commit_ref_update(): remove the flags parameter
[git/git.git] / refs / files-backend.c
CommitLineData
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1#include "../cache.h"
2#include "../refs.h"
3#include "refs-internal.h"
4#include "../lockfile.h"
5#include "../object.h"
6#include "../dir.h"
7
8struct ref_lock {
9 char *ref_name;
10 char *orig_ref_name;
11 struct lock_file *lk;
12 struct object_id old_oid;
13};
14
15struct ref_entry;
16
17/*
18 * Information used (along with the information in ref_entry) to
19 * describe a single cached reference. This data structure only
20 * occurs embedded in a union in struct ref_entry, and only when
21 * (ref_entry->flag & REF_DIR) is zero.
22 */
23struct ref_value {
24 /*
25 * The name of the object to which this reference resolves
26 * (which may be a tag object). If REF_ISBROKEN, this is
27 * null. If REF_ISSYMREF, then this is the name of the object
28 * referred to by the last reference in the symlink chain.
29 */
30 struct object_id oid;
31
32 /*
33 * If REF_KNOWS_PEELED, then this field holds the peeled value
34 * of this reference, or null if the reference is known not to
35 * be peelable. See the documentation for peel_ref() for an
36 * exact definition of "peelable".
37 */
38 struct object_id peeled;
39};
40
41struct ref_cache;
42
43/*
44 * Information used (along with the information in ref_entry) to
45 * describe a level in the hierarchy of references. This data
46 * structure only occurs embedded in a union in struct ref_entry, and
47 * only when (ref_entry.flag & REF_DIR) is set. In that case,
48 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
49 * in the directory have already been read:
50 *
51 * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
52 * or packed references, already read.
53 *
54 * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
55 * references that hasn't been read yet (nor has any of its
56 * subdirectories).
57 *
58 * Entries within a directory are stored within a growable array of
59 * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
60 * sorted are sorted by their component name in strcmp() order and the
61 * remaining entries are unsorted.
62 *
63 * Loose references are read lazily, one directory at a time. When a
64 * directory of loose references is read, then all of the references
65 * in that directory are stored, and REF_INCOMPLETE stubs are created
66 * for any subdirectories, but the subdirectories themselves are not
67 * read. The reading is triggered by get_ref_dir().
68 */
69struct ref_dir {
70 int nr, alloc;
71
72 /*
73 * Entries with index 0 <= i < sorted are sorted by name. New
74 * entries are appended to the list unsorted, and are sorted
75 * only when required; thus we avoid the need to sort the list
76 * after the addition of every reference.
77 */
78 int sorted;
79
80 /* A pointer to the ref_cache that contains this ref_dir. */
81 struct ref_cache *ref_cache;
82
83 struct ref_entry **entries;
84};
85
86/*
87 * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
88 * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
89 * public values; see refs.h.
90 */
91
92/*
93 * The field ref_entry->u.value.peeled of this value entry contains
94 * the correct peeled value for the reference, which might be
95 * null_sha1 if the reference is not a tag or if it is broken.
96 */
97#define REF_KNOWS_PEELED 0x10
98
99/* ref_entry represents a directory of references */
100#define REF_DIR 0x20
101
102/*
103 * Entry has not yet been read from disk (used only for REF_DIR
104 * entries representing loose references)
105 */
106#define REF_INCOMPLETE 0x40
107
108/*
109 * A ref_entry represents either a reference or a "subdirectory" of
110 * references.
111 *
112 * Each directory in the reference namespace is represented by a
113 * ref_entry with (flags & REF_DIR) set and containing a subdir member
114 * that holds the entries in that directory that have been read so
115 * far. If (flags & REF_INCOMPLETE) is set, then the directory and
116 * its subdirectories haven't been read yet. REF_INCOMPLETE is only
117 * used for loose reference directories.
118 *
119 * References are represented by a ref_entry with (flags & REF_DIR)
120 * unset and a value member that describes the reference's value. The
121 * flag member is at the ref_entry level, but it is also needed to
122 * interpret the contents of the value field (in other words, a
123 * ref_value object is not very much use without the enclosing
124 * ref_entry).
125 *
126 * Reference names cannot end with slash and directories' names are
127 * always stored with a trailing slash (except for the top-level
128 * directory, which is always denoted by ""). This has two nice
129 * consequences: (1) when the entries in each subdir are sorted
130 * lexicographically by name (as they usually are), the references in
131 * a whole tree can be generated in lexicographic order by traversing
132 * the tree in left-to-right, depth-first order; (2) the names of
133 * references and subdirectories cannot conflict, and therefore the
134 * presence of an empty subdirectory does not block the creation of a
135 * similarly-named reference. (The fact that reference names with the
136 * same leading components can conflict *with each other* is a
137 * separate issue that is regulated by verify_refname_available().)
138 *
139 * Please note that the name field contains the fully-qualified
140 * reference (or subdirectory) name. Space could be saved by only
141 * storing the relative names. But that would require the full names
142 * to be generated on the fly when iterating in do_for_each_ref(), and
143 * would break callback functions, who have always been able to assume
144 * that the name strings that they are passed will not be freed during
145 * the iteration.
146 */
147struct ref_entry {
148 unsigned char flag; /* ISSYMREF? ISPACKED? */
149 union {
150 struct ref_value value; /* if not (flags&REF_DIR) */
151 struct ref_dir subdir; /* if (flags&REF_DIR) */
152 } u;
153 /*
154 * The full name of the reference (e.g., "refs/heads/master")
155 * or the full name of the directory with a trailing slash
156 * (e.g., "refs/heads/"):
157 */
158 char name[FLEX_ARRAY];
159};
160
161static void read_loose_refs(const char *dirname, struct ref_dir *dir);
162static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
163static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
164 const char *dirname, size_t len,
165 int incomplete);
166static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
167
168static struct ref_dir *get_ref_dir(struct ref_entry *entry)
169{
170 struct ref_dir *dir;
171 assert(entry->flag & REF_DIR);
172 dir = &entry->u.subdir;
173 if (entry->flag & REF_INCOMPLETE) {
174 read_loose_refs(entry->name, dir);
175
176 /*
177 * Manually add refs/bisect, which, being
178 * per-worktree, might not appear in the directory
179 * listing for refs/ in the main repo.
180 */
181 if (!strcmp(entry->name, "refs/")) {
182 int pos = search_ref_dir(dir, "refs/bisect/", 12);
183 if (pos < 0) {
184 struct ref_entry *child_entry;
185 child_entry = create_dir_entry(dir->ref_cache,
186 "refs/bisect/",
187 12, 1);
188 add_entry_to_dir(dir, child_entry);
189 read_loose_refs("refs/bisect",
190 &child_entry->u.subdir);
191 }
192 }
193 entry->flag &= ~REF_INCOMPLETE;
194 }
195 return dir;
196}
197
198static struct ref_entry *create_ref_entry(const char *refname,
199 const unsigned char *sha1, int flag,
200 int check_name)
201{
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202 struct ref_entry *ref;
203
204 if (check_name &&
205 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
206 die("Reference has invalid format: '%s'", refname);
96ffc06f 207 FLEX_ALLOC_STR(ref, name, refname);
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208 hashcpy(ref->u.value.oid.hash, sha1);
209 oidclr(&ref->u.value.peeled);
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210 ref->flag = flag;
211 return ref;
212}
213
214static void clear_ref_dir(struct ref_dir *dir);
215
216static void free_ref_entry(struct ref_entry *entry)
217{
218 if (entry->flag & REF_DIR) {
219 /*
220 * Do not use get_ref_dir() here, as that might
221 * trigger the reading of loose refs.
222 */
223 clear_ref_dir(&entry->u.subdir);
224 }
225 free(entry);
226}
227
228/*
229 * Add a ref_entry to the end of dir (unsorted). Entry is always
230 * stored directly in dir; no recursion into subdirectories is
231 * done.
232 */
233static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
234{
235 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
236 dir->entries[dir->nr++] = entry;
237 /* optimize for the case that entries are added in order */
238 if (dir->nr == 1 ||
239 (dir->nr == dir->sorted + 1 &&
240 strcmp(dir->entries[dir->nr - 2]->name,
241 dir->entries[dir->nr - 1]->name) < 0))
242 dir->sorted = dir->nr;
243}
244
245/*
246 * Clear and free all entries in dir, recursively.
247 */
248static void clear_ref_dir(struct ref_dir *dir)
249{
250 int i;
251 for (i = 0; i < dir->nr; i++)
252 free_ref_entry(dir->entries[i]);
253 free(dir->entries);
254 dir->sorted = dir->nr = dir->alloc = 0;
255 dir->entries = NULL;
256}
257
258/*
259 * Create a struct ref_entry object for the specified dirname.
260 * dirname is the name of the directory with a trailing slash (e.g.,
261 * "refs/heads/") or "" for the top-level directory.
262 */
263static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
264 const char *dirname, size_t len,
265 int incomplete)
266{
267 struct ref_entry *direntry;
96ffc06f 268 FLEX_ALLOC_MEM(direntry, name, dirname, len);
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269 direntry->u.subdir.ref_cache = ref_cache;
270 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
271 return direntry;
272}
273
274static int ref_entry_cmp(const void *a, const void *b)
275{
276 struct ref_entry *one = *(struct ref_entry **)a;
277 struct ref_entry *two = *(struct ref_entry **)b;
278 return strcmp(one->name, two->name);
279}
280
281static void sort_ref_dir(struct ref_dir *dir);
282
283struct string_slice {
284 size_t len;
285 const char *str;
286};
287
288static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
289{
290 const struct string_slice *key = key_;
291 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
292 int cmp = strncmp(key->str, ent->name, key->len);
293 if (cmp)
294 return cmp;
295 return '\0' - (unsigned char)ent->name[key->len];
296}
297
298/*
299 * Return the index of the entry with the given refname from the
300 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
301 * no such entry is found. dir must already be complete.
302 */
303static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
304{
305 struct ref_entry **r;
306 struct string_slice key;
307
308 if (refname == NULL || !dir->nr)
309 return -1;
310
311 sort_ref_dir(dir);
312 key.len = len;
313 key.str = refname;
314 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
315 ref_entry_cmp_sslice);
316
317 if (r == NULL)
318 return -1;
319
320 return r - dir->entries;
321}
322
323/*
324 * Search for a directory entry directly within dir (without
325 * recursing). Sort dir if necessary. subdirname must be a directory
326 * name (i.e., end in '/'). If mkdir is set, then create the
327 * directory if it is missing; otherwise, return NULL if the desired
328 * directory cannot be found. dir must already be complete.
329 */
330static struct ref_dir *search_for_subdir(struct ref_dir *dir,
331 const char *subdirname, size_t len,
332 int mkdir)
333{
334 int entry_index = search_ref_dir(dir, subdirname, len);
335 struct ref_entry *entry;
336 if (entry_index == -1) {
337 if (!mkdir)
338 return NULL;
339 /*
340 * Since dir is complete, the absence of a subdir
341 * means that the subdir really doesn't exist;
342 * therefore, create an empty record for it but mark
343 * the record complete.
344 */
345 entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
346 add_entry_to_dir(dir, entry);
347 } else {
348 entry = dir->entries[entry_index];
349 }
350 return get_ref_dir(entry);
351}
352
353/*
354 * If refname is a reference name, find the ref_dir within the dir
355 * tree that should hold refname. If refname is a directory name
356 * (i.e., ends in '/'), then return that ref_dir itself. dir must
357 * represent the top-level directory and must already be complete.
358 * Sort ref_dirs and recurse into subdirectories as necessary. If
359 * mkdir is set, then create any missing directories; otherwise,
360 * return NULL if the desired directory cannot be found.
361 */
362static struct ref_dir *find_containing_dir(struct ref_dir *dir,
363 const char *refname, int mkdir)
364{
365 const char *slash;
366 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
367 size_t dirnamelen = slash - refname + 1;
368 struct ref_dir *subdir;
369 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
370 if (!subdir) {
371 dir = NULL;
372 break;
373 }
374 dir = subdir;
375 }
376
377 return dir;
378}
379
380/*
381 * Find the value entry with the given name in dir, sorting ref_dirs
382 * and recursing into subdirectories as necessary. If the name is not
383 * found or it corresponds to a directory entry, return NULL.
384 */
385static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
386{
387 int entry_index;
388 struct ref_entry *entry;
389 dir = find_containing_dir(dir, refname, 0);
390 if (!dir)
391 return NULL;
392 entry_index = search_ref_dir(dir, refname, strlen(refname));
393 if (entry_index == -1)
394 return NULL;
395 entry = dir->entries[entry_index];
396 return (entry->flag & REF_DIR) ? NULL : entry;
397}
398
399/*
400 * Remove the entry with the given name from dir, recursing into
401 * subdirectories as necessary. If refname is the name of a directory
402 * (i.e., ends with '/'), then remove the directory and its contents.
403 * If the removal was successful, return the number of entries
404 * remaining in the directory entry that contained the deleted entry.
405 * If the name was not found, return -1. Please note that this
406 * function only deletes the entry from the cache; it does not delete
407 * it from the filesystem or ensure that other cache entries (which
408 * might be symbolic references to the removed entry) are updated.
409 * Nor does it remove any containing dir entries that might be made
410 * empty by the removal. dir must represent the top-level directory
411 * and must already be complete.
412 */
413static int remove_entry(struct ref_dir *dir, const char *refname)
414{
415 int refname_len = strlen(refname);
416 int entry_index;
417 struct ref_entry *entry;
418 int is_dir = refname[refname_len - 1] == '/';
419 if (is_dir) {
420 /*
421 * refname represents a reference directory. Remove
422 * the trailing slash; otherwise we will get the
423 * directory *representing* refname rather than the
424 * one *containing* it.
425 */
426 char *dirname = xmemdupz(refname, refname_len - 1);
427 dir = find_containing_dir(dir, dirname, 0);
428 free(dirname);
429 } else {
430 dir = find_containing_dir(dir, refname, 0);
431 }
432 if (!dir)
433 return -1;
434 entry_index = search_ref_dir(dir, refname, refname_len);
435 if (entry_index == -1)
436 return -1;
437 entry = dir->entries[entry_index];
438
439 memmove(&dir->entries[entry_index],
440 &dir->entries[entry_index + 1],
441 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
442 );
443 dir->nr--;
444 if (dir->sorted > entry_index)
445 dir->sorted--;
446 free_ref_entry(entry);
447 return dir->nr;
448}
449
450/*
451 * Add a ref_entry to the ref_dir (unsorted), recursing into
452 * subdirectories as necessary. dir must represent the top-level
453 * directory. Return 0 on success.
454 */
455static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
456{
457 dir = find_containing_dir(dir, ref->name, 1);
458 if (!dir)
459 return -1;
460 add_entry_to_dir(dir, ref);
461 return 0;
462}
463
464/*
465 * Emit a warning and return true iff ref1 and ref2 have the same name
466 * and the same sha1. Die if they have the same name but different
467 * sha1s.
468 */
469static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
470{
471 if (strcmp(ref1->name, ref2->name))
472 return 0;
473
474 /* Duplicate name; make sure that they don't conflict: */
475
476 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
477 /* This is impossible by construction */
478 die("Reference directory conflict: %s", ref1->name);
479
480 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
481 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
482
483 warning("Duplicated ref: %s", ref1->name);
484 return 1;
485}
486
487/*
488 * Sort the entries in dir non-recursively (if they are not already
489 * sorted) and remove any duplicate entries.
490 */
491static void sort_ref_dir(struct ref_dir *dir)
492{
493 int i, j;
494 struct ref_entry *last = NULL;
495
496 /*
497 * This check also prevents passing a zero-length array to qsort(),
498 * which is a problem on some platforms.
499 */
500 if (dir->sorted == dir->nr)
501 return;
502
503 qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
504
505 /* Remove any duplicates: */
506 for (i = 0, j = 0; j < dir->nr; j++) {
507 struct ref_entry *entry = dir->entries[j];
508 if (last && is_dup_ref(last, entry))
509 free_ref_entry(entry);
510 else
511 last = dir->entries[i++] = entry;
512 }
513 dir->sorted = dir->nr = i;
514}
515
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516/*
517 * Return true iff the reference described by entry can be resolved to
518 * an object in the database. Emit a warning if the referred-to
519 * object does not exist.
520 */
521static int ref_resolves_to_object(struct ref_entry *entry)
522{
523 if (entry->flag & REF_ISBROKEN)
524 return 0;
525 if (!has_sha1_file(entry->u.value.oid.hash)) {
526 error("%s does not point to a valid object!", entry->name);
527 return 0;
528 }
529 return 1;
530}
531
532/*
533 * current_ref is a performance hack: when iterating over references
534 * using the for_each_ref*() functions, current_ref is set to the
535 * current reference's entry before calling the callback function. If
536 * the callback function calls peel_ref(), then peel_ref() first
537 * checks whether the reference to be peeled is the current reference
538 * (it usually is) and if so, returns that reference's peeled version
539 * if it is available. This avoids a refname lookup in a common case.
540 */
541static struct ref_entry *current_ref;
542
543typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
544
545struct ref_entry_cb {
546 const char *base;
547 int trim;
548 int flags;
549 each_ref_fn *fn;
550 void *cb_data;
551};
552
553/*
554 * Handle one reference in a do_for_each_ref*()-style iteration,
555 * calling an each_ref_fn for each entry.
556 */
557static int do_one_ref(struct ref_entry *entry, void *cb_data)
558{
559 struct ref_entry_cb *data = cb_data;
560 struct ref_entry *old_current_ref;
561 int retval;
562
563 if (!starts_with(entry->name, data->base))
564 return 0;
565
566 if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
567 !ref_resolves_to_object(entry))
568 return 0;
569
570 /* Store the old value, in case this is a recursive call: */
571 old_current_ref = current_ref;
572 current_ref = entry;
573 retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
574 entry->flag, data->cb_data);
575 current_ref = old_current_ref;
576 return retval;
577}
578
579/*
580 * Call fn for each reference in dir that has index in the range
581 * offset <= index < dir->nr. Recurse into subdirectories that are in
582 * that index range, sorting them before iterating. This function
583 * does not sort dir itself; it should be sorted beforehand. fn is
584 * called for all references, including broken ones.
585 */
586static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
587 each_ref_entry_fn fn, void *cb_data)
588{
589 int i;
590 assert(dir->sorted == dir->nr);
591 for (i = offset; i < dir->nr; i++) {
592 struct ref_entry *entry = dir->entries[i];
593 int retval;
594 if (entry->flag & REF_DIR) {
595 struct ref_dir *subdir = get_ref_dir(entry);
596 sort_ref_dir(subdir);
597 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
598 } else {
599 retval = fn(entry, cb_data);
600 }
601 if (retval)
602 return retval;
603 }
604 return 0;
605}
606
607/*
608 * Call fn for each reference in the union of dir1 and dir2, in order
609 * by refname. Recurse into subdirectories. If a value entry appears
610 * in both dir1 and dir2, then only process the version that is in
611 * dir2. The input dirs must already be sorted, but subdirs will be
612 * sorted as needed. fn is called for all references, including
613 * broken ones.
614 */
615static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
616 struct ref_dir *dir2,
617 each_ref_entry_fn fn, void *cb_data)
618{
619 int retval;
620 int i1 = 0, i2 = 0;
621
622 assert(dir1->sorted == dir1->nr);
623 assert(dir2->sorted == dir2->nr);
624 while (1) {
625 struct ref_entry *e1, *e2;
626 int cmp;
627 if (i1 == dir1->nr) {
628 return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
629 }
630 if (i2 == dir2->nr) {
631 return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
632 }
633 e1 = dir1->entries[i1];
634 e2 = dir2->entries[i2];
635 cmp = strcmp(e1->name, e2->name);
636 if (cmp == 0) {
637 if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
638 /* Both are directories; descend them in parallel. */
639 struct ref_dir *subdir1 = get_ref_dir(e1);
640 struct ref_dir *subdir2 = get_ref_dir(e2);
641 sort_ref_dir(subdir1);
642 sort_ref_dir(subdir2);
643 retval = do_for_each_entry_in_dirs(
644 subdir1, subdir2, fn, cb_data);
645 i1++;
646 i2++;
647 } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
648 /* Both are references; ignore the one from dir1. */
649 retval = fn(e2, cb_data);
650 i1++;
651 i2++;
652 } else {
653 die("conflict between reference and directory: %s",
654 e1->name);
655 }
656 } else {
657 struct ref_entry *e;
658 if (cmp < 0) {
659 e = e1;
660 i1++;
661 } else {
662 e = e2;
663 i2++;
664 }
665 if (e->flag & REF_DIR) {
666 struct ref_dir *subdir = get_ref_dir(e);
667 sort_ref_dir(subdir);
668 retval = do_for_each_entry_in_dir(
669 subdir, 0, fn, cb_data);
670 } else {
671 retval = fn(e, cb_data);
672 }
673 }
674 if (retval)
675 return retval;
676 }
677}
678
679/*
680 * Load all of the refs from the dir into our in-memory cache. The hard work
681 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
682 * through all of the sub-directories. We do not even need to care about
683 * sorting, as traversal order does not matter to us.
684 */
685static void prime_ref_dir(struct ref_dir *dir)
686{
687 int i;
688 for (i = 0; i < dir->nr; i++) {
689 struct ref_entry *entry = dir->entries[i];
690 if (entry->flag & REF_DIR)
691 prime_ref_dir(get_ref_dir(entry));
692 }
693}
694
695struct nonmatching_ref_data {
696 const struct string_list *skip;
697 const char *conflicting_refname;
698};
699
700static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
701{
702 struct nonmatching_ref_data *data = vdata;
703
704 if (data->skip && string_list_has_string(data->skip, entry->name))
705 return 0;
706
707 data->conflicting_refname = entry->name;
708 return 1;
709}
710
711/*
712 * Return 0 if a reference named refname could be created without
713 * conflicting with the name of an existing reference in dir.
714 * See verify_refname_available for more information.
715 */
716static int verify_refname_available_dir(const char *refname,
717 const struct string_list *extras,
718 const struct string_list *skip,
719 struct ref_dir *dir,
720 struct strbuf *err)
721{
722 const char *slash;
0845122c 723 const char *extra_refname;
7bd9bcf3
MH
724 int pos;
725 struct strbuf dirname = STRBUF_INIT;
726 int ret = -1;
727
728 /*
729 * For the sake of comments in this function, suppose that
730 * refname is "refs/foo/bar".
731 */
732
733 assert(err);
734
735 strbuf_grow(&dirname, strlen(refname) + 1);
736 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
737 /* Expand dirname to the new prefix, not including the trailing slash: */
738 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
739
740 /*
741 * We are still at a leading dir of the refname (e.g.,
742 * "refs/foo"; if there is a reference with that name,
743 * it is a conflict, *unless* it is in skip.
744 */
745 if (dir) {
746 pos = search_ref_dir(dir, dirname.buf, dirname.len);
747 if (pos >= 0 &&
748 (!skip || !string_list_has_string(skip, dirname.buf))) {
749 /*
750 * We found a reference whose name is
751 * a proper prefix of refname; e.g.,
752 * "refs/foo", and is not in skip.
753 */
754 strbuf_addf(err, "'%s' exists; cannot create '%s'",
755 dirname.buf, refname);
756 goto cleanup;
757 }
758 }
759
760 if (extras && string_list_has_string(extras, dirname.buf) &&
761 (!skip || !string_list_has_string(skip, dirname.buf))) {
762 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
763 refname, dirname.buf);
764 goto cleanup;
765 }
766
767 /*
768 * Otherwise, we can try to continue our search with
769 * the next component. So try to look up the
770 * directory, e.g., "refs/foo/". If we come up empty,
771 * we know there is nothing under this whole prefix,
772 * but even in that case we still have to continue the
773 * search for conflicts with extras.
774 */
775 strbuf_addch(&dirname, '/');
776 if (dir) {
777 pos = search_ref_dir(dir, dirname.buf, dirname.len);
778 if (pos < 0) {
779 /*
780 * There was no directory "refs/foo/",
781 * so there is nothing under this
782 * whole prefix. So there is no need
783 * to continue looking for conflicting
784 * references. But we need to continue
785 * looking for conflicting extras.
786 */
787 dir = NULL;
788 } else {
789 dir = get_ref_dir(dir->entries[pos]);
790 }
791 }
792 }
793
794 /*
795 * We are at the leaf of our refname (e.g., "refs/foo/bar").
796 * There is no point in searching for a reference with that
797 * name, because a refname isn't considered to conflict with
798 * itself. But we still need to check for references whose
799 * names are in the "refs/foo/bar/" namespace, because they
800 * *do* conflict.
801 */
802 strbuf_addstr(&dirname, refname + dirname.len);
803 strbuf_addch(&dirname, '/');
804
805 if (dir) {
806 pos = search_ref_dir(dir, dirname.buf, dirname.len);
807
808 if (pos >= 0) {
809 /*
810 * We found a directory named "$refname/"
811 * (e.g., "refs/foo/bar/"). It is a problem
812 * iff it contains any ref that is not in
813 * "skip".
814 */
815 struct nonmatching_ref_data data;
816
817 data.skip = skip;
818 data.conflicting_refname = NULL;
819 dir = get_ref_dir(dir->entries[pos]);
820 sort_ref_dir(dir);
821 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
822 strbuf_addf(err, "'%s' exists; cannot create '%s'",
823 data.conflicting_refname, refname);
824 goto cleanup;
825 }
826 }
827 }
828
0845122c
DT
829 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
830 if (extra_refname)
831 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
832 refname, extra_refname);
833 else
834 ret = 0;
7bd9bcf3
MH
835
836cleanup:
837 strbuf_release(&dirname);
838 return ret;
839}
840
841struct packed_ref_cache {
842 struct ref_entry *root;
843
844 /*
845 * Count of references to the data structure in this instance,
846 * including the pointer from ref_cache::packed if any. The
847 * data will not be freed as long as the reference count is
848 * nonzero.
849 */
850 unsigned int referrers;
851
852 /*
853 * Iff the packed-refs file associated with this instance is
854 * currently locked for writing, this points at the associated
855 * lock (which is owned by somebody else). The referrer count
856 * is also incremented when the file is locked and decremented
857 * when it is unlocked.
858 */
859 struct lock_file *lock;
860
861 /* The metadata from when this packed-refs cache was read */
862 struct stat_validity validity;
863};
864
865/*
866 * Future: need to be in "struct repository"
867 * when doing a full libification.
868 */
869static struct ref_cache {
870 struct ref_cache *next;
871 struct ref_entry *loose;
872 struct packed_ref_cache *packed;
873 /*
874 * The submodule name, or "" for the main repo. We allocate
875 * length 1 rather than FLEX_ARRAY so that the main ref_cache
876 * is initialized correctly.
877 */
878 char name[1];
879} ref_cache, *submodule_ref_caches;
880
881/* Lock used for the main packed-refs file: */
882static struct lock_file packlock;
883
884/*
885 * Increment the reference count of *packed_refs.
886 */
887static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
888{
889 packed_refs->referrers++;
890}
891
892/*
893 * Decrease the reference count of *packed_refs. If it goes to zero,
894 * free *packed_refs and return true; otherwise return false.
895 */
896static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
897{
898 if (!--packed_refs->referrers) {
899 free_ref_entry(packed_refs->root);
900 stat_validity_clear(&packed_refs->validity);
901 free(packed_refs);
902 return 1;
903 } else {
904 return 0;
905 }
906}
907
908static void clear_packed_ref_cache(struct ref_cache *refs)
909{
910 if (refs->packed) {
911 struct packed_ref_cache *packed_refs = refs->packed;
912
913 if (packed_refs->lock)
914 die("internal error: packed-ref cache cleared while locked");
915 refs->packed = NULL;
916 release_packed_ref_cache(packed_refs);
917 }
918}
919
920static void clear_loose_ref_cache(struct ref_cache *refs)
921{
922 if (refs->loose) {
923 free_ref_entry(refs->loose);
924 refs->loose = NULL;
925 }
926}
927
a2d5156c
JK
928/*
929 * Create a new submodule ref cache and add it to the internal
930 * set of caches.
931 */
7bd9bcf3
MH
932static struct ref_cache *create_ref_cache(const char *submodule)
933{
7bd9bcf3
MH
934 struct ref_cache *refs;
935 if (!submodule)
936 submodule = "";
96ffc06f 937 FLEX_ALLOC_STR(refs, name, submodule);
a2d5156c
JK
938 refs->next = submodule_ref_caches;
939 submodule_ref_caches = refs;
7bd9bcf3
MH
940 return refs;
941}
942
a2d5156c 943static struct ref_cache *lookup_ref_cache(const char *submodule)
7bd9bcf3
MH
944{
945 struct ref_cache *refs;
946
947 if (!submodule || !*submodule)
948 return &ref_cache;
949
950 for (refs = submodule_ref_caches; refs; refs = refs->next)
951 if (!strcmp(submodule, refs->name))
952 return refs;
a2d5156c
JK
953 return NULL;
954}
7bd9bcf3 955
a2d5156c
JK
956/*
957 * Return a pointer to a ref_cache for the specified submodule. For
958 * the main repository, use submodule==NULL. The returned structure
959 * will be allocated and initialized but not necessarily populated; it
960 * should not be freed.
961 */
962static struct ref_cache *get_ref_cache(const char *submodule)
963{
964 struct ref_cache *refs = lookup_ref_cache(submodule);
965 if (!refs)
966 refs = create_ref_cache(submodule);
7bd9bcf3
MH
967 return refs;
968}
969
970/* The length of a peeled reference line in packed-refs, including EOL: */
971#define PEELED_LINE_LENGTH 42
972
973/*
974 * The packed-refs header line that we write out. Perhaps other
975 * traits will be added later. The trailing space is required.
976 */
977static const char PACKED_REFS_HEADER[] =
978 "# pack-refs with: peeled fully-peeled \n";
979
980/*
981 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
982 * Return a pointer to the refname within the line (null-terminated),
983 * or NULL if there was a problem.
984 */
985static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
986{
987 const char *ref;
988
989 /*
990 * 42: the answer to everything.
991 *
992 * In this case, it happens to be the answer to
993 * 40 (length of sha1 hex representation)
994 * +1 (space in between hex and name)
995 * +1 (newline at the end of the line)
996 */
997 if (line->len <= 42)
998 return NULL;
999
1000 if (get_sha1_hex(line->buf, sha1) < 0)
1001 return NULL;
1002 if (!isspace(line->buf[40]))
1003 return NULL;
1004
1005 ref = line->buf + 41;
1006 if (isspace(*ref))
1007 return NULL;
1008
1009 if (line->buf[line->len - 1] != '\n')
1010 return NULL;
1011 line->buf[--line->len] = 0;
1012
1013 return ref;
1014}
1015
1016/*
1017 * Read f, which is a packed-refs file, into dir.
1018 *
1019 * A comment line of the form "# pack-refs with: " may contain zero or
1020 * more traits. We interpret the traits as follows:
1021 *
1022 * No traits:
1023 *
1024 * Probably no references are peeled. But if the file contains a
1025 * peeled value for a reference, we will use it.
1026 *
1027 * peeled:
1028 *
1029 * References under "refs/tags/", if they *can* be peeled, *are*
1030 * peeled in this file. References outside of "refs/tags/" are
1031 * probably not peeled even if they could have been, but if we find
1032 * a peeled value for such a reference we will use it.
1033 *
1034 * fully-peeled:
1035 *
1036 * All references in the file that can be peeled are peeled.
1037 * Inversely (and this is more important), any references in the
1038 * file for which no peeled value is recorded is not peelable. This
1039 * trait should typically be written alongside "peeled" for
1040 * compatibility with older clients, but we do not require it
1041 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1042 */
1043static void read_packed_refs(FILE *f, struct ref_dir *dir)
1044{
1045 struct ref_entry *last = NULL;
1046 struct strbuf line = STRBUF_INIT;
1047 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1048
1049 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1050 unsigned char sha1[20];
1051 const char *refname;
1052 const char *traits;
1053
1054 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1055 if (strstr(traits, " fully-peeled "))
1056 peeled = PEELED_FULLY;
1057 else if (strstr(traits, " peeled "))
1058 peeled = PEELED_TAGS;
1059 /* perhaps other traits later as well */
1060 continue;
1061 }
1062
1063 refname = parse_ref_line(&line, sha1);
1064 if (refname) {
1065 int flag = REF_ISPACKED;
1066
1067 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1068 if (!refname_is_safe(refname))
1069 die("packed refname is dangerous: %s", refname);
1070 hashclr(sha1);
1071 flag |= REF_BAD_NAME | REF_ISBROKEN;
1072 }
1073 last = create_ref_entry(refname, sha1, flag, 0);
1074 if (peeled == PEELED_FULLY ||
1075 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1076 last->flag |= REF_KNOWS_PEELED;
1077 add_ref(dir, last);
1078 continue;
1079 }
1080 if (last &&
1081 line.buf[0] == '^' &&
1082 line.len == PEELED_LINE_LENGTH &&
1083 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1084 !get_sha1_hex(line.buf + 1, sha1)) {
1085 hashcpy(last->u.value.peeled.hash, sha1);
1086 /*
1087 * Regardless of what the file header said,
1088 * we definitely know the value of *this*
1089 * reference:
1090 */
1091 last->flag |= REF_KNOWS_PEELED;
1092 }
1093 }
1094
1095 strbuf_release(&line);
1096}
1097
1098/*
1099 * Get the packed_ref_cache for the specified ref_cache, creating it
1100 * if necessary.
1101 */
1102static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1103{
1104 char *packed_refs_file;
1105
1106 if (*refs->name)
1107 packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
1108 else
1109 packed_refs_file = git_pathdup("packed-refs");
1110
1111 if (refs->packed &&
1112 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1113 clear_packed_ref_cache(refs);
1114
1115 if (!refs->packed) {
1116 FILE *f;
1117
1118 refs->packed = xcalloc(1, sizeof(*refs->packed));
1119 acquire_packed_ref_cache(refs->packed);
1120 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1121 f = fopen(packed_refs_file, "r");
1122 if (f) {
1123 stat_validity_update(&refs->packed->validity, fileno(f));
1124 read_packed_refs(f, get_ref_dir(refs->packed->root));
1125 fclose(f);
1126 }
1127 }
1128 free(packed_refs_file);
1129 return refs->packed;
1130}
1131
1132static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1133{
1134 return get_ref_dir(packed_ref_cache->root);
1135}
1136
1137static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1138{
1139 return get_packed_ref_dir(get_packed_ref_cache(refs));
1140}
1141
1142/*
1143 * Add a reference to the in-memory packed reference cache. This may
1144 * only be called while the packed-refs file is locked (see
1145 * lock_packed_refs()). To actually write the packed-refs file, call
1146 * commit_packed_refs().
1147 */
1148static void add_packed_ref(const char *refname, const unsigned char *sha1)
1149{
1150 struct packed_ref_cache *packed_ref_cache =
1151 get_packed_ref_cache(&ref_cache);
1152
1153 if (!packed_ref_cache->lock)
1154 die("internal error: packed refs not locked");
1155 add_ref(get_packed_ref_dir(packed_ref_cache),
1156 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1157}
1158
1159/*
1160 * Read the loose references from the namespace dirname into dir
1161 * (without recursing). dirname must end with '/'. dir must be the
1162 * directory entry corresponding to dirname.
1163 */
1164static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1165{
1166 struct ref_cache *refs = dir->ref_cache;
1167 DIR *d;
1168 struct dirent *de;
1169 int dirnamelen = strlen(dirname);
1170 struct strbuf refname;
1171 struct strbuf path = STRBUF_INIT;
1172 size_t path_baselen;
1173
1174 if (*refs->name)
1175 strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
1176 else
1177 strbuf_git_path(&path, "%s", dirname);
1178 path_baselen = path.len;
1179
1180 d = opendir(path.buf);
1181 if (!d) {
1182 strbuf_release(&path);
1183 return;
1184 }
1185
1186 strbuf_init(&refname, dirnamelen + 257);
1187 strbuf_add(&refname, dirname, dirnamelen);
1188
1189 while ((de = readdir(d)) != NULL) {
1190 unsigned char sha1[20];
1191 struct stat st;
1192 int flag;
1193
1194 if (de->d_name[0] == '.')
1195 continue;
1196 if (ends_with(de->d_name, ".lock"))
1197 continue;
1198 strbuf_addstr(&refname, de->d_name);
1199 strbuf_addstr(&path, de->d_name);
1200 if (stat(path.buf, &st) < 0) {
1201 ; /* silently ignore */
1202 } else if (S_ISDIR(st.st_mode)) {
1203 strbuf_addch(&refname, '/');
1204 add_entry_to_dir(dir,
1205 create_dir_entry(refs, refname.buf,
1206 refname.len, 1));
1207 } else {
1208 int read_ok;
1209
1210 if (*refs->name) {
1211 hashclr(sha1);
1212 flag = 0;
1213 read_ok = !resolve_gitlink_ref(refs->name,
1214 refname.buf, sha1);
1215 } else {
1216 read_ok = !read_ref_full(refname.buf,
1217 RESOLVE_REF_READING,
1218 sha1, &flag);
1219 }
1220
1221 if (!read_ok) {
1222 hashclr(sha1);
1223 flag |= REF_ISBROKEN;
1224 } else if (is_null_sha1(sha1)) {
1225 /*
1226 * It is so astronomically unlikely
1227 * that NULL_SHA1 is the SHA-1 of an
1228 * actual object that we consider its
1229 * appearance in a loose reference
1230 * file to be repo corruption
1231 * (probably due to a software bug).
1232 */
1233 flag |= REF_ISBROKEN;
1234 }
1235
1236 if (check_refname_format(refname.buf,
1237 REFNAME_ALLOW_ONELEVEL)) {
1238 if (!refname_is_safe(refname.buf))
1239 die("loose refname is dangerous: %s", refname.buf);
1240 hashclr(sha1);
1241 flag |= REF_BAD_NAME | REF_ISBROKEN;
1242 }
1243 add_entry_to_dir(dir,
1244 create_ref_entry(refname.buf, sha1, flag, 0));
1245 }
1246 strbuf_setlen(&refname, dirnamelen);
1247 strbuf_setlen(&path, path_baselen);
1248 }
1249 strbuf_release(&refname);
1250 strbuf_release(&path);
1251 closedir(d);
1252}
1253
1254static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1255{
1256 if (!refs->loose) {
1257 /*
1258 * Mark the top-level directory complete because we
1259 * are about to read the only subdirectory that can
1260 * hold references:
1261 */
1262 refs->loose = create_dir_entry(refs, "", 0, 0);
1263 /*
1264 * Create an incomplete entry for "refs/":
1265 */
1266 add_entry_to_dir(get_ref_dir(refs->loose),
1267 create_dir_entry(refs, "refs/", 5, 1));
1268 }
1269 return get_ref_dir(refs->loose);
1270}
1271
7bd9bcf3
MH
1272#define MAXREFLEN (1024)
1273
1274/*
1275 * Called by resolve_gitlink_ref_recursive() after it failed to read
1276 * from the loose refs in ref_cache refs. Find <refname> in the
1277 * packed-refs file for the submodule.
1278 */
1279static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1280 const char *refname, unsigned char *sha1)
1281{
1282 struct ref_entry *ref;
1283 struct ref_dir *dir = get_packed_refs(refs);
1284
1285 ref = find_ref(dir, refname);
1286 if (ref == NULL)
1287 return -1;
1288
1289 hashcpy(sha1, ref->u.value.oid.hash);
1290 return 0;
1291}
1292
1293static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1294 const char *refname, unsigned char *sha1,
1295 int recursion)
1296{
1297 int fd, len;
1298 char buffer[128], *p;
1299 char *path;
1300
2d0663b2 1301 if (recursion > SYMREF_MAXDEPTH || strlen(refname) > MAXREFLEN)
7bd9bcf3
MH
1302 return -1;
1303 path = *refs->name
1304 ? git_pathdup_submodule(refs->name, "%s", refname)
1305 : git_pathdup("%s", refname);
1306 fd = open(path, O_RDONLY);
1307 free(path);
1308 if (fd < 0)
1309 return resolve_gitlink_packed_ref(refs, refname, sha1);
1310
1311 len = read(fd, buffer, sizeof(buffer)-1);
1312 close(fd);
1313 if (len < 0)
1314 return -1;
1315 while (len && isspace(buffer[len-1]))
1316 len--;
1317 buffer[len] = 0;
1318
1319 /* Was it a detached head or an old-fashioned symlink? */
1320 if (!get_sha1_hex(buffer, sha1))
1321 return 0;
1322
1323 /* Symref? */
1324 if (strncmp(buffer, "ref:", 4))
1325 return -1;
1326 p = buffer + 4;
1327 while (isspace(*p))
1328 p++;
1329
1330 return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1331}
1332
1333int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1334{
1335 int len = strlen(path), retval;
a2d5156c 1336 struct strbuf submodule = STRBUF_INIT;
7bd9bcf3
MH
1337 struct ref_cache *refs;
1338
1339 while (len && path[len-1] == '/')
1340 len--;
1341 if (!len)
1342 return -1;
a2d5156c
JK
1343
1344 strbuf_add(&submodule, path, len);
1345 refs = lookup_ref_cache(submodule.buf);
1346 if (!refs) {
1347 if (!is_nonbare_repository_dir(&submodule)) {
1348 strbuf_release(&submodule);
1349 return -1;
1350 }
1351 refs = create_ref_cache(submodule.buf);
1352 }
1353 strbuf_release(&submodule);
7bd9bcf3
MH
1354
1355 retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1356 return retval;
1357}
1358
1359/*
1360 * Return the ref_entry for the given refname from the packed
1361 * references. If it does not exist, return NULL.
1362 */
1363static struct ref_entry *get_packed_ref(const char *refname)
1364{
1365 return find_ref(get_packed_refs(&ref_cache), refname);
1366}
1367
1368/*
419c6f4c 1369 * A loose ref file doesn't exist; check for a packed ref.
7bd9bcf3
MH
1370 */
1371static int resolve_missing_loose_ref(const char *refname,
7bd9bcf3 1372 unsigned char *sha1,
89e82389 1373 unsigned int *flags)
7bd9bcf3
MH
1374{
1375 struct ref_entry *entry;
1376
1377 /*
1378 * The loose reference file does not exist; check for a packed
1379 * reference.
1380 */
1381 entry = get_packed_ref(refname);
1382 if (entry) {
1383 hashcpy(sha1, entry->u.value.oid.hash);
a70a93b7 1384 *flags |= REF_ISPACKED;
7bd9bcf3
MH
1385 return 0;
1386 }
419c6f4c
MH
1387 /* refname is not a packed reference. */
1388 return -1;
7bd9bcf3
MH
1389}
1390
2d0663b2 1391int read_raw_ref(const char *refname, unsigned char *sha1,
92b38093 1392 struct strbuf *referent, unsigned int *type)
7bd9bcf3 1393{
42a38cf7
MH
1394 struct strbuf sb_contents = STRBUF_INIT;
1395 struct strbuf sb_path = STRBUF_INIT;
7048653a
DT
1396 const char *path;
1397 const char *buf;
1398 struct stat st;
1399 int fd;
42a38cf7
MH
1400 int ret = -1;
1401 int save_errno;
7bd9bcf3 1402
fa96ea1b 1403 *type = 0;
42a38cf7
MH
1404 strbuf_reset(&sb_path);
1405 strbuf_git_path(&sb_path, "%s", refname);
1406 path = sb_path.buf;
7bd9bcf3 1407
7048653a
DT
1408stat_ref:
1409 /*
1410 * We might have to loop back here to avoid a race
1411 * condition: first we lstat() the file, then we try
1412 * to read it as a link or as a file. But if somebody
1413 * changes the type of the file (file <-> directory
1414 * <-> symlink) between the lstat() and reading, then
1415 * we don't want to report that as an error but rather
1416 * try again starting with the lstat().
1417 */
7bd9bcf3 1418
7048653a
DT
1419 if (lstat(path, &st) < 0) {
1420 if (errno != ENOENT)
42a38cf7 1421 goto out;
3a0b6b9a 1422 if (resolve_missing_loose_ref(refname, sha1, type)) {
7048653a 1423 errno = ENOENT;
42a38cf7 1424 goto out;
7bd9bcf3 1425 }
42a38cf7
MH
1426 ret = 0;
1427 goto out;
7bd9bcf3 1428 }
7bd9bcf3 1429
7048653a
DT
1430 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1431 if (S_ISLNK(st.st_mode)) {
42a38cf7
MH
1432 strbuf_reset(&sb_contents);
1433 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
7048653a 1434 if (errno == ENOENT || errno == EINVAL)
7bd9bcf3
MH
1435 /* inconsistent with lstat; retry */
1436 goto stat_ref;
1437 else
42a38cf7 1438 goto out;
7bd9bcf3 1439 }
42a38cf7
MH
1440 if (starts_with(sb_contents.buf, "refs/") &&
1441 !check_refname_format(sb_contents.buf, 0)) {
92b38093 1442 strbuf_swap(&sb_contents, referent);
3a0b6b9a 1443 *type |= REF_ISSYMREF;
42a38cf7
MH
1444 ret = 0;
1445 goto out;
7bd9bcf3 1446 }
7048653a 1447 }
7bd9bcf3 1448
7048653a
DT
1449 /* Is it a directory? */
1450 if (S_ISDIR(st.st_mode)) {
e167a567
MH
1451 /*
1452 * Even though there is a directory where the loose
1453 * ref is supposed to be, there could still be a
1454 * packed ref:
1455 */
3a0b6b9a 1456 if (resolve_missing_loose_ref(refname, sha1, type)) {
e167a567
MH
1457 errno = EISDIR;
1458 goto out;
1459 }
1460 ret = 0;
42a38cf7 1461 goto out;
7048653a
DT
1462 }
1463
1464 /*
1465 * Anything else, just open it and try to use it as
1466 * a ref
1467 */
1468 fd = open(path, O_RDONLY);
1469 if (fd < 0) {
1470 if (errno == ENOENT)
1471 /* inconsistent with lstat; retry */
1472 goto stat_ref;
1473 else
42a38cf7 1474 goto out;
7048653a 1475 }
42a38cf7
MH
1476 strbuf_reset(&sb_contents);
1477 if (strbuf_read(&sb_contents, fd, 256) < 0) {
7048653a
DT
1478 int save_errno = errno;
1479 close(fd);
1480 errno = save_errno;
42a38cf7 1481 goto out;
7048653a
DT
1482 }
1483 close(fd);
42a38cf7
MH
1484 strbuf_rtrim(&sb_contents);
1485 buf = sb_contents.buf;
7048653a
DT
1486 if (starts_with(buf, "ref:")) {
1487 buf += 4;
7bd9bcf3
MH
1488 while (isspace(*buf))
1489 buf++;
7048653a 1490
92b38093
MH
1491 strbuf_reset(referent);
1492 strbuf_addstr(referent, buf);
3a0b6b9a 1493 *type |= REF_ISSYMREF;
42a38cf7
MH
1494 ret = 0;
1495 goto out;
7bd9bcf3 1496 }
7bd9bcf3 1497
7048653a
DT
1498 /*
1499 * Please note that FETCH_HEAD has additional
1500 * data after the sha.
1501 */
1502 if (get_sha1_hex(buf, sha1) ||
1503 (buf[40] != '\0' && !isspace(buf[40]))) {
3a0b6b9a 1504 *type |= REF_ISBROKEN;
7048653a 1505 errno = EINVAL;
42a38cf7 1506 goto out;
7048653a
DT
1507 }
1508
42a38cf7 1509 ret = 0;
7bd9bcf3 1510
42a38cf7
MH
1511out:
1512 save_errno = errno;
7bd9bcf3
MH
1513 strbuf_release(&sb_path);
1514 strbuf_release(&sb_contents);
42a38cf7 1515 errno = save_errno;
7bd9bcf3
MH
1516 return ret;
1517}
1518
8415d247
MH
1519static void unlock_ref(struct ref_lock *lock)
1520{
1521 /* Do not free lock->lk -- atexit() still looks at them */
1522 if (lock->lk)
1523 rollback_lock_file(lock->lk);
1524 free(lock->ref_name);
1525 free(lock->orig_ref_name);
1526 free(lock);
1527}
1528
92b1551b
MH
1529/*
1530 * Lock refname, without following symrefs, and set *lock_p to point
1531 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1532 * and type similarly to read_raw_ref().
1533 *
1534 * The caller must verify that refname is a "safe" reference name (in
1535 * the sense of refname_is_safe()) before calling this function.
1536 *
1537 * If the reference doesn't already exist, verify that refname doesn't
1538 * have a D/F conflict with any existing references. extras and skip
1539 * are passed to verify_refname_available_dir() for this check.
1540 *
1541 * If mustexist is not set and the reference is not found or is
1542 * broken, lock the reference anyway but clear sha1.
1543 *
1544 * Return 0 on success. On failure, write an error message to err and
1545 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1546 *
1547 * Implementation note: This function is basically
1548 *
1549 * lock reference
1550 * read_raw_ref()
1551 *
1552 * but it includes a lot more code to
1553 * - Deal with possible races with other processes
1554 * - Avoid calling verify_refname_available_dir() when it can be
1555 * avoided, namely if we were successfully able to read the ref
1556 * - Generate informative error messages in the case of failure
1557 */
1558static int lock_raw_ref(const char *refname, int mustexist,
1559 const struct string_list *extras,
1560 const struct string_list *skip,
1561 struct ref_lock **lock_p,
1562 struct strbuf *referent,
1563 unsigned int *type,
1564 struct strbuf *err)
1565{
1566 struct ref_lock *lock;
1567 struct strbuf ref_file = STRBUF_INIT;
1568 int attempts_remaining = 3;
1569 int ret = TRANSACTION_GENERIC_ERROR;
1570
1571 assert(err);
1572 *type = 0;
1573
1574 /* First lock the file so it can't change out from under us. */
1575
1576 *lock_p = lock = xcalloc(1, sizeof(*lock));
1577
1578 lock->ref_name = xstrdup(refname);
1579 lock->orig_ref_name = xstrdup(refname);
1580 strbuf_git_path(&ref_file, "%s", refname);
1581
1582retry:
1583 switch (safe_create_leading_directories(ref_file.buf)) {
1584 case SCLD_OK:
1585 break; /* success */
1586 case SCLD_EXISTS:
1587 /*
1588 * Suppose refname is "refs/foo/bar". We just failed
1589 * to create the containing directory, "refs/foo",
1590 * because there was a non-directory in the way. This
1591 * indicates a D/F conflict, probably because of
1592 * another reference such as "refs/foo". There is no
1593 * reason to expect this error to be transitory.
1594 */
1595 if (verify_refname_available(refname, extras, skip, err)) {
1596 if (mustexist) {
1597 /*
1598 * To the user the relevant error is
1599 * that the "mustexist" reference is
1600 * missing:
1601 */
1602 strbuf_reset(err);
1603 strbuf_addf(err, "unable to resolve reference '%s'",
1604 refname);
1605 } else {
1606 /*
1607 * The error message set by
1608 * verify_refname_available_dir() is OK.
1609 */
1610 ret = TRANSACTION_NAME_CONFLICT;
1611 }
1612 } else {
1613 /*
1614 * The file that is in the way isn't a loose
1615 * reference. Report it as a low-level
1616 * failure.
1617 */
1618 strbuf_addf(err, "unable to create lock file %s.lock; "
1619 "non-directory in the way",
1620 ref_file.buf);
1621 }
1622 goto error_return;
1623 case SCLD_VANISHED:
1624 /* Maybe another process was tidying up. Try again. */
1625 if (--attempts_remaining > 0)
1626 goto retry;
1627 /* fall through */
1628 default:
1629 strbuf_addf(err, "unable to create directory for %s",
1630 ref_file.buf);
1631 goto error_return;
1632 }
1633
1634 if (!lock->lk)
1635 lock->lk = xcalloc(1, sizeof(struct lock_file));
1636
1637 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1638 if (errno == ENOENT && --attempts_remaining > 0) {
1639 /*
1640 * Maybe somebody just deleted one of the
1641 * directories leading to ref_file. Try
1642 * again:
1643 */
1644 goto retry;
1645 } else {
1646 unable_to_lock_message(ref_file.buf, errno, err);
1647 goto error_return;
1648 }
1649 }
1650
1651 /*
1652 * Now we hold the lock and can read the reference without
1653 * fear that its value will change.
1654 */
1655
1656 if (read_raw_ref(refname, lock->old_oid.hash, referent, type)) {
1657 if (errno == ENOENT) {
1658 if (mustexist) {
1659 /* Garden variety missing reference. */
1660 strbuf_addf(err, "unable to resolve reference '%s'",
1661 refname);
1662 goto error_return;
1663 } else {
1664 /*
1665 * Reference is missing, but that's OK. We
1666 * know that there is not a conflict with
1667 * another loose reference because
1668 * (supposing that we are trying to lock
1669 * reference "refs/foo/bar"):
1670 *
1671 * - We were successfully able to create
1672 * the lockfile refs/foo/bar.lock, so we
1673 * know there cannot be a loose reference
1674 * named "refs/foo".
1675 *
1676 * - We got ENOENT and not EISDIR, so we
1677 * know that there cannot be a loose
1678 * reference named "refs/foo/bar/baz".
1679 */
1680 }
1681 } else if (errno == EISDIR) {
1682 /*
1683 * There is a directory in the way. It might have
1684 * contained references that have been deleted. If
1685 * we don't require that the reference already
1686 * exists, try to remove the directory so that it
1687 * doesn't cause trouble when we want to rename the
1688 * lockfile into place later.
1689 */
1690 if (mustexist) {
1691 /* Garden variety missing reference. */
1692 strbuf_addf(err, "unable to resolve reference '%s'",
1693 refname);
1694 goto error_return;
1695 } else if (remove_dir_recursively(&ref_file,
1696 REMOVE_DIR_EMPTY_ONLY)) {
1697 if (verify_refname_available_dir(
1698 refname, extras, skip,
1699 get_loose_refs(&ref_cache),
1700 err)) {
1701 /*
1702 * The error message set by
1703 * verify_refname_available() is OK.
1704 */
1705 ret = TRANSACTION_NAME_CONFLICT;
1706 goto error_return;
1707 } else {
1708 /*
1709 * We can't delete the directory,
1710 * but we also don't know of any
1711 * references that it should
1712 * contain.
1713 */
1714 strbuf_addf(err, "there is a non-empty directory '%s' "
1715 "blocking reference '%s'",
1716 ref_file.buf, refname);
1717 goto error_return;
1718 }
1719 }
1720 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1721 strbuf_addf(err, "unable to resolve reference '%s': "
1722 "reference broken", refname);
1723 goto error_return;
1724 } else {
1725 strbuf_addf(err, "unable to resolve reference '%s': %s",
1726 refname, strerror(errno));
1727 goto error_return;
1728 }
1729
1730 /*
1731 * If the ref did not exist and we are creating it,
1732 * make sure there is no existing packed ref whose
1733 * name begins with our refname, nor a packed ref
1734 * whose name is a proper prefix of our refname.
1735 */
1736 if (verify_refname_available_dir(
1737 refname, extras, skip,
1738 get_packed_refs(&ref_cache),
1739 err)) {
1740 goto error_return;
1741 }
1742 }
1743
1744 ret = 0;
1745 goto out;
1746
1747error_return:
1748 unlock_ref(lock);
1749 *lock_p = NULL;
1750
1751out:
1752 strbuf_release(&ref_file);
1753 return ret;
1754}
1755
7bd9bcf3
MH
1756/*
1757 * Peel the entry (if possible) and return its new peel_status. If
1758 * repeel is true, re-peel the entry even if there is an old peeled
1759 * value that is already stored in it.
1760 *
1761 * It is OK to call this function with a packed reference entry that
1762 * might be stale and might even refer to an object that has since
1763 * been garbage-collected. In such a case, if the entry has
1764 * REF_KNOWS_PEELED then leave the status unchanged and return
1765 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1766 */
1767static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1768{
1769 enum peel_status status;
1770
1771 if (entry->flag & REF_KNOWS_PEELED) {
1772 if (repeel) {
1773 entry->flag &= ~REF_KNOWS_PEELED;
1774 oidclr(&entry->u.value.peeled);
1775 } else {
1776 return is_null_oid(&entry->u.value.peeled) ?
1777 PEEL_NON_TAG : PEEL_PEELED;
1778 }
1779 }
1780 if (entry->flag & REF_ISBROKEN)
1781 return PEEL_BROKEN;
1782 if (entry->flag & REF_ISSYMREF)
1783 return PEEL_IS_SYMREF;
1784
1785 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1786 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1787 entry->flag |= REF_KNOWS_PEELED;
1788 return status;
1789}
1790
1791int peel_ref(const char *refname, unsigned char *sha1)
1792{
1793 int flag;
1794 unsigned char base[20];
1795
1796 if (current_ref && (current_ref->name == refname
1797 || !strcmp(current_ref->name, refname))) {
1798 if (peel_entry(current_ref, 0))
1799 return -1;
1800 hashcpy(sha1, current_ref->u.value.peeled.hash);
1801 return 0;
1802 }
1803
1804 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1805 return -1;
1806
1807 /*
1808 * If the reference is packed, read its ref_entry from the
1809 * cache in the hope that we already know its peeled value.
1810 * We only try this optimization on packed references because
1811 * (a) forcing the filling of the loose reference cache could
1812 * be expensive and (b) loose references anyway usually do not
1813 * have REF_KNOWS_PEELED.
1814 */
1815 if (flag & REF_ISPACKED) {
1816 struct ref_entry *r = get_packed_ref(refname);
1817 if (r) {
1818 if (peel_entry(r, 0))
1819 return -1;
1820 hashcpy(sha1, r->u.value.peeled.hash);
1821 return 0;
1822 }
1823 }
1824
1825 return peel_object(base, sha1);
1826}
1827
1828/*
1829 * Call fn for each reference in the specified ref_cache, omitting
1830 * references not in the containing_dir of base. fn is called for all
1831 * references, including broken ones. If fn ever returns a non-zero
1832 * value, stop the iteration and return that value; otherwise, return
1833 * 0.
1834 */
1835static int do_for_each_entry(struct ref_cache *refs, const char *base,
1836 each_ref_entry_fn fn, void *cb_data)
1837{
1838 struct packed_ref_cache *packed_ref_cache;
1839 struct ref_dir *loose_dir;
1840 struct ref_dir *packed_dir;
1841 int retval = 0;
1842
1843 /*
1844 * We must make sure that all loose refs are read before accessing the
1845 * packed-refs file; this avoids a race condition in which loose refs
1846 * are migrated to the packed-refs file by a simultaneous process, but
1847 * our in-memory view is from before the migration. get_packed_ref_cache()
1848 * takes care of making sure our view is up to date with what is on
1849 * disk.
1850 */
1851 loose_dir = get_loose_refs(refs);
1852 if (base && *base) {
1853 loose_dir = find_containing_dir(loose_dir, base, 0);
1854 }
1855 if (loose_dir)
1856 prime_ref_dir(loose_dir);
1857
1858 packed_ref_cache = get_packed_ref_cache(refs);
1859 acquire_packed_ref_cache(packed_ref_cache);
1860 packed_dir = get_packed_ref_dir(packed_ref_cache);
1861 if (base && *base) {
1862 packed_dir = find_containing_dir(packed_dir, base, 0);
1863 }
1864
1865 if (packed_dir && loose_dir) {
1866 sort_ref_dir(packed_dir);
1867 sort_ref_dir(loose_dir);
1868 retval = do_for_each_entry_in_dirs(
1869 packed_dir, loose_dir, fn, cb_data);
1870 } else if (packed_dir) {
1871 sort_ref_dir(packed_dir);
1872 retval = do_for_each_entry_in_dir(
1873 packed_dir, 0, fn, cb_data);
1874 } else if (loose_dir) {
1875 sort_ref_dir(loose_dir);
1876 retval = do_for_each_entry_in_dir(
1877 loose_dir, 0, fn, cb_data);
1878 }
1879
1880 release_packed_ref_cache(packed_ref_cache);
1881 return retval;
1882}
1883
1884/*
1885 * Call fn for each reference in the specified ref_cache for which the
1886 * refname begins with base. If trim is non-zero, then trim that many
1887 * characters off the beginning of each refname before passing the
1888 * refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1889 * broken references in the iteration. If fn ever returns a non-zero
1890 * value, stop the iteration and return that value; otherwise, return
1891 * 0.
1892 */
93770590
DT
1893int do_for_each_ref(const char *submodule, const char *base,
1894 each_ref_fn fn, int trim, int flags, void *cb_data)
7bd9bcf3
MH
1895{
1896 struct ref_entry_cb data;
93770590
DT
1897 struct ref_cache *refs;
1898
1899 refs = get_ref_cache(submodule);
7bd9bcf3
MH
1900 data.base = base;
1901 data.trim = trim;
1902 data.flags = flags;
1903 data.fn = fn;
1904 data.cb_data = cb_data;
1905
1906 if (ref_paranoia < 0)
1907 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1908 if (ref_paranoia)
1909 data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1910
1911 return do_for_each_entry(refs, base, do_one_ref, &data);
1912}
1913
7bd9bcf3
MH
1914/*
1915 * Verify that the reference locked by lock has the value old_sha1.
1916 * Fail if the reference doesn't exist and mustexist is set. Return 0
1917 * on success. On error, write an error message to err, set errno, and
1918 * return a negative value.
1919 */
1920static int verify_lock(struct ref_lock *lock,
1921 const unsigned char *old_sha1, int mustexist,
1922 struct strbuf *err)
1923{
1924 assert(err);
1925
1926 if (read_ref_full(lock->ref_name,
1927 mustexist ? RESOLVE_REF_READING : 0,
1928 lock->old_oid.hash, NULL)) {
6294dcb4
JK
1929 if (old_sha1) {
1930 int save_errno = errno;
0568c8e9 1931 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
6294dcb4
JK
1932 errno = save_errno;
1933 return -1;
1934 } else {
1935 hashclr(lock->old_oid.hash);
1936 return 0;
1937 }
7bd9bcf3 1938 }
6294dcb4 1939 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
0568c8e9 1940 strbuf_addf(err, "ref '%s' is at %s but expected %s",
7bd9bcf3
MH
1941 lock->ref_name,
1942 sha1_to_hex(lock->old_oid.hash),
1943 sha1_to_hex(old_sha1));
1944 errno = EBUSY;
1945 return -1;
1946 }
1947 return 0;
1948}
1949
1950static int remove_empty_directories(struct strbuf *path)
1951{
1952 /*
1953 * we want to create a file but there is a directory there;
1954 * if that is an empty directory (or a directory that contains
1955 * only empty directories), remove them.
1956 */
1957 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
1958}
1959
1960/*
1961 * Locks a ref returning the lock on success and NULL on failure.
1962 * On failure errno is set to something meaningful.
1963 */
1964static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1965 const unsigned char *old_sha1,
1966 const struct string_list *extras,
1967 const struct string_list *skip,
bcb497d0 1968 unsigned int flags, int *type,
7bd9bcf3
MH
1969 struct strbuf *err)
1970{
1971 struct strbuf ref_file = STRBUF_INIT;
1972 struct strbuf orig_ref_file = STRBUF_INIT;
1973 const char *orig_refname = refname;
1974 struct ref_lock *lock;
1975 int last_errno = 0;
2859dcd4 1976 int lflags = 0;
7bd9bcf3
MH
1977 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1978 int resolve_flags = 0;
1979 int attempts_remaining = 3;
1980
1981 assert(err);
1982
1983 lock = xcalloc(1, sizeof(struct ref_lock));
1984
1985 if (mustexist)
1986 resolve_flags |= RESOLVE_REF_READING;
2859dcd4 1987 if (flags & REF_DELETING)
7bd9bcf3 1988 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
2859dcd4
JK
1989 if (flags & REF_NODEREF) {
1990 resolve_flags |= RESOLVE_REF_NO_RECURSE;
1991 lflags |= LOCK_NO_DEREF;
7bd9bcf3
MH
1992 }
1993
1994 refname = resolve_ref_unsafe(refname, resolve_flags,
bcb497d0 1995 lock->old_oid.hash, type);
7bd9bcf3
MH
1996 if (!refname && errno == EISDIR) {
1997 /*
1998 * we are trying to lock foo but we used to
1999 * have foo/bar which now does not exist;
2000 * it is normal for the empty directory 'foo'
2001 * to remain.
2002 */
2003 strbuf_git_path(&orig_ref_file, "%s", orig_refname);
2004 if (remove_empty_directories(&orig_ref_file)) {
2005 last_errno = errno;
2006 if (!verify_refname_available_dir(orig_refname, extras, skip,
2007 get_loose_refs(&ref_cache), err))
2008 strbuf_addf(err, "there are still refs under '%s'",
2009 orig_refname);
2010 goto error_return;
2011 }
2012 refname = resolve_ref_unsafe(orig_refname, resolve_flags,
bcb497d0 2013 lock->old_oid.hash, type);
7bd9bcf3 2014 }
7bd9bcf3
MH
2015 if (!refname) {
2016 last_errno = errno;
2017 if (last_errno != ENOTDIR ||
2018 !verify_refname_available_dir(orig_refname, extras, skip,
2019 get_loose_refs(&ref_cache), err))
0568c8e9 2020 strbuf_addf(err, "unable to resolve reference '%s': %s",
7bd9bcf3
MH
2021 orig_refname, strerror(last_errno));
2022
2023 goto error_return;
2024 }
2859dcd4
JK
2025
2026 if (flags & REF_NODEREF)
2027 refname = orig_refname;
2028
7bd9bcf3
MH
2029 /*
2030 * If the ref did not exist and we are creating it, make sure
2031 * there is no existing packed ref whose name begins with our
2032 * refname, nor a packed ref whose name is a proper prefix of
2033 * our refname.
2034 */
2035 if (is_null_oid(&lock->old_oid) &&
2036 verify_refname_available_dir(refname, extras, skip,
2037 get_packed_refs(&ref_cache), err)) {
2038 last_errno = ENOTDIR;
2039 goto error_return;
2040 }
2041
2042 lock->lk = xcalloc(1, sizeof(struct lock_file));
2043
7bd9bcf3
MH
2044 lock->ref_name = xstrdup(refname);
2045 lock->orig_ref_name = xstrdup(orig_refname);
2046 strbuf_git_path(&ref_file, "%s", refname);
2047
2048 retry:
2049 switch (safe_create_leading_directories_const(ref_file.buf)) {
2050 case SCLD_OK:
2051 break; /* success */
2052 case SCLD_VANISHED:
2053 if (--attempts_remaining > 0)
2054 goto retry;
2055 /* fall through */
2056 default:
2057 last_errno = errno;
0568c8e9 2058 strbuf_addf(err, "unable to create directory for '%s'",
7bd9bcf3
MH
2059 ref_file.buf);
2060 goto error_return;
2061 }
2062
2063 if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
2064 last_errno = errno;
2065 if (errno == ENOENT && --attempts_remaining > 0)
2066 /*
2067 * Maybe somebody just deleted one of the
2068 * directories leading to ref_file. Try
2069 * again:
2070 */
2071 goto retry;
2072 else {
2073 unable_to_lock_message(ref_file.buf, errno, err);
2074 goto error_return;
2075 }
2076 }
6294dcb4 2077 if (verify_lock(lock, old_sha1, mustexist, err)) {
7bd9bcf3
MH
2078 last_errno = errno;
2079 goto error_return;
2080 }
2081 goto out;
2082
2083 error_return:
2084 unlock_ref(lock);
2085 lock = NULL;
2086
2087 out:
2088 strbuf_release(&ref_file);
2089 strbuf_release(&orig_ref_file);
2090 errno = last_errno;
2091 return lock;
2092}
2093
2094/*
2095 * Write an entry to the packed-refs file for the specified refname.
2096 * If peeled is non-NULL, write it as the entry's peeled value.
2097 */
2098static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2099 unsigned char *peeled)
2100{
2101 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2102 if (peeled)
2103 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2104}
2105
2106/*
2107 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2108 */
2109static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2110{
2111 enum peel_status peel_status = peel_entry(entry, 0);
2112
2113 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2114 error("internal error: %s is not a valid packed reference!",
2115 entry->name);
2116 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2117 peel_status == PEEL_PEELED ?
2118 entry->u.value.peeled.hash : NULL);
2119 return 0;
2120}
2121
2122/*
2123 * Lock the packed-refs file for writing. Flags is passed to
2124 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2125 * errno appropriately and return a nonzero value.
2126 */
2127static int lock_packed_refs(int flags)
2128{
2129 static int timeout_configured = 0;
2130 static int timeout_value = 1000;
2131
2132 struct packed_ref_cache *packed_ref_cache;
2133
2134 if (!timeout_configured) {
2135 git_config_get_int("core.packedrefstimeout", &timeout_value);
2136 timeout_configured = 1;
2137 }
2138
2139 if (hold_lock_file_for_update_timeout(
2140 &packlock, git_path("packed-refs"),
2141 flags, timeout_value) < 0)
2142 return -1;
2143 /*
2144 * Get the current packed-refs while holding the lock. If the
2145 * packed-refs file has been modified since we last read it,
2146 * this will automatically invalidate the cache and re-read
2147 * the packed-refs file.
2148 */
2149 packed_ref_cache = get_packed_ref_cache(&ref_cache);
2150 packed_ref_cache->lock = &packlock;
2151 /* Increment the reference count to prevent it from being freed: */
2152 acquire_packed_ref_cache(packed_ref_cache);
2153 return 0;
2154}
2155
2156/*
2157 * Write the current version of the packed refs cache from memory to
2158 * disk. The packed-refs file must already be locked for writing (see
2159 * lock_packed_refs()). Return zero on success. On errors, set errno
2160 * and return a nonzero value
2161 */
2162static int commit_packed_refs(void)
2163{
2164 struct packed_ref_cache *packed_ref_cache =
2165 get_packed_ref_cache(&ref_cache);
2166 int error = 0;
2167 int save_errno = 0;
2168 FILE *out;
2169
2170 if (!packed_ref_cache->lock)
2171 die("internal error: packed-refs not locked");
2172
2173 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2174 if (!out)
2175 die_errno("unable to fdopen packed-refs descriptor");
2176
2177 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2178 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2179 0, write_packed_entry_fn, out);
2180
2181 if (commit_lock_file(packed_ref_cache->lock)) {
2182 save_errno = errno;
2183 error = -1;
2184 }
2185 packed_ref_cache->lock = NULL;
2186 release_packed_ref_cache(packed_ref_cache);
2187 errno = save_errno;
2188 return error;
2189}
2190
2191/*
2192 * Rollback the lockfile for the packed-refs file, and discard the
2193 * in-memory packed reference cache. (The packed-refs file will be
2194 * read anew if it is needed again after this function is called.)
2195 */
2196static void rollback_packed_refs(void)
2197{
2198 struct packed_ref_cache *packed_ref_cache =
2199 get_packed_ref_cache(&ref_cache);
2200
2201 if (!packed_ref_cache->lock)
2202 die("internal error: packed-refs not locked");
2203 rollback_lock_file(packed_ref_cache->lock);
2204 packed_ref_cache->lock = NULL;
2205 release_packed_ref_cache(packed_ref_cache);
2206 clear_packed_ref_cache(&ref_cache);
2207}
2208
2209struct ref_to_prune {
2210 struct ref_to_prune *next;
2211 unsigned char sha1[20];
2212 char name[FLEX_ARRAY];
2213};
2214
2215struct pack_refs_cb_data {
2216 unsigned int flags;
2217 struct ref_dir *packed_refs;
2218 struct ref_to_prune *ref_to_prune;
2219};
2220
2221/*
2222 * An each_ref_entry_fn that is run over loose references only. If
2223 * the loose reference can be packed, add an entry in the packed ref
2224 * cache. If the reference should be pruned, also add it to
2225 * ref_to_prune in the pack_refs_cb_data.
2226 */
2227static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2228{
2229 struct pack_refs_cb_data *cb = cb_data;
2230 enum peel_status peel_status;
2231 struct ref_entry *packed_entry;
2232 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2233
2234 /* Do not pack per-worktree refs: */
2235 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2236 return 0;
2237
2238 /* ALWAYS pack tags */
2239 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2240 return 0;
2241
2242 /* Do not pack symbolic or broken refs: */
2243 if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2244 return 0;
2245
2246 /* Add a packed ref cache entry equivalent to the loose entry. */
2247 peel_status = peel_entry(entry, 1);
2248 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2249 die("internal error peeling reference %s (%s)",
2250 entry->name, oid_to_hex(&entry->u.value.oid));
2251 packed_entry = find_ref(cb->packed_refs, entry->name);
2252 if (packed_entry) {
2253 /* Overwrite existing packed entry with info from loose entry */
2254 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2255 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2256 } else {
2257 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2258 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2259 add_ref(cb->packed_refs, packed_entry);
2260 }
2261 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2262
2263 /* Schedule the loose reference for pruning if requested. */
2264 if ((cb->flags & PACK_REFS_PRUNE)) {
96ffc06f
JK
2265 struct ref_to_prune *n;
2266 FLEX_ALLOC_STR(n, name, entry->name);
7bd9bcf3 2267 hashcpy(n->sha1, entry->u.value.oid.hash);
7bd9bcf3
MH
2268 n->next = cb->ref_to_prune;
2269 cb->ref_to_prune = n;
2270 }
2271 return 0;
2272}
2273
2274/*
2275 * Remove empty parents, but spare refs/ and immediate subdirs.
2276 * Note: munges *name.
2277 */
2278static void try_remove_empty_parents(char *name)
2279{
2280 char *p, *q;
2281 int i;
2282 p = name;
2283 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2284 while (*p && *p != '/')
2285 p++;
2286 /* tolerate duplicate slashes; see check_refname_format() */
2287 while (*p == '/')
2288 p++;
2289 }
2290 for (q = p; *q; q++)
2291 ;
2292 while (1) {
2293 while (q > p && *q != '/')
2294 q--;
2295 while (q > p && *(q-1) == '/')
2296 q--;
2297 if (q == p)
2298 break;
2299 *q = '\0';
2300 if (rmdir(git_path("%s", name)))
2301 break;
2302 }
2303}
2304
2305/* make sure nobody touched the ref, and unlink */
2306static void prune_ref(struct ref_to_prune *r)
2307{
2308 struct ref_transaction *transaction;
2309 struct strbuf err = STRBUF_INIT;
2310
2311 if (check_refname_format(r->name, 0))
2312 return;
2313
2314 transaction = ref_transaction_begin(&err);
2315 if (!transaction ||
2316 ref_transaction_delete(transaction, r->name, r->sha1,
c52ce248 2317 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
7bd9bcf3
MH
2318 ref_transaction_commit(transaction, &err)) {
2319 ref_transaction_free(transaction);
2320 error("%s", err.buf);
2321 strbuf_release(&err);
2322 return;
2323 }
2324 ref_transaction_free(transaction);
2325 strbuf_release(&err);
2326 try_remove_empty_parents(r->name);
2327}
2328
2329static void prune_refs(struct ref_to_prune *r)
2330{
2331 while (r) {
2332 prune_ref(r);
2333 r = r->next;
2334 }
2335}
2336
2337int pack_refs(unsigned int flags)
2338{
2339 struct pack_refs_cb_data cbdata;
2340
2341 memset(&cbdata, 0, sizeof(cbdata));
2342 cbdata.flags = flags;
2343
2344 lock_packed_refs(LOCK_DIE_ON_ERROR);
2345 cbdata.packed_refs = get_packed_refs(&ref_cache);
2346
2347 do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2348 pack_if_possible_fn, &cbdata);
2349
2350 if (commit_packed_refs())
2351 die_errno("unable to overwrite old ref-pack file");
2352
2353 prune_refs(cbdata.ref_to_prune);
2354 return 0;
2355}
2356
2357/*
2358 * Rewrite the packed-refs file, omitting any refs listed in
2359 * 'refnames'. On error, leave packed-refs unchanged, write an error
2360 * message to 'err', and return a nonzero value.
2361 *
2362 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2363 */
2364static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
2365{
2366 struct ref_dir *packed;
2367 struct string_list_item *refname;
2368 int ret, needs_repacking = 0, removed = 0;
2369
2370 assert(err);
2371
2372 /* Look for a packed ref */
2373 for_each_string_list_item(refname, refnames) {
2374 if (get_packed_ref(refname->string)) {
2375 needs_repacking = 1;
2376 break;
2377 }
2378 }
2379
2380 /* Avoid locking if we have nothing to do */
2381 if (!needs_repacking)
2382 return 0; /* no refname exists in packed refs */
2383
2384 if (lock_packed_refs(0)) {
2385 unable_to_lock_message(git_path("packed-refs"), errno, err);
2386 return -1;
2387 }
2388 packed = get_packed_refs(&ref_cache);
2389
2390 /* Remove refnames from the cache */
2391 for_each_string_list_item(refname, refnames)
2392 if (remove_entry(packed, refname->string) != -1)
2393 removed = 1;
2394 if (!removed) {
2395 /*
2396 * All packed entries disappeared while we were
2397 * acquiring the lock.
2398 */
2399 rollback_packed_refs();
2400 return 0;
2401 }
2402
2403 /* Write what remains */
2404 ret = commit_packed_refs();
2405 if (ret)
2406 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2407 strerror(errno));
2408 return ret;
2409}
2410
2411static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2412{
2413 assert(err);
2414
2415 if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2416 /*
2417 * loose. The loose file name is the same as the
2418 * lockfile name, minus ".lock":
2419 */
2420 char *loose_filename = get_locked_file_path(lock->lk);
2421 int res = unlink_or_msg(loose_filename, err);
2422 free(loose_filename);
2423 if (res)
2424 return 1;
2425 }
2426 return 0;
2427}
2428
2429int delete_refs(struct string_list *refnames)
2430{
2431 struct strbuf err = STRBUF_INIT;
2432 int i, result = 0;
2433
2434 if (!refnames->nr)
2435 return 0;
2436
2437 result = repack_without_refs(refnames, &err);
2438 if (result) {
2439 /*
2440 * If we failed to rewrite the packed-refs file, then
2441 * it is unsafe to try to remove loose refs, because
2442 * doing so might expose an obsolete packed value for
2443 * a reference that might even point at an object that
2444 * has been garbage collected.
2445 */
2446 if (refnames->nr == 1)
2447 error(_("could not delete reference %s: %s"),
2448 refnames->items[0].string, err.buf);
2449 else
2450 error(_("could not delete references: %s"), err.buf);
2451
2452 goto out;
2453 }
2454
2455 for (i = 0; i < refnames->nr; i++) {
2456 const char *refname = refnames->items[i].string;
2457
2458 if (delete_ref(refname, NULL, 0))
2459 result |= error(_("could not remove reference %s"), refname);
2460 }
2461
2462out:
2463 strbuf_release(&err);
2464 return result;
2465}
2466
2467/*
2468 * People using contrib's git-new-workdir have .git/logs/refs ->
2469 * /some/other/path/.git/logs/refs, and that may live on another device.
2470 *
2471 * IOW, to avoid cross device rename errors, the temporary renamed log must
2472 * live into logs/refs.
2473 */
2474#define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
2475
2476static int rename_tmp_log(const char *newrefname)
2477{
2478 int attempts_remaining = 4;
2479 struct strbuf path = STRBUF_INIT;
2480 int ret = -1;
2481
2482 retry:
2483 strbuf_reset(&path);
2484 strbuf_git_path(&path, "logs/%s", newrefname);
2485 switch (safe_create_leading_directories_const(path.buf)) {
2486 case SCLD_OK:
2487 break; /* success */
2488 case SCLD_VANISHED:
2489 if (--attempts_remaining > 0)
2490 goto retry;
2491 /* fall through */
2492 default:
2493 error("unable to create directory for %s", newrefname);
2494 goto out;
2495 }
2496
2497 if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
2498 if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2499 /*
2500 * rename(a, b) when b is an existing
2501 * directory ought to result in ISDIR, but
2502 * Solaris 5.8 gives ENOTDIR. Sheesh.
2503 */
2504 if (remove_empty_directories(&path)) {
2505 error("Directory not empty: logs/%s", newrefname);
2506 goto out;
2507 }
2508 goto retry;
2509 } else if (errno == ENOENT && --attempts_remaining > 0) {
2510 /*
2511 * Maybe another process just deleted one of
2512 * the directories in the path to newrefname.
2513 * Try again from the beginning.
2514 */
2515 goto retry;
2516 } else {
2517 error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2518 newrefname, strerror(errno));
2519 goto out;
2520 }
2521 }
2522 ret = 0;
2523out:
2524 strbuf_release(&path);
2525 return ret;
2526}
2527
2528int verify_refname_available(const char *newname,
3a8af7be
MH
2529 const struct string_list *extras,
2530 const struct string_list *skip,
7bd9bcf3
MH
2531 struct strbuf *err)
2532{
2533 struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
2534 struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
2535
2536 if (verify_refname_available_dir(newname, extras, skip,
2537 packed_refs, err) ||
2538 verify_refname_available_dir(newname, extras, skip,
2539 loose_refs, err))
2540 return -1;
2541
2542 return 0;
2543}
2544
7bd9bcf3
MH
2545static int write_ref_to_lockfile(struct ref_lock *lock,
2546 const unsigned char *sha1, struct strbuf *err);
2547static int commit_ref_update(struct ref_lock *lock,
2548 const unsigned char *sha1, const char *logmsg,
5d9b2de4 2549 struct strbuf *err);
7bd9bcf3
MH
2550
2551int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2552{
2553 unsigned char sha1[20], orig_sha1[20];
2554 int flag = 0, logmoved = 0;
2555 struct ref_lock *lock;
2556 struct stat loginfo;
2557 int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
7bd9bcf3
MH
2558 struct strbuf err = STRBUF_INIT;
2559
2560 if (log && S_ISLNK(loginfo.st_mode))
2561 return error("reflog for %s is a symlink", oldrefname);
2562
12fd3496
DT
2563 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2564 orig_sha1, &flag))
e711b1af
MH
2565 return error("refname %s not found", oldrefname);
2566
7bd9bcf3
MH
2567 if (flag & REF_ISSYMREF)
2568 return error("refname %s is a symbolic ref, renaming it is not supported",
2569 oldrefname);
7bd9bcf3
MH
2570 if (!rename_ref_available(oldrefname, newrefname))
2571 return 1;
2572
2573 if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2574 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2575 oldrefname, strerror(errno));
2576
2577 if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2578 error("unable to delete old %s", oldrefname);
2579 goto rollback;
2580 }
2581
12fd3496
DT
2582 /*
2583 * Since we are doing a shallow lookup, sha1 is not the
2584 * correct value to pass to delete_ref as old_sha1. But that
2585 * doesn't matter, because an old_sha1 check wouldn't add to
2586 * the safety anyway; we want to delete the reference whatever
2587 * its current value.
2588 */
2589 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2590 sha1, NULL) &&
2591 delete_ref(newrefname, NULL, REF_NODEREF)) {
7bd9bcf3
MH
2592 if (errno==EISDIR) {
2593 struct strbuf path = STRBUF_INIT;
2594 int result;
2595
2596 strbuf_git_path(&path, "%s", newrefname);
2597 result = remove_empty_directories(&path);
2598 strbuf_release(&path);
2599
2600 if (result) {
2601 error("Directory not empty: %s", newrefname);
2602 goto rollback;
2603 }
2604 } else {
2605 error("unable to delete existing %s", newrefname);
2606 goto rollback;
2607 }
2608 }
2609
2610 if (log && rename_tmp_log(newrefname))
2611 goto rollback;
2612
2613 logmoved = log;
2614
12fd3496
DT
2615 lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, REF_NODEREF,
2616 NULL, &err);
7bd9bcf3
MH
2617 if (!lock) {
2618 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2619 strbuf_release(&err);
2620 goto rollback;
2621 }
2622 hashcpy(lock->old_oid.hash, orig_sha1);
2623
2624 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2625 commit_ref_update(lock, orig_sha1, logmsg, &err)) {
7bd9bcf3
MH
2626 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2627 strbuf_release(&err);
2628 goto rollback;
2629 }
2630
2631 return 0;
2632
2633 rollback:
12fd3496
DT
2634 lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, REF_NODEREF,
2635 NULL, &err);
7bd9bcf3
MH
2636 if (!lock) {
2637 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2638 strbuf_release(&err);
2639 goto rollbacklog;
2640 }
2641
2642 flag = log_all_ref_updates;
2643 log_all_ref_updates = 0;
2644 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2645 commit_ref_update(lock, orig_sha1, NULL, &err)) {
7bd9bcf3
MH
2646 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2647 strbuf_release(&err);
2648 }
2649 log_all_ref_updates = flag;
2650
2651 rollbacklog:
2652 if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2653 error("unable to restore logfile %s from %s: %s",
2654 oldrefname, newrefname, strerror(errno));
2655 if (!logmoved && log &&
2656 rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2657 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2658 oldrefname, strerror(errno));
2659
2660 return 1;
2661}
2662
2663static int close_ref(struct ref_lock *lock)
2664{
2665 if (close_lock_file(lock->lk))
2666 return -1;
2667 return 0;
2668}
2669
2670static int commit_ref(struct ref_lock *lock)
2671{
5387c0d8
MH
2672 char *path = get_locked_file_path(lock->lk);
2673 struct stat st;
2674
2675 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2676 /*
2677 * There is a directory at the path we want to rename
2678 * the lockfile to. Hopefully it is empty; try to
2679 * delete it.
2680 */
2681 size_t len = strlen(path);
2682 struct strbuf sb_path = STRBUF_INIT;
2683
2684 strbuf_attach(&sb_path, path, len, len);
2685
2686 /*
2687 * If this fails, commit_lock_file() will also fail
2688 * and will report the problem.
2689 */
2690 remove_empty_directories(&sb_path);
2691 strbuf_release(&sb_path);
2692 } else {
2693 free(path);
2694 }
2695
7bd9bcf3
MH
2696 if (commit_lock_file(lock->lk))
2697 return -1;
2698 return 0;
2699}
2700
2701/*
2702 * Create a reflog for a ref. If force_create = 0, the reflog will
2703 * only be created for certain refs (those for which
2704 * should_autocreate_reflog returns non-zero. Otherwise, create it
2705 * regardless of the ref name. Fill in *err and return -1 on failure.
2706 */
2707static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
2708{
2709 int logfd, oflags = O_APPEND | O_WRONLY;
2710
2711 strbuf_git_path(logfile, "logs/%s", refname);
2712 if (force_create || should_autocreate_reflog(refname)) {
2713 if (safe_create_leading_directories(logfile->buf) < 0) {
0568c8e9 2714 strbuf_addf(err, "unable to create directory for '%s': "
7bd9bcf3
MH
2715 "%s", logfile->buf, strerror(errno));
2716 return -1;
2717 }
2718 oflags |= O_CREAT;
2719 }
2720
2721 logfd = open(logfile->buf, oflags, 0666);
2722 if (logfd < 0) {
2723 if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
2724 return 0;
2725
2726 if (errno == EISDIR) {
2727 if (remove_empty_directories(logfile)) {
0568c8e9 2728 strbuf_addf(err, "there are still logs under "
7bd9bcf3
MH
2729 "'%s'", logfile->buf);
2730 return -1;
2731 }
2732 logfd = open(logfile->buf, oflags, 0666);
2733 }
2734
2735 if (logfd < 0) {
0568c8e9 2736 strbuf_addf(err, "unable to append to '%s': %s",
7bd9bcf3
MH
2737 logfile->buf, strerror(errno));
2738 return -1;
2739 }
2740 }
2741
2742 adjust_shared_perm(logfile->buf);
2743 close(logfd);
2744 return 0;
2745}
2746
2747
2748int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
2749{
2750 int ret;
2751 struct strbuf sb = STRBUF_INIT;
2752
2753 ret = log_ref_setup(refname, &sb, err, force_create);
2754 strbuf_release(&sb);
2755 return ret;
2756}
2757
2758static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2759 const unsigned char *new_sha1,
2760 const char *committer, const char *msg)
2761{
2762 int msglen, written;
2763 unsigned maxlen, len;
2764 char *logrec;
2765
2766 msglen = msg ? strlen(msg) : 0;
2767 maxlen = strlen(committer) + msglen + 100;
2768 logrec = xmalloc(maxlen);
2769 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2770 sha1_to_hex(old_sha1),
2771 sha1_to_hex(new_sha1),
2772 committer);
2773 if (msglen)
2774 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2775
2776 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2777 free(logrec);
2778 if (written != len)
2779 return -1;
2780
2781 return 0;
2782}
2783
2784static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
2785 const unsigned char *new_sha1, const char *msg,
2786 struct strbuf *logfile, int flags,
2787 struct strbuf *err)
2788{
2789 int logfd, result, oflags = O_APPEND | O_WRONLY;
2790
2791 if (log_all_ref_updates < 0)
2792 log_all_ref_updates = !is_bare_repository();
2793
2794 result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
2795
2796 if (result)
2797 return result;
2798
2799 logfd = open(logfile->buf, oflags);
2800 if (logfd < 0)
2801 return 0;
2802 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2803 git_committer_info(0), msg);
2804 if (result) {
0568c8e9 2805 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
2806 strerror(errno));
2807 close(logfd);
2808 return -1;
2809 }
2810 if (close(logfd)) {
0568c8e9 2811 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
2812 strerror(errno));
2813 return -1;
2814 }
2815 return 0;
2816}
2817
2818static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2819 const unsigned char *new_sha1, const char *msg,
2820 int flags, struct strbuf *err)
5f3c3a4e
DT
2821{
2822 return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
2823 err);
2824}
2825
2826int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
2827 const unsigned char *new_sha1, const char *msg,
2828 int flags, struct strbuf *err)
7bd9bcf3
MH
2829{
2830 struct strbuf sb = STRBUF_INIT;
2831 int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
2832 err);
2833 strbuf_release(&sb);
2834 return ret;
2835}
2836
2837/*
2838 * Write sha1 into the open lockfile, then close the lockfile. On
2839 * errors, rollback the lockfile, fill in *err and
2840 * return -1.
2841 */
2842static int write_ref_to_lockfile(struct ref_lock *lock,
2843 const unsigned char *sha1, struct strbuf *err)
2844{
2845 static char term = '\n';
2846 struct object *o;
2847 int fd;
2848
2849 o = parse_object(sha1);
2850 if (!o) {
2851 strbuf_addf(err,
0568c8e9 2852 "trying to write ref '%s' with nonexistent object %s",
7bd9bcf3
MH
2853 lock->ref_name, sha1_to_hex(sha1));
2854 unlock_ref(lock);
2855 return -1;
2856 }
2857 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2858 strbuf_addf(err,
0568c8e9 2859 "trying to write non-commit object %s to branch '%s'",
7bd9bcf3
MH
2860 sha1_to_hex(sha1), lock->ref_name);
2861 unlock_ref(lock);
2862 return -1;
2863 }
2864 fd = get_lock_file_fd(lock->lk);
2865 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
2866 write_in_full(fd, &term, 1) != 1 ||
2867 close_ref(lock) < 0) {
2868 strbuf_addf(err,
0568c8e9 2869 "couldn't write '%s'", get_lock_file_path(lock->lk));
7bd9bcf3
MH
2870 unlock_ref(lock);
2871 return -1;
2872 }
2873 return 0;
2874}
2875
2876/*
2877 * Commit a change to a loose reference that has already been written
2878 * to the loose reference lockfile. Also update the reflogs if
2879 * necessary, using the specified lockmsg (which can be NULL).
2880 */
2881static int commit_ref_update(struct ref_lock *lock,
2882 const unsigned char *sha1, const char *logmsg,
5d9b2de4 2883 struct strbuf *err)
7bd9bcf3
MH
2884{
2885 clear_loose_ref_cache(&ref_cache);
5d9b2de4 2886 if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err) < 0 ||
7bd9bcf3 2887 (strcmp(lock->ref_name, lock->orig_ref_name) &&
5d9b2de4 2888 log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, 0, err) < 0)) {
7bd9bcf3 2889 char *old_msg = strbuf_detach(err, NULL);
0568c8e9 2890 strbuf_addf(err, "cannot update the ref '%s': %s",
7bd9bcf3
MH
2891 lock->ref_name, old_msg);
2892 free(old_msg);
2893 unlock_ref(lock);
2894 return -1;
2895 }
2896 if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
2897 /*
2898 * Special hack: If a branch is updated directly and HEAD
2899 * points to it (may happen on the remote side of a push
2900 * for example) then logically the HEAD reflog should be
2901 * updated too.
2902 * A generic solution implies reverse symref information,
2903 * but finding all symrefs pointing to the given branch
2904 * would be rather costly for this rare event (the direct
2905 * update of a branch) to be worth it. So let's cheat and
2906 * check with HEAD only which should cover 99% of all usage
2907 * scenarios (even 100% of the default ones).
2908 */
2909 unsigned char head_sha1[20];
2910 int head_flag;
2911 const char *head_ref;
2912 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
2913 head_sha1, &head_flag);
2914 if (head_ref && (head_flag & REF_ISSYMREF) &&
2915 !strcmp(head_ref, lock->ref_name)) {
2916 struct strbuf log_err = STRBUF_INIT;
2917 if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
2918 logmsg, 0, &log_err)) {
2919 error("%s", log_err.buf);
2920 strbuf_release(&log_err);
2921 }
2922 }
2923 }
5d9b2de4 2924 if (commit_ref(lock)) {
0568c8e9 2925 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
7bd9bcf3
MH
2926 unlock_ref(lock);
2927 return -1;
2928 }
2929
2930 unlock_ref(lock);
2931 return 0;
2932}
2933
370e5ad6 2934static int create_ref_symlink(struct ref_lock *lock, const char *target)
7bd9bcf3 2935{
370e5ad6 2936 int ret = -1;
7bd9bcf3 2937#ifndef NO_SYMLINK_HEAD
370e5ad6
JK
2938 char *ref_path = get_locked_file_path(lock->lk);
2939 unlink(ref_path);
2940 ret = symlink(target, ref_path);
2941 free(ref_path);
2942
2943 if (ret)
7bd9bcf3 2944 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
7bd9bcf3 2945#endif
370e5ad6
JK
2946 return ret;
2947}
7bd9bcf3 2948
370e5ad6
JK
2949static void update_symref_reflog(struct ref_lock *lock, const char *refname,
2950 const char *target, const char *logmsg)
2951{
2952 struct strbuf err = STRBUF_INIT;
2953 unsigned char new_sha1[20];
b9badadd 2954 if (logmsg && !read_ref(target, new_sha1) &&
370e5ad6 2955 log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
7bd9bcf3
MH
2956 error("%s", err.buf);
2957 strbuf_release(&err);
2958 }
370e5ad6 2959}
7bd9bcf3 2960
370e5ad6
JK
2961static int create_symref_locked(struct ref_lock *lock, const char *refname,
2962 const char *target, const char *logmsg)
2963{
2964 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
2965 update_symref_reflog(lock, refname, target, logmsg);
2966 return 0;
2967 }
2968
2969 if (!fdopen_lock_file(lock->lk, "w"))
2970 return error("unable to fdopen %s: %s",
2971 lock->lk->tempfile.filename.buf, strerror(errno));
2972
396da8f7
JK
2973 update_symref_reflog(lock, refname, target, logmsg);
2974
370e5ad6
JK
2975 /* no error check; commit_ref will check ferror */
2976 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
2977 if (commit_ref(lock) < 0)
2978 return error("unable to write symref for %s: %s", refname,
2979 strerror(errno));
7bd9bcf3
MH
2980 return 0;
2981}
2982
370e5ad6
JK
2983int create_symref(const char *refname, const char *target, const char *logmsg)
2984{
2985 struct strbuf err = STRBUF_INIT;
2986 struct ref_lock *lock;
2987 int ret;
2988
2989 lock = lock_ref_sha1_basic(refname, NULL, NULL, NULL, REF_NODEREF, NULL,
2990 &err);
2991 if (!lock) {
2992 error("%s", err.buf);
2993 strbuf_release(&err);
2994 return -1;
2995 }
2996
2997 ret = create_symref_locked(lock, refname, target, logmsg);
2998 unlock_ref(lock);
2999 return ret;
3000}
3001
2233066e
KY
3002int set_worktree_head_symref(const char *gitdir, const char *target)
3003{
3004 static struct lock_file head_lock;
3005 struct ref_lock *lock;
2233066e
KY
3006 struct strbuf head_path = STRBUF_INIT;
3007 const char *head_rel;
3008 int ret;
3009
3010 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3011 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3012 LOCK_NO_DEREF) < 0) {
18eb3a9c
KY
3013 struct strbuf err = STRBUF_INIT;
3014 unable_to_lock_message(head_path.buf, errno, &err);
2233066e
KY
3015 error("%s", err.buf);
3016 strbuf_release(&err);
3017 strbuf_release(&head_path);
3018 return -1;
3019 }
3020
3021 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3022 linked trees */
3023 head_rel = remove_leading_path(head_path.buf,
3024 absolute_path(get_git_common_dir()));
3025 /* to make use of create_symref_locked(), initialize ref_lock */
3026 lock = xcalloc(1, sizeof(struct ref_lock));
3027 lock->lk = &head_lock;
3028 lock->ref_name = xstrdup(head_rel);
3029 lock->orig_ref_name = xstrdup(head_rel);
3030
3031 ret = create_symref_locked(lock, head_rel, target, NULL);
3032
3033 unlock_ref(lock); /* will free lock */
3034 strbuf_release(&head_path);
3035 return ret;
3036}
3037
7bd9bcf3
MH
3038int reflog_exists(const char *refname)
3039{
3040 struct stat st;
3041
3042 return !lstat(git_path("logs/%s", refname), &st) &&
3043 S_ISREG(st.st_mode);
3044}
3045
3046int delete_reflog(const char *refname)
3047{
3048 return remove_path(git_path("logs/%s", refname));
3049}
3050
3051static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3052{
3053 unsigned char osha1[20], nsha1[20];
3054 char *email_end, *message;
3055 unsigned long timestamp;
3056 int tz;
3057
3058 /* old SP new SP name <email> SP time TAB msg LF */
3059 if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3060 get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3061 get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3062 !(email_end = strchr(sb->buf + 82, '>')) ||
3063 email_end[1] != ' ' ||
3064 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3065 !message || message[0] != ' ' ||
3066 (message[1] != '+' && message[1] != '-') ||
3067 !isdigit(message[2]) || !isdigit(message[3]) ||
3068 !isdigit(message[4]) || !isdigit(message[5]))
3069 return 0; /* corrupt? */
3070 email_end[1] = '\0';
3071 tz = strtol(message + 1, NULL, 10);
3072 if (message[6] != '\t')
3073 message += 6;
3074 else
3075 message += 7;
3076 return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3077}
3078
3079static char *find_beginning_of_line(char *bob, char *scan)
3080{
3081 while (bob < scan && *(--scan) != '\n')
3082 ; /* keep scanning backwards */
3083 /*
3084 * Return either beginning of the buffer, or LF at the end of
3085 * the previous line.
3086 */
3087 return scan;
3088}
3089
3090int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3091{
3092 struct strbuf sb = STRBUF_INIT;
3093 FILE *logfp;
3094 long pos;
3095 int ret = 0, at_tail = 1;
3096
3097 logfp = fopen(git_path("logs/%s", refname), "r");
3098 if (!logfp)
3099 return -1;
3100
3101 /* Jump to the end */
3102 if (fseek(logfp, 0, SEEK_END) < 0)
3103 return error("cannot seek back reflog for %s: %s",
3104 refname, strerror(errno));
3105 pos = ftell(logfp);
3106 while (!ret && 0 < pos) {
3107 int cnt;
3108 size_t nread;
3109 char buf[BUFSIZ];
3110 char *endp, *scanp;
3111
3112 /* Fill next block from the end */
3113 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3114 if (fseek(logfp, pos - cnt, SEEK_SET))
3115 return error("cannot seek back reflog for %s: %s",
3116 refname, strerror(errno));
3117 nread = fread(buf, cnt, 1, logfp);
3118 if (nread != 1)
3119 return error("cannot read %d bytes from reflog for %s: %s",
3120 cnt, refname, strerror(errno));
3121 pos -= cnt;
3122
3123 scanp = endp = buf + cnt;
3124 if (at_tail && scanp[-1] == '\n')
3125 /* Looking at the final LF at the end of the file */
3126 scanp--;
3127 at_tail = 0;
3128
3129 while (buf < scanp) {
3130 /*
3131 * terminating LF of the previous line, or the beginning
3132 * of the buffer.
3133 */
3134 char *bp;
3135
3136 bp = find_beginning_of_line(buf, scanp);
3137
3138 if (*bp == '\n') {
3139 /*
3140 * The newline is the end of the previous line,
3141 * so we know we have complete line starting
3142 * at (bp + 1). Prefix it onto any prior data
3143 * we collected for the line and process it.
3144 */
3145 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3146 scanp = bp;
3147 endp = bp + 1;
3148 ret = show_one_reflog_ent(&sb, fn, cb_data);
3149 strbuf_reset(&sb);
3150 if (ret)
3151 break;
3152 } else if (!pos) {
3153 /*
3154 * We are at the start of the buffer, and the
3155 * start of the file; there is no previous
3156 * line, and we have everything for this one.
3157 * Process it, and we can end the loop.
3158 */
3159 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3160 ret = show_one_reflog_ent(&sb, fn, cb_data);
3161 strbuf_reset(&sb);
3162 break;
3163 }
3164
3165 if (bp == buf) {
3166 /*
3167 * We are at the start of the buffer, and there
3168 * is more file to read backwards. Which means
3169 * we are in the middle of a line. Note that we
3170 * may get here even if *bp was a newline; that
3171 * just means we are at the exact end of the
3172 * previous line, rather than some spot in the
3173 * middle.
3174 *
3175 * Save away what we have to be combined with
3176 * the data from the next read.
3177 */
3178 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3179 break;
3180 }
3181 }
3182
3183 }
3184 if (!ret && sb.len)
3185 die("BUG: reverse reflog parser had leftover data");
3186
3187 fclose(logfp);
3188 strbuf_release(&sb);
3189 return ret;
3190}
3191
3192int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3193{
3194 FILE *logfp;
3195 struct strbuf sb = STRBUF_INIT;
3196 int ret = 0;
3197
3198 logfp = fopen(git_path("logs/%s", refname), "r");
3199 if (!logfp)
3200 return -1;
3201
3202 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3203 ret = show_one_reflog_ent(&sb, fn, cb_data);
3204 fclose(logfp);
3205 strbuf_release(&sb);
3206 return ret;
3207}
3208/*
3209 * Call fn for each reflog in the namespace indicated by name. name
3210 * must be empty or end with '/'. Name will be used as a scratch
3211 * space, but its contents will be restored before return.
3212 */
3213static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3214{
3215 DIR *d = opendir(git_path("logs/%s", name->buf));
3216 int retval = 0;
3217 struct dirent *de;
3218 int oldlen = name->len;
3219
3220 if (!d)
3221 return name->len ? errno : 0;
3222
3223 while ((de = readdir(d)) != NULL) {
3224 struct stat st;
3225
3226 if (de->d_name[0] == '.')
3227 continue;
3228 if (ends_with(de->d_name, ".lock"))
3229 continue;
3230 strbuf_addstr(name, de->d_name);
3231 if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3232 ; /* silently ignore */
3233 } else {
3234 if (S_ISDIR(st.st_mode)) {
3235 strbuf_addch(name, '/');
3236 retval = do_for_each_reflog(name, fn, cb_data);
3237 } else {
3238 struct object_id oid;
3239
3240 if (read_ref_full(name->buf, 0, oid.hash, NULL))
3241 retval = error("bad ref for %s", name->buf);
3242 else
3243 retval = fn(name->buf, &oid, 0, cb_data);
3244 }
3245 if (retval)
3246 break;
3247 }
3248 strbuf_setlen(name, oldlen);
3249 }
3250 closedir(d);
3251 return retval;
3252}
3253
3254int for_each_reflog(each_ref_fn fn, void *cb_data)
3255{
3256 int retval;
3257 struct strbuf name;
3258 strbuf_init(&name, PATH_MAX);
3259 retval = do_for_each_reflog(&name, fn, cb_data);
3260 strbuf_release(&name);
3261 return retval;
3262}
3263
3264static int ref_update_reject_duplicates(struct string_list *refnames,
3265 struct strbuf *err)
3266{
3267 int i, n = refnames->nr;
3268
3269 assert(err);
3270
3271 for (i = 1; i < n; i++)
3272 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3273 strbuf_addf(err,
0568c8e9 3274 "multiple updates for ref '%s' not allowed.",
7bd9bcf3
MH
3275 refnames->items[i].string);
3276 return 1;
3277 }
3278 return 0;
3279}
3280
165056b2 3281/*
92b1551b
MH
3282 * If update is a direct update of head_ref (the reference pointed to
3283 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3284 */
3285static int split_head_update(struct ref_update *update,
3286 struct ref_transaction *transaction,
3287 const char *head_ref,
3288 struct string_list *affected_refnames,
3289 struct strbuf *err)
3290{
3291 struct string_list_item *item;
3292 struct ref_update *new_update;
3293
3294 if ((update->flags & REF_LOG_ONLY) ||
3295 (update->flags & REF_ISPRUNING) ||
3296 (update->flags & REF_UPDATE_VIA_HEAD))
3297 return 0;
3298
3299 if (strcmp(update->refname, head_ref))
3300 return 0;
3301
3302 /*
3303 * First make sure that HEAD is not already in the
3304 * transaction. This insertion is O(N) in the transaction
3305 * size, but it happens at most once per transaction.
3306 */
3307 item = string_list_insert(affected_refnames, "HEAD");
3308 if (item->util) {
3309 /* An entry already existed */
3310 strbuf_addf(err,
3311 "multiple updates for 'HEAD' (including one "
3312 "via its referent '%s') are not allowed",
3313 update->refname);
3314 return TRANSACTION_NAME_CONFLICT;
3315 }
3316
3317 new_update = ref_transaction_add_update(
3318 transaction, "HEAD",
3319 update->flags | REF_LOG_ONLY | REF_NODEREF,
3320 update->new_sha1, update->old_sha1,
3321 update->msg);
3322
3323 item->util = new_update;
3324
3325 return 0;
3326}
3327
3328/*
3329 * update is for a symref that points at referent and doesn't have
3330 * REF_NODEREF set. Split it into two updates:
3331 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3332 * - A new, separate update for the referent reference
3333 * Note that the new update will itself be subject to splitting when
3334 * the iteration gets to it.
3335 */
3336static int split_symref_update(struct ref_update *update,
3337 const char *referent,
3338 struct ref_transaction *transaction,
3339 struct string_list *affected_refnames,
3340 struct strbuf *err)
3341{
3342 struct string_list_item *item;
3343 struct ref_update *new_update;
3344 unsigned int new_flags;
3345
3346 /*
3347 * First make sure that referent is not already in the
3348 * transaction. This insertion is O(N) in the transaction
3349 * size, but it happens at most once per symref in a
3350 * transaction.
3351 */
3352 item = string_list_insert(affected_refnames, referent);
3353 if (item->util) {
3354 /* An entry already existed */
3355 strbuf_addf(err,
3356 "multiple updates for '%s' (including one "
3357 "via symref '%s') are not allowed",
3358 referent, update->refname);
3359 return TRANSACTION_NAME_CONFLICT;
3360 }
3361
3362 new_flags = update->flags;
3363 if (!strcmp(update->refname, "HEAD")) {
3364 /*
3365 * Record that the new update came via HEAD, so that
3366 * when we process it, split_head_update() doesn't try
3367 * to add another reflog update for HEAD. Note that
3368 * this bit will be propagated if the new_update
3369 * itself needs to be split.
3370 */
3371 new_flags |= REF_UPDATE_VIA_HEAD;
3372 }
3373
3374 new_update = ref_transaction_add_update(
3375 transaction, referent, new_flags,
3376 update->new_sha1, update->old_sha1,
3377 update->msg);
3378
6e30b2f6
MH
3379 new_update->parent_update = update;
3380
3381 /*
3382 * Change the symbolic ref update to log only. Also, it
3383 * doesn't need to check its old SHA-1 value, as that will be
3384 * done when new_update is processed.
3385 */
92b1551b 3386 update->flags |= REF_LOG_ONLY | REF_NODEREF;
6e30b2f6 3387 update->flags &= ~REF_HAVE_OLD;
92b1551b
MH
3388
3389 item->util = new_update;
3390
3391 return 0;
3392}
3393
6e30b2f6
MH
3394/*
3395 * Return the refname under which update was originally requested.
3396 */
3397static const char *original_update_refname(struct ref_update *update)
3398{
3399 while (update->parent_update)
3400 update = update->parent_update;
3401
3402 return update->refname;
3403}
3404
92b1551b
MH
3405/*
3406 * Prepare for carrying out update:
3407 * - Lock the reference referred to by update.
3408 * - Read the reference under lock.
3409 * - Check that its old SHA-1 value (if specified) is correct, and in
3410 * any case record it in update->lock->old_oid for later use when
3411 * writing the reflog.
3412 * - If it is a symref update without REF_NODEREF, split it up into a
3413 * REF_LOG_ONLY update of the symref and add a separate update for
3414 * the referent to transaction.
3415 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3416 * update of HEAD.
165056b2
MH
3417 */
3418static int lock_ref_for_update(struct ref_update *update,
3419 struct ref_transaction *transaction,
92b1551b 3420 const char *head_ref,
165056b2
MH
3421 struct string_list *affected_refnames,
3422 struct strbuf *err)
3423{
92b1551b
MH
3424 struct strbuf referent = STRBUF_INIT;
3425 int mustexist = (update->flags & REF_HAVE_OLD) &&
3426 !is_null_sha1(update->old_sha1);
165056b2 3427 int ret;
92b1551b 3428 struct ref_lock *lock;
165056b2 3429
92b1551b 3430 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
165056b2 3431 update->flags |= REF_DELETING;
92b1551b
MH
3432
3433 if (head_ref) {
3434 ret = split_head_update(update, transaction, head_ref,
3435 affected_refnames, err);
3436 if (ret)
3437 return ret;
3438 }
3439
3440 ret = lock_raw_ref(update->refname, mustexist,
3441 affected_refnames, NULL,
3442 &update->lock, &referent,
3443 &update->type, err);
3444
3445 if (ret) {
165056b2
MH
3446 char *reason;
3447
165056b2
MH
3448 reason = strbuf_detach(err, NULL);
3449 strbuf_addf(err, "cannot lock ref '%s': %s",
3450 update->refname, reason);
3451 free(reason);
3452 return ret;
3453 }
92b1551b
MH
3454
3455 lock = update->lock;
3456
8169d0d0 3457 if (update->type & REF_ISSYMREF) {
6e30b2f6
MH
3458 if (update->flags & REF_NODEREF) {
3459 /*
3460 * We won't be reading the referent as part of
3461 * the transaction, so we have to read it here
3462 * to record and possibly check old_sha1:
3463 */
3464 if (read_ref_full(update->refname,
3465 mustexist ? RESOLVE_REF_READING : 0,
3466 lock->old_oid.hash, NULL)) {
3467 if (update->flags & REF_HAVE_OLD) {
3468 strbuf_addf(err, "cannot lock ref '%s': "
3469 "can't resolve old value",
3470 update->refname);
3471 return TRANSACTION_GENERIC_ERROR;
3472 } else {
3473 hashclr(lock->old_oid.hash);
3474 }
3475 }
3476 if ((update->flags & REF_HAVE_OLD) &&
3477 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3478 strbuf_addf(err, "cannot lock ref '%s': "
3479 "is at %s but expected %s",
3480 update->refname,
3481 sha1_to_hex(lock->old_oid.hash),
3482 sha1_to_hex(update->old_sha1));
8169d0d0 3483 return TRANSACTION_GENERIC_ERROR;
8169d0d0 3484 }
92b1551b 3485
6e30b2f6
MH
3486 } else {
3487 /*
3488 * Create a new update for the reference this
3489 * symref is pointing at. Also, we will record
3490 * and verify old_sha1 for this update as part
3491 * of processing the split-off update, so we
3492 * don't have to do it here.
3493 */
92b1551b
MH
3494 ret = split_symref_update(update, referent.buf, transaction,
3495 affected_refnames, err);
3496 if (ret)
3497 return ret;
3498 }
6e30b2f6
MH
3499 } else {
3500 struct ref_update *parent_update;
8169d0d0 3501
6e30b2f6
MH
3502 /*
3503 * If this update is happening indirectly because of a
3504 * symref update, record the old SHA-1 in the parent
3505 * update:
3506 */
3507 for (parent_update = update->parent_update;
3508 parent_update;
3509 parent_update = parent_update->parent_update) {
3510 oidcpy(&parent_update->lock->old_oid, &lock->old_oid);
3511 }
3512
3513 if ((update->flags & REF_HAVE_OLD) &&
3514 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3515 if (is_null_sha1(update->old_sha1))
3516 strbuf_addf(err, "cannot lock ref '%s': reference already exists",
3517 original_update_refname(update));
3518 else
3519 strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
3520 original_update_refname(update),
3521 sha1_to_hex(lock->old_oid.hash),
3522 sha1_to_hex(update->old_sha1));
3523
3524 return TRANSACTION_GENERIC_ERROR;
3525 }
92b1551b
MH
3526 }
3527
165056b2
MH
3528 if ((update->flags & REF_HAVE_NEW) &&
3529 !(update->flags & REF_DELETING) &&
3530 !(update->flags & REF_LOG_ONLY)) {
92b1551b
MH
3531 if (!(update->type & REF_ISSYMREF) &&
3532 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
165056b2
MH
3533 /*
3534 * The reference already has the desired
3535 * value, so we don't need to write it.
3536 */
92b1551b 3537 } else if (write_ref_to_lockfile(lock, update->new_sha1,
165056b2
MH
3538 err)) {
3539 char *write_err = strbuf_detach(err, NULL);
3540
3541 /*
3542 * The lock was freed upon failure of
3543 * write_ref_to_lockfile():
3544 */
3545 update->lock = NULL;
3546 strbuf_addf(err,
3547 "cannot update the ref '%s': %s",
3548 update->refname, write_err);
3549 free(write_err);
3550 return TRANSACTION_GENERIC_ERROR;
3551 } else {
3552 update->flags |= REF_NEEDS_COMMIT;
3553 }
3554 }
3555 if (!(update->flags & REF_NEEDS_COMMIT)) {
3556 /*
3557 * We didn't call write_ref_to_lockfile(), so
3558 * the lockfile is still open. Close it to
3559 * free up the file descriptor:
3560 */
92b1551b 3561 if (close_ref(lock)) {
165056b2
MH
3562 strbuf_addf(err, "couldn't close '%s.lock'",
3563 update->refname);
3564 return TRANSACTION_GENERIC_ERROR;
3565 }
3566 }
3567 return 0;
3568}
3569
7bd9bcf3
MH
3570int ref_transaction_commit(struct ref_transaction *transaction,
3571 struct strbuf *err)
3572{
3573 int ret = 0, i;
7bd9bcf3
MH
3574 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3575 struct string_list_item *ref_to_delete;
3576 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
92b1551b
MH
3577 char *head_ref = NULL;
3578 int head_type;
3579 struct object_id head_oid;
7bd9bcf3
MH
3580
3581 assert(err);
3582
3583 if (transaction->state != REF_TRANSACTION_OPEN)
3584 die("BUG: commit called for transaction that is not open");
3585
efe47281 3586 if (!transaction->nr) {
7bd9bcf3
MH
3587 transaction->state = REF_TRANSACTION_CLOSED;
3588 return 0;
3589 }
3590
92b1551b
MH
3591 /*
3592 * Fail if a refname appears more than once in the
3593 * transaction. (If we end up splitting up any updates using
3594 * split_symref_update() or split_head_update(), those
3595 * functions will check that the new updates don't have the
3596 * same refname as any existing ones.)
3597 */
3598 for (i = 0; i < transaction->nr; i++) {
3599 struct ref_update *update = transaction->updates[i];
3600 struct string_list_item *item =
3601 string_list_append(&affected_refnames, update->refname);
3602
3603 /*
3604 * We store a pointer to update in item->util, but at
3605 * the moment we never use the value of this field
3606 * except to check whether it is non-NULL.
3607 */
3608 item->util = update;
3609 }
7bd9bcf3
MH
3610 string_list_sort(&affected_refnames);
3611 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3612 ret = TRANSACTION_GENERIC_ERROR;
3613 goto cleanup;
3614 }
3615
92b1551b
MH
3616 /*
3617 * Special hack: If a branch is updated directly and HEAD
3618 * points to it (may happen on the remote side of a push
3619 * for example) then logically the HEAD reflog should be
3620 * updated too.
3621 *
3622 * A generic solution would require reverse symref lookups,
3623 * but finding all symrefs pointing to a given branch would be
3624 * rather costly for this rare event (the direct update of a
3625 * branch) to be worth it. So let's cheat and check with HEAD
3626 * only, which should cover 99% of all usage scenarios (even
3627 * 100% of the default ones).
3628 *
3629 * So if HEAD is a symbolic reference, then record the name of
3630 * the reference that it points to. If we see an update of
3631 * head_ref within the transaction, then split_head_update()
3632 * arranges for the reflog of HEAD to be updated, too.
3633 */
3634 head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
3635 head_oid.hash, &head_type);
3636
3637 if (head_ref && !(head_type & REF_ISSYMREF)) {
3638 free(head_ref);
3639 head_ref = NULL;
3640 }
3641
7bd9bcf3
MH
3642 /*
3643 * Acquire all locks, verify old values if provided, check
3644 * that new values are valid, and write new values to the
3645 * lockfiles, ready to be activated. Only keep one lockfile
3646 * open at a time to avoid running out of file descriptors.
3647 */
efe47281
MH
3648 for (i = 0; i < transaction->nr; i++) {
3649 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3650
92b1551b 3651 ret = lock_ref_for_update(update, transaction, head_ref,
165056b2
MH
3652 &affected_refnames, err);
3653 if (ret)
7bd9bcf3 3654 goto cleanup;
7bd9bcf3
MH
3655 }
3656
3657 /* Perform updates first so live commits remain referenced */
efe47281
MH
3658 for (i = 0; i < transaction->nr; i++) {
3659 struct ref_update *update = transaction->updates[i];
92b1551b 3660 struct ref_lock *lock = update->lock;
7bd9bcf3 3661
d99aa884
DT
3662 if (update->flags & REF_NEEDS_COMMIT ||
3663 update->flags & REF_LOG_ONLY) {
92b1551b
MH
3664 if (log_ref_write(lock->ref_name, lock->old_oid.hash,
3665 update->new_sha1,
3666 update->msg, update->flags, err)) {
3667 char *old_msg = strbuf_detach(err, NULL);
3668
3669 strbuf_addf(err, "cannot update the ref '%s': %s",
3670 lock->ref_name, old_msg);
3671 free(old_msg);
3672 unlock_ref(lock);
7bd9bcf3
MH
3673 update->lock = NULL;
3674 ret = TRANSACTION_GENERIC_ERROR;
3675 goto cleanup;
92b1551b
MH
3676 }
3677 }
3678 if (update->flags & REF_NEEDS_COMMIT) {
3679 clear_loose_ref_cache(&ref_cache);
3680 if (commit_ref(lock)) {
3681 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3682 unlock_ref(lock);
7bd9bcf3 3683 update->lock = NULL;
92b1551b
MH
3684 ret = TRANSACTION_GENERIC_ERROR;
3685 goto cleanup;
7bd9bcf3
MH
3686 }
3687 }
3688 }
7bd9bcf3 3689 /* Perform deletes now that updates are safely completed */
efe47281
MH
3690 for (i = 0; i < transaction->nr; i++) {
3691 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3692
d99aa884
DT
3693 if (update->flags & REF_DELETING &&
3694 !(update->flags & REF_LOG_ONLY)) {
7bd9bcf3
MH
3695 if (delete_ref_loose(update->lock, update->type, err)) {
3696 ret = TRANSACTION_GENERIC_ERROR;
3697 goto cleanup;
3698 }
3699
3700 if (!(update->flags & REF_ISPRUNING))
3701 string_list_append(&refs_to_delete,
3702 update->lock->ref_name);
3703 }
3704 }
3705
3706 if (repack_without_refs(&refs_to_delete, err)) {
3707 ret = TRANSACTION_GENERIC_ERROR;
3708 goto cleanup;
3709 }
3710 for_each_string_list_item(ref_to_delete, &refs_to_delete)
3711 unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
3712 clear_loose_ref_cache(&ref_cache);
3713
3714cleanup:
3715 transaction->state = REF_TRANSACTION_CLOSED;
3716
efe47281
MH
3717 for (i = 0; i < transaction->nr; i++)
3718 if (transaction->updates[i]->lock)
3719 unlock_ref(transaction->updates[i]->lock);
7bd9bcf3 3720 string_list_clear(&refs_to_delete, 0);
92b1551b 3721 free(head_ref);
7bd9bcf3 3722 string_list_clear(&affected_refnames, 0);
92b1551b 3723
7bd9bcf3
MH
3724 return ret;
3725}
3726
3727static int ref_present(const char *refname,
3728 const struct object_id *oid, int flags, void *cb_data)
3729{
3730 struct string_list *affected_refnames = cb_data;
3731
3732 return string_list_has_string(affected_refnames, refname);
3733}
3734
3735int initial_ref_transaction_commit(struct ref_transaction *transaction,
3736 struct strbuf *err)
3737{
3738 int ret = 0, i;
7bd9bcf3
MH
3739 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
3740
3741 assert(err);
3742
3743 if (transaction->state != REF_TRANSACTION_OPEN)
3744 die("BUG: commit called for transaction that is not open");
3745
3746 /* Fail if a refname appears more than once in the transaction: */
efe47281
MH
3747 for (i = 0; i < transaction->nr; i++)
3748 string_list_append(&affected_refnames,
3749 transaction->updates[i]->refname);
7bd9bcf3
MH
3750 string_list_sort(&affected_refnames);
3751 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3752 ret = TRANSACTION_GENERIC_ERROR;
3753 goto cleanup;
3754 }
3755
3756 /*
3757 * It's really undefined to call this function in an active
3758 * repository or when there are existing references: we are
3759 * only locking and changing packed-refs, so (1) any
3760 * simultaneous processes might try to change a reference at
3761 * the same time we do, and (2) any existing loose versions of
3762 * the references that we are setting would have precedence
3763 * over our values. But some remote helpers create the remote
3764 * "HEAD" and "master" branches before calling this function,
3765 * so here we really only check that none of the references
3766 * that we are creating already exists.
3767 */
3768 if (for_each_rawref(ref_present, &affected_refnames))
3769 die("BUG: initial ref transaction called with existing refs");
3770
efe47281
MH
3771 for (i = 0; i < transaction->nr; i++) {
3772 struct ref_update *update = transaction->updates[i];
7bd9bcf3
MH
3773
3774 if ((update->flags & REF_HAVE_OLD) &&
3775 !is_null_sha1(update->old_sha1))
3776 die("BUG: initial ref transaction with old_sha1 set");
3777 if (verify_refname_available(update->refname,
3778 &affected_refnames, NULL,
3779 err)) {
3780 ret = TRANSACTION_NAME_CONFLICT;
3781 goto cleanup;
3782 }
3783 }
3784
3785 if (lock_packed_refs(0)) {
3786 strbuf_addf(err, "unable to lock packed-refs file: %s",
3787 strerror(errno));
3788 ret = TRANSACTION_GENERIC_ERROR;
3789 goto cleanup;
3790 }
3791
efe47281
MH
3792 for (i = 0; i < transaction->nr; i++) {
3793 struct ref_update *update = transaction->updates[i];
7bd9bcf3
MH
3794
3795 if ((update->flags & REF_HAVE_NEW) &&
3796 !is_null_sha1(update->new_sha1))
3797 add_packed_ref(update->refname, update->new_sha1);
3798 }
3799
3800 if (commit_packed_refs()) {
3801 strbuf_addf(err, "unable to commit packed-refs file: %s",
3802 strerror(errno));
3803 ret = TRANSACTION_GENERIC_ERROR;
3804 goto cleanup;
3805 }
3806
3807cleanup:
3808 transaction->state = REF_TRANSACTION_CLOSED;
3809 string_list_clear(&affected_refnames, 0);
3810 return ret;
3811}
3812
3813struct expire_reflog_cb {
3814 unsigned int flags;
3815 reflog_expiry_should_prune_fn *should_prune_fn;
3816 void *policy_cb;
3817 FILE *newlog;
3818 unsigned char last_kept_sha1[20];
3819};
3820
3821static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
3822 const char *email, unsigned long timestamp, int tz,
3823 const char *message, void *cb_data)
3824{
3825 struct expire_reflog_cb *cb = cb_data;
3826 struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
3827
3828 if (cb->flags & EXPIRE_REFLOGS_REWRITE)
3829 osha1 = cb->last_kept_sha1;
3830
3831 if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
3832 message, policy_cb)) {
3833 if (!cb->newlog)
3834 printf("would prune %s", message);
3835 else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
3836 printf("prune %s", message);
3837 } else {
3838 if (cb->newlog) {
3839 fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
3840 sha1_to_hex(osha1), sha1_to_hex(nsha1),
3841 email, timestamp, tz, message);
3842 hashcpy(cb->last_kept_sha1, nsha1);
3843 }
3844 if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
3845 printf("keep %s", message);
3846 }
3847 return 0;
3848}
3849
3850int reflog_expire(const char *refname, const unsigned char *sha1,
3851 unsigned int flags,
3852 reflog_expiry_prepare_fn prepare_fn,
3853 reflog_expiry_should_prune_fn should_prune_fn,
3854 reflog_expiry_cleanup_fn cleanup_fn,
3855 void *policy_cb_data)
3856{
3857 static struct lock_file reflog_lock;
3858 struct expire_reflog_cb cb;
3859 struct ref_lock *lock;
3860 char *log_file;
3861 int status = 0;
3862 int type;
3863 struct strbuf err = STRBUF_INIT;
3864
3865 memset(&cb, 0, sizeof(cb));
3866 cb.flags = flags;
3867 cb.policy_cb = policy_cb_data;
3868 cb.should_prune_fn = should_prune_fn;
3869
3870 /*
3871 * The reflog file is locked by holding the lock on the
3872 * reference itself, plus we might need to update the
3873 * reference if --updateref was specified:
3874 */
41d796ed
DT
3875 lock = lock_ref_sha1_basic(refname, sha1, NULL, NULL, REF_NODEREF,
3876 &type, &err);
7bd9bcf3
MH
3877 if (!lock) {
3878 error("cannot lock ref '%s': %s", refname, err.buf);
3879 strbuf_release(&err);
3880 return -1;
3881 }
3882 if (!reflog_exists(refname)) {
3883 unlock_ref(lock);
3884 return 0;
3885 }
3886
3887 log_file = git_pathdup("logs/%s", refname);
3888 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3889 /*
3890 * Even though holding $GIT_DIR/logs/$reflog.lock has
3891 * no locking implications, we use the lock_file
3892 * machinery here anyway because it does a lot of the
3893 * work we need, including cleaning up if the program
3894 * exits unexpectedly.
3895 */
3896 if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
3897 struct strbuf err = STRBUF_INIT;
3898 unable_to_lock_message(log_file, errno, &err);
3899 error("%s", err.buf);
3900 strbuf_release(&err);
3901 goto failure;
3902 }
3903 cb.newlog = fdopen_lock_file(&reflog_lock, "w");
3904 if (!cb.newlog) {
3905 error("cannot fdopen %s (%s)",
3906 get_lock_file_path(&reflog_lock), strerror(errno));
3907 goto failure;
3908 }
3909 }
3910
3911 (*prepare_fn)(refname, sha1, cb.policy_cb);
3912 for_each_reflog_ent(refname, expire_reflog_ent, &cb);
3913 (*cleanup_fn)(cb.policy_cb);
3914
3915 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3916 /*
3917 * It doesn't make sense to adjust a reference pointed
3918 * to by a symbolic ref based on expiring entries in
3919 * the symbolic reference's reflog. Nor can we update
3920 * a reference if there are no remaining reflog
3921 * entries.
3922 */
3923 int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
3924 !(type & REF_ISSYMREF) &&
3925 !is_null_sha1(cb.last_kept_sha1);
3926
3927 if (close_lock_file(&reflog_lock)) {
3928 status |= error("couldn't write %s: %s", log_file,
3929 strerror(errno));
3930 } else if (update &&
3931 (write_in_full(get_lock_file_fd(lock->lk),
3932 sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
3933 write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
3934 close_ref(lock) < 0)) {
3935 status |= error("couldn't write %s",
3936 get_lock_file_path(lock->lk));
3937 rollback_lock_file(&reflog_lock);
3938 } else if (commit_lock_file(&reflog_lock)) {
e0048d3e 3939 status |= error("unable to write reflog '%s' (%s)",
7bd9bcf3
MH
3940 log_file, strerror(errno));
3941 } else if (update && commit_ref(lock)) {
3942 status |= error("couldn't set %s", lock->ref_name);
3943 }
3944 }
3945 free(log_file);
3946 unlock_ref(lock);
3947 return status;
3948
3949 failure:
3950 rollback_lock_file(&reflog_lock);
3951 free(log_file);
3952 unlock_ref(lock);
3953 return -1;
3954}