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