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 connectivity_only;
  27 static int check_strict;
  28 static int keep_cache_objects;
  29 static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
  30 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
  31 static struct object_id head_oid;
  32 static const char *head_points_at;
  33 static int errors_found;
  34 static int write_lost_and_found;
  35 static int verbose;
  36 static int show_progress = -1;
  37 static int show_dangling = 1;
  38 #define ERROR_OBJECT 01
  39 #define ERROR_REACHABLE 02
  40 #define ERROR_PACK 04
  41
  42 #ifdef NO_D_INO_IN_DIRENT
  43 #define SORT_DIRENT 0
  44 #define DIRENT_SORT_HINT(de) 0
  45 #else
  46 #define SORT_DIRENT 1
  47 #define DIRENT_SORT_HINT(de) ((de)->d_ino)
  48 #endif
  49
  50 static int fsck_config(const char *var, const char *value, void *cb)
  51 {
  52         if (skip_prefix(var, "fsck.", &var)) {
  53                 fsck_set_msg_type(&fsck_obj_options, var, value);
  54                 return 0;
  55         }
  56
  57         return git_default_config(var, value, cb);
  58 }
  59
  60 static void objreport(struct object *obj, const char *msg_type,
  61                         const char *err)
  62 {
  63         fprintf(stderr, "%s in %s %s: %s\n",
  64                 msg_type, typename(obj->type), sha1_to_hex(obj->sha1), err);
  65 }
  66
  67 static int objerror(struct object *obj, const char *err)
  68 {
  69         errors_found |= ERROR_OBJECT;
  70         objreport(obj, "error", err);
  71         return -1;
  72 }
  73
  74 static int fsck_error_func(struct object *obj, int type, const char *message)
  75 {
  76         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", message);
  77         return (type == FSCK_WARN) ? 0 : 1;
  78 }
  79
  80 static struct object_array pending;
  81
  82 static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
  83 {
  84         struct object *parent = data;
  85
  86         /*
  87          * The only case data is NULL or type is OBJ_ANY is when
  88          * mark_object_reachable() calls us.  All the callers of
  89          * that function has non-NULL obj hence ...
  90          */
  91         if (!obj) {
  92                 /* ... these references to parent->fld are safe here */
  93                 printf("broken link from %7s %s\n",
  94                            typename(parent->type), sha1_to_hex(parent->sha1));
  95                 printf("broken link from %7s %s\n",
  96                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
  97                 errors_found |= ERROR_REACHABLE;
  98                 return 1;
  99         }
 100
 101         if (type != OBJ_ANY && obj->type != type)
 102                 /* ... and the reference to parent is safe here */
 103                 objerror(parent, "wrong object type in link");
 104
 105         if (obj->flags & REACHABLE)
 106                 return 0;
 107         obj->flags |= REACHABLE;
 108         if (!(obj->flags & HAS_OBJ)) {
 109                 if (parent && !has_sha1_file(obj->sha1)) {
 110                         printf("broken link from %7s %s\n",
 111                                  typename(parent->type), sha1_to_hex(parent->sha1));
 112                         printf("              to %7s %s\n",
 113                                  typename(obj->type), sha1_to_hex(obj->sha1));
 114                         errors_found |= ERROR_REACHABLE;
 115                 }
 116                 return 1;
 117         }
 118
 119         add_object_array(obj, NULL, &pending);
 120         return 0;
 121 }
 122
 123 static void mark_object_reachable(struct object *obj)
 124 {
 125         mark_object(obj, OBJ_ANY, NULL, NULL);
 126 }
 127
 128 static int traverse_one_object(struct object *obj)
 129 {
 130         int result;
 131         struct tree *tree = NULL;
 132
 133         if (obj->type == OBJ_TREE) {
 134                 tree = (struct tree *)obj;
 135                 if (parse_tree(tree) < 0)
 136                         return 1; /* error already displayed */
 137         }
 138         result = fsck_walk(obj, obj, &fsck_walk_options);
 139         if (tree)
 140                 free_tree_buffer(tree);
 141         return result;
 142 }
 143
 144 static int traverse_reachable(void)
 145 {
 146         struct progress *progress = NULL;
 147         unsigned int nr = 0;
 148         int result = 0;
 149         if (show_progress)
 150                 progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
 151         while (pending.nr) {
 152                 struct object_array_entry *entry;
 153                 struct object *obj;
 154
 155                 entry = pending.objects + --pending.nr;
 156                 obj = entry->item;
 157                 result |= traverse_one_object(obj);
 158                 display_progress(progress, ++nr);
 159         }
 160         stop_progress(&progress);
 161         return !!result;
 162 }
 163
 164 static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
 165 {
 166         if (!obj)
 167                 return 1;
 168         obj->used = 1;
 169         return 0;
 170 }
 171
 172 /*
 173  * Check a single reachable object
 174  */
 175 static void check_reachable_object(struct object *obj)
 176 {
 177         /*
 178          * We obviously want the object to be parsed,
 179          * except if it was in a pack-file and we didn't
 180          * do a full fsck
 181          */
 182         if (!(obj->flags & HAS_OBJ)) {
 183                 if (has_sha1_pack(obj->sha1))
 184                         return; /* it is in pack - forget about it */
 185                 if (connectivity_only && has_sha1_file(obj->sha1))
 186                         return;
 187                 printf("missing %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 188                 errors_found |= ERROR_REACHABLE;
 189                 return;
 190         }
 191 }
 192
 193 /*
 194  * Check a single unreachable object
 195  */
 196 static void check_unreachable_object(struct object *obj)
 197 {
 198         /*
 199          * Missing unreachable object? Ignore it. It's not like
 200          * we miss it (since it can't be reached), nor do we want
 201          * to complain about it being unreachable (since it does
 202          * not exist).
 203          */
 204         if (!obj->parsed)
 205                 return;
 206
 207         /*
 208          * Unreachable object that exists? Show it if asked to,
 209          * since this is something that is prunable.
 210          */
 211         if (show_unreachable) {
 212                 printf("unreachable %s %s\n", typename(obj->type), sha1_to_hex(obj->sha1));
 213                 return;
 214         }
 215
 216         /*
 217          * "!used" means that nothing at all points to it, including
 218          * other unreachable objects. In other words, it's the "tip"
 219          * of some set of unreachable objects, usually a commit that
 220          * got dropped.
 221          *
 222          * Such starting points are more interesting than some random
 223          * set of unreachable objects, so we show them even if the user
 224          * hasn't asked for _all_ unreachable objects. If you have
 225          * deleted a branch by mistake, this is a prime candidate to
 226          * start looking at, for example.
 227          */
 228         if (!obj->used) {
 229                 if (show_dangling)
 230                         printf("dangling %s %s\n", typename(obj->type),
 231                                sha1_to_hex(obj->sha1));
 232                 if (write_lost_and_found) {
 233                         const char *filename = git_path("lost-found/%s/%s",
 234                                 obj->type == OBJ_COMMIT ? "commit" : "other",
 235                                 sha1_to_hex(obj->sha1));
 236                         FILE *f;
 237
 238                         if (safe_create_leading_directories_const(filename)) {
 239                                 error("Could not create lost-found");
 240                                 return;
 241                         }
 242                         if (!(f = fopen(filename, "w")))
 243                                 die_errno("Could not open '%s'", filename);
 244                         if (obj->type == OBJ_BLOB) {
 245                                 if (stream_blob_to_fd(fileno(f), obj->sha1, NULL, 1))
 246                                         die_errno("Could not write '%s'", filename);
 247                         } else
 248                                 fprintf(f, "%s\n", sha1_to_hex(obj->sha1));
 249                         if (fclose(f))
 250                                 die_errno("Could not finish '%s'",
 251                                           filename);
 252                 }
 253                 return;
 254         }
 255
 256         /*
 257          * Otherwise? It's there, it's unreachable, and some other unreachable
 258          * object points to it. Ignore it - it's not interesting, and we showed
 259          * all the interesting cases above.
 260          */
 261 }
 262
 263 static void check_object(struct object *obj)
 264 {
 265         if (verbose)
 266                 fprintf(stderr, "Checking %s\n", sha1_to_hex(obj->sha1));
 267
 268         if (obj->flags & REACHABLE)
 269                 check_reachable_object(obj);
 270         else
 271                 check_unreachable_object(obj);
 272 }
 273
 274 static void check_connectivity(void)
 275 {
 276         int i, max;
 277
 278         /* Traverse the pending reachable objects */
 279         traverse_reachable();
 280
 281         /* Look up all the requirements, warn about missing objects.. */
 282         max = get_max_object_index();
 283         if (verbose)
 284                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
 285
 286         for (i = 0; i < max; i++) {
 287                 struct object *obj = get_indexed_object(i);
 288
 289                 if (obj)
 290                         check_object(obj);
 291         }
 292 }
 293
 294 static int fsck_obj(struct object *obj)
 295 {
 296         if (obj->flags & SEEN)
 297                 return 0;
 298         obj->flags |= SEEN;
 299
 300         if (verbose)
 301                 fprintf(stderr, "Checking %s %s\n",
 302                         typename(obj->type), sha1_to_hex(obj->sha1));
 303
 304         if (fsck_walk(obj, NULL, &fsck_obj_options))
 305                 objerror(obj, "broken links");
 306         if (fsck_object(obj, NULL, 0, &fsck_obj_options))
 307                 return -1;
 308
 309         if (obj->type == OBJ_TREE) {
 310                 struct tree *item = (struct tree *) obj;
 311
 312                 free_tree_buffer(item);
 313         }
 314
 315         if (obj->type == OBJ_COMMIT) {
 316                 struct commit *commit = (struct commit *) obj;
 317
 318                 free_commit_buffer(commit);
 319
 320                 if (!commit->parents && show_root)
 321                         printf("root %s\n", sha1_to_hex(commit->object.sha1));
 322         }
 323
 324         if (obj->type == OBJ_TAG) {
 325                 struct tag *tag = (struct tag *) obj;
 326
 327                 if (show_tags && tag->tagged) {
 328                         printf("tagged %s %s", typename(tag->tagged->type), sha1_to_hex(tag->tagged->sha1));
 329                         printf(" (%s) in %s\n", tag->tag, sha1_to_hex(tag->object.sha1));
 330                 }
 331         }
 332
 333         return 0;
 334 }
 335
 336 static int fsck_sha1(const unsigned char *sha1)
 337 {
 338         struct object *obj = parse_object(sha1);
 339         if (!obj) {
 340                 errors_found |= ERROR_OBJECT;
 341                 return error("%s: object corrupt or missing",
 342                              sha1_to_hex(sha1));
 343         }
 344         obj->flags |= HAS_OBJ;
 345         return fsck_obj(obj);
 346 }
 347
 348 static int fsck_obj_buffer(const unsigned char *sha1, enum object_type type,
 349                            unsigned long size, void *buffer, int *eaten)
 350 {
 351         struct object *obj;
 352         obj = parse_object_buffer(sha1, type, size, buffer, eaten);
 353         if (!obj) {
 354                 errors_found |= ERROR_OBJECT;
 355                 return error("%s: object corrupt or missing", sha1_to_hex(sha1));
 356         }
 357         obj->flags = HAS_OBJ;
 358         return fsck_obj(obj);
 359 }
 360
 361 /*
 362  * This is the sorting chunk size: make it reasonably
 363  * big so that we can sort well..
 364  */
 365 #define MAX_SHA1_ENTRIES (1024)
 366
 367 struct sha1_entry {
 368         unsigned long ino;
 369         unsigned char sha1[20];
 370 };
 371
 372 static struct {
 373         unsigned long nr;
 374         struct sha1_entry *entry[MAX_SHA1_ENTRIES];
 375 } sha1_list;
 376
 377 static int ino_compare(const void *_a, const void *_b)
 378 {
 379         const struct sha1_entry *a = _a, *b = _b;
 380         unsigned long ino1 = a->ino, ino2 = b->ino;
 381         return ino1 < ino2 ? -1 : ino1 > ino2 ? 1 : 0;
 382 }
 383
 384 static void fsck_sha1_list(void)
 385 {
 386         int i, nr = sha1_list.nr;
 387
 388         if (SORT_DIRENT)
 389                 qsort(sha1_list.entry, nr,
 390                       sizeof(struct sha1_entry *), ino_compare);
 391         for (i = 0; i < nr; i++) {
 392                 struct sha1_entry *entry = sha1_list.entry[i];
 393                 unsigned char *sha1 = entry->sha1;
 394
 395                 sha1_list.entry[i] = NULL;
 396                 if (fsck_sha1(sha1))
 397                         errors_found |= ERROR_OBJECT;
 398                 free(entry);
 399         }
 400         sha1_list.nr = 0;
 401 }
 402
 403 static void add_sha1_list(unsigned char *sha1, unsigned long ino)
 404 {
 405         struct sha1_entry *entry = xmalloc(sizeof(*entry));
 406         int nr;
 407
 408         entry->ino = ino;
 409         hashcpy(entry->sha1, sha1);
 410         nr = sha1_list.nr;
 411         if (nr == MAX_SHA1_ENTRIES) {
 412                 fsck_sha1_list();
 413                 nr = 0;
 414         }
 415         sha1_list.entry[nr] = entry;
 416         sha1_list.nr = ++nr;
 417 }
 418
 419 static inline int is_loose_object_file(struct dirent *de,
 420                                        char *name, unsigned char *sha1)
 421 {
 422         if (strlen(de->d_name) != 38)
 423                 return 0;
 424         memcpy(name + 2, de->d_name, 39);
 425         return !get_sha1_hex(name, sha1);
 426 }
 427
 428 static void fsck_dir(int i, char *path)
 429 {
 430         DIR *dir = opendir(path);
 431         struct dirent *de;
 432         char name[100];
 433
 434         if (!dir)
 435                 return;
 436
 437         if (verbose)
 438                 fprintf(stderr, "Checking directory %s\n", path);
 439
 440         sprintf(name, "%02x", i);
 441         while ((de = readdir(dir)) != NULL) {
 442                 unsigned char sha1[20];
 443
 444                 if (is_dot_or_dotdot(de->d_name))
 445                         continue;
 446                 if (is_loose_object_file(de, name, sha1)) {
 447                         add_sha1_list(sha1, DIRENT_SORT_HINT(de));
 448                         continue;
 449                 }
 450                 if (starts_with(de->d_name, "tmp_obj_"))
 451                         continue;
 452                 fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);
 453         }
 454         closedir(dir);
 455 }
 456
 457 static int default_refs;
 458
 459 static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 460                 const char *email, unsigned long timestamp, int tz,
 461                 const char *message, void *cb_data)
 462 {
 463         struct object *obj;
 464
 465         if (verbose)
 466                 fprintf(stderr, "Checking reflog %s->%s\n",
 467                         sha1_to_hex(osha1), sha1_to_hex(nsha1));
 468
 469         if (!is_null_sha1(osha1)) {
 470                 obj = lookup_object(osha1);
 471                 if (obj) {
 472                         obj->used = 1;
 473                         mark_object_reachable(obj);
 474                 }
 475         }
 476         obj = lookup_object(nsha1);
 477         if (obj) {
 478                 obj->used = 1;
 479                 mark_object_reachable(obj);
 480         }
 481         return 0;
 482 }
 483
 484 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
 485                               int flag, void *cb_data)
 486 {
 487         for_each_reflog_ent(logname, fsck_handle_reflog_ent, NULL);
 488         return 0;
 489 }
 490
 491 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 492                            int flag, void *cb_data)
 493 {
 494         struct object *obj;
 495
 496         obj = parse_object(oid->hash);
 497         if (!obj) {
 498                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
 499                 errors_found |= ERROR_REACHABLE;
 500                 /* We'll continue with the rest despite the error.. */
 501                 return 0;
 502         }
 503         if (obj->type != OBJ_COMMIT && is_branch(refname))
 504                 error("%s: not a commit", refname);
 505         default_refs++;
 506         obj->used = 1;
 507         mark_object_reachable(obj);
 508
 509         return 0;
 510 }
 511
 512 static void get_default_heads(void)
 513 {
 514         if (head_points_at && !is_null_oid(&head_oid))
 515                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
 516         for_each_rawref(fsck_handle_ref, NULL);
 517         if (include_reflogs)
 518                 for_each_reflog(fsck_handle_reflog, NULL);
 519
 520         /*
 521          * Not having any default heads isn't really fatal, but
 522          * it does mean that "--unreachable" no longer makes any
 523          * sense (since in this case everything will obviously
 524          * be unreachable by definition.
 525          *
 526          * Showing dangling objects is valid, though (as those
 527          * dangling objects are likely lost heads).
 528          *
 529          * So we just print a warning about it, and clear the
 530          * "show_unreachable" flag.
 531          */
 532         if (!default_refs) {
 533                 fprintf(stderr, "notice: No default references\n");
 534                 show_unreachable = 0;
 535         }
 536 }
 537
 538 static void fsck_object_dir(const char *path)
 539 {
 540         int i;
 541         struct progress *progress = NULL;
 542
 543         if (verbose)
 544                 fprintf(stderr, "Checking object directory\n");
 545
 546         if (show_progress)
 547                 progress = start_progress(_("Checking object directories"), 256);
 548         for (i = 0; i < 256; i++) {
 549                 static char dir[4096];
 550                 sprintf(dir, "%s/%02x", path, i);
 551                 fsck_dir(i, dir);
 552                 display_progress(progress, i+1);
 553         }
 554         stop_progress(&progress);
 555         fsck_sha1_list();
 556 }
 557
 558 static int fsck_head_link(void)
 559 {
 560         int flag;
 561         int null_is_error = 0;
 562
 563         if (verbose)
 564                 fprintf(stderr, "Checking HEAD link\n");
 565
 566         head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, &flag);
 567         if (!head_points_at)
 568                 return error("Invalid HEAD");
 569         if (!strcmp(head_points_at, "HEAD"))
 570                 /* detached HEAD */
 571                 null_is_error = 1;
 572         else if (!starts_with(head_points_at, "refs/heads/"))
 573                 return error("HEAD points to something strange (%s)",
 574                              head_points_at);
 575         if (is_null_oid(&head_oid)) {
 576                 if (null_is_error)
 577                         return error("HEAD: detached HEAD points at nothing");
 578                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
 579                         head_points_at + 11);
 580         }
 581         return 0;
 582 }
 583
 584 static int fsck_cache_tree(struct cache_tree *it)
 585 {
 586         int i;
 587         int err = 0;
 588
 589         if (verbose)
 590                 fprintf(stderr, "Checking cache tree\n");
 591
 592         if (0 <= it->entry_count) {
 593                 struct object *obj = parse_object(it->sha1);
 594                 if (!obj) {
 595                         error("%s: invalid sha1 pointer in cache-tree",
 596                               sha1_to_hex(it->sha1));
 597                         return 1;
 598                 }
 599                 obj->used = 1;
 600                 mark_object_reachable(obj);
 601                 if (obj->type != OBJ_TREE)
 602                         err |= objerror(obj, "non-tree in cache-tree");
 603         }
 604         for (i = 0; i < it->subtree_nr; i++)
 605                 err |= fsck_cache_tree(it->down[i]->cache_tree);
 606         return err;
 607 }
 608
 609 static char const * const fsck_usage[] = {
 610         N_("git fsck [<options>] [<object>...]"),
 611         NULL
 612 };
 613
 614 static struct option fsck_opts[] = {
 615         OPT__VERBOSE(&verbose, N_("be verbose")),
 616         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
 617         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
 618         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
 619         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
 620         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
 621         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
 622         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
 623         OPT_BOOL(0, "connectivity-only", &connectivity_only, N_("check only connectivity")),
 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         fsck_walk_options.walk = mark_object;
 642         fsck_obj_options.walk = mark_used;
 643         fsck_obj_options.error_func = fsck_error_func;
 644         if (check_strict)
 645                 fsck_obj_options.strict = 1;
 646
 647         if (show_progress == -1)
 648                 show_progress = isatty(2);
 649         if (verbose)
 650                 show_progress = 0;
 651
 652         if (write_lost_and_found) {
 653                 check_full = 1;
 654                 include_reflogs = 0;
 655         }
 656
 657         git_config(fsck_config, NULL);
 658
 659         fsck_head_link();
 660         if (!connectivity_only)
 661                 fsck_object_dir(get_object_directory());
 662
 663         prepare_alt_odb();
 664         for (alt = alt_odb_list; alt; alt = alt->next) {
 665                 char namebuf[PATH_MAX];
 666                 int namelen = alt->name - alt->base;
 667                 memcpy(namebuf, alt->base, namelen);
 668                 namebuf[namelen - 1] = 0;
 669                 fsck_object_dir(namebuf);
 670         }
 671
 672         if (check_full) {
 673                 struct packed_git *p;
 674                 uint32_t total = 0, count = 0;
 675                 struct progress *progress = NULL;
 676
 677                 prepare_packed_git();
 678
 679                 if (show_progress) {
 680                         for (p = packed_git; p; p = p->next) {
 681                                 if (open_pack_index(p))
 682                                         continue;
 683                                 total += p->num_objects;
 684                         }
 685
 686                         progress = start_progress(_("Checking objects"), total);
 687                 }
 688                 for (p = packed_git; p; p = p->next) {
 689                         /* verify gives error messages itself */
 690                         if (verify_pack(p, fsck_obj_buffer,
 691                                         progress, count))
 692                                 errors_found |= ERROR_PACK;
 693                         count += p->num_objects;
 694                 }
 695                 stop_progress(&progress);
 696         }
 697
 698         heads = 0;
 699         for (i = 0; i < argc; i++) {
 700                 const char *arg = argv[i];
 701                 unsigned char sha1[20];
 702                 if (!get_sha1(arg, sha1)) {
 703                         struct object *obj = lookup_object(sha1);
 704
 705                         /* Error is printed by lookup_object(). */
 706                         if (!obj)
 707                                 continue;
 708
 709                         obj->used = 1;
 710                         mark_object_reachable(obj);
 711                         heads++;
 712                         continue;
 713                 }
 714                 error("invalid parameter: expected sha1, got '%s'", arg);
 715         }
 716
 717         /*
 718          * If we've not been given any explicit head information, do the
 719          * default ones from .git/refs. We also consider the index file
 720          * in this case (ie this implies --cache).
 721          */
 722         if (!heads) {
 723                 get_default_heads();
 724                 keep_cache_objects = 1;
 725         }
 726
 727         if (keep_cache_objects) {
 728                 read_cache();
 729                 for (i = 0; i < active_nr; i++) {
 730                         unsigned int mode;
 731                         struct blob *blob;
 732                         struct object *obj;
 733
 734                         mode = active_cache[i]->ce_mode;
 735                         if (S_ISGITLINK(mode))
 736                                 continue;
 737                         blob = lookup_blob(active_cache[i]->sha1);
 738                         if (!blob)
 739                                 continue;
 740                         obj = &blob->object;
 741                         obj->used = 1;
 742                         mark_object_reachable(obj);
 743                 }
 744                 if (active_cache_tree)
 745                         fsck_cache_tree(active_cache_tree);
 746         }
 747
 748         check_connectivity();
 749         return errors_found;
 750 }