8fb10e451cba0e07481c0c6f40ee97a7039c6360
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include "cache.h"
  10#include "string-list.h"
  11#include "delta.h"
  12#include "pack.h"
  13#include "blob.h"
  14#include "commit.h"
  15#include "run-command.h"
  16#include "tag.h"
  17#include "tree.h"
  18#include "tree-walk.h"
  19#include "refs.h"
  20#include "pack-revindex.h"
  21#include "sha1-lookup.h"
  22#include "bulk-checkin.h"
  23#include "streaming.h"
  24#include "dir.h"
  25
  26#ifndef O_NOATIME
  27#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  28#define O_NOATIME 01000000
  29#else
  30#define O_NOATIME 0
  31#endif
  32#endif
  33
  34#define SZ_FMT PRIuMAX
  35static inline uintmax_t sz_fmt(size_t s) { return s; }
  36
  37const unsigned char null_sha1[20];
  38
  39/*
  40 * This is meant to hold a *small* number of objects that you would
  41 * want read_sha1_file() to be able to return, but yet you do not want
  42 * to write them into the object store (e.g. a browse-only
  43 * application).
  44 */
  45static struct cached_object {
  46        unsigned char sha1[20];
  47        enum object_type type;
  48        void *buf;
  49        unsigned long size;
  50} *cached_objects;
  51static int cached_object_nr, cached_object_alloc;
  52
  53static struct cached_object empty_tree = {
  54        EMPTY_TREE_SHA1_BIN_LITERAL,
  55        OBJ_TREE,
  56        "",
  57        0
  58};
  59
  60static struct packed_git *last_found_pack;
  61
  62static struct cached_object *find_cached_object(const unsigned char *sha1)
  63{
  64        int i;
  65        struct cached_object *co = cached_objects;
  66
  67        for (i = 0; i < cached_object_nr; i++, co++) {
  68                if (!hashcmp(co->sha1, sha1))
  69                        return co;
  70        }
  71        if (!hashcmp(sha1, empty_tree.sha1))
  72                return &empty_tree;
  73        return NULL;
  74}
  75
  76int mkdir_in_gitdir(const char *path)
  77{
  78        if (mkdir(path, 0777)) {
  79                int saved_errno = errno;
  80                struct stat st;
  81                struct strbuf sb = STRBUF_INIT;
  82
  83                if (errno != EEXIST)
  84                        return -1;
  85                /*
  86                 * Are we looking at a path in a symlinked worktree
  87                 * whose original repository does not yet have it?
  88                 * e.g. .git/rr-cache pointing at its original
  89                 * repository in which the user hasn't performed any
  90                 * conflict resolution yet?
  91                 */
  92                if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
  93                    strbuf_readlink(&sb, path, st.st_size) ||
  94                    !is_absolute_path(sb.buf) ||
  95                    mkdir(sb.buf, 0777)) {
  96                        strbuf_release(&sb);
  97                        errno = saved_errno;
  98                        return -1;
  99                }
 100                strbuf_release(&sb);
 101        }
 102        return adjust_shared_perm(path);
 103}
 104
 105int safe_create_leading_directories(char *path)
 106{
 107        char *pos = path + offset_1st_component(path);
 108        struct stat st;
 109
 110        while (pos) {
 111                pos = strchr(pos, '/');
 112                if (!pos)
 113                        break;
 114                while (*++pos == '/')
 115                        ;
 116                if (!*pos)
 117                        break;
 118                *--pos = '\0';
 119                if (!stat(path, &st)) {
 120                        /* path exists */
 121                        if (!S_ISDIR(st.st_mode)) {
 122                                *pos = '/';
 123                                return -3;
 124                        }
 125                }
 126                else if (mkdir(path, 0777)) {
 127                        if (errno == EEXIST &&
 128                            !stat(path, &st) && S_ISDIR(st.st_mode)) {
 129                                ; /* somebody created it since we checked */
 130                        } else {
 131                                *pos = '/';
 132                                return -1;
 133                        }
 134                }
 135                else if (adjust_shared_perm(path)) {
 136                        *pos = '/';
 137                        return -2;
 138                }
 139                *pos++ = '/';
 140        }
 141        return 0;
 142}
 143
 144int safe_create_leading_directories_const(const char *path)
 145{
 146        /* path points to cache entries, so xstrdup before messing with it */
 147        char *buf = xstrdup(path);
 148        int result = safe_create_leading_directories(buf);
 149        free(buf);
 150        return result;
 151}
 152
 153static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 154{
 155        int i;
 156        for (i = 0; i < 20; i++) {
 157                static char hex[] = "0123456789abcdef";
 158                unsigned int val = sha1[i];
 159                char *pos = pathbuf + i*2 + (i > 0);
 160                *pos++ = hex[val >> 4];
 161                *pos = hex[val & 0xf];
 162        }
 163}
 164
 165/*
 166 * NOTE! This returns a statically allocated buffer, so you have to be
 167 * careful about using it. Do an "xstrdup()" if you need to save the
 168 * filename.
 169 *
 170 * Also note that this returns the location for creating.  Reading
 171 * SHA1 file can happen from any alternate directory listed in the
 172 * DB_ENVIRONMENT environment variable if it is not found in
 173 * the primary object database.
 174 */
 175char *sha1_file_name(const unsigned char *sha1)
 176{
 177        static char buf[PATH_MAX];
 178        const char *objdir;
 179        int len;
 180
 181        objdir = get_object_directory();
 182        len = strlen(objdir);
 183
 184        /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 185        if (len + 43 > PATH_MAX)
 186                die("insanely long object directory %s", objdir);
 187        memcpy(buf, objdir, len);
 188        buf[len] = '/';
 189        buf[len+3] = '/';
 190        buf[len+42] = '\0';
 191        fill_sha1_path(buf + len + 1, sha1);
 192        return buf;
 193}
 194
 195static char *sha1_get_pack_name(const unsigned char *sha1,
 196                                char **name, char **base, const char *which)
 197{
 198        static const char hex[] = "0123456789abcdef";
 199        char *buf;
 200        int i;
 201
 202        if (!*base) {
 203                const char *sha1_file_directory = get_object_directory();
 204                int len = strlen(sha1_file_directory);
 205                *base = xmalloc(len + 60);
 206                sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 207                        sha1_file_directory, which);
 208                *name = *base + len + 11;
 209        }
 210
 211        buf = *name;
 212
 213        for (i = 0; i < 20; i++) {
 214                unsigned int val = *sha1++;
 215                *buf++ = hex[val >> 4];
 216                *buf++ = hex[val & 0xf];
 217        }
 218
 219        return *base;
 220}
 221
 222char *sha1_pack_name(const unsigned char *sha1)
 223{
 224        static char *name, *base;
 225
 226        return sha1_get_pack_name(sha1, &name, &base, "pack");
 227}
 228
 229char *sha1_pack_index_name(const unsigned char *sha1)
 230{
 231        static char *name, *base;
 232
 233        return sha1_get_pack_name(sha1, &name, &base, "idx");
 234}
 235
 236struct alternate_object_database *alt_odb_list;
 237static struct alternate_object_database **alt_odb_tail;
 238
 239static int git_open_noatime(const char *name);
 240
 241/*
 242 * Prepare alternate object database registry.
 243 *
 244 * The variable alt_odb_list points at the list of struct
 245 * alternate_object_database.  The elements on this list come from
 246 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 247 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 248 * whose contents is similar to that environment variable but can be
 249 * LF separated.  Its base points at a statically allocated buffer that
 250 * contains "/the/directory/corresponding/to/.git/objects/...", while
 251 * its name points just after the slash at the end of ".git/objects/"
 252 * in the example above, and has enough space to hold 40-byte hex
 253 * SHA1, an extra slash for the first level indirection, and the
 254 * terminating NUL.
 255 */
 256static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
 257{
 258        const char *objdir = get_object_directory();
 259        struct alternate_object_database *ent;
 260        struct alternate_object_database *alt;
 261        int pfxlen, entlen;
 262        struct strbuf pathbuf = STRBUF_INIT;
 263
 264        if (!is_absolute_path(entry) && relative_base) {
 265                strbuf_addstr(&pathbuf, real_path(relative_base));
 266                strbuf_addch(&pathbuf, '/');
 267        }
 268        strbuf_addstr(&pathbuf, entry);
 269
 270        normalize_path_copy(pathbuf.buf, pathbuf.buf);
 271
 272        pfxlen = strlen(pathbuf.buf);
 273
 274        /*
 275         * The trailing slash after the directory name is given by
 276         * this function at the end. Remove duplicates.
 277         */
 278        while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
 279                pfxlen -= 1;
 280
 281        entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
 282        ent = xmalloc(sizeof(*ent) + entlen);
 283        memcpy(ent->base, pathbuf.buf, pfxlen);
 284        strbuf_release(&pathbuf);
 285
 286        ent->name = ent->base + pfxlen + 1;
 287        ent->base[pfxlen + 3] = '/';
 288        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 289
 290        /* Detect cases where alternate disappeared */
 291        if (!is_directory(ent->base)) {
 292                error("object directory %s does not exist; "
 293                      "check .git/objects/info/alternates.",
 294                      ent->base);
 295                free(ent);
 296                return -1;
 297        }
 298
 299        /* Prevent the common mistake of listing the same
 300         * thing twice, or object directory itself.
 301         */
 302        for (alt = alt_odb_list; alt; alt = alt->next) {
 303                if (!memcmp(ent->base, alt->base, pfxlen)) {
 304                        free(ent);
 305                        return -1;
 306                }
 307        }
 308        if (!strcmp(ent->base, objdir)) {
 309                free(ent);
 310                return -1;
 311        }
 312
 313        /* add the alternate entry */
 314        *alt_odb_tail = ent;
 315        alt_odb_tail = &(ent->next);
 316        ent->next = NULL;
 317
 318        /* recursively add alternates */
 319        read_info_alternates(ent->base, depth + 1);
 320
 321        ent->base[pfxlen] = '/';
 322
 323        return 0;
 324}
 325
 326static void link_alt_odb_entries(const char *alt, int len, int sep,
 327                                 const char *relative_base, int depth)
 328{
 329        struct string_list entries = STRING_LIST_INIT_NODUP;
 330        char *alt_copy;
 331        int i;
 332
 333        if (depth > 5) {
 334                error("%s: ignoring alternate object stores, nesting too deep.",
 335                                relative_base);
 336                return;
 337        }
 338
 339        alt_copy = xmemdupz(alt, len);
 340        string_list_split_in_place(&entries, alt_copy, sep, -1);
 341        for (i = 0; i < entries.nr; i++) {
 342                const char *entry = entries.items[i].string;
 343                if (entry[0] == '\0' || entry[0] == '#')
 344                        continue;
 345                if (!is_absolute_path(entry) && depth) {
 346                        error("%s: ignoring relative alternate object store %s",
 347                                        relative_base, entry);
 348                } else {
 349                        link_alt_odb_entry(entry, relative_base, depth);
 350                }
 351        }
 352        string_list_clear(&entries, 0);
 353        free(alt_copy);
 354}
 355
 356void read_info_alternates(const char * relative_base, int depth)
 357{
 358        char *map;
 359        size_t mapsz;
 360        struct stat st;
 361        const char alt_file_name[] = "info/alternates";
 362        /* Given that relative_base is no longer than PATH_MAX,
 363           ensure that "path" has enough space to append "/", the
 364           file name, "info/alternates", and a trailing NUL.  */
 365        char path[PATH_MAX + 1 + sizeof alt_file_name];
 366        int fd;
 367
 368        sprintf(path, "%s/%s", relative_base, alt_file_name);
 369        fd = git_open_noatime(path);
 370        if (fd < 0)
 371                return;
 372        if (fstat(fd, &st) || (st.st_size == 0)) {
 373                close(fd);
 374                return;
 375        }
 376        mapsz = xsize_t(st.st_size);
 377        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 378        close(fd);
 379
 380        link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
 381
 382        munmap(map, mapsz);
 383}
 384
 385void add_to_alternates_file(const char *reference)
 386{
 387        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 388        int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
 389        char *alt = mkpath("%s\n", reference);
 390        write_or_die(fd, alt, strlen(alt));
 391        if (commit_lock_file(lock))
 392                die("could not close alternates file");
 393        if (alt_odb_tail)
 394                link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
 395}
 396
 397void foreach_alt_odb(alt_odb_fn fn, void *cb)
 398{
 399        struct alternate_object_database *ent;
 400
 401        prepare_alt_odb();
 402        for (ent = alt_odb_list; ent; ent = ent->next)
 403                if (fn(ent, cb))
 404                        return;
 405}
 406
 407void prepare_alt_odb(void)
 408{
 409        const char *alt;
 410
 411        if (alt_odb_tail)
 412                return;
 413
 414        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 415        if (!alt) alt = "";
 416
 417        alt_odb_tail = &alt_odb_list;
 418        link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
 419
 420        read_info_alternates(get_object_directory(), 0);
 421}
 422
 423static int has_loose_object_local(const unsigned char *sha1)
 424{
 425        char *name = sha1_file_name(sha1);
 426        return !access(name, F_OK);
 427}
 428
 429int has_loose_object_nonlocal(const unsigned char *sha1)
 430{
 431        struct alternate_object_database *alt;
 432        prepare_alt_odb();
 433        for (alt = alt_odb_list; alt; alt = alt->next) {
 434                fill_sha1_path(alt->name, sha1);
 435                if (!access(alt->base, F_OK))
 436                        return 1;
 437        }
 438        return 0;
 439}
 440
 441static int has_loose_object(const unsigned char *sha1)
 442{
 443        return has_loose_object_local(sha1) ||
 444               has_loose_object_nonlocal(sha1);
 445}
 446
 447static unsigned int pack_used_ctr;
 448static unsigned int pack_mmap_calls;
 449static unsigned int peak_pack_open_windows;
 450static unsigned int pack_open_windows;
 451static unsigned int pack_open_fds;
 452static unsigned int pack_max_fds;
 453static size_t peak_pack_mapped;
 454static size_t pack_mapped;
 455struct packed_git *packed_git;
 456
 457void pack_report(void)
 458{
 459        fprintf(stderr,
 460                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 461                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 462                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 463                sz_fmt(getpagesize()),
 464                sz_fmt(packed_git_window_size),
 465                sz_fmt(packed_git_limit));
 466        fprintf(stderr,
 467                "pack_report: pack_used_ctr            = %10u\n"
 468                "pack_report: pack_mmap_calls          = %10u\n"
 469                "pack_report: pack_open_windows        = %10u / %10u\n"
 470                "pack_report: pack_mapped              = "
 471                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 472                pack_used_ctr,
 473                pack_mmap_calls,
 474                pack_open_windows, peak_pack_open_windows,
 475                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 476}
 477
 478static int check_packed_git_idx(const char *path,  struct packed_git *p)
 479{
 480        void *idx_map;
 481        struct pack_idx_header *hdr;
 482        size_t idx_size;
 483        uint32_t version, nr, i, *index;
 484        int fd = git_open_noatime(path);
 485        struct stat st;
 486
 487        if (fd < 0)
 488                return -1;
 489        if (fstat(fd, &st)) {
 490                close(fd);
 491                return -1;
 492        }
 493        idx_size = xsize_t(st.st_size);
 494        if (idx_size < 4 * 256 + 20 + 20) {
 495                close(fd);
 496                return error("index file %s is too small", path);
 497        }
 498        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 499        close(fd);
 500
 501        hdr = idx_map;
 502        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 503                version = ntohl(hdr->idx_version);
 504                if (version < 2 || version > 2) {
 505                        munmap(idx_map, idx_size);
 506                        return error("index file %s is version %"PRIu32
 507                                     " and is not supported by this binary"
 508                                     " (try upgrading GIT to a newer version)",
 509                                     path, version);
 510                }
 511        } else
 512                version = 1;
 513
 514        nr = 0;
 515        index = idx_map;
 516        if (version > 1)
 517                index += 2;  /* skip index header */
 518        for (i = 0; i < 256; i++) {
 519                uint32_t n = ntohl(index[i]);
 520                if (n < nr) {
 521                        munmap(idx_map, idx_size);
 522                        return error("non-monotonic index %s", path);
 523                }
 524                nr = n;
 525        }
 526
 527        if (version == 1) {
 528                /*
 529                 * Total size:
 530                 *  - 256 index entries 4 bytes each
 531                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 532                 *  - 20-byte SHA1 of the packfile
 533                 *  - 20-byte SHA1 file checksum
 534                 */
 535                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 536                        munmap(idx_map, idx_size);
 537                        return error("wrong index v1 file size in %s", path);
 538                }
 539        } else if (version == 2) {
 540                /*
 541                 * Minimum size:
 542                 *  - 8 bytes of header
 543                 *  - 256 index entries 4 bytes each
 544                 *  - 20-byte sha1 entry * nr
 545                 *  - 4-byte crc entry * nr
 546                 *  - 4-byte offset entry * nr
 547                 *  - 20-byte SHA1 of the packfile
 548                 *  - 20-byte SHA1 file checksum
 549                 * And after the 4-byte offset table might be a
 550                 * variable sized table containing 8-byte entries
 551                 * for offsets larger than 2^31.
 552                 */
 553                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 554                unsigned long max_size = min_size;
 555                if (nr)
 556                        max_size += (nr - 1)*8;
 557                if (idx_size < min_size || idx_size > max_size) {
 558                        munmap(idx_map, idx_size);
 559                        return error("wrong index v2 file size in %s", path);
 560                }
 561                if (idx_size != min_size &&
 562                    /*
 563                     * make sure we can deal with large pack offsets.
 564                     * 31-bit signed offset won't be enough, neither
 565                     * 32-bit unsigned one will be.
 566                     */
 567                    (sizeof(off_t) <= 4)) {
 568                        munmap(idx_map, idx_size);
 569                        return error("pack too large for current definition of off_t in %s", path);
 570                }
 571        }
 572
 573        p->index_version = version;
 574        p->index_data = idx_map;
 575        p->index_size = idx_size;
 576        p->num_objects = nr;
 577        return 0;
 578}
 579
 580int open_pack_index(struct packed_git *p)
 581{
 582        char *idx_name;
 583        int ret;
 584
 585        if (p->index_data)
 586                return 0;
 587
 588        idx_name = xstrdup(p->pack_name);
 589        strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
 590        ret = check_packed_git_idx(idx_name, p);
 591        free(idx_name);
 592        return ret;
 593}
 594
 595static void scan_windows(struct packed_git *p,
 596        struct packed_git **lru_p,
 597        struct pack_window **lru_w,
 598        struct pack_window **lru_l)
 599{
 600        struct pack_window *w, *w_l;
 601
 602        for (w_l = NULL, w = p->windows; w; w = w->next) {
 603                if (!w->inuse_cnt) {
 604                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 605                                *lru_p = p;
 606                                *lru_w = w;
 607                                *lru_l = w_l;
 608                        }
 609                }
 610                w_l = w;
 611        }
 612}
 613
 614static int unuse_one_window(struct packed_git *current, int keep_fd)
 615{
 616        struct packed_git *p, *lru_p = NULL;
 617        struct pack_window *lru_w = NULL, *lru_l = NULL;
 618
 619        if (current)
 620                scan_windows(current, &lru_p, &lru_w, &lru_l);
 621        for (p = packed_git; p; p = p->next)
 622                scan_windows(p, &lru_p, &lru_w, &lru_l);
 623        if (lru_p) {
 624                munmap(lru_w->base, lru_w->len);
 625                pack_mapped -= lru_w->len;
 626                if (lru_l)
 627                        lru_l->next = lru_w->next;
 628                else {
 629                        lru_p->windows = lru_w->next;
 630                        if (!lru_p->windows && lru_p->pack_fd != -1
 631                                && lru_p->pack_fd != keep_fd) {
 632                                close(lru_p->pack_fd);
 633                                pack_open_fds--;
 634                                lru_p->pack_fd = -1;
 635                        }
 636                }
 637                free(lru_w);
 638                pack_open_windows--;
 639                return 1;
 640        }
 641        return 0;
 642}
 643
 644void release_pack_memory(size_t need, int fd)
 645{
 646        size_t cur = pack_mapped;
 647        while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
 648                ; /* nothing */
 649}
 650
 651void *xmmap(void *start, size_t length,
 652        int prot, int flags, int fd, off_t offset)
 653{
 654        void *ret = mmap(start, length, prot, flags, fd, offset);
 655        if (ret == MAP_FAILED) {
 656                if (!length)
 657                        return NULL;
 658                release_pack_memory(length, fd);
 659                ret = mmap(start, length, prot, flags, fd, offset);
 660                if (ret == MAP_FAILED)
 661                        die_errno("Out of memory? mmap failed");
 662        }
 663        return ret;
 664}
 665
 666void close_pack_windows(struct packed_git *p)
 667{
 668        while (p->windows) {
 669                struct pack_window *w = p->windows;
 670
 671                if (w->inuse_cnt)
 672                        die("pack '%s' still has open windows to it",
 673                            p->pack_name);
 674                munmap(w->base, w->len);
 675                pack_mapped -= w->len;
 676                pack_open_windows--;
 677                p->windows = w->next;
 678                free(w);
 679        }
 680}
 681
 682void unuse_pack(struct pack_window **w_cursor)
 683{
 684        struct pack_window *w = *w_cursor;
 685        if (w) {
 686                w->inuse_cnt--;
 687                *w_cursor = NULL;
 688        }
 689}
 690
 691void close_pack_index(struct packed_git *p)
 692{
 693        if (p->index_data) {
 694                munmap((void *)p->index_data, p->index_size);
 695                p->index_data = NULL;
 696        }
 697}
 698
 699/*
 700 * This is used by git-repack in case a newly created pack happens to
 701 * contain the same set of objects as an existing one.  In that case
 702 * the resulting file might be different even if its name would be the
 703 * same.  It is best to close any reference to the old pack before it is
 704 * replaced on disk.  Of course no index pointers nor windows for given pack
 705 * must subsist at this point.  If ever objects from this pack are requested
 706 * again, the new version of the pack will be reinitialized through
 707 * reprepare_packed_git().
 708 */
 709void free_pack_by_name(const char *pack_name)
 710{
 711        struct packed_git *p, **pp = &packed_git;
 712
 713        while (*pp) {
 714                p = *pp;
 715                if (strcmp(pack_name, p->pack_name) == 0) {
 716                        clear_delta_base_cache();
 717                        close_pack_windows(p);
 718                        if (p->pack_fd != -1) {
 719                                close(p->pack_fd);
 720                                pack_open_fds--;
 721                        }
 722                        close_pack_index(p);
 723                        free(p->bad_object_sha1);
 724                        *pp = p->next;
 725                        if (last_found_pack == p)
 726                                last_found_pack = NULL;
 727                        free(p);
 728                        return;
 729                }
 730                pp = &p->next;
 731        }
 732}
 733
 734static unsigned int get_max_fd_limit(void)
 735{
 736#ifdef RLIMIT_NOFILE
 737        struct rlimit lim;
 738
 739        if (getrlimit(RLIMIT_NOFILE, &lim))
 740                die_errno("cannot get RLIMIT_NOFILE");
 741
 742        return lim.rlim_cur;
 743#elif defined(_SC_OPEN_MAX)
 744        return sysconf(_SC_OPEN_MAX);
 745#elif defined(OPEN_MAX)
 746        return OPEN_MAX;
 747#else
 748        return 1; /* see the caller ;-) */
 749#endif
 750}
 751
 752/*
 753 * Do not call this directly as this leaks p->pack_fd on error return;
 754 * call open_packed_git() instead.
 755 */
 756static int open_packed_git_1(struct packed_git *p)
 757{
 758        struct stat st;
 759        struct pack_header hdr;
 760        unsigned char sha1[20];
 761        unsigned char *idx_sha1;
 762        long fd_flag;
 763
 764        if (!p->index_data && open_pack_index(p))
 765                return error("packfile %s index unavailable", p->pack_name);
 766
 767        if (!pack_max_fds) {
 768                unsigned int max_fds = get_max_fd_limit();
 769
 770                /* Save 3 for stdin/stdout/stderr, 22 for work */
 771                if (25 < max_fds)
 772                        pack_max_fds = max_fds - 25;
 773                else
 774                        pack_max_fds = 1;
 775        }
 776
 777        while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
 778                ; /* nothing */
 779
 780        p->pack_fd = git_open_noatime(p->pack_name);
 781        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 782                return -1;
 783        pack_open_fds++;
 784
 785        /* If we created the struct before we had the pack we lack size. */
 786        if (!p->pack_size) {
 787                if (!S_ISREG(st.st_mode))
 788                        return error("packfile %s not a regular file", p->pack_name);
 789                p->pack_size = st.st_size;
 790        } else if (p->pack_size != st.st_size)
 791                return error("packfile %s size changed", p->pack_name);
 792
 793        /* We leave these file descriptors open with sliding mmap;
 794         * there is no point keeping them open across exec(), though.
 795         */
 796        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 797        if (fd_flag < 0)
 798                return error("cannot determine file descriptor flags");
 799        fd_flag |= FD_CLOEXEC;
 800        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 801                return error("cannot set FD_CLOEXEC");
 802
 803        /* Verify we recognize this pack file format. */
 804        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 805                return error("file %s is far too short to be a packfile", p->pack_name);
 806        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 807                return error("file %s is not a GIT packfile", p->pack_name);
 808        if (!pack_version_ok(hdr.hdr_version))
 809                return error("packfile %s is version %"PRIu32" and not"
 810                        " supported (try upgrading GIT to a newer version)",
 811                        p->pack_name, ntohl(hdr.hdr_version));
 812
 813        /* Verify the pack matches its index. */
 814        if (p->num_objects != ntohl(hdr.hdr_entries))
 815                return error("packfile %s claims to have %"PRIu32" objects"
 816                             " while index indicates %"PRIu32" objects",
 817                             p->pack_name, ntohl(hdr.hdr_entries),
 818                             p->num_objects);
 819        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 820                return error("end of packfile %s is unavailable", p->pack_name);
 821        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 822                return error("packfile %s signature is unavailable", p->pack_name);
 823        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 824        if (hashcmp(sha1, idx_sha1))
 825                return error("packfile %s does not match index", p->pack_name);
 826        return 0;
 827}
 828
 829static int open_packed_git(struct packed_git *p)
 830{
 831        if (!open_packed_git_1(p))
 832                return 0;
 833        if (p->pack_fd != -1) {
 834                close(p->pack_fd);
 835                pack_open_fds--;
 836                p->pack_fd = -1;
 837        }
 838        return -1;
 839}
 840
 841static int in_window(struct pack_window *win, off_t offset)
 842{
 843        /* We must promise at least 20 bytes (one hash) after the
 844         * offset is available from this window, otherwise the offset
 845         * is not actually in this window and a different window (which
 846         * has that one hash excess) must be used.  This is to support
 847         * the object header and delta base parsing routines below.
 848         */
 849        off_t win_off = win->offset;
 850        return win_off <= offset
 851                && (offset + 20) <= (win_off + win->len);
 852}
 853
 854unsigned char *use_pack(struct packed_git *p,
 855                struct pack_window **w_cursor,
 856                off_t offset,
 857                unsigned long *left)
 858{
 859        struct pack_window *win = *w_cursor;
 860
 861        /* Since packfiles end in a hash of their content and it's
 862         * pointless to ask for an offset into the middle of that
 863         * hash, and the in_window function above wouldn't match
 864         * don't allow an offset too close to the end of the file.
 865         */
 866        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 867                die("packfile %s cannot be accessed", p->pack_name);
 868        if (offset > (p->pack_size - 20))
 869                die("offset beyond end of packfile (truncated pack?)");
 870
 871        if (!win || !in_window(win, offset)) {
 872                if (win)
 873                        win->inuse_cnt--;
 874                for (win = p->windows; win; win = win->next) {
 875                        if (in_window(win, offset))
 876                                break;
 877                }
 878                if (!win) {
 879                        size_t window_align = packed_git_window_size / 2;
 880                        off_t len;
 881
 882                        if (p->pack_fd == -1 && open_packed_git(p))
 883                                die("packfile %s cannot be accessed", p->pack_name);
 884
 885                        win = xcalloc(1, sizeof(*win));
 886                        win->offset = (offset / window_align) * window_align;
 887                        len = p->pack_size - win->offset;
 888                        if (len > packed_git_window_size)
 889                                len = packed_git_window_size;
 890                        win->len = (size_t)len;
 891                        pack_mapped += win->len;
 892                        while (packed_git_limit < pack_mapped
 893                                && unuse_one_window(p, p->pack_fd))
 894                                ; /* nothing */
 895                        win->base = xmmap(NULL, win->len,
 896                                PROT_READ, MAP_PRIVATE,
 897                                p->pack_fd, win->offset);
 898                        if (win->base == MAP_FAILED)
 899                                die("packfile %s cannot be mapped: %s",
 900                                        p->pack_name,
 901                                        strerror(errno));
 902                        if (!win->offset && win->len == p->pack_size
 903                                && !p->do_not_close) {
 904                                close(p->pack_fd);
 905                                pack_open_fds--;
 906                                p->pack_fd = -1;
 907                        }
 908                        pack_mmap_calls++;
 909                        pack_open_windows++;
 910                        if (pack_mapped > peak_pack_mapped)
 911                                peak_pack_mapped = pack_mapped;
 912                        if (pack_open_windows > peak_pack_open_windows)
 913                                peak_pack_open_windows = pack_open_windows;
 914                        win->next = p->windows;
 915                        p->windows = win;
 916                }
 917        }
 918        if (win != *w_cursor) {
 919                win->last_used = pack_used_ctr++;
 920                win->inuse_cnt++;
 921                *w_cursor = win;
 922        }
 923        offset -= win->offset;
 924        if (left)
 925                *left = win->len - xsize_t(offset);
 926        return win->base + offset;
 927}
 928
 929static struct packed_git *alloc_packed_git(int extra)
 930{
 931        struct packed_git *p = xmalloc(sizeof(*p) + extra);
 932        memset(p, 0, sizeof(*p));
 933        p->pack_fd = -1;
 934        return p;
 935}
 936
 937static void try_to_free_pack_memory(size_t size)
 938{
 939        release_pack_memory(size, -1);
 940}
 941
 942struct packed_git *add_packed_git(const char *path, int path_len, int local)
 943{
 944        static int have_set_try_to_free_routine;
 945        struct stat st;
 946        struct packed_git *p = alloc_packed_git(path_len + 2);
 947
 948        if (!have_set_try_to_free_routine) {
 949                have_set_try_to_free_routine = 1;
 950                set_try_to_free_routine(try_to_free_pack_memory);
 951        }
 952
 953        /*
 954         * Make sure a corresponding .pack file exists and that
 955         * the index looks sane.
 956         */
 957        path_len -= strlen(".idx");
 958        if (path_len < 1) {
 959                free(p);
 960                return NULL;
 961        }
 962        memcpy(p->pack_name, path, path_len);
 963
 964        strcpy(p->pack_name + path_len, ".keep");
 965        if (!access(p->pack_name, F_OK))
 966                p->pack_keep = 1;
 967
 968        strcpy(p->pack_name + path_len, ".pack");
 969        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 970                free(p);
 971                return NULL;
 972        }
 973
 974        /* ok, it looks sane as far as we can check without
 975         * actually mapping the pack file.
 976         */
 977        p->pack_size = st.st_size;
 978        p->pack_local = local;
 979        p->mtime = st.st_mtime;
 980        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 981                hashclr(p->sha1);
 982        return p;
 983}
 984
 985struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 986{
 987        const char *path = sha1_pack_name(sha1);
 988        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 989
 990        strcpy(p->pack_name, path);
 991        hashcpy(p->sha1, sha1);
 992        if (check_packed_git_idx(idx_path, p)) {
 993                free(p);
 994                return NULL;
 995        }
 996
 997        return p;
 998}
 999
1000void install_packed_git(struct packed_git *pack)
1001{
1002        if (pack->pack_fd != -1)
1003                pack_open_fds++;
1004
1005        pack->next = packed_git;
1006        packed_git = pack;
1007}
1008
1009void (*report_garbage)(const char *desc, const char *path);
1010
1011static void report_helper(const struct string_list *list,
1012                          int seen_bits, int first, int last)
1013{
1014        const char *msg;
1015        switch (seen_bits) {
1016        case 0:
1017                msg = "no corresponding .idx nor .pack";
1018                break;
1019        case 1:
1020                msg = "no corresponding .idx";
1021                break;
1022        case 2:
1023                msg = "no corresponding .pack";
1024                break;
1025        default:
1026                return;
1027        }
1028        for (; first < last; first++)
1029                report_garbage(msg, list->items[first].string);
1030}
1031
1032static void report_pack_garbage(struct string_list *list)
1033{
1034        int i, baselen = -1, first = 0, seen_bits = 0;
1035
1036        if (!report_garbage)
1037                return;
1038
1039        sort_string_list(list);
1040
1041        for (i = 0; i < list->nr; i++) {
1042                const char *path = list->items[i].string;
1043                if (baselen != -1 &&
1044                    strncmp(path, list->items[first].string, baselen)) {
1045                        report_helper(list, seen_bits, first, i);
1046                        baselen = -1;
1047                        seen_bits = 0;
1048                }
1049                if (baselen == -1) {
1050                        const char *dot = strrchr(path, '.');
1051                        if (!dot) {
1052                                report_garbage("garbage found", path);
1053                                continue;
1054                        }
1055                        baselen = dot - path + 1;
1056                        first = i;
1057                }
1058                if (!strcmp(path + baselen, "pack"))
1059                        seen_bits |= 1;
1060                else if (!strcmp(path + baselen, "idx"))
1061                        seen_bits |= 2;
1062        }
1063        report_helper(list, seen_bits, first, list->nr);
1064}
1065
1066static void prepare_packed_git_one(char *objdir, int local)
1067{
1068        /* Ensure that this buffer is large enough so that we can
1069           append "/pack/" without clobbering the stack even if
1070           strlen(objdir) were PATH_MAX.  */
1071        char path[PATH_MAX + 1 + 4 + 1 + 1];
1072        int len;
1073        DIR *dir;
1074        struct dirent *de;
1075        struct string_list garbage = STRING_LIST_INIT_DUP;
1076
1077        sprintf(path, "%s/pack", objdir);
1078        len = strlen(path);
1079        dir = opendir(path);
1080        if (!dir) {
1081                if (errno != ENOENT)
1082                        error("unable to open object pack directory: %s: %s",
1083                              path, strerror(errno));
1084                return;
1085        }
1086        path[len++] = '/';
1087        while ((de = readdir(dir)) != NULL) {
1088                int namelen = strlen(de->d_name);
1089                struct packed_git *p;
1090
1091                if (len + namelen + 1 > sizeof(path)) {
1092                        if (report_garbage) {
1093                                struct strbuf sb = STRBUF_INIT;
1094                                strbuf_addf(&sb, "%.*s/%s", len - 1, path, de->d_name);
1095                                report_garbage("path too long", sb.buf);
1096                                strbuf_release(&sb);
1097                        }
1098                        continue;
1099                }
1100
1101                if (is_dot_or_dotdot(de->d_name))
1102                        continue;
1103
1104                strcpy(path + len, de->d_name);
1105
1106                if (has_extension(de->d_name, ".idx")) {
1107                        /* Don't reopen a pack we already have. */
1108                        for (p = packed_git; p; p = p->next) {
1109                                if (!memcmp(path, p->pack_name, len + namelen - 4))
1110                                        break;
1111                        }
1112                        if (p == NULL &&
1113                            /*
1114                             * See if it really is a valid .idx file with
1115                             * corresponding .pack file that we can map.
1116                             */
1117                            (p = add_packed_git(path, len + namelen, local)) != NULL)
1118                                install_packed_git(p);
1119                }
1120
1121                if (!report_garbage)
1122                        continue;
1123
1124                if (has_extension(de->d_name, ".idx") ||
1125                    has_extension(de->d_name, ".pack") ||
1126                    has_extension(de->d_name, ".keep"))
1127                        string_list_append(&garbage, path);
1128                else
1129                        report_garbage("garbage found", path);
1130        }
1131        closedir(dir);
1132        report_pack_garbage(&garbage);
1133        string_list_clear(&garbage, 0);
1134}
1135
1136static int sort_pack(const void *a_, const void *b_)
1137{
1138        struct packed_git *a = *((struct packed_git **)a_);
1139        struct packed_git *b = *((struct packed_git **)b_);
1140        int st;
1141
1142        /*
1143         * Local packs tend to contain objects specific to our
1144         * variant of the project than remote ones.  In addition,
1145         * remote ones could be on a network mounted filesystem.
1146         * Favor local ones for these reasons.
1147         */
1148        st = a->pack_local - b->pack_local;
1149        if (st)
1150                return -st;
1151
1152        /*
1153         * Younger packs tend to contain more recent objects,
1154         * and more recent objects tend to get accessed more
1155         * often.
1156         */
1157        if (a->mtime < b->mtime)
1158                return 1;
1159        else if (a->mtime == b->mtime)
1160                return 0;
1161        return -1;
1162}
1163
1164static void rearrange_packed_git(void)
1165{
1166        struct packed_git **ary, *p;
1167        int i, n;
1168
1169        for (n = 0, p = packed_git; p; p = p->next)
1170                n++;
1171        if (n < 2)
1172                return;
1173
1174        /* prepare an array of packed_git for easier sorting */
1175        ary = xcalloc(n, sizeof(struct packed_git *));
1176        for (n = 0, p = packed_git; p; p = p->next)
1177                ary[n++] = p;
1178
1179        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1180
1181        /* link them back again */
1182        for (i = 0; i < n - 1; i++)
1183                ary[i]->next = ary[i + 1];
1184        ary[n - 1]->next = NULL;
1185        packed_git = ary[0];
1186
1187        free(ary);
1188}
1189
1190static int prepare_packed_git_run_once = 0;
1191void prepare_packed_git(void)
1192{
1193        struct alternate_object_database *alt;
1194
1195        if (prepare_packed_git_run_once)
1196                return;
1197        prepare_packed_git_one(get_object_directory(), 1);
1198        prepare_alt_odb();
1199        for (alt = alt_odb_list; alt; alt = alt->next) {
1200                alt->name[-1] = 0;
1201                prepare_packed_git_one(alt->base, 0);
1202                alt->name[-1] = '/';
1203        }
1204        rearrange_packed_git();
1205        prepare_packed_git_run_once = 1;
1206}
1207
1208void reprepare_packed_git(void)
1209{
1210        discard_revindex();
1211        prepare_packed_git_run_once = 0;
1212        prepare_packed_git();
1213}
1214
1215static void mark_bad_packed_object(struct packed_git *p,
1216                                   const unsigned char *sha1)
1217{
1218        unsigned i;
1219        for (i = 0; i < p->num_bad_objects; i++)
1220                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1221                        return;
1222        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1223        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1224        p->num_bad_objects++;
1225}
1226
1227static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1228{
1229        struct packed_git *p;
1230        unsigned i;
1231
1232        for (p = packed_git; p; p = p->next)
1233                for (i = 0; i < p->num_bad_objects; i++)
1234                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1235                                return p;
1236        return NULL;
1237}
1238
1239/*
1240 * With an in-core object data in "map", rehash it to make sure the
1241 * object name actually matches "sha1" to detect object corruption.
1242 * With "map" == NULL, try reading the object named with "sha1" using
1243 * the streaming interface and rehash it to do the same.
1244 */
1245int check_sha1_signature(const unsigned char *sha1, void *map,
1246                         unsigned long size, const char *type)
1247{
1248        unsigned char real_sha1[20];
1249        enum object_type obj_type;
1250        struct git_istream *st;
1251        git_SHA_CTX c;
1252        char hdr[32];
1253        int hdrlen;
1254
1255        if (map) {
1256                hash_sha1_file(map, size, type, real_sha1);
1257                return hashcmp(sha1, real_sha1) ? -1 : 0;
1258        }
1259
1260        st = open_istream(sha1, &obj_type, &size, NULL);
1261        if (!st)
1262                return -1;
1263
1264        /* Generate the header */
1265        hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
1266
1267        /* Sha1.. */
1268        git_SHA1_Init(&c);
1269        git_SHA1_Update(&c, hdr, hdrlen);
1270        for (;;) {
1271                char buf[1024 * 16];
1272                ssize_t readlen = read_istream(st, buf, sizeof(buf));
1273
1274                if (readlen < 0) {
1275                        close_istream(st);
1276                        return -1;
1277                }
1278                if (!readlen)
1279                        break;
1280                git_SHA1_Update(&c, buf, readlen);
1281        }
1282        git_SHA1_Final(real_sha1, &c);
1283        close_istream(st);
1284        return hashcmp(sha1, real_sha1) ? -1 : 0;
1285}
1286
1287static int git_open_noatime(const char *name)
1288{
1289        static int sha1_file_open_flag = O_NOATIME;
1290
1291        for (;;) {
1292                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1293                if (fd >= 0)
1294                        return fd;
1295
1296                /* Might the failure be due to O_NOATIME? */
1297                if (errno != ENOENT && sha1_file_open_flag) {
1298                        sha1_file_open_flag = 0;
1299                        continue;
1300                }
1301
1302                return -1;
1303        }
1304}
1305
1306static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
1307{
1308        char *name = sha1_file_name(sha1);
1309        struct alternate_object_database *alt;
1310
1311        if (!lstat(name, st))
1312                return 0;
1313
1314        prepare_alt_odb();
1315        errno = ENOENT;
1316        for (alt = alt_odb_list; alt; alt = alt->next) {
1317                name = alt->name;
1318                fill_sha1_path(name, sha1);
1319                if (!lstat(alt->base, st))
1320                        return 0;
1321        }
1322
1323        return -1;
1324}
1325
1326static int open_sha1_file(const unsigned char *sha1)
1327{
1328        int fd;
1329        char *name = sha1_file_name(sha1);
1330        struct alternate_object_database *alt;
1331
1332        fd = git_open_noatime(name);
1333        if (fd >= 0)
1334                return fd;
1335
1336        prepare_alt_odb();
1337        errno = ENOENT;
1338        for (alt = alt_odb_list; alt; alt = alt->next) {
1339                name = alt->name;
1340                fill_sha1_path(name, sha1);
1341                fd = git_open_noatime(alt->base);
1342                if (fd >= 0)
1343                        return fd;
1344        }
1345        return -1;
1346}
1347
1348void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1349{
1350        void *map;
1351        int fd;
1352
1353        fd = open_sha1_file(sha1);
1354        map = NULL;
1355        if (fd >= 0) {
1356                struct stat st;
1357
1358                if (!fstat(fd, &st)) {
1359                        *size = xsize_t(st.st_size);
1360                        if (!*size) {
1361                                /* mmap() is forbidden on empty files */
1362                                error("object file %s is empty", sha1_file_name(sha1));
1363                                return NULL;
1364                        }
1365                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1366                }
1367                close(fd);
1368        }
1369        return map;
1370}
1371
1372/*
1373 * There used to be a second loose object header format which
1374 * was meant to mimic the in-pack format, allowing for direct
1375 * copy of the object data.  This format turned up not to be
1376 * really worth it and we no longer write loose objects in that
1377 * format.
1378 */
1379static int experimental_loose_object(unsigned char *map)
1380{
1381        unsigned int word;
1382
1383        /*
1384         * We must determine if the buffer contains the standard
1385         * zlib-deflated stream or the experimental format based
1386         * on the in-pack object format. Compare the header byte
1387         * for each format:
1388         *
1389         * RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
1390         * Experimental pack-based : Stttssss : ttt = 1,2,3,4
1391         *
1392         * If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
1393         * in standard loose-object format, UNLESS it is a Git-pack
1394         * format object *exactly* 8 bytes in size when inflated.
1395         *
1396         * However, RFC1950 also specifies that the 1st 16-bit word
1397         * must be divisible by 31 - this checksum tells us our buffer
1398         * is in the standard format, giving a false positive only if
1399         * the 1st word of the Git-pack format object happens to be
1400         * divisible by 31, ie:
1401         *      ((byte0 * 256) + byte1) % 31 = 0
1402         *   =>        0ttt10000www1000 % 31 = 0
1403         *
1404         * As it happens, this case can only arise for www=3 & ttt=1
1405         * - ie, a Commit object, which would have to be 8 bytes in
1406         * size. As no Commit can be that small, we find that the
1407         * combination of these two criteria (bitmask & checksum)
1408         * can always correctly determine the buffer format.
1409         */
1410        word = (map[0] << 8) + map[1];
1411        if ((map[0] & 0x8F) == 0x08 && !(word % 31))
1412                return 0;
1413        else
1414                return 1;
1415}
1416
1417unsigned long unpack_object_header_buffer(const unsigned char *buf,
1418                unsigned long len, enum object_type *type, unsigned long *sizep)
1419{
1420        unsigned shift;
1421        unsigned long size, c;
1422        unsigned long used = 0;
1423
1424        c = buf[used++];
1425        *type = (c >> 4) & 7;
1426        size = c & 15;
1427        shift = 4;
1428        while (c & 0x80) {
1429                if (len <= used || bitsizeof(long) <= shift) {
1430                        error("bad object header");
1431                        size = used = 0;
1432                        break;
1433                }
1434                c = buf[used++];
1435                size += (c & 0x7f) << shift;
1436                shift += 7;
1437        }
1438        *sizep = size;
1439        return used;
1440}
1441
1442int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1443{
1444        unsigned long size, used;
1445        static const char valid_loose_object_type[8] = {
1446                0, /* OBJ_EXT */
1447                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1448                0, /* "delta" and others are invalid in a loose object */
1449        };
1450        enum object_type type;
1451
1452        /* Get the data stream */
1453        memset(stream, 0, sizeof(*stream));
1454        stream->next_in = map;
1455        stream->avail_in = mapsize;
1456        stream->next_out = buffer;
1457        stream->avail_out = bufsiz;
1458
1459        if (experimental_loose_object(map)) {
1460                /*
1461                 * The old experimental format we no longer produce;
1462                 * we can still read it.
1463                 */
1464                used = unpack_object_header_buffer(map, mapsize, &type, &size);
1465                if (!used || !valid_loose_object_type[type])
1466                        return -1;
1467                map += used;
1468                mapsize -= used;
1469
1470                /* Set up the stream for the rest.. */
1471                stream->next_in = map;
1472                stream->avail_in = mapsize;
1473                git_inflate_init(stream);
1474
1475                /* And generate the fake traditional header */
1476                stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1477                                                 typename(type), size);
1478                return 0;
1479        }
1480        git_inflate_init(stream);
1481        return git_inflate(stream, 0);
1482}
1483
1484static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1485{
1486        int bytes = strlen(buffer) + 1;
1487        unsigned char *buf = xmallocz(size);
1488        unsigned long n;
1489        int status = Z_OK;
1490
1491        n = stream->total_out - bytes;
1492        if (n > size)
1493                n = size;
1494        memcpy(buf, (char *) buffer + bytes, n);
1495        bytes = n;
1496        if (bytes <= size) {
1497                /*
1498                 * The above condition must be (bytes <= size), not
1499                 * (bytes < size).  In other words, even though we
1500                 * expect no more output and set avail_out to zero,
1501                 * the input zlib stream may have bytes that express
1502                 * "this concludes the stream", and we *do* want to
1503                 * eat that input.
1504                 *
1505                 * Otherwise we would not be able to test that we
1506                 * consumed all the input to reach the expected size;
1507                 * we also want to check that zlib tells us that all
1508                 * went well with status == Z_STREAM_END at the end.
1509                 */
1510                stream->next_out = buf + bytes;
1511                stream->avail_out = size - bytes;
1512                while (status == Z_OK)
1513                        status = git_inflate(stream, Z_FINISH);
1514        }
1515        if (status == Z_STREAM_END && !stream->avail_in) {
1516                git_inflate_end(stream);
1517                return buf;
1518        }
1519
1520        if (status < 0)
1521                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1522        else if (stream->avail_in)
1523                error("garbage at end of loose object '%s'",
1524                      sha1_to_hex(sha1));
1525        free(buf);
1526        return NULL;
1527}
1528
1529/*
1530 * We used to just use "sscanf()", but that's actually way
1531 * too permissive for what we want to check. So do an anal
1532 * object header parse by hand.
1533 */
1534int parse_sha1_header(const char *hdr, unsigned long *sizep)
1535{
1536        char type[10];
1537        int i;
1538        unsigned long size;
1539
1540        /*
1541         * The type can be at most ten bytes (including the
1542         * terminating '\0' that we add), and is followed by
1543         * a space.
1544         */
1545        i = 0;
1546        for (;;) {
1547                char c = *hdr++;
1548                if (c == ' ')
1549                        break;
1550                type[i++] = c;
1551                if (i >= sizeof(type))
1552                        return -1;
1553        }
1554        type[i] = 0;
1555
1556        /*
1557         * The length must follow immediately, and be in canonical
1558         * decimal format (ie "010" is not valid).
1559         */
1560        size = *hdr++ - '0';
1561        if (size > 9)
1562                return -1;
1563        if (size) {
1564                for (;;) {
1565                        unsigned long c = *hdr - '0';
1566                        if (c > 9)
1567                                break;
1568                        hdr++;
1569                        size = size * 10 + c;
1570                }
1571        }
1572        *sizep = size;
1573
1574        /*
1575         * The length must be followed by a zero byte
1576         */
1577        return *hdr ? -1 : type_from_string(type);
1578}
1579
1580static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1581{
1582        int ret;
1583        git_zstream stream;
1584        char hdr[8192];
1585
1586        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1587        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1588                return NULL;
1589
1590        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1591}
1592
1593unsigned long get_size_from_delta(struct packed_git *p,
1594                                  struct pack_window **w_curs,
1595                                  off_t curpos)
1596{
1597        const unsigned char *data;
1598        unsigned char delta_head[20], *in;
1599        git_zstream stream;
1600        int st;
1601
1602        memset(&stream, 0, sizeof(stream));
1603        stream.next_out = delta_head;
1604        stream.avail_out = sizeof(delta_head);
1605
1606        git_inflate_init(&stream);
1607        do {
1608                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1609                stream.next_in = in;
1610                st = git_inflate(&stream, Z_FINISH);
1611                curpos += stream.next_in - in;
1612        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1613                 stream.total_out < sizeof(delta_head));
1614        git_inflate_end(&stream);
1615        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1616                error("delta data unpack-initial failed");
1617                return 0;
1618        }
1619
1620        /* Examine the initial part of the delta to figure out
1621         * the result size.
1622         */
1623        data = delta_head;
1624
1625        /* ignore base size */
1626        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1627
1628        /* Read the result size */
1629        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1630}
1631
1632static off_t get_delta_base(struct packed_git *p,
1633                                    struct pack_window **w_curs,
1634                                    off_t *curpos,
1635                                    enum object_type type,
1636                                    off_t delta_obj_offset)
1637{
1638        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1639        off_t base_offset;
1640
1641        /* use_pack() assured us we have [base_info, base_info + 20)
1642         * as a range that we can look at without walking off the
1643         * end of the mapped window.  Its actually the hash size
1644         * that is assured.  An OFS_DELTA longer than the hash size
1645         * is stupid, as then a REF_DELTA would be smaller to store.
1646         */
1647        if (type == OBJ_OFS_DELTA) {
1648                unsigned used = 0;
1649                unsigned char c = base_info[used++];
1650                base_offset = c & 127;
1651                while (c & 128) {
1652                        base_offset += 1;
1653                        if (!base_offset || MSB(base_offset, 7))
1654                                return 0;  /* overflow */
1655                        c = base_info[used++];
1656                        base_offset = (base_offset << 7) + (c & 127);
1657                }
1658                base_offset = delta_obj_offset - base_offset;
1659                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1660                        return 0;  /* out of bound */
1661                *curpos += used;
1662        } else if (type == OBJ_REF_DELTA) {
1663                /* The base entry _must_ be in the same pack */
1664                base_offset = find_pack_entry_one(base_info, p);
1665                *curpos += 20;
1666        } else
1667                die("I am totally screwed");
1668        return base_offset;
1669}
1670
1671int unpack_object_header(struct packed_git *p,
1672                         struct pack_window **w_curs,
1673                         off_t *curpos,
1674                         unsigned long *sizep)
1675{
1676        unsigned char *base;
1677        unsigned long left;
1678        unsigned long used;
1679        enum object_type type;
1680
1681        /* use_pack() assures us we have [base, base + 20) available
1682         * as a range that we can look at.  (Its actually the hash
1683         * size that is assured.)  With our object header encoding
1684         * the maximum deflated object size is 2^137, which is just
1685         * insane, so we know won't exceed what we have been given.
1686         */
1687        base = use_pack(p, w_curs, *curpos, &left);
1688        used = unpack_object_header_buffer(base, left, &type, sizep);
1689        if (!used) {
1690                type = OBJ_BAD;
1691        } else
1692                *curpos += used;
1693
1694        return type;
1695}
1696
1697static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
1698{
1699        int type;
1700        struct revindex_entry *revidx;
1701        const unsigned char *sha1;
1702        revidx = find_pack_revindex(p, obj_offset);
1703        if (!revidx)
1704                return OBJ_BAD;
1705        sha1 = nth_packed_object_sha1(p, revidx->nr);
1706        mark_bad_packed_object(p, sha1);
1707        type = sha1_object_info(sha1, NULL);
1708        if (type <= OBJ_NONE)
1709                return OBJ_BAD;
1710        return type;
1711}
1712
1713#define POI_STACK_PREALLOC 64
1714
1715static enum object_type packed_to_object_type(struct packed_git *p,
1716                                              off_t obj_offset,
1717                                              enum object_type type,
1718                                              struct pack_window **w_curs,
1719                                              off_t curpos)
1720{
1721        off_t small_poi_stack[POI_STACK_PREALLOC];
1722        off_t *poi_stack = small_poi_stack;
1723        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1724
1725        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1726                off_t base_offset;
1727                unsigned long size;
1728                /* Push the object we're going to leave behind */
1729                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1730                        poi_stack_alloc = alloc_nr(poi_stack_nr);
1731                        poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
1732                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1733                } else {
1734                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1735                }
1736                poi_stack[poi_stack_nr++] = obj_offset;
1737                /* If parsing the base offset fails, just unwind */
1738                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1739                if (!base_offset)
1740                        goto unwind;
1741                curpos = obj_offset = base_offset;
1742                type = unpack_object_header(p, w_curs, &curpos, &size);
1743                if (type <= OBJ_NONE) {
1744                        /* If getting the base itself fails, we first
1745                         * retry the base, otherwise unwind */
1746                        type = retry_bad_packed_offset(p, base_offset);
1747                        if (type > OBJ_NONE)
1748                                goto out;
1749                        goto unwind;
1750                }
1751        }
1752
1753        switch (type) {
1754        case OBJ_BAD:
1755        case OBJ_COMMIT:
1756        case OBJ_TREE:
1757        case OBJ_BLOB:
1758        case OBJ_TAG:
1759                break;
1760        default:
1761                error("unknown object type %i at offset %"PRIuMAX" in %s",
1762                      type, (uintmax_t)obj_offset, p->pack_name);
1763                type = OBJ_BAD;
1764        }
1765
1766out:
1767        if (poi_stack != small_poi_stack)
1768                free(poi_stack);
1769        return type;
1770
1771unwind:
1772        while (poi_stack_nr) {
1773                obj_offset = poi_stack[--poi_stack_nr];
1774                type = retry_bad_packed_offset(p, obj_offset);
1775                if (type > OBJ_NONE)
1776                        goto out;
1777        }
1778        type = OBJ_BAD;
1779        goto out;
1780}
1781
1782static int packed_object_info(struct packed_git *p, off_t obj_offset,
1783                              unsigned long *sizep, int *rtype,
1784                              unsigned long *disk_sizep)
1785{
1786        struct pack_window *w_curs = NULL;
1787        unsigned long size;
1788        off_t curpos = obj_offset;
1789        enum object_type type;
1790
1791        type = unpack_object_header(p, &w_curs, &curpos, &size);
1792
1793        if (rtype)
1794                *rtype = type; /* representation type */
1795
1796        if (sizep) {
1797                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1798                        off_t tmp_pos = curpos;
1799                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1800                                                           type, obj_offset);
1801                        if (!base_offset) {
1802                                type = OBJ_BAD;
1803                                goto out;
1804                        }
1805                        *sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1806                        if (*sizep == 0) {
1807                                type = OBJ_BAD;
1808                                goto out;
1809                        }
1810                } else {
1811                        *sizep = size;
1812                }
1813        }
1814
1815        if (disk_sizep) {
1816                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1817                *disk_sizep = revidx[1].offset - obj_offset;
1818        }
1819
1820        type = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
1821
1822out:
1823        unuse_pack(&w_curs);
1824        return type;
1825}
1826
1827static void *unpack_compressed_entry(struct packed_git *p,
1828                                    struct pack_window **w_curs,
1829                                    off_t curpos,
1830                                    unsigned long size)
1831{
1832        int st;
1833        git_zstream stream;
1834        unsigned char *buffer, *in;
1835
1836        buffer = xmallocz(size);
1837        memset(&stream, 0, sizeof(stream));
1838        stream.next_out = buffer;
1839        stream.avail_out = size + 1;
1840
1841        git_inflate_init(&stream);
1842        do {
1843                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1844                stream.next_in = in;
1845                st = git_inflate(&stream, Z_FINISH);
1846                if (!stream.avail_out)
1847                        break; /* the payload is larger than it should be */
1848                curpos += stream.next_in - in;
1849        } while (st == Z_OK || st == Z_BUF_ERROR);
1850        git_inflate_end(&stream);
1851        if ((st != Z_STREAM_END) || stream.total_out != size) {
1852                free(buffer);
1853                return NULL;
1854        }
1855
1856        return buffer;
1857}
1858
1859#define MAX_DELTA_CACHE (256)
1860
1861static size_t delta_base_cached;
1862
1863static struct delta_base_cache_lru_list {
1864        struct delta_base_cache_lru_list *prev;
1865        struct delta_base_cache_lru_list *next;
1866} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1867
1868static struct delta_base_cache_entry {
1869        struct delta_base_cache_lru_list lru;
1870        void *data;
1871        struct packed_git *p;
1872        off_t base_offset;
1873        unsigned long size;
1874        enum object_type type;
1875} delta_base_cache[MAX_DELTA_CACHE];
1876
1877static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1878{
1879        unsigned long hash;
1880
1881        hash = (unsigned long)p + (unsigned long)base_offset;
1882        hash += (hash >> 8) + (hash >> 16);
1883        return hash % MAX_DELTA_CACHE;
1884}
1885
1886static struct delta_base_cache_entry *
1887get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1888{
1889        unsigned long hash = pack_entry_hash(p, base_offset);
1890        return delta_base_cache + hash;
1891}
1892
1893static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
1894                                     struct packed_git *p, off_t base_offset)
1895{
1896        return (ent->data && ent->p == p && ent->base_offset == base_offset);
1897}
1898
1899static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1900{
1901        struct delta_base_cache_entry *ent;
1902        ent = get_delta_base_cache_entry(p, base_offset);
1903        return eq_delta_base_cache_entry(ent, p, base_offset);
1904}
1905
1906static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1907{
1908        ent->data = NULL;
1909        ent->lru.next->prev = ent->lru.prev;
1910        ent->lru.prev->next = ent->lru.next;
1911        delta_base_cached -= ent->size;
1912}
1913
1914static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1915        unsigned long *base_size, enum object_type *type, int keep_cache)
1916{
1917        struct delta_base_cache_entry *ent;
1918        void *ret;
1919
1920        ent = get_delta_base_cache_entry(p, base_offset);
1921
1922        if (!eq_delta_base_cache_entry(ent, p, base_offset))
1923                return unpack_entry(p, base_offset, type, base_size);
1924
1925        ret = ent->data;
1926
1927        if (!keep_cache)
1928                clear_delta_base_cache_entry(ent);
1929        else
1930                ret = xmemdupz(ent->data, ent->size);
1931        *type = ent->type;
1932        *base_size = ent->size;
1933        return ret;
1934}
1935
1936static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1937{
1938        if (ent->data) {
1939                free(ent->data);
1940                ent->data = NULL;
1941                ent->lru.next->prev = ent->lru.prev;
1942                ent->lru.prev->next = ent->lru.next;
1943                delta_base_cached -= ent->size;
1944        }
1945}
1946
1947void clear_delta_base_cache(void)
1948{
1949        unsigned long p;
1950        for (p = 0; p < MAX_DELTA_CACHE; p++)
1951                release_delta_base_cache(&delta_base_cache[p]);
1952}
1953
1954static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1955        void *base, unsigned long base_size, enum object_type type)
1956{
1957        unsigned long hash = pack_entry_hash(p, base_offset);
1958        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1959        struct delta_base_cache_lru_list *lru;
1960
1961        release_delta_base_cache(ent);
1962        delta_base_cached += base_size;
1963
1964        for (lru = delta_base_cache_lru.next;
1965             delta_base_cached > delta_base_cache_limit
1966             && lru != &delta_base_cache_lru;
1967             lru = lru->next) {
1968                struct delta_base_cache_entry *f = (void *)lru;
1969                if (f->type == OBJ_BLOB)
1970                        release_delta_base_cache(f);
1971        }
1972        for (lru = delta_base_cache_lru.next;
1973             delta_base_cached > delta_base_cache_limit
1974             && lru != &delta_base_cache_lru;
1975             lru = lru->next) {
1976                struct delta_base_cache_entry *f = (void *)lru;
1977                release_delta_base_cache(f);
1978        }
1979
1980        ent->p = p;
1981        ent->base_offset = base_offset;
1982        ent->type = type;
1983        ent->data = base;
1984        ent->size = base_size;
1985        ent->lru.next = &delta_base_cache_lru;
1986        ent->lru.prev = delta_base_cache_lru.prev;
1987        delta_base_cache_lru.prev->next = &ent->lru;
1988        delta_base_cache_lru.prev = &ent->lru;
1989}
1990
1991static void *read_object(const unsigned char *sha1, enum object_type *type,
1992                         unsigned long *size);
1993
1994static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1995{
1996        static FILE *log_file;
1997
1998        if (!log_file) {
1999                log_file = fopen(log_pack_access, "w");
2000                if (!log_file) {
2001                        error("cannot open pack access log '%s' for writing: %s",
2002                              log_pack_access, strerror(errno));
2003                        log_pack_access = NULL;
2004                        return;
2005                }
2006        }
2007        fprintf(log_file, "%s %"PRIuMAX"\n",
2008                p->pack_name, (uintmax_t)obj_offset);
2009        fflush(log_file);
2010}
2011
2012int do_check_packed_object_crc;
2013
2014#define UNPACK_ENTRY_STACK_PREALLOC 64
2015struct unpack_entry_stack_ent {
2016        off_t obj_offset;
2017        off_t curpos;
2018        unsigned long size;
2019};
2020
2021void *unpack_entry(struct packed_git *p, off_t obj_offset,
2022                   enum object_type *final_type, unsigned long *final_size)
2023{
2024        struct pack_window *w_curs = NULL;
2025        off_t curpos = obj_offset;
2026        void *data = NULL;
2027        unsigned long size;
2028        enum object_type type;
2029        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
2030        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
2031        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
2032        int base_from_cache = 0;
2033
2034        if (log_pack_access)
2035                write_pack_access_log(p, obj_offset);
2036
2037        /* PHASE 1: drill down to the innermost base object */
2038        for (;;) {
2039                off_t base_offset;
2040                int i;
2041                struct delta_base_cache_entry *ent;
2042
2043                if (do_check_packed_object_crc && p->index_version > 1) {
2044                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
2045                        unsigned long len = revidx[1].offset - obj_offset;
2046                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
2047                                const unsigned char *sha1 =
2048                                        nth_packed_object_sha1(p, revidx->nr);
2049                                error("bad packed object CRC for %s",
2050                                      sha1_to_hex(sha1));
2051                                mark_bad_packed_object(p, sha1);
2052                                unuse_pack(&w_curs);
2053                                return NULL;
2054                        }
2055                }
2056
2057                ent = get_delta_base_cache_entry(p, curpos);
2058                if (eq_delta_base_cache_entry(ent, p, curpos)) {
2059                        type = ent->type;
2060                        data = ent->data;
2061                        size = ent->size;
2062                        clear_delta_base_cache_entry(ent);
2063                        base_from_cache = 1;
2064                        break;
2065                }
2066
2067                type = unpack_object_header(p, &w_curs, &curpos, &size);
2068                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
2069                        break;
2070
2071                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
2072                if (!base_offset) {
2073                        error("failed to validate delta base reference "
2074                              "at offset %"PRIuMAX" from %s",
2075                              (uintmax_t)curpos, p->pack_name);
2076                        /* bail to phase 2, in hopes of recovery */
2077                        data = NULL;
2078                        break;
2079                }
2080
2081                /* push object, proceed to base */
2082                if (delta_stack_nr >= delta_stack_alloc
2083                    && delta_stack == small_delta_stack) {
2084                        delta_stack_alloc = alloc_nr(delta_stack_nr);
2085                        delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
2086                        memcpy(delta_stack, small_delta_stack,
2087                               sizeof(*delta_stack)*delta_stack_nr);
2088                } else {
2089                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
2090                }
2091                i = delta_stack_nr++;
2092                delta_stack[i].obj_offset = obj_offset;
2093                delta_stack[i].curpos = curpos;
2094                delta_stack[i].size = size;
2095
2096                curpos = obj_offset = base_offset;
2097        }
2098
2099        /* PHASE 2: handle the base */
2100        switch (type) {
2101        case OBJ_OFS_DELTA:
2102        case OBJ_REF_DELTA:
2103                if (data)
2104                        die("BUG in unpack_entry: left loop at a valid delta");
2105                break;
2106        case OBJ_COMMIT:
2107        case OBJ_TREE:
2108        case OBJ_BLOB:
2109        case OBJ_TAG:
2110                if (!base_from_cache)
2111                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
2112                break;
2113        default:
2114                data = NULL;
2115                error("unknown object type %i at offset %"PRIuMAX" in %s",
2116                      type, (uintmax_t)obj_offset, p->pack_name);
2117        }
2118
2119        /* PHASE 3: apply deltas in order */
2120
2121        /* invariants:
2122         *   'data' holds the base data, or NULL if there was corruption
2123         */
2124        while (delta_stack_nr) {
2125                void *delta_data;
2126                void *base = data;
2127                unsigned long delta_size, base_size = size;
2128                int i;
2129
2130                data = NULL;
2131
2132                if (base)
2133                        add_delta_base_cache(p, obj_offset, base, base_size, type);
2134
2135                if (!base) {
2136                        /*
2137                         * We're probably in deep shit, but let's try to fetch
2138                         * the required base anyway from another pack or loose.
2139                         * This is costly but should happen only in the presence
2140                         * of a corrupted pack, and is better than failing outright.
2141                         */
2142                        struct revindex_entry *revidx;
2143                        const unsigned char *base_sha1;
2144                        revidx = find_pack_revindex(p, obj_offset);
2145                        if (revidx) {
2146                                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
2147                                error("failed to read delta base object %s"
2148                                      " at offset %"PRIuMAX" from %s",
2149                                      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
2150                                      p->pack_name);
2151                                mark_bad_packed_object(p, base_sha1);
2152                                base = read_object(base_sha1, &type, &base_size);
2153                        }
2154                }
2155
2156                i = --delta_stack_nr;
2157                obj_offset = delta_stack[i].obj_offset;
2158                curpos = delta_stack[i].curpos;
2159                delta_size = delta_stack[i].size;
2160
2161                if (!base)
2162                        continue;
2163
2164                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
2165
2166                if (!delta_data) {
2167                        error("failed to unpack compressed delta "
2168                              "at offset %"PRIuMAX" from %s",
2169                              (uintmax_t)curpos, p->pack_name);
2170                        data = NULL;
2171                        continue;
2172                }
2173
2174                data = patch_delta(base, base_size,
2175                                   delta_data, delta_size,
2176                                   &size);
2177                if (!data)
2178                        die("failed to apply delta");
2179
2180                free (delta_data);
2181        }
2182
2183        *final_type = type;
2184        *final_size = size;
2185
2186        unuse_pack(&w_curs);
2187        return data;
2188}
2189
2190const unsigned char *nth_packed_object_sha1(struct packed_git *p,
2191                                            uint32_t n)
2192{
2193        const unsigned char *index = p->index_data;
2194        if (!index) {
2195                if (open_pack_index(p))
2196                        return NULL;
2197                index = p->index_data;
2198        }
2199        if (n >= p->num_objects)
2200                return NULL;
2201        index += 4 * 256;
2202        if (p->index_version == 1) {
2203                return index + 24 * n + 4;
2204        } else {
2205                index += 8;
2206                return index + 20 * n;
2207        }
2208}
2209
2210off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
2211{
2212        const unsigned char *index = p->index_data;
2213        index += 4 * 256;
2214        if (p->index_version == 1) {
2215                return ntohl(*((uint32_t *)(index + 24 * n)));
2216        } else {
2217                uint32_t off;
2218                index += 8 + p->num_objects * (20 + 4);
2219                off = ntohl(*((uint32_t *)(index + 4 * n)));
2220                if (!(off & 0x80000000))
2221                        return off;
2222                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
2223                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
2224                                   ntohl(*((uint32_t *)(index + 4)));
2225        }
2226}
2227
2228off_t find_pack_entry_one(const unsigned char *sha1,
2229                                  struct packed_git *p)
2230{
2231        const uint32_t *level1_ofs = p->index_data;
2232        const unsigned char *index = p->index_data;
2233        unsigned hi, lo, stride;
2234        static int use_lookup = -1;
2235        static int debug_lookup = -1;
2236
2237        if (debug_lookup < 0)
2238                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
2239
2240        if (!index) {
2241                if (open_pack_index(p))
2242                        return 0;
2243                level1_ofs = p->index_data;
2244                index = p->index_data;
2245        }
2246        if (p->index_version > 1) {
2247                level1_ofs += 2;
2248                index += 8;
2249        }
2250        index += 4 * 256;
2251        hi = ntohl(level1_ofs[*sha1]);
2252        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
2253        if (p->index_version > 1) {
2254                stride = 20;
2255        } else {
2256                stride = 24;
2257                index += 4;
2258        }
2259
2260        if (debug_lookup)
2261                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
2262                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
2263
2264        if (use_lookup < 0)
2265                use_lookup = !!getenv("GIT_USE_LOOKUP");
2266        if (use_lookup) {
2267                int pos = sha1_entry_pos(index, stride, 0,
2268                                         lo, hi, p->num_objects, sha1);
2269                if (pos < 0)
2270                        return 0;
2271                return nth_packed_object_offset(p, pos);
2272        }
2273
2274        do {
2275                unsigned mi = (lo + hi) / 2;
2276                int cmp = hashcmp(index + mi * stride, sha1);
2277
2278                if (debug_lookup)
2279                        printf("lo %u hi %u rg %u mi %u\n",
2280                               lo, hi, hi - lo, mi);
2281                if (!cmp)
2282                        return nth_packed_object_offset(p, mi);
2283                if (cmp > 0)
2284                        hi = mi;
2285                else
2286                        lo = mi+1;
2287        } while (lo < hi);
2288        return 0;
2289}
2290
2291int is_pack_valid(struct packed_git *p)
2292{
2293        /* An already open pack is known to be valid. */
2294        if (p->pack_fd != -1)
2295                return 1;
2296
2297        /* If the pack has one window completely covering the
2298         * file size, the pack is known to be valid even if
2299         * the descriptor is not currently open.
2300         */
2301        if (p->windows) {
2302                struct pack_window *w = p->windows;
2303
2304                if (!w->offset && w->len == p->pack_size)
2305                        return 1;
2306        }
2307
2308        /* Force the pack to open to prove its valid. */
2309        return !open_packed_git(p);
2310}
2311
2312static int fill_pack_entry(const unsigned char *sha1,
2313                           struct pack_entry *e,
2314                           struct packed_git *p)
2315{
2316        off_t offset;
2317
2318        if (p->num_bad_objects) {
2319                unsigned i;
2320                for (i = 0; i < p->num_bad_objects; i++)
2321                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2322                                return 0;
2323        }
2324
2325        offset = find_pack_entry_one(sha1, p);
2326        if (!offset)
2327                return 0;
2328
2329        /*
2330         * We are about to tell the caller where they can locate the
2331         * requested object.  We better make sure the packfile is
2332         * still here and can be accessed before supplying that
2333         * answer, as it may have been deleted since the index was
2334         * loaded!
2335         */
2336        if (!is_pack_valid(p)) {
2337                warning("packfile %s cannot be accessed", p->pack_name);
2338                return 0;
2339        }
2340        e->offset = offset;
2341        e->p = p;
2342        hashcpy(e->sha1, sha1);
2343        return 1;
2344}
2345
2346static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2347{
2348        struct packed_git *p;
2349
2350        prepare_packed_git();
2351        if (!packed_git)
2352                return 0;
2353
2354        if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2355                return 1;
2356
2357        for (p = packed_git; p; p = p->next) {
2358                if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
2359                        continue;
2360
2361                last_found_pack = p;
2362                return 1;
2363        }
2364        return 0;
2365}
2366
2367struct packed_git *find_sha1_pack(const unsigned char *sha1,
2368                                  struct packed_git *packs)
2369{
2370        struct packed_git *p;
2371
2372        for (p = packs; p; p = p->next) {
2373                if (find_pack_entry_one(sha1, p))
2374                        return p;
2375        }
2376        return NULL;
2377
2378}
2379
2380static int sha1_loose_object_info(const unsigned char *sha1,
2381                                  enum object_type *typep,
2382                                  unsigned long *sizep,
2383                                  unsigned long *disk_sizep)
2384{
2385        int status;
2386        unsigned long mapsize, size;
2387        void *map;
2388        git_zstream stream;
2389        char hdr[32];
2390
2391        /*
2392         * If we don't care about type or size, then we don't
2393         * need to look inside the object at all.
2394         */
2395        if (!typep && !sizep) {
2396                if (disk_sizep) {
2397                        struct stat st;
2398                        if (stat_sha1_file(sha1, &st) < 0)
2399                                return -1;
2400                        *disk_sizep = st.st_size;
2401                }
2402                return 0;
2403        }
2404
2405        map = map_sha1_file(sha1, &mapsize);
2406        if (!map)
2407                return error("unable to find %s", sha1_to_hex(sha1));
2408        if (disk_sizep)
2409                *disk_sizep = mapsize;
2410        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2411                status = error("unable to unpack %s header",
2412                               sha1_to_hex(sha1));
2413        else if ((status = parse_sha1_header(hdr, &size)) < 0)
2414                status = error("unable to parse %s header", sha1_to_hex(sha1));
2415        else if (sizep)
2416                *sizep = size;
2417        git_inflate_end(&stream);
2418        munmap(map, mapsize);
2419        if (typep)
2420                *typep = status;
2421        return 0;
2422}
2423
2424/* returns enum object_type or negative */
2425int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
2426{
2427        struct cached_object *co;
2428        struct pack_entry e;
2429        int type, rtype;
2430
2431        co = find_cached_object(sha1);
2432        if (co) {
2433                if (oi->sizep)
2434                        *(oi->sizep) = co->size;
2435                if (oi->disk_sizep)
2436                        *(oi->disk_sizep) = 0;
2437                oi->whence = OI_CACHED;
2438                return co->type;
2439        }
2440
2441        if (!find_pack_entry(sha1, &e)) {
2442                /* Most likely it's a loose object. */
2443                if (!sha1_loose_object_info(sha1, &type,
2444                                            oi->sizep, oi->disk_sizep)) {
2445                        oi->whence = OI_LOOSE;
2446                        return type;
2447                }
2448
2449                /* Not a loose object; someone else may have just packed it. */
2450                reprepare_packed_git();
2451                if (!find_pack_entry(sha1, &e))
2452                        return -1;
2453        }
2454
2455        type = packed_object_info(e.p, e.offset, oi->sizep, &rtype,
2456                                  oi->disk_sizep);
2457        if (type < 0) {
2458                mark_bad_packed_object(e.p, sha1);
2459                type = sha1_object_info_extended(sha1, oi);
2460        } else if (in_delta_base_cache(e.p, e.offset)) {
2461                oi->whence = OI_DBCACHED;
2462        } else {
2463                oi->whence = OI_PACKED;
2464                oi->u.packed.offset = e.offset;
2465                oi->u.packed.pack = e.p;
2466                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2467                                         rtype == OBJ_OFS_DELTA);
2468        }
2469
2470        return type;
2471}
2472
2473int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2474{
2475        struct object_info oi = {0};
2476
2477        oi.sizep = sizep;
2478        return sha1_object_info_extended(sha1, &oi);
2479}
2480
2481static void *read_packed_sha1(const unsigned char *sha1,
2482                              enum object_type *type, unsigned long *size)
2483{
2484        struct pack_entry e;
2485        void *data;
2486
2487        if (!find_pack_entry(sha1, &e))
2488                return NULL;
2489        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2490        if (!data) {
2491                /*
2492                 * We're probably in deep shit, but let's try to fetch
2493                 * the required object anyway from another pack or loose.
2494                 * This should happen only in the presence of a corrupted
2495                 * pack, and is better than failing outright.
2496                 */
2497                error("failed to read object %s at offset %"PRIuMAX" from %s",
2498                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2499                mark_bad_packed_object(e.p, sha1);
2500                data = read_object(sha1, type, size);
2501        }
2502        return data;
2503}
2504
2505int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2506                      unsigned char *sha1)
2507{
2508        struct cached_object *co;
2509
2510        hash_sha1_file(buf, len, typename(type), sha1);
2511        if (has_sha1_file(sha1) || find_cached_object(sha1))
2512                return 0;
2513        if (cached_object_alloc <= cached_object_nr) {
2514                cached_object_alloc = alloc_nr(cached_object_alloc);
2515                cached_objects = xrealloc(cached_objects,
2516                                          sizeof(*cached_objects) *
2517                                          cached_object_alloc);
2518        }
2519        co = &cached_objects[cached_object_nr++];
2520        co->size = len;
2521        co->type = type;
2522        co->buf = xmalloc(len);
2523        memcpy(co->buf, buf, len);
2524        hashcpy(co->sha1, sha1);
2525        return 0;
2526}
2527
2528static void *read_object(const unsigned char *sha1, enum object_type *type,
2529                         unsigned long *size)
2530{
2531        unsigned long mapsize;
2532        void *map, *buf;
2533        struct cached_object *co;
2534
2535        co = find_cached_object(sha1);
2536        if (co) {
2537                *type = co->type;
2538                *size = co->size;
2539                return xmemdupz(co->buf, co->size);
2540        }
2541
2542        buf = read_packed_sha1(sha1, type, size);
2543        if (buf)
2544                return buf;
2545        map = map_sha1_file(sha1, &mapsize);
2546        if (map) {
2547                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2548                munmap(map, mapsize);
2549                return buf;
2550        }
2551        reprepare_packed_git();
2552        return read_packed_sha1(sha1, type, size);
2553}
2554
2555/*
2556 * This function dies on corrupt objects; the callers who want to
2557 * deal with them should arrange to call read_object() and give error
2558 * messages themselves.
2559 */
2560void *read_sha1_file_extended(const unsigned char *sha1,
2561                              enum object_type *type,
2562                              unsigned long *size,
2563                              unsigned flag)
2564{
2565        void *data;
2566        char *path;
2567        const struct packed_git *p;
2568        const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2569                ? lookup_replace_object(sha1) : sha1;
2570
2571        errno = 0;
2572        data = read_object(repl, type, size);
2573        if (data)
2574                return data;
2575
2576        if (errno && errno != ENOENT)
2577                die_errno("failed to read object %s", sha1_to_hex(sha1));
2578
2579        /* die if we replaced an object with one that does not exist */
2580        if (repl != sha1)
2581                die("replacement %s not found for %s",
2582                    sha1_to_hex(repl), sha1_to_hex(sha1));
2583
2584        if (has_loose_object(repl)) {
2585                path = sha1_file_name(sha1);
2586                die("loose object %s (stored in %s) is corrupt",
2587                    sha1_to_hex(repl), path);
2588        }
2589
2590        if ((p = has_packed_and_bad(repl)) != NULL)
2591                die("packed object %s (stored in %s) is corrupt",
2592                    sha1_to_hex(repl), p->pack_name);
2593
2594        return NULL;
2595}
2596
2597void *read_object_with_reference(const unsigned char *sha1,
2598                                 const char *required_type_name,
2599                                 unsigned long *size,
2600                                 unsigned char *actual_sha1_return)
2601{
2602        enum object_type type, required_type;
2603        void *buffer;
2604        unsigned long isize;
2605        unsigned char actual_sha1[20];
2606
2607        required_type = type_from_string(required_type_name);
2608        hashcpy(actual_sha1, sha1);
2609        while (1) {
2610                int ref_length = -1;
2611                const char *ref_type = NULL;
2612
2613                buffer = read_sha1_file(actual_sha1, &type, &isize);
2614                if (!buffer)
2615                        return NULL;
2616                if (type == required_type) {
2617                        *size = isize;
2618                        if (actual_sha1_return)
2619                                hashcpy(actual_sha1_return, actual_sha1);
2620                        return buffer;
2621                }
2622                /* Handle references */
2623                else if (type == OBJ_COMMIT)
2624                        ref_type = "tree ";
2625                else if (type == OBJ_TAG)
2626                        ref_type = "object ";
2627                else {
2628                        free(buffer);
2629                        return NULL;
2630                }
2631                ref_length = strlen(ref_type);
2632
2633                if (ref_length + 40 > isize ||
2634                    memcmp(buffer, ref_type, ref_length) ||
2635                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2636                        free(buffer);
2637                        return NULL;
2638                }
2639                free(buffer);
2640                /* Now we have the ID of the referred-to object in
2641                 * actual_sha1.  Check again. */
2642        }
2643}
2644
2645static void write_sha1_file_prepare(const void *buf, unsigned long len,
2646                                    const char *type, unsigned char *sha1,
2647                                    char *hdr, int *hdrlen)
2648{
2649        git_SHA_CTX c;
2650
2651        /* Generate the header */
2652        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2653
2654        /* Sha1.. */
2655        git_SHA1_Init(&c);
2656        git_SHA1_Update(&c, hdr, *hdrlen);
2657        git_SHA1_Update(&c, buf, len);
2658        git_SHA1_Final(sha1, &c);
2659}
2660
2661/*
2662 * Move the just written object into its final resting place.
2663 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2664 * "moving" is only a part of what it does, when no patch between
2665 * master to pu changes the call sites of this function.
2666 */
2667int move_temp_to_file(const char *tmpfile, const char *filename)
2668{
2669        int ret = 0;
2670
2671        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2672                goto try_rename;
2673        else if (link(tmpfile, filename))
2674                ret = errno;
2675
2676        /*
2677         * Coda hack - coda doesn't like cross-directory links,
2678         * so we fall back to a rename, which will mean that it
2679         * won't be able to check collisions, but that's not a
2680         * big deal.
2681         *
2682         * The same holds for FAT formatted media.
2683         *
2684         * When this succeeds, we just return.  We have nothing
2685         * left to unlink.
2686         */
2687        if (ret && ret != EEXIST) {
2688        try_rename:
2689                if (!rename(tmpfile, filename))
2690                        goto out;
2691                ret = errno;
2692        }
2693        unlink_or_warn(tmpfile);
2694        if (ret) {
2695                if (ret != EEXIST) {
2696                        return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
2697                }
2698                /* FIXME!!! Collision check here ? */
2699        }
2700
2701out:
2702        if (adjust_shared_perm(filename))
2703                return error("unable to set permission to '%s'", filename);
2704        return 0;
2705}
2706
2707static int write_buffer(int fd, const void *buf, size_t len)
2708{
2709        if (write_in_full(fd, buf, len) < 0)
2710                return error("file write error (%s)", strerror(errno));
2711        return 0;
2712}
2713
2714int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2715                   unsigned char *sha1)
2716{
2717        char hdr[32];
2718        int hdrlen;
2719        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2720        return 0;
2721}
2722
2723/* Finalize a file on disk, and close it. */
2724static void close_sha1_file(int fd)
2725{
2726        if (fsync_object_files)
2727                fsync_or_die(fd, "sha1 file");
2728        if (close(fd) != 0)
2729                die_errno("error when closing sha1 file");
2730}
2731
2732/* Size of directory component, including the ending '/' */
2733static inline int directory_size(const char *filename)
2734{
2735        const char *s = strrchr(filename, '/');
2736        if (!s)
2737                return 0;
2738        return s - filename + 1;
2739}
2740
2741/*
2742 * This creates a temporary file in the same directory as the final
2743 * 'filename'
2744 *
2745 * We want to avoid cross-directory filename renames, because those
2746 * can have problems on various filesystems (FAT, NFS, Coda).
2747 */
2748static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2749{
2750        int fd, dirlen = directory_size(filename);
2751
2752        if (dirlen + 20 > bufsiz) {
2753                errno = ENAMETOOLONG;
2754                return -1;
2755        }
2756        memcpy(buffer, filename, dirlen);
2757        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2758        fd = git_mkstemp_mode(buffer, 0444);
2759        if (fd < 0 && dirlen && errno == ENOENT) {
2760                /* Make sure the directory exists */
2761                memcpy(buffer, filename, dirlen);
2762                buffer[dirlen-1] = 0;
2763                if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2764                        return -1;
2765
2766                /* Try again */
2767                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2768                fd = git_mkstemp_mode(buffer, 0444);
2769        }
2770        return fd;
2771}
2772
2773static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2774                              const void *buf, unsigned long len, time_t mtime)
2775{
2776        int fd, ret;
2777        unsigned char compressed[4096];
2778        git_zstream stream;
2779        git_SHA_CTX c;
2780        unsigned char parano_sha1[20];
2781        char *filename;
2782        static char tmp_file[PATH_MAX];
2783
2784        filename = sha1_file_name(sha1);
2785        fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2786        if (fd < 0) {
2787                if (errno == EACCES)
2788                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
2789                else
2790                        return error("unable to create temporary file: %s", strerror(errno));
2791        }
2792
2793        /* Set it up */
2794        memset(&stream, 0, sizeof(stream));
2795        git_deflate_init(&stream, zlib_compression_level);
2796        stream.next_out = compressed;
2797        stream.avail_out = sizeof(compressed);
2798        git_SHA1_Init(&c);
2799
2800        /* First header.. */
2801        stream.next_in = (unsigned char *)hdr;
2802        stream.avail_in = hdrlen;
2803        while (git_deflate(&stream, 0) == Z_OK)
2804                ; /* nothing */
2805        git_SHA1_Update(&c, hdr, hdrlen);
2806
2807        /* Then the data itself.. */
2808        stream.next_in = (void *)buf;
2809        stream.avail_in = len;
2810        do {
2811                unsigned char *in0 = stream.next_in;
2812                ret = git_deflate(&stream, Z_FINISH);
2813                git_SHA1_Update(&c, in0, stream.next_in - in0);
2814                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2815                        die("unable to write sha1 file");
2816                stream.next_out = compressed;
2817                stream.avail_out = sizeof(compressed);
2818        } while (ret == Z_OK);
2819
2820        if (ret != Z_STREAM_END)
2821                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2822        ret = git_deflate_end_gently(&stream);
2823        if (ret != Z_OK)
2824                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2825        git_SHA1_Final(parano_sha1, &c);
2826        if (hashcmp(sha1, parano_sha1) != 0)
2827                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2828
2829        close_sha1_file(fd);
2830
2831        if (mtime) {
2832                struct utimbuf utb;
2833                utb.actime = mtime;
2834                utb.modtime = mtime;
2835                if (utime(tmp_file, &utb) < 0)
2836                        warning("failed utime() on %s: %s",
2837                                tmp_file, strerror(errno));
2838        }
2839
2840        return move_temp_to_file(tmp_file, filename);
2841}
2842
2843int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2844{
2845        unsigned char sha1[20];
2846        char hdr[32];
2847        int hdrlen;
2848
2849        /* Normally if we have it in the pack then we do not bother writing
2850         * it out into .git/objects/??/?{38} file.
2851         */
2852        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2853        if (returnsha1)
2854                hashcpy(returnsha1, sha1);
2855        if (has_sha1_file(sha1))
2856                return 0;
2857        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2858}
2859
2860int force_object_loose(const unsigned char *sha1, time_t mtime)
2861{
2862        void *buf;
2863        unsigned long len;
2864        enum object_type type;
2865        char hdr[32];
2866        int hdrlen;
2867        int ret;
2868
2869        if (has_loose_object(sha1))
2870                return 0;
2871        buf = read_packed_sha1(sha1, &type, &len);
2872        if (!buf)
2873                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2874        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2875        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2876        free(buf);
2877
2878        return ret;
2879}
2880
2881int has_pack_index(const unsigned char *sha1)
2882{
2883        struct stat st;
2884        if (stat(sha1_pack_index_name(sha1), &st))
2885                return 0;
2886        return 1;
2887}
2888
2889int has_sha1_pack(const unsigned char *sha1)
2890{
2891        struct pack_entry e;
2892        return find_pack_entry(sha1, &e);
2893}
2894
2895int has_sha1_file(const unsigned char *sha1)
2896{
2897        struct pack_entry e;
2898
2899        if (find_pack_entry(sha1, &e))
2900                return 1;
2901        return has_loose_object(sha1);
2902}
2903
2904static void check_tree(const void *buf, size_t size)
2905{
2906        struct tree_desc desc;
2907        struct name_entry entry;
2908
2909        init_tree_desc(&desc, buf, size);
2910        while (tree_entry(&desc, &entry))
2911                /* do nothing
2912                 * tree_entry() will die() on malformed entries */
2913                ;
2914}
2915
2916static void check_commit(const void *buf, size_t size)
2917{
2918        struct commit c;
2919        memset(&c, 0, sizeof(c));
2920        if (parse_commit_buffer(&c, buf, size))
2921                die("corrupt commit");
2922}
2923
2924static void check_tag(const void *buf, size_t size)
2925{
2926        struct tag t;
2927        memset(&t, 0, sizeof(t));
2928        if (parse_tag_buffer(&t, buf, size))
2929                die("corrupt tag");
2930}
2931
2932static int index_mem(unsigned char *sha1, void *buf, size_t size,
2933                     enum object_type type,
2934                     const char *path, unsigned flags)
2935{
2936        int ret, re_allocated = 0;
2937        int write_object = flags & HASH_WRITE_OBJECT;
2938
2939        if (!type)
2940                type = OBJ_BLOB;
2941
2942        /*
2943         * Convert blobs to git internal format
2944         */
2945        if ((type == OBJ_BLOB) && path) {
2946                struct strbuf nbuf = STRBUF_INIT;
2947                if (convert_to_git(path, buf, size, &nbuf,
2948                                   write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
2949                        buf = strbuf_detach(&nbuf, &size);
2950                        re_allocated = 1;
2951                }
2952        }
2953        if (flags & HASH_FORMAT_CHECK) {
2954                if (type == OBJ_TREE)
2955                        check_tree(buf, size);
2956                if (type == OBJ_COMMIT)
2957                        check_commit(buf, size);
2958                if (type == OBJ_TAG)
2959                        check_tag(buf, size);
2960        }
2961
2962        if (write_object)
2963                ret = write_sha1_file(buf, size, typename(type), sha1);
2964        else
2965                ret = hash_sha1_file(buf, size, typename(type), sha1);
2966        if (re_allocated)
2967                free(buf);
2968        return ret;
2969}
2970
2971static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
2972                      const char *path, unsigned flags)
2973{
2974        struct strbuf sbuf = STRBUF_INIT;
2975        int ret;
2976
2977        if (strbuf_read(&sbuf, fd, 4096) >= 0)
2978                ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
2979        else
2980                ret = -1;
2981        strbuf_release(&sbuf);
2982        return ret;
2983}
2984
2985#define SMALL_FILE_SIZE (32*1024)
2986
2987static int index_core(unsigned char *sha1, int fd, size_t size,
2988                      enum object_type type, const char *path,
2989                      unsigned flags)
2990{
2991        int ret;
2992
2993        if (!size) {
2994                ret = index_mem(sha1, NULL, size, type, path, flags);
2995        } else if (size <= SMALL_FILE_SIZE) {
2996                char *buf = xmalloc(size);
2997                if (size == read_in_full(fd, buf, size))
2998                        ret = index_mem(sha1, buf, size, type, path, flags);
2999                else
3000                        ret = error("short read %s", strerror(errno));
3001                free(buf);
3002        } else {
3003                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
3004                ret = index_mem(sha1, buf, size, type, path, flags);
3005                munmap(buf, size);
3006        }
3007        return ret;
3008}
3009
3010/*
3011 * This creates one packfile per large blob unless bulk-checkin
3012 * machinery is "plugged".
3013 *
3014 * This also bypasses the usual "convert-to-git" dance, and that is on
3015 * purpose. We could write a streaming version of the converting
3016 * functions and insert that before feeding the data to fast-import
3017 * (or equivalent in-core API described above). However, that is
3018 * somewhat complicated, as we do not know the size of the filter
3019 * result, which we need to know beforehand when writing a git object.
3020 * Since the primary motivation for trying to stream from the working
3021 * tree file and to avoid mmaping it in core is to deal with large
3022 * binary blobs, they generally do not want to get any conversion, and
3023 * callers should avoid this code path when filters are requested.
3024 */
3025static int index_stream(unsigned char *sha1, int fd, size_t size,
3026                        enum object_type type, const char *path,
3027                        unsigned flags)
3028{
3029        return index_bulk_checkin(sha1, fd, size, type, path, flags);
3030}
3031
3032int index_fd(unsigned char *sha1, int fd, struct stat *st,
3033             enum object_type type, const char *path, unsigned flags)
3034{
3035        int ret;
3036        size_t size = xsize_t(st->st_size);
3037
3038        if (!S_ISREG(st->st_mode))
3039                ret = index_pipe(sha1, fd, type, path, flags);
3040        else if (size <= big_file_threshold || type != OBJ_BLOB ||
3041                 (path && would_convert_to_git(path, NULL, 0, 0)))
3042                ret = index_core(sha1, fd, size, type, path, flags);
3043        else
3044                ret = index_stream(sha1, fd, size, type, path, flags);
3045        close(fd);
3046        return ret;
3047}
3048
3049int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
3050{
3051        int fd;
3052        struct strbuf sb = STRBUF_INIT;
3053
3054        switch (st->st_mode & S_IFMT) {
3055        case S_IFREG:
3056                fd = open(path, O_RDONLY);
3057                if (fd < 0)
3058                        return error("open(\"%s\"): %s", path,
3059                                     strerror(errno));
3060                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
3061                        return error("%s: failed to insert into database",
3062                                     path);
3063                break;
3064        case S_IFLNK:
3065                if (strbuf_readlink(&sb, path, st->st_size)) {
3066                        char *errstr = strerror(errno);
3067                        return error("readlink(\"%s\"): %s", path,
3068                                     errstr);
3069                }
3070                if (!(flags & HASH_WRITE_OBJECT))
3071                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
3072                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
3073                        return error("%s: failed to insert into database",
3074                                     path);
3075                strbuf_release(&sb);
3076                break;
3077        case S_IFDIR:
3078                return resolve_gitlink_ref(path, "HEAD", sha1);
3079        default:
3080                return error("%s: unsupported file type", path);
3081        }
3082        return 0;
3083}
3084
3085int read_pack_header(int fd, struct pack_header *header)
3086{
3087        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
3088                /* "eof before pack header was fully read" */
3089                return PH_ERROR_EOF;
3090
3091        if (header->hdr_signature != htonl(PACK_SIGNATURE))
3092                /* "protocol error (pack signature mismatch detected)" */
3093                return PH_ERROR_PACK_SIGNATURE;
3094        if (!pack_version_ok(header->hdr_version))
3095                /* "protocol error (pack version unsupported)" */
3096                return PH_ERROR_PROTOCOL;
3097        return 0;
3098}
3099
3100void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
3101{
3102        enum object_type type = sha1_object_info(sha1, NULL);
3103        if (type < 0)
3104                die("%s is not a valid object", sha1_to_hex(sha1));
3105        if (type != expect)
3106                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
3107                    typename(expect));
3108}