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 fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
  29 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
  30 static struct object_id head_oid;
  31 static const char *head_points_at;
  32 static int errors_found;
  33 static int write_lost_and_found;
  34 static int verbose;
  35 static int show_progress = -1;
  36 static int show_dangling = 1;
  37 #define ERROR_OBJECT 01
  38 #define ERROR_REACHABLE 02
  39 #define ERROR_PACK 04
  40
  41 #ifdef NO_D_INO_IN_DIRENT
  42 #define SORT_DIRENT 0
  43 #define DIRENT_SORT_HINT(de) 0
  44 #else
  45 #define SORT_DIRENT 1
  46 #define DIRENT_SORT_HINT(de) ((de)->d_ino)
  47 #endif
  48
  49 static void objreport(struct object *obj, const char *severity,
  50                       const char *err, va_list params)
  51 {
  52         fprintf(stderr, "%s in %s %s: ",
  53                 severity, typename(obj->type), sha1_to_hex(obj->sha1));
  54         vfprintf(stderr, err, params);
  55         fputs("\n", stderr);
  56 }
  57
  58 __attribute__((format (printf, 2, 3)))
  59 static int objerror(struct object *obj, const char *err, ...)
  60 {
  61         va_list params;
  62         va_start(params, err);
  63         errors_found |= ERROR_OBJECT;
  64         objreport(obj, "error", err, params);
  65         va_end(params);
  66         return -1;
  67 }
  68
  69 __attribute__((format (printf, 3, 4)))
  70 static int fsck_error_func(struct object *obj, int type, const char *err, ...)
  71 {
  72         va_list params;
  73         va_start(params, err);
  74         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", err, params);
  75         va_end(params);
  76         return (type == FSCK_WARN) ? 0 : 1;
  77 }
  78
  79 static struct object_array pending;
  80
  81 static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
  82 {
  83         struct object *parent = data;
  84
  85         /*
  86          * The only case data is NULL or type is OBJ_ANY is when
  87          * mark_object_reachable() calls us.  All the callers of
  88          * that function has non-NULL obj hence ...
  89          */
  90         if (!obj) {
  91                 /* ... these references to parent->fld are safe here */
  92                 printf("broken link from %7s %s\n",
  93                            typename(parent->type), sha1_to_hex(parent->sha1));
  94                 printf("broken link from %7s %s\n",
  95                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
  96                 errors_found |= ERROR_REACHABLE;
  97                 return 1;
  98         }
  99
 100         if (type != OBJ_ANY && obj->type != type)
 101                 /* ... and the reference to parent is safe here */
 102                 objerror(parent, "wrong object type in link");
 103
 104         if (obj->flags & REACHABLE)
 105                 return 0;
 106         obj->flags |= REACHABLE;
 107         if (!(obj->flags & HAS_OBJ)) {
 108                 if (parent && !has_sha1_file(obj->sha1)) {
 109                         printf("broken link from %7s %s\n",
 110                                  typename(parent->type), sha1_to_hex(parent->sha1));
 111                         printf("              to %7s %s\n",
 112                                  typename(obj->type), sha1_to_hex(obj->sha1));
 113                         errors_found |= ERROR_REACHABLE;
 114                 }
 115                 return 1;
 116         }
 117
 118         add_object_array(obj, NULL, &pending);
 119         return 0;
 120 }
 121
 122 static void mark_object_reachable(struct object *obj)
 123 {
 124         mark_object(obj, OBJ_ANY, NULL, NULL);
 125 }
 126
 127 static int traverse_one_object(struct object *obj)
 128 {
 129         int result;
 130         struct tree *tree = NULL;
 131
 132         if (obj->type == OBJ_TREE) {
 133                 tree = (struct tree *)obj;
 134                 if (parse_tree(tree) < 0)
 135                         return 1; /* error already displayed */
 136         }
 137         result = fsck_walk(obj, obj, &fsck_walk_options);
 138         if (tree)
 139                 free_tree_buffer(tree);
 140         return result;
 141 }
 142
 143 static int traverse_reachable(void)
 144 {
 145         struct progress *progress = NULL;
 146         unsigned int nr = 0;
 147         int result = 0;
 148         if (show_progress)
 149                 progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
 150         while (pending.nr) {
 151                 struct object_array_entry *entry;
 152                 struct object *obj;
 153
 154                 entry = pending.objects + --pending.nr;
 155                 obj = entry->item;
 156                 result |= traverse_one_object(obj);
 157                 display_progress(progress, ++nr);
 158         }
 159         stop_progress(&progress);
 160         return !!result;
 161 }
 162
 163 static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
 164 {
 165         if (!obj)
 166                 return 1;
 167         obj->used = 1;
 168         return 0;
 169 }
 170
 171 /*
 172  * Check a single reachable object
 173  */
 174 static void check_reachable_object(struct object *obj)
 175 {
 176         /*
 177          * We obviously want the object to be parsed,
 178          * except if it was in a pack-file and we didn't
 179          * do a full fsck
 180          */
 181         if (!(obj->flags & HAS_OBJ)) {
 182                 if (has_sha1_pack(obj->sha1))
 183                         return; /* it is in pack - forget about it */
 184                 printf("missing %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 185                 errors_found |= ERROR_REACHABLE;
 186                 return;
 187         }
 188 }
 189
 190 /*
 191  * Check a single unreachable object
 192  */
 193 static void check_unreachable_object(struct object *obj)
 194 {
 195         /*
 196          * Missing unreachable object? Ignore it. It's not like
 197          * we miss it (since it can't be reached), nor do we want
 198          * to complain about it being unreachable (since it does
 199          * not exist).
 200          */
 201         if (!obj->parsed)
 202                 return;
 203
 204         /*
 205          * Unreachable object that exists? Show it if asked to,
 206          * since this is something that is prunable.
 207          */
 208         if (show_unreachable) {
 209                 printf("unreachable %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 210                 return;
 211         }
 212
 213         /*
 214          * "!used" means that nothing at all points to it, including
 215          * other unreachable objects. In other words, it's the "tip"
 216          * of some set of unreachable objects, usually a commit that
 217          * got dropped.
 218          *
 219          * Such starting points are more interesting than some random
 220          * set of unreachable objects, so we show them even if the user
 221          * hasn't asked for _all_ unreachable objects. If you have
 222          * deleted a branch by mistake, this is a prime candidate to
 223          * start looking at, for example.
 224          */
 225         if (!obj->used) {
 226                 if (show_dangling)
 227                         printf("dangling %s %s\n", typename(obj->type),
 228                                sha1_to_hex(obj->sha1));
 229                 if (write_lost_and_found) {
 230                         const char *filename = git_path("lost-found/%s/%s",
 231                                 obj->type == OBJ_COMMIT ? "commit" : "other",
 232                                 sha1_to_hex(obj->sha1));
 233                         FILE *f;
 234
 235                         if (safe_create_leading_directories_const(filename)) {
 236                                 error("Could not create lost-found");
 237                                 return;
 238                         }
 239                         if (!(f = fopen(filename, "w")))
 240                                 die_errno("Could not open '%s'", filename);
 241                         if (obj->type == OBJ_BLOB) {
 242                                 if (stream_blob_to_fd(fileno(f), obj->sha1, NULL, 1))
 243                                         die_errno("Could not write '%s'", filename);
 244                         } else
 245                                 fprintf(f, "%s\n", sha1_to_hex(obj->sha1));
 246                         if (fclose(f))
 247                                 die_errno("Could not finish '%s'",
 248                                           filename);
 249                 }
 250                 return;
 251         }
 252
 253         /*
 254          * Otherwise? It's there, it's unreachable, and some other unreachable
 255          * object points to it. Ignore it - it's not interesting, and we showed
 256          * all the interesting cases above.
 257          */
 258 }
 259
 260 static void check_object(struct object *obj)
 261 {
 262         if (verbose)
 263                 fprintf(stderr, "Checking %s\n", sha1_to_hex(obj->sha1));
 264
 265         if (obj->flags & REACHABLE)
 266                 check_reachable_object(obj);
 267         else
 268                 check_unreachable_object(obj);
 269 }
 270
 271 static void check_connectivity(void)
 272 {
 273         int i, max;
 274
 275         /* Traverse the pending reachable objects */
 276         traverse_reachable();
 277
 278         /* Look up all the requirements, warn about missing objects.. */
 279         max = get_max_object_index();
 280         if (verbose)
 281                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
 282
 283         for (i = 0; i < max; i++) {
 284                 struct object *obj = get_indexed_object(i);
 285
 286                 if (obj)
 287                         check_object(obj);
 288         }
 289 }
 290
 291 static int fsck_obj(struct object *obj)
 292 {
 293         if (obj->flags & SEEN)
 294                 return 0;
 295         obj->flags |= SEEN;
 296
 297         if (verbose)
 298                 fprintf(stderr, "Checking %s %s\n",
 299                         typename(obj->type), sha1_to_hex(obj->sha1));
 300
 301         if (fsck_walk(obj, NULL, &fsck_obj_options))
 302                 objerror(obj, "broken links");
 303         if (fsck_object(obj, NULL, 0, &fsck_obj_options))
 304                 return -1;
 305
 306         if (obj->type == OBJ_TREE) {
 307                 struct tree *item = (struct tree *) obj;
 308
 309                 free_tree_buffer(item);
 310         }
 311
 312         if (obj->type == OBJ_COMMIT) {
 313                 struct commit *commit = (struct commit *) obj;
 314
 315                 free_commit_buffer(commit);
 316
 317                 if (!commit->parents && show_root)
 318                         printf("root %s\n", sha1_to_hex(commit->object.sha1));
 319         }
 320
 321         if (obj->type == OBJ_TAG) {
 322                 struct tag *tag = (struct tag *) obj;
 323
 324                 if (show_tags && tag->tagged) {
 325                         printf("tagged %s %s", typename(tag->tagged->type), sha1_to_hex(tag->tagged->sha1));
 326                         printf(" (%s) in %s\n", tag->tag, sha1_to_hex(tag->object.sha1));
 327                 }
 328         }
 329
 330         return 0;
 331 }
 332
 333 static int fsck_sha1(const unsigned char *sha1)
 334 {
 335         struct object *obj = parse_object(sha1);
 336         if (!obj) {
 337                 errors_found |= ERROR_OBJECT;
 338                 return error("%s: object corrupt or missing",
 339                              sha1_to_hex(sha1));
 340         }
 341         obj->flags |= HAS_OBJ;
 342         return fsck_obj(obj);
 343 }
 344
 345 static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
 346                            unsigned long size, void *buffer, int *eaten)
 347 {
 348         struct object *obj;
 349         obj = parse_object_buffer(sha1, type, size, buffer, eaten);
 350         if (!obj) {
 351                 errors_found |= ERROR_OBJECT;
 352                 return error("%s: object corrupt or missing", sha1_to_hex(sha1));
 353         }
 354         obj->flags = HAS_OBJ;
 355         return fsck_obj(obj);
 356 }
 357
 358 /*
 359  * This is the sorting chunk size: make it reasonably
 360  * big so that we can sort well..
 361  */
 362 #define MAX_SHA1_ENTRIES (1024)
 363
 364 struct sha1_entry {
 365         unsigned long ino;
 366         unsigned char sha1[20];
 367 };
 368
 369 static struct {
 370         unsigned long nr;
 371         struct sha1_entry *entry[MAX_SHA1_ENTRIES];
 372 } sha1_list;
 373
 374 static int ino_compare(const void *_a, const void *_b)
 375 {
 376         const struct sha1_entry *a = _a, *b = _b;
 377         unsigned long ino1 = a->ino, ino2 = b->ino;
 378         return ino1 < ino2 ? -1 : ino1 > ino2 ? 1 : 0;
 379 }
 380
 381 static void fsck_sha1_list(void)
 382 {
 383         int i, nr = sha1_list.nr;
 384
 385         if (SORT_DIRENT)
 386                 qsort(sha1_list.entry, nr,
 387                       sizeof(struct sha1_entry *), ino_compare);
 388         for (i = 0; i < nr; i++) {
 389                 struct sha1_entry *entry = sha1_list.entry[i];
 390                 unsigned char *sha1 = entry->sha1;
 391
 392                 sha1_list.entry[i] = NULL;
 393                 if (fsck_sha1(sha1))
 394                         errors_found |= ERROR_OBJECT;
 395                 free(entry);
 396         }
 397         sha1_list.nr = 0;
 398 }
 399
 400 static void add_sha1_list(unsigned char *sha1, unsigned long ino)
 401 {
 402         struct sha1_entry *entry = xmalloc(sizeof(*entry));
 403         int nr;
 404
 405         entry->ino = ino;
 406         hashcpy(entry->sha1, sha1);
 407         nr = sha1_list.nr;
 408         if (nr == MAX_SHA1_ENTRIES) {
 409                 fsck_sha1_list();
 410                 nr = 0;
 411         }
 412         sha1_list.entry[nr] = entry;
 413         sha1_list.nr = ++nr;
 414 }
 415
 416 static inline int is_loose_object_file(struct dirent *de,
 417                                        char *name, unsigned char *sha1)
 418 {
 419         if (strlen(de->d_name) != 38)
 420                 return 0;
 421         memcpy(name + 2, de->d_name, 39);
 422         return !get_sha1_hex(name, sha1);
 423 }
 424
 425 static void fsck_dir(int i, char *path)
 426 {
 427         DIR *dir = opendir(path);
 428         struct dirent *de;
 429         char name[100];
 430
 431         if (!dir)
 432                 return;
 433
 434         if (verbose)
 435                 fprintf(stderr, "Checking directory %s\n", path);
 436
 437         sprintf(name, "%02x", i);
 438         while ((de = readdir(dir)) != NULL) {
 439                 unsigned char sha1[20];
 440
 441                 if (is_dot_or_dotdot(de->d_name))
 442                         continue;
 443                 if (is_loose_object_file(de, name, sha1)) {
 444                         add_sha1_list(sha1, DIRENT_SORT_HINT(de));
 445                         continue;
 446                 }
 447                 if (starts_with(de->d_name, "tmp_obj_"))
 448                         continue;
 449                 fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
 450         }
 451         closedir(dir);
 452 }
 453
 454 static int default_refs;
 455
 456 static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 457                 const char *email, unsigned long timestamp, int tz,
 458                 const char *message, void *cb_data)
 459 {
 460         struct object *obj;
 461
 462         if (verbose)
 463                 fprintf(stderr, "Checking reflog %s->%s\n",
 464                         sha1_to_hex(osha1), sha1_to_hex(nsha1));
 465
 466         if (!is_null_sha1(osha1)) {
 467                 obj = lookup_object(osha1);
 468                 if (obj) {
 469                         obj->used = 1;
 470                         mark_object_reachable(obj);
 471                 }
 472         }
 473         obj = lookup_object(nsha1);
 474         if (obj) {
 475                 obj->used = 1;
 476                 mark_object_reachable(obj);
 477         }
 478         return 0;
 479 }
 480
 481 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
 482                               int flag, void *cb_data)
 483 {
 484         for_each_reflog_ent(logname, fsck_handle_reflog_ent, NULL);
 485         return 0;
 486 }
 487
 488 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 489                            int flag, void *cb_data)
 490 {
 491         struct object *obj;
 492
 493         obj = parse_object(oid->hash);
 494         if (!obj) {
 495                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 496                 errors_found |= ERROR_REACHABLE;
 497                 /* We'll continue with the rest despite the error.. */
 498                 return 0;
 499         }
 500         if (obj->type != OBJ_COMMIT && is_branch(refname))
 501                 error("%s: not a commit", refname);
 502         default_refs++;
 503         obj->used = 1;
 504         mark_object_reachable(obj);
 505
 506         return 0;
 507 }
 508
 509 static void get_default_heads(void)
 510 {
 511         if (head_points_at && !is_null_oid(&head_oid))
 512                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
 513         for_each_rawref(fsck_handle_ref, NULL);
 514         if (include_reflogs)
 515                 for_each_reflog(fsck_handle_reflog, NULL);
 516
 517         /*
 518          * Not having any default heads isn't really fatal, but
 519          * it does mean that "--unreachable" no longer makes any
 520          * sense (since in this case everything will obviously
 521          * be unreachable by definition.
 522          *
 523          * Showing dangling objects is valid, though (as those
 524          * dangling objects are likely lost heads).
 525          *
 526          * So we just print a warning about it, and clear the
 527          * "show_unreachable" flag.
 528          */
 529         if (!default_refs) {
 530                 fprintf(stderr, "notice: No default references\n");
 531                 show_unreachable = 0;
 532         }
 533 }
 534
 535 static void fsck_object_dir(const char *path)
 536 {
 537         int i;
 538         struct progress *progress = NULL;
 539
 540         if (verbose)
 541                 fprintf(stderr, "Checking object directory\n");
 542
 543         if (show_progress)
 544                 progress = start_progress(_("Checking object directories"), 256);
 545         for (i = 0; i < 256; i++) {
 546                 static char dir[4096];
 547                 sprintf(dir, "%s/%02x", path, i);
 548                 fsck_dir(i, dir);
 549                 display_progress(progress, i+1);
 550         }
 551         stop_progress(&progress);
 552         fsck_sha1_list();
 553 }
 554
 555 static int fsck_head_link(void)
 556 {
 557         int flag;
 558         int null_is_error = 0;
 559
 560         if (verbose)
 561                 fprintf(stderr, "Checking HEAD link\n");
 562
 563         head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, &flag);
 564         if (!head_points_at)
 565                 return error("Invalid HEAD");
 566         if (!strcmp(head_points_at, "HEAD"))
 567                 /* detached HEAD */
 568                 null_is_error = 1;
 569         else if (!starts_with(head_points_at, "refs/heads/"))
 570                 return error("HEAD points to something strange (%s)",
 571                              head_points_at);
 572         if (is_null_oid(&head_oid)) {
 573                 if (null_is_error)
 574                         return error("HEAD: detached HEAD points at nothing");
 575                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
 576                         head_points_at + 11);
 577         }
 578         return 0;
 579 }
 580
 581 static int fsck_cache_tree(struct cache_tree *it)
 582 {
 583         int i;
 584         int err = 0;
 585
 586         if (verbose)
 587                 fprintf(stderr, "Checking cache tree\n");
 588
 589         if (0 <= it->entry_count) {
 590                 struct object *obj = parse_object(it->sha1);
 591                 if (!obj) {
 592                         error("%s: invalid sha1 pointer in cache-tree",
 593                               sha1_to_hex(it->sha1));
 594                         return 1;
 595                 }
 596                 obj->used = 1;
 597                 mark_object_reachable(obj);
 598                 if (obj->type != OBJ_TREE)
 599                         err |= objerror(obj, "non-tree in cache-tree");
 600         }
 601         for (i = 0; i < it->subtree_nr; i++)
 602                 err |= fsck_cache_tree(it->down[i]->cache_tree);
 603         return err;
 604 }
 605
 606 static char const * const fsck_usage[] = {
 607         N_("git fsck [<options>] [<object>...]"),
 608         NULL
 609 };
 610
 611 static struct option fsck_opts[] = {
 612         OPT__VERBOSE(&verbose, N_("be verbose")),
 613         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
 614         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
 615         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
 616         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
 617         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
 618         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
 619         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
 620         OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
 621         OPT_BOOL(0, "lost-found", &write_lost_and_found,
 622                                 N_("write dangling objects in .git/lost-found")),
 623         OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
 624         OPT_END(),
 625 };
 626
 627 int cmd_fsck(int argc, const char **argv, const char *prefix)
 628 {
 629         int i, heads;
 630         struct alternate_object_database *alt;
 631
 632         errors_found = 0;
 633         check_replace_refs = 0;
 634
 635         argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);
 636
 637         fsck_walk_options.walk = mark_object;
 638         fsck_obj_options.walk = mark_used;
 639         fsck_obj_options.error_func = fsck_error_func;
 640         if (check_strict)
 641                 fsck_obj_options.strict = 1;
 642
 643         if (show_progress == -1)
 644                 show_progress = isatty(2);
 645         if (verbose)
 646                 show_progress = 0;
 647
 648         if (write_lost_and_found) {
 649                 check_full = 1;
 650                 include_reflogs = 0;
 651         }
 652
 653         fsck_head_link();
 654         fsck_object_dir(get_object_directory());
 655
 656         prepare_alt_odb();
 657         for (alt = alt_odb_list; alt; alt = alt->next) {
 658                 char namebuf[PATH_MAX];
 659                 int namelen = alt->name - alt->base;
 660                 memcpy(namebuf, alt->base, namelen);
 661                 namebuf[namelen - 1] = 0;
 662                 fsck_object_dir(namebuf);
 663         }
 664
 665         if (check_full) {
 666                 struct packed_git *p;
 667                 uint32_t total = 0, count = 0;
 668                 struct progress *progress = NULL;
 669
 670                 prepare_packed_git();
 671
 672                 if (show_progress) {
 673                         for (p = packed_git; p; p = p->next) {
 674                                 if (open_pack_index(p))
 675                                         continue;
 676                                 total += p->num_objects;
 677                         }
 678
 679                         progress = start_progress(_("Checking objects"), total);
 680                 }
 681                 for (p = packed_git; p; p = p->next) {
 682                         /* verify gives error messages itself */
 683                         if (verify_pack(p, fsck_obj_buffer,
 684                                         progress, count))
 685                                 errors_found |= ERROR_PACK;
 686                         count += p->num_objects;
 687                 }
 688                 stop_progress(&progress);
 689         }
 690
 691         heads = 0;
 692         for (i = 0; i < argc; i++) {
 693                 const char *arg = argv[i];
 694                 unsigned char sha1[20];
 695                 if (!get_sha1(arg, sha1)) {
 696                         struct object *obj = lookup_object(sha1);
 697
 698                         /* Error is printed by lookup_object(). */
 699                         if (!obj)
 700                                 continue;
 701
 702                         obj->used = 1;
 703                         mark_object_reachable(obj);
 704                         heads++;
 705                         continue;
 706                 }
 707                 error("invalid parameter: expected sha1, got '%s'", arg);
 708         }
 709
 710         /*
 711          * If we've not been given any explicit head information, do the
 712          * default ones from .git/refs. We also consider the index file
 713          * in this case (ie this implies --cache).
 714          */
 715         if (!heads) {
 716                 get_default_heads();
 717                 keep_cache_objects = 1;
 718         }
 719
 720         if (keep_cache_objects) {
 721                 read_cache();
 722                 for (i = 0; i < active_nr; i++) {
 723                         unsigned int mode;
 724                         struct blob *blob;
 725                         struct object *obj;
 726
 727                         mode = active_cache[i]->ce_mode;
 728                         if (S_ISGITLINK(mode))
 729                                 continue;
 730                         blob = lookup_blob(active_cache[i]->sha1);
 731                         if (!blob)
 732                                 continue;
 733                         obj = &blob->object;
 734                         obj->used = 1;
 735                         mark_object_reachable(obj);
 736                 }
 737                 if (active_cache_tree)
 738                         fsck_cache_tree(active_cache_tree);
 739         }
 740
 741         check_connectivity();
 742         return errors_found;
 743 }