git.oblomov.eu Git - git/blob - builtin/fsck.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6 #include "tag.h"
   7 #include "refs.h"
   8 #include "pack.h"
   9 #include "cache-tree.h"
  10 #include "tree-walk.h"
  11 #include "fsck.h"
  12 #include "parse-options.h"
  13 #include "dir.h"
  14 #include "progress.h"
  15 #include "streaming.h"
  16
  17 #define REACHABLE 0x0001
  18 #define SEEN      0x0002
  19 #define HAS_OBJ   0x0004
  20
  21 static int show_root;
  22 static int show_tags;
  23 static int show_unreachable;
  24 static int include_reflogs = 1;
  25 static int check_full = 1;
  26 static int check_strict;
  27 static int keep_cache_objects;
  28 static struct object_id head_oid;
  29 static const char *head_points_at;
  30 static int errors_found;
  31 static int write_lost_and_found;
  32 static int verbose;
  33 static int show_progress = -1;
  34 static int show_dangling = 1;
  35 #define ERROR_OBJECT 01
  36 #define ERROR_REACHABLE 02
  37 #define ERROR_PACK 04
  38
  39 #ifdef NO_D_INO_IN_DIRENT
  40 #define SORT_DIRENT 0
  41 #define DIRENT_SORT_HINT(de) 0
  42 #else
  43 #define SORT_DIRENT 1
  44 #define DIRENT_SORT_HINT(de) ((de)->d_ino)
  45 #endif
  46
  47 static void objreport(struct object *obj, const char *severity,
  48                       const char *err, va_list params)
  49 {
  50         fprintf(stderr, "%s in %s %s: ",
  51                 severity, typename(obj->type), sha1_to_hex(obj->sha1));
  52         vfprintf(stderr, err, params);
  53         fputs("\n", stderr);
  54 }
  55
  56 __attribute__((format (printf, 2, 3)))
  57 static int objerror(struct object *obj, const char *err, ...)
  58 {
  59         va_list params;
  60         va_start(params, err);
  61         errors_found |= ERROR_OBJECT;
  62         objreport(obj, "error", err, params);
  63         va_end(params);
  64         return -1;
  65 }
  66
  67 __attribute__((format (printf, 3, 4)))
  68 static int fsck_error_func(struct object *obj, int type, const char *err, ...)
  69 {
  70         va_list params;
  71         va_start(params, err);
  72         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", err, params);
  73         va_end(params);
  74         return (type == FSCK_WARN) ? 0 : 1;
  75 }
  76
  77 static struct object_array pending;
  78
  79 static int mark_object(struct object *obj, int type, void *data)
  80 {
  81         struct object *parent = data;
  82
  83         /*
  84          * The only case data is NULL or type is OBJ_ANY is when
  85          * mark_object_reachable() calls us.  All the callers of
  86          * that function has non-NULL obj hence ...
  87          */
  88         if (!obj) {
  89                 /* ... these references to parent->fld are safe here */
  90                 printf("broken link from %7s %s\n",
  91                            typename(parent->type), sha1_to_hex(parent->sha1));
  92                 printf("broken link from %7s %s\n",
  93                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
  94                 errors_found |= ERROR_REACHABLE;
  95                 return 1;
  96         }
  97
  98         if (type != OBJ_ANY && obj->type != type)
  99                 /* ... and the reference to parent is safe here */
 100                 objerror(parent, "wrong object type in link");
 101
 102         if (obj->flags & REACHABLE)
 103                 return 0;
 104         obj->flags |= REACHABLE;
 105         if (!(obj->flags & HAS_OBJ)) {
 106                 if (parent && !has_sha1_file(obj->sha1)) {
 107                         printf("broken link from %7s %s\n",
 108                                  typename(parent->type), sha1_to_hex(parent->sha1));
 109                         printf("              to %7s %s\n",
 110                                  typename(obj->type), sha1_to_hex(obj->sha1));
 111                         errors_found |= ERROR_REACHABLE;
 112                 }
 113                 return 1;
 114         }
 115
 116         add_object_array(obj, NULL, &pending);
 117         return 0;
 118 }
 119
 120 static void mark_object_reachable(struct object *obj)
 121 {
 122         mark_object(obj, OBJ_ANY, NULL);
 123 }
 124
 125 static int traverse_one_object(struct object *obj)
 126 {
 127         int result;
 128         struct tree *tree = NULL;
 129
 130         if (obj->type == OBJ_TREE) {
 131                 tree = (struct tree *)obj;
 132                 if (parse_tree(tree) < 0)
 133                         return 1; /* error already displayed */
 134         }
 135         result = fsck_walk(obj, mark_object, obj);
 136         if (tree)
 137                 free_tree_buffer(tree);
 138         return result;
 139 }
 140
 141 static int traverse_reachable(void)
 142 {
 143         struct progress *progress = NULL;
 144         unsigned int nr = 0;
 145         int result = 0;
 146         if (show_progress)
 147                 progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
 148         while (pending.nr) {
 149                 struct object_array_entry *entry;
 150                 struct object *obj;
 151
 152                 entry = pending.objects + --pending.nr;
 153                 obj = entry->item;
 154                 result |= traverse_one_object(obj);
 155                 display_progress(progress, ++nr);
 156         }
 157         stop_progress(&progress);
 158         return !!result;
 159 }
 160
 161 static int mark_used(struct object *obj, int type, void *data)
 162 {
 163         if (!obj)
 164                 return 1;
 165         obj->used = 1;
 166         return 0;
 167 }
 168
 169 /*
 170  * Check a single reachable object
 171  */
 172 static void check_reachable_object(struct object *obj)
 173 {
 174         /*
 175          * We obviously want the object to be parsed,
 176          * except if it was in a pack-file and we didn't
 177          * do a full fsck
 178          */
 179         if (!(obj->flags & HAS_OBJ)) {
 180                 if (has_sha1_pack(obj->sha1))
 181                         return; /* it is in pack - forget about it */
 182                 printf("missing %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 183                 errors_found |= ERROR_REACHABLE;
 184                 return;
 185         }
 186 }
 187
 188 /*
 189  * Check a single unreachable object
 190  */
 191 static void check_unreachable_object(struct object *obj)
 192 {
 193         /*
 194          * Missing unreachable object? Ignore it. It's not like
 195          * we miss it (since it can't be reached), nor do we want
 196          * to complain about it being unreachable (since it does
 197          * not exist).
 198          */
 199         if (!obj->parsed)
 200                 return;
 201
 202         /*
 203          * Unreachable object that exists? Show it if asked to,
 204          * since this is something that is prunable.
 205          */
 206         if (show_unreachable) {
 207                 printf("unreachable %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 208                 return;
 209         }
 210
 211         /*
 212          * "!used" means that nothing at all points to it, including
 213          * other unreachable objects. In other words, it's the "tip"
 214          * of some set of unreachable objects, usually a commit that
 215          * got dropped.
 216          *
 217          * Such starting points are more interesting than some random
 218          * set of unreachable objects, so we show them even if the user
 219          * hasn't asked for _all_ unreachable objects. If you have
 220          * deleted a branch by mistake, this is a prime candidate to
 221          * start looking at, for example.
 222          */
 223         if (!obj->used) {
 224                 if (show_dangling)
 225                         printf("dangling %s %s\n", typename(obj->type),
 226                                sha1_to_hex(obj->sha1));
 227                 if (write_lost_and_found) {
 228                         const char *filename = git_path("lost-found/%s/%s",
 229                                 obj->type == OBJ_COMMIT ? "commit" : "other",
 230                                 sha1_to_hex(obj->sha1));
 231                         FILE *f;
 232
 233                         if (safe_create_leading_directories_const(filename)) {
 234                                 error("Could not create lost-found");
 235                                 return;
 236                         }
 237                         if (!(f = fopen(filename, "w")))
 238                                 die_errno("Could not open '%s'", filename);
 239                         if (obj->type == OBJ_BLOB) {
 240                                 if (stream_blob_to_fd(fileno(f), obj->sha1, NULL, 1))
 241                                         die_errno("Could not write '%s'", filename);
 242                         } else
 243                                 fprintf(f, "%s\n", sha1_to_hex(obj->sha1));
 244                         if (fclose(f))
 245                                 die_errno("Could not finish '%s'",
 246                                           filename);
 247                 }
 248                 return;
 249         }
 250
 251         /*
 252          * Otherwise? It's there, it's unreachable, and some other unreachable
 253          * object points to it. Ignore it - it's not interesting, and we showed
 254          * all the interesting cases above.
 255          */
 256 }
 257
 258 static void check_object(struct object *obj)
 259 {
 260         if (verbose)
 261                 fprintf(stderr, "Checking %s\n", sha1_to_hex(obj->sha1));
 262
 263         if (obj->flags & REACHABLE)
 264                 check_reachable_object(obj);
 265         else
 266                 check_unreachable_object(obj);
 267 }
 268
 269 static void check_connectivity(void)
 270 {
 271         int i, max;
 272
 273         /* Traverse the pending reachable objects */
 274         traverse_reachable();
 275
 276         /* Look up all the requirements, warn about missing objects.. */
 277         max = get_max_object_index();
 278         if (verbose)
 279                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
 280
 281         for (i = 0; i < max; i++) {
 282                 struct object *obj = get_indexed_object(i);
 283
 284                 if (obj)
 285                         check_object(obj);
 286         }
 287 }
 288
 289 static int fsck_obj(struct object *obj)
 290 {
 291         if (obj->flags & SEEN)
 292                 return 0;
 293         obj->flags |= SEEN;
 294
 295         if (verbose)
 296                 fprintf(stderr, "Checking %s %s\n",
 297                         typename(obj->type), sha1_to_hex(obj->sha1));
 298
 299         if (fsck_walk(obj, mark_used, NULL))
 300                 objerror(obj, "broken links");
 301         if (fsck_object(obj, NULL, 0, check_strict, fsck_error_func))
 302                 return -1;
 303
 304         if (obj->type == OBJ_TREE) {
 305                 struct tree *item = (struct tree *) obj;
 306
 307                 free_tree_buffer(item);
 308         }
 309
 310         if (obj->type == OBJ_COMMIT) {
 311                 struct commit *commit = (struct commit *) obj;
 312
 313                 free_commit_buffer(commit);
 314
 315                 if (!commit->parents && show_root)
 316                         printf("root %s\n", sha1_to_hex(commit->object.sha1));
 317         }
 318
 319         if (obj->type == OBJ_TAG) {
 320                 struct tag *tag = (struct tag *) obj;
 321
 322                 if (show_tags && tag->tagged) {
 323                         printf("tagged %s %s", typename(tag->tagged->type), sha1_to_hex(tag->tagged->sha1));
 324                         printf(" (%s) in %s\n", tag->tag, sha1_to_hex(tag->object.sha1));
 325                 }
 326         }
 327
 328         return 0;
 329 }
 330
 331 static int fsck_sha1(const unsigned char *sha1)
 332 {
 333         struct object *obj = parse_object(sha1);
 334         if (!obj) {
 335                 errors_found |= ERROR_OBJECT;
 336                 return error("%s: object corrupt or missing",
 337                              sha1_to_hex(sha1));
 338         }
 339         obj->flags |= HAS_OBJ;
 340         return fsck_obj(obj);
 341 }
 342
 343 static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
 344                            unsigned long size, void *buffer, int *eaten)
 345 {
 346         struct object *obj;
 347         obj = parse_object_buffer(sha1, type, size, buffer, eaten);
 348         if (!obj) {
 349                 errors_found |= ERROR_OBJECT;
 350                 return error("%s: object corrupt or missing", sha1_to_hex(sha1));
 351         }
 352         obj->flags = HAS_OBJ;
 353         return fsck_obj(obj);
 354 }
 355
 356 /*
 357  * This is the sorting chunk size: make it reasonably
 358  * big so that we can sort well..
 359  */
 360 #define MAX_SHA1_ENTRIES (1024)
 361
 362 struct sha1_entry {
 363         unsigned long ino;
 364         unsigned char sha1[20];
 365 };
 366
 367 static struct {
 368         unsigned long nr;
 369         struct sha1_entry *entry[MAX_SHA1_ENTRIES];
 370 } sha1_list;
 371
 372 static int ino_compare(const void *_a, const void *_b)
 373 {
 374         const struct sha1_entry *a = _a, *b = _b;
 375         unsigned long ino1 = a->ino, ino2 = b->ino;
 376         return ino1 < ino2 ? -1 : ino1 > ino2 ? 1 : 0;
 377 }
 378
 379 static void fsck_sha1_list(void)
 380 {
 381         int i, nr = sha1_list.nr;
 382
 383         if (SORT_DIRENT)
 384                 qsort(sha1_list.entry, nr,
 385                       sizeof(struct sha1_entry *), ino_compare);
 386         for (i = 0; i < nr; i++) {
 387                 struct sha1_entry *entry = sha1_list.entry[i];
 388                 unsigned char *sha1 = entry->sha1;
 389
 390                 sha1_list.entry[i] = NULL;
 391                 if (fsck_sha1(sha1))
 392                         errors_found |= ERROR_OBJECT;
 393                 free(entry);
 394         }
 395         sha1_list.nr = 0;
 396 }
 397
 398 static void add_sha1_list(unsigned char *sha1, unsigned long ino)
 399 {
 400         struct sha1_entry *entry = xmalloc(sizeof(*entry));
 401         int nr;
 402
 403         entry->ino = ino;
 404         hashcpy(entry->sha1, sha1);
 405         nr = sha1_list.nr;
 406         if (nr == MAX_SHA1_ENTRIES) {
 407                 fsck_sha1_list();
 408                 nr = 0;
 409         }
 410         sha1_list.entry[nr] = entry;
 411         sha1_list.nr = ++nr;
 412 }
 413
 414 static inline int is_loose_object_file(struct dirent *de,
 415                                        char *name, unsigned char *sha1)
 416 {
 417         if (strlen(de->d_name) != 38)
 418                 return 0;
 419         memcpy(name + 2, de->d_name, 39);
 420         return !get_sha1_hex(name, sha1);
 421 }
 422
 423 static void fsck_dir(int i, char *path)
 424 {
 425         DIR *dir = opendir(path);
 426         struct dirent *de;
 427         char name[100];
 428
 429         if (!dir)
 430                 return;
 431
 432         if (verbose)
 433                 fprintf(stderr, "Checking directory %s\n", path);
 434
 435         sprintf(name, "%02x", i);
 436         while ((de = readdir(dir)) != NULL) {
 437                 unsigned char sha1[20];
 438
 439                 if (is_dot_or_dotdot(de->d_name))
 440                         continue;
 441                 if (is_loose_object_file(de, name, sha1)) {
 442                         add_sha1_list(sha1, DIRENT_SORT_HINT(de));
 443                         continue;
 444                 }
 445                 if (starts_with(de->d_name, "tmp_obj_"))
 446                         continue;
 447                 fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
 448         }
 449         closedir(dir);
 450 }
 451
 452 static int default_refs;
 453
 454 static void fsck_handle_reflog_sha1(const char *refname, unsigned char *sha1)
 455 {
 456         struct object *obj;
 457
 458         if (!is_null_sha1(sha1)) {
 459                 obj = lookup_object(sha1);
 460                 if (obj) {
 461                         obj->used = 1;
 462                         mark_object_reachable(obj);
 463                 } else {
 464                         error("%s: invalid reflog entry %s", refname, sha1_to_hex(sha1));
 465                         errors_found |= ERROR_REACHABLE;
 466                 }
 467         }
 468 }
 469
 470 static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 471                 const char *email, unsigned long timestamp, int tz,
 472                 const char *message, void *cb_data)
 473 {
 474         const char *refname = cb_data;
 475
 476         if (verbose)
 477                 fprintf(stderr, "Checking reflog %s->%s\n",
 478                         sha1_to_hex(osha1), sha1_to_hex(nsha1));
 479
 480         fsck_handle_reflog_sha1(refname, osha1);
 481         fsck_handle_reflog_sha1(refname, nsha1);
 482         return 0;
 483 }
 484
 485 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
 486                               int flag, void *cb_data)
 487 {
 488         for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
 489         return 0;
 490 }
 491
 492 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 493                            int flag, void *cb_data)
 494 {
 495         struct object *obj;
 496
 497         obj = parse_object(oid->hash);
 498         if (!obj) {
 499                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 500                 errors_found |= ERROR_REACHABLE;
 501                 /* We'll continue with the rest despite the error.. */
 502                 return 0;
 503         }
 504         if (obj->type != OBJ_COMMIT && is_branch(refname))
 505                 error("%s: not a commit", refname);
 506         default_refs++;
 507         obj->used = 1;
 508         mark_object_reachable(obj);
 509
 510         return 0;
 511 }
 512
 513 static void get_default_heads(void)
 514 {
 515         if (head_points_at && !is_null_oid(&head_oid))
 516                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
 517         for_each_rawref(fsck_handle_ref, NULL);
 518         if (include_reflogs)
 519                 for_each_reflog(fsck_handle_reflog, NULL);
 520
 521         /*
 522          * Not having any default heads isn't really fatal, but
 523          * it does mean that "--unreachable" no longer makes any
 524          * sense (since in this case everything will obviously
 525          * be unreachable by definition.
 526          *
 527          * Showing dangling objects is valid, though (as those
 528          * dangling objects are likely lost heads).
 529          *
 530          * So we just print a warning about it, and clear the
 531          * "show_unreachable" flag.
 532          */
 533         if (!default_refs) {
 534                 fprintf(stderr, "notice: No default references\n");
 535                 show_unreachable = 0;
 536         }
 537 }
 538
 539 static void fsck_object_dir(const char *path)
 540 {
 541         int i;
 542         struct progress *progress = NULL;
 543
 544         if (verbose)
 545                 fprintf(stderr, "Checking object directory\n");
 546
 547         if (show_progress)
 548                 progress = start_progress(_("Checking object directories"), 256);
 549         for (i = 0; i < 256; i++) {
 550                 static char dir[4096];
 551                 sprintf(dir, "%s/%02x", path, i);
 552                 fsck_dir(i, dir);
 553                 display_progress(progress, i+1);
 554         }
 555         stop_progress(&progress);
 556         fsck_sha1_list();
 557 }
 558
 559 static int fsck_head_link(void)
 560 {
 561         int flag;
 562         int null_is_error = 0;
 563
 564         if (verbose)
 565                 fprintf(stderr, "Checking HEAD link\n");
 566
 567         head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, &flag);
 568         if (!head_points_at)
 569                 return error("Invalid HEAD");
 570         if (!strcmp(head_points_at, "HEAD"))
 571                 /* detached HEAD */
 572                 null_is_error = 1;
 573         else if (!starts_with(head_points_at, "refs/heads/"))
 574                 return error("HEAD points to something strange (%s)",
 575                              head_points_at);
 576         if (is_null_oid(&head_oid)) {
 577                 if (null_is_error)
 578                         return error("HEAD: detached HEAD points at nothing");
 579                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
 580                         head_points_at + 11);
 581         }
 582         return 0;
 583 }
 584
 585 static int fsck_cache_tree(struct cache_tree *it)
 586 {
 587         int i;
 588         int err = 0;
 589
 590         if (verbose)
 591                 fprintf(stderr, "Checking cache tree\n");
 592
 593         if (0 <= it->entry_count) {
 594                 struct object *obj = parse_object(it->sha1);
 595                 if (!obj) {
 596                         error("%s: invalid sha1 pointer in cache-tree",
 597                               sha1_to_hex(it->sha1));
 598                         return 1;
 599                 }
 600                 obj->used = 1;
 601                 mark_object_reachable(obj);
 602                 if (obj->type != OBJ_TREE)
 603                         err |= objerror(obj, "non-tree in cache-tree");
 604         }
 605         for (i = 0; i < it->subtree_nr; i++)
 606                 err |= fsck_cache_tree(it->down[i]->cache_tree);
 607         return err;
 608 }
 609
 610 static char const * const fsck_usage[] = {
 611         N_("git fsck [<options>] [<object>...]"),
 612         NULL
 613 };
 614
 615 static struct option fsck_opts[] = {
 616         OPT__VERBOSE(&verbose, N_("be verbose")),
 617         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
 618         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
 619         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
 620         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
 621         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
 622         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
 623         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
 624         OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
 625         OPT_BOOL(0, "lost-found", &write_lost_and_found,
 626                                 N_("write dangling objects in .git/lost-found")),
 627         OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
 628         OPT_END(),
 629 };
 630
 631 int cmd_fsck(int argc, const char **argv, const char *prefix)
 632 {
 633         int i, heads;
 634         struct alternate_object_database *alt;
 635
 636         errors_found = 0;
 637         check_replace_refs = 0;
 638
 639         argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);
 640
 641         if (show_progress == -1)
 642                 show_progress = isatty(2);
 643         if (verbose)
 644                 show_progress = 0;
 645
 646         if (write_lost_and_found) {
 647                 check_full = 1;
 648                 include_reflogs = 0;
 649         }
 650
 651         fsck_head_link();
 652         fsck_object_dir(get_object_directory());
 653
 654         prepare_alt_odb();
 655         for (alt = alt_odb_list; alt; alt = alt->next) {
 656                 char namebuf[PATH_MAX];
 657                 int namelen = alt->name - alt->base;
 658                 memcpy(namebuf, alt->base, namelen);
 659                 namebuf[namelen - 1] = 0;
 660                 fsck_object_dir(namebuf);
 661         }
 662
 663         if (check_full) {
 664                 struct packed_git *p;
 665                 uint32_t total = 0, count = 0;
 666                 struct progress *progress = NULL;
 667
 668                 prepare_packed_git();
 669
 670                 if (show_progress) {
 671                         for (p = packed_git; p; p = p->next) {
 672                                 if (open_pack_index(p))
 673                                         continue;
 674                                 total += p->num_objects;
 675                         }
 676
 677                         progress = start_progress(_("Checking objects"), total);
 678                 }
 679                 for (p = packed_git; p; p = p->next) {
 680                         /* verify gives error messages itself */
 681                         if (verify_pack(p, fsck_obj_buffer,
 682                                         progress, count))
 683                                 errors_found |= ERROR_PACK;
 684                         count += p->num_objects;
 685                 }
 686                 stop_progress(&progress);
 687         }
 688
 689         heads = 0;
 690         for (i = 0; i < argc; i++) {
 691                 const char *arg = argv[i];
 692                 unsigned char sha1[20];
 693                 if (!get_sha1(arg, sha1)) {
 694                         struct object *obj = lookup_object(sha1);
 695
 696                         /* Error is printed by lookup_object(). */
 697                         if (!obj)
 698                                 continue;
 699
 700                         obj->used = 1;
 701                         mark_object_reachable(obj);
 702                         heads++;
 703                         continue;
 704                 }
 705                 error("invalid parameter: expected sha1, got '%s'", arg);
 706         }
 707
 708         /*
 709          * If we've not been given any explicit head information, do the
 710          * default ones from .git/refs. We also consider the index file
 711          * in this case (ie this implies --cache).
 712          */
 713         if (!heads) {
 714                 get_default_heads();
 715                 keep_cache_objects = 1;
 716         }
 717
 718         if (keep_cache_objects) {
 719                 read_cache();
 720                 for (i = 0; i < active_nr; i++) {
 721                         unsigned int mode;
 722                         struct blob *blob;
 723                         struct object *obj;
 724
 725                         mode = active_cache[i]->ce_mode;
 726                         if (S_ISGITLINK(mode))
 727                                 continue;
 728                         blob = lookup_blob(active_cache[i]->sha1);
 729                         if (!blob)
 730                                 continue;
 731                         obj = &blob->object;
 732                         obj->used = 1;
 733                         mark_object_reachable(obj);
 734                 }
 735                 if (active_cache_tree)
 736                         fsck_cache_tree(active_cache_tree);
 737         }
 738
 739         check_connectivity();
 740         return errors_found;
 741 }