Merge tag 'v2.11.3' into maint-2.12
[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
169 static struct ref_dir *get_ref_dir(struct ref_entry *entry)
170 {
171 struct ref_dir *dir;
172 assert(entry->flag & REF_DIR);
173 dir = &entry->u.subdir;
174 if (entry->flag & REF_INCOMPLETE) {
175 read_loose_refs(entry->name, dir);
176
177 /*
178 * Manually add refs/bisect, which, being
179 * per-worktree, might not appear in the directory
180 * listing for refs/ in the main repo.
181 */
182 if (!strcmp(entry->name, "refs/")) {
183 int pos = search_ref_dir(dir, "refs/bisect/", 12);
184 if (pos < 0) {
185 struct ref_entry *child_entry;
186 child_entry = create_dir_entry(dir->ref_store,
187 "refs/bisect/",
188 12, 1);
189 add_entry_to_dir(dir, child_entry);
190 read_loose_refs("refs/bisect",
191 &child_entry->u.subdir);
192 }
193 }
194 entry->flag &= ~REF_INCOMPLETE;
195 }
196 return dir;
197 }
198
199 static struct ref_entry *create_ref_entry(const char *refname,
200 const unsigned char *sha1, int flag,
201 int check_name)
202 {
203 struct ref_entry *ref;
204
205 if (check_name &&
206 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
207 die("Reference has invalid format: '%s'", refname);
208 FLEX_ALLOC_STR(ref, name, refname);
209 hashcpy(ref->u.value.oid.hash, sha1);
210 oidclr(&ref->u.value.peeled);
211 ref->flag = flag;
212 return ref;
213 }
214
215 static void clear_ref_dir(struct ref_dir *dir);
216
217 static void free_ref_entry(struct ref_entry *entry)
218 {
219 if (entry->flag & REF_DIR) {
220 /*
221 * Do not use get_ref_dir() here, as that might
222 * trigger the reading of loose refs.
223 */
224 clear_ref_dir(&entry->u.subdir);
225 }
226 free(entry);
227 }
228
229 /*
230 * Add a ref_entry to the end of dir (unsorted). Entry is always
231 * stored directly in dir; no recursion into subdirectories is
232 * done.
233 */
234 static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
235 {
236 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
237 dir->entries[dir->nr++] = entry;
238 /* optimize for the case that entries are added in order */
239 if (dir->nr == 1 ||
240 (dir->nr == dir->sorted + 1 &&
241 strcmp(dir->entries[dir->nr - 2]->name,
242 dir->entries[dir->nr - 1]->name) < 0))
243 dir->sorted = dir->nr;
244 }
245
246 /*
247 * Clear and free all entries in dir, recursively.
248 */
249 static void clear_ref_dir(struct ref_dir *dir)
250 {
251 int i;
252 for (i = 0; i < dir->nr; i++)
253 free_ref_entry(dir->entries[i]);
254 free(dir->entries);
255 dir->sorted = dir->nr = dir->alloc = 0;
256 dir->entries = NULL;
257 }
258
259 /*
260 * Create a struct ref_entry object for the specified dirname.
261 * dirname is the name of the directory with a trailing slash (e.g.,
262 * "refs/heads/") or "" for the top-level directory.
263 */
264 static struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
265 const char *dirname, size_t len,
266 int incomplete)
267 {
268 struct ref_entry *direntry;
269 FLEX_ALLOC_MEM(direntry, name, dirname, len);
270 direntry->u.subdir.ref_store = ref_store;
271 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
272 return direntry;
273 }
274
275 static int ref_entry_cmp(const void *a, const void *b)
276 {
277 struct ref_entry *one = *(struct ref_entry **)a;
278 struct ref_entry *two = *(struct ref_entry **)b;
279 return strcmp(one->name, two->name);
280 }
281
282 static void sort_ref_dir(struct ref_dir *dir);
283
284 struct string_slice {
285 size_t len;
286 const char *str;
287 };
288
289 static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
290 {
291 const struct string_slice *key = key_;
292 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
293 int cmp = strncmp(key->str, ent->name, key->len);
294 if (cmp)
295 return cmp;
296 return '\0' - (unsigned char)ent->name[key->len];
297 }
298
299 /*
300 * Return the index of the entry with the given refname from the
301 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
302 * no such entry is found. dir must already be complete.
303 */
304 static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
305 {
306 struct ref_entry **r;
307 struct string_slice key;
308
309 if (refname == NULL || !dir->nr)
310 return -1;
311
312 sort_ref_dir(dir);
313 key.len = len;
314 key.str = refname;
315 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
316 ref_entry_cmp_sslice);
317
318 if (r == NULL)
319 return -1;
320
321 return r - dir->entries;
322 }
323
324 /*
325 * Search for a directory entry directly within dir (without
326 * recursing). Sort dir if necessary. subdirname must be a directory
327 * name (i.e., end in '/'). If mkdir is set, then create the
328 * directory if it is missing; otherwise, return NULL if the desired
329 * directory cannot be found. dir must already be complete.
330 */
331 static struct ref_dir *search_for_subdir(struct ref_dir *dir,
332 const char *subdirname, size_t len,
333 int mkdir)
334 {
335 int entry_index = search_ref_dir(dir, subdirname, len);
336 struct ref_entry *entry;
337 if (entry_index == -1) {
338 if (!mkdir)
339 return NULL;
340 /*
341 * Since dir is complete, the absence of a subdir
342 * means that the subdir really doesn't exist;
343 * therefore, create an empty record for it but mark
344 * the record complete.
345 */
346 entry = create_dir_entry(dir->ref_store, subdirname, len, 0);
347 add_entry_to_dir(dir, entry);
348 } else {
349 entry = dir->entries[entry_index];
350 }
351 return get_ref_dir(entry);
352 }
353
354 /*
355 * If refname is a reference name, find the ref_dir within the dir
356 * tree that should hold refname. If refname is a directory name
357 * (i.e., ends in '/'), then return that ref_dir itself. dir must
358 * represent the top-level directory and must already be complete.
359 * Sort ref_dirs and recurse into subdirectories as necessary. If
360 * mkdir is set, then create any missing directories; otherwise,
361 * return NULL if the desired directory cannot be found.
362 */
363 static struct ref_dir *find_containing_dir(struct ref_dir *dir,
364 const char *refname, int mkdir)
365 {
366 const char *slash;
367 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
368 size_t dirnamelen = slash - refname + 1;
369 struct ref_dir *subdir;
370 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
371 if (!subdir) {
372 dir = NULL;
373 break;
374 }
375 dir = subdir;
376 }
377
378 return dir;
379 }
380
381 /*
382 * Find the value entry with the given name in dir, sorting ref_dirs
383 * and recursing into subdirectories as necessary. If the name is not
384 * found or it corresponds to a directory entry, return NULL.
385 */
386 static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
387 {
388 int entry_index;
389 struct ref_entry *entry;
390 dir = find_containing_dir(dir, refname, 0);
391 if (!dir)
392 return NULL;
393 entry_index = search_ref_dir(dir, refname, strlen(refname));
394 if (entry_index == -1)
395 return NULL;
396 entry = dir->entries[entry_index];
397 return (entry->flag & REF_DIR) ? NULL : entry;
398 }
399
400 /*
401 * Remove the entry with the given name from dir, recursing into
402 * subdirectories as necessary. If refname is the name of a directory
403 * (i.e., ends with '/'), then remove the directory and its contents.
404 * If the removal was successful, return the number of entries
405 * remaining in the directory entry that contained the deleted entry.
406 * If the name was not found, return -1. Please note that this
407 * function only deletes the entry from the cache; it does not delete
408 * it from the filesystem or ensure that other cache entries (which
409 * might be symbolic references to the removed entry) are updated.
410 * Nor does it remove any containing dir entries that might be made
411 * empty by the removal. dir must represent the top-level directory
412 * and must already be complete.
413 */
414 static int remove_entry(struct ref_dir *dir, const char *refname)
415 {
416 int refname_len = strlen(refname);
417 int entry_index;
418 struct ref_entry *entry;
419 int is_dir = refname[refname_len - 1] == '/';
420 if (is_dir) {
421 /*
422 * refname represents a reference directory. Remove
423 * the trailing slash; otherwise we will get the
424 * directory *representing* refname rather than the
425 * one *containing* it.
426 */
427 char *dirname = xmemdupz(refname, refname_len - 1);
428 dir = find_containing_dir(dir, dirname, 0);
429 free(dirname);
430 } else {
431 dir = find_containing_dir(dir, refname, 0);
432 }
433 if (!dir)
434 return -1;
435 entry_index = search_ref_dir(dir, refname, refname_len);
436 if (entry_index == -1)
437 return -1;
438 entry = dir->entries[entry_index];
439
440 memmove(&dir->entries[entry_index],
441 &dir->entries[entry_index + 1],
442 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
443 );
444 dir->nr--;
445 if (dir->sorted > entry_index)
446 dir->sorted--;
447 free_ref_entry(entry);
448 return dir->nr;
449 }
450
451 /*
452 * Add a ref_entry to the ref_dir (unsorted), recursing into
453 * subdirectories as necessary. dir must represent the top-level
454 * directory. Return 0 on success.
455 */
456 static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
457 {
458 dir = find_containing_dir(dir, ref->name, 1);
459 if (!dir)
460 return -1;
461 add_entry_to_dir(dir, ref);
462 return 0;
463 }
464
465 /*
466 * Emit a warning and return true iff ref1 and ref2 have the same name
467 * and the same sha1. Die if they have the same name but different
468 * sha1s.
469 */
470 static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
471 {
472 if (strcmp(ref1->name, ref2->name))
473 return 0;
474
475 /* Duplicate name; make sure that they don't conflict: */
476
477 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
478 /* This is impossible by construction */
479 die("Reference directory conflict: %s", ref1->name);
480
481 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
482 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
483
484 warning("Duplicated ref: %s", ref1->name);
485 return 1;
486 }
487
488 /*
489 * Sort the entries in dir non-recursively (if they are not already
490 * sorted) and remove any duplicate entries.
491 */
492 static void sort_ref_dir(struct ref_dir *dir)
493 {
494 int i, j;
495 struct ref_entry *last = NULL;
496
497 /*
498 * This check also prevents passing a zero-length array to qsort(),
499 * which is a problem on some platforms.
500 */
501 if (dir->sorted == dir->nr)
502 return;
503
504 QSORT(dir->entries, dir->nr, ref_entry_cmp);
505
506 /* Remove any duplicates: */
507 for (i = 0, j = 0; j < dir->nr; j++) {
508 struct ref_entry *entry = dir->entries[j];
509 if (last && is_dup_ref(last, entry))
510 free_ref_entry(entry);
511 else
512 last = dir->entries[i++] = entry;
513 }
514 dir->sorted = dir->nr = i;
515 }
516
517 /*
518 * Return true if refname, which has the specified oid and flags, can
519 * be resolved to an object in the database. If the referred-to object
520 * does not exist, emit a warning and return false.
521 */
522 static int ref_resolves_to_object(const char *refname,
523 const struct object_id *oid,
524 unsigned int flags)
525 {
526 if (flags & REF_ISBROKEN)
527 return 0;
528 if (!has_sha1_file(oid->hash)) {
529 error("%s does not point to a valid object!", refname);
530 return 0;
531 }
532 return 1;
533 }
534
535 /*
536 * Return true if the reference described by entry can be resolved to
537 * an object in the database; otherwise, emit a warning and return
538 * false.
539 */
540 static int entry_resolves_to_object(struct ref_entry *entry)
541 {
542 return ref_resolves_to_object(entry->name,
543 &entry->u.value.oid, entry->flag);
544 }
545
546 typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
547
548 /*
549 * Call fn for each reference in dir that has index in the range
550 * offset <= index < dir->nr. Recurse into subdirectories that are in
551 * that index range, sorting them before iterating. This function
552 * does not sort dir itself; it should be sorted beforehand. fn is
553 * called for all references, including broken ones.
554 */
555 static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
556 each_ref_entry_fn fn, void *cb_data)
557 {
558 int i;
559 assert(dir->sorted == dir->nr);
560 for (i = offset; i < dir->nr; i++) {
561 struct ref_entry *entry = dir->entries[i];
562 int retval;
563 if (entry->flag & REF_DIR) {
564 struct ref_dir *subdir = get_ref_dir(entry);
565 sort_ref_dir(subdir);
566 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
567 } else {
568 retval = fn(entry, cb_data);
569 }
570 if (retval)
571 return retval;
572 }
573 return 0;
574 }
575
576 /*
577 * Load all of the refs from the dir into our in-memory cache. The hard work
578 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
579 * through all of the sub-directories. We do not even need to care about
580 * sorting, as traversal order does not matter to us.
581 */
582 static void prime_ref_dir(struct ref_dir *dir)
583 {
584 int i;
585 for (i = 0; i < dir->nr; i++) {
586 struct ref_entry *entry = dir->entries[i];
587 if (entry->flag & REF_DIR)
588 prime_ref_dir(get_ref_dir(entry));
589 }
590 }
591
592 /*
593 * A level in the reference hierarchy that is currently being iterated
594 * through.
595 */
596 struct cache_ref_iterator_level {
597 /*
598 * The ref_dir being iterated over at this level. The ref_dir
599 * is sorted before being stored here.
600 */
601 struct ref_dir *dir;
602
603 /*
604 * The index of the current entry within dir (which might
605 * itself be a directory). If index == -1, then the iteration
606 * hasn't yet begun. If index == dir->nr, then the iteration
607 * through this level is over.
608 */
609 int index;
610 };
611
612 /*
613 * Represent an iteration through a ref_dir in the memory cache. The
614 * iteration recurses through subdirectories.
615 */
616 struct cache_ref_iterator {
617 struct ref_iterator base;
618
619 /*
620 * The number of levels currently on the stack. This is always
621 * at least 1, because when it becomes zero the iteration is
622 * ended and this struct is freed.
623 */
624 size_t levels_nr;
625
626 /* The number of levels that have been allocated on the stack */
627 size_t levels_alloc;
628
629 /*
630 * A stack of levels. levels[0] is the uppermost level that is
631 * being iterated over in this iteration. (This is not
632 * necessary the top level in the references hierarchy. If we
633 * are iterating through a subtree, then levels[0] will hold
634 * the ref_dir for that subtree, and subsequent levels will go
635 * on from there.)
636 */
637 struct cache_ref_iterator_level *levels;
638 };
639
640 static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
641 {
642 struct cache_ref_iterator *iter =
643 (struct cache_ref_iterator *)ref_iterator;
644
645 while (1) {
646 struct cache_ref_iterator_level *level =
647 &iter->levels[iter->levels_nr - 1];
648 struct ref_dir *dir = level->dir;
649 struct ref_entry *entry;
650
651 if (level->index == -1)
652 sort_ref_dir(dir);
653
654 if (++level->index == level->dir->nr) {
655 /* This level is exhausted; pop up a level */
656 if (--iter->levels_nr == 0)
657 return ref_iterator_abort(ref_iterator);
658
659 continue;
660 }
661
662 entry = dir->entries[level->index];
663
664 if (entry->flag & REF_DIR) {
665 /* push down a level */
666 ALLOC_GROW(iter->levels, iter->levels_nr + 1,
667 iter->levels_alloc);
668
669 level = &iter->levels[iter->levels_nr++];
670 level->dir = get_ref_dir(entry);
671 level->index = -1;
672 } else {
673 iter->base.refname = entry->name;
674 iter->base.oid = &entry->u.value.oid;
675 iter->base.flags = entry->flag;
676 return ITER_OK;
677 }
678 }
679 }
680
681 static enum peel_status peel_entry(struct ref_entry *entry, int repeel);
682
683 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
684 struct object_id *peeled)
685 {
686 struct cache_ref_iterator *iter =
687 (struct cache_ref_iterator *)ref_iterator;
688 struct cache_ref_iterator_level *level;
689 struct ref_entry *entry;
690
691 level = &iter->levels[iter->levels_nr - 1];
692
693 if (level->index == -1)
694 die("BUG: peel called before advance for cache iterator");
695
696 entry = level->dir->entries[level->index];
697
698 if (peel_entry(entry, 0))
699 return -1;
700 oidcpy(peeled, &entry->u.value.peeled);
701 return 0;
702 }
703
704 static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
705 {
706 struct cache_ref_iterator *iter =
707 (struct cache_ref_iterator *)ref_iterator;
708
709 free(iter->levels);
710 base_ref_iterator_free(ref_iterator);
711 return ITER_DONE;
712 }
713
714 static struct ref_iterator_vtable cache_ref_iterator_vtable = {
715 cache_ref_iterator_advance,
716 cache_ref_iterator_peel,
717 cache_ref_iterator_abort
718 };
719
720 static struct ref_iterator *cache_ref_iterator_begin(struct ref_dir *dir)
721 {
722 struct cache_ref_iterator *iter;
723 struct ref_iterator *ref_iterator;
724 struct cache_ref_iterator_level *level;
725
726 iter = xcalloc(1, sizeof(*iter));
727 ref_iterator = &iter->base;
728 base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
729 ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
730
731 iter->levels_nr = 1;
732 level = &iter->levels[0];
733 level->index = -1;
734 level->dir = dir;
735
736 return ref_iterator;
737 }
738
739 struct nonmatching_ref_data {
740 const struct string_list *skip;
741 const char *conflicting_refname;
742 };
743
744 static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
745 {
746 struct nonmatching_ref_data *data = vdata;
747
748 if (data->skip && string_list_has_string(data->skip, entry->name))
749 return 0;
750
751 data->conflicting_refname = entry->name;
752 return 1;
753 }
754
755 /*
756 * Return 0 if a reference named refname could be created without
757 * conflicting with the name of an existing reference in dir.
758 * See verify_refname_available for more information.
759 */
760 static int verify_refname_available_dir(const char *refname,
761 const struct string_list *extras,
762 const struct string_list *skip,
763 struct ref_dir *dir,
764 struct strbuf *err)
765 {
766 const char *slash;
767 const char *extra_refname;
768 int pos;
769 struct strbuf dirname = STRBUF_INIT;
770 int ret = -1;
771
772 /*
773 * For the sake of comments in this function, suppose that
774 * refname is "refs/foo/bar".
775 */
776
777 assert(err);
778
779 strbuf_grow(&dirname, strlen(refname) + 1);
780 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
781 /* Expand dirname to the new prefix, not including the trailing slash: */
782 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
783
784 /*
785 * We are still at a leading dir of the refname (e.g.,
786 * "refs/foo"; if there is a reference with that name,
787 * it is a conflict, *unless* it is in skip.
788 */
789 if (dir) {
790 pos = search_ref_dir(dir, dirname.buf, dirname.len);
791 if (pos >= 0 &&
792 (!skip || !string_list_has_string(skip, dirname.buf))) {
793 /*
794 * We found a reference whose name is
795 * a proper prefix of refname; e.g.,
796 * "refs/foo", and is not in skip.
797 */
798 strbuf_addf(err, "'%s' exists; cannot create '%s'",
799 dirname.buf, refname);
800 goto cleanup;
801 }
802 }
803
804 if (extras && string_list_has_string(extras, dirname.buf) &&
805 (!skip || !string_list_has_string(skip, dirname.buf))) {
806 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
807 refname, dirname.buf);
808 goto cleanup;
809 }
810
811 /*
812 * Otherwise, we can try to continue our search with
813 * the next component. So try to look up the
814 * directory, e.g., "refs/foo/". If we come up empty,
815 * we know there is nothing under this whole prefix,
816 * but even in that case we still have to continue the
817 * search for conflicts with extras.
818 */
819 strbuf_addch(&dirname, '/');
820 if (dir) {
821 pos = search_ref_dir(dir, dirname.buf, dirname.len);
822 if (pos < 0) {
823 /*
824 * There was no directory "refs/foo/",
825 * so there is nothing under this
826 * whole prefix. So there is no need
827 * to continue looking for conflicting
828 * references. But we need to continue
829 * looking for conflicting extras.
830 */
831 dir = NULL;
832 } else {
833 dir = get_ref_dir(dir->entries[pos]);
834 }
835 }
836 }
837
838 /*
839 * We are at the leaf of our refname (e.g., "refs/foo/bar").
840 * There is no point in searching for a reference with that
841 * name, because a refname isn't considered to conflict with
842 * itself. But we still need to check for references whose
843 * names are in the "refs/foo/bar/" namespace, because they
844 * *do* conflict.
845 */
846 strbuf_addstr(&dirname, refname + dirname.len);
847 strbuf_addch(&dirname, '/');
848
849 if (dir) {
850 pos = search_ref_dir(dir, dirname.buf, dirname.len);
851
852 if (pos >= 0) {
853 /*
854 * We found a directory named "$refname/"
855 * (e.g., "refs/foo/bar/"). It is a problem
856 * iff it contains any ref that is not in
857 * "skip".
858 */
859 struct nonmatching_ref_data data;
860
861 data.skip = skip;
862 data.conflicting_refname = NULL;
863 dir = get_ref_dir(dir->entries[pos]);
864 sort_ref_dir(dir);
865 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
866 strbuf_addf(err, "'%s' exists; cannot create '%s'",
867 data.conflicting_refname, refname);
868 goto cleanup;
869 }
870 }
871 }
872
873 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
874 if (extra_refname)
875 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
876 refname, extra_refname);
877 else
878 ret = 0;
879
880 cleanup:
881 strbuf_release(&dirname);
882 return ret;
883 }
884
885 struct packed_ref_cache {
886 struct ref_entry *root;
887
888 /*
889 * Count of references to the data structure in this instance,
890 * including the pointer from files_ref_store::packed if any.
891 * The data will not be freed as long as the reference count
892 * is nonzero.
893 */
894 unsigned int referrers;
895
896 /*
897 * Iff the packed-refs file associated with this instance is
898 * currently locked for writing, this points at the associated
899 * lock (which is owned by somebody else). The referrer count
900 * is also incremented when the file is locked and decremented
901 * when it is unlocked.
902 */
903 struct lock_file *lock;
904
905 /* The metadata from when this packed-refs cache was read */
906 struct stat_validity validity;
907 };
908
909 /*
910 * Future: need to be in "struct repository"
911 * when doing a full libification.
912 */
913 struct files_ref_store {
914 struct ref_store base;
915 struct ref_entry *loose;
916 struct packed_ref_cache *packed;
917 };
918
919 /* Lock used for the main packed-refs file: */
920 static struct lock_file packlock;
921
922 /*
923 * Increment the reference count of *packed_refs.
924 */
925 static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
926 {
927 packed_refs->referrers++;
928 }
929
930 /*
931 * Decrease the reference count of *packed_refs. If it goes to zero,
932 * free *packed_refs and return true; otherwise return false.
933 */
934 static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
935 {
936 if (!--packed_refs->referrers) {
937 free_ref_entry(packed_refs->root);
938 stat_validity_clear(&packed_refs->validity);
939 free(packed_refs);
940 return 1;
941 } else {
942 return 0;
943 }
944 }
945
946 static void clear_packed_ref_cache(struct files_ref_store *refs)
947 {
948 if (refs->packed) {
949 struct packed_ref_cache *packed_refs = refs->packed;
950
951 if (packed_refs->lock)
952 die("internal error: packed-ref cache cleared while locked");
953 refs->packed = NULL;
954 release_packed_ref_cache(packed_refs);
955 }
956 }
957
958 static void clear_loose_ref_cache(struct files_ref_store *refs)
959 {
960 if (refs->loose) {
961 free_ref_entry(refs->loose);
962 refs->loose = NULL;
963 }
964 }
965
966 /*
967 * Create a new submodule ref cache and add it to the internal
968 * set of caches.
969 */
970 static struct ref_store *files_ref_store_create(const char *submodule)
971 {
972 struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
973 struct ref_store *ref_store = (struct ref_store *)refs;
974
975 base_ref_store_init(ref_store, &refs_be_files, submodule);
976
977 return ref_store;
978 }
979
980 /*
981 * Downcast ref_store to files_ref_store. Die if ref_store is not a
982 * files_ref_store. If submodule_allowed is not true, then also die if
983 * files_ref_store is for a submodule (i.e., not for the main
984 * repository). caller is used in any necessary error messages.
985 */
986 static struct files_ref_store *files_downcast(
987 struct ref_store *ref_store, int submodule_allowed,
988 const char *caller)
989 {
990 if (ref_store->be != &refs_be_files)
991 die("BUG: ref_store is type \"%s\" not \"files\" in %s",
992 ref_store->be->name, caller);
993
994 if (!submodule_allowed)
995 assert_main_repository(ref_store, caller);
996
997 return (struct files_ref_store *)ref_store;
998 }
999
1000 /* The length of a peeled reference line in packed-refs, including EOL: */
1001 #define PEELED_LINE_LENGTH 42
1002
1003 /*
1004 * The packed-refs header line that we write out. Perhaps other
1005 * traits will be added later. The trailing space is required.
1006 */
1007 static const char PACKED_REFS_HEADER[] =
1008 "# pack-refs with: peeled fully-peeled \n";
1009
1010 /*
1011 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
1012 * Return a pointer to the refname within the line (null-terminated),
1013 * or NULL if there was a problem.
1014 */
1015 static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
1016 {
1017 const char *ref;
1018
1019 /*
1020 * 42: the answer to everything.
1021 *
1022 * In this case, it happens to be the answer to
1023 * 40 (length of sha1 hex representation)
1024 * +1 (space in between hex and name)
1025 * +1 (newline at the end of the line)
1026 */
1027 if (line->len <= 42)
1028 return NULL;
1029
1030 if (get_sha1_hex(line->buf, sha1) < 0)
1031 return NULL;
1032 if (!isspace(line->buf[40]))
1033 return NULL;
1034
1035 ref = line->buf + 41;
1036 if (isspace(*ref))
1037 return NULL;
1038
1039 if (line->buf[line->len - 1] != '\n')
1040 return NULL;
1041 line->buf[--line->len] = 0;
1042
1043 return ref;
1044 }
1045
1046 /*
1047 * Read f, which is a packed-refs file, into dir.
1048 *
1049 * A comment line of the form "# pack-refs with: " may contain zero or
1050 * more traits. We interpret the traits as follows:
1051 *
1052 * No traits:
1053 *
1054 * Probably no references are peeled. But if the file contains a
1055 * peeled value for a reference, we will use it.
1056 *
1057 * peeled:
1058 *
1059 * References under "refs/tags/", if they *can* be peeled, *are*
1060 * peeled in this file. References outside of "refs/tags/" are
1061 * probably not peeled even if they could have been, but if we find
1062 * a peeled value for such a reference we will use it.
1063 *
1064 * fully-peeled:
1065 *
1066 * All references in the file that can be peeled are peeled.
1067 * Inversely (and this is more important), any references in the
1068 * file for which no peeled value is recorded is not peelable. This
1069 * trait should typically be written alongside "peeled" for
1070 * compatibility with older clients, but we do not require it
1071 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1072 */
1073 static void read_packed_refs(FILE *f, struct ref_dir *dir)
1074 {
1075 struct ref_entry *last = NULL;
1076 struct strbuf line = STRBUF_INIT;
1077 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1078
1079 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1080 unsigned char sha1[20];
1081 const char *refname;
1082 const char *traits;
1083
1084 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1085 if (strstr(traits, " fully-peeled "))
1086 peeled = PEELED_FULLY;
1087 else if (strstr(traits, " peeled "))
1088 peeled = PEELED_TAGS;
1089 /* perhaps other traits later as well */
1090 continue;
1091 }
1092
1093 refname = parse_ref_line(&line, sha1);
1094 if (refname) {
1095 int flag = REF_ISPACKED;
1096
1097 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1098 if (!refname_is_safe(refname))
1099 die("packed refname is dangerous: %s", refname);
1100 hashclr(sha1);
1101 flag |= REF_BAD_NAME | REF_ISBROKEN;
1102 }
1103 last = create_ref_entry(refname, sha1, flag, 0);
1104 if (peeled == PEELED_FULLY ||
1105 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1106 last->flag |= REF_KNOWS_PEELED;
1107 add_ref(dir, last);
1108 continue;
1109 }
1110 if (last &&
1111 line.buf[0] == '^' &&
1112 line.len == PEELED_LINE_LENGTH &&
1113 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1114 !get_sha1_hex(line.buf + 1, sha1)) {
1115 hashcpy(last->u.value.peeled.hash, sha1);
1116 /*
1117 * Regardless of what the file header said,
1118 * we definitely know the value of *this*
1119 * reference:
1120 */
1121 last->flag |= REF_KNOWS_PEELED;
1122 }
1123 }
1124
1125 strbuf_release(&line);
1126 }
1127
1128 /*
1129 * Get the packed_ref_cache for the specified files_ref_store,
1130 * creating it if necessary.
1131 */
1132 static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *refs)
1133 {
1134 char *packed_refs_file;
1135
1136 if (*refs->base.submodule)
1137 packed_refs_file = git_pathdup_submodule(refs->base.submodule,
1138 "packed-refs");
1139 else
1140 packed_refs_file = git_pathdup("packed-refs");
1141
1142 if (refs->packed &&
1143 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1144 clear_packed_ref_cache(refs);
1145
1146 if (!refs->packed) {
1147 FILE *f;
1148
1149 refs->packed = xcalloc(1, sizeof(*refs->packed));
1150 acquire_packed_ref_cache(refs->packed);
1151 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1152 f = fopen(packed_refs_file, "r");
1153 if (f) {
1154 stat_validity_update(&refs->packed->validity, fileno(f));
1155 read_packed_refs(f, get_ref_dir(refs->packed->root));
1156 fclose(f);
1157 }
1158 }
1159 free(packed_refs_file);
1160 return refs->packed;
1161 }
1162
1163 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1164 {
1165 return get_ref_dir(packed_ref_cache->root);
1166 }
1167
1168 static struct ref_dir *get_packed_refs(struct files_ref_store *refs)
1169 {
1170 return get_packed_ref_dir(get_packed_ref_cache(refs));
1171 }
1172
1173 /*
1174 * Add a reference to the in-memory packed reference cache. This may
1175 * only be called while the packed-refs file is locked (see
1176 * lock_packed_refs()). To actually write the packed-refs file, call
1177 * commit_packed_refs().
1178 */
1179 static void add_packed_ref(struct files_ref_store *refs,
1180 const char *refname, const unsigned char *sha1)
1181 {
1182 struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
1183
1184 if (!packed_ref_cache->lock)
1185 die("internal error: packed refs not locked");
1186 add_ref(get_packed_ref_dir(packed_ref_cache),
1187 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1188 }
1189
1190 /*
1191 * Read the loose references from the namespace dirname into dir
1192 * (without recursing). dirname must end with '/'. dir must be the
1193 * directory entry corresponding to dirname.
1194 */
1195 static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1196 {
1197 struct files_ref_store *refs = dir->ref_store;
1198 DIR *d;
1199 struct dirent *de;
1200 int dirnamelen = strlen(dirname);
1201 struct strbuf refname;
1202 struct strbuf path = STRBUF_INIT;
1203 size_t path_baselen;
1204 int err = 0;
1205
1206 if (*refs->base.submodule)
1207 err = strbuf_git_path_submodule(&path, refs->base.submodule, "%s", dirname);
1208 else
1209 strbuf_git_path(&path, "%s", dirname);
1210 path_baselen = path.len;
1211
1212 if (err) {
1213 strbuf_release(&path);
1214 return;
1215 }
1216
1217 d = opendir(path.buf);
1218 if (!d) {
1219 strbuf_release(&path);
1220 return;
1221 }
1222
1223 strbuf_init(&refname, dirnamelen + 257);
1224 strbuf_add(&refname, dirname, dirnamelen);
1225
1226 while ((de = readdir(d)) != NULL) {
1227 unsigned char sha1[20];
1228 struct stat st;
1229 int flag;
1230
1231 if (de->d_name[0] == '.')
1232 continue;
1233 if (ends_with(de->d_name, ".lock"))
1234 continue;
1235 strbuf_addstr(&refname, de->d_name);
1236 strbuf_addstr(&path, de->d_name);
1237 if (stat(path.buf, &st) < 0) {
1238 ; /* silently ignore */
1239 } else if (S_ISDIR(st.st_mode)) {
1240 strbuf_addch(&refname, '/');
1241 add_entry_to_dir(dir,
1242 create_dir_entry(refs, refname.buf,
1243 refname.len, 1));
1244 } else {
1245 int read_ok;
1246
1247 if (*refs->base.submodule) {
1248 hashclr(sha1);
1249 flag = 0;
1250 read_ok = !resolve_gitlink_ref(refs->base.submodule,
1251 refname.buf, sha1);
1252 } else {
1253 read_ok = !read_ref_full(refname.buf,
1254 RESOLVE_REF_READING,
1255 sha1, &flag);
1256 }
1257
1258 if (!read_ok) {
1259 hashclr(sha1);
1260 flag |= REF_ISBROKEN;
1261 } else if (is_null_sha1(sha1)) {
1262 /*
1263 * It is so astronomically unlikely
1264 * that NULL_SHA1 is the SHA-1 of an
1265 * actual object that we consider its
1266 * appearance in a loose reference
1267 * file to be repo corruption
1268 * (probably due to a software bug).
1269 */
1270 flag |= REF_ISBROKEN;
1271 }
1272
1273 if (check_refname_format(refname.buf,
1274 REFNAME_ALLOW_ONELEVEL)) {
1275 if (!refname_is_safe(refname.buf))
1276 die("loose refname is dangerous: %s", refname.buf);
1277 hashclr(sha1);
1278 flag |= REF_BAD_NAME | REF_ISBROKEN;
1279 }
1280 add_entry_to_dir(dir,
1281 create_ref_entry(refname.buf, sha1, flag, 0));
1282 }
1283 strbuf_setlen(&refname, dirnamelen);
1284 strbuf_setlen(&path, path_baselen);
1285 }
1286 strbuf_release(&refname);
1287 strbuf_release(&path);
1288 closedir(d);
1289 }
1290
1291 static struct ref_dir *get_loose_refs(struct files_ref_store *refs)
1292 {
1293 if (!refs->loose) {
1294 /*
1295 * Mark the top-level directory complete because we
1296 * are about to read the only subdirectory that can
1297 * hold references:
1298 */
1299 refs->loose = create_dir_entry(refs, "", 0, 0);
1300 /*
1301 * Create an incomplete entry for "refs/":
1302 */
1303 add_entry_to_dir(get_ref_dir(refs->loose),
1304 create_dir_entry(refs, "refs/", 5, 1));
1305 }
1306 return get_ref_dir(refs->loose);
1307 }
1308
1309 /*
1310 * Return the ref_entry for the given refname from the packed
1311 * references. If it does not exist, return NULL.
1312 */
1313 static struct ref_entry *get_packed_ref(struct files_ref_store *refs,
1314 const char *refname)
1315 {
1316 return find_ref(get_packed_refs(refs), refname);
1317 }
1318
1319 /*
1320 * A loose ref file doesn't exist; check for a packed ref.
1321 */
1322 static int resolve_packed_ref(struct files_ref_store *refs,
1323 const char *refname,
1324 unsigned char *sha1, unsigned int *flags)
1325 {
1326 struct ref_entry *entry;
1327
1328 /*
1329 * The loose reference file does not exist; check for a packed
1330 * reference.
1331 */
1332 entry = get_packed_ref(refs, refname);
1333 if (entry) {
1334 hashcpy(sha1, entry->u.value.oid.hash);
1335 *flags |= REF_ISPACKED;
1336 return 0;
1337 }
1338 /* refname is not a packed reference. */
1339 return -1;
1340 }
1341
1342 static int files_read_raw_ref(struct ref_store *ref_store,
1343 const char *refname, unsigned char *sha1,
1344 struct strbuf *referent, unsigned int *type)
1345 {
1346 struct files_ref_store *refs =
1347 files_downcast(ref_store, 1, "read_raw_ref");
1348 struct strbuf sb_contents = STRBUF_INIT;
1349 struct strbuf sb_path = STRBUF_INIT;
1350 const char *path;
1351 const char *buf;
1352 struct stat st;
1353 int fd;
1354 int ret = -1;
1355 int save_errno;
1356 int remaining_retries = 3;
1357
1358 *type = 0;
1359 strbuf_reset(&sb_path);
1360
1361 if (*refs->base.submodule)
1362 strbuf_git_path_submodule(&sb_path, refs->base.submodule, "%s", refname);
1363 else
1364 strbuf_git_path(&sb_path, "%s", refname);
1365
1366 path = sb_path.buf;
1367
1368 stat_ref:
1369 /*
1370 * We might have to loop back here to avoid a race
1371 * condition: first we lstat() the file, then we try
1372 * to read it as a link or as a file. But if somebody
1373 * changes the type of the file (file <-> directory
1374 * <-> symlink) between the lstat() and reading, then
1375 * we don't want to report that as an error but rather
1376 * try again starting with the lstat().
1377 *
1378 * We'll keep a count of the retries, though, just to avoid
1379 * any confusing situation sending us into an infinite loop.
1380 */
1381
1382 if (remaining_retries-- <= 0)
1383 goto out;
1384
1385 if (lstat(path, &st) < 0) {
1386 if (errno != ENOENT)
1387 goto out;
1388 if (resolve_packed_ref(refs, refname, sha1, type)) {
1389 errno = ENOENT;
1390 goto out;
1391 }
1392 ret = 0;
1393 goto out;
1394 }
1395
1396 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1397 if (S_ISLNK(st.st_mode)) {
1398 strbuf_reset(&sb_contents);
1399 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
1400 if (errno == ENOENT || errno == EINVAL)
1401 /* inconsistent with lstat; retry */
1402 goto stat_ref;
1403 else
1404 goto out;
1405 }
1406 if (starts_with(sb_contents.buf, "refs/") &&
1407 !check_refname_format(sb_contents.buf, 0)) {
1408 strbuf_swap(&sb_contents, referent);
1409 *type |= REF_ISSYMREF;
1410 ret = 0;
1411 goto out;
1412 }
1413 /*
1414 * It doesn't look like a refname; fall through to just
1415 * treating it like a non-symlink, and reading whatever it
1416 * points to.
1417 */
1418 }
1419
1420 /* Is it a directory? */
1421 if (S_ISDIR(st.st_mode)) {
1422 /*
1423 * Even though there is a directory where the loose
1424 * ref is supposed to be, there could still be a
1425 * packed ref:
1426 */
1427 if (resolve_packed_ref(refs, refname, sha1, type)) {
1428 errno = EISDIR;
1429 goto out;
1430 }
1431 ret = 0;
1432 goto out;
1433 }
1434
1435 /*
1436 * Anything else, just open it and try to use it as
1437 * a ref
1438 */
1439 fd = open(path, O_RDONLY);
1440 if (fd < 0) {
1441 if (errno == ENOENT && !S_ISLNK(st.st_mode))
1442 /* inconsistent with lstat; retry */
1443 goto stat_ref;
1444 else
1445 goto out;
1446 }
1447 strbuf_reset(&sb_contents);
1448 if (strbuf_read(&sb_contents, fd, 256) < 0) {
1449 int save_errno = errno;
1450 close(fd);
1451 errno = save_errno;
1452 goto out;
1453 }
1454 close(fd);
1455 strbuf_rtrim(&sb_contents);
1456 buf = sb_contents.buf;
1457 if (starts_with(buf, "ref:")) {
1458 buf += 4;
1459 while (isspace(*buf))
1460 buf++;
1461
1462 strbuf_reset(referent);
1463 strbuf_addstr(referent, buf);
1464 *type |= REF_ISSYMREF;
1465 ret = 0;
1466 goto out;
1467 }
1468
1469 /*
1470 * Please note that FETCH_HEAD has additional
1471 * data after the sha.
1472 */
1473 if (get_sha1_hex(buf, sha1) ||
1474 (buf[40] != '\0' && !isspace(buf[40]))) {
1475 *type |= REF_ISBROKEN;
1476 errno = EINVAL;
1477 goto out;
1478 }
1479
1480 ret = 0;
1481
1482 out:
1483 save_errno = errno;
1484 strbuf_release(&sb_path);
1485 strbuf_release(&sb_contents);
1486 errno = save_errno;
1487 return ret;
1488 }
1489
1490 static void unlock_ref(struct ref_lock *lock)
1491 {
1492 /* Do not free lock->lk -- atexit() still looks at them */
1493 if (lock->lk)
1494 rollback_lock_file(lock->lk);
1495 free(lock->ref_name);
1496 free(lock);
1497 }
1498
1499 /*
1500 * Lock refname, without following symrefs, and set *lock_p to point
1501 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1502 * and type similarly to read_raw_ref().
1503 *
1504 * The caller must verify that refname is a "safe" reference name (in
1505 * the sense of refname_is_safe()) before calling this function.
1506 *
1507 * If the reference doesn't already exist, verify that refname doesn't
1508 * have a D/F conflict with any existing references. extras and skip
1509 * are passed to verify_refname_available_dir() for this check.
1510 *
1511 * If mustexist is not set and the reference is not found or is
1512 * broken, lock the reference anyway but clear sha1.
1513 *
1514 * Return 0 on success. On failure, write an error message to err and
1515 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1516 *
1517 * Implementation note: This function is basically
1518 *
1519 * lock reference
1520 * read_raw_ref()
1521 *
1522 * but it includes a lot more code to
1523 * - Deal with possible races with other processes
1524 * - Avoid calling verify_refname_available_dir() when it can be
1525 * avoided, namely if we were successfully able to read the ref
1526 * - Generate informative error messages in the case of failure
1527 */
1528 static int lock_raw_ref(struct files_ref_store *refs,
1529 const char *refname, int mustexist,
1530 const struct string_list *extras,
1531 const struct string_list *skip,
1532 struct ref_lock **lock_p,
1533 struct strbuf *referent,
1534 unsigned int *type,
1535 struct strbuf *err)
1536 {
1537 struct ref_lock *lock;
1538 struct strbuf ref_file = STRBUF_INIT;
1539 int attempts_remaining = 3;
1540 int ret = TRANSACTION_GENERIC_ERROR;
1541
1542 assert(err);
1543 assert_main_repository(&refs->base, "lock_raw_ref");
1544
1545 *type = 0;
1546
1547 /* First lock the file so it can't change out from under us. */
1548
1549 *lock_p = lock = xcalloc(1, sizeof(*lock));
1550
1551 lock->ref_name = xstrdup(refname);
1552 strbuf_git_path(&ref_file, "%s", refname);
1553
1554 retry:
1555 switch (safe_create_leading_directories(ref_file.buf)) {
1556 case SCLD_OK:
1557 break; /* success */
1558 case SCLD_EXISTS:
1559 /*
1560 * Suppose refname is "refs/foo/bar". We just failed
1561 * to create the containing directory, "refs/foo",
1562 * because there was a non-directory in the way. This
1563 * indicates a D/F conflict, probably because of
1564 * another reference such as "refs/foo". There is no
1565 * reason to expect this error to be transitory.
1566 */
1567 if (verify_refname_available(refname, extras, skip, err)) {
1568 if (mustexist) {
1569 /*
1570 * To the user the relevant error is
1571 * that the "mustexist" reference is
1572 * missing:
1573 */
1574 strbuf_reset(err);
1575 strbuf_addf(err, "unable to resolve reference '%s'",
1576 refname);
1577 } else {
1578 /*
1579 * The error message set by
1580 * verify_refname_available_dir() is OK.
1581 */
1582 ret = TRANSACTION_NAME_CONFLICT;
1583 }
1584 } else {
1585 /*
1586 * The file that is in the way isn't a loose
1587 * reference. Report it as a low-level
1588 * failure.
1589 */
1590 strbuf_addf(err, "unable to create lock file %s.lock; "
1591 "non-directory in the way",
1592 ref_file.buf);
1593 }
1594 goto error_return;
1595 case SCLD_VANISHED:
1596 /* Maybe another process was tidying up. Try again. */
1597 if (--attempts_remaining > 0)
1598 goto retry;
1599 /* fall through */
1600 default:
1601 strbuf_addf(err, "unable to create directory for %s",
1602 ref_file.buf);
1603 goto error_return;
1604 }
1605
1606 if (!lock->lk)
1607 lock->lk = xcalloc(1, sizeof(struct lock_file));
1608
1609 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1610 if (errno == ENOENT && --attempts_remaining > 0) {
1611 /*
1612 * Maybe somebody just deleted one of the
1613 * directories leading to ref_file. Try
1614 * again:
1615 */
1616 goto retry;
1617 } else {
1618 unable_to_lock_message(ref_file.buf, errno, err);
1619 goto error_return;
1620 }
1621 }
1622
1623 /*
1624 * Now we hold the lock and can read the reference without
1625 * fear that its value will change.
1626 */
1627
1628 if (files_read_raw_ref(&refs->base, refname,
1629 lock->old_oid.hash, referent, type)) {
1630 if (errno == ENOENT) {
1631 if (mustexist) {
1632 /* Garden variety missing reference. */
1633 strbuf_addf(err, "unable to resolve reference '%s'",
1634 refname);
1635 goto error_return;
1636 } else {
1637 /*
1638 * Reference is missing, but that's OK. We
1639 * know that there is not a conflict with
1640 * another loose reference because
1641 * (supposing that we are trying to lock
1642 * reference "refs/foo/bar"):
1643 *
1644 * - We were successfully able to create
1645 * the lockfile refs/foo/bar.lock, so we
1646 * know there cannot be a loose reference
1647 * named "refs/foo".
1648 *
1649 * - We got ENOENT and not EISDIR, so we
1650 * know that there cannot be a loose
1651 * reference named "refs/foo/bar/baz".
1652 */
1653 }
1654 } else if (errno == EISDIR) {
1655 /*
1656 * There is a directory in the way. It might have
1657 * contained references that have been deleted. If
1658 * we don't require that the reference already
1659 * exists, try to remove the directory so that it
1660 * doesn't cause trouble when we want to rename the
1661 * lockfile into place later.
1662 */
1663 if (mustexist) {
1664 /* Garden variety missing reference. */
1665 strbuf_addf(err, "unable to resolve reference '%s'",
1666 refname);
1667 goto error_return;
1668 } else if (remove_dir_recursively(&ref_file,
1669 REMOVE_DIR_EMPTY_ONLY)) {
1670 if (verify_refname_available_dir(
1671 refname, extras, skip,
1672 get_loose_refs(refs),
1673 err)) {
1674 /*
1675 * The error message set by
1676 * verify_refname_available() is OK.
1677 */
1678 ret = TRANSACTION_NAME_CONFLICT;
1679 goto error_return;
1680 } else {
1681 /*
1682 * We can't delete the directory,
1683 * but we also don't know of any
1684 * references that it should
1685 * contain.
1686 */
1687 strbuf_addf(err, "there is a non-empty directory '%s' "
1688 "blocking reference '%s'",
1689 ref_file.buf, refname);
1690 goto error_return;
1691 }
1692 }
1693 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1694 strbuf_addf(err, "unable to resolve reference '%s': "
1695 "reference broken", refname);
1696 goto error_return;
1697 } else {
1698 strbuf_addf(err, "unable to resolve reference '%s': %s",
1699 refname, strerror(errno));
1700 goto error_return;
1701 }
1702
1703 /*
1704 * If the ref did not exist and we are creating it,
1705 * make sure there is no existing packed ref whose
1706 * name begins with our refname, nor a packed ref
1707 * whose name is a proper prefix of our refname.
1708 */
1709 if (verify_refname_available_dir(
1710 refname, extras, skip,
1711 get_packed_refs(refs),
1712 err)) {
1713 goto error_return;
1714 }
1715 }
1716
1717 ret = 0;
1718 goto out;
1719
1720 error_return:
1721 unlock_ref(lock);
1722 *lock_p = NULL;
1723
1724 out:
1725 strbuf_release(&ref_file);
1726 return ret;
1727 }
1728
1729 /*
1730 * Peel the entry (if possible) and return its new peel_status. If
1731 * repeel is true, re-peel the entry even if there is an old peeled
1732 * value that is already stored in it.
1733 *
1734 * It is OK to call this function with a packed reference entry that
1735 * might be stale and might even refer to an object that has since
1736 * been garbage-collected. In such a case, if the entry has
1737 * REF_KNOWS_PEELED then leave the status unchanged and return
1738 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1739 */
1740 static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1741 {
1742 enum peel_status status;
1743
1744 if (entry->flag & REF_KNOWS_PEELED) {
1745 if (repeel) {
1746 entry->flag &= ~REF_KNOWS_PEELED;
1747 oidclr(&entry->u.value.peeled);
1748 } else {
1749 return is_null_oid(&entry->u.value.peeled) ?
1750 PEEL_NON_TAG : PEEL_PEELED;
1751 }
1752 }
1753 if (entry->flag & REF_ISBROKEN)
1754 return PEEL_BROKEN;
1755 if (entry->flag & REF_ISSYMREF)
1756 return PEEL_IS_SYMREF;
1757
1758 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1759 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1760 entry->flag |= REF_KNOWS_PEELED;
1761 return status;
1762 }
1763
1764 static int files_peel_ref(struct ref_store *ref_store,
1765 const char *refname, unsigned char *sha1)
1766 {
1767 struct files_ref_store *refs = files_downcast(ref_store, 0, "peel_ref");
1768 int flag;
1769 unsigned char base[20];
1770
1771 if (current_ref_iter && current_ref_iter->refname == refname) {
1772 struct object_id peeled;
1773
1774 if (ref_iterator_peel(current_ref_iter, &peeled))
1775 return -1;
1776 hashcpy(sha1, peeled.hash);
1777 return 0;
1778 }
1779
1780 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1781 return -1;
1782
1783 /*
1784 * If the reference is packed, read its ref_entry from the
1785 * cache in the hope that we already know its peeled value.
1786 * We only try this optimization on packed references because
1787 * (a) forcing the filling of the loose reference cache could
1788 * be expensive and (b) loose references anyway usually do not
1789 * have REF_KNOWS_PEELED.
1790 */
1791 if (flag & REF_ISPACKED) {
1792 struct ref_entry *r = get_packed_ref(refs, refname);
1793 if (r) {
1794 if (peel_entry(r, 0))
1795 return -1;
1796 hashcpy(sha1, r->u.value.peeled.hash);
1797 return 0;
1798 }
1799 }
1800
1801 return peel_object(base, sha1);
1802 }
1803
1804 struct files_ref_iterator {
1805 struct ref_iterator base;
1806
1807 struct packed_ref_cache *packed_ref_cache;
1808 struct ref_iterator *iter0;
1809 unsigned int flags;
1810 };
1811
1812 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
1813 {
1814 struct files_ref_iterator *iter =
1815 (struct files_ref_iterator *)ref_iterator;
1816 int ok;
1817
1818 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
1819 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
1820 ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
1821 continue;
1822
1823 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
1824 !ref_resolves_to_object(iter->iter0->refname,
1825 iter->iter0->oid,
1826 iter->iter0->flags))
1827 continue;
1828
1829 iter->base.refname = iter->iter0->refname;
1830 iter->base.oid = iter->iter0->oid;
1831 iter->base.flags = iter->iter0->flags;
1832 return ITER_OK;
1833 }
1834
1835 iter->iter0 = NULL;
1836 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
1837 ok = ITER_ERROR;
1838
1839 return ok;
1840 }
1841
1842 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
1843 struct object_id *peeled)
1844 {
1845 struct files_ref_iterator *iter =
1846 (struct files_ref_iterator *)ref_iterator;
1847
1848 return ref_iterator_peel(iter->iter0, peeled);
1849 }
1850
1851 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
1852 {
1853 struct files_ref_iterator *iter =
1854 (struct files_ref_iterator *)ref_iterator;
1855 int ok = ITER_DONE;
1856
1857 if (iter->iter0)
1858 ok = ref_iterator_abort(iter->iter0);
1859
1860 release_packed_ref_cache(iter->packed_ref_cache);
1861 base_ref_iterator_free(ref_iterator);
1862 return ok;
1863 }
1864
1865 static struct ref_iterator_vtable files_ref_iterator_vtable = {
1866 files_ref_iterator_advance,
1867 files_ref_iterator_peel,
1868 files_ref_iterator_abort
1869 };
1870
1871 static struct ref_iterator *files_ref_iterator_begin(
1872 struct ref_store *ref_store,
1873 const char *prefix, unsigned int flags)
1874 {
1875 struct files_ref_store *refs =
1876 files_downcast(ref_store, 1, "ref_iterator_begin");
1877 struct ref_dir *loose_dir, *packed_dir;
1878 struct ref_iterator *loose_iter, *packed_iter;
1879 struct files_ref_iterator *iter;
1880 struct ref_iterator *ref_iterator;
1881
1882 if (!refs)
1883 return empty_ref_iterator_begin();
1884
1885 if (ref_paranoia < 0)
1886 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1887 if (ref_paranoia)
1888 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1889
1890 iter = xcalloc(1, sizeof(*iter));
1891 ref_iterator = &iter->base;
1892 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
1893
1894 /*
1895 * We must make sure that all loose refs are read before
1896 * accessing the packed-refs file; this avoids a race
1897 * condition if loose refs are migrated to the packed-refs
1898 * file by a simultaneous process, but our in-memory view is
1899 * from before the migration. We ensure this as follows:
1900 * First, we call prime_ref_dir(), which pre-reads the loose
1901 * references for the subtree into the cache. (If they've
1902 * already been read, that's OK; we only need to guarantee
1903 * that they're read before the packed refs, not *how much*
1904 * before.) After that, we call get_packed_ref_cache(), which
1905 * internally checks whether the packed-ref cache is up to
1906 * date with what is on disk, and re-reads it if not.
1907 */
1908
1909 loose_dir = get_loose_refs(refs);
1910
1911 if (prefix && *prefix)
1912 loose_dir = find_containing_dir(loose_dir, prefix, 0);
1913
1914 if (loose_dir) {
1915 prime_ref_dir(loose_dir);
1916 loose_iter = cache_ref_iterator_begin(loose_dir);
1917 } else {
1918 /* There's nothing to iterate over. */
1919 loose_iter = empty_ref_iterator_begin();
1920 }
1921
1922 iter->packed_ref_cache = get_packed_ref_cache(refs);
1923 acquire_packed_ref_cache(iter->packed_ref_cache);
1924 packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
1925
1926 if (prefix && *prefix)
1927 packed_dir = find_containing_dir(packed_dir, prefix, 0);
1928
1929 if (packed_dir) {
1930 packed_iter = cache_ref_iterator_begin(packed_dir);
1931 } else {
1932 /* There's nothing to iterate over. */
1933 packed_iter = empty_ref_iterator_begin();
1934 }
1935
1936 iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
1937 iter->flags = flags;
1938
1939 return ref_iterator;
1940 }
1941
1942 /*
1943 * Verify that the reference locked by lock has the value old_sha1.
1944 * Fail if the reference doesn't exist and mustexist is set. Return 0
1945 * on success. On error, write an error message to err, set errno, and
1946 * return a negative value.
1947 */
1948 static int verify_lock(struct ref_lock *lock,
1949 const unsigned char *old_sha1, int mustexist,
1950 struct strbuf *err)
1951 {
1952 assert(err);
1953
1954 if (read_ref_full(lock->ref_name,
1955 mustexist ? RESOLVE_REF_READING : 0,
1956 lock->old_oid.hash, NULL)) {
1957 if (old_sha1) {
1958 int save_errno = errno;
1959 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
1960 errno = save_errno;
1961 return -1;
1962 } else {
1963 oidclr(&lock->old_oid);
1964 return 0;
1965 }
1966 }
1967 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
1968 strbuf_addf(err, "ref '%s' is at %s but expected %s",
1969 lock->ref_name,
1970 oid_to_hex(&lock->old_oid),
1971 sha1_to_hex(old_sha1));
1972 errno = EBUSY;
1973 return -1;
1974 }
1975 return 0;
1976 }
1977
1978 static int remove_empty_directories(struct strbuf *path)
1979 {
1980 /*
1981 * we want to create a file but there is a directory there;
1982 * if that is an empty directory (or a directory that contains
1983 * only empty directories), remove them.
1984 */
1985 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
1986 }
1987
1988 /*
1989 * Locks a ref returning the lock on success and NULL on failure.
1990 * On failure errno is set to something meaningful.
1991 */
1992 static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
1993 const char *refname,
1994 const unsigned char *old_sha1,
1995 const struct string_list *extras,
1996 const struct string_list *skip,
1997 unsigned int flags, int *type,
1998 struct strbuf *err)
1999 {
2000 struct strbuf ref_file = STRBUF_INIT;
2001 struct ref_lock *lock;
2002 int last_errno = 0;
2003 int lflags = LOCK_NO_DEREF;
2004 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2005 int resolve_flags = RESOLVE_REF_NO_RECURSE;
2006 int attempts_remaining = 3;
2007 int resolved;
2008
2009 assert_main_repository(&refs->base, "lock_ref_sha1_basic");
2010 assert(err);
2011
2012 lock = xcalloc(1, sizeof(struct ref_lock));
2013
2014 if (mustexist)
2015 resolve_flags |= RESOLVE_REF_READING;
2016 if (flags & REF_DELETING)
2017 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
2018
2019 strbuf_git_path(&ref_file, "%s", refname);
2020 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2021 lock->old_oid.hash, type);
2022 if (!resolved && errno == EISDIR) {
2023 /*
2024 * we are trying to lock foo but we used to
2025 * have foo/bar which now does not exist;
2026 * it is normal for the empty directory 'foo'
2027 * to remain.
2028 */
2029 if (remove_empty_directories(&ref_file)) {
2030 last_errno = errno;
2031 if (!verify_refname_available_dir(
2032 refname, extras, skip,
2033 get_loose_refs(refs), err))
2034 strbuf_addf(err, "there are still refs under '%s'",
2035 refname);
2036 goto error_return;
2037 }
2038 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2039 lock->old_oid.hash, type);
2040 }
2041 if (!resolved) {
2042 last_errno = errno;
2043 if (last_errno != ENOTDIR ||
2044 !verify_refname_available_dir(
2045 refname, extras, skip,
2046 get_loose_refs(refs), err))
2047 strbuf_addf(err, "unable to resolve reference '%s': %s",
2048 refname, strerror(last_errno));
2049
2050 goto error_return;
2051 }
2052
2053 /*
2054 * If the ref did not exist and we are creating it, make sure
2055 * there is no existing packed ref whose name begins with our
2056 * refname, nor a packed ref whose name is a proper prefix of
2057 * our refname.
2058 */
2059 if (is_null_oid(&lock->old_oid) &&
2060 verify_refname_available_dir(refname, extras, skip,
2061 get_packed_refs(refs),
2062 err)) {
2063 last_errno = ENOTDIR;
2064 goto error_return;
2065 }
2066
2067 lock->lk = xcalloc(1, sizeof(struct lock_file));
2068
2069 lock->ref_name = xstrdup(refname);
2070
2071 retry:
2072 switch (safe_create_leading_directories_const(ref_file.buf)) {
2073 case SCLD_OK:
2074 break; /* success */
2075 case SCLD_VANISHED:
2076 if (--attempts_remaining > 0)
2077 goto retry;
2078 /* fall through */
2079 default:
2080 last_errno = errno;
2081 strbuf_addf(err, "unable to create directory for '%s'",
2082 ref_file.buf);
2083 goto error_return;
2084 }
2085
2086 if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
2087 last_errno = errno;
2088 if (errno == ENOENT && --attempts_remaining > 0)
2089 /*
2090 * Maybe somebody just deleted one of the
2091 * directories leading to ref_file. Try
2092 * again:
2093 */
2094 goto retry;
2095 else {
2096 unable_to_lock_message(ref_file.buf, errno, err);
2097 goto error_return;
2098 }
2099 }
2100 if (verify_lock(lock, old_sha1, mustexist, err)) {
2101 last_errno = errno;
2102 goto error_return;
2103 }
2104 goto out;
2105
2106 error_return:
2107 unlock_ref(lock);
2108 lock = NULL;
2109
2110 out:
2111 strbuf_release(&ref_file);
2112 errno = last_errno;
2113 return lock;
2114 }
2115
2116 /*
2117 * Write an entry to the packed-refs file for the specified refname.
2118 * If peeled is non-NULL, write it as the entry's peeled value.
2119 */
2120 static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2121 unsigned char *peeled)
2122 {
2123 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2124 if (peeled)
2125 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2126 }
2127
2128 /*
2129 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2130 */
2131 static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2132 {
2133 enum peel_status peel_status = peel_entry(entry, 0);
2134
2135 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2136 error("internal error: %s is not a valid packed reference!",
2137 entry->name);
2138 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2139 peel_status == PEEL_PEELED ?
2140 entry->u.value.peeled.hash : NULL);
2141 return 0;
2142 }
2143
2144 /*
2145 * Lock the packed-refs file for writing. Flags is passed to
2146 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2147 * errno appropriately and return a nonzero value.
2148 */
2149 static int lock_packed_refs(struct files_ref_store *refs, int flags)
2150 {
2151 static int timeout_configured = 0;
2152 static int timeout_value = 1000;
2153 struct packed_ref_cache *packed_ref_cache;
2154
2155 assert_main_repository(&refs->base, "lock_packed_refs");
2156
2157 if (!timeout_configured) {
2158 git_config_get_int("core.packedrefstimeout", &timeout_value);
2159 timeout_configured = 1;
2160 }
2161
2162 if (hold_lock_file_for_update_timeout(
2163 &packlock, git_path("packed-refs"),
2164 flags, timeout_value) < 0)
2165 return -1;
2166 /*
2167 * Get the current packed-refs while holding the lock. If the
2168 * packed-refs file has been modified since we last read it,
2169 * this will automatically invalidate the cache and re-read
2170 * the packed-refs file.
2171 */
2172 packed_ref_cache = get_packed_ref_cache(refs);
2173 packed_ref_cache->lock = &packlock;
2174 /* Increment the reference count to prevent it from being freed: */
2175 acquire_packed_ref_cache(packed_ref_cache);
2176 return 0;
2177 }
2178
2179 /*
2180 * Write the current version of the packed refs cache from memory to
2181 * disk. The packed-refs file must already be locked for writing (see
2182 * lock_packed_refs()). Return zero on success. On errors, set errno
2183 * and return a nonzero value
2184 */
2185 static int commit_packed_refs(struct files_ref_store *refs)
2186 {
2187 struct packed_ref_cache *packed_ref_cache =
2188 get_packed_ref_cache(refs);
2189 int error = 0;
2190 int save_errno = 0;
2191 FILE *out;
2192
2193 assert_main_repository(&refs->base, "commit_packed_refs");
2194
2195 if (!packed_ref_cache->lock)
2196 die("internal error: packed-refs not locked");
2197
2198 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2199 if (!out)
2200 die_errno("unable to fdopen packed-refs descriptor");
2201
2202 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2203 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2204 0, write_packed_entry_fn, out);
2205
2206 if (commit_lock_file(packed_ref_cache->lock)) {
2207 save_errno = errno;
2208 error = -1;
2209 }
2210 packed_ref_cache->lock = NULL;
2211 release_packed_ref_cache(packed_ref_cache);
2212 errno = save_errno;
2213 return error;
2214 }
2215
2216 /*
2217 * Rollback the lockfile for the packed-refs file, and discard the
2218 * in-memory packed reference cache. (The packed-refs file will be
2219 * read anew if it is needed again after this function is called.)
2220 */
2221 static void rollback_packed_refs(struct files_ref_store *refs)
2222 {
2223 struct packed_ref_cache *packed_ref_cache =
2224 get_packed_ref_cache(refs);
2225
2226 assert_main_repository(&refs->base, "rollback_packed_refs");
2227
2228 if (!packed_ref_cache->lock)
2229 die("internal error: packed-refs not locked");
2230 rollback_lock_file(packed_ref_cache->lock);
2231 packed_ref_cache->lock = NULL;
2232 release_packed_ref_cache(packed_ref_cache);
2233 clear_packed_ref_cache(refs);
2234 }
2235
2236 struct ref_to_prune {
2237 struct ref_to_prune *next;
2238 unsigned char sha1[20];
2239 char name[FLEX_ARRAY];
2240 };
2241
2242 struct pack_refs_cb_data {
2243 unsigned int flags;
2244 struct ref_dir *packed_refs;
2245 struct ref_to_prune *ref_to_prune;
2246 };
2247
2248 /*
2249 * An each_ref_entry_fn that is run over loose references only. If
2250 * the loose reference can be packed, add an entry in the packed ref
2251 * cache. If the reference should be pruned, also add it to
2252 * ref_to_prune in the pack_refs_cb_data.
2253 */
2254 static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2255 {
2256 struct pack_refs_cb_data *cb = cb_data;
2257 enum peel_status peel_status;
2258 struct ref_entry *packed_entry;
2259 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2260
2261 /* Do not pack per-worktree refs: */
2262 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2263 return 0;
2264
2265 /* ALWAYS pack tags */
2266 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2267 return 0;
2268
2269 /* Do not pack symbolic or broken refs: */
2270 if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
2271 return 0;
2272
2273 /* Add a packed ref cache entry equivalent to the loose entry. */
2274 peel_status = peel_entry(entry, 1);
2275 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2276 die("internal error peeling reference %s (%s)",
2277 entry->name, oid_to_hex(&entry->u.value.oid));
2278 packed_entry = find_ref(cb->packed_refs, entry->name);
2279 if (packed_entry) {
2280 /* Overwrite existing packed entry with info from loose entry */
2281 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2282 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2283 } else {
2284 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2285 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2286 add_ref(cb->packed_refs, packed_entry);
2287 }
2288 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2289
2290 /* Schedule the loose reference for pruning if requested. */
2291 if ((cb->flags & PACK_REFS_PRUNE)) {
2292 struct ref_to_prune *n;
2293 FLEX_ALLOC_STR(n, name, entry->name);
2294 hashcpy(n->sha1, entry->u.value.oid.hash);
2295 n->next = cb->ref_to_prune;
2296 cb->ref_to_prune = n;
2297 }
2298 return 0;
2299 }
2300
2301 /*
2302 * Remove empty parents, but spare refs/ and immediate subdirs.
2303 * Note: munges *name.
2304 */
2305 static void try_remove_empty_parents(char *name)
2306 {
2307 char *p, *q;
2308 int i;
2309 p = name;
2310 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2311 while (*p && *p != '/')
2312 p++;
2313 /* tolerate duplicate slashes; see check_refname_format() */
2314 while (*p == '/')
2315 p++;
2316 }
2317 for (q = p; *q; q++)
2318 ;
2319 while (1) {
2320 while (q > p && *q != '/')
2321 q--;
2322 while (q > p && *(q-1) == '/')
2323 q--;
2324 if (q == p)
2325 break;
2326 *q = '\0';
2327 if (rmdir(git_path("%s", name)))
2328 break;
2329 }
2330 }
2331
2332 /* make sure nobody touched the ref, and unlink */
2333 static void prune_ref(struct ref_to_prune *r)
2334 {
2335 struct ref_transaction *transaction;
2336 struct strbuf err = STRBUF_INIT;
2337
2338 if (check_refname_format(r->name, 0))
2339 return;
2340
2341 transaction = ref_transaction_begin(&err);
2342 if (!transaction ||
2343 ref_transaction_delete(transaction, r->name, r->sha1,
2344 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
2345 ref_transaction_commit(transaction, &err)) {
2346 ref_transaction_free(transaction);
2347 error("%s", err.buf);
2348 strbuf_release(&err);
2349 return;
2350 }
2351 ref_transaction_free(transaction);
2352 strbuf_release(&err);
2353 try_remove_empty_parents(r->name);
2354 }
2355
2356 static void prune_refs(struct ref_to_prune *r)
2357 {
2358 while (r) {
2359 prune_ref(r);
2360 r = r->next;
2361 }
2362 }
2363
2364 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
2365 {
2366 struct files_ref_store *refs =
2367 files_downcast(ref_store, 0, "pack_refs");
2368 struct pack_refs_cb_data cbdata;
2369
2370 memset(&cbdata, 0, sizeof(cbdata));
2371 cbdata.flags = flags;
2372
2373 lock_packed_refs(refs, LOCK_DIE_ON_ERROR);
2374 cbdata.packed_refs = get_packed_refs(refs);
2375
2376 do_for_each_entry_in_dir(get_loose_refs(refs), 0,
2377 pack_if_possible_fn, &cbdata);
2378
2379 if (commit_packed_refs(refs))
2380 die_errno("unable to overwrite old ref-pack file");
2381
2382 prune_refs(cbdata.ref_to_prune);
2383 return 0;
2384 }
2385
2386 /*
2387 * Rewrite the packed-refs file, omitting any refs listed in
2388 * 'refnames'. On error, leave packed-refs unchanged, write an error
2389 * message to 'err', and return a nonzero value.
2390 *
2391 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2392 */
2393 static int repack_without_refs(struct files_ref_store *refs,
2394 struct string_list *refnames, struct strbuf *err)
2395 {
2396 struct ref_dir *packed;
2397 struct string_list_item *refname;
2398 int ret, needs_repacking = 0, removed = 0;
2399
2400 assert_main_repository(&refs->base, "repack_without_refs");
2401 assert(err);
2402
2403 /* Look for a packed ref */
2404 for_each_string_list_item(refname, refnames) {
2405 if (get_packed_ref(refs, refname->string)) {
2406 needs_repacking = 1;
2407 break;
2408 }
2409 }
2410
2411 /* Avoid locking if we have nothing to do */
2412 if (!needs_repacking)
2413 return 0; /* no refname exists in packed refs */
2414
2415 if (lock_packed_refs(refs, 0)) {
2416 unable_to_lock_message(git_path("packed-refs"), errno, err);
2417 return -1;
2418 }
2419 packed = get_packed_refs(refs);
2420
2421 /* Remove refnames from the cache */
2422 for_each_string_list_item(refname, refnames)
2423 if (remove_entry(packed, refname->string) != -1)
2424 removed = 1;
2425 if (!removed) {
2426 /*
2427 * All packed entries disappeared while we were
2428 * acquiring the lock.
2429 */
2430 rollback_packed_refs(refs);
2431 return 0;
2432 }
2433
2434 /* Write what remains */
2435 ret = commit_packed_refs(refs);
2436 if (ret)
2437 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2438 strerror(errno));
2439 return ret;
2440 }
2441
2442 static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2443 {
2444 assert(err);
2445
2446 if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2447 /*
2448 * loose. The loose file name is the same as the
2449 * lockfile name, minus ".lock":
2450 */
2451 char *loose_filename = get_locked_file_path(lock->lk);
2452 int res = unlink_or_msg(loose_filename, err);
2453 free(loose_filename);
2454 if (res)
2455 return 1;
2456 }
2457 return 0;
2458 }
2459
2460 static int files_delete_refs(struct ref_store *ref_store,
2461 struct string_list *refnames, unsigned int flags)
2462 {
2463 struct files_ref_store *refs =
2464 files_downcast(ref_store, 0, "delete_refs");
2465 struct strbuf err = STRBUF_INIT;
2466 int i, result = 0;
2467
2468 if (!refnames->nr)
2469 return 0;
2470
2471 result = repack_without_refs(refs, refnames, &err);
2472 if (result) {
2473 /*
2474 * If we failed to rewrite the packed-refs file, then
2475 * it is unsafe to try to remove loose refs, because
2476 * doing so might expose an obsolete packed value for
2477 * a reference that might even point at an object that
2478 * has been garbage collected.
2479 */
2480 if (refnames->nr == 1)
2481 error(_("could not delete reference %s: %s"),
2482 refnames->items[0].string, err.buf);
2483 else
2484 error(_("could not delete references: %s"), err.buf);
2485
2486 goto out;
2487 }
2488
2489 for (i = 0; i < refnames->nr; i++) {
2490 const char *refname = refnames->items[i].string;
2491
2492 if (delete_ref(refname, NULL, flags))
2493 result |= error(_("could not remove reference %s"), refname);
2494 }
2495
2496 out:
2497 strbuf_release(&err);
2498 return result;
2499 }
2500
2501 /*
2502 * People using contrib's git-new-workdir have .git/logs/refs ->
2503 * /some/other/path/.git/logs/refs, and that may live on another device.
2504 *
2505 * IOW, to avoid cross device rename errors, the temporary renamed log must
2506 * live into logs/refs.
2507 */
2508 #define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
2509
2510 static int rename_tmp_log(const char *newrefname)
2511 {
2512 int attempts_remaining = 4;
2513 struct strbuf path = STRBUF_INIT;
2514 int ret = -1;
2515
2516 retry:
2517 strbuf_reset(&path);
2518 strbuf_git_path(&path, "logs/%s", newrefname);
2519 switch (safe_create_leading_directories_const(path.buf)) {
2520 case SCLD_OK:
2521 break; /* success */
2522 case SCLD_VANISHED:
2523 if (--attempts_remaining > 0)
2524 goto retry;
2525 /* fall through */
2526 default:
2527 error("unable to create directory for %s", newrefname);
2528 goto out;
2529 }
2530
2531 if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
2532 if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2533 /*
2534 * rename(a, b) when b is an existing
2535 * directory ought to result in ISDIR, but
2536 * Solaris 5.8 gives ENOTDIR. Sheesh.
2537 */
2538 if (remove_empty_directories(&path)) {
2539 error("Directory not empty: logs/%s", newrefname);
2540 goto out;
2541 }
2542 goto retry;
2543 } else if (errno == ENOENT && --attempts_remaining > 0) {
2544 /*
2545 * Maybe another process just deleted one of
2546 * the directories in the path to newrefname.
2547 * Try again from the beginning.
2548 */
2549 goto retry;
2550 } else {
2551 error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2552 newrefname, strerror(errno));
2553 goto out;
2554 }
2555 }
2556 ret = 0;
2557 out:
2558 strbuf_release(&path);
2559 return ret;
2560 }
2561
2562 static int files_verify_refname_available(struct ref_store *ref_store,
2563 const char *newname,
2564 const struct string_list *extras,
2565 const struct string_list *skip,
2566 struct strbuf *err)
2567 {
2568 struct files_ref_store *refs =
2569 files_downcast(ref_store, 1, "verify_refname_available");
2570 struct ref_dir *packed_refs = get_packed_refs(refs);
2571 struct ref_dir *loose_refs = get_loose_refs(refs);
2572
2573 if (verify_refname_available_dir(newname, extras, skip,
2574 packed_refs, err) ||
2575 verify_refname_available_dir(newname, extras, skip,
2576 loose_refs, err))
2577 return -1;
2578
2579 return 0;
2580 }
2581
2582 static int write_ref_to_lockfile(struct ref_lock *lock,
2583 const unsigned char *sha1, struct strbuf *err);
2584 static int commit_ref_update(struct files_ref_store *refs,
2585 struct ref_lock *lock,
2586 const unsigned char *sha1, const char *logmsg,
2587 struct strbuf *err);
2588
2589 static int files_rename_ref(struct ref_store *ref_store,
2590 const char *oldrefname, const char *newrefname,
2591 const char *logmsg)
2592 {
2593 struct files_ref_store *refs =
2594 files_downcast(ref_store, 0, "rename_ref");
2595 unsigned char sha1[20], orig_sha1[20];
2596 int flag = 0, logmoved = 0;
2597 struct ref_lock *lock;
2598 struct stat loginfo;
2599 int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2600 struct strbuf err = STRBUF_INIT;
2601
2602 if (log && S_ISLNK(loginfo.st_mode))
2603 return error("reflog for %s is a symlink", oldrefname);
2604
2605 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2606 orig_sha1, &flag))
2607 return error("refname %s not found", oldrefname);
2608
2609 if (flag & REF_ISSYMREF)
2610 return error("refname %s is a symbolic ref, renaming it is not supported",
2611 oldrefname);
2612 if (!rename_ref_available(oldrefname, newrefname))
2613 return 1;
2614
2615 if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2616 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2617 oldrefname, strerror(errno));
2618
2619 if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2620 error("unable to delete old %s", oldrefname);
2621 goto rollback;
2622 }
2623
2624 /*
2625 * Since we are doing a shallow lookup, sha1 is not the
2626 * correct value to pass to delete_ref as old_sha1. But that
2627 * doesn't matter, because an old_sha1 check wouldn't add to
2628 * the safety anyway; we want to delete the reference whatever
2629 * its current value.
2630 */
2631 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2632 sha1, NULL) &&
2633 delete_ref(newrefname, NULL, REF_NODEREF)) {
2634 if (errno==EISDIR) {
2635 struct strbuf path = STRBUF_INIT;
2636 int result;
2637
2638 strbuf_git_path(&path, "%s", newrefname);
2639 result = remove_empty_directories(&path);
2640 strbuf_release(&path);
2641
2642 if (result) {
2643 error("Directory not empty: %s", newrefname);
2644 goto rollback;
2645 }
2646 } else {
2647 error("unable to delete existing %s", newrefname);
2648 goto rollback;
2649 }
2650 }
2651
2652 if (log && rename_tmp_log(newrefname))
2653 goto rollback;
2654
2655 logmoved = log;
2656
2657 lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
2658 REF_NODEREF, NULL, &err);
2659 if (!lock) {
2660 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2661 strbuf_release(&err);
2662 goto rollback;
2663 }
2664 hashcpy(lock->old_oid.hash, orig_sha1);
2665
2666 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2667 commit_ref_update(refs, lock, orig_sha1, logmsg, &err)) {
2668 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2669 strbuf_release(&err);
2670 goto rollback;
2671 }
2672
2673 return 0;
2674
2675 rollback:
2676 lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
2677 REF_NODEREF, NULL, &err);
2678 if (!lock) {
2679 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2680 strbuf_release(&err);
2681 goto rollbacklog;
2682 }
2683
2684 flag = log_all_ref_updates;
2685 log_all_ref_updates = LOG_REFS_NONE;
2686 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2687 commit_ref_update(refs, lock, orig_sha1, NULL, &err)) {
2688 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2689 strbuf_release(&err);
2690 }
2691 log_all_ref_updates = flag;
2692
2693 rollbacklog:
2694 if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2695 error("unable to restore logfile %s from %s: %s",
2696 oldrefname, newrefname, strerror(errno));
2697 if (!logmoved && log &&
2698 rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2699 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2700 oldrefname, strerror(errno));
2701
2702 return 1;
2703 }
2704
2705 static int close_ref(struct ref_lock *lock)
2706 {
2707 if (close_lock_file(lock->lk))
2708 return -1;
2709 return 0;
2710 }
2711
2712 static int commit_ref(struct ref_lock *lock)
2713 {
2714 char *path = get_locked_file_path(lock->lk);
2715 struct stat st;
2716
2717 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2718 /*
2719 * There is a directory at the path we want to rename
2720 * the lockfile to. Hopefully it is empty; try to
2721 * delete it.
2722 */
2723 size_t len = strlen(path);
2724 struct strbuf sb_path = STRBUF_INIT;
2725
2726 strbuf_attach(&sb_path, path, len, len);
2727
2728 /*
2729 * If this fails, commit_lock_file() will also fail
2730 * and will report the problem.
2731 */
2732 remove_empty_directories(&sb_path);
2733 strbuf_release(&sb_path);
2734 } else {
2735 free(path);
2736 }
2737
2738 if (commit_lock_file(lock->lk))
2739 return -1;
2740 return 0;
2741 }
2742
2743 /*
2744 * Create a reflog for a ref. If force_create = 0, the reflog will
2745 * only be created for certain refs (those for which
2746 * should_autocreate_reflog returns non-zero. Otherwise, create it
2747 * regardless of the ref name. Fill in *err and return -1 on failure.
2748 */
2749 static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
2750 {
2751 int logfd, oflags = O_APPEND | O_WRONLY;
2752
2753 strbuf_git_path(logfile, "logs/%s", refname);
2754 if (force_create || should_autocreate_reflog(refname)) {
2755 if (safe_create_leading_directories(logfile->buf) < 0) {
2756 strbuf_addf(err, "unable to create directory for '%s': "
2757 "%s", logfile->buf, strerror(errno));
2758 return -1;
2759 }
2760 oflags |= O_CREAT;
2761 }
2762
2763 logfd = open(logfile->buf, oflags, 0666);
2764 if (logfd < 0) {
2765 if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
2766 return 0;
2767
2768 if (errno == EISDIR) {
2769 if (remove_empty_directories(logfile)) {
2770 strbuf_addf(err, "there are still logs under "
2771 "'%s'", logfile->buf);
2772 return -1;
2773 }
2774 logfd = open(logfile->buf, oflags, 0666);
2775 }
2776
2777 if (logfd < 0) {
2778 strbuf_addf(err, "unable to append to '%s': %s",
2779 logfile->buf, strerror(errno));
2780 return -1;
2781 }
2782 }
2783
2784 adjust_shared_perm(logfile->buf);
2785 close(logfd);
2786 return 0;
2787 }
2788
2789
2790 static int files_create_reflog(struct ref_store *ref_store,
2791 const char *refname, int force_create,
2792 struct strbuf *err)
2793 {
2794 int ret;
2795 struct strbuf sb = STRBUF_INIT;
2796
2797 /* Check validity (but we don't need the result): */
2798 files_downcast(ref_store, 0, "create_reflog");
2799
2800 ret = log_ref_setup(refname, &sb, err, force_create);
2801 strbuf_release(&sb);
2802 return ret;
2803 }
2804
2805 static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2806 const unsigned char *new_sha1,
2807 const char *committer, const char *msg)
2808 {
2809 int msglen, written;
2810 unsigned maxlen, len;
2811 char *logrec;
2812
2813 msglen = msg ? strlen(msg) : 0;
2814 maxlen = strlen(committer) + msglen + 100;
2815 logrec = xmalloc(maxlen);
2816 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2817 sha1_to_hex(old_sha1),
2818 sha1_to_hex(new_sha1),
2819 committer);
2820 if (msglen)
2821 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2822
2823 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2824 free(logrec);
2825 if (written != len)
2826 return -1;
2827
2828 return 0;
2829 }
2830
2831 static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
2832 const unsigned char *new_sha1, const char *msg,
2833 struct strbuf *logfile, int flags,
2834 struct strbuf *err)
2835 {
2836 int logfd, result, oflags = O_APPEND | O_WRONLY;
2837
2838 if (log_all_ref_updates == LOG_REFS_UNSET)
2839 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
2840
2841 result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
2842
2843 if (result)
2844 return result;
2845
2846 logfd = open(logfile->buf, oflags);
2847 if (logfd < 0)
2848 return 0;
2849 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2850 git_committer_info(0), msg);
2851 if (result) {
2852 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
2853 strerror(errno));
2854 close(logfd);
2855 return -1;
2856 }
2857 if (close(logfd)) {
2858 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
2859 strerror(errno));
2860 return -1;
2861 }
2862 return 0;
2863 }
2864
2865 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2866 const unsigned char *new_sha1, const char *msg,
2867 int flags, struct strbuf *err)
2868 {
2869 return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
2870 err);
2871 }
2872
2873 int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
2874 const unsigned char *new_sha1, const char *msg,
2875 int flags, struct strbuf *err)
2876 {
2877 struct strbuf sb = STRBUF_INIT;
2878 int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
2879 err);
2880 strbuf_release(&sb);
2881 return ret;
2882 }
2883
2884 /*
2885 * Write sha1 into the open lockfile, then close the lockfile. On
2886 * errors, rollback the lockfile, fill in *err and
2887 * return -1.
2888 */
2889 static int write_ref_to_lockfile(struct ref_lock *lock,
2890 const unsigned char *sha1, struct strbuf *err)
2891 {
2892 static char term = '\n';
2893 struct object *o;
2894 int fd;
2895
2896 o = parse_object(sha1);
2897 if (!o) {
2898 strbuf_addf(err,
2899 "trying to write ref '%s' with nonexistent object %s",
2900 lock->ref_name, sha1_to_hex(sha1));
2901 unlock_ref(lock);
2902 return -1;
2903 }
2904 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2905 strbuf_addf(err,
2906 "trying to write non-commit object %s to branch '%s'",
2907 sha1_to_hex(sha1), lock->ref_name);
2908 unlock_ref(lock);
2909 return -1;
2910 }
2911 fd = get_lock_file_fd(lock->lk);
2912 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
2913 write_in_full(fd, &term, 1) != 1 ||
2914 close_ref(lock) < 0) {
2915 strbuf_addf(err,
2916 "couldn't write '%s'", get_lock_file_path(lock->lk));
2917 unlock_ref(lock);
2918 return -1;
2919 }
2920 return 0;
2921 }
2922
2923 /*
2924 * Commit a change to a loose reference that has already been written
2925 * to the loose reference lockfile. Also update the reflogs if
2926 * necessary, using the specified lockmsg (which can be NULL).
2927 */
2928 static int commit_ref_update(struct files_ref_store *refs,
2929 struct ref_lock *lock,
2930 const unsigned char *sha1, const char *logmsg,
2931 struct strbuf *err)
2932 {
2933 assert_main_repository(&refs->base, "commit_ref_update");
2934
2935 clear_loose_ref_cache(refs);
2936 if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
2937 char *old_msg = strbuf_detach(err, NULL);
2938 strbuf_addf(err, "cannot update the ref '%s': %s",
2939 lock->ref_name, old_msg);
2940 free(old_msg);
2941 unlock_ref(lock);
2942 return -1;
2943 }
2944
2945 if (strcmp(lock->ref_name, "HEAD") != 0) {
2946 /*
2947 * Special hack: If a branch is updated directly and HEAD
2948 * points to it (may happen on the remote side of a push
2949 * for example) then logically the HEAD reflog should be
2950 * updated too.
2951 * A generic solution implies reverse symref information,
2952 * but finding all symrefs pointing to the given branch
2953 * would be rather costly for this rare event (the direct
2954 * update of a branch) to be worth it. So let's cheat and
2955 * check with HEAD only which should cover 99% of all usage
2956 * scenarios (even 100% of the default ones).
2957 */
2958 unsigned char head_sha1[20];
2959 int head_flag;
2960 const char *head_ref;
2961
2962 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
2963 head_sha1, &head_flag);
2964 if (head_ref && (head_flag & REF_ISSYMREF) &&
2965 !strcmp(head_ref, lock->ref_name)) {
2966 struct strbuf log_err = STRBUF_INIT;
2967 if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
2968 logmsg, 0, &log_err)) {
2969 error("%s", log_err.buf);
2970 strbuf_release(&log_err);
2971 }
2972 }
2973 }
2974
2975 if (commit_ref(lock)) {
2976 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
2977 unlock_ref(lock);
2978 return -1;
2979 }
2980
2981 unlock_ref(lock);
2982 return 0;
2983 }
2984
2985 static int create_ref_symlink(struct ref_lock *lock, const char *target)
2986 {
2987 int ret = -1;
2988 #ifndef NO_SYMLINK_HEAD
2989 char *ref_path = get_locked_file_path(lock->lk);
2990 unlink(ref_path);
2991 ret = symlink(target, ref_path);
2992 free(ref_path);
2993
2994 if (ret)
2995 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
2996 #endif
2997 return ret;
2998 }
2999
3000 static void update_symref_reflog(struct ref_lock *lock, const char *refname,
3001 const char *target, const char *logmsg)
3002 {
3003 struct strbuf err = STRBUF_INIT;
3004 unsigned char new_sha1[20];
3005 if (logmsg && !read_ref(target, new_sha1) &&
3006 log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
3007 error("%s", err.buf);
3008 strbuf_release(&err);
3009 }
3010 }
3011
3012 static int create_symref_locked(struct ref_lock *lock, const char *refname,
3013 const char *target, const char *logmsg)
3014 {
3015 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
3016 update_symref_reflog(lock, refname, target, logmsg);
3017 return 0;
3018 }
3019
3020 if (!fdopen_lock_file(lock->lk, "w"))
3021 return error("unable to fdopen %s: %s",
3022 lock->lk->tempfile.filename.buf, strerror(errno));
3023
3024 update_symref_reflog(lock, refname, target, logmsg);
3025
3026 /* no error check; commit_ref will check ferror */
3027 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
3028 if (commit_ref(lock) < 0)
3029 return error("unable to write symref for %s: %s", refname,
3030 strerror(errno));
3031 return 0;
3032 }
3033
3034 static int files_create_symref(struct ref_store *ref_store,
3035 const char *refname, const char *target,
3036 const char *logmsg)
3037 {
3038 struct files_ref_store *refs =
3039 files_downcast(ref_store, 0, "create_symref");
3040 struct strbuf err = STRBUF_INIT;
3041 struct ref_lock *lock;
3042 int ret;
3043
3044 lock = lock_ref_sha1_basic(refs, refname, NULL,
3045 NULL, NULL, REF_NODEREF, NULL,
3046 &err);
3047 if (!lock) {
3048 error("%s", err.buf);
3049 strbuf_release(&err);
3050 return -1;
3051 }
3052
3053 ret = create_symref_locked(lock, refname, target, logmsg);
3054 unlock_ref(lock);
3055 return ret;
3056 }
3057
3058 int set_worktree_head_symref(const char *gitdir, const char *target)
3059 {
3060 static struct lock_file head_lock;
3061 struct ref_lock *lock;
3062 struct strbuf head_path = STRBUF_INIT;
3063 const char *head_rel;
3064 int ret;
3065
3066 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3067 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3068 LOCK_NO_DEREF) < 0) {
3069 struct strbuf err = STRBUF_INIT;
3070 unable_to_lock_message(head_path.buf, errno, &err);
3071 error("%s", err.buf);
3072 strbuf_release(&err);
3073 strbuf_release(&head_path);
3074 return -1;
3075 }
3076
3077 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3078 linked trees */
3079 head_rel = remove_leading_path(head_path.buf,
3080 absolute_path(get_git_common_dir()));
3081 /* to make use of create_symref_locked(), initialize ref_lock */
3082 lock = xcalloc(1, sizeof(struct ref_lock));
3083 lock->lk = &head_lock;
3084 lock->ref_name = xstrdup(head_rel);
3085
3086 ret = create_symref_locked(lock, head_rel, target, NULL);
3087
3088 unlock_ref(lock); /* will free lock */
3089 strbuf_release(&head_path);
3090 return ret;
3091 }
3092
3093 static int files_reflog_exists(struct ref_store *ref_store,
3094 const char *refname)
3095 {
3096 struct stat st;
3097
3098 /* Check validity (but we don't need the result): */
3099 files_downcast(ref_store, 0, "reflog_exists");
3100
3101 return !lstat(git_path("logs/%s", refname), &st) &&
3102 S_ISREG(st.st_mode);
3103 }
3104
3105 static int files_delete_reflog(struct ref_store *ref_store,
3106 const char *refname)
3107 {
3108 /* Check validity (but we don't need the result): */
3109 files_downcast(ref_store, 0, "delete_reflog");
3110
3111 return remove_path(git_path("logs/%s", refname));
3112 }
3113
3114 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3115 {
3116 unsigned char osha1[20], nsha1[20];
3117 char *email_end, *message;
3118 unsigned long timestamp;
3119 int tz;
3120
3121 /* old SP new SP name <email> SP time TAB msg LF */
3122 if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3123 get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3124 get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3125 !(email_end = strchr(sb->buf + 82, '>')) ||
3126 email_end[1] != ' ' ||
3127 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3128 !message || message[0] != ' ' ||
3129 (message[1] != '+' && message[1] != '-') ||
3130 !isdigit(message[2]) || !isdigit(message[3]) ||
3131 !isdigit(message[4]) || !isdigit(message[5]))
3132 return 0; /* corrupt? */
3133 email_end[1] = '\0';
3134 tz = strtol(message + 1, NULL, 10);
3135 if (message[6] != '\t')
3136 message += 6;
3137 else
3138 message += 7;
3139 return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3140 }
3141
3142 static char *find_beginning_of_line(char *bob, char *scan)
3143 {
3144 while (bob < scan && *(--scan) != '\n')
3145 ; /* keep scanning backwards */
3146 /*
3147 * Return either beginning of the buffer, or LF at the end of
3148 * the previous line.
3149 */
3150 return scan;
3151 }
3152
3153 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
3154 const char *refname,
3155 each_reflog_ent_fn fn,
3156 void *cb_data)
3157 {
3158 struct strbuf sb = STRBUF_INIT;
3159 FILE *logfp;
3160 long pos;
3161 int ret = 0, at_tail = 1;
3162
3163 /* Check validity (but we don't need the result): */
3164 files_downcast(ref_store, 0, "for_each_reflog_ent_reverse");
3165
3166 logfp = fopen(git_path("logs/%s", refname), "r");
3167 if (!logfp)
3168 return -1;
3169
3170 /* Jump to the end */
3171 if (fseek(logfp, 0, SEEK_END) < 0)
3172 return error("cannot seek back reflog for %s: %s",
3173 refname, strerror(errno));
3174 pos = ftell(logfp);
3175 while (!ret && 0 < pos) {
3176 int cnt;
3177 size_t nread;
3178 char buf[BUFSIZ];
3179 char *endp, *scanp;
3180
3181 /* Fill next block from the end */
3182 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3183 if (fseek(logfp, pos - cnt, SEEK_SET))
3184 return error("cannot seek back reflog for %s: %s",
3185 refname, strerror(errno));
3186 nread = fread(buf, cnt, 1, logfp);
3187 if (nread != 1)
3188 return error("cannot read %d bytes from reflog for %s: %s",
3189 cnt, refname, strerror(errno));
3190 pos -= cnt;
3191
3192 scanp = endp = buf + cnt;
3193 if (at_tail && scanp[-1] == '\n')
3194 /* Looking at the final LF at the end of the file */
3195 scanp--;
3196 at_tail = 0;
3197
3198 while (buf < scanp) {
3199 /*
3200 * terminating LF of the previous line, or the beginning
3201 * of the buffer.
3202 */
3203 char *bp;
3204
3205 bp = find_beginning_of_line(buf, scanp);
3206
3207 if (*bp == '\n') {
3208 /*
3209 * The newline is the end of the previous line,
3210 * so we know we have complete line starting
3211 * at (bp + 1). Prefix it onto any prior data
3212 * we collected for the line and process it.
3213 */
3214 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3215 scanp = bp;
3216 endp = bp + 1;
3217 ret = show_one_reflog_ent(&sb, fn, cb_data);
3218 strbuf_reset(&sb);
3219 if (ret)
3220 break;
3221 } else if (!pos) {
3222 /*
3223 * We are at the start of the buffer, and the
3224 * start of the file; there is no previous
3225 * line, and we have everything for this one.
3226 * Process it, and we can end the loop.
3227 */
3228 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3229 ret = show_one_reflog_ent(&sb, fn, cb_data);
3230 strbuf_reset(&sb);
3231 break;
3232 }
3233
3234 if (bp == buf) {
3235 /*
3236 * We are at the start of the buffer, and there
3237 * is more file to read backwards. Which means
3238 * we are in the middle of a line. Note that we
3239 * may get here even if *bp was a newline; that
3240 * just means we are at the exact end of the
3241 * previous line, rather than some spot in the
3242 * middle.
3243 *
3244 * Save away what we have to be combined with
3245 * the data from the next read.
3246 */
3247 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3248 break;
3249 }
3250 }
3251
3252 }
3253 if (!ret && sb.len)
3254 die("BUG: reverse reflog parser had leftover data");
3255
3256 fclose(logfp);
3257 strbuf_release(&sb);
3258 return ret;
3259 }
3260
3261 static int files_for_each_reflog_ent(struct ref_store *ref_store,
3262 const char *refname,
3263 each_reflog_ent_fn fn, void *cb_data)
3264 {
3265 FILE *logfp;
3266 struct strbuf sb = STRBUF_INIT;
3267 int ret = 0;
3268
3269 /* Check validity (but we don't need the result): */
3270 files_downcast(ref_store, 0, "for_each_reflog_ent");
3271
3272 logfp = fopen(git_path("logs/%s", refname), "r");
3273 if (!logfp)
3274 return -1;
3275
3276 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3277 ret = show_one_reflog_ent(&sb, fn, cb_data);
3278 fclose(logfp);
3279 strbuf_release(&sb);
3280 return ret;
3281 }
3282
3283 struct files_reflog_iterator {
3284 struct ref_iterator base;
3285
3286 struct dir_iterator *dir_iterator;
3287 struct object_id oid;
3288 };
3289
3290 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
3291 {
3292 struct files_reflog_iterator *iter =
3293 (struct files_reflog_iterator *)ref_iterator;
3294 struct dir_iterator *diter = iter->dir_iterator;
3295 int ok;
3296
3297 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
3298 int flags;
3299
3300 if (!S_ISREG(diter->st.st_mode))
3301 continue;
3302 if (diter->basename[0] == '.')
3303 continue;
3304 if (ends_with(diter->basename, ".lock"))
3305 continue;
3306
3307 if (read_ref_full(diter->relative_path, 0,
3308 iter->oid.hash, &flags)) {
3309 error("bad ref for %s", diter->path.buf);
3310 continue;
3311 }
3312
3313 iter->base.refname = diter->relative_path;
3314 iter->base.oid = &iter->oid;
3315 iter->base.flags = flags;
3316 return ITER_OK;
3317 }
3318
3319 iter->dir_iterator = NULL;
3320 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
3321 ok = ITER_ERROR;
3322 return ok;
3323 }
3324
3325 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
3326 struct object_id *peeled)
3327 {
3328 die("BUG: ref_iterator_peel() called for reflog_iterator");
3329 }
3330
3331 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
3332 {
3333 struct files_reflog_iterator *iter =
3334 (struct files_reflog_iterator *)ref_iterator;
3335 int ok = ITER_DONE;
3336
3337 if (iter->dir_iterator)
3338 ok = dir_iterator_abort(iter->dir_iterator);
3339
3340 base_ref_iterator_free(ref_iterator);
3341 return ok;
3342 }
3343
3344 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
3345 files_reflog_iterator_advance,
3346 files_reflog_iterator_peel,
3347 files_reflog_iterator_abort
3348 };
3349
3350 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
3351 {
3352 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
3353 struct ref_iterator *ref_iterator = &iter->base;
3354
3355 /* Check validity (but we don't need the result): */
3356 files_downcast(ref_store, 0, "reflog_iterator_begin");
3357
3358 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
3359 iter->dir_iterator = dir_iterator_begin(git_path("logs"));
3360 return ref_iterator;
3361 }
3362
3363 static int ref_update_reject_duplicates(struct string_list *refnames,
3364 struct strbuf *err)
3365 {
3366 int i, n = refnames->nr;
3367
3368 assert(err);
3369
3370 for (i = 1; i < n; i++)
3371 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3372 strbuf_addf(err,
3373 "multiple updates for ref '%s' not allowed.",
3374 refnames->items[i].string);
3375 return 1;
3376 }
3377 return 0;
3378 }
3379
3380 /*
3381 * If update is a direct update of head_ref (the reference pointed to
3382 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3383 */
3384 static int split_head_update(struct ref_update *update,
3385 struct ref_transaction *transaction,
3386 const char *head_ref,
3387 struct string_list *affected_refnames,
3388 struct strbuf *err)
3389 {
3390 struct string_list_item *item;
3391 struct ref_update *new_update;
3392
3393 if ((update->flags & REF_LOG_ONLY) ||
3394 (update->flags & REF_ISPRUNING) ||
3395 (update->flags & REF_UPDATE_VIA_HEAD))
3396 return 0;
3397
3398 if (strcmp(update->refname, head_ref))
3399 return 0;
3400
3401 /*
3402 * First make sure that HEAD is not already in the
3403 * transaction. This insertion is O(N) in the transaction
3404 * size, but it happens at most once per transaction.
3405 */
3406 item = string_list_insert(affected_refnames, "HEAD");
3407 if (item->util) {
3408 /* An entry already existed */
3409 strbuf_addf(err,
3410 "multiple updates for 'HEAD' (including one "
3411 "via its referent '%s') are not allowed",
3412 update->refname);
3413 return TRANSACTION_NAME_CONFLICT;
3414 }
3415
3416 new_update = ref_transaction_add_update(
3417 transaction, "HEAD",
3418 update->flags | REF_LOG_ONLY | REF_NODEREF,
3419 update->new_sha1, update->old_sha1,
3420 update->msg);
3421
3422 item->util = new_update;
3423
3424 return 0;
3425 }
3426
3427 /*
3428 * update is for a symref that points at referent and doesn't have
3429 * REF_NODEREF set. Split it into two updates:
3430 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3431 * - A new, separate update for the referent reference
3432 * Note that the new update will itself be subject to splitting when
3433 * the iteration gets to it.
3434 */
3435 static int split_symref_update(struct files_ref_store *refs,
3436 struct ref_update *update,
3437 const char *referent,
3438 struct ref_transaction *transaction,
3439 struct string_list *affected_refnames,
3440 struct strbuf *err)
3441 {
3442 struct string_list_item *item;
3443 struct ref_update *new_update;
3444 unsigned int new_flags;
3445
3446 /*
3447 * First make sure that referent is not already in the
3448 * transaction. This insertion is O(N) in the transaction
3449 * size, but it happens at most once per symref in a
3450 * transaction.
3451 */
3452 item = string_list_insert(affected_refnames, referent);
3453 if (item->util) {
3454 /* An entry already existed */
3455 strbuf_addf(err,
3456 "multiple updates for '%s' (including one "
3457 "via symref '%s') are not allowed",
3458 referent, update->refname);
3459 return TRANSACTION_NAME_CONFLICT;
3460 }
3461
3462 new_flags = update->flags;
3463 if (!strcmp(update->refname, "HEAD")) {
3464 /*
3465 * Record that the new update came via HEAD, so that
3466 * when we process it, split_head_update() doesn't try
3467 * to add another reflog update for HEAD. Note that
3468 * this bit will be propagated if the new_update
3469 * itself needs to be split.
3470 */
3471 new_flags |= REF_UPDATE_VIA_HEAD;
3472 }
3473
3474 new_update = ref_transaction_add_update(
3475 transaction, referent, new_flags,
3476 update->new_sha1, update->old_sha1,
3477 update->msg);
3478
3479 new_update->parent_update = update;
3480
3481 /*
3482 * Change the symbolic ref update to log only. Also, it
3483 * doesn't need to check its old SHA-1 value, as that will be
3484 * done when new_update is processed.
3485 */
3486 update->flags |= REF_LOG_ONLY | REF_NODEREF;
3487 update->flags &= ~REF_HAVE_OLD;
3488
3489 item->util = new_update;
3490
3491 return 0;
3492 }
3493
3494 /*
3495 * Return the refname under which update was originally requested.
3496 */
3497 static const char *original_update_refname(struct ref_update *update)
3498 {
3499 while (update->parent_update)
3500 update = update->parent_update;
3501
3502 return update->refname;
3503 }
3504
3505 /*
3506 * Check whether the REF_HAVE_OLD and old_oid values stored in update
3507 * are consistent with oid, which is the reference's current value. If
3508 * everything is OK, return 0; otherwise, write an error message to
3509 * err and return -1.
3510 */
3511 static int check_old_oid(struct ref_update *update, struct object_id *oid,
3512 struct strbuf *err)
3513 {
3514 if (!(update->flags & REF_HAVE_OLD) ||
3515 !hashcmp(oid->hash, update->old_sha1))
3516 return 0;
3517
3518 if (is_null_sha1(update->old_sha1))
3519 strbuf_addf(err, "cannot lock ref '%s': "
3520 "reference already exists",
3521 original_update_refname(update));
3522 else if (is_null_oid(oid))
3523 strbuf_addf(err, "cannot lock ref '%s': "
3524 "reference is missing but expected %s",
3525 original_update_refname(update),
3526 sha1_to_hex(update->old_sha1));
3527 else
3528 strbuf_addf(err, "cannot lock ref '%s': "
3529 "is at %s but expected %s",
3530 original_update_refname(update),
3531 oid_to_hex(oid),
3532 sha1_to_hex(update->old_sha1));
3533
3534 return -1;
3535 }
3536
3537 /*
3538 * Prepare for carrying out update:
3539 * - Lock the reference referred to by update.
3540 * - Read the reference under lock.
3541 * - Check that its old SHA-1 value (if specified) is correct, and in
3542 * any case record it in update->lock->old_oid for later use when
3543 * writing the reflog.
3544 * - If it is a symref update without REF_NODEREF, split it up into a
3545 * REF_LOG_ONLY update of the symref and add a separate update for
3546 * the referent to transaction.
3547 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3548 * update of HEAD.
3549 */
3550 static int lock_ref_for_update(struct files_ref_store *refs,
3551 struct ref_update *update,
3552 struct ref_transaction *transaction,
3553 const char *head_ref,
3554 struct string_list *affected_refnames,
3555 struct strbuf *err)
3556 {
3557 struct strbuf referent = STRBUF_INIT;
3558 int mustexist = (update->flags & REF_HAVE_OLD) &&
3559 !is_null_sha1(update->old_sha1);
3560 int ret;
3561 struct ref_lock *lock;
3562
3563 assert_main_repository(&refs->base, "lock_ref_for_update");
3564
3565 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
3566 update->flags |= REF_DELETING;
3567
3568 if (head_ref) {
3569 ret = split_head_update(update, transaction, head_ref,
3570 affected_refnames, err);
3571 if (ret)
3572 return ret;
3573 }
3574
3575 ret = lock_raw_ref(refs, update->refname, mustexist,
3576 affected_refnames, NULL,
3577 &lock, &referent,
3578 &update->type, err);
3579 if (ret) {
3580 char *reason;
3581
3582 reason = strbuf_detach(err, NULL);
3583 strbuf_addf(err, "cannot lock ref '%s': %s",
3584 original_update_refname(update), reason);
3585 free(reason);
3586 return ret;
3587 }
3588
3589 update->backend_data = lock;
3590
3591 if (update->type & REF_ISSYMREF) {
3592 if (update->flags & REF_NODEREF) {
3593 /*
3594 * We won't be reading the referent as part of
3595 * the transaction, so we have to read it here
3596 * to record and possibly check old_sha1:
3597 */
3598 if (read_ref_full(referent.buf, 0,
3599 lock->old_oid.hash, NULL)) {
3600 if (update->flags & REF_HAVE_OLD) {
3601 strbuf_addf(err, "cannot lock ref '%s': "
3602 "error reading reference",
3603 original_update_refname(update));
3604 return -1;
3605 }
3606 } else if (check_old_oid(update, &lock->old_oid, err)) {
3607 return TRANSACTION_GENERIC_ERROR;
3608 }
3609 } else {
3610 /*
3611 * Create a new update for the reference this
3612 * symref is pointing at. Also, we will record
3613 * and verify old_sha1 for this update as part
3614 * of processing the split-off update, so we
3615 * don't have to do it here.
3616 */
3617 ret = split_symref_update(refs, update,
3618 referent.buf, transaction,
3619 affected_refnames, err);
3620 if (ret)
3621 return ret;
3622 }
3623 } else {
3624 struct ref_update *parent_update;
3625
3626 if (check_old_oid(update, &lock->old_oid, err))
3627 return TRANSACTION_GENERIC_ERROR;
3628
3629 /*
3630 * If this update is happening indirectly because of a
3631 * symref update, record the old SHA-1 in the parent
3632 * update:
3633 */
3634 for (parent_update = update->parent_update;
3635 parent_update;
3636 parent_update = parent_update->parent_update) {
3637 struct ref_lock *parent_lock = parent_update->backend_data;
3638 oidcpy(&parent_lock->old_oid, &lock->old_oid);
3639 }
3640 }
3641
3642 if ((update->flags & REF_HAVE_NEW) &&
3643 !(update->flags & REF_DELETING) &&
3644 !(update->flags & REF_LOG_ONLY)) {
3645 if (!(update->type & REF_ISSYMREF) &&
3646 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
3647 /*
3648 * The reference already has the desired
3649 * value, so we don't need to write it.
3650 */
3651 } else if (write_ref_to_lockfile(lock, update->new_sha1,
3652 err)) {
3653 char *write_err = strbuf_detach(err, NULL);
3654
3655 /*
3656 * The lock was freed upon failure of
3657 * write_ref_to_lockfile():
3658 */
3659 update->backend_data = NULL;
3660 strbuf_addf(err,
3661 "cannot update ref '%s': %s",
3662 update->refname, write_err);
3663 free(write_err);
3664 return TRANSACTION_GENERIC_ERROR;
3665 } else {
3666 update->flags |= REF_NEEDS_COMMIT;
3667 }
3668 }
3669 if (!(update->flags & REF_NEEDS_COMMIT)) {
3670 /*
3671 * We didn't call write_ref_to_lockfile(), so
3672 * the lockfile is still open. Close it to
3673 * free up the file descriptor:
3674 */
3675 if (close_ref(lock)) {
3676 strbuf_addf(err, "couldn't close '%s.lock'",
3677 update->refname);
3678 return TRANSACTION_GENERIC_ERROR;
3679 }
3680 }
3681 return 0;
3682 }
3683
3684 static int files_transaction_commit(struct ref_store *ref_store,
3685 struct ref_transaction *transaction,
3686 struct strbuf *err)
3687 {
3688 struct files_ref_store *refs =
3689 files_downcast(ref_store, 0, "ref_transaction_commit");
3690 int ret = 0, i;
3691 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3692 struct string_list_item *ref_to_delete;
3693 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
3694 char *head_ref = NULL;
3695 int head_type;
3696 struct object_id head_oid;
3697
3698 assert(err);
3699
3700 if (transaction->state != REF_TRANSACTION_OPEN)
3701 die("BUG: commit called for transaction that is not open");
3702
3703 if (!transaction->nr) {
3704 transaction->state = REF_TRANSACTION_CLOSED;
3705 return 0;
3706 }
3707
3708 /*
3709 * Fail if a refname appears more than once in the
3710 * transaction. (If we end up splitting up any updates using
3711 * split_symref_update() or split_head_update(), those
3712 * functions will check that the new updates don't have the
3713 * same refname as any existing ones.)
3714 */
3715 for (i = 0; i < transaction->nr; i++) {
3716 struct ref_update *update = transaction->updates[i];
3717 struct string_list_item *item =
3718 string_list_append(&affected_refnames, update->refname);
3719
3720 /*
3721 * We store a pointer to update in item->util, but at
3722 * the moment we never use the value of this field
3723 * except to check whether it is non-NULL.
3724 */
3725 item->util = update;
3726 }
3727 string_list_sort(&affected_refnames);
3728 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3729 ret = TRANSACTION_GENERIC_ERROR;
3730 goto cleanup;
3731 }
3732
3733 /*
3734 * Special hack: If a branch is updated directly and HEAD
3735 * points to it (may happen on the remote side of a push
3736 * for example) then logically the HEAD reflog should be
3737 * updated too.
3738 *
3739 * A generic solution would require reverse symref lookups,
3740 * but finding all symrefs pointing to a given branch would be
3741 * rather costly for this rare event (the direct update of a
3742 * branch) to be worth it. So let's cheat and check with HEAD
3743 * only, which should cover 99% of all usage scenarios (even
3744 * 100% of the default ones).
3745 *
3746 * So if HEAD is a symbolic reference, then record the name of
3747 * the reference that it points to. If we see an update of
3748 * head_ref within the transaction, then split_head_update()
3749 * arranges for the reflog of HEAD to be updated, too.
3750 */
3751 head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
3752 head_oid.hash, &head_type);
3753
3754 if (head_ref && !(head_type & REF_ISSYMREF)) {
3755 free(head_ref);
3756 head_ref = NULL;
3757 }
3758
3759 /*
3760 * Acquire all locks, verify old values if provided, check
3761 * that new values are valid, and write new values to the
3762 * lockfiles, ready to be activated. Only keep one lockfile
3763 * open at a time to avoid running out of file descriptors.
3764 */
3765 for (i = 0; i < transaction->nr; i++) {
3766 struct ref_update *update = transaction->updates[i];
3767
3768 ret = lock_ref_for_update(refs, update, transaction,
3769 head_ref, &affected_refnames, err);
3770 if (ret)
3771 goto cleanup;
3772 }
3773
3774 /* Perform updates first so live commits remain referenced */
3775 for (i = 0; i < transaction->nr; i++) {
3776 struct ref_update *update = transaction->updates[i];
3777 struct ref_lock *lock = update->backend_data;
3778
3779 if (update->flags & REF_NEEDS_COMMIT ||
3780 update->flags & REF_LOG_ONLY) {
3781 if (log_ref_write(lock->ref_name, lock->old_oid.hash,
3782 update->new_sha1,
3783 update->msg, update->flags, err)) {
3784 char *old_msg = strbuf_detach(err, NULL);
3785
3786 strbuf_addf(err, "cannot update the ref '%s': %s",
3787 lock->ref_name, old_msg);
3788 free(old_msg);
3789 unlock_ref(lock);
3790 update->backend_data = NULL;
3791 ret = TRANSACTION_GENERIC_ERROR;
3792 goto cleanup;
3793 }
3794 }
3795 if (update->flags & REF_NEEDS_COMMIT) {
3796 clear_loose_ref_cache(refs);
3797 if (commit_ref(lock)) {
3798 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3799 unlock_ref(lock);
3800 update->backend_data = NULL;
3801 ret = TRANSACTION_GENERIC_ERROR;
3802 goto cleanup;
3803 }
3804 }
3805 }
3806 /* Perform deletes now that updates are safely completed */
3807 for (i = 0; i < transaction->nr; i++) {
3808 struct ref_update *update = transaction->updates[i];
3809 struct ref_lock *lock = update->backend_data