git.oblomov.eu Git - git/blob - packfile.c

   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 #include "midx.h"
  19 #include "commit-graph.h"
  20
  21 char *odb_pack_name(struct strbuf *buf,
  22                     const unsigned char *sha1,
  23                     const char *ext)
  24 {
  25         strbuf_reset(buf);
  26         strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
  27                     sha1_to_hex(sha1), ext);
  28         return buf->buf;
  29 }
  30
  31 char *sha1_pack_name(const unsigned char *sha1)
  32 {
  33         static struct strbuf buf = STRBUF_INIT;
  34         return odb_pack_name(&buf, sha1, "pack");
  35 }
  36
  37 char *sha1_pack_index_name(const unsigned char *sha1)
  38 {
  39         static struct strbuf buf = STRBUF_INIT;
  40         return odb_pack_name(&buf, sha1, "idx");
  41 }
  42
  43 static unsigned int pack_used_ctr;
  44 static unsigned int pack_mmap_calls;
  45 static unsigned int peak_pack_open_windows;
  46 static unsigned int pack_open_windows;
  47 static unsigned int pack_open_fds;
  48 static unsigned int pack_max_fds;
  49 static size_t peak_pack_mapped;
  50 static size_t pack_mapped;
  51
  52 #define SZ_FMT PRIuMAX
  53 static inline uintmax_t sz_fmt(size_t s) { return s; }
  54
  55 void pack_report(void)
  56 {
  57         fprintf(stderr,
  58                 "pack_report: getpagesize()            = %10" SZ_FMT "\n"
  59                 "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
  60                 "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
  61                 sz_fmt(getpagesize()),
  62                 sz_fmt(packed_git_window_size),
  63                 sz_fmt(packed_git_limit));
  64         fprintf(stderr,
  65                 "pack_report: pack_used_ctr            = %10u\n"
  66                 "pack_report: pack_mmap_calls          = %10u\n"
  67                 "pack_report: pack_open_windows        = %10u / %10u\n"
  68                 "pack_report: pack_mapped              = "
  69                         "%10" SZ_FMT " / %10" SZ_FMT "\n",
  70                 pack_used_ctr,
  71                 pack_mmap_calls,
  72                 pack_open_windows, peak_pack_open_windows,
  73                 sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
  74 }
  75
  76 /*
  77  * Open and mmap the index file at path, perform a couple of
  78  * consistency checks, then record its information to p.  Return 0 on
  79  * success.
  80  */
  81 static int check_packed_git_idx(const char *path, struct packed_git *p)
  82 {
  83         void *idx_map;
  84         size_t idx_size;
  85         int fd = git_open(path), ret;
  86         struct stat st;
  87         const unsigned int hashsz = the_hash_algo->rawsz;
  88
  89         if (fd < 0)
  90                 return -1;
  91         if (fstat(fd, &st)) {
  92                 close(fd);
  93                 return -1;
  94         }
  95         idx_size = xsize_t(st.st_size);
  96         if (idx_size < 4 * 256 + hashsz + hashsz) {
  97                 close(fd);
  98                 return error("index file %s is too small", path);
  99         }
 100         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 101         close(fd);
 102
 103         ret = load_idx(path, hashsz, idx_map, idx_size, p);
 104
 105         if (ret)
 106                 munmap(idx_map, idx_size);
 107
 108         return ret;
 109 }
 110
 111 int load_idx(const char *path, const unsigned int hashsz, void *idx_map,
 112              size_t idx_size, struct packed_git *p)
 113 {
 114         struct pack_idx_header *hdr = idx_map;
 115         uint32_t version, nr, i, *index;
 116
 117         if (idx_size < 4 * 256 + hashsz + hashsz)
 118                 return error("index file %s is too small", path);
 119         if (idx_map == NULL)
 120                 return error("empty data");
 121
 122         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 123                 version = ntohl(hdr->idx_version);
 124                 if (version < 2 || version > 2)
 125                         return error("index file %s is version %"PRIu32
 126                                      " and is not supported by this binary"
 127                                      " (try upgrading GIT to a newer version)",
 128                                      path, version);
 129         } else
 130                 version = 1;
 131
 132         nr = 0;
 133         index = idx_map;
 134         if (version > 1)
 135                 index += 2;  /* skip index header */
 136         for (i = 0; i < 256; i++) {
 137                 uint32_t n = ntohl(index[i]);
 138                 if (n < nr)
 139                         return error("non-monotonic index %s", path);
 140                 nr = n;
 141         }
 142
 143         if (version == 1) {
 144                 /*
 145                  * Total size:
 146                  *  - 256 index entries 4 bytes each
 147                  *  - 24-byte entries * nr (object ID + 4-byte offset)
 148                  *  - hash of the packfile
 149                  *  - file checksum
 150                  */
 151                 if (idx_size != 4 * 256 + nr * (hashsz + 4) + hashsz + hashsz)
 152                         return error("wrong index v1 file size in %s", path);
 153         } else if (version == 2) {
 154                 /*
 155                  * Minimum size:
 156                  *  - 8 bytes of header
 157                  *  - 256 index entries 4 bytes each
 158                  *  - object ID entry * nr
 159                  *  - 4-byte crc entry * nr
 160                  *  - 4-byte offset entry * nr
 161                  *  - hash of the packfile
 162                  *  - file checksum
 163                  * And after the 4-byte offset table might be a
 164                  * variable sized table containing 8-byte entries
 165                  * for offsets larger than 2^31.
 166                  */
 167                 unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;
 168                 unsigned long max_size = min_size;
 169                 if (nr)
 170                         max_size += (nr - 1)*8;
 171                 if (idx_size < min_size || idx_size > max_size)
 172                         return error("wrong index v2 file size in %s", path);
 173                 if (idx_size != min_size &&
 174                     /*
 175                      * make sure we can deal with large pack offsets.
 176                      * 31-bit signed offset won't be enough, neither
 177                      * 32-bit unsigned one will be.
 178                      */
 179                     (sizeof(off_t) <= 4))
 180                         return error("pack too large for current definition of off_t in %s", path);
 181         }
 182
 183         p->index_version = version;
 184         p->index_data = idx_map;
 185         p->index_size = idx_size;
 186         p->num_objects = nr;
 187         return 0;
 188 }
 189
 190 int open_pack_index(struct packed_git *p)
 191 {
 192         char *idx_name;
 193         size_t len;
 194         int ret;
 195
 196         if (p->index_data)
 197                 return 0;
 198
 199         if (!strip_suffix(p->pack_name, ".pack", &len))
 200                 BUG("pack_name does not end in .pack");
 201         idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
 202         ret = check_packed_git_idx(idx_name, p);
 203         free(idx_name);
 204         return ret;
 205 }
 206
 207 uint32_t get_pack_fanout(struct packed_git *p, uint32_t value)
 208 {
 209         const uint32_t *level1_ofs = p->index_data;
 210
 211         if (!level1_ofs) {
 212                 if (open_pack_index(p))
 213                         return 0;
 214                 level1_ofs = p->index_data;
 215         }
 216
 217         if (p->index_version > 1) {
 218                 level1_ofs += 2;
 219         }
 220
 221         return ntohl(level1_ofs[value]);
 222 }
 223
 224 static struct packed_git *alloc_packed_git(int extra)
 225 {
 226         struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
 227         memset(p, 0, sizeof(*p));
 228         p->pack_fd = -1;
 229         return p;
 230 }
 231
 232 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 233 {
 234         const char *path = sha1_pack_name(sha1);
 235         size_t alloc = st_add(strlen(path), 1);
 236         struct packed_git *p = alloc_packed_git(alloc);
 237
 238         memcpy(p->pack_name, path, alloc); /* includes NUL */
 239         hashcpy(p->hash, sha1);
 240         if (check_packed_git_idx(idx_path, p)) {
 241                 free(p);
 242                 return NULL;
 243         }
 244
 245         return p;
 246 }
 247
 248 static void scan_windows(struct packed_git *p,
 249         struct packed_git **lru_p,
 250         struct pack_window **lru_w,
 251         struct pack_window **lru_l)
 252 {
 253         struct pack_window *w, *w_l;
 254
 255         for (w_l = NULL, w = p->windows; w; w = w->next) {
 256                 if (!w->inuse_cnt) {
 257                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 258                                 *lru_p = p;
 259                                 *lru_w = w;
 260                                 *lru_l = w_l;
 261                         }
 262                 }
 263                 w_l = w;
 264         }
 265 }
 266
 267 static int unuse_one_window(struct packed_git *current)
 268 {
 269         struct packed_git *p, *lru_p = NULL;
 270         struct pack_window *lru_w = NULL, *lru_l = NULL;
 271
 272         if (current)
 273                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 274         for (p = the_repository->objects->packed_git; p; p = p->next)
 275                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 276         if (lru_p) {
 277                 munmap(lru_w->base, lru_w->len);
 278                 pack_mapped -= lru_w->len;
 279                 if (lru_l)
 280                         lru_l->next = lru_w->next;
 281                 else
 282                         lru_p->windows = lru_w->next;
 283                 free(lru_w);
 284                 pack_open_windows--;
 285                 return 1;
 286         }
 287         return 0;
 288 }
 289
 290 void release_pack_memory(size_t need)
 291 {
 292         size_t cur = pack_mapped;
 293         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 294                 ; /* nothing */
 295 }
 296
 297 void close_pack_windows(struct packed_git *p)
 298 {
 299         while (p->windows) {
 300                 struct pack_window *w = p->windows;
 301
 302                 if (w->inuse_cnt)
 303                         die("pack '%s' still has open windows to it",
 304                             p->pack_name);
 305                 munmap(w->base, w->len);
 306                 pack_mapped -= w->len;
 307                 pack_open_windows--;
 308                 p->windows = w->next;
 309                 free(w);
 310         }
 311 }
 312
 313 int close_pack_fd(struct packed_git *p)
 314 {
 315         if (p->pack_fd < 0)
 316                 return 0;
 317
 318         close(p->pack_fd);
 319         pack_open_fds--;
 320         p->pack_fd = -1;
 321
 322         return 1;
 323 }
 324
 325 void close_pack_index(struct packed_git *p)
 326 {
 327         if (p->index_data) {
 328                 munmap((void *)p->index_data, p->index_size);
 329                 p->index_data = NULL;
 330         }
 331 }
 332
 333 void close_pack(struct packed_git *p)
 334 {
 335         close_pack_windows(p);
 336         close_pack_fd(p);
 337         close_pack_index(p);
 338 }
 339
 340 void close_object_store(struct raw_object_store *o)
 341 {
 342         struct packed_git *p;
 343
 344         for (p = o->packed_git; p; p = p->next)
 345                 if (p->do_not_close)
 346                         BUG("want to close pack marked 'do-not-close'");
 347                 else
 348                         close_pack(p);
 349
 350         if (o->multi_pack_index) {
 351                 close_midx(o->multi_pack_index);
 352                 o->multi_pack_index = NULL;
 353         }
 354
 355         close_commit_graph(o);
 356 }
 357
 358 void unlink_pack_path(const char *pack_name, int force_delete)
 359 {
 360         static const char *exts[] = {".pack", ".idx", ".keep", ".bitmap", ".promisor"};
 361         int i;
 362         struct strbuf buf = STRBUF_INIT;
 363         size_t plen;
 364
 365         strbuf_addstr(&buf, pack_name);
 366         strip_suffix_mem(buf.buf, &buf.len, ".pack");
 367         plen = buf.len;
 368
 369         if (!force_delete) {
 370                 strbuf_addstr(&buf, ".keep");
 371                 if (!access(buf.buf, F_OK)) {
 372                         strbuf_release(&buf);
 373                         return;
 374                 }
 375         }
 376
 377         for (i = 0; i < ARRAY_SIZE(exts); i++) {
 378                 strbuf_setlen(&buf, plen);
 379                 strbuf_addstr(&buf, exts[i]);
 380                 unlink(buf.buf);
 381         }
 382
 383         strbuf_release(&buf);
 384 }
 385
 386 /*
 387  * The LRU pack is the one with the oldest MRU window, preferring packs
 388  * with no used windows, or the oldest mtime if it has no windows allocated.
 389  */
 390 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 391 {
 392         struct pack_window *w, *this_mru_w;
 393         int has_windows_inuse = 0;
 394
 395         /*
 396          * Reject this pack if it has windows and the previously selected
 397          * one does not.  If this pack does not have windows, reject
 398          * it if the pack file is newer than the previously selected one.
 399          */
 400         if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 401                 return;
 402
 403         for (w = this_mru_w = p->windows; w; w = w->next) {
 404                 /*
 405                  * Reject this pack if any of its windows are in use,
 406                  * but the previously selected pack did not have any
 407                  * inuse windows.  Otherwise, record that this pack
 408                  * has windows in use.
 409                  */
 410                 if (w->inuse_cnt) {
 411                         if (*accept_windows_inuse)
 412                                 has_windows_inuse = 1;
 413                         else
 414                                 return;
 415                 }
 416
 417                 if (w->last_used > this_mru_w->last_used)
 418                         this_mru_w = w;
 419
 420                 /*
 421                  * Reject this pack if it has windows that have been
 422                  * used more recently than the previously selected pack.
 423                  * If the previously selected pack had windows inuse and
 424                  * we have not encountered a window in this pack that is
 425                  * inuse, skip this check since we prefer a pack with no
 426                  * inuse windows to one that has inuse windows.
 427                  */
 428                 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 429                     this_mru_w->last_used > (*mru_w)->last_used)
 430                         return;
 431         }
 432
 433         /*
 434          * Select this pack.
 435          */
 436         *mru_w = this_mru_w;
 437         *lru_p = p;
 438         *accept_windows_inuse = has_windows_inuse;
 439 }
 440
 441 static int close_one_pack(void)
 442 {
 443         struct packed_git *p, *lru_p = NULL;
 444         struct pack_window *mru_w = NULL;
 445         int accept_windows_inuse = 1;
 446
 447         for (p = the_repository->objects->packed_git; p; p = p->next) {
 448                 if (p->pack_fd == -1)
 449                         continue;
 450                 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 451         }
 452
 453         if (lru_p)
 454                 return close_pack_fd(lru_p);
 455
 456         return 0;
 457 }
 458
 459 static unsigned int get_max_fd_limit(void)
 460 {
 461 #ifdef RLIMIT_NOFILE
 462         {
 463                 struct rlimit lim;
 464
 465                 if (!getrlimit(RLIMIT_NOFILE, &lim))
 466                         return lim.rlim_cur;
 467         }
 468 #endif
 469
 470 #ifdef _SC_OPEN_MAX
 471         {
 472                 long open_max = sysconf(_SC_OPEN_MAX);
 473                 if (0 < open_max)
 474                         return open_max;
 475                 /*
 476                  * Otherwise, we got -1 for one of the two
 477                  * reasons:
 478                  *
 479                  * (1) sysconf() did not understand _SC_OPEN_MAX
 480                  *     and signaled an error with -1; or
 481                  * (2) sysconf() said there is no limit.
 482                  *
 483                  * We _could_ clear errno before calling sysconf() to
 484                  * tell these two cases apart and return a huge number
 485                  * in the latter case to let the caller cap it to a
 486                  * value that is not so selfish, but letting the
 487                  * fallback OPEN_MAX codepath take care of these cases
 488                  * is a lot simpler.
 489                  */
 490         }
 491 #endif
 492
 493 #ifdef OPEN_MAX
 494         return OPEN_MAX;
 495 #else
 496         return 1; /* see the caller ;-) */
 497 #endif
 498 }
 499
 500 const char *pack_basename(struct packed_git *p)
 501 {
 502         const char *ret = strrchr(p->pack_name, '/');
 503         if (ret)
 504                 ret = ret + 1; /* skip past slash */
 505         else
 506                 ret = p->pack_name; /* we only have a base */
 507         return ret;
 508 }
 509
 510 /*
 511  * Do not call this directly as this leaks p->pack_fd on error return;
 512  * call open_packed_git() instead.
 513  */
 514 static int open_packed_git_1(struct packed_git *p)
 515 {
 516         struct stat st;
 517         struct pack_header hdr;
 518         unsigned char hash[GIT_MAX_RAWSZ];
 519         unsigned char *idx_hash;
 520         long fd_flag;
 521         ssize_t read_result;
 522         const unsigned hashsz = the_hash_algo->rawsz;
 523
 524         if (!p->index_data) {
 525                 struct multi_pack_index *m;
 526                 const char *pack_name = pack_basename(p);
 527
 528                 for (m = the_repository->objects->multi_pack_index;
 529                      m; m = m->next) {
 530                         if (midx_contains_pack(m, pack_name))
 531                                 break;
 532                 }
 533
 534                 if (!m && open_pack_index(p))
 535                         return error("packfile %s index unavailable", p->pack_name);
 536         }
 537
 538         if (!pack_max_fds) {
 539                 unsigned int max_fds = get_max_fd_limit();
 540
 541                 /* Save 3 for stdin/stdout/stderr, 22 for work */
 542                 if (25 < max_fds)
 543                         pack_max_fds = max_fds - 25;
 544                 else
 545                         pack_max_fds = 1;
 546         }
 547
 548         while (pack_max_fds <= pack_open_fds && close_one_pack())
 549                 ; /* nothing */
 550
 551         p->pack_fd = git_open(p->pack_name);
 552         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 553                 return -1;
 554         pack_open_fds++;
 555
 556         /* If we created the struct before we had the pack we lack size. */
 557         if (!p->pack_size) {
 558                 if (!S_ISREG(st.st_mode))
 559                         return error("packfile %s not a regular file", p->pack_name);
 560                 p->pack_size = st.st_size;
 561         } else if (p->pack_size != st.st_size)
 562                 return error("packfile %s size changed", p->pack_name);
 563
 564         /* We leave these file descriptors open with sliding mmap;
 565          * there is no point keeping them open across exec(), though.
 566          */
 567         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 568         if (fd_flag < 0)
 569                 return error("cannot determine file descriptor flags");
 570         fd_flag |= FD_CLOEXEC;
 571         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 572                 return error("cannot set FD_CLOEXEC");
 573
 574         /* Verify we recognize this pack file format. */
 575         read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
 576         if (read_result < 0)
 577                 return error_errno("error reading from %s", p->pack_name);
 578         if (read_result != sizeof(hdr))
 579                 return error("file %s is far too short to be a packfile", p->pack_name);
 580         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 581                 return error("file %s is not a GIT packfile", p->pack_name);
 582         if (!pack_version_ok(hdr.hdr_version))
 583                 return error("packfile %s is version %"PRIu32" and not"
 584                         " supported (try upgrading GIT to a newer version)",
 585                         p->pack_name, ntohl(hdr.hdr_version));
 586
 587         /* Skip index checking if in multi-pack-index */
 588         if (!p->index_data)
 589                 return 0;
 590
 591         /* Verify the pack matches its index. */
 592         if (p->num_objects != ntohl(hdr.hdr_entries))
 593                 return error("packfile %s claims to have %"PRIu32" objects"
 594                              " while index indicates %"PRIu32" objects",
 595                              p->pack_name, ntohl(hdr.hdr_entries),
 596                              p->num_objects);
 597         if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
 598                 return error("end of packfile %s is unavailable", p->pack_name);
 599         read_result = read_in_full(p->pack_fd, hash, hashsz);
 600         if (read_result < 0)
 601                 return error_errno("error reading from %s", p->pack_name);
 602         if (read_result != hashsz)
 603                 return error("packfile %s signature is unavailable", p->pack_name);
 604         idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
 605         if (!hasheq(hash, idx_hash))
 606                 return error("packfile %s does not match index", p->pack_name);
 607         return 0;
 608 }
 609
 610 static int open_packed_git(struct packed_git *p)
 611 {
 612         if (!open_packed_git_1(p))
 613                 return 0;
 614         close_pack_fd(p);
 615         return -1;
 616 }
 617
 618 static int in_window(struct pack_window *win, off_t offset)
 619 {
 620         /* We must promise at least one full hash after the
 621          * offset is available from this window, otherwise the offset
 622          * is not actually in this window and a different window (which
 623          * has that one hash excess) must be used.  This is to support
 624          * the object header and delta base parsing routines below.
 625          */
 626         off_t win_off = win->offset;
 627         return win_off <= offset
 628                 && (offset + the_hash_algo->rawsz) <= (win_off + win->len);
 629 }
 630
 631 unsigned char *use_pack(struct packed_git *p,
 632                 struct pack_window **w_cursor,
 633                 off_t offset,
 634                 unsigned long *left)
 635 {
 636         struct pack_window *win = *w_cursor;
 637
 638         /* Since packfiles end in a hash of their content and it's
 639          * pointless to ask for an offset into the middle of that
 640          * hash, and the in_window function above wouldn't match
 641          * don't allow an offset too close to the end of the file.
 642          */
 643         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 644                 die("packfile %s cannot be accessed", p->pack_name);
 645         if (offset > (p->pack_size - the_hash_algo->rawsz))
 646                 die("offset beyond end of packfile (truncated pack?)");
 647         if (offset < 0)
 648                 die(_("offset before end of packfile (broken .idx?)"));
 649
 650         if (!win || !in_window(win, offset)) {
 651                 if (win)
 652                         win->inuse_cnt--;
 653                 for (win = p->windows; win; win = win->next) {
 654                         if (in_window(win, offset))
 655                                 break;
 656                 }
 657                 if (!win) {
 658                         size_t window_align = packed_git_window_size / 2;
 659                         off_t len;
 660
 661                         if (p->pack_fd == -1 && open_packed_git(p))
 662                                 die("packfile %s cannot be accessed", p->pack_name);
 663
 664                         win = xcalloc(1, sizeof(*win));
 665                         win->offset = (offset / window_align) * window_align;
 666                         len = p->pack_size - win->offset;
 667                         if (len > packed_git_window_size)
 668                                 len = packed_git_window_size;
 669                         win->len = (size_t)len;
 670                         pack_mapped += win->len;
 671                         while (packed_git_limit < pack_mapped
 672                                 && unuse_one_window(p))
 673                                 ; /* nothing */
 674                         win->base = xmmap_gently(NULL, win->len,
 675                                 PROT_READ, MAP_PRIVATE,
 676                                 p->pack_fd, win->offset);
 677                         if (win->base == MAP_FAILED)
 678                                 die_errno("packfile %s cannot be mapped",
 679                                           p->pack_name);
 680                         if (!win->offset && win->len == p->pack_size
 681                                 && !p->do_not_close)
 682                                 close_pack_fd(p);
 683                         pack_mmap_calls++;
 684                         pack_open_windows++;
 685                         if (pack_mapped > peak_pack_mapped)
 686                                 peak_pack_mapped = pack_mapped;
 687                         if (pack_open_windows > peak_pack_open_windows)
 688                                 peak_pack_open_windows = pack_open_windows;
 689                         win->next = p->windows;
 690                         p->windows = win;
 691                 }
 692         }
 693         if (win != *w_cursor) {
 694                 win->last_used = pack_used_ctr++;
 695                 win->inuse_cnt++;
 696                 *w_cursor = win;
 697         }
 698         offset -= win->offset;
 699         if (left)
 700                 *left = win->len - xsize_t(offset);
 701         return win->base + offset;
 702 }
 703
 704 void unuse_pack(struct pack_window **w_cursor)
 705 {
 706         struct pack_window *w = *w_cursor;
 707         if (w) {
 708                 w->inuse_cnt--;
 709                 *w_cursor = NULL;
 710         }
 711 }
 712
 713 static void try_to_free_pack_memory(size_t size)
 714 {
 715         release_pack_memory(size);
 716 }
 717
 718 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
 719 {
 720         static int have_set_try_to_free_routine;
 721         struct stat st;
 722         size_t alloc;
 723         struct packed_git *p;
 724
 725         if (!have_set_try_to_free_routine) {
 726                 have_set_try_to_free_routine = 1;
 727                 set_try_to_free_routine(try_to_free_pack_memory);
 728         }
 729
 730         /*
 731          * Make sure a corresponding .pack file exists and that
 732          * the index looks sane.
 733          */
 734         if (!strip_suffix_mem(path, &path_len, ".idx"))
 735                 return NULL;
 736
 737         /*
 738          * ".promisor" is long enough to hold any suffix we're adding (and
 739          * the use xsnprintf double-checks that)
 740          */
 741         alloc = st_add3(path_len, strlen(".promisor"), 1);
 742         p = alloc_packed_git(alloc);
 743         memcpy(p->pack_name, path, path_len);
 744
 745         xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
 746         if (!access(p->pack_name, F_OK))
 747                 p->pack_keep = 1;
 748
 749         xsnprintf(p->pack_name + path_len, alloc - path_len, ".promisor");
 750         if (!access(p->pack_name, F_OK))
 751                 p->pack_promisor = 1;
 752
 753         xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
 754         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 755                 free(p);
 756                 return NULL;
 757         }
 758
 759         /* ok, it looks sane as far as we can check without
 760          * actually mapping the pack file.
 761          */
 762         p->pack_size = st.st_size;
 763         p->pack_local = local;
 764         p->mtime = st.st_mtime;
 765         if (path_len < the_hash_algo->hexsz ||
 766             get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->hash))
 767                 hashclr(p->hash);
 768         return p;
 769 }
 770
 771 void install_packed_git(struct repository *r, struct packed_git *pack)
 772 {
 773         if (pack->pack_fd != -1)
 774                 pack_open_fds++;
 775
 776         pack->next = r->objects->packed_git;
 777         r->objects->packed_git = pack;
 778 }
 779
 780 void (*report_garbage)(unsigned seen_bits, const char *path);
 781
 782 static void report_helper(const struct string_list *list,
 783                           int seen_bits, int first, int last)
 784 {
 785         if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
 786                 return;
 787
 788         for (; first < last; first++)
 789                 report_garbage(seen_bits, list->items[first].string);
 790 }
 791
 792 static void report_pack_garbage(struct string_list *list)
 793 {
 794         int i, baselen = -1, first = 0, seen_bits = 0;
 795
 796         if (!report_garbage)
 797                 return;
 798
 799         string_list_sort(list);
 800
 801         for (i = 0; i < list->nr; i++) {
 802                 const char *path = list->items[i].string;
 803                 if (baselen != -1 &&
 804                     strncmp(path, list->items[first].string, baselen)) {
 805                         report_helper(list, seen_bits, first, i);
 806                         baselen = -1;
 807                         seen_bits = 0;
 808                 }
 809                 if (baselen == -1) {
 810                         const char *dot = strrchr(path, '.');
 811                         if (!dot) {
 812                                 report_garbage(PACKDIR_FILE_GARBAGE, path);
 813                                 continue;
 814                         }
 815                         baselen = dot - path + 1;
 816                         first = i;
 817                 }
 818                 if (!strcmp(path + baselen, "pack"))
 819                         seen_bits |= 1;
 820                 else if (!strcmp(path + baselen, "idx"))
 821                         seen_bits |= 2;
 822         }
 823         report_helper(list, seen_bits, first, list->nr);
 824 }
 825
 826 void for_each_file_in_pack_dir(const char *objdir,
 827                                each_file_in_pack_dir_fn fn,
 828                                void *data)
 829 {
 830         struct strbuf path = STRBUF_INIT;
 831         size_t dirnamelen;
 832         DIR *dir;
 833         struct dirent *de;
 834
 835         strbuf_addstr(&path, objdir);
 836         strbuf_addstr(&path, "/pack");
 837         dir = opendir(path.buf);
 838         if (!dir) {
 839                 if (errno != ENOENT)
 840                         error_errno("unable to open object pack directory: %s",
 841                                     path.buf);
 842                 strbuf_release(&path);
 843                 return;
 844         }
 845         strbuf_addch(&path, '/');
 846         dirnamelen = path.len;
 847         while ((de = readdir(dir)) != NULL) {
 848                 if (is_dot_or_dotdot(de->d_name))
 849                         continue;
 850
 851                 strbuf_setlen(&path, dirnamelen);
 852                 strbuf_addstr(&path, de->d_name);
 853
 854                 fn(path.buf, path.len, de->d_name, data);
 855         }
 856
 857         closedir(dir);
 858         strbuf_release(&path);
 859 }
 860
 861 struct prepare_pack_data {
 862         struct repository *r;
 863         struct string_list *garbage;
 864         int local;
 865         struct multi_pack_index *m;
 866 };
 867
 868 static void prepare_pack(const char *full_name, size_t full_name_len,
 869                          const char *file_name, void *_data)
 870 {
 871         struct prepare_pack_data *data = (struct prepare_pack_data *)_data;
 872         struct packed_git *p;
 873         size_t base_len = full_name_len;
 874
 875         if (strip_suffix_mem(full_name, &base_len, ".idx") &&
 876             !(data->m && midx_contains_pack(data->m, file_name))) {
 877                 /* Don't reopen a pack we already have. */
 878                 for (p = data->r->objects->packed_git; p; p = p->next) {
 879                         size_t len;
 880                         if (strip_suffix(p->pack_name, ".pack", &len) &&
 881                             len == base_len &&
 882                             !memcmp(p->pack_name, full_name, len))
 883                                 break;
 884                 }
 885
 886                 if (!p) {
 887                         p = add_packed_git(full_name, full_name_len, data->local);
 888                         if (p)
 889                                 install_packed_git(data->r, p);
 890                 }
 891         }
 892
 893         if (!report_garbage)
 894                 return;
 895
 896         if (!strcmp(file_name, "multi-pack-index"))
 897                 return;
 898         if (ends_with(file_name, ".idx") ||
 899             ends_with(file_name, ".pack") ||
 900             ends_with(file_name, ".bitmap") ||
 901             ends_with(file_name, ".keep") ||
 902             ends_with(file_name, ".promisor"))
 903                 string_list_append(data->garbage, full_name);
 904         else
 905                 report_garbage(PACKDIR_FILE_GARBAGE, full_name);
 906 }
 907
 908 static void prepare_packed_git_one(struct repository *r, char *objdir, int local)
 909 {
 910         struct prepare_pack_data data;
 911         struct string_list garbage = STRING_LIST_INIT_DUP;
 912
 913         data.m = r->objects->multi_pack_index;
 914
 915         /* look for the multi-pack-index for this object directory */
 916         while (data.m && strcmp(data.m->object_dir, objdir))
 917                 data.m = data.m->next;
 918
 919         data.r = r;
 920         data.garbage = &garbage;
 921         data.local = local;
 922
 923         for_each_file_in_pack_dir(objdir, prepare_pack, &data);
 924
 925         report_pack_garbage(data.garbage);
 926         string_list_clear(data.garbage, 0);
 927 }
 928
 929 static void prepare_packed_git(struct repository *r);
 930 /*
 931  * Give a fast, rough count of the number of objects in the repository. This
 932  * ignores loose objects completely. If you have a lot of them, then either
 933  * you should repack because your performance will be awful, or they are
 934  * all unreachable objects about to be pruned, in which case they're not really
 935  * interesting as a measure of repo size in the first place.
 936  */
 937 unsigned long repo_approximate_object_count(struct repository *r)
 938 {
 939         if (!r->objects->approximate_object_count_valid) {
 940                 unsigned long count;
 941                 struct multi_pack_index *m;
 942                 struct packed_git *p;
 943
 944                 prepare_packed_git(r);
 945                 count = 0;
 946                 for (m = get_multi_pack_index(r); m; m = m->next)
 947                         count += m->num_objects;
 948                 for (p = r->objects->packed_git; p; p = p->next) {
 949                         if (open_pack_index(p))
 950                                 continue;
 951                         count += p->num_objects;
 952                 }
 953                 r->objects->approximate_object_count = count;
 954         }
 955         return r->objects->approximate_object_count;
 956 }
 957
 958 static void *get_next_packed_git(const void *p)
 959 {
 960         return ((const struct packed_git *)p)->next;
 961 }
 962
 963 static void set_next_packed_git(void *p, void *next)
 964 {
 965         ((struct packed_git *)p)->next = next;
 966 }
 967
 968 static int sort_pack(const void *a_, const void *b_)
 969 {
 970         const struct packed_git *a = a_;
 971         const struct packed_git *b = b_;
 972         int st;
 973
 974         /*
 975          * Local packs tend to contain objects specific to our
 976          * variant of the project than remote ones.  In addition,
 977          * remote ones could be on a network mounted filesystem.
 978          * Favor local ones for these reasons.
 979          */
 980         st = a->pack_local - b->pack_local;
 981         if (st)
 982                 return -st;
 983
 984         /*
 985          * Younger packs tend to contain more recent objects,
 986          * and more recent objects tend to get accessed more
 987          * often.
 988          */
 989         if (a->mtime < b->mtime)
 990                 return 1;
 991         else if (a->mtime == b->mtime)
 992                 return 0;
 993         return -1;
 994 }
 995
 996 static void rearrange_packed_git(struct repository *r)
 997 {
 998         r->objects->packed_git = llist_mergesort(
 999                 r->objects->packed_git, get_next_packed_git,
1000                 set_next_packed_git, sort_pack);
1001 }
1002
1003 static void prepare_packed_git_mru(struct repository *r)
1004 {
1005         struct packed_git *p;
1006
1007         INIT_LIST_HEAD(&r->objects->packed_git_mru);
1008
1009         for (p = r->objects->packed_git; p; p = p->next)
1010                 list_add_tail(&p->mru, &r->objects->packed_git_mru);
1011 }
1012
1013 static void prepare_packed_git(struct repository *r)
1014 {
1015         struct object_directory *odb;
1016
1017         if (r->objects->packed_git_initialized)
1018                 return;
1019
1020         prepare_alt_odb(r);
1021         for (odb = r->objects->odb; odb; odb = odb->next) {
1022                 int local = (odb == r->objects->odb);
1023                 prepare_multi_pack_index_one(r, odb->path, local);
1024                 prepare_packed_git_one(r, odb->path, local);
1025         }
1026         rearrange_packed_git(r);
1027
1028         prepare_packed_git_mru(r);
1029         r->objects->packed_git_initialized = 1;
1030 }
1031
1032 void reprepare_packed_git(struct repository *r)
1033 {
1034         struct object_directory *odb;
1035
1036         for (odb = r->objects->odb; odb; odb = odb->next)
1037                 odb_clear_loose_cache(odb);
1038
1039         r->objects->approximate_object_count_valid = 0;
1040         r->objects->packed_git_initialized = 0;
1041         prepare_packed_git(r);
1042 }
1043
1044 struct packed_git *get_packed_git(struct repository *r)
1045 {
1046         prepare_packed_git(r);
1047         return r->objects->packed_git;
1048 }
1049
1050 struct multi_pack_index *get_multi_pack_index(struct repository *r)
1051 {
1052         prepare_packed_git(r);
1053         return r->objects->multi_pack_index;
1054 }
1055
1056 struct packed_git *get_all_packs(struct repository *r)
1057 {
1058         struct multi_pack_index *m;
1059
1060         prepare_packed_git(r);
1061         for (m = r->objects->multi_pack_index; m; m = m->next) {
1062                 uint32_t i;
1063                 for (i = 0; i < m->num_packs; i++)
1064                         prepare_midx_pack(r, m, i);
1065         }
1066
1067         return r->objects->packed_git;
1068 }
1069
1070 struct list_head *get_packed_git_mru(struct repository *r)
1071 {
1072         prepare_packed_git(r);
1073         return &r->objects->packed_git_mru;
1074 }
1075
1076 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1077                 unsigned long len, enum object_type *type, unsigned long *sizep)
1078 {
1079         unsigned shift;
1080         unsigned long size, c;
1081         unsigned long used = 0;
1082
1083         c = buf[used++];
1084         *type = (c >> 4) & 7;
1085         size = c & 15;
1086         shift = 4;
1087         while (c & 0x80) {
1088                 if (len <= used || bitsizeof(long) <= shift) {
1089                         error("bad object header");
1090                         size = used = 0;
1091                         break;
1092                 }
1093                 c = buf[used++];
1094                 size += (c & 0x7f) << shift;
1095                 shift += 7;
1096         }
1097         *sizep = size;
1098         return used;
1099 }
1100
1101 unsigned long get_size_from_delta(struct packed_git *p,
1102                                   struct pack_window **w_curs,
1103                                   off_t curpos)
1104 {
1105         const unsigned char *data;
1106         unsigned char delta_head[20], *in;
1107         git_zstream stream;
1108         int st;
1109
1110         memset(&stream, 0, sizeof(stream));
1111         stream.next_out = delta_head;
1112         stream.avail_out = sizeof(delta_head);
1113
1114         git_inflate_init(&stream);
1115         do {
1116                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1117                 stream.next_in = in;
1118                 st = git_inflate(&stream, Z_FINISH);
1119                 curpos += stream.next_in - in;
1120         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1121                  stream.total_out < sizeof(delta_head));
1122         git_inflate_end(&stream);
1123         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1124                 error("delta data unpack-initial failed");
1125                 return 0;
1126         }
1127
1128         /* Examine the initial part of the delta to figure out
1129          * the result size.
1130          */
1131         data = delta_head;
1132
1133         /* ignore base size */
1134         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1135
1136         /* Read the result size */
1137         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1138 }
1139
1140 int unpack_object_header(struct packed_git *p,
1141                          struct pack_window **w_curs,
1142                          off_t *curpos,
1143                          unsigned long *sizep)
1144 {
1145         unsigned char *base;
1146         unsigned long left;
1147         unsigned long used;
1148         enum object_type type;
1149
1150         /* use_pack() assures us we have [base, base + 20) available
1151          * as a range that we can look at.  (Its actually the hash
1152          * size that is assured.)  With our object header encoding
1153          * the maximum deflated object size is 2^137, which is just
1154          * insane, so we know won't exceed what we have been given.
1155          */
1156         base = use_pack(p, w_curs, *curpos, &left);
1157         used = unpack_object_header_buffer(base, left, &type, sizep);
1158         if (!used) {
1159                 type = OBJ_BAD;
1160         } else
1161                 *curpos += used;
1162
1163         return type;
1164 }
1165
1166 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1167 {
1168         unsigned i;
1169         const unsigned hashsz = the_hash_algo->rawsz;
1170         for (i = 0; i < p->num_bad_objects; i++)
1171                 if (hasheq(sha1, p->bad_object_sha1 + hashsz * i))
1172                         return;
1173         p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1174                                       st_mult(GIT_MAX_RAWSZ,
1175                                               st_add(p->num_bad_objects, 1)));
1176         hashcpy(p->bad_object_sha1 + hashsz * p->num_bad_objects, sha1);
1177         p->num_bad_objects++;
1178 }
1179
1180 const struct packed_git *has_packed_and_bad(struct repository *r,
1181                                             const unsigned char *sha1)
1182 {
1183         struct packed_git *p;
1184         unsigned i;
1185
1186         for (p = r->objects->packed_git; p; p = p->next)
1187                 for (i = 0; i < p->num_bad_objects; i++)
1188                         if (hasheq(sha1,
1189                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1190                                 return p;
1191         return NULL;
1192 }
1193
1194 static off_t get_delta_base(struct packed_git *p,
1195                                     struct pack_window **w_curs,
1196                                     off_t *curpos,
1197                                     enum object_type type,
1198                                     off_t delta_obj_offset)
1199 {
1200         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1201         off_t base_offset;
1202
1203         /* use_pack() assured us we have [base_info, base_info + 20)
1204          * as a range that we can look at without walking off the
1205          * end of the mapped window.  Its actually the hash size
1206          * that is assured.  An OFS_DELTA longer than the hash size
1207          * is stupid, as then a REF_DELTA would be smaller to store.
1208          */
1209         if (type == OBJ_OFS_DELTA) {
1210                 unsigned used = 0;
1211                 unsigned char c = base_info[used++];
1212                 base_offset = c & 127;
1213                 while (c & 128) {
1214                         base_offset += 1;
1215                         if (!base_offset || MSB(base_offset, 7))
1216                                 return 0;  /* overflow */
1217                         c = base_info[used++];
1218                         base_offset = (base_offset << 7) + (c & 127);
1219                 }
1220                 base_offset = delta_obj_offset - base_offset;
1221                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1222                         return 0;  /* out of bound */
1223                 *curpos += used;
1224         } else if (type == OBJ_REF_DELTA) {
1225                 /* The base entry _must_ be in the same pack */
1226                 base_offset = find_pack_entry_one(base_info, p);
1227                 *curpos += the_hash_algo->rawsz;
1228         } else
1229                 die("I am totally screwed");
1230         return base_offset;
1231 }
1232
1233 /*
1234  * Like get_delta_base above, but we return the sha1 instead of the pack
1235  * offset. This means it is cheaper for REF deltas (we do not have to do
1236  * the final object lookup), but more expensive for OFS deltas (we
1237  * have to load the revidx to convert the offset back into a sha1).
1238  */
1239 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1240                                                 struct pack_window **w_curs,
1241                                                 off_t curpos,
1242                                                 enum object_type type,
1243                                                 off_t delta_obj_offset)
1244 {
1245         if (type == OBJ_REF_DELTA) {
1246                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1247                 return base;
1248         } else if (type == OBJ_OFS_DELTA) {
1249                 struct revindex_entry *revidx;
1250                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1251                                                    type, delta_obj_offset);
1252
1253                 if (!base_offset)
1254                         return NULL;
1255
1256                 revidx = find_pack_revindex(p, base_offset);
1257                 if (!revidx)
1258                         return NULL;
1259
1260                 return nth_packed_object_sha1(p, revidx->nr);
1261         } else
1262                 return NULL;
1263 }
1264
1265 static int retry_bad_packed_offset(struct repository *r,
1266                                    struct packed_git *p,
1267                                    off_t obj_offset)
1268 {
1269         int type;
1270         struct revindex_entry *revidx;
1271         struct object_id oid;
1272         revidx = find_pack_revindex(p, obj_offset);
1273         if (!revidx)
1274                 return OBJ_BAD;
1275         nth_packed_object_oid(&oid, p, revidx->nr);
1276         mark_bad_packed_object(p, oid.hash);
1277         type = oid_object_info(r, &oid, NULL);
1278         if (type <= OBJ_NONE)
1279                 return OBJ_BAD;
1280         return type;
1281 }
1282
1283 #define POI_STACK_PREALLOC 64
1284
1285 static enum object_type packed_to_object_type(struct repository *r,
1286                                               struct packed_git *p,
1287                                               off_t obj_offset,
1288                                               enum object_type type,
1289                                               struct pack_window **w_curs,
1290                                               off_t curpos)
1291 {
1292         off_t small_poi_stack[POI_STACK_PREALLOC];
1293         off_t *poi_stack = small_poi_stack;
1294         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1295
1296         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1297                 off_t base_offset;
1298                 unsigned long size;
1299                 /* Push the object we're going to leave behind */
1300                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1301                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1302                         ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1303                         COPY_ARRAY(poi_stack, small_poi_stack, poi_stack_nr);
1304                 } else {
1305                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1306                 }
1307                 poi_stack[poi_stack_nr++] = obj_offset;
1308                 /* If parsing the base offset fails, just unwind */
1309                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1310                 if (!base_offset)
1311                         goto unwind;
1312                 curpos = obj_offset = base_offset;
1313                 type = unpack_object_header(p, w_curs, &curpos, &size);
1314                 if (type <= OBJ_NONE) {
1315                         /* If getting the base itself fails, we first
1316                          * retry the base, otherwise unwind */
1317                         type = retry_bad_packed_offset(r, p, base_offset);
1318                         if (type > OBJ_NONE)
1319                                 goto out;
1320                         goto unwind;
1321                 }
1322         }
1323
1324         switch (type) {
1325         case OBJ_BAD:
1326         case OBJ_COMMIT:
1327         case OBJ_TREE:
1328         case OBJ_BLOB:
1329         case OBJ_TAG:
1330                 break;
1331         default:
1332                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1333                       type, (uintmax_t)obj_offset, p->pack_name);
1334                 type = OBJ_BAD;
1335         }
1336
1337 out:
1338         if (poi_stack != small_poi_stack)
1339                 free(poi_stack);
1340         return type;
1341
1342 unwind:
1343         while (poi_stack_nr) {
1344                 obj_offset = poi_stack[--poi_stack_nr];
1345                 type = retry_bad_packed_offset(r, p, obj_offset);
1346                 if (type > OBJ_NONE)
1347                         goto out;
1348         }
1349         type = OBJ_BAD;
1350         goto out;
1351 }
1352
1353 static struct hashmap delta_base_cache;
1354 static size_t delta_base_cached;
1355
1356 static LIST_HEAD(delta_base_cache_lru);
1357
1358 struct delta_base_cache_key {
1359         struct packed_git *p;
1360         off_t base_offset;
1361 };
1362
1363 struct delta_base_cache_entry {
1364         struct hashmap_entry ent;
1365         struct delta_base_cache_key key;
1366         struct list_head lru;
1367         void *data;
1368         unsigned long size;
1369         enum object_type type;
1370 };
1371
1372 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1373 {
1374         unsigned int hash;
1375
1376         hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1377         hash += (hash >> 8) + (hash >> 16);
1378         return hash;
1379 }
1380
1381 static struct delta_base_cache_entry *
1382 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1383 {
1384         struct hashmap_entry entry, *e;
1385         struct delta_base_cache_key key;
1386
1387         if (!delta_base_cache.cmpfn)
1388                 return NULL;
1389
1390         hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1391         key.p = p;
1392         key.base_offset = base_offset;
1393         e = hashmap_get(&delta_base_cache, &entry, &key);
1394         return e ? container_of(e, struct delta_base_cache_entry, ent) : NULL;
1395 }
1396
1397 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1398                                    const struct delta_base_cache_key *b)
1399 {
1400         return a->p == b->p && a->base_offset == b->base_offset;
1401 }
1402
1403 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1404                                      const struct hashmap_entry *va,
1405                                      const struct hashmap_entry *vb,
1406                                      const void *vkey)
1407 {
1408         const struct delta_base_cache_entry *a, *b;
1409         const struct delta_base_cache_key *key = vkey;
1410
1411         a = container_of(va, const struct delta_base_cache_entry, ent);
1412         b = container_of(vb, const struct delta_base_cache_entry, ent);
1413
1414         if (key)
1415                 return !delta_base_cache_key_eq(&a->key, key);
1416         else
1417                 return !delta_base_cache_key_eq(&a->key, &b->key);
1418 }
1419
1420 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1421 {
1422         return !!get_delta_base_cache_entry(p, base_offset);
1423 }
1424
1425 /*
1426  * Remove the entry from the cache, but do _not_ free the associated
1427  * entry data. The caller takes ownership of the "data" buffer, and
1428  * should copy out any fields it wants before detaching.
1429  */
1430 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1431 {
1432         hashmap_remove(&delta_base_cache, &ent->ent, &ent->key);
1433         list_del(&ent->lru);
1434         delta_base_cached -= ent->size;
1435         free(ent);
1436 }
1437
1438 static void *cache_or_unpack_entry(struct repository *r, struct packed_git *p,
1439                                    off_t base_offset, unsigned long *base_size,
1440                                    enum object_type *type)
1441 {
1442         struct delta_base_cache_entry *ent;
1443
1444         ent = get_delta_base_cache_entry(p, base_offset);
1445         if (!ent)
1446                 return unpack_entry(r, p, base_offset, type, base_size);
1447
1448         if (type)
1449                 *type = ent->type;
1450         if (base_size)
1451                 *base_size = ent->size;
1452         return xmemdupz(ent->data, ent->size);
1453 }
1454
1455 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1456 {
1457         free(ent->data);
1458         detach_delta_base_cache_entry(ent);
1459 }
1460
1461 void clear_delta_base_cache(void)
1462 {
1463         struct list_head *lru, *tmp;
1464         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1465                 struct delta_base_cache_entry *entry =
1466                         list_entry(lru, struct delta_base_cache_entry, lru);
1467                 release_delta_base_cache(entry);
1468         }
1469 }
1470
1471 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1472         void *base, unsigned long base_size, enum object_type type)
1473 {
1474         struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1475         struct list_head *lru, *tmp;
1476
1477         delta_base_cached += base_size;
1478
1479         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1480                 struct delta_base_cache_entry *f =
1481                         list_entry(lru, struct delta_base_cache_entry, lru);
1482                 if (delta_base_cached <= delta_base_cache_limit)
1483                         break;
1484                 release_delta_base_cache(f);
1485         }
1486
1487         ent->key.p = p;
1488         ent->key.base_offset = base_offset;
1489         ent->type = type;
1490         ent->data = base;
1491         ent->size = base_size;
1492         list_add_tail(&ent->lru, &delta_base_cache_lru);
1493
1494         if (!delta_base_cache.cmpfn)
1495                 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1496         hashmap_entry_init(&ent->ent, pack_entry_hash(p, base_offset));
1497         hashmap_add(&delta_base_cache, &ent->ent);
1498 }
1499
1500 int packed_object_info(struct repository *r, struct packed_git *p,
1501                        off_t obj_offset, struct object_info *oi)
1502 {
1503         struct pack_window *w_curs = NULL;
1504         unsigned long size;
1505         off_t curpos = obj_offset;
1506         enum object_type type;
1507
1508         /*
1509          * We always get the representation type, but only convert it to
1510          * a "real" type later if the caller is interested.
1511          */
1512         if (oi->contentp) {
1513                 *oi->contentp = cache_or_unpack_entry(r, p, obj_offset, oi->sizep,
1514                                                       &type);
1515                 if (!*oi->contentp)
1516                         type = OBJ_BAD;
1517         } else {
1518                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1519         }
1520
1521         if (!oi->contentp && oi->sizep) {
1522                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1523                         off_t tmp_pos = curpos;
1524                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1525                                                            type, obj_offset);
1526                         if (!base_offset) {
1527                                 type = OBJ_BAD;
1528                                 goto out;
1529                         }
1530                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1531                         if (*oi->sizep == 0) {
1532                                 type = OBJ_BAD;
1533                                 goto out;
1534                         }
1535                 } else {
1536                         *oi->sizep = size;
1537                 }
1538         }
1539
1540         if (oi->disk_sizep) {
1541                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1542                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1543         }
1544
1545         if (oi->typep || oi->type_name) {
1546                 enum object_type ptot;
1547                 ptot = packed_to_object_type(r, p, obj_offset,
1548                                              type, &w_curs, curpos);
1549                 if (oi->typep)
1550                         *oi->typep = ptot;
1551                 if (oi->type_name) {
1552                         const char *tn = type_name(ptot);
1553                         if (tn)
1554                                 strbuf_addstr(oi->type_name, tn);
1555                 }
1556                 if (ptot < 0) {
1557                         type = OBJ_BAD;
1558                         goto out;
1559                 }
1560         }
1561
1562         if (oi->delta_base_sha1) {
1563                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1564                         const unsigned char *base;
1565
1566                         base = get_delta_base_sha1(p, &w_curs, curpos,
1567                                                    type, obj_offset);
1568                         if (!base) {
1569                                 type = OBJ_BAD;
1570                                 goto out;
1571                         }
1572
1573                         hashcpy(oi->delta_base_sha1, base);
1574                 } else
1575                         hashclr(oi->delta_base_sha1);
1576         }
1577
1578         oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1579                                                           OI_PACKED;
1580
1581 out:
1582         unuse_pack(&w_curs);
1583         return type;
1584 }
1585
1586 static void *unpack_compressed_entry(struct packed_git *p,
1587                                     struct pack_window **w_curs,
1588                                     off_t curpos,
1589                                     unsigned long size)
1590 {
1591         int st;
1592         git_zstream stream;
1593         unsigned char *buffer, *in;
1594
1595         buffer = xmallocz_gently(size);
1596         if (!buffer)
1597                 return NULL;
1598         memset(&stream, 0, sizeof(stream));
1599         stream.next_out = buffer;
1600         stream.avail_out = size + 1;
1601
1602         git_inflate_init(&stream);
1603         do {
1604                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1605                 stream.next_in = in;
1606                 st = git_inflate(&stream, Z_FINISH);
1607                 if (!stream.avail_out)
1608                         break; /* the payload is larger than it should be */
1609                 curpos += stream.next_in - in;
1610         } while (st == Z_OK || st == Z_BUF_ERROR);
1611         git_inflate_end(&stream);
1612         if ((st != Z_STREAM_END) || stream.total_out != size) {
1613                 free(buffer);
1614                 return NULL;
1615         }
1616
1617         /* versions of zlib can clobber unconsumed portion of outbuf */
1618         buffer[size] = '\0';
1619
1620         return buffer;
1621 }
1622
1623 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1624 {
1625         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1626         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1627                          p->pack_name, (uintmax_t)obj_offset);
1628 }
1629
1630 int do_check_packed_object_crc;
1631
1632 #define UNPACK_ENTRY_STACK_PREALLOC 64
1633 struct unpack_entry_stack_ent {
1634         off_t obj_offset;
1635         off_t curpos;
1636         unsigned long size;
1637 };
1638
1639 static void *read_object(struct repository *r,
1640                          const struct object_id *oid,
1641                          enum object_type *type,
1642                          unsigned long *size)
1643 {
1644         struct object_info oi = OBJECT_INFO_INIT;
1645         void *content;
1646         oi.typep = type;
1647         oi.sizep = size;
1648         oi.contentp = &content;
1649
1650         if (oid_object_info_extended(r, oid, &oi, 0) < 0)
1651                 return NULL;
1652         return content;
1653 }
1654
1655 void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset,
1656                    enum object_type *final_type, unsigned long *final_size)
1657 {
1658         struct pack_window *w_curs = NULL;
1659         off_t curpos = obj_offset;
1660         void *data = NULL;
1661         unsigned long size;
1662         enum object_type type;
1663         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1664         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1665         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1666         int base_from_cache = 0;
1667
1668         write_pack_access_log(p, obj_offset);
1669
1670         /* PHASE 1: drill down to the innermost base object */
1671         for (;;) {
1672                 off_t base_offset;
1673                 int i;
1674                 struct delta_base_cache_entry *ent;
1675
1676                 ent = get_delta_base_cache_entry(p, curpos);
1677                 if (ent) {
1678                         type = ent->type;
1679                         data = ent->data;
1680                         size = ent->size;
1681                         detach_delta_base_cache_entry(ent);
1682                         base_from_cache = 1;
1683                         break;
1684                 }
1685
1686                 if (do_check_packed_object_crc && p->index_version > 1) {
1687                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1688                         off_t len = revidx[1].offset - obj_offset;
1689                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1690                                 struct object_id oid;
1691                                 nth_packed_object_oid(&oid, p, revidx->nr);
1692                                 error("bad packed object CRC for %s",
1693                                       oid_to_hex(&oid));
1694                                 mark_bad_packed_object(p, oid.hash);
1695                                 data = NULL;
1696                                 goto out;
1697                         }
1698                 }
1699
1700                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1701                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1702                         break;
1703
1704                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1705                 if (!base_offset) {
1706                         error("failed to validate delta base reference "
1707                               "at offset %"PRIuMAX" from %s",
1708                               (uintmax_t)curpos, p->pack_name);
1709                         /* bail to phase 2, in hopes of recovery */
1710                         data = NULL;
1711                         break;
1712                 }
1713
1714                 /* push object, proceed to base */
1715                 if (delta_stack_nr >= delta_stack_alloc
1716                     && delta_stack == small_delta_stack) {
1717                         delta_stack_alloc = alloc_nr(delta_stack_nr);
1718                         ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1719                         COPY_ARRAY(delta_stack, small_delta_stack,
1720                                    delta_stack_nr);
1721                 } else {
1722                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1723                 }
1724                 i = delta_stack_nr++;
1725                 delta_stack[i].obj_offset = obj_offset;
1726                 delta_stack[i].curpos = curpos;
1727                 delta_stack[i].size = size;
1728
1729                 curpos = obj_offset = base_offset;
1730         }
1731
1732         /* PHASE 2: handle the base */
1733         switch (type) {
1734         case OBJ_OFS_DELTA:
1735         case OBJ_REF_DELTA:
1736                 if (data)
1737                         BUG("unpack_entry: left loop at a valid delta");
1738                 break;
1739         case OBJ_COMMIT:
1740         case OBJ_TREE:
1741         case OBJ_BLOB:
1742         case OBJ_TAG:
1743                 if (!base_from_cache)
1744                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
1745                 break;
1746         default:
1747                 data = NULL;
1748                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1749                       type, (uintmax_t)obj_offset, p->pack_name);
1750         }
1751
1752         /* PHASE 3: apply deltas in order */
1753
1754         /* invariants:
1755          *   'data' holds the base data, or NULL if there was corruption
1756          */
1757         while (delta_stack_nr) {
1758                 void *delta_data;
1759                 void *base = data;
1760                 void *external_base = NULL;
1761                 unsigned long delta_size, base_size = size;
1762                 int i;
1763
1764                 data = NULL;
1765
1766                 if (base)
1767                         add_delta_base_cache(p, obj_offset, base, base_size, type);
1768
1769                 if (!base) {
1770                         /*
1771                          * We're probably in deep shit, but let's try to fetch
1772                          * the required base anyway from another pack or loose.
1773                          * This is costly but should happen only in the presence
1774                          * of a corrupted pack, and is better than failing outright.
1775                          */
1776                         struct revindex_entry *revidx;
1777                         struct object_id base_oid;
1778                         revidx = find_pack_revindex(p, obj_offset);
1779                         if (revidx) {
1780                                 nth_packed_object_oid(&base_oid, p, revidx->nr);
1781                                 error("failed to read delta base object %s"
1782                                       " at offset %"PRIuMAX" from %s",
1783                                       oid_to_hex(&base_oid), (uintmax_t)obj_offset,
1784                                       p->pack_name);
1785                                 mark_bad_packed_object(p, base_oid.hash);
1786                                 base = read_object(r, &base_oid, &type, &base_size);
1787                                 external_base = base;
1788                         }
1789                 }
1790
1791                 i = --delta_stack_nr;
1792                 obj_offset = delta_stack[i].obj_offset;
1793                 curpos = delta_stack[i].curpos;
1794                 delta_size = delta_stack[i].size;
1795
1796                 if (!base)
1797                         continue;
1798
1799                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1800
1801                 if (!delta_data) {
1802                         error("failed to unpack compressed delta "
1803                               "at offset %"PRIuMAX" from %s",
1804                               (uintmax_t)curpos, p->pack_name);
1805                         data = NULL;
1806                         free(external_base);
1807                         continue;
1808                 }
1809
1810                 data = patch_delta(base, base_size,
1811                                    delta_data, delta_size,
1812                                    &size);
1813
1814                 /*
1815                  * We could not apply the delta; warn the user, but keep going.
1816                  * Our failure will be noticed either in the next iteration of
1817                  * the loop, or if this is the final delta, in the caller when
1818                  * we return NULL. Those code paths will take care of making
1819                  * a more explicit warning and retrying with another copy of
1820                  * the object.
1821                  */
1822                 if (!data)
1823                         error("failed to apply delta");
1824
1825                 free(delta_data);
1826                 free(external_base);
1827         }
1828
1829         if (final_type)
1830                 *final_type = type;
1831         if (final_size)
1832                 *final_size = size;
1833
1834 out:
1835         unuse_pack(&w_curs);
1836
1837         if (delta_stack != small_delta_stack)
1838                 free(delta_stack);
1839
1840         return data;
1841 }
1842
1843 int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result)
1844 {
1845         const unsigned char *index_fanout = p->index_data;
1846         const unsigned char *index_lookup;
1847         const unsigned int hashsz = the_hash_algo->rawsz;
1848         int index_lookup_width;
1849
1850         if (!index_fanout)
1851                 BUG("bsearch_pack called without a valid pack-index");
1852
1853         index_lookup = index_fanout + 4 * 256;
1854         if (p->index_version == 1) {
1855                 index_lookup_width = hashsz + 4;
1856                 index_lookup += 4;
1857         } else {
1858                 index_lookup_width = hashsz;
1859                 index_fanout += 8;
1860                 index_lookup += 8;
1861         }
1862
1863         return bsearch_hash(oid->hash, (const uint32_t*)index_fanout,
1864                             index_lookup, index_lookup_width, result);
1865 }
1866
1867 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1868                                             uint32_t n)
1869 {
1870         const unsigned char *index = p->index_data;
1871         const unsigned int hashsz = the_hash_algo->rawsz;
1872         if (!index) {
1873                 if (open_pack_index(p))
1874                         return NULL;
1875                 index = p->index_data;
1876         }
1877         if (n >= p->num_objects)
1878                 return NULL;
1879         index += 4 * 256;
1880         if (p->index_version == 1) {
1881                 return index + (hashsz + 4) * n + 4;
1882         } else {
1883                 index += 8;
1884                 return index + hashsz * n;
1885         }
1886 }
1887
1888 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1889                                               struct packed_git *p,
1890                                               uint32_t n)
1891 {
1892         const unsigned char *hash = nth_packed_object_sha1(p, n);
1893         if (!hash)
1894                 return NULL;
1895         hashcpy(oid->hash, hash);
1896         return oid;
1897 }
1898
1899 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1900 {
1901         const unsigned char *ptr = vptr;
1902         const unsigned char *start = p->index_data;
1903         const unsigned char *end = start + p->index_size;
1904         if (ptr < start)
1905                 die(_("offset before start of pack index for %s (corrupt index?)"),
1906                     p->pack_name);
1907         /* No need to check for underflow; .idx files must be at least 8 bytes */
1908         if (ptr >= end - 8)
1909                 die(_("offset beyond end of pack index for %s (truncated index?)"),
1910                     p->pack_name);
1911 }
1912
1913 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1914 {
1915         const unsigned char *index = p->index_data;
1916         const unsigned int hashsz = the_hash_algo->rawsz;
1917         index += 4 * 256;
1918         if (p->index_version == 1) {
1919                 return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
1920         } else {
1921                 uint32_t off;
1922                 index += 8 + p->num_objects * (hashsz + 4);
1923                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1924                 if (!(off & 0x80000000))
1925                         return off;
1926                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1927                 check_pack_index_ptr(p, index);
1928                 return get_be64(index);
1929         }
1930 }
1931
1932 off_t find_pack_entry_one(const unsigned char *sha1,
1933                                   struct packed_git *p)
1934 {
1935         const unsigned char *index = p->index_data;
1936         struct object_id oid;
1937         uint32_t result;
1938
1939         if (!index) {
1940                 if (open_pack_index(p))
1941                         return 0;
1942         }
1943
1944         hashcpy(oid.hash, sha1);
1945         if (bsearch_pack(&oid, p, &result))
1946                 return nth_packed_object_offset(p, result);
1947         return 0;
1948 }
1949
1950 int is_pack_valid(struct packed_git *p)
1951 {
1952         /* An already open pack is known to be valid. */
1953         if (p->pack_fd != -1)
1954                 return 1;
1955
1956         /* If the pack has one window completely covering the
1957          * file size, the pack is known to be valid even if
1958          * the descriptor is not currently open.
1959          */
1960         if (p->windows) {
1961                 struct pack_window *w = p->windows;
1962
1963                 if (!w->offset && w->len == p->pack_size)
1964                         return 1;
1965         }
1966
1967         /* Force the pack to open to prove its valid. */
1968         return !open_packed_git(p);
1969 }
1970
1971 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1972                                   struct packed_git *packs)
1973 {
1974         struct packed_git *p;
1975
1976         for (p = packs; p; p = p->next) {
1977                 if (find_pack_entry_one(sha1, p))
1978                         return p;
1979         }
1980         return NULL;
1981
1982 }
1983
1984 static int fill_pack_entry(const struct object_id *oid,
1985                            struct pack_entry *e,
1986                            struct packed_git *p)
1987 {
1988         off_t offset;
1989
1990         if (p->num_bad_objects) {
1991                 unsigned i;
1992                 for (i = 0; i < p->num_bad_objects; i++)
1993                         if (hasheq(oid->hash,
1994                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1995                                 return 0;
1996         }
1997
1998         offset = find_pack_entry_one(oid->hash, p);
1999         if (!offset)
2000                 return 0;
2001
2002         /*
2003          * We are about to tell the caller where they can locate the
2004          * requested object.  We better make sure the packfile is
2005          * still here and can be accessed before supplying that
2006          * answer, as it may have been deleted since the index was
2007          * loaded!
2008          */
2009         if (!is_pack_valid(p))
2010                 return 0;
2011         e->offset = offset;
2012         e->p = p;
2013         return 1;
2014 }
2015
2016 int find_pack_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e)
2017 {
2018         struct list_head *pos;
2019         struct multi_pack_index *m;
2020
2021         prepare_packed_git(r);
2022         if (!r->objects->packed_git && !r->objects->multi_pack_index)
2023                 return 0;
2024
2025         for (m = r->objects->multi_pack_index; m; m = m->next) {
2026                 if (fill_midx_entry(r, oid, e, m))
2027                         return 1;
2028         }
2029
2030         list_for_each(pos, &r->objects->packed_git_mru) {
2031                 struct packed_git *p = list_entry(pos, struct packed_git, mru);
2032                 if (!p->multi_pack_index && fill_pack_entry(oid, e, p)) {
2033                         list_move(&p->mru, &r->objects->packed_git_mru);
2034                         return 1;
2035                 }
2036         }
2037         return 0;
2038 }
2039
2040 int has_object_pack(const struct object_id *oid)
2041 {
2042         struct pack_entry e;
2043         return find_pack_entry(the_repository, oid, &e);
2044 }
2045
2046 int has_pack_index(const unsigned char *sha1)
2047 {
2048         struct stat st;
2049         if (stat(sha1_pack_index_name(sha1), &st))
2050                 return 0;
2051         return 1;
2052 }
2053
2054 int for_each_object_in_pack(struct packed_git *p,
2055                             each_packed_object_fn cb, void *data,
2056                             enum for_each_object_flags flags)
2057 {
2058         uint32_t i;
2059         int r = 0;
2060
2061         if (flags & FOR_EACH_OBJECT_PACK_ORDER) {
2062                 if (load_pack_revindex(p))
2063                         return -1;
2064         }
2065
2066         for (i = 0; i < p->num_objects; i++) {
2067                 uint32_t pos;
2068                 struct object_id oid;
2069
2070                 if (flags & FOR_EACH_OBJECT_PACK_ORDER)
2071                         pos = p->revindex[i].nr;
2072                 else
2073                         pos = i;
2074
2075                 if (!nth_packed_object_oid(&oid, p, pos))
2076                         return error("unable to get sha1 of object %u in %s",
2077                                      pos, p->pack_name);
2078
2079                 r = cb(&oid, p, pos, data);
2080                 if (r)
2081                         break;
2082         }
2083         return r;
2084 }
2085
2086 int for_each_packed_object(each_packed_object_fn cb, void *data,
2087                            enum for_each_object_flags flags)
2088 {
2089         struct packed_git *p;
2090         int r = 0;
2091         int pack_errors = 0;
2092
2093         prepare_packed_git(the_repository);
2094         for (p = get_all_packs(the_repository); p; p = p->next) {
2095                 if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
2096                         continue;
2097                 if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
2098                     !p->pack_promisor)
2099                         continue;
2100                 if (open_pack_index(p)) {
2101                         pack_errors = 1;
2102                         continue;
2103                 }
2104                 r = for_each_object_in_pack(p, cb, data, flags);
2105                 if (r)
2106                         break;
2107         }
2108         return r ? r : pack_errors;
2109 }
2110
2111 static int add_promisor_object(const struct object_id *oid,
2112                                struct packed_git *pack,
2113                                uint32_t pos,
2114                                void *set_)
2115 {
2116         struct oidset *set = set_;
2117         struct object *obj = parse_object(the_repository, oid);
2118         if (!obj)
2119                 return 1;
2120
2121         oidset_insert(set, oid);
2122
2123         /*
2124          * If this is a tree, commit, or tag, the objects it refers
2125          * to are also promisor objects. (Blobs refer to no objects->)
2126          */
2127         if (obj->type == OBJ_TREE) {
2128                 struct tree *tree = (struct tree *)obj;
2129                 struct tree_desc desc;
2130                 struct name_entry entry;
2131                 if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
2132                         /*
2133                          * Error messages are given when packs are
2134                          * verified, so do not print any here.
2135                          */
2136                         return 0;
2137                 while (tree_entry_gently(&desc, &entry))
2138                         oidset_insert(set, &entry.oid);
2139         } else if (obj->type == OBJ_COMMIT) {
2140                 struct commit *commit = (struct commit *) obj;
2141                 struct commit_list *parents = commit->parents;
2142
2143                 oidset_insert(set, get_commit_tree_oid(commit));
2144                 for (; parents; parents = parents->next)
2145                         oidset_insert(set, &parents->item->object.oid);
2146         } else if (obj->type == OBJ_TAG) {
2147                 struct tag *tag = (struct tag *) obj;
2148                 oidset_insert(set, &tag->tagged->oid);
2149         }
2150         return 0;
2151 }
2152
2153 int is_promisor_object(const struct object_id *oid)
2154 {
2155         static struct oidset promisor_objects;
2156         static int promisor_objects_prepared;
2157
2158         if (!promisor_objects_prepared) {
2159                 if (repository_format_partial_clone) {
2160                         for_each_packed_object(add_promisor_object,
2161                                                &promisor_objects,
2162                                                FOR_EACH_OBJECT_PROMISOR_ONLY);
2163                 }
2164                 promisor_objects_prepared = 1;
2165         }
2166         return oidset_contains(&promisor_objects, oid);
2167 }