Merge branch 'bw/submodule-with-bs-path'
[git/git.git] / refs / files-backend.c
1 #include "../cache.h"
2 #include "../refs.h"
3 #include "refs-internal.h"
4 #include "../iterator.h"
5 #include "../dir-iterator.h"
6 #include "../lockfile.h"
7 #include "../object.h"
8 #include "../dir.h"
9
10 struct ref_lock {
11 char *ref_name;
12 struct lock_file *lk;
13 struct object_id old_oid;
14 };
15
16 struct ref_entry;
17
18 /*
19 * Information used (along with the information in ref_entry) to
20 * describe a single cached reference. This data structure only
21 * occurs embedded in a union in struct ref_entry, and only when
22 * (ref_entry->flag & REF_DIR) is zero.
23 */
24 struct ref_value {
25 /*
26 * The name of the object to which this reference resolves
27 * (which may be a tag object). If REF_ISBROKEN, this is
28 * null. If REF_ISSYMREF, then this is the name of the object
29 * referred to by the last reference in the symlink chain.
30 */
31 struct object_id oid;
32
33 /*
34 * If REF_KNOWS_PEELED, then this field holds the peeled value
35 * of this reference, or null if the reference is known not to
36 * be peelable. See the documentation for peel_ref() for an
37 * exact definition of "peelable".
38 */
39 struct object_id peeled;
40 };
41
42 struct files_ref_store;
43
44 /*
45 * Information used (along with the information in ref_entry) to
46 * describe a level in the hierarchy of references. This data
47 * structure only occurs embedded in a union in struct ref_entry, and
48 * only when (ref_entry.flag & REF_DIR) is set. In that case,
49 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
50 * in the directory have already been read:
51 *
52 * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
53 * or packed references, already read.
54 *
55 * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
56 * references that hasn't been read yet (nor has any of its
57 * subdirectories).
58 *
59 * Entries within a directory are stored within a growable array of
60 * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
61 * sorted are sorted by their component name in strcmp() order and the
62 * remaining entries are unsorted.
63 *
64 * Loose references are read lazily, one directory at a time. When a
65 * directory of loose references is read, then all of the references
66 * in that directory are stored, and REF_INCOMPLETE stubs are created
67 * for any subdirectories, but the subdirectories themselves are not
68 * read. The reading is triggered by get_ref_dir().
69 */
70 struct ref_dir {
71 int nr, alloc;
72
73 /*
74 * Entries with index 0 <= i < sorted are sorted by name. New
75 * entries are appended to the list unsorted, and are sorted
76 * only when required; thus we avoid the need to sort the list
77 * after the addition of every reference.
78 */
79 int sorted;
80
81 /* A pointer to the files_ref_store that contains this ref_dir. */
82 struct files_ref_store *ref_store;
83
84 struct ref_entry **entries;
85 };
86
87 /*
88 * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
89 * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
90 * public values; see refs.h.
91 */
92
93 /*
94 * The field ref_entry->u.value.peeled of this value entry contains
95 * the correct peeled value for the reference, which might be
96 * null_sha1 if the reference is not a tag or if it is broken.
97 */
98 #define REF_KNOWS_PEELED 0x10
99
100 /* ref_entry represents a directory of references */
101 #define REF_DIR 0x20
102
103 /*
104 * Entry has not yet been read from disk (used only for REF_DIR
105 * entries representing loose references)
106 */
107 #define REF_INCOMPLETE 0x40
108
109 /*
110 * A ref_entry represents either a reference or a "subdirectory" of
111 * references.
112 *
113 * Each directory in the reference namespace is represented by a
114 * ref_entry with (flags & REF_DIR) set and containing a subdir member
115 * that holds the entries in that directory that have been read so
116 * far. If (flags & REF_INCOMPLETE) is set, then the directory and
117 * its subdirectories haven't been read yet. REF_INCOMPLETE is only
118 * used for loose reference directories.
119 *
120 * References are represented by a ref_entry with (flags & REF_DIR)
121 * unset and a value member that describes the reference's value. The
122 * flag member is at the ref_entry level, but it is also needed to
123 * interpret the contents of the value field (in other words, a
124 * ref_value object is not very much use without the enclosing
125 * ref_entry).
126 *
127 * Reference names cannot end with slash and directories' names are
128 * always stored with a trailing slash (except for the top-level
129 * directory, which is always denoted by ""). This has two nice
130 * consequences: (1) when the entries in each subdir are sorted
131 * lexicographically by name (as they usually are), the references in
132 * a whole tree can be generated in lexicographic order by traversing
133 * the tree in left-to-right, depth-first order; (2) the names of
134 * references and subdirectories cannot conflict, and therefore the
135 * presence of an empty subdirectory does not block the creation of a
136 * similarly-named reference. (The fact that reference names with the
137 * same leading components can conflict *with each other* is a
138 * separate issue that is regulated by verify_refname_available().)
139 *
140 * Please note that the name field contains the fully-qualified
141 * reference (or subdirectory) name. Space could be saved by only
142 * storing the relative names. But that would require the full names
143 * to be generated on the fly when iterating in do_for_each_ref(), and
144 * would break callback functions, who have always been able to assume
145 * that the name strings that they are passed will not be freed during
146 * the iteration.
147 */
148 struct ref_entry {
149 unsigned char flag; /* ISSYMREF? ISPACKED? */
150 union {
151 struct ref_value value; /* if not (flags&REF_DIR) */
152 struct ref_dir subdir; /* if (flags&REF_DIR) */
153 } u;
154 /*
155 * The full name of the reference (e.g., "refs/heads/master")
156 * or the full name of the directory with a trailing slash
157 * (e.g., "refs/heads/"):
158 */
159 char name[FLEX_ARRAY];
160 };
161
162 static void read_loose_refs(const char *dirname, struct ref_dir *dir);
163 static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
164 static struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
165 const char *dirname, size_t len,
166 int incomplete);
167 static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
168 static int files_log_ref_write(struct files_ref_store *refs,
169 const char *refname, const unsigned char *old_sha1,
170 const unsigned char *new_sha1, const char *msg,
171 int flags, struct strbuf *err);
172
173 static struct ref_dir *get_ref_dir(struct ref_entry *entry)
174 {
175 struct ref_dir *dir;
176 assert(entry->flag & REF_DIR);
177 dir = &entry->u.subdir;
178 if (entry->flag & REF_INCOMPLETE) {
179 read_loose_refs(entry->name, dir);
180
181 /*
182 * Manually add refs/bisect, which, being
183 * per-worktree, might not appear in the directory
184 * listing for refs/ in the main repo.
185 */
186 if (!strcmp(entry->name, "refs/")) {
187 int pos = search_ref_dir(dir, "refs/bisect/", 12);
188 if (pos < 0) {
189 struct ref_entry *child_entry;
190 child_entry = create_dir_entry(dir->ref_store,
191 "refs/bisect/",
192 12, 1);
193 add_entry_to_dir(dir, child_entry);
194 read_loose_refs("refs/bisect",
195 &child_entry->u.subdir);
196 }
197 }
198 entry->flag &= ~REF_INCOMPLETE;
199 }
200 return dir;
201 }
202
203 static struct ref_entry *create_ref_entry(const char *refname,
204 const unsigned char *sha1, int flag,
205 int check_name)
206 {
207 struct ref_entry *ref;
208
209 if (check_name &&
210 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
211 die("Reference has invalid format: '%s'", refname);
212 FLEX_ALLOC_STR(ref, name, refname);
213 hashcpy(ref->u.value.oid.hash, sha1);
214 oidclr(&ref->u.value.peeled);
215 ref->flag = flag;
216 return ref;
217 }
218
219 static void clear_ref_dir(struct ref_dir *dir);
220
221 static void free_ref_entry(struct ref_entry *entry)
222 {
223 if (entry->flag & REF_DIR) {
224 /*
225 * Do not use get_ref_dir() here, as that might
226 * trigger the reading of loose refs.
227 */
228 clear_ref_dir(&entry->u.subdir);
229 }
230 free(entry);
231 }
232
233 /*
234 * Add a ref_entry to the end of dir (unsorted). Entry is always
235 * stored directly in dir; no recursion into subdirectories is
236 * done.
237 */
238 static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
239 {
240 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
241 dir->entries[dir->nr++] = entry;
242 /* optimize for the case that entries are added in order */
243 if (dir->nr == 1 ||
244 (dir->nr == dir->sorted + 1 &&
245 strcmp(dir->entries[dir->nr - 2]->name,
246 dir->entries[dir->nr - 1]->name) < 0))
247 dir->sorted = dir->nr;
248 }
249
250 /*
251 * Clear and free all entries in dir, recursively.
252 */
253 static void clear_ref_dir(struct ref_dir *dir)
254 {
255 int i;
256 for (i = 0; i < dir->nr; i++)
257 free_ref_entry(dir->entries[i]);
258 free(dir->entries);
259 dir->sorted = dir->nr = dir->alloc = 0;
260 dir->entries = NULL;
261 }
262
263 /*
264 * Create a struct ref_entry object for the specified dirname.
265 * dirname is the name of the directory with a trailing slash (e.g.,
266 * "refs/heads/") or "" for the top-level directory.
267 */
268 static struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
269 const char *dirname, size_t len,
270 int incomplete)
271 {
272 struct ref_entry *direntry;
273 FLEX_ALLOC_MEM(direntry, name, dirname, len);
274 direntry->u.subdir.ref_store = ref_store;
275 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
276 return direntry;
277 }
278
279 static int ref_entry_cmp(const void *a, const void *b)
280 {
281 struct ref_entry *one = *(struct ref_entry **)a;
282 struct ref_entry *two = *(struct ref_entry **)b;
283 return strcmp(one->name, two->name);
284 }
285
286 static void sort_ref_dir(struct ref_dir *dir);
287
288 struct string_slice {
289 size_t len;
290 const char *str;
291 };
292
293 static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
294 {
295 const struct string_slice *key = key_;
296 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
297 int cmp = strncmp(key->str, ent->name, key->len);
298 if (cmp)
299 return cmp;
300 return '\0' - (unsigned char)ent->name[key->len];
301 }
302
303 /*
304 * Return the index of the entry with the given refname from the
305 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
306 * no such entry is found. dir must already be complete.
307 */
308 static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
309 {
310 struct ref_entry **r;
311 struct string_slice key;
312
313 if (refname == NULL || !dir->nr)
314 return -1;
315
316 sort_ref_dir(dir);
317 key.len = len;
318 key.str = refname;
319 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
320 ref_entry_cmp_sslice);
321
322 if (r == NULL)
323 return -1;
324
325 return r - dir->entries;
326 }
327
328 /*
329 * Search for a directory entry directly within dir (without
330 * recursing). Sort dir if necessary. subdirname must be a directory
331 * name (i.e., end in '/'). If mkdir is set, then create the
332 * directory if it is missing; otherwise, return NULL if the desired
333 * directory cannot be found. dir must already be complete.
334 */
335 static struct ref_dir *search_for_subdir(struct ref_dir *dir,
336 const char *subdirname, size_t len,
337 int mkdir)
338 {
339 int entry_index = search_ref_dir(dir, subdirname, len);
340 struct ref_entry *entry;
341 if (entry_index == -1) {
342 if (!mkdir)
343 return NULL;
344 /*
345 * Since dir is complete, the absence of a subdir
346 * means that the subdir really doesn't exist;
347 * therefore, create an empty record for it but mark
348 * the record complete.
349 */
350 entry = create_dir_entry(dir->ref_store, subdirname, len, 0);
351 add_entry_to_dir(dir, entry);
352 } else {
353 entry = dir->entries[entry_index];
354 }
355 return get_ref_dir(entry);
356 }
357
358 /*
359 * If refname is a reference name, find the ref_dir within the dir
360 * tree that should hold refname. If refname is a directory name
361 * (i.e., ends in '/'), then return that ref_dir itself. dir must
362 * represent the top-level directory and must already be complete.
363 * Sort ref_dirs and recurse into subdirectories as necessary. If
364 * mkdir is set, then create any missing directories; otherwise,
365 * return NULL if the desired directory cannot be found.
366 */
367 static struct ref_dir *find_containing_dir(struct ref_dir *dir,
368 const char *refname, int mkdir)
369 {
370 const char *slash;
371 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
372 size_t dirnamelen = slash - refname + 1;
373 struct ref_dir *subdir;
374 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
375 if (!subdir) {
376 dir = NULL;
377 break;
378 }
379 dir = subdir;
380 }
381
382 return dir;
383 }
384
385 /*
386 * Find the value entry with the given name in dir, sorting ref_dirs
387 * and recursing into subdirectories as necessary. If the name is not
388 * found or it corresponds to a directory entry, return NULL.
389 */
390 static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
391 {
392 int entry_index;
393 struct ref_entry *entry;
394 dir = find_containing_dir(dir, refname, 0);
395 if (!dir)
396 return NULL;
397 entry_index = search_ref_dir(dir, refname, strlen(refname));
398 if (entry_index == -1)
399 return NULL;
400 entry = dir->entries[entry_index];
401 return (entry->flag & REF_DIR) ? NULL : entry;
402 }
403
404 /*
405 * Remove the entry with the given name from dir, recursing into
406 * subdirectories as necessary. If refname is the name of a directory
407 * (i.e., ends with '/'), then remove the directory and its contents.
408 * If the removal was successful, return the number of entries
409 * remaining in the directory entry that contained the deleted entry.
410 * If the name was not found, return -1. Please note that this
411 * function only deletes the entry from the cache; it does not delete
412 * it from the filesystem or ensure that other cache entries (which
413 * might be symbolic references to the removed entry) are updated.
414 * Nor does it remove any containing dir entries that might be made
415 * empty by the removal. dir must represent the top-level directory
416 * and must already be complete.
417 */
418 static int remove_entry(struct ref_dir *dir, const char *refname)
419 {
420 int refname_len = strlen(refname);
421 int entry_index;
422 struct ref_entry *entry;
423 int is_dir = refname[refname_len - 1] == '/';
424 if (is_dir) {
425 /*
426 * refname represents a reference directory. Remove
427 * the trailing slash; otherwise we will get the
428 * directory *representing* refname rather than the
429 * one *containing* it.
430 */
431 char *dirname = xmemdupz(refname, refname_len - 1);
432 dir = find_containing_dir(dir, dirname, 0);
433 free(dirname);
434 } else {
435 dir = find_containing_dir(dir, refname, 0);
436 }
437 if (!dir)
438 return -1;
439 entry_index = search_ref_dir(dir, refname, refname_len);
440 if (entry_index == -1)
441 return -1;
442 entry = dir->entries[entry_index];
443
444 memmove(&dir->entries[entry_index],
445 &dir->entries[entry_index + 1],
446 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
447 );
448 dir->nr--;
449 if (dir->sorted > entry_index)
450 dir->sorted--;
451 free_ref_entry(entry);
452 return dir->nr;
453 }
454
455 /*
456 * Add a ref_entry to the ref_dir (unsorted), recursing into
457 * subdirectories as necessary. dir must represent the top-level
458 * directory. Return 0 on success.
459 */
460 static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
461 {
462 dir = find_containing_dir(dir, ref->name, 1);
463 if (!dir)
464 return -1;
465 add_entry_to_dir(dir, ref);
466 return 0;
467 }
468
469 /*
470 * Emit a warning and return true iff ref1 and ref2 have the same name
471 * and the same sha1. Die if they have the same name but different
472 * sha1s.
473 */
474 static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
475 {
476 if (strcmp(ref1->name, ref2->name))
477 return 0;
478
479 /* Duplicate name; make sure that they don't conflict: */
480
481 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
482 /* This is impossible by construction */
483 die("Reference directory conflict: %s", ref1->name);
484
485 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
486 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
487
488 warning("Duplicated ref: %s", ref1->name);
489 return 1;
490 }
491
492 /*
493 * Sort the entries in dir non-recursively (if they are not already
494 * sorted) and remove any duplicate entries.
495 */
496 static void sort_ref_dir(struct ref_dir *dir)
497 {
498 int i, j;
499 struct ref_entry *last = NULL;
500
501 /*
502 * This check also prevents passing a zero-length array to qsort(),
503 * which is a problem on some platforms.
504 */
505 if (dir->sorted == dir->nr)
506 return;
507
508 QSORT(dir->entries, dir->nr, ref_entry_cmp);
509
510 /* Remove any duplicates: */
511 for (i = 0, j = 0; j < dir->nr; j++) {
512 struct ref_entry *entry = dir->entries[j];
513 if (last && is_dup_ref(last, entry))
514 free_ref_entry(entry);
515 else
516 last = dir->entries[i++] = entry;
517 }
518 dir->sorted = dir->nr = i;
519 }
520
521 /*
522 * Return true if refname, which has the specified oid and flags, can
523 * be resolved to an object in the database. If the referred-to object
524 * does not exist, emit a warning and return false.
525 */
526 static int ref_resolves_to_object(const char *refname,
527 const struct object_id *oid,
528 unsigned int flags)
529 {
530 if (flags & REF_ISBROKEN)
531 return 0;
532 if (!has_sha1_file(oid->hash)) {
533 error("%s does not point to a valid object!", refname);
534 return 0;
535 }
536 return 1;
537 }
538
539 /*
540 * Return true if the reference described by entry can be resolved to
541 * an object in the database; otherwise, emit a warning and return
542 * false.
543 */
544 static int entry_resolves_to_object(struct ref_entry *entry)
545 {
546 return ref_resolves_to_object(entry->name,
547 &entry->u.value.oid, entry->flag);
548 }
549
550 typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
551
552 /*
553 * Call fn for each reference in dir that has index in the range
554 * offset <= index < dir->nr. Recurse into subdirectories that are in
555 * that index range, sorting them before iterating. This function
556 * does not sort dir itself; it should be sorted beforehand. fn is
557 * called for all references, including broken ones.
558 */
559 static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
560 each_ref_entry_fn fn, void *cb_data)
561 {
562 int i;
563 assert(dir->sorted == dir->nr);
564 for (i = offset; i < dir->nr; i++) {
565 struct ref_entry *entry = dir->entries[i];
566 int retval;
567 if (entry->flag & REF_DIR) {
568 struct ref_dir *subdir = get_ref_dir(entry);
569 sort_ref_dir(subdir);
570 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
571 } else {
572 retval = fn(entry, cb_data);
573 }
574 if (retval)
575 return retval;
576 }
577 return 0;
578 }
579
580 /*
581 * Load all of the refs from the dir into our in-memory cache. The hard work
582 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
583 * through all of the sub-directories. We do not even need to care about
584 * sorting, as traversal order does not matter to us.
585 */
586 static void prime_ref_dir(struct ref_dir *dir)
587 {
588 int i;
589 for (i = 0; i < dir->nr; i++) {
590 struct ref_entry *entry = dir->entries[i];
591 if (entry->flag & REF_DIR)
592 prime_ref_dir(get_ref_dir(entry));
593 }
594 }
595
596 /*
597 * A level in the reference hierarchy that is currently being iterated
598 * through.
599 */
600 struct cache_ref_iterator_level {
601 /*
602 * The ref_dir being iterated over at this level. The ref_dir
603 * is sorted before being stored here.
604 */
605 struct ref_dir *dir;
606
607 /*
608 * The index of the current entry within dir (which might
609 * itself be a directory). If index == -1, then the iteration
610 * hasn't yet begun. If index == dir->nr, then the iteration
611 * through this level is over.
612 */
613 int index;
614 };
615
616 /*
617 * Represent an iteration through a ref_dir in the memory cache. The
618 * iteration recurses through subdirectories.
619 */
620 struct cache_ref_iterator {
621 struct ref_iterator base;
622
623 /*
624 * The number of levels currently on the stack. This is always
625 * at least 1, because when it becomes zero the iteration is
626 * ended and this struct is freed.
627 */
628 size_t levels_nr;
629
630 /* The number of levels that have been allocated on the stack */
631 size_t levels_alloc;
632
633 /*
634 * A stack of levels. levels[0] is the uppermost level that is
635 * being iterated over in this iteration. (This is not
636 * necessary the top level in the references hierarchy. If we
637 * are iterating through a subtree, then levels[0] will hold
638 * the ref_dir for that subtree, and subsequent levels will go
639 * on from there.)
640 */
641 struct cache_ref_iterator_level *levels;
642 };
643
644 static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
645 {
646 struct cache_ref_iterator *iter =
647 (struct cache_ref_iterator *)ref_iterator;
648
649 while (1) {
650 struct cache_ref_iterator_level *level =
651 &iter->levels[iter->levels_nr - 1];
652 struct ref_dir *dir = level->dir;
653 struct ref_entry *entry;
654
655 if (level->index == -1)
656 sort_ref_dir(dir);
657
658 if (++level->index == level->dir->nr) {
659 /* This level is exhausted; pop up a level */
660 if (--iter->levels_nr == 0)
661 return ref_iterator_abort(ref_iterator);
662
663 continue;
664 }
665
666 entry = dir->entries[level->index];
667
668 if (entry->flag & REF_DIR) {
669 /* push down a level */
670 ALLOC_GROW(iter->levels, iter->levels_nr + 1,
671 iter->levels_alloc);
672
673 level = &iter->levels[iter->levels_nr++];
674 level->dir = get_ref_dir(entry);
675 level->index = -1;
676 } else {
677 iter->base.refname = entry->name;
678 iter->base.oid = &entry->u.value.oid;
679 iter->base.flags = entry->flag;
680 return ITER_OK;
681 }
682 }
683 }
684
685 static enum peel_status peel_entry(struct ref_entry *entry, int repeel);
686
687 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
688 struct object_id *peeled)
689 {
690 struct cache_ref_iterator *iter =
691 (struct cache_ref_iterator *)ref_iterator;
692 struct cache_ref_iterator_level *level;
693 struct ref_entry *entry;
694
695 level = &iter->levels[iter->levels_nr - 1];
696
697 if (level->index == -1)
698 die("BUG: peel called before advance for cache iterator");
699
700 entry = level->dir->entries[level->index];
701
702 if (peel_entry(entry, 0))
703 return -1;
704 oidcpy(peeled, &entry->u.value.peeled);
705 return 0;
706 }
707
708 static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
709 {
710 struct cache_ref_iterator *iter =
711 (struct cache_ref_iterator *)ref_iterator;
712
713 free(iter->levels);
714 base_ref_iterator_free(ref_iterator);
715 return ITER_DONE;
716 }
717
718 static struct ref_iterator_vtable cache_ref_iterator_vtable = {
719 cache_ref_iterator_advance,
720 cache_ref_iterator_peel,
721 cache_ref_iterator_abort
722 };
723
724 static struct ref_iterator *cache_ref_iterator_begin(struct ref_dir *dir)
725 {
726 struct cache_ref_iterator *iter;
727 struct ref_iterator *ref_iterator;
728 struct cache_ref_iterator_level *level;
729
730 iter = xcalloc(1, sizeof(*iter));
731 ref_iterator = &iter->base;
732 base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
733 ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
734
735 iter->levels_nr = 1;
736 level = &iter->levels[0];
737 level->index = -1;
738 level->dir = dir;
739
740 return ref_iterator;
741 }
742
743 struct nonmatching_ref_data {
744 const struct string_list *skip;
745 const char *conflicting_refname;
746 };
747
748 static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
749 {
750 struct nonmatching_ref_data *data = vdata;
751
752 if (data->skip && string_list_has_string(data->skip, entry->name))
753 return 0;
754
755 data->conflicting_refname = entry->name;
756 return 1;
757 }
758
759 /*
760 * Return 0 if a reference named refname could be created without
761 * conflicting with the name of an existing reference in dir.
762 * See verify_refname_available for more information.
763 */
764 static int verify_refname_available_dir(const char *refname,
765 const struct string_list *extras,
766 const struct string_list *skip,
767 struct ref_dir *dir,
768 struct strbuf *err)
769 {
770 const char *slash;
771 const char *extra_refname;
772 int pos;
773 struct strbuf dirname = STRBUF_INIT;
774 int ret = -1;
775
776 /*
777 * For the sake of comments in this function, suppose that
778 * refname is "refs/foo/bar".
779 */
780
781 assert(err);
782
783 strbuf_grow(&dirname, strlen(refname) + 1);
784 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
785 /* Expand dirname to the new prefix, not including the trailing slash: */
786 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
787
788 /*
789 * We are still at a leading dir of the refname (e.g.,
790 * "refs/foo"; if there is a reference with that name,
791 * it is a conflict, *unless* it is in skip.
792 */
793 if (dir) {
794 pos = search_ref_dir(dir, dirname.buf, dirname.len);
795 if (pos >= 0 &&
796 (!skip || !string_list_has_string(skip, dirname.buf))) {
797 /*
798 * We found a reference whose name is
799 * a proper prefix of refname; e.g.,
800 * "refs/foo", and is not in skip.
801 */
802 strbuf_addf(err, "'%s' exists; cannot create '%s'",
803 dirname.buf, refname);
804 goto cleanup;
805 }
806 }
807
808 if (extras && string_list_has_string(extras, dirname.buf) &&
809 (!skip || !string_list_has_string(skip, dirname.buf))) {
810 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
811 refname, dirname.buf);
812 goto cleanup;
813 }
814
815 /*
816 * Otherwise, we can try to continue our search with
817 * the next component. So try to look up the
818 * directory, e.g., "refs/foo/". If we come up empty,
819 * we know there is nothing under this whole prefix,
820 * but even in that case we still have to continue the
821 * search for conflicts with extras.
822 */
823 strbuf_addch(&dirname, '/');
824 if (dir) {
825 pos = search_ref_dir(dir, dirname.buf, dirname.len);
826 if (pos < 0) {
827 /*
828 * There was no directory "refs/foo/",
829 * so there is nothing under this
830 * whole prefix. So there is no need
831 * to continue looking for conflicting
832 * references. But we need to continue
833 * looking for conflicting extras.
834 */
835 dir = NULL;
836 } else {
837 dir = get_ref_dir(dir->entries[pos]);
838 }
839 }
840 }
841
842 /*
843 * We are at the leaf of our refname (e.g., "refs/foo/bar").
844 * There is no point in searching for a reference with that
845 * name, because a refname isn't considered to conflict with
846 * itself. But we still need to check for references whose
847 * names are in the "refs/foo/bar/" namespace, because they
848 * *do* conflict.
849 */
850 strbuf_addstr(&dirname, refname + dirname.len);
851 strbuf_addch(&dirname, '/');
852
853 if (dir) {
854 pos = search_ref_dir(dir, dirname.buf, dirname.len);
855
856 if (pos >= 0) {
857 /*
858 * We found a directory named "$refname/"
859 * (e.g., "refs/foo/bar/"). It is a problem
860 * iff it contains any ref that is not in
861 * "skip".
862 */
863 struct nonmatching_ref_data data;
864
865 data.skip = skip;
866 data.conflicting_refname = NULL;
867 dir = get_ref_dir(dir->entries[pos]);
868 sort_ref_dir(dir);
869 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
870 strbuf_addf(err, "'%s' exists; cannot create '%s'",
871 data.conflicting_refname, refname);
872 goto cleanup;
873 }
874 }
875 }
876
877 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
878 if (extra_refname)
879 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
880 refname, extra_refname);
881 else
882 ret = 0;
883
884 cleanup:
885 strbuf_release(&dirname);
886 return ret;
887 }
888
889 struct packed_ref_cache {
890 struct ref_entry *root;
891
892 /*
893 * Count of references to the data structure in this instance,
894 * including the pointer from files_ref_store::packed if any.
895 * The data will not be freed as long as the reference count
896 * is nonzero.
897 */
898 unsigned int referrers;
899
900 /*
901 * Iff the packed-refs file associated with this instance is
902 * currently locked for writing, this points at the associated
903 * lock (which is owned by somebody else). The referrer count
904 * is also incremented when the file is locked and decremented
905 * when it is unlocked.
906 */
907 struct lock_file *lock;
908
909 /* The metadata from when this packed-refs cache was read */
910 struct stat_validity validity;
911 };
912
913 /*
914 * Future: need to be in "struct repository"
915 * when doing a full libification.
916 */
917 struct files_ref_store {
918 struct ref_store base;
919 unsigned int store_flags;
920
921 char *gitdir;
922 char *gitcommondir;
923 char *packed_refs_path;
924
925 struct ref_entry *loose;
926 struct packed_ref_cache *packed;
927 };
928
929 /* Lock used for the main packed-refs file: */
930 static struct lock_file packlock;
931
932 /*
933 * Increment the reference count of *packed_refs.
934 */
935 static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
936 {
937 packed_refs->referrers++;
938 }
939
940 /*
941 * Decrease the reference count of *packed_refs. If it goes to zero,
942 * free *packed_refs and return true; otherwise return false.
943 */
944 static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
945 {
946 if (!--packed_refs->referrers) {
947 free_ref_entry(packed_refs->root);
948 stat_validity_clear(&packed_refs->validity);
949 free(packed_refs);
950 return 1;
951 } else {
952 return 0;
953 }
954 }
955
956 static void clear_packed_ref_cache(struct files_ref_store *refs)
957 {
958 if (refs->packed) {
959 struct packed_ref_cache *packed_refs = refs->packed;
960
961 if (packed_refs->lock)
962 die("internal error: packed-ref cache cleared while locked");
963 refs->packed = NULL;
964 release_packed_ref_cache(packed_refs);
965 }
966 }
967
968 static void clear_loose_ref_cache(struct files_ref_store *refs)
969 {
970 if (refs->loose) {
971 free_ref_entry(refs->loose);
972 refs->loose = NULL;
973 }
974 }
975
976 /*
977 * Create a new submodule ref cache and add it to the internal
978 * set of caches.
979 */
980 static struct ref_store *files_ref_store_create(const char *gitdir,
981 unsigned int flags)
982 {
983 struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
984 struct ref_store *ref_store = (struct ref_store *)refs;
985 struct strbuf sb = STRBUF_INIT;
986
987 base_ref_store_init(ref_store, &refs_be_files);
988 refs->store_flags = flags;
989
990 refs->gitdir = xstrdup(gitdir);
991 get_common_dir_noenv(&sb, gitdir);
992 refs->gitcommondir = strbuf_detach(&sb, NULL);
993 strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
994 refs->packed_refs_path = strbuf_detach(&sb, NULL);
995
996 return ref_store;
997 }
998
999 /*
1000 * Die if refs is not the main ref store. caller is used in any
1001 * necessary error messages.
1002 */
1003 static void files_assert_main_repository(struct files_ref_store *refs,
1004 const char *caller)
1005 {
1006 if (refs->store_flags & REF_STORE_MAIN)
1007 return;
1008
1009 die("BUG: operation %s only allowed for main ref store", caller);
1010 }
1011
1012 /*
1013 * Downcast ref_store to files_ref_store. Die if ref_store is not a
1014 * files_ref_store. required_flags is compared with ref_store's
1015 * store_flags to ensure the ref_store has all required capabilities.
1016 * "caller" is used in any necessary error messages.
1017 */
1018 static struct files_ref_store *files_downcast(struct ref_store *ref_store,
1019 unsigned int required_flags,
1020 const char *caller)
1021 {
1022 struct files_ref_store *refs;
1023
1024 if (ref_store->be != &refs_be_files)
1025 die("BUG: ref_store is type \"%s\" not \"files\" in %s",
1026 ref_store->be->name, caller);
1027
1028 refs = (struct files_ref_store *)ref_store;
1029
1030 if ((refs->store_flags & required_flags) != required_flags)
1031 die("BUG: operation %s requires abilities 0x%x, but only have 0x%x",
1032 caller, required_flags, refs->store_flags);
1033
1034 return refs;
1035 }
1036
1037 /* The length of a peeled reference line in packed-refs, including EOL: */
1038 #define PEELED_LINE_LENGTH 42
1039
1040 /*
1041 * The packed-refs header line that we write out. Perhaps other
1042 * traits will be added later. The trailing space is required.
1043 */
1044 static const char PACKED_REFS_HEADER[] =
1045 "# pack-refs with: peeled fully-peeled \n";
1046
1047 /*
1048 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
1049 * Return a pointer to the refname within the line (null-terminated),
1050 * or NULL if there was a problem.
1051 */
1052 static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
1053 {
1054 const char *ref;
1055
1056 /*
1057 * 42: the answer to everything.
1058 *
1059 * In this case, it happens to be the answer to
1060 * 40 (length of sha1 hex representation)
1061 * +1 (space in between hex and name)
1062 * +1 (newline at the end of the line)
1063 */
1064 if (line->len <= 42)
1065 return NULL;
1066
1067 if (get_sha1_hex(line->buf, sha1) < 0)
1068 return NULL;
1069 if (!isspace(line->buf[40]))
1070 return NULL;
1071
1072 ref = line->buf + 41;
1073 if (isspace(*ref))
1074 return NULL;
1075
1076 if (line->buf[line->len - 1] != '\n')
1077 return NULL;
1078 line->buf[--line->len] = 0;
1079
1080 return ref;
1081 }
1082
1083 /*
1084 * Read f, which is a packed-refs file, into dir.
1085 *
1086 * A comment line of the form "# pack-refs with: " may contain zero or
1087 * more traits. We interpret the traits as follows:
1088 *
1089 * No traits:
1090 *
1091 * Probably no references are peeled. But if the file contains a
1092 * peeled value for a reference, we will use it.
1093 *
1094 * peeled:
1095 *
1096 * References under "refs/tags/", if they *can* be peeled, *are*
1097 * peeled in this file. References outside of "refs/tags/" are
1098 * probably not peeled even if they could have been, but if we find
1099 * a peeled value for such a reference we will use it.
1100 *
1101 * fully-peeled:
1102 *
1103 * All references in the file that can be peeled are peeled.
1104 * Inversely (and this is more important), any references in the
1105 * file for which no peeled value is recorded is not peelable. This
1106 * trait should typically be written alongside "peeled" for
1107 * compatibility with older clients, but we do not require it
1108 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1109 */
1110 static void read_packed_refs(FILE *f, struct ref_dir *dir)
1111 {
1112 struct ref_entry *last = NULL;
1113 struct strbuf line = STRBUF_INIT;
1114 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1115
1116 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1117 unsigned char sha1[20];
1118 const char *refname;
1119 const char *traits;
1120
1121 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1122 if (strstr(traits, " fully-peeled "))
1123 peeled = PEELED_FULLY;
1124 else if (strstr(traits, " peeled "))
1125 peeled = PEELED_TAGS;
1126 /* perhaps other traits later as well */
1127 continue;
1128 }
1129
1130 refname = parse_ref_line(&line, sha1);
1131 if (refname) {
1132 int flag = REF_ISPACKED;
1133
1134 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1135 if (!refname_is_safe(refname))
1136 die("packed refname is dangerous: %s", refname);
1137 hashclr(sha1);
1138 flag |= REF_BAD_NAME | REF_ISBROKEN;
1139 }
1140 last = create_ref_entry(refname, sha1, flag, 0);
1141 if (peeled == PEELED_FULLY ||
1142 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1143 last->flag |= REF_KNOWS_PEELED;
1144 add_ref(dir, last);
1145 continue;
1146 }
1147 if (last &&
1148 line.buf[0] == '^' &&
1149 line.len == PEELED_LINE_LENGTH &&
1150 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1151 !get_sha1_hex(line.buf + 1, sha1)) {
1152 hashcpy(last->u.value.peeled.hash, sha1);
1153 /*
1154 * Regardless of what the file header said,
1155 * we definitely know the value of *this*
1156 * reference:
1157 */
1158 last->flag |= REF_KNOWS_PEELED;
1159 }
1160 }
1161
1162 strbuf_release(&line);
1163 }
1164
1165 static const char *files_packed_refs_path(struct files_ref_store *refs)
1166 {
1167 return refs->packed_refs_path;
1168 }
1169
1170 static void files_reflog_path(struct files_ref_store *refs,
1171 struct strbuf *sb,
1172 const char *refname)
1173 {
1174 if (!refname) {
1175 /*
1176 * FIXME: of course this is wrong in multi worktree
1177 * setting. To be fixed real soon.
1178 */
1179 strbuf_addf(sb, "%s/logs", refs->gitcommondir);
1180 return;
1181 }
1182
1183 switch (ref_type(refname)) {
1184 case REF_TYPE_PER_WORKTREE:
1185 case REF_TYPE_PSEUDOREF:
1186 strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
1187 break;
1188 case REF_TYPE_NORMAL:
1189 strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
1190 break;
1191 default:
1192 die("BUG: unknown ref type %d of ref %s",
1193 ref_type(refname), refname);
1194 }
1195 }
1196
1197 static void files_ref_path(struct files_ref_store *refs,
1198 struct strbuf *sb,
1199 const char *refname)
1200 {
1201 switch (ref_type(refname)) {
1202 case REF_TYPE_PER_WORKTREE:
1203 case REF_TYPE_PSEUDOREF:
1204 strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
1205 break;
1206 case REF_TYPE_NORMAL:
1207 strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
1208 break;
1209 default:
1210 die("BUG: unknown ref type %d of ref %s",
1211 ref_type(refname), refname);
1212 }
1213 }
1214
1215 /*
1216 * Get the packed_ref_cache for the specified files_ref_store,
1217 * creating it if necessary.
1218 */
1219 static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *refs)
1220 {
1221 const char *packed_refs_file = files_packed_refs_path(refs);
1222
1223 if (refs->packed &&
1224 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1225 clear_packed_ref_cache(refs);
1226
1227 if (!refs->packed) {
1228 FILE *f;
1229
1230 refs->packed = xcalloc(1, sizeof(*refs->packed));
1231 acquire_packed_ref_cache(refs->packed);
1232 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1233 f = fopen(packed_refs_file, "r");
1234 if (f) {
1235 stat_validity_update(&refs->packed->validity, fileno(f));
1236 read_packed_refs(f, get_ref_dir(refs->packed->root));
1237 fclose(f);
1238 }
1239 }
1240 return refs->packed;
1241 }
1242
1243 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1244 {
1245 return get_ref_dir(packed_ref_cache->root);
1246 }
1247
1248 static struct ref_dir *get_packed_refs(struct files_ref_store *refs)
1249 {
1250 return get_packed_ref_dir(get_packed_ref_cache(refs));
1251 }
1252
1253 /*
1254 * Add a reference to the in-memory packed reference cache. This may
1255 * only be called while the packed-refs file is locked (see
1256 * lock_packed_refs()). To actually write the packed-refs file, call
1257 * commit_packed_refs().
1258 */
1259 static void add_packed_ref(struct files_ref_store *refs,
1260 const char *refname, const unsigned char *sha1)
1261 {
1262 struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
1263
1264 if (!packed_ref_cache->lock)
1265 die("internal error: packed refs not locked");
1266 add_ref(get_packed_ref_dir(packed_ref_cache),
1267 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1268 }
1269
1270 /*
1271 * Read the loose references from the namespace dirname into dir
1272 * (without recursing). dirname must end with '/'. dir must be the
1273 * directory entry corresponding to dirname.
1274 */
1275 static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1276 {
1277 struct files_ref_store *refs = dir->ref_store;
1278 DIR *d;
1279 struct dirent *de;
1280 int dirnamelen = strlen(dirname);
1281 struct strbuf refname;
1282 struct strbuf path = STRBUF_INIT;
1283 size_t path_baselen;
1284
1285 files_ref_path(refs, &path, dirname);
1286 path_baselen = path.len;
1287
1288 d = opendir(path.buf);
1289 if (!d) {
1290 strbuf_release(&path);
1291 return;
1292 }
1293
1294 strbuf_init(&refname, dirnamelen + 257);
1295 strbuf_add(&refname, dirname, dirnamelen);
1296
1297 while ((de = readdir(d)) != NULL) {
1298 unsigned char sha1[20];
1299 struct stat st;
1300 int flag;
1301
1302 if (de->d_name[0] == '.')
1303 continue;
1304 if (ends_with(de->d_name, ".lock"))
1305 continue;
1306 strbuf_addstr(&refname, de->d_name);
1307 strbuf_addstr(&path, de->d_name);
1308 if (stat(path.buf, &st) < 0) {
1309 ; /* silently ignore */
1310 } else if (S_ISDIR(st.st_mode)) {
1311 strbuf_addch(&refname, '/');
1312 add_entry_to_dir(dir,
1313 create_dir_entry(refs, refname.buf,
1314 refname.len, 1));
1315 } else {
1316 if (!refs_resolve_ref_unsafe(&refs->base,
1317 refname.buf,
1318 RESOLVE_REF_READING,
1319 sha1, &flag)) {
1320 hashclr(sha1);
1321 flag |= REF_ISBROKEN;
1322 } else if (is_null_sha1(sha1)) {
1323 /*
1324 * It is so astronomically unlikely
1325 * that NULL_SHA1 is the SHA-1 of an
1326 * actual object that we consider its
1327 * appearance in a loose reference
1328 * file to be repo corruption
1329 * (probably due to a software bug).
1330 */
1331 flag |= REF_ISBROKEN;
1332 }
1333
1334 if (check_refname_format(refname.buf,
1335 REFNAME_ALLOW_ONELEVEL)) {
1336 if (!refname_is_safe(refname.buf))
1337 die("loose refname is dangerous: %s", refname.buf);
1338 hashclr(sha1);
1339 flag |= REF_BAD_NAME | REF_ISBROKEN;
1340 }
1341 add_entry_to_dir(dir,
1342 create_ref_entry(refname.buf, sha1, flag, 0));
1343 }
1344 strbuf_setlen(&refname, dirnamelen);
1345 strbuf_setlen(&path, path_baselen);
1346 }
1347 strbuf_release(&refname);
1348 strbuf_release(&path);
1349 closedir(d);
1350 }
1351
1352 static struct ref_dir *get_loose_refs(struct files_ref_store *refs)
1353 {
1354 if (!refs->loose) {
1355 /*
1356 * Mark the top-level directory complete because we
1357 * are about to read the only subdirectory that can
1358 * hold references:
1359 */
1360 refs->loose = create_dir_entry(refs, "", 0, 0);
1361 /*
1362 * Create an incomplete entry for "refs/":
1363 */
1364 add_entry_to_dir(get_ref_dir(refs->loose),
1365 create_dir_entry(refs, "refs/", 5, 1));
1366 }
1367 return get_ref_dir(refs->loose);
1368 }
1369
1370 /*
1371 * Return the ref_entry for the given refname from the packed
1372 * references. If it does not exist, return NULL.
1373 */
1374 static struct ref_entry *get_packed_ref(struct files_ref_store *refs,
1375 const char *refname)
1376 {
1377 return find_ref(get_packed_refs(refs), refname);
1378 }
1379
1380 /*
1381 * A loose ref file doesn't exist; check for a packed ref.
1382 */
1383 static int resolve_packed_ref(struct files_ref_store *refs,
1384 const char *refname,
1385 unsigned char *sha1, unsigned int *flags)
1386 {
1387 struct ref_entry *entry;
1388
1389 /*
1390 * The loose reference file does not exist; check for a packed
1391 * reference.
1392 */
1393 entry = get_packed_ref(refs, refname);
1394 if (entry) {
1395 hashcpy(sha1, entry->u.value.oid.hash);
1396 *flags |= REF_ISPACKED;
1397 return 0;
1398 }
1399 /* refname is not a packed reference. */
1400 return -1;
1401 }
1402
1403 static int files_read_raw_ref(struct ref_store *ref_store,
1404 const char *refname, unsigned char *sha1,
1405 struct strbuf *referent, unsigned int *type)
1406 {
1407 struct files_ref_store *refs =
1408 files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
1409 struct strbuf sb_contents = STRBUF_INIT;
1410 struct strbuf sb_path = STRBUF_INIT;
1411 const char *path;
1412 const char *buf;
1413 struct stat st;
1414 int fd;
1415 int ret = -1;
1416 int save_errno;
1417 int remaining_retries = 3;
1418
1419 *type = 0;
1420 strbuf_reset(&sb_path);
1421
1422 files_ref_path(refs, &sb_path, refname);
1423
1424 path = sb_path.buf;
1425
1426 stat_ref:
1427 /*
1428 * We might have to loop back here to avoid a race
1429 * condition: first we lstat() the file, then we try
1430 * to read it as a link or as a file. But if somebody
1431 * changes the type of the file (file <-> directory
1432 * <-> symlink) between the lstat() and reading, then
1433 * we don't want to report that as an error but rather
1434 * try again starting with the lstat().
1435 *
1436 * We'll keep a count of the retries, though, just to avoid
1437 * any confusing situation sending us into an infinite loop.
1438 */
1439
1440 if (remaining_retries-- <= 0)
1441 goto out;
1442
1443 if (lstat(path, &st) < 0) {
1444 if (errno != ENOENT)
1445 goto out;
1446 if (resolve_packed_ref(refs, refname, sha1, type)) {
1447 errno = ENOENT;
1448 goto out;
1449 }
1450 ret = 0;
1451 goto out;
1452 }
1453
1454 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1455 if (S_ISLNK(st.st_mode)) {
1456 strbuf_reset(&sb_contents);
1457 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
1458 if (errno == ENOENT || errno == EINVAL)
1459 /* inconsistent with lstat; retry */
1460 goto stat_ref;
1461 else
1462 goto out;
1463 }
1464 if (starts_with(sb_contents.buf, "refs/") &&
1465 !check_refname_format(sb_contents.buf, 0)) {
1466 strbuf_swap(&sb_contents, referent);
1467 *type |= REF_ISSYMREF;
1468 ret = 0;
1469 goto out;
1470 }
1471 /*
1472 * It doesn't look like a refname; fall through to just
1473 * treating it like a non-symlink, and reading whatever it
1474 * points to.
1475 */
1476 }
1477
1478 /* Is it a directory? */
1479 if (S_ISDIR(st.st_mode)) {
1480 /*
1481 * Even though there is a directory where the loose
1482 * ref is supposed to be, there could still be a
1483 * packed ref:
1484 */
1485 if (resolve_packed_ref(refs, refname, sha1, type)) {
1486 errno = EISDIR;
1487 goto out;
1488 }
1489 ret = 0;
1490 goto out;
1491 }
1492
1493 /*
1494 * Anything else, just open it and try to use it as
1495 * a ref
1496 */
1497 fd = open(path, O_RDONLY);
1498 if (fd < 0) {
1499 if (errno == ENOENT && !S_ISLNK(st.st_mode))
1500 /* inconsistent with lstat; retry */
1501 goto stat_ref;
1502 else
1503 goto out;
1504 }
1505 strbuf_reset(&sb_contents);
1506 if (strbuf_read(&sb_contents, fd, 256) < 0) {
1507 int save_errno = errno;
1508 close(fd);
1509 errno = save_errno;
1510 goto out;
1511 }
1512 close(fd);
1513 strbuf_rtrim(&sb_contents);
1514 buf = sb_contents.buf;
1515 if (starts_with(buf, "ref:")) {
1516 buf += 4;
1517 while (isspace(*buf))
1518 buf++;
1519
1520 strbuf_reset(referent);
1521 strbuf_addstr(referent, buf);
1522 *type |= REF_ISSYMREF;
1523 ret = 0;
1524 goto out;
1525 }
1526
1527 /*
1528 * Please note that FETCH_HEAD has additional
1529 * data after the sha.
1530 */
1531 if (get_sha1_hex(buf, sha1) ||
1532 (buf[40] != '\0' && !isspace(buf[40]))) {
1533 *type |= REF_ISBROKEN;
1534 errno = EINVAL;
1535 goto out;
1536 }
1537
1538 ret = 0;
1539
1540 out:
1541 save_errno = errno;
1542 strbuf_release(&sb_path);
1543 strbuf_release(&sb_contents);
1544 errno = save_errno;
1545 return ret;
1546 }
1547
1548 static void unlock_ref(struct ref_lock *lock)
1549 {
1550 /* Do not free lock->lk -- atexit() still looks at them */
1551 if (lock->lk)
1552 rollback_lock_file(lock->lk);
1553 free(lock->ref_name);
1554 free(lock);
1555 }
1556
1557 /*
1558 * Lock refname, without following symrefs, and set *lock_p to point
1559 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1560 * and type similarly to read_raw_ref().
1561 *
1562 * The caller must verify that refname is a "safe" reference name (in
1563 * the sense of refname_is_safe()) before calling this function.
1564 *
1565 * If the reference doesn't already exist, verify that refname doesn't
1566 * have a D/F conflict with any existing references. extras and skip
1567 * are passed to verify_refname_available_dir() for this check.
1568 *
1569 * If mustexist is not set and the reference is not found or is
1570 * broken, lock the reference anyway but clear sha1.
1571 *
1572 * Return 0 on success. On failure, write an error message to err and
1573 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1574 *
1575 * Implementation note: This function is basically
1576 *
1577 * lock reference
1578 * read_raw_ref()
1579 *
1580 * but it includes a lot more code to
1581 * - Deal with possible races with other processes
1582 * - Avoid calling verify_refname_available_dir() when it can be
1583 * avoided, namely if we were successfully able to read the ref
1584 * - Generate informative error messages in the case of failure
1585 */
1586 static int lock_raw_ref(struct files_ref_store *refs,
1587 const char *refname, int mustexist,
1588 const struct string_list *extras,
1589 const struct string_list *skip,
1590 struct ref_lock **lock_p,
1591 struct strbuf *referent,
1592 unsigned int *type,
1593 struct strbuf *err)
1594 {
1595 struct ref_lock *lock;
1596 struct strbuf ref_file = STRBUF_INIT;
1597 int attempts_remaining = 3;
1598 int ret = TRANSACTION_GENERIC_ERROR;
1599
1600 assert(err);
1601 files_assert_main_repository(refs, "lock_raw_ref");
1602
1603 *type = 0;
1604
1605 /* First lock the file so it can't change out from under us. */
1606
1607 *lock_p = lock = xcalloc(1, sizeof(*lock));
1608
1609 lock->ref_name = xstrdup(refname);
1610 files_ref_path(refs, &ref_file, refname);
1611
1612 retry:
1613 switch (safe_create_leading_directories(ref_file.buf)) {
1614 case SCLD_OK:
1615 break; /* success */
1616 case SCLD_EXISTS:
1617 /*
1618 * Suppose refname is "refs/foo/bar". We just failed
1619 * to create the containing directory, "refs/foo",
1620 * because there was a non-directory in the way. This
1621 * indicates a D/F conflict, probably because of
1622 * another reference such as "refs/foo". There is no
1623 * reason to expect this error to be transitory.
1624 */
1625 if (refs_verify_refname_available(&refs->base, refname,
1626 extras, skip, err)) {
1627 if (mustexist) {
1628 /*
1629 * To the user the relevant error is
1630 * that the "mustexist" reference is
1631 * missing:
1632 */
1633 strbuf_reset(err);
1634 strbuf_addf(err, "unable to resolve reference '%s'",
1635 refname);
1636 } else {
1637 /*
1638 * The error message set by
1639 * verify_refname_available_dir() is OK.
1640 */
1641 ret = TRANSACTION_NAME_CONFLICT;
1642 }
1643 } else {
1644 /*
1645 * The file that is in the way isn't a loose
1646 * reference. Report it as a low-level
1647 * failure.
1648 */
1649 strbuf_addf(err, "unable to create lock file %s.lock; "
1650 "non-directory in the way",
1651 ref_file.buf);
1652 }
1653 goto error_return;
1654 case SCLD_VANISHED:
1655 /* Maybe another process was tidying up. Try again. */
1656 if (--attempts_remaining > 0)
1657 goto retry;
1658 /* fall through */
1659 default:
1660 strbuf_addf(err, "unable to create directory for %s",
1661 ref_file.buf);
1662 goto error_return;
1663 }
1664
1665 if (!lock->lk)
1666 lock->lk = xcalloc(1, sizeof(struct lock_file));
1667
1668 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1669 if (errno == ENOENT && --attempts_remaining > 0) {
1670 /*
1671 * Maybe somebody just deleted one of the
1672 * directories leading to ref_file. Try
1673 * again:
1674 */
1675 goto retry;
1676 } else {
1677 unable_to_lock_message(ref_file.buf, errno, err);
1678 goto error_return;
1679 }
1680 }
1681
1682 /*
1683 * Now we hold the lock and can read the reference without
1684 * fear that its value will change.
1685 */
1686
1687 if (files_read_raw_ref(&refs->base, refname,
1688 lock->old_oid.hash, referent, type)) {
1689 if (errno == ENOENT) {
1690 if (mustexist) {
1691 /* Garden variety missing reference. */
1692 strbuf_addf(err, "unable to resolve reference '%s'",
1693 refname);
1694 goto error_return;
1695 } else {
1696 /*
1697 * Reference is missing, but that's OK. We
1698 * know that there is not a conflict with
1699 * another loose reference because
1700 * (supposing that we are trying to lock
1701 * reference "refs/foo/bar"):
1702 *
1703 * - We were successfully able to create
1704 * the lockfile refs/foo/bar.lock, so we
1705 * know there cannot be a loose reference
1706 * named "refs/foo".
1707 *
1708 * - We got ENOENT and not EISDIR, so we
1709 * know that there cannot be a loose
1710 * reference named "refs/foo/bar/baz".
1711 */
1712 }
1713 } else if (errno == EISDIR) {
1714 /*
1715 * There is a directory in the way. It might have
1716 * contained references that have been deleted. If
1717 * we don't require that the reference already
1718 * exists, try to remove the directory so that it
1719 * doesn't cause trouble when we want to rename the
1720 * lockfile into place later.
1721 */
1722 if (mustexist) {
1723 /* Garden variety missing reference. */
1724 strbuf_addf(err, "unable to resolve reference '%s'",
1725 refname);
1726 goto error_return;
1727 } else if (remove_dir_recursively(&ref_file,
1728 REMOVE_DIR_EMPTY_ONLY)) {
1729 if (verify_refname_available_dir(
1730 refname, extras, skip,
1731 get_loose_refs(refs),
1732 err)) {
1733 /*
1734 * The error message set by
1735 * verify_refname_available() is OK.
1736 */
1737 ret = TRANSACTION_NAME_CONFLICT;
1738 goto error_return;
1739 } else {
1740 /*
1741 * We can't delete the directory,
1742 * but we also don't know of any
1743 * references that it should
1744 * contain.
1745 */
1746 strbuf_addf(err, "there is a non-empty directory '%s' "
1747 "blocking reference '%s'",
1748 ref_file.buf, refname);
1749 goto error_return;
1750 }
1751 }
1752 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1753 strbuf_addf(err, "unable to resolve reference '%s': "
1754 "reference broken", refname);
1755 goto error_return;
1756 } else {
1757 strbuf_addf(err, "unable to resolve reference '%s': %s",
1758 refname, strerror(errno));
1759 goto error_return;
1760 }
1761
1762 /*
1763 * If the ref did not exist and we are creating it,
1764 * make sure there is no existing packed ref whose
1765 * name begins with our refname, nor a packed ref
1766 * whose name is a proper prefix of our refname.
1767 */
1768 if (verify_refname_available_dir(
1769 refname, extras, skip,
1770 get_packed_refs(refs),
1771 err)) {
1772 goto error_return;
1773 }
1774 }
1775
1776 ret = 0;
1777 goto out;
1778
1779 error_return:
1780 unlock_ref(lock);
1781 *lock_p = NULL;
1782
1783 out:
1784 strbuf_release(&ref_file);
1785 return ret;
1786 }
1787
1788 /*
1789 * Peel the entry (if possible) and return its new peel_status. If
1790 * repeel is true, re-peel the entry even if there is an old peeled
1791 * value that is already stored in it.
1792 *
1793 * It is OK to call this function with a packed reference entry that
1794 * might be stale and might even refer to an object that has since
1795 * been garbage-collected. In such a case, if the entry has
1796 * REF_KNOWS_PEELED then leave the status unchanged and return
1797 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1798 */
1799 static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1800 {
1801 enum peel_status status;
1802
1803 if (entry->flag & REF_KNOWS_PEELED) {
1804 if (repeel) {
1805 entry->flag &= ~REF_KNOWS_PEELED;
1806 oidclr(&entry->u.value.peeled);
1807 } else {
1808 return is_null_oid(&entry->u.value.peeled) ?
1809 PEEL_NON_TAG : PEEL_PEELED;
1810 }
1811 }
1812 if (entry->flag & REF_ISBROKEN)
1813 return PEEL_BROKEN;
1814 if (entry->flag & REF_ISSYMREF)
1815 return PEEL_IS_SYMREF;
1816
1817 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1818 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1819 entry->flag |= REF_KNOWS_PEELED;
1820 return status;
1821 }
1822
1823 static int files_peel_ref(struct ref_store *ref_store,
1824 const char *refname, unsigned char *sha1)
1825 {
1826 struct files_ref_store *refs =
1827 files_downcast(ref_store, REF_STORE_READ | REF_STORE_ODB,
1828 "peel_ref");
1829 int flag;
1830 unsigned char base[20];
1831
1832 if (current_ref_iter && current_ref_iter->refname == refname) {
1833 struct object_id peeled;
1834
1835 if (ref_iterator_peel(current_ref_iter, &peeled))
1836 return -1;
1837 hashcpy(sha1, peeled.hash);
1838 return 0;
1839 }
1840
1841 if (refs_read_ref_full(ref_store, refname,
1842 RESOLVE_REF_READING, base, &flag))
1843 return -1;
1844
1845 /*
1846 * If the reference is packed, read its ref_entry from the
1847 * cache in the hope that we already know its peeled value.
1848 * We only try this optimization on packed references because
1849 * (a) forcing the filling of the loose reference cache could
1850 * be expensive and (b) loose references anyway usually do not
1851 * have REF_KNOWS_PEELED.
1852 */
1853 if (flag & REF_ISPACKED) {
1854 struct ref_entry *r = get_packed_ref(refs, refname);
1855 if (r) {
1856 if (peel_entry(r, 0))
1857 return -1;
1858 hashcpy(sha1, r->u.value.peeled.hash);
1859 return 0;
1860 }
1861 }
1862
1863 return peel_object(base, sha1);
1864 }
1865
1866 struct files_ref_iterator {
1867 struct ref_iterator base;
1868
1869 struct packed_ref_cache *packed_ref_cache;
1870 struct ref_iterator *iter0;
1871 unsigned int flags;
1872 };
1873
1874 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
1875 {
1876 struct files_ref_iterator *iter =
1877 (struct files_ref_iterator *)ref_iterator;
1878 int ok;
1879
1880 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
1881 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
1882 ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
1883 continue;
1884
1885 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
1886 !ref_resolves_to_object(iter->iter0->refname,
1887 iter->iter0->oid,
1888 iter->iter0->flags))
1889 continue;
1890
1891 iter->base.refname = iter->iter0->refname;
1892 iter->base.oid = iter->iter0->oid;
1893 iter->base.flags = iter->iter0->flags;
1894 return ITER_OK;
1895 }
1896
1897 iter->iter0 = NULL;
1898 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
1899 ok = ITER_ERROR;
1900
1901 return ok;
1902 }
1903
1904 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
1905 struct object_id *peeled)
1906 {
1907 struct files_ref_iterator *iter =
1908 (struct files_ref_iterator *)ref_iterator;
1909
1910 return ref_iterator_peel(iter->iter0, peeled);
1911 }
1912
1913 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
1914 {
1915 struct files_ref_iterator *iter =
1916 (struct files_ref_iterator *)ref_iterator;
1917 int ok = ITER_DONE;
1918
1919 if (iter->iter0)
1920 ok = ref_iterator_abort(iter->iter0);
1921
1922 release_packed_ref_cache(iter->packed_ref_cache);
1923 base_ref_iterator_free(ref_iterator);
1924 return ok;
1925 }
1926
1927 static struct ref_iterator_vtable files_ref_iterator_vtable = {
1928 files_ref_iterator_advance,
1929 files_ref_iterator_peel,
1930 files_ref_iterator_abort
1931 };
1932
1933 static struct ref_iterator *files_ref_iterator_begin(
1934 struct ref_store *ref_store,
1935 const char *prefix, unsigned int flags)
1936 {
1937 struct files_ref_store *refs;
1938 struct ref_dir *loose_dir, *packed_dir;
1939 struct ref_iterator *loose_iter, *packed_iter;
1940 struct files_ref_iterator *iter;
1941 struct ref_iterator *ref_iterator;
1942
1943 if (ref_paranoia < 0)
1944 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1945 if (ref_paranoia)
1946 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1947
1948 refs = files_downcast(ref_store,
1949 REF_STORE_READ | (ref_paranoia ? 0 : REF_STORE_ODB),
1950 "ref_iterator_begin");
1951
1952 iter = xcalloc(1, sizeof(*iter));
1953 ref_iterator = &iter->base;
1954 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
1955
1956 /*
1957 * We must make sure that all loose refs are read before
1958 * accessing the packed-refs file; this avoids a race
1959 * condition if loose refs are migrated to the packed-refs
1960 * file by a simultaneous process, but our in-memory view is
1961 * from before the migration. We ensure this as follows:
1962 * First, we call prime_ref_dir(), which pre-reads the loose
1963 * references for the subtree into the cache. (If they've
1964 * already been read, that's OK; we only need to guarantee
1965 * that they're read before the packed refs, not *how much*
1966 * before.) After that, we call get_packed_ref_cache(), which
1967 * internally checks whether the packed-ref cache is up to
1968 * date with what is on disk, and re-reads it if not.
1969 */
1970
1971 loose_dir = get_loose_refs(refs);
1972
1973 if (prefix && *prefix)
1974 loose_dir = find_containing_dir(loose_dir, prefix, 0);
1975
1976 if (loose_dir) {
1977 prime_ref_dir(loose_dir);
1978 loose_iter = cache_ref_iterator_begin(loose_dir);
1979 } else {
1980 /* There's nothing to iterate over. */
1981 loose_iter = empty_ref_iterator_begin();
1982 }
1983
1984 iter->packed_ref_cache = get_packed_ref_cache(refs);
1985 acquire_packed_ref_cache(iter->packed_ref_cache);
1986 packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
1987
1988 if (prefix && *prefix)
1989 packed_dir = find_containing_dir(packed_dir, prefix, 0);
1990
1991 if (packed_dir) {
1992 packed_iter = cache_ref_iterator_begin(packed_dir);
1993 } else {
1994 /* There's nothing to iterate over. */
1995 packed_iter = empty_ref_iterator_begin();
1996 }
1997
1998 iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
1999 iter->flags = flags;
2000
2001 return ref_iterator;
2002 }
2003
2004 /*
2005 * Verify that the reference locked by lock has the value old_sha1.
2006 * Fail if the reference doesn't exist and mustexist is set. Return 0
2007 * on success. On error, write an error message to err, set errno, and
2008 * return a negative value.
2009 */
2010 static int verify_lock(struct ref_store *ref_store, struct ref_lock *lock,
2011 const unsigned char *old_sha1, int mustexist,
2012 struct strbuf *err)
2013 {
2014 assert(err);
2015
2016 if (refs_read_ref_full(ref_store, lock->ref_name,
2017 mustexist ? RESOLVE_REF_READING : 0,
2018 lock->old_oid.hash, NULL)) {
2019 if (old_sha1) {
2020 int save_errno = errno;
2021 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
2022 errno = save_errno;
2023 return -1;
2024 } else {
2025 oidclr(&lock->old_oid);
2026 return 0;
2027 }
2028 }
2029 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
2030 strbuf_addf(err, "ref '%s' is at %s but expected %s",
2031 lock->ref_name,
2032 oid_to_hex(&lock->old_oid),
2033 sha1_to_hex(old_sha1));
2034 errno = EBUSY;
2035 return -1;
2036 }
2037 return 0;
2038 }
2039
2040 static int remove_empty_directories(struct strbuf *path)
2041 {
2042 /*
2043 * we want to create a file but there is a directory there;
2044 * if that is an empty directory (or a directory that contains
2045 * only empty directories), remove them.
2046 */
2047 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
2048 }
2049
2050 static int create_reflock(const char *path, void *cb)
2051 {
2052 struct lock_file *lk = cb;
2053
2054 return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0;
2055 }
2056
2057 /*
2058 * Locks a ref returning the lock on success and NULL on failure.
2059 * On failure errno is set to something meaningful.
2060 */
2061 static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
2062 const char *refname,
2063 const unsigned char *old_sha1,
2064 const struct string_list *extras,
2065 const struct string_list *skip,
2066 unsigned int flags, int *type,
2067 struct strbuf *err)
2068 {
2069 struct strbuf ref_file = STRBUF_INIT;
2070 struct ref_lock *lock;
2071 int last_errno = 0;
2072 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2073 int resolve_flags = RESOLVE_REF_NO_RECURSE;
2074 int resolved;
2075
2076 files_assert_main_repository(refs, "lock_ref_sha1_basic");
2077 assert(err);
2078
2079 lock = xcalloc(1, sizeof(struct ref_lock));
2080
2081 if (mustexist)
2082 resolve_flags |= RESOLVE_REF_READING;
2083 if (flags & REF_DELETING)
2084 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
2085
2086 files_ref_path(refs, &ref_file, refname);
2087 resolved = !!refs_resolve_ref_unsafe(&refs->base,
2088 refname, resolve_flags,
2089 lock->old_oid.hash, type);
2090 if (!resolved && errno == EISDIR) {
2091 /*
2092 * we are trying to lock foo but we used to
2093 * have foo/bar which now does not exist;
2094 * it is normal for the empty directory 'foo'
2095 * to remain.
2096 */
2097 if (remove_empty_directories(&ref_file)) {
2098 last_errno = errno;
2099 if (!verify_refname_available_dir(
2100 refname, extras, skip,
2101 get_loose_refs(refs), err))
2102 strbuf_addf(err, "there are still refs under '%s'",
2103 refname);
2104 goto error_return;
2105 }
2106 resolved = !!refs_resolve_ref_unsafe(&refs->base,
2107 refname, resolve_flags,
2108 lock->old_oid.hash, type);
2109 }
2110 if (!resolved) {
2111 last_errno = errno;
2112 if (last_errno != ENOTDIR ||
2113 !verify_refname_available_dir(
2114 refname, extras, skip,
2115 get_loose_refs(refs), err))
2116 strbuf_addf(err, "unable to resolve reference '%s': %s",
2117 refname, strerror(last_errno));
2118
2119 goto error_return;
2120 }
2121
2122 /*
2123 * If the ref did not exist and we are creating it, make sure
2124 * there is no existing packed ref whose name begins with our
2125 * refname, nor a packed ref whose name is a proper prefix of
2126 * our refname.
2127 */
2128 if (is_null_oid(&lock->old_oid) &&
2129 verify_refname_available_dir(refname, extras, skip,
2130 get_packed_refs(refs),
2131 err)) {
2132 last_errno = ENOTDIR;
2133 goto error_return;
2134 }
2135
2136 lock->lk = xcalloc(1, sizeof(struct lock_file));
2137
2138 lock->ref_name = xstrdup(refname);
2139
2140 if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
2141 last_errno = errno;
2142 unable_to_lock_message(ref_file.buf, errno, err);
2143 goto error_return;
2144 }
2145
2146 if (verify_lock(&refs->base, lock, old_sha1, mustexist, err)) {
2147 last_errno = errno;
2148 goto error_return;
2149 }
2150 goto out;
2151
2152 error_return:
2153 unlock_ref(lock);
2154 lock = NULL;
2155
2156 out:
2157 strbuf_release(&ref_file);
2158 errno = last_errno;
2159 return lock;
2160 }
2161
2162 /*
2163 * Write an entry to the packed-refs file for the specified refname.
2164 * If peeled is non-NULL, write it as the entry's peeled value.
2165 */
2166 static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2167 unsigned char *peeled)
2168 {
2169 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2170 if (peeled)
2171 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2172 }
2173
2174 /*
2175 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2176 */
2177 static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2178 {
2179 enum peel_status peel_status = peel_entry(entry, 0);
2180
2181 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2182 error("internal error: %s is not a valid packed reference!",
2183 entry->name);
2184 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2185 peel_status == PEEL_PEELED ?
2186 entry->u.value.peeled.hash : NULL);
2187 return 0;
2188 }
2189
2190 /*
2191 * Lock the packed-refs file for writing. Flags is passed to
2192 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2193 * errno appropriately and return a nonzero value.
2194 */
2195 static int lock_packed_refs(struct files_ref_store *refs, int flags)
2196 {
2197 static int timeout_configured = 0;
2198 static int timeout_value = 1000;
2199 struct packed_ref_cache *packed_ref_cache;
2200
2201 files_assert_main_repository(refs, "lock_packed_refs");
2202
2203 if (!timeout_configured) {
2204 git_config_get_int("core.packedrefstimeout", &timeout_value);
2205 timeout_configured = 1;
2206 }
2207
2208 if (hold_lock_file_for_update_timeout(
2209 &packlock, files_packed_refs_path(refs),
2210 flags, timeout_value) < 0)
2211 return -1;
2212 /*
2213 * Get the current packed-refs while holding the lock. If the
2214 * packed-refs file has been modified since we last read it,
2215 * this will automatically invalidate the cache and re-read
2216 * the packed-refs file.
2217 */
2218 packed_ref_cache = get_packed_ref_cache(refs);
2219 packed_ref_cache->lock = &packlock;
2220 /* Increment the reference count to prevent it from being freed: */
2221 acquire_packed_ref_cache(packed_ref_cache);
2222 return 0;
2223 }
2224
2225 /*
2226 * Write the current version of the packed refs cache from memory to
2227 * disk. The packed-refs file must already be locked for writing (see
2228 * lock_packed_refs()). Return zero on success. On errors, set errno
2229 * and return a nonzero value
2230 */
2231 static int commit_packed_refs(struct files_ref_store *refs)
2232 {
2233 struct packed_ref_cache *packed_ref_cache =
2234 get_packed_ref_cache(refs);
2235 int error = 0;
2236 int save_errno = 0;
2237 FILE *out;
2238
2239 files_assert_main_repository(refs, "commit_packed_refs");
2240
2241 if (!packed_ref_cache->lock)
2242 die("internal error: packed-refs not locked");
2243
2244 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2245 if (!out)
2246 die_errno("unable to fdopen packed-refs descriptor");
2247
2248 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2249 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2250 0, write_packed_entry_fn, out);
2251
2252 if (commit_lock_file(packed_ref_cache->lock)) {
2253 save_errno = errno;
2254 error = -1;
2255 }
2256 packed_ref_cache->lock = NULL;
2257 release_packed_ref_cache(packed_ref_cache);
2258 errno = save_errno;
2259 return error;
2260 }
2261
2262 /*
2263 * Rollback the lockfile for the packed-refs file, and discard the
2264 * in-memory packed reference cache. (The packed-refs file will be
2265 * read anew if it is needed again after this function is called.)
2266 */
2267 static void rollback_packed_refs(struct files_ref_store *refs)
2268 {
2269 struct packed_ref_cache *packed_ref_cache =
2270 get_packed_ref_cache(refs);
2271
2272 files_assert_main_repository(refs, "rollback_packed_refs");
2273
2274 if (!packed_ref_cache->lock)
2275 die("internal error: packed-refs not locked");
2276 rollback_lock_file(packed_ref_cache->lock);
2277 packed_ref_cache->lock = NULL;
2278 release_packed_ref_cache(packed_ref_cache);
2279 clear_packed_ref_cache(refs);
2280 }
2281
2282 struct ref_to_prune {
2283 struct ref_to_prune *next;
2284 unsigned char sha1[20];
2285 char name[FLEX_ARRAY];
2286 };
2287
2288 struct pack_refs_cb_data {
2289 unsigned int flags;
2290 struct ref_dir *packed_refs;
2291 struct ref_to_prune *ref_to_prune;
2292 };
2293
2294 /*
2295 * An each_ref_entry_fn that is run over loose references only. If
2296 * the loose reference can be packed, add an entry in the packed ref
2297 * cache. If the reference should be pruned, also add it to
2298 * ref_to_prune in the pack_refs_cb_data.
2299 */
2300 static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2301 {
2302 struct pack_refs_cb_data *cb = cb_data;
2303 enum peel_status peel_status;
2304 struct ref_entry *packed_entry;
2305 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2306
2307 /* Do not pack per-worktree refs: */
2308 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2309 return 0;
2310
2311 /* ALWAYS pack tags */
2312 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2313 return 0;
2314
2315 /* Do not pack symbolic or broken refs: */
2316 if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
2317 return 0;
2318
2319 /* Add a packed ref cache entry equivalent to the loose entry. */
2320 peel_status = peel_entry(entry, 1);
2321 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2322 die("internal error peeling reference %s (%s)",
2323 entry->name, oid_to_hex(&entry->u.value.oid));
2324 packed_entry = find_ref(cb->packed_refs, entry->name);
2325 if (packed_entry) {
2326 /* Overwrite existing packed entry with info from loose entry */
2327 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2328 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2329 } else {
2330 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2331 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2332 add_ref(cb->packed_refs, packed_entry);
2333 }
2334 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2335
2336 /* Schedule the loose reference for pruning if requested. */
2337 if ((cb->flags & PACK_REFS_PRUNE)) {
2338 struct ref_to_prune *n;
2339 FLEX_ALLOC_STR(n, name, entry->name);
2340 hashcpy(n->sha1, entry->u.value.oid.hash);
2341 n->next = cb->ref_to_prune;
2342 cb->ref_to_prune = n;
2343 }
2344 return 0;
2345 }
2346
2347 enum {
2348 REMOVE_EMPTY_PARENTS_REF = 0x01,
2349 REMOVE_EMPTY_PARENTS_REFLOG = 0x02
2350 };
2351
2352 /*
2353 * Remove empty parent directories associated with the specified
2354 * reference and/or its reflog, but spare [logs/]refs/ and immediate
2355 * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
2356 * REMOVE_EMPTY_PARENTS_REFLOG.
2357 */
2358 static void try_remove_empty_parents(struct files_ref_store *refs,
2359 const char *refname,
2360 unsigned int flags)
2361 {
2362 struct strbuf buf = STRBUF_INIT;
2363 struct strbuf sb = STRBUF_INIT;
2364 char *p, *q;
2365 int i;
2366
2367 strbuf_addstr(&buf, refname);
2368 p = buf.buf;
2369 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2370 while (*p && *p != '/')
2371 p++;
2372 /* tolerate duplicate slashes; see check_refname_format() */
2373 while (*p == '/')
2374 p++;
2375 }
2376 q = buf.buf + buf.len;
2377 while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
2378 while (q > p && *q != '/')
2379 q--;
2380 while (q > p && *(q-1) == '/')
2381 q--;
2382 if (q == p)
2383 break;
2384 strbuf_setlen(&buf, q - buf.buf);
2385
2386 strbuf_reset(&sb);
2387 files_ref_path(refs, &sb, buf.buf);
2388 if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
2389 flags &= ~REMOVE_EMPTY_PARENTS_REF;
2390
2391 strbuf_reset(&sb);
2392 files_reflog_path(refs, &sb, buf.buf);
2393 if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
2394 flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
2395 }
2396 strbuf_release(&buf);
2397 strbuf_release(&sb);
2398 }
2399
2400 /* make sure nobody touched the ref, and unlink */
2401 static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
2402 {
2403 struct ref_transaction *transaction;
2404 struct strbuf err = STRBUF_INIT;
2405
2406 if (check_refname_format(r->name, 0))
2407 return;
2408
2409 transaction = ref_store_transaction_begin(&refs->base, &err);
2410 if (!transaction ||
2411 ref_transaction_delete(transaction, r->name, r->sha1,
2412 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
2413 ref_transaction_commit(transaction, &err)) {
2414 ref_transaction_free(transaction);
2415 error("%s", err.buf);
2416 strbuf_release(&err);
2417 return;
2418 }
2419 ref_transaction_free(transaction);
2420 strbuf_release(&err);
2421 }
2422
2423 static void prune_refs(struct files_ref_store *refs, struct ref_to_prune *r)
2424 {
2425 while (r) {
2426 prune_ref(refs, r);
2427 r = r->next;
2428 }
2429 }
2430
2431 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
2432 {
2433 struct files_ref_store *refs =
2434 files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
2435 "pack_refs");
2436 struct pack_refs_cb_data cbdata;
2437
2438 memset(&cbdata, 0, sizeof(cbdata));
2439 cbdata.flags = flags;
2440
2441 lock_packed_refs(refs, LOCK_DIE_ON_ERROR);
2442 cbdata.packed_refs = get_packed_refs(refs);
2443
2444 do_for_each_entry_in_dir(get_loose_refs(refs), 0,
2445 pack_if_possible_fn, &cbdata);
2446
2447 if (commit_packed_refs(refs))
2448 die_errno("unable to overwrite old ref-pack file");
2449
2450 prune_refs(refs, cbdata.ref_to_prune);
2451 return 0;
2452 }
2453
2454 /*
2455 * Rewrite the packed-refs file, omitting any refs listed in
2456 * 'refnames'. On error, leave packed-refs unchanged, write an error
2457 * message to 'err', and return a nonzero value.
2458 *
2459 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2460 */
2461 static int repack_without_refs(struct files_ref_store *refs,
2462 struct string_list *refnames, struct strbuf *err)
2463 {
2464 struct ref_dir *packed;
2465 struct string_list_item *refname;
2466 int ret, needs_repacking = 0, removed = 0;
2467
2468 files_assert_main_repository(refs, "repack_without_refs");
2469 assert(err);
2470
2471 /* Look for a packed ref */
2472 for_each_string_list_item(refname, refnames) {
2473 if (get_packed_ref(refs, refname->string)) {
2474 needs_repacking = 1;
2475 break;
2476 }
2477 }
2478
2479 /* Avoid locking if we have nothing to do */
2480 if (!needs_repacking)
2481 return 0; /* no refname exists in packed refs */
2482
2483 if (lock_packed_refs(refs, 0)) {
2484 unable_to_lock_message(files_packed_refs_path(refs), errno, err);
2485 return -1;
2486 }
2487 packed = get_packed_refs(refs);
2488
2489 /* Remove refnames from the cache */
2490 for_each_string_list_item(refname, refnames)
2491 if (remove_entry(packed, refname->string) != -1)
2492 removed = 1;
2493 if (!removed) {
2494 /*
2495 * All packed entries disappeared while we were
2496 * acquiring the lock.
2497 */
2498 rollback_packed_refs(refs);
2499 return 0;
2500 }
2501
2502 /* Write what remains */
2503 ret = commit_packed_refs(refs);
2504 if (ret)
2505 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2506 strerror(errno));
2507 return ret;
2508 }
2509
2510 static int files_delete_refs(struct ref_store *ref_store,
2511 struct string_list *refnames, unsigned int flags)
2512 {
2513 struct files_ref_store *refs =
2514 files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
2515 struct strbuf err = STRBUF_INIT;
2516 int i, result = 0;
2517
2518 if (!refnames->nr)
2519 return 0;
2520
2521 result = repack_without_refs(refs, refnames, &err);
2522 if (result) {
2523 /*
2524 * If we failed to rewrite the packed-refs file, then
2525 * it is unsafe to try to remove loose refs, because
2526 * doing so might expose an obsolete packed value for
2527 * a reference that might even point at an object that
2528 * has been garbage collected.
2529 */
2530 if (refnames->nr == 1)
2531 error(_("could not delete reference %s: %s"),
2532 refnames->items[0].string, err.buf);
2533 else
2534 error(_("could not delete references: %s"), err.buf);
2535
2536 goto out;
2537 }
2538
2539 for (i = 0; i < refnames->nr; i++) {
2540 const char *refname = refnames->items[i].string;
2541
2542 if (refs_delete_ref(&refs->base, NULL, refname, NULL, flags))
2543 result |= error(_("could not remove reference %s"), refname);
2544 }
2545
2546 out:
2547 strbuf_release(&err);
2548 return result;
2549 }
2550
2551 /*
2552 * People using contrib's git-new-workdir have .git/logs/refs ->
2553 * /some/other/path/.git/logs/refs, and that may live on another device.
2554 *
2555 * IOW, to avoid cross device rename errors, the temporary renamed log must
2556 * live into logs/refs.
2557 */
2558 #define TMP_RENAMED_LOG "refs/.tmp-renamed-log"
2559
2560 struct rename_cb {
2561 const char *tmp_renamed_log;
2562 int true_errno;
2563 };
2564
2565 static int rename_tmp_log_callback(const char *path, void *cb_data)
2566 {
2567 struct rename_cb *cb = cb_data;
2568
2569 if (rename(cb->tmp_renamed_log, path)) {
2570 /*
2571 * rename(a, b) when b is an existing directory ought
2572 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
2573 * Sheesh. Record the true errno for error reporting,
2574 * but report EISDIR to raceproof_create_file() so
2575 * that it knows to retry.
2576 */
2577 cb->true_errno = errno;
2578 if (errno == ENOTDIR)
2579 errno = EISDIR;
2580 return -1;
2581 } else {
2582 return 0;
2583 }
2584 }
2585
2586 static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
2587 {
2588 struct strbuf path = STRBUF_INIT;
2589 struct strbuf tmp = STRBUF_INIT;
2590 struct rename_cb cb;
2591 int ret;
2592
2593 files_reflog_path(refs, &path, newrefname);
2594 files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
2595 cb.tmp_renamed_log = tmp.buf;
2596 ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
2597 if (ret) {
2598 if (errno == EISDIR)
2599 error("directory not empty: %s", path.buf);
2600 else
2601 error("unable to move logfile %s to %s: %s",
2602 tmp.buf, path.buf,
2603 strerror(cb.true_errno));
2604 }
2605
2606 strbuf_release(&path);
2607 strbuf_release(&tmp);
2608 return ret;
2609 }
2610
2611 static int files_verify_refname_available(struct ref_store *ref_store,
2612 const char *newname,
2613 const struct string_list *extras,
2614 const struct string_list *skip,
2615 struct strbuf *err)
2616 {
2617 struct files_ref_store *refs =
2618 files_downcast(ref_store, REF_STORE_READ, "verify_refname_available");
2619 struct ref_dir *packed_refs = get_packed_refs(refs);
2620 struct ref_dir *loose_refs = get_loose_refs(refs);
2621
2622 if (verify_refname_available_dir(newname, extras, skip,
2623 packed_refs, err) ||
2624 verify_refname_available_dir(newname, extras, skip,
2625 loose_refs, err))
2626 return -1;
2627
2628 return 0;
2629 }
2630
2631 static int write_ref_to_lockfile(struct ref_lock *lock,
2632 const unsigned char *sha1, struct strbuf *err);
2633 static int commit_ref_update(struct files_ref_store *refs,
2634 struct ref_lock *lock,
2635 const unsigned char *sha1, const char *logmsg,
2636 struct strbuf *err);
2637
2638 static int files_rename_ref(struct ref_store *ref_store,
2639 const char *oldrefname, const char *newrefname,
2640 const char *logmsg)
2641 {
2642 struct files_ref_store *refs =
2643 files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
2644 unsigned char sha1[20], orig_sha1[20];
2645 int flag = 0, logmoved = 0;
2646 struct ref_lock *lock;
2647 struct stat loginfo;
2648 struct strbuf sb_oldref = STRBUF_INIT;
2649 struct strbuf sb_newref = STRBUF_INIT;
2650 struct strbuf tmp_renamed_log = STRBUF_INIT;
2651 int log, ret;
2652 struct strbuf err = STRBUF_INIT;
2653
2654 files_reflog_path(refs, &sb_oldref, oldrefname);
2655 files_reflog_path(refs, &sb_newref, newrefname);
2656 files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
2657
2658 log = !lstat(sb_oldref.buf, &loginfo);
2659 if (log && S_ISLNK(loginfo.st_mode)) {
2660 ret = error("reflog for %s is a symlink", oldrefname);
2661 goto out;
2662 }
2663
2664 if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
2665 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2666 orig_sha1, &flag)) {
2667 ret = error("refname %s not found", oldrefname);
2668 goto out;
2669 }
2670
2671 if (flag & REF_ISSYMREF) {
2672 ret = error("refname %s is a symbolic ref, renaming it is not supported",
2673 oldrefname);
2674 goto out;
2675 }
2676 if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
2677 ret = 1;
2678 goto out;
2679 }
2680
2681 if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
2682 ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
2683 oldrefname, strerror(errno));
2684 goto out;
2685 }
2686
2687 if (refs_delete_ref(&refs->base, logmsg, oldrefname,
2688 orig_sha1, REF_NODEREF)) {
2689 error("unable to delete old %s", oldrefname);
2690 goto rollback;
2691 }
2692
2693 /*
2694 * Since we are doing a shallow lookup, sha1 is not the
2695 * correct value to pass to delete_ref as old_sha1. But that
2696 * doesn't matter, because an old_sha1 check wouldn't add to
2697 * the safety anyway; we want to delete the reference whatever
2698 * its current value.
2699 */
2700 if (!refs_read_ref_full(&refs->base, newrefname,
2701 RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2702 sha1, NULL) &&
2703 refs_delete_ref(&refs->base, NULL, newrefname,
2704 NULL, REF_NODEREF)) {
2705 if (errno == EISDIR) {
2706 struct strbuf path = STRBUF_INIT;
2707 int result;
2708
2709 files_ref_path(refs, &path, newrefname);
2710 result = remove_empty_directories(&path);
2711 strbuf_release(&path);
2712
2713 if (result) {
2714 error("Directory not empty: %s", newrefname);
2715 goto rollback;
2716 }
2717 } else {
2718 error("unable to delete existing %s", newrefname);
2719 goto rollback;
2720 }
2721 }
2722
2723 if (log && rename_tmp_log(refs, newrefname))
2724 goto rollback;
2725
2726 logmoved = log;
2727
2728 lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
2729 REF_NODEREF, NULL, &err);
2730 if (!lock) {
2731 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2732 strbuf_release(&err);
2733 goto rollback;
2734 }
2735 hashcpy(lock->old_oid.hash, orig_sha1);
2736
2737 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2738 commit_ref_update(refs, lock, orig_sha1, logmsg, &err)) {
2739 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2740 strbuf_release(&err);
2741 goto rollback;
2742 }
2743
2744 ret = 0;
2745 goto out;
2746
2747 rollback:
2748 lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
2749 REF_NODEREF, NULL, &err);
2750 if (!lock) {
2751 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2752 strbuf_release(&err);
2753 goto rollbacklog;
2754 }
2755
2756 flag = log_all_ref_updates;
2757 log_all_ref_updates = LOG_REFS_NONE;
2758 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2759 commit_ref_update(refs, lock, orig_sha1, NULL, &err)) {
2760 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2761 strbuf_release(&err);
2762 }
2763 log_all_ref_updates = flag;
2764
2765 rollbacklog:
2766 if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
2767 error("unable to restore logfile %s from %s: %s",
2768 oldrefname, newrefname, strerror(errno));
2769 if (!logmoved && log &&
2770 rename(tmp_renamed_log.buf, sb_oldref.buf))
2771 error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
2772 oldrefname, strerror(errno));
2773 ret = 1;
2774 out:
2775 strbuf_release(&sb_newref);
2776 strbuf_release(&sb_oldref);
2777 strbuf_release(&tmp_renamed_log);
2778
2779 return ret;
2780 }
2781
2782 static int close_ref(struct ref_lock *lock)
2783 {
2784 if (close_lock_file(lock->lk))
2785 return -1;
2786 return 0;
2787 }
2788
2789 static int commit_ref(struct ref_lock *lock)
2790 {
2791 char *path = get_locked_file_path(lock->lk);
2792 struct stat st;
2793
2794 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2795 /*
2796 * There is a directory at the path we want to rename
2797 * the lockfile to. Hopefully it is empty; try to
2798 * delete it.
2799 */
2800 size_t len = strlen(path);
2801 struct strbuf sb_path = STRBUF_INIT;
2802
2803 strbuf_attach(&sb_path, path, len, len);
2804
2805 /*
2806 * If this fails, commit_lock_file() will also fail
2807 * and will report the problem.
2808 */
2809 remove_empty_directories(&sb_path);
2810 strbuf_release(&sb_path);
2811 } else {
2812 free(path);
2813 }
2814
2815 if (commit_lock_file(lock->lk))
2816 return -1;
2817 return 0;
2818 }
2819
2820 static int open_or_create_logfile(const char *path, void *cb)
2821 {
2822 int *fd = cb;
2823
2824 *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
2825 return (*fd < 0) ? -1 : 0;
2826 }
2827
2828 /*
2829 * Create a reflog for a ref. If force_create = 0, only create the
2830 * reflog for certain refs (those for which should_autocreate_reflog
2831 * returns non-zero). Otherwise, create it regardless of the reference
2832 * name. If the logfile already existed or was created, return 0 and
2833 * set *logfd to the file descriptor opened for appending to the file.
2834 * If no logfile exists and we decided not to create one, return 0 and
2835 * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
2836 * return -1.
2837 */
2838 static int log_ref_setup(struct files_ref_store *refs,
2839 const char *refname, int force_create,
2840 int *logfd, struct strbuf *err)
2841 {
2842 struct strbuf logfile_sb = STRBUF_INIT;
2843 char *logfile;
2844
2845 files_reflog_path(refs, &logfile_sb, refname);
2846 logfile = strbuf_detach(&logfile_sb, NULL);
2847
2848 if (force_create || should_autocreate_reflog(refname)) {
2849 if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
2850 if (errno == ENOENT)
2851 strbuf_addf(err, "unable to create directory for '%s': "
2852 "%s", logfile, strerror(errno));
2853 else if (errno == EISDIR)
2854 strbuf_addf(err, "there are still logs under '%s'",
2855 logfile);
2856 else
2857 strbuf_addf(err, "unable to append to '%s': %s",
2858 logfile, strerror(errno));
2859
2860 goto error;
2861 }
2862 } else {
2863 *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
2864 if (*logfd < 0) {
2865 if (errno == ENOENT || errno == EISDIR) {
2866 /*
2867 * The logfile doesn't already exist,
2868 * but that is not an error; it only
2869 * means that we won't write log
2870 * entries to it.
2871 */
2872 ;
2873 } else {
2874 strbuf_addf(err, "unable to append to '%s': %s",
2875 logfile, strerror(errno));
2876 goto error;
2877 }
2878 }
2879 }
2880
2881 if (*logfd >= 0)
2882 adjust_shared_perm(logfile);
2883
2884 free(logfile);
2885 return 0;
2886
2887 error:
2888 free(logfile);
2889 return -1;
2890 }
2891
2892 static int files_create_reflog(struct ref_store *ref_store,
2893 const char *refname, int force_create,
2894 struct strbuf *err)
2895 {
2896 struct files_ref_store *refs =
2897 files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
2898 int fd;
2899
2900 if (log_ref_setup(refs, refname, force_create, &fd, err))
2901 return -1;
2902
2903 if (fd >= 0)
2904 close(fd);
2905
2906 return 0;
2907 }
2908
2909 static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2910 const unsigned char *new_sha1,
2911 const char *committer, const char *msg)
2912 {
2913 int msglen, written;
2914 unsigned maxlen, len;
2915 char *logrec;
2916
2917 msglen = msg ? strlen(msg) : 0;
2918 maxlen = strlen(committer) + msglen + 100;
2919 logrec = xmalloc(maxlen);
2920 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2921 sha1_to_hex(old_sha1),
2922 sha1_to_hex(new_sha1),
2923 committer);
2924 if (msglen)
2925 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2926
2927 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2928 free(logrec);
2929 if (written != len)
2930 return -1;
2931
2932 return 0;
2933 }
2934
2935 static int files_log_ref_write(struct files_ref_store *refs,
2936 const char *refname, const unsigned char *old_sha1,
2937 const unsigned char *new_sha1, const char *msg,
2938 int flags, struct strbuf *err)
2939 {
2940 int logfd, result;
2941
2942 if (log_all_ref_updates == LOG_REFS_UNSET)
2943 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
2944
2945 result = log_ref_setup(refs, refname,
2946 flags & REF_FORCE_CREATE_REFLOG,
2947 &logfd, err);
2948
2949 if (result)
2950 return result;
2951
2952 if (logfd < 0)
2953 return 0;
2954 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2955 git_committer_info(0), msg);
2956 if (result) {
2957 struct strbuf sb = STRBUF_INIT;
2958 int save_errno = errno;
2959
2960 files_reflog_path(refs, &sb, refname);
2961 strbuf_addf(err, "unable to append to '%s': %s",
2962 sb.buf, strerror(save_errno));
2963 strbuf_release(&sb);
2964 close(logfd);
2965 return -1;
2966 }
2967 if (close(logfd)) {
2968 struct strbuf sb = STRBUF_INIT;
2969 int save_errno = errno;
2970
2971 files_reflog_path(refs, &sb, refname);
2972 strbuf_addf(err, "unable to append to '%s': %s",
2973 sb.buf, strerror(save_errno));
2974 strbuf_release(&sb);
2975 return -1;
2976 }
2977 return 0;
2978 }
2979
2980 /*
2981 * Write sha1 into the open lockfile, then close the lockfile. On
2982 * errors, rollback the lockfile, fill in *err and
2983 * return -1.
2984 */
2985 static int write_ref_to_lockfile(struct ref_lock *lock,
2986 const unsigned char *sha1, struct strbuf *err)
2987 {
2988 static char term = '\n';
2989 struct object *o;
2990 int fd;
2991
2992 o = parse_object(sha1);
2993 if (!o) {
2994 strbuf_addf(err,
2995 "trying to write ref '%s' with nonexistent object %s",
2996 lock->ref_name, sha1_to_hex(sha1));
2997 unlock_ref(lock);
2998 return -1;
2999 }
3000 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
3001 strbuf_addf(err,
3002 "trying to write non-commit object %s to branch '%s'",
3003 sha1_to_hex(sha1), lock->ref_name);
3004 unlock_ref(lock);
3005 return -1;
3006 }
3007 fd = get_lock_file_fd(lock->lk);
3008 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
3009 write_in_full(fd, &term, 1) != 1 ||
3010 close_ref(lock) < 0) {
3011 strbuf_addf(err,
3012 "couldn't write '%s'", get_lock_file_path(lock->lk));
3013 unlock_ref(lock);
3014 return -1;
3015 }
3016 return 0;
3017 }
3018
3019 /*
3020 * Commit a change to a loose reference that has already been written
3021 * to the loose reference lockfile. Also update the reflogs if
3022 * necessary, using the specified lockmsg (which can be NULL).
3023 */
3024 static int commit_ref_update(struct files_ref_store *refs,
3025 struct ref_lock *lock,
3026 const unsigned char *sha1, const char *logmsg,
3027 struct strbuf *err)
3028 {
3029 files_assert_main_repository(refs, "commit_ref_update");
3030
3031 clear_loose_ref_cache(refs);
3032 if (files_log_ref_write(refs, lock->ref_name,
3033 lock->old_oid.hash, sha1,
3034 logmsg, 0, err)) {
3035 char *old_msg = strbuf_detach(err, NULL);
3036 strbuf_addf(err, "cannot update the ref '%s': %s",
3037 lock->ref_name, old_msg);
3038 free(old_msg);
3039 unlock_ref(lock);
3040 return -1;
3041 }
3042
3043 if (strcmp(lock->ref_name, "HEAD") != 0) {
3044 /*
3045 * Special hack: If a branch is updated directly and HEAD
3046 * points to it (may happen on the remote side of a push
3047 * for example) then logically the HEAD reflog should be
3048 * updated too.
3049 * A generic solution implies reverse symref information,
3050 * but finding all symrefs pointing to the given branch
3051 * would be rather costly for this rare event (the direct
3052 * update of a branch) to be worth it. So let's cheat and
3053 * check with HEAD only which should cover 99% of all usage
3054 * scenarios (even 100% of the default ones).
3055 */
3056 unsigned char head_sha1[20];
3057 int head_flag;
3058 const char *head_ref;
3059
3060 head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
3061 RESOLVE_REF_READING,
3062 head_sha1, &head_flag);
3063 if (head_ref && (head_flag & REF_ISSYMREF) &&
3064 !strcmp(head_ref, lock->ref_name)) {
3065 struct strbuf log_err = STRBUF_INIT;
3066 if (files_log_ref_write(refs, "HEAD",
3067 lock->old_oid.hash, sha1,
3068 logmsg, 0, &log_err)) {
3069 error("%s", log_err.buf);
3070 strbuf_release(&log_err);
3071 }
3072 }
3073 }
3074
3075 if (commit_ref(lock)) {
3076 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3077 unlock_ref(lock);
3078 return -1;
3079 }
3080
3081 unlock_ref(lock);
3082 return 0;
3083 }
3084
3085 static int create_ref_symlink(struct ref_lock *lock, const char *target)
3086 {
3087 int ret = -1;
3088 #ifndef NO_SYMLINK_HEAD
3089 char *ref_path = get_locked_file_path(lock->lk);
3090 unlink(ref_path);
3091 ret = symlink(target, ref_path);
3092 free(ref_path);
3093
3094 if (ret)
3095 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
3096 #endif
3097 return ret;
3098 }
3099
3100 static void update_symref_reflog(struct files_ref_store *refs,
3101 struct ref_lock *lock, const char *refname,
3102 const char *target, const char *logmsg)
3103 {
3104 struct strbuf err = STRBUF_INIT;
3105 unsigned char new_sha1[20];
3106 if (logmsg &&
3107 !refs_read_ref_full(&refs->base, target,
3108 RESOLVE_REF_READING, new_sha1, NULL) &&
3109 files_log_ref_write(refs, refname, lock->old_oid.hash,
3110 new_sha1, logmsg, 0, &err)) {
3111 error("%s", err.buf);
3112 strbuf_release(&err);
3113 }
3114 }
3115
3116 static int create_symref_locked(struct files_ref_store *refs,
3117 struct ref_lock *lock, const char *refname,
3118 const char *target, const char *logmsg)
3119 {
3120 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
3121 update_symref_reflog(refs, lock, refname, target, logmsg);
3122 return 0;
3123 }
3124
3125 if (!fdopen_lock_file(lock->lk, "w"))
3126 return error("unable to fdopen %s: %s",
3127 lock->lk->tempfile.filename.buf, strerror(errno));
3128
3129 update_symref_reflog(refs, lock, refname, target, logmsg);
3130
3131 /* no error check; commit_ref will check ferror */
3132 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
3133 if (commit_ref(lock) < 0)
3134 return error("unable to write symref for %s: %s", refname,
3135 strerror(errno));
3136 return 0;
3137 }
3138
3139 static int files_create_symref(struct ref_store *ref_store,
3140 const char *refname, const char *target,
3141 const char *logmsg)
3142 {
3143 struct files_ref_store *refs =
3144 files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
3145 struct strbuf err = STRBUF_INIT;
3146 struct ref_lock *lock;
3147 int ret;
3148
3149 lock = lock_ref_sha1_basic(refs, refname, NULL,
3150 NULL, NULL, REF_NODEREF, NULL,
3151 &err);
3152 if (!lock) {
3153 error("%s", err.buf);
3154 strbuf_release(&err);
3155 return -1;
3156 }
3157
3158 ret = create_symref_locked(refs, lock, refname, target, logmsg);
3159 unlock_ref(lock);
3160 return ret;
3161 }
3162
3163 int set_worktree_head_symref(const char *gitdir, const char *target, const char *logmsg)
3164 {
3165 /*
3166 * FIXME: this obviously will not work well for future refs
3167 * backends. This function needs to die.
3168 */
3169 struct files_ref_store *refs =
3170 files_downcast(get_main_ref_store(),
3171 REF_STORE_WRITE,
3172 "set_head_symref");
3173
3174 static struct lock_file head_lock;
3175 struct ref_lock *lock;
3176 struct strbuf head_path = STRBUF_INIT;
3177 const char *head_rel;
3178 int ret;
3179
3180 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3181 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3182 LOCK_NO_DEREF) < 0) {
3183 struct strbuf err = STRBUF_INIT;
3184 unable_to_lock_message(head_path.buf, errno, &err);
3185 error("%s", err.buf);
3186 strbuf_release(&err);
3187 strbuf_release(&head_path);
3188 return -1;
3189 }
3190
3191 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3192 linked trees */
3193 head_rel = remove_leading_path(head_path.buf,
3194 absolute_path(get_git_common_dir()));
3195 /* to make use of create_symref_locked(), initialize ref_lock */
3196 lock = xcalloc(1, sizeof(struct ref_lock));
3197 lock->lk = &head_lock;
3198 lock->ref_name = xstrdup(head_rel);
3199
3200 ret = create_symref_locked(refs, lock, head_rel, target, logmsg);
3201
3202 unlock_ref(lock); /* will free lock */
3203 strbuf_release(&head_path);
3204 return ret;
3205 }
3206
3207 static int files_reflog_exists(struct ref_store *ref_store,
3208 const char *refname)
3209 {
3210 struct files_ref_store *refs =
3211 files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
3212 struct strbuf sb = STRBUF_INIT;
3213 struct stat st;
3214 int ret;
3215
3216 files_reflog_path(refs, &sb, refname);
3217 ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
3218 strbuf_release(&sb);
3219 return ret;
3220 }
3221
3222 static int files_delete_reflog(struct ref_store *ref_store,
3223 const char *refname)
3224 {
3225 struct files_ref_store *refs =
3226 files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
3227 struct strbuf sb = STRBUF_INIT;
3228 int ret;
3229
3230 files_reflog_path(refs, &sb, refname);
3231 ret = remove_path(sb.buf);
3232 strbuf_release(&sb);
3233 return ret;
3234 }
3235
3236 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3237 {
3238 struct object_id ooid, noid;
3239 char *email_end, *message;
3240 unsigned long timestamp;
3241 int tz;
3242 const char *p = sb->buf;
3243
3244 /* old SP new SP name <email> SP time TAB msg LF */
3245 if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
3246 parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
3247 parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
3248 !(email_end = strchr(p, '>')) ||
3249 email_end[1] != ' ' ||
3250 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3251 !message || message[0] != ' ' ||
3252 (message[1] != '+' && message[1] != '-') ||
3253 !isdigit(message[2]) || !isdigit(message[3]) ||
3254 !isdigit(message[4]) || !isdigit(message[5]))
3255 return 0; /* corrupt? */
3256 email_end[1] = '\0';
3257 tz = strtol(message + 1, NULL, 10);
3258 if (message[6] != '\t')
3259 message += 6;
3260 else
3261 message += 7;
3262 return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
3263 }
3264
3265 static char *find_beginning_of_line(char *bob, char *scan)
3266 {
3267 while (bob < scan && *(--scan) != '\n')
3268 ; /* keep scanning backwards */
3269 /*
3270 * Return either beginning of the buffer, or LF at the end of
3271 * the previous line.
3272 */
3273 return scan;
3274 }
3275
3276 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
3277 const char *refname,
3278 each_reflog_ent_fn fn,
3279 void *cb_data)
3280 {
3281 struct files_ref_store *refs =
3282 files_downcast(ref_store, REF_STORE_READ,
3283 "for_each_reflog_ent_reverse");
3284 struct strbuf sb = STRBUF_INIT;
3285 FILE *logfp;
3286 long pos;
3287 int ret = 0, at_tail = 1;
3288
3289 files_reflog_path(refs, &sb, refname);
3290 logfp = fopen(sb.buf, "r");
3291 strbuf_release(&sb);
3292 if (!logfp)
3293 return -1;
3294
3295 /* Jump to the end */
3296 if (fseek(logfp, 0, SEEK_END) < 0)
3297 return error("cannot seek back reflog for %s: %s",
3298 refname, strerror(errno));
3299 pos = ftell(logfp);
3300 while (!ret && 0 < pos) {
3301 int cnt;
3302 size_t nread;
3303 char buf[BUFSIZ];
3304 char *endp, *scanp;
3305
3306 /* Fill next block from the end */
3307 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3308 if (fseek(logfp, pos - cnt, SEEK_SET))
3309 return error("cannot seek back reflog for %s: %s",
3310 refname, strerror(errno));
3311 nread = fread(buf, cnt, 1, logfp);
3312 if (nread != 1)
3313 return error("cannot read %d bytes from reflog for %s: %s",
3314 cnt, refname, strerror(errno));
3315 pos -= cnt;
3316
3317 scanp = endp = buf + cnt;
3318 if (at_tail && scanp[-1] == '\n')
3319 /* Looking at the final LF at the end of the file */
3320 scanp--;
3321 at_tail = 0;
3322
3323 while (buf < scanp) {
3324 /*
3325 * terminating LF of the previous line, or the beginning
3326 * of the buffer.
3327 */
3328 char *bp;
3329
3330 bp = find_beginning_of_line(buf, scanp);
3331
3332 if (*bp == '\n') {
3333 /*
3334 * The newline is the end of the previous line,
3335 * so we know we have complete line starting
3336 * at (bp + 1). Prefix it onto any prior data
3337 * we collected for the line and process it.
3338 */
3339 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3340 scanp = bp;
3341 endp = bp + 1;
3342 ret = show_one_reflog_ent(&sb, fn, cb_data);
3343 strbuf_reset(&sb);
3344 if (ret)
3345 break;
3346 } else if (!pos) {
3347 /*
3348 * We are at the start of the buffer, and the
3349 * start of the file; there is no previous
3350 * line, and we have everything for this one.
3351 * Process it, and we can end the loop.
3352 */
3353 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3354 ret = show_one_reflog_ent(&sb, fn, cb_data);
3355 strbuf_reset(&sb);
3356 break;
3357 }
3358
3359 if (bp == buf) {
3360 /*
3361 * We are at the start of the buffer, and there
3362 * is more file to read backwards. Which means
3363 * we are in the middle of a line. Note that we
3364 * may get here even if *bp was a newline; that
3365 * just means we are at the exact end of the
3366 * previous line, rather than some spot in the
3367 * middle.
3368 *
3369 * Save away what we have to be combined with
3370 * the data from the next read.
3371 */
3372 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3373 break;
3374 }
3375 }
3376
3377 }
3378 if (!ret && sb.len)
3379 die("BUG: reverse reflog parser had leftover data");
3380
3381 fclose(logfp);
3382 strbuf_release(&sb);
3383 return ret;
3384 }
3385
3386 static int files_for_each_reflog_ent(struct ref_store *ref_store,
3387 const char *refname,
3388 each_reflog_ent_fn fn, void *cb_data)
3389 {
3390 struct files_ref_store *refs =
3391 files_downcast(ref_store, REF_STORE_READ,
3392 "for_each_reflog_ent");
3393 FILE *logfp;
3394 struct strbuf sb = STRBUF_INIT;
3395 int ret = 0;
3396
3397 files_reflog_path(refs, &sb, refname);
3398 logfp = fopen(sb.buf, "r");
3399 strbuf_release(&sb);
3400 if (!logfp)
3401 return -1;
3402
3403 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3404 ret = show_one_reflog_ent(&sb, fn, cb_data);
3405 fclose(logfp);
3406 strbuf_release(&sb);
3407 return ret;
3408 }
3409
3410 struct files_reflog_iterator {
3411 struct ref_iterator base;
3412
3413 struct ref_store *ref_store;
3414 struct dir_iterator *dir_iterator;
3415 struct object_id oid;
3416 };
3417
3418 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
3419 {
3420 struct files_reflog_iterator *iter =
3421 (struct files_reflog_iterator *)ref_iterator;
3422 struct dir_iterator *diter = iter->dir_iterator;
3423 int ok;
3424
3425 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
3426 int flags;
3427
3428 if (!S_ISREG(diter->st.st_mode))
3429 continue;
3430 if (diter->basename[0] == '.')
3431 continue;
3432 if (ends_with(diter->basename, ".lock"))
3433 continue;
3434
3435 if (refs_read_ref_full(iter->ref_store,
3436 diter->relative_path, 0,
3437 iter->oid.hash, &flags)) {
3438 error("bad ref for %s", diter->path.buf);
3439 continue;
3440 }
3441
3442 iter->base.refname = diter->relative_path;
3443 iter->base.oid = &iter->oid;
3444 iter->base.flags = flags;
3445 return ITER_OK;
3446 }
3447
3448 iter->dir_iterator = NULL;
3449 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
3450 ok = ITER_ERROR;
3451 return ok;
3452 }
3453
3454 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
3455 struct object_id *peeled)
3456 {
3457 die("BUG: ref_iterator_peel() called for reflog_iterator");
3458 }
3459
3460 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
3461 {
3462 struct files_reflog_iterator *iter =
3463 (struct files_reflog_iterator *)ref_iterator;
3464 int ok = ITER_DONE;
3465
3466 if (iter->dir_iterator)
3467 ok = dir_iterator_abort(iter->dir_iterator);
3468
3469 base_ref_iterator_free(ref_iterator);
3470 return ok;
3471 }
3472
3473 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
3474 files_reflog_iterator_advance,
3475 files_reflog_iterator_peel,
3476 files_reflog_iterator_abort
3477 };
3478
3479 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
3480 {
3481 struct files_ref_store *refs =
3482 files_downcast(ref_store, REF_STORE_READ,
3483 "reflog_iterator_begin");
3484 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
3485 struct ref_iterator *ref_iterator = &iter->base;
3486 struct strbuf sb = STRBUF_INIT;
3487
3488 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
3489 files_reflog_path(refs, &sb, NULL);
3490 iter->dir_iterator = dir_iterator_begin(sb.buf);
3491 iter->ref_store = ref_store;
3492 strbuf_release(&sb);
3493 return ref_iterator;
3494 }
3495
3496 static int ref_update_reject_duplicates(struct string_list *refnames,
3497 struct strbuf *err)
3498 {
3499 int i, n = refnames->nr;
3500
3501 assert(err);
3502
3503 for (i = 1; i < n; i++)
3504 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3505 strbuf_addf(err,
3506 "multiple updates for ref '%s' not allowed.",
3507 refnames->items[i].string);
3508 return 1;
3509 }
3510 return 0;
3511 }
3512
3513 /*
3514 * If update is a direct update of head_ref (the reference pointed to
3515 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3516 */
3517 static int split_head_update(struct ref_update *update,
3518 struct ref_transaction *transaction,
3519 const char *head_ref,
3520 struct string_list *affected_refnames,
3521 struct strbuf *err)
3522 {
3523 struct string_list_item *item;
3524 struct ref_update *new_update;
3525
3526 if ((update->flags & REF_LOG_ONLY) ||
3527 (update->flags & REF_ISPRUNING) ||
3528 (update->flags & REF_UPDATE_VIA_HEAD))
3529 return 0;
3530
3531 if (strcmp(update->refname, head_ref))
3532 return 0;
3533
3534 /*
3535 * First make sure that HEAD is not already in the
3536 * transaction. This insertion is O(N) in the transaction
3537 * size, but it happens at most once per transaction.
3538 */
3539 item = string_list_insert(affected_refnames, "HEAD");
3540 if (item->util) {
3541 /* An entry already existed */
3542 strbuf_addf(err,
3543 "multiple updates for 'HEAD' (including one "
3544 "via its referent '%s') are not allowed",
3545 update->refname);
3546 return TRANSACTION_NAME_CONFLICT;
3547 }
3548
3549 new_update = ref_transaction_add_update(
3550 transaction, "HEAD",
3551 update->flags | REF_LOG_ONLY | REF_NODEREF,
3552 update->new_sha1, update->old_sha1,
3553 update->msg);
3554
3555 item->util = new_update;
3556
3557 return 0;
3558 }
3559
3560 /*
3561 * update is for a symref that points at referent and doesn't have
3562 * REF_NODEREF set. Split it into two updates:
3563 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3564 * - A new, separate update for the referent reference
3565 * Note that the new update will itself be subject to splitting when
3566 * the iteration gets to it.
3567 */
3568 static int split_symref_update(struct files_ref_store *refs,
3569 struct ref_update *update,
3570 const char *referent,
3571 struct ref_transaction *transaction,
3572 struct string_list *affected_refnames,
3573 struct strbuf *err)
3574 {
3575 struct string_list_item *item;
3576 struct ref_update *new_update;
3577 unsigned int new_flags;
3578
3579 /*
3580 * First make sure that referent is not already in the
3581 * transaction. This insertion is O(N) in the transaction
3582 * size, but it happens at most once per symref in a
3583 * transaction.
3584 */
3585 item = string_list_insert(affected_refnames, referent);
3586 if (item->util) {
3587 /* An entry already existed */
3588 strbuf_addf(err,
3589 "multiple updates for '%s' (including one "
3590 "via symref '%s') are not allowed",
3591 referent, update->refname);
3592 return TRANSACTION_NAME_CONFLICT;
3593 }
3594
3595 new_flags = update->flags;
3596 if (!strcmp(update->refname, "HEAD")) {
3597 /*
3598 * Record that the new update came via HEAD, so that
3599 * when we process it, split_head_update() doesn't try
3600 * to add another reflog update for HEAD. Note that
3601 * this bit will be propagated if the new_update
3602 * itself needs to be split.
3603 */
3604 new_flags |= REF_UPDATE_VIA_HEAD;
3605 }
3606
3607 new_update = ref_transaction_add_update(
3608 transaction, referent, new_flags,
3609 update->new_sha1, update->old_sha1,
3610 update->msg);
3611
3612 new_update->parent_update = update;
3613
3614 /*
3615 * Change the symbolic ref update to log only. Also, it
3616 * doesn't need to check its old SHA-1 value, as that will be
3617 * done when new_update is processed.
3618 */
3619 update->flags |= REF_LOG_ONLY | REF_NODEREF;
3620 update->flags &= ~REF_HAVE_OLD;
3621
3622 item->util = new_update;
3623
3624 return 0;
3625 }
3626
3627 /*
3628 * Return the refname under which update was originally requested.
3629 */
3630 static const char *original_update_refname(struct ref_update *update)
3631 {
3632 while (update->parent_update)
3633 update = update->parent_update;
3634
3635 return update->refname;
3636 }
3637
3638 /*
3639 * Check whether the REF_HAVE_OLD and old_oid values stored in update
3640 * are consistent with oid, which is the reference's current value. If
3641 * everything is OK, return 0; otherwise, write an error message to
3642 * err and return -1.
3643 */
3644 static int check_old_oid(struct ref_update *update, struct object_id *oid,
3645 struct strbuf *err)
3646 {
3647 if (!(update->flags & REF_HAVE_OLD) ||
3648 !hashcmp(oid->hash, update->old_sha1))
3649 return 0;
3650
3651 if (is_null_sha1(update->old_sha1))
3652 strbuf_addf(err, "cannot lock ref '%s': "
3653 "reference already exists",
3654 original_update_refname(update));
3655 else if (is_null_oid(oid))
3656 strbuf_addf(err, "cannot lock ref '%s': "
3657 "reference is missing but expected %s",
3658 original_update_refname(update),
3659 sha1_to_hex(update->old_sha1));
3660 else
3661 strbuf_addf(err, "cannot lock ref '%s': "
3662 "is at %s but expected %s",
3663 original_update_refname(update),
3664 oid_to_hex(oid),
3665 sha1_to_hex(update->old_sha1));
3666
3667 return -1;
3668 }
3669
3670 /*
3671 * Prepare for carrying out update:
3672 * - Lock the reference referred to by update.
3673 * - Read the reference under lock.
3674 * - Check that its old SHA-1 value (if specified) is correct, and in
3675 * any case record it in update->lock->old_oid for later use when
3676 * writing the reflog.
3677 * - If it is a symref update without REF_NODEREF, split it up into a
3678 * REF_LOG_ONLY update of the symref and add a separate update for
3679 * the referent to transaction.
3680 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3681 * update of HEAD.
3682 */
3683 static int lock_ref_for_update(struct files_ref_store *refs,
3684 struct ref_update *update,
3685 struct ref_transaction *transaction,
3686 const char *head_ref,
3687 struct string_list *affected_refnames,
3688 struct strbuf *err)
3689 {
3690 struct strbuf referent = STRBUF_INIT;
3691 int mustexist = (update->flags & REF_HAVE_OLD) &&
3692 !is_null_sha1(update->old_sha1);
3693 int ret;
3694 struct ref_lock *lock;
3695
3696 files_assert_main_repository(refs, "lock_ref_for_update");
3697
3698 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
3699 update->flags |= REF_DELETING;
3700
3701 if (head_ref) {
3702 ret = split_head_update(update, transaction, head_ref,
3703 affected_refnames, err);
3704 if (ret)
3705 return ret;
3706 }
3707
3708 ret = lock_raw_ref(refs, update->refname, mustexist,
3709 affected_refnames, NULL,
3710 &lock, &referent,
3711 &update->type, err);
3712 if (ret) {
3713 char *reason;
3714
3715 reason = strbuf_detach(err, NULL);
3716 strbuf_addf(err, "cannot lock ref '%s': %s",
3717 original_update_refname(update), reason);
3718 free(reason);
3719 return ret;
3720 }
3721
3722 update->backend_data = lock;
3723
3724 if (update->type & REF_ISSYMREF) {
3725 if (update->flags & REF_NODEREF) {
3726 /*
3727 * We won't be reading the referent as part of
3728 * the transaction, so we have to read it here
3729 * to record and possibly check old_sha1:
3730 */
3731 if (refs_read_ref_full(&refs->base,
3732 referent.buf, 0,
3733 lock->old_oid.hash, NULL)) {
3734 if (update->flags & REF_HAVE_OLD) {
3735 strbuf_addf(err, "cannot lock ref '%s': "
3736 "error reading reference",
3737 original_update_refname(update));
3738 return -1;
3739 }
3740 } else if (check_old_oid(update, &lock->old_oid, err)) {
3741 return TRANSACTION_GENERIC_ERROR;
3742 }
3743 } else {
3744 /*
3745 * Create a new update for the reference this
3746 * symref is pointing at. Also, we will record
3747 * and verify old_sha1 for this update as part
3748 * of processing the split-off update, so we
3749 * don't have to do it here.
3750 */
3751 ret = split_symref_update(refs, update,
3752 referent.buf, transaction,
3753 affected_refnames, err);
3754 if (ret)
3755 return ret;
3756 }
3757 } else {
3758 struct ref_update *parent_update;
3759
3760 if (check_old_oid(update, &lock->old_oid, err))
3761 return TRANSACTION_GENERIC_ERROR;
3762
3763 /*
3764 * If this update is happening indirectly because of a
3765 * symref update, record the old SHA-1 in the parent
3766 * update:
3767 */
3768 for (parent_update = update->parent_update;
3769 parent_update;
3770 parent_update = parent_update->parent_update) {
3771 struct ref_lock *parent_lock = parent_update->backend_data;
3772 oidcpy(&parent_lock->old_oid, &lock->old_oid);
3773 }
3774 }
3775
3776 if ((update->flags & REF_HAVE_NEW) &&
3777 !(update->flags & REF_DELETING) &&
3778 !(update->flags & REF_LOG_ONLY)) {
3779 if (!(update->type & REF_ISSYMREF) &&
3780 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
3781 /*
3782 * The reference already has the desired
3783 * value, so we don't need to write it.
3784 */
3785 } else if (write_ref_to_lockfile(lock, update->new_sha1,
3786 err)) {
3787 char *write_err = strbuf_detach(err, NULL);
3788
3789 /*
3790 * The lock was freed upon failure of
3791 * write_ref_to_lockfile():
3792 */
3793 update->backend_data = NULL;
3794 strbuf_addf(err,
3795 "cannot update ref '%s': %s",
3796 update->refname, write_err);
3797 free(write_err);
3798 return TRANSACTION_GENERIC_ERROR;
3799 } else {
3800 update->flags |= REF_NEEDS_COMMIT;
3801 }
3802 }
3803 if (!(update->flags & REF_NEEDS_COMMIT)) {
3804 /*
3805 * We didn't call write_ref_to_lockfile(), so
3806 * the lockfile is still open. Close it to
3807 * free up the file descriptor:
3808 */
3809 if (close_ref(lock)) {
3810 strbuf_addf(err, "couldn't close '%s.lock'",
3811 update->refname);
3812 return TRANSACTION_GENERIC_ERROR;
3813 }
3814 }
3815 return 0;
3816 }
3817
3818 static int files_transaction_commit(struct ref_store *ref_store,
3819 struct ref_transaction *transaction,
3820 struct strbuf *err)