refs.c: make get_main_ref_store() public and use it
[git/git.git] / refs / files-backend.c
1 #include "../cache.h"
2 #include "../refs.h"
3 #include "refs-internal.h"
4 #include "../iterator.h"
5 #include "../dir-iterator.h"
6 #include "../lockfile.h"
7 #include "../object.h"
8 #include "../dir.h"
9
10 struct ref_lock {
11 char *ref_name;
12 struct lock_file *lk;
13 struct object_id old_oid;
14 };
15
16 struct ref_entry;
17
18 /*
19 * Information used (along with the information in ref_entry) to
20 * describe a single cached reference. This data structure only
21 * occurs embedded in a union in struct ref_entry, and only when
22 * (ref_entry->flag & REF_DIR) is zero.
23 */
24 struct ref_value {
25 /*
26 * The name of the object to which this reference resolves
27 * (which may be a tag object). If REF_ISBROKEN, this is
28 * null. If REF_ISSYMREF, then this is the name of the object
29 * referred to by the last reference in the symlink chain.
30 */
31 struct object_id oid;
32
33 /*
34 * If REF_KNOWS_PEELED, then this field holds the peeled value
35 * of this reference, or null if the reference is known not to
36 * be peelable. See the documentation for peel_ref() for an
37 * exact definition of "peelable".
38 */
39 struct object_id peeled;
40 };
41
42 struct files_ref_store;
43
44 /*
45 * Information used (along with the information in ref_entry) to
46 * describe a level in the hierarchy of references. This data
47 * structure only occurs embedded in a union in struct ref_entry, and
48 * only when (ref_entry.flag & REF_DIR) is set. In that case,
49 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
50 * in the directory have already been read:
51 *
52 * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
53 * or packed references, already read.
54 *
55 * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
56 * references that hasn't been read yet (nor has any of its
57 * subdirectories).
58 *
59 * Entries within a directory are stored within a growable array of
60 * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
61 * sorted are sorted by their component name in strcmp() order and the
62 * remaining entries are unsorted.
63 *
64 * Loose references are read lazily, one directory at a time. When a
65 * directory of loose references is read, then all of the references
66 * in that directory are stored, and REF_INCOMPLETE stubs are created
67 * for any subdirectories, but the subdirectories themselves are not
68 * read. The reading is triggered by get_ref_dir().
69 */
70 struct ref_dir {
71 int nr, alloc;
72
73 /*
74 * Entries with index 0 <= i < sorted are sorted by name. New
75 * entries are appended to the list unsorted, and are sorted
76 * only when required; thus we avoid the need to sort the list
77 * after the addition of every reference.
78 */
79 int sorted;
80
81 /* A pointer to the files_ref_store that contains this ref_dir. */
82 struct files_ref_store *ref_store;
83
84 struct ref_entry **entries;
85 };
86
87 /*
88 * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
89 * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
90 * public values; see refs.h.
91 */
92
93 /*
94 * The field ref_entry->u.value.peeled of this value entry contains
95 * the correct peeled value for the reference, which might be
96 * null_sha1 if the reference is not a tag or if it is broken.
97 */
98 #define REF_KNOWS_PEELED 0x10
99
100 /* ref_entry represents a directory of references */
101 #define REF_DIR 0x20
102
103 /*
104 * Entry has not yet been read from disk (used only for REF_DIR
105 * entries representing loose references)
106 */
107 #define REF_INCOMPLETE 0x40
108
109 /*
110 * A ref_entry represents either a reference or a "subdirectory" of
111 * references.
112 *
113 * Each directory in the reference namespace is represented by a
114 * ref_entry with (flags & REF_DIR) set and containing a subdir member
115 * that holds the entries in that directory that have been read so
116 * far. If (flags & REF_INCOMPLETE) is set, then the directory and
117 * its subdirectories haven't been read yet. REF_INCOMPLETE is only
118 * used for loose reference directories.
119 *
120 * References are represented by a ref_entry with (flags & REF_DIR)
121 * unset and a value member that describes the reference's value. The
122 * flag member is at the ref_entry level, but it is also needed to
123 * interpret the contents of the value field (in other words, a
124 * ref_value object is not very much use without the enclosing
125 * ref_entry).
126 *
127 * Reference names cannot end with slash and directories' names are
128 * always stored with a trailing slash (except for the top-level
129 * directory, which is always denoted by ""). This has two nice
130 * consequences: (1) when the entries in each subdir are sorted
131 * lexicographically by name (as they usually are), the references in
132 * a whole tree can be generated in lexicographic order by traversing
133 * the tree in left-to-right, depth-first order; (2) the names of
134 * references and subdirectories cannot conflict, and therefore the
135 * presence of an empty subdirectory does not block the creation of a
136 * similarly-named reference. (The fact that reference names with the
137 * same leading components can conflict *with each other* is a
138 * separate issue that is regulated by verify_refname_available().)
139 *
140 * Please note that the name field contains the fully-qualified
141 * reference (or subdirectory) name. Space could be saved by only
142 * storing the relative names. But that would require the full names
143 * to be generated on the fly when iterating in do_for_each_ref(), and
144 * would break callback functions, who have always been able to assume
145 * that the name strings that they are passed will not be freed during
146 * the iteration.
147 */
148 struct ref_entry {
149 unsigned char flag; /* ISSYMREF? ISPACKED? */
150 union {
151 struct ref_value value; /* if not (flags&REF_DIR) */
152 struct ref_dir subdir; /* if (flags&REF_DIR) */
153 } u;
154 /*
155 * The full name of the reference (e.g., "refs/heads/master")
156 * or the full name of the directory with a trailing slash
157 * (e.g., "refs/heads/"):
158 */
159 char name[FLEX_ARRAY];
160 };
161
162 static void read_loose_refs(const char *dirname, struct ref_dir *dir);
163 static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
164 static struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
165 const char *dirname, size_t len,
166 int incomplete);
167 static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
168 static int files_log_ref_write(struct files_ref_store *refs,
169 const char *refname, const unsigned char *old_sha1,
170 const unsigned char *new_sha1, const char *msg,
171 int flags, struct strbuf *err);
172
173 static struct ref_dir *get_ref_dir(struct ref_entry *entry)
174 {
175 struct ref_dir *dir;
176 assert(entry->flag & REF_DIR);
177 dir = &entry->u.subdir;
178 if (entry->flag & REF_INCOMPLETE) {
179 read_loose_refs(entry->name, dir);
180
181 /*
182 * Manually add refs/bisect, which, being
183 * per-worktree, might not appear in the directory
184 * listing for refs/ in the main repo.
185 */
186 if (!strcmp(entry->name, "refs/")) {
187 int pos = search_ref_dir(dir, "refs/bisect/", 12);
188 if (pos < 0) {
189 struct ref_entry *child_entry;
190 child_entry = create_dir_entry(dir->ref_store,
191 "refs/bisect/",
192 12, 1);
193 add_entry_to_dir(dir, child_entry);
194 read_loose_refs("refs/bisect",
195 &child_entry->u.subdir);
196 }
197 }
198 entry->flag &= ~REF_INCOMPLETE;
199 }
200 return dir;
201 }
202
203 static struct ref_entry *create_ref_entry(const char *refname,
204 const unsigned char *sha1, int flag,
205 int check_name)
206 {
207 struct ref_entry *ref;
208
209 if (check_name &&
210 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
211 die("Reference has invalid format: '%s'", refname);
212 FLEX_ALLOC_STR(ref, name, refname);
213 hashcpy(ref->u.value.oid.hash, sha1);
214 oidclr(&ref->u.value.peeled);
215 ref->flag = flag;
216 return ref;
217 }
218
219 static void clear_ref_dir(struct ref_dir *dir);
220
221 static void free_ref_entry(struct ref_entry *entry)
222 {
223 if (entry->flag & REF_DIR) {
224 /*
225 * Do not use get_ref_dir() here, as that might
226 * trigger the reading of loose refs.
227 */
228 clear_ref_dir(&entry->u.subdir);
229 }
230 free(entry);
231 }
232
233 /*
234 * Add a ref_entry to the end of dir (unsorted). Entry is always
235 * stored directly in dir; no recursion into subdirectories is
236 * done.
237 */
238 static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
239 {
240 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
241 dir->entries[dir->nr++] = entry;
242 /* optimize for the case that entries are added in order */
243 if (dir->nr == 1 ||
244 (dir->nr == dir->sorted + 1 &&
245 strcmp(dir->entries[dir->nr - 2]->name,
246 dir->entries[dir->nr - 1]->name) < 0))
247 dir->sorted = dir->nr;
248 }
249
250 /*
251 * Clear and free all entries in dir, recursively.
252 */
253 static void clear_ref_dir(struct ref_dir *dir)
254 {
255 int i;
256 for (i = 0; i < dir->nr; i++)
257 free_ref_entry(dir->entries[i]);
258 free(dir->entries);
259 dir->sorted = dir->nr = dir->alloc = 0;
260 dir->entries = NULL;
261 }
262
263 /*
264 * Create a struct ref_entry object for the specified dirname.
265 * dirname is the name of the directory with a trailing slash (e.g.,
266 * "refs/heads/") or "" for the top-level directory.
267 */
268 static struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
269 const char *dirname, size_t len,
270 int incomplete)
271 {
272 struct ref_entry *direntry;
273 FLEX_ALLOC_MEM(direntry, name, dirname, len);
274 direntry->u.subdir.ref_store = ref_store;
275 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
276 return direntry;
277 }
278
279 static int ref_entry_cmp(const void *a, const void *b)
280 {
281 struct ref_entry *one = *(struct ref_entry **)a;
282 struct ref_entry *two = *(struct ref_entry **)b;
283 return strcmp(one->name, two->name);
284 }
285
286 static void sort_ref_dir(struct ref_dir *dir);
287
288 struct string_slice {
289 size_t len;
290 const char *str;
291 };
292
293 static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
294 {
295 const struct string_slice *key = key_;
296 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
297 int cmp = strncmp(key->str, ent->name, key->len);
298 if (cmp)
299 return cmp;
300 return '\0' - (unsigned char)ent->name[key->len];
301 }
302
303 /*
304 * Return the index of the entry with the given refname from the
305 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
306 * no such entry is found. dir must already be complete.
307 */
308 static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
309 {
310 struct ref_entry **r;
311 struct string_slice key;
312
313 if (refname == NULL || !dir->nr)
314 return -1;
315
316 sort_ref_dir(dir);
317 key.len = len;
318 key.str = refname;
319 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
320 ref_entry_cmp_sslice);
321
322 if (r == NULL)
323 return -1;
324
325 return r - dir->entries;
326 }
327
328 /*
329 * Search for a directory entry directly within dir (without
330 * recursing). Sort dir if necessary. subdirname must be a directory
331 * name (i.e., end in '/'). If mkdir is set, then create the
332 * directory if it is missing; otherwise, return NULL if the desired
333 * directory cannot be found. dir must already be complete.
334 */
335 static struct ref_dir *search_for_subdir(struct ref_dir *dir,
336 const char *subdirname, size_t len,
337 int mkdir)
338 {
339 int entry_index = search_ref_dir(dir, subdirname, len);
340 struct ref_entry *entry;
341 if (entry_index == -1) {
342 if (!mkdir)
343 return NULL;
344 /*
345 * Since dir is complete, the absence of a subdir
346 * means that the subdir really doesn't exist;
347 * therefore, create an empty record for it but mark
348 * the record complete.
349 */
350 entry = create_dir_entry(dir->ref_store, subdirname, len, 0);
351 add_entry_to_dir(dir, entry);
352 } else {
353 entry = dir->entries[entry_index];
354 }
355 return get_ref_dir(entry);
356 }
357
358 /*
359 * If refname is a reference name, find the ref_dir within the dir
360 * tree that should hold refname. If refname is a directory name
361 * (i.e., ends in '/'), then return that ref_dir itself. dir must
362 * represent the top-level directory and must already be complete.
363 * Sort ref_dirs and recurse into subdirectories as necessary. If
364 * mkdir is set, then create any missing directories; otherwise,
365 * return NULL if the desired directory cannot be found.
366 */
367 static struct ref_dir *find_containing_dir(struct ref_dir *dir,
368 const char *refname, int mkdir)
369 {
370 const char *slash;
371 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
372 size_t dirnamelen = slash - refname + 1;
373 struct ref_dir *subdir;
374 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
375 if (!subdir) {
376 dir = NULL;
377 break;
378 }
379 dir = subdir;
380 }
381
382 return dir;
383 }
384
385 /*
386 * Find the value entry with the given name in dir, sorting ref_dirs
387 * and recursing into subdirectories as necessary. If the name is not
388 * found or it corresponds to a directory entry, return NULL.
389 */
390 static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
391 {
392 int entry_index;
393 struct ref_entry *entry;
394 dir = find_containing_dir(dir, refname, 0);
395 if (!dir)
396 return NULL;
397 entry_index = search_ref_dir(dir, refname, strlen(refname));
398 if (entry_index == -1)
399 return NULL;
400 entry = dir->entries[entry_index];
401 return (entry->flag & REF_DIR) ? NULL : entry;
402 }
403
404 /*
405 * Remove the entry with the given name from dir, recursing into
406 * subdirectories as necessary. If refname is the name of a directory
407 * (i.e., ends with '/'), then remove the directory and its contents.
408 * If the removal was successful, return the number of entries
409 * remaining in the directory entry that contained the deleted entry.
410 * If the name was not found, return -1. Please note that this
411 * function only deletes the entry from the cache; it does not delete
412 * it from the filesystem or ensure that other cache entries (which
413 * might be symbolic references to the removed entry) are updated.
414 * Nor does it remove any containing dir entries that might be made
415 * empty by the removal. dir must represent the top-level directory
416 * and must already be complete.
417 */
418 static int remove_entry(struct ref_dir *dir, const char *refname)
419 {
420 int refname_len = strlen(refname);
421 int entry_index;
422 struct ref_entry *entry;
423 int is_dir = refname[refname_len - 1] == '/';
424 if (is_dir) {
425 /*
426 * refname represents a reference directory. Remove
427 * the trailing slash; otherwise we will get the
428 * directory *representing* refname rather than the
429 * one *containing* it.
430 */
431 char *dirname = xmemdupz(refname, refname_len - 1);
432 dir = find_containing_dir(dir, dirname, 0);
433 free(dirname);
434 } else {
435 dir = find_containing_dir(dir, refname, 0);
436 }
437 if (!dir)
438 return -1;
439 entry_index = search_ref_dir(dir, refname, refname_len);
440 if (entry_index == -1)
441 return -1;
442 entry = dir->entries[entry_index];
443
444 memmove(&dir->entries[entry_index],
445 &dir->entries[entry_index + 1],
446 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
447 );
448 dir->nr--;
449 if (dir->sorted > entry_index)
450 dir->sorted--;
451 free_ref_entry(entry);
452 return dir->nr;
453 }
454
455 /*
456 * Add a ref_entry to the ref_dir (unsorted), recursing into
457 * subdirectories as necessary. dir must represent the top-level
458 * directory. Return 0 on success.
459 */
460 static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
461 {
462 dir = find_containing_dir(dir, ref->name, 1);
463 if (!dir)
464 return -1;
465 add_entry_to_dir(dir, ref);
466 return 0;
467 }
468
469 /*
470 * Emit a warning and return true iff ref1 and ref2 have the same name
471 * and the same sha1. Die if they have the same name but different
472 * sha1s.
473 */
474 static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
475 {
476 if (strcmp(ref1->name, ref2->name))
477 return 0;
478
479 /* Duplicate name; make sure that they don't conflict: */
480
481 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
482 /* This is impossible by construction */
483 die("Reference directory conflict: %s", ref1->name);
484
485 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
486 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
487
488 warning("Duplicated ref: %s", ref1->name);
489 return 1;
490 }
491
492 /*
493 * Sort the entries in dir non-recursively (if they are not already
494 * sorted) and remove any duplicate entries.
495 */
496 static void sort_ref_dir(struct ref_dir *dir)
497 {
498 int i, j;
499 struct ref_entry *last = NULL;
500
501 /*
502 * This check also prevents passing a zero-length array to qsort(),
503 * which is a problem on some platforms.
504 */
505 if (dir->sorted == dir->nr)
506 return;
507
508 QSORT(dir->entries, dir->nr, ref_entry_cmp);
509
510 /* Remove any duplicates: */
511 for (i = 0, j = 0; j < dir->nr; j++) {
512 struct ref_entry *entry = dir->entries[j];
513 if (last && is_dup_ref(last, entry))
514 free_ref_entry(entry);
515 else
516 last = dir->entries[i++] = entry;
517 }
518 dir->sorted = dir->nr = i;
519 }
520
521 /*
522 * Return true if refname, which has the specified oid and flags, can
523 * be resolved to an object in the database. If the referred-to object
524 * does not exist, emit a warning and return false.
525 */
526 static int ref_resolves_to_object(const char *refname,
527 const struct object_id *oid,
528 unsigned int flags)
529 {
530 if (flags & REF_ISBROKEN)
531 return 0;
532 if (!has_sha1_file(oid->hash)) {
533 error("%s does not point to a valid object!", refname);
534 return 0;
535 }
536 return 1;
537 }
538
539 /*
540 * Return true if the reference described by entry can be resolved to
541 * an object in the database; otherwise, emit a warning and return
542 * false.
543 */
544 static int entry_resolves_to_object(struct ref_entry *entry)
545 {
546 return ref_resolves_to_object(entry->name,
547 &entry->u.value.oid, entry->flag);
548 }
549
550 typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
551
552 /*
553 * Call fn for each reference in dir that has index in the range
554 * offset <= index < dir->nr. Recurse into subdirectories that are in
555 * that index range, sorting them before iterating. This function
556 * does not sort dir itself; it should be sorted beforehand. fn is
557 * called for all references, including broken ones.
558 */
559 static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
560 each_ref_entry_fn fn, void *cb_data)
561 {
562 int i;
563 assert(dir->sorted == dir->nr);
564 for (i = offset; i < dir->nr; i++) {
565 struct ref_entry *entry = dir->entries[i];
566 int retval;
567 if (entry->flag & REF_DIR) {
568 struct ref_dir *subdir = get_ref_dir(entry);
569 sort_ref_dir(subdir);
570 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
571 } else {
572 retval = fn(entry, cb_data);
573 }
574 if (retval)
575 return retval;
576 }
577 return 0;
578 }
579
580 /*
581 * Load all of the refs from the dir into our in-memory cache. The hard work
582 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
583 * through all of the sub-directories. We do not even need to care about
584 * sorting, as traversal order does not matter to us.
585 */
586 static void prime_ref_dir(struct ref_dir *dir)
587 {
588 int i;
589 for (i = 0; i < dir->nr; i++) {
590 struct ref_entry *entry = dir->entries[i];
591 if (entry->flag & REF_DIR)
592 prime_ref_dir(get_ref_dir(entry));
593 }
594 }
595
596 /*
597 * A level in the reference hierarchy that is currently being iterated
598 * through.
599 */
600 struct cache_ref_iterator_level {
601 /*
602 * The ref_dir being iterated over at this level. The ref_dir
603 * is sorted before being stored here.
604 */
605 struct ref_dir *dir;
606
607 /*
608 * The index of the current entry within dir (which might
609 * itself be a directory). If index == -1, then the iteration
610 * hasn't yet begun. If index == dir->nr, then the iteration
611 * through this level is over.
612 */
613 int index;
614 };
615
616 /*
617 * Represent an iteration through a ref_dir in the memory cache. The
618 * iteration recurses through subdirectories.
619 */
620 struct cache_ref_iterator {
621 struct ref_iterator base;
622
623 /*
624 * The number of levels currently on the stack. This is always
625 * at least 1, because when it becomes zero the iteration is
626 * ended and this struct is freed.
627 */
628 size_t levels_nr;
629
630 /* The number of levels that have been allocated on the stack */
631 size_t levels_alloc;
632
633 /*
634 * A stack of levels. levels[0] is the uppermost level that is
635 * being iterated over in this iteration. (This is not
636 * necessary the top level in the references hierarchy. If we
637 * are iterating through a subtree, then levels[0] will hold
638 * the ref_dir for that subtree, and subsequent levels will go
639 * on from there.)
640 */
641 struct cache_ref_iterator_level *levels;
642 };
643
644 static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
645 {
646 struct cache_ref_iterator *iter =
647 (struct cache_ref_iterator *)ref_iterator;
648
649 while (1) {
650 struct cache_ref_iterator_level *level =
651 &iter->levels[iter->levels_nr - 1];
652 struct ref_dir *dir = level->dir;
653 struct ref_entry *entry;
654
655 if (level->index == -1)
656 sort_ref_dir(dir);
657
658 if (++level->index == level->dir->nr) {
659 /* This level is exhausted; pop up a level */
660 if (--iter->levels_nr == 0)
661 return ref_iterator_abort(ref_iterator);
662
663 continue;
664 }
665
666 entry = dir->entries[level->index];
667
668 if (entry->flag & REF_DIR) {
669 /* push down a level */
670 ALLOC_GROW(iter->levels, iter->levels_nr + 1,
671 iter->levels_alloc);
672
673 level = &iter->levels[iter->levels_nr++];
674 level->dir = get_ref_dir(entry);
675 level->index = -1;
676 } else {
677 iter->base.refname = entry->name;
678 iter->base.oid = &entry->u.value.oid;
679 iter->base.flags = entry->flag;
680 return ITER_OK;
681 }
682 }
683 }
684
685 static enum peel_status peel_entry(struct ref_entry *entry, int repeel);
686
687 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
688 struct object_id *peeled)
689 {
690 struct cache_ref_iterator *iter =
691 (struct cache_ref_iterator *)ref_iterator;
692 struct cache_ref_iterator_level *level;
693 struct ref_entry *entry;
694
695 level = &iter->levels[iter->levels_nr - 1];
696
697 if (level->index == -1)
698 die("BUG: peel called before advance for cache iterator");
699
700 entry = level->dir->entries[level->index];
701
702 if (peel_entry(entry, 0))
703 return -1;
704 oidcpy(peeled, &entry->u.value.peeled);
705 return 0;
706 }
707
708 static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
709 {
710 struct cache_ref_iterator *iter =
711 (struct cache_ref_iterator *)ref_iterator;
712
713 free(iter->levels);
714 base_ref_iterator_free(ref_iterator);
715 return ITER_DONE;
716 }
717
718 static struct ref_iterator_vtable cache_ref_iterator_vtable = {
719 cache_ref_iterator_advance,
720 cache_ref_iterator_peel,
721 cache_ref_iterator_abort
722 };
723
724 static struct ref_iterator *cache_ref_iterator_begin(struct ref_dir *dir)
725 {
726 struct cache_ref_iterator *iter;
727 struct ref_iterator *ref_iterator;
728 struct cache_ref_iterator_level *level;
729
730 iter = xcalloc(1, sizeof(*iter));
731 ref_iterator = &iter->base;
732 base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
733 ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
734
735 iter->levels_nr = 1;
736 level = &iter->levels[0];
737 level->index = -1;
738 level->dir = dir;
739
740 return ref_iterator;
741 }
742
743 struct nonmatching_ref_data {
744 const struct string_list *skip;
745 const char *conflicting_refname;
746 };
747
748 static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
749 {
750 struct nonmatching_ref_data *data = vdata;
751
752 if (data->skip && string_list_has_string(data->skip, entry->name))
753 return 0;
754
755 data->conflicting_refname = entry->name;
756 return 1;
757 }
758
759 /*
760 * Return 0 if a reference named refname could be created without
761 * conflicting with the name of an existing reference in dir.
762 * See verify_refname_available for more information.
763 */
764 static int verify_refname_available_dir(const char *refname,
765 const struct string_list *extras,
766 const struct string_list *skip,
767 struct ref_dir *dir,
768 struct strbuf *err)
769 {
770 const char *slash;
771 const char *extra_refname;
772 int pos;
773 struct strbuf dirname = STRBUF_INIT;
774 int ret = -1;
775
776 /*
777 * For the sake of comments in this function, suppose that
778 * refname is "refs/foo/bar".
779 */
780
781 assert(err);
782
783 strbuf_grow(&dirname, strlen(refname) + 1);
784 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
785 /* Expand dirname to the new prefix, not including the trailing slash: */
786 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
787
788 /*
789 * We are still at a leading dir of the refname (e.g.,
790 * "refs/foo"; if there is a reference with that name,
791 * it is a conflict, *unless* it is in skip.
792 */
793 if (dir) {
794 pos = search_ref_dir(dir, dirname.buf, dirname.len);
795 if (pos >= 0 &&
796 (!skip || !string_list_has_string(skip, dirname.buf))) {
797 /*
798 * We found a reference whose name is
799 * a proper prefix of refname; e.g.,
800 * "refs/foo", and is not in skip.
801 */
802 strbuf_addf(err, "'%s' exists; cannot create '%s'",
803 dirname.buf, refname);
804 goto cleanup;
805 }
806 }
807
808 if (extras && string_list_has_string(extras, dirname.buf) &&
809 (!skip || !string_list_has_string(skip, dirname.buf))) {
810 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
811 refname, dirname.buf);
812 goto cleanup;
813 }
814
815 /*
816 * Otherwise, we can try to continue our search with
817 * the next component. So try to look up the
818 * directory, e.g., "refs/foo/". If we come up empty,
819 * we know there is nothing under this whole prefix,
820 * but even in that case we still have to continue the
821 * search for conflicts with extras.
822 */
823 strbuf_addch(&dirname, '/');
824 if (dir) {
825 pos = search_ref_dir(dir, dirname.buf, dirname.len);
826 if (pos < 0) {
827 /*
828 * There was no directory "refs/foo/",
829 * so there is nothing under this
830 * whole prefix. So there is no need
831 * to continue looking for conflicting
832 * references. But we need to continue
833 * looking for conflicting extras.
834 */
835 dir = NULL;
836 } else {
837 dir = get_ref_dir(dir->entries[pos]);
838 }
839 }
840 }
841
842 /*
843 * We are at the leaf of our refname (e.g., "refs/foo/bar").
844 * There is no point in searching for a reference with that
845 * name, because a refname isn't considered to conflict with
846 * itself. But we still need to check for references whose
847 * names are in the "refs/foo/bar/" namespace, because they
848 * *do* conflict.
849 */
850 strbuf_addstr(&dirname, refname + dirname.len);
851 strbuf_addch(&dirname, '/');
852
853 if (dir) {
854 pos = search_ref_dir(dir, dirname.buf, dirname.len);
855
856 if (pos >= 0) {
857 /*
858 * We found a directory named "$refname/"
859 * (e.g., "refs/foo/bar/"). It is a problem
860 * iff it contains any ref that is not in
861 * "skip".
862 */
863 struct nonmatching_ref_data data;
864
865 data.skip = skip;
866 data.conflicting_refname = NULL;
867 dir = get_ref_dir(dir->entries[pos]);
868 sort_ref_dir(dir);
869 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
870 strbuf_addf(err, "'%s' exists; cannot create '%s'",
871 data.conflicting_refname, refname);
872 goto cleanup;
873 }
874 }
875 }
876
877 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
878 if (extra_refname)
879 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
880 refname, extra_refname);
881 else
882 ret = 0;
883
884 cleanup:
885 strbuf_release(&dirname);
886 return ret;
887 }
888
889 struct packed_ref_cache {
890 struct ref_entry *root;
891
892 /*
893 * Count of references to the data structure in this instance,
894 * including the pointer from files_ref_store::packed if any.
895 * The data will not be freed as long as the reference count
896 * is nonzero.
897 */
898 unsigned int referrers;
899
900 /*
901 * Iff the packed-refs file associated with this instance is
902 * currently locked for writing, this points at the associated
903 * lock (which is owned by somebody else). The referrer count
904 * is also incremented when the file is locked and decremented
905 * when it is unlocked.
906 */
907 struct lock_file *lock;
908
909 /* The metadata from when this packed-refs cache was read */
910 struct stat_validity validity;
911 };
912
913 /*
914 * Future: need to be in "struct repository"
915 * when doing a full libification.
916 */
917 struct files_ref_store {
918 struct ref_store base;
919
920 /*
921 * The name of the submodule represented by this object, or
922 * NULL if it represents the main repository's reference
923 * store:
924 */
925 const char *submodule;
926 char *gitdir;
927 char *gitcommondir;
928 char *packed_refs_path;
929
930 struct ref_entry *loose;
931 struct packed_ref_cache *packed;
932 };
933
934 /* Lock used for the main packed-refs file: */
935 static struct lock_file packlock;
936
937 /*
938 * Increment the reference count of *packed_refs.
939 */
940 static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
941 {
942 packed_refs->referrers++;
943 }
944
945 /*
946 * Decrease the reference count of *packed_refs. If it goes to zero,
947 * free *packed_refs and return true; otherwise return false.
948 */
949 static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
950 {
951 if (!--packed_refs->referrers) {
952 free_ref_entry(packed_refs->root);
953 stat_validity_clear(&packed_refs->validity);
954 free(packed_refs);
955 return 1;
956 } else {
957 return 0;
958 }
959 }
960
961 static void clear_packed_ref_cache(struct files_ref_store *refs)
962 {
963 if (refs->packed) {
964 struct packed_ref_cache *packed_refs = refs->packed;
965
966 if (packed_refs->lock)
967 die("internal error: packed-ref cache cleared while locked");
968 refs->packed = NULL;
969 release_packed_ref_cache(packed_refs);
970 }
971 }
972
973 static void clear_loose_ref_cache(struct files_ref_store *refs)
974 {
975 if (refs->loose) {
976 free_ref_entry(refs->loose);
977 refs->loose = NULL;
978 }
979 }
980
981 /*
982 * Create a new submodule ref cache and add it to the internal
983 * set of caches.
984 */
985 static struct ref_store *files_ref_store_create(const char *submodule)
986 {
987 struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
988 struct ref_store *ref_store = (struct ref_store *)refs;
989 struct strbuf sb = STRBUF_INIT;
990 const char *gitdir = get_git_dir();
991
992 base_ref_store_init(ref_store, &refs_be_files);
993
994 if (submodule) {
995 refs->submodule = xstrdup(submodule);
996 refs->packed_refs_path = git_pathdup_submodule(
997 refs->submodule, "packed-refs");
998 return ref_store;
999 }
1000
1001 refs->gitdir = xstrdup(gitdir);
1002 get_common_dir_noenv(&sb, gitdir);
1003 refs->gitcommondir = strbuf_detach(&sb, NULL);
1004 strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
1005 refs->packed_refs_path = strbuf_detach(&sb, NULL);
1006
1007 return ref_store;
1008 }
1009
1010 /*
1011 * Die if refs is for a submodule (i.e., not for the main repository).
1012 * caller is used in any necessary error messages.
1013 */
1014 static void files_assert_main_repository(struct files_ref_store *refs,
1015 const char *caller)
1016 {
1017 if (refs->submodule)
1018 die("BUG: %s called for a submodule", caller);
1019 }
1020
1021 /*
1022 * Downcast ref_store to files_ref_store. Die if ref_store is not a
1023 * files_ref_store. If submodule_allowed is not true, then also die if
1024 * files_ref_store is for a submodule (i.e., not for the main
1025 * repository). caller is used in any necessary error messages.
1026 */
1027 static struct files_ref_store *files_downcast(
1028 struct ref_store *ref_store, int submodule_allowed,
1029 const char *caller)
1030 {
1031 struct files_ref_store *refs;
1032
1033 if (ref_store->be != &refs_be_files)
1034 die("BUG: ref_store is type \"%s\" not \"files\" in %s",
1035 ref_store->be->name, caller);
1036
1037 refs = (struct files_ref_store *)ref_store;
1038
1039 if (!submodule_allowed)
1040 files_assert_main_repository(refs, caller);
1041
1042 return refs;
1043 }
1044
1045 /* The length of a peeled reference line in packed-refs, including EOL: */
1046 #define PEELED_LINE_LENGTH 42
1047
1048 /*
1049 * The packed-refs header line that we write out. Perhaps other
1050 * traits will be added later. The trailing space is required.
1051 */
1052 static const char PACKED_REFS_HEADER[] =
1053 "# pack-refs with: peeled fully-peeled \n";
1054
1055 /*
1056 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
1057 * Return a pointer to the refname within the line (null-terminated),
1058 * or NULL if there was a problem.
1059 */
1060 static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
1061 {
1062 const char *ref;
1063
1064 /*
1065 * 42: the answer to everything.
1066 *
1067 * In this case, it happens to be the answer to
1068 * 40 (length of sha1 hex representation)
1069 * +1 (space in between hex and name)
1070 * +1 (newline at the end of the line)
1071 */
1072 if (line->len <= 42)
1073 return NULL;
1074
1075 if (get_sha1_hex(line->buf, sha1) < 0)
1076 return NULL;
1077 if (!isspace(line->buf[40]))
1078 return NULL;
1079
1080 ref = line->buf + 41;
1081 if (isspace(*ref))
1082 return NULL;
1083
1084 if (line->buf[line->len - 1] != '\n')
1085 return NULL;
1086 line->buf[--line->len] = 0;
1087
1088 return ref;
1089 }
1090
1091 /*
1092 * Read f, which is a packed-refs file, into dir.
1093 *
1094 * A comment line of the form "# pack-refs with: " may contain zero or
1095 * more traits. We interpret the traits as follows:
1096 *
1097 * No traits:
1098 *
1099 * Probably no references are peeled. But if the file contains a
1100 * peeled value for a reference, we will use it.
1101 *
1102 * peeled:
1103 *
1104 * References under "refs/tags/", if they *can* be peeled, *are*
1105 * peeled in this file. References outside of "refs/tags/" are
1106 * probably not peeled even if they could have been, but if we find
1107 * a peeled value for such a reference we will use it.
1108 *
1109 * fully-peeled:
1110 *
1111 * All references in the file that can be peeled are peeled.
1112 * Inversely (and this is more important), any references in the
1113 * file for which no peeled value is recorded is not peelable. This
1114 * trait should typically be written alongside "peeled" for
1115 * compatibility with older clients, but we do not require it
1116 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1117 */
1118 static void read_packed_refs(FILE *f, struct ref_dir *dir)
1119 {
1120 struct ref_entry *last = NULL;
1121 struct strbuf line = STRBUF_INIT;
1122 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1123
1124 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1125 unsigned char sha1[20];
1126 const char *refname;
1127 const char *traits;
1128
1129 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1130 if (strstr(traits, " fully-peeled "))
1131 peeled = PEELED_FULLY;
1132 else if (strstr(traits, " peeled "))
1133 peeled = PEELED_TAGS;
1134 /* perhaps other traits later as well */
1135 continue;
1136 }
1137
1138 refname = parse_ref_line(&line, sha1);
1139 if (refname) {
1140 int flag = REF_ISPACKED;
1141
1142 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1143 if (!refname_is_safe(refname))
1144 die("packed refname is dangerous: %s", refname);
1145 hashclr(sha1);
1146 flag |= REF_BAD_NAME | REF_ISBROKEN;
1147 }
1148 last = create_ref_entry(refname, sha1, flag, 0);
1149 if (peeled == PEELED_FULLY ||
1150 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1151 last->flag |= REF_KNOWS_PEELED;
1152 add_ref(dir, last);
1153 continue;
1154 }
1155 if (last &&
1156 line.buf[0] == '^' &&
1157 line.len == PEELED_LINE_LENGTH &&
1158 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1159 !get_sha1_hex(line.buf + 1, sha1)) {
1160 hashcpy(last->u.value.peeled.hash, sha1);
1161 /*
1162 * Regardless of what the file header said,
1163 * we definitely know the value of *this*
1164 * reference:
1165 */
1166 last->flag |= REF_KNOWS_PEELED;
1167 }
1168 }
1169
1170 strbuf_release(&line);
1171 }
1172
1173 static const char *files_packed_refs_path(struct files_ref_store *refs)
1174 {
1175 return refs->packed_refs_path;
1176 }
1177
1178 static void files_reflog_path(struct files_ref_store *refs,
1179 struct strbuf *sb,
1180 const char *refname)
1181 {
1182 if (!refname) {
1183 /*
1184 * FIXME: of course this is wrong in multi worktree
1185 * setting. To be fixed real soon.
1186 */
1187 strbuf_addf(sb, "%s/logs", refs->gitcommondir);
1188 return;
1189 }
1190
1191 switch (ref_type(refname)) {
1192 case REF_TYPE_PER_WORKTREE:
1193 case REF_TYPE_PSEUDOREF:
1194 strbuf_addf(sb, "%s/logs/%s", refs->gitdir, refname);
1195 break;
1196 case REF_TYPE_NORMAL:
1197 strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, refname);
1198 break;
1199 default:
1200 die("BUG: unknown ref type %d of ref %s",
1201 ref_type(refname), refname);
1202 }
1203 }
1204
1205 static void files_ref_path(struct files_ref_store *refs,
1206 struct strbuf *sb,
1207 const char *refname)
1208 {
1209 if (refs->submodule) {
1210 strbuf_git_path_submodule(sb, refs->submodule, "%s", refname);
1211 return;
1212 }
1213
1214 switch (ref_type(refname)) {
1215 case REF_TYPE_PER_WORKTREE:
1216 case REF_TYPE_PSEUDOREF:
1217 strbuf_addf(sb, "%s/%s", refs->gitdir, refname);
1218 break;
1219 case REF_TYPE_NORMAL:
1220 strbuf_addf(sb, "%s/%s", refs->gitcommondir, refname);
1221 break;
1222 default:
1223 die("BUG: unknown ref type %d of ref %s",
1224 ref_type(refname), refname);
1225 }
1226 }
1227
1228 /*
1229 * Get the packed_ref_cache for the specified files_ref_store,
1230 * creating it if necessary.
1231 */
1232 static struct packed_ref_cache *get_packed_ref_cache(struct files_ref_store *refs)
1233 {
1234 const char *packed_refs_file = files_packed_refs_path(refs);
1235
1236 if (refs->packed &&
1237 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1238 clear_packed_ref_cache(refs);
1239
1240 if (!refs->packed) {
1241 FILE *f;
1242
1243 refs->packed = xcalloc(1, sizeof(*refs->packed));
1244 acquire_packed_ref_cache(refs->packed);
1245 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1246 f = fopen(packed_refs_file, "r");
1247 if (f) {
1248 stat_validity_update(&refs->packed->validity, fileno(f));
1249 read_packed_refs(f, get_ref_dir(refs->packed->root));
1250 fclose(f);
1251 }
1252 }
1253 return refs->packed;
1254 }
1255
1256 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1257 {
1258 return get_ref_dir(packed_ref_cache->root);
1259 }
1260
1261 static struct ref_dir *get_packed_refs(struct files_ref_store *refs)
1262 {
1263 return get_packed_ref_dir(get_packed_ref_cache(refs));
1264 }
1265
1266 /*
1267 * Add a reference to the in-memory packed reference cache. This may
1268 * only be called while the packed-refs file is locked (see
1269 * lock_packed_refs()). To actually write the packed-refs file, call
1270 * commit_packed_refs().
1271 */
1272 static void add_packed_ref(struct files_ref_store *refs,
1273 const char *refname, const unsigned char *sha1)
1274 {
1275 struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
1276
1277 if (!packed_ref_cache->lock)
1278 die("internal error: packed refs not locked");
1279 add_ref(get_packed_ref_dir(packed_ref_cache),
1280 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1281 }
1282
1283 /*
1284 * Read the loose references from the namespace dirname into dir
1285 * (without recursing). dirname must end with '/'. dir must be the
1286 * directory entry corresponding to dirname.
1287 */
1288 static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1289 {
1290 struct files_ref_store *refs = dir->ref_store;
1291 DIR *d;
1292 struct dirent *de;
1293 int dirnamelen = strlen(dirname);
1294 struct strbuf refname;
1295 struct strbuf path = STRBUF_INIT;
1296 size_t path_baselen;
1297
1298 files_ref_path(refs, &path, dirname);
1299 path_baselen = path.len;
1300
1301 d = opendir(path.buf);
1302 if (!d) {
1303 strbuf_release(&path);
1304 return;
1305 }
1306
1307 strbuf_init(&refname, dirnamelen + 257);
1308 strbuf_add(&refname, dirname, dirnamelen);
1309
1310 while ((de = readdir(d)) != NULL) {
1311 unsigned char sha1[20];
1312 struct stat st;
1313 int flag;
1314
1315 if (de->d_name[0] == '.')
1316 continue;
1317 if (ends_with(de->d_name, ".lock"))
1318 continue;
1319 strbuf_addstr(&refname, de->d_name);
1320 strbuf_addstr(&path, de->d_name);
1321 if (stat(path.buf, &st) < 0) {
1322 ; /* silently ignore */
1323 } else if (S_ISDIR(st.st_mode)) {
1324 strbuf_addch(&refname, '/');
1325 add_entry_to_dir(dir,
1326 create_dir_entry(refs, refname.buf,
1327 refname.len, 1));
1328 } else {
1329 if (!resolve_ref_recursively(&refs->base,
1330 refname.buf,
1331 RESOLVE_REF_READING,
1332 sha1, &flag)) {
1333 hashclr(sha1);
1334 flag |= REF_ISBROKEN;
1335 } else if (is_null_sha1(sha1)) {
1336 /*
1337 * It is so astronomically unlikely
1338 * that NULL_SHA1 is the SHA-1 of an
1339 * actual object that we consider its
1340 * appearance in a loose reference
1341 * file to be repo corruption
1342 * (probably due to a software bug).
1343 */
1344 flag |= REF_ISBROKEN;
1345 }
1346
1347 if (check_refname_format(refname.buf,
1348 REFNAME_ALLOW_ONELEVEL)) {
1349 if (!refname_is_safe(refname.buf))
1350 die("loose refname is dangerous: %s", refname.buf);
1351 hashclr(sha1);
1352 flag |= REF_BAD_NAME | REF_ISBROKEN;
1353 }
1354 add_entry_to_dir(dir,
1355 create_ref_entry(refname.buf, sha1, flag, 0));
1356 }
1357 strbuf_setlen(&refname, dirnamelen);
1358 strbuf_setlen(&path, path_baselen);
1359 }
1360 strbuf_release(&refname);
1361 strbuf_release(&path);
1362 closedir(d);
1363 }
1364
1365 static struct ref_dir *get_loose_refs(struct files_ref_store *refs)
1366 {
1367 if (!refs->loose) {
1368 /*
1369 * Mark the top-level directory complete because we
1370 * are about to read the only subdirectory that can
1371 * hold references:
1372 */
1373 refs->loose = create_dir_entry(refs, "", 0, 0);
1374 /*
1375 * Create an incomplete entry for "refs/":
1376 */
1377 add_entry_to_dir(get_ref_dir(refs->loose),
1378 create_dir_entry(refs, "refs/", 5, 1));
1379 }
1380 return get_ref_dir(refs->loose);
1381 }
1382
1383 /*
1384 * Return the ref_entry for the given refname from the packed
1385 * references. If it does not exist, return NULL.
1386 */
1387 static struct ref_entry *get_packed_ref(struct files_ref_store *refs,
1388 const char *refname)
1389 {
1390 return find_ref(get_packed_refs(refs), refname);
1391 }
1392
1393 /*
1394 * A loose ref file doesn't exist; check for a packed ref.
1395 */
1396 static int resolve_packed_ref(struct files_ref_store *refs,
1397 const char *refname,
1398 unsigned char *sha1, unsigned int *flags)
1399 {
1400 struct ref_entry *entry;
1401
1402 /*
1403 * The loose reference file does not exist; check for a packed
1404 * reference.
1405 */
1406 entry = get_packed_ref(refs, refname);
1407 if (entry) {
1408 hashcpy(sha1, entry->u.value.oid.hash);
1409 *flags |= REF_ISPACKED;
1410 return 0;
1411 }
1412 /* refname is not a packed reference. */
1413 return -1;
1414 }
1415
1416 static int files_read_raw_ref(struct ref_store *ref_store,
1417 const char *refname, unsigned char *sha1,
1418 struct strbuf *referent, unsigned int *type)
1419 {
1420 struct files_ref_store *refs =
1421 files_downcast(ref_store, 1, "read_raw_ref");
1422 struct strbuf sb_contents = STRBUF_INIT;
1423 struct strbuf sb_path = STRBUF_INIT;
1424 const char *path;
1425 const char *buf;
1426 struct stat st;
1427 int fd;
1428 int ret = -1;
1429 int save_errno;
1430 int remaining_retries = 3;
1431
1432 *type = 0;
1433 strbuf_reset(&sb_path);
1434
1435 files_ref_path(refs, &sb_path, refname);
1436
1437 path = sb_path.buf;
1438
1439 stat_ref:
1440 /*
1441 * We might have to loop back here to avoid a race
1442 * condition: first we lstat() the file, then we try
1443 * to read it as a link or as a file. But if somebody
1444 * changes the type of the file (file <-> directory
1445 * <-> symlink) between the lstat() and reading, then
1446 * we don't want to report that as an error but rather
1447 * try again starting with the lstat().
1448 *
1449 * We'll keep a count of the retries, though, just to avoid
1450 * any confusing situation sending us into an infinite loop.
1451 */
1452
1453 if (remaining_retries-- <= 0)
1454 goto out;
1455
1456 if (lstat(path, &st) < 0) {
1457 if (errno != ENOENT)
1458 goto out;
1459 if (resolve_packed_ref(refs, refname, sha1, type)) {
1460 errno = ENOENT;
1461 goto out;
1462 }
1463 ret = 0;
1464 goto out;
1465 }
1466
1467 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1468 if (S_ISLNK(st.st_mode)) {
1469 strbuf_reset(&sb_contents);
1470 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
1471 if (errno == ENOENT || errno == EINVAL)
1472 /* inconsistent with lstat; retry */
1473 goto stat_ref;
1474 else
1475 goto out;
1476 }
1477 if (starts_with(sb_contents.buf, "refs/") &&
1478 !check_refname_format(sb_contents.buf, 0)) {
1479 strbuf_swap(&sb_contents, referent);
1480 *type |= REF_ISSYMREF;
1481 ret = 0;
1482 goto out;
1483 }
1484 /*
1485 * It doesn't look like a refname; fall through to just
1486 * treating it like a non-symlink, and reading whatever it
1487 * points to.
1488 */
1489 }
1490
1491 /* Is it a directory? */
1492 if (S_ISDIR(st.st_mode)) {
1493 /*
1494 * Even though there is a directory where the loose
1495 * ref is supposed to be, there could still be a
1496 * packed ref:
1497 */
1498 if (resolve_packed_ref(refs, refname, sha1, type)) {
1499 errno = EISDIR;
1500 goto out;
1501 }
1502 ret = 0;
1503 goto out;
1504 }
1505
1506 /*
1507 * Anything else, just open it and try to use it as
1508 * a ref
1509 */
1510 fd = open(path, O_RDONLY);
1511 if (fd < 0) {
1512 if (errno == ENOENT && !S_ISLNK(st.st_mode))
1513 /* inconsistent with lstat; retry */
1514 goto stat_ref;
1515 else
1516 goto out;
1517 }
1518 strbuf_reset(&sb_contents);
1519 if (strbuf_read(&sb_contents, fd, 256) < 0) {
1520 int save_errno = errno;
1521 close(fd);
1522 errno = save_errno;
1523 goto out;
1524 }
1525 close(fd);
1526 strbuf_rtrim(&sb_contents);
1527 buf = sb_contents.buf;
1528 if (starts_with(buf, "ref:")) {
1529 buf += 4;
1530 while (isspace(*buf))
1531 buf++;
1532
1533 strbuf_reset(referent);
1534 strbuf_addstr(referent, buf);
1535 *type |= REF_ISSYMREF;
1536 ret = 0;
1537 goto out;
1538 }
1539
1540 /*
1541 * Please note that FETCH_HEAD has additional
1542 * data after the sha.
1543 */
1544 if (get_sha1_hex(buf, sha1) ||
1545 (buf[40] != '\0' && !isspace(buf[40]))) {
1546 *type |= REF_ISBROKEN;
1547 errno = EINVAL;
1548 goto out;
1549 }
1550
1551 ret = 0;
1552
1553 out:
1554 save_errno = errno;
1555 strbuf_release(&sb_path);
1556 strbuf_release(&sb_contents);
1557 errno = save_errno;
1558 return ret;
1559 }
1560
1561 static void unlock_ref(struct ref_lock *lock)
1562 {
1563 /* Do not free lock->lk -- atexit() still looks at them */
1564 if (lock->lk)
1565 rollback_lock_file(lock->lk);
1566 free(lock->ref_name);
1567 free(lock);
1568 }
1569
1570 /*
1571 * Lock refname, without following symrefs, and set *lock_p to point
1572 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1573 * and type similarly to read_raw_ref().
1574 *
1575 * The caller must verify that refname is a "safe" reference name (in
1576 * the sense of refname_is_safe()) before calling this function.
1577 *
1578 * If the reference doesn't already exist, verify that refname doesn't
1579 * have a D/F conflict with any existing references. extras and skip
1580 * are passed to verify_refname_available_dir() for this check.
1581 *
1582 * If mustexist is not set and the reference is not found or is
1583 * broken, lock the reference anyway but clear sha1.
1584 *
1585 * Return 0 on success. On failure, write an error message to err and
1586 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1587 *
1588 * Implementation note: This function is basically
1589 *
1590 * lock reference
1591 * read_raw_ref()
1592 *
1593 * but it includes a lot more code to
1594 * - Deal with possible races with other processes
1595 * - Avoid calling verify_refname_available_dir() when it can be
1596 * avoided, namely if we were successfully able to read the ref
1597 * - Generate informative error messages in the case of failure
1598 */
1599 static int lock_raw_ref(struct files_ref_store *refs,
1600 const char *refname, int mustexist,
1601 const struct string_list *extras,
1602 const struct string_list *skip,
1603 struct ref_lock **lock_p,
1604 struct strbuf *referent,
1605 unsigned int *type,
1606 struct strbuf *err)
1607 {
1608 struct ref_lock *lock;
1609 struct strbuf ref_file = STRBUF_INIT;
1610 int attempts_remaining = 3;
1611 int ret = TRANSACTION_GENERIC_ERROR;
1612
1613 assert(err);
1614 files_assert_main_repository(refs, "lock_raw_ref");
1615
1616 *type = 0;
1617
1618 /* First lock the file so it can't change out from under us. */
1619
1620 *lock_p = lock = xcalloc(1, sizeof(*lock));
1621
1622 lock->ref_name = xstrdup(refname);
1623 files_ref_path(refs, &ref_file, refname);
1624
1625 retry:
1626 switch (safe_create_leading_directories(ref_file.buf)) {
1627 case SCLD_OK:
1628 break; /* success */
1629 case SCLD_EXISTS:
1630 /*
1631 * Suppose refname is "refs/foo/bar". We just failed
1632 * to create the containing directory, "refs/foo",
1633 * because there was a non-directory in the way. This
1634 * indicates a D/F conflict, probably because of
1635 * another reference such as "refs/foo". There is no
1636 * reason to expect this error to be transitory.
1637 */
1638 if (verify_refname_available(refname, extras, skip, err)) {
1639 if (mustexist) {
1640 /*
1641 * To the user the relevant error is
1642 * that the "mustexist" reference is
1643 * missing:
1644 */
1645 strbuf_reset(err);
1646 strbuf_addf(err, "unable to resolve reference '%s'",
1647 refname);
1648 } else {
1649 /*
1650 * The error message set by
1651 * verify_refname_available_dir() is OK.
1652 */
1653 ret = TRANSACTION_NAME_CONFLICT;
1654 }
1655 } else {
1656 /*
1657 * The file that is in the way isn't a loose
1658 * reference. Report it as a low-level
1659 * failure.
1660 */
1661 strbuf_addf(err, "unable to create lock file %s.lock; "
1662 "non-directory in the way",
1663 ref_file.buf);
1664 }
1665 goto error_return;
1666 case SCLD_VANISHED:
1667 /* Maybe another process was tidying up. Try again. */
1668 if (--attempts_remaining > 0)
1669 goto retry;
1670 /* fall through */
1671 default:
1672 strbuf_addf(err, "unable to create directory for %s",
1673 ref_file.buf);
1674 goto error_return;
1675 }
1676
1677 if (!lock->lk)
1678 lock->lk = xcalloc(1, sizeof(struct lock_file));
1679
1680 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1681 if (errno == ENOENT && --attempts_remaining > 0) {
1682 /*
1683 * Maybe somebody just deleted one of the
1684 * directories leading to ref_file. Try
1685 * again:
1686 */
1687 goto retry;
1688 } else {
1689 unable_to_lock_message(ref_file.buf, errno, err);
1690 goto error_return;
1691 }
1692 }
1693
1694 /*
1695 * Now we hold the lock and can read the reference without
1696 * fear that its value will change.
1697 */
1698
1699 if (files_read_raw_ref(&refs->base, refname,
1700 lock->old_oid.hash, referent, type)) {
1701 if (errno == ENOENT) {
1702 if (mustexist) {
1703 /* Garden variety missing reference. */
1704 strbuf_addf(err, "unable to resolve reference '%s'",
1705 refname);
1706 goto error_return;
1707 } else {
1708 /*
1709 * Reference is missing, but that's OK. We
1710 * know that there is not a conflict with
1711 * another loose reference because
1712 * (supposing that we are trying to lock
1713 * reference "refs/foo/bar"):
1714 *
1715 * - We were successfully able to create
1716 * the lockfile refs/foo/bar.lock, so we
1717 * know there cannot be a loose reference
1718 * named "refs/foo".
1719 *
1720 * - We got ENOENT and not EISDIR, so we
1721 * know that there cannot be a loose
1722 * reference named "refs/foo/bar/baz".
1723 */
1724 }
1725 } else if (errno == EISDIR) {
1726 /*
1727 * There is a directory in the way. It might have
1728 * contained references that have been deleted. If
1729 * we don't require that the reference already
1730 * exists, try to remove the directory so that it
1731 * doesn't cause trouble when we want to rename the
1732 * lockfile into place later.
1733 */
1734 if (mustexist) {
1735 /* Garden variety missing reference. */
1736 strbuf_addf(err, "unable to resolve reference '%s'",
1737 refname);
1738 goto error_return;
1739 } else if (remove_dir_recursively(&ref_file,
1740 REMOVE_DIR_EMPTY_ONLY)) {
1741 if (verify_refname_available_dir(
1742 refname, extras, skip,
1743 get_loose_refs(refs),
1744 err)) {
1745 /*
1746 * The error message set by
1747 * verify_refname_available() is OK.
1748 */
1749 ret = TRANSACTION_NAME_CONFLICT;
1750 goto error_return;
1751 } else {
1752 /*
1753 * We can't delete the directory,
1754 * but we also don't know of any
1755 * references that it should
1756 * contain.
1757 */
1758 strbuf_addf(err, "there is a non-empty directory '%s' "
1759 "blocking reference '%s'",
1760 ref_file.buf, refname);
1761 goto error_return;
1762 }
1763 }
1764 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1765 strbuf_addf(err, "unable to resolve reference '%s': "
1766 "reference broken", refname);
1767 goto error_return;
1768 } else {
1769 strbuf_addf(err, "unable to resolve reference '%s': %s",
1770 refname, strerror(errno));
1771 goto error_return;
1772 }
1773
1774 /*
1775 * If the ref did not exist and we are creating it,
1776 * make sure there is no existing packed ref whose
1777 * name begins with our refname, nor a packed ref
1778 * whose name is a proper prefix of our refname.
1779 */
1780 if (verify_refname_available_dir(
1781 refname, extras, skip,
1782 get_packed_refs(refs),
1783 err)) {
1784 goto error_return;
1785 }
1786 }
1787
1788 ret = 0;
1789 goto out;
1790
1791 error_return:
1792 unlock_ref(lock);
1793 *lock_p = NULL;
1794
1795 out:
1796 strbuf_release(&ref_file);
1797 return ret;
1798 }
1799
1800 /*
1801 * Peel the entry (if possible) and return its new peel_status. If
1802 * repeel is true, re-peel the entry even if there is an old peeled
1803 * value that is already stored in it.
1804 *
1805 * It is OK to call this function with a packed reference entry that
1806 * might be stale and might even refer to an object that has since
1807 * been garbage-collected. In such a case, if the entry has
1808 * REF_KNOWS_PEELED then leave the status unchanged and return
1809 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1810 */
1811 static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1812 {
1813 enum peel_status status;
1814
1815 if (entry->flag & REF_KNOWS_PEELED) {
1816 if (repeel) {
1817 entry->flag &= ~REF_KNOWS_PEELED;
1818 oidclr(&entry->u.value.peeled);
1819 } else {
1820 return is_null_oid(&entry->u.value.peeled) ?
1821 PEEL_NON_TAG : PEEL_PEELED;
1822 }
1823 }
1824 if (entry->flag & REF_ISBROKEN)
1825 return PEEL_BROKEN;
1826 if (entry->flag & REF_ISSYMREF)
1827 return PEEL_IS_SYMREF;
1828
1829 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1830 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1831 entry->flag |= REF_KNOWS_PEELED;
1832 return status;
1833 }
1834
1835 static int files_peel_ref(struct ref_store *ref_store,
1836 const char *refname, unsigned char *sha1)
1837 {
1838 struct files_ref_store *refs = files_downcast(ref_store, 0, "peel_ref");
1839 int flag;
1840 unsigned char base[20];
1841
1842 if (current_ref_iter && current_ref_iter->refname == refname) {
1843 struct object_id peeled;
1844
1845 if (ref_iterator_peel(current_ref_iter, &peeled))
1846 return -1;
1847 hashcpy(sha1, peeled.hash);
1848 return 0;
1849 }
1850
1851 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1852 return -1;
1853
1854 /*
1855 * If the reference is packed, read its ref_entry from the
1856 * cache in the hope that we already know its peeled value.
1857 * We only try this optimization on packed references because
1858 * (a) forcing the filling of the loose reference cache could
1859 * be expensive and (b) loose references anyway usually do not
1860 * have REF_KNOWS_PEELED.
1861 */
1862 if (flag & REF_ISPACKED) {
1863 struct ref_entry *r = get_packed_ref(refs, refname);
1864 if (r) {
1865 if (peel_entry(r, 0))
1866 return -1;
1867 hashcpy(sha1, r->u.value.peeled.hash);
1868 return 0;
1869 }
1870 }
1871
1872 return peel_object(base, sha1);
1873 }
1874
1875 struct files_ref_iterator {
1876 struct ref_iterator base;
1877
1878 struct packed_ref_cache *packed_ref_cache;
1879 struct ref_iterator *iter0;
1880 unsigned int flags;
1881 };
1882
1883 static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
1884 {
1885 struct files_ref_iterator *iter =
1886 (struct files_ref_iterator *)ref_iterator;
1887 int ok;
1888
1889 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
1890 if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
1891 ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
1892 continue;
1893
1894 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
1895 !ref_resolves_to_object(iter->iter0->refname,
1896 iter->iter0->oid,
1897 iter->iter0->flags))
1898 continue;
1899
1900 iter->base.refname = iter->iter0->refname;
1901 iter->base.oid = iter->iter0->oid;
1902 iter->base.flags = iter->iter0->flags;
1903 return ITER_OK;
1904 }
1905
1906 iter->iter0 = NULL;
1907 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
1908 ok = ITER_ERROR;
1909
1910 return ok;
1911 }
1912
1913 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
1914 struct object_id *peeled)
1915 {
1916 struct files_ref_iterator *iter =
1917 (struct files_ref_iterator *)ref_iterator;
1918
1919 return ref_iterator_peel(iter->iter0, peeled);
1920 }
1921
1922 static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
1923 {
1924 struct files_ref_iterator *iter =
1925 (struct files_ref_iterator *)ref_iterator;
1926 int ok = ITER_DONE;
1927
1928 if (iter->iter0)
1929 ok = ref_iterator_abort(iter->iter0);
1930
1931 release_packed_ref_cache(iter->packed_ref_cache);
1932 base_ref_iterator_free(ref_iterator);
1933 return ok;
1934 }
1935
1936 static struct ref_iterator_vtable files_ref_iterator_vtable = {
1937 files_ref_iterator_advance,
1938 files_ref_iterator_peel,
1939 files_ref_iterator_abort
1940 };
1941
1942 static struct ref_iterator *files_ref_iterator_begin(
1943 struct ref_store *ref_store,
1944 const char *prefix, unsigned int flags)
1945 {
1946 struct files_ref_store *refs =
1947 files_downcast(ref_store, 1, "ref_iterator_begin");
1948 struct ref_dir *loose_dir, *packed_dir;
1949 struct ref_iterator *loose_iter, *packed_iter;
1950 struct files_ref_iterator *iter;
1951 struct ref_iterator *ref_iterator;
1952
1953 if (ref_paranoia < 0)
1954 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1955 if (ref_paranoia)
1956 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1957
1958 iter = xcalloc(1, sizeof(*iter));
1959 ref_iterator = &iter->base;
1960 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
1961
1962 /*
1963 * We must make sure that all loose refs are read before
1964 * accessing the packed-refs file; this avoids a race
1965 * condition if loose refs are migrated to the packed-refs
1966 * file by a simultaneous process, but our in-memory view is
1967 * from before the migration. We ensure this as follows:
1968 * First, we call prime_ref_dir(), which pre-reads the loose
1969 * references for the subtree into the cache. (If they've
1970 * already been read, that's OK; we only need to guarantee
1971 * that they're read before the packed refs, not *how much*
1972 * before.) After that, we call get_packed_ref_cache(), which
1973 * internally checks whether the packed-ref cache is up to
1974 * date with what is on disk, and re-reads it if not.
1975 */
1976
1977 loose_dir = get_loose_refs(refs);
1978
1979 if (prefix && *prefix)
1980 loose_dir = find_containing_dir(loose_dir, prefix, 0);
1981
1982 if (loose_dir) {
1983 prime_ref_dir(loose_dir);
1984 loose_iter = cache_ref_iterator_begin(loose_dir);
1985 } else {
1986 /* There's nothing to iterate over. */
1987 loose_iter = empty_ref_iterator_begin();
1988 }
1989
1990 iter->packed_ref_cache = get_packed_ref_cache(refs);
1991 acquire_packed_ref_cache(iter->packed_ref_cache);
1992 packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
1993
1994 if (prefix && *prefix)
1995 packed_dir = find_containing_dir(packed_dir, prefix, 0);
1996
1997 if (packed_dir) {
1998 packed_iter = cache_ref_iterator_begin(packed_dir);
1999 } else {
2000 /* There's nothing to iterate over. */
2001 packed_iter = empty_ref_iterator_begin();
2002 }
2003
2004 iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
2005 iter->flags = flags;
2006
2007 return ref_iterator;
2008 }
2009
2010 /*
2011 * Verify that the reference locked by lock has the value old_sha1.
2012 * Fail if the reference doesn't exist and mustexist is set. Return 0
2013 * on success. On error, write an error message to err, set errno, and
2014 * return a negative value.
2015 */
2016 static int verify_lock(struct ref_lock *lock,
2017 const unsigned char *old_sha1, int mustexist,
2018 struct strbuf *err)
2019 {
2020 assert(err);
2021
2022 if (read_ref_full(lock->ref_name,
2023 mustexist ? RESOLVE_REF_READING : 0,
2024 lock->old_oid.hash, NULL)) {
2025 if (old_sha1) {
2026 int save_errno = errno;
2027 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
2028 errno = save_errno;
2029 return -1;
2030 } else {
2031 oidclr(&lock->old_oid);
2032 return 0;
2033 }
2034 }
2035 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
2036 strbuf_addf(err, "ref '%s' is at %s but expected %s",
2037 lock->ref_name,
2038 oid_to_hex(&lock->old_oid),
2039 sha1_to_hex(old_sha1));
2040 errno = EBUSY;
2041 return -1;
2042 }
2043 return 0;
2044 }
2045
2046 static int remove_empty_directories(struct strbuf *path)
2047 {
2048 /*
2049 * we want to create a file but there is a directory there;
2050 * if that is an empty directory (or a directory that contains
2051 * only empty directories), remove them.
2052 */
2053 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
2054 }
2055
2056 static int create_reflock(const char *path, void *cb)
2057 {
2058 struct lock_file *lk = cb;
2059
2060 return hold_lock_file_for_update(lk, path, LOCK_NO_DEREF) < 0 ? -1 : 0;
2061 }
2062
2063 /*
2064 * Locks a ref returning the lock on success and NULL on failure.
2065 * On failure errno is set to something meaningful.
2066 */
2067 static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
2068 const char *refname,
2069 const unsigned char *old_sha1,
2070 const struct string_list *extras,
2071 const struct string_list *skip,
2072 unsigned int flags, int *type,
2073 struct strbuf *err)
2074 {
2075 struct strbuf ref_file = STRBUF_INIT;
2076 struct ref_lock *lock;
2077 int last_errno = 0;
2078 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
2079 int resolve_flags = RESOLVE_REF_NO_RECURSE;
2080 int resolved;
2081
2082 files_assert_main_repository(refs, "lock_ref_sha1_basic");
2083 assert(err);
2084
2085 lock = xcalloc(1, sizeof(struct ref_lock));
2086
2087 if (mustexist)
2088 resolve_flags |= RESOLVE_REF_READING;
2089 if (flags & REF_DELETING)
2090 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
2091
2092 files_ref_path(refs, &ref_file, refname);
2093 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2094 lock->old_oid.hash, type);
2095 if (!resolved && errno == EISDIR) {
2096 /*
2097 * we are trying to lock foo but we used to
2098 * have foo/bar which now does not exist;
2099 * it is normal for the empty directory 'foo'
2100 * to remain.
2101 */
2102 if (remove_empty_directories(&ref_file)) {
2103 last_errno = errno;
2104 if (!verify_refname_available_dir(
2105 refname, extras, skip,
2106 get_loose_refs(refs), err))
2107 strbuf_addf(err, "there are still refs under '%s'",
2108 refname);
2109 goto error_return;
2110 }
2111 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2112 lock->old_oid.hash, type);
2113 }
2114 if (!resolved) {
2115 last_errno = errno;
2116 if (last_errno != ENOTDIR ||
2117 !verify_refname_available_dir(
2118 refname, extras, skip,
2119 get_loose_refs(refs), err))
2120 strbuf_addf(err, "unable to resolve reference '%s': %s",
2121 refname, strerror(last_errno));
2122
2123 goto error_return;
2124 }
2125
2126 /*
2127 * If the ref did not exist and we are creating it, make sure
2128 * there is no existing packed ref whose name begins with our
2129 * refname, nor a packed ref whose name is a proper prefix of
2130 * our refname.
2131 */
2132 if (is_null_oid(&lock->old_oid) &&
2133 verify_refname_available_dir(refname, extras, skip,
2134 get_packed_refs(refs),
2135 err)) {
2136 last_errno = ENOTDIR;
2137 goto error_return;
2138 }
2139
2140 lock->lk = xcalloc(1, sizeof(struct lock_file));
2141
2142 lock->ref_name = xstrdup(refname);
2143
2144 if (raceproof_create_file(ref_file.buf, create_reflock, lock->lk)) {
2145 last_errno = errno;
2146 unable_to_lock_message(ref_file.buf, errno, err);
2147 goto error_return;
2148 }
2149
2150 if (verify_lock(lock, old_sha1, mustexist, err)) {
2151 last_errno = errno;
2152 goto error_return;
2153 }
2154 goto out;
2155
2156 error_return:
2157 unlock_ref(lock);
2158 lock = NULL;
2159
2160 out:
2161 strbuf_release(&ref_file);
2162 errno = last_errno;
2163 return lock;
2164 }
2165
2166 /*
2167 * Write an entry to the packed-refs file for the specified refname.
2168 * If peeled is non-NULL, write it as the entry's peeled value.
2169 */
2170 static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2171 unsigned char *peeled)
2172 {
2173 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2174 if (peeled)
2175 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2176 }
2177
2178 /*
2179 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2180 */
2181 static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2182 {
2183 enum peel_status peel_status = peel_entry(entry, 0);
2184
2185 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2186 error("internal error: %s is not a valid packed reference!",
2187 entry->name);
2188 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2189 peel_status == PEEL_PEELED ?
2190 entry->u.value.peeled.hash : NULL);
2191 return 0;
2192 }
2193
2194 /*
2195 * Lock the packed-refs file for writing. Flags is passed to
2196 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2197 * errno appropriately and return a nonzero value.
2198 */
2199 static int lock_packed_refs(struct files_ref_store *refs, int flags)
2200 {
2201 static int timeout_configured = 0;
2202 static int timeout_value = 1000;
2203 struct packed_ref_cache *packed_ref_cache;
2204
2205 files_assert_main_repository(refs, "lock_packed_refs");
2206
2207 if (!timeout_configured) {
2208 git_config_get_int("core.packedrefstimeout", &timeout_value);
2209 timeout_configured = 1;
2210 }
2211
2212 if (hold_lock_file_for_update_timeout(
2213 &packlock, files_packed_refs_path(refs),
2214 flags, timeout_value) < 0)
2215 return -1;
2216 /*
2217 * Get the current packed-refs while holding the lock. If the
2218 * packed-refs file has been modified since we last read it,
2219 * this will automatically invalidate the cache and re-read
2220 * the packed-refs file.
2221 */
2222 packed_ref_cache = get_packed_ref_cache(refs);
2223 packed_ref_cache->lock = &packlock;
2224 /* Increment the reference count to prevent it from being freed: */
2225 acquire_packed_ref_cache(packed_ref_cache);
2226 return 0;
2227 }
2228
2229 /*
2230 * Write the current version of the packed refs cache from memory to
2231 * disk. The packed-refs file must already be locked for writing (see
2232 * lock_packed_refs()). Return zero on success. On errors, set errno
2233 * and return a nonzero value
2234 */
2235 static int commit_packed_refs(struct files_ref_store *refs)
2236 {
2237 struct packed_ref_cache *packed_ref_cache =
2238 get_packed_ref_cache(refs);
2239 int error = 0;
2240 int save_errno = 0;
2241 FILE *out;
2242
2243 files_assert_main_repository(refs, "commit_packed_refs");
2244
2245 if (!packed_ref_cache->lock)
2246 die("internal error: packed-refs not locked");
2247
2248 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2249 if (!out)
2250 die_errno("unable to fdopen packed-refs descriptor");
2251
2252 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2253 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2254 0, write_packed_entry_fn, out);
2255
2256 if (commit_lock_file(packed_ref_cache->lock)) {
2257 save_errno = errno;
2258 error = -1;
2259 }
2260 packed_ref_cache->lock = NULL;
2261 release_packed_ref_cache(packed_ref_cache);
2262 errno = save_errno;
2263 return error;
2264 }
2265
2266 /*
2267 * Rollback the lockfile for the packed-refs file, and discard the
2268 * in-memory packed reference cache. (The packed-refs file will be
2269 * read anew if it is needed again after this function is called.)
2270 */
2271 static void rollback_packed_refs(struct files_ref_store *refs)
2272 {
2273 struct packed_ref_cache *packed_ref_cache =
2274 get_packed_ref_cache(refs);
2275
2276 files_assert_main_repository(refs, "rollback_packed_refs");
2277
2278 if (!packed_ref_cache->lock)
2279 die("internal error: packed-refs not locked");
2280 rollback_lock_file(packed_ref_cache->lock);
2281 packed_ref_cache->lock = NULL;
2282 release_packed_ref_cache(packed_ref_cache);
2283 clear_packed_ref_cache(refs);
2284 }
2285
2286 struct ref_to_prune {
2287 struct ref_to_prune *next;
2288 unsigned char sha1[20];
2289 char name[FLEX_ARRAY];
2290 };
2291
2292 struct pack_refs_cb_data {
2293 unsigned int flags;
2294 struct ref_dir *packed_refs;
2295 struct ref_to_prune *ref_to_prune;
2296 };
2297
2298 /*
2299 * An each_ref_entry_fn that is run over loose references only. If
2300 * the loose reference can be packed, add an entry in the packed ref
2301 * cache. If the reference should be pruned, also add it to
2302 * ref_to_prune in the pack_refs_cb_data.
2303 */
2304 static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2305 {
2306 struct pack_refs_cb_data *cb = cb_data;
2307 enum peel_status peel_status;
2308 struct ref_entry *packed_entry;
2309 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2310
2311 /* Do not pack per-worktree refs: */
2312 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2313 return 0;
2314
2315 /* ALWAYS pack tags */
2316 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2317 return 0;
2318
2319 /* Do not pack symbolic or broken refs: */
2320 if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
2321 return 0;
2322
2323 /* Add a packed ref cache entry equivalent to the loose entry. */
2324 peel_status = peel_entry(entry, 1);
2325 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2326 die("internal error peeling reference %s (%s)",
2327 entry->name, oid_to_hex(&entry->u.value.oid));
2328 packed_entry = find_ref(cb->packed_refs, entry->name);
2329 if (packed_entry) {
2330 /* Overwrite existing packed entry with info from loose entry */
2331 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2332 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2333 } else {
2334 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2335 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2336 add_ref(cb->packed_refs, packed_entry);
2337 }
2338 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2339
2340 /* Schedule the loose reference for pruning if requested. */
2341 if ((cb->flags & PACK_REFS_PRUNE)) {
2342 struct ref_to_prune *n;
2343 FLEX_ALLOC_STR(n, name, entry->name);
2344 hashcpy(n->sha1, entry->u.value.oid.hash);
2345 n->next = cb->ref_to_prune;
2346 cb->ref_to_prune = n;
2347 }
2348 return 0;
2349 }
2350
2351 enum {
2352 REMOVE_EMPTY_PARENTS_REF = 0x01,
2353 REMOVE_EMPTY_PARENTS_REFLOG = 0x02
2354 };
2355
2356 /*
2357 * Remove empty parent directories associated with the specified
2358 * reference and/or its reflog, but spare [logs/]refs/ and immediate
2359 * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
2360 * REMOVE_EMPTY_PARENTS_REFLOG.
2361 */
2362 static void try_remove_empty_parents(struct files_ref_store *refs,
2363 const char *refname,
2364 unsigned int flags)
2365 {
2366 struct strbuf buf = STRBUF_INIT;
2367 struct strbuf sb = STRBUF_INIT;
2368 char *p, *q;
2369 int i;
2370
2371 strbuf_addstr(&buf, refname);
2372 p = buf.buf;
2373 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2374 while (*p && *p != '/')
2375 p++;
2376 /* tolerate duplicate slashes; see check_refname_format() */
2377 while (*p == '/')
2378 p++;
2379 }
2380 q = buf.buf + buf.len;
2381 while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
2382 while (q > p && *q != '/')
2383 q--;
2384 while (q > p && *(q-1) == '/')
2385 q--;
2386 if (q == p)
2387 break;
2388 strbuf_setlen(&buf, q - buf.buf);
2389
2390 strbuf_reset(&sb);
2391 files_ref_path(refs, &sb, buf.buf);
2392 if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
2393 flags &= ~REMOVE_EMPTY_PARENTS_REF;
2394
2395 strbuf_reset(&sb);
2396 files_reflog_path(refs, &sb, buf.buf);
2397 if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
2398 flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
2399 }
2400 strbuf_release(&buf);
2401 strbuf_release(&sb);
2402 }
2403
2404 /* make sure nobody touched the ref, and unlink */
2405 static void prune_ref(struct ref_to_prune *r)
2406 {
2407 struct ref_transaction *transaction;
2408 struct strbuf err = STRBUF_INIT;
2409
2410 if (check_refname_format(r->name, 0))
2411 return;
2412
2413 transaction = ref_transaction_begin(&err);
2414 if (!transaction ||
2415 ref_transaction_delete(transaction, r->name, r->sha1,
2416 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
2417 ref_transaction_commit(transaction, &err)) {
2418 ref_transaction_free(transaction);
2419 error("%s", err.buf);
2420 strbuf_release(&err);
2421 return;
2422 }
2423 ref_transaction_free(transaction);
2424 strbuf_release(&err);
2425 }
2426
2427 static void prune_refs(struct ref_to_prune *r)
2428 {
2429 while (r) {
2430 prune_ref(r);
2431 r = r->next;
2432 }
2433 }
2434
2435 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
2436 {
2437 struct files_ref_store *refs =
2438 files_downcast(ref_store, 0, "pack_refs");
2439 struct pack_refs_cb_data cbdata;
2440
2441 memset(&cbdata, 0, sizeof(cbdata));
2442 cbdata.flags = flags;
2443
2444 lock_packed_refs(refs, LOCK_DIE_ON_ERROR);
2445 cbdata.packed_refs = get_packed_refs(refs);
2446
2447 do_for_each_entry_in_dir(get_loose_refs(refs), 0,
2448 pack_if_possible_fn, &cbdata);
2449
2450 if (commit_packed_refs(refs))
2451 die_errno("unable to overwrite old ref-pack file");
2452
2453 prune_refs(cbdata.ref_to_prune);
2454 return 0;
2455 }
2456
2457 /*
2458 * Rewrite the packed-refs file, omitting any refs listed in
2459 * 'refnames'. On error, leave packed-refs unchanged, write an error
2460 * message to 'err', and return a nonzero value.
2461 *
2462 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2463 */
2464 static int repack_without_refs(struct files_ref_store *refs,
2465 struct string_list *refnames, struct strbuf *err)
2466 {
2467 struct ref_dir *packed;
2468 struct string_list_item *refname;
2469 int ret, needs_repacking = 0, removed = 0;
2470
2471 files_assert_main_repository(refs, "repack_without_refs");
2472 assert(err);
2473
2474 /* Look for a packed ref */
2475 for_each_string_list_item(refname, refnames) {
2476 if (get_packed_ref(refs, refname->string)) {
2477 needs_repacking = 1;
2478 break;
2479 }
2480 }
2481
2482 /* Avoid locking if we have nothing to do */
2483 if (!needs_repacking)
2484 return 0; /* no refname exists in packed refs */
2485
2486 if (lock_packed_refs(refs, 0)) {
2487 unable_to_lock_message(files_packed_refs_path(refs), errno, err);
2488 return -1;
2489 }
2490 packed = get_packed_refs(refs);
2491
2492 /* Remove refnames from the cache */
2493 for_each_string_list_item(refname, refnames)
2494 if (remove_entry(packed, refname->string) != -1)
2495 removed = 1;
2496 if (!removed) {
2497 /*
2498 * All packed entries disappeared while we were
2499 * acquiring the lock.
2500 */
2501 rollback_packed_refs(refs);
2502 return 0;
2503 }
2504
2505 /* Write what remains */
2506 ret = commit_packed_refs(refs);
2507 if (ret)
2508 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2509 strerror(errno));
2510 return ret;
2511 }
2512
2513 static int files_delete_refs(struct ref_store *ref_store,
2514 struct string_list *refnames, unsigned int flags)
2515 {
2516 struct files_ref_store *refs =
2517 files_downcast(ref_store, 0, "delete_refs");
2518 struct strbuf err = STRBUF_INIT;
2519 int i, result = 0;
2520
2521 if (!refnames->nr)
2522 return 0;
2523
2524 result = repack_without_refs(refs, refnames, &err);
2525 if (result) {
2526 /*
2527 * If we failed to rewrite the packed-refs file, then
2528 * it is unsafe to try to remove loose refs, because
2529 * doing so might expose an obsolete packed value for
2530 * a reference that might even point at an object that
2531 * has been garbage collected.
2532 */
2533 if (refnames->nr == 1)
2534 error(_("could not delete reference %s: %s"),
2535 refnames->items[0].string, err.buf);
2536 else
2537 error(_("could not delete references: %s"), err.buf);
2538
2539 goto out;
2540 }
2541
2542 for (i = 0; i < refnames->nr; i++) {
2543 const char *refname = refnames->items[i].string;
2544
2545 if (delete_ref(NULL, refname, NULL, flags))
2546 result |= error(_("could not remove reference %s"), refname);
2547 }
2548
2549 out:
2550 strbuf_release(&err);
2551 return result;
2552 }
2553
2554 /*
2555 * People using contrib's git-new-workdir have .git/logs/refs ->
2556 * /some/other/path/.git/logs/refs, and that may live on another device.
2557 *
2558 * IOW, to avoid cross device rename errors, the temporary renamed log must
2559 * live into logs/refs.
2560 */
2561 #define TMP_RENAMED_LOG "refs/.tmp-renamed-log"
2562
2563 struct rename_cb {
2564 const char *tmp_renamed_log;
2565 int true_errno;
2566 };
2567
2568 static int rename_tmp_log_callback(const char *path, void *cb_data)
2569 {
2570 struct rename_cb *cb = cb_data;
2571
2572 if (rename(cb->tmp_renamed_log, path)) {
2573 /*
2574 * rename(a, b) when b is an existing directory ought
2575 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
2576 * Sheesh. Record the true errno for error reporting,
2577 * but report EISDIR to raceproof_create_file() so
2578 * that it knows to retry.
2579 */
2580 cb->true_errno = errno;
2581 if (errno == ENOTDIR)
2582 errno = EISDIR;
2583 return -1;
2584 } else {
2585 return 0;
2586 }
2587 }
2588
2589 static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
2590 {
2591 struct strbuf path = STRBUF_INIT;
2592 struct strbuf tmp = STRBUF_INIT;
2593 struct rename_cb cb;
2594 int ret;
2595
2596 files_reflog_path(refs, &path, newrefname);
2597 files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
2598 cb.tmp_renamed_log = tmp.buf;
2599 ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
2600 if (ret) {
2601 if (errno == EISDIR)
2602 error("directory not empty: %s", path.buf);
2603 else
2604 error("unable to move logfile %s to %s: %s",
2605 tmp.buf, path.buf,
2606 strerror(cb.true_errno));
2607 }
2608
2609 strbuf_release(&path);
2610 strbuf_release(&tmp);
2611 return ret;
2612 }
2613
2614 static int files_verify_refname_available(struct ref_store *ref_store,
2615 const char *newname,
2616 const struct string_list *extras,
2617 const struct string_list *skip,
2618 struct strbuf *err)
2619 {
2620 struct files_ref_store *refs =
2621 files_downcast(ref_store, 1, "verify_refname_available");
2622 struct ref_dir *packed_refs = get_packed_refs(refs);
2623 struct ref_dir *loose_refs = get_loose_refs(refs);
2624
2625 if (verify_refname_available_dir(newname, extras, skip,
2626 packed_refs, err) ||
2627 verify_refname_available_dir(newname, extras, skip,
2628 loose_refs, err))
2629 return -1;
2630
2631 return 0;
2632 }
2633
2634 static int write_ref_to_lockfile(struct ref_lock *lock,
2635 const unsigned char *sha1, struct strbuf *err);
2636 static int commit_ref_update(struct files_ref_store *refs,
2637 struct ref_lock *lock,
2638 const unsigned char *sha1, const char *logmsg,
2639 struct strbuf *err);
2640
2641 static int files_rename_ref(struct ref_store *ref_store,
2642 const char *oldrefname, const char *newrefname,
2643 const char *logmsg)
2644 {
2645 struct files_ref_store *refs =
2646 files_downcast(ref_store, 0, "rename_ref");
2647 unsigned char sha1[20], orig_sha1[20];
2648 int flag = 0, logmoved = 0;
2649 struct ref_lock *lock;
2650 struct stat loginfo;
2651 struct strbuf sb_oldref = STRBUF_INIT;
2652 struct strbuf sb_newref = STRBUF_INIT;
2653 struct strbuf tmp_renamed_log = STRBUF_INIT;
2654 int log, ret;
2655 struct strbuf err = STRBUF_INIT;
2656
2657 files_reflog_path(refs, &sb_oldref, oldrefname);
2658 files_reflog_path(refs, &sb_newref, newrefname);
2659 files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
2660
2661 log = !lstat(sb_oldref.buf, &loginfo);
2662 if (log && S_ISLNK(loginfo.st_mode)) {
2663 ret = error("reflog for %s is a symlink", oldrefname);
2664 goto out;
2665 }
2666
2667 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2668 orig_sha1, &flag)) {
2669 ret = error("refname %s not found", oldrefname);
2670 goto out;
2671 }
2672
2673 if (flag & REF_ISSYMREF) {
2674 ret = error("refname %s is a symbolic ref, renaming it is not supported",
2675 oldrefname);
2676 goto out;
2677 }
2678 if (!rename_ref_available(oldrefname, newrefname)) {
2679 ret = 1;
2680 goto out;
2681 }
2682
2683 if (log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
2684 ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
2685 oldrefname, strerror(errno));
2686 goto out;
2687 }
2688
2689 if (delete_ref(logmsg, oldrefname, orig_sha1, REF_NODEREF)) {
2690 error("unable to delete old %s", oldrefname);
2691 goto rollback;
2692 }
2693
2694 /*
2695 * Since we are doing a shallow lookup, sha1 is not the
2696 * correct value to pass to delete_ref as old_sha1. But that
2697 * doesn't matter, because an old_sha1 check wouldn't add to
2698 * the safety anyway; we want to delete the reference whatever
2699 * its current value.
2700 */
2701 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2702 sha1, NULL) &&
2703 delete_ref(NULL, newrefname, NULL, REF_NODEREF)) {
2704 if (errno == EISDIR) {
2705 struct strbuf path = STRBUF_INIT;
2706 int result;
2707
2708 files_ref_path(refs, &path, newrefname);
2709 result = remove_empty_directories(&path);
2710 strbuf_release(&path);
2711
2712 if (result) {
2713 error("Directory not empty: %s", newrefname);
2714 goto rollback;
2715 }
2716 } else {
2717 error("unable to delete existing %s", newrefname);
2718 goto rollback;
2719 }
2720 }
2721
2722 if (log && rename_tmp_log(refs, newrefname))
2723 goto rollback;
2724
2725 logmoved = log;
2726
2727 lock = lock_ref_sha1_basic(refs, newrefname, NULL, NULL, NULL,
2728 REF_NODEREF, NULL, &err);
2729 if (!lock) {
2730 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2731 strbuf_release(&err);
2732 goto rollback;
2733 }
2734 hashcpy(lock->old_oid.hash, orig_sha1);
2735
2736 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2737 commit_ref_update(refs, lock, orig_sha1, logmsg, &err)) {
2738 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2739 strbuf_release(&err);
2740 goto rollback;
2741 }
2742
2743 ret = 0;
2744 goto out;
2745
2746 rollback:
2747 lock = lock_ref_sha1_basic(refs, oldrefname, NULL, NULL, NULL,
2748 REF_NODEREF, NULL, &err);
2749 if (!lock) {
2750 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2751 strbuf_release(&err);
2752 goto rollbacklog;
2753 }
2754
2755 flag = log_all_ref_updates;
2756 log_all_ref_updates = LOG_REFS_NONE;
2757 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
2758 commit_ref_update(refs, lock, orig_sha1, NULL, &err)) {
2759 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2760 strbuf_release(&err);
2761 }
2762 log_all_ref_updates = flag;
2763
2764 rollbacklog:
2765 if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
2766 error("unable to restore logfile %s from %s: %s",
2767 oldrefname, newrefname, strerror(errno));
2768 if (!logmoved && log &&
2769 rename(tmp_renamed_log.buf, sb_oldref.buf))
2770 error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
2771 oldrefname, strerror(errno));
2772 ret = 1;
2773 out:
2774 strbuf_release(&sb_newref);
2775 strbuf_release(&sb_oldref);
2776 strbuf_release(&tmp_renamed_log);
2777
2778 return ret;
2779 }
2780
2781 static int close_ref(struct ref_lock *lock)
2782 {
2783 if (close_lock_file(lock->lk))
2784 return -1;
2785 return 0;
2786 }
2787
2788 static int commit_ref(struct ref_lock *lock)
2789 {
2790 char *path = get_locked_file_path(lock->lk);
2791 struct stat st;
2792
2793 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2794 /*
2795 * There is a directory at the path we want to rename
2796 * the lockfile to. Hopefully it is empty; try to
2797 * delete it.
2798 */
2799 size_t len = strlen(path);
2800 struct strbuf sb_path = STRBUF_INIT;
2801
2802 strbuf_attach(&sb_path, path, len, len);
2803
2804 /*
2805 * If this fails, commit_lock_file() will also fail
2806 * and will report the problem.
2807 */
2808 remove_empty_directories(&sb_path);
2809 strbuf_release(&sb_path);
2810 } else {
2811 free(path);
2812 }
2813
2814 if (commit_lock_file(lock->lk))
2815 return -1;
2816 return 0;
2817 }
2818
2819 static int open_or_create_logfile(const char *path, void *cb)
2820 {
2821 int *fd = cb;
2822
2823 *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
2824 return (*fd < 0) ? -1 : 0;
2825 }
2826
2827 /*
2828 * Create a reflog for a ref. If force_create = 0, only create the
2829 * reflog for certain refs (those for which should_autocreate_reflog
2830 * returns non-zero). Otherwise, create it regardless of the reference
2831 * name. If the logfile already existed or was created, return 0 and
2832 * set *logfd to the file descriptor opened for appending to the file.
2833 * If no logfile exists and we decided not to create one, return 0 and
2834 * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
2835 * return -1.
2836 */
2837 static int log_ref_setup(struct files_ref_store *refs,
2838 const char *refname, int force_create,
2839 int *logfd, struct strbuf *err)
2840 {
2841 struct strbuf logfile_sb = STRBUF_INIT;
2842 char *logfile;
2843
2844 files_reflog_path(refs, &logfile_sb, refname);
2845 logfile = strbuf_detach(&logfile_sb, NULL);
2846
2847 if (force_create || should_autocreate_reflog(refname)) {
2848 if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
2849 if (errno == ENOENT)
2850 strbuf_addf(err, "unable to create directory for '%s': "
2851 "%s", logfile, strerror(errno));
2852 else if (errno == EISDIR)
2853 strbuf_addf(err, "there are still logs under '%s'",
2854 logfile);
2855 else
2856 strbuf_addf(err, "unable to append to '%s': %s",
2857 logfile, strerror(errno));
2858
2859 goto error;
2860 }
2861 } else {
2862 *logfd = open(logfile, O_APPEND | O_WRONLY, 0666);
2863 if (*logfd < 0) {
2864 if (errno == ENOENT || errno == EISDIR) {
2865 /*
2866 * The logfile doesn't already exist,
2867 * but that is not an error; it only
2868 * means that we won't write log
2869 * entries to it.
2870 */
2871 ;
2872 } else {
2873 strbuf_addf(err, "unable to append to '%s': %s",
2874 logfile, strerror(errno));
2875 goto error;
2876 }
2877 }
2878 }
2879
2880 if (*logfd >= 0)
2881 adjust_shared_perm(logfile);
2882
2883 free(logfile);
2884 return 0;
2885
2886 error:
2887 free(logfile);
2888 return -1;
2889 }
2890
2891 static int files_create_reflog(struct ref_store *ref_store,
2892 const char *refname, int force_create,
2893 struct strbuf *err)
2894 {
2895 struct files_ref_store *refs =
2896 files_downcast(ref_store, 0, "create_reflog");
2897 int fd;
2898
2899 if (log_ref_setup(refs, refname, force_create, &fd, err))
2900 return -1;
2901
2902 if (fd >= 0)
2903 close(fd);
2904
2905 return 0;
2906 }
2907
2908 static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2909 const unsigned char *new_sha1,
2910 const char *committer, const char *msg)
2911 {
2912 int msglen, written;
2913 unsigned maxlen, len;
2914 char *logrec;
2915
2916 msglen = msg ? strlen(msg) : 0;
2917 maxlen = strlen(committer) + msglen + 100;
2918 logrec = xmalloc(maxlen);
2919 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2920 sha1_to_hex(old_sha1),
2921 sha1_to_hex(new_sha1),
2922 committer);
2923 if (msglen)
2924 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2925
2926 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2927 free(logrec);
2928 if (written != len)
2929 return -1;
2930
2931 return 0;
2932 }
2933
2934 static int files_log_ref_write(struct files_ref_store *refs,
2935 const char *refname, const unsigned char *old_sha1,
2936 const unsigned char *new_sha1, const char *msg,
2937 int flags, struct strbuf *err)
2938 {
2939 int logfd, result;
2940
2941 if (log_all_ref_updates == LOG_REFS_UNSET)
2942 log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
2943
2944 result = log_ref_setup(refs, refname,
2945 flags & REF_FORCE_CREATE_REFLOG,
2946 &logfd, err);
2947
2948 if (result)
2949 return result;
2950
2951 if (logfd < 0)
2952 return 0;
2953 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2954 git_committer_info(0), msg);
2955 if (result) {
2956 struct strbuf sb = STRBUF_INIT;
2957 int save_errno = errno;
2958
2959 files_reflog_path(refs, &sb, refname);
2960 strbuf_addf(err, "unable to append to '%s': %s",
2961 sb.buf, strerror(save_errno));
2962 strbuf_release(&sb);
2963 close(logfd);
2964 return -1;
2965 }
2966 if (close(logfd)) {
2967 struct strbuf sb = STRBUF_INIT;
2968 int save_errno = errno;
2969
2970 files_reflog_path(refs, &sb, refname);
2971 strbuf_addf(err, "unable to append to '%s': %s",
2972 sb.buf, strerror(save_errno));
2973 strbuf_release(&sb);
2974 return -1;
2975 }
2976 return 0;
2977 }
2978
2979 /*
2980 * Write sha1 into the open lockfile, then close the lockfile. On
2981 * errors, rollback the lockfile, fill in *err and
2982 * return -1.
2983 */
2984 static int write_ref_to_lockfile(struct ref_lock *lock,
2985 const unsigned char *sha1, struct strbuf *err)
2986 {
2987 static char term = '\n';
2988 struct object *o;
2989 int fd;
2990
2991 o = parse_object(sha1);
2992 if (!o) {
2993 strbuf_addf(err,
2994 "trying to write ref '%s' with nonexistent object %s",
2995 lock->ref_name, sha1_to_hex(sha1));
2996 unlock_ref(lock);
2997 return -1;
2998 }
2999 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
3000 strbuf_addf(err,
3001 "trying to write non-commit object %s to branch '%s'",
3002 sha1_to_hex(sha1), lock->ref_name);
3003 unlock_ref(lock);
3004 return -1;
3005 }
3006 fd = get_lock_file_fd(lock->lk);
3007 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
3008 write_in_full(fd, &term, 1) != 1 ||
3009 close_ref(lock) < 0) {
3010 strbuf_addf(err,
3011 "couldn't write '%s'", get_lock_file_path(lock->lk));
3012 unlock_ref(lock);
3013 return -1;
3014 }
3015 return 0;
3016 }
3017
3018 /*
3019 * Commit a change to a loose reference that has already been written
3020 * to the loose reference lockfile. Also update the reflogs if
3021 * necessary, using the specified lockmsg (which can be NULL).
3022 */
3023 static int commit_ref_update(struct files_ref_store *refs,
3024 struct ref_lock *lock,
3025 const unsigned char *sha1, const char *logmsg,
3026 struct strbuf *err)
3027 {
3028 files_assert_main_repository(refs, "commit_ref_update");
3029
3030 clear_loose_ref_cache(refs);
3031 if (files_log_ref_write(refs, lock->ref_name,
3032 lock->old_oid.hash, sha1,
3033 logmsg, 0, err)) {
3034 char *old_msg = strbuf_detach(err, NULL);
3035 strbuf_addf(err, "cannot update the ref '%s': %s",
3036 lock->ref_name, old_msg);
3037 free(old_msg);
3038 unlock_ref(lock);
3039 return -1;
3040 }
3041
3042 if (strcmp(lock->ref_name, "HEAD") != 0) {
3043 /*
3044 * Special hack: If a branch is updated directly and HEAD
3045 * points to it (may happen on the remote side of a push
3046 * for example) then logically the HEAD reflog should be
3047 * updated too.
3048 * A generic solution implies reverse symref information,
3049 * but finding all symrefs pointing to the given branch
3050 * would be rather costly for this rare event (the direct
3051 * update of a branch) to be worth it. So let's cheat and
3052 * check with HEAD only which should cover 99% of all usage
3053 * scenarios (even 100% of the default ones).
3054 */
3055 unsigned char head_sha1[20];
3056 int head_flag;
3057 const char *head_ref;
3058
3059 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
3060 head_sha1, &head_flag);
3061 if (head_ref && (head_flag & REF_ISSYMREF) &&
3062 !strcmp(head_ref, lock->ref_name)) {
3063 struct strbuf log_err = STRBUF_INIT;
3064 if (files_log_ref_write(refs, "HEAD",
3065 lock->old_oid.hash, sha1,
3066 logmsg, 0, &log_err)) {
3067 error("%s", log_err.buf);
3068 strbuf_release(&log_err);
3069 }
3070 }
3071 }
3072
3073 if (commit_ref(lock)) {
3074 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3075 unlock_ref(lock);
3076 return -1;
3077 }
3078
3079 unlock_ref(lock);
3080 return 0;
3081 }
3082
3083 static int create_ref_symlink(struct ref_lock *lock, const char *target)
3084 {
3085 int ret = -1;
3086 #ifndef NO_SYMLINK_HEAD
3087 char *ref_path = get_locked_file_path(lock->lk);
3088 unlink(ref_path);
3089 ret = symlink(target, ref_path);
3090 free(ref_path);
3091
3092 if (ret)
3093 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
3094 #endif
3095 return ret;
3096 }
3097
3098 static void update_symref_reflog(struct files_ref_store *refs,
3099 struct ref_lock *lock, const char *refname,
3100 const char *target, const char *logmsg)
3101 {
3102 struct strbuf err = STRBUF_INIT;
3103 unsigned char new_sha1[20];
3104 if (logmsg && !read_ref(target, new_sha1) &&
3105 files_log_ref_write(refs, refname, lock->old_oid.hash,
3106 new_sha1, logmsg, 0, &err)) {
3107 error("%s", err.buf);
3108 strbuf_release(&err);
3109 }
3110 }
3111
3112 static int create_symref_locked(struct files_ref_store *refs,
3113 struct ref_lock *lock, const char *refname,
3114 const char *target, const char *logmsg)
3115 {
3116 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
3117 update_symref_reflog(refs, lock, refname, target, logmsg);
3118 return 0;
3119 }
3120
3121 if (!fdopen_lock_file(lock->lk, "w"))
3122 return error("unable to fdopen %s: %s",
3123 lock->lk->tempfile.filename.buf, strerror(errno));
3124
3125 update_symref_reflog(refs, lock, refname, target, logmsg);
3126
3127 /* no error check; commit_ref will check ferror */
3128 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
3129 if (commit_ref(lock) < 0)
3130 return error("unable to write symref for %s: %s", refname,
3131 strerror(errno));
3132 return 0;
3133 }
3134
3135 static int files_create_symref(struct ref_store *ref_store,
3136 const char *refname, const char *target,
3137 const char *logmsg)
3138 {
3139 struct files_ref_store *refs =
3140 files_downcast(ref_store, 0, "create_symref");
3141 struct strbuf err = STRBUF_INIT;
3142 struct ref_lock *lock;
3143 int ret;
3144
3145 lock = lock_ref_sha1_basic(refs, refname, NULL,
3146 NULL, NULL, REF_NODEREF, NULL,
3147 &err);
3148 if (!lock) {
3149 error("%s", err.buf);
3150 strbuf_release(&err);
3151 return -1;
3152 }
3153
3154 ret = create_symref_locked(refs, lock, refname, target, logmsg);
3155 unlock_ref(lock);
3156 return ret;
3157 }
3158
3159 int set_worktree_head_symref(const char *gitdir, const char *target, const char *logmsg)
3160 {
3161 /*
3162 * FIXME: this obviously will not work well for future refs
3163 * backends. This function needs to die.
3164 */
3165 struct files_ref_store *refs =
3166 files_downcast(get_main_ref_store(), 0, "set_head_symref");
3167
3168 static struct lock_file head_lock;
3169 struct ref_lock *lock;
3170 struct strbuf head_path = STRBUF_INIT;
3171 const char *head_rel;
3172 int ret;
3173
3174 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3175 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3176 LOCK_NO_DEREF) < 0) {
3177 struct strbuf err = STRBUF_INIT;
3178 unable_to_lock_message(head_path.buf, errno, &err);
3179 error("%s", err.buf);
3180 strbuf_release(&err);
3181 strbuf_release(&head_path);
3182 return -1;
3183 }
3184
3185 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3186 linked trees */
3187 head_rel = remove_leading_path(head_path.buf,
3188 absolute_path(get_git_common_dir()));
3189 /* to make use of create_symref_locked(), initialize ref_lock */
3190 lock = xcalloc(1, sizeof(struct ref_lock));
3191 lock->lk = &head_lock;
3192 lock->ref_name = xstrdup(head_rel);
3193
3194 ret = create_symref_locked(refs, lock, head_rel, target, logmsg);
3195
3196 unlock_ref(lock); /* will free lock */
3197 strbuf_release(&head_path);
3198 return ret;
3199 }
3200
3201 static int files_reflog_exists(struct ref_store *ref_store,
3202 const char *refname)
3203 {
3204 struct files_ref_store *refs =
3205 files_downcast(ref_store, 0, "reflog_exists");
3206 struct strbuf sb = STRBUF_INIT;
3207 struct stat st;
3208 int ret;
3209
3210 files_reflog_path(refs, &sb, refname);
3211 ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
3212 strbuf_release(&sb);
3213 return ret;
3214 }
3215
3216 static int files_delete_reflog(struct ref_store *ref_store,
3217 const char *refname)
3218 {
3219 struct files_ref_store *refs =
3220 files_downcast(ref_store, 0, "delete_reflog");
3221 struct strbuf sb = STRBUF_INIT;
3222 int ret;
3223
3224 files_reflog_path(refs, &sb, refname);
3225 ret = remove_path(sb.buf);
3226 strbuf_release(&sb);
3227 return ret;
3228 }
3229
3230 static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3231 {
3232 struct object_id ooid, noid;
3233 char *email_end, *message;
3234 unsigned long timestamp;
3235 int tz;
3236 const char *p = sb->buf;
3237
3238 /* old SP new SP name <email> SP time TAB msg LF */
3239 if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
3240 parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
3241 parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
3242 !(email_end = strchr(p, '>')) ||
3243 email_end[1] != ' ' ||
3244 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3245 !message || message[0] != ' ' ||
3246 (message[1] != '+' && message[1] != '-') ||
3247 !isdigit(message[2]) || !isdigit(message[3]) ||
3248 !isdigit(message[4]) || !isdigit(message[5]))
3249 return 0; /* corrupt? */
3250 email_end[1] = '\0';
3251 tz = strtol(message + 1, NULL, 10);
3252 if (message[6] != '\t')
3253 message += 6;
3254 else
3255 message += 7;
3256 return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
3257 }
3258
3259 static char *find_beginning_of_line(char *bob, char *scan)
3260 {
3261 while (bob < scan && *(--scan) != '\n')
3262 ; /* keep scanning backwards */
3263 /*
3264 * Return either beginning of the buffer, or LF at the end of
3265 * the previous line.
3266 */
3267 return scan;
3268 }
3269
3270 static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
3271 const char *refname,
3272 each_reflog_ent_fn fn,
3273 void *cb_data)
3274 {
3275 struct files_ref_store *refs =
3276 files_downcast(ref_store, 0, "for_each_reflog_ent_reverse");
3277 struct strbuf sb = STRBUF_INIT;
3278 FILE *logfp;
3279 long pos;
3280 int ret = 0, at_tail = 1;
3281
3282 files_reflog_path(refs, &sb, refname);
3283 logfp = fopen(sb.buf, "r");
3284 strbuf_release(&sb);
3285 if (!logfp)
3286 return -1;
3287
3288 /* Jump to the end */
3289 if (fseek(logfp, 0, SEEK_END) < 0)
3290 return error("cannot seek back reflog for %s: %s",
3291 refname, strerror(errno));
3292 pos = ftell(logfp);
3293 while (!ret && 0 < pos) {
3294 int cnt;
3295 size_t nread;
3296 char buf[BUFSIZ];
3297 char *endp, *scanp;
3298
3299 /* Fill next block from the end */
3300 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3301 if (fseek(logfp, pos - cnt, SEEK_SET))
3302 return error("cannot seek back reflog for %s: %s",
3303 refname, strerror(errno));
3304 nread = fread(buf, cnt, 1, logfp);
3305 if (nread != 1)
3306 return error("cannot read %d bytes from reflog for %s: %s",
3307 cnt, refname, strerror(errno));
3308 pos -= cnt;
3309
3310 scanp = endp = buf + cnt;
3311 if (at_tail && scanp[-1] == '\n')
3312 /* Looking at the final LF at the end of the file */
3313 scanp--;
3314 at_tail = 0;
3315
3316 while (buf < scanp) {
3317 /*
3318 * terminating LF of the previous line, or the beginning
3319 * of the buffer.
3320 */
3321 char *bp;
3322
3323 bp = find_beginning_of_line(buf, scanp);
3324
3325 if (*bp == '\n') {
3326 /*
3327 * The newline is the end of the previous line,
3328 * so we know we have complete line starting
3329 * at (bp + 1). Prefix it onto any prior data
3330 * we collected for the line and process it.
3331 */
3332 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3333 scanp = bp;
3334 endp = bp + 1;
3335 ret = show_one_reflog_ent(&sb, fn, cb_data);
3336 strbuf_reset(&sb);
3337 if (ret)
3338 break;
3339 } else if (!pos) {
3340 /*
3341 * We are at the start of the buffer, and the
3342 * start of the file; there is no previous
3343 * line, and we have everything for this one.
3344 * Process it, and we can end the loop.
3345 */
3346 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3347 ret = show_one_reflog_ent(&sb, fn, cb_data);
3348 strbuf_reset(&sb);
3349 break;
3350 }
3351
3352 if (bp == buf) {
3353 /*
3354 * We are at the start of the buffer, and there
3355 * is more file to read backwards. Which means
3356 * we are in the middle of a line. Note that we
3357 * may get here even if *bp was a newline; that
3358 * just means we are at the exact end of the
3359 * previous line, rather than some spot in the
3360 * middle.
3361 *
3362 * Save away what we have to be combined with
3363 * the data from the next read.
3364 */
3365 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3366 break;
3367 }
3368 }
3369
3370 }
3371 if (!ret && sb.len)
3372 die("BUG: reverse reflog parser had leftover data");
3373
3374 fclose(logfp);
3375 strbuf_release(&sb);
3376 return ret;
3377 }
3378
3379 static int files_for_each_reflog_ent(struct ref_store *ref_store,
3380 const char *refname,
3381 each_reflog_ent_fn fn, void *cb_data)
3382 {
3383 struct files_ref_store *refs =
3384 files_downcast(ref_store, 0, "for_each_reflog_ent");
3385 FILE *logfp;
3386 struct strbuf sb = STRBUF_INIT;
3387 int ret = 0;
3388
3389 files_reflog_path(refs, &sb, refname);
3390 logfp = fopen(sb.buf, "r");
3391 strbuf_release(&sb);
3392 if (!logfp)
3393 return -1;
3394
3395 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3396 ret = show_one_reflog_ent(&sb, fn, cb_data);
3397 fclose(logfp);
3398 strbuf_release(&sb);
3399 return ret;
3400 }
3401
3402 struct files_reflog_iterator {
3403 struct ref_iterator base;
3404
3405 struct dir_iterator *dir_iterator;
3406 struct object_id oid;
3407 };
3408
3409 static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
3410 {
3411 struct files_reflog_iterator *iter =
3412 (struct files_reflog_iterator *)ref_iterator;
3413 struct dir_iterator *diter = iter->dir_iterator;
3414 int ok;
3415
3416 while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
3417 int flags;
3418
3419 if (!S_ISREG(diter->st.st_mode))
3420 continue;
3421 if (diter->basename[0] == '.')
3422 continue;
3423 if (ends_with(diter->basename, ".lock"))
3424 continue;
3425
3426 if (read_ref_full(diter->relative_path, 0,
3427 iter->oid.hash, &flags)) {
3428 error("bad ref for %s", diter->path.buf);
3429 continue;
3430 }
3431
3432 iter->base.refname = diter->relative_path;
3433 iter->base.oid = &iter->oid;
3434 iter->base.flags = flags;
3435 return ITER_OK;
3436 }
3437
3438 iter->dir_iterator = NULL;
3439 if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
3440 ok = ITER_ERROR;
3441 return ok;
3442 }
3443
3444 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator,
3445 struct object_id *peeled)
3446 {
3447 die("BUG: ref_iterator_peel() called for reflog_iterator");
3448 }
3449
3450 static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
3451 {
3452 struct files_reflog_iterator *iter =
3453 (struct files_reflog_iterator *)ref_iterator;
3454 int ok = ITER_DONE;
3455
3456 if (iter->dir_iterator)
3457 ok = dir_iterator_abort(iter->dir_iterator);
3458
3459 base_ref_iterator_free(ref_iterator);
3460 return ok;
3461 }
3462
3463 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
3464 files_reflog_iterator_advance,
3465 files_reflog_iterator_peel,
3466 files_reflog_iterator_abort
3467 };
3468
3469 static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
3470 {
3471 struct files_ref_store *refs =
3472 files_downcast(ref_store, 0, "reflog_iterator_begin");
3473 struct files_reflog_iterator *iter = xcalloc(1, sizeof(*iter));
3474 struct ref_iterator *ref_iterator = &iter->base;
3475 struct strbuf sb = STRBUF_INIT;
3476
3477 base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable);
3478 files_reflog_path(refs, &sb, NULL);
3479 iter->dir_iterator = dir_iterator_begin(sb.buf);
3480 strbuf_release(&sb);
3481 return ref_iterator;
3482 }
3483
3484 static int ref_update_reject_duplicates(struct string_list *refnames,
3485 struct strbuf *err)
3486 {
3487 int i, n = refnames->nr;
3488
3489 assert(err);
3490
3491 for (i = 1; i < n; i++)
3492 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3493 strbuf_addf(err,
3494 "multiple updates for ref '%s' not allowed.",
3495 refnames->items[i].string);
3496 return 1;
3497 }
3498 return 0;
3499 }
3500
3501 /*
3502 * If update is a direct update of head_ref (the reference pointed to
3503 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3504 */
3505 static int split_head_update(struct ref_update *update,
3506 struct ref_transaction *transaction,
3507 const char *head_ref,
3508 struct string_list *affected_refnames,
3509 struct strbuf *err)
3510 {
3511 struct string_list_item *item;
3512 struct ref_update *new_update;
3513
3514 if ((update->flags & REF_LOG_ONLY) ||
3515 (update->flags & REF_ISPRUNING) ||
3516 (update->flags & REF_UPDATE_VIA_HEAD))
3517 return 0;
3518
3519 if (strcmp(update->refname, head_ref))
3520 return 0;
3521
3522 /*
3523 * First make sure that HEAD is not already in the
3524 * transaction. This insertion is O(N) in the transaction
3525 * size, but it happens at most once per transaction.
3526 */
3527 item = string_list_insert(affected_refnames, "HEAD");
3528 if (item->util) {
3529 /* An entry already existed */
3530 strbuf_addf(err,
3531 "multiple updates for 'HEAD' (including one "
3532 "via its referent '%s') are not allowed",
3533 update->refname);
3534 return TRANSACTION_NAME_CONFLICT;
3535 }
3536
3537 new_update = ref_transaction_add_update(
3538 transaction, "HEAD",
3539 update->flags | REF_LOG_ONLY | REF_NODEREF,
3540 update->new_sha1, update->old_sha1,
3541 update->msg);
3542
3543 item->util = new_update;
3544
3545 return 0;
3546 }
3547
3548 /*
3549 * update is for a symref that points at referent and doesn't have
3550 * REF_NODEREF set. Split it into two updates:
3551 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3552 * - A new, separate update for the referent reference
3553 * Note that the new update will itself be subject to splitting when
3554 * the iteration gets to it.
3555 */
3556 static int split_symref_update(struct files_ref_store *refs,
3557 struct ref_update *update,
3558 const char *referent,
3559 struct ref_transaction *transaction,
3560 struct string_list *affected_refnames,
3561 struct strbuf *err)
3562 {
3563 struct string_list_item *item;
3564 struct ref_update *new_update;
3565 unsigned int new_flags;
3566
3567 /*
3568 * First make sure that referent is not already in the
3569 * transaction. This insertion is O(N) in the transaction
3570 * size, but it happens at most once per symref in a
3571 * transaction.
3572 */
3573 item = string_list_insert(affected_refnames, referent);
3574 if (item->util) {
3575 /* An entry already existed */
3576 strbuf_addf(err,
3577 "multiple updates for '%s' (including one "
3578 "via symref '%s') are not allowed",
3579 referent, update->refname);
3580 return TRANSACTION_NAME_CONFLICT;
3581 }
3582
3583 new_flags = update->flags;
3584 if (!strcmp(update->refname, "HEAD")) {
3585 /*
3586 * Record that the new update came via HEAD, so that
3587 * when we process it, split_head_update() doesn't try
3588 * to add another reflog update for HEAD. Note that
3589 * this bit will be propagated if the new_update
3590 * itself needs to be split.
3591 */
3592 new_flags |= REF_UPDATE_VIA_HEAD;
3593 }
3594
3595 new_update = ref_transaction_add_update(
3596 transaction, referent, new_flags,
3597 update->new_sha1, update->old_sha1,
3598 update->msg);
3599
3600 new_update->parent_update = update;
3601
3602 /*
3603 * Change the symbolic ref update to log only. Also, it
3604 * doesn't need to check its old SHA-1 value, as that will be
3605 * done when new_update is processed.
3606 */
3607 update->flags |= REF_LOG_ONLY | REF_NODEREF;
3608 update->flags &= ~REF_HAVE_OLD;
3609
3610 item->util = new_update;
3611
3612 return 0;
3613 }
3614
3615 /*
3616 * Return the refname under which update was originally requested.
3617 */
3618 static const char *original_update_refname(struct ref_update *update)
3619 {
3620 while (update->parent_update)
3621 update = update->parent_update;
3622
3623 return update->refname;
3624 }
3625
3626 /*
3627 * Check whether the REF_HAVE_OLD and old_oid values stored in update
3628 * are consistent with oid, which is the reference's current value. If
3629 * everything is OK, return 0; otherwise, write an error message to
3630 * err and return -1.
3631 */
3632 static int check_old_oid(struct ref_update *update, struct object_id *oid,
3633 struct strbuf *err)
3634 {
3635 if (!(update->flags & REF_HAVE_OLD) ||
3636 !hashcmp(oid->hash, update->old_sha1))
3637 return 0;
3638
3639 if (is_null_sha1(update->old_sha1))
3640 strbuf_addf(err, "cannot lock ref '%s': "
3641 "reference already exists",
3642 original_update_refname(update));
3643 else if (is_null_oid(oid))
3644 strbuf_addf(err, "cannot lock ref '%s': "
3645 "reference is missing but expected %s",
3646 original_update_refname(update),
3647 sha1_to_hex(update->old_sha1));
3648 else
3649 strbuf_addf(err, "cannot lock ref '%s': "
3650 "is at %s but expected %s",
3651 original_update_refname(update),
3652 oid_to_hex(oid),
3653 sha1_to_hex(update->old_sha1));
3654
3655 return -1;
3656 }
3657
3658 /*
3659 * Prepare for carrying out update:
3660 * - Lock the reference referred to by update.
3661 * - Read the reference under lock.
3662 * - Check that its old SHA-1 value (if specified) is correct, and in
3663 * any case record it in update->lock->old_oid for later use when
3664 * writing the reflog.
3665 * - If it is a symref update without REF_NODEREF, split it up into a
3666 * REF_LOG_ONLY update of the symref and add a separate update for
3667 * the referent to transaction.
3668 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3669 * update of HEAD.
3670 */
3671 static int lock_ref_for_update(struct files_ref_store *refs,
3672 struct ref_update *update,
3673 struct ref_transaction *transaction,
3674 const char *head_ref,
3675 struct string_list *affected_refnames,
3676 struct strbuf *err)
3677 {
3678 struct strbuf referent = STRBUF_INIT;
3679 int mustexist = (update->flags & REF_HAVE_OLD) &&
3680 !is_null_sha1(update->old_sha1);
3681 int ret;
3682 struct ref_lock *lock;
3683
3684 files_assert_main_repository(refs, "lock_ref_for_update");
3685
3686 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
3687 update->flags |= REF_DELETING;
3688
3689 if (head_ref) {
3690 ret = split_head_update(update, transaction, head_ref,
3691 affected_refnames, err);
3692 if (ret)
3693 return ret;
3694 }
3695
3696 ret = lock_raw_ref(refs, update->refname, mustexist,
3697 affected_refnames, NULL,
3698 &lock, &referent,
3699 &update->type, err);
3700 if (ret) {
3701 char *reason;
3702
3703 reason = strbuf_detach(err, NULL);
3704 strbuf_addf(err, "cannot lock ref '%s': %s",
3705 original_update_refname(update), reason);
3706 free(reason);
3707 return ret;
3708 }
3709
3710 update->backend_data = lock;
3711
3712 if (update->type & REF_ISSYMREF) {
3713 if (update->flags & REF_NODEREF) {
3714 /*
3715 * We won't be reading the referent as part of
3716 * the transaction, so we have to read it here
3717 * to record and possibly check old_sha1:
3718 */
3719 if (read_ref_full(referent.buf, 0,
3720 lock->old_oid.hash, NULL)) {
3721 if (update->flags & REF_HAVE_OLD) {
3722 strbuf_addf(err, "cannot lock ref '%s': "
3723 "error reading reference",
3724 original_update_refname(update));
3725 return -1;
3726 }
3727 } else if (check_old_oid(update, &lock->old_oid, err)) {
3728 return TRANSACTION_GENERIC_ERROR;
3729 }
3730 } else {
3731 /*
3732 * Create a new update for the reference this
3733 * symref is pointing at. Also, we will record
3734 * and verify old_sha1 for this update as part
3735 * of processing the split-off update, so we
3736 * don't have to do it here.
3737 */
3738 ret = split_symref_update(refs, update,
3739 referent.buf, transaction,
3740 affected_refnames, err);
3741 if (ret)
3742 return ret;
3743 }
3744 } else {
3745 struct ref_update *parent_update;
3746
3747 if (check_old_oid(update, &lock->old_oid, err))
3748 return TRANSACTION_GENERIC_ERROR;
3749
3750 /*
3751 * If this update is happening indirectly because of a
3752 * symref update, record the old SHA-1 in the parent
3753 * update:
3754 */
3755 for (parent_update = update->parent_update;
3756 parent_update;
3757 parent_update = parent_update->parent_update) {
3758 struct ref_lock *parent_lock = parent_update->backend_data;
3759 oidcpy(&parent_lock->old_oid, &lock->old_oid);
3760 }
3761 }
3762
3763 if ((update->flags & REF_HAVE_NEW) &&
3764 !(update->flags & REF_DELETING) &&
3765 !(update->flags & REF_LOG_ONLY)) {
3766 if (!(update->type & REF_ISSYMREF) &&
3767 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
3768 /*
3769 * The reference already has the desired
3770 * value, so we don't need to write it.
3771 */
3772 } else if (write_ref_to_lockfile(lock, update->new_sha1,
3773 err)) {
3774 char *write_err = strbuf_detach(err, NULL);
3775
3776 /*
3777 * The lock was freed upon failure of
3778 * write_ref_to_lockfile():
3779 */
3780 update->backend_data = NULL;
3781 strbuf_addf(err,
3782 "cannot update ref '%s': %s",
3783 update->refname, write_err);
3784 free(write_err);
3785 return TRANSACTION_GENERIC_ERROR;
3786 } else {
3787 update->flags |= REF_NEEDS_COMMIT;
3788 }
3789 }
3790 if (!(update->flags & REF_NEEDS_COMMIT)) {
3791 /*
3792 * We didn't call write_ref_to_lockfile(), so
3793 * the lockfile is still open. Close it to
3794 * free up the file descriptor:
3795 */
3796 if (close_ref(lock)) {
3797 strbuf_addf(err, "couldn't close '%s.lock'",
3798 update->refname);
3799 return TRANSACTION_GENERIC_ERROR;
3800 }
3801 }
3802 return 0;
3803 }
3804
3805 static int files_transaction_commit(struct ref_store *ref_store,
3806 struct ref_transaction *transaction,
3807 struct strbuf *err)
3808 {
3809 struct files_ref_store *refs =
3810 files_downcast(ref_store, 0, "ref_transaction_commit");
3811 int ret = 0, i;
3812 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3813 struct string_list_item *ref_to_delete;
3814 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
3815 char *head_ref = NULL;
3816 int head_type;
3817 struct object_id head_oid;
3818 struct strbuf sb = STRBUF_INIT;
3819
3820 assert(err);
3821
3822