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 alternate_object_database *alt;
 975
 976         if (r->objects->packed_git_initialized)
 977                 return;
 978         prepare_multi_pack_index_one(r, r->objects->objectdir, 1);
 979         prepare_packed_git_one(r, r->objects->objectdir, 1);
 980         prepare_alt_odb(r);
 981         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 982                 prepare_multi_pack_index_one(r, alt->path, 0);
 983                 prepare_packed_git_one(r, alt->path, 0);
 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         r->objects->approximate_object_count_valid = 0;
 996         r->objects->packed_git_initialized = 0;
 997         prepare_packed_git(r);
 998 }
 999
1000 struct packed_git *get_packed_git(struct repository *r)
1001 {
1002         prepare_packed_git(r);
1003         return r->objects->packed_git;
1004 }
1005
1006 struct multi_pack_index *get_multi_pack_index(struct repository *r)
1007 {
1008         prepare_packed_git(r);
1009         return r->objects->multi_pack_index;
1010 }
1011
1012 struct packed_git *get_all_packs(struct repository *r)
1013 {
1014         prepare_packed_git(r);
1015
1016         if (!r->objects->all_packs) {
1017                 struct packed_git *p = r->objects->packed_git;
1018                 struct multi_pack_index *m;
1019
1020                 for (m = r->objects->multi_pack_index; m; m = m->next) {
1021                         uint32_t i;
1022                         for (i = 0; i < m->num_packs; i++) {
1023                                 if (!prepare_midx_pack(m, i)) {
1024                                         m->packs[i]->next = p;
1025                                         p = m->packs[i];
1026                                 }
1027                         }
1028                 }
1029
1030                 r->objects->all_packs = p;
1031         }
1032
1033         return r->objects->all_packs;
1034 }
1035
1036 struct list_head *get_packed_git_mru(struct repository *r)
1037 {
1038         prepare_packed_git(r);
1039         return &r->objects->packed_git_mru;
1040 }
1041
1042 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1043                 unsigned long len, enum object_type *type, unsigned long *sizep)
1044 {
1045         unsigned shift;
1046         unsigned long size, c;
1047         unsigned long used = 0;
1048
1049         c = buf[used++];
1050         *type = (c >> 4) & 7;
1051         size = c & 15;
1052         shift = 4;
1053         while (c & 0x80) {
1054                 if (len <= used || bitsizeof(long) <= shift) {
1055                         error("bad object header");
1056                         size = used = 0;
1057                         break;
1058                 }
1059                 c = buf[used++];
1060                 size += (c & 0x7f) << shift;
1061                 shift += 7;
1062         }
1063         *sizep = size;
1064         return used;
1065 }
1066
1067 unsigned long get_size_from_delta(struct packed_git *p,
1068                                   struct pack_window **w_curs,
1069                                   off_t curpos)
1070 {
1071         const unsigned char *data;
1072         unsigned char delta_head[20], *in;
1073         git_zstream stream;
1074         int st;
1075
1076         memset(&stream, 0, sizeof(stream));
1077         stream.next_out = delta_head;
1078         stream.avail_out = sizeof(delta_head);
1079
1080         git_inflate_init(&stream);
1081         do {
1082                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1083                 stream.next_in = in;
1084                 st = git_inflate(&stream, Z_FINISH);
1085                 curpos += stream.next_in - in;
1086         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1087                  stream.total_out < sizeof(delta_head));
1088         git_inflate_end(&stream);
1089         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1090                 error("delta data unpack-initial failed");
1091                 return 0;
1092         }
1093
1094         /* Examine the initial part of the delta to figure out
1095          * the result size.
1096          */
1097         data = delta_head;
1098
1099         /* ignore base size */
1100         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1101
1102         /* Read the result size */
1103         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1104 }
1105
1106 int unpack_object_header(struct packed_git *p,
1107                          struct pack_window **w_curs,
1108                          off_t *curpos,
1109                          unsigned long *sizep)
1110 {
1111         unsigned char *base;
1112         unsigned long left;
1113         unsigned long used;
1114         enum object_type type;
1115
1116         /* use_pack() assures us we have [base, base + 20) available
1117          * as a range that we can look at.  (Its actually the hash
1118          * size that is assured.)  With our object header encoding
1119          * the maximum deflated object size is 2^137, which is just
1120          * insane, so we know won't exceed what we have been given.
1121          */
1122         base = use_pack(p, w_curs, *curpos, &left);
1123         used = unpack_object_header_buffer(base, left, &type, sizep);
1124         if (!used) {
1125                 type = OBJ_BAD;
1126         } else
1127                 *curpos += used;
1128
1129         return type;
1130 }
1131
1132 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1133 {
1134         unsigned i;
1135         const unsigned hashsz = the_hash_algo->rawsz;
1136         for (i = 0; i < p->num_bad_objects; i++)
1137                 if (hasheq(sha1, p->bad_object_sha1 + hashsz * i))
1138                         return;
1139         p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1140                                       st_mult(GIT_MAX_RAWSZ,
1141                                               st_add(p->num_bad_objects, 1)));
1142         hashcpy(p->bad_object_sha1 + hashsz * p->num_bad_objects, sha1);
1143         p->num_bad_objects++;
1144 }
1145
1146 const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1147 {
1148         struct packed_git *p;
1149         unsigned i;
1150
1151         for (p = the_repository->objects->packed_git; p; p = p->next)
1152                 for (i = 0; i < p->num_bad_objects; i++)
1153                         if (hasheq(sha1,
1154                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1155                                 return p;
1156         return NULL;
1157 }
1158
1159 static off_t get_delta_base(struct packed_git *p,
1160                                     struct pack_window **w_curs,
1161                                     off_t *curpos,
1162                                     enum object_type type,
1163                                     off_t delta_obj_offset)
1164 {
1165         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1166         off_t base_offset;
1167
1168         /* use_pack() assured us we have [base_info, base_info + 20)
1169          * as a range that we can look at without walking off the
1170          * end of the mapped window.  Its actually the hash size
1171          * that is assured.  An OFS_DELTA longer than the hash size
1172          * is stupid, as then a REF_DELTA would be smaller to store.
1173          */
1174         if (type == OBJ_OFS_DELTA) {
1175                 unsigned used = 0;
1176                 unsigned char c = base_info[used++];
1177                 base_offset = c & 127;
1178                 while (c & 128) {
1179                         base_offset += 1;
1180                         if (!base_offset || MSB(base_offset, 7))
1181                                 return 0;  /* overflow */
1182                         c = base_info[used++];
1183                         base_offset = (base_offset << 7) + (c & 127);
1184                 }
1185                 base_offset = delta_obj_offset - base_offset;
1186                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1187                         return 0;  /* out of bound */
1188                 *curpos += used;
1189         } else if (type == OBJ_REF_DELTA) {
1190                 /* The base entry _must_ be in the same pack */
1191                 base_offset = find_pack_entry_one(base_info, p);
1192                 *curpos += the_hash_algo->rawsz;
1193         } else
1194                 die("I am totally screwed");
1195         return base_offset;
1196 }
1197
1198 /*
1199  * Like get_delta_base above, but we return the sha1 instead of the pack
1200  * offset. This means it is cheaper for REF deltas (we do not have to do
1201  * the final object lookup), but more expensive for OFS deltas (we
1202  * have to load the revidx to convert the offset back into a sha1).
1203  */
1204 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1205                                                 struct pack_window **w_curs,
1206                                                 off_t curpos,
1207                                                 enum object_type type,
1208                                                 off_t delta_obj_offset)
1209 {
1210         if (type == OBJ_REF_DELTA) {
1211                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1212                 return base;
1213         } else if (type == OBJ_OFS_DELTA) {
1214                 struct revindex_entry *revidx;
1215                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1216                                                    type, delta_obj_offset);
1217
1218                 if (!base_offset)
1219                         return NULL;
1220
1221                 revidx = find_pack_revindex(p, base_offset);
1222                 if (!revidx)
1223                         return NULL;
1224
1225                 return nth_packed_object_sha1(p, revidx->nr);
1226         } else
1227                 return NULL;
1228 }
1229
1230 static int retry_bad_packed_offset(struct repository *r,
1231                                    struct packed_git *p,
1232                                    off_t obj_offset)
1233 {
1234         int type;
1235         struct revindex_entry *revidx;
1236         struct object_id oid;
1237         revidx = find_pack_revindex(p, obj_offset);
1238         if (!revidx)
1239                 return OBJ_BAD;
1240         nth_packed_object_oid(&oid, p, revidx->nr);
1241         mark_bad_packed_object(p, oid.hash);
1242         type = oid_object_info(r, &oid, NULL);
1243         if (type <= OBJ_NONE)
1244                 return OBJ_BAD;
1245         return type;
1246 }
1247
1248 #define POI_STACK_PREALLOC 64
1249
1250 static enum object_type packed_to_object_type(struct repository *r,
1251                                               struct packed_git *p,
1252                                               off_t obj_offset,
1253                                               enum object_type type,
1254                                               struct pack_window **w_curs,
1255                                               off_t curpos)
1256 {
1257         off_t small_poi_stack[POI_STACK_PREALLOC];
1258         off_t *poi_stack = small_poi_stack;
1259         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1260
1261         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1262                 off_t base_offset;
1263                 unsigned long size;
1264                 /* Push the object we're going to leave behind */
1265                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1266                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1267                         ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1268                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1269                 } else {
1270                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1271                 }
1272                 poi_stack[poi_stack_nr++] = obj_offset;
1273                 /* If parsing the base offset fails, just unwind */
1274                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1275                 if (!base_offset)
1276                         goto unwind;
1277                 curpos = obj_offset = base_offset;
1278                 type = unpack_object_header(p, w_curs, &curpos, &size);
1279                 if (type <= OBJ_NONE) {
1280                         /* If getting the base itself fails, we first
1281                          * retry the base, otherwise unwind */
1282                         type = retry_bad_packed_offset(r, p, base_offset);
1283                         if (type > OBJ_NONE)
1284                                 goto out;
1285                         goto unwind;
1286                 }
1287         }
1288
1289         switch (type) {
1290         case OBJ_BAD:
1291         case OBJ_COMMIT:
1292         case OBJ_TREE:
1293         case OBJ_BLOB:
1294         case OBJ_TAG:
1295                 break;
1296         default:
1297                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1298                       type, (uintmax_t)obj_offset, p->pack_name);
1299                 type = OBJ_BAD;
1300         }
1301
1302 out:
1303         if (poi_stack != small_poi_stack)
1304                 free(poi_stack);
1305         return type;
1306
1307 unwind:
1308         while (poi_stack_nr) {
1309                 obj_offset = poi_stack[--poi_stack_nr];
1310                 type = retry_bad_packed_offset(r, p, obj_offset);
1311                 if (type > OBJ_NONE)
1312                         goto out;
1313         }
1314         type = OBJ_BAD;
1315         goto out;
1316 }
1317
1318 static struct hashmap delta_base_cache;
1319 static size_t delta_base_cached;
1320
1321 static LIST_HEAD(delta_base_cache_lru);
1322
1323 struct delta_base_cache_key {
1324         struct packed_git *p;
1325         off_t base_offset;
1326 };
1327
1328 struct delta_base_cache_entry {
1329         struct hashmap hash;
1330         struct delta_base_cache_key key;
1331         struct list_head lru;
1332         void *data;
1333         unsigned long size;
1334         enum object_type type;
1335 };
1336
1337 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1338 {
1339         unsigned int hash;
1340
1341         hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1342         hash += (hash >> 8) + (hash >> 16);
1343         return hash;
1344 }
1345
1346 static struct delta_base_cache_entry *
1347 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1348 {
1349         struct hashmap_entry entry;
1350         struct delta_base_cache_key key;
1351
1352         if (!delta_base_cache.cmpfn)
1353                 return NULL;
1354
1355         hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1356         key.p = p;
1357         key.base_offset = base_offset;
1358         return hashmap_get(&delta_base_cache, &entry, &key);
1359 }
1360
1361 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1362                                    const struct delta_base_cache_key *b)
1363 {
1364         return a->p == b->p && a->base_offset == b->base_offset;
1365 }
1366
1367 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1368                                      const void *va, const void *vb,
1369                                      const void *vkey)
1370 {
1371         const struct delta_base_cache_entry *a = va, *b = vb;
1372         const struct delta_base_cache_key *key = vkey;
1373         if (key)
1374                 return !delta_base_cache_key_eq(&a->key, key);
1375         else
1376                 return !delta_base_cache_key_eq(&a->key, &b->key);
1377 }
1378
1379 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1380 {
1381         return !!get_delta_base_cache_entry(p, base_offset);
1382 }
1383
1384 /*
1385  * Remove the entry from the cache, but do _not_ free the associated
1386  * entry data. The caller takes ownership of the "data" buffer, and
1387  * should copy out any fields it wants before detaching.
1388  */
1389 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1390 {
1391         hashmap_remove(&delta_base_cache, ent, &ent->key);
1392         list_del(&ent->lru);
1393         delta_base_cached -= ent->size;
1394         free(ent);
1395 }
1396
1397 static void *cache_or_unpack_entry(struct repository *r, struct packed_git *p,
1398                                    off_t base_offset, unsigned long *base_size,
1399                                    enum object_type *type)
1400 {
1401         struct delta_base_cache_entry *ent;
1402
1403         ent = get_delta_base_cache_entry(p, base_offset);
1404         if (!ent)
1405                 return unpack_entry(r, p, base_offset, type, base_size);
1406
1407         if (type)
1408                 *type = ent->type;
1409         if (base_size)
1410                 *base_size = ent->size;
1411         return xmemdupz(ent->data, ent->size);
1412 }
1413
1414 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1415 {
1416         free(ent->data);
1417         detach_delta_base_cache_entry(ent);
1418 }
1419
1420 void clear_delta_base_cache(void)
1421 {
1422         struct list_head *lru, *tmp;
1423         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1424                 struct delta_base_cache_entry *entry =
1425                         list_entry(lru, struct delta_base_cache_entry, lru);
1426                 release_delta_base_cache(entry);
1427         }
1428 }
1429
1430 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1431         void *base, unsigned long base_size, enum object_type type)
1432 {
1433         struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1434         struct list_head *lru, *tmp;
1435
1436         delta_base_cached += base_size;
1437
1438         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1439                 struct delta_base_cache_entry *f =
1440                         list_entry(lru, struct delta_base_cache_entry, lru);
1441                 if (delta_base_cached <= delta_base_cache_limit)
1442                         break;
1443                 release_delta_base_cache(f);
1444         }
1445
1446         ent->key.p = p;
1447         ent->key.base_offset = base_offset;
1448         ent->type = type;
1449         ent->data = base;
1450         ent->size = base_size;
1451         list_add_tail(&ent->lru, &delta_base_cache_lru);
1452
1453         if (!delta_base_cache.cmpfn)
1454                 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1455         hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1456         hashmap_add(&delta_base_cache, ent);
1457 }
1458
1459 int packed_object_info(struct repository *r, struct packed_git *p,
1460                        off_t obj_offset, struct object_info *oi)
1461 {
1462         struct pack_window *w_curs = NULL;
1463         unsigned long size;
1464         off_t curpos = obj_offset;
1465         enum object_type type;
1466
1467         /*
1468          * We always get the representation type, but only convert it to
1469          * a "real" type later if the caller is interested.
1470          */
1471         if (oi->contentp) {
1472                 *oi->contentp = cache_or_unpack_entry(r, p, obj_offset, oi->sizep,
1473                                                       &type);
1474                 if (!*oi->contentp)
1475                         type = OBJ_BAD;
1476         } else {
1477                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1478         }
1479
1480         if (!oi->contentp && oi->sizep) {
1481                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1482                         off_t tmp_pos = curpos;
1483                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1484                                                            type, obj_offset);
1485                         if (!base_offset) {
1486                                 type = OBJ_BAD;
1487                                 goto out;
1488                         }
1489                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1490                         if (*oi->sizep == 0) {
1491                                 type = OBJ_BAD;
1492                                 goto out;
1493                         }
1494                 } else {
1495                         *oi->sizep = size;
1496                 }
1497         }
1498
1499         if (oi->disk_sizep) {
1500                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1501                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1502         }
1503
1504         if (oi->typep || oi->type_name) {
1505                 enum object_type ptot;
1506                 ptot = packed_to_object_type(r, p, obj_offset,
1507                                              type, &w_curs, curpos);
1508                 if (oi->typep)
1509                         *oi->typep = ptot;
1510                 if (oi->type_name) {
1511                         const char *tn = type_name(ptot);
1512                         if (tn)
1513                                 strbuf_addstr(oi->type_name, tn);
1514                 }
1515                 if (ptot < 0) {
1516                         type = OBJ_BAD;
1517                         goto out;
1518                 }
1519         }
1520
1521         if (oi->delta_base_sha1) {
1522                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1523                         const unsigned char *base;
1524
1525                         base = get_delta_base_sha1(p, &w_curs, curpos,
1526                                                    type, obj_offset);
1527                         if (!base) {
1528                                 type = OBJ_BAD;
1529                                 goto out;
1530                         }
1531
1532                         hashcpy(oi->delta_base_sha1, base);
1533                 } else
1534                         hashclr(oi->delta_base_sha1);
1535         }
1536
1537         oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1538                                                           OI_PACKED;
1539
1540 out:
1541         unuse_pack(&w_curs);
1542         return type;
1543 }
1544
1545 static void *unpack_compressed_entry(struct packed_git *p,
1546                                     struct pack_window **w_curs,
1547                                     off_t curpos,
1548                                     unsigned long size)
1549 {
1550         int st;
1551         git_zstream stream;
1552         unsigned char *buffer, *in;
1553
1554         buffer = xmallocz_gently(size);
1555         if (!buffer)
1556                 return NULL;
1557         memset(&stream, 0, sizeof(stream));
1558         stream.next_out = buffer;
1559         stream.avail_out = size + 1;
1560
1561         git_inflate_init(&stream);
1562         do {
1563                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1564                 stream.next_in = in;
1565                 st = git_inflate(&stream, Z_FINISH);
1566                 if (!stream.avail_out)
1567                         break; /* the payload is larger than it should be */
1568                 curpos += stream.next_in - in;
1569         } while (st == Z_OK || st == Z_BUF_ERROR);
1570         git_inflate_end(&stream);
1571         if ((st != Z_STREAM_END) || stream.total_out != size) {
1572                 free(buffer);
1573                 return NULL;
1574         }
1575
1576         /* versions of zlib can clobber unconsumed portion of outbuf */
1577         buffer[size] = '\0';
1578
1579         return buffer;
1580 }
1581
1582 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1583 {
1584         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1585         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1586                          p->pack_name, (uintmax_t)obj_offset);
1587 }
1588
1589 int do_check_packed_object_crc;
1590
1591 #define UNPACK_ENTRY_STACK_PREALLOC 64
1592 struct unpack_entry_stack_ent {
1593         off_t obj_offset;
1594         off_t curpos;
1595         unsigned long size;
1596 };
1597
1598 static void *read_object(struct repository *r,
1599                          const struct object_id *oid,
1600                          enum object_type *type,
1601                          unsigned long *size)
1602 {
1603         struct object_info oi = OBJECT_INFO_INIT;
1604         void *content;
1605         oi.typep = type;
1606         oi.sizep = size;
1607         oi.contentp = &content;
1608
1609         if (oid_object_info_extended(r, oid, &oi, 0) < 0)
1610                 return NULL;
1611         return content;
1612 }
1613
1614 void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset,
1615                    enum object_type *final_type, unsigned long *final_size)
1616 {
1617         struct pack_window *w_curs = NULL;
1618         off_t curpos = obj_offset;
1619         void *data = NULL;
1620         unsigned long size;
1621         enum object_type type;
1622         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1623         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1624         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1625         int base_from_cache = 0;
1626
1627         write_pack_access_log(p, obj_offset);
1628
1629         /* PHASE 1: drill down to the innermost base object */
1630         for (;;) {
1631                 off_t base_offset;
1632                 int i;
1633                 struct delta_base_cache_entry *ent;
1634
1635                 ent = get_delta_base_cache_entry(p, curpos);
1636                 if (ent) {
1637                         type = ent->type;
1638                         data = ent->data;
1639                         size = ent->size;
1640                         detach_delta_base_cache_entry(ent);
1641                         base_from_cache = 1;
1642                         break;
1643                 }
1644
1645                 if (do_check_packed_object_crc && p->index_version > 1) {
1646                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1647                         off_t len = revidx[1].offset - obj_offset;
1648                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1649                                 struct object_id oid;
1650                                 nth_packed_object_oid(&oid, p, revidx->nr);
1651                                 error("bad packed object CRC for %s",
1652                                       oid_to_hex(&oid));
1653                                 mark_bad_packed_object(p, oid.hash);
1654                                 data = NULL;
1655                                 goto out;
1656                         }
1657                 }
1658
1659                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1660                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1661                         break;
1662
1663                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1664                 if (!base_offset) {
1665                         error("failed to validate delta base reference "
1666                               "at offset %"PRIuMAX" from %s",
1667                               (uintmax_t)curpos, p->pack_name);
1668                         /* bail to phase 2, in hopes of recovery */
1669                         data = NULL;
1670                         break;
1671                 }
1672
1673                 /* push object, proceed to base */
1674                 if (delta_stack_nr >= delta_stack_alloc
1675                     && delta_stack == small_delta_stack) {
1676                         delta_stack_alloc = alloc_nr(delta_stack_nr);
1677                         ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1678                         memcpy(delta_stack, small_delta_stack,
1679                                sizeof(*delta_stack)*delta_stack_nr);
1680                 } else {
1681                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1682                 }
1683                 i = delta_stack_nr++;
1684                 delta_stack[i].obj_offset = obj_offset;
1685                 delta_stack[i].curpos = curpos;
1686                 delta_stack[i].size = size;
1687
1688                 curpos = obj_offset = base_offset;
1689         }
1690
1691         /* PHASE 2: handle the base */
1692         switch (type) {
1693         case OBJ_OFS_DELTA:
1694         case OBJ_REF_DELTA:
1695                 if (data)
1696                         BUG("unpack_entry: left loop at a valid delta");
1697                 break;
1698         case OBJ_COMMIT:
1699         case OBJ_TREE:
1700         case OBJ_BLOB:
1701         case OBJ_TAG:
1702                 if (!base_from_cache)
1703                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
1704                 break;
1705         default:
1706                 data = NULL;
1707                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1708                       type, (uintmax_t)obj_offset, p->pack_name);
1709         }
1710
1711         /* PHASE 3: apply deltas in order */
1712
1713         /* invariants:
1714          *   'data' holds the base data, or NULL if there was corruption
1715          */
1716         while (delta_stack_nr) {
1717                 void *delta_data;
1718                 void *base = data;
1719                 void *external_base = NULL;
1720                 unsigned long delta_size, base_size = size;
1721                 int i;
1722
1723                 data = NULL;
1724
1725                 if (base)
1726                         add_delta_base_cache(p, obj_offset, base, base_size, type);
1727
1728                 if (!base) {
1729                         /*
1730                          * We're probably in deep shit, but let's try to fetch
1731                          * the required base anyway from another pack or loose.
1732                          * This is costly but should happen only in the presence
1733                          * of a corrupted pack, and is better than failing outright.
1734                          */
1735                         struct revindex_entry *revidx;
1736                         struct object_id base_oid;
1737                         revidx = find_pack_revindex(p, obj_offset);
1738                         if (revidx) {
1739                                 nth_packed_object_oid(&base_oid, p, revidx->nr);
1740                                 error("failed to read delta base object %s"
1741                                       " at offset %"PRIuMAX" from %s",
1742                                       oid_to_hex(&base_oid), (uintmax_t)obj_offset,
1743                                       p->pack_name);
1744                                 mark_bad_packed_object(p, base_oid.hash);
1745                                 base = read_object(r, &base_oid, &type, &base_size);
1746                                 external_base = base;
1747                         }
1748                 }
1749
1750                 i = --delta_stack_nr;
1751                 obj_offset = delta_stack[i].obj_offset;
1752                 curpos = delta_stack[i].curpos;
1753                 delta_size = delta_stack[i].size;
1754
1755                 if (!base)
1756                         continue;
1757
1758                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1759
1760                 if (!delta_data) {
1761                         error("failed to unpack compressed delta "
1762                               "at offset %"PRIuMAX" from %s",
1763                               (uintmax_t)curpos, p->pack_name);
1764                         data = NULL;
1765                         free(external_base);
1766                         continue;
1767                 }
1768
1769                 data = patch_delta(base, base_size,
1770                                    delta_data, delta_size,
1771                                    &size);
1772
1773                 /*
1774                  * We could not apply the delta; warn the user, but keep going.
1775                  * Our failure will be noticed either in the next iteration of
1776                  * the loop, or if this is the final delta, in the caller when
1777                  * we return NULL. Those code paths will take care of making
1778                  * a more explicit warning and retrying with another copy of
1779                  * the object.
1780                  */
1781                 if (!data)
1782                         error("failed to apply delta");
1783
1784                 free(delta_data);
1785                 free(external_base);
1786         }
1787
1788         if (final_type)
1789                 *final_type = type;
1790         if (final_size)
1791                 *final_size = size;
1792
1793 out:
1794         unuse_pack(&w_curs);
1795
1796         if (delta_stack != small_delta_stack)
1797                 free(delta_stack);
1798
1799         return data;
1800 }
1801
1802 int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result)
1803 {
1804         const unsigned char *index_fanout = p->index_data;
1805         const unsigned char *index_lookup;
1806         const unsigned int hashsz = the_hash_algo->rawsz;
1807         int index_lookup_width;
1808
1809         if (!index_fanout)
1810                 BUG("bsearch_pack called without a valid pack-index");
1811
1812         index_lookup = index_fanout + 4 * 256;
1813         if (p->index_version == 1) {
1814                 index_lookup_width = hashsz + 4;
1815                 index_lookup += 4;
1816         } else {
1817                 index_lookup_width = hashsz;
1818                 index_fanout += 8;
1819                 index_lookup += 8;
1820         }
1821
1822         return bsearch_hash(oid->hash, (const uint32_t*)index_fanout,
1823                             index_lookup, index_lookup_width, result);
1824 }
1825
1826 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1827                                             uint32_t n)
1828 {
1829         const unsigned char *index = p->index_data;
1830         const unsigned int hashsz = the_hash_algo->rawsz;
1831         if (!index) {
1832                 if (open_pack_index(p))
1833                         return NULL;
1834                 index = p->index_data;
1835         }
1836         if (n >= p->num_objects)
1837                 return NULL;
1838         index += 4 * 256;
1839         if (p->index_version == 1) {
1840                 return index + (hashsz + 4) * n + 4;
1841         } else {
1842                 index += 8;
1843                 return index + hashsz * n;
1844         }
1845 }
1846
1847 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1848                                               struct packed_git *p,
1849                                               uint32_t n)
1850 {
1851         const unsigned char *hash = nth_packed_object_sha1(p, n);
1852         if (!hash)
1853                 return NULL;
1854         hashcpy(oid->hash, hash);
1855         return oid;
1856 }
1857
1858 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1859 {
1860         const unsigned char *ptr = vptr;
1861         const unsigned char *start = p->index_data;
1862         const unsigned char *end = start + p->index_size;
1863         if (ptr < start)
1864                 die(_("offset before start of pack index for %s (corrupt index?)"),
1865                     p->pack_name);
1866         /* No need to check for underflow; .idx files must be at least 8 bytes */
1867         if (ptr >= end - 8)
1868                 die(_("offset beyond end of pack index for %s (truncated index?)"),
1869                     p->pack_name);
1870 }
1871
1872 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1873 {
1874         const unsigned char *index = p->index_data;
1875         const unsigned int hashsz = the_hash_algo->rawsz;
1876         index += 4 * 256;
1877         if (p->index_version == 1) {
1878                 return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
1879         } else {
1880                 uint32_t off;
1881                 index += 8 + p->num_objects * (hashsz + 4);
1882                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1883                 if (!(off & 0x80000000))
1884                         return off;
1885                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1886                 check_pack_index_ptr(p, index);
1887                 return get_be64(index);
1888         }
1889 }
1890
1891 off_t find_pack_entry_one(const unsigned char *sha1,
1892                                   struct packed_git *p)
1893 {
1894         const unsigned char *index = p->index_data;
1895         struct object_id oid;
1896         uint32_t result;
1897
1898         if (!index) {
1899                 if (open_pack_index(p))
1900                         return 0;
1901         }
1902
1903         hashcpy(oid.hash, sha1);
1904         if (bsearch_pack(&oid, p, &result))
1905                 return nth_packed_object_offset(p, result);
1906         return 0;
1907 }
1908
1909 int is_pack_valid(struct packed_git *p)
1910 {
1911         /* An already open pack is known to be valid. */
1912         if (p->pack_fd != -1)
1913                 return 1;
1914
1915         /* If the pack has one window completely covering the
1916          * file size, the pack is known to be valid even if
1917          * the descriptor is not currently open.
1918          */
1919         if (p->windows) {
1920                 struct pack_window *w = p->windows;
1921
1922                 if (!w->offset && w->len == p->pack_size)
1923                         return 1;
1924         }
1925
1926         /* Force the pack to open to prove its valid. */
1927         return !open_packed_git(p);
1928 }
1929
1930 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1931                                   struct packed_git *packs)
1932 {
1933         struct packed_git *p;
1934
1935         for (p = packs; p; p = p->next) {
1936                 if (find_pack_entry_one(sha1, p))
1937                         return p;
1938         }
1939         return NULL;
1940
1941 }
1942
1943 static int fill_pack_entry(const struct object_id *oid,
1944                            struct pack_entry *e,
1945                            struct packed_git *p)
1946 {
1947         off_t offset;
1948
1949         if (p->num_bad_objects) {
1950                 unsigned i;
1951                 for (i = 0; i < p->num_bad_objects; i++)
1952                         if (hasheq(oid->hash,
1953                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
1954                                 return 0;
1955         }
1956
1957         offset = find_pack_entry_one(oid->hash, p);
1958         if (!offset)
1959                 return 0;
1960
1961         /*
1962          * We are about to tell the caller where they can locate the
1963          * requested object.  We better make sure the packfile is
1964          * still here and can be accessed before supplying that
1965          * answer, as it may have been deleted since the index was
1966          * loaded!
1967          */
1968         if (!is_pack_valid(p))
1969                 return 0;
1970         e->offset = offset;
1971         e->p = p;
1972         return 1;
1973 }
1974
1975 int find_pack_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e)
1976 {
1977         struct list_head *pos;
1978         struct multi_pack_index *m;
1979
1980         prepare_packed_git(r);
1981         if (!r->objects->packed_git && !r->objects->multi_pack_index)
1982                 return 0;
1983
1984         for (m = r->objects->multi_pack_index; m; m = m->next) {
1985                 if (fill_midx_entry(oid, e, m))
1986                         return 1;
1987         }
1988
1989         list_for_each(pos, &r->objects->packed_git_mru) {
1990                 struct packed_git *p = list_entry(pos, struct packed_git, mru);
1991                 if (fill_pack_entry(oid, e, p)) {
1992                         list_move(&p->mru, &r->objects->packed_git_mru);
1993                         return 1;
1994                 }
1995         }
1996         return 0;
1997 }
1998
1999 int has_object_pack(const struct object_id *oid)
2000 {
2001         struct pack_entry e;
2002         return find_pack_entry(the_repository, oid, &e);
2003 }
2004
2005 int has_pack_index(const unsigned char *sha1)
2006 {
2007         struct stat st;
2008         if (stat(sha1_pack_index_name(sha1), &st))
2009                 return 0;
2010         return 1;
2011 }
2012
2013 int for_each_object_in_pack(struct packed_git *p,
2014                             each_packed_object_fn cb, void *data,
2015                             enum for_each_object_flags flags)
2016 {
2017         uint32_t i;
2018         int r = 0;
2019
2020         if (flags & FOR_EACH_OBJECT_PACK_ORDER)
2021                 load_pack_revindex(p);
2022
2023         for (i = 0; i < p->num_objects; i++) {
2024                 uint32_t pos;
2025                 struct object_id oid;
2026
2027                 if (flags & FOR_EACH_OBJECT_PACK_ORDER)
2028                         pos = p->revindex[i].nr;
2029                 else
2030                         pos = i;
2031
2032                 if (!nth_packed_object_oid(&oid, p, pos))
2033                         return error("unable to get sha1 of object %u in %s",
2034                                      pos, p->pack_name);
2035
2036                 r = cb(&oid, p, pos, data);
2037                 if (r)
2038                         break;
2039         }
2040         return r;
2041 }
2042
2043 int for_each_packed_object(each_packed_object_fn cb, void *data,
2044                            enum for_each_object_flags flags)
2045 {
2046         struct packed_git *p;
2047         int r = 0;
2048         int pack_errors = 0;
2049
2050         prepare_packed_git(the_repository);
2051         for (p = get_all_packs(the_repository); p; p = p->next) {
2052                 if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
2053                         continue;
2054                 if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
2055                     !p->pack_promisor)
2056                         continue;
2057                 if (open_pack_index(p)) {
2058                         pack_errors = 1;
2059                         continue;
2060                 }
2061                 r = for_each_object_in_pack(p, cb, data, flags);
2062                 if (r)
2063                         break;
2064         }
2065         return r ? r : pack_errors;
2066 }
2067
2068 static int add_promisor_object(const struct object_id *oid,
2069                                struct packed_git *pack,
2070                                uint32_t pos,
2071                                void *set_)
2072 {
2073         struct oidset *set = set_;
2074         struct object *obj = parse_object(the_repository, oid);
2075         if (!obj)
2076                 return 1;
2077
2078         oidset_insert(set, oid);
2079
2080         /*
2081          * If this is a tree, commit, or tag, the objects it refers
2082          * to are also promisor objects. (Blobs refer to no objects->)
2083          */
2084         if (obj->type == OBJ_TREE) {
2085                 struct tree *tree = (struct tree *)obj;
2086                 struct tree_desc desc;
2087                 struct name_entry entry;
2088                 if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
2089                         /*
2090                          * Error messages are given when packs are
2091                          * verified, so do not print any here.
2092                          */
2093                         return 0;
2094                 while (tree_entry_gently(&desc, &entry))
2095                         oidset_insert(set, entry.oid);
2096         } else if (obj->type == OBJ_COMMIT) {
2097                 struct commit *commit = (struct commit *) obj;
2098                 struct commit_list *parents = commit->parents;
2099
2100                 oidset_insert(set, get_commit_tree_oid(commit));
2101                 for (; parents; parents = parents->next)
2102                         oidset_insert(set, &parents->item->object.oid);
2103         } else if (obj->type == OBJ_TAG) {
2104                 struct tag *tag = (struct tag *) obj;
2105                 oidset_insert(set, &tag->tagged->oid);
2106         }
2107         return 0;
2108 }
2109
2110 int is_promisor_object(const struct object_id *oid)
2111 {
2112         static struct oidset promisor_objects;
2113         static int promisor_objects_prepared;
2114
2115         if (!promisor_objects_prepared) {
2116                 if (repository_format_partial_clone) {
2117                         for_each_packed_object(add_promisor_object,
2118                                                &promisor_objects,
2119                                                FOR_EACH_OBJECT_PROMISOR_ONLY);
2120                 }
2121                 promisor_objects_prepared = 1;
2122         }
2123         return oidset_contains(&promisor_objects, oid);
2124 }