sha1_file.con commit Merge branch 'maint-1.7.8' into maint (80a3f53)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include "cache.h"
  10#include "delta.h"
  11#include "pack.h"
  12#include "blob.h"
  13#include "commit.h"
  14#include "run-command.h"
  15#include "tag.h"
  16#include "tree.h"
  17#include "tree-walk.h"
  18#include "refs.h"
  19#include "pack-revindex.h"
  20#include "sha1-lookup.h"
  21#include "bulk-checkin.h"
  22
  23#ifndef O_NOATIME
  24#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  25#define O_NOATIME 01000000
  26#else
  27#define O_NOATIME 0
  28#endif
  29#endif
  30
  31#define SZ_FMT PRIuMAX
  32static inline uintmax_t sz_fmt(size_t s) { return s; }
  33
  34const unsigned char null_sha1[20];
  35
  36/*
  37 * This is meant to hold a *small* number of objects that you would
  38 * want read_sha1_file() to be able to return, but yet you do not want
  39 * to write them into the object store (e.g. a browse-only
  40 * application).
  41 */
  42static struct cached_object {
  43        unsigned char sha1[20];
  44        enum object_type type;
  45        void *buf;
  46        unsigned long size;
  47} *cached_objects;
  48static int cached_object_nr, cached_object_alloc;
  49
  50static struct cached_object empty_tree = {
  51        EMPTY_TREE_SHA1_BIN_LITERAL,
  52        OBJ_TREE,
  53        "",
  54        0
  55};
  56
  57static struct packed_git *last_found_pack;
  58
  59static struct cached_object *find_cached_object(const unsigned char *sha1)
  60{
  61        int i;
  62        struct cached_object *co = cached_objects;
  63
  64        for (i = 0; i < cached_object_nr; i++, co++) {
  65                if (!hashcmp(co->sha1, sha1))
  66                        return co;
  67        }
  68        if (!hashcmp(sha1, empty_tree.sha1))
  69                return &empty_tree;
  70        return NULL;
  71}
  72
  73int mkdir_in_gitdir(const char *path)
  74{
  75        if (mkdir(path, 0777)) {
  76                int saved_errno = errno;
  77                struct stat st;
  78                struct strbuf sb = STRBUF_INIT;
  79
  80                if (errno != EEXIST)
  81                        return -1;
  82                /*
  83                 * Are we looking at a path in a symlinked worktree
  84                 * whose original repository does not yet have it?
  85                 * e.g. .git/rr-cache pointing at its original
  86                 * repository in which the user hasn't performed any
  87                 * conflict resolution yet?
  88                 */
  89                if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
  90                    strbuf_readlink(&sb, path, st.st_size) ||
  91                    !is_absolute_path(sb.buf) ||
  92                    mkdir(sb.buf, 0777)) {
  93                        strbuf_release(&sb);
  94                        errno = saved_errno;
  95                        return -1;
  96                }
  97                strbuf_release(&sb);
  98        }
  99        return adjust_shared_perm(path);
 100}
 101
 102int safe_create_leading_directories(char *path)
 103{
 104        char *pos = path + offset_1st_component(path);
 105        struct stat st;
 106
 107        while (pos) {
 108                pos = strchr(pos, '/');
 109                if (!pos)
 110                        break;
 111                while (*++pos == '/')
 112                        ;
 113                if (!*pos)
 114                        break;
 115                *--pos = '\0';
 116                if (!stat(path, &st)) {
 117                        /* path exists */
 118                        if (!S_ISDIR(st.st_mode)) {
 119                                *pos = '/';
 120                                return -3;
 121                        }
 122                }
 123                else if (mkdir(path, 0777)) {
 124                        *pos = '/';
 125                        return -1;
 126                }
 127                else if (adjust_shared_perm(path)) {
 128                        *pos = '/';
 129                        return -2;
 130                }
 131                *pos++ = '/';
 132        }
 133        return 0;
 134}
 135
 136int safe_create_leading_directories_const(const char *path)
 137{
 138        /* path points to cache entries, so xstrdup before messing with it */
 139        char *buf = xstrdup(path);
 140        int result = safe_create_leading_directories(buf);
 141        free(buf);
 142        return result;
 143}
 144
 145static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 146{
 147        int i;
 148        for (i = 0; i < 20; i++) {
 149                static char hex[] = "0123456789abcdef";
 150                unsigned int val = sha1[i];
 151                char *pos = pathbuf + i*2 + (i > 0);
 152                *pos++ = hex[val >> 4];
 153                *pos = hex[val & 0xf];
 154        }
 155}
 156
 157/*
 158 * NOTE! This returns a statically allocated buffer, so you have to be
 159 * careful about using it. Do an "xstrdup()" if you need to save the
 160 * filename.
 161 *
 162 * Also note that this returns the location for creating.  Reading
 163 * SHA1 file can happen from any alternate directory listed in the
 164 * DB_ENVIRONMENT environment variable if it is not found in
 165 * the primary object database.
 166 */
 167char *sha1_file_name(const unsigned char *sha1)
 168{
 169        static char buf[PATH_MAX];
 170        const char *objdir;
 171        int len;
 172
 173        objdir = get_object_directory();
 174        len = strlen(objdir);
 175
 176        /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
 177        if (len + 43 > PATH_MAX)
 178                die("insanely long object directory %s", objdir);
 179        memcpy(buf, objdir, len);
 180        buf[len] = '/';
 181        buf[len+3] = '/';
 182        buf[len+42] = '\0';
 183        fill_sha1_path(buf + len + 1, sha1);
 184        return buf;
 185}
 186
 187static char *sha1_get_pack_name(const unsigned char *sha1,
 188                                char **name, char **base, const char *which)
 189{
 190        static const char hex[] = "0123456789abcdef";
 191        char *buf;
 192        int i;
 193
 194        if (!*base) {
 195                const char *sha1_file_directory = get_object_directory();
 196                int len = strlen(sha1_file_directory);
 197                *base = xmalloc(len + 60);
 198                sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
 199                        sha1_file_directory, which);
 200                *name = *base + len + 11;
 201        }
 202
 203        buf = *name;
 204
 205        for (i = 0; i < 20; i++) {
 206                unsigned int val = *sha1++;
 207                *buf++ = hex[val >> 4];
 208                *buf++ = hex[val & 0xf];
 209        }
 210
 211        return *base;
 212}
 213
 214char *sha1_pack_name(const unsigned char *sha1)
 215{
 216        static char *name, *base;
 217
 218        return sha1_get_pack_name(sha1, &name, &base, "pack");
 219}
 220
 221char *sha1_pack_index_name(const unsigned char *sha1)
 222{
 223        static char *name, *base;
 224
 225        return sha1_get_pack_name(sha1, &name, &base, "idx");
 226}
 227
 228struct alternate_object_database *alt_odb_list;
 229static struct alternate_object_database **alt_odb_tail;
 230
 231static void read_info_alternates(const char * alternates, int depth);
 232static int git_open_noatime(const char *name);
 233
 234/*
 235 * Prepare alternate object database registry.
 236 *
 237 * The variable alt_odb_list points at the list of struct
 238 * alternate_object_database.  The elements on this list come from
 239 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 240 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 241 * whose contents is similar to that environment variable but can be
 242 * LF separated.  Its base points at a statically allocated buffer that
 243 * contains "/the/directory/corresponding/to/.git/objects/...", while
 244 * its name points just after the slash at the end of ".git/objects/"
 245 * in the example above, and has enough space to hold 40-byte hex
 246 * SHA1, an extra slash for the first level indirection, and the
 247 * terminating NUL.
 248 */
 249static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 250{
 251        const char *objdir = get_object_directory();
 252        struct alternate_object_database *ent;
 253        struct alternate_object_database *alt;
 254        int pfxlen, entlen;
 255        struct strbuf pathbuf = STRBUF_INIT;
 256
 257        if (!is_absolute_path(entry) && relative_base) {
 258                strbuf_addstr(&pathbuf, real_path(relative_base));
 259                strbuf_addch(&pathbuf, '/');
 260        }
 261        strbuf_add(&pathbuf, entry, len);
 262
 263        normalize_path_copy(pathbuf.buf, pathbuf.buf);
 264
 265        pfxlen = strlen(pathbuf.buf);
 266
 267        /*
 268         * The trailing slash after the directory name is given by
 269         * this function at the end. Remove duplicates.
 270         */
 271        while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
 272                pfxlen -= 1;
 273
 274        entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
 275        ent = xmalloc(sizeof(*ent) + entlen);
 276        memcpy(ent->base, pathbuf.buf, pfxlen);
 277        strbuf_release(&pathbuf);
 278
 279        ent->name = ent->base + pfxlen + 1;
 280        ent->base[pfxlen + 3] = '/';
 281        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 282
 283        /* Detect cases where alternate disappeared */
 284        if (!is_directory(ent->base)) {
 285                error("object directory %s does not exist; "
 286                      "check .git/objects/info/alternates.",
 287                      ent->base);
 288                free(ent);
 289                return -1;
 290        }
 291
 292        /* Prevent the common mistake of listing the same
 293         * thing twice, or object directory itself.
 294         */
 295        for (alt = alt_odb_list; alt; alt = alt->next) {
 296                if (!memcmp(ent->base, alt->base, pfxlen)) {
 297                        free(ent);
 298                        return -1;
 299                }
 300        }
 301        if (!memcmp(ent->base, objdir, pfxlen)) {
 302                free(ent);
 303                return -1;
 304        }
 305
 306        /* add the alternate entry */
 307        *alt_odb_tail = ent;
 308        alt_odb_tail = &(ent->next);
 309        ent->next = NULL;
 310
 311        /* recursively add alternates */
 312        read_info_alternates(ent->base, depth + 1);
 313
 314        ent->base[pfxlen] = '/';
 315
 316        return 0;
 317}
 318
 319static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 320                                 const char *relative_base, int depth)
 321{
 322        const char *cp, *last;
 323
 324        if (depth > 5) {
 325                error("%s: ignoring alternate object stores, nesting too deep.",
 326                                relative_base);
 327                return;
 328        }
 329
 330        last = alt;
 331        while (last < ep) {
 332                cp = last;
 333                if (cp < ep && *cp == '#') {
 334                        while (cp < ep && *cp != sep)
 335                                cp++;
 336                        last = cp + 1;
 337                        continue;
 338                }
 339                while (cp < ep && *cp != sep)
 340                        cp++;
 341                if (last != cp) {
 342                        if (!is_absolute_path(last) && depth) {
 343                                error("%s: ignoring relative alternate object store %s",
 344                                                relative_base, last);
 345                        } else {
 346                                link_alt_odb_entry(last, cp - last,
 347                                                relative_base, depth);
 348                        }
 349                }
 350                while (cp < ep && *cp == sep)
 351                        cp++;
 352                last = cp;
 353        }
 354}
 355
 356static void 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, 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, 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, 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
 734/*
 735 * Do not call this directly as this leaks p->pack_fd on error return;
 736 * call open_packed_git() instead.
 737 */
 738static int open_packed_git_1(struct packed_git *p)
 739{
 740        struct stat st;
 741        struct pack_header hdr;
 742        unsigned char sha1[20];
 743        unsigned char *idx_sha1;
 744        long fd_flag;
 745
 746        if (!p->index_data && open_pack_index(p))
 747                return error("packfile %s index unavailable", p->pack_name);
 748
 749        if (!pack_max_fds) {
 750                struct rlimit lim;
 751                unsigned int max_fds;
 752
 753                if (getrlimit(RLIMIT_NOFILE, &lim))
 754                        die_errno("cannot get RLIMIT_NOFILE");
 755
 756                max_fds = lim.rlim_cur;
 757
 758                /* Save 3 for stdin/stdout/stderr, 22 for work */
 759                if (25 < max_fds)
 760                        pack_max_fds = max_fds - 25;
 761                else
 762                        pack_max_fds = 1;
 763        }
 764
 765        while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
 766                ; /* nothing */
 767
 768        p->pack_fd = git_open_noatime(p->pack_name);
 769        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 770                return -1;
 771        pack_open_fds++;
 772
 773        /* If we created the struct before we had the pack we lack size. */
 774        if (!p->pack_size) {
 775                if (!S_ISREG(st.st_mode))
 776                        return error("packfile %s not a regular file", p->pack_name);
 777                p->pack_size = st.st_size;
 778        } else if (p->pack_size != st.st_size)
 779                return error("packfile %s size changed", p->pack_name);
 780
 781        /* We leave these file descriptors open with sliding mmap;
 782         * there is no point keeping them open across exec(), though.
 783         */
 784        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 785        if (fd_flag < 0)
 786                return error("cannot determine file descriptor flags");
 787        fd_flag |= FD_CLOEXEC;
 788        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 789                return error("cannot set FD_CLOEXEC");
 790
 791        /* Verify we recognize this pack file format. */
 792        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 793                return error("file %s is far too short to be a packfile", p->pack_name);
 794        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 795                return error("file %s is not a GIT packfile", p->pack_name);
 796        if (!pack_version_ok(hdr.hdr_version))
 797                return error("packfile %s is version %"PRIu32" and not"
 798                        " supported (try upgrading GIT to a newer version)",
 799                        p->pack_name, ntohl(hdr.hdr_version));
 800
 801        /* Verify the pack matches its index. */
 802        if (p->num_objects != ntohl(hdr.hdr_entries))
 803                return error("packfile %s claims to have %"PRIu32" objects"
 804                             " while index indicates %"PRIu32" objects",
 805                             p->pack_name, ntohl(hdr.hdr_entries),
 806                             p->num_objects);
 807        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 808                return error("end of packfile %s is unavailable", p->pack_name);
 809        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 810                return error("packfile %s signature is unavailable", p->pack_name);
 811        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 812        if (hashcmp(sha1, idx_sha1))
 813                return error("packfile %s does not match index", p->pack_name);
 814        return 0;
 815}
 816
 817static int open_packed_git(struct packed_git *p)
 818{
 819        if (!open_packed_git_1(p))
 820                return 0;
 821        if (p->pack_fd != -1) {
 822                close(p->pack_fd);
 823                pack_open_fds--;
 824                p->pack_fd = -1;
 825        }
 826        return -1;
 827}
 828
 829static int in_window(struct pack_window *win, off_t offset)
 830{
 831        /* We must promise at least 20 bytes (one hash) after the
 832         * offset is available from this window, otherwise the offset
 833         * is not actually in this window and a different window (which
 834         * has that one hash excess) must be used.  This is to support
 835         * the object header and delta base parsing routines below.
 836         */
 837        off_t win_off = win->offset;
 838        return win_off <= offset
 839                && (offset + 20) <= (win_off + win->len);
 840}
 841
 842unsigned char *use_pack(struct packed_git *p,
 843                struct pack_window **w_cursor,
 844                off_t offset,
 845                unsigned long *left)
 846{
 847        struct pack_window *win = *w_cursor;
 848
 849        /* Since packfiles end in a hash of their content and it's
 850         * pointless to ask for an offset into the middle of that
 851         * hash, and the in_window function above wouldn't match
 852         * don't allow an offset too close to the end of the file.
 853         */
 854        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 855                die("packfile %s cannot be accessed", p->pack_name);
 856        if (offset > (p->pack_size - 20))
 857                die("offset beyond end of packfile (truncated pack?)");
 858
 859        if (!win || !in_window(win, offset)) {
 860                if (win)
 861                        win->inuse_cnt--;
 862                for (win = p->windows; win; win = win->next) {
 863                        if (in_window(win, offset))
 864                                break;
 865                }
 866                if (!win) {
 867                        size_t window_align = packed_git_window_size / 2;
 868                        off_t len;
 869
 870                        if (p->pack_fd == -1 && open_packed_git(p))
 871                                die("packfile %s cannot be accessed", p->pack_name);
 872
 873                        win = xcalloc(1, sizeof(*win));
 874                        win->offset = (offset / window_align) * window_align;
 875                        len = p->pack_size - win->offset;
 876                        if (len > packed_git_window_size)
 877                                len = packed_git_window_size;
 878                        win->len = (size_t)len;
 879                        pack_mapped += win->len;
 880                        while (packed_git_limit < pack_mapped
 881                                && unuse_one_window(p, p->pack_fd))
 882                                ; /* nothing */
 883                        win->base = xmmap(NULL, win->len,
 884                                PROT_READ, MAP_PRIVATE,
 885                                p->pack_fd, win->offset);
 886                        if (win->base == MAP_FAILED)
 887                                die("packfile %s cannot be mapped: %s",
 888                                        p->pack_name,
 889                                        strerror(errno));
 890                        if (!win->offset && win->len == p->pack_size
 891                                && !p->do_not_close) {
 892                                close(p->pack_fd);
 893                                pack_open_fds--;
 894                                p->pack_fd = -1;
 895                        }
 896                        pack_mmap_calls++;
 897                        pack_open_windows++;
 898                        if (pack_mapped > peak_pack_mapped)
 899                                peak_pack_mapped = pack_mapped;
 900                        if (pack_open_windows > peak_pack_open_windows)
 901                                peak_pack_open_windows = pack_open_windows;
 902                        win->next = p->windows;
 903                        p->windows = win;
 904                }
 905        }
 906        if (win != *w_cursor) {
 907                win->last_used = pack_used_ctr++;
 908                win->inuse_cnt++;
 909                *w_cursor = win;
 910        }
 911        offset -= win->offset;
 912        if (left)
 913                *left = win->len - xsize_t(offset);
 914        return win->base + offset;
 915}
 916
 917static struct packed_git *alloc_packed_git(int extra)
 918{
 919        struct packed_git *p = xmalloc(sizeof(*p) + extra);
 920        memset(p, 0, sizeof(*p));
 921        p->pack_fd = -1;
 922        return p;
 923}
 924
 925static void try_to_free_pack_memory(size_t size)
 926{
 927        release_pack_memory(size, -1);
 928}
 929
 930struct packed_git *add_packed_git(const char *path, int path_len, int local)
 931{
 932        static int have_set_try_to_free_routine;
 933        struct stat st;
 934        struct packed_git *p = alloc_packed_git(path_len + 2);
 935
 936        if (!have_set_try_to_free_routine) {
 937                have_set_try_to_free_routine = 1;
 938                set_try_to_free_routine(try_to_free_pack_memory);
 939        }
 940
 941        /*
 942         * Make sure a corresponding .pack file exists and that
 943         * the index looks sane.
 944         */
 945        path_len -= strlen(".idx");
 946        if (path_len < 1) {
 947                free(p);
 948                return NULL;
 949        }
 950        memcpy(p->pack_name, path, path_len);
 951
 952        strcpy(p->pack_name + path_len, ".keep");
 953        if (!access(p->pack_name, F_OK))
 954                p->pack_keep = 1;
 955
 956        strcpy(p->pack_name + path_len, ".pack");
 957        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 958                free(p);
 959                return NULL;
 960        }
 961
 962        /* ok, it looks sane as far as we can check without
 963         * actually mapping the pack file.
 964         */
 965        p->pack_size = st.st_size;
 966        p->pack_local = local;
 967        p->mtime = st.st_mtime;
 968        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 969                hashclr(p->sha1);
 970        return p;
 971}
 972
 973struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 974{
 975        const char *path = sha1_pack_name(sha1);
 976        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 977
 978        strcpy(p->pack_name, path);
 979        hashcpy(p->sha1, sha1);
 980        if (check_packed_git_idx(idx_path, p)) {
 981                free(p);
 982                return NULL;
 983        }
 984
 985        return p;
 986}
 987
 988void install_packed_git(struct packed_git *pack)
 989{
 990        if (pack->pack_fd != -1)
 991                pack_open_fds++;
 992
 993        pack->next = packed_git;
 994        packed_git = pack;
 995}
 996
 997static void prepare_packed_git_one(char *objdir, int local)
 998{
 999        /* Ensure that this buffer is large enough so that we can
1000           append "/pack/" without clobbering the stack even if
1001           strlen(objdir) were PATH_MAX.  */
1002        char path[PATH_MAX + 1 + 4 + 1 + 1];
1003        int len;
1004        DIR *dir;
1005        struct dirent *de;
1006
1007        sprintf(path, "%s/pack", objdir);
1008        len = strlen(path);
1009        dir = opendir(path);
1010        if (!dir) {
1011                if (errno != ENOENT)
1012                        error("unable to open object pack directory: %s: %s",
1013                              path, strerror(errno));
1014                return;
1015        }
1016        path[len++] = '/';
1017        while ((de = readdir(dir)) != NULL) {
1018                int namelen = strlen(de->d_name);
1019                struct packed_git *p;
1020
1021                if (!has_extension(de->d_name, ".idx"))
1022                        continue;
1023
1024                if (len + namelen + 1 > sizeof(path))
1025                        continue;
1026
1027                /* Don't reopen a pack we already have. */
1028                strcpy(path + len, de->d_name);
1029                for (p = packed_git; p; p = p->next) {
1030                        if (!memcmp(path, p->pack_name, len + namelen - 4))
1031                                break;
1032                }
1033                if (p)
1034                        continue;
1035                /* See if it really is a valid .idx file with corresponding
1036                 * .pack file that we can map.
1037                 */
1038                p = add_packed_git(path, len + namelen, local);
1039                if (!p)
1040                        continue;
1041                install_packed_git(p);
1042        }
1043        closedir(dir);
1044}
1045
1046static int sort_pack(const void *a_, const void *b_)
1047{
1048        struct packed_git *a = *((struct packed_git **)a_);
1049        struct packed_git *b = *((struct packed_git **)b_);
1050        int st;
1051
1052        /*
1053         * Local packs tend to contain objects specific to our
1054         * variant of the project than remote ones.  In addition,
1055         * remote ones could be on a network mounted filesystem.
1056         * Favor local ones for these reasons.
1057         */
1058        st = a->pack_local - b->pack_local;
1059        if (st)
1060                return -st;
1061
1062        /*
1063         * Younger packs tend to contain more recent objects,
1064         * and more recent objects tend to get accessed more
1065         * often.
1066         */
1067        if (a->mtime < b->mtime)
1068                return 1;
1069        else if (a->mtime == b->mtime)
1070                return 0;
1071        return -1;
1072}
1073
1074static void rearrange_packed_git(void)
1075{
1076        struct packed_git **ary, *p;
1077        int i, n;
1078
1079        for (n = 0, p = packed_git; p; p = p->next)
1080                n++;
1081        if (n < 2)
1082                return;
1083
1084        /* prepare an array of packed_git for easier sorting */
1085        ary = xcalloc(n, sizeof(struct packed_git *));
1086        for (n = 0, p = packed_git; p; p = p->next)
1087                ary[n++] = p;
1088
1089        qsort(ary, n, sizeof(struct packed_git *), sort_pack);
1090
1091        /* link them back again */
1092        for (i = 0; i < n - 1; i++)
1093                ary[i]->next = ary[i + 1];
1094        ary[n - 1]->next = NULL;
1095        packed_git = ary[0];
1096
1097        free(ary);
1098}
1099
1100static int prepare_packed_git_run_once = 0;
1101void prepare_packed_git(void)
1102{
1103        struct alternate_object_database *alt;
1104
1105        if (prepare_packed_git_run_once)
1106                return;
1107        prepare_packed_git_one(get_object_directory(), 1);
1108        prepare_alt_odb();
1109        for (alt = alt_odb_list; alt; alt = alt->next) {
1110                alt->name[-1] = 0;
1111                prepare_packed_git_one(alt->base, 0);
1112                alt->name[-1] = '/';
1113        }
1114        rearrange_packed_git();
1115        prepare_packed_git_run_once = 1;
1116}
1117
1118void reprepare_packed_git(void)
1119{
1120        discard_revindex();
1121        prepare_packed_git_run_once = 0;
1122        prepare_packed_git();
1123}
1124
1125static void mark_bad_packed_object(struct packed_git *p,
1126                                   const unsigned char *sha1)
1127{
1128        unsigned i;
1129        for (i = 0; i < p->num_bad_objects; i++)
1130                if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1131                        return;
1132        p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
1133        hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
1134        p->num_bad_objects++;
1135}
1136
1137static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1138{
1139        struct packed_git *p;
1140        unsigned i;
1141
1142        for (p = packed_git; p; p = p->next)
1143                for (i = 0; i < p->num_bad_objects; i++)
1144                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1145                                return p;
1146        return NULL;
1147}
1148
1149int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
1150{
1151        unsigned char real_sha1[20];
1152        hash_sha1_file(map, size, type, real_sha1);
1153        return hashcmp(sha1, real_sha1) ? -1 : 0;
1154}
1155
1156static int git_open_noatime(const char *name)
1157{
1158        static int sha1_file_open_flag = O_NOATIME;
1159
1160        for (;;) {
1161                int fd = open(name, O_RDONLY | sha1_file_open_flag);
1162                if (fd >= 0)
1163                        return fd;
1164
1165                /* Might the failure be due to O_NOATIME? */
1166                if (errno != ENOENT && sha1_file_open_flag) {
1167                        sha1_file_open_flag = 0;
1168                        continue;
1169                }
1170
1171                return -1;
1172        }
1173}
1174
1175static int open_sha1_file(const unsigned char *sha1)
1176{
1177        int fd;
1178        char *name = sha1_file_name(sha1);
1179        struct alternate_object_database *alt;
1180
1181        fd = git_open_noatime(name);
1182        if (fd >= 0)
1183                return fd;
1184
1185        prepare_alt_odb();
1186        errno = ENOENT;
1187        for (alt = alt_odb_list; alt; alt = alt->next) {
1188                name = alt->name;
1189                fill_sha1_path(name, sha1);
1190                fd = git_open_noatime(alt->base);
1191                if (fd >= 0)
1192                        return fd;
1193        }
1194        return -1;
1195}
1196
1197void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
1198{
1199        void *map;
1200        int fd;
1201
1202        fd = open_sha1_file(sha1);
1203        map = NULL;
1204        if (fd >= 0) {
1205                struct stat st;
1206
1207                if (!fstat(fd, &st)) {
1208                        *size = xsize_t(st.st_size);
1209                        if (!*size) {
1210                                /* mmap() is forbidden on empty files */
1211                                error("object file %s is empty", sha1_file_name(sha1));
1212                                return NULL;
1213                        }
1214                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
1215                }
1216                close(fd);
1217        }
1218        return map;
1219}
1220
1221/*
1222 * There used to be a second loose object header format which
1223 * was meant to mimic the in-pack format, allowing for direct
1224 * copy of the object data.  This format turned up not to be
1225 * really worth it and we no longer write loose objects in that
1226 * format.
1227 */
1228static int experimental_loose_object(unsigned char *map)
1229{
1230        unsigned int word;
1231
1232        /*
1233         * We must determine if the buffer contains the standard
1234         * zlib-deflated stream or the experimental format based
1235         * on the in-pack object format. Compare the header byte
1236         * for each format:
1237         *
1238         * RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
1239         * Experimental pack-based : Stttssss : ttt = 1,2,3,4
1240         *
1241         * If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
1242         * in standard loose-object format, UNLESS it is a Git-pack
1243         * format object *exactly* 8 bytes in size when inflated.
1244         *
1245         * However, RFC1950 also specifies that the 1st 16-bit word
1246         * must be divisible by 31 - this checksum tells us our buffer
1247         * is in the standard format, giving a false positive only if
1248         * the 1st word of the Git-pack format object happens to be
1249         * divisible by 31, ie:
1250         *      ((byte0 * 256) + byte1) % 31 = 0
1251         *   =>        0ttt10000www1000 % 31 = 0
1252         *
1253         * As it happens, this case can only arise for www=3 & ttt=1
1254         * - ie, a Commit object, which would have to be 8 bytes in
1255         * size. As no Commit can be that small, we find that the
1256         * combination of these two criteria (bitmask & checksum)
1257         * can always correctly determine the buffer format.
1258         */
1259        word = (map[0] << 8) + map[1];
1260        if ((map[0] & 0x8F) == 0x08 && !(word % 31))
1261                return 0;
1262        else
1263                return 1;
1264}
1265
1266unsigned long unpack_object_header_buffer(const unsigned char *buf,
1267                unsigned long len, enum object_type *type, unsigned long *sizep)
1268{
1269        unsigned shift;
1270        unsigned long size, c;
1271        unsigned long used = 0;
1272
1273        c = buf[used++];
1274        *type = (c >> 4) & 7;
1275        size = c & 15;
1276        shift = 4;
1277        while (c & 0x80) {
1278                if (len <= used || bitsizeof(long) <= shift) {
1279                        error("bad object header");
1280                        size = used = 0;
1281                        break;
1282                }
1283                c = buf[used++];
1284                size += (c & 0x7f) << shift;
1285                shift += 7;
1286        }
1287        *sizep = size;
1288        return used;
1289}
1290
1291int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
1292{
1293        unsigned long size, used;
1294        static const char valid_loose_object_type[8] = {
1295                0, /* OBJ_EXT */
1296                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
1297                0, /* "delta" and others are invalid in a loose object */
1298        };
1299        enum object_type type;
1300
1301        /* Get the data stream */
1302        memset(stream, 0, sizeof(*stream));
1303        stream->next_in = map;
1304        stream->avail_in = mapsize;
1305        stream->next_out = buffer;
1306        stream->avail_out = bufsiz;
1307
1308        if (experimental_loose_object(map)) {
1309                /*
1310                 * The old experimental format we no longer produce;
1311                 * we can still read it.
1312                 */
1313                used = unpack_object_header_buffer(map, mapsize, &type, &size);
1314                if (!used || !valid_loose_object_type[type])
1315                        return -1;
1316                map += used;
1317                mapsize -= used;
1318
1319                /* Set up the stream for the rest.. */
1320                stream->next_in = map;
1321                stream->avail_in = mapsize;
1322                git_inflate_init(stream);
1323
1324                /* And generate the fake traditional header */
1325                stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
1326                                                 typename(type), size);
1327                return 0;
1328        }
1329        git_inflate_init(stream);
1330        return git_inflate(stream, 0);
1331}
1332
1333static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
1334{
1335        int bytes = strlen(buffer) + 1;
1336        unsigned char *buf = xmallocz(size);
1337        unsigned long n;
1338        int status = Z_OK;
1339
1340        n = stream->total_out - bytes;
1341        if (n > size)
1342                n = size;
1343        memcpy(buf, (char *) buffer + bytes, n);
1344        bytes = n;
1345        if (bytes <= size) {
1346                /*
1347                 * The above condition must be (bytes <= size), not
1348                 * (bytes < size).  In other words, even though we
1349                 * expect no more output and set avail_out to zero,
1350                 * the input zlib stream may have bytes that express
1351                 * "this concludes the stream", and we *do* want to
1352                 * eat that input.
1353                 *
1354                 * Otherwise we would not be able to test that we
1355                 * consumed all the input to reach the expected size;
1356                 * we also want to check that zlib tells us that all
1357                 * went well with status == Z_STREAM_END at the end.
1358                 */
1359                stream->next_out = buf + bytes;
1360                stream->avail_out = size - bytes;
1361                while (status == Z_OK)
1362                        status = git_inflate(stream, Z_FINISH);
1363        }
1364        if (status == Z_STREAM_END && !stream->avail_in) {
1365                git_inflate_end(stream);
1366                return buf;
1367        }
1368
1369        if (status < 0)
1370                error("corrupt loose object '%s'", sha1_to_hex(sha1));
1371        else if (stream->avail_in)
1372                error("garbage at end of loose object '%s'",
1373                      sha1_to_hex(sha1));
1374        free(buf);
1375        return NULL;
1376}
1377
1378/*
1379 * We used to just use "sscanf()", but that's actually way
1380 * too permissive for what we want to check. So do an anal
1381 * object header parse by hand.
1382 */
1383int parse_sha1_header(const char *hdr, unsigned long *sizep)
1384{
1385        char type[10];
1386        int i;
1387        unsigned long size;
1388
1389        /*
1390         * The type can be at most ten bytes (including the
1391         * terminating '\0' that we add), and is followed by
1392         * a space.
1393         */
1394        i = 0;
1395        for (;;) {
1396                char c = *hdr++;
1397                if (c == ' ')
1398                        break;
1399                type[i++] = c;
1400                if (i >= sizeof(type))
1401                        return -1;
1402        }
1403        type[i] = 0;
1404
1405        /*
1406         * The length must follow immediately, and be in canonical
1407         * decimal format (ie "010" is not valid).
1408         */
1409        size = *hdr++ - '0';
1410        if (size > 9)
1411                return -1;
1412        if (size) {
1413                for (;;) {
1414                        unsigned long c = *hdr - '0';
1415                        if (c > 9)
1416                                break;
1417                        hdr++;
1418                        size = size * 10 + c;
1419                }
1420        }
1421        *sizep = size;
1422
1423        /*
1424         * The length must be followed by a zero byte
1425         */
1426        return *hdr ? -1 : type_from_string(type);
1427}
1428
1429static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1430{
1431        int ret;
1432        git_zstream stream;
1433        char hdr[8192];
1434
1435        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1436        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1437                return NULL;
1438
1439        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1440}
1441
1442unsigned long get_size_from_delta(struct packed_git *p,
1443                                  struct pack_window **w_curs,
1444                                  off_t curpos)
1445{
1446        const unsigned char *data;
1447        unsigned char delta_head[20], *in;
1448        git_zstream stream;
1449        int st;
1450
1451        memset(&stream, 0, sizeof(stream));
1452        stream.next_out = delta_head;
1453        stream.avail_out = sizeof(delta_head);
1454
1455        git_inflate_init(&stream);
1456        do {
1457                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1458                stream.next_in = in;
1459                st = git_inflate(&stream, Z_FINISH);
1460                curpos += stream.next_in - in;
1461        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1462                 stream.total_out < sizeof(delta_head));
1463        git_inflate_end(&stream);
1464        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1465                error("delta data unpack-initial failed");
1466                return 0;
1467        }
1468
1469        /* Examine the initial part of the delta to figure out
1470         * the result size.
1471         */
1472        data = delta_head;
1473
1474        /* ignore base size */
1475        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1476
1477        /* Read the result size */
1478        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1479}
1480
1481static off_t get_delta_base(struct packed_git *p,
1482                                    struct pack_window **w_curs,
1483                                    off_t *curpos,
1484                                    enum object_type type,
1485                                    off_t delta_obj_offset)
1486{
1487        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1488        off_t base_offset;
1489
1490        /* use_pack() assured us we have [base_info, base_info + 20)
1491         * as a range that we can look at without walking off the
1492         * end of the mapped window.  Its actually the hash size
1493         * that is assured.  An OFS_DELTA longer than the hash size
1494         * is stupid, as then a REF_DELTA would be smaller to store.
1495         */
1496        if (type == OBJ_OFS_DELTA) {
1497                unsigned used = 0;
1498                unsigned char c = base_info[used++];
1499                base_offset = c & 127;
1500                while (c & 128) {
1501                        base_offset += 1;
1502                        if (!base_offset || MSB(base_offset, 7))
1503                                return 0;  /* overflow */
1504                        c = base_info[used++];
1505                        base_offset = (base_offset << 7) + (c & 127);
1506                }
1507                base_offset = delta_obj_offset - base_offset;
1508                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1509                        return 0;  /* out of bound */
1510                *curpos += used;
1511        } else if (type == OBJ_REF_DELTA) {
1512                /* The base entry _must_ be in the same pack */
1513                base_offset = find_pack_entry_one(base_info, p);
1514                *curpos += 20;
1515        } else
1516                die("I am totally screwed");
1517        return base_offset;
1518}
1519
1520/* forward declaration for a mutually recursive function */
1521static int packed_object_info(struct packed_git *p, off_t offset,
1522                              unsigned long *sizep, int *rtype);
1523
1524static int packed_delta_info(struct packed_git *p,
1525                             struct pack_window **w_curs,
1526                             off_t curpos,
1527                             enum object_type type,
1528                             off_t obj_offset,
1529                             unsigned long *sizep)
1530{
1531        off_t base_offset;
1532
1533        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1534        if (!base_offset)
1535                return OBJ_BAD;
1536        type = packed_object_info(p, base_offset, NULL, NULL);
1537        if (type <= OBJ_NONE) {
1538                struct revindex_entry *revidx;
1539                const unsigned char *base_sha1;
1540                revidx = find_pack_revindex(p, base_offset);
1541                if (!revidx)
1542                        return OBJ_BAD;
1543                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1544                mark_bad_packed_object(p, base_sha1);
1545                type = sha1_object_info(base_sha1, NULL);
1546                if (type <= OBJ_NONE)
1547                        return OBJ_BAD;
1548        }
1549
1550        /* We choose to only get the type of the base object and
1551         * ignore potentially corrupt pack file that expects the delta
1552         * based on a base with a wrong size.  This saves tons of
1553         * inflate() calls.
1554         */
1555        if (sizep) {
1556                *sizep = get_size_from_delta(p, w_curs, curpos);
1557                if (*sizep == 0)
1558                        type = OBJ_BAD;
1559        }
1560
1561        return type;
1562}
1563
1564int unpack_object_header(struct packed_git *p,
1565                         struct pack_window **w_curs,
1566                         off_t *curpos,
1567                         unsigned long *sizep)
1568{
1569        unsigned char *base;
1570        unsigned long left;
1571        unsigned long used;
1572        enum object_type type;
1573
1574        /* use_pack() assures us we have [base, base + 20) available
1575         * as a range that we can look at.  (Its actually the hash
1576         * size that is assured.)  With our object header encoding
1577         * the maximum deflated object size is 2^137, which is just
1578         * insane, so we know won't exceed what we have been given.
1579         */
1580        base = use_pack(p, w_curs, *curpos, &left);
1581        used = unpack_object_header_buffer(base, left, &type, sizep);
1582        if (!used) {
1583                type = OBJ_BAD;
1584        } else
1585                *curpos += used;
1586
1587        return type;
1588}
1589
1590static int packed_object_info(struct packed_git *p, off_t obj_offset,
1591                              unsigned long *sizep, int *rtype)
1592{
1593        struct pack_window *w_curs = NULL;
1594        unsigned long size;
1595        off_t curpos = obj_offset;
1596        enum object_type type;
1597
1598        type = unpack_object_header(p, &w_curs, &curpos, &size);
1599        if (rtype)
1600                *rtype = type; /* representation type */
1601
1602        switch (type) {
1603        case OBJ_OFS_DELTA:
1604        case OBJ_REF_DELTA:
1605                type = packed_delta_info(p, &w_curs, curpos,
1606                                         type, obj_offset, sizep);
1607                break;
1608        case OBJ_COMMIT:
1609        case OBJ_TREE:
1610        case OBJ_BLOB:
1611        case OBJ_TAG:
1612                if (sizep)
1613                        *sizep = size;
1614                break;
1615        default:
1616                error("unknown object type %i at offset %"PRIuMAX" in %s",
1617                      type, (uintmax_t)obj_offset, p->pack_name);
1618                type = OBJ_BAD;
1619        }
1620        unuse_pack(&w_curs);
1621        return type;
1622}
1623
1624static void *unpack_compressed_entry(struct packed_git *p,
1625                                    struct pack_window **w_curs,
1626                                    off_t curpos,
1627                                    unsigned long size)
1628{
1629        int st;
1630        git_zstream stream;
1631        unsigned char *buffer, *in;
1632
1633        buffer = xmallocz(size);
1634        memset(&stream, 0, sizeof(stream));
1635        stream.next_out = buffer;
1636        stream.avail_out = size + 1;
1637
1638        git_inflate_init(&stream);
1639        do {
1640                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1641                stream.next_in = in;
1642                st = git_inflate(&stream, Z_FINISH);
1643                if (!stream.avail_out)
1644                        break; /* the payload is larger than it should be */
1645                curpos += stream.next_in - in;
1646        } while (st == Z_OK || st == Z_BUF_ERROR);
1647        git_inflate_end(&stream);
1648        if ((st != Z_STREAM_END) || stream.total_out != size) {
1649                free(buffer);
1650                return NULL;
1651        }
1652
1653        return buffer;
1654}
1655
1656#define MAX_DELTA_CACHE (256)
1657
1658static size_t delta_base_cached;
1659
1660static struct delta_base_cache_lru_list {
1661        struct delta_base_cache_lru_list *prev;
1662        struct delta_base_cache_lru_list *next;
1663} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
1664
1665static struct delta_base_cache_entry {
1666        struct delta_base_cache_lru_list lru;
1667        void *data;
1668        struct packed_git *p;
1669        off_t base_offset;
1670        unsigned long size;
1671        enum object_type type;
1672} delta_base_cache[MAX_DELTA_CACHE];
1673
1674static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
1675{
1676        unsigned long hash;
1677
1678        hash = (unsigned long)p + (unsigned long)base_offset;
1679        hash += (hash >> 8) + (hash >> 16);
1680        return hash % MAX_DELTA_CACHE;
1681}
1682
1683static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1684{
1685        unsigned long hash = pack_entry_hash(p, base_offset);
1686        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1687        return (ent->data && ent->p == p && ent->base_offset == base_offset);
1688}
1689
1690static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
1691        unsigned long *base_size, enum object_type *type, int keep_cache)
1692{
1693        void *ret;
1694        unsigned long hash = pack_entry_hash(p, base_offset);
1695        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1696
1697        ret = ent->data;
1698        if (!ret || ent->p != p || ent->base_offset != base_offset)
1699                return unpack_entry(p, base_offset, type, base_size);
1700
1701        if (!keep_cache) {
1702                ent->data = NULL;
1703                ent->lru.next->prev = ent->lru.prev;
1704                ent->lru.prev->next = ent->lru.next;
1705                delta_base_cached -= ent->size;
1706        } else {
1707                ret = xmemdupz(ent->data, ent->size);
1708        }
1709        *type = ent->type;
1710        *base_size = ent->size;
1711        return ret;
1712}
1713
1714static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1715{
1716        if (ent->data) {
1717                free(ent->data);
1718                ent->data = NULL;
1719                ent->lru.next->prev = ent->lru.prev;
1720                ent->lru.prev->next = ent->lru.next;
1721                delta_base_cached -= ent->size;
1722        }
1723}
1724
1725void clear_delta_base_cache(void)
1726{
1727        unsigned long p;
1728        for (p = 0; p < MAX_DELTA_CACHE; p++)
1729                release_delta_base_cache(&delta_base_cache[p]);
1730}
1731
1732static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1733        void *base, unsigned long base_size, enum object_type type)
1734{
1735        unsigned long hash = pack_entry_hash(p, base_offset);
1736        struct delta_base_cache_entry *ent = delta_base_cache + hash;
1737        struct delta_base_cache_lru_list *lru;
1738
1739        release_delta_base_cache(ent);
1740        delta_base_cached += base_size;
1741
1742        for (lru = delta_base_cache_lru.next;
1743             delta_base_cached > delta_base_cache_limit
1744             && lru != &delta_base_cache_lru;
1745             lru = lru->next) {
1746                struct delta_base_cache_entry *f = (void *)lru;
1747                if (f->type == OBJ_BLOB)
1748                        release_delta_base_cache(f);
1749        }
1750        for (lru = delta_base_cache_lru.next;
1751             delta_base_cached > delta_base_cache_limit
1752             && lru != &delta_base_cache_lru;
1753             lru = lru->next) {
1754                struct delta_base_cache_entry *f = (void *)lru;
1755                release_delta_base_cache(f);
1756        }
1757
1758        ent->p = p;
1759        ent->base_offset = base_offset;
1760        ent->type = type;
1761        ent->data = base;
1762        ent->size = base_size;
1763        ent->lru.next = &delta_base_cache_lru;
1764        ent->lru.prev = delta_base_cache_lru.prev;
1765        delta_base_cache_lru.prev->next = &ent->lru;
1766        delta_base_cache_lru.prev = &ent->lru;
1767}
1768
1769static void *read_object(const unsigned char *sha1, enum object_type *type,
1770                         unsigned long *size);
1771
1772static void *unpack_delta_entry(struct packed_git *p,
1773                                struct pack_window **w_curs,
1774                                off_t curpos,
1775                                unsigned long delta_size,
1776                                off_t obj_offset,
1777                                enum object_type *type,
1778                                unsigned long *sizep)
1779{
1780        void *delta_data, *result, *base;
1781        unsigned long base_size;
1782        off_t base_offset;
1783
1784        base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1785        if (!base_offset) {
1786                error("failed to validate delta base reference "
1787                      "at offset %"PRIuMAX" from %s",
1788                      (uintmax_t)curpos, p->pack_name);
1789                return NULL;
1790        }
1791        unuse_pack(w_curs);
1792        base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
1793        if (!base) {
1794                /*
1795                 * We're probably in deep shit, but let's try to fetch
1796                 * the required base anyway from another pack or loose.
1797                 * This is costly but should happen only in the presence
1798                 * of a corrupted pack, and is better than failing outright.
1799                 */
1800                struct revindex_entry *revidx;
1801                const unsigned char *base_sha1;
1802                revidx = find_pack_revindex(p, base_offset);
1803                if (!revidx)
1804                        return NULL;
1805                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
1806                error("failed to read delta base object %s"
1807                      " at offset %"PRIuMAX" from %s",
1808                      sha1_to_hex(base_sha1), (uintmax_t)base_offset,
1809                      p->pack_name);
1810                mark_bad_packed_object(p, base_sha1);
1811                base = read_object(base_sha1, type, &base_size);
1812                if (!base)
1813                        return NULL;
1814        }
1815
1816        delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1817        if (!delta_data) {
1818                error("failed to unpack compressed delta "
1819                      "at offset %"PRIuMAX" from %s",
1820                      (uintmax_t)curpos, p->pack_name);
1821                free(base);
1822                return NULL;
1823        }
1824        result = patch_delta(base, base_size,
1825                             delta_data, delta_size,
1826                             sizep);
1827        if (!result)
1828                die("failed to apply delta");
1829        free(delta_data);
1830        add_delta_base_cache(p, base_offset, base, base_size, *type);
1831        return result;
1832}
1833
1834static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1835{
1836        static FILE *log_file;
1837
1838        if (!log_file) {
1839                log_file = fopen(log_pack_access, "w");
1840                if (!log_file) {
1841                        error("cannot open pack access log '%s' for writing: %s",
1842                              log_pack_access, strerror(errno));
1843                        log_pack_access = NULL;
1844                        return;
1845                }
1846        }
1847        fprintf(log_file, "%s %"PRIuMAX"\n",
1848                p->pack_name, (uintmax_t)obj_offset);
1849        fflush(log_file);
1850}
1851
1852int do_check_packed_object_crc;
1853
1854void *unpack_entry(struct packed_git *p, off_t obj_offset,
1855                   enum object_type *type, unsigned long *sizep)
1856{
1857        struct pack_window *w_curs = NULL;
1858        off_t curpos = obj_offset;
1859        void *data;
1860
1861        if (log_pack_access)
1862                write_pack_access_log(p, obj_offset);
1863
1864        if (do_check_packed_object_crc && p->index_version > 1) {
1865                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1866                unsigned long len = revidx[1].offset - obj_offset;
1867                if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1868                        const unsigned char *sha1 =
1869                                nth_packed_object_sha1(p, revidx->nr);
1870                        error("bad packed object CRC for %s",
1871                              sha1_to_hex(sha1));
1872                        mark_bad_packed_object(p, sha1);
1873                        unuse_pack(&w_curs);
1874                        return NULL;
1875                }
1876        }
1877
1878        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1879        switch (*type) {
1880        case OBJ_OFS_DELTA:
1881        case OBJ_REF_DELTA:
1882                data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1883                                          obj_offset, type, sizep);
1884                break;
1885        case OBJ_COMMIT:
1886        case OBJ_TREE:
1887        case OBJ_BLOB:
1888        case OBJ_TAG:
1889                data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1890                break;
1891        default:
1892                data = NULL;
1893                error("unknown object type %i at offset %"PRIuMAX" in %s",
1894                      *type, (uintmax_t)obj_offset, p->pack_name);
1895        }
1896        unuse_pack(&w_curs);
1897        return data;
1898}
1899
1900const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1901                                            uint32_t n)
1902{
1903        const unsigned char *index = p->index_data;
1904        if (!index) {
1905                if (open_pack_index(p))
1906                        return NULL;
1907                index = p->index_data;
1908        }
1909        if (n >= p->num_objects)
1910                return NULL;
1911        index += 4 * 256;
1912        if (p->index_version == 1) {
1913                return index + 24 * n + 4;
1914        } else {
1915                index += 8;
1916                return index + 20 * n;
1917        }
1918}
1919
1920off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1921{
1922        const unsigned char *index = p->index_data;
1923        index += 4 * 256;
1924        if (p->index_version == 1) {
1925                return ntohl(*((uint32_t *)(index + 24 * n)));
1926        } else {
1927                uint32_t off;
1928                index += 8 + p->num_objects * (20 + 4);
1929                off = ntohl(*((uint32_t *)(index + 4 * n)));
1930                if (!(off & 0x80000000))
1931                        return off;
1932                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1933                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
1934                                   ntohl(*((uint32_t *)(index + 4)));
1935        }
1936}
1937
1938off_t find_pack_entry_one(const unsigned char *sha1,
1939                                  struct packed_git *p)
1940{
1941        const uint32_t *level1_ofs = p->index_data;
1942        const unsigned char *index = p->index_data;
1943        unsigned hi, lo, stride;
1944        static int use_lookup = -1;
1945        static int debug_lookup = -1;
1946
1947        if (debug_lookup < 0)
1948                debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
1949
1950        if (!index) {
1951                if (open_pack_index(p))
1952                        return 0;
1953                level1_ofs = p->index_data;
1954                index = p->index_data;
1955        }
1956        if (p->index_version > 1) {
1957                level1_ofs += 2;
1958                index += 8;
1959        }
1960        index += 4 * 256;
1961        hi = ntohl(level1_ofs[*sha1]);
1962        lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1963        if (p->index_version > 1) {
1964                stride = 20;
1965        } else {
1966                stride = 24;
1967                index += 4;
1968        }
1969
1970        if (debug_lookup)
1971                printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
1972                       sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
1973
1974        if (use_lookup < 0)
1975                use_lookup = !!getenv("GIT_USE_LOOKUP");
1976        if (use_lookup) {
1977                int pos = sha1_entry_pos(index, stride, 0,
1978                                         lo, hi, p->num_objects, sha1);
1979                if (pos < 0)
1980                        return 0;
1981                return nth_packed_object_offset(p, pos);
1982        }
1983
1984        do {
1985                unsigned mi = (lo + hi) / 2;
1986                int cmp = hashcmp(index + mi * stride, sha1);
1987
1988                if (debug_lookup)
1989                        printf("lo %u hi %u rg %u mi %u\n",
1990                               lo, hi, hi - lo, mi);
1991                if (!cmp)
1992                        return nth_packed_object_offset(p, mi);
1993                if (cmp > 0)
1994                        hi = mi;
1995                else
1996                        lo = mi+1;
1997        } while (lo < hi);
1998        return 0;
1999}
2000
2001int is_pack_valid(struct packed_git *p)
2002{
2003        /* An already open pack is known to be valid. */
2004        if (p->pack_fd != -1)
2005                return 1;
2006
2007        /* If the pack has one window completely covering the
2008         * file size, the pack is known to be valid even if
2009         * the descriptor is not currently open.
2010         */
2011        if (p->windows) {
2012                struct pack_window *w = p->windows;
2013
2014                if (!w->offset && w->len == p->pack_size)
2015                        return 1;
2016        }
2017
2018        /* Force the pack to open to prove its valid. */
2019        return !open_packed_git(p);
2020}
2021
2022static int fill_pack_entry(const unsigned char *sha1,
2023                           struct pack_entry *e,
2024                           struct packed_git *p)
2025{
2026        off_t offset;
2027
2028        if (p->num_bad_objects) {
2029                unsigned i;
2030                for (i = 0; i < p->num_bad_objects; i++)
2031                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
2032                                return 0;
2033        }
2034
2035        offset = find_pack_entry_one(sha1, p);
2036        if (!offset)
2037                return 0;
2038
2039        /*
2040         * We are about to tell the caller where they can locate the
2041         * requested object.  We better make sure the packfile is
2042         * still here and can be accessed before supplying that
2043         * answer, as it may have been deleted since the index was
2044         * loaded!
2045         */
2046        if (!is_pack_valid(p)) {
2047                warning("packfile %s cannot be accessed", p->pack_name);
2048                return 0;
2049        }
2050        e->offset = offset;
2051        e->p = p;
2052        hashcpy(e->sha1, sha1);
2053        return 1;
2054}
2055
2056static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
2057{
2058        struct packed_git *p;
2059
2060        prepare_packed_git();
2061        if (!packed_git)
2062                return 0;
2063
2064        if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
2065                return 1;
2066
2067        for (p = packed_git; p; p = p->next) {
2068                if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
2069                        continue;
2070
2071                last_found_pack = p;
2072                return 1;
2073        }
2074        return 0;
2075}
2076
2077struct packed_git *find_sha1_pack(const unsigned char *sha1,
2078                                  struct packed_git *packs)
2079{
2080        struct packed_git *p;
2081
2082        for (p = packs; p; p = p->next) {
2083                if (find_pack_entry_one(sha1, p))
2084                        return p;
2085        }
2086        return NULL;
2087
2088}
2089
2090static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
2091{
2092        int status;
2093        unsigned long mapsize, size;
2094        void *map;
2095        git_zstream stream;
2096        char hdr[32];
2097
2098        map = map_sha1_file(sha1, &mapsize);
2099        if (!map)
2100                return error("unable to find %s", sha1_to_hex(sha1));
2101        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
2102                status = error("unable to unpack %s header",
2103                               sha1_to_hex(sha1));
2104        else if ((status = parse_sha1_header(hdr, &size)) < 0)
2105                status = error("unable to parse %s header", sha1_to_hex(sha1));
2106        else if (sizep)
2107                *sizep = size;
2108        git_inflate_end(&stream);
2109        munmap(map, mapsize);
2110        return status;
2111}
2112
2113/* returns enum object_type or negative */
2114int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
2115{
2116        struct cached_object *co;
2117        struct pack_entry e;
2118        int status, rtype;
2119
2120        co = find_cached_object(sha1);
2121        if (co) {
2122                if (oi->sizep)
2123                        *(oi->sizep) = co->size;
2124                oi->whence = OI_CACHED;
2125                return co->type;
2126        }
2127
2128        if (!find_pack_entry(sha1, &e)) {
2129                /* Most likely it's a loose object. */
2130                status = sha1_loose_object_info(sha1, oi->sizep);
2131                if (status >= 0) {
2132                        oi->whence = OI_LOOSE;
2133                        return status;
2134                }
2135
2136                /* Not a loose object; someone else may have just packed it. */
2137                reprepare_packed_git();
2138                if (!find_pack_entry(sha1, &e))
2139                        return status;
2140        }
2141
2142        status = packed_object_info(e.p, e.offset, oi->sizep, &rtype);
2143        if (status < 0) {
2144                mark_bad_packed_object(e.p, sha1);
2145                status = sha1_object_info_extended(sha1, oi);
2146        } else if (in_delta_base_cache(e.p, e.offset)) {
2147                oi->whence = OI_DBCACHED;
2148        } else {
2149                oi->whence = OI_PACKED;
2150                oi->u.packed.offset = e.offset;
2151                oi->u.packed.pack = e.p;
2152                oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
2153                                         rtype == OBJ_OFS_DELTA);
2154        }
2155
2156        return status;
2157}
2158
2159int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
2160{
2161        struct object_info oi;
2162
2163        oi.sizep = sizep;
2164        return sha1_object_info_extended(sha1, &oi);
2165}
2166
2167static void *read_packed_sha1(const unsigned char *sha1,
2168                              enum object_type *type, unsigned long *size)
2169{
2170        struct pack_entry e;
2171        void *data;
2172
2173        if (!find_pack_entry(sha1, &e))
2174                return NULL;
2175        data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
2176        if (!data) {
2177                /*
2178                 * We're probably in deep shit, but let's try to fetch
2179                 * the required object anyway from another pack or loose.
2180                 * This should happen only in the presence of a corrupted
2181                 * pack, and is better than failing outright.
2182                 */
2183                error("failed to read object %s at offset %"PRIuMAX" from %s",
2184                      sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
2185                mark_bad_packed_object(e.p, sha1);
2186                data = read_object(sha1, type, size);
2187        }
2188        return data;
2189}
2190
2191int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
2192                      unsigned char *sha1)
2193{
2194        struct cached_object *co;
2195
2196        hash_sha1_file(buf, len, typename(type), sha1);
2197        if (has_sha1_file(sha1) || find_cached_object(sha1))
2198                return 0;
2199        if (cached_object_alloc <= cached_object_nr) {
2200                cached_object_alloc = alloc_nr(cached_object_alloc);
2201                cached_objects = xrealloc(cached_objects,
2202                                          sizeof(*cached_objects) *
2203                                          cached_object_alloc);
2204        }
2205        co = &cached_objects[cached_object_nr++];
2206        co->size = len;
2207        co->type = type;
2208        co->buf = xmalloc(len);
2209        memcpy(co->buf, buf, len);
2210        hashcpy(co->sha1, sha1);
2211        return 0;
2212}
2213
2214static void *read_object(const unsigned char *sha1, enum object_type *type,
2215                         unsigned long *size)
2216{
2217        unsigned long mapsize;
2218        void *map, *buf;
2219        struct cached_object *co;
2220
2221        co = find_cached_object(sha1);
2222        if (co) {
2223                *type = co->type;
2224                *size = co->size;
2225                return xmemdupz(co->buf, co->size);
2226        }
2227
2228        buf = read_packed_sha1(sha1, type, size);
2229        if (buf)
2230                return buf;
2231        map = map_sha1_file(sha1, &mapsize);
2232        if (map) {
2233                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
2234                munmap(map, mapsize);
2235                return buf;
2236        }
2237        reprepare_packed_git();
2238        return read_packed_sha1(sha1, type, size);
2239}
2240
2241/*
2242 * This function dies on corrupt objects; the callers who want to
2243 * deal with them should arrange to call read_object() and give error
2244 * messages themselves.
2245 */
2246void *read_sha1_file_extended(const unsigned char *sha1,
2247                              enum object_type *type,
2248                              unsigned long *size,
2249                              unsigned flag)
2250{
2251        void *data;
2252        char *path;
2253        const struct packed_git *p;
2254        const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
2255                ? lookup_replace_object(sha1) : sha1;
2256
2257        errno = 0;
2258        data = read_object(repl, type, size);
2259        if (data)
2260                return data;
2261
2262        if (errno && errno != ENOENT)
2263                die_errno("failed to read object %s", sha1_to_hex(sha1));
2264
2265        /* die if we replaced an object with one that does not exist */
2266        if (repl != sha1)
2267                die("replacement %s not found for %s",
2268                    sha1_to_hex(repl), sha1_to_hex(sha1));
2269
2270        if (has_loose_object(repl)) {
2271                path = sha1_file_name(sha1);
2272                die("loose object %s (stored in %s) is corrupt",
2273                    sha1_to_hex(repl), path);
2274        }
2275
2276        if ((p = has_packed_and_bad(repl)) != NULL)
2277                die("packed object %s (stored in %s) is corrupt",
2278                    sha1_to_hex(repl), p->pack_name);
2279
2280        return NULL;
2281}
2282
2283void *read_object_with_reference(const unsigned char *sha1,
2284                                 const char *required_type_name,
2285                                 unsigned long *size,
2286                                 unsigned char *actual_sha1_return)
2287{
2288        enum object_type type, required_type;
2289        void *buffer;
2290        unsigned long isize;
2291        unsigned char actual_sha1[20];
2292
2293        required_type = type_from_string(required_type_name);
2294        hashcpy(actual_sha1, sha1);
2295        while (1) {
2296                int ref_length = -1;
2297                const char *ref_type = NULL;
2298
2299                buffer = read_sha1_file(actual_sha1, &type, &isize);
2300                if (!buffer)
2301                        return NULL;
2302                if (type == required_type) {
2303                        *size = isize;
2304                        if (actual_sha1_return)
2305                                hashcpy(actual_sha1_return, actual_sha1);
2306                        return buffer;
2307                }
2308                /* Handle references */
2309                else if (type == OBJ_COMMIT)
2310                        ref_type = "tree ";
2311                else if (type == OBJ_TAG)
2312                        ref_type = "object ";
2313                else {
2314                        free(buffer);
2315                        return NULL;
2316                }
2317                ref_length = strlen(ref_type);
2318
2319                if (ref_length + 40 > isize ||
2320                    memcmp(buffer, ref_type, ref_length) ||
2321                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
2322                        free(buffer);
2323                        return NULL;
2324                }
2325                free(buffer);
2326                /* Now we have the ID of the referred-to object in
2327                 * actual_sha1.  Check again. */
2328        }
2329}
2330
2331static void write_sha1_file_prepare(const void *buf, unsigned long len,
2332                                    const char *type, unsigned char *sha1,
2333                                    char *hdr, int *hdrlen)
2334{
2335        git_SHA_CTX c;
2336
2337        /* Generate the header */
2338        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
2339
2340        /* Sha1.. */
2341        git_SHA1_Init(&c);
2342        git_SHA1_Update(&c, hdr, *hdrlen);
2343        git_SHA1_Update(&c, buf, len);
2344        git_SHA1_Final(sha1, &c);
2345}
2346
2347/*
2348 * Move the just written object into its final resting place.
2349 * NEEDSWORK: this should be renamed to finalize_temp_file() as
2350 * "moving" is only a part of what it does, when no patch between
2351 * master to pu changes the call sites of this function.
2352 */
2353int move_temp_to_file(const char *tmpfile, const char *filename)
2354{
2355        int ret = 0;
2356
2357        if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
2358                goto try_rename;
2359        else if (link(tmpfile, filename))
2360                ret = errno;
2361
2362        /*
2363         * Coda hack - coda doesn't like cross-directory links,
2364         * so we fall back to a rename, which will mean that it
2365         * won't be able to check collisions, but that's not a
2366         * big deal.
2367         *
2368         * The same holds for FAT formatted media.
2369         *
2370         * When this succeeds, we just return.  We have nothing
2371         * left to unlink.
2372         */
2373        if (ret && ret != EEXIST) {
2374        try_rename:
2375                if (!rename(tmpfile, filename))
2376                        goto out;
2377                ret = errno;
2378        }
2379        unlink_or_warn(tmpfile);
2380        if (ret) {
2381                if (ret != EEXIST) {
2382                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
2383                }
2384                /* FIXME!!! Collision check here ? */
2385        }
2386
2387out:
2388        if (adjust_shared_perm(filename))
2389                return error("unable to set permission to '%s'", filename);
2390        return 0;
2391}
2392
2393static int write_buffer(int fd, const void *buf, size_t len)
2394{
2395        if (write_in_full(fd, buf, len) < 0)
2396                return error("file write error (%s)", strerror(errno));
2397        return 0;
2398}
2399
2400int hash_sha1_file(const void *buf, unsigned long len, const char *type,
2401                   unsigned char *sha1)
2402{
2403        char hdr[32];
2404        int hdrlen;
2405        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2406        return 0;
2407}
2408
2409/* Finalize a file on disk, and close it. */
2410static void close_sha1_file(int fd)
2411{
2412        if (fsync_object_files)
2413                fsync_or_die(fd, "sha1 file");
2414        if (close(fd) != 0)
2415                die_errno("error when closing sha1 file");
2416}
2417
2418/* Size of directory component, including the ending '/' */
2419static inline int directory_size(const char *filename)
2420{
2421        const char *s = strrchr(filename, '/');
2422        if (!s)
2423                return 0;
2424        return s - filename + 1;
2425}
2426
2427/*
2428 * This creates a temporary file in the same directory as the final
2429 * 'filename'
2430 *
2431 * We want to avoid cross-directory filename renames, because those
2432 * can have problems on various filesystems (FAT, NFS, Coda).
2433 */
2434static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
2435{
2436        int fd, dirlen = directory_size(filename);
2437
2438        if (dirlen + 20 > bufsiz) {
2439                errno = ENAMETOOLONG;
2440                return -1;
2441        }
2442        memcpy(buffer, filename, dirlen);
2443        strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
2444        fd = git_mkstemp_mode(buffer, 0444);
2445        if (fd < 0 && dirlen && errno == ENOENT) {
2446                /* Make sure the directory exists */
2447                memcpy(buffer, filename, dirlen);
2448                buffer[dirlen-1] = 0;
2449                if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
2450                        return -1;
2451
2452                /* Try again */
2453                strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
2454                fd = git_mkstemp_mode(buffer, 0444);
2455        }
2456        return fd;
2457}
2458
2459static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
2460                              const void *buf, unsigned long len, time_t mtime)
2461{
2462        int fd, ret;
2463        unsigned char compressed[4096];
2464        git_zstream stream;
2465        git_SHA_CTX c;
2466        unsigned char parano_sha1[20];
2467        char *filename;
2468        static char tmp_file[PATH_MAX];
2469
2470        filename = sha1_file_name(sha1);
2471        fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
2472        if (fd < 0) {
2473                if (errno == EACCES)
2474                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
2475                else
2476                        return error("unable to create temporary sha1 filename %s: %s\n", tmp_file, strerror(errno));
2477        }
2478
2479        /* Set it up */
2480        memset(&stream, 0, sizeof(stream));
2481        git_deflate_init(&stream, zlib_compression_level);
2482        stream.next_out = compressed;
2483        stream.avail_out = sizeof(compressed);
2484        git_SHA1_Init(&c);
2485
2486        /* First header.. */
2487        stream.next_in = (unsigned char *)hdr;
2488        stream.avail_in = hdrlen;
2489        while (git_deflate(&stream, 0) == Z_OK)
2490                ; /* nothing */
2491        git_SHA1_Update(&c, hdr, hdrlen);
2492
2493        /* Then the data itself.. */
2494        stream.next_in = (void *)buf;
2495        stream.avail_in = len;
2496        do {
2497                unsigned char *in0 = stream.next_in;
2498                ret = git_deflate(&stream, Z_FINISH);
2499                git_SHA1_Update(&c, in0, stream.next_in - in0);
2500                if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
2501                        die("unable to write sha1 file");
2502                stream.next_out = compressed;
2503                stream.avail_out = sizeof(compressed);
2504        } while (ret == Z_OK);
2505
2506        if (ret != Z_STREAM_END)
2507                die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
2508        ret = git_deflate_end_gently(&stream);
2509        if (ret != Z_OK)
2510                die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
2511        git_SHA1_Final(parano_sha1, &c);
2512        if (hashcmp(sha1, parano_sha1) != 0)
2513                die("confused by unstable object source data for %s", sha1_to_hex(sha1));
2514
2515        close_sha1_file(fd);
2516
2517        if (mtime) {
2518                struct utimbuf utb;
2519                utb.actime = mtime;
2520                utb.modtime = mtime;
2521                if (utime(tmp_file, &utb) < 0)
2522                        warning("failed utime() on %s: %s",
2523                                tmp_file, strerror(errno));
2524        }
2525
2526        return move_temp_to_file(tmp_file, filename);
2527}
2528
2529int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
2530{
2531        unsigned char sha1[20];
2532        char hdr[32];
2533        int hdrlen;
2534
2535        /* Normally if we have it in the pack then we do not bother writing
2536         * it out into .git/objects/??/?{38} file.
2537         */
2538        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
2539        if (returnsha1)
2540                hashcpy(returnsha1, sha1);
2541        if (has_sha1_file(sha1))
2542                return 0;
2543        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
2544}
2545
2546int force_object_loose(const unsigned char *sha1, time_t mtime)
2547{
2548        void *buf;
2549        unsigned long len;
2550        enum object_type type;
2551        char hdr[32];
2552        int hdrlen;
2553        int ret;
2554
2555        if (has_loose_object(sha1))
2556                return 0;
2557        buf = read_packed_sha1(sha1, &type, &len);
2558        if (!buf)
2559                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
2560        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
2561        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
2562        free(buf);
2563
2564        return ret;
2565}
2566
2567int has_pack_index(const unsigned char *sha1)
2568{
2569        struct stat st;
2570        if (stat(sha1_pack_index_name(sha1), &st))
2571                return 0;
2572        return 1;
2573}
2574
2575int has_sha1_pack(const unsigned char *sha1)
2576{
2577        struct pack_entry e;
2578        return find_pack_entry(sha1, &e);
2579}
2580
2581int has_sha1_file(const unsigned char *sha1)
2582{
2583        struct pack_entry e;
2584
2585        if (find_pack_entry(sha1, &e))
2586                return 1;
2587        return has_loose_object(sha1);
2588}
2589
2590static void check_tree(const void *buf, size_t size)
2591{
2592        struct tree_desc desc;
2593        struct name_entry entry;
2594
2595        init_tree_desc(&desc, buf, size);
2596        while (tree_entry(&desc, &entry))
2597                /* do nothing
2598                 * tree_entry() will die() on malformed entries */
2599                ;
2600}
2601
2602static void check_commit(const void *buf, size_t size)
2603{
2604        struct commit c;
2605        memset(&c, 0, sizeof(c));
2606        if (parse_commit_buffer(&c, buf, size))
2607                die("corrupt commit");
2608}
2609
2610static void check_tag(const void *buf, size_t size)
2611{
2612        struct tag t;
2613        memset(&t, 0, sizeof(t));
2614        if (parse_tag_buffer(&t, buf, size))
2615                die("corrupt tag");
2616}
2617
2618static int index_mem(unsigned char *sha1, void *buf, size_t size,
2619                     enum object_type type,
2620                     const char *path, unsigned flags)
2621{
2622        int ret, re_allocated = 0;
2623        int write_object = flags & HASH_WRITE_OBJECT;
2624
2625        if (!type)
2626                type = OBJ_BLOB;
2627
2628        /*
2629         * Convert blobs to git internal format
2630         */
2631        if ((type == OBJ_BLOB) && path) {
2632                struct strbuf nbuf = STRBUF_INIT;
2633                if (convert_to_git(path, buf, size, &nbuf,
2634                                   write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
2635                        buf = strbuf_detach(&nbuf, &size);
2636                        re_allocated = 1;
2637                }
2638        }
2639        if (flags & HASH_FORMAT_CHECK) {
2640                if (type == OBJ_TREE)
2641                        check_tree(buf, size);
2642                if (type == OBJ_COMMIT)
2643                        check_commit(buf, size);
2644                if (type == OBJ_TAG)
2645                        check_tag(buf, size);
2646        }
2647
2648        if (write_object)
2649                ret = write_sha1_file(buf, size, typename(type), sha1);
2650        else
2651                ret = hash_sha1_file(buf, size, typename(type), sha1);
2652        if (re_allocated)
2653                free(buf);
2654        return ret;
2655}
2656
2657static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
2658                      const char *path, unsigned flags)
2659{
2660        struct strbuf sbuf = STRBUF_INIT;
2661        int ret;
2662
2663        if (strbuf_read(&sbuf, fd, 4096) >= 0)
2664                ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
2665        else
2666                ret = -1;
2667        strbuf_release(&sbuf);
2668        return ret;
2669}
2670
2671#define SMALL_FILE_SIZE (32*1024)
2672
2673static int index_core(unsigned char *sha1, int fd, size_t size,
2674                      enum object_type type, const char *path,
2675                      unsigned flags)
2676{
2677        int ret;
2678
2679        if (!size) {
2680                ret = index_mem(sha1, NULL, size, type, path, flags);
2681        } else if (size <= SMALL_FILE_SIZE) {
2682                char *buf = xmalloc(size);
2683                if (size == read_in_full(fd, buf, size))
2684                        ret = index_mem(sha1, buf, size, type, path, flags);
2685                else
2686                        ret = error("short read %s", strerror(errno));
2687                free(buf);
2688        } else {
2689                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2690                ret = index_mem(sha1, buf, size, type, path, flags);
2691                munmap(buf, size);
2692        }
2693        return ret;
2694}
2695
2696/*
2697 * This creates one packfile per large blob unless bulk-checkin
2698 * machinery is "plugged".
2699 *
2700 * This also bypasses the usual "convert-to-git" dance, and that is on
2701 * purpose. We could write a streaming version of the converting
2702 * functions and insert that before feeding the data to fast-import
2703 * (or equivalent in-core API described above). However, that is
2704 * somewhat complicated, as we do not know the size of the filter
2705 * result, which we need to know beforehand when writing a git object.
2706 * Since the primary motivation for trying to stream from the working
2707 * tree file and to avoid mmaping it in core is to deal with large
2708 * binary blobs, they generally do not want to get any conversion, and
2709 * callers should avoid this code path when filters are requested.
2710 */
2711static int index_stream(unsigned char *sha1, int fd, size_t size,
2712                        enum object_type type, const char *path,
2713                        unsigned flags)
2714{
2715        return index_bulk_checkin(sha1, fd, size, type, path, flags);
2716}
2717
2718int index_fd(unsigned char *sha1, int fd, struct stat *st,
2719             enum object_type type, const char *path, unsigned flags)
2720{
2721        int ret;
2722        size_t size = xsize_t(st->st_size);
2723
2724        if (!S_ISREG(st->st_mode))
2725                ret = index_pipe(sha1, fd, type, path, flags);
2726        else if (size <= big_file_threshold || type != OBJ_BLOB ||
2727                 (path && would_convert_to_git(path, NULL, 0, 0)))
2728                ret = index_core(sha1, fd, size, type, path, flags);
2729        else
2730                ret = index_stream(sha1, fd, size, type, path, flags);
2731        close(fd);
2732        return ret;
2733}
2734
2735int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
2736{
2737        int fd;
2738        struct strbuf sb = STRBUF_INIT;
2739
2740        switch (st->st_mode & S_IFMT) {
2741        case S_IFREG:
2742                fd = open(path, O_RDONLY);
2743                if (fd < 0)
2744                        return error("open(\"%s\"): %s", path,
2745                                     strerror(errno));
2746                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
2747                        return error("%s: failed to insert into database",
2748                                     path);
2749                break;
2750        case S_IFLNK:
2751                if (strbuf_readlink(&sb, path, st->st_size)) {
2752                        char *errstr = strerror(errno);
2753                        return error("readlink(\"%s\"): %s", path,
2754                                     errstr);
2755                }
2756                if (!(flags & HASH_WRITE_OBJECT))
2757                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
2758                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
2759                        return error("%s: failed to insert into database",
2760                                     path);
2761                strbuf_release(&sb);
2762                break;
2763        case S_IFDIR:
2764                return resolve_gitlink_ref(path, "HEAD", sha1);
2765        default:
2766                return error("%s: unsupported file type", path);
2767        }
2768        return 0;
2769}
2770
2771int read_pack_header(int fd, struct pack_header *header)
2772{
2773        if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
2774                /* "eof before pack header was fully read" */
2775                return PH_ERROR_EOF;
2776
2777        if (header->hdr_signature != htonl(PACK_SIGNATURE))
2778                /* "protocol error (pack signature mismatch detected)" */
2779                return PH_ERROR_PACK_SIGNATURE;
2780        if (!pack_version_ok(header->hdr_version))
2781                /* "protocol error (pack version unsupported)" */
2782                return PH_ERROR_PROTOCOL;
2783        return 0;
2784}
2785
2786void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
2787{
2788        enum object_type type = sha1_object_info(sha1, NULL);
2789        if (type < 0)
2790                die("%s is not a valid object", sha1_to_hex(sha1));
2791        if (type != expect)
2792                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
2793                    typename(expect));
2794}