned char *repl = lookup_replace_object(sha1);
2132        void *data;
2133        char *path;
2134        const struct packed_git *p;
2135
2136        errno = 0;
2137        data = read_object(repl, type, size);
2138        if (data) {
2139                if (replacement)
2140                        *replacement = repl;
2141                return data;
2142        }
2143
2144        if (errno != ENOENT)
2145                die_errno("failed to read object %s", sha1_to_hex(sha1));
2146
2147        /* die if we replaced an object with one that does not exist */
2148        if (repl != sha1)
2149                die("replacement %s not found for %s",
2150                    sha1_to_hex(repl), sha1_to_hex(sha1));
2151
2152        if (has_loose_object(repl)) {
2153                path = sha1_file_name(sha1);
2154                die("loose object %s (stored in %s) is corrupt",
2155                    sha1_to_hex(repl), path);
2156        }
2157
2158        if ((p = has_packed_and_bad(repl)) != NULL)
2159                die("packed object %s (stored in %s) is corrupt",
2160                    sha1_to_hex(repl), p->pack_name);
2161
2162        return NULL;
2163}
2164
2165void *read_object_with_reference(const unsigned char *sha1,
2166                                 const char *required_type_name,
2167                                 unsigned long *size,
2168                                 unsigned char *actual_sha1_return)
2169{
2170        enum object_type type, required_type;
2171        void *buffer;
2172        unsigned long isize;
2173        unsigned char actual_sha1[20];
2174
2175        required_type = type_from_string(required_type_name);
2176        hashcpy(actual_sha1, sha1);
2177        while (1) {
2178                int ref_length = -1;
2179                const char *ref_type = NULL;
2180
2181                buffer = read_sha1_file(actual_sha1, &type, &isize);
2182                if (!buffer)
2183                        return NULL;
2184                if (type == required_type) {
2185                        *size = isize;
2186                        if (actual_sha1_return)
2187                                hashcpy(actual_sha1_return, actual_sha1);
2188                        return buffer;
2189                }
2190                /* Handle references */
2191                else if (type == OBJ_COMMIT)
2192                        ref_type = "tree ";
2193                else if (type == OBJ_TAG)
2194                        ref_type = "object ";
2195                else {
2196                        free(buffer);
2197                        return NULL;
2198                }
2199                ref_length = strlen(ref_type);
2200
2201                if (ref_length + 40 > isize ||
2202                    memcmp(buffer, ref_type, ref_length) ||
2203                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2204                        free(buffer);
2205                        return NULL;
2206                }
2207                free(buffer);
2208                /* Now we have the ID of the referred-to object in
2209                 * actual_sha1.  Check again. */
2210        }
2211}
2212
2213static void write_sha1_file_prepare(const void *buf, unsigned long len,
2214                                    const char *type, unsigned char *sha1,
2215                                    char *hdr, int *hdrlen)
2216{
2217        git_SHA_CTX c;
2218
2219        /* Generate the header */
2220        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2221
2222        /* Sha1.. */
2223        git_SHA1_Init(&c);
2224        git_SHA1_Update(&c, hdr, *hdrlen);
2225        git_SHA1_Update(&c, buf, len);
2226        git_SHA1_Final(sha1, &c);
2227}
2228
2229/*
2230 * Move the just written object into its final resting place.
2231 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2232 * "moving" is only a part of what it does, when no patch between
2233 * master to pu changes the call sites of this function.
2234 */
2235int move_temp_to_file(const char *tmpfile, const char *filename)
2236{
2237        int ret = 0;
2238
2239        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2240                goto try_rename;
2241        else if (link(tmpfile, filename))
2242                ret = errno;
2243
2244        /*
2245         * Coda hack - coda doesn't like cross-directory links,
2246         * so we fall back to a rename, which will mean that it
2247         * won't be able to check collisions, but that's not a
2248         * big deal.
2249         *
2250         * The same holds for FAT formatted media.
2251         *
2252         * When this succeeds, we just return.  We have nothing
2253         * left to unlink.
2254         */
2255        if (ret && ret != EEXIST) {
2256        try_rename:
2257                if (!rename(tmpfile, filename))
2258                        goto out;
2259                ret = errno;
2260        }
2261        unlink_or_warn(tmpfile);
2262        if (ret) {
2263                if (ret != EEXIST) {
2264                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2265                }
2266                /* FIXME!!! Collision check here ? */
2267        }
2268
2269out:
2270        if (adjust_shared_perm(filename))
2271                return error("unable to set permission to '%s'", filename);
2272        return 0;
2273}
2274
2275static int write_buffer(int fd, const void *buf, size_t len)
2276{
2277        if (write_in_full(fd, buf, len) < 0)
2278                return error("file write error (%s)", strerror(errno));
2279        return 0;
2280}
2281
2282int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2283                   unsigned char *sha1)
2284{
2285        char hdr[32];
2286        int hdrlen;
2287        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2288        return 0;
2289}
2290
2291/* Finalize a file on disk, and close it. */
2292static void close_sha1_file(int fd)
2293{
2294        if (fsync_object_files)
2295                fsync_or_die(fd, "sha1 file");
2296        if (close(fd) != 0)
2297                die_errno("error when closing sha1 file");
2298}
2299
2300/* Size of directory component, including the ending '/' */
2301static inline int directory_size(const char *filename)
2302{
2303        const char *s = strrchr(filename, '/');
2304        if (!s)
2305                return 0;
2306        return s - filename + 1;
2307}
2308
2309/*
2310 * This creates a temporary file in the same directory as the final
2311 * 'filename'
2312 *
2313 * We want to avoid cross-directory filename renames, because those
2314 * can have problems on various filesystems (FAT, NFS, Coda).
2315 */
2316static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2317{
2318        int fd, dirlen = directory_size(filename);
2319
2320        if (dirlen + 20 > bufsiz) {
2321                errno = ENAMETOOLONG;
2322                return -1;
2323        }
2324        memcpy(buffer, filename, dirlen);
2325        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2326        fd = git_mkstemp_mode(buffer, 0444);
2327        if (fd < 0 && dirlen && errno == ENOENT) {
2328                /* Make sure the directory exists */
2329                memcpy(buffer, filename, dirlen);
2330                buffer[dirlen-1] = 0;
2331                if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2332                        return -1;
2333
2334                /* Try again */
2335                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2336                fd = git_mkstemp_mode(buffer, 0444);
2337        }
2338        return fd;
2339}
2340
2341static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2342                              const void *buf, unsigned long len, time_t mtime)
2343{
2344        int fd, ret;
2345        unsigned char compressed[4096];
2346        z_stream stream;
2347        git_SHA_CTX c;
2348        unsigned char parano_sha1[20];
2349        char *filename;
2350        static char tmpfile[PATH_MAX];
2351
2352        filename = sha1_file_name(sha1);
2353        fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2354        while (fd < 0 && errno == EMFILE && unuse_one_window(NULL, -1))
2355                fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2356        if (fd < 0) {
2357                if (errno == EACCES)
2358                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2359                else
2360                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
2361        }
2362
2363        /* Set it up */
2364        memset(&stream, 0, sizeof(stream));
2365        deflateInit(&stream, zlib_compression_level);
2366        stream.next_out = compressed;
2367        stream.avail_out = sizeof(compressed);
2368        git_SHA1_Init(&c);
2369
2370        /* First header.. */
2371        stream.next_in = (unsigned char *)hdr;
2372        stream.avail_in = hdrlen;
2373        while (deflate(&stream, 0) == Z_OK)
2374                /* nothing */;
2375        git_SHA1_Update(&c, hdr, hdrlen);
2376
2377        /* Then the data itself.. */
2378        stream.next_in = (void *)buf;
2379        stream.avail_in = len;
2380        do {
2381                unsigned char *in0 = stream.next_in;
2382                ret = deflate(&stream, Z_FINISH);
2383                git_SHA1_Update(&c, in0, stream.next_in - in0);
2384                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2385                        die("unable to write sha1 file");
2386                stream.next_out = compressed;
2387                stream.avail_out = sizeof(compressed);
2388        } while (ret == Z_OK);
2389
2390        if (ret != Z_STREAM_END)
2391                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2392        ret = deflateEnd(&stream);
2393        if (ret != Z_OK)
2394                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2395        git_SHA1_Final(parano_sha1, &c);
2396        if (hashcmp(sha1, parano_sha1) != 0)
2397                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2398
2399        close_sha1_file(fd);
2400
2401        if (mtime) {
2402                struct utimbuf utb;
2403                utb.actime = mtime;
2404                utb.modtime = mtime;
2405                if (utime(tmpfile, &utb) < 0)
2406                        warning("failed utime() on %s: %s",
2407                                tmpfile, strerror(errno));
2408        }
2409
2410        return move_temp_to_file(tmpfile, filename);
2411}
2412
2413int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2414{
2415        unsigned char sha1[20];
2416        char hdr[32];
2417        int hdrlen;
2418
2419        /* Normally if we have it in the pack then we do not bother writing
2420         * it out into .git/objects/??/?{38} file.
2421         */
2422        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2423        if (returnsha1)
2424                hashcpy(returnsha1, sha1);
2425        if (has_sha1_file(sha1))
2426                return 0;
2427        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2428}
2429
2430int force_object_loose(const unsigned char *sha1, time_t mtime)
2431{
2432        void *buf;
2433        unsigned long len;
2434        enum object_type type;
2435        char hdr[32];
2436        int hdrlen;
2437        int ret;
2438
2439        if (has_loose_object(sha1))
2440                return 0;
2441        buf = read_packed_sha1(sha1, &type, &len);
2442        if (!buf)
2443                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2444        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2445        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2446        free(buf);
2447
2448        return ret;
2449}
2450
2451int has_pack_index(const unsigned char *sha1)
2452{
2453        struct stat st;
2454        if (stat(sha1_pack_index_name(sha1), &st))
2455                return 0;
2456        return 1;
2457}
2458
2459int has_sha1_pack(const unsigned char *sha1)
2460{
2461        struct pack_entry e;
2462        return find_pack_entry(sha1, &e);
2463}
2464
2465int has_sha1_file(const unsigned char *sha1)
2466{
2467        struct pack_entry e;
2468
2469        if (find_pack_entry(sha1, &e))
2470                return 1;
2471        return has_loose_object(sha1);
2472}
2473
2474static int index_mem(unsigned char *sha1, void *buf, size_t size,
2475                     int write_object, enum object_type type, const char *path)
2476{
2477        int ret, re_allocated = 0;
2478
2479        if (!type)
2480                type = OBJ_BLOB;
2481
2482        /*
2483         * Convert blobs to git internal format
2484         */
2485        if ((type == OBJ_BLOB) && path) {
2486                struct strbuf nbuf = STRBUF_INIT;
2487                if (convert_to_git(path, buf, size, &nbuf,
2488                                   write_object ? safe_crlf : 0)) {
2489                        buf = strbuf_detach(&nbuf, &size);
2490                        re_allocated = 1;
2491                }
2492        }
2493
2494        if (write_object)
2495                ret = write_sha1_file(buf, size, typename(type), sha1);
2496        else
2497                ret = hash_sha1_file(buf, size, typename(type), sha1);
2498        if (re_allocated)
2499                free(buf);
2500        return ret;
2501}
2502
2503#define SMALL_FILE_SIZE (32*1024)
2504
2505int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2506             enum object_type type, const char *path)
2507{
2508        int ret;
2509        size_t size = xsize_t(st->st_size);
2510
2511        if (!S_ISREG(st->st_mode)) {
2512                struct strbuf sbuf = STRBUF_INIT;
2513                if (strbuf_read(&sbuf, fd, 4096) >= 0)
2514                        ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
2515                                        type, path);
2516                else
2517                        ret = -1;
2518                strbuf_release(&sbuf);
2519        } else if (!size) {
2520                ret = index_mem(sha1, NULL, size, write_object, type, path);
2521        } else if (size <= SMALL_FILE_SIZE) {
2522                char *buf = xmalloc(size);
2523                if (size == read_in_full(fd, buf, size))
2524                        ret = index_mem(sha1, buf, size, write_object, type,
2525                                        path);
2526                else
2527                        ret = error("short read %s", strerror(errno));
2528                free(buf);
2529        } else {
2530                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2531                ret = index_mem(sha1, buf, size, write_object, type, path);
2532                munmap(buf, size);
2533        }
2534        close(fd);
2535        return ret;
2536}
2537
2538int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2539{
2540        int fd;
2541        struct strbuf sb = STRBUF_INIT;
2542
2543        switch (st->st_mode & S_IFMT) {
2544        case S_IFREG:
2545                fd = open(path, O_RDONLY);
2546                if (fd < 0)
2547                        return error("open(\"%s\"): %s", path,
2548                                     strerror(errno));
2549                if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
2550                        return error("%s: failed to insert into database",
2551                                     path);
2552                break;
2553        case S_IFLNK:
2554                if (strbuf_readlink(&sb, path, st->st_size)) {
2555                        char *errstr = strerror(errno);
2556                        return error("readlink(\"%s\"): %s", path,
2557                                     errstr);
2558                }
2559                if (!write_object)
2560                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2561                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2562                        return error("%s: failed to insert into database",
2563                                     path);
2564                strbuf_release(&sb);
2565                break;
2566        case S_IFDIR:
2567                return resolve_gitlink_ref(path, "HEAD", sha1);
2568        default:
2569                return error("%s: unsupported file type", path);
2570        }
2571        return 0;
2572}
2573
2574int read_pack_header(int fd, struct pack_header *header)
2575{
2576        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2577                /* "eof before pack header was fully read" */
2578                return PH_ERROR_EOF;
2579
2580        if (header->hdr_signature != htonl(PACK_SIGNATURE))
2581                /* "protocol error (pack signature mismatch detected)" */
2582                return PH_ERROR_PACK_SIGNATURE;
2583        if (!pack_version_ok(header->hdr_version))
2584                /* "protocol error (pack version unsupported)" */
2585                return PH_ERROR_PROTOCOL;
2586        return 0;
2587}
2588
2589void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
2590{
2591        enum object_type type = sha1_object_info(sha1, NULL);
2592        if (type < 0)
2593                die("%s is not a valid object", sha1_to_hex(sha1));
2594        if (type != expect)
2595                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
2596                    typename(expect));
2597}