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->sha1, 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 static 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 /*
 470  * Do not call this directly as this leaks p->pack_fd on error return;
 471  * call open_packed_git() instead.
 472  */
 473 static int open_packed_git_1(struct packed_git *p)
 474 {
 475         struct stat st;
 476         struct pack_header hdr;
 477         unsigned char hash[GIT_MAX_RAWSZ];
 478         unsigned char *idx_hash;
 479         long fd_flag;
 480         ssize_t read_result;
 481         const unsigned hashsz = the_hash_algo->rawsz;
 482
 483         if (!p->index_data) {
 484                 struct multi_pack_index *m;
 485                 const char *pack_name = strrchr(p->pack_name, '/');
 486
 487                 for (m = the_repository->objects->multi_pack_index;
 488                      m; m = m->next) {
 489                         if (midx_contains_pack(m, pack_name))
 490                                 break;
 491                 }
 492
 493                 if (!m && open_pack_index(p))
 494                         return error("packfile %s index unavailable", p->pack_name);
 495         }
 496
 497         if (!pack_max_fds) {
 498                 unsigned int max_fds = get_max_fd_limit();
 499
 500                 /* Save 3 for stdin/stdout/stderr, 22 for work */
 501                 if (25 < max_fds)
 502                         pack_max_fds = max_fds - 25;
 503                 else
 504                         pack_max_fds = 1;
 505         }
 506
 507         while (pack_max_fds <= pack_open_fds && close_one_pack())
 508                 ; /* nothing */
 509
 510         p->pack_fd = git_open(p->pack_name);
 511         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 512                 return -1;
 513         pack_open_fds++;
 514
 515         /* If we created the struct before we had the pack we lack size. */
 516         if (!p->pack_size) {
 517                 if (!S_ISREG(st.st_mode))
 518                         return error("packfile %s not a regular file", p->pack_name);
 519                 p->pack_size = st.st_size;
 520         } else if (p->pack_size != st.st_size)
 521                 return error("packfile %s size changed", p->pack_name);
 522
 523         /* We leave these file descriptors open with sliding mmap;
 524          * there is no point keeping them open across exec(), though.
 525          */
 526         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 527         if (fd_flag < 0)
 528                 return error("cannot determine file descriptor flags");
 529         fd_flag |= FD_CLOEXEC;
 530         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 531                 return error("cannot set FD_CLOEXEC");
 532
 533         /* Verify we recognize this pack file format. */
 534         read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
 535         if (read_result < 0)
 536                 return error_errno("error reading from %s", p->pack_name);
 537         if (read_result != sizeof(hdr))
 538                 return error("file %s is far too short to be a packfile", p->pack_name);
 539         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 540                 return error("file %s is not a GIT packfile", p->pack_name);
 541         if (!pack_version_ok(hdr.hdr_version))
 542                 return error("packfile %s is version %"PRIu32" and not"
 543                         " supported (try upgrading GIT to a newer version)",
 544                         p->pack_name, ntohl(hdr.hdr_version));
 545
 546         /* Skip index checking if in multi-pack-index */
 547         if (!p->index_data)
 548                 return 0;
 549
 550         /* Verify the pack matches its index. */
 551         if (p->num_objects != ntohl(hdr.hdr_entries))
 552                 return error("packfile %s claims to have %"PRIu32" objects"
 553                              " while index indicates %"PRIu32" objects",
 554                              p->pack_name, ntohl(hdr.hdr_entries),
 555                              p->num_objects);
 556         if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
 557                 return error("end of packfile %s is unavailable", p->pack_name);
 558         read_result = read_in_full(p->pack_fd, hash, hashsz);
 559         if (read_result < 0)
 560                 return error_errno("error reading from %s", p->pack_name);
 561         if (read_result != hashsz)
 562                 return error("packfile %s signature is unavailable", p->pack_name);
 563         idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
 564         if (!hasheq(hash, idx_hash))
 565                 return error("packfile %s does not match index", p->pack_name);
 566         return 0;
 567 }
 568
 569 static int open_packed_git(struct packed_git *p)
 570 {
 571         if (!open_packed_git_1(p))
 572                 return 0;
 573         close_pack_fd(p);
 574         return -1;
 575 }
 576
 577 static int in_window(struct pack_window *win, off_t offset)
 578 {
 579         /* We must promise at least one full hash after the
 580          * offset is available from this window, otherwise the offset
 581          * is not actually in this window and a different window (which
 582          * has that one hash excess) must be used.  This is to support
 583          * the object header and delta base parsing routines below.
 584          */
 585         off_t win_off = win->offset;
 586         return win_off <= offset
 587                 && (offset + the_hash_algo->rawsz) <= (win_off + win->len);
 588 }
 589
 590 unsigned char *use_pack(struct packed_git *p,
 591                 struct pack_window **w_cursor,
 592                 off_t offset,
 593                 unsigned long *left)
 594 {
 595         struct pack_window *win = *w_cursor;
 596
 597         /* Since packfiles end in a hash of their content and it's
 598          * pointless to ask for an offset into the middle of that
 599          * hash, and the in_window function above wouldn't match
 600          * don't allow an offset too close to the end of the file.
 601          */
 602         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 603                 die("packfile %s cannot be accessed", p->pack_name);
 604         if (offset > (p->pack_size - the_hash_algo->rawsz))
 605                 die("offset beyond end of packfile (truncated pack?)");
 606         if (offset < 0)
 607                 die(_("offset before end of packfile (broken .idx?)"));
 608
 609         if (!win || !in_window(win, offset)) {
 610                 if (win)
 611                         win->inuse_cnt--;
 612                 for (win = p->windows; win; win = win->next) {
 613                         if (in_window(win, offset))
 614                                 break;
 615                 }
 616                 if (!win) {
 617                         size_t window_align = packed_git_window_size / 2;
 618                         off_t len;
 619
 620                         if (p->pack_fd == -1 && open_packed_git(p))
 621                                 die("packfile %s cannot be accessed", p->pack_name);
 622
 623                         win = xcalloc(1, sizeof(*win));
 624                         win->offset = (offset / window_align) * window_align;
 625                         len = p->pack_size - win->offset;
 626                         if (len > packed_git_window_size)
 627                                 len = packed_git_window_size;
 628                         win->len = (size_t)len;
 629                         pack_mapped += win->len;
 630                         while (packed_git_limit < pack_mapped
 631                                 && unuse_one_window(p))
 632                                 ; /* nothing */
 633                         win->base = xmmap(NULL, win->len,
 634                                 PROT_READ, MAP_PRIVATE,
 635                                 p->pack_fd, win->offset);
 636                         if (win->base == MAP_FAILED)
 637                                 die_errno("packfile %s cannot be mapped",
 638                                           p->pack_name);
 639                         if (!win->offset && win->len == p->pack_size
 640                                 && !p->do_not_close)
 641                                 close_pack_fd(p);
 642                         pack_mmap_calls++;
 643                         pack_open_windows++;
 644                         if (pack_mapped > peak_pack_mapped)
 645                                 peak_pack_mapped = pack_mapped;
 646                         if (pack_open_windows > peak_pack_open_windows)
 647                                 peak_pack_open_windows = pack_open_windows;
 648                         win->next = p->windows;
 649                         p->windows = win;
 650                 }
 651         }
 652         if (win != *w_cursor) {
 653                 win->last_used = pack_used_ctr++;
 654                 win->inuse_cnt++;
 655                 *w_cursor = win;
 656         }
 657         offset -= win->offset;
 658         if (left)
 659                 *left = win->len - xsize_t(offset);
 660         return win->base + offset;
 661 }
 662
 663 void unuse_pack(struct pack_window **w_cursor)
 664 {
 665         struct pack_window *w = *w_cursor;
 666         if (w) {
 667                 w->inuse_cnt--;
 668                 *w_cursor = NULL;
 669         }
 670 }
 671
 672 static void try_to_free_pack_memory(size_t size)
 673 {
 674         release_pack_memory(size);
 675 }
 676
 677 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
 678 {
 679         static int have_set_try_to_free_routine;
 680         struct stat st;
 681         size_t alloc;
 682         struct packed_git *p;
 683
 684         if (!have_set_try_to_free_routine) {
 685                 have_set_try_to_free_routine = 1;
 686                 set_try_to_free_routine(try_to_free_pack_memory);
 687         }
 688
 689         /*
 690          * Make sure a corresponding .pack file exists and that
 691          * the index looks sane.
 692          */
 693         if (!strip_suffix_mem(path, &path_len, ".idx"))
 694                 return NULL;
 695
 696         /*
 697          * ".promisor" is long enough to hold any suffix we're adding (and
 698          * the use xsnprintf double-checks that)
 699          */
 700         alloc = st_add3(path_len, strlen(".promisor"), 1);
 701         p = alloc_packed_git(alloc);
 702         memcpy(p->pack_name, path, path_len);
 703
 704         xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
 705         if (!access(p->pack_name, F_OK))
 706                 p->pack_keep = 1;
 707
 708         xsnprintf(p->pack_name + path_len, alloc - path_len, ".promisor");
 709         if (!access(p->pack_name, F_OK))
 710                 p->pack_promisor = 1;
 711
 712         xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
 713         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 714                 free(p);
 715                 return NULL;
 716         }
 717
 718         /* ok, it looks sane as far as we can check without
 719          * actually mapping the pack file.
 720          */
 721         p->pack_size = st.st_size;
 722         p->pack_local = local;
 723         p->mtime = st.st_mtime;
 724         if (path_len < the_hash_algo->hexsz ||
 725             get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))
 726                 hashclr(p->sha1);
 727         return p;
 728 }
 729
 730 void install_packed_git(struct repository *r, struct packed_git *pack)
 731 {
 732         if (pack->pack_fd != -1)
 733                 pack_open_fds++;
 734
 735         pack->next = r->objects->packed_git;
 736         r->objects->packed_git = pack;
 737 }
 738
 739 void (*report_garbage)(unsigned seen_bits, const char *path);
 740
 741 static void report_helper(const struct string_list *list,
 742                           int seen_bits, int first, int last)
 743 {
 744         if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
 745                 return;
 746
 747         for (; first < last; first++)
 748                 report_garbage(seen_bits, list->items[first].string);
 749 }
 750
 751 static void report_pack_garbage(struct string_list *list)
 752 {
 753         int i, baselen = -1, first = 0, seen_bits = 0;
 754
 755         if (!report_garbage)
 756                 return;
 757
 758         string_list_sort(list);
 759
 760         for (i = 0; i < list->nr; i++) {
 761                 const char *path = list->items[i].string;
 762                 if (baselen != -1 &&
 763                     strncmp(path, list->items[first].string, baselen)) {
 764                         report_helper(list, seen_bits, first, i);
 765                         baselen = -1;
 766                         seen_bits = 0;
 767                 }
 768                 if (baselen == -1) {
 769                         const char *dot = strrchr(path, '.');
 770                         if (!dot) {
 771                                 report_garbage(PACKDIR_FILE_GARBAGE, path);
 772                                 continue;
 773                         }
 774                         baselen = dot - path + 1;
 775                         first = i;
 776                 }
 777                 if (!strcmp(path + baselen, "pack"))
 778                         seen_bits |= 1;
 779                 else if (!strcmp(path + baselen, "idx"))
 780                         seen_bits |= 2;
 781         }
 782         report_helper(list, seen_bits, first, list->nr);
 783 }
 784
 785 void for_each_file_in_pack_dir(const char *objdir,
 786                                each_file_in_pack_dir_fn fn,
 787                                void *data)
 788 {
 789         struct strbuf path = STRBUF_INIT;
 790         size_t dirnamelen;
 791         DIR *dir;
 792         struct dirent *de;
 793
 794         strbuf_addstr(&path, objdir);
 795         strbuf_addstr(&path, "/pack");
 796         dir = opendir(path.buf);
 797         if (!dir) {
 798                 if (errno != ENOENT)
 799                         error_errno("unable to open object pack directory: %s",
 800                                     path.buf);
 801                 strbuf_release(&path);
 802                 return;
 803         }
 804         strbuf_addch(&path, '/');
 805         dirnamelen = path.len;
 806         while ((de = readdir(dir)) != NULL) {
 807                 if (is_dot_or_dotdot(de->d_name))
 808                         continue;
 809
 810                 strbuf_setlen(&path, dirnamelen);
 811                 strbuf_addstr(&path, de->d_name);
 812
 813                 fn(path.buf, path.len, de->d_name, data);
 814         }
 815
 816         closedir(dir);
 817         strbuf_release(&path);
 818 }
 819
 820 struct prepare_pack_data {
 821         struct repository *r;
 822         struct string_list *garbage;
 823         int local;
 824         struct multi_pack_index *m;
 825 };
 826
 827 static void prepare_pack(const char *full_name, size_t full_name_len,
 828                          const char *file_name, void *_data)
 829 {
 830         struct prepare_pack_data *data = (struct prepare_pack_data *)_data;
 831         struct packed_git *p;
 832         size_t base_len = full_name_len;
 833
 834         if (strip_suffix_mem(full_name, &base_len, ".idx") &&
 835             !(data->m && midx_contains_pack(data->m, file_name))) {
 836                 /* Don't reopen a pack we already have. */
 837                 for (p = data->r->objects->packed_git; p; p = p->next) {
 838                         size_t len;
 839                         if (strip_suffix(p->pack_name, ".pack", &len) &&
 840                             len == base_len &&
 841                             !memcmp(p->pack_name, full_name, len))
 842                                 break;
 843                 }
 844
 845                 if (!p) {
 846                         p = add_packed_git(full_name, full_name_len, data->local);
 847                         if (p)
 848                                 install_packed_git(data->r, p);
 849                 }
 850         }
 851
 852         if (!report_garbage)
 853                 return;
 854
 855         if (!strcmp(file_name, "multi-pack-index"))
 856                 return;
 857         if (ends_with(file_name, ".idx") ||
 858             ends_with(file_name, ".pack") ||
 859             ends_with(file_name, ".bitmap") ||
 860             ends_with(file_name, ".keep") ||
 861             ends_with(file_name, ".promisor"))
 862                 string_list_append(data->garbage, full_name);
 863         else
 864                 report_garbage(PACKDIR_FILE_GARBAGE, full_name);
 865 }
 866
 867 static void prepare_packed_git_one(struct repository *r, char *objdir, int local)
 868 {
 869         struct prepare_pack_data data;
 870         struct string_list garbage = STRING_LIST_INIT_DUP;
 871
 872         data.m = r->objects->multi_pack_index;
 873
 874         /* look for the multi-pack-index for this object directory */
 875         while (data.m && strcmp(data.m->object_dir, objdir))
 876                 data.m = data.m->next;
 877
 878         data.r = r;
 879         data.garbage = &garbage;
 880         data.local = local;
 881
 882         for_each_file_in_pack_dir(objdir, prepare_pack, &data);
 883
 884         report_pack_garbage(data.garbage);
 885         string_list_clear(data.garbage, 0);
 886 }
 887
 888 static void prepare_packed_git(struct repository *r);
 889 /*
 890  * Give a fast, rough count of the number of objects in the repository. This
 891  * ignores loose objects completely. If you have a lot of them, then either
 892  * you should repack because your performance will be awful, or they are
 893  * all unreachable objects about to be pruned, in which case they're not really
 894  * interesting as a measure of repo size in the first place.
 895  */
 896 unsigned long approximate_object_count(void)
 897 {
 898         if (!the_repository->objects->approximate_object_count_valid) {
 899                 unsigned long count;
 900                 struct multi_pack_index *m;
 901                 struct packed_git *p;
 902
 903                 prepare_packed_git(the_repository);
 904                 count = 0;
 905                 for (m = get_multi_pack_index(the_repository); m; m = m->next)
 906                         count += m->num_objects;
 907                 for (p = the_repository->objects->packed_git; p; p = p->next) {
 908                         if (open_pack_index(p))
 909                                 continue;
 910                         count += p->num_objects;
 911                 }
 912                 the_repository->objects->approximate_object_count = count;
 913         }
 914         return the_repository->objects->approximate_object_count;
 915 }
 916
 917 static void *get_next_packed_git(const void *p)
 918 {
 919         return ((const struct packed_git *)p)->next;
 920 }
 921
 922 static void set_next_packed_git(void *p, void *next)
 923 {
 924         ((struct packed_git *)p)->next = next;
 925 }
 926
 927 static int sort_pack(const void *a_, const void *b_)
 928 {
 929         const struct packed_git *a = a_;
 930         const struct packed_git *b = b_;
 931         int st;
 932
 933         /*
 934          * Local packs tend to contain objects specific to our
 935          * variant of the project than remote ones.  In addition,
 936          * remote ones could be on a network mounted filesystem.
 937          * Favor local ones for these reasons.
 938          */
 939         st = a->pack_local - b->pack_local;
 940         if (st)
 941                 return -st;
 942
 943         /*
 944          * Younger packs tend to contain more recent objects,
 945          * and more recent objects tend to get accessed more
 946          * often.
 947          */
 948         if (a->mtime < b->mtime)
 949                 return 1;
 950         else if (a->mtime == b->mtime)
 951                 return 0;
 952         return -1;
 953 }
 954
 955 static void rearrange_packed_git(struct repository *r)
 956 {
 957         r->objects->packed_git = llist_mergesort(
 958                 r->objects->packed_git, get_next_packed_git,
 959                 set_next_packed_git, sort_pack);
 960 }
 961
 962 static void prepare_packed_git_mru(struct repository *r)
 963 {
 964         struct packed_git *p;
 965
 966         INIT_LIST_HEAD(&r->objects->packed_git_mru);
 967
 968         for (p = r->objects->packed_git; p; p = p->next)
 969                 list_add_tail(&p->mru, &r->objects->packed_git_mru);
 970 }
 971
 972 static void prepare_packed_git(struct repository *r)
 973 {
 974         struct object_directory *odb;
 975
 976         if (r->objects->packed_git_initialized)
 977                 return;
 978
 979         prepare_alt_odb(r);
 980         for (odb = r->objects->odb; odb; odb = odb->next) {
 981                 int local = (odb == r->objects->odb);
 982                 prepare_multi_pack_index_one(r, odb->path, local);
 983                 prepare_packed_git_one(r, odb->path, local);
 984         }
 985         rearrange_packed_git(r);
 986
 987         r->objects->all_packs = NULL;
 988
 989         prepare_packed_git_mru(r);
 990         r->objects->packed_git_initialized = 1;
 991 }
 992
 993 void reprepare_packed_git(struct repository *r)
 994 {
 995         struct object_directory *odb;
 996
 997         for (odb = r->objects->odb; odb; odb = odb->next)
 998                 odb_clear_loose_cache(odb);
 999
1000         r->objects->approximate_object_count_valid = 0;
1001         r->objects->packed_git_initialized = 0;
1002         prepare_packed_git(r);
1003 }
1004
1005 struct packed_git *get_packed_git(struct repository *r)
1006 {
1007         prepare_packed_git(r);
1008         return r->objects->packed_git;
1009 }
1010
1011 struct multi_pack_index *get_multi_pack_index(struct repository *r)
1012 {
1013         prepare_packed_git(r);
1014         return r->objects->multi_pack_index;
1015 }
1016
1017 struct packed_git *get_all_packs(struct repository *r)
1018 {
1019         prepare_packed_git(r);
1020
1021         if (!r->objects->all_packs) {
1022                 struct packed_git *p = r->objects->packed_git;
1023                 struct multi_pack_index *m;
1024
1025                 for (m = r->objects->multi_pack_index; m; m = m->next) {
1026                         uint32_t i;
1027                         for (i = 0; i < m->num_packs; i++) {
1028                                 if (!prepare_midx_pack(m, i)) {
1029                                         m->packs[i]->next = p;
1030                                         p = m->packs[i];
1031                                 }
1032                         }
1033                 }
1034
1035                 r->objects->all_packs = p;
1036         }
1037
1038         return r->objects->all_packs;
1039 }
1040
1041 struct list_head *get_packed_git_mru(struct repository *r)
1042 {
1043         prepare_packed_git(r);
1044         return &r->objects->packed_git_mru;
1045 }
1046
1047 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1048                 unsigned long len, enum object_type *type, unsigned long *sizep)
1049 {
1050         unsigned shift;
1051         unsigned long size, c;
1052         unsigned long used = 0;
1053
1054         c = buf[used++];
1055         *type = (c >> 4) & 7;
1056         size = c & 15;
1057         shift = 4;
1058         while (c & 0x80) {
1059                 if (len <= used || bitsizeof(long) <= shift) {
1060                         error("bad object header");
1061                         size = used = 0;
1062                         break;
1063                 }
1064                 c = buf[used++];
1065                 size += (c & 0x7f) << shift;
1066                 shift += 7;
1067         }
1068         *sizep = size;
1069         return used;
1070 }
1071
1072 unsigned long get_size_from_delta(struct packed_git *p,
1073                                   struct pack_window **w_curs,
1074                                   off_t curpos)
1075 {
1076         const unsigned char *data;
1077         unsigned char delta_head[20], *in;
1078         git_zstream stream;
1079         int st;
1080
1081         memset(&stream, 0, sizeof(stream));
1082         stream.next_out = delta_head;
1083         stream.avail_out = sizeof(delta_head);
1084
1085         git_inflate_init(&stream);
1086         do {
1087                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1088                 stream.next_in = in;
1089                 st = git_inflate(&stream, Z_FINISH);
1090                 curpos += stream.next_in - in;
1091         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1092                  stream.total_out < sizeof(delta_head));
1093         git_inflate_end(&stream);
1094         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1095                 error("delta data unpack-initial failed");
1096                 return 0;
1097         }
1098
1099         /* Examine the initial part of the delta to figure out
1100          * the result size.
1101          */
1102         data = delta_head;
1103
1104         /* ignore base size */
1105         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1106
1107         /* Read the result size */
1108         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1109 }
1110
1111 int unpack_object_header(struct packed_git *p,
1112                          struct pack_window **w_curs,
1113                          off_t *curpos,
1114                          unsigned long *sizep)
1115 {
1116         unsigned char *base;
1117         unsigned long left;
1118         unsigned long used;
1119         enum object_type type;
1120
1121         /* use_pack() assures us we have [base, base + 20) available
1122          * as a range that we can look at.  (Its actually the hash
1123          * size that is assured.)  With our object header encoding
1124          * the maximum deflated object size is 2^137, which is just
1125          * insane, so we know won't exceed what we have been given.
1126          */
1127         base = use_pack(p, w_curs, *curpos, &left);
1128         used = unpack_object_header_buffer(base, left, &type, sizep);
1129         if (!used) {
1130                 type = OBJ_BAD;
1131         } else
1132                 *curpos += used;
1133
1134         return type;
1135 }
1136
1137 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1138 {
1139         unsigned i;
1140         const unsigned hashsz = the_hash_algo->rawsz;
1141         for (i = 0; i < p->num_bad_objects; i++)
1142                 if (hasheq(sha1, p->bad_object_sha1 + hashsz * i))
1143                         return;
1144         p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1145                                       st_mult(GIT_MAX_RAWSZ,
1146                                               st_add(p->num_bad_objects, 1)));
1147         hashcpy(p->bad_object_sha1 + hashsz * p->num_bad_objects, sha1);
1148         p->num_bad_objects++;
1149 }
1150
1151 const struct packed_git *has_packed_and_bad(struct repository *r,
1152                                             const unsigned char *sha1)
1153 {
1154         struct packed_git *p;
1155         unsigned i;
1156
1157         for (p = r->objects->packed_git; p; p = p->next)
1158                 for (i = 0; i < p->num_bad_objects; i++)
1159                         if (hasheq(sha1,
1160                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1161                                 return p;
1162         return NULL;
1163 }
1164
1165 static off_t get_delta_base(struct packed_git *p,
1166                                     struct pack_window **w_curs,
1167                                     off_t *curpos,
1168                                     enum object_type type,
1169                                     off_t delta_obj_offset)
1170 {
1171         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1172         off_t base_offset;
1173
1174         /* use_pack() assured us we have [base_info, base_info + 20)
1175          * as a range that we can look at without walking off the
1176          * end of the mapped window.  Its actually the hash size
1177          * that is assured.  An OFS_DELTA longer than the hash size
1178          * is stupid, as then a REF_DELTA would be smaller to store.
1179          */
1180         if (type == OBJ_OFS_DELTA) {
1181                 unsigned used = 0;
1182                 unsigned char c = base_info[used++];
1183                 base_offset = c & 127;
1184                 while (c & 128) {
1185                         base_offset += 1;
1186                         if (!base_offset || MSB(base_offset, 7))
1187                                 return 0;  /* overflow */
1188                         c = base_info[used++];
1189                         base_offset = (base_offset << 7) + (c & 127);
1190                 }
1191                 base_offset = delta_obj_offset - base_offset;
1192                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1193                         return 0;  /* out of bound */
1194                 *curpos += used;
1195         } else if (type == OBJ_REF_DELTA) {
1196                 /* The base entry _must_ be in the same pack */
1197                 base_offset = find_pack_entry_one(base_info, p);
1198                 *curpos += the_hash_algo->rawsz;
1199         } else
1200                 die("I am totally screwed");
1201         return base_offset;
1202 }
1203
1204 /*
1205  * Like get_delta_base above, but we return the sha1 instead of the pack
1206  * offset. This means it is cheaper for REF deltas (we do not have to do
1207  * the final object lookup), but more expensive for OFS deltas (we
1208  * have to load the revidx to convert the offset back into a sha1).
1209  */
1210 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1211                                                 struct pack_window **w_curs,
1212                                                 off_t curpos,
1213                                                 enum object_type type,
1214                                                 off_t delta_obj_offset)
1215 {
1216         if (type == OBJ_REF_DELTA) {
1217                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1218                 return base;
1219         } else if (type == OBJ_OFS_DELTA) {
1220                 struct revindex_entry *revidx;
1221                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1222                                                    type, delta_obj_offset);
1223
1224                 if (!base_offset)
1225                         return NULL;
1226
1227                 revidx = find_pack_revindex(p, base_offset);
1228                 if (!revidx)
1229                         return NULL;
1230
1231                 return nth_packed_object_sha1(p, revidx->nr);
1232         } else
1233                 return NULL;
1234 }
1235
1236 static int retry_bad_packed_offset(struct repository *r,
1237                                    struct packed_git *p,
1238                                    off_t obj_offset)
1239 {
1240         int type;
1241         struct revindex_entry *revidx;
1242         struct object_id oid;
1243         revidx = find_pack_revindex(p, obj_offset);
1244         if (!revidx)
1245                 return OBJ_BAD;
1246         nth_packed_object_oid(&oid, p, revidx->nr);
1247         mark_bad_packed_object(p, oid.hash);
1248         type = oid_object_info(r, &oid, NULL);
1249         if (type <= OBJ_NONE)
1250                 return OBJ_BAD;
1251         return type;
1252 }
1253
1254 #define POI_STACK_PREALLOC 64
1255
1256 static enum object_type packed_to_object_type(struct repository *r,
1257                                               struct packed_git *p,
1258                                               off_t obj_offset,
1259                                               enum object_type type,
1260                                               struct pack_window **w_curs,
1261                                               off_t curpos)
1262 {
1263         off_t small_poi_stack[POI_STACK_PREALLOC];
1264         off_t *poi_stack = small_poi_stack;
1265         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1266
1267         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1268                 off_t base_offset;
1269                 unsigned long size;
1270                 /* Push the object we're going to leave behind */
1271                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1272                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1273                         ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1274                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1275                 } else {
1276                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1277                 }
1278                 poi_stack[poi_stack_nr++] = obj_offset;
1279                 /* If parsing the base offset fails, just unwind */
1280                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1281                 if (!base_offset)
1282                         goto unwind;
1283                 curpos = obj_offset = base_offset;
1284                 type = unpack_object_header(p, w_curs, &curpos, &size);
1285                 if (type <= OBJ_NONE) {
1286                         /* If getting the base itself fails, we first
1287                          * retry the base, otherwise unwind */
1288                         type = retry_bad_packed_offset(r, p, base_offset);
1289                         if (type > OBJ_NONE)
1290                                 goto out;
1291                         goto unwind;
1292                 }
1293         }
1294
1295         switch (type) {
1296         case OBJ_BAD:
1297         case OBJ_COMMIT:
1298         case OBJ_TREE:
1299         case OBJ_BLOB:
1300         case OBJ_TAG:
1301                 break;
1302         default:
1303                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1304                       type, (uintmax_t)obj_offset, p->pack_name);
1305                 type = OBJ_BAD;
1306         }
1307
1308 out:
1309         if (poi_stack != small_poi_stack)
1310                 free(poi_stack);
1311         return type;
1312
1313 unwind:
1314         while (poi_stack_nr) {
1315                 obj_offset = poi_stack[--poi_stack_nr];
1316                 type = retry_bad_packed_offset(r, p, obj_offset);
1317                 if (type > OBJ_NONE)
1318                         goto out;
1319         }
1320         type = OBJ_BAD;
1321         goto out;
1322 }
1323
1324 static struct hashmap delta_base_cache;
1325 static size_t delta_base_cached;
1326
1327 static LIST_HEAD(delta_base_cache_lru);
1328
1329 struct delta_base_cache_key {
1330         struct packed_git *p;
1331         off_t base_offset;
1332 };
1333
1334 struct delta_base_cache_entry {
1335         struct hashmap hash;
1336         struct delta_base_cache_key key;
1337         struct list_head lru;
1338         void *data;
1339         unsigned long size;
1340         enum object_type type;
1341 };
1342
1343 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1344 {
1345         unsigned int hash;
1346
1347         hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1348         hash += (hash >> 8) + (hash >> 16);
1349         return hash;
1350 }
1351
1352 static struct delta_base_cache_entry *
1353 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1354 {
1355         struct hashmap_entry entry;
1356         struct delta_base_cache_key key;
1357
1358         if (!delta_base_cache.cmpfn)
1359                 return NULL;
1360
1361         hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1362         key.p = p;
1363         key.base_offset = base_offset;
1364         return hashmap_get(&delta_base_cache, &entry, &key);
1365 }
1366
1367 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1368                                    const struct delta_base_cache_key *b)
1369 {
1370         return a->p == b->p && a->base_offset == b->base_offset;
1371 }
1372
1373 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1374                                      const void *va, const void *vb,
1375                                      const void *vkey)
1376 {
1377         const struct delta_base_cache_entry *a = va, *b = vb;
1378         const struct delta_base_cache_key *key = vkey;
1379         if (key)
1380                 return !delta_base_cache_key_eq(&a->key, key);
1381         else
1382                 return !delta_base_cache_key_eq(&a->key, &b->key);
1383 }
1384
1385 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1386 {
1387         return !!get_delta_base_cache_entry(p, base_offset);
1388 }
1389
1390 /*
1391  * Remove the entry from the cache, but do _not_ free the associated
1392  * entry data. The caller takes ownership of the "data" buffer, and
1393  * should copy out any fields it wants before detaching.
1394  */
1395 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1396 {
1397         hashmap_remove(&delta_base_cache, ent, &ent->key);
1398         list_del(&ent->lru);
1399         delta_base_cached -= ent->size;
1400         free(ent);
1401 }
1402
1403 static void *cache_or_unpack_entry(struct repository *r, struct packed_git *p,
1404                                    off_t base_offset, unsigned long *base_size,
1405                                    enum object_type *type)
1406 {
1407         struct delta_base_cache_entry *ent;
1408
1409         ent = get_delta_base_cache_entry(p, base_offset);
1410         if (!ent)
1411                 return unpack_entry(r, p, base_offset, type, base_size);
1412
1413         if (type)
1414                 *type = ent->type;
1415         if (base_size)
1416                 *base_size = ent->size;
1417         return xmemdupz(ent->data, ent->size);
1418 }
1419
1420 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1421 {
1422         free(ent->data);
1423         detach_delta_base_cache_entry(ent);
1424 }
1425
1426 void clear_delta_base_cache(void)
1427 {
1428         struct list_head *lru, *tmp;
1429         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1430                 struct delta_base_cache_entry *entry =
1431                         list_entry(lru, struct delta_base_cache_entry, lru);
1432                 release_delta_base_cache(entry);
1433         }
1434 }
1435
1436 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1437         void *base, unsigned long base_size, enum object_type type)
1438 {
1439         struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1440         struct list_head *lru, *tmp;
1441
1442         delta_base_cached += base_size;
1443
1444         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1445                 struct delta_base_cache_entry *f =
1446                         list_entry(lru, struct delta_base_cache_entry, lru);
1447                 if (delta_base_cached <= delta_base_cache_limit)
1448                         break;
1449                 release_delta_base_cache(f);
1450         }
1451
1452         ent->key.p = p;
1453         ent->key.base_offset = base_offset;
1454         ent->type = type;
1455         ent->data = base;
1456         ent->size = base_size;
1457         list_add_tail(&ent->lru, &delta_base_cache_lru);
1458
1459         if (!delta_base_cache.cmpfn)
1460                 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1461         hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1462         hashmap_add(&delta_base_cache, ent);
1463 }
1464
1465 int packed_object_info(struct repository *r, struct packed_git *p,
1466                        off_t obj_offset, struct object_info *oi)
1467 {
1468         struct pack_window *w_curs = NULL;
1469         unsigned long size;
1470         off_t curpos = obj_offset;
1471         enum object_type type;
1472
1473         /*
1474          * We always get the representation type, but only convert it to
1475          * a "real" type later if the caller is interested.
1476          */
1477         if (oi->contentp) {
1478                 *oi->contentp = cache_or_unpack_entry(r, p, obj_offset, oi->sizep,
1479                                                       &type);
1480                 if (!*oi->contentp)
1481                         type = OBJ_BAD;
1482         } else {
1483                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1484         }
1485
1486         if (!oi->contentp && oi->sizep) {
1487                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1488                         off_t tmp_pos = curpos;
1489                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1490                                                            type, obj_offset);
1491                         if (!base_offset) {
1492                                 type = OBJ_BAD;
1493                                 goto out;
1494                         }
1495                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1496                         if (*oi->sizep == 0) {
1497                                 type = OBJ_BAD;
1498                                 goto out;
1499                         }
1500                 } else {
1501                         *oi->sizep = size;
1502                 }
1503         }
1504
1505         if (oi->disk_sizep) {
1506                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1507                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1508         }
1509
1510         if (oi->typep || oi->type_name) {
1511                 enum object_type ptot;
1512                 ptot = packed_to_object_type(r, p, obj_offset,
1513                                              type, &w_curs, curpos);
1514                 if (oi->typep)
1515                         *oi->typep = ptot;
1516                 if (oi->type_name) {
1517                         const char *tn = type_name(ptot);
1518                         if (tn)
1519                                 strbuf_addstr(oi->type_name, tn);
1520                 }
1521                 if (ptot < 0) {
1522                         type = OBJ_BAD;
1523                         goto out;
1524                 }
1525         }
1526
1527         if (oi->delta_base_sha1) {
1528                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1529                         const unsigned char *base;
1530
1531                         base = get_delta_base_sha1(p, &w_curs, curpos,
1532                                                    type, obj_offset);
1533                         if (!base) {
1534                                 type = OBJ_BAD;
1535                                 goto out;
1536                         }
1537
1538                         hashcpy(oi->delta_base_sha1, base);
1539                 } else
1540                         hashclr(oi->delta_base_sha1);
1541         }
1542
1543         oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1544                                                           OI_PACKED;
1545
1546 out:
1547         unuse_pack(&w_curs);
1548         return type;
1549 }
1550
1551 static void *unpack_compressed_entry(struct packed_git *p,
1552                                     struct pack_window **w_curs,
1553                                     off_t curpos,
1554                                     unsigned long size)
1555 {
1556         int st;
1557         git_zstream stream;
1558         unsigned char *buffer, *in;
1559
1560         buffer = xmallocz_gently(size);
1561         if (!buffer)
1562                 return NULL;
1563         memset(&stream, 0, sizeof(stream));
1564         stream.next_out = buffer;
1565         stream.avail_out = size + 1;
1566
1567         git_inflate_init(&stream);
1568         do {
1569                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1570                 stream.next_in = in;
1571                 st = git_inflate(&stream, Z_FINISH);
1572                 if (!stream.avail_out)
1573                         break; /* the payload is larger than it should be */
1574                 curpos += stream.next_in - in;
1575         } while (st == Z_OK || st == Z_BUF_ERROR);
1576         git_inflate_end(&stream);
1577         if ((st != Z_STREAM_END) || stream.total_out != size) {
1578                 free(buffer);
1579                 return NULL;
1580         }
1581
1582         /* versions of zlib can clobber unconsumed portion of outbuf */
1583         buffer[size] = '\0';
1584
1585         return buffer;
1586 }
1587
1588 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1589 {
1590         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1591         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1592                          p->pack_name, (uintmax_t)obj_offset);
1593 }
1594
1595 int do_check_packed_object_crc;
1596
1597 #define UNPACK_ENTRY_STACK_PREALLOC 64
1598 struct unpack_entry_stack_ent {
1599         off_t obj_offset;
1600         off_t curpos;
1601         unsigned long size;
1602 };
1603
1604 static void *read_object(struct repository *r,
1605                          const struct object_id *oid,
1606                          enum object_type *type,
1607                          unsigned long *size)
1608 {
1609         struct object_info oi = OBJECT_INFO_INIT;
1610         void *content;
1611         oi.typep = type;
1612         oi.sizep = size;
1613         oi.contentp = &content;
1614
1615         if (oid_object_info_extended(r, oid, &oi, 0) < 0)
1616                 return NULL;
1617         return content;
1618 }
1619
1620 void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset,
1621                    enum object_type *final_type, unsigned long *final_size)
1622 {
1623         struct pack_window *w_curs = NULL;
1624         off_t curpos = obj_offset;
1625         void *data = NULL;
1626         unsigned long size;
1627         enum object_type type;
1628         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1629         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1630         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1631         int base_from_cache = 0;
1632
1633         write_pack_access_log(p, obj_offset);
1634
1635         /* PHASE 1: drill down to the innermost base object */
1636         for (;;) {
1637                 off_t base_offset;
1638                 int i;
1639                 struct delta_base_cache_entry *ent;
1640
1641                 ent = get_delta_base_cache_entry(p, curpos);
1642                 if (ent) {
1643                         type = ent->type;
1644                         data = ent->data;
1645                         size = ent->size;
1646                         detach_delta_base_cache_entry(ent);
1647                         base_from_cache = 1;
1648                         break;
1649                 }
1650
1651                 if (do_check_packed_object_crc && p->index_version > 1) {
1652                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1653                         off_t len = revidx[1].offset - obj_offset;
1654                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1655                                 struct object_id oid;
1656                                 nth_packed_object_oid(&oid, p, revidx->nr);
1657                                 error("bad packed object CRC for %s",
1658                                       oid_to_hex(&oid));
1659                                 mark_bad_packed_object(p, oid.hash);
1660                                 data = NULL;
1661                                 goto out;
1662                         }
1663                 }
1664
1665                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1666                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1667                         break;
1668
1669                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1670                 if (!base_offset) {
1671                         error("failed to validate delta base reference "
1672                               "at offset %"PRIuMAX" from %s",
1673                               (uintmax_t)curpos, p->pack_name);
1674                         /* bail to phase 2, in hopes of recovery */
1675                         data = NULL;
1676                         break;
1677                 }
1678
1679                 /* push object, proceed to base */
1680                 if (delta_stack_nr >= delta_stack_alloc
1681                     && delta_stack == small_delta_stack) {
1682                         delta_stack_alloc = alloc_nr(delta_stack_nr);
1683                         ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1684                         memcpy(delta_stack, small_delta_stack,
1685                                sizeof(*delta_stack)*delta_stack_nr);
1686                 } else {
1687                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1688                 }
1689                 i = delta_stack_nr++;
1690                 delta_stack[i].obj_offset = obj_offset;
1691                 delta_stack[i].curpos = curpos;
1692                 delta_stack[i].size = size;
1693
1694                 curpos = obj_offset = base_offset;
1695         }
1696
1697         /* PHASE 2: handle the base */
1698         switch (type) {
1699         case OBJ_OFS_DELTA:
1700         case OBJ_REF_DELTA:
1701                 if (data)
1702                         BUG("unpack_entry: left loop at a valid delta");
1703                 break;
1704         case OBJ_COMMIT:
1705         case OBJ_TREE:
1706         case OBJ_BLOB:
1707         case OBJ_TAG:
1708                 if (!base_from_cache)
1709                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
1710                 break;
1711         default:
1712                 data = NULL;
1713                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1714                       type, (uintmax_t)obj_offset, p->pack_name);
1715         }
1716
1717         /* PHASE 3: apply deltas in order */
1718
1719         /* invariants:
1720          *   'data' holds the base data, or NULL if there was corruption
1721          */
1722         while (delta_stack_nr) {
1723                 void *delta_data;
1724                 void *base = data;
1725                 void *external_base = NULL;
1726                 unsigned long delta_size, base_size = size;
1727                 int i;
1728
1729                 data = NULL;
1730
1731                 if (base)
1732                         add_delta_base_cache(p, obj_offset, base, base_size, type);
1733
1734                 if (!base) {
1735                         /*
1736                          * We're probably in deep shit, but let's try to fetch
1737                          * the required base anyway from another pack or loose.
1738                          * This is costly but should happen only in the presence
1739                          * of a corrupted pack, and is better than failing outright.
1740                          */
1741                         struct revindex_entry *revidx;
1742                         struct object_id base_oid;
1743                         revidx = find_pack_revindex(p, obj_offset);
1744                         if (revidx) {
1745                                 nth_packed_object_oid(&base_oid, p, revidx->nr);
1746                                 error("failed to read delta base object %s"
1747                                       " at offset %"PRIuMAX" from %s",
1748                                       oid_to_hex(&base_oid), (uintmax_t)obj_offset,
1749                                       p->pack_name);
1750                                 mark_bad_packed_object(p, base_oid.hash);
1751                                 base = read_object(r, &base_oid, &type, &base_size);
1752                                 external_base = base;
1753                         }
1754                 }
1755
1756                 i = --delta_stack_nr;
1757                 obj_offset = delta_stack[i].obj_offset;
1758                 curpos = delta_stack[i].curpos;
1759                 delta_size = delta_stack[i].size;
1760
1761                 if (!base)
1762                         continue;
1763
1764                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1765
1766                 if (!delta_data) {
1767                         error("failed to unpack compressed delta "
1768                               "at offset %"PRIuMAX" from %s",
1769                               (uintmax_t)curpos, p->pack_name);
1770                         data = NULL;
1771                         free(external_base);
1772                         continue;
1773                 }
1774
1775                 data = patch_delta(base, base_size,
1776                                    delta_data, delta_size,
1777                                    &size);
1778
1779                 /*
1780                  * We could not apply the delta; warn the user, but keep going.
1781                  * Our failure will be noticed either in the next iteration of
1782                  * the loop, or if this is the final delta, in the caller when
1783                  * we return NULL. Those code paths will take care of making
1784                  * a more explicit warning and retrying with another copy of
1785                  * the object.
1786                  */
1787                 if (!data)
1788                         error("failed to apply delta");
1789
1790                 free(delta_data);
1791                 free(external_base);
1792         }
1793
1794         if (final_type)
1795                 *final_type = type;
1796         if (final_size)
1797                 *final_size = size;
1798
1799 out:
1800         unuse_pack(&w_curs);
1801
1802         if (delta_stack != small_delta_stack)
1803                 free(delta_stack);
1804
1805         return data;
1806 }
1807
1808 int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result)
1809 {
1810         const unsigned char *index_fanout = p->index_data;
1811         const unsigned char *index_lookup;
1812         const unsigned int hashsz = the_hash_algo->rawsz;
1813         int index_lookup_width;
1814
1815         if (!index_fanout)
1816                 BUG("bsearch_pack called without a valid pack-index");
1817
1818         index_lookup = index_fanout + 4 * 256;
1819         if (p->index_version == 1) {
1820                 index_lookup_width = hashsz + 4;
1821                 index_lookup += 4;
1822         } else {
1823                 index_lookup_width = hashsz;
1824                 index_fanout += 8;
1825                 index_lookup += 8;
1826         }
1827
1828         return bsearch_hash(oid->hash, (const uint32_t*)index_fanout,
1829                             index_lookup, index_lookup_width, result);
1830 }
1831
1832 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1833                                             uint32_t n)
1834 {
1835         const unsigned char *index = p->index_data;
1836         const unsigned int hashsz = the_hash_algo->rawsz;
1837         if (!index) {
1838                 if (open_pack_index(p))
1839                         return NULL;
1840                 index = p->index_data;
1841         }
1842         if (n >= p->num_objects)
1843                 return NULL;
1844         index += 4 * 256;
1845         if (p->index_version == 1) {
1846                 return index + (hashsz + 4) * n + 4;
1847         } else {
1848                 index += 8;
1849                 return index + hashsz * n;
1850         }
1851 }
1852
1853 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1854                                               struct packed_git *p,
1855                                               uint32_t n)
1856 {
1857         const unsigned char *hash = nth_packed_object_sha1(p, n);
1858         if (!hash)
1859                 return NULL;
1860         hashcpy(oid->hash, hash);
1861         return oid;
1862 }
1863
1864 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1865 {
1866         const unsigned char *ptr = vptr;
1867         const unsigned char *start = p->index_data;
1868         const unsigned char *end = start + p->index_size;
1869         if (ptr < start)
1870                 die(_("offset before start of pack index for %s (corrupt index?)"),
1871                     p->pack_name);
1872         /* No need to check for underflow; .idx files must be at least 8 bytes */
1873         if (ptr >= end - 8)
1874                 die(_("offset beyond end of pack index for %s (truncated index?)"),
1875                     p->pack_name);
1876 }
1877
1878 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1879 {
1880         const unsigned char *index = p->index_data;
1881         const unsigned int hashsz = the_hash_algo->rawsz;
1882         index += 4 * 256;
1883         if (p->index_version == 1) {
1884                 return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
1885         } else {
1886                 uint32_t off;
1887                 index += 8 + p->num_objects * (hashsz + 4);
1888                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1889                 if (!(off & 0x80000000))
1890                         return off;
1891                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1892                 check_pack_index_ptr(p, index);
1893                 return get_be64(index);
1894         }
1895 }
1896
1897 off_t find_pack_entry_one(const unsigned char *sha1,
1898                                   struct packed_git *p)
1899 {
1900         const unsigned char *index = p->index_data;
1901         struct object_id oid;
1902         uint32_t result;
1903
1904         if (!index) {
1905                 if (open_pack_index(p))
1906                         return 0;
1907         }
1908
1909         hashcpy(oid.hash, sha1);
1910         if (bsearch_pack(&oid, p, &result))
1911                 return nth_packed_object_offset(p, result);
1912         return 0;
1913 }
1914
1915 int is_pack_valid(struct packed_git *p)
1916 {
1917         /* An already open pack is known to be valid. */
1918         if (p->pack_fd != -1)
1919                 return 1;
1920
1921         /* If the pack has one window completely covering the
1922          * file size, the pack is known to be valid even if
1923          * the descriptor is not currently open.
1924          */
1925         if (p->windows) {
1926                 struct pack_window *w = p->windows;
1927
1928                 if (!w->offset && w->len == p->pack_size)
1929                         return 1;
1930         }
1931
1932         /* Force the pack to open to prove its valid. */
1933         return !open_packed_git(p);
1934 }
1935
1936 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1937                                   struct packed_git *packs)
1938 {
1939         struct packed_git *p;
1940
1941         for (p = packs; p; p = p->next) {
1942                 if (find_pack_entry_one(sha1, p))
1943                         return p;
1944         }
1945         return NULL;
1946
1947 }
1948
1949 static int fill_pack_entry(const struct object_id *oid,
1950                            struct pack_entry *e,
1951                            struct packed_git *p)
1952 {
1953         off_t offset;
1954
1955         if (p->num_bad_objects) {
1956                 unsigned i;
1957                 for (i = 0; i < p->num_bad_objects; i++)
1958                         if (hasheq(oid->hash,
1959                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1960                                 return 0;
1961         }
1962
1963         offset = find_pack_entry_one(oid->hash, p);
1964         if (!offset)
1965                 return 0;
1966
1967         /*
1968          * We are about to tell the caller where they can locate the
1969          * requested object.  We better make sure the packfile is
1970          * still here and can be accessed before supplying that
1971          * answer, as it may have been deleted since the index was
1972          * loaded!
1973          */
1974         if (!is_pack_valid(p))
1975                 return 0;
1976         e->offset = offset;
1977         e->p = p;
1978         return 1;
1979 }
1980
1981 int find_pack_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e)
1982 {
1983         struct list_head *pos;
1984         struct multi_pack_index *m;
1985
1986         prepare_packed_git(r);
1987         if (!r->objects->packed_git && !r->objects->multi_pack_index)
1988                 return 0;
1989
1990         for (m = r->objects->multi_pack_index; m; m = m->next) {
1991                 if (fill_midx_entry(oid, e, m))
1992                         return 1;
1993         }
1994
1995         list_for_each(pos, &r->objects->packed_git_mru) {
1996                 struct packed_git *p = list_entry(pos, struct packed_git, mru);
1997                 if (fill_pack_entry(oid, e, p)) {
1998                         list_move(&p->mru, &r->objects->packed_git_mru);
1999                         return 1;
2000                 }
2001         }
2002         return 0;
2003 }
2004
2005 int has_object_pack(const struct object_id *oid)
2006 {
2007         struct pack_entry e;
2008         return find_pack_entry(the_repository, oid, &e);
2009 }
2010
2011 int has_pack_index(const unsigned char *sha1)
2012 {
2013         struct stat st;
2014         if (stat(sha1_pack_index_name(sha1), &st))
2015                 return 0;
2016         return 1;
2017 }
2018
2019 int for_each_object_in_pack(struct packed_git *p,
2020                             each_packed_object_fn cb, void *data,
2021                             enum for_each_object_flags flags)
2022 {
2023         uint32_t i;
2024         int r = 0;
2025
2026         if (flags & FOR_EACH_OBJECT_PACK_ORDER)
2027                 load_pack_revindex(p);
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 }