sha1_file.con commit docs: fix filter-branch subdir example for exotic repo names (6cb0186)
   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
  40/*
  41 * This is meant to hold a *small* number of objects that you would
  42 * want read_sha1_file() to be able to return, but yet you do not want
  43 * to write them into the object store (e.g. a browse-only
  44 * application).
  45 */
  46static struct cached_object {
  47        unsigned char sha1[20];
  48        enum object_type type;
  49        void *buf;
  50        unsigned long size;
  51} *cached_objects;
  52static int cached_object_nr, cached_object_alloc;
  53
  54static struct cached_object empty_tree = {
  55        EMPTY_TREE_SHA1_BIN_LITERAL,
  56        OBJ_TREE,
  57        "",
  58        0
  59};
  60
  61static struct cached_object *find_cached_object(const unsigned char *sha1)
  62{
  63        int i;
  64        struct cached_object *co = cached_objects;
  65
  66        for (i = 0; i < cached_object_nr; i++, co++) {
  67                if (!hashcmp(co->sha1, sha1))
  68                        return co;
  69        }
  70        if (!hashcmp(sha1, empty_tree.sha1))
  71                return &empty_tree;
  72        return NULL;
  73}
  74
  75int safe_create_leading_directories(char *path)
  76{
  77        char *pos = path + offset_1st_component(path);
  78        struct stat st;
  79
  80        while (pos) {
  81                pos = strchr(pos, '/');
  82                if (!pos)
  83                        break;
  84                while (*++pos == '/')
  85                        ;
  86                if (!*pos)
  87                        break;
  88                *--pos = '\0';
  89                if (!stat(path, &st)) {
  90                        /* path exists */
  91                        if (!S_ISDIR(st.st_mode)) {
  92                                *pos = '/';
  93                                return -3;
  94                        }
  95                }
  96                else if (mkdir(path, 0777)) {
  97                        *pos = '/';
  98                        return -1;
  99                }
 100                else if (adjust_shared_perm(path)) {
 101                        *pos = '/';
 102                        return -2;
 103                }
 104                *pos++ = '/';
 105        }
 106        return 0;
 107}
 108
 109int safe_create_leading_directories_const(const char *path)
 110{
 111        /* path points to cache entries, so xstrdup before messing with it */
 112        char *buf = xstrdup(path);
 113        int result = safe_create_leading_directories(buf);
 114        free(buf);
 115        return result;
 116}
 117
 118static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 119{
 120        int i;
 121        for (i = 0; i < 20; i++) {
 122                static char hex[] = "0123456789abcdef";
 123                unsigned int val = sha1[i];
 124                char *pos = pathbuf + i*2 + (i > 0);
 125                *pos++ = hex[val >> 4];
 126                *pos = hex[val & 0xf];
 127        }
 128}
 129
 130/*
 131 * NOTE! This returns a statically allocated buffer, so you have to be
 132 * careful about using it. Do an "xstrdup()" if you need to save the
 133 * filename.
 134 *
 135 * Also note that this returns the location for creating.  Reading
 136 * SHA1 file can happen from any alternate directory listed in the
 137 * DB_ENVIRONMENT environment variable if it is not found in
 138 * the primary object database.
 139 */
 140char *sha1_file_name(const unsigned char *sha1)
 141{
 142        static char buf[PATH_MAX];
 143        const char *objdir;
 144        int len;
 145
 146        objdir = get_object_directory();
 147        len = strlen(objdir);
 148
 149        /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 150        if (len + 43 > PATH_MAX)
 151                die("insanely long object directory %s", objdir);
 152        memcpy(buf, objdir, len);
 153        buf[len] = '/';
 154        buf[len+3] = '/';
 155        buf[len+42] = '\0';
 156        fill_sha1_path(buf + len + 1, sha1);
 157        return buf;
 158}
 159
 160static char *sha1_get_pack_name(const unsigned char *sha1,
 161                                char **name, char **base, const char *which)
 162{
 163        static const char hex[] = "0123456789abcdef";
 164        char *buf;
 165        int i;
 166
 167        if (!*base) {
 168                const char *sha1_file_directory = get_object_directory();
 169                int len = strlen(sha1_file_directory);
 170                *base = xmalloc(len + 60);
 171                sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 172                        sha1_file_directory, which);
 173                *name = *base + len + 11;
 174        }
 175
 176        buf = *name;
 177
 178        for (i = 0; i < 20; i++) {
 179                unsigned int val = *sha1++;
 180                *buf++ = hex[val >> 4];
 181                *buf++ = hex[val & 0xf];
 182        }
 183
 184        return *base;
 185}
 186
 187char *sha1_pack_name(const unsigned char *sha1)
 188{
 189        static char *name, *base;
 190
 191        return sha1_get_pack_name(sha1, &name, &base, "pack");
 192}
 193
 194char *sha1_pack_index_name(const unsigned char *sha1)
 195{
 196        static char *name, *base;
 197
 198        return sha1_get_pack_name(sha1, &name, &base, "idx");
 199}
 200
 201struct alternate_object_database *alt_odb_list;
 202static struct alternate_object_database **alt_odb_tail;
 203
 204static void read_info_alternates(const char * alternates, int depth);
 205
 206/*
 207 * Prepare alternate object database registry.
 208 *
 209 * The variable alt_odb_list points at the list of struct
 210 * alternate_object_database.  The elements on this list come from
 211 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 212 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 213 * whose contents is similar to that environment variable but can be
 214 * LF separated.  Its base points at a statically allocated buffer that
 215 * contains "/the/directory/corresponding/to/.git/objects/...", while
 216 * its name points just after the slash at the end of ".git/objects/"
 217 * in the example above, and has enough space to hold 40-byte hex
 218 * SHA1, an extra slash for the first level indirection, and the
 219 * terminating NUL.
 220 */
 221static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 222{
 223        const char *objdir = get_object_directory();
 224        struct alternate_object_database *ent;
 225        struct alternate_object_database *alt;
 226        /* 43 = 40-byte + 2 '/' + terminating NUL */
 227        int pfxlen = len;
 228        int entlen = pfxlen + 43;
 229        int base_len = -1;
 230
 231        if (!is_absolute_path(entry) && relative_base) {
 232                /* Relative alt-odb */
 233                if (base_len < 0)
 234                        base_len = strlen(relative_base) + 1;
 235                entlen += base_len;
 236                pfxlen += base_len;
 237        }
 238        ent = xmalloc(sizeof(*ent) + entlen);
 239
 240        if (!is_absolute_path(entry) && relative_base) {
 241                memcpy(ent->base, relative_base, base_len - 1);
 242                ent->base[base_len - 1] = '/';
 243                memcpy(ent->base + base_len, entry, len);
 244        }
 245        else
 246                memcpy(ent->base, entry, pfxlen);
 247
 248        ent->name = ent->base + pfxlen + 1;
 249        ent->base[pfxlen + 3] = '/';
 250        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 251
 252        /* Detect cases where alternate disappeared */
 253        if (!is_directory(ent->base)) {
 254                error("object directory %s does not exist; "
 255                      "check .git/objects/info/alternates.",
 256                      ent->base);
 257                free(ent);
 258                return -1;
 259        }
 260
 261        /* Prevent the common mistake of listing the same
 262         * thing twice, or object directory itself.
 263         */
 264        for (alt = alt_odb_list; alt; alt = alt->next) {
 265                if (!memcmp(ent->base, alt->base, pfxlen)) {
 266                        free(ent);
 267                        return -1;
 268                }
 269        }
 270        if (!memcmp(ent->base, objdir, pfxlen)) {
 271                free(ent);
 272                return -1;
 273        }
 274
 275        /* add the alternate entry */
 276        *alt_odb_tail = ent;
 277        alt_odb_tail = &(ent->next);
 278        ent->next = NULL;
 279
 280        /* recursively add alternates */
 281        read_info_alternates(ent->base, depth + 1);
 282
 283        ent->base[pfxlen] = '/';
 284
 285        return 0;
 286}
 287
 288static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 289                                 const char *relative_base, int depth)
 290{
 291        const char *cp, *last;
 292
 293        if (depth > 5) {
 294                error("%s: ignoring alternate object stores, nesting too deep.",
 295                                relative_base);
 296                return;
 297        }
 298
 299        last = alt;
 300        while (last < ep) {
 301                cp = last;
 302                if (cp < ep && *cp == '#') {
 303                        while (cp < ep && *cp != sep)
 304                                cp++;
 305                        last = cp + 1;
 306                        continue;
 307                }
 308                while (cp < ep && *cp != sep)
 309                        cp++;
 310                if (last != cp) {
 311                        if (!is_absolute_path(last) && depth) {
 312                                error("%s: ignoring relative alternate object store %s",
 313                                                relative_base, last);
 314                        } else {
 315                                link_alt_odb_entry(last, cp - last,
 316                                                relative_base, depth);
 317                        }
 318                }
 319                while (cp < ep && *cp == sep)
 320                        cp++;
 321                last = cp;
 322        }
 323}
 324
 325static void read_info_alternates(const char * relative_base, int depth)
 326{
 327        char *map;
 328        size_t mapsz;
 329        struct stat st;
 330        const char alt_file_name[] = "info/alternates";
 331        /* Given that relative_base is no longer than PATH_MAX,
 332           ensure that "path" has enough space to append "/", the
 333           file name, "info/alternates", and a trailing NUL.  */
 334        char path[PATH_MAX + 1 + sizeof alt_file_name];
 335        int fd;
 336
 337        sprintf(path, "%s/%s", relative_base, alt_file_name);
 338        fd = git_open_noatime(path, NULL);
 339        if (fd < 0)
 340                return;
 341        if (fstat(fd, &st) || (st.st_size == 0)) {
 342                close(fd);
 343                return;
 344        }
 345        mapsz = xsize_t(st.st_size);
 346        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 347        close(fd);
 348
 349        link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 350
 351        munmap(map, mapsz);
 352}
 353
 354void add_to_alternates_file(const char *reference)
 355{
 356        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 357        int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 358        char *alt = mkpath("%s/objects\n", reference);
 359        write_or_die(fd, alt, strlen(alt));
 360        if (commit_lock_file(lock))
 361                die("could not close alternates file");
 362        if (alt_odb_tail)
 363                link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
 364}
 365
 366void foreach_alt_odb(alt_odb_fn fn, void *cb)
 367{
 368        struct alternate_object_database *ent;
 369
 370        prepare_alt_odb();
 371        for (ent = alt_odb_list; ent; ent = ent->next)
 372                if (fn(ent, cb))
 373                        return;
 374}
 375
 376void prepare_alt_odb(void)
 377{
 378        const char *alt;
 379
 380        if (alt_odb_tail)
 381                return;
 382
 383        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 384        if (!alt) alt = "";
 385
 386        alt_odb_tail = &alt_odb_list;
 387        link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
 388
 389        read_info_alternates(get_object_directory(), 0);
 390}
 391
 392static int has_loose_object_local(const unsigned char *sha1)
 393{
 394        char *name = sha1_file_name(sha1);
 395        return !access(name, F_OK);
 396}
 397
 398int has_loose_object_nonlocal(const unsigned char *sha1)
 399{
 400        struct alternate_object_database *alt;
 401        prepare_alt_odb();
 402        for (alt = alt_odb_list; alt; alt = alt->next) {
 403                fill_sha1_path(alt->name, sha1);
 404                if (!access(alt->base, F_OK))
 405                        return 1;
 406        }
 407        return 0;
 408}
 409
 410static int has_loose_object(const unsigned char *sha1)
 411{
 412        return has_loose_object_local(sha1) ||
 413               has_loose_object_nonlocal(sha1);
 414}
 415
 416static unsigned int pack_used_ctr;
 417static unsigned int pack_mmap_calls;
 418static unsigned int peak_pack_open_windows;
 419static unsigned int pack_open_windows;
 420static unsigned int pack_open_fds;
 421static unsigned int pack_max_fds;
 422static size_t peak_pack_mapped;
 423static size_t pack_mapped;
 424struct packed_git *packed_git;
 425
 426void pack_report(void)
 427{
 428        fprintf(stderr,
 429                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 430                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 431                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 432                sz_fmt(getpagesize()),
 433                sz_fmt(packed_git_window_size),
 434                sz_fmt(packed_git_limit));
 435        fprintf(stderr,
 436                "pack_report: pack_used_ctr            = %10u\n"
 437                "pack_report: pack_mmap_calls          = %10u\n"
 438                "pack_report: pack_open_windows        = %10u / %10u\n"
 439                "pack_report: pack_mapped              = "
 440                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 441                pack_used_ctr,
 442                pack_mmap_calls,
 443                pack_open_windows, peak_pack_open_windows,
 444                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 445}
 446
 447static int check_packed_git_idx(const char *path,  struct packed_git *p)
 448{
 449        void *idx_map;
 450        struct pack_idx_header *hdr;
 451        size_t idx_size;
 452        uint32_t version, nr, i, *index;
 453        int fd = git_open_noatime(path, p);
 454        struct stat st;
 455
 456        if (fd < 0)
 457                return -1;
 458        if (fstat(fd, &st)) {
 459                close(fd);
 460                return -1;
 461        }
 462        idx_size = xsize_t(st.st_size);
 463        if (idx_size < 4 * 256 + 20 + 20) {
 464                close(fd);
 465                return error("index file %s is too small", path);
 466        }
 467        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 468        close(fd);
 469
 470        hdr = idx_map;
 471        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 472                version = ntohl(hdr->idx_version);
 473                if (version < 2 || version > 2) {
 474                        munmap(idx_map, idx_size);
 475                        return error("index file %s is version %"PRIu32
 476                                     " and is not supported by this binary"
 477                                     " (try upgrading GIT to a newer version)",
 478                                     path, version);
 479                }
 480        } else
 481                version = 1;
 482
 483        nr = 0;
 484        index = idx_map;
 485        if (version > 1)
 486                index += 2;  /* skip index header */
 487        for (i = 0; i < 256; i++) {
 488                uint32_t n = ntohl(index[i]);
 489                if (n < nr) {
 490                        munmap(idx_map, idx_size);
 491                        return error("non-monotonic index %s", path);
 492                }
 493                nr = n;
 494        }
 495
 496        if (version == 1) {
 497                /*
 498                 * Total size:
 499                 *  - 256 index entries 4 bytes each
 500                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 501                 *  - 20-byte SHA1 of the packfile
 502                 *  - 20-byte SHA1 file checksum
 503                 */
 504                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 505                        munmap(idx_map, idx_size);
 506                        return error("wrong index v1 file size in %s", path);
 507                }
 508        } else if (version == 2) {
 509                /*
 510                 * Minimum size:
 511                 *  - 8 bytes of header
 512                 *  - 256 index entries 4 bytes each
 513                 *  - 20-byte sha1 entry * nr
 514                 *  - 4-byte crc entry * nr
 515                 *  - 4-byte offset entry * nr
 516                 *  - 20-byte SHA1 of the packfile
 517                 *  - 20-byte SHA1 file checksum
 518                 * And after the 4-byte offset table might be a
 519                 * variable sized table containing 8-byte entries
 520                 * for offsets larger than 2^31.
 521                 */
 522                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 523                unsigned long max_size = min_size;
 524                if (nr)
 525                        max_size += (nr - 1)*8;
 526                if (idx_size < min_size || idx_size > max_size) {
 527                        munmap(idx_map, idx_size);
 528                        return error("wrong index v2 file size in %s", path);
 529                }
 530                if (idx_size != min_size &&
 531                    /*
 532                     * make sure we can deal with large pack offsets.
 533                     * 31-bit signed offset won't be enough, neither
 534                     * 32-bit unsigned one will be.
 535                     */
 536                    (sizeof(off_t) <= 4)) {
 537                        munmap(idx_map, idx_size);
 538                        return error("pack too large for current definition of off_t in %s", path);
 539                }
 540        }
 541
 542        p->index_version = version;
 543        p->index_data = idx_map;
 544        p->index_size = idx_size;
 545        p->num_objects = nr;
 546        return 0;
 547}
 548
 549int open_pack_index(struct packed_git *p)
 550{
 551        char *idx_name;
 552        int ret;
 553
 554        if (p->index_data)
 555                return 0;
 556
 557        idx_name = xstrdup(p->pack_name);
 558        strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 559        ret = check_packed_git_idx(idx_name, p);
 560        free(idx_name);
 561        return ret;
 562}
 563
 564static void scan_windows(struct packed_git *p,
 565        struct packed_git **lru_p,
 566        struct pack_window **lru_w,
 567        struct pack_window **lru_l)
 568{
 569        struct pack_window *w, *w_l;
 570
 571        for (w_l = NULL, w = p->windows; w; w = w->next) {
 572                if (!w->inuse_cnt) {
 573                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 574                                *lru_p = p;
 575                                *lru_w = w;
 576                                *lru_l = w_l;
 577                        }
 578                }
 579                w_l = w;
 580        }
 581}
 582
 583static int unuse_one_window(struct packed_git *current, int keep_fd)
 584{
 585        struct packed_git *p, *lru_p = NULL;
 586        struct pack_window *lru_w = NULL, *lru_l = NULL;
 587
 588        if (current)
 589                scan_windows(current, &lru_p, &lru_w, &lru_l);
 590        for (p = packed_git; p; p = p->next)
 591                scan_windows(p, &lru_p, &lru_w, &lru_l);
 592        if (lru_p) {
 593                munmap(lru_w->base, lru_w->len);
 594                pack_mapped -= lru_w->len;
 595                if (lru_l)
 596                        lru_l->next = lru_w->next;
 597                else {
 598                        lru_p->windows = lru_w->next;
 599                        if (!lru_p->windows && lru_p->pack_fd != -1
 600                                && lru_p->pack_fd != keep_fd) {
 601                                close(lru_p->pack_fd);
 602                                pack_open_fds--;
 603                                lru_p->pack_fd = -1;
 604                        }
 605                }
 606                free(lru_w);
 607                pack_open_windows--;
 608                return 1;
 609        }
 610        return 0;
 611}
 612
 613void release_pack_memory(size_t need, int fd)
 614{
 615        size_t cur = pack_mapped;
 616        while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
 617                ; /* nothing */
 618}
 619
 620void *xmmap(void *start, size_t length,
 621        int prot, int flags, int fd, off_t offset)
 622{
 623        void *ret = mmap(start, length, prot, flags, fd, offset);
 624        if (ret == MAP_FAILED) {
 625                if (!length)
 626                        return NULL;
 627                release_pack_memory(length, fd);
 628                ret = mmap(start, length, prot, flags, fd, offset);
 629                if (ret == MAP_FAILED)
 630                        die_errno("Out of memory? mmap failed");
 631        }
 632        return ret;
 633}
 634
 635void close_pack_windows(struct packed_git *p)
 636{
 637        while (p->windows) {
 638                struct pack_window *w = p->windows;
 639
 640                if (w->inuse_cnt)
 641                        die("pack '%s' still has open windows to it",
 642                            p->pack_name);
 643                munmap(w->base, w->len);
 644                pack_mapped -= w->len;
 645                pack_open_windows--;
 646                p->windows = w->next;
 647                free(w);
 648        }
 649}
 650
 651void unuse_pack(struct pack_window **w_cursor)
 652{
 653        struct pack_window *w = *w_cursor;
 654        if (w) {
 655                w->inuse_cnt--;
 656                *w_cursor = NULL;
 657        }
 658}
 659
 660void close_pack_index(struct packed_git *p)
 661{
 662        if (p->index_data) {
 663                munmap((void *)p->index_data, p->index_size);
 664                p->index_data = NULL;
 665        }
 666}
 667
 668/*
 669 * This is used by git-repack in case a newly created pack happens to
 670 * contain the same set of objects as an existing one.  In that case
 671 * the resulting file might be different even if its name would be the
 672 * same.  It is best to close any reference to the old pack before it is
 673 * replaced on disk.  Of course no index pointers nor windows for given pack
 674 * must subsist at this point.  If ever objects from this pack are requested
 675 * again, the new version of the pack will be reinitialized through
 676 * reprepare_packed_git().
 677 */
 678void free_pack_by_name(const char *pack_name)
 679{
 680        struct packed_git *p, **pp = &packed_git;
 681
 682        while (*pp) {
 683                p = *pp;
 684                if (strcmp(pack_name, p->pack_name) == 0) {
 685                        clear_delta_base_cache();
 686                        close_pack_windows(p);
 687                        if (p->pack_fd != -1) {
 688                                close(p->pack_fd);
 689                                pack_open_fds--;
 690                        }
 691                        close_pack_index(p);
 692                        free(p->bad_object_sha1);
 693                        *pp = p->next;
 694                        free(p);
 695                        return;
 696                }
 697                pp = &p->next;
 698        }
 699}
 700
 701/*
 702 * Do not call this directly as this leaks p->pack_fd on error return;
 703 * call open_packed_git() instead.
 704 */
 705static int open_packed_git_1(struct packed_git *p)
 706{
 707        struct stat st;
 708        struct pack_header hdr;
 709        unsigned char sha1[20];
 710        unsigned char *idx_sha1;
 711        long fd_flag;
 712
 713        if (!p->index_data && open_pack_index(p))
 714                return error("packfile %s index unavailable", p->pack_name);
 715
 716        if (!pack_max_fds) {
 717                struct rlimit lim;
 718                unsigned int max_fds;
 719
 720                if (getrlimit(RLIMIT_NOFILE, &lim))
 721                        die_errno("cannot get RLIMIT_NOFILE");
 722
 723                max_fds = lim.rlim_cur;
 724
 725                /* Save 3 for stdin/stdout/stderr, 22 for work */
 726                if (25 < max_fds)
 727                        pack_max_fds = max_fds - 25;
 728                else
 729                        pack_max_fds = 1;
 730        }
 731
 732        while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
 733                ; /* nothing */
 734
 735        p->pack_fd = git_open_noatime(p->pack_name, p);
 736        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 737                return -1;
 738        pack_open_fds++;
 739
 740        /* If we created the struct before we had the pack we lack size. */
 741        if (!p->pack_size) {
 742                if (!S_ISREG(st.st_mode))
 743                        return error("packfile %s not a regular file", p->pack_name);
 744                p->pack_size = st.st_size;
 745        } else if (p->pack_size != st.st_size)
 746                return error("packfile %s size changed", p->pack_name);
 747
 748        /* We leave these file descriptors open with sliding mmap;
 749         * there is no point keeping them open across exec(), though.
 750         */
 751        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 752        if (fd_flag < 0)
 753                return error("cannot determine file descriptor flags");
 754        fd_flag |= FD_CLOEXEC;
 755        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 756                return error("cannot set FD_CLOEXEC");
 757
 758        /* Verify we recognize this pack file format. */
 759        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 760                return error("file %s is far too short to be a packfile", p->pack_name);
 761        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 762                return error("file %s is not a GIT packfile", p->pack_name);
 763        if (!pack_version_ok(hdr.hdr_version))
 764                return error("packfile %s is version %"PRIu32" and not"
 765                        " supported (try upgrading GIT to a newer version)",
 766                        p->pack_name, ntohl(hdr.hdr_version));
 767
 768        /* Verify the pack matches its index. */
 769        if (p->num_objects != ntohl(hdr.hdr_entries))
 770                return error("packfile %s claims to have %"PRIu32" objects"
 771                             " while index indicates %"PRIu32" objects",
 772                             p->pack_name, ntohl(hdr.hdr_entries),
 773                             p->num_objects);
 774        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 775                return error("end of packfile %s is unavailable", p->pack_name);
 776        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 777                return error("packfile %s signature is unavailable", p->pack_name);
 778        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 779        if (hashcmp(sha1, idx_sha1))
 780                return error("packfile %s does not match index", p->pack_name);
 781        return 0;
 782}
 783
 784static int open_packed_git(struct packed_git *p)
 785{
 786        if (!open_packed_git_1(p))
 787                return 0;
 788        if (p->pack_fd != -1) {
 789                close(p->pack_fd);
 790                pack_open_fds--;
 791                p->pack_fd = -1;
 792        }
 793        return -1;
 794}
 795
 796static int in_window(struct pack_window *win, off_t offset)
 797{
 798        /* We must promise at least 20 bytes (one hash) after the
 799         * offset is available from this window, otherwise the offset
 800         * is not actually in this window and a different window (which
 801         * has that one hash excess) must be used.  This is to support
 802         * the object header and delta base parsing routines below.
 803         */
 804        off_t win_off = win->offset;
 805        return win_off <= offset
 806                && (offset + 20) <= (win_off + win->len);
 807}
 808
 809unsigned char *use_pack(struct packed_git *p,
 810                struct pack_window **w_cursor,
 811                off_t offset,
 812                unsigned int *left)
 813{
 814        struct pack_window *win = *w_cursor;
 815
 816        /* Since packfiles end in a hash of their content and it's
 817         * pointless to ask for an offset into the middle of that
 818         * hash, and the in_window function above wouldn't match
 819         * don't allow an offset too close to the end of the file.
 820         */
 821        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 822                die("packfile %s cannot be accessed", p->pack_name);
 823        if (offset > (p->pack_size - 20))
 824                die("offset beyond end of packfile (truncated pack?)");
 825
 826        if (!win || !in_window(win, offset)) {
 827                if (win)
 828                        win->inuse_cnt--;
 829                for (win = p->windows; win; win = win->next) {
 830                        if (in_window(win, offset))
 831                                break;
 832                }
 833                if (!win) {
 834                        size_t window_align = packed_git_window_size / 2;
 835                        off_t len;
 836
 837                        if (p->pack_fd == -1 && open_packed_git(p))
 838                                die("packfile %s cannot be accessed", p->pack_name);
 839
 840                        win = xcalloc(1, sizeof(*win));
 841                        win->offset = (offset / window_align) * window_align;
 842                        len = p->pack_size - win->offset;
 843                        if (len > packed_git_window_size)
 844                                len = packed_git_window_size;
 845                        win->len = (size_t)len;
 846                        pack_mapped += win->len;
 847                        while (packed_git_limit < pack_mapped
 848                                && unuse_one_window(p, p->pack_fd))
 849                                ; /* nothing */
 850                        win->base = xmmap(NULL, win->len,
 851                                PROT_READ, MAP_PRIVATE,
 852                                p->pack_fd, win->offset);
 853                        if (win->base == MAP_FAILED)
 854                                die("packfile %s cannot be mapped: %s",
 855                                        p->pack_name,
 856                                        strerror(errno));
 857                        if (!win->offset && win->len == p->pack_size
 858                                && !p->do_not_close) {
 859                                close(p->pack_fd);
 860                                pack_open_fds--;
 861                                p->pack_fd = -1;
 862                        }
 863                        pack_mmap_calls++;
 864                        pack_open_windows++;
 865                        if (pack_mapped > peak_pack_mapped)
 866                                peak_pack_mapped = pack_mapped;
 867                        if (pack_open_windows > peak_pack_open_windows)
 868                                peak_pack_open_windows = pack_open_windows;
 869                        win->next = p->windows;
 870                        p->windows = win;
 871                }
 872        }
 873        if (win != *w_cursor) {
 874                win->last_used = pack_used_ctr++;
 875                win->inuse_cnt++;
 876                *w_cursor = win;
 877        }
 878        offset -= win->offset;
 879        if (left)
 880                *left = win->len - xsize_t(offset);
 881        return win->base + offset;
 882}
 883
 884static struct packed_git *alloc_packed_git(int extra)
 885{
 886        struct packed_git *p = xmalloc(sizeof(*p) + extra);
 887        memset(p, 0, sizeof(*p));
 888        p->pack_fd = -1;
 889        return p;
 890}
 891
 892static void try_to_free_pack_memory(size_t size)
 893{
 894        release_pack_memory(size, -1);
 895}
 896
 897struct packed_git *add_packed_git(const char *path, int path_len, int local)
 898{
 899        static int have_set_try_to_free_routine;
 900        struct stat st;
 901        struct packed_git *p = alloc_packed_git(path_len + 2);
 902
 903        if (!have_set_try_to_free_routine) {
 904                have_set_try_to_free_routine = 1;
 905                set_try_to_free_routine(try_to_free_pack_memory);
 906        }
 907
 908        /*
 909         * Make sure a corresponding .pack file exists and that
 910         * the index looks sane.
 911         */
 912        path_len -= strlen(".idx");
 913        if (path_len < 1) {
 914                free(p);
 915                return NULL;
 916        }
 917        memcpy(p->pack_name, path, path_len);
 918
 919        strcpy(p->pack_name + path_len, ".keep");
 920        if (!access(p->pack_name, F_OK))
 921                p->pack_keep = 1;
 922
 923        strcpy(p->pack_name + path_len, ".pack");
 924        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 925                free(p);
 926                return NULL;
 927        }
 928
 929        /* ok, it looks sane as far as we can check without
 930         * actually mapping the pack file.
 931         */
 932        p->pack_size = st.st_size;
 933        p->pack_local = local;
 934        p->mtime = st.st_mtime;
 935        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 936                hashclr(p->sha1);
 937        return p;
 938}
 939
 940struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 941{
 942        const char *path = sha1_pack_name(sha1);
 943        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 944
 945        strcpy(p->pack_name, path);
 946        hashcpy(p->sha1, sha1);
 947        if (check_packed_git_idx(idx_path, p)) {
 948                free(p);
 949                return NULL;
 950        }
 951
 952        return p;
 953}
 954
 955void install_packed_git(struct packed_git *pack)
 956{
 957        if (pack->pack_fd != -1)
 958                pack_open_fds++;
 959
 960        pack->next = packed_git;
 961        packed_git = pack;
 962}
 963
 964static void prepare_packed_git_one(char *objdir, int local)
 965{
 966        /* Ensure that this buffer is large enough so that we can
 967           append "/pack/" without clobbering the stack even if
 968           strlen(objdir) were PATH_MAX.  */
 969        char path[PATH_MAX + 1 + 4 + 1 + 1];
 970        int len;
 971        DIR *dir;
 972        struct dirent *de;
 973
 974        sprintf(path, "%s/pack", objdir);
 975        len = strlen(path);
 976        dir = opendir(path);
 977        if (!dir) {
 978                if (errno != ENOENT)
 979                        error("unable to open object pack directory: %s: %s",
 980                              path, strerror(errno));
 981                return;
 982        }
 983        path[len++] = '/';
 984        while ((de = readdir(dir)) != NULL) {
 985                int namelen = strlen(de->d_name);
 986                struct packed_git *p;
 987
 988                if (!has_extension(de->d_name, ".idx"))
 989                        continue;
 990
 991                if (len + namelen + 1 > sizeof(path))
 992                        continue;
 993
 994                /* Don't reopen a pack we already have. */
 995                strcpy(path + len, de->d_name);
 996                for (p = packed_git; p; p = p->next) {
 997                        if (!memcmp(path, p->pack_name, len + namelen - 4))
 998                                break;
 999                }
1000                if (p)
1001                        continue;
1002                /* See if it really is a valid .idx file with corresponding
1003                 * .pack file that we can map.
1004                 */
1005                p = add_packed_git(path, len + namelen, local);
1006                if (!p)
1007                        continue;
1008                install_packed_git(p);
1009        }
1010        closedir(dir);
1011}
1012
1013static int sort_pack(const void *a_, const void *b_)
1014{
1015        struct packed_git *a = *((struct packed_git **)a_);
1016        struct packed_git *b = *((struct packed_git **)b_);
1017        int st;
1018
1019        /*
1020         * Local packs tend to contain objects specific to our
1021         * variant of the project than remote ones.  In addition,
1022         * remote ones could be on a network mounted filesystem.
1023         * Favor local ones for these reasons.
1024         */
1025        st = a->pack_local - b->pack_local;
1026        if (st)
1027                return -st;
1028
1029        /*
1030         * Younger packs tend to contain more recent objects,
1031         * and more recent objects tend to get accessed more
1032         * often.
1033         */
1034        if (a->mtime < b->mtime)
1035                return 1;
1036        else if (a->mtime == b->mtime)
1037                return 0;
1038        return -1;
1039}
1040
1041static void rearrange_packed_git(void)
1042{
1043        struct packed_git **ary, *p;
1044        int i, n;
1045
1046        for (n = 0, p = packed_git; p; p = p->next)
1047                n++;
1048        if (n < 2)
1049                return;
1050
1051        /* prepare an array of packed_git for easier sorting */
1052        ary = xcalloc(n, sizeof(struct packed_git *));
1053        for (n = 0, p = packed_git; p; p = p->next)
1054                ary[n++] = p;
1055
1056        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1057
1058        /* link them back again */
1059        for (i = 0; i < n - 1; i++)
1060                ary[i]->next = ary[i + 1];
1061        ary[n - 1]->next = NULL;
1062        packed_git = ary[0];
1063
1064        free(ary);
1065}
1066
1067static int prepare_packed_git_run_once = 0;
1068void prepare_packed_git(void)
1069{
1070        struct alternate_object_database *alt;
1071
1072        if (prepare_packed_git_run_once)
1073                return;
1074        prepare_packed_git_one(get_object_directory(), 1);
1075        prepare_alt_odb();
1076        for (alt = alt_odb_list; alt; alt = alt->next) {
1077                alt->name[-1] = 0;
1078                prepare_packed_git_one(alt->base, 0);
1079                alt->name[-1] = '/';
1080        }
1081        rearrange_packed_git();
1082        prepare_packed_git_run_once = 1;
1083}
1084
1085void reprepare_packed_git(void)
1086{
1087        discard_revindex();
1088        prepare_packed_git_run_once = 0;
1089        prepare_packed_git();
1090}
1091
1092static void mark_bad_packed_object(struct packed_git *p,
1093                                   const unsigned char *sha1)
1094{
1095        unsigned i;
1096        for (i = 0; i < p->num_bad_objects; i++)
1097                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1098                        return;
1099        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1100        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1101        p->num_bad_objects++;
1102}
1103
1104static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1105{
1106        struct packed_git *p;
1107        unsigned i;
1108
1109        for (p = packed_git; p; p = p->next)
1110                for (i = 0; i < p->num_bad_objects; i++)
1111                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1112                                return p;
1113        return NULL;
1114}
1115
1116int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1117{
1118        unsigned char real_sha1[20];
1119        hash_sha1_file(map, size, type, real_sha1);
1120        return hashcmp(sha1, real_sha1) ? -1 : 0;
1121}
1122
1123static int git_open_noatime(const char *name, struct packed_git *p)
1124{
1125        static int sha1_file_open_flag = O_NOATIME;
1126
1127        for (;;) {
1128                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1129                if (fd >= 0)
1130                        return fd;
1131
1132                /* Might the failure be due to O_NOATIME? */
1133                if (errno != ENOENT && sha1_file_open_flag) {
1134                        sha1_file_open_flag = 0;
1135                        continue;
1136                }
1137
1138                return -1;
1139        }
1140}
1141
1142static int open_sha1_file(const unsigned char *sha1)
1143{
1144        int fd;
1145        char *name = sha1_file_name(sha1);
1146        struct alternate_object_database *alt;
1147
1148        fd = git_open_noatime(name, NULL);
1149        if (fd >= 0)
1150                return fd;
1151
1152        prepare_alt_odb();
1153        errno = ENOENT;
1154        for (alt = alt_odb_list; alt; alt = alt->next) {
1155                name = alt->name;
1156                fill_sha1_path(name, sha1);
1157                fd = git_open_noatime(alt->base, NULL);
1158                if (fd >= 0)
1159                        return fd;
1160        }
1161        return -1;
1162}
1163
1164static void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1165{
1166        void *map;
1167        int fd;
1168
1169        fd = open_sha1_file(sha1);
1170        map = NULL;
1171        if (fd >= 0) {
1172                struct stat st;
1173
1174                if (!fstat(fd, &st)) {
1175                        *size = xsize_t(st.st_size);
1176                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1177                }
1178                close(fd);
1179        }
1180        return map;
1181}
1182
1183static int legacy_loose_object(unsigned char *map)
1184{
1185        unsigned int word;
1186
1187        /*
1188         * Is it a zlib-compressed buffer? If so, the first byte
1189         * must be 0x78 (15-bit window size, deflated), and the
1190         * first 16-bit word is evenly divisible by 31
1191         */
1192        word = (map[0] << 8) + map[1];
1193        if (map[0] == 0x78 && !(word % 31))
1194                return 1;
1195        else
1196                return 0;
1197}
1198
1199unsigned long unpack_object_header_buffer(const unsigned char *buf,
1200                unsigned long len, enum object_type *type, unsigned long *sizep)
1201{
1202        unsigned shift;
1203        unsigned long size, c;
1204        unsigned long used = 0;
1205
1206        c = buf[used++];
1207        *type = (c >> 4) & 7;
1208        size = c & 15;
1209        shift = 4;
1210        while (c & 0x80) {
1211                if (len <= used || bitsizeof(long) <= shift) {
1212                        error("bad object header");
1213                        return 0;
1214                }
1215                c = buf[used++];
1216                size += (c & 0x7f) << shift;
1217                shift += 7;
1218        }
1219        *sizep = size;
1220        return used;
1221}
1222
1223static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1224{
1225        unsigned long size, used;
1226        static const char valid_loose_object_type[8] = {
1227                0, /* OBJ_EXT */
1228                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1229                0, /* "delta" and others are invalid in a loose object */
1230        };
1231        enum object_type type;
1232
1233        /* Get the data stream */
1234        memset(stream, 0, sizeof(*stream));
1235        stream->next_in = map;
1236        stream->avail_in = mapsize;
1237        stream->next_out = buffer;
1238        stream->avail_out = bufsiz;
1239
1240        if (legacy_loose_object(map)) {
1241                git_inflate_init(stream);
1242                return git_inflate(stream, 0);
1243        }
1244
1245
1246        /*
1247         * There used to be a second loose object header format which
1248         * was meant to mimic the in-pack format, allowing for direct
1249         * copy of the object data.  This format turned up not to be
1250         * really worth it and we don't write it any longer.  But we
1251         * can still read it.
1252         */
1253        used = unpack_object_header_buffer(map, mapsize, &type, &size);
1254        if (!used || !valid_loose_object_type[type])
1255                return -1;
1256        map += used;
1257        mapsize -= used;
1258
1259        /* Set up the stream for the rest.. */
1260        stream->next_in = map;
1261        stream->avail_in = mapsize;
1262        git_inflate_init(stream);
1263
1264        /* And generate the fake traditional header */
1265        stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1266                                         typename(type), size);
1267        return 0;
1268}
1269
1270static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1271{
1272        int bytes = strlen(buffer) + 1;
1273        unsigned char *buf = xmallocz(size);
1274        unsigned long n;
1275        int status = Z_OK;
1276
1277        n = stream->total_out - bytes;
1278        if (n > size)
1279                n = size;
1280        memcpy(buf, (char *) buffer + bytes, n);
1281        bytes = n;
1282        if (bytes <= size) {
1283                /*
1284                 * The above condition must be (bytes <= size), not
1285                 * (bytes < size).  In other words, even though we
1286                 * expect no more output and set avail_out to zer0,
1287                 * the input zlib stream may have bytes that express
1288                 * "this concludes the stream", and we *do* want to
1289                 * eat that input.
1290                 *
1291                 * Otherwise we would not be able to test that we
1292                 * consumed all the input to reach the expected size;
1293                 * we also want to check that zlib tells us that all
1294                 * went well with status == Z_STREAM_END at the end.
1295                 */
1296                stream->next_out = buf + bytes;
1297                stream->avail_out = size - bytes;
1298                while (status == Z_OK)
1299                        status = git_inflate(stream, Z_FINISH);
1300        }
1301        if (status == Z_STREAM_END && !stream->avail_in) {
1302                git_inflate_end(stream);
1303                return buf;
1304        }
1305
1306        if (status < 0)
1307                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1308        else if (stream->avail_in)
1309                error("garbage at end of loose object '%s'",
1310                      sha1_to_hex(sha1));
1311        free(buf);
1312        return NULL;
1313}
1314
1315/*
1316 * We used to just use "sscanf()", but that's actually way
1317 * too permissive for what we want to check. So do an anal
1318 * object header parse by hand.
1319 */
1320static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1321{
1322        char type[10];
1323        int i;
1324        unsigned long size;
1325
1326        /*
1327         * The type can be at most ten bytes (including the
1328         * terminating '\0' that we add), and is followed by
1329         * a space.
1330         */
1331        i = 0;
1332        for (;;) {
1333                char c = *hdr++;
1334                if (c == ' ')
1335                        break;
1336                type[i++] = c;
1337                if (i >= sizeof(type))
1338                        return -1;
1339        }
1340        type[i] = 0;
1341
1342        /*
1343         * The length must follow immediately, and be in canonical
1344         * decimal format (ie "010" is not valid).
1345         */
1346        size = *hdr++ - '0';
1347        if (size > 9)
1348                return -1;
1349        if (size) {
1350                for (;;) {
1351                        unsigned long c = *hdr - '0';
1352                        if (c > 9)
1353                                break;
1354                        hdr++;
1355                        size = size * 10 + c;
1356                }
1357        }
1358        *sizep = size;
1359
1360        /*
1361         * The length must be followed by a zero byte
1362         */
1363        return *hdr ? -1 : type_from_string(type);
1364}
1365
1366static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1367{
1368        int ret;
1369        z_stream stream;
1370        char hdr[8192];
1371
1372        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1373        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1374                return NULL;
1375
1376        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1377}
1378
1379unsigned long get_size_from_delta(struct packed_git *p,
1380                                  struct pack_window **w_curs,
1381                                  off_t curpos)
1382{
1383        const unsigned char *data;
1384        unsigned char delta_head[20], *in;
1385        z_stream stream;
1386        int st;
1387
1388        memset(&stream, 0, sizeof(stream));
1389        stream.next_out = delta_head;
1390        stream.avail_out = sizeof(delta_head);
1391
1392        git_inflate_init(&stream);
1393        do {
1394                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1395                stream.next_in = in;
1396                st = git_inflate(&stream, Z_FINISH);
1397                curpos += stream.next_in - in;
1398        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1399                 stream.total_out < sizeof(delta_head));
1400        git_inflate_end(&stream);
1401        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1402                error("delta data unpack-initial failed");
1403                return 0;
1404        }
1405
1406        /* Examine the initial part of the delta to figure out
1407         * the result size.
1408         */
1409        data = delta_head;
1410
1411        /* ignore base size */
1412        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1413
1414        /* Read the result size */
1415        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1416}
1417
1418static off_t get_delta_base(struct packed_git *p,
1419                                    struct pack_window **w_curs,
1420                                    off_t *curpos,
1421                                    enum object_type type,
1422                                    off_t delta_obj_offset)
1423{
1424        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1425        off_t base_offset;
1426
1427        /* use_pack() assured us we have [base_info, base_info + 20)
1428         * as a range that we can look at without walking off the
1429         * end of the mapped window.  Its actually the hash size
1430         * that is assured.  An OFS_DELTA longer than the hash size
1431         * is stupid, as then a REF_DELTA would be smaller to store.
1432         */
1433        if (type == OBJ_OFS_DELTA) {
1434                unsigned used = 0;
1435                unsigned char c = base_info[used++];
1436                base_offset = c & 127;
1437                while (c & 128) {
1438                        base_offset += 1;
1439                        if (!base_offset || MSB(base_offset, 7))
1440                                return 0;  /* overflow */
1441                        c = base_info[used++];
1442                        base_offset = (base_offset << 7) + (c & 127);
1443                }
1444                base_offset = delta_obj_offset - base_offset;
1445                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1446                        return 0;  /* out of bound */
1447                *curpos += used;
1448        } else if (type == OBJ_REF_DELTA) {
1449                /* The base entry _must_ be in the same pack */
1450                base_offset = find_pack_entry_one(base_info, p);
1451                *curpos += 20;
1452        } else
1453                die("I am totally screwed");
1454        return base_offset;
1455}
1456
1457/* forward declaration for a mutually recursive function */
1458static int packed_object_info(struct packed_git *p, off_t offset,
1459                              unsigned long *sizep);
1460
1461static int packed_delta_info(struct packed_git *p,
1462                             struct pack_window **w_curs,
1463                             off_t curpos,
1464                             enum object_type type,
1465                             off_t obj_offset,
1466                             unsigned long *sizep)
1467{
1468        off_t base_offset;
1469
1470        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1471        if (!base_offset)
1472                return OBJ_BAD;
1473        type = packed_object_info(p, base_offset, NULL);
1474        if (type <= OBJ_NONE) {
1475                struct revindex_entry *revidx;
1476                const unsigned char *base_sha1;
1477                revidx = find_pack_revindex(p, base_offset);
1478                if (!revidx)
1479                        return OBJ_BAD;
1480                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1481                mark_bad_packed_object(p, base_sha1);
1482                type = sha1_object_info(base_sha1, NULL);
1483                if (type <= OBJ_NONE)
1484                        return OBJ_BAD;
1485        }
1486
1487        /* We choose to only get the type of the base object and
1488         * ignore potentially corrupt pack file that expects the delta
1489         * based on a base with a wrong size.  This saves tons of
1490         * inflate() calls.
1491         */
1492        if (sizep) {
1493                *sizep = get_size_from_delta(p, w_curs, curpos);
1494                if (*sizep == 0)
1495                        type = OBJ_BAD;
1496        }
1497
1498        return type;
1499}
1500
1501static int unpack_object_header(struct packed_git *p,
1502                                struct pack_window **w_curs,
1503                                off_t *curpos,
1504                                unsigned long *sizep)
1505{
1506        unsigned char *base;
1507        unsigned int left;
1508        unsigned long used;
1509        enum object_type type;
1510
1511        /* use_pack() assures us we have [base, base + 20) available
1512         * as a range that we can look at at.  (Its actually the hash
1513         * size that is assured.)  With our object header encoding
1514         * the maximum deflated object size is 2^137, which is just
1515         * insane, so we know won't exceed what we have been given.
1516         */
1517        base = use_pack(p, w_curs, *curpos, &left);
1518        used = unpack_object_header_buffer(base, left, &type, sizep);
1519        if (!used) {
1520                type = OBJ_BAD;
1521        } else
1522                *curpos += used;
1523
1524        return type;
1525}
1526
1527const char *packed_object_info_detail(struct packed_git *p,
1528                                      off_t obj_offset,
1529                                      unsigned long *size,
1530                                      unsigned long *store_size,
1531                                      unsigned int *delta_chain_length,
1532                                      unsigned char *base_sha1)
1533{
1534        struct pack_window *w_curs = NULL;
1535        off_t curpos;
1536        unsigned long dummy;
1537        unsigned char *next_sha1;
1538        enum object_type type;
1539        struct revindex_entry *revidx;
1540
1541        *delta_chain_length = 0;
1542        curpos = obj_offset;
1543        type = unpack_object_header(p, &w_curs, &curpos, size);
1544
1545        revidx = find_pack_revindex(p, obj_offset);
1546        *store_size = revidx[1].offset - obj_offset;
1547
1548        for (;;) {
1549                switch (type) {
1550                default:
1551                        die("pack %s contains unknown object type %d",
1552                            p->pack_name, type);
1553                case OBJ_COMMIT:
1554                case OBJ_TREE:
1555                case OBJ_BLOB:
1556                case OBJ_TAG:
1557                        unuse_pack(&w_curs);
1558                        return typename(type);
1559                case OBJ_OFS_DELTA:
1560                        obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1561                        if (!obj_offset)
1562                                die("pack %s contains bad delta base reference of type %s",
1563                                    p->pack_name, typename(type));
1564                        if (*delta_chain_length == 0) {
1565                                revidx = find_pack_revindex(p, obj_offset);
1566                                hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
1567                        }
1568                        break;
1569                case OBJ_REF_DELTA:
1570                        next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1571                        if (*delta_chain_length == 0)
1572                                hashcpy(base_sha1, next_sha1);
1573                        obj_offset = find_pack_entry_one(next_sha1, p);
1574                        break;
1575                }
1576                (*delta_chain_length)++;
1577                curpos = obj_offset;
1578                type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1579        }
1580}
1581
1582static int packed_object_info(struct packed_git *p, off_t obj_offset,
1583                              unsigned long *sizep)
1584{
1585        struct pack_window *w_curs = NULL;
1586        unsigned long size;
1587        off_t curpos = obj_offset;
1588        enum object_type type;
1589
1590        type = unpack_object_header(p, &w_curs, &curpos, &size);
1591
1592        switch (type) {
1593        case OBJ_OFS_DELTA:
1594        case OBJ_REF_DELTA:
1595                type = packed_delta_info(p, &w_curs, curpos,
1596                                         type, obj_offset, sizep);
1597                break;
1598        case OBJ_COMMIT:
1599        case OBJ_TREE:
1600        case OBJ_BLOB:
1601        case OBJ_TAG:
1602                if (sizep)
1603                        *sizep = size;
1604                break;
1605        default:
1606                error("unknown object type %i at offset %"PRIuMAX" in %s",
1607                      type, (uintmax_t)obj_offset, p->pack_name);
1608                type = OBJ_BAD;
1609        }
1610        unuse_pack(&w_curs);
1611        return type;
1612}
1613
1614static void *unpack_compressed_entry(struct packed_git *p,
1615                                    struct pack_window **w_curs,
1616                                    off_t curpos,
1617                                    unsigned long size)
1618{
1619        int st;
1620        z_stream stream;
1621        unsigned char *buffer, *in;
1622
1623        buffer = xmallocz(size);
1624        memset(&stream, 0, sizeof(stream));
1625        stream.next_out = buffer;
1626        stream.avail_out = size + 1;
1627
1628        git_inflate_init(&stream);
1629        do {
1630                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1631                stream.next_in = in;
1632                st = git_inflate(&stream, Z_FINISH);
1633                if (!stream.avail_out)
1634                        break; /* the payload is larger than it should be */
1635                curpos += stream.next_in - in;
1636        } while (st == Z_OK || st == Z_BUF_ERROR);
1637        git_inflate_end(&stream);
1638        if ((st != Z_STREAM_END) || stream.total_out != size) {
1639                free(buffer);
1640                return NULL;
1641        }
1642
1643        return buffer;
1644}
1645
1646#define MAX_DELTA_CACHE (256)
1647
1648static size_t delta_base_cached;
1649
1650static struct delta_base_cache_lru_list {
1651        struct delta_base_cache_lru_list *prev;
1652        struct delta_base_cache_lru_list *next;
1653} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1654
1655static struct delta_base_cache_entry {
1656        struct delta_base_cache_lru_list lru;
1657        void *data;
1658        struct packed_git *p;
1659        off_t base_offset;
1660        unsigned long size;
1661        enum object_type type;
1662} delta_base_cache[MAX_DELTA_CACHE];
1663
1664static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1665{
1666        unsigned long hash;
1667
1668        hash = (unsigned long)p + (unsigned long)base_offset;
1669        hash += (hash >> 8) + (hash >> 16);
1670        return hash % MAX_DELTA_CACHE;
1671}
1672
1673static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1674        unsigned long *base_size, enum object_type *type, int keep_cache)
1675{
1676        void *ret;
1677        unsigned long hash = pack_entry_hash(p, base_offset);
1678        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1679
1680        ret = ent->data;
1681        if (!ret || ent->p != p || ent->base_offset != base_offset)
1682                return unpack_entry(p, base_offset, type, base_size);
1683
1684        if (!keep_cache) {
1685                ent->data = NULL;
1686                ent->lru.next->prev = ent->lru.prev;
1687                ent->lru.prev->next = ent->lru.next;
1688                delta_base_cached -= ent->size;
1689        } else {
1690                ret = xmemdupz(ent->data, ent->size);
1691        }
1692        *type = ent->type;
1693        *base_size = ent->size;
1694        return ret;
1695}
1696
1697static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1698{
1699        if (ent->data) {
1700                free(ent->data);
1701                ent->data = NULL;
1702                ent->lru.next->prev = ent->lru.prev;
1703                ent->lru.prev->next = ent->lru.next;
1704                delta_base_cached -= ent->size;
1705        }
1706}
1707
1708void clear_delta_base_cache(void)
1709{
1710        unsigned long p;
1711        for (p = 0; p < MAX_DELTA_CACHE; p++)
1712                release_delta_base_cache(&delta_base_cache[p]);
1713}
1714
1715static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1716        void *base, unsigned long base_size, enum object_type type)
1717{
1718        unsigned long hash = pack_entry_hash(p, base_offset);
1719        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1720        struct delta_base_cache_lru_list *lru;
1721
1722        release_delta_base_cache(ent);
1723        delta_base_cached += base_size;
1724
1725        for (lru = delta_base_cache_lru.next;
1726             delta_base_cached > delta_base_cache_limit
1727             && lru != &delta_base_cache_lru;
1728             lru = lru->next) {
1729                struct delta_base_cache_entry *f = (void *)lru;
1730                if (f->type == OBJ_BLOB)
1731                        release_delta_base_cache(f);
1732        }
1733        for (lru = delta_base_cache_lru.next;
1734             delta_base_cached > delta_base_cache_limit
1735             && lru != &delta_base_cache_lru;
1736             lru = lru->next) {
1737                struct delta_base_cache_entry *f = (void *)lru;
1738                release_delta_base_cache(f);
1739        }
1740
1741        ent->p = p;
1742        ent->base_offset = base_offset;
1743        ent->type = type;
1744        ent->data = base;
1745        ent->size = base_size;
1746        ent->lru.next = &delta_base_cache_lru;
1747        ent->lru.prev = delta_base_cache_lru.prev;
1748        delta_base_cache_lru.prev->next = &ent->lru;
1749        delta_base_cache_lru.prev = &ent->lru;
1750}
1751
1752static void *read_object(const unsigned char *sha1, enum object_type *type,
1753                         unsigned long *size);
1754
1755static void *unpack_delta_entry(struct packed_git *p,
1756                                struct pack_window **w_curs,
1757                                off_t curpos,
1758                                unsigned long delta_size,
1759                                off_t obj_offset,
1760                                enum object_type *type,
1761                                unsigned long *sizep)
1762{
1763        void *delta_data, *result, *base;
1764        unsigned long base_size;
1765        off_t base_offset;
1766
1767        base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1768        if (!base_offset) {
1769                error("failed to validate delta base reference "
1770                      "at offset %"PRIuMAX" from %s",
1771                      (uintmax_t)curpos, p->pack_name);
1772                return NULL;
1773        }
1774        unuse_pack(w_curs);
1775        base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1776        if (!base) {
1777                /*
1778                 * We're probably in deep shit, but let's try to fetch
1779                 * the required base anyway from another pack or loose.
1780                 * This is costly but should happen only in the presence
1781                 * of a corrupted pack, and is better than failing outright.
1782                 */
1783                struct revindex_entry *revidx;
1784                const unsigned char *base_sha1;
1785                revidx = find_pack_revindex(p, base_offset);
1786                if (!revidx)
1787                        return NULL;
1788                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1789                error("failed to read delta base object %s"
1790                      " at offset %"PRIuMAX" from %s",
1791                      sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1792                      p->pack_name);
1793                mark_bad_packed_object(p, base_sha1);
1794                base = read_object(base_sha1, type, &base_size);
1795                if (!base)
1796                        return NULL;
1797        }
1798
1799        delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1800        if (!delta_data) {
1801                error("failed to unpack compressed delta "
1802                      "at offset %"PRIuMAX" from %s",
1803                      (uintmax_t)curpos, p->pack_name);
1804                free(base);
1805                return NULL;
1806        }
1807        result = patch_delta(base, base_size,
1808                             delta_data, delta_size,
1809                             sizep);
1810        if (!result)
1811                die("failed to apply delta");
1812        free(delta_data);
1813        add_delta_base_cache(p, base_offset, base, base_size, *type);
1814        return result;
1815}
1816
1817int do_check_packed_object_crc;
1818
1819void *unpack_entry(struct packed_git *p, off_t obj_offset,
1820                   enum object_type *type, unsigned long *sizep)
1821{
1822        struct pack_window *w_curs = NULL;
1823        off_t curpos = obj_offset;
1824        void *data;
1825
1826        if (do_check_packed_object_crc && p->index_version > 1) {
1827                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1828                unsigned long len = revidx[1].offset - obj_offset;
1829                if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1830                        const unsigned char *sha1 =
1831                                nth_packed_object_sha1(p, revidx->nr);
1832                        error("bad packed object CRC for %s",
1833                              sha1_to_hex(sha1));
1834                        mark_bad_packed_object(p, sha1);
1835                        unuse_pack(&w_curs);
1836                        return NULL;
1837                }
1838        }
1839
1840        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1841        switch (*type) {
1842        case OBJ_OFS_DELTA:
1843        case OBJ_REF_DELTA:
1844                data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1845                                          obj_offset, type, sizep);
1846                break;
1847        case OBJ_COMMIT:
1848        case OBJ_TREE:
1849        case OBJ_BLOB:
1850        case OBJ_TAG:
1851                data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1852                break;
1853        default:
1854                data = NULL;
1855                error("unknown object type %i at offset %"PRIuMAX" in %s",
1856                      *type, (uintmax_t)obj_offset, p->pack_name);
1857        }
1858        unuse_pack(&w_curs);
1859        return data;
1860}
1861
1862const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1863                                            uint32_t n)
1864{
1865        const unsigned char *index = p->index_data;
1866        if (!index) {
1867                if (open_pack_index(p))
1868                        return NULL;
1869                index = p->index_data;
1870        }
1871        if (n >= p->num_objects)
1872                return NULL;
1873        index += 4 * 256;
1874        if (p->index_version == 1) {
1875                return index + 24 * n + 4;
1876        } else {
1877                index += 8;
1878                return index + 20 * n;
1879        }
1880}
1881
1882off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1883{
1884        const unsigned char *index = p->index_data;
1885        index += 4 * 256;
1886        if (p->index_version == 1) {
1887                return ntohl(*((uint32_t *)(index + 24 * n)));
1888        } else {
1889                uint32_t off;
1890                index += 8 + p->num_objects * (20 + 4);
1891                off = ntohl(*((uint32_t *)(index + 4 * n)));
1892                if (!(off & 0x80000000))
1893                        return off;
1894                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1895                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1896                                   ntohl(*((uint32_t *)(index + 4)));
1897        }
1898}
1899
1900off_t find_pack_entry_one(const unsigned char *sha1,
1901                                  struct packed_git *p)
1902{
1903        const uint32_t *level1_ofs = p->index_data;
1904        const unsigned char *index = p->index_data;
1905        unsigned hi, lo, stride;
1906        static int use_lookup = -1;
1907        static int debug_lookup = -1;
1908
1909        if (debug_lookup < 0)
1910                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1911
1912        if (!index) {
1913                if (open_pack_index(p))
1914                        return 0;
1915                level1_ofs = p->index_data;
1916                index = p->index_data;
1917        }
1918        if (p->index_version > 1) {
1919                level1_ofs += 2;
1920                index += 8;
1921        }
1922        index += 4 * 256;
1923        hi = ntohl(level1_ofs[*sha1]);
1924        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1925        if (p->index_version > 1) {
1926                stride = 20;
1927        } else {
1928                stride = 24;
1929                index += 4;
1930        }
1931
1932        if (debug_lookup)
1933                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1934                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1935
1936        if (use_lookup < 0)
1937                use_lookup = !!getenv("GIT_USE_LOOKUP");
1938        if (use_lookup) {
1939                int pos = sha1_entry_pos(index, stride, 0,
1940                                         lo, hi, p->num_objects, sha1);
1941                if (pos < 0)
1942                        return 0;
1943                return nth_packed_object_offset(p, pos);
1944        }
1945
1946        do {
1947                unsigned mi = (lo + hi) / 2;
1948                int cmp = hashcmp(index + mi * stride, sha1);
1949
1950                if (debug_lookup)
1951                        printf("lo %u hi %u rg %u mi %u\n",
1952                               lo, hi, hi - lo, mi);
1953                if (!cmp)
1954                        return nth_packed_object_offset(p, mi);
1955                if (cmp > 0)
1956                        hi = mi;
1957                else
1958                        lo = mi+1;
1959        } while (lo < hi);
1960        return 0;
1961}
1962
1963static int is_pack_valid(struct packed_git *p)
1964{
1965        /* An already open pack is known to be valid. */
1966        if (p->pack_fd != -1)
1967                return 1;
1968
1969        /* If the pack has one window completely covering the
1970         * file size, the pack is known to be valid even if
1971         * the descriptor is not currently open.
1972         */
1973        if (p->windows) {
1974                struct pack_window *w = p->windows;
1975
1976                if (!w->offset && w->len == p->pack_size)
1977                        return 1;
1978        }
1979
1980        /* Force the pack to open to prove its valid. */
1981        return !open_packed_git(p);
1982}
1983
1984static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
1985{
1986        static struct packed_git *last_found = (void *)1;
1987        struct packed_git *p;
1988        off_t offset;
1989
1990        prepare_packed_git();
1991        if (!packed_git)
1992                return 0;
1993        p = (last_found == (void *)1) ? packed_git : last_found;
1994
1995        do {
1996                if (p->num_bad_objects) {
1997                        unsigned i;
1998                        for (i = 0; i < p->num_bad_objects; i++)
1999                                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2000                                        goto next;
2001                }
2002
2003                offset = find_pack_entry_one(sha1, p);
2004                if (offset) {
2005                        /*
2006                         * We are about to tell the caller where they can
2007                         * locate the requested object.  We better make
2008                         * sure the packfile is still here and can be
2009                         * accessed before supplying that answer, as
2010                         * it may have been deleted since the index
2011                         * was loaded!
2012                         */
2013                        if (!is_pack_valid(p)) {
2014                                error("packfile %s cannot be accessed", p->pack_name);
2015                                goto next;
2016                        }
2017                        e->offset = offset;
2018                        e->p = p;
2019                        hashcpy(e->sha1, sha1);
2020                        last_found = p;
2021                        return 1;
2022                }
2023
2024                next:
2025                if (p == last_found)
2026                        p = packed_git;
2027                else
2028                        p = p->next;
2029                if (p == last_found)
2030                        p = p->next;
2031        } while (p);
2032        return 0;
2033}
2034
2035struct packed_git *find_sha1_pack(const unsigned char *sha1,
2036                                  struct packed_git *packs)
2037{
2038        struct packed_git *p;
2039
2040        for (p = packs; p; p = p->next) {
2041                if (find_pack_entry_one(sha1, p))
2042                        return p;
2043        }
2044        return NULL;
2045
2046}
2047
2048static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
2049{
2050        int status;
2051        unsigned long mapsize, size;
2052        void *map;
2053        z_stream stream;
2054        char hdr[32];
2055
2056        map = map_sha1_file(sha1, &mapsize);
2057        if (!map)
2058                return error("unable to find %s", sha1_to_hex(sha1));
2059        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2060                status = error("unable to unpack %s header",
2061                               sha1_to_hex(sha1));
2062        else if ((status = parse_sha1_header(hdr, &size)) < 0)
2063                status = error("unable to parse %s header", sha1_to_hex(sha1));
2064        else if (sizep)
2065                *sizep = size;
2066        git_inflate_end(&stream);
2067        munmap(map, mapsize);
2068        return status;
2069}
2070
2071int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2072{
2073        struct cached_object *co;
2074        struct pack_entry e;
2075        int status;
2076
2077        co = find_cached_object(sha1);
2078        if (co) {
2079                if (sizep)
2080                        *sizep = co->size;
2081                return co->type;
2082        }
2083
2084        if (!find_pack_entry(sha1, &e)) {
2085                /* Most likely it's a loose object. */
2086                status = sha1_loose_object_info(sha1, sizep);
2087                if (status >= 0)
2088                        return status;
2089
2090                /* Not a loose object; someone else may have just packed it. */
2091                reprepare_packed_git();
2092                if (!find_pack_entry(sha1, &e))
2093                        return status;
2094        }
2095
2096        status = packed_object_info(e.p, e.offset, sizep);
2097        if (status < 0) {
2098                mark_bad_packed_object(e.p, sha1);
2099                status = sha1_object_info(sha1, sizep);
2100        }
2101
2102        return status;
2103}
2104
2105static void *read_packed_sha1(const unsigned char *sha1,
2106                              enum object_type *type, unsigned long *size)
2107{
2108        struct pack_entry e;
2109        void *data;
2110
2111        if (!find_pack_entry(sha1, &e))
2112                return NULL;
2113        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2114        if (!data) {
2115                /*
2116                 * We're probably in deep shit, but let's try to fetch
2117                 * the required object anyway from another pack or loose.
2118                 * This should happen only in the presence of a corrupted
2119                 * pack, and is better than failing outright.
2120                 */
2121                error("failed to read object %s at offset %"PRIuMAX" from %s",
2122                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2123                mark_bad_packed_object(e.p, sha1);
2124                data = read_object(sha1, type, size);
2125        }
2126        return data;
2127}
2128
2129int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2130                      unsigned char *sha1)
2131{
2132        struct cached_object *co;
2133
2134        hash_sha1_file(buf, len, typename(type), sha1);
2135        if (has_sha1_file(sha1) || find_cached_object(sha1))
2136                return 0;
2137        if (cached_object_alloc <= cached_object_nr) {
2138                cached_object_alloc = alloc_nr(cached_object_alloc);
2139                cached_objects = xrealloc(cached_objects,
2140                                          sizeof(*cached_objects) *
2141                                          cached_object_alloc);
2142        }
2143        co = &cached_objects[cached_object_nr++];
2144        co->size = len;
2145        co->type = type;
2146        co->buf = xmalloc(len);
2147        memcpy(co->buf, buf, len);
2148        hashcpy(co->sha1, sha1);
2149        return 0;
2150}
2151
2152static void *read_object(const unsigned char *sha1, enum object_type *type,
2153                         unsigned long *size)
2154{
2155        unsigned long mapsize;
2156        void *map, *buf;
2157        struct cached_object *co;
2158
2159        co = find_cached_object(sha1);
2160        if (co) {
2161                *type = co->type;
2162                *size = co->size;
2163                return xmemdupz(co->buf, co->size);
2164        }
2165
2166        buf = read_packed_sha1(sha1, type, size);
2167        if (buf)
2168                return buf;
2169        map = map_sha1_file(sha1, &mapsize);
2170        if (map) {
2171                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2172                munmap(map, mapsize);
2173                return buf;
2174        }
2175        reprepare_packed_git();
2176        return read_packed_sha1(sha1, type, size);
2177}
2178
2179/*
2180 * This function dies on corrupt objects; the callers who want to
2181 * deal with them should arrange to call read_object() and give error
2182 * messages themselves.
2183 */
2184void *read_sha1_file_repl(const unsigned char *sha1,
2185                          enum object_type *type,
2186                          unsigned long *size,
2187                          const unsigned char **replacement)
2188{
2189        const unsigned char *repl = lookup_replace_object(sha1);
2190        void *data;
2191        char *path;
2192        const struct packed_git *p;
2193
2194        errno = 0;
2195        data = read_object(repl, type, size);
2196        if (data) {
2197                if (replacement)
2198                        *replacement = repl;
2199                return data;
2200        }
2201
2202        if (errno && errno != ENOENT)
2203                die_errno("failed to read object %s", sha1_to_hex(sha1));
2204
2205        /* die if we replaced an object with one that does not exist */
2206        if (repl != sha1)
2207                die("replacement %s not found for %s",
2208                    sha1_to_hex(repl), sha1_to_hex(sha1));
2209
2210        if (has_loose_object(repl)) {
2211                path = sha1_file_name(sha1);
2212                die("loose object %s (stored in %s) is corrupt",
2213                    sha1_to_hex(repl), path);
2214        }
2215
2216        if ((p = has_packed_and_bad(repl)) != NULL)
2217                die("packed object %s (stored in %s) is corrupt",
2218                    sha1_to_hex(repl), p->pack_name);
2219
2220        return NULL;
2221}
2222
2223void *read_object_with_reference(const unsigned char *sha1,
2224                                 const char *required_type_name,
2225                                 unsigned long *size,
2226                                 unsigned char *actual_sha1_return)
2227{
2228        enum object_type type, required_type;
2229        void *buffer;
2230        unsigned long isize;
2231        unsigned char actual_sha1[20];
2232
2233        required_type = type_from_string(required_type_name);
2234        hashcpy(actual_sha1, sha1);
2235        while (1) {
2236                int ref_length = -1;
2237                const char *ref_type = NULL;
2238
2239                buffer = read_sha1_file(actual_sha1, &type, &isize);
2240                if (!buffer)
2241                        return NULL;
2242                if (type == required_type) {
2243                        *size = isize;
2244                        if (actual_sha1_return)
2245                                hashcpy(actual_sha1_return, actual_sha1);
2246                        return buffer;
2247                }
2248                /* Handle references */
2249                else if (type == OBJ_COMMIT)
2250                        ref_type = "tree ";
2251                else if (type == OBJ_TAG)
2252                        ref_type = "object ";
2253                else {
2254                        free(buffer);
2255                        return NULL;
2256                }
2257                ref_length = strlen(ref_type);
2258
2259                if (ref_length + 40 > isize ||
2260                    memcmp(buffer, ref_type, ref_length) ||
2261                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2262                        free(buffer);
2263                        return NULL;
2264                }
2265                free(buffer);
2266                /* Now we have the ID of the referred-to object in
2267                 * actual_sha1.  Check again. */
2268        }
2269}
2270
2271static void write_sha1_file_prepare(const void *buf, unsigned long len,
2272                                    const char *type, unsigned char *sha1,
2273                                    char *hdr, int *hdrlen)
2274{
2275        git_SHA_CTX c;
2276
2277        /* Generate the header */
2278        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2279
2280        /* Sha1.. */
2281        git_SHA1_Init(&c);
2282        git_SHA1_Update(&c, hdr, *hdrlen);
2283        git_SHA1_Update(&c, buf, len);
2284        git_SHA1_Final(sha1, &c);
2285}
2286
2287/*
2288 * Move the just written object into its final resting place.
2289 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2290 * "moving" is only a part of what it does, when no patch between
2291 * master to pu changes the call sites of this function.
2292 */
2293int move_temp_to_file(const char *tmpfile, const char *filename)
2294{
2295        int ret = 0;
2296
2297        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2298                goto try_rename;
2299        else if (link(tmpfile, filename))
2300                ret = errno;
2301
2302        /*
2303         * Coda hack - coda doesn't like cross-directory links,
2304         * so we fall back to a rename, which will mean that it
2305         * won't be able to check collisions, but that's not a
2306         * big deal.
2307         *
2308         * The same holds for FAT formatted media.
2309         *
2310         * When this succeeds, we just return.  We have nothing
2311         * left to unlink.
2312         */
2313        if (ret && ret != EEXIST) {
2314        try_rename:
2315                if (!rename(tmpfile, filename))
2316                        goto out;
2317                ret = errno;
2318        }
2319        unlink_or_warn(tmpfile);
2320        if (ret) {
2321                if (ret != EEXIST) {
2322                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2323                }
2324                /* FIXME!!! Collision check here ? */
2325        }
2326
2327out:
2328        if (adjust_shared_perm(filename))
2329                return error("unable to set permission to '%s'", filename);
2330        return 0;
2331}
2332
2333static int write_buffer(int fd, const void *buf, size_t len)
2334{
2335        if (write_in_full(fd, buf, len) < 0)
2336                return error("file write error (%s)", strerror(errno));
2337        return 0;
2338}
2339
2340int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2341                   unsigned char *sha1)
2342{
2343        char hdr[32];
2344        int hdrlen;
2345        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2346        return 0;
2347}
2348
2349/* Finalize a file on disk, and close it. */
2350static void close_sha1_file(int fd)
2351{
2352        if (fsync_object_files)
2353                fsync_or_die(fd, "sha1 file");
2354        if (close(fd) != 0)
2355                die_errno("error when closing sha1 file");
2356}
2357
2358/* Size of directory component, including the ending '/' */
2359static inline int directory_size(const char *filename)
2360{
2361        const char *s = strrchr(filename, '/');
2362        if (!s)
2363                return 0;
2364        return s - filename + 1;
2365}
2366
2367/*
2368 * This creates a temporary file in the same directory as the final
2369 * 'filename'
2370 *
2371 * We want to avoid cross-directory filename renames, because those
2372 * can have problems on various filesystems (FAT, NFS, Coda).
2373 */
2374static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2375{
2376        int fd, dirlen = directory_size(filename);
2377
2378        if (dirlen + 20 > bufsiz) {
2379                errno = ENAMETOOLONG;
2380                return -1;
2381        }
2382        memcpy(buffer, filename, dirlen);
2383        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2384        fd = git_mkstemp_mode(buffer, 0444);
2385        if (fd < 0 && dirlen && errno == ENOENT) {
2386                /* Make sure the directory exists */
2387                memcpy(buffer, filename, dirlen);
2388                buffer[dirlen-1] = 0;
2389                if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2390                        return -1;
2391
2392                /* Try again */
2393                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2394                fd = git_mkstemp_mode(buffer, 0444);
2395        }
2396        return fd;
2397}
2398
2399static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2400                              const void *buf, unsigned long len, time_t mtime)
2401{
2402        int fd, ret;
2403        unsigned char compressed[4096];
2404        z_stream stream;
2405        git_SHA_CTX c;
2406        unsigned char parano_sha1[20];
2407        char *filename;
2408        static char tmpfile[PATH_MAX];
2409
2410        filename = sha1_file_name(sha1);
2411        fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
2412        if (fd < 0) {
2413                if (errno == EACCES)
2414                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2415                else
2416                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
2417        }
2418
2419        /* Set it up */
2420        memset(&stream, 0, sizeof(stream));
2421        deflateInit(&stream, zlib_compression_level);
2422        stream.next_out = compressed;
2423        stream.avail_out = sizeof(compressed);
2424        git_SHA1_Init(&c);
2425
2426        /* First header.. */
2427        stream.next_in = (unsigned char *)hdr;
2428        stream.avail_in = hdrlen;
2429        while (deflate(&stream, 0) == Z_OK)
2430                /* nothing */;
2431        git_SHA1_Update(&c, hdr, hdrlen);
2432
2433        /* Then the data itself.. */
2434        stream.next_in = (void *)buf;
2435        stream.avail_in = len;
2436        do {
2437                unsigned char *in0 = stream.next_in;
2438                ret = deflate(&stream, Z_FINISH);
2439                git_SHA1_Update(&c, in0, stream.next_in - in0);
2440                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2441                        die("unable to write sha1 file");
2442                stream.next_out = compressed;
2443                stream.avail_out = sizeof(compressed);
2444        } while (ret == Z_OK);
2445
2446        if (ret != Z_STREAM_END)
2447                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2448        ret = deflateEnd(&stream);
2449        if (ret != Z_OK)
2450                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2451        git_SHA1_Final(parano_sha1, &c);
2452        if (hashcmp(sha1, parano_sha1) != 0)
2453                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2454
2455        close_sha1_file(fd);
2456
2457        if (mtime) {
2458                struct utimbuf utb;
2459                utb.actime = mtime;
2460                utb.modtime = mtime;
2461                if (utime(tmpfile, &utb) < 0)
2462                        warning("failed utime() on %s: %s",
2463                                tmpfile, strerror(errno));
2464        }
2465
2466        return move_temp_to_file(tmpfile, filename);
2467}
2468
2469int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2470{
2471        unsigned char sha1[20];
2472        char hdr[32];
2473        int hdrlen;
2474
2475        /* Normally if we have it in the pack then we do not bother writing
2476         * it out into .git/objects/??/?{38} file.
2477         */
2478        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2479        if (returnsha1)
2480                hashcpy(returnsha1, sha1);
2481        if (has_sha1_file(sha1))
2482                return 0;
2483        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2484}
2485
2486int force_object_loose(const unsigned char *sha1, time_t mtime)
2487{
2488        void *buf;
2489        unsigned long len;
2490        enum object_type type;
2491        char hdr[32];
2492        int hdrlen;
2493        int ret;
2494
2495        if (has_loose_object(sha1))
2496                return 0;
2497        buf = read_packed_sha1(sha1, &type, &len);
2498        if (!buf)
2499                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2500        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2501        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2502        free(buf);
2503
2504        return ret;
2505}
2506
2507int has_pack_index(const unsigned char *sha1)
2508{
2509        struct stat st;
2510        if (stat(sha1_pack_index_name(sha1), &st))
2511                return 0;
2512        return 1;
2513}
2514
2515int has_sha1_pack(const unsigned char *sha1)
2516{
2517        struct pack_entry e;
2518        return find_pack_entry(sha1, &e);
2519}
2520
2521int has_sha1_file(const unsigned char *sha1)
2522{
2523        struct pack_entry e;
2524
2525        if (find_pack_entry(sha1, &e))
2526                return 1;
2527        return has_loose_object(sha1);
2528}
2529
2530static int index_mem(unsigned char *sha1, void *buf, size_t size,
2531                     int write_object, enum object_type type, const char *path)
2532{
2533        int ret, re_allocated = 0;
2534
2535        if (!type)
2536                type = OBJ_BLOB;
2537
2538        /*
2539         * Convert blobs to git internal format
2540         */
2541        if ((type == OBJ_BLOB) && path) {
2542                struct strbuf nbuf = STRBUF_INIT;
2543                if (convert_to_git(path, buf, size, &nbuf,
2544                                   write_object ? safe_crlf : 0)) {
2545                        buf = strbuf_detach(&nbuf, &size);
2546                        re_allocated = 1;
2547                }
2548        }
2549
2550        if (write_object)
2551                ret = write_sha1_file(buf, size, typename(type), sha1);
2552        else
2553                ret = hash_sha1_file(buf, size, typename(type), sha1);
2554        if (re_allocated)
2555                free(buf);
2556        return ret;
2557}
2558
2559#define SMALL_FILE_SIZE (32*1024)
2560
2561int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2562             enum object_type type, const char *path)
2563{
2564        int ret;
2565        size_t size = xsize_t(st->st_size);
2566
2567        if (!S_ISREG(st->st_mode)) {
2568                struct strbuf sbuf = STRBUF_INIT;
2569                if (strbuf_read(&sbuf, fd, 4096) >= 0)
2570                        ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
2571                                        type, path);
2572                else
2573                        ret = -1;
2574                strbuf_release(&sbuf);
2575        } else if (!size) {
2576                ret = index_mem(sha1, NULL, size, write_object, type, path);
2577        } else if (size <= SMALL_FILE_SIZE) {
2578                char *buf = xmalloc(size);
2579                if (size == read_in_full(fd, buf, size))
2580                        ret = index_mem(sha1, buf, size, write_object, type,
2581                                        path);
2582                else
2583                        ret = error("short read %s", strerror(errno));
2584                free(buf);
2585        } else {
2586                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2587                ret = index_mem(sha1, buf, size, write_object, type, path);
2588                munmap(buf, size);
2589        }
2590        close(fd);
2591        return ret;
2592}
2593
2594int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2595{
2596        int fd;
2597        struct strbuf sb = STRBUF_INIT;
2598
2599        switch (st->st_mode & S_IFMT) {
2600        case S_IFREG:
2601                fd = open(path, O_RDONLY);
2602                if (fd < 0)
2603                        return error("open(\"%s\"): %s", path,
2604                                     strerror(errno));
2605                if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
2606                        return error("%s: failed to insert into database",
2607                                     path);
2608                break;
2609        case S_IFLNK:
2610                if (strbuf_readlink(&sb, path, st->st_size)) {
2611                        char *errstr = strerror(errno);
2612                        return error("readlink(\"%s\"): %s", path,
2613                                     errstr);
2614                }
2615                if (!write_object)
2616                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2617                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2618                        return error("%s: failed to insert into database",
2619                                     path);
2620                strbuf_release(&sb);
2621                break;
2622        case S_IFDIR:
2623                return resolve_gitlink_ref(path, "HEAD", sha1);
2624        default:
2625                return error("%s: unsupported file type", path);
2626        }
2627        return 0;
2628}
2629
2630int read_pack_header(int fd, struct pack_header *header)
2631{
2632        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2633                /* "eof before pack header was fully read" */
2634                return PH_ERROR_EOF;
2635
2636        if (header->hdr_signature != htonl(PACK_SIGNATURE))
2637                /* "protocol error (pack signature mismatch detected)" */
2638                return PH_ERROR_PACK_SIGNATURE;
2639        if (!pack_version_ok(header->hdr_version))
2640                /* "protocol error (pack version unsupported)" */
2641                return PH_ERROR_PROTOCOL;
2642        return 0;
2643}
2644
2645void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
2646{
2647        enum object_type type = sha1_object_info(sha1, NULL);
2648        if (type < 0)
2649                die("%s is not a valid object", sha1_to_hex(sha1));
2650        if (type != expect)
2651                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
2652                    typename(expect));
2653}