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