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