fsck: support refs pointing to promisor objects
[git] / builtin / fsck.c
1 #include "builtin.h"
2 #include "cache.h"
3 #include "config.h"
4 #include "commit.h"
5 #include "tree.h"
6 #include "blob.h"
7 #include "tag.h"
8 #include "refs.h"
9 #include "pack.h"
10 #include "cache-tree.h"
11 #include "tree-walk.h"
12 #include "fsck.h"
13 #include "parse-options.h"
14 #include "dir.h"
15 #include "progress.h"
16 #include "streaming.h"
17 #include "decorate.h"
18 #include "packfile.h"
19
20 #define REACHABLE 0x0001
21 #define SEEN      0x0002
22 #define HAS_OBJ   0x0004
23 /* This flag is set if something points to this object. */
24 #define USED      0x0008
25
26 static int show_root;
27 static int show_tags;
28 static int show_unreachable;
29 static int include_reflogs = 1;
30 static int check_full = 1;
31 static int connectivity_only;
32 static int check_strict;
33 static int keep_cache_objects;
34 static struct fsck_options fsck_walk_options = FSCK_OPTIONS_DEFAULT;
35 static struct fsck_options fsck_obj_options = FSCK_OPTIONS_DEFAULT;
36 static struct object_id head_oid;
37 static const char *head_points_at;
38 static int errors_found;
39 static int write_lost_and_found;
40 static int verbose;
41 static int show_progress = -1;
42 static int show_dangling = 1;
43 static int name_objects;
44 #define ERROR_OBJECT 01
45 #define ERROR_REACHABLE 02
46 #define ERROR_PACK 04
47 #define ERROR_REFS 010
48
49 static const char *describe_object(struct object *obj)
50 {
51         static struct strbuf buf = STRBUF_INIT;
52         char *name = name_objects ?
53                 lookup_decoration(fsck_walk_options.object_names, obj) : NULL;
54
55         strbuf_reset(&buf);
56         strbuf_addstr(&buf, oid_to_hex(&obj->oid));
57         if (name)
58                 strbuf_addf(&buf, " (%s)", name);
59
60         return buf.buf;
61 }
62
63 static const char *printable_type(struct object *obj)
64 {
65         const char *ret;
66
67         if (obj->type == OBJ_NONE) {
68                 enum object_type type = sha1_object_info(obj->oid.hash, NULL);
69                 if (type > 0)
70                         object_as_type(obj, type, 0);
71         }
72
73         ret = typename(obj->type);
74         if (!ret)
75                 ret = "unknown";
76
77         return ret;
78 }
79
80 static int fsck_config(const char *var, const char *value, void *cb)
81 {
82         if (strcmp(var, "fsck.skiplist") == 0) {
83                 const char *path;
84                 struct strbuf sb = STRBUF_INIT;
85
86                 if (git_config_pathname(&path, var, value))
87                         return 1;
88                 strbuf_addf(&sb, "skiplist=%s", path);
89                 free((char *)path);
90                 fsck_set_msg_types(&fsck_obj_options, sb.buf);
91                 strbuf_release(&sb);
92                 return 0;
93         }
94
95         if (skip_prefix(var, "fsck.", &var)) {
96                 fsck_set_msg_type(&fsck_obj_options, var, value);
97                 return 0;
98         }
99
100         return git_default_config(var, value, cb);
101 }
102
103 static void objreport(struct object *obj, const char *msg_type,
104                         const char *err)
105 {
106         fprintf(stderr, "%s in %s %s: %s\n",
107                 msg_type, printable_type(obj), describe_object(obj), err);
108 }
109
110 static int objerror(struct object *obj, const char *err)
111 {
112         errors_found |= ERROR_OBJECT;
113         objreport(obj, "error", err);
114         return -1;
115 }
116
117 static int fsck_error_func(struct fsck_options *o,
118         struct object *obj, int type, const char *message)
119 {
120         objreport(obj, (type == FSCK_WARN) ? "warning" : "error", message);
121         return (type == FSCK_WARN) ? 0 : 1;
122 }
123
124 static struct object_array pending;
125
126 static int mark_object(struct object *obj, int type, void *data, struct fsck_options *options)
127 {
128         struct object *parent = data;
129
130         /*
131          * The only case data is NULL or type is OBJ_ANY is when
132          * mark_object_reachable() calls us.  All the callers of
133          * that function has non-NULL obj hence ...
134          */
135         if (!obj) {
136                 /* ... these references to parent->fld are safe here */
137                 printf("broken link from %7s %s\n",
138                            printable_type(parent), describe_object(parent));
139                 printf("broken link from %7s %s\n",
140                            (type == OBJ_ANY ? "unknown" : typename(type)), "unknown");
141                 errors_found |= ERROR_REACHABLE;
142                 return 1;
143         }
144
145         if (type != OBJ_ANY && obj->type != type)
146                 /* ... and the reference to parent is safe here */
147                 objerror(parent, "wrong object type in link");
148
149         if (obj->flags & REACHABLE)
150                 return 0;
151         obj->flags |= REACHABLE;
152         if (!(obj->flags & HAS_OBJ)) {
153                 if (parent && !has_object_file(&obj->oid)) {
154                         printf("broken link from %7s %s\n",
155                                  printable_type(parent), describe_object(parent));
156                         printf("              to %7s %s\n",
157                                  printable_type(obj), describe_object(obj));
158                         errors_found |= ERROR_REACHABLE;
159                 }
160                 return 1;
161         }
162
163         add_object_array(obj, NULL, &pending);
164         return 0;
165 }
166
167 static void mark_object_reachable(struct object *obj)
168 {
169         mark_object(obj, OBJ_ANY, NULL, NULL);
170 }
171
172 static int traverse_one_object(struct object *obj)
173 {
174         return fsck_walk(obj, obj, &fsck_walk_options);
175 }
176
177 static int traverse_reachable(void)
178 {
179         struct progress *progress = NULL;
180         unsigned int nr = 0;
181         int result = 0;
182         if (show_progress)
183                 progress = start_delayed_progress(_("Checking connectivity"), 0);
184         while (pending.nr) {
185                 result |= traverse_one_object(object_array_pop(&pending));
186                 display_progress(progress, ++nr);
187         }
188         stop_progress(&progress);
189         return !!result;
190 }
191
192 static int mark_used(struct object *obj, int type, void *data, struct fsck_options *options)
193 {
194         if (!obj)
195                 return 1;
196         obj->flags |= USED;
197         return 0;
198 }
199
200 /*
201  * Check a single reachable object
202  */
203 static void check_reachable_object(struct object *obj)
204 {
205         /*
206          * We obviously want the object to be parsed,
207          * except if it was in a pack-file and we didn't
208          * do a full fsck
209          */
210         if (!(obj->flags & HAS_OBJ)) {
211                 if (has_sha1_pack(obj->oid.hash))
212                         return; /* it is in pack - forget about it */
213                 printf("missing %s %s\n", printable_type(obj),
214                         describe_object(obj));
215                 errors_found |= ERROR_REACHABLE;
216                 return;
217         }
218 }
219
220 /*
221  * Check a single unreachable object
222  */
223 static void check_unreachable_object(struct object *obj)
224 {
225         /*
226          * Missing unreachable object? Ignore it. It's not like
227          * we miss it (since it can't be reached), nor do we want
228          * to complain about it being unreachable (since it does
229          * not exist).
230          */
231         if (!(obj->flags & HAS_OBJ))
232                 return;
233
234         /*
235          * Unreachable object that exists? Show it if asked to,
236          * since this is something that is prunable.
237          */
238         if (show_unreachable) {
239                 printf("unreachable %s %s\n", printable_type(obj),
240                         describe_object(obj));
241                 return;
242         }
243
244         /*
245          * "!USED" means that nothing at all points to it, including
246          * other unreachable objects. In other words, it's the "tip"
247          * of some set of unreachable objects, usually a commit that
248          * got dropped.
249          *
250          * Such starting points are more interesting than some random
251          * set of unreachable objects, so we show them even if the user
252          * hasn't asked for _all_ unreachable objects. If you have
253          * deleted a branch by mistake, this is a prime candidate to
254          * start looking at, for example.
255          */
256         if (!(obj->flags & USED)) {
257                 if (show_dangling)
258                         printf("dangling %s %s\n", printable_type(obj),
259                                describe_object(obj));
260                 if (write_lost_and_found) {
261                         char *filename = git_pathdup("lost-found/%s/%s",
262                                 obj->type == OBJ_COMMIT ? "commit" : "other",
263                                 describe_object(obj));
264                         FILE *f;
265
266                         if (safe_create_leading_directories_const(filename)) {
267                                 error("Could not create lost-found");
268                                 free(filename);
269                                 return;
270                         }
271                         f = xfopen(filename, "w");
272                         if (obj->type == OBJ_BLOB) {
273                                 if (stream_blob_to_fd(fileno(f), &obj->oid, NULL, 1))
274                                         die_errno("Could not write '%s'", filename);
275                         } else
276                                 fprintf(f, "%s\n", describe_object(obj));
277                         if (fclose(f))
278                                 die_errno("Could not finish '%s'",
279                                           filename);
280                         free(filename);
281                 }
282                 return;
283         }
284
285         /*
286          * Otherwise? It's there, it's unreachable, and some other unreachable
287          * object points to it. Ignore it - it's not interesting, and we showed
288          * all the interesting cases above.
289          */
290 }
291
292 static void check_object(struct object *obj)
293 {
294         if (verbose)
295                 fprintf(stderr, "Checking %s\n", describe_object(obj));
296
297         if (obj->flags & REACHABLE)
298                 check_reachable_object(obj);
299         else
300                 check_unreachable_object(obj);
301 }
302
303 static void check_connectivity(void)
304 {
305         int i, max;
306
307         /* Traverse the pending reachable objects */
308         traverse_reachable();
309
310         /* Look up all the requirements, warn about missing objects.. */
311         max = get_max_object_index();
312         if (verbose)
313                 fprintf(stderr, "Checking connectivity (%d objects)\n", max);
314
315         for (i = 0; i < max; i++) {
316                 struct object *obj = get_indexed_object(i);
317
318                 if (obj)
319                         check_object(obj);
320         }
321 }
322
323 static int fsck_obj(struct object *obj)
324 {
325         int err;
326
327         if (obj->flags & SEEN)
328                 return 0;
329         obj->flags |= SEEN;
330
331         if (verbose)
332                 fprintf(stderr, "Checking %s %s\n",
333                         printable_type(obj), describe_object(obj));
334
335         if (fsck_walk(obj, NULL, &fsck_obj_options))
336                 objerror(obj, "broken links");
337         err = fsck_object(obj, NULL, 0, &fsck_obj_options);
338         if (err)
339                 goto out;
340
341         if (obj->type == OBJ_COMMIT) {
342                 struct commit *commit = (struct commit *) obj;
343
344                 if (!commit->parents && show_root)
345                         printf("root %s\n", describe_object(&commit->object));
346         }
347
348         if (obj->type == OBJ_TAG) {
349                 struct tag *tag = (struct tag *) obj;
350
351                 if (show_tags && tag->tagged) {
352                         printf("tagged %s %s", printable_type(tag->tagged),
353                                 describe_object(tag->tagged));
354                         printf(" (%s) in %s\n", tag->tag,
355                                 describe_object(&tag->object));
356                 }
357         }
358
359 out:
360         if (obj->type == OBJ_TREE)
361                 free_tree_buffer((struct tree *)obj);
362         if (obj->type == OBJ_COMMIT)
363                 free_commit_buffer((struct commit *)obj);
364         return err;
365 }
366
367 static int fsck_obj_buffer(const struct object_id *oid, enum object_type type,
368                            unsigned long size, void *buffer, int *eaten)
369 {
370         /*
371          * Note, buffer may be NULL if type is OBJ_BLOB. See
372          * verify_packfile(), data_valid variable for details.
373          */
374         struct object *obj;
375         obj = parse_object_buffer(oid, type, size, buffer, eaten);
376         if (!obj) {
377                 errors_found |= ERROR_OBJECT;
378                 return error("%s: object corrupt or missing", oid_to_hex(oid));
379         }
380         obj->flags &= ~(REACHABLE | SEEN);
381         obj->flags |= HAS_OBJ;
382         return fsck_obj(obj);
383 }
384
385 static int default_refs;
386
387 static void fsck_handle_reflog_oid(const char *refname, struct object_id *oid,
388         timestamp_t timestamp)
389 {
390         struct object *obj;
391
392         if (!is_null_oid(oid)) {
393                 obj = lookup_object(oid->hash);
394                 if (obj && (obj->flags & HAS_OBJ)) {
395                         if (timestamp && name_objects)
396                                 add_decoration(fsck_walk_options.object_names,
397                                         obj,
398                                         xstrfmt("%s@{%"PRItime"}", refname, timestamp));
399                         obj->flags |= USED;
400                         mark_object_reachable(obj);
401                 } else if (!is_promisor_object(oid)) {
402                         error("%s: invalid reflog entry %s", refname, oid_to_hex(oid));
403                         errors_found |= ERROR_REACHABLE;
404                 }
405         }
406 }
407
408 static int fsck_handle_reflog_ent(struct object_id *ooid, struct object_id *noid,
409                 const char *email, timestamp_t timestamp, int tz,
410                 const char *message, void *cb_data)
411 {
412         const char *refname = cb_data;
413
414         if (verbose)
415                 fprintf(stderr, "Checking reflog %s->%s\n",
416                         oid_to_hex(ooid), oid_to_hex(noid));
417
418         fsck_handle_reflog_oid(refname, ooid, 0);
419         fsck_handle_reflog_oid(refname, noid, timestamp);
420         return 0;
421 }
422
423 static int fsck_handle_reflog(const char *logname, const struct object_id *oid,
424                               int flag, void *cb_data)
425 {
426         for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
427         return 0;
428 }
429
430 static int fsck_handle_ref(const char *refname, const struct object_id *oid,
431                            int flag, void *cb_data)
432 {
433         struct object *obj;
434
435         obj = parse_object(oid);
436         if (!obj) {
437                 if (is_promisor_object(oid)) {
438                         /*
439                          * Increment default_refs anyway, because this is a
440                          * valid ref.
441                          */
442                          default_refs++;
443                          return 0;
444                 }
445                 error("%s: invalid sha1 pointer %s", refname, oid_to_hex(oid));
446                 errors_found |= ERROR_REACHABLE;
447                 /* We'll continue with the rest despite the error.. */
448                 return 0;
449         }
450         if (obj->type != OBJ_COMMIT && is_branch(refname)) {
451                 error("%s: not a commit", refname);
452                 errors_found |= ERROR_REFS;
453         }
454         default_refs++;
455         obj->flags |= USED;
456         if (name_objects)
457                 add_decoration(fsck_walk_options.object_names,
458                         obj, xstrdup(refname));
459         mark_object_reachable(obj);
460
461         return 0;
462 }
463
464 static void get_default_heads(void)
465 {
466         if (head_points_at && !is_null_oid(&head_oid))
467                 fsck_handle_ref("HEAD", &head_oid, 0, NULL);
468         for_each_rawref(fsck_handle_ref, NULL);
469         if (include_reflogs)
470                 for_each_reflog(fsck_handle_reflog, NULL);
471
472         /*
473          * Not having any default heads isn't really fatal, but
474          * it does mean that "--unreachable" no longer makes any
475          * sense (since in this case everything will obviously
476          * be unreachable by definition.
477          *
478          * Showing dangling objects is valid, though (as those
479          * dangling objects are likely lost heads).
480          *
481          * So we just print a warning about it, and clear the
482          * "show_unreachable" flag.
483          */
484         if (!default_refs) {
485                 fprintf(stderr, "notice: No default references\n");
486                 show_unreachable = 0;
487         }
488 }
489
490 static struct object *parse_loose_object(const struct object_id *oid,
491                                          const char *path)
492 {
493         struct object *obj;
494         void *contents;
495         enum object_type type;
496         unsigned long size;
497         int eaten;
498
499         if (read_loose_object(path, oid->hash, &type, &size, &contents) < 0)
500                 return NULL;
501
502         if (!contents && type != OBJ_BLOB)
503                 die("BUG: read_loose_object streamed a non-blob");
504
505         obj = parse_object_buffer(oid, type, size, contents, &eaten);
506
507         if (!eaten)
508                 free(contents);
509         return obj;
510 }
511
512 static int fsck_loose(const struct object_id *oid, const char *path, void *data)
513 {
514         struct object *obj = parse_loose_object(oid, path);
515
516         if (!obj) {
517                 errors_found |= ERROR_OBJECT;
518                 error("%s: object corrupt or missing: %s",
519                       oid_to_hex(oid), path);
520                 return 0; /* keep checking other objects */
521         }
522
523         obj->flags &= ~(REACHABLE | SEEN);
524         obj->flags |= HAS_OBJ;
525         if (fsck_obj(obj))
526                 errors_found |= ERROR_OBJECT;
527         return 0;
528 }
529
530 static int fsck_cruft(const char *basename, const char *path, void *data)
531 {
532         if (!starts_with(basename, "tmp_obj_"))
533                 fprintf(stderr, "bad sha1 file: %s\n", path);
534         return 0;
535 }
536
537 static int fsck_subdir(unsigned int nr, const char *path, void *progress)
538 {
539         display_progress(progress, nr + 1);
540         return 0;
541 }
542
543 static void fsck_object_dir(const char *path)
544 {
545         struct progress *progress = NULL;
546
547         if (verbose)
548                 fprintf(stderr, "Checking object directory\n");
549
550         if (show_progress)
551                 progress = start_progress(_("Checking object directories"), 256);
552
553         for_each_loose_file_in_objdir(path, fsck_loose, fsck_cruft, fsck_subdir,
554                                       progress);
555         display_progress(progress, 256);
556         stop_progress(&progress);
557 }
558
559 static int fsck_head_link(void)
560 {
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, NULL);
567         if (!head_points_at) {
568                 errors_found |= ERROR_REFS;
569                 return error("Invalid HEAD");
570         }
571         if (!strcmp(head_points_at, "HEAD"))
572                 /* detached HEAD */
573                 null_is_error = 1;
574         else if (!starts_with(head_points_at, "refs/heads/")) {
575                 errors_found |= ERROR_REFS;
576                 return error("HEAD points to something strange (%s)",
577                              head_points_at);
578         }
579         if (is_null_oid(&head_oid)) {
580                 if (null_is_error) {
581                         errors_found |= ERROR_REFS;
582                         return error("HEAD: detached HEAD points at nothing");
583                 }
584                 fprintf(stderr, "notice: HEAD points to an unborn branch (%s)\n",
585                         head_points_at + 11);
586         }
587         return 0;
588 }
589
590 static int fsck_cache_tree(struct cache_tree *it)
591 {
592         int i;
593         int err = 0;
594
595         if (verbose)
596                 fprintf(stderr, "Checking cache tree\n");
597
598         if (0 <= it->entry_count) {
599                 struct object *obj = parse_object(&it->oid);
600                 if (!obj) {
601                         error("%s: invalid sha1 pointer in cache-tree",
602                               oid_to_hex(&it->oid));
603                         errors_found |= ERROR_REFS;
604                         return 1;
605                 }
606                 obj->flags |= USED;
607                 if (name_objects)
608                         add_decoration(fsck_walk_options.object_names,
609                                 obj, xstrdup(":"));
610                 mark_object_reachable(obj);
611                 if (obj->type != OBJ_TREE)
612                         err |= objerror(obj, "non-tree in cache-tree");
613         }
614         for (i = 0; i < it->subtree_nr; i++)
615                 err |= fsck_cache_tree(it->down[i]->cache_tree);
616         return err;
617 }
618
619 static void mark_object_for_connectivity(const struct object_id *oid)
620 {
621         struct object *obj = lookup_unknown_object(oid->hash);
622         obj->flags |= HAS_OBJ;
623 }
624
625 static int mark_loose_for_connectivity(const struct object_id *oid,
626                                        const char *path,
627                                        void *data)
628 {
629         mark_object_for_connectivity(oid);
630         return 0;
631 }
632
633 static int mark_packed_for_connectivity(const struct object_id *oid,
634                                         struct packed_git *pack,
635                                         uint32_t pos,
636                                         void *data)
637 {
638         mark_object_for_connectivity(oid);
639         return 0;
640 }
641
642 static char const * const fsck_usage[] = {
643         N_("git fsck [<options>] [<object>...]"),
644         NULL
645 };
646
647 static struct option fsck_opts[] = {
648         OPT__VERBOSE(&verbose, N_("be verbose")),
649         OPT_BOOL(0, "unreachable", &show_unreachable, N_("show unreachable objects")),
650         OPT_BOOL(0, "dangling", &show_dangling, N_("show dangling objects")),
651         OPT_BOOL(0, "tags", &show_tags, N_("report tags")),
652         OPT_BOOL(0, "root", &show_root, N_("report root nodes")),
653         OPT_BOOL(0, "cache", &keep_cache_objects, N_("make index objects head nodes")),
654         OPT_BOOL(0, "reflogs", &include_reflogs, N_("make reflogs head nodes (default)")),
655         OPT_BOOL(0, "full", &check_full, N_("also consider packs and alternate objects")),
656         OPT_BOOL(0, "connectivity-only", &connectivity_only, N_("check only connectivity")),
657         OPT_BOOL(0, "strict", &check_strict, N_("enable more strict checking")),
658         OPT_BOOL(0, "lost-found", &write_lost_and_found,
659                                 N_("write dangling objects in .git/lost-found")),
660         OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
661         OPT_BOOL(0, "name-objects", &name_objects, N_("show verbose names for reachable objects")),
662         OPT_END(),
663 };
664
665 int cmd_fsck(int argc, const char **argv, const char *prefix)
666 {
667         int i;
668         struct alternate_object_database *alt;
669
670         errors_found = 0;
671         check_replace_refs = 0;
672
673         argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0);
674
675         fsck_walk_options.walk = mark_object;
676         fsck_obj_options.walk = mark_used;
677         fsck_obj_options.error_func = fsck_error_func;
678         if (check_strict)
679                 fsck_obj_options.strict = 1;
680
681         if (show_progress == -1)
682                 show_progress = isatty(2);
683         if (verbose)
684                 show_progress = 0;
685
686         if (write_lost_and_found) {
687                 check_full = 1;
688                 include_reflogs = 0;
689         }
690
691         if (name_objects)
692                 fsck_walk_options.object_names =
693                         xcalloc(1, sizeof(struct decoration));
694
695         git_config(fsck_config, NULL);
696
697         fsck_head_link();
698         if (connectivity_only) {
699                 for_each_loose_object(mark_loose_for_connectivity, NULL, 0);
700                 for_each_packed_object(mark_packed_for_connectivity, NULL, 0);
701         } else {
702                 fsck_object_dir(get_object_directory());
703
704                 prepare_alt_odb();
705                 for (alt = alt_odb_list; alt; alt = alt->next)
706                         fsck_object_dir(alt->path);
707
708                 if (check_full) {
709                         struct packed_git *p;
710                         uint32_t total = 0, count = 0;
711                         struct progress *progress = NULL;
712
713                         prepare_packed_git();
714
715                         if (show_progress) {
716                                 for (p = packed_git; p; p = p->next) {
717                                         if (open_pack_index(p))
718                                                 continue;
719                                         total += p->num_objects;
720                                 }
721
722                                 progress = start_progress(_("Checking objects"), total);
723                         }
724                         for (p = packed_git; p; p = p->next) {
725                                 /* verify gives error messages itself */
726                                 if (verify_pack(p, fsck_obj_buffer,
727                                                 progress, count))
728                                         errors_found |= ERROR_PACK;
729                                 count += p->num_objects;
730                         }
731                         stop_progress(&progress);
732                 }
733         }
734
735         for (i = 0; i < argc; i++) {
736                 const char *arg = argv[i];
737                 struct object_id oid;
738                 if (!get_oid(arg, &oid)) {
739                         struct object *obj = lookup_object(oid.hash);
740
741                         if (!obj || !(obj->flags & HAS_OBJ)) {
742                                 error("%s: object missing", oid_to_hex(&oid));
743                                 errors_found |= ERROR_OBJECT;
744                                 continue;
745                         }
746
747                         obj->flags |= USED;
748                         if (name_objects)
749                                 add_decoration(fsck_walk_options.object_names,
750                                         obj, xstrdup(arg));
751                         mark_object_reachable(obj);
752                         continue;
753                 }
754                 error("invalid parameter: expected sha1, got '%s'", arg);
755                 errors_found |= ERROR_OBJECT;
756         }
757
758         /*
759          * If we've not been given any explicit head information, do the
760          * default ones from .git/refs. We also consider the index file
761          * in this case (ie this implies --cache).
762          */
763         if (!argc) {
764                 get_default_heads();
765                 keep_cache_objects = 1;
766         }
767
768         if (keep_cache_objects) {
769                 verify_index_checksum = 1;
770                 read_cache();
771                 for (i = 0; i < active_nr; i++) {
772                         unsigned int mode;
773                         struct blob *blob;
774                         struct object *obj;
775
776                         mode = active_cache[i]->ce_mode;
777                         if (S_ISGITLINK(mode))
778                                 continue;
779                         blob = lookup_blob(&active_cache[i]->oid);
780                         if (!blob)
781                                 continue;
782                         obj = &blob->object;
783                         obj->flags |= USED;
784                         if (name_objects)
785                                 add_decoration(fsck_walk_options.object_names,
786                                         obj,
787                                         xstrfmt(":%s", active_cache[i]->name));
788                         mark_object_reachable(obj);
789                 }
790                 if (active_cache_tree)
791                         fsck_cache_tree(active_cache_tree);
792         }
793
794         check_connectivity();
795         return errors_found;
796 }