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status: add optional stash count information
[git-core/git.git] / 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 #include "decorate.h"
17
18 #define REACHABLE 0x0001
19 #define SEEN      0x0002
20 #define HAS_OBJ   0x0004
21
22 static int show_root;
23 static int show_tags;
24 static int show_unreachable;
25 static int include_reflogs = 1;
26 static int check_full = 1;
27 static int connectivity_only;
28 static int check_strict;
29 static int keep_cache_objects;
30 static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
31 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
32 static struct object_id head_oid;
33 static const char *head_points_at;
34 static int errors_found;
35 static int write_lost_and_found;
36 static int verbose;
37 static int show_progress = -1;
38 static int show_dangling = 1;
39 static int name_objects;
40 #define ERROR_OBJECT 01
41 #define ERROR_REACHABLE 02
42 #define ERROR_PACK 04
43 #define ERROR_REFS 010
44
45 static const char *describe_object(struct object *obj)
46 {
47         static struct strbuf buf = STRBUF_INIT;
48         char *name = name_objects ?
49                 lookup_decoration(fsck_walk_options.object_names, obj) : NULL;
50
51         strbuf_reset(&buf);
52         strbuf_addstr(&buf, oid_to_hex(&obj->oid));
53         if (name)
54                 strbuf_addf(&buf, " (%s)", name);
55
56         return buf.buf;
57 }
58
59 static const char *printable_type(struct object *obj)
60 {
61         const char *ret;
62
63         if (obj->type == OBJ_NONE) {
64                 enum object_type type = sha1_object_info(obj->oid.hash, NULL);
65                 if (type > 0)
66                         object_as_type(obj, type, 0);
67         }
68
69         ret = typename(obj->type);
70         if (!ret)
71                 ret = "unknown";
72
73         return ret;
74 }
75
76 static int fsck_config(const char *var, const char *value, void *cb)
77 {
78         if (strcmp(var, "fsck.skiplist") == 0) {
79                 const char *path;
80                 struct strbuf sb = STRBUF_INIT;
81
82                 if (git_config_pathname(&path, var, value))
83                         return 1;
84                 strbuf_addf(&sb, "skiplist=%s", path);
85                 free((char *)path);
86                 fsck_set_msg_types(&fsck_obj_options, sb.buf);
87                 strbuf_release(&sb);
88                 return 0;
89         }
90
91         if (skip_prefix(var, "fsck.", &var)) {
92                 fsck_set_msg_type(&fsck_obj_options, var, value);
93                 return 0;
94         }
95
96         return git_default_config(var, value, cb);
97 }
98
99 static void objreport(struct object *obj, const char *msg_type,
100                         const char *err)
101 {
102         fprintf(stderr, "%s in %s %s: %s\n",
103                 msg_type, printable_type(obj), describe_object(obj), err);
104 }
105
106 static int objerror(struct object *obj, const char *err)
107 {
108         errors_found |= ERROR_OBJECT;
109         objreport(obj, "error", err);
110         return -1;
111 }
112
113 static int fsck_error_func(struct fsck_options *o,
114         struct object *obj, int type, const char *message)
115 {
116         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", message);
117         return (type == FSCK_WARN) ? 0 : 1;
118 }
119
120 static struct object_array pending;
121
122 static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
123 {
124         struct object *parent = data;
125
126         /*
127          * The only case data is NULL or type is OBJ_ANY is when
128          * mark_object_reachable() calls us.  All the callers of
129          * that function has non-NULL obj hence ...
130          */
131         if (!obj) {
132                 /* ... these references to parent->fld are safe here */
133                 printf("broken link from %7s %s\n",
134                            printable_type(parent), describe_object(parent));
135                 printf("broken link from %7s %s\n",
136                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
137                 errors_found |= ERROR_REACHABLE;
138                 return 1;
139         }
140
141         if (type != OBJ_ANY && obj->type != type)
142                 /* ... and the reference to parent is safe here */
143                 objerror(parent, "wrong object type in link");
144
145         if (obj->flags & REACHABLE)
146                 return 0;
147         obj->flags |= REACHABLE;
148         if (!(obj->flags & HAS_OBJ)) {
149                 if (parent && !has_object_file(&obj->oid)) {
150                         printf("broken link from %7s %s\n",
151                                  printable_type(parent), describe_object(parent));
152                         printf("              to %7s %s\n",
153                                  printable_type(obj), describe_object(obj));
154                         errors_found |= ERROR_REACHABLE;
155                 }
156                 return 1;
157         }
158
159         add_object_array(obj, NULL, &pending);
160         return 0;
161 }
162
163 static void mark_object_reachable(struct object *obj)
164 {
165         mark_object(obj, OBJ_ANY, NULL, NULL);
166 }
167
168 static int traverse_one_object(struct object *obj)
169 {
170         int result;
171         struct tree *tree = NULL;
172
173         if (obj->type == OBJ_TREE) {
174                 tree = (struct tree *)obj;
175                 if (parse_tree(tree) < 0)
176                         return 1; /* error already displayed */
177         }
178         result = fsck_walk(obj, obj, &fsck_walk_options);
179         if (tree)
180                 free_tree_buffer(tree);
181         return result;
182 }
183
184 static int traverse_reachable(void)
185 {
186         struct progress *progress = NULL;
187         unsigned int nr = 0;
188         int result = 0;
189         if (show_progress)
190                 progress = start_progress_delay(_("Checking connectivity"), 0, 0, 2);
191         while (pending.nr) {
192                 struct object_array_entry *entry;
193                 struct object *obj;
194
195                 entry = pending.objects + --pending.nr;
196                 obj = entry->item;
197                 result |= traverse_one_object(obj);
198                 display_progress(progress, ++nr);
199         }
200         stop_progress(&progress);
201         return !!result;
202 }
203
204 static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
205 {
206         if (!obj)
207                 return 1;
208         obj->used = 1;
209         return 0;
210 }
211
212 /*
213  * Check a single reachable object
214  */
215 static void check_reachable_object(struct object *obj)
216 {
217         /*
218          * We obviously want the object to be parsed,
219          * except if it was in a pack-file and we didn't
220          * do a full fsck
221          */
222         if (!(obj->flags & HAS_OBJ)) {
223                 if (has_sha1_pack(obj->oid.hash))
224                         return; /* it is in pack - forget about it */
225                 printf("missing %s %s\n", printable_type(obj),
226                         describe_object(obj));
227                 errors_found |= ERROR_REACHABLE;
228                 return;
229         }
230 }
231
232 /*
233  * Check a single unreachable object
234  */
235 static void check_unreachable_object(struct object *obj)
236 {
237         /*
238          * Missing unreachable object? Ignore it. It's not like
239          * we miss it (since it can't be reached), nor do we want
240          * to complain about it being unreachable (since it does
241          * not exist).
242          */
243         if (!(obj->flags & HAS_OBJ))
244                 return;
245
246         /*
247          * Unreachable object that exists? Show it if asked to,
248          * since this is something that is prunable.
249          */
250         if (show_unreachable) {
251                 printf("unreachable %s %s\n", printable_type(obj),
252                         describe_object(obj));
253                 return;
254         }
255
256         /*
257          * "!used" means that nothing at all points to it, including
258          * other unreachable objects. In other words, it's the "tip"
259          * of some set of unreachable objects, usually a commit that
260          * got dropped.
261          *
262          * Such starting points are more interesting than some random
263          * set of unreachable objects, so we show them even if the user
264          * hasn't asked for _all_ unreachable objects. If you have
265          * deleted a branch by mistake, this is a prime candidate to
266          * start looking at, for example.
267          */
268         if (!obj->used) {
269                 if (show_dangling)
270                         printf("dangling %s %s\n", printable_type(obj),
271                                describe_object(obj));
272                 if (write_lost_and_found) {
273                         char *filename = git_pathdup("lost-found/%s/%s",
274                                 obj->type == OBJ_COMMIT ? "commit" : "other",
275                                 describe_object(obj));
276                         FILE *f;
277
278                         if (safe_create_leading_directories_const(filename)) {
279                                 error("Could not create lost-found");
280                                 free(filename);
281                                 return;
282                         }
283                         f = xfopen(filename, "w");
284                         if (obj->type == OBJ_BLOB) {
285                                 if (stream_blob_to_fd(fileno(f), &obj->oid, NULL, 1))
286                                         die_errno("Could not write '%s'", filename);
287                         } else
288                                 fprintf(f, "%s\n", describe_object(obj));
289                         if (fclose(f))
290                                 die_errno("Could not finish '%s'",
291                                           filename);
292                         free(filename);
293                 }
294                 return;
295         }
296
297         /*
298          * Otherwise? It's there, it's unreachable, and some other unreachable
299          * object points to it. Ignore it - it's not interesting, and we showed
300          * all the interesting cases above.
301          */
302 }
303
304 static void check_object(struct object *obj)
305 {
306         if (verbose)
307                 fprintf(stderr, "Checking %s\n", describe_object(obj));
308
309         if (obj->flags & REACHABLE)
310                 check_reachable_object(obj);
311         else
312                 check_unreachable_object(obj);
313 }
314
315 static void check_connectivity(void)
316 {
317         int i, max;
318
319         /* Traverse the pending reachable objects */
320         traverse_reachable();
321
322         /* Look up all the requirements, warn about missing objects.. */
323         max = get_max_object_index();
324         if (verbose)
325                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
326
327         for (i = 0; i < max; i++) {
328                 struct object *obj = get_indexed_object(i);
329
330                 if (obj)
331                         check_object(obj);
332         }
333 }
334
335 static int fsck_obj(struct object *obj)
336 {
337         if (obj->flags & SEEN)
338                 return 0;
339         obj->flags |= SEEN;
340
341         if (verbose)
342                 fprintf(stderr, "Checking %s %s\n",
343                         printable_type(obj), describe_object(obj));
344
345         if (fsck_walk(obj, NULL, &fsck_obj_options))
346                 objerror(obj, "broken links");
347         if (fsck_object(obj, NULL, 0, &fsck_obj_options))
348                 return -1;
349
350         if (obj->type == OBJ_TREE) {
351                 struct tree *item = (struct tree *) obj;
352
353                 free_tree_buffer(item);
354         }
355
356         if (obj->type == OBJ_COMMIT) {
357                 struct commit *commit = (struct commit *) obj;
358
359                 free_commit_buffer(commit);
360
361                 if (!commit->parents && show_root)
362                         printf("root %s\n", describe_object(&commit->object));
363         }
364
365         if (obj->type == OBJ_TAG) {
366                 struct tag *tag = (struct tag *) obj;
367
368                 if (show_tags && tag->tagged) {
369                         printf("tagged %s %s", printable_type(tag->tagged),
370                                 describe_object(tag->tagged));
371                         printf(" (%s) in %s\n", tag->tag,
372                                 describe_object(&tag->object));
373                 }
374         }
375
376         return 0;
377 }
378
379 static int fsck_obj_buffer(const struct object_id *oid, enum object_type type,
380                            unsigned long size, void *buffer, int *eaten)
381 {
382         /*
383          * Note, buffer may be NULL if type is OBJ_BLOB. See
384          * verify_packfile(), data_valid variable for details.
385          */
386         struct object *obj;
387         obj = parse_object_buffer(oid, type, size, buffer, eaten);
388         if (!obj) {
389                 errors_found |= ERROR_OBJECT;
390                 return error("%s: object corrupt or missing", oid_to_hex(oid));
391         }
392         obj->flags = HAS_OBJ;
393         return fsck_obj(obj);
394 }
395
396 static int default_refs;
397
398 static void fsck_handle_reflog_oid(const char *refname, struct object_id *oid,
399         timestamp_t timestamp)
400 {
401         struct object *obj;
402
403         if (!is_null_oid(oid)) {
404                 obj = lookup_object(oid->hash);
405                 if (obj && (obj->flags & HAS_OBJ)) {
406                         if (timestamp && name_objects)
407                                 add_decoration(fsck_walk_options.object_names,
408                                         obj,
409                                         xstrfmt("%s@{%"PRItime"}", refname, timestamp));
410                         obj->used = 1;
411                         mark_object_reachable(obj);
412                 } else {
413                         error("%s: invalid reflog entry %s", refname, oid_to_hex(oid));
414                         errors_found |= ERROR_REACHABLE;
415                 }
416         }
417 }
418
419 static int fsck_handle_reflog_ent(struct object_id *ooid, struct object_id *noid,
420                 const char *email, timestamp_t timestamp, int tz,
421                 const char *message, void *cb_data)
422 {
423         const char *refname = cb_data;
424
425         if (verbose)
426                 fprintf(stderr, "Checking reflog %s->%s\n",
427                         oid_to_hex(ooid), oid_to_hex(noid));
428
429         fsck_handle_reflog_oid(refname, ooid, 0);
430         fsck_handle_reflog_oid(refname, noid, timestamp);
431         return 0;
432 }
433
434 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
435                               int flag, void *cb_data)
436 {
437         for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
438         return 0;
439 }
440
441 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
442                            int flag, void *cb_data)
443 {
444         struct object *obj;
445
446         obj = parse_object(oid);
447         if (!obj) {
448                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
449                 errors_found |= ERROR_REACHABLE;
450                 /* We'll continue with the rest despite the error.. */
451                 return 0;
452         }
453         if (obj->type != OBJ_COMMIT && is_branch(refname)) {
454                 error("%s: not a commit", refname);
455                 errors_found |= ERROR_REFS;
456         }
457         default_refs++;
458         obj->used = 1;
459         if (name_objects)
460                 add_decoration(fsck_walk_options.object_names,
461                         obj, xstrdup(refname));
462         mark_object_reachable(obj);
463
464         return 0;
465 }
466
467 static void get_default_heads(void)
468 {
469         if (head_points_at && !is_null_oid(&head_oid))
470                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
471         for_each_rawref(fsck_handle_ref, NULL);
472         if (include_reflogs)
473                 for_each_reflog(fsck_handle_reflog, NULL);
474
475         /*
476          * Not having any default heads isn't really fatal, but
477          * it does mean that "--unreachable" no longer makes any
478          * sense (since in this case everything will obviously
479          * be unreachable by definition.
480          *
481          * Showing dangling objects is valid, though (as those
482          * dangling objects are likely lost heads).
483          *
484          * So we just print a warning about it, and clear the
485          * "show_unreachable" flag.
486          */
487         if (!default_refs) {
488                 fprintf(stderr, "notice: No default references\n");
489                 show_unreachable = 0;
490         }
491 }
492
493 static struct object *parse_loose_object(const struct object_id *oid,
494                                          const char *path)
495 {
496         struct object *obj;
497         void *contents;
498         enum object_type type;
499         unsigned long size;
500         int eaten;
501
502         if (read_loose_object(path, oid->hash, &type, &size, &contents) < 0)
503                 return NULL;
504
505         if (!contents && type != OBJ_BLOB)
506                 die("BUG: read_loose_object streamed a non-blob");
507
508         obj = parse_object_buffer(oid, type, size, contents, &eaten);
509
510         if (!eaten)
511                 free(contents);
512         return obj;
513 }
514
515 static int fsck_loose(const struct object_id *oid, const char *path, void *data)
516 {
517         struct object *obj = parse_loose_object(oid, path);
518
519         if (!obj) {
520                 errors_found |= ERROR_OBJECT;
521                 error("%s: object corrupt or missing: %s",
522                       oid_to_hex(oid), path);
523                 return 0; /* keep checking other objects */
524         }
525
526         obj->flags = HAS_OBJ;
527         if (fsck_obj(obj))
528                 errors_found |= ERROR_OBJECT;
529         return 0;
530 }
531
532 static int fsck_cruft(const char *basename, const char *path, void *data)
533 {
534         if (!starts_with(basename, "tmp_obj_"))
535                 fprintf(stderr, "bad sha1 file: %s\n", path);
536         return 0;
537 }
538
539 static int fsck_subdir(int nr, const char *path, void *progress)
540 {
541         display_progress(progress, nr + 1);
542         return 0;
543 }
544
545 static void fsck_object_dir(const char *path)
546 {
547         struct progress *progress = NULL;
548
549         if (verbose)
550                 fprintf(stderr, "Checking object directory\n");
551
552         if (show_progress)
553                 progress = start_progress(_("Checking object directories"), 256);
554
555         for_each_loose_file_in_objdir(path, fsck_loose, fsck_cruft, fsck_subdir,
556                                       progress);
557         display_progress(progress, 256);
558         stop_progress(&progress);
559 }
560
561 static int fsck_head_link(void)
562 {
563         int null_is_error = 0;
564
565         if (verbose)
566                 fprintf(stderr, "Checking HEAD link\n");
567
568         head_points_at = resolve_ref_unsafe("HEAD", 0, head_oid.hash, NULL);
569         if (!head_points_at) {
570                 errors_found |= ERROR_REFS;
571                 return error("Invalid HEAD");
572         }
573         if (!strcmp(head_points_at, "HEAD"))
574                 /* detached HEAD */
575                 null_is_error = 1;
576         else if (!starts_with(head_points_at, "refs/heads/")) {
577                 errors_found |= ERROR_REFS;
578                 return error("HEAD points to something strange (%s)",
579                              head_points_at);
580         }
581         if (is_null_oid(&head_oid)) {
582                 if (null_is_error) {
583                         errors_found |= ERROR_REFS;
584                         return error("HEAD: detached HEAD points at nothing");
585                 }
586                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
587                         head_points_at + 11);
588         }
589         return 0;
590 }
591
592 static int fsck_cache_tree(struct cache_tree *it)
593 {
594         int i;
595         int err = 0;
596
597         if (verbose)
598                 fprintf(stderr, "Checking cache tree\n");
599
600         if (0 <= it->entry_count) {
601                 struct object *obj = parse_object(&it->oid);
602                 if (!obj) {
603                         error("%s: invalid sha1 pointer in cache-tree",
604                               oid_to_hex(&it->oid));
605                         errors_found |= ERROR_REFS;
606                         return 1;
607                 }
608                 obj->used = 1;
609                 if (name_objects)
610                         add_decoration(fsck_walk_options.object_names,
611                                 obj, xstrdup(":"));
612                 mark_object_reachable(obj);
613                 if (obj->type != OBJ_TREE)
614                         err |= objerror(obj, "non-tree in cache-tree");
615         }
616         for (i = 0; i < it->subtree_nr; i++)
617                 err |= fsck_cache_tree(it->down[i]->cache_tree);
618         return err;
619 }
620
621 static void mark_object_for_connectivity(const struct object_id *oid)
622 {
623         struct object *obj = lookup_unknown_object(oid->hash);
624         obj->flags |= HAS_OBJ;
625 }
626
627 static int mark_loose_for_connectivity(const struct object_id *oid,
628                                        const char *path,
629                                        void *data)
630 {
631         mark_object_for_connectivity(oid);
632         return 0;
633 }
634
635 static int mark_packed_for_connectivity(const struct object_id *oid,
636                                         struct packed_git *pack,
637                                         uint32_t pos,
638                                         void *data)
639 {
640         mark_object_for_connectivity(oid);
641         return 0;
642 }
643
644 static char const * const fsck_usage[] = {
645         N_("git fsck [<options>] [<object>...]"),
646         NULL
647 };
648
649 static struct option fsck_opts[] = {
650         OPT__VERBOSE(&verbose, N_("be verbose")),
651         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
652         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
653         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
654         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
655         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
656         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
657         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
658         OPT_BOOL(0, "connectivity-only", &connectivity_only, N_("check only connectivity")),
659         OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
660         OPT_BOOL(0, "lost-found", &write_lost_and_found,
661                                 N_("write dangling objects in .git/lost-found")),
662         OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
663         OPT_BOOL(0, "name-objects", &name_objects, N_("show verbose names for reachable objects")),
664         OPT_END(),
665 };
666
667 int cmd_fsck(int argc, const char **argv, const char *prefix)
668 {
669         int i, heads;
670         struct alternate_object_database *alt;
671
672         errors_found = 0;
673         check_replace_refs = 0;
674
675         argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);
676
677         fsck_walk_options.walk = mark_object;
678         fsck_obj_options.walk = mark_used;
679         fsck_obj_options.error_func = fsck_error_func;
680         if (check_strict)
681                 fsck_obj_options.strict = 1;
682
683         if (show_progress == -1)
684                 show_progress = isatty(2);
685         if (verbose)
686                 show_progress = 0;
687
688         if (write_lost_and_found) {
689                 check_full = 1;
690                 include_reflogs = 0;
691         }
692
693         if (name_objects)
694                 fsck_walk_options.object_names =
695                         xcalloc(1, sizeof(struct decoration));
696
697         git_config(fsck_config, NULL);
698
699         fsck_head_link();
700         if (connectivity_only) {
701                 for_each_loose_object(mark_loose_for_connectivity, NULL, 0);
702                 for_each_packed_object(mark_packed_for_connectivity, NULL, 0);
703         } else {
704                 fsck_object_dir(get_object_directory());
705
706                 prepare_alt_odb();
707                 for (alt = alt_odb_list; alt; alt = alt->next)
708                         fsck_object_dir(alt->path);
709
710                 if (check_full) {
711                         struct packed_git *p;
712                         uint32_t total = 0, count = 0;
713                         struct progress *progress = NULL;
714
715                         prepare_packed_git();
716
717                         if (show_progress) {
718                                 for (p = packed_git; p; p = p->next) {
719                                         if (open_pack_index(p))
720                                                 continue;
721                                         total += p->num_objects;
722                                 }
723
724                                 progress = start_progress(_("Checking objects"), total);
725                         }
726                         for (p = packed_git; p; p = p->next) {
727                                 /* verify gives error messages itself */
728                                 if (verify_pack(p, fsck_obj_buffer,
729                                                 progress, count))
730                                         errors_found |= ERROR_PACK;
731                                 count += p->num_objects;
732                         }
733                         stop_progress(&progress);
734                 }
735         }
736
737         heads = 0;
738         for (i = 0; i < argc; i++) {
739                 const char *arg = argv[i];
740                 unsigned char sha1[20];
741                 if (!get_sha1(arg, sha1)) {
742                         struct object *obj = lookup_object(sha1);
743
744                         if (!obj || !(obj->flags & HAS_OBJ)) {
745                                 error("%s: object missing", sha1_to_hex(sha1));
746                                 errors_found |= ERROR_OBJECT;
747                                 continue;
748                         }
749
750                         obj->used = 1;
751                         if (name_objects)
752                                 add_decoration(fsck_walk_options.object_names,
753                                         obj, xstrdup(arg));
754                         mark_object_reachable(obj);
755                         heads++;
756                         continue;
757                 }
758                 error("invalid parameter: expected sha1, got '%s'", arg);
759                 errors_found |= ERROR_OBJECT;
760         }
761
762         /*
763          * If we've not been given any explicit head information, do the
764          * default ones from .git/refs. We also consider the index file
765          * in this case (ie this implies --cache).
766          */
767         if (!argc) {
768                 get_default_heads();
769                 keep_cache_objects = 1;
770         }
771
772         if (keep_cache_objects) {
773                 verify_index_checksum = 1;
774                 read_cache();
775                 for (i = 0; i < active_nr; i++) {
776                         unsigned int mode;
777                         struct blob *blob;
778                         struct object *obj;
779
780                         mode = active_cache[i]->ce_mode;
781                         if (S_ISGITLINK(mode))
782                                 continue;
783                         blob = lookup_blob(&active_cache[i]->oid);
784                         if (!blob)
785                                 continue;
786                         obj = &blob->object;
787                         obj->used = 1;
788                         if (name_objects)
789                                 add_decoration(fsck_walk_options.object_names,
790                                         obj,
791                                         xstrfmt(":%s", active_cache[i]->name));
792                         mark_object_reachable(obj);
793                 }
794                 if (active_cache_tree)
795                         fsck_cache_tree(active_cache_tree);
796         }
797
798         check_connectivity();
799         return errors_found;
800 }