packfile.con commit Merge branch 'bc/asciidoctor-tab-width' (d7e9611)
   1#include "cache.h"
   2#include "list.h"
   3#include "pack.h"
   4#include "repository.h"
   5#include "dir.h"
   6#include "mergesort.h"
   7#include "packfile.h"
   8#include "delta.h"
   9#include "list.h"
  10#include "streaming.h"
  11#include "sha1-lookup.h"
  12#include "commit.h"
  13#include "object.h"
  14#include "tag.h"
  15#include "tree-walk.h"
  16#include "tree.h"
  17#include "object-store.h"
  18
  19char *odb_pack_name(struct strbuf *buf,
  20                    const unsigned char *sha1,
  21                    const char *ext)
  22{
  23        strbuf_reset(buf);
  24        strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
  25                    sha1_to_hex(sha1), ext);
  26        return buf->buf;
  27}
  28
  29char *sha1_pack_name(const unsigned char *sha1)
  30{
  31        static struct strbuf buf = STRBUF_INIT;
  32        return odb_pack_name(&buf, sha1, "pack");
  33}
  34
  35char *sha1_pack_index_name(const unsigned char *sha1)
  36{
  37        static struct strbuf buf = STRBUF_INIT;
  38        return odb_pack_name(&buf, sha1, "idx");
  39}
  40
  41static unsigned int pack_used_ctr;
  42static unsigned int pack_mmap_calls;
  43static unsigned int peak_pack_open_windows;
  44static unsigned int pack_open_windows;
  45static unsigned int pack_open_fds;
  46static unsigned int pack_max_fds;
  47static size_t peak_pack_mapped;
  48static size_t pack_mapped;
  49
  50#define SZ_FMT PRIuMAX
  51static inline uintmax_t sz_fmt(size_t s) { return s; }
  52
  53void pack_report(void)
  54{
  55        fprintf(stderr,
  56                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
  57                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
  58                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
  59                sz_fmt(getpagesize()),
  60                sz_fmt(packed_git_window_size),
  61                sz_fmt(packed_git_limit));
  62        fprintf(stderr,
  63                "pack_report: pack_used_ctr            = %10u\n"
  64                "pack_report: pack_mmap_calls          = %10u\n"
  65                "pack_report: pack_open_windows        = %10u / %10u\n"
  66                "pack_report: pack_mapped              = "
  67                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
  68                pack_used_ctr,
  69                pack_mmap_calls,
  70                pack_open_windows, peak_pack_open_windows,
  71                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
  72}
  73
  74/*
  75 * Open and mmap the index file at path, perform a couple of
  76 * consistency checks, then record its information to p.  Return 0 on
  77 * success.
  78 */
  79static int check_packed_git_idx(const char *path, struct packed_git *p)
  80{
  81        void *idx_map;
  82        struct pack_idx_header *hdr;
  83        size_t idx_size;
  84        uint32_t version, nr, i, *index;
  85        int fd = git_open(path);
  86        struct stat st;
  87
  88        if (fd < 0)
  89                return -1;
  90        if (fstat(fd, &st)) {
  91                close(fd);
  92                return -1;
  93        }
  94        idx_size = xsize_t(st.st_size);
  95        if (idx_size < 4 * 256 + 20 + 20) {
  96                close(fd);
  97                return error("index file %s is too small", path);
  98        }
  99        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 100        close(fd);
 101
 102        hdr = idx_map;
 103        if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 104                version = ntohl(hdr->idx_version);
 105                if (version < 2 || version > 2) {
 106                        munmap(idx_map, idx_size);
 107                        return error("index file %s is version %"PRIu32
 108                                     " and is not supported by this binary"
 109                                     " (try upgrading GIT to a newer version)",
 110                                     path, version);
 111                }
 112        } else
 113                version = 1;
 114
 115        nr = 0;
 116        index = idx_map;
 117        if (version > 1)
 118                index += 2;  /* skip index header */
 119        for (i = 0; i < 256; i++) {
 120                uint32_t n = ntohl(index[i]);
 121                if (n < nr) {
 122                        munmap(idx_map, idx_size);
 123                        return error("non-monotonic index %s", path);
 124                }
 125                nr = n;
 126        }
 127
 128        if (version == 1) {
 129                /*
 130                 * Total size:
 131                 *  - 256 index entries 4 bytes each
 132                 *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 133                 *  - 20-byte SHA1 of the packfile
 134                 *  - 20-byte SHA1 file checksum
 135                 */
 136                if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 137                        munmap(idx_map, idx_size);
 138                        return error("wrong index v1 file size in %s", path);
 139                }
 140        } else if (version == 2) {
 141                /*
 142                 * Minimum size:
 143                 *  - 8 bytes of header
 144                 *  - 256 index entries 4 bytes each
 145                 *  - 20-byte sha1 entry * nr
 146                 *  - 4-byte crc entry * nr
 147                 *  - 4-byte offset entry * nr
 148                 *  - 20-byte SHA1 of the packfile
 149                 *  - 20-byte SHA1 file checksum
 150                 * And after the 4-byte offset table might be a
 151                 * variable sized table containing 8-byte entries
 152                 * for offsets larger than 2^31.
 153                 */
 154                unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
 155                unsigned long max_size = min_size;
 156                if (nr)
 157                        max_size += (nr - 1)*8;
 158                if (idx_size < min_size || idx_size > max_size) {
 159                        munmap(idx_map, idx_size);
 160                        return error("wrong index v2 file size in %s", path);
 161                }
 162                if (idx_size != min_size &&
 163                    /*
 164                     * make sure we can deal with large pack offsets.
 165                     * 31-bit signed offset won't be enough, neither
 166                     * 32-bit unsigned one will be.
 167                     */
 168                    (sizeof(off_t) <= 4)) {
 169                        munmap(idx_map, idx_size);
 170                        return error("pack too large for current definition of off_t in %s", path);
 171                }
 172        }
 173
 174        p->index_version = version;
 175        p->index_data = idx_map;
 176        p->index_size = idx_size;
 177        p->num_objects = nr;
 178        return 0;
 179}
 180
 181int open_pack_index(struct packed_git *p)
 182{
 183        char *idx_name;
 184        size_t len;
 185        int ret;
 186
 187        if (p->index_data)
 188                return 0;
 189
 190        if (!strip_suffix(p->pack_name, ".pack", &len))
 191                die("BUG: pack_name does not end in .pack");
 192        idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
 193        ret = check_packed_git_idx(idx_name, p);
 194        free(idx_name);
 195        return ret;
 196}
 197
 198static struct packed_git *alloc_packed_git(int extra)
 199{
 200        struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
 201        memset(p, 0, sizeof(*p));
 202        p->pack_fd = -1;
 203        return p;
 204}
 205
 206struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 207{
 208        const char *path = sha1_pack_name(sha1);
 209        size_t alloc = st_add(strlen(path), 1);
 210        struct packed_git *p = alloc_packed_git(alloc);
 211
 212        memcpy(p->pack_name, path, alloc); /* includes NUL */
 213        hashcpy(p->sha1, sha1);
 214        if (check_packed_git_idx(idx_path, p)) {
 215                free(p);
 216                return NULL;
 217        }
 218
 219        return p;
 220}
 221
 222static void scan_windows(struct packed_git *p,
 223        struct packed_git **lru_p,
 224        struct pack_window **lru_w,
 225        struct pack_window **lru_l)
 226{
 227        struct pack_window *w, *w_l;
 228
 229        for (w_l = NULL, w = p->windows; w; w = w->next) {
 230                if (!w->inuse_cnt) {
 231                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 232                                *lru_p = p;
 233                                *lru_w = w;
 234                                *lru_l = w_l;
 235                        }
 236                }
 237                w_l = w;
 238        }
 239}
 240
 241static int unuse_one_window(struct packed_git *current)
 242{
 243        struct packed_git *p, *lru_p = NULL;
 244        struct pack_window *lru_w = NULL, *lru_l = NULL;
 245
 246        if (current)
 247                scan_windows(current, &lru_p, &lru_w, &lru_l);
 248        for (p = the_repository->objects->packed_git; p; p = p->next)
 249                scan_windows(p, &lru_p, &lru_w, &lru_l);
 250        if (lru_p) {
 251                munmap(lru_w->base, lru_w->len);
 252                pack_mapped -= lru_w->len;
 253                if (lru_l)
 254                        lru_l->next = lru_w->next;
 255                else
 256                        lru_p->windows = lru_w->next;
 257                free(lru_w);
 258                pack_open_windows--;
 259                return 1;
 260        }
 261        return 0;
 262}
 263
 264void release_pack_memory(size_t need)
 265{
 266        size_t cur = pack_mapped;
 267        while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 268                ; /* nothing */
 269}
 270
 271void close_pack_windows(struct packed_git *p)
 272{
 273        while (p->windows) {
 274                struct pack_window *w = p->windows;
 275
 276                if (w->inuse_cnt)
 277                        die("pack '%s' still has open windows to it",
 278                            p->pack_name);
 279                munmap(w->base, w->len);
 280                pack_mapped -= w->len;
 281                pack_open_windows--;
 282                p->windows = w->next;
 283                free(w);
 284        }
 285}
 286
 287static int close_pack_fd(struct packed_git *p)
 288{
 289        if (p->pack_fd < 0)
 290                return 0;
 291
 292        close(p->pack_fd);
 293        pack_open_fds--;
 294        p->pack_fd = -1;
 295
 296        return 1;
 297}
 298
 299void close_pack_index(struct packed_git *p)
 300{
 301        if (p->index_data) {
 302                munmap((void *)p->index_data, p->index_size);
 303                p->index_data = NULL;
 304        }
 305}
 306
 307void close_pack(struct packed_git *p)
 308{
 309        close_pack_windows(p);
 310        close_pack_fd(p);
 311        close_pack_index(p);
 312}
 313
 314void close_all_packs(struct raw_object_store *o)
 315{
 316        struct packed_git *p;
 317
 318        for (p = o->packed_git; p; p = p->next)
 319                if (p->do_not_close)
 320                        die("BUG: want to close pack marked 'do-not-close'");
 321                else
 322                        close_pack(p);
 323}
 324
 325/*
 326 * The LRU pack is the one with the oldest MRU window, preferring packs
 327 * with no used windows, or the oldest mtime if it has no windows allocated.
 328 */
 329static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 330{
 331        struct pack_window *w, *this_mru_w;
 332        int has_windows_inuse = 0;
 333
 334        /*
 335         * Reject this pack if it has windows and the previously selected
 336         * one does not.  If this pack does not have windows, reject
 337         * it if the pack file is newer than the previously selected one.
 338         */
 339        if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 340                return;
 341
 342        for (w = this_mru_w = p->windows; w; w = w->next) {
 343                /*
 344                 * Reject this pack if any of its windows are in use,
 345                 * but the previously selected pack did not have any
 346                 * inuse windows.  Otherwise, record that this pack
 347                 * has windows in use.
 348                 */
 349                if (w->inuse_cnt) {
 350                        if (*accept_windows_inuse)
 351                                has_windows_inuse = 1;
 352                        else
 353                                return;
 354                }
 355
 356                if (w->last_used > this_mru_w->last_used)
 357                        this_mru_w = w;
 358
 359                /*
 360                 * Reject this pack if it has windows that have been
 361                 * used more recently than the previously selected pack.
 362                 * If the previously selected pack had windows inuse and
 363                 * we have not encountered a window in this pack that is
 364                 * inuse, skip this check since we prefer a pack with no
 365                 * inuse windows to one that has inuse windows.
 366                 */
 367                if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 368                    this_mru_w->last_used > (*mru_w)->last_used)
 369                        return;
 370        }
 371
 372        /*
 373         * Select this pack.
 374         */
 375        *mru_w = this_mru_w;
 376        *lru_p = p;
 377        *accept_windows_inuse = has_windows_inuse;
 378}
 379
 380static int close_one_pack(void)
 381{
 382        struct packed_git *p, *lru_p = NULL;
 383        struct pack_window *mru_w = NULL;
 384        int accept_windows_inuse = 1;
 385
 386        for (p = the_repository->objects->packed_git; p; p = p->next) {
 387                if (p->pack_fd == -1)
 388                        continue;
 389                find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 390        }
 391
 392        if (lru_p)
 393                return close_pack_fd(lru_p);
 394
 395        return 0;
 396}
 397
 398static unsigned int get_max_fd_limit(void)
 399{
 400#ifdef RLIMIT_NOFILE
 401        {
 402                struct rlimit lim;
 403
 404                if (!getrlimit(RLIMIT_NOFILE, &lim))
 405                        return lim.rlim_cur;
 406        }
 407#endif
 408
 409#ifdef _SC_OPEN_MAX
 410        {
 411                long open_max = sysconf(_SC_OPEN_MAX);
 412                if (0 < open_max)
 413                        return open_max;
 414                /*
 415                 * Otherwise, we got -1 for one of the two
 416                 * reasons:
 417                 *
 418                 * (1) sysconf() did not understand _SC_OPEN_MAX
 419                 *     and signaled an error with -1; or
 420                 * (2) sysconf() said there is no limit.
 421                 *
 422                 * We _could_ clear errno before calling sysconf() to
 423                 * tell these two cases apart and return a huge number
 424                 * in the latter case to let the caller cap it to a
 425                 * value that is not so selfish, but letting the
 426                 * fallback OPEN_MAX codepath take care of these cases
 427                 * is a lot simpler.
 428                 */
 429        }
 430#endif
 431
 432#ifdef OPEN_MAX
 433        return OPEN_MAX;
 434#else
 435        return 1; /* see the caller ;-) */
 436#endif
 437}
 438
 439/*
 440 * Do not call this directly as this leaks p->pack_fd on error return;
 441 * call open_packed_git() instead.
 442 */
 443static int open_packed_git_1(struct packed_git *p)
 444{
 445        struct stat st;
 446        struct pack_header hdr;
 447        unsigned char sha1[20];
 448        unsigned char *idx_sha1;
 449        long fd_flag;
 450        ssize_t read_result;
 451
 452        if (!p->index_data && open_pack_index(p))
 453                return error("packfile %s index unavailable", p->pack_name);
 454
 455        if (!pack_max_fds) {
 456                unsigned int max_fds = get_max_fd_limit();
 457
 458                /* Save 3 for stdin/stdout/stderr, 22 for work */
 459                if (25 < max_fds)
 460                        pack_max_fds = max_fds - 25;
 461                else
 462                        pack_max_fds = 1;
 463        }
 464
 465        while (pack_max_fds <= pack_open_fds && close_one_pack())
 466                ; /* nothing */
 467
 468        p->pack_fd = git_open(p->pack_name);
 469        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 470                return -1;
 471        pack_open_fds++;
 472
 473        /* If we created the struct before we had the pack we lack size. */
 474        if (!p->pack_size) {
 475                if (!S_ISREG(st.st_mode))
 476                        return error("packfile %s not a regular file", p->pack_name);
 477                p->pack_size = st.st_size;
 478        } else if (p->pack_size != st.st_size)
 479                return error("packfile %s size changed", p->pack_name);
 480
 481        /* We leave these file descriptors open with sliding mmap;
 482         * there is no point keeping them open across exec(), though.
 483         */
 484        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 485        if (fd_flag < 0)
 486                return error("cannot determine file descriptor flags");
 487        fd_flag |= FD_CLOEXEC;
 488        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 489                return error("cannot set FD_CLOEXEC");
 490
 491        /* Verify we recognize this pack file format. */
 492        read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
 493        if (read_result < 0)
 494                return error_errno("error reading from %s", p->pack_name);
 495        if (read_result != sizeof(hdr))
 496                return error("file %s is far too short to be a packfile", p->pack_name);
 497        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 498                return error("file %s is not a GIT packfile", p->pack_name);
 499        if (!pack_version_ok(hdr.hdr_version))
 500                return error("packfile %s is version %"PRIu32" and not"
 501                        " supported (try upgrading GIT to a newer version)",
 502                        p->pack_name, ntohl(hdr.hdr_version));
 503
 504        /* Verify the pack matches its index. */
 505        if (p->num_objects != ntohl(hdr.hdr_entries))
 506                return error("packfile %s claims to have %"PRIu32" objects"
 507                             " while index indicates %"PRIu32" objects",
 508                             p->pack_name, ntohl(hdr.hdr_entries),
 509                             p->num_objects);
 510        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 511                return error("end of packfile %s is unavailable", p->pack_name);
 512        read_result = read_in_full(p->pack_fd, sha1, sizeof(sha1));
 513        if (read_result < 0)
 514                return error_errno("error reading from %s", p->pack_name);
 515        if (read_result != sizeof(sha1))
 516                return error("packfile %s signature is unavailable", p->pack_name);
 517        idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
 518        if (hashcmp(sha1, idx_sha1))
 519                return error("packfile %s does not match index", p->pack_name);
 520        return 0;
 521}
 522
 523static int open_packed_git(struct packed_git *p)
 524{
 525        if (!open_packed_git_1(p))
 526                return 0;
 527        close_pack_fd(p);
 528        return -1;
 529}
 530
 531static int in_window(struct pack_window *win, off_t offset)
 532{
 533        /* We must promise at least 20 bytes (one hash) after the
 534         * offset is available from this window, otherwise the offset
 535         * is not actually in this window and a different window (which
 536         * has that one hash excess) must be used.  This is to support
 537         * the object header and delta base parsing routines below.
 538         */
 539        off_t win_off = win->offset;
 540        return win_off <= offset
 541                && (offset + 20) <= (win_off + win->len);
 542}
 543
 544unsigned char *use_pack(struct packed_git *p,
 545                struct pack_window **w_cursor,
 546                off_t offset,
 547                unsigned long *left)
 548{
 549        struct pack_window *win = *w_cursor;
 550
 551        /* Since packfiles end in a hash of their content and it's
 552         * pointless to ask for an offset into the middle of that
 553         * hash, and the in_window function above wouldn't match
 554         * don't allow an offset too close to the end of the file.
 555         */
 556        if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 557                die("packfile %s cannot be accessed", p->pack_name);
 558        if (offset > (p->pack_size - 20))
 559                die("offset beyond end of packfile (truncated pack?)");
 560        if (offset < 0)
 561                die(_("offset before end of packfile (broken .idx?)"));
 562
 563        if (!win || !in_window(win, offset)) {
 564                if (win)
 565                        win->inuse_cnt--;
 566                for (win = p->windows; win; win = win->next) {
 567                        if (in_window(win, offset))
 568                                break;
 569                }
 570                if (!win) {
 571                        size_t window_align = packed_git_window_size / 2;
 572                        off_t len;
 573
 574                        if (p->pack_fd == -1 && open_packed_git(p))
 575                                die("packfile %s cannot be accessed", p->pack_name);
 576
 577                        win = xcalloc(1, sizeof(*win));
 578                        win->offset = (offset / window_align) * window_align;
 579                        len = p->pack_size - win->offset;
 580                        if (len > packed_git_window_size)
 581                                len = packed_git_window_size;
 582                        win->len = (size_t)len;
 583                        pack_mapped += win->len;
 584                        while (packed_git_limit < pack_mapped
 585                                && unuse_one_window(p))
 586                                ; /* nothing */
 587                        win->base = xmmap(NULL, win->len,
 588                                PROT_READ, MAP_PRIVATE,
 589                                p->pack_fd, win->offset);
 590                        if (win->base == MAP_FAILED)
 591                                die_errno("packfile %s cannot be mapped",
 592                                          p->pack_name);
 593                        if (!win->offset && win->len == p->pack_size
 594                                && !p->do_not_close)
 595                                close_pack_fd(p);
 596                        pack_mmap_calls++;
 597                        pack_open_windows++;
 598                        if (pack_mapped > peak_pack_mapped)
 599                                peak_pack_mapped = pack_mapped;
 600                        if (pack_open_windows > peak_pack_open_windows)
 601                                peak_pack_open_windows = pack_open_windows;
 602                        win->next = p->windows;
 603                        p->windows = win;
 604                }
 605        }
 606        if (win != *w_cursor) {
 607                win->last_used = pack_used_ctr++;
 608                win->inuse_cnt++;
 609                *w_cursor = win;
 610        }
 611        offset -= win->offset;
 612        if (left)
 613                *left = win->len - xsize_t(offset);
 614        return win->base + offset;
 615}
 616
 617void unuse_pack(struct pack_window **w_cursor)
 618{
 619        struct pack_window *w = *w_cursor;
 620        if (w) {
 621                w->inuse_cnt--;
 622                *w_cursor = NULL;
 623        }
 624}
 625
 626static void try_to_free_pack_memory(size_t size)
 627{
 628        release_pack_memory(size);
 629}
 630
 631struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
 632{
 633        static int have_set_try_to_free_routine;
 634        struct stat st;
 635        size_t alloc;
 636        struct packed_git *p;
 637
 638        if (!have_set_try_to_free_routine) {
 639                have_set_try_to_free_routine = 1;
 640                set_try_to_free_routine(try_to_free_pack_memory);
 641        }
 642
 643        /*
 644         * Make sure a corresponding .pack file exists and that
 645         * the index looks sane.
 646         */
 647        if (!strip_suffix_mem(path, &path_len, ".idx"))
 648                return NULL;
 649
 650        /*
 651         * ".promisor" is long enough to hold any suffix we're adding (and
 652         * the use xsnprintf double-checks that)
 653         */
 654        alloc = st_add3(path_len, strlen(".promisor"), 1);
 655        p = alloc_packed_git(alloc);
 656        memcpy(p->pack_name, path, path_len);
 657
 658        xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
 659        if (!access(p->pack_name, F_OK))
 660                p->pack_keep = 1;
 661
 662        xsnprintf(p->pack_name + path_len, alloc - path_len, ".promisor");
 663        if (!access(p->pack_name, F_OK))
 664                p->pack_promisor = 1;
 665
 666        xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
 667        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 668                free(p);
 669                return NULL;
 670        }
 671
 672        /* ok, it looks sane as far as we can check without
 673         * actually mapping the pack file.
 674         */
 675        p->pack_size = st.st_size;
 676        p->pack_local = local;
 677        p->mtime = st.st_mtime;
 678        if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
 679                hashclr(p->sha1);
 680        return p;
 681}
 682
 683void install_packed_git(struct repository *r, struct packed_git *pack)
 684{
 685        if (pack->pack_fd != -1)
 686                pack_open_fds++;
 687
 688        pack->next = r->objects->packed_git;
 689        r->objects->packed_git = pack;
 690}
 691
 692void (*report_garbage)(unsigned seen_bits, const char *path);
 693
 694static void report_helper(const struct string_list *list,
 695                          int seen_bits, int first, int last)
 696{
 697        if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
 698                return;
 699
 700        for (; first < last; first++)
 701                report_garbage(seen_bits, list->items[first].string);
 702}
 703
 704static void report_pack_garbage(struct string_list *list)
 705{
 706        int i, baselen = -1, first = 0, seen_bits = 0;
 707
 708        if (!report_garbage)
 709                return;
 710
 711        string_list_sort(list);
 712
 713        for (i = 0; i < list->nr; i++) {
 714                const char *path = list->items[i].string;
 715                if (baselen != -1 &&
 716                    strncmp(path, list->items[first].string, baselen)) {
 717                        report_helper(list, seen_bits, first, i);
 718                        baselen = -1;
 719                        seen_bits = 0;
 720                }
 721                if (baselen == -1) {
 722                        const char *dot = strrchr(path, '.');
 723                        if (!dot) {
 724                                report_garbage(PACKDIR_FILE_GARBAGE, path);
 725                                continue;
 726                        }
 727                        baselen = dot - path + 1;
 728                        first = i;
 729                }
 730                if (!strcmp(path + baselen, "pack"))
 731                        seen_bits |= 1;
 732                else if (!strcmp(path + baselen, "idx"))
 733                        seen_bits |= 2;
 734        }
 735        report_helper(list, seen_bits, first, list->nr);
 736}
 737
 738static void prepare_packed_git_one(struct repository *r, char *objdir, int local)
 739{
 740        struct strbuf path = STRBUF_INIT;
 741        size_t dirnamelen;
 742        DIR *dir;
 743        struct dirent *de;
 744        struct string_list garbage = STRING_LIST_INIT_DUP;
 745
 746        strbuf_addstr(&path, objdir);
 747        strbuf_addstr(&path, "/pack");
 748        dir = opendir(path.buf);
 749        if (!dir) {
 750                if (errno != ENOENT)
 751                        error_errno("unable to open object pack directory: %s",
 752                                    path.buf);
 753                strbuf_release(&path);
 754                return;
 755        }
 756        strbuf_addch(&path, '/');
 757        dirnamelen = path.len;
 758        while ((de = readdir(dir)) != NULL) {
 759                struct packed_git *p;
 760                size_t base_len;
 761
 762                if (is_dot_or_dotdot(de->d_name))
 763                        continue;
 764
 765                strbuf_setlen(&path, dirnamelen);
 766                strbuf_addstr(&path, de->d_name);
 767
 768                base_len = path.len;
 769                if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
 770                        /* Don't reopen a pack we already have. */
 771                        for (p = r->objects->packed_git; p;
 772                             p = p->next) {
 773                                size_t len;
 774                                if (strip_suffix(p->pack_name, ".pack", &len) &&
 775                                    len == base_len &&
 776                                    !memcmp(p->pack_name, path.buf, len))
 777                                        break;
 778                        }
 779                        if (p == NULL &&
 780                            /*
 781                             * See if it really is a valid .idx file with
 782                             * corresponding .pack file that we can map.
 783                             */
 784                            (p = add_packed_git(path.buf, path.len, local)) != NULL)
 785                                install_packed_git(r, p);
 786                }
 787
 788                if (!report_garbage)
 789                        continue;
 790
 791                if (ends_with(de->d_name, ".idx") ||
 792                    ends_with(de->d_name, ".pack") ||
 793                    ends_with(de->d_name, ".bitmap") ||
 794                    ends_with(de->d_name, ".keep") ||
 795                    ends_with(de->d_name, ".promisor"))
 796                        string_list_append(&garbage, path.buf);
 797                else
 798                        report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
 799        }
 800        closedir(dir);
 801        report_pack_garbage(&garbage);
 802        string_list_clear(&garbage, 0);
 803        strbuf_release(&path);
 804}
 805
 806static void prepare_packed_git(struct repository *r);
 807/*
 808 * Give a fast, rough count of the number of objects in the repository. This
 809 * ignores loose objects completely. If you have a lot of them, then either
 810 * you should repack because your performance will be awful, or they are
 811 * all unreachable objects about to be pruned, in which case they're not really
 812 * interesting as a measure of repo size in the first place.
 813 */
 814unsigned long approximate_object_count(void)
 815{
 816        if (!the_repository->objects->approximate_object_count_valid) {
 817                unsigned long count;
 818                struct packed_git *p;
 819
 820                prepare_packed_git(the_repository);
 821                count = 0;
 822                for (p = the_repository->objects->packed_git; p; p = p->next) {
 823                        if (open_pack_index(p))
 824                                continue;
 825                        count += p->num_objects;
 826                }
 827                the_repository->objects->approximate_object_count = count;
 828        }
 829        return the_repository->objects->approximate_object_count;
 830}
 831
 832static void *get_next_packed_git(const void *p)
 833{
 834        return ((const struct packed_git *)p)->next;
 835}
 836
 837static void set_next_packed_git(void *p, void *next)
 838{
 839        ((struct packed_git *)p)->next = next;
 840}
 841
 842static int sort_pack(const void *a_, const void *b_)
 843{
 844        const struct packed_git *a = a_;
 845        const struct packed_git *b = b_;
 846        int st;
 847
 848        /*
 849         * Local packs tend to contain objects specific to our
 850         * variant of the project than remote ones.  In addition,
 851         * remote ones could be on a network mounted filesystem.
 852         * Favor local ones for these reasons.
 853         */
 854        st = a->pack_local - b->pack_local;
 855        if (st)
 856                return -st;
 857
 858        /*
 859         * Younger packs tend to contain more recent objects,
 860         * and more recent objects tend to get accessed more
 861         * often.
 862         */
 863        if (a->mtime < b->mtime)
 864                return 1;
 865        else if (a->mtime == b->mtime)
 866                return 0;
 867        return -1;
 868}
 869
 870static void rearrange_packed_git(struct repository *r)
 871{
 872        r->objects->packed_git = llist_mergesort(
 873                r->objects->packed_git, get_next_packed_git,
 874                set_next_packed_git, sort_pack);
 875}
 876
 877static void prepare_packed_git_mru(struct repository *r)
 878{
 879        struct packed_git *p;
 880
 881        INIT_LIST_HEAD(&r->objects->packed_git_mru);
 882
 883        for (p = r->objects->packed_git; p; p = p->next)
 884                list_add_tail(&p->mru, &r->objects->packed_git_mru);
 885}
 886
 887static void prepare_packed_git(struct repository *r)
 888{
 889        struct alternate_object_database *alt;
 890
 891        if (r->objects->packed_git_initialized)
 892                return;
 893        prepare_packed_git_one(r, r->objects->objectdir, 1);
 894        prepare_alt_odb(r);
 895        for (alt = r->objects->alt_odb_list; alt; alt = alt->next)
 896                prepare_packed_git_one(r, alt->path, 0);
 897        rearrange_packed_git(r);
 898        prepare_packed_git_mru(r);
 899        r->objects->packed_git_initialized = 1;
 900}
 901
 902void reprepare_packed_git(struct repository *r)
 903{
 904        r->objects->approximate_object_count_valid = 0;
 905        r->objects->packed_git_initialized = 0;
 906        prepare_packed_git(r);
 907}
 908
 909struct packed_git *get_packed_git(struct repository *r)
 910{
 911        prepare_packed_git(r);
 912        return r->objects->packed_git;
 913}
 914
 915struct list_head *get_packed_git_mru(struct repository *r)
 916{
 917        prepare_packed_git(r);
 918        return &r->objects->packed_git_mru;
 919}
 920
 921unsigned long unpack_object_header_buffer(const unsigned char *buf,
 922                unsigned long len, enum object_type *type, unsigned long *sizep)
 923{
 924        unsigned shift;
 925        unsigned long size, c;
 926        unsigned long used = 0;
 927
 928        c = buf[used++];
 929        *type = (c >> 4) & 7;
 930        size = c & 15;
 931        shift = 4;
 932        while (c & 0x80) {
 933                if (len <= used || bitsizeof(long) <= shift) {
 934                        error("bad object header");
 935                        size = used = 0;
 936                        break;
 937                }
 938                c = buf[used++];
 939                size += (c & 0x7f) << shift;
 940                shift += 7;
 941        }
 942        *sizep = size;
 943        return used;
 944}
 945
 946unsigned long get_size_from_delta(struct packed_git *p,
 947                                  struct pack_window **w_curs,
 948                                  off_t curpos)
 949{
 950        const unsigned char *data;
 951        unsigned char delta_head[20], *in;
 952        git_zstream stream;
 953        int st;
 954
 955        memset(&stream, 0, sizeof(stream));
 956        stream.next_out = delta_head;
 957        stream.avail_out = sizeof(delta_head);
 958
 959        git_inflate_init(&stream);
 960        do {
 961                in = use_pack(p, w_curs, curpos, &stream.avail_in);
 962                stream.next_in = in;
 963                st = git_inflate(&stream, Z_FINISH);
 964                curpos += stream.next_in - in;
 965        } while ((st == Z_OK || st == Z_BUF_ERROR) &&
 966                 stream.total_out < sizeof(delta_head));
 967        git_inflate_end(&stream);
 968        if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
 969                error("delta data unpack-initial failed");
 970                return 0;
 971        }
 972
 973        /* Examine the initial part of the delta to figure out
 974         * the result size.
 975         */
 976        data = delta_head;
 977
 978        /* ignore base size */
 979        get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 980
 981        /* Read the result size */
 982        return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
 983}
 984
 985int unpack_object_header(struct packed_git *p,
 986                         struct pack_window **w_curs,
 987                         off_t *curpos,
 988                         unsigned long *sizep)
 989{
 990        unsigned char *base;
 991        unsigned long left;
 992        unsigned long used;
 993        enum object_type type;
 994
 995        /* use_pack() assures us we have [base, base + 20) available
 996         * as a range that we can look at.  (Its actually the hash
 997         * size that is assured.)  With our object header encoding
 998         * the maximum deflated object size is 2^137, which is just
 999         * insane, so we know won't exceed what we have been given.
1000         */
1001        base = use_pack(p, w_curs, *curpos, &left);
1002        used = unpack_object_header_buffer(base, left, &type, sizep);
1003        if (!used) {
1004                type = OBJ_BAD;
1005        } else
1006                *curpos += used;
1007
1008        return type;
1009}
1010
1011void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1012{
1013        unsigned i;
1014        for (i = 0; i < p->num_bad_objects; i++)
1015                if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
1016                        return;
1017        p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1018                                      st_mult(GIT_MAX_RAWSZ,
1019                                              st_add(p->num_bad_objects, 1)));
1020        hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
1021        p->num_bad_objects++;
1022}
1023
1024const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1025{
1026        struct packed_git *p;
1027        unsigned i;
1028
1029        for (p = the_repository->objects->packed_git; p; p = p->next)
1030                for (i = 0; i < p->num_bad_objects; i++)
1031                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1032                                return p;
1033        return NULL;
1034}
1035
1036static off_t get_delta_base(struct packed_git *p,
1037                                    struct pack_window **w_curs,
1038                                    off_t *curpos,
1039                                    enum object_type type,
1040                                    off_t delta_obj_offset)
1041{
1042        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1043        off_t base_offset;
1044
1045        /* use_pack() assured us we have [base_info, base_info + 20)
1046         * as a range that we can look at without walking off the
1047         * end of the mapped window.  Its actually the hash size
1048         * that is assured.  An OFS_DELTA longer than the hash size
1049         * is stupid, as then a REF_DELTA would be smaller to store.
1050         */
1051        if (type == OBJ_OFS_DELTA) {
1052                unsigned used = 0;
1053                unsigned char c = base_info[used++];
1054                base_offset = c & 127;
1055                while (c & 128) {
1056                        base_offset += 1;
1057                        if (!base_offset || MSB(base_offset, 7))
1058                                return 0;  /* overflow */
1059                        c = base_info[used++];
1060                        base_offset = (base_offset << 7) + (c & 127);
1061                }
1062                base_offset = delta_obj_offset - base_offset;
1063                if (base_offset <= 0 || base_offset >= delta_obj_offset)
1064                        return 0;  /* out of bound */
1065                *curpos += used;
1066        } else if (type == OBJ_REF_DELTA) {
1067                /* The base entry _must_ be in the same pack */
1068                base_offset = find_pack_entry_one(base_info, p);
1069                *curpos += 20;
1070        } else
1071                die("I am totally screwed");
1072        return base_offset;
1073}
1074
1075/*
1076 * Like get_delta_base above, but we return the sha1 instead of the pack
1077 * offset. This means it is cheaper for REF deltas (we do not have to do
1078 * the final object lookup), but more expensive for OFS deltas (we
1079 * have to load the revidx to convert the offset back into a sha1).
1080 */
1081static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1082                                                struct pack_window **w_curs,
1083                                                off_t curpos,
1084                                                enum object_type type,
1085                                                off_t delta_obj_offset)
1086{
1087        if (type == OBJ_REF_DELTA) {
1088                unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1089                return base;
1090        } else if (type == OBJ_OFS_DELTA) {
1091                struct revindex_entry *revidx;
1092                off_t base_offset = get_delta_base(p, w_curs, &curpos,
1093                                                   type, delta_obj_offset);
1094
1095                if (!base_offset)
1096                        return NULL;
1097
1098                revidx = find_pack_revindex(p, base_offset);
1099                if (!revidx)
1100                        return NULL;
1101
1102                return nth_packed_object_sha1(p, revidx->nr);
1103        } else
1104                return NULL;
1105}
1106
1107static int retry_bad_packed_offset(struct repository *r,
1108                                   struct packed_git *p,
1109                                   off_t obj_offset)
1110{
1111        int type;
1112        struct revindex_entry *revidx;
1113        struct object_id oid;
1114        revidx = find_pack_revindex(p, obj_offset);
1115        if (!revidx)
1116                return OBJ_BAD;
1117        nth_packed_object_oid(&oid, p, revidx->nr);
1118        mark_bad_packed_object(p, oid.hash);
1119        type = oid_object_info(r, &oid, NULL);
1120        if (type <= OBJ_NONE)
1121                return OBJ_BAD;
1122        return type;
1123}
1124
1125#define POI_STACK_PREALLOC 64
1126
1127static enum object_type packed_to_object_type(struct repository *r,
1128                                              struct packed_git *p,
1129                                              off_t obj_offset,
1130                                              enum object_type type,
1131                                              struct pack_window **w_curs,
1132                                              off_t curpos)
1133{
1134        off_t small_poi_stack[POI_STACK_PREALLOC];
1135        off_t *poi_stack = small_poi_stack;
1136        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1137
1138        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1139                off_t base_offset;
1140                unsigned long size;
1141                /* Push the object we're going to leave behind */
1142                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1143                        poi_stack_alloc = alloc_nr(poi_stack_nr);
1144                        ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1145                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1146                } else {
1147                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1148                }
1149                poi_stack[poi_stack_nr++] = obj_offset;
1150                /* If parsing the base offset fails, just unwind */
1151                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1152                if (!base_offset)
1153                        goto unwind;
1154                curpos = obj_offset = base_offset;
1155                type = unpack_object_header(p, w_curs, &curpos, &size);
1156                if (type <= OBJ_NONE) {
1157                        /* If getting the base itself fails, we first
1158                         * retry the base, otherwise unwind */
1159                        type = retry_bad_packed_offset(r, p, base_offset);
1160                        if (type > OBJ_NONE)
1161                                goto out;
1162                        goto unwind;
1163                }
1164        }
1165
1166        switch (type) {
1167        case OBJ_BAD:
1168        case OBJ_COMMIT:
1169        case OBJ_TREE:
1170        case OBJ_BLOB:
1171        case OBJ_TAG:
1172                break;
1173        default:
1174                error("unknown object type %i at offset %"PRIuMAX" in %s",
1175                      type, (uintmax_t)obj_offset, p->pack_name);
1176                type = OBJ_BAD;
1177        }
1178
1179out:
1180        if (poi_stack != small_poi_stack)
1181                free(poi_stack);
1182        return type;
1183
1184unwind:
1185        while (poi_stack_nr) {
1186                obj_offset = poi_stack[--poi_stack_nr];
1187                type = retry_bad_packed_offset(r, p, obj_offset);
1188                if (type > OBJ_NONE)
1189                        goto out;
1190        }
1191        type = OBJ_BAD;
1192        goto out;
1193}
1194
1195static struct hashmap delta_base_cache;
1196static size_t delta_base_cached;
1197
1198static LIST_HEAD(delta_base_cache_lru);
1199
1200struct delta_base_cache_key {
1201        struct packed_git *p;
1202        off_t base_offset;
1203};
1204
1205struct delta_base_cache_entry {
1206        struct hashmap hash;
1207        struct delta_base_cache_key key;
1208        struct list_head lru;
1209        void *data;
1210        unsigned long size;
1211        enum object_type type;
1212};
1213
1214static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1215{
1216        unsigned int hash;
1217
1218        hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1219        hash += (hash >> 8) + (hash >> 16);
1220        return hash;
1221}
1222
1223static struct delta_base_cache_entry *
1224get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1225{
1226        struct hashmap_entry entry;
1227        struct delta_base_cache_key key;
1228
1229        if (!delta_base_cache.cmpfn)
1230                return NULL;
1231
1232        hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1233        key.p = p;
1234        key.base_offset = base_offset;
1235        return hashmap_get(&delta_base_cache, &entry, &key);
1236}
1237
1238static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1239                                   const struct delta_base_cache_key *b)
1240{
1241        return a->p == b->p && a->base_offset == b->base_offset;
1242}
1243
1244static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1245                                     const void *va, const void *vb,
1246                                     const void *vkey)
1247{
1248        const struct delta_base_cache_entry *a = va, *b = vb;
1249        const struct delta_base_cache_key *key = vkey;
1250        if (key)
1251                return !delta_base_cache_key_eq(&a->key, key);
1252        else
1253                return !delta_base_cache_key_eq(&a->key, &b->key);
1254}
1255
1256static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1257{
1258        return !!get_delta_base_cache_entry(p, base_offset);
1259}
1260
1261/*
1262 * Remove the entry from the cache, but do _not_ free the associated
1263 * entry data. The caller takes ownership of the "data" buffer, and
1264 * should copy out any fields it wants before detaching.
1265 */
1266static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1267{
1268        hashmap_remove(&delta_base_cache, ent, &ent->key);
1269        list_del(&ent->lru);
1270        delta_base_cached -= ent->size;
1271        free(ent);
1272}
1273
1274static void *cache_or_unpack_entry(struct repository *r, struct packed_git *p,
1275                                   off_t base_offset, unsigned long *base_size,
1276                                   enum object_type *type)
1277{
1278        struct delta_base_cache_entry *ent;
1279
1280        ent = get_delta_base_cache_entry(p, base_offset);
1281        if (!ent)
1282                return unpack_entry(r, p, base_offset, type, base_size);
1283
1284        if (type)
1285                *type = ent->type;
1286        if (base_size)
1287                *base_size = ent->size;
1288        return xmemdupz(ent->data, ent->size);
1289}
1290
1291static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1292{
1293        free(ent->data);
1294        detach_delta_base_cache_entry(ent);
1295}
1296
1297void clear_delta_base_cache(void)
1298{
1299        struct list_head *lru, *tmp;
1300        list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1301                struct delta_base_cache_entry *entry =
1302                        list_entry(lru, struct delta_base_cache_entry, lru);
1303                release_delta_base_cache(entry);
1304        }
1305}
1306
1307static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1308        void *base, unsigned long base_size, enum object_type type)
1309{
1310        struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1311        struct list_head *lru, *tmp;
1312
1313        delta_base_cached += base_size;
1314
1315        list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1316                struct delta_base_cache_entry *f =
1317                        list_entry(lru, struct delta_base_cache_entry, lru);
1318                if (delta_base_cached <= delta_base_cache_limit)
1319                        break;
1320                release_delta_base_cache(f);
1321        }
1322
1323        ent->key.p = p;
1324        ent->key.base_offset = base_offset;
1325        ent->type = type;
1326        ent->data = base;
1327        ent->size = base_size;
1328        list_add_tail(&ent->lru, &delta_base_cache_lru);
1329
1330        if (!delta_base_cache.cmpfn)
1331                hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1332        hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1333        hashmap_add(&delta_base_cache, ent);
1334}
1335
1336int packed_object_info(struct repository *r, struct packed_git *p,
1337                       off_t obj_offset, struct object_info *oi)
1338{
1339        struct pack_window *w_curs = NULL;
1340        unsigned long size;
1341        off_t curpos = obj_offset;
1342        enum object_type type;
1343
1344        /*
1345         * We always get the representation type, but only convert it to
1346         * a "real" type later if the caller is interested.
1347         */
1348        if (oi->contentp) {
1349                *oi->contentp = cache_or_unpack_entry(r, p, obj_offset, oi->sizep,
1350                                                      &type);
1351                if (!*oi->contentp)
1352                        type = OBJ_BAD;
1353        } else {
1354                type = unpack_object_header(p, &w_curs, &curpos, &size);
1355        }
1356
1357        if (!oi->contentp && oi->sizep) {
1358                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1359                        off_t tmp_pos = curpos;
1360                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1361                                                           type, obj_offset);
1362                        if (!base_offset) {
1363                                type = OBJ_BAD;
1364                                goto out;
1365                        }
1366                        *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1367                        if (*oi->sizep == 0) {
1368                                type = OBJ_BAD;
1369                                goto out;
1370                        }
1371                } else {
1372                        *oi->sizep = size;
1373                }
1374        }
1375
1376        if (oi->disk_sizep) {
1377                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1378                *oi->disk_sizep = revidx[1].offset - obj_offset;
1379        }
1380
1381        if (oi->typep || oi->type_name) {
1382                enum object_type ptot;
1383                ptot = packed_to_object_type(r, p, obj_offset,
1384                                             type, &w_curs, curpos);
1385                if (oi->typep)
1386                        *oi->typep = ptot;
1387                if (oi->type_name) {
1388                        const char *tn = type_name(ptot);
1389                        if (tn)
1390                                strbuf_addstr(oi->type_name, tn);
1391                }
1392                if (ptot < 0) {
1393                        type = OBJ_BAD;
1394                        goto out;
1395                }
1396        }
1397
1398        if (oi->delta_base_sha1) {
1399                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1400                        const unsigned char *base;
1401
1402                        base = get_delta_base_sha1(p, &w_curs, curpos,
1403                                                   type, obj_offset);
1404                        if (!base) {
1405                                type = OBJ_BAD;
1406                                goto out;
1407                        }
1408
1409                        hashcpy(oi->delta_base_sha1, base);
1410                } else
1411                        hashclr(oi->delta_base_sha1);
1412        }
1413
1414        oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1415                                                          OI_PACKED;
1416
1417out:
1418        unuse_pack(&w_curs);
1419        return type;
1420}
1421
1422static void *unpack_compressed_entry(struct packed_git *p,
1423                                    struct pack_window **w_curs,
1424                                    off_t curpos,
1425                                    unsigned long size)
1426{
1427        int st;
1428        git_zstream stream;
1429        unsigned char *buffer, *in;
1430
1431        buffer = xmallocz_gently(size);
1432        if (!buffer)
1433                return NULL;
1434        memset(&stream, 0, sizeof(stream));
1435        stream.next_out = buffer;
1436        stream.avail_out = size + 1;
1437
1438        git_inflate_init(&stream);
1439        do {
1440                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1441                stream.next_in = in;
1442                st = git_inflate(&stream, Z_FINISH);
1443                if (!stream.avail_out)
1444                        break; /* the payload is larger than it should be */
1445                curpos += stream.next_in - in;
1446        } while (st == Z_OK || st == Z_BUF_ERROR);
1447        git_inflate_end(&stream);
1448        if ((st != Z_STREAM_END) || stream.total_out != size) {
1449                free(buffer);
1450                return NULL;
1451        }
1452
1453        return buffer;
1454}
1455
1456static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1457{
1458        static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1459        trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1460                         p->pack_name, (uintmax_t)obj_offset);
1461}
1462
1463int do_check_packed_object_crc;
1464
1465#define UNPACK_ENTRY_STACK_PREALLOC 64
1466struct unpack_entry_stack_ent {
1467        off_t obj_offset;
1468        off_t curpos;
1469        unsigned long size;
1470};
1471
1472static void *read_object(struct repository *r,
1473                         const struct object_id *oid,
1474                         enum object_type *type,
1475                         unsigned long *size)
1476{
1477        struct object_info oi = OBJECT_INFO_INIT;
1478        void *content;
1479        oi.typep = type;
1480        oi.sizep = size;
1481        oi.contentp = &content;
1482
1483        if (oid_object_info_extended(r, oid, &oi, 0) < 0)
1484                return NULL;
1485        return content;
1486}
1487
1488void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset,
1489                   enum object_type *final_type, unsigned long *final_size)
1490{
1491        struct pack_window *w_curs = NULL;
1492        off_t curpos = obj_offset;
1493        void *data = NULL;
1494        unsigned long size;
1495        enum object_type type;
1496        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1497        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1498        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1499        int base_from_cache = 0;
1500
1501        write_pack_access_log(p, obj_offset);
1502
1503        /* PHASE 1: drill down to the innermost base object */
1504        for (;;) {
1505                off_t base_offset;
1506                int i;
1507                struct delta_base_cache_entry *ent;
1508
1509                ent = get_delta_base_cache_entry(p, curpos);
1510                if (ent) {
1511                        type = ent->type;
1512                        data = ent->data;
1513                        size = ent->size;
1514                        detach_delta_base_cache_entry(ent);
1515                        base_from_cache = 1;
1516                        break;
1517                }
1518
1519                if (do_check_packed_object_crc && p->index_version > 1) {
1520                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1521                        off_t len = revidx[1].offset - obj_offset;
1522                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1523                                struct object_id oid;
1524                                nth_packed_object_oid(&oid, p, revidx->nr);
1525                                error("bad packed object CRC for %s",
1526                                      oid_to_hex(&oid));
1527                                mark_bad_packed_object(p, oid.hash);
1528                                data = NULL;
1529                                goto out;
1530                        }
1531                }
1532
1533                type = unpack_object_header(p, &w_curs, &curpos, &size);
1534                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1535                        break;
1536
1537                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1538                if (!base_offset) {
1539                        error("failed to validate delta base reference "
1540                              "at offset %"PRIuMAX" from %s",
1541                              (uintmax_t)curpos, p->pack_name);
1542                        /* bail to phase 2, in hopes of recovery */
1543                        data = NULL;
1544                        break;
1545                }
1546
1547                /* push object, proceed to base */
1548                if (delta_stack_nr >= delta_stack_alloc
1549                    && delta_stack == small_delta_stack) {
1550                        delta_stack_alloc = alloc_nr(delta_stack_nr);
1551                        ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1552                        memcpy(delta_stack, small_delta_stack,
1553                               sizeof(*delta_stack)*delta_stack_nr);
1554                } else {
1555                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1556                }
1557                i = delta_stack_nr++;
1558                delta_stack[i].obj_offset = obj_offset;
1559                delta_stack[i].curpos = curpos;
1560                delta_stack[i].size = size;
1561
1562                curpos = obj_offset = base_offset;
1563        }
1564
1565        /* PHASE 2: handle the base */
1566        switch (type) {
1567        case OBJ_OFS_DELTA:
1568        case OBJ_REF_DELTA:
1569                if (data)
1570                        die("BUG: unpack_entry: left loop at a valid delta");
1571                break;
1572        case OBJ_COMMIT:
1573        case OBJ_TREE:
1574        case OBJ_BLOB:
1575        case OBJ_TAG:
1576                if (!base_from_cache)
1577                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
1578                break;
1579        default:
1580                data = NULL;
1581                error("unknown object type %i at offset %"PRIuMAX" in %s",
1582                      type, (uintmax_t)obj_offset, p->pack_name);
1583        }
1584
1585        /* PHASE 3: apply deltas in order */
1586
1587        /* invariants:
1588         *   'data' holds the base data, or NULL if there was corruption
1589         */
1590        while (delta_stack_nr) {
1591                void *delta_data;
1592                void *base = data;
1593                void *external_base = NULL;
1594                unsigned long delta_size, base_size = size;
1595                int i;
1596
1597                data = NULL;
1598
1599                if (base)
1600                        add_delta_base_cache(p, obj_offset, base, base_size, type);
1601
1602                if (!base) {
1603                        /*
1604                         * We're probably in deep shit, but let's try to fetch
1605                         * the required base anyway from another pack or loose.
1606                         * This is costly but should happen only in the presence
1607                         * of a corrupted pack, and is better than failing outright.
1608                         */
1609                        struct revindex_entry *revidx;
1610                        struct object_id base_oid;
1611                        revidx = find_pack_revindex(p, obj_offset);
1612                        if (revidx) {
1613                                nth_packed_object_oid(&base_oid, p, revidx->nr);
1614                                error("failed to read delta base object %s"
1615                                      " at offset %"PRIuMAX" from %s",
1616                                      oid_to_hex(&base_oid), (uintmax_t)obj_offset,
1617                                      p->pack_name);
1618                                mark_bad_packed_object(p, base_oid.hash);
1619                                base = read_object(r, &base_oid, &type, &base_size);
1620                                external_base = base;
1621                        }
1622                }
1623
1624                i = --delta_stack_nr;
1625                obj_offset = delta_stack[i].obj_offset;
1626                curpos = delta_stack[i].curpos;
1627                delta_size = delta_stack[i].size;
1628
1629                if (!base)
1630                        continue;
1631
1632                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1633
1634                if (!delta_data) {
1635                        error("failed to unpack compressed delta "
1636                              "at offset %"PRIuMAX" from %s",
1637                              (uintmax_t)curpos, p->pack_name);
1638                        data = NULL;
1639                        free(external_base);
1640                        continue;
1641                }
1642
1643                data = patch_delta(base, base_size,
1644                                   delta_data, delta_size,
1645                                   &size);
1646
1647                /*
1648                 * We could not apply the delta; warn the user, but keep going.
1649                 * Our failure will be noticed either in the next iteration of
1650                 * the loop, or if this is the final delta, in the caller when
1651                 * we return NULL. Those code paths will take care of making
1652                 * a more explicit warning and retrying with another copy of
1653                 * the object.
1654                 */
1655                if (!data)
1656                        error("failed to apply delta");
1657
1658                free(delta_data);
1659                free(external_base);
1660        }
1661
1662        if (final_type)
1663                *final_type = type;
1664        if (final_size)
1665                *final_size = size;
1666
1667out:
1668        unuse_pack(&w_curs);
1669
1670        if (delta_stack != small_delta_stack)
1671                free(delta_stack);
1672
1673        return data;
1674}
1675
1676int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result)
1677{
1678        const unsigned char *index_fanout = p->index_data;
1679        const unsigned char *index_lookup;
1680        int index_lookup_width;
1681
1682        if (!index_fanout)
1683                BUG("bsearch_pack called without a valid pack-index");
1684
1685        index_lookup = index_fanout + 4 * 256;
1686        if (p->index_version == 1) {
1687                index_lookup_width = 24;
1688                index_lookup += 4;
1689        } else {
1690                index_lookup_width = 20;
1691                index_fanout += 8;
1692                index_lookup += 8;
1693        }
1694
1695        return bsearch_hash(oid->hash, (const uint32_t*)index_fanout,
1696                            index_lookup, index_lookup_width, result);
1697}
1698
1699const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1700                                            uint32_t n)
1701{
1702        const unsigned char *index = p->index_data;
1703        if (!index) {
1704                if (open_pack_index(p))
1705                        return NULL;
1706                index = p->index_data;
1707        }
1708        if (n >= p->num_objects)
1709                return NULL;
1710        index += 4 * 256;
1711        if (p->index_version == 1) {
1712                return index + 24 * n + 4;
1713        } else {
1714                index += 8;
1715                return index + 20 * n;
1716        }
1717}
1718
1719const struct object_id *nth_packed_object_oid(struct object_id *oid,
1720                                              struct packed_git *p,
1721                                              uint32_t n)
1722{
1723        const unsigned char *hash = nth_packed_object_sha1(p, n);
1724        if (!hash)
1725                return NULL;
1726        hashcpy(oid->hash, hash);
1727        return oid;
1728}
1729
1730void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1731{
1732        const unsigned char *ptr = vptr;
1733        const unsigned char *start = p->index_data;
1734        const unsigned char *end = start + p->index_size;
1735        if (ptr < start)
1736                die(_("offset before start of pack index for %s (corrupt index?)"),
1737                    p->pack_name);
1738        /* No need to check for underflow; .idx files must be at least 8 bytes */
1739        if (ptr >= end - 8)
1740                die(_("offset beyond end of pack index for %s (truncated index?)"),
1741                    p->pack_name);
1742}
1743
1744off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1745{
1746        const unsigned char *index = p->index_data;
1747        index += 4 * 256;
1748        if (p->index_version == 1) {
1749                return ntohl(*((uint32_t *)(index + 24 * n)));
1750        } else {
1751                uint32_t off;
1752                index += 8 + p->num_objects * (20 + 4);
1753                off = ntohl(*((uint32_t *)(index + 4 * n)));
1754                if (!(off & 0x80000000))
1755                        return off;
1756                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1757                check_pack_index_ptr(p, index);
1758                return get_be64(index);
1759        }
1760}
1761
1762off_t find_pack_entry_one(const unsigned char *sha1,
1763                                  struct packed_git *p)
1764{
1765        const unsigned char *index = p->index_data;
1766        struct object_id oid;
1767        uint32_t result;
1768
1769        if (!index) {
1770                if (open_pack_index(p))
1771                        return 0;
1772        }
1773
1774        hashcpy(oid.hash, sha1);
1775        if (bsearch_pack(&oid, p, &result))
1776                return nth_packed_object_offset(p, result);
1777        return 0;
1778}
1779
1780int is_pack_valid(struct packed_git *p)
1781{
1782        /* An already open pack is known to be valid. */
1783        if (p->pack_fd != -1)
1784                return 1;
1785
1786        /* If the pack has one window completely covering the
1787         * file size, the pack is known to be valid even if
1788         * the descriptor is not currently open.
1789         */
1790        if (p->windows) {
1791                struct pack_window *w = p->windows;
1792
1793                if (!w->offset && w->len == p->pack_size)
1794                        return 1;
1795        }
1796
1797        /* Force the pack to open to prove its valid. */
1798        return !open_packed_git(p);
1799}
1800
1801struct packed_git *find_sha1_pack(const unsigned char *sha1,
1802                                  struct packed_git *packs)
1803{
1804        struct packed_git *p;
1805
1806        for (p = packs; p; p = p->next) {
1807                if (find_pack_entry_one(sha1, p))
1808                        return p;
1809        }
1810        return NULL;
1811
1812}
1813
1814static int fill_pack_entry(const unsigned char *sha1,
1815                           struct pack_entry *e,
1816                           struct packed_git *p)
1817{
1818        off_t offset;
1819
1820        if (p->num_bad_objects) {
1821                unsigned i;
1822                for (i = 0; i < p->num_bad_objects; i++)
1823                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
1824                                return 0;
1825        }
1826
1827        offset = find_pack_entry_one(sha1, p);
1828        if (!offset)
1829                return 0;
1830
1831        /*
1832         * We are about to tell the caller where they can locate the
1833         * requested object.  We better make sure the packfile is
1834         * still here and can be accessed before supplying that
1835         * answer, as it may have been deleted since the index was
1836         * loaded!
1837         */
1838        if (!is_pack_valid(p))
1839                return 0;
1840        e->offset = offset;
1841        e->p = p;
1842        hashcpy(e->sha1, sha1);
1843        return 1;
1844}
1845
1846int find_pack_entry(struct repository *r, const unsigned char *sha1, struct pack_entry *e)
1847{
1848        struct list_head *pos;
1849
1850        prepare_packed_git(r);
1851        if (!r->objects->packed_git)
1852                return 0;
1853
1854        list_for_each(pos, &r->objects->packed_git_mru) {
1855                struct packed_git *p = list_entry(pos, struct packed_git, mru);
1856                if (fill_pack_entry(sha1, e, p)) {
1857                        list_move(&p->mru, &r->objects->packed_git_mru);
1858                        return 1;
1859                }
1860        }
1861        return 0;
1862}
1863
1864int has_sha1_pack(const unsigned char *sha1)
1865{
1866        struct pack_entry e;
1867        return find_pack_entry(the_repository, sha1, &e);
1868}
1869
1870int has_pack_index(const unsigned char *sha1)
1871{
1872        struct stat st;
1873        if (stat(sha1_pack_index_name(sha1), &st))
1874                return 0;
1875        return 1;
1876}
1877
1878int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
1879{
1880        uint32_t i;
1881        int r = 0;
1882
1883        for (i = 0; i < p->num_objects; i++) {
1884                struct object_id oid;
1885
1886                if (!nth_packed_object_oid(&oid, p, i))
1887                        return error("unable to get sha1 of object %u in %s",
1888                                     i, p->pack_name);
1889
1890                r = cb(&oid, p, i, data);
1891                if (r)
1892                        break;
1893        }
1894        return r;
1895}
1896
1897int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
1898{
1899        struct packed_git *p;
1900        int r = 0;
1901        int pack_errors = 0;
1902
1903        prepare_packed_git(the_repository);
1904        for (p = the_repository->objects->packed_git; p; p = p->next) {
1905                if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
1906                        continue;
1907                if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
1908                    !p->pack_promisor)
1909                        continue;
1910                if (open_pack_index(p)) {
1911                        pack_errors = 1;
1912                        continue;
1913                }
1914                r = for_each_object_in_pack(p, cb, data);
1915                if (r)
1916                        break;
1917        }
1918        return r ? r : pack_errors;
1919}
1920
1921static int add_promisor_object(const struct object_id *oid,
1922                               struct packed_git *pack,
1923                               uint32_t pos,
1924                               void *set_)
1925{
1926        struct oidset *set = set_;
1927        struct object *obj = parse_object(oid);
1928        if (!obj)
1929                return 1;
1930
1931        oidset_insert(set, oid);
1932
1933        /*
1934         * If this is a tree, commit, or tag, the objects it refers
1935         * to are also promisor objects. (Blobs refer to no objects->)
1936         */
1937        if (obj->type == OBJ_TREE) {
1938                struct tree *tree = (struct tree *)obj;
1939                struct tree_desc desc;
1940                struct name_entry entry;
1941                if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
1942                        /*
1943                         * Error messages are given when packs are
1944                         * verified, so do not print any here.
1945                         */
1946                        return 0;
1947                while (tree_entry_gently(&desc, &entry))
1948                        oidset_insert(set, entry.oid);
1949        } else if (obj->type == OBJ_COMMIT) {
1950                struct commit *commit = (struct commit *) obj;
1951                struct commit_list *parents = commit->parents;
1952
1953                oidset_insert(set, get_commit_tree_oid(commit));
1954                for (; parents; parents = parents->next)
1955                        oidset_insert(set, &parents->item->object.oid);
1956        } else if (obj->type == OBJ_TAG) {
1957                struct tag *tag = (struct tag *) obj;
1958                oidset_insert(set, &tag->tagged->oid);
1959        }
1960        return 0;
1961}
1962
1963int is_promisor_object(const struct object_id *oid)
1964{
1965        static struct oidset promisor_objects;
1966        static int promisor_objects_prepared;
1967
1968        if (!promisor_objects_prepared) {
1969                if (repository_format_partial_clone) {
1970                        for_each_packed_object(add_promisor_object,
1971                                               &promisor_objects,
1972                                               FOR_EACH_OBJECT_PROMISOR_ONLY);
1973                }
1974                promisor_objects_prepared = 1;
1975        }
1976        return oidset_contains(&promisor_objects, oid);
1977}