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         struct pack_idx_header *hdr;
  84         size_t idx_size;
  85         uint32_t version, nr, i, *index;
  86         int fd = git_open(path);
  87         struct stat st;
  88         const unsigned int hashsz = the_hash_algo->rawsz;
  89
  90         if (fd < 0)
  91                 return -1;
  92         if (fstat(fd, &st)) {
  93                 close(fd);
  94                 return -1;
  95         }
  96         idx_size = xsize_t(st.st_size);
  97         if (idx_size < 4 * 256 + hashsz + hashsz) {
  98                 close(fd);
  99                 return error("index file %s is too small", path);
 100         }
 101         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 102         close(fd);
 103
 104         hdr = idx_map;
 105         if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
 106                 version = ntohl(hdr->idx_version);
 107                 if (version < 2 || version > 2) {
 108                         munmap(idx_map, idx_size);
 109                         return error("index file %s is version %"PRIu32
 110                                      " and is not supported by this binary"
 111                                      " (try upgrading GIT to a newer version)",
 112                                      path, version);
 113                 }
 114         } else
 115                 version = 1;
 116
 117         nr = 0;
 118         index = idx_map;
 119         if (version > 1)
 120                 index += 2;  /* skip index header */
 121         for (i = 0; i < 256; i++) {
 122                 uint32_t n = ntohl(index[i]);
 123                 if (n < nr) {
 124                         munmap(idx_map, idx_size);
 125                         return error("non-monotonic index %s", path);
 126                 }
 127                 nr = n;
 128         }
 129
 130         if (version == 1) {
 131                 /*
 132                  * Total size:
 133                  *  - 256 index entries 4 bytes each
 134                  *  - 24-byte entries * nr (object ID + 4-byte offset)
 135                  *  - hash of the packfile
 136                  *  - file checksum
 137                  */
 138                 if (idx_size != 4*256 + nr * (hashsz + 4) + hashsz + hashsz) {
 139                         munmap(idx_map, idx_size);
 140                         return error("wrong index v1 file size in %s", path);
 141                 }
 142         } else if (version == 2) {
 143                 /*
 144                  * Minimum size:
 145                  *  - 8 bytes of header
 146                  *  - 256 index entries 4 bytes each
 147                  *  - object ID entry * nr
 148                  *  - 4-byte crc entry * nr
 149                  *  - 4-byte offset entry * nr
 150                  *  - hash of the packfile
 151                  *  - file checksum
 152                  * And after the 4-byte offset table might be a
 153                  * variable sized table containing 8-byte entries
 154                  * for offsets larger than 2^31.
 155                  */
 156                 unsigned long min_size = 8 + 4*256 + nr*(hashsz + 4 + 4) + hashsz + hashsz;
 157                 unsigned long max_size = min_size;
 158                 if (nr)
 159                         max_size += (nr - 1)*8;
 160                 if (idx_size < min_size || idx_size > max_size) {
 161                         munmap(idx_map, idx_size);
 162                         return error("wrong index v2 file size in %s", path);
 163                 }
 164                 if (idx_size != min_size &&
 165                     /*
 166                      * make sure we can deal with large pack offsets.
 167                      * 31-bit signed offset won't be enough, neither
 168                      * 32-bit unsigned one will be.
 169                      */
 170                     (sizeof(off_t) <= 4)) {
 171                         munmap(idx_map, idx_size);
 172                         return error("pack too large for current definition of off_t in %s", path);
 173                 }
 174         }
 175
 176         p->index_version = version;
 177         p->index_data = idx_map;
 178         p->index_size = idx_size;
 179         p->num_objects = nr;
 180         return 0;
 181 }
 182
 183 int open_pack_index(struct packed_git *p)
 184 {
 185         char *idx_name;
 186         size_t len;
 187         int ret;
 188
 189         if (p->index_data)
 190                 return 0;
 191
 192         if (!strip_suffix(p->pack_name, ".pack", &len))
 193                 BUG("pack_name does not end in .pack");
 194         idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
 195         ret = check_packed_git_idx(idx_name, p);
 196         free(idx_name);
 197         return ret;
 198 }
 199
 200 uint32_t get_pack_fanout(struct packed_git *p, uint32_t value)
 201 {
 202         const uint32_t *level1_ofs = p->index_data;
 203
 204         if (!level1_ofs) {
 205                 if (open_pack_index(p))
 206                         return 0;
 207                 level1_ofs = p->index_data;
 208         }
 209
 210         if (p->index_version > 1) {
 211                 level1_ofs += 2;
 212         }
 213
 214         return ntohl(level1_ofs[value]);
 215 }
 216
 217 static struct packed_git *alloc_packed_git(int extra)
 218 {
 219         struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
 220         memset(p, 0, sizeof(*p));
 221         p->pack_fd = -1;
 222         return p;
 223 }
 224
 225 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 226 {
 227         const char *path = sha1_pack_name(sha1);
 228         size_t alloc = st_add(strlen(path), 1);
 229         struct packed_git *p = alloc_packed_git(alloc);
 230
 231         memcpy(p->pack_name, path, alloc); /* includes NUL */
 232         hashcpy(p->sha1, sha1);
 233         if (check_packed_git_idx(idx_path, p)) {
 234                 free(p);
 235                 return NULL;
 236         }
 237
 238         return p;
 239 }
 240
 241 static void scan_windows(struct packed_git *p,
 242         struct packed_git **lru_p,
 243         struct pack_window **lru_w,
 244         struct pack_window **lru_l)
 245 {
 246         struct pack_window *w, *w_l;
 247
 248         for (w_l = NULL, w = p->windows; w; w = w->next) {
 249                 if (!w->inuse_cnt) {
 250                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 251                                 *lru_p = p;
 252                                 *lru_w = w;
 253                                 *lru_l = w_l;
 254                         }
 255                 }
 256                 w_l = w;
 257         }
 258 }
 259
 260 static int unuse_one_window(struct packed_git *current)
 261 {
 262         struct packed_git *p, *lru_p = NULL;
 263         struct pack_window *lru_w = NULL, *lru_l = NULL;
 264
 265         if (current)
 266                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 267         for (p = the_repository->objects->packed_git; p; p = p->next)
 268                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 269         if (lru_p) {
 270                 munmap(lru_w->base, lru_w->len);
 271                 pack_mapped -= lru_w->len;
 272                 if (lru_l)
 273                         lru_l->next = lru_w->next;
 274                 else
 275                         lru_p->windows = lru_w->next;
 276                 free(lru_w);
 277                 pack_open_windows--;
 278                 return 1;
 279         }
 280         return 0;
 281 }
 282
 283 void release_pack_memory(size_t need)
 284 {
 285         size_t cur = pack_mapped;
 286         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 287                 ; /* nothing */
 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 static 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_all_packs(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
 344 /*
 345  * The LRU pack is the one with the oldest MRU window, preferring packs
 346  * with no used windows, or the oldest mtime if it has no windows allocated.
 347  */
 348 static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
 349 {
 350         struct pack_window *w, *this_mru_w;
 351         int has_windows_inuse = 0;
 352
 353         /*
 354          * Reject this pack if it has windows and the previously selected
 355          * one does not.  If this pack does not have windows, reject
 356          * it if the pack file is newer than the previously selected one.
 357          */
 358         if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
 359                 return;
 360
 361         for (w = this_mru_w = p->windows; w; w = w->next) {
 362                 /*
 363                  * Reject this pack if any of its windows are in use,
 364                  * but the previously selected pack did not have any
 365                  * inuse windows.  Otherwise, record that this pack
 366                  * has windows in use.
 367                  */
 368                 if (w->inuse_cnt) {
 369                         if (*accept_windows_inuse)
 370                                 has_windows_inuse = 1;
 371                         else
 372                                 return;
 373                 }
 374
 375                 if (w->last_used > this_mru_w->last_used)
 376                         this_mru_w = w;
 377
 378                 /*
 379                  * Reject this pack if it has windows that have been
 380                  * used more recently than the previously selected pack.
 381                  * If the previously selected pack had windows inuse and
 382                  * we have not encountered a window in this pack that is
 383                  * inuse, skip this check since we prefer a pack with no
 384                  * inuse windows to one that has inuse windows.
 385                  */
 386                 if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
 387                     this_mru_w->last_used > (*mru_w)->last_used)
 388                         return;
 389         }
 390
 391         /*
 392          * Select this pack.
 393          */
 394         *mru_w = this_mru_w;
 395         *lru_p = p;
 396         *accept_windows_inuse = has_windows_inuse;
 397 }
 398
 399 static int close_one_pack(void)
 400 {
 401         struct packed_git *p, *lru_p = NULL;
 402         struct pack_window *mru_w = NULL;
 403         int accept_windows_inuse = 1;
 404
 405         for (p = the_repository->objects->packed_git; p; p = p->next) {
 406                 if (p->pack_fd == -1)
 407                         continue;
 408                 find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
 409         }
 410
 411         if (lru_p)
 412                 return close_pack_fd(lru_p);
 413
 414         return 0;
 415 }
 416
 417 static unsigned int get_max_fd_limit(void)
 418 {
 419 #ifdef RLIMIT_NOFILE
 420         {
 421                 struct rlimit lim;
 422
 423                 if (!getrlimit(RLIMIT_NOFILE, &lim))
 424                         return lim.rlim_cur;
 425         }
 426 #endif
 427
 428 #ifdef _SC_OPEN_MAX
 429         {
 430                 long open_max = sysconf(_SC_OPEN_MAX);
 431                 if (0 < open_max)
 432                         return open_max;
 433                 /*
 434                  * Otherwise, we got -1 for one of the two
 435                  * reasons:
 436                  *
 437                  * (1) sysconf() did not understand _SC_OPEN_MAX
 438                  *     and signaled an error with -1; or
 439                  * (2) sysconf() said there is no limit.
 440                  *
 441                  * We _could_ clear errno before calling sysconf() to
 442                  * tell these two cases apart and return a huge number
 443                  * in the latter case to let the caller cap it to a
 444                  * value that is not so selfish, but letting the
 445                  * fallback OPEN_MAX codepath take care of these cases
 446                  * is a lot simpler.
 447                  */
 448         }
 449 #endif
 450
 451 #ifdef OPEN_MAX
 452         return OPEN_MAX;
 453 #else
 454         return 1; /* see the caller ;-) */
 455 #endif
 456 }
 457
 458 /*
 459  * Do not call this directly as this leaks p->pack_fd on error return;
 460  * call open_packed_git() instead.
 461  */
 462 static int open_packed_git_1(struct packed_git *p)
 463 {
 464         struct stat st;
 465         struct pack_header hdr;
 466         unsigned char hash[GIT_MAX_RAWSZ];
 467         unsigned char *idx_hash;
 468         long fd_flag;
 469         ssize_t read_result;
 470         const unsigned hashsz = the_hash_algo->rawsz;
 471
 472         if (!p->index_data) {
 473                 struct multi_pack_index *m;
 474                 const char *pack_name = strrchr(p->pack_name, '/');
 475
 476                 for (m = the_repository->objects->multi_pack_index;
 477                      m; m = m->next) {
 478                         if (midx_contains_pack(m, pack_name))
 479                                 break;
 480                 }
 481
 482                 if (!m && open_pack_index(p))
 483                         return error("packfile %s index unavailable", p->pack_name);
 484         }
 485
 486         if (!pack_max_fds) {
 487                 unsigned int max_fds = get_max_fd_limit();
 488
 489                 /* Save 3 for stdin/stdout/stderr, 22 for work */
 490                 if (25 < max_fds)
 491                         pack_max_fds = max_fds - 25;
 492                 else
 493                         pack_max_fds = 1;
 494         }
 495
 496         while (pack_max_fds <= pack_open_fds && close_one_pack())
 497                 ; /* nothing */
 498
 499         p->pack_fd = git_open(p->pack_name);
 500         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 501                 return -1;
 502         pack_open_fds++;
 503
 504         /* If we created the struct before we had the pack we lack size. */
 505         if (!p->pack_size) {
 506                 if (!S_ISREG(st.st_mode))
 507                         return error("packfile %s not a regular file", p->pack_name);
 508                 p->pack_size = st.st_size;
 509         } else if (p->pack_size != st.st_size)
 510                 return error("packfile %s size changed", p->pack_name);
 511
 512         /* We leave these file descriptors open with sliding mmap;
 513          * there is no point keeping them open across exec(), though.
 514          */
 515         fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 516         if (fd_flag < 0)
 517                 return error("cannot determine file descriptor flags");
 518         fd_flag |= FD_CLOEXEC;
 519         if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 520                 return error("cannot set FD_CLOEXEC");
 521
 522         /* Verify we recognize this pack file format. */
 523         read_result = read_in_full(p->pack_fd, &hdr, sizeof(hdr));
 524         if (read_result < 0)
 525                 return error_errno("error reading from %s", p->pack_name);
 526         if (read_result != sizeof(hdr))
 527                 return error("file %s is far too short to be a packfile", p->pack_name);
 528         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 529                 return error("file %s is not a GIT packfile", p->pack_name);
 530         if (!pack_version_ok(hdr.hdr_version))
 531                 return error("packfile %s is version %"PRIu32" and not"
 532                         " supported (try upgrading GIT to a newer version)",
 533                         p->pack_name, ntohl(hdr.hdr_version));
 534
 535         /* Skip index checking if in multi-pack-index */
 536         if (!p->index_data)
 537                 return 0;
 538
 539         /* Verify the pack matches its index. */
 540         if (p->num_objects != ntohl(hdr.hdr_entries))
 541                 return error("packfile %s claims to have %"PRIu32" objects"
 542                              " while index indicates %"PRIu32" objects",
 543                              p->pack_name, ntohl(hdr.hdr_entries),
 544                              p->num_objects);
 545         if (lseek(p->pack_fd, p->pack_size - hashsz, SEEK_SET) == -1)
 546                 return error("end of packfile %s is unavailable", p->pack_name);
 547         read_result = read_in_full(p->pack_fd, hash, hashsz);
 548         if (read_result < 0)
 549                 return error_errno("error reading from %s", p->pack_name);
 550         if (read_result != hashsz)
 551                 return error("packfile %s signature is unavailable", p->pack_name);
 552         idx_hash = ((unsigned char *)p->index_data) + p->index_size - hashsz * 2;
 553         if (hashcmp(hash, idx_hash))
 554                 return error("packfile %s does not match index", p->pack_name);
 555         return 0;
 556 }
 557
 558 static int open_packed_git(struct packed_git *p)
 559 {
 560         if (!open_packed_git_1(p))
 561                 return 0;
 562         close_pack_fd(p);
 563         return -1;
 564 }
 565
 566 static int in_window(struct pack_window *win, off_t offset)
 567 {
 568         /* We must promise at least one full hash after the
 569          * offset is available from this window, otherwise the offset
 570          * is not actually in this window and a different window (which
 571          * has that one hash excess) must be used.  This is to support
 572          * the object header and delta base parsing routines below.
 573          */
 574         off_t win_off = win->offset;
 575         return win_off <= offset
 576                 && (offset + the_hash_algo->rawsz) <= (win_off + win->len);
 577 }
 578
 579 unsigned char *use_pack(struct packed_git *p,
 580                 struct pack_window **w_cursor,
 581                 off_t offset,
 582                 unsigned long *left)
 583 {
 584         struct pack_window *win = *w_cursor;
 585
 586         /* Since packfiles end in a hash of their content and it's
 587          * pointless to ask for an offset into the middle of that
 588          * hash, and the in_window function above wouldn't match
 589          * don't allow an offset too close to the end of the file.
 590          */
 591         if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
 592                 die("packfile %s cannot be accessed", p->pack_name);
 593         if (offset > (p->pack_size - the_hash_algo->rawsz))
 594                 die("offset beyond end of packfile (truncated pack?)");
 595         if (offset < 0)
 596                 die(_("offset before end of packfile (broken .idx?)"));
 597
 598         if (!win || !in_window(win, offset)) {
 599                 if (win)
 600                         win->inuse_cnt--;
 601                 for (win = p->windows; win; win = win->next) {
 602                         if (in_window(win, offset))
 603                                 break;
 604                 }
 605                 if (!win) {
 606                         size_t window_align = packed_git_window_size / 2;
 607                         off_t len;
 608
 609                         if (p->pack_fd == -1 && open_packed_git(p))
 610                                 die("packfile %s cannot be accessed", p->pack_name);
 611
 612                         win = xcalloc(1, sizeof(*win));
 613                         win->offset = (offset / window_align) * window_align;
 614                         len = p->pack_size - win->offset;
 615                         if (len > packed_git_window_size)
 616                                 len = packed_git_window_size;
 617                         win->len = (size_t)len;
 618                         pack_mapped += win->len;
 619                         while (packed_git_limit < pack_mapped
 620                                 && unuse_one_window(p))
 621                                 ; /* nothing */
 622                         win->base = xmmap(NULL, win->len,
 623                                 PROT_READ, MAP_PRIVATE,
 624                                 p->pack_fd, win->offset);
 625                         if (win->base == MAP_FAILED)
 626                                 die_errno("packfile %s cannot be mapped",
 627                                           p->pack_name);
 628                         if (!win->offset && win->len == p->pack_size
 629                                 && !p->do_not_close)
 630                                 close_pack_fd(p);
 631                         pack_mmap_calls++;
 632                         pack_open_windows++;
 633                         if (pack_mapped > peak_pack_mapped)
 634                                 peak_pack_mapped = pack_mapped;
 635                         if (pack_open_windows > peak_pack_open_windows)
 636                                 peak_pack_open_windows = pack_open_windows;
 637                         win->next = p->windows;
 638                         p->windows = win;
 639                 }
 640         }
 641         if (win != *w_cursor) {
 642                 win->last_used = pack_used_ctr++;
 643                 win->inuse_cnt++;
 644                 *w_cursor = win;
 645         }
 646         offset -= win->offset;
 647         if (left)
 648                 *left = win->len - xsize_t(offset);
 649         return win->base + offset;
 650 }
 651
 652 void unuse_pack(struct pack_window **w_cursor)
 653 {
 654         struct pack_window *w = *w_cursor;
 655         if (w) {
 656                 w->inuse_cnt--;
 657                 *w_cursor = NULL;
 658         }
 659 }
 660
 661 static void try_to_free_pack_memory(size_t size)
 662 {
 663         release_pack_memory(size);
 664 }
 665
 666 struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
 667 {
 668         static int have_set_try_to_free_routine;
 669         struct stat st;
 670         size_t alloc;
 671         struct packed_git *p;
 672
 673         if (!have_set_try_to_free_routine) {
 674                 have_set_try_to_free_routine = 1;
 675                 set_try_to_free_routine(try_to_free_pack_memory);
 676         }
 677
 678         /*
 679          * Make sure a corresponding .pack file exists and that
 680          * the index looks sane.
 681          */
 682         if (!strip_suffix_mem(path, &path_len, ".idx"))
 683                 return NULL;
 684
 685         /*
 686          * ".promisor" is long enough to hold any suffix we're adding (and
 687          * the use xsnprintf double-checks that)
 688          */
 689         alloc = st_add3(path_len, strlen(".promisor"), 1);
 690         p = alloc_packed_git(alloc);
 691         memcpy(p->pack_name, path, path_len);
 692
 693         xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
 694         if (!access(p->pack_name, F_OK))
 695                 p->pack_keep = 1;
 696
 697         xsnprintf(p->pack_name + path_len, alloc - path_len, ".promisor");
 698         if (!access(p->pack_name, F_OK))
 699                 p->pack_promisor = 1;
 700
 701         xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
 702         if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
 703                 free(p);
 704                 return NULL;
 705         }
 706
 707         /* ok, it looks sane as far as we can check without
 708          * actually mapping the pack file.
 709          */
 710         p->pack_size = st.st_size;
 711         p->pack_local = local;
 712         p->mtime = st.st_mtime;
 713         if (path_len < the_hash_algo->hexsz ||
 714             get_sha1_hex(path + path_len - the_hash_algo->hexsz, p->sha1))
 715                 hashclr(p->sha1);
 716         return p;
 717 }
 718
 719 void install_packed_git(struct repository *r, struct packed_git *pack)
 720 {
 721         if (pack->pack_fd != -1)
 722                 pack_open_fds++;
 723
 724         pack->next = r->objects->packed_git;
 725         r->objects->packed_git = pack;
 726 }
 727
 728 void (*report_garbage)(unsigned seen_bits, const char *path);
 729
 730 static void report_helper(const struct string_list *list,
 731                           int seen_bits, int first, int last)
 732 {
 733         if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
 734                 return;
 735
 736         for (; first < last; first++)
 737                 report_garbage(seen_bits, list->items[first].string);
 738 }
 739
 740 static void report_pack_garbage(struct string_list *list)
 741 {
 742         int i, baselen = -1, first = 0, seen_bits = 0;
 743
 744         if (!report_garbage)
 745                 return;
 746
 747         string_list_sort(list);
 748
 749         for (i = 0; i < list->nr; i++) {
 750                 const char *path = list->items[i].string;
 751                 if (baselen != -1 &&
 752                     strncmp(path, list->items[first].string, baselen)) {
 753                         report_helper(list, seen_bits, first, i);
 754                         baselen = -1;
 755                         seen_bits = 0;
 756                 }
 757                 if (baselen == -1) {
 758                         const char *dot = strrchr(path, '.');
 759                         if (!dot) {
 760                                 report_garbage(PACKDIR_FILE_GARBAGE, path);
 761                                 continue;
 762                         }
 763                         baselen = dot - path + 1;
 764                         first = i;
 765                 }
 766                 if (!strcmp(path + baselen, "pack"))
 767                         seen_bits |= 1;
 768                 else if (!strcmp(path + baselen, "idx"))
 769                         seen_bits |= 2;
 770         }
 771         report_helper(list, seen_bits, first, list->nr);
 772 }
 773
 774 void for_each_file_in_pack_dir(const char *objdir,
 775                                each_file_in_pack_dir_fn fn,
 776                                void *data)
 777 {
 778         struct strbuf path = STRBUF_INIT;
 779         size_t dirnamelen;
 780         DIR *dir;
 781         struct dirent *de;
 782
 783         strbuf_addstr(&path, objdir);
 784         strbuf_addstr(&path, "/pack");
 785         dir = opendir(path.buf);
 786         if (!dir) {
 787                 if (errno != ENOENT)
 788                         error_errno("unable to open object pack directory: %s",
 789                                     path.buf);
 790                 strbuf_release(&path);
 791                 return;
 792         }
 793         strbuf_addch(&path, '/');
 794         dirnamelen = path.len;
 795         while ((de = readdir(dir)) != NULL) {
 796                 if (is_dot_or_dotdot(de->d_name))
 797                         continue;
 798
 799                 strbuf_setlen(&path, dirnamelen);
 800                 strbuf_addstr(&path, de->d_name);
 801
 802                 fn(path.buf, path.len, de->d_name, data);
 803         }
 804
 805         closedir(dir);
 806         strbuf_release(&path);
 807 }
 808
 809 struct prepare_pack_data {
 810         struct repository *r;
 811         struct string_list *garbage;
 812         int local;
 813         struct multi_pack_index *m;
 814 };
 815
 816 static void prepare_pack(const char *full_name, size_t full_name_len,
 817                          const char *file_name, void *_data)
 818 {
 819         struct prepare_pack_data *data = (struct prepare_pack_data *)_data;
 820         struct packed_git *p;
 821         size_t base_len = full_name_len;
 822
 823         if (strip_suffix_mem(full_name, &base_len, ".idx")) {
 824                 if (data->m && midx_contains_pack(data->m, file_name))
 825                         return;
 826                 /* Don't reopen a pack we already have. */
 827                 for (p = data->r->objects->packed_git; p; p = p->next) {
 828                         size_t len;
 829                         if (strip_suffix(p->pack_name, ".pack", &len) &&
 830                             len == base_len &&
 831                             !memcmp(p->pack_name, full_name, len))
 832                                 break;
 833                 }
 834
 835                 if (!p) {
 836                         p = add_packed_git(full_name, full_name_len, data->local);
 837                         if (p)
 838                                 install_packed_git(data->r, p);
 839                 }
 840         }
 841
 842         if (!report_garbage)
 843                 return;
 844
 845         if (ends_with(file_name, ".idx") ||
 846             ends_with(file_name, ".pack") ||
 847             ends_with(file_name, ".bitmap") ||
 848             ends_with(file_name, ".keep") ||
 849             ends_with(file_name, ".promisor"))
 850                 string_list_append(data->garbage, full_name);
 851         else
 852                 report_garbage(PACKDIR_FILE_GARBAGE, full_name);
 853 }
 854
 855 static void prepare_packed_git_one(struct repository *r, char *objdir, int local)
 856 {
 857         struct prepare_pack_data data;
 858         struct string_list garbage = STRING_LIST_INIT_DUP;
 859
 860         data.m = r->objects->multi_pack_index;
 861
 862         /* look for the multi-pack-index for this object directory */
 863         while (data.m && strcmp(data.m->object_dir, objdir))
 864                 data.m = data.m->next;
 865
 866         data.r = r;
 867         data.garbage = &garbage;
 868         data.local = local;
 869
 870         for_each_file_in_pack_dir(objdir, prepare_pack, &data);
 871
 872         report_pack_garbage(data.garbage);
 873         string_list_clear(data.garbage, 0);
 874 }
 875
 876 static void prepare_packed_git(struct repository *r);
 877 /*
 878  * Give a fast, rough count of the number of objects in the repository. This
 879  * ignores loose objects completely. If you have a lot of them, then either
 880  * you should repack because your performance will be awful, or they are
 881  * all unreachable objects about to be pruned, in which case they're not really
 882  * interesting as a measure of repo size in the first place.
 883  */
 884 unsigned long approximate_object_count(void)
 885 {
 886         if (!the_repository->objects->approximate_object_count_valid) {
 887                 unsigned long count;
 888                 struct multi_pack_index *m;
 889                 struct packed_git *p;
 890
 891                 prepare_packed_git(the_repository);
 892                 count = 0;
 893                 for (m = get_multi_pack_index(the_repository); m; m = m->next)
 894                         count += m->num_objects;
 895                 for (p = the_repository->objects->packed_git; p; p = p->next) {
 896                         if (open_pack_index(p))
 897                                 continue;
 898                         count += p->num_objects;
 899                 }
 900                 the_repository->objects->approximate_object_count = count;
 901         }
 902         return the_repository->objects->approximate_object_count;
 903 }
 904
 905 static void *get_next_packed_git(const void *p)
 906 {
 907         return ((const struct packed_git *)p)->next;
 908 }
 909
 910 static void set_next_packed_git(void *p, void *next)
 911 {
 912         ((struct packed_git *)p)->next = next;
 913 }
 914
 915 static int sort_pack(const void *a_, const void *b_)
 916 {
 917         const struct packed_git *a = a_;
 918         const struct packed_git *b = b_;
 919         int st;
 920
 921         /*
 922          * Local packs tend to contain objects specific to our
 923          * variant of the project than remote ones.  In addition,
 924          * remote ones could be on a network mounted filesystem.
 925          * Favor local ones for these reasons.
 926          */
 927         st = a->pack_local - b->pack_local;
 928         if (st)
 929                 return -st;
 930
 931         /*
 932          * Younger packs tend to contain more recent objects,
 933          * and more recent objects tend to get accessed more
 934          * often.
 935          */
 936         if (a->mtime < b->mtime)
 937                 return 1;
 938         else if (a->mtime == b->mtime)
 939                 return 0;
 940         return -1;
 941 }
 942
 943 static void rearrange_packed_git(struct repository *r)
 944 {
 945         r->objects->packed_git = llist_mergesort(
 946                 r->objects->packed_git, get_next_packed_git,
 947                 set_next_packed_git, sort_pack);
 948 }
 949
 950 static void prepare_packed_git_mru(struct repository *r)
 951 {
 952         struct packed_git *p;
 953
 954         INIT_LIST_HEAD(&r->objects->packed_git_mru);
 955
 956         for (p = r->objects->packed_git; p; p = p->next)
 957                 list_add_tail(&p->mru, &r->objects->packed_git_mru);
 958 }
 959
 960 static void prepare_packed_git(struct repository *r)
 961 {
 962         struct alternate_object_database *alt;
 963
 964         if (r->objects->packed_git_initialized)
 965                 return;
 966         prepare_multi_pack_index_one(r, r->objects->objectdir);
 967         prepare_packed_git_one(r, r->objects->objectdir, 1);
 968         prepare_alt_odb(r);
 969         for (alt = r->objects->alt_odb_list; alt; alt = alt->next) {
 970                 prepare_multi_pack_index_one(r, alt->path);
 971                 prepare_packed_git_one(r, alt->path, 0);
 972         }
 973         rearrange_packed_git(r);
 974         prepare_packed_git_mru(r);
 975         r->objects->packed_git_initialized = 1;
 976 }
 977
 978 void reprepare_packed_git(struct repository *r)
 979 {
 980         r->objects->approximate_object_count_valid = 0;
 981         r->objects->packed_git_initialized = 0;
 982         prepare_packed_git(r);
 983 }
 984
 985 struct packed_git *get_packed_git(struct repository *r)
 986 {
 987         prepare_packed_git(r);
 988         return r->objects->packed_git;
 989 }
 990
 991 struct multi_pack_index *get_multi_pack_index(struct repository *r)
 992 {
 993         prepare_packed_git(r);
 994         return r->objects->multi_pack_index;
 995 }
 996
 997 struct list_head *get_packed_git_mru(struct repository *r)
 998 {
 999         prepare_packed_git(r);
1000         return &r->objects->packed_git_mru;
1001 }
1002
1003 unsigned long unpack_object_header_buffer(const unsigned char *buf,
1004                 unsigned long len, enum object_type *type, unsigned long *sizep)
1005 {
1006         unsigned shift;
1007         unsigned long size, c;
1008         unsigned long used = 0;
1009
1010         c = buf[used++];
1011         *type = (c >> 4) & 7;
1012         size = c & 15;
1013         shift = 4;
1014         while (c & 0x80) {
1015                 if (len <= used || bitsizeof(long) <= shift) {
1016                         error("bad object header");
1017                         size = used = 0;
1018                         break;
1019                 }
1020                 c = buf[used++];
1021                 size += (c & 0x7f) << shift;
1022                 shift += 7;
1023         }
1024         *sizep = size;
1025         return used;
1026 }
1027
1028 unsigned long get_size_from_delta(struct packed_git *p,
1029                                   struct pack_window **w_curs,
1030                                   off_t curpos)
1031 {
1032         const unsigned char *data;
1033         unsigned char delta_head[20], *in;
1034         git_zstream stream;
1035         int st;
1036
1037         memset(&stream, 0, sizeof(stream));
1038         stream.next_out = delta_head;
1039         stream.avail_out = sizeof(delta_head);
1040
1041         git_inflate_init(&stream);
1042         do {
1043                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1044                 stream.next_in = in;
1045                 st = git_inflate(&stream, Z_FINISH);
1046                 curpos += stream.next_in - in;
1047         } while ((st == Z_OK || st == Z_BUF_ERROR) &&
1048                  stream.total_out < sizeof(delta_head));
1049         git_inflate_end(&stream);
1050         if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
1051                 error("delta data unpack-initial failed");
1052                 return 0;
1053         }
1054
1055         /* Examine the initial part of the delta to figure out
1056          * the result size.
1057          */
1058         data = delta_head;
1059
1060         /* ignore base size */
1061         get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1062
1063         /* Read the result size */
1064         return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1065 }
1066
1067 int unpack_object_header(struct packed_git *p,
1068                          struct pack_window **w_curs,
1069                          off_t *curpos,
1070                          unsigned long *sizep)
1071 {
1072         unsigned char *base;
1073         unsigned long left;
1074         unsigned long used;
1075         enum object_type type;
1076
1077         /* use_pack() assures us we have [base, base + 20) available
1078          * as a range that we can look at.  (Its actually the hash
1079          * size that is assured.)  With our object header encoding
1080          * the maximum deflated object size is 2^137, which is just
1081          * insane, so we know won't exceed what we have been given.
1082          */
1083         base = use_pack(p, w_curs, *curpos, &left);
1084         used = unpack_object_header_buffer(base, left, &type, sizep);
1085         if (!used) {
1086                 type = OBJ_BAD;
1087         } else
1088                 *curpos += used;
1089
1090         return type;
1091 }
1092
1093 void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
1094 {
1095         unsigned i;
1096         for (i = 0; i < p->num_bad_objects; i++)
1097                 if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
1098                         return;
1099         p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
1100                                       st_mult(GIT_MAX_RAWSZ,
1101                                               st_add(p->num_bad_objects, 1)));
1102         hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
1103         p->num_bad_objects++;
1104 }
1105
1106 const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
1107 {
1108         struct packed_git *p;
1109         unsigned i;
1110
1111         for (p = the_repository->objects->packed_git; p; p = p->next)
1112                 for (i = 0; i < p->num_bad_objects; i++)
1113                         if (!hashcmp(sha1,
1114                                      p->bad_object_sha1 + the_hash_algo->rawsz * i))
1115                                 return p;
1116         return NULL;
1117 }
1118
1119 static off_t get_delta_base(struct packed_git *p,
1120                                     struct pack_window **w_curs,
1121                                     off_t *curpos,
1122                                     enum object_type type,
1123                                     off_t delta_obj_offset)
1124 {
1125         unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1126         off_t base_offset;
1127
1128         /* use_pack() assured us we have [base_info, base_info + 20)
1129          * as a range that we can look at without walking off the
1130          * end of the mapped window.  Its actually the hash size
1131          * that is assured.  An OFS_DELTA longer than the hash size
1132          * is stupid, as then a REF_DELTA would be smaller to store.
1133          */
1134         if (type == OBJ_OFS_DELTA) {
1135                 unsigned used = 0;
1136                 unsigned char c = base_info[used++];
1137                 base_offset = c & 127;
1138                 while (c & 128) {
1139                         base_offset += 1;
1140                         if (!base_offset || MSB(base_offset, 7))
1141                                 return 0;  /* overflow */
1142                         c = base_info[used++];
1143                         base_offset = (base_offset << 7) + (c & 127);
1144                 }
1145                 base_offset = delta_obj_offset - base_offset;
1146                 if (base_offset <= 0 || base_offset >= delta_obj_offset)
1147                         return 0;  /* out of bound */
1148                 *curpos += used;
1149         } else if (type == OBJ_REF_DELTA) {
1150                 /* The base entry _must_ be in the same pack */
1151                 base_offset = find_pack_entry_one(base_info, p);
1152                 *curpos += the_hash_algo->rawsz;
1153         } else
1154                 die("I am totally screwed");
1155         return base_offset;
1156 }
1157
1158 /*
1159  * Like get_delta_base above, but we return the sha1 instead of the pack
1160  * offset. This means it is cheaper for REF deltas (we do not have to do
1161  * the final object lookup), but more expensive for OFS deltas (we
1162  * have to load the revidx to convert the offset back into a sha1).
1163  */
1164 static const unsigned char *get_delta_base_sha1(struct packed_git *p,
1165                                                 struct pack_window **w_curs,
1166                                                 off_t curpos,
1167                                                 enum object_type type,
1168                                                 off_t delta_obj_offset)
1169 {
1170         if (type == OBJ_REF_DELTA) {
1171                 unsigned char *base = use_pack(p, w_curs, curpos, NULL);
1172                 return base;
1173         } else if (type == OBJ_OFS_DELTA) {
1174                 struct revindex_entry *revidx;
1175                 off_t base_offset = get_delta_base(p, w_curs, &curpos,
1176                                                    type, delta_obj_offset);
1177
1178                 if (!base_offset)
1179                         return NULL;
1180
1181                 revidx = find_pack_revindex(p, base_offset);
1182                 if (!revidx)
1183                         return NULL;
1184
1185                 return nth_packed_object_sha1(p, revidx->nr);
1186         } else
1187                 return NULL;
1188 }
1189
1190 static int retry_bad_packed_offset(struct repository *r,
1191                                    struct packed_git *p,
1192                                    off_t obj_offset)
1193 {
1194         int type;
1195         struct revindex_entry *revidx;
1196         struct object_id oid;
1197         revidx = find_pack_revindex(p, obj_offset);
1198         if (!revidx)
1199                 return OBJ_BAD;
1200         nth_packed_object_oid(&oid, p, revidx->nr);
1201         mark_bad_packed_object(p, oid.hash);
1202         type = oid_object_info(r, &oid, NULL);
1203         if (type <= OBJ_NONE)
1204                 return OBJ_BAD;
1205         return type;
1206 }
1207
1208 #define POI_STACK_PREALLOC 64
1209
1210 static enum object_type packed_to_object_type(struct repository *r,
1211                                               struct packed_git *p,
1212                                               off_t obj_offset,
1213                                               enum object_type type,
1214                                               struct pack_window **w_curs,
1215                                               off_t curpos)
1216 {
1217         off_t small_poi_stack[POI_STACK_PREALLOC];
1218         off_t *poi_stack = small_poi_stack;
1219         int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
1220
1221         while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1222                 off_t base_offset;
1223                 unsigned long size;
1224                 /* Push the object we're going to leave behind */
1225                 if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
1226                         poi_stack_alloc = alloc_nr(poi_stack_nr);
1227                         ALLOC_ARRAY(poi_stack, poi_stack_alloc);
1228                         memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
1229                 } else {
1230                         ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
1231                 }
1232                 poi_stack[poi_stack_nr++] = obj_offset;
1233                 /* If parsing the base offset fails, just unwind */
1234                 base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1235                 if (!base_offset)
1236                         goto unwind;
1237                 curpos = obj_offset = base_offset;
1238                 type = unpack_object_header(p, w_curs, &curpos, &size);
1239                 if (type <= OBJ_NONE) {
1240                         /* If getting the base itself fails, we first
1241                          * retry the base, otherwise unwind */
1242                         type = retry_bad_packed_offset(r, p, base_offset);
1243                         if (type > OBJ_NONE)
1244                                 goto out;
1245                         goto unwind;
1246                 }
1247         }
1248
1249         switch (type) {
1250         case OBJ_BAD:
1251         case OBJ_COMMIT:
1252         case OBJ_TREE:
1253         case OBJ_BLOB:
1254         case OBJ_TAG:
1255                 break;
1256         default:
1257                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1258                       type, (uintmax_t)obj_offset, p->pack_name);
1259                 type = OBJ_BAD;
1260         }
1261
1262 out:
1263         if (poi_stack != small_poi_stack)
1264                 free(poi_stack);
1265         return type;
1266
1267 unwind:
1268         while (poi_stack_nr) {
1269                 obj_offset = poi_stack[--poi_stack_nr];
1270                 type = retry_bad_packed_offset(r, p, obj_offset);
1271                 if (type > OBJ_NONE)
1272                         goto out;
1273         }
1274         type = OBJ_BAD;
1275         goto out;
1276 }
1277
1278 static struct hashmap delta_base_cache;
1279 static size_t delta_base_cached;
1280
1281 static LIST_HEAD(delta_base_cache_lru);
1282
1283 struct delta_base_cache_key {
1284         struct packed_git *p;
1285         off_t base_offset;
1286 };
1287
1288 struct delta_base_cache_entry {
1289         struct hashmap hash;
1290         struct delta_base_cache_key key;
1291         struct list_head lru;
1292         void *data;
1293         unsigned long size;
1294         enum object_type type;
1295 };
1296
1297 static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
1298 {
1299         unsigned int hash;
1300
1301         hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
1302         hash += (hash >> 8) + (hash >> 16);
1303         return hash;
1304 }
1305
1306 static struct delta_base_cache_entry *
1307 get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
1308 {
1309         struct hashmap_entry entry;
1310         struct delta_base_cache_key key;
1311
1312         if (!delta_base_cache.cmpfn)
1313                 return NULL;
1314
1315         hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
1316         key.p = p;
1317         key.base_offset = base_offset;
1318         return hashmap_get(&delta_base_cache, &entry, &key);
1319 }
1320
1321 static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
1322                                    const struct delta_base_cache_key *b)
1323 {
1324         return a->p == b->p && a->base_offset == b->base_offset;
1325 }
1326
1327 static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
1328                                      const void *va, const void *vb,
1329                                      const void *vkey)
1330 {
1331         const struct delta_base_cache_entry *a = va, *b = vb;
1332         const struct delta_base_cache_key *key = vkey;
1333         if (key)
1334                 return !delta_base_cache_key_eq(&a->key, key);
1335         else
1336                 return !delta_base_cache_key_eq(&a->key, &b->key);
1337 }
1338
1339 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
1340 {
1341         return !!get_delta_base_cache_entry(p, base_offset);
1342 }
1343
1344 /*
1345  * Remove the entry from the cache, but do _not_ free the associated
1346  * entry data. The caller takes ownership of the "data" buffer, and
1347  * should copy out any fields it wants before detaching.
1348  */
1349 static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
1350 {
1351         hashmap_remove(&delta_base_cache, ent, &ent->key);
1352         list_del(&ent->lru);
1353         delta_base_cached -= ent->size;
1354         free(ent);
1355 }
1356
1357 static void *cache_or_unpack_entry(struct repository *r, struct packed_git *p,
1358                                    off_t base_offset, unsigned long *base_size,
1359                                    enum object_type *type)
1360 {
1361         struct delta_base_cache_entry *ent;
1362
1363         ent = get_delta_base_cache_entry(p, base_offset);
1364         if (!ent)
1365                 return unpack_entry(r, p, base_offset, type, base_size);
1366
1367         if (type)
1368                 *type = ent->type;
1369         if (base_size)
1370                 *base_size = ent->size;
1371         return xmemdupz(ent->data, ent->size);
1372 }
1373
1374 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
1375 {
1376         free(ent->data);
1377         detach_delta_base_cache_entry(ent);
1378 }
1379
1380 void clear_delta_base_cache(void)
1381 {
1382         struct list_head *lru, *tmp;
1383         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1384                 struct delta_base_cache_entry *entry =
1385                         list_entry(lru, struct delta_base_cache_entry, lru);
1386                 release_delta_base_cache(entry);
1387         }
1388 }
1389
1390 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
1391         void *base, unsigned long base_size, enum object_type type)
1392 {
1393         struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
1394         struct list_head *lru, *tmp;
1395
1396         delta_base_cached += base_size;
1397
1398         list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
1399                 struct delta_base_cache_entry *f =
1400                         list_entry(lru, struct delta_base_cache_entry, lru);
1401                 if (delta_base_cached <= delta_base_cache_limit)
1402                         break;
1403                 release_delta_base_cache(f);
1404         }
1405
1406         ent->key.p = p;
1407         ent->key.base_offset = base_offset;
1408         ent->type = type;
1409         ent->data = base;
1410         ent->size = base_size;
1411         list_add_tail(&ent->lru, &delta_base_cache_lru);
1412
1413         if (!delta_base_cache.cmpfn)
1414                 hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
1415         hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
1416         hashmap_add(&delta_base_cache, ent);
1417 }
1418
1419 int packed_object_info(struct repository *r, struct packed_git *p,
1420                        off_t obj_offset, struct object_info *oi)
1421 {
1422         struct pack_window *w_curs = NULL;
1423         unsigned long size;
1424         off_t curpos = obj_offset;
1425         enum object_type type;
1426
1427         /*
1428          * We always get the representation type, but only convert it to
1429          * a "real" type later if the caller is interested.
1430          */
1431         if (oi->contentp) {
1432                 *oi->contentp = cache_or_unpack_entry(r, p, obj_offset, oi->sizep,
1433                                                       &type);
1434                 if (!*oi->contentp)
1435                         type = OBJ_BAD;
1436         } else {
1437                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1438         }
1439
1440         if (!oi->contentp && oi->sizep) {
1441                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1442                         off_t tmp_pos = curpos;
1443                         off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
1444                                                            type, obj_offset);
1445                         if (!base_offset) {
1446                                 type = OBJ_BAD;
1447                                 goto out;
1448                         }
1449                         *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
1450                         if (*oi->sizep == 0) {
1451                                 type = OBJ_BAD;
1452                                 goto out;
1453                         }
1454                 } else {
1455                         *oi->sizep = size;
1456                 }
1457         }
1458
1459         if (oi->disk_sizep) {
1460                 struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1461                 *oi->disk_sizep = revidx[1].offset - obj_offset;
1462         }
1463
1464         if (oi->typep || oi->type_name) {
1465                 enum object_type ptot;
1466                 ptot = packed_to_object_type(r, p, obj_offset,
1467                                              type, &w_curs, curpos);
1468                 if (oi->typep)
1469                         *oi->typep = ptot;
1470                 if (oi->type_name) {
1471                         const char *tn = type_name(ptot);
1472                         if (tn)
1473                                 strbuf_addstr(oi->type_name, tn);
1474                 }
1475                 if (ptot < 0) {
1476                         type = OBJ_BAD;
1477                         goto out;
1478                 }
1479         }
1480
1481         if (oi->delta_base_sha1) {
1482                 if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
1483                         const unsigned char *base;
1484
1485                         base = get_delta_base_sha1(p, &w_curs, curpos,
1486                                                    type, obj_offset);
1487                         if (!base) {
1488                                 type = OBJ_BAD;
1489                                 goto out;
1490                         }
1491
1492                         hashcpy(oi->delta_base_sha1, base);
1493                 } else
1494                         hashclr(oi->delta_base_sha1);
1495         }
1496
1497         oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
1498                                                           OI_PACKED;
1499
1500 out:
1501         unuse_pack(&w_curs);
1502         return type;
1503 }
1504
1505 static void *unpack_compressed_entry(struct packed_git *p,
1506                                     struct pack_window **w_curs,
1507                                     off_t curpos,
1508                                     unsigned long size)
1509 {
1510         int st;
1511         git_zstream stream;
1512         unsigned char *buffer, *in;
1513
1514         buffer = xmallocz_gently(size);
1515         if (!buffer)
1516                 return NULL;
1517         memset(&stream, 0, sizeof(stream));
1518         stream.next_out = buffer;
1519         stream.avail_out = size + 1;
1520
1521         git_inflate_init(&stream);
1522         do {
1523                 in = use_pack(p, w_curs, curpos, &stream.avail_in);
1524                 stream.next_in = in;
1525                 st = git_inflate(&stream, Z_FINISH);
1526                 if (!stream.avail_out)
1527                         break; /* the payload is larger than it should be */
1528                 curpos += stream.next_in - in;
1529         } while (st == Z_OK || st == Z_BUF_ERROR);
1530         git_inflate_end(&stream);
1531         if ((st != Z_STREAM_END) || stream.total_out != size) {
1532                 free(buffer);
1533                 return NULL;
1534         }
1535
1536         /* versions of zlib can clobber unconsumed portion of outbuf */
1537         buffer[size] = '\0';
1538
1539         return buffer;
1540 }
1541
1542 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
1543 {
1544         static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
1545         trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
1546                          p->pack_name, (uintmax_t)obj_offset);
1547 }
1548
1549 int do_check_packed_object_crc;
1550
1551 #define UNPACK_ENTRY_STACK_PREALLOC 64
1552 struct unpack_entry_stack_ent {
1553         off_t obj_offset;
1554         off_t curpos;
1555         unsigned long size;
1556 };
1557
1558 static void *read_object(struct repository *r,
1559                          const struct object_id *oid,
1560                          enum object_type *type,
1561                          unsigned long *size)
1562 {
1563         struct object_info oi = OBJECT_INFO_INIT;
1564         void *content;
1565         oi.typep = type;
1566         oi.sizep = size;
1567         oi.contentp = &content;
1568
1569         if (oid_object_info_extended(r, oid, &oi, 0) < 0)
1570                 return NULL;
1571         return content;
1572 }
1573
1574 void *unpack_entry(struct repository *r, struct packed_git *p, off_t obj_offset,
1575                    enum object_type *final_type, unsigned long *final_size)
1576 {
1577         struct pack_window *w_curs = NULL;
1578         off_t curpos = obj_offset;
1579         void *data = NULL;
1580         unsigned long size;
1581         enum object_type type;
1582         struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
1583         struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
1584         int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
1585         int base_from_cache = 0;
1586
1587         write_pack_access_log(p, obj_offset);
1588
1589         /* PHASE 1: drill down to the innermost base object */
1590         for (;;) {
1591                 off_t base_offset;
1592                 int i;
1593                 struct delta_base_cache_entry *ent;
1594
1595                 ent = get_delta_base_cache_entry(p, curpos);
1596                 if (ent) {
1597                         type = ent->type;
1598                         data = ent->data;
1599                         size = ent->size;
1600                         detach_delta_base_cache_entry(ent);
1601                         base_from_cache = 1;
1602                         break;
1603                 }
1604
1605                 if (do_check_packed_object_crc && p->index_version > 1) {
1606                         struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
1607                         off_t len = revidx[1].offset - obj_offset;
1608                         if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
1609                                 struct object_id oid;
1610                                 nth_packed_object_oid(&oid, p, revidx->nr);
1611                                 error("bad packed object CRC for %s",
1612                                       oid_to_hex(&oid));
1613                                 mark_bad_packed_object(p, oid.hash);
1614                                 data = NULL;
1615                                 goto out;
1616                         }
1617                 }
1618
1619                 type = unpack_object_header(p, &w_curs, &curpos, &size);
1620                 if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
1621                         break;
1622
1623                 base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1624                 if (!base_offset) {
1625                         error("failed to validate delta base reference "
1626                               "at offset %"PRIuMAX" from %s",
1627                               (uintmax_t)curpos, p->pack_name);
1628                         /* bail to phase 2, in hopes of recovery */
1629                         data = NULL;
1630                         break;
1631                 }
1632
1633                 /* push object, proceed to base */
1634                 if (delta_stack_nr >= delta_stack_alloc
1635                     && delta_stack == small_delta_stack) {
1636                         delta_stack_alloc = alloc_nr(delta_stack_nr);
1637                         ALLOC_ARRAY(delta_stack, delta_stack_alloc);
1638                         memcpy(delta_stack, small_delta_stack,
1639                                sizeof(*delta_stack)*delta_stack_nr);
1640                 } else {
1641                         ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
1642                 }
1643                 i = delta_stack_nr++;
1644                 delta_stack[i].obj_offset = obj_offset;
1645                 delta_stack[i].curpos = curpos;
1646                 delta_stack[i].size = size;
1647
1648                 curpos = obj_offset = base_offset;
1649         }
1650
1651         /* PHASE 2: handle the base */
1652         switch (type) {
1653         case OBJ_OFS_DELTA:
1654         case OBJ_REF_DELTA:
1655                 if (data)
1656                         BUG("unpack_entry: left loop at a valid delta");
1657                 break;
1658         case OBJ_COMMIT:
1659         case OBJ_TREE:
1660         case OBJ_BLOB:
1661         case OBJ_TAG:
1662                 if (!base_from_cache)
1663                         data = unpack_compressed_entry(p, &w_curs, curpos, size);
1664                 break;
1665         default:
1666                 data = NULL;
1667                 error("unknown object type %i at offset %"PRIuMAX" in %s",
1668                       type, (uintmax_t)obj_offset, p->pack_name);
1669         }
1670
1671         /* PHASE 3: apply deltas in order */
1672
1673         /* invariants:
1674          *   'data' holds the base data, or NULL if there was corruption
1675          */
1676         while (delta_stack_nr) {
1677                 void *delta_data;
1678                 void *base = data;
1679                 void *external_base = NULL;
1680                 unsigned long delta_size, base_size = size;
1681                 int i;
1682
1683                 data = NULL;
1684
1685                 if (base)
1686                         add_delta_base_cache(p, obj_offset, base, base_size, type);
1687
1688                 if (!base) {
1689                         /*
1690                          * We're probably in deep shit, but let's try to fetch
1691                          * the required base anyway from another pack or loose.
1692                          * This is costly but should happen only in the presence
1693                          * of a corrupted pack, and is better than failing outright.
1694                          */
1695                         struct revindex_entry *revidx;
1696                         struct object_id base_oid;
1697                         revidx = find_pack_revindex(p, obj_offset);
1698                         if (revidx) {
1699                                 nth_packed_object_oid(&base_oid, p, revidx->nr);
1700                                 error("failed to read delta base object %s"
1701                                       " at offset %"PRIuMAX" from %s",
1702                                       oid_to_hex(&base_oid), (uintmax_t)obj_offset,
1703                                       p->pack_name);
1704                                 mark_bad_packed_object(p, base_oid.hash);
1705                                 base = read_object(r, &base_oid, &type, &base_size);
1706                                 external_base = base;
1707                         }
1708                 }
1709
1710                 i = --delta_stack_nr;
1711                 obj_offset = delta_stack[i].obj_offset;
1712                 curpos = delta_stack[i].curpos;
1713                 delta_size = delta_stack[i].size;
1714
1715                 if (!base)
1716                         continue;
1717
1718                 delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
1719
1720                 if (!delta_data) {
1721                         error("failed to unpack compressed delta "
1722                               "at offset %"PRIuMAX" from %s",
1723                               (uintmax_t)curpos, p->pack_name);
1724                         data = NULL;
1725                         free(external_base);
1726                         continue;
1727                 }
1728
1729                 data = patch_delta(base, base_size,
1730                                    delta_data, delta_size,
1731                                    &size);
1732
1733                 /*
1734                  * We could not apply the delta; warn the user, but keep going.
1735                  * Our failure will be noticed either in the next iteration of
1736                  * the loop, or if this is the final delta, in the caller when
1737                  * we return NULL. Those code paths will take care of making
1738                  * a more explicit warning and retrying with another copy of
1739                  * the object.
1740                  */
1741                 if (!data)
1742                         error("failed to apply delta");
1743
1744                 free(delta_data);
1745                 free(external_base);
1746         }
1747
1748         if (final_type)
1749                 *final_type = type;
1750         if (final_size)
1751                 *final_size = size;
1752
1753 out:
1754         unuse_pack(&w_curs);
1755
1756         if (delta_stack != small_delta_stack)
1757                 free(delta_stack);
1758
1759         return data;
1760 }
1761
1762 int bsearch_pack(const struct object_id *oid, const struct packed_git *p, uint32_t *result)
1763 {
1764         const unsigned char *index_fanout = p->index_data;
1765         const unsigned char *index_lookup;
1766         const unsigned int hashsz = the_hash_algo->rawsz;
1767         int index_lookup_width;
1768
1769         if (!index_fanout)
1770                 BUG("bsearch_pack called without a valid pack-index");
1771
1772         index_lookup = index_fanout + 4 * 256;
1773         if (p->index_version == 1) {
1774                 index_lookup_width = hashsz + 4;
1775                 index_lookup += 4;
1776         } else {
1777                 index_lookup_width = hashsz;
1778                 index_fanout += 8;
1779                 index_lookup += 8;
1780         }
1781
1782         return bsearch_hash(oid->hash, (const uint32_t*)index_fanout,
1783                             index_lookup, index_lookup_width, result);
1784 }
1785
1786 const unsigned char *nth_packed_object_sha1(struct packed_git *p,
1787                                             uint32_t n)
1788 {
1789         const unsigned char *index = p->index_data;
1790         const unsigned int hashsz = the_hash_algo->rawsz;
1791         if (!index) {
1792                 if (open_pack_index(p))
1793                         return NULL;
1794                 index = p->index_data;
1795         }
1796         if (n >= p->num_objects)
1797                 return NULL;
1798         index += 4 * 256;
1799         if (p->index_version == 1) {
1800                 return index + (hashsz + 4) * n + 4;
1801         } else {
1802                 index += 8;
1803                 return index + hashsz * n;
1804         }
1805 }
1806
1807 const struct object_id *nth_packed_object_oid(struct object_id *oid,
1808                                               struct packed_git *p,
1809                                               uint32_t n)
1810 {
1811         const unsigned char *hash = nth_packed_object_sha1(p, n);
1812         if (!hash)
1813                 return NULL;
1814         hashcpy(oid->hash, hash);
1815         return oid;
1816 }
1817
1818 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
1819 {
1820         const unsigned char *ptr = vptr;
1821         const unsigned char *start = p->index_data;
1822         const unsigned char *end = start + p->index_size;
1823         if (ptr < start)
1824                 die(_("offset before start of pack index for %s (corrupt index?)"),
1825                     p->pack_name);
1826         /* No need to check for underflow; .idx files must be at least 8 bytes */
1827         if (ptr >= end - 8)
1828                 die(_("offset beyond end of pack index for %s (truncated index?)"),
1829                     p->pack_name);
1830 }
1831
1832 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
1833 {
1834         const unsigned char *index = p->index_data;
1835         const unsigned int hashsz = the_hash_algo->rawsz;
1836         index += 4 * 256;
1837         if (p->index_version == 1) {
1838                 return ntohl(*((uint32_t *)(index + (hashsz + 4) * n)));
1839         } else {
1840                 uint32_t off;
1841                 index += 8 + p->num_objects * (hashsz + 4);
1842                 off = ntohl(*((uint32_t *)(index + 4 * n)));
1843                 if (!(off & 0x80000000))
1844                         return off;
1845                 index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
1846                 check_pack_index_ptr(p, index);
1847                 return get_be64(index);
1848         }
1849 }
1850
1851 off_t find_pack_entry_one(const unsigned char *sha1,
1852                                   struct packed_git *p)
1853 {
1854         const unsigned char *index = p->index_data;
1855         struct object_id oid;
1856         uint32_t result;
1857
1858         if (!index) {
1859                 if (open_pack_index(p))
1860                         return 0;
1861         }
1862
1863         hashcpy(oid.hash, sha1);
1864         if (bsearch_pack(&oid, p, &result))
1865                 return nth_packed_object_offset(p, result);
1866         return 0;
1867 }
1868
1869 int is_pack_valid(struct packed_git *p)
1870 {
1871         /* An already open pack is known to be valid. */
1872         if (p->pack_fd != -1)
1873                 return 1;
1874
1875         /* If the pack has one window completely covering the
1876          * file size, the pack is known to be valid even if
1877          * the descriptor is not currently open.
1878          */
1879         if (p->windows) {
1880                 struct pack_window *w = p->windows;
1881
1882                 if (!w->offset && w->len == p->pack_size)
1883                         return 1;
1884         }
1885
1886         /* Force the pack to open to prove its valid. */
1887         return !open_packed_git(p);
1888 }
1889
1890 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1891                                   struct packed_git *packs)
1892 {
1893         struct packed_git *p;
1894
1895         for (p = packs; p; p = p->next) {
1896                 if (find_pack_entry_one(sha1, p))
1897                         return p;
1898         }
1899         return NULL;
1900
1901 }
1902
1903 static int fill_pack_entry(const struct object_id *oid,
1904                            struct pack_entry *e,
1905                            struct packed_git *p)
1906 {
1907         off_t offset;
1908
1909         if (p->num_bad_objects) {
1910                 unsigned i;
1911                 for (i = 0; i < p->num_bad_objects; i++)
1912                         if (!hashcmp(oid->hash,
1913                                      p->bad_object_sha1 + the_hash_algo->rawsz * i))
1914                                 return 0;
1915         }
1916
1917         offset = find_pack_entry_one(oid->hash, p);
1918         if (!offset)
1919                 return 0;
1920
1921         /*
1922          * We are about to tell the caller where they can locate the
1923          * requested object.  We better make sure the packfile is
1924          * still here and can be accessed before supplying that
1925          * answer, as it may have been deleted since the index was
1926          * loaded!
1927          */
1928         if (!is_pack_valid(p))
1929                 return 0;
1930         e->offset = offset;
1931         e->p = p;
1932         return 1;
1933 }
1934
1935 int find_pack_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e)
1936 {
1937         struct list_head *pos;
1938         struct multi_pack_index *m;
1939
1940         prepare_packed_git(r);
1941         if (!r->objects->packed_git && !r->objects->multi_pack_index)
1942                 return 0;
1943
1944         for (m = r->objects->multi_pack_index; m; m = m->next) {
1945                 if (fill_midx_entry(oid, e, m))
1946                         return 1;
1947         }
1948
1949         list_for_each(pos, &r->objects->packed_git_mru) {
1950                 struct packed_git *p = list_entry(pos, struct packed_git, mru);
1951                 if (fill_pack_entry(oid, e, p)) {
1952                         list_move(&p->mru, &r->objects->packed_git_mru);
1953                         return 1;
1954                 }
1955         }
1956         return 0;
1957 }
1958
1959 int has_object_pack(const struct object_id *oid)
1960 {
1961         struct pack_entry e;
1962         return find_pack_entry(the_repository, oid, &e);
1963 }
1964
1965 int has_pack_index(const unsigned char *sha1)
1966 {
1967         struct stat st;
1968         if (stat(sha1_pack_index_name(sha1), &st))
1969                 return 0;
1970         return 1;
1971 }
1972
1973 int for_each_object_in_pack(struct packed_git *p,
1974                             each_packed_object_fn cb, void *data,
1975                             enum for_each_object_flags flags)
1976 {
1977         uint32_t i;
1978         int r = 0;
1979
1980         if (flags & FOR_EACH_OBJECT_PACK_ORDER)
1981                 load_pack_revindex(p);
1982
1983         for (i = 0; i < p->num_objects; i++) {
1984                 uint32_t pos;
1985                 struct object_id oid;
1986
1987                 if (flags & FOR_EACH_OBJECT_PACK_ORDER)
1988                         pos = p->revindex[i].nr;
1989                 else
1990                         pos = i;
1991
1992                 if (!nth_packed_object_oid(&oid, p, pos))
1993                         return error("unable to get sha1 of object %u in %s",
1994                                      pos, p->pack_name);
1995
1996                 r = cb(&oid, p, pos, data);
1997                 if (r)
1998                         break;
1999         }
2000         return r;
2001 }
2002
2003 int for_each_packed_object(each_packed_object_fn cb, void *data,
2004                            enum for_each_object_flags flags)
2005 {
2006         struct packed_git *p;
2007         int r = 0;
2008         int pack_errors = 0;
2009
2010         prepare_packed_git(the_repository);
2011         for (p = the_repository->objects->packed_git; p; p = p->next) {
2012                 if ((flags & FOR_EACH_OBJECT_LOCAL_ONLY) && !p->pack_local)
2013                         continue;
2014                 if ((flags & FOR_EACH_OBJECT_PROMISOR_ONLY) &&
2015                     !p->pack_promisor)
2016                         continue;
2017                 if (open_pack_index(p)) {
2018                         pack_errors = 1;
2019                         continue;
2020                 }
2021                 r = for_each_object_in_pack(p, cb, data, flags);
2022                 if (r)
2023                         break;
2024         }
2025         return r ? r : pack_errors;
2026 }
2027
2028 static int add_promisor_object(const struct object_id *oid,
2029                                struct packed_git *pack,
2030                                uint32_t pos,
2031                                void *set_)
2032 {
2033         struct oidset *set = set_;
2034         struct object *obj = parse_object(the_repository, oid);
2035         if (!obj)
2036                 return 1;
2037
2038         oidset_insert(set, oid);
2039
2040         /*
2041          * If this is a tree, commit, or tag, the objects it refers
2042          * to are also promisor objects. (Blobs refer to no objects->)
2043          */
2044         if (obj->type == OBJ_TREE) {
2045                 struct tree *tree = (struct tree *)obj;
2046                 struct tree_desc desc;
2047                 struct name_entry entry;
2048                 if (init_tree_desc_gently(&desc, tree->buffer, tree->size))
2049                         /*
2050                          * Error messages are given when packs are
2051                          * verified, so do not print any here.
2052                          */
2053                         return 0;
2054                 while (tree_entry_gently(&desc, &entry))
2055                         oidset_insert(set, entry.oid);
2056         } else if (obj->type == OBJ_COMMIT) {
2057                 struct commit *commit = (struct commit *) obj;
2058                 struct commit_list *parents = commit->parents;
2059
2060                 oidset_insert(set, get_commit_tree_oid(commit));
2061                 for (; parents; parents = parents->next)
2062                         oidset_insert(set, &parents->item->object.oid);
2063         } else if (obj->type == OBJ_TAG) {
2064                 struct tag *tag = (struct tag *) obj;
2065                 oidset_insert(set, &tag->tagged->oid);
2066         }
2067         return 0;
2068 }
2069
2070 int is_promisor_object(const struct object_id *oid)
2071 {
2072         static struct oidset promisor_objects;
2073         static int promisor_objects_prepared;
2074
2075         if (!promisor_objects_prepared) {
2076                 if (repository_format_partial_clone) {
2077                         for_each_packed_object(add_promisor_object,
2078                                                &promisor_objects,
2079                                                FOR_EACH_OBJECT_PROMISOR_ONLY);
2080                 }
2081                 promisor_objects_prepared = 1;
2082         }
2083         return oidset_contains(&promisor_objects, oid);
2084 }