Merge tag 'v2.9.5' into maint-2.10
[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 ref_cache;
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 ref_cache that contains this ref_dir. */
82 struct ref_cache *ref_cache;
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 ref_cache *ref_cache,
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_cache,
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 ref_cache *ref_cache,
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_cache = ref_cache;
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_cache, 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, sizeof(*dir->entries), 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 hashcpy(peeled->hash, entry->u.value.peeled.hash);
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 ref_cache::packed if any. The
891 * data will not be freed as long as the reference count is
892 * 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 static struct ref_cache {
914 struct ref_cache *next;
915 struct ref_entry *loose;
916 struct packed_ref_cache *packed;
917 /*
918 * The submodule name, or "" for the main repo. We allocate
919 * length 1 rather than FLEX_ARRAY so that the main ref_cache
920 * is initialized correctly.
921 */
922 char name[1];
923 } ref_cache, *submodule_ref_caches;
924
925 /* Lock used for the main packed-refs file: */
926 static struct lock_file packlock;
927
928 /*
929 * Increment the reference count of *packed_refs.
930 */
931 static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
932 {
933 packed_refs->referrers++;
934 }
935
936 /*
937 * Decrease the reference count of *packed_refs. If it goes to zero,
938 * free *packed_refs and return true; otherwise return false.
939 */
940 static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
941 {
942 if (!--packed_refs->referrers) {
943 free_ref_entry(packed_refs->root);
944 stat_validity_clear(&packed_refs->validity);
945 free(packed_refs);
946 return 1;
947 } else {
948 return 0;
949 }
950 }
951
952 static void clear_packed_ref_cache(struct ref_cache *refs)
953 {
954 if (refs->packed) {
955 struct packed_ref_cache *packed_refs = refs->packed;
956
957 if (packed_refs->lock)
958 die("internal error: packed-ref cache cleared while locked");
959 refs->packed = NULL;
960 release_packed_ref_cache(packed_refs);
961 }
962 }
963
964 static void clear_loose_ref_cache(struct ref_cache *refs)
965 {
966 if (refs->loose) {
967 free_ref_entry(refs->loose);
968 refs->loose = NULL;
969 }
970 }
971
972 /*
973 * Create a new submodule ref cache and add it to the internal
974 * set of caches.
975 */
976 static struct ref_cache *create_ref_cache(const char *submodule)
977 {
978 struct ref_cache *refs;
979 if (!submodule)
980 submodule = "";
981 FLEX_ALLOC_STR(refs, name, submodule);
982 refs->next = submodule_ref_caches;
983 submodule_ref_caches = refs;
984 return refs;
985 }
986
987 static struct ref_cache *lookup_ref_cache(const char *submodule)
988 {
989 struct ref_cache *refs;
990
991 if (!submodule || !*submodule)
992 return &ref_cache;
993
994 for (refs = submodule_ref_caches; refs; refs = refs->next)
995 if (!strcmp(submodule, refs->name))
996 return refs;
997 return NULL;
998 }
999
1000 /*
1001 * Return a pointer to a ref_cache for the specified submodule. For
1002 * the main repository, use submodule==NULL; such a call cannot fail.
1003 * For a submodule, the submodule must exist and be a nonbare
1004 * repository, otherwise return NULL.
1005 *
1006 * The returned structure will be allocated and initialized but not
1007 * necessarily populated; it should not be freed.
1008 */
1009 static struct ref_cache *get_ref_cache(const char *submodule)
1010 {
1011 struct ref_cache *refs = lookup_ref_cache(submodule);
1012
1013 if (!refs) {
1014 struct strbuf submodule_sb = STRBUF_INIT;
1015
1016 strbuf_addstr(&submodule_sb, submodule);
1017 if (is_nonbare_repository_dir(&submodule_sb))
1018 refs = create_ref_cache(submodule);
1019 strbuf_release(&submodule_sb);
1020 }
1021
1022 return refs;
1023 }
1024
1025 /* The length of a peeled reference line in packed-refs, including EOL: */
1026 #define PEELED_LINE_LENGTH 42
1027
1028 /*
1029 * The packed-refs header line that we write out. Perhaps other
1030 * traits will be added later. The trailing space is required.
1031 */
1032 static const char PACKED_REFS_HEADER[] =
1033 "# pack-refs with: peeled fully-peeled \n";
1034
1035 /*
1036 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
1037 * Return a pointer to the refname within the line (null-terminated),
1038 * or NULL if there was a problem.
1039 */
1040 static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
1041 {
1042 const char *ref;
1043
1044 /*
1045 * 42: the answer to everything.
1046 *
1047 * In this case, it happens to be the answer to
1048 * 40 (length of sha1 hex representation)
1049 * +1 (space in between hex and name)
1050 * +1 (newline at the end of the line)
1051 */
1052 if (line->len <= 42)
1053 return NULL;
1054
1055 if (get_sha1_hex(line->buf, sha1) < 0)
1056 return NULL;
1057 if (!isspace(line->buf[40]))
1058 return NULL;
1059
1060 ref = line->buf + 41;
1061 if (isspace(*ref))
1062 return NULL;
1063
1064 if (line->buf[line->len - 1] != '\n')
1065 return NULL;
1066 line->buf[--line->len] = 0;
1067
1068 return ref;
1069 }
1070
1071 /*
1072 * Read f, which is a packed-refs file, into dir.
1073 *
1074 * A comment line of the form "# pack-refs with: " may contain zero or
1075 * more traits. We interpret the traits as follows:
1076 *
1077 * No traits:
1078 *
1079 * Probably no references are peeled. But if the file contains a
1080 * peeled value for a reference, we will use it.
1081 *
1082 * peeled:
1083 *
1084 * References under "refs/tags/", if they *can* be peeled, *are*
1085 * peeled in this file. References outside of "refs/tags/" are
1086 * probably not peeled even if they could have been, but if we find
1087 * a peeled value for such a reference we will use it.
1088 *
1089 * fully-peeled:
1090 *
1091 * All references in the file that can be peeled are peeled.
1092 * Inversely (and this is more important), any references in the
1093 * file for which no peeled value is recorded is not peelable. This
1094 * trait should typically be written alongside "peeled" for
1095 * compatibility with older clients, but we do not require it
1096 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1097 */
1098 static void read_packed_refs(FILE *f, struct ref_dir *dir)
1099 {
1100 struct ref_entry *last = NULL;
1101 struct strbuf line = STRBUF_INIT;
1102 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1103
1104 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1105 unsigned char sha1[20];
1106 const char *refname;
1107 const char *traits;
1108
1109 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1110 if (strstr(traits, " fully-peeled "))
1111 peeled = PEELED_FULLY;
1112 else if (strstr(traits, " peeled "))
1113 peeled = PEELED_TAGS;
1114 /* perhaps other traits later as well */
1115 continue;
1116 }
1117
1118 refname = parse_ref_line(&line, sha1);
1119 if (refname) {
1120 int flag = REF_ISPACKED;
1121
1122 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1123 if (!refname_is_safe(refname))
1124 die("packed refname is dangerous: %s", refname);
1125 hashclr(sha1);
1126 flag |= REF_BAD_NAME | REF_ISBROKEN;
1127 }
1128 last = create_ref_entry(refname, sha1, flag, 0);
1129 if (peeled == PEELED_FULLY ||
1130 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1131 last->flag |= REF_KNOWS_PEELED;
1132 add_ref(dir, last);
1133 continue;
1134 }
1135 if (last &&
1136 line.buf[0] == '^' &&
1137 line.len == PEELED_LINE_LENGTH &&
1138 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1139 !get_sha1_hex(line.buf + 1, sha1)) {
1140 hashcpy(last->u.value.peeled.hash, sha1);
1141 /*
1142 * Regardless of what the file header said,
1143 * we definitely know the value of *this*
1144 * reference:
1145 */
1146 last->flag |= REF_KNOWS_PEELED;
1147 }
1148 }
1149
1150 strbuf_release(&line);
1151 }
1152
1153 /*
1154 * Get the packed_ref_cache for the specified ref_cache, creating it
1155 * if necessary.
1156 */
1157 static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1158 {
1159 char *packed_refs_file;
1160
1161 if (*refs->name)
1162 packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
1163 else
1164 packed_refs_file = git_pathdup("packed-refs");
1165
1166 if (refs->packed &&
1167 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1168 clear_packed_ref_cache(refs);
1169
1170 if (!refs->packed) {
1171 FILE *f;
1172
1173 refs->packed = xcalloc(1, sizeof(*refs->packed));
1174 acquire_packed_ref_cache(refs->packed);
1175 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1176 f = fopen(packed_refs_file, "r");
1177 if (f) {
1178 stat_validity_update(&refs->packed->validity, fileno(f));
1179 read_packed_refs(f, get_ref_dir(refs->packed->root));
1180 fclose(f);
1181 }
1182 }
1183 free(packed_refs_file);
1184 return refs->packed;
1185 }
1186
1187 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1188 {
1189 return get_ref_dir(packed_ref_cache->root);
1190 }
1191
1192 static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1193 {
1194 return get_packed_ref_dir(get_packed_ref_cache(refs));
1195 }
1196
1197 /*
1198 * Add a reference to the in-memory packed reference cache. This may
1199 * only be called while the packed-refs file is locked (see
1200 * lock_packed_refs()). To actually write the packed-refs file, call
1201 * commit_packed_refs().
1202 */
1203 static void add_packed_ref(const char *refname, const unsigned char *sha1)
1204 {
1205 struct packed_ref_cache *packed_ref_cache =
1206 get_packed_ref_cache(&ref_cache);
1207
1208 if (!packed_ref_cache->lock)
1209 die("internal error: packed refs not locked");
1210 add_ref(get_packed_ref_dir(packed_ref_cache),
1211 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1212 }
1213
1214 /*
1215 * Read the loose references from the namespace dirname into dir
1216 * (without recursing). dirname must end with '/'. dir must be the
1217 * directory entry corresponding to dirname.
1218 */
1219 static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1220 {
1221 struct ref_cache *refs = dir->ref_cache;
1222 DIR *d;
1223 struct dirent *de;
1224 int dirnamelen = strlen(dirname);
1225 struct strbuf refname;
1226 struct strbuf path = STRBUF_INIT;
1227 size_t path_baselen;
1228
1229 if (*refs->name)
1230 strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
1231 else
1232 strbuf_git_path(&path, "%s", dirname);
1233 path_baselen = path.len;
1234
1235 d = opendir(path.buf);
1236 if (!d) {
1237 strbuf_release(&path);
1238 return;
1239 }
1240
1241 strbuf_init(&refname, dirnamelen + 257);
1242 strbuf_add(&refname, dirname, dirnamelen);
1243
1244 while ((de = readdir(d)) != NULL) {
1245 unsigned char sha1[20];
1246 struct stat st;
1247 int flag;
1248
1249 if (de->d_name[0] == '.')
1250 continue;
1251 if (ends_with(de->d_name, ".lock"))
1252 continue;
1253 strbuf_addstr(&refname, de->d_name);
1254 strbuf_addstr(&path, de->d_name);
1255 if (stat(path.buf, &st) < 0) {
1256 ; /* silently ignore */
1257 } else if (S_ISDIR(st.st_mode)) {
1258 strbuf_addch(&refname, '/');
1259 add_entry_to_dir(dir,
1260 create_dir_entry(refs, refname.buf,
1261 refname.len, 1));
1262 } else {
1263 int read_ok;
1264
1265 if (*refs->name) {
1266 hashclr(sha1);
1267 flag = 0;
1268 read_ok = !resolve_gitlink_ref(refs->name,
1269 refname.buf, sha1);
1270 } else {
1271 read_ok = !read_ref_full(refname.buf,
1272 RESOLVE_REF_READING,
1273 sha1, &flag);
1274 }
1275
1276 if (!read_ok) {
1277 hashclr(sha1);
1278 flag |= REF_ISBROKEN;
1279 } else if (is_null_sha1(sha1)) {
1280 /*
1281 * It is so astronomically unlikely
1282 * that NULL_SHA1 is the SHA-1 of an
1283 * actual object that we consider its
1284 * appearance in a loose reference
1285 * file to be repo corruption
1286 * (probably due to a software bug).
1287 */
1288 flag |= REF_ISBROKEN;
1289 }
1290
1291 if (check_refname_format(refname.buf,
1292 REFNAME_ALLOW_ONELEVEL)) {
1293 if (!refname_is_safe(refname.buf))
1294 die("loose refname is dangerous: %s", refname.buf);
1295 hashclr(sha1);
1296 flag |= REF_BAD_NAME | REF_ISBROKEN;
1297 }
1298 add_entry_to_dir(dir,
1299 create_ref_entry(refname.buf, sha1, flag, 0));
1300 }
1301 strbuf_setlen(&refname, dirnamelen);
1302 strbuf_setlen(&path, path_baselen);
1303 }
1304 strbuf_release(&refname);
1305 strbuf_release(&path);
1306 closedir(d);
1307 }
1308
1309 static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1310 {
1311 if (!refs->loose) {
1312 /*
1313 * Mark the top-level directory complete because we
1314 * are about to read the only subdirectory that can
1315 * hold references:
1316 */
1317 refs->loose = create_dir_entry(refs, "", 0, 0);
1318 /*
1319 * Create an incomplete entry for "refs/":
1320 */
1321 add_entry_to_dir(get_ref_dir(refs->loose),
1322 create_dir_entry(refs, "refs/", 5, 1));
1323 }
1324 return get_ref_dir(refs->loose);
1325 }
1326
1327 #define MAXREFLEN (1024)
1328
1329 /*
1330 * Called by resolve_gitlink_ref_recursive() after it failed to read
1331 * from the loose refs in ref_cache refs. Find <refname> in the
1332 * packed-refs file for the submodule.
1333 */
1334 static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1335 const char *refname, unsigned char *sha1)
1336 {
1337 struct ref_entry *ref;
1338 struct ref_dir *dir = get_packed_refs(refs);
1339
1340 ref = find_ref(dir, refname);
1341 if (ref == NULL)
1342 return -1;
1343
1344 hashcpy(sha1, ref->u.value.oid.hash);
1345 return 0;
1346 }
1347
1348 static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1349 const char *refname, unsigned char *sha1,
1350 int recursion)
1351 {
1352 int fd, len;
1353 char buffer[128], *p;
1354 char *path;
1355
1356 if (recursion > SYMREF_MAXDEPTH || strlen(refname) > MAXREFLEN)
1357 return -1;
1358 path = *refs->name
1359 ? git_pathdup_submodule(refs->name, "%s", refname)
1360 : git_pathdup("%s", refname);
1361 fd = open(path, O_RDONLY);
1362 free(path);
1363 if (fd < 0)
1364 return resolve_gitlink_packed_ref(refs, refname, sha1);
1365
1366 len = read(fd, buffer, sizeof(buffer)-1);
1367 close(fd);
1368 if (len < 0)
1369 return -1;
1370 while (len && isspace(buffer[len-1]))
1371 len--;
1372 buffer[len] = 0;
1373
1374 /* Was it a detached head or an old-fashioned symlink? */
1375 if (!get_sha1_hex(buffer, sha1))
1376 return 0;
1377
1378 /* Symref? */
1379 if (strncmp(buffer, "ref:", 4))
1380 return -1;
1381 p = buffer + 4;
1382 while (isspace(*p))
1383 p++;
1384
1385 return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1386 }
1387
1388 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1389 {
1390 int len = strlen(path), retval;
1391 struct strbuf submodule = STRBUF_INIT;
1392 struct ref_cache *refs;
1393
1394 while (len && path[len-1] == '/')
1395 len--;
1396 if (!len)
1397 return -1;
1398
1399 strbuf_add(&submodule, path, len);
1400 refs = get_ref_cache(submodule.buf);
1401 if (!refs) {
1402 strbuf_release(&submodule);
1403 return -1;
1404 }
1405 strbuf_release(&submodule);
1406
1407 retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1408 return retval;
1409 }
1410
1411 /*
1412 * Return the ref_entry for the given refname from the packed
1413 * references. If it does not exist, return NULL.
1414 */
1415 static struct ref_entry *get_packed_ref(const char *refname)
1416 {
1417 return find_ref(get_packed_refs(&ref_cache), refname);
1418 }
1419
1420 /*
1421 * A loose ref file doesn't exist; check for a packed ref.
1422 */
1423 static int resolve_missing_loose_ref(const char *refname,
1424 unsigned char *sha1,
1425 unsigned int *flags)
1426 {
1427 struct ref_entry *entry;
1428
1429 /*
1430 * The loose reference file does not exist; check for a packed
1431 * reference.
1432 */
1433 entry = get_packed_ref(refname);
1434 if (entry) {
1435 hashcpy(sha1, entry->u.value.oid.hash);
1436 *flags |= REF_ISPACKED;
1437 return 0;
1438 }
1439 /* refname is not a packed reference. */
1440 return -1;
1441 }
1442
1443 int read_raw_ref(const char *refname, unsigned char *sha1,
1444 struct strbuf *referent, unsigned int *type)
1445 {
1446 struct strbuf sb_contents = STRBUF_INIT;
1447 struct strbuf sb_path = STRBUF_INIT;
1448 const char *path;
1449 const char *buf;
1450 struct stat st;
1451 int fd;
1452 int ret = -1;
1453 int save_errno;
1454 int remaining_retries = 3;
1455
1456 *type = 0;
1457 strbuf_reset(&sb_path);
1458 strbuf_git_path(&sb_path, "%s", refname);
1459 path = sb_path.buf;
1460
1461 stat_ref:
1462 /*
1463 * We might have to loop back here to avoid a race
1464 * condition: first we lstat() the file, then we try
1465 * to read it as a link or as a file. But if somebody
1466 * changes the type of the file (file <-> directory
1467 * <-> symlink) between the lstat() and reading, then
1468 * we don't want to report that as an error but rather
1469 * try again starting with the lstat().
1470 *
1471 * We'll keep a count of the retries, though, just to avoid
1472 * any confusing situation sending us into an infinite loop.
1473 */
1474
1475 if (remaining_retries-- <= 0)
1476 goto out;
1477
1478 if (lstat(path, &st) < 0) {
1479 if (errno != ENOENT)
1480 goto out;
1481 if (resolve_missing_loose_ref(refname, sha1, type)) {
1482 errno = ENOENT;
1483 goto out;
1484 }
1485 ret = 0;
1486 goto out;
1487 }
1488
1489 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1490 if (S_ISLNK(st.st_mode)) {
1491 strbuf_reset(&sb_contents);
1492 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
1493 if (errno == ENOENT || errno == EINVAL)
1494 /* inconsistent with lstat; retry */
1495 goto stat_ref;
1496 else
1497 goto out;
1498 }
1499 if (starts_with(sb_contents.buf, "refs/") &&
1500 !check_refname_format(sb_contents.buf, 0)) {
1501 strbuf_swap(&sb_contents, referent);
1502 *type |= REF_ISSYMREF;
1503 ret = 0;
1504 goto out;
1505 }
1506 /*
1507 * It doesn't look like a refname; fall through to just
1508 * treating it like a non-symlink, and reading whatever it
1509 * points to.
1510 */
1511 }
1512
1513 /* Is it a directory? */
1514 if (S_ISDIR(st.st_mode)) {
1515 /*
1516 * Even though there is a directory where the loose
1517 * ref is supposed to be, there could still be a
1518 * packed ref:
1519 */
1520 if (resolve_missing_loose_ref(refname, sha1, type)) {
1521 errno = EISDIR;
1522 goto out;
1523 }
1524 ret = 0;
1525 goto out;
1526 }
1527
1528 /*
1529 * Anything else, just open it and try to use it as
1530 * a ref
1531 */
1532 fd = open(path, O_RDONLY);
1533 if (fd < 0) {
1534 if (errno == ENOENT && !S_ISLNK(st.st_mode))
1535 /* inconsistent with lstat; retry */
1536 goto stat_ref;
1537 else
1538 goto out;
1539 }
1540 strbuf_reset(&sb_contents);
1541 if (strbuf_read(&sb_contents, fd, 256) < 0) {
1542 int save_errno = errno;
1543 close(fd);
1544 errno = save_errno;
1545 goto out;
1546 }
1547 close(fd);
1548 strbuf_rtrim(&sb_contents);
1549 buf = sb_contents.buf;
1550 if (starts_with(buf, "ref:")) {
1551 buf += 4;
1552 while (isspace(*buf))
1553 buf++;
1554
1555 strbuf_reset(referent);
1556 strbuf_addstr(referent, buf);
1557 *type |= REF_ISSYMREF;
1558 ret = 0;
1559 goto out;
1560 }
1561
1562 /*
1563 * Please note that FETCH_HEAD has additional
1564 * data after the sha.
1565 */
1566 if (get_sha1_hex(buf, sha1) ||
1567 (buf[40] != '\0' && !isspace(buf[40]))) {
1568 *type |= REF_ISBROKEN;
1569 errno = EINVAL;
1570 goto out;
1571 }
1572
1573 ret = 0;
1574
1575 out:
1576 save_errno = errno;
1577 strbuf_release(&sb_path);
1578 strbuf_release(&sb_contents);
1579 errno = save_errno;
1580 return ret;
1581 }
1582
1583 static void unlock_ref(struct ref_lock *lock)
1584 {
1585 /* Do not free lock->lk -- atexit() still looks at them */
1586 if (lock->lk)
1587 rollback_lock_file(lock->lk);
1588 free(lock->ref_name);
1589 free(lock);
1590 }
1591
1592 /*
1593 * Lock refname, without following symrefs, and set *lock_p to point
1594 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1595 * and type similarly to read_raw_ref().
1596 *
1597 * The caller must verify that refname is a "safe" reference name (in
1598 * the sense of refname_is_safe()) before calling this function.
1599 *
1600 * If the reference doesn't already exist, verify that refname doesn't
1601 * have a D/F conflict with any existing references. extras and skip
1602 * are passed to verify_refname_available_dir() for this check.
1603 *
1604 * If mustexist is not set and the reference is not found or is
1605 * broken, lock the reference anyway but clear sha1.
1606 *
1607 * Return 0 on success. On failure, write an error message to err and
1608 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1609 *
1610 * Implementation note: This function is basically
1611 *
1612 * lock reference
1613 * read_raw_ref()
1614 *
1615 * but it includes a lot more code to
1616 * - Deal with possible races with other processes
1617 * - Avoid calling verify_refname_available_dir() when it can be
1618 * avoided, namely if we were successfully able to read the ref
1619 * - Generate informative error messages in the case of failure
1620 */
1621 static int lock_raw_ref(const char *refname, int mustexist,
1622 const struct string_list *extras,
1623 const struct string_list *skip,
1624 struct ref_lock **lock_p,
1625 struct strbuf *referent,
1626 unsigned int *type,
1627 struct strbuf *err)
1628 {
1629 struct ref_lock *lock;
1630 struct strbuf ref_file = STRBUF_INIT;
1631 int attempts_remaining = 3;
1632 int ret = TRANSACTION_GENERIC_ERROR;
1633
1634 assert(err);
1635 *type = 0;
1636
1637 /* First lock the file so it can't change out from under us. */
1638
1639 *lock_p = lock = xcalloc(1, sizeof(*lock));
1640
1641 lock->ref_name = xstrdup(refname);
1642 strbuf_git_path(&ref_file, "%s", refname);
1643
1644 retry:
1645 switch (safe_create_leading_directories(ref_file.buf)) {
1646 case SCLD_OK:
1647 break; /* success */
1648 case SCLD_EXISTS:
1649 /*
1650 * Suppose refname is "refs/foo/bar". We just failed
1651 * to create the containing directory, "refs/foo",
1652 * because there was a non-directory in the way. This
1653 * indicates a D/F conflict, probably because of
1654 * another reference such as "refs/foo". There is no
1655 * reason to expect this error to be transitory.
1656 */
1657 if (verify_refname_available(refname, extras, skip, err)) {
1658 if (mustexist) {
1659 /*
1660 * To the user the relevant error is
1661 * that the "mustexist" reference is
1662 * missing:
1663 */
1664 strbuf_reset(err);
1665 strbuf_addf(err, "unable to resolve reference '%s'",
1666 refname);
1667 } else {
1668 /*
1669 * The error message set by
1670 * verify_refname_available_dir() is OK.
1671 */
1672 ret = TRANSACTION_NAME_CONFLICT;
1673 }
1674 } else {
1675 /*
1676 * The file that is in the way isn't a loose
1677 * reference. Report it as a low-level
1678 * failure.
1679 */
1680 strbuf_addf(err, "unable to create lock file %s.lock; "
1681 "non-directory in the way",
1682 ref_file.buf);
1683 }
1684 goto error_return;
1685 case SCLD_VANISHED:
1686 /* Maybe another process was tidying up. Try again. */
1687 if (--attempts_remaining > 0)
1688 goto retry;
1689 /* fall through */
1690 default:
1691 strbuf_addf(err, "unable to create directory for %s",
1692 ref_file.buf);
1693 goto error_return;
1694 }
1695
1696 if (!lock->lk)
1697 lock->lk = xcalloc(1, sizeof(struct lock_file));
1698
1699 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1700 if (errno == ENOENT && --attempts_remaining > 0) {
1701 /*
1702 * Maybe somebody just deleted one of the
1703 * directories leading to ref_file. Try
1704 * again:
1705 */
1706 goto retry;
1707 } else {
1708 unable_to_lock_message(ref_file.buf, errno, err);
1709 goto error_return;
1710 }
1711 }
1712
1713 /*
1714 * Now we hold the lock and can read the reference without
1715 * fear that its value will change.
1716 */
1717
1718 if (read_raw_ref(refname, lock->old_oid.hash, referent, type)) {
1719 if (errno == ENOENT) {
1720 if (mustexist) {
1721 /* Garden variety missing reference. */
1722 strbuf_addf(err, "unable to resolve reference '%s'",
1723 refname);
1724 goto error_return;
1725 } else {
1726 /*
1727 * Reference is missing, but that's OK. We
1728 * know that there is not a conflict with
1729 * another loose reference because
1730 * (supposing that we are trying to lock
1731 * reference "refs/foo/bar"):
1732 *
1733 * - We were successfully able to create
1734 * the lockfile refs/foo/bar.lock, so we
1735 * know there cannot be a loose reference
1736 * named "refs/foo".
1737 *
1738 * - We got ENOENT and not EISDIR, so we
1739 * know that there cannot be a loose
1740 * reference named "refs/foo/bar/baz".
1741 */
1742 }
1743 } else if (errno == EISDIR) {
1744 /*
1745 * There is a directory in the way. It might have
1746 * contained references that have been deleted. If
1747 * we don't require that the reference already
1748 * exists, try to remove the directory so that it
1749 * doesn't cause trouble when we want to rename the
1750 * lockfile into place later.
1751 */
1752 if (mustexist) {
1753 /* Garden variety missing reference. */
1754 strbuf_addf(err, "unable to resolve reference '%s'",
1755 refname);
1756 goto error_return;
1757 } else if (remove_dir_recursively(&ref_file,
1758 REMOVE_DIR_EMPTY_ONLY)) {
1759 if (verify_refname_available_dir(
1760 refname, extras, skip,
1761 get_loose_refs(&ref_cache),
1762 err)) {
1763 /*
1764 * The error message set by
1765 * verify_refname_available() is OK.
1766 */
1767 ret = TRANSACTION_NAME_CONFLICT;
1768 goto error_return;
1769 } else {
1770 /*
1771 * We can't delete the directory,
1772 * but we also don't know of any
1773 * references that it should
1774 * contain.
1775 */
1776 strbuf_addf(err, "there is a non-empty directory '%s' "
1777 "blocking reference '%s'",
1778 ref_file.buf, refname);
1779 goto error_return;
1780 }
1781 }
1782 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1783 strbuf_addf(err, "unable to resolve reference '%s': "
1784 "reference broken", refname);
1785 goto error_return;
1786 } else {
1787 strbuf_addf(err, "unable to resolve reference '%s': %s",
1788 refname, strerror(errno));
1789 goto error_return;
1790 }
1791
1792 /*
1793 * If the ref did not exist and we are creating it,
1794 * make sure there is no existing packed ref whose
1795 * name begins with our refname, nor a packed ref
1796 * whose name is a proper prefix of our refname.
1797 */
1798 if (verify_refname_available_dir(
1799 refname, extras, skip,
1800 get_packed_refs(&ref_cache),
1801 err)) {
1802 goto error_return;
1803 }
1804 }
1805
1806 ret = 0;
1807 goto out;
1808
1809 error_return:
1810 unlock_ref(lock);
1811 *lock_p = NULL;
1812
1813 out:
1814 strbuf_release(&ref_file);
1815 return ret;
1816 }
1817
1818 /*
1819 * Peel the entry (if possible) and return its new peel_status. If
1820 * repeel is true, re-peel the entry even if there is an old peeled
1821 * value that is already stored in it.
1822 *
1823 * It is OK to call this function with a packed reference entry that
1824 * might be stale and might even refer to an object that has since
1825 * been garbage-collected. In such a case, if the entry has
1826 * REF_KNOWS_PEELED then leave the status unchanged and return
1827 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1828 */
1829 static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1830 {
1831 enum peel_status status;
1832
1833 if (entry->flag & REF_KNOWS_PEELED) {
1834 if (repeel) {
1835 entry->flag &= ~REF_KNOWS_PEELED;
1836 oidclr(&entry->u.value.peeled);
1837 } else {
1838 return is_null_oid(&entry->u.value.peeled) ?
1839 PEEL_NON_TAG : PEEL_PEELED;
1840 }
1841 }
1842 if (entry->flag & REF_ISBROKEN)
1843 return PEEL_BROKEN;
1844 if (entry->flag & REF_ISSYMREF)
1845 return PEEL_IS_SYMREF;
1846
1847 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1848 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1849 entry->flag |= REF_KNOWS_PEELED;
1850 return status;
1851 }
1852
1853 int peel_ref(const char *refname, unsigned char *sha1)
1854 {
1855 int flag;
1856 unsigned char base[20];
1857
1858 if (current_ref_iter && current_ref_iter->refname == refname) {
1859 struct object_id peeled;
1860
1861 if (ref_iterator_peel(current_ref_iter, &peeled))
1862 return -1;
1863 hashcpy(sha1, peeled.hash);
1864 return 0;
1865 }
1866
1867 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1868 return -1;
1869
1870 /*
1871 * If the reference is packed, read its ref_entry from the
1872 * cache in the hope that we already know its peeled value.
1873 * We only try this optimization on packed references because
1874 * (a) forcing the filling of the loose reference cache could
1875 * be expensive and (b) loose references anyway usually do not
1876 * have REF_KNOWS_PEELED.
1877 */
1878 if (flag & REF_ISPACKED) {
1879 struct ref_entry *r = get_packed_ref(refname);
1880 if (r) {
1881 if (peel_entry(r, 0))
1882 return -1;
1883 hashcpy(sha1, r->u.value.peeled.hash);
1884 return 0;
1885 }
1886 }
1887
1888 return peel_object(base, sha1);
1889 }
1890
1891 struct files_ref_iterator {
1892 struct ref_iterator base;
1893
1894 struct packed_ref_cache *packed_ref_cache;
1895 struct ref_iterator *iter0;
1896 unsigned int flags;
1897 };
1898
1899 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
1900 {
1901 struct files_ref_iterator *iter =
1902 (struct files_ref_iterator *)ref_iterator;
1903 int ok;
1904
1905 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
1906 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
1907 !ref_resolves_to_object(iter->iter0->refname,
1908 iter->iter0->oid,
1909 iter->iter0->flags))
1910 continue;
1911
1912 iter->base.refname = iter->iter0->refname;
1913 iter->base.oid = iter->iter0->oid;
1914 iter->base.flags = iter->iter0->flags;
1915 return ITER_OK;
1916 }
1917
1918 iter->iter0 = NULL;
1919 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
1920 ok = ITER_ERROR;
1921
1922 return ok;
1923 }
1924
1925 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
1926 struct object_id *peeled)
1927 {
1928 struct files_ref_iterator *iter =
1929 (struct files_ref_iterator *)ref_iterator;
1930
1931 return ref_iterator_peel(iter->iter0, peeled);
1932 }
1933
1934 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
1935 {
1936 struct files_ref_iterator *iter =
1937 (struct files_ref_iterator *)ref_iterator;
1938 int ok = ITER_DONE;
1939
1940 if (iter->iter0)
1941 ok = ref_iterator_abort(iter->iter0);
1942
1943 release_packed_ref_cache(iter->packed_ref_cache);
1944 base_ref_iterator_free(ref_iterator);
1945 return ok;
1946 }
1947
1948 static struct ref_iterator_vtable files_ref_iterator_vtable = {
1949 files_ref_iterator_advance,
1950 files_ref_iterator_peel,
1951 files_ref_iterator_abort
1952 };
1953
1954 struct ref_iterator *files_ref_iterator_begin(
1955 const char *submodule,
1956 const char *prefix, unsigned int flags)
1957 {
1958 struct ref_cache *refs = get_ref_cache(submodule);
1959 struct ref_dir *loose_dir, *packed_dir;
1960 struct ref_iterator *loose_iter, *packed_iter;
1961 struct files_ref_iterator *iter;
1962 struct ref_iterator *ref_iterator;
1963
1964 if (!refs)
1965 return empty_ref_iterator_begin();
1966
1967 if (ref_paranoia < 0)
1968 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1969 if (ref_paranoia)
1970 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1971
1972 iter = xcalloc(1, sizeof(*iter));
1973 ref_iterator = &iter->base;
1974 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
1975
1976 /*
1977 * We must make sure that all loose refs are read before
1978 * accessing the packed-refs file; this avoids a race
1979 * condition if loose refs are migrated to the packed-refs
1980 * file by a simultaneous process, but our in-memory view is
1981 * from before the migration. We ensure this as follows:
1982 * First, we call prime_ref_dir(), which pre-reads the loose
1983 * references for the subtree into the cache. (If they've
1984 * already been read, that's OK; we only need to guarantee
1985 * that they're read before the packed refs, not *how much*
1986 * before.) After that, we call get_packed_ref_cache(), which
1987 * internally checks whether the packed-ref cache is up to
1988 * date with what is on disk, and re-reads it if not.
1989 */
1990
1991 loose_dir = get_loose_refs(refs);
1992
1993 if (prefix && *prefix)
1994 loose_dir = find_containing_dir(loose_dir, prefix, 0);
1995
1996 if (loose_dir) {
1997 prime_ref_dir(loose_dir);
1998 loose_iter = cache_ref_iterator_begin(loose_dir);
1999 } else {
2000 /* There's nothing to iterate over. */
2001 loose_iter = empty_ref_iterator_begin();
2002 }
2003
2004 iter->packed_ref_cache = get_packed_ref_cache(refs);
2005 acquire_packed_ref_cache(iter->packed_ref_cache);
2006 packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
2007
2008 if (prefix && *prefix)
2009 packed_dir = find_containing_dir(packed_dir, prefix, 0);
2010
2011 if (packed_dir) {
2012 packed_iter = cache_ref_iterator_begin(packed_dir);
2013 } else {
2014 /* There's nothing to iterate over. */
2015 packed_iter = empty_ref_iterator_begin();
2016 }
2017
2018 iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
2019 iter->flags = flags;
2020
2021 return ref_iterator;
2022 }
2023
2024 /*
2025 * Verify that the reference locked by lock has the value old_sha1.
2026 * Fail if the reference doesn't exist and mustexist is set. Return 0
2027 * on success. On error, write an error message to err, set errno, and
2028 * return a negative value.
2029 */
2030 static int verify_lock(struct ref_lock *lock,
2031 const unsigned char *old_sha1, int mustexist,
2032 struct strbuf *err)
2033 {
2034 assert(err);
2035
2036 if (read_ref_full(lock->ref_name,
2037 mustexist ? RESOLVE_REF_READING : 0,
2038 lock->old_oid.hash, NULL)) {
2039 if (old_sha1) {
2040 int save_errno = errno;
2041 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
2042 errno = save_errno;
2043 return -1;
2044 } else {
2045 oidclr(&lock->old_oid);
2046 return 0;
2047 }
2048 }
2049 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
2050 strbuf_addf(err, "ref '%s' is at %s but expected %s",
2051 lock->ref_name,
2052 oid_to_hex(&lock->old_oid),
2053 sha1_to_hex(old_sha1));
2054 errno = EBUSY;
2055 return -1;
2056 }
2057 return 0;
2058 }
2059
2060 static int remove_empty_directories(struct strbuf *path)
2061 {
2062 /*
2063 * we want to create a file but there is a directory there;
2064 * if that is an empty directory (or a directory that contains
2065 * only empty directories), remove them.
2066 */
2067 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
2068 }
2069
2070 /*
2071 * Locks a ref returning the lock on success and NULL on failure.
2072 * On failure errno is set to something meaningful.
2073 */
2074 static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2075 const unsigned char *old_sha1,
2076 const struct string_list *extras,
2077 const struct string_list *skip,
2078 unsigned int flags, int *type,
2079 struct strbuf *err)
2080 {
2081 struct strbuf ref_file = STRBUF_INIT;
2082 struct ref_lock *lock;
2083 int last_errno = 0;
2084 int lflags = LOCK_NO_DEREF;
2085 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2086 int resolve_flags = RESOLVE_REF_NO_RECURSE;
2087 int attempts_remaining = 3;
2088 int resolved;
2089
2090 assert(err);
2091
2092 lock = xcalloc(1, sizeof(struct ref_lock));
2093
2094 if (mustexist)
2095 resolve_flags |= RESOLVE_REF_READING;
2096 if (flags & REF_DELETING)
2097 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
2098
2099 strbuf_git_path(&ref_file, "%s", refname);
2100 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2101 lock->old_oid.hash, type);
2102 if (!resolved && errno == EISDIR) {
2103 /*
2104 * we are trying to lock foo but we used to
2105 * have foo/bar which now does not exist;
2106 * it is normal for the empty directory 'foo'
2107 * to remain.
2108 */
2109 if (remove_empty_directories(&ref_file)) {
2110 last_errno = errno;
2111 if (!verify_refname_available_dir(refname, extras, skip,
2112 get_loose_refs(&ref_cache), err))
2113 strbuf_addf(err, "there are still refs under '%s'",
2114 refname);
2115 goto error_return;
2116 }
2117 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2118 lock->old_oid.hash, type);
2119 }
2120 if (!resolved) {
2121 last_errno = errno;
2122 if (last_errno != ENOTDIR ||
2123 !verify_refname_available_dir(refname, extras, skip,
2124 get_loose_refs(&ref_cache), err))
2125 strbuf_addf(err, "unable to resolve reference '%s': %s",
2126 refname, strerror(last_errno));
2127
2128 goto error_return;
2129 }
2130
2131 /*
2132 * If the ref did not exist and we are creating it, make sure
2133 * there is no existing packed ref whose name begins with our
2134 * refname, nor a packed ref whose name is a proper prefix of
2135 * our refname.
2136 */
2137 if (is_null_oid(&lock->old_oid) &&
2138 verify_refname_available_dir(refname, extras, skip,
2139 get_packed_refs(&ref_cache), err)) {
2140 last_errno = ENOTDIR;
2141 goto error_return;
2142 }
2143
2144 lock->lk = xcalloc(1, sizeof(struct lock_file));
2145
2146 lock->ref_name = xstrdup(refname);
2147
2148 retry:
2149 switch (safe_create_leading_directories_const(ref_file.buf)) {
2150 case SCLD_OK:
2151 break; /* success */
2152 case SCLD_VANISHED:
2153 if (--attempts_remaining > 0)
2154 goto retry;
2155 /* fall through */
2156 default:
2157 last_errno = errno;
2158 strbuf_addf(err, "unable to create directory for '%s'",
2159 ref_file.buf);
2160 goto error_return;
2161 }
2162
2163 if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
2164 last_errno = errno;
2165 if (errno == ENOENT && --attempts_remaining > 0)
2166 /*
2167 * Maybe somebody just deleted one of the
2168 * directories leading to ref_file. Try
2169 * again:
2170 */
2171 goto retry;
2172 else {
2173 unable_to_lock_message(ref_file.buf, errno, err);
2174 goto error_return;
2175 }
2176 }
2177 if (verify_lock(lock, old_sha1, mustexist, err)) {
2178 last_errno = errno;
2179 goto error_return;
2180 }
2181 goto out;
2182
2183 error_return:
2184 unlock_ref(lock);
2185 lock = NULL;
2186
2187 out:
2188 strbuf_release(&ref_file);
2189 errno = last_errno;
2190 return lock;
2191 }
2192
2193 /*
2194 * Write an entry to the packed-refs file for the specified refname.
2195 * If peeled is non-NULL, write it as the entry's peeled value.
2196 */
2197 static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2198 unsigned char *peeled)
2199 {
2200 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2201 if (peeled)
2202 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2203 }
2204
2205 /*
2206 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2207 */
2208 static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2209 {
2210 enum peel_status peel_status = peel_entry(entry, 0);
2211
2212 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2213 error("internal error: %s is not a valid packed reference!",
2214 entry->name);
2215 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2216 peel_status == PEEL_PEELED ?
2217 entry->u.value.peeled.hash : NULL);
2218 return 0;
2219 }
2220
2221 /*
2222 * Lock the packed-refs file for writing. Flags is passed to
2223 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2224 * errno appropriately and return a nonzero value.
2225 */
2226 static int lock_packed_refs(int flags)
2227 {
2228 static int timeout_configured = 0;
2229 static int timeout_value = 1000;
2230
2231 struct packed_ref_cache *packed_ref_cache;
2232
2233 if (!timeout_configured) {
2234 git_config_get_int("core.packedrefstimeout", &timeout_value);
2235 timeout_configured = 1;
2236 }
2237
2238 if (hold_lock_file_for_update_timeout(
2239 &packlock, git_path("packed-refs"),
2240 flags, timeout_value) < 0)
2241 return -1;
2242 /*
2243 * Get the current packed-refs while holding the lock. If the
2244 * packed-refs file has been modified since we last read it,
2245 * this will automatically invalidate the cache and re-read
2246 * the packed-refs file.
2247 */
2248 packed_ref_cache = get_packed_ref_cache(&ref_cache);
2249 packed_ref_cache->lock = &packlock;
2250 /* Increment the reference count to prevent it from being freed: */
2251 acquire_packed_ref_cache(packed_ref_cache);
2252 return 0;
2253 }
2254
2255 /*
2256 * Write the current version of the packed refs cache from memory to
2257 * disk. The packed-refs file must already be locked for writing (see
2258 * lock_packed_refs()). Return zero on success. On errors, set errno
2259 * and return a nonzero value
2260 */
2261 static int commit_packed_refs(void)
2262 {
2263 struct packed_ref_cache *packed_ref_cache =
2264 get_packed_ref_cache(&ref_cache);
2265 int error = 0;
2266 int save_errno = 0;
2267 FILE *out;
2268
2269 if (!packed_ref_cache->lock)
2270 die("internal error: packed-refs not locked");
2271
2272 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2273 if (!out)
2274 die_errno("unable to fdopen packed-refs descriptor");
2275
2276 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2277 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2278 0, write_packed_entry_fn, out);
2279
2280 if (commit_lock_file(packed_ref_cache->lock)) {
2281 save_errno = errno;
2282 error = -1;
2283 }
2284 packed_ref_cache->lock = NULL;
2285 release_packed_ref_cache(packed_ref_cache);
2286 errno = save_errno;
2287 return error;
2288 }
2289
2290 /*
2291 * Rollback the lockfile for the packed-refs file, and discard the
2292 * in-memory packed reference cache. (The packed-refs file will be
2293 * read anew if it is needed again after this function is called.)
2294 */
2295 static void rollback_packed_refs(void)
2296 {
2297 struct packed_ref_cache *packed_ref_cache =
2298 get_packed_ref_cache(&ref_cache);
2299
2300 if (!packed_ref_cache->lock)
2301 die("internal error: packed-refs not locked");
2302 rollback_lock_file(packed_ref_cache->lock);
2303 packed_ref_cache->lock = NULL;
2304 release_packed_ref_cache(packed_ref_cache);
2305 clear_packed_ref_cache(&ref_cache);
2306 }
2307
2308 struct ref_to_prune {
2309 struct ref_to_prune *next;
2310 unsigned char sha1[20];
2311 char name[FLEX_ARRAY];
2312 };
2313
2314 struct pack_refs_cb_data {
2315 unsigned int flags;
2316 struct ref_dir *packed_refs;
2317 struct ref_to_prune *ref_to_prune;
2318 };
2319
2320 /*
2321 * An each_ref_entry_fn that is run over loose references only. If
2322 * the loose reference can be packed, add an entry in the packed ref
2323 * cache. If the reference should be pruned, also add it to
2324 * ref_to_prune in the pack_refs_cb_data.
2325 */
2326 static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2327 {
2328 struct pack_refs_cb_data *cb = cb_data;
2329 enum peel_status peel_status;
2330 struct ref_entry *packed_entry;
2331 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2332
2333 /* Do not pack per-worktree refs: */
2334 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2335 return 0;
2336
2337 /* ALWAYS pack tags */
2338 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2339 return 0;
2340
2341 /* Do not pack symbolic or broken refs: */
2342 if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
2343 return 0;
2344
2345 /* Add a packed ref cache entry equivalent to the loose entry. */
2346 peel_status = peel_entry(entry, 1);
2347 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2348 die("internal error peeling reference %s (%s)",
2349 entry->name, oid_to_hex(&entry->u.value.oid));
2350 packed_entry = find_ref(cb->packed_refs, entry->name);
2351 if (packed_entry) {
2352 /* Overwrite existing packed entry with info from loose entry */
2353 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2354 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2355 } else {
2356 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2357 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2358 add_ref(cb->packed_refs, packed_entry);
2359 }
2360 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2361
2362 /* Schedule the loose reference for pruning if requested. */
2363 if ((cb->flags & PACK_REFS_PRUNE)) {
2364 struct ref_to_prune *n;
2365 FLEX_ALLOC_STR(n, name, entry->name);
2366 hashcpy(n->sha1, entry->u.value.oid.hash);
2367 n->next = cb->ref_to_prune;
2368 cb->ref_to_prune = n;
2369 }
2370 return 0;
2371 }
2372
2373 /*
2374 * Remove empty parents, but spare refs/ and immediate subdirs.
2375 * Note: munges *name.
2376 */
2377 static void try_remove_empty_parents(char *name)
2378 {
2379 char *p, *q;
2380 int i;
2381 p = name;
2382 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2383 while (*p && *p != '/')
2384 p++;
2385 /* tolerate duplicate slashes; see check_refname_format() */
2386 while (*p == '/')
2387 p++;
2388 }
2389 for (q = p; *q; q++)
2390 ;
2391 while (1) {
2392 while (q > p && *q != '/')
2393 q--;
2394 while (q > p && *(q-1) == '/')
2395 q--;
2396 if (q == p)
2397 break;
2398 *q = '\0';
2399 if (rmdir(git_path("%s", name)))
2400 break;
2401 }
2402 }
2403
2404 /* make sure nobody touched the ref, and unlink */
2405 static void prune_ref(struct ref_to_prune *r)
2406 {
2407 struct ref_transaction *transaction;
2408 struct strbuf err = STRBUF_INIT;
2409
2410 if (check_refname_format(r->name, 0))
2411 return;
2412
2413 transaction = ref_transaction_begin(&err);
2414 if (!transaction ||
2415 ref_transaction_delete(transaction, r->name, r->sha1,
2416 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
2417 ref_transaction_commit(transaction, &err)) {
2418 ref_transaction_free(transaction);
2419 error("%s", err.buf);
2420 strbuf_release(&err);
2421 return;
2422 }
2423 ref_transaction_free(transaction);
2424 strbuf_release(&err);
2425 try_remove_empty_parents(r->name);
2426 }
2427
2428 static void prune_refs(struct ref_to_prune *r)
2429 {
2430 while (r) {
2431 prune_ref(r);
2432 r = r->next;
2433 }
2434 }
2435
2436 int pack_refs(unsigned int flags)
2437 {
2438 struct pack_refs_cb_data cbdata;
2439
2440 memset(&cbdata, 0, sizeof(cbdata));
2441 cbdata.flags = flags;
2442
2443 lock_packed_refs(LOCK_DIE_ON_ERROR);
2444 cbdata.packed_refs = get_packed_refs(&ref_cache);
2445
2446 do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2447 pack_if_possible_fn, &cbdata);
2448
2449 if (commit_packed_refs())
2450 die_errno("unable to overwrite old ref-pack file");
2451
2452 prune_refs(cbdata.ref_to_prune);
2453 return 0;
2454 }
2455
2456 /*
2457 * Rewrite the packed-refs file, omitting any refs listed in
2458 * 'refnames'. On error, leave packed-refs unchanged, write an error
2459 * message to 'err', and return a nonzero value.
2460 *
2461 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2462 */
2463 static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
2464 {
2465 struct ref_dir *packed;
2466 struct string_list_item *refname;
2467 int ret, needs_repacking = 0, removed = 0;
2468
2469 assert(err);
2470
2471 /* Look for a packed ref */
2472 for_each_string_list_item(refname, refnames) {
2473 if (get_packed_ref(refname->string)) {
2474 needs_repacking = 1;
2475 break;
2476 }
2477 }
2478
2479 /* Avoid locking if we have nothing to do */
2480 if (!needs_repacking)
2481 return 0; /* no refname exists in packed refs */
2482
2483 if (lock_packed_refs(0)) {
2484 unable_to_lock_message(git_path("packed-refs"), errno, err);
2485 return -1;
2486 }
2487 packed = get_packed_refs(&ref_cache);
2488
2489 /* Remove refnames from the cache */
2490 for_each_string_list_item(refname, refnames)
2491 if (remove_entry(packed, refname->string) != -1)
2492 removed = 1;
2493 if (!removed) {
2494 /*
2495 * All packed entries disappeared while we were
2496 * acquiring the lock.
2497 */
2498 rollback_packed_refs();
2499 return 0;
2500 }
2501
2502 /* Write what remains */
2503 ret = commit_packed_refs();
2504 if (ret)
2505 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2506 strerror(errno));
2507 return ret;
2508 }
2509
2510 static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2511 {
2512 assert(err);
2513
2514 if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2515 /*
2516 * loose. The loose file name is the same as the
2517 * lockfile name, minus ".lock":
2518 */
2519 char *loose_filename = get_locked_file_path(lock->lk);
2520 int res = unlink_or_msg(loose_filename, err);
2521 free(loose_filename);
2522 if (res)
2523 return 1;
2524 }
2525 return 0;
2526 }
2527
2528 int delete_refs(struct string_list *refnames, unsigned int flags)
2529 {
2530 struct strbuf err = STRBUF_INIT;
2531 int i, result = 0;
2532
2533 if (!refnames->nr)
2534 return 0;
2535
2536 result = repack_without_refs(refnames, &err);
2537 if (result) {
2538 /*
2539 * If we failed to rewrite the packed-refs file, then
2540 * it is unsafe to try to remove loose refs, because
2541 * doing so might expose an obsolete packed value for
2542 * a reference that might even point at an object that
2543 * has been garbage collected.
2544 */
2545 if (refnames->nr == 1)
2546 error(_("could not delete reference %s: %s"),
2547 refnames->items[0].string, err.buf);
2548 else
2549 error(_("could not delete references: %s"), err.buf);
2550
2551 goto out;
2552 }
2553
2554 for (i = 0; i < refnames->nr; i++) {
2555 const char *refname = refnames->items[i].string;
2556
2557 if (delete_ref(refname, NULL, flags))
2558 result |= error(_("could not remove reference %s"), refname);
2559 }
2560
2561 out:
2562 strbuf_release(&err);
2563 return result;
2564 }
2565
2566 /*
2567 * People using contrib's git-new-workdir have .git/logs/refs ->
2568 * /some/other/path/.git/logs/refs, and that may live on another device.
2569 *
2570 * IOW, to avoid cross device rename errors, the temporary renamed log must
2571 * live into logs/refs.
2572 */
2573 #define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
2574
2575 static int rename_tmp_log(const char *newrefname)
2576 {
2577 int attempts_remaining = 4;
2578 struct strbuf path = STRBUF_INIT;
2579 int ret = -1;
2580
2581 retry:
2582 strbuf_reset(&path);
2583 strbuf_git_path(&path, "logs/%s", newrefname);
2584 switch (safe_create_leading_directories_const(path.buf)) {
2585 case SCLD_OK:
2586 break; /* success */
2587 case SCLD_VANISHED:
2588 if (--attempts_remaining > 0)
2589 goto retry;
2590 /* fall through */
2591 default:
2592 error("unable to create directory for %s", newrefname);
2593 goto out;
2594 }
2595
2596 if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
2597 if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2598 /*
2599 * rename(a, b) when b is an existing
2600 * directory ought to result in ISDIR, but
2601 * Solaris 5.8 gives ENOTDIR. Sheesh.
2602 */
2603 if (remove_empty_directories(&path)) {
2604 error("Directory not empty: logs/%s", newrefname);
2605 goto out;
2606 }
2607 goto retry;
2608 } else if (errno == ENOENT && --attempts_remaining > 0) {
2609 /*
2610 * Maybe another process just deleted one of
2611 * the directories in the path to newrefname.
2612 * Try again from the beginning.
2613 */
2614 goto retry;
2615 } else {
2616 error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2617 newrefname, strerror(errno));
2618 goto out;
2619 }
2620 }
2621 ret = 0;
2622 out:
2623 strbuf_release(&path);
2624 return ret;
2625 }
2626
2627 int verify_refname_available(const char *newname,
2628 const struct string_list *extras,
2629 const struct string_list *skip,
2630 struct strbuf *err)
2631 {
2632 struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
2633 struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
2634
2635 if (verify_refname_available_dir(newname, extras, skip,
2636 packed_refs, err) ||
2637 verify_refname_available_dir(newname, extras, skip,
2638 loose_refs, err))
2639 return -1;
2640
2641 return 0;
2642 }
2643
2644 static int write_ref_to_lockfile(struct ref_lock *lock,
2645 const unsigned char *sha1, struct strbuf *err);
2646 static int commit_ref_update(struct ref_lock *lock,
2647 const unsigned char *sha1, const char *logmsg,
2648 struct strbuf *err);
2649
2650 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2651 {
2652 unsigned char sha1[20], orig_sha1[20];
2653 int flag = 0, logmoved = 0;
2654 struct ref_lock *lock;
2655 struct stat loginfo;
2656 int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
2657 struct strbuf err = STRBUF_INIT;
2658
2659 if (log && S_ISLNK(loginfo.st_mode))
2660 return error("reflog for %s is a symlink", oldrefname);
2661
2662 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2663 orig_sha1, &flag))
2664 return error("refname %s not found", oldrefname);
2665
2666 if (flag & REF_ISSYMREF)
2667 return error("refname %s is a symbolic ref, renaming it is not supported",
2668 oldrefname);
2669 if (!rename_ref_available(oldrefname, newrefname))
2670 return 1;
2671
2672 if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2673 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2674 oldrefname, strerror(errno));
2675
2676 if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2677 error("unable to delete old %s", oldrefname);
2678 goto rollback;
2679 }
2680
2681 /*
2682 * Since we are doing a shallow lookup, sha1 is not the
2683 * correct value to pass to delete_ref as old_sha1. But that
2684 * doesn't matter, because an old_sha1 check wouldn't add to
2685 * the safety anyway; we want to delete the reference whatever
2686 * its current value.
2687 */
2688 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2689 sha1, NULL) &&
2690 delete_ref(newrefname, NULL, REF_NODEREF)) {
2691 if (errno==EISDIR) {
2692 struct strbuf path = STRBUF_INIT;
2693 int result;
2694
2695 strbuf_git_path(&path, "%s", newrefname);
2696 result = remove_empty_directories(&path);
2697 strbuf_release(&path);
2698
2699 if (result) {
2700 error("Directory not empty: %s", newrefname);
2701 goto rollback;
2702 }
2703 } else {
2704 error("unable to delete existing %s", newrefname);
2705 goto rollback;
2706 }
2707 }
2708
2709 if (log && rename_tmp_log(newrefname))
2710 goto rollback;
2711
2712 logmoved = log;
2713
2714 lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, REF_NODEREF,
2715 NULL, &err);
2716 if (!lock) {
2717 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2718 strbuf_release(&err);
2719 goto rollback;
2720 }
2721 hashcpy(lock->old_oid.hash, orig_sha1);
2722
2723 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2724 commit_ref_update(lock, orig_sha1, logmsg, &err)) {
2725 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2726 strbuf_release(&err);
2727 goto rollback;
2728 }
2729
2730 return 0;
2731
2732 rollback:
2733 lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, REF_NODEREF,
2734 NULL, &err);
2735 if (!lock) {
2736 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2737 strbuf_release(&err);
2738 goto rollbacklog;
2739 }
2740
2741 flag = log_all_ref_updates;
2742 log_all_ref_updates = 0;
2743 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2744 commit_ref_update(lock, orig_sha1, NULL, &err)) {
2745 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2746 strbuf_release(&err);
2747 }
2748 log_all_ref_updates = flag;
2749
2750 rollbacklog:
2751 if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2752 error("unable to restore logfile %s from %s: %s",
2753 oldrefname, newrefname, strerror(errno));
2754 if (!logmoved && log &&
2755 rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2756 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2757 oldrefname, strerror(errno));
2758
2759 return 1;
2760 }
2761
2762 static int close_ref(struct ref_lock *lock)
2763 {
2764 if (close_lock_file(lock->lk))
2765 return -1;
2766 return 0;
2767 }
2768
2769 static int commit_ref(struct ref_lock *lock)
2770 {
2771 char *path = get_locked_file_path(lock->lk);
2772 struct stat st;
2773
2774 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2775 /*
2776 * There is a directory at the path we want to rename
2777 * the lockfile to. Hopefully it is empty; try to
2778 * delete it.
2779 */
2780 size_t len = strlen(path);
2781 struct strbuf sb_path = STRBUF_INIT;
2782
2783 strbuf_attach(&sb_path, path, len, len);
2784
2785 /*
2786 * If this fails, commit_lock_file() will also fail
2787 * and will report the problem.
2788 */
2789 remove_empty_directories(&sb_path);
2790 strbuf_release(&sb_path);
2791 } else {
2792 free(path);
2793 }
2794
2795 if (commit_lock_file(lock->lk))
2796 return -1;
2797 return 0;
2798 }
2799
2800 /*
2801 * Create a reflog for a ref. If force_create = 0, the reflog will
2802 * only be created for certain refs (those for which
2803 * should_autocreate_reflog returns non-zero. Otherwise, create it
2804 * regardless of the ref name. Fill in *err and return -1 on failure.
2805 */
2806 static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
2807 {
2808 int logfd, oflags = O_APPEND | O_WRONLY;
2809
2810 strbuf_git_path(logfile, "logs/%s", refname);
2811 if (force_create || should_autocreate_reflog(refname)) {
2812 if (safe_create_leading_directories(logfile->buf) < 0) {
2813 strbuf_addf(err, "unable to create directory for '%s': "
2814 "%s", logfile->buf, strerror(errno));
2815 return -1;
2816 }
2817 oflags |= O_CREAT;
2818 }
2819
2820 logfd = open(logfile->buf, oflags, 0666);
2821 if (logfd < 0) {
2822 if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
2823 return 0;
2824
2825 if (errno == EISDIR) {
2826 if (remove_empty_directories(logfile)) {
2827 strbuf_addf(err, "there are still logs under "
2828 "'%s'", logfile->buf);
2829 return -1;
2830 }
2831 logfd = open(logfile->buf, oflags, 0666);
2832 }
2833
2834 if (logfd < 0) {
2835 strbuf_addf(err, "unable to append to '%s': %s",
2836 logfile->buf, strerror(errno));
2837 return -1;
2838 }
2839 }
2840
2841 adjust_shared_perm(logfile->buf);
2842 close(logfd);
2843 return 0;
2844 }
2845
2846
2847 int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
2848 {
2849 int ret;
2850 struct strbuf sb = STRBUF_INIT;
2851
2852 ret = log_ref_setup(refname, &sb, err, force_create);
2853 strbuf_release(&sb);
2854 return ret;
2855 }
2856
2857 static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2858 const unsigned char *new_sha1,
2859 const char *committer, const char *msg)
2860 {
2861 int msglen, written;
2862 unsigned maxlen, len;
2863 char *logrec;
2864
2865 msglen = msg ? strlen(msg) : 0;
2866 maxlen = strlen(committer) + msglen + 100;
2867 logrec = xmalloc(maxlen);
2868 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2869 sha1_to_hex(old_sha1),
2870 sha1_to_hex(new_sha1),
2871 committer);
2872 if (msglen)
2873 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2874
2875 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2876 free(logrec);
2877 if (written != len)
2878 return -1;
2879
2880 return 0;
2881 }
2882
2883 static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
2884 const unsigned char *new_sha1, const char *msg,
2885 struct strbuf *logfile, int flags,
2886 struct strbuf *err)
2887 {
2888 int logfd, result, oflags = O_APPEND | O_WRONLY;
2889
2890 if (log_all_ref_updates < 0)
2891 log_all_ref_updates = !is_bare_repository();
2892
2893 result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
2894
2895 if (result)
2896 return result;
2897
2898 logfd = open(logfile->buf, oflags);
2899 if (logfd < 0)
2900 return 0;
2901 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2902 git_committer_info(0), msg);
2903 if (result) {
2904 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
2905 strerror(errno));
2906 close(logfd);
2907 return -1;
2908 }
2909 if (close(logfd)) {
2910 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
2911 strerror(errno));
2912 return -1;
2913 }
2914 return 0;
2915 }
2916
2917 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2918 const unsigned char *new_sha1, const char *msg,
2919 int flags, struct strbuf *err)
2920 {
2921 return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
2922 err);
2923 }
2924
2925 int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
2926 const unsigned char *new_sha1, const char *msg,
2927 int flags, struct strbuf *err)
2928 {
2929 struct strbuf sb = STRBUF_INIT;
2930 int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
2931 err);
2932 strbuf_release(&sb);
2933 return ret;
2934 }
2935
2936 /*
2937 * Write sha1 into the open lockfile, then close the lockfile. On
2938 * errors, rollback the lockfile, fill in *err and
2939 * return -1.
2940 */
2941 static int write_ref_to_lockfile(struct ref_lock *lock,
2942 const unsigned char *sha1, struct strbuf *err)
2943 {
2944 static char term = '\n';
2945 struct object *o;
2946 int fd;
2947
2948 o = parse_object(sha1);
2949 if (!o) {
2950 strbuf_addf(err,
2951 "trying to write ref '%s' with nonexistent object %s",
2952 lock->ref_name, sha1_to_hex(sha1));
2953 unlock_ref(lock);
2954 return -1;
2955 }
2956 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2957 strbuf_addf(err,
2958 "trying to write non-commit object %s to branch '%s'",
2959 sha1_to_hex(sha1), lock->ref_name);
2960 unlock_ref(lock);
2961 return -1;
2962 }
2963 fd = get_lock_file_fd(lock->lk);
2964 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
2965 write_in_full(fd, &term, 1) != 1 ||
2966 close_ref(lock) < 0) {
2967 strbuf_addf(err,
2968 "couldn't write '%s'", get_lock_file_path(lock->lk));
2969 unlock_ref(lock);
2970 return -1;
2971 }
2972 return 0;
2973 }
2974
2975 /*
2976 * Commit a change to a loose reference that has already been written
2977 * to the loose reference lockfile. Also update the reflogs if
2978 * necessary, using the specified lockmsg (which can be NULL).
2979 */
2980 static int commit_ref_update(struct ref_lock *lock,
2981 const unsigned char *sha1, const char *logmsg,
2982 struct strbuf *err)
2983 {
2984 clear_loose_ref_cache(&ref_cache);
2985 if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
2986 char *old_msg = strbuf_detach(err, NULL);
2987 strbuf_addf(err, "cannot update the ref '%s': %s",
2988 lock->ref_name, old_msg);
2989 free(old_msg);
2990 unlock_ref(lock);
2991 return -1;
2992 }
2993
2994 if (strcmp(lock->ref_name, "HEAD") != 0) {
2995 /*
2996 * Special hack: If a branch is updated directly and HEAD
2997 * points to it (may happen on the remote side of a push
2998 * for example) then logically the HEAD reflog should be
2999 * updated too.
3000 * A generic solution implies reverse symref information,
3001 * but finding all symrefs pointing to the given branch
3002 * would be rather costly for this rare event (the direct
3003 * update of a branch) to be worth it. So let's cheat and
3004 * check with HEAD only which should cover 99% of all usage
3005 * scenarios (even 100% of the default ones).
3006 */
3007 unsigned char head_sha1[20];
3008 int head_flag;
3009 const char *head_ref;
3010
3011 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
3012 head_sha1, &head_flag);
3013 if (head_ref && (head_flag & REF_ISSYMREF) &&
3014 !strcmp(head_ref, lock->ref_name)) {
3015 struct strbuf log_err = STRBUF_INIT;
3016 if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
3017 logmsg, 0, &log_err)) {
3018 error("%s", log_err.buf);
3019 strbuf_release(&log_err);
3020 }
3021 }
3022 }
3023
3024 if (commit_ref(lock)) {
3025 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3026 unlock_ref(lock);
3027 return -1;
3028 }
3029
3030 unlock_ref(lock);
3031 return 0;
3032 }
3033
3034 static int create_ref_symlink(struct ref_lock *lock, const char *target)
3035 {
3036 int ret = -1;
3037 #ifndef NO_SYMLINK_HEAD
3038 char *ref_path = get_locked_file_path(lock->lk);
3039 unlink(ref_path);
3040 ret = symlink(target, ref_path);
3041 free(ref_path);
3042
3043 if (ret)
3044 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
3045 #endif
3046 return ret;
3047 }
3048
3049 static void update_symref_reflog(struct ref_lock *lock, const char *refname,
3050 const char *target, const char *logmsg)
3051 {
3052 struct strbuf err = STRBUF_INIT;
3053 unsigned char new_sha1[20];
3054 if (logmsg && !read_ref(target, new_sha1) &&
3055 log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
3056 error("%s", err.buf);
3057 strbuf_release(&err);
3058 }
3059 }
3060
3061 static int create_symref_locked(struct ref_lock *lock, const char *refname,
3062 const char *target, const char *logmsg)
3063 {
3064 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
3065 update_symref_reflog(lock, refname, target, logmsg);
3066 return 0;
3067 }
3068
3069 if (!fdopen_lock_file(lock->lk, "w"))
3070 return error("unable to fdopen %s: %s",
3071 lock->lk->tempfile.filename.buf, strerror(errno));
3072
3073 update_symref_reflog(lock, refname, target, logmsg);
3074
3075 /* no error check; commit_ref will check ferror */
3076 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
3077 if (commit_ref(lock) < 0)
3078 return error("unable to write symref for %s: %s", refname,
3079 strerror(errno));
3080 return 0;
3081 }
3082
3083 int create_symref(const char *refname, const char *target, const char *logmsg)
3084 {
3085 struct strbuf err = STRBUF_INIT;
3086 struct ref_lock *lock;
3087 int ret;
3088
3089 lock = lock_ref_sha1_basic(refname, NULL, NULL, NULL, REF_NODEREF, NULL,
3090 &err);
3091 if (!lock) {
3092 error("%s", err.buf);
3093 strbuf_release(&err);
3094 return -1;
3095 }
3096
3097 ret = create_symref_locked(lock, refname, target, logmsg);
3098 unlock_ref(lock);
3099 return ret;
3100 }
3101
3102 int set_worktree_head_symref(const char *gitdir, const char *target)
3103 {
3104 static struct lock_file head_lock;
3105 struct ref_lock *lock;
3106 struct strbuf head_path = STRBUF_INIT;
3107 const char *head_rel;
3108 int ret;
3109
3110 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3111 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3112 LOCK_NO_DEREF) < 0) {
3113 struct strbuf err = STRBUF_INIT;
3114 unable_to_lock_message(head_path.buf, errno, &err);
3115 error("%s", err.buf);
3116 strbuf_release(&err);
3117 strbuf_release(&head_path);
3118 return -1;
3119 }
3120
3121 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3122 linked trees */
3123 head_rel = remove_leading_path(head_path.buf,
3124 absolute_path(get_git_common_dir()));
3125 /* to make use of create_symref_locked(), initialize ref_lock */
3126 lock = xcalloc(1, sizeof(struct ref_lock));
3127 lock->lk = &head_lock;
3128 lock->ref_name = xstrdup(head_rel);
3129
3130 ret = create_symref_locked(lock, head_rel, target, NULL);
3131
3132 unlock_ref(lock); /* will free lock */
3133 strbuf_release(&head_path);
3134 return ret;
3135 }
3136
3137 int reflog_exists(const char *refname)
3138 {
3139 struct stat st;
3140
3141 return !lstat(git_path("logs/%s", refname), &st) &&
3142 S_ISREG(st.st_mode);
3143 }
3144
3145 int delete_reflog(const char *refname)
3146 {
3147 return remove_path(git_path("logs/%s", refname));
3148 }
3149
3150 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3151 {
3152 unsigned char osha1[20], nsha1[20];
3153 char *email_end, *message;
3154 unsigned long timestamp;
3155 int tz;
3156
3157 /* old SP new SP name <email> SP time TAB msg LF */
3158 if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3159 get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3160 get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3161 !(email_end = strchr(sb->buf + 82, '>')) ||
3162 email_end[1] != ' ' ||
3163 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3164 !message || message[0] != ' ' ||
3165 (message[1] != '+' && message[1] != '-') ||
3166 !isdigit(message[2]) || !isdigit(message[3]) ||
3167 !isdigit(message[4]) || !isdigit(message[5]))
3168 return 0; /* corrupt? */
3169 email_end[1] = '\0';
3170 tz = strtol(message + 1, NULL, 10);
3171 if (message[6] != '\t')
3172 message += 6;
3173 else
3174 message += 7;
3175 return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3176 }
3177
3178 static char *find_beginning_of_line(char *bob, char *scan)
3179 {
3180 while (bob < scan && *(--scan) != '\n')
3181 ; /* keep scanning backwards */
3182 /*
3183 * Return either beginning of the buffer, or LF at the end of
3184 * the previous line.
3185 */
3186 return scan;
3187 }
3188
3189 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3190 {
3191 struct strbuf sb = STRBUF_INIT;
3192 FILE *logfp;
3193 long pos;
3194 int ret = 0, at_tail = 1;
3195
3196 logfp = fopen(git_path("logs/%s", refname), "r");
3197 if (!logfp)
3198 return -1;
3199
3200 /* Jump to the end */
3201 if (fseek(logfp, 0, SEEK_END) < 0)
3202 return error("cannot seek back reflog for %s: %s",
3203 refname, strerror(errno));
3204 pos = ftell(logfp);
3205 while (!ret && 0 < pos) {
3206 int cnt;
3207 size_t nread;
3208 char buf[BUFSIZ];
3209 char *endp, *scanp;
3210
3211 /* Fill next block from the end */
3212 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3213 if (fseek(logfp, pos - cnt, SEEK_SET))
3214 return error("cannot seek back reflog for %s: %s",
3215 refname, strerror(errno));
3216 nread = fread(buf, cnt, 1, logfp);
3217 if (nread != 1)
3218 return error("cannot read %d bytes from reflog for %s: %s",
3219 cnt, refname, strerror(errno));
3220 pos -= cnt;
3221
3222 scanp = endp = buf + cnt;
3223 if (at_tail && scanp[-1] == '\n')
3224 /* Looking at the final LF at the end of the file */
3225 scanp--;
3226 at_tail = 0;
3227
3228 while (buf < scanp) {
3229 /*
3230 * terminating LF of the previous line, or the beginning
3231 * of the buffer.
3232 */
3233 char *bp;
3234
3235 bp = find_beginning_of_line(buf, scanp);
3236
3237 if (*bp == '\n') {
3238 /*
3239 * The newline is the end of the previous line,
3240 * so we know we have complete line starting
3241 * at (bp + 1). Prefix it onto any prior data
3242 * we collected for the line and process it.
3243 */
3244 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3245 scanp = bp;
3246 endp = bp + 1;
3247 ret = show_one_reflog_ent(&sb, fn, cb_data);
3248 strbuf_reset(&sb);
3249 if (ret)
3250 break;
3251 } else if (!pos) {
3252 /*
3253 * We are at the start of the buffer, and the
3254 * start of the file; there is no previous
3255 * line, and we have everything for this one.
3256 * Process it, and we can end the loop.
3257 */
3258 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3259 ret = show_one_reflog_ent(&sb, fn, cb_data);
3260 strbuf_reset(&sb);
3261 break;
3262 }
3263
3264 if (bp == buf) {
3265 /*
3266 * We are at the start of the buffer, and there
3267 * is more file to read backwards. Which means
3268 * we are in the middle of a line. Note that we
3269 * may get here even if *bp was a newline; that
3270 * just means we are at the exact end of the
3271 * previous line, rather than some spot in the
3272 * middle.
3273 *
3274 * Save away what we have to be combined with
3275 * the data from the next read.
3276 */
3277 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3278 break;
3279 }
3280 }
3281
3282 }
3283 if (!ret && sb.len)
3284 die("BUG: reverse reflog parser had leftover data");
3285
3286 fclose(logfp);
3287 strbuf_release(&sb);
3288 return ret;
3289 }
3290
3291 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3292 {
3293 FILE *logfp;
3294 struct strbuf sb = STRBUF_INIT;
3295 int ret = 0;
3296
3297 logfp = fopen(git_path("logs/%s", refname), "r");
3298 if (!logfp)
3299 return -1;
3300
3301 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3302 ret = show_one_reflog_ent(&sb, fn, cb_data);
3303 fclose(logfp);
3304 strbuf_release(&sb);
3305 return ret;
3306 }
3307
3308 struct files_reflog_iterator {
3309 struct ref_iterator base;
3310
3311 struct dir_iterator *dir_iterator;
3312 struct object_id oid;
3313 };
3314
3315 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
3316 {
3317 struct files_reflog_iterator *iter =
3318 (struct files_reflog_iterator *)ref_iterator;
3319 struct dir_iterator *diter = iter->dir_iterator;
3320 int ok;
3321
3322 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
3323 int flags;
3324
3325 if (!S_ISREG(diter->st.st_mode))
3326 continue;
3327 if (diter->basename[0] == '.')
3328 continue;
3329 if (ends_with(diter->basename, ".lock"))
3330 continue;
3331
3332 if (read_ref_full(diter->relative_path, 0,
3333 iter->oid.hash, &flags)) {
3334 error("bad ref for %s", diter->path.buf);
3335 continue;
3336 }
3337
3338 iter->base.refname = diter->relative_path;
3339 iter->base.oid = &iter->oid;
3340 iter->base.flags = flags;
3341 return ITER_OK;
3342 }
3343
3344 iter->dir_iterator = NULL;
3345 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
3346 ok = ITER_ERROR;
3347 return ok;
3348 }
3349
3350 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
3351 struct object_id *peeled)
3352 {
3353 die("BUG: ref_iterator_peel() called for reflog_iterator");
3354 }
3355
3356 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
3357 {
3358 struct files_reflog_iterator *iter =
3359 (struct files_reflog_iterator *)ref_iterator;
3360 int ok = ITER_DONE;
3361
3362 if (iter->dir_iterator)
3363 ok = dir_iterator_abort(iter->dir_iterator);
3364
3365 base_ref_iterator_free(ref_iterator);
3366 return ok;
3367 }
3368
3369 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
3370 files_reflog_iterator_advance,
3371 files_reflog_iterator_peel,
3372 files_reflog_iterator_abort
3373 };
3374
3375 struct ref_iterator *files_reflog_iterator_begin(void)
3376 {
3377 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
3378 struct ref_iterator *ref_iterator = &iter->base;
3379
3380 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
3381 iter->dir_iterator = dir_iterator_begin(git_path("logs"));
3382 return ref_iterator;
3383 }
3384
3385 int for_each_reflog(each_ref_fn fn, void *cb_data)
3386 {
3387 return do_for_each_ref_iterator(files_reflog_iterator_begin(),
3388 fn, cb_data);
3389 }
3390
3391 static int ref_update_reject_duplicates(struct string_list *refnames,
3392 struct strbuf *err)
3393 {
3394 int i, n = refnames->nr;
3395
3396 assert(err);
3397
3398 for (i = 1; i < n; i++)
3399 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3400 strbuf_addf(err,
3401 "multiple updates for ref '%s' not allowed.",
3402 refnames->items[i].string);
3403 return 1;
3404 }
3405 return 0;
3406 }
3407
3408 /*
3409 * If update is a direct update of head_ref (the reference pointed to
3410 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3411 */
3412 static int split_head_update(struct ref_update *update,
3413 struct ref_transaction *transaction,
3414 const char *head_ref,
3415 struct string_list *affected_refnames,
3416 struct strbuf *err)
3417 {
3418 struct string_list_item *item;
3419 struct ref_update *new_update;
3420
3421 if ((update->flags & REF_LOG_ONLY) ||
3422 (update->flags & REF_ISPRUNING) ||
3423 (update->flags & REF_UPDATE_VIA_HEAD))
3424 return 0;
3425
3426 if (strcmp(update->refname, head_ref))
3427 return 0;
3428
3429 /*
3430 * First make sure that HEAD is not already in the
3431 * transaction. This insertion is O(N) in the transaction
3432 * size, but it happens at most once per transaction.
3433 */
3434 item = string_list_insert(affected_refnames, "HEAD");
3435 if (item->util) {
3436 /* An entry already existed */
3437 strbuf_addf(err,
3438 "multiple updates for 'HEAD' (including one "
3439 "via its referent '%s') are not allowed",
3440 update->refname);
3441 return TRANSACTION_NAME_CONFLICT;
3442 }
3443
3444 new_update = ref_transaction_add_update(
3445 transaction, "HEAD",
3446 update->flags | REF_LOG_ONLY | REF_NODEREF,
3447 update->new_sha1, update->old_sha1,
3448 update->msg);
3449
3450 item->util = new_update;
3451
3452 return 0;
3453 }
3454
3455 /*
3456 * update is for a symref that points at referent and doesn't have
3457 * REF_NODEREF set. Split it into two updates:
3458 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3459 * - A new, separate update for the referent reference
3460 * Note that the new update will itself be subject to splitting when
3461 * the iteration gets to it.
3462 */
3463 static int split_symref_update(struct ref_update *update,
3464 const char *referent,
3465 struct ref_transaction *transaction,
3466 struct string_list *affected_refnames,
3467 struct strbuf *err)
3468 {
3469 struct string_list_item *item;
3470 struct ref_update *new_update;
3471 unsigned int new_flags;
3472
3473 /*
3474 * First make sure that referent is not already in the
3475 * transaction. This insertion is O(N) in the transaction
3476 * size, but it happens at most once per symref in a
3477 * transaction.
3478 */
3479 item = string_list_insert(affected_refnames, referent);
3480 if (item->util) {
3481 /* An entry already existed */
3482 strbuf_addf(err,
3483 "multiple updates for '%s' (including one "
3484 "via symref '%s') are not allowed",
3485 referent, update->refname);
3486 return TRANSACTION_NAME_CONFLICT;
3487 }
3488
3489 new_flags = update->flags;
3490 if (!strcmp(update->refname, "HEAD")) {
3491 /*
3492 * Record that the new update came via HEAD, so that
3493 * when we process it, split_head_update() doesn't try
3494 * to add another reflog update for HEAD. Note that
3495 * this bit will be propagated if the new_update
3496 * itself needs to be split.
3497 */
3498 new_flags |= REF_UPDATE_VIA_HEAD;
3499 }
3500
3501 new_update = ref_transaction_add_update(
3502 transaction, referent, new_flags,
3503 update->new_sha1, update->old_sha1,
3504 update->msg);
3505
3506 new_update->parent_update = update;
3507
3508 /*
3509 * Change the symbolic ref update to log only. Also, it
3510 * doesn't need to check its old SHA-1 value, as that will be
3511 * done when new_update is processed.
3512 */
3513 update->flags |= REF_LOG_ONLY | REF_NODEREF;
3514 update->flags &= ~REF_HAVE_OLD;
3515
3516 item->util = new_update;
3517
3518 return 0;
3519 }
3520
3521 /*
3522 * Return the refname under which update was originally requested.
3523 */
3524 static const char *original_update_refname(struct ref_update *update)
3525 {
3526 while (update->parent_update)
3527 update = update->parent_update;
3528
3529 return update->refname;
3530 }
3531
3532 /*
3533 * Check whether the REF_HAVE_OLD and old_oid values stored in update
3534 * are consistent with oid, which is the reference's current value. If
3535 * everything is OK, return 0; otherwise, write an error message to
3536 * err and return -1.
3537 */
3538 static int check_old_oid(struct ref_update *update, struct object_id *oid,
3539 struct strbuf *err)
3540 {
3541 if (!(update->flags & REF_HAVE_OLD) ||
3542 !hashcmp(oid->hash, update->old_sha1))
3543 return 0;
3544
3545 if (is_null_sha1(update->old_sha1))
3546 strbuf_addf(err, "cannot lock ref '%s': "
3547 "reference already exists",
3548 original_update_refname(update));
3549 else if (is_null_oid(oid))
3550 strbuf_addf(err, "cannot lock ref '%s': "
3551 "reference is missing but expected %s",
3552 original_update_refname(update),
3553 sha1_to_hex(update->old_sha1));
3554 else
3555 strbuf_addf(err, "cannot lock ref '%s': "
3556 "is at %s but expected %s",
3557 original_update_refname(update),
3558 oid_to_hex(oid),
3559 sha1_to_hex(update->old_sha1));
3560
3561 return -1;
3562 }
3563
3564 /*
3565 * Prepare for carrying out update:
3566 * - Lock the reference referred to by update.
3567 * - Read the reference under lock.
3568 * - Check that its old SHA-1 value (if specified) is correct, and in
3569 * any case record it in update->lock->old_oid for later use when
3570 * writing the reflog.
3571 * - If it is a symref update without REF_NODEREF, split it up into a
3572 * REF_LOG_ONLY update of the symref and add a separate update for
3573 * the referent to transaction.
3574 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3575 * update of HEAD.
3576 */
3577 static int lock_ref_for_update(struct ref_update *update,
3578 struct ref_transaction *transaction,
3579 const char *head_ref,
3580 struct string_list *affected_refnames,
3581 struct strbuf *err)
3582 {
3583 struct strbuf referent = STRBUF_INIT;
3584 int mustexist = (update->flags & REF_HAVE_OLD) &&
3585 !is_null_sha1(update->old_sha1);
3586 int ret;
3587 struct ref_lock *lock;
3588
3589 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
3590 update->flags |= REF_DELETING;
3591
3592 if (head_ref) {
3593 ret = split_head_update(update, transaction, head_ref,
3594 affected_refnames, err);
3595 if (ret)
3596 return ret;
3597 }
3598
3599 ret = lock_raw_ref(update->refname, mustexist,
3600 affected_refnames, NULL,
3601 &update->lock, &referent,
3602 &update->type, err);
3603
3604 if (ret) {
3605 char *reason;
3606
3607 reason = strbuf_detach(err, NULL);
3608 strbuf_addf(err, "cannot lock ref '%s': %s",
3609 original_update_refname(update), reason);
3610 free(reason);
3611 return ret;
3612 }
3613
3614 lock = update->lock;
3615
3616 if (update->type & REF_ISSYMREF) {
3617 if (update->flags & REF_NODEREF) {
3618 /*
3619 * We won't be reading the referent as part of
3620 * the transaction, so we have to read it here
3621 * to record and possibly check old_sha1:
3622 */
3623 if (read_ref_full(referent.buf, 0,
3624 lock->old_oid.hash, NULL)) {
3625 if (update->flags & REF_HAVE_OLD) {
3626 strbuf_addf(err, "cannot lock ref '%s': "
3627 "error reading reference",
3628 original_update_refname(update));
3629 return -1;
3630 }
3631 } else if (check_old_oid(update, &lock->old_oid, err)) {
3632 return TRANSACTION_GENERIC_ERROR;
3633 }
3634 } else {
3635 /*
3636 * Create a new update for the reference this
3637 * symref is pointing at. Also, we will record
3638 * and verify old_sha1 for this update as part
3639 * of processing the split-off update, so we
3640 * don't have to do it here.
3641 */
3642 ret = split_symref_update(update, referent.buf, transaction,
3643 affected_refnames, err);
3644 if (ret)
3645 return ret;
3646 }
3647 } else {
3648 struct ref_update *parent_update;
3649
3650 if (check_old_oid(update, &lock->old_oid, err))
3651 return TRANSACTION_GENERIC_ERROR;
3652
3653 /*
3654 * If this update is happening indirectly because of a
3655 * symref update, record the old SHA-1 in the parent
3656 * update:
3657 */
3658 for (parent_update = update->parent_update;
3659 parent_update;
3660 parent_update = parent_update->parent_update) {
3661 oidcpy(&parent_update->lock->old_oid, &lock->old_oid);
3662 }
3663 }
3664
3665 if ((update->flags & REF_HAVE_NEW) &&
3666 !(update->flags & REF_DELETING) &&
3667 !(update->flags & REF_LOG_ONLY)) {
3668 if (!(update->type & REF_ISSYMREF) &&
3669 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
3670 /*
3671 * The reference already has the desired
3672 * value, so we don't need to write it.
3673 */
3674 } else if (write_ref_to_lockfile(lock, update->new_sha1,
3675 err)) {
3676 char *write_err = strbuf_detach(err, NULL);
3677
3678 /*
3679 * The lock was freed upon failure of
3680 * write_ref_to_lockfile():
3681 */
3682 update->lock = NULL;
3683 strbuf_addf(err,
3684 "cannot update ref '%s': %s",
3685 update->refname, write_err);
3686 free(write_err);
3687 return TRANSACTION_GENERIC_ERROR;
3688 } else {
3689 update->flags |= REF_NEEDS_COMMIT;
3690 }
3691 }
3692 if (!(update->flags & REF_NEEDS_COMMIT)) {
3693 /*
3694 * We didn't call write_ref_to_lockfile(), so
3695 * the lockfile is still open. Close it to
3696 * free up the file descriptor:
3697 */
3698 if (close_ref(lock)) {
3699 strbuf_addf(err, "couldn't close '%s.lock'",
3700 update->refname);
3701 return TRANSACTION_GENERIC_ERROR;
3702 }
3703 }
3704 return 0;
3705 }
3706
3707 int ref_transaction_commit(struct ref_transaction *transaction,
3708 struct strbuf *err)
3709 {
3710 int ret = 0, i;
3711 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3712 struct string_list_item *ref_to_delete;
3713 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
3714 char *head_ref = NULL;
3715 int head_type;
3716 struct object_id head_oid;
3717
3718 assert(err);
3719
3720 if (transaction->state != REF_TRANSACTION_OPEN)
3721 die("BUG: commit called for transaction that is not open");
3722
3723 if (!transaction->nr) {
3724 transaction->state = REF_TRANSACTION_CLOSED;
3725 return 0;
3726 }
3727
3728 /*
3729 * Fail if a refname appears more than once in the
3730 * transaction. (If we end up splitting up any updates using
3731 * split_symref_update() or split_head_update(), those
3732 * functions will check that the new updates don't have the
3733 * same refname as any existing ones.)
3734 */
3735 for (i = 0; i < transaction->nr; i++) {
3736 struct ref_update *update = transaction->updates[i];
3737 struct string_list_item *item =
3738 string_list_append(&affected_refnames, update->refname);
3739
3740 /*
3741 * We store a pointer to update in item->util, but at
3742 * the moment we never use the value of this field
3743 * except to check whether it is non-NULL.
3744 */
3745 item->util = update;
3746 }
3747 string_list_sort(&affected_refnames);
3748 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3749 ret = TRANSACTION_GENERIC_ERROR;
3750 goto cleanup;
3751 }
3752
3753 /*
3754 * Special hack: If a branch is updated directly and HEAD
3755 * points to it (may happen on the remote side of a push
3756 * for example) then logically the HEAD reflog should be
3757 * updated too.
3758 *
3759 * A generic solution would require reverse symref lookups,
3760 * but finding all symrefs pointing to a given branch would be
3761 * rather costly for this rare event (the direct update of a
3762 * branch) to be worth it. So let's cheat and check with HEAD
3763 * only, which should cover 99% of all usage scenarios (even
3764 * 100% of the default ones).
3765 *
3766 * So if HEAD is a symbolic reference, then record the name of
3767 * the reference that it points to. If we see an update of
3768 * head_ref within the transaction, then split_head_update()
3769 * arranges for the reflog of HEAD to be updated, too.
3770 */
3771 head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
3772 head_oid.hash, &head_type);
3773
3774 if (head_ref && !(head_type & REF_ISSYMREF)) {
3775 free(head_ref);
3776 head_ref = NULL;
3777 }
3778
3779 /*
3780 * Acquire all locks, verify old values if provided, check
3781 * that new values are valid, and write new values to the
3782 * lockfiles, ready to be activated. Only keep one lockfile
3783 * open at a time to avoid running out of file descriptors.
3784 */
3785 for (i = 0; i < transaction->nr; i++) {
3786 struct ref_update *update = transaction->updates[i];
3787
3788 ret = lock_ref_for_update(update, transaction, head_ref,
3789 &affected_refnames, err);
3790 if (ret)
3791 goto cleanup;
3792 }
3793
3794 /* Perform updates first so live commits remain referenced */
3795 for (i = 0; i < transaction->nr; i++) {
3796 struct ref_update *update = transaction->updates[i];
3797 struct ref_lock *lock = update->lock;
3798
3799 if (update->flags & REF_NEEDS_COMMIT ||
3800 update->flags & REF_LOG_ONLY) {
3801 if (log_ref_write(lock->ref_name, lock->old_oid.hash,
3802 update->new_sha1,
3803 update->msg, update->flags, err)) {
3804 char *old_msg = strbuf_detach(err, NULL);
3805
3806 strbuf_addf(err, "cannot update the ref '%s': %s",
3807 lock->ref_name, old_msg);
3808 free(old_msg);
3809 unlock_ref(lock);
3810 update->lock = NULL;
3811 ret = TRANSACTION_GENERIC_ERROR;
3812 goto cleanup;
3813 }
3814 }
3815 if (update->flags & REF_NEEDS_COMMIT) {
3816 clear_loose_ref_cache(&ref_cache);
3817 if (commit_ref(lock)) {
3818 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3819 unlock_ref(lock);
3820 update->lock = NULL;
3821 ret = TRANSACTION_GENERIC_ERROR;
3822 goto cleanup;