t1404: add more tests of update-ref error handling
[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;
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10 struct lock_file *lk;
11 struct object_id old_oid;
12};
13
14struct ref_entry;
15
16/*
17 * Information used (along with the information in ref_entry) to
18 * describe a single cached reference. This data structure only
19 * occurs embedded in a union in struct ref_entry, and only when
20 * (ref_entry->flag & REF_DIR) is zero.
21 */
22struct ref_value {
23 /*
24 * The name of the object to which this reference resolves
25 * (which may be a tag object). If REF_ISBROKEN, this is
26 * null. If REF_ISSYMREF, then this is the name of the object
27 * referred to by the last reference in the symlink chain.
28 */
29 struct object_id oid;
30
31 /*
32 * If REF_KNOWS_PEELED, then this field holds the peeled value
33 * of this reference, or null if the reference is known not to
34 * be peelable. See the documentation for peel_ref() for an
35 * exact definition of "peelable".
36 */
37 struct object_id peeled;
38};
39
40struct ref_cache;
41
42/*
43 * Information used (along with the information in ref_entry) to
44 * describe a level in the hierarchy of references. This data
45 * structure only occurs embedded in a union in struct ref_entry, and
46 * only when (ref_entry.flag & REF_DIR) is set. In that case,
47 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
48 * in the directory have already been read:
49 *
50 * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
51 * or packed references, already read.
52 *
53 * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
54 * references that hasn't been read yet (nor has any of its
55 * subdirectories).
56 *
57 * Entries within a directory are stored within a growable array of
58 * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
59 * sorted are sorted by their component name in strcmp() order and the
60 * remaining entries are unsorted.
61 *
62 * Loose references are read lazily, one directory at a time. When a
63 * directory of loose references is read, then all of the references
64 * in that directory are stored, and REF_INCOMPLETE stubs are created
65 * for any subdirectories, but the subdirectories themselves are not
66 * read. The reading is triggered by get_ref_dir().
67 */
68struct ref_dir {
69 int nr, alloc;
70
71 /*
72 * Entries with index 0 <= i < sorted are sorted by name. New
73 * entries are appended to the list unsorted, and are sorted
74 * only when required; thus we avoid the need to sort the list
75 * after the addition of every reference.
76 */
77 int sorted;
78
79 /* A pointer to the ref_cache that contains this ref_dir. */
80 struct ref_cache *ref_cache;
81
82 struct ref_entry **entries;
83};
84
85/*
86 * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
87 * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
88 * public values; see refs.h.
89 */
90
91/*
92 * The field ref_entry->u.value.peeled of this value entry contains
93 * the correct peeled value for the reference, which might be
94 * null_sha1 if the reference is not a tag or if it is broken.
95 */
96#define REF_KNOWS_PEELED 0x10
97
98/* ref_entry represents a directory of references */
99#define REF_DIR 0x20
100
101/*
102 * Entry has not yet been read from disk (used only for REF_DIR
103 * entries representing loose references)
104 */
105#define REF_INCOMPLETE 0x40
106
107/*
108 * A ref_entry represents either a reference or a "subdirectory" of
109 * references.
110 *
111 * Each directory in the reference namespace is represented by a
112 * ref_entry with (flags & REF_DIR) set and containing a subdir member
113 * that holds the entries in that directory that have been read so
114 * far. If (flags & REF_INCOMPLETE) is set, then the directory and
115 * its subdirectories haven't been read yet. REF_INCOMPLETE is only
116 * used for loose reference directories.
117 *
118 * References are represented by a ref_entry with (flags & REF_DIR)
119 * unset and a value member that describes the reference's value. The
120 * flag member is at the ref_entry level, but it is also needed to
121 * interpret the contents of the value field (in other words, a
122 * ref_value object is not very much use without the enclosing
123 * ref_entry).
124 *
125 * Reference names cannot end with slash and directories' names are
126 * always stored with a trailing slash (except for the top-level
127 * directory, which is always denoted by ""). This has two nice
128 * consequences: (1) when the entries in each subdir are sorted
129 * lexicographically by name (as they usually are), the references in
130 * a whole tree can be generated in lexicographic order by traversing
131 * the tree in left-to-right, depth-first order; (2) the names of
132 * references and subdirectories cannot conflict, and therefore the
133 * presence of an empty subdirectory does not block the creation of a
134 * similarly-named reference. (The fact that reference names with the
135 * same leading components can conflict *with each other* is a
136 * separate issue that is regulated by verify_refname_available().)
137 *
138 * Please note that the name field contains the fully-qualified
139 * reference (or subdirectory) name. Space could be saved by only
140 * storing the relative names. But that would require the full names
141 * to be generated on the fly when iterating in do_for_each_ref(), and
142 * would break callback functions, who have always been able to assume
143 * that the name strings that they are passed will not be freed during
144 * the iteration.
145 */
146struct ref_entry {
147 unsigned char flag; /* ISSYMREF? ISPACKED? */
148 union {
149 struct ref_value value; /* if not (flags&REF_DIR) */
150 struct ref_dir subdir; /* if (flags&REF_DIR) */
151 } u;
152 /*
153 * The full name of the reference (e.g., "refs/heads/master")
154 * or the full name of the directory with a trailing slash
155 * (e.g., "refs/heads/"):
156 */
157 char name[FLEX_ARRAY];
158};
159
160static void read_loose_refs(const char *dirname, struct ref_dir *dir);
161static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
162static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
163 const char *dirname, size_t len,
164 int incomplete);
165static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
166
167static struct ref_dir *get_ref_dir(struct ref_entry *entry)
168{
169 struct ref_dir *dir;
170 assert(entry->flag & REF_DIR);
171 dir = &entry->u.subdir;
172 if (entry->flag & REF_INCOMPLETE) {
173 read_loose_refs(entry->name, dir);
174
175 /*
176 * Manually add refs/bisect, which, being
177 * per-worktree, might not appear in the directory
178 * listing for refs/ in the main repo.
179 */
180 if (!strcmp(entry->name, "refs/")) {
181 int pos = search_ref_dir(dir, "refs/bisect/", 12);
182 if (pos < 0) {
183 struct ref_entry *child_entry;
184 child_entry = create_dir_entry(dir->ref_cache,
185 "refs/bisect/",
186 12, 1);
187 add_entry_to_dir(dir, child_entry);
188 read_loose_refs("refs/bisect",
189 &child_entry->u.subdir);
190 }
191 }
192 entry->flag &= ~REF_INCOMPLETE;
193 }
194 return dir;
195}
196
197static struct ref_entry *create_ref_entry(const char *refname,
198 const unsigned char *sha1, int flag,
199 int check_name)
200{
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201 struct ref_entry *ref;
202
203 if (check_name &&
204 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
205 die("Reference has invalid format: '%s'", refname);
96ffc06f 206 FLEX_ALLOC_STR(ref, name, refname);
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207 hashcpy(ref->u.value.oid.hash, sha1);
208 oidclr(&ref->u.value.peeled);
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209 ref->flag = flag;
210 return ref;
211}
212
213static void clear_ref_dir(struct ref_dir *dir);
214
215static void free_ref_entry(struct ref_entry *entry)
216{
217 if (entry->flag & REF_DIR) {
218 /*
219 * Do not use get_ref_dir() here, as that might
220 * trigger the reading of loose refs.
221 */
222 clear_ref_dir(&entry->u.subdir);
223 }
224 free(entry);
225}
226
227/*
228 * Add a ref_entry to the end of dir (unsorted). Entry is always
229 * stored directly in dir; no recursion into subdirectories is
230 * done.
231 */
232static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
233{
234 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
235 dir->entries[dir->nr++] = entry;
236 /* optimize for the case that entries are added in order */
237 if (dir->nr == 1 ||
238 (dir->nr == dir->sorted + 1 &&
239 strcmp(dir->entries[dir->nr - 2]->name,
240 dir->entries[dir->nr - 1]->name) < 0))
241 dir->sorted = dir->nr;
242}
243
244/*
245 * Clear and free all entries in dir, recursively.
246 */
247static void clear_ref_dir(struct ref_dir *dir)
248{
249 int i;
250 for (i = 0; i < dir->nr; i++)
251 free_ref_entry(dir->entries[i]);
252 free(dir->entries);
253 dir->sorted = dir->nr = dir->alloc = 0;
254 dir->entries = NULL;
255}
256
257/*
258 * Create a struct ref_entry object for the specified dirname.
259 * dirname is the name of the directory with a trailing slash (e.g.,
260 * "refs/heads/") or "" for the top-level directory.
261 */
262static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
263 const char *dirname, size_t len,
264 int incomplete)
265{
266 struct ref_entry *direntry;
96ffc06f 267 FLEX_ALLOC_MEM(direntry, name, dirname, len);
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268 direntry->u.subdir.ref_cache = ref_cache;
269 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
270 return direntry;
271}
272
273static int ref_entry_cmp(const void *a, const void *b)
274{
275 struct ref_entry *one = *(struct ref_entry **)a;
276 struct ref_entry *two = *(struct ref_entry **)b;
277 return strcmp(one->name, two->name);
278}
279
280static void sort_ref_dir(struct ref_dir *dir);
281
282struct string_slice {
283 size_t len;
284 const char *str;
285};
286
287static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
288{
289 const struct string_slice *key = key_;
290 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
291 int cmp = strncmp(key->str, ent->name, key->len);
292 if (cmp)
293 return cmp;
294 return '\0' - (unsigned char)ent->name[key->len];
295}
296
297/*
298 * Return the index of the entry with the given refname from the
299 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
300 * no such entry is found. dir must already be complete.
301 */
302static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
303{
304 struct ref_entry **r;
305 struct string_slice key;
306
307 if (refname == NULL || !dir->nr)
308 return -1;
309
310 sort_ref_dir(dir);
311 key.len = len;
312 key.str = refname;
313 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
314 ref_entry_cmp_sslice);
315
316 if (r == NULL)
317 return -1;
318
319 return r - dir->entries;
320}
321
322/*
323 * Search for a directory entry directly within dir (without
324 * recursing). Sort dir if necessary. subdirname must be a directory
325 * name (i.e., end in '/'). If mkdir is set, then create the
326 * directory if it is missing; otherwise, return NULL if the desired
327 * directory cannot be found. dir must already be complete.
328 */
329static struct ref_dir *search_for_subdir(struct ref_dir *dir,
330 const char *subdirname, size_t len,
331 int mkdir)
332{
333 int entry_index = search_ref_dir(dir, subdirname, len);
334 struct ref_entry *entry;
335 if (entry_index == -1) {
336 if (!mkdir)
337 return NULL;
338 /*
339 * Since dir is complete, the absence of a subdir
340 * means that the subdir really doesn't exist;
341 * therefore, create an empty record for it but mark
342 * the record complete.
343 */
344 entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
345 add_entry_to_dir(dir, entry);
346 } else {
347 entry = dir->entries[entry_index];
348 }
349 return get_ref_dir(entry);
350}
351
352/*
353 * If refname is a reference name, find the ref_dir within the dir
354 * tree that should hold refname. If refname is a directory name
355 * (i.e., ends in '/'), then return that ref_dir itself. dir must
356 * represent the top-level directory and must already be complete.
357 * Sort ref_dirs and recurse into subdirectories as necessary. If
358 * mkdir is set, then create any missing directories; otherwise,
359 * return NULL if the desired directory cannot be found.
360 */
361static struct ref_dir *find_containing_dir(struct ref_dir *dir,
362 const char *refname, int mkdir)
363{
364 const char *slash;
365 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
366 size_t dirnamelen = slash - refname + 1;
367 struct ref_dir *subdir;
368 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
369 if (!subdir) {
370 dir = NULL;
371 break;
372 }
373 dir = subdir;
374 }
375
376 return dir;
377}
378
379/*
380 * Find the value entry with the given name in dir, sorting ref_dirs
381 * and recursing into subdirectories as necessary. If the name is not
382 * found or it corresponds to a directory entry, return NULL.
383 */
384static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
385{
386 int entry_index;
387 struct ref_entry *entry;
388 dir = find_containing_dir(dir, refname, 0);
389 if (!dir)
390 return NULL;
391 entry_index = search_ref_dir(dir, refname, strlen(refname));
392 if (entry_index == -1)
393 return NULL;
394 entry = dir->entries[entry_index];
395 return (entry->flag & REF_DIR) ? NULL : entry;
396}
397
398/*
399 * Remove the entry with the given name from dir, recursing into
400 * subdirectories as necessary. If refname is the name of a directory
401 * (i.e., ends with '/'), then remove the directory and its contents.
402 * If the removal was successful, return the number of entries
403 * remaining in the directory entry that contained the deleted entry.
404 * If the name was not found, return -1. Please note that this
405 * function only deletes the entry from the cache; it does not delete
406 * it from the filesystem or ensure that other cache entries (which
407 * might be symbolic references to the removed entry) are updated.
408 * Nor does it remove any containing dir entries that might be made
409 * empty by the removal. dir must represent the top-level directory
410 * and must already be complete.
411 */
412static int remove_entry(struct ref_dir *dir, const char *refname)
413{
414 int refname_len = strlen(refname);
415 int entry_index;
416 struct ref_entry *entry;
417 int is_dir = refname[refname_len - 1] == '/';
418 if (is_dir) {
419 /*
420 * refname represents a reference directory. Remove
421 * the trailing slash; otherwise we will get the
422 * directory *representing* refname rather than the
423 * one *containing* it.
424 */
425 char *dirname = xmemdupz(refname, refname_len - 1);
426 dir = find_containing_dir(dir, dirname, 0);
427 free(dirname);
428 } else {
429 dir = find_containing_dir(dir, refname, 0);
430 }
431 if (!dir)
432 return -1;
433 entry_index = search_ref_dir(dir, refname, refname_len);
434 if (entry_index == -1)
435 return -1;
436 entry = dir->entries[entry_index];
437
438 memmove(&dir->entries[entry_index],
439 &dir->entries[entry_index + 1],
440 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
441 );
442 dir->nr--;
443 if (dir->sorted > entry_index)
444 dir->sorted--;
445 free_ref_entry(entry);
446 return dir->nr;
447}
448
449/*
450 * Add a ref_entry to the ref_dir (unsorted), recursing into
451 * subdirectories as necessary. dir must represent the top-level
452 * directory. Return 0 on success.
453 */
454static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
455{
456 dir = find_containing_dir(dir, ref->name, 1);
457 if (!dir)
458 return -1;
459 add_entry_to_dir(dir, ref);
460 return 0;
461}
462
463/*
464 * Emit a warning and return true iff ref1 and ref2 have the same name
465 * and the same sha1. Die if they have the same name but different
466 * sha1s.
467 */
468static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
469{
470 if (strcmp(ref1->name, ref2->name))
471 return 0;
472
473 /* Duplicate name; make sure that they don't conflict: */
474
475 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
476 /* This is impossible by construction */
477 die("Reference directory conflict: %s", ref1->name);
478
479 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
480 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
481
482 warning("Duplicated ref: %s", ref1->name);
483 return 1;
484}
485
486/*
487 * Sort the entries in dir non-recursively (if they are not already
488 * sorted) and remove any duplicate entries.
489 */
490static void sort_ref_dir(struct ref_dir *dir)
491{
492 int i, j;
493 struct ref_entry *last = NULL;
494
495 /*
496 * This check also prevents passing a zero-length array to qsort(),
497 * which is a problem on some platforms.
498 */
499 if (dir->sorted == dir->nr)
500 return;
501
502 qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
503
504 /* Remove any duplicates: */
505 for (i = 0, j = 0; j < dir->nr; j++) {
506 struct ref_entry *entry = dir->entries[j];
507 if (last && is_dup_ref(last, entry))
508 free_ref_entry(entry);
509 else
510 last = dir->entries[i++] = entry;
511 }
512 dir->sorted = dir->nr = i;
513}
514
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515/*
516 * Return true iff the reference described by entry can be resolved to
517 * an object in the database. Emit a warning if the referred-to
518 * object does not exist.
519 */
520static int ref_resolves_to_object(struct ref_entry *entry)
521{
522 if (entry->flag & REF_ISBROKEN)
523 return 0;
524 if (!has_sha1_file(entry->u.value.oid.hash)) {
525 error("%s does not point to a valid object!", entry->name);
526 return 0;
527 }
528 return 1;
529}
530
531/*
532 * current_ref is a performance hack: when iterating over references
533 * using the for_each_ref*() functions, current_ref is set to the
534 * current reference's entry before calling the callback function. If
535 * the callback function calls peel_ref(), then peel_ref() first
536 * checks whether the reference to be peeled is the current reference
537 * (it usually is) and if so, returns that reference's peeled version
538 * if it is available. This avoids a refname lookup in a common case.
539 */
540static struct ref_entry *current_ref;
541
542typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
543
544struct ref_entry_cb {
545 const char *base;
546 int trim;
547 int flags;
548 each_ref_fn *fn;
549 void *cb_data;
550};
551
552/*
553 * Handle one reference in a do_for_each_ref*()-style iteration,
554 * calling an each_ref_fn for each entry.
555 */
556static int do_one_ref(struct ref_entry *entry, void *cb_data)
557{
558 struct ref_entry_cb *data = cb_data;
559 struct ref_entry *old_current_ref;
560 int retval;
561
562 if (!starts_with(entry->name, data->base))
563 return 0;
564
565 if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
566 !ref_resolves_to_object(entry))
567 return 0;
568
569 /* Store the old value, in case this is a recursive call: */
570 old_current_ref = current_ref;
571 current_ref = entry;
572 retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
573 entry->flag, data->cb_data);
574 current_ref = old_current_ref;
575 return retval;
576}
577
578/*
579 * Call fn for each reference in dir that has index in the range
580 * offset <= index < dir->nr. Recurse into subdirectories that are in
581 * that index range, sorting them before iterating. This function
582 * does not sort dir itself; it should be sorted beforehand. fn is
583 * called for all references, including broken ones.
584 */
585static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
586 each_ref_entry_fn fn, void *cb_data)
587{
588 int i;
589 assert(dir->sorted == dir->nr);
590 for (i = offset; i < dir->nr; i++) {
591 struct ref_entry *entry = dir->entries[i];
592 int retval;
593 if (entry->flag & REF_DIR) {
594 struct ref_dir *subdir = get_ref_dir(entry);
595 sort_ref_dir(subdir);
596 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
597 } else {
598 retval = fn(entry, cb_data);
599 }
600 if (retval)
601 return retval;
602 }
603 return 0;
604}
605
606/*
607 * Call fn for each reference in the union of dir1 and dir2, in order
608 * by refname. Recurse into subdirectories. If a value entry appears
609 * in both dir1 and dir2, then only process the version that is in
610 * dir2. The input dirs must already be sorted, but subdirs will be
611 * sorted as needed. fn is called for all references, including
612 * broken ones.
613 */
614static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
615 struct ref_dir *dir2,
616 each_ref_entry_fn fn, void *cb_data)
617{
618 int retval;
619 int i1 = 0, i2 = 0;
620
621 assert(dir1->sorted == dir1->nr);
622 assert(dir2->sorted == dir2->nr);
623 while (1) {
624 struct ref_entry *e1, *e2;
625 int cmp;
626 if (i1 == dir1->nr) {
627 return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
628 }
629 if (i2 == dir2->nr) {
630 return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
631 }
632 e1 = dir1->entries[i1];
633 e2 = dir2->entries[i2];
634 cmp = strcmp(e1->name, e2->name);
635 if (cmp == 0) {
636 if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
637 /* Both are directories; descend them in parallel. */
638 struct ref_dir *subdir1 = get_ref_dir(e1);
639 struct ref_dir *subdir2 = get_ref_dir(e2);
640 sort_ref_dir(subdir1);
641 sort_ref_dir(subdir2);
642 retval = do_for_each_entry_in_dirs(
643 subdir1, subdir2, fn, cb_data);
644 i1++;
645 i2++;
646 } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
647 /* Both are references; ignore the one from dir1. */
648 retval = fn(e2, cb_data);
649 i1++;
650 i2++;
651 } else {
652 die("conflict between reference and directory: %s",
653 e1->name);
654 }
655 } else {
656 struct ref_entry *e;
657 if (cmp < 0) {
658 e = e1;
659 i1++;
660 } else {
661 e = e2;
662 i2++;
663 }
664 if (e->flag & REF_DIR) {
665 struct ref_dir *subdir = get_ref_dir(e);
666 sort_ref_dir(subdir);
667 retval = do_for_each_entry_in_dir(
668 subdir, 0, fn, cb_data);
669 } else {
670 retval = fn(e, cb_data);
671 }
672 }
673 if (retval)
674 return retval;
675 }
676}
677
678/*
679 * Load all of the refs from the dir into our in-memory cache. The hard work
680 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
681 * through all of the sub-directories. We do not even need to care about
682 * sorting, as traversal order does not matter to us.
683 */
684static void prime_ref_dir(struct ref_dir *dir)
685{
686 int i;
687 for (i = 0; i < dir->nr; i++) {
688 struct ref_entry *entry = dir->entries[i];
689 if (entry->flag & REF_DIR)
690 prime_ref_dir(get_ref_dir(entry));
691 }
692}
693
694struct nonmatching_ref_data {
695 const struct string_list *skip;
696 const char *conflicting_refname;
697};
698
699static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
700{
701 struct nonmatching_ref_data *data = vdata;
702
703 if (data->skip && string_list_has_string(data->skip, entry->name))
704 return 0;
705
706 data->conflicting_refname = entry->name;
707 return 1;
708}
709
710/*
711 * Return 0 if a reference named refname could be created without
712 * conflicting with the name of an existing reference in dir.
713 * See verify_refname_available for more information.
714 */
715static int verify_refname_available_dir(const char *refname,
716 const struct string_list *extras,
717 const struct string_list *skip,
718 struct ref_dir *dir,
719 struct strbuf *err)
720{
721 const char *slash;
0845122c 722 const char *extra_refname;
7bd9bcf3
MH
723 int pos;
724 struct strbuf dirname = STRBUF_INIT;
725 int ret = -1;
726
727 /*
728 * For the sake of comments in this function, suppose that
729 * refname is "refs/foo/bar".
730 */
731
732 assert(err);
733
734 strbuf_grow(&dirname, strlen(refname) + 1);
735 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
736 /* Expand dirname to the new prefix, not including the trailing slash: */
737 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
738
739 /*
740 * We are still at a leading dir of the refname (e.g.,
741 * "refs/foo"; if there is a reference with that name,
742 * it is a conflict, *unless* it is in skip.
743 */
744 if (dir) {
745 pos = search_ref_dir(dir, dirname.buf, dirname.len);
746 if (pos >= 0 &&
747 (!skip || !string_list_has_string(skip, dirname.buf))) {
748 /*
749 * We found a reference whose name is
750 * a proper prefix of refname; e.g.,
751 * "refs/foo", and is not in skip.
752 */
753 strbuf_addf(err, "'%s' exists; cannot create '%s'",
754 dirname.buf, refname);
755 goto cleanup;
756 }
757 }
758
759 if (extras && string_list_has_string(extras, dirname.buf) &&
760 (!skip || !string_list_has_string(skip, dirname.buf))) {
761 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
762 refname, dirname.buf);
763 goto cleanup;
764 }
765
766 /*
767 * Otherwise, we can try to continue our search with
768 * the next component. So try to look up the
769 * directory, e.g., "refs/foo/". If we come up empty,
770 * we know there is nothing under this whole prefix,
771 * but even in that case we still have to continue the
772 * search for conflicts with extras.
773 */
774 strbuf_addch(&dirname, '/');
775 if (dir) {
776 pos = search_ref_dir(dir, dirname.buf, dirname.len);
777 if (pos < 0) {
778 /*
779 * There was no directory "refs/foo/",
780 * so there is nothing under this
781 * whole prefix. So there is no need
782 * to continue looking for conflicting
783 * references. But we need to continue
784 * looking for conflicting extras.
785 */
786 dir = NULL;
787 } else {
788 dir = get_ref_dir(dir->entries[pos]);
789 }
790 }
791 }
792
793 /*
794 * We are at the leaf of our refname (e.g., "refs/foo/bar").
795 * There is no point in searching for a reference with that
796 * name, because a refname isn't considered to conflict with
797 * itself. But we still need to check for references whose
798 * names are in the "refs/foo/bar/" namespace, because they
799 * *do* conflict.
800 */
801 strbuf_addstr(&dirname, refname + dirname.len);
802 strbuf_addch(&dirname, '/');
803
804 if (dir) {
805 pos = search_ref_dir(dir, dirname.buf, dirname.len);
806
807 if (pos >= 0) {
808 /*
809 * We found a directory named "$refname/"
810 * (e.g., "refs/foo/bar/"). It is a problem
811 * iff it contains any ref that is not in
812 * "skip".
813 */
814 struct nonmatching_ref_data data;
815
816 data.skip = skip;
817 data.conflicting_refname = NULL;
818 dir = get_ref_dir(dir->entries[pos]);
819 sort_ref_dir(dir);
820 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
821 strbuf_addf(err, "'%s' exists; cannot create '%s'",
822 data.conflicting_refname, refname);
823 goto cleanup;
824 }
825 }
826 }
827
0845122c
DT
828 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
829 if (extra_refname)
830 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
831 refname, extra_refname);
832 else
833 ret = 0;
7bd9bcf3
MH
834
835cleanup:
836 strbuf_release(&dirname);
837 return ret;
838}
839
840struct packed_ref_cache {
841 struct ref_entry *root;
842
843 /*
844 * Count of references to the data structure in this instance,
845 * including the pointer from ref_cache::packed if any. The
846 * data will not be freed as long as the reference count is
847 * nonzero.
848 */
849 unsigned int referrers;
850
851 /*
852 * Iff the packed-refs file associated with this instance is
853 * currently locked for writing, this points at the associated
854 * lock (which is owned by somebody else). The referrer count
855 * is also incremented when the file is locked and decremented
856 * when it is unlocked.
857 */
858 struct lock_file *lock;
859
860 /* The metadata from when this packed-refs cache was read */
861 struct stat_validity validity;
862};
863
864/*
865 * Future: need to be in "struct repository"
866 * when doing a full libification.
867 */
868static struct ref_cache {
869 struct ref_cache *next;
870 struct ref_entry *loose;
871 struct packed_ref_cache *packed;
872 /*
873 * The submodule name, or "" for the main repo. We allocate
874 * length 1 rather than FLEX_ARRAY so that the main ref_cache
875 * is initialized correctly.
876 */
877 char name[1];
878} ref_cache, *submodule_ref_caches;
879
880/* Lock used for the main packed-refs file: */
881static struct lock_file packlock;
882
883/*
884 * Increment the reference count of *packed_refs.
885 */
886static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
887{
888 packed_refs->referrers++;
889}
890
891/*
892 * Decrease the reference count of *packed_refs. If it goes to zero,
893 * free *packed_refs and return true; otherwise return false.
894 */
895static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
896{
897 if (!--packed_refs->referrers) {
898 free_ref_entry(packed_refs->root);
899 stat_validity_clear(&packed_refs->validity);
900 free(packed_refs);
901 return 1;
902 } else {
903 return 0;
904 }
905}
906
907static void clear_packed_ref_cache(struct ref_cache *refs)
908{
909 if (refs->packed) {
910 struct packed_ref_cache *packed_refs = refs->packed;
911
912 if (packed_refs->lock)
913 die("internal error: packed-ref cache cleared while locked");
914 refs->packed = NULL;
915 release_packed_ref_cache(packed_refs);
916 }
917}
918
919static void clear_loose_ref_cache(struct ref_cache *refs)
920{
921 if (refs->loose) {
922 free_ref_entry(refs->loose);
923 refs->loose = NULL;
924 }
925}
926
a2d5156c
JK
927/*
928 * Create a new submodule ref cache and add it to the internal
929 * set of caches.
930 */
7bd9bcf3
MH
931static struct ref_cache *create_ref_cache(const char *submodule)
932{
7bd9bcf3
MH
933 struct ref_cache *refs;
934 if (!submodule)
935 submodule = "";
96ffc06f 936 FLEX_ALLOC_STR(refs, name, submodule);
a2d5156c
JK
937 refs->next = submodule_ref_caches;
938 submodule_ref_caches = refs;
7bd9bcf3
MH
939 return refs;
940}
941
a2d5156c 942static struct ref_cache *lookup_ref_cache(const char *submodule)
7bd9bcf3
MH
943{
944 struct ref_cache *refs;
945
946 if (!submodule || !*submodule)
947 return &ref_cache;
948
949 for (refs = submodule_ref_caches; refs; refs = refs->next)
950 if (!strcmp(submodule, refs->name))
951 return refs;
a2d5156c
JK
952 return NULL;
953}
7bd9bcf3 954
a2d5156c
JK
955/*
956 * Return a pointer to a ref_cache for the specified submodule. For
957 * the main repository, use submodule==NULL. The returned structure
958 * will be allocated and initialized but not necessarily populated; it
959 * should not be freed.
960 */
961static struct ref_cache *get_ref_cache(const char *submodule)
962{
963 struct ref_cache *refs = lookup_ref_cache(submodule);
964 if (!refs)
965 refs = create_ref_cache(submodule);
7bd9bcf3
MH
966 return refs;
967}
968
969/* The length of a peeled reference line in packed-refs, including EOL: */
970#define PEELED_LINE_LENGTH 42
971
972/*
973 * The packed-refs header line that we write out. Perhaps other
974 * traits will be added later. The trailing space is required.
975 */
976static const char PACKED_REFS_HEADER[] =
977 "# pack-refs with: peeled fully-peeled \n";
978
979/*
980 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
981 * Return a pointer to the refname within the line (null-terminated),
982 * or NULL if there was a problem.
983 */
984static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
985{
986 const char *ref;
987
988 /*
989 * 42: the answer to everything.
990 *
991 * In this case, it happens to be the answer to
992 * 40 (length of sha1 hex representation)
993 * +1 (space in between hex and name)
994 * +1 (newline at the end of the line)
995 */
996 if (line->len <= 42)
997 return NULL;
998
999 if (get_sha1_hex(line->buf, sha1) < 0)
1000 return NULL;
1001 if (!isspace(line->buf[40]))
1002 return NULL;
1003
1004 ref = line->buf + 41;
1005 if (isspace(*ref))
1006 return NULL;
1007
1008 if (line->buf[line->len - 1] != '\n')
1009 return NULL;
1010 line->buf[--line->len] = 0;
1011
1012 return ref;
1013}
1014
1015/*
1016 * Read f, which is a packed-refs file, into dir.
1017 *
1018 * A comment line of the form "# pack-refs with: " may contain zero or
1019 * more traits. We interpret the traits as follows:
1020 *
1021 * No traits:
1022 *
1023 * Probably no references are peeled. But if the file contains a
1024 * peeled value for a reference, we will use it.
1025 *
1026 * peeled:
1027 *
1028 * References under "refs/tags/", if they *can* be peeled, *are*
1029 * peeled in this file. References outside of "refs/tags/" are
1030 * probably not peeled even if they could have been, but if we find
1031 * a peeled value for such a reference we will use it.
1032 *
1033 * fully-peeled:
1034 *
1035 * All references in the file that can be peeled are peeled.
1036 * Inversely (and this is more important), any references in the
1037 * file for which no peeled value is recorded is not peelable. This
1038 * trait should typically be written alongside "peeled" for
1039 * compatibility with older clients, but we do not require it
1040 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1041 */
1042static void read_packed_refs(FILE *f, struct ref_dir *dir)
1043{
1044 struct ref_entry *last = NULL;
1045 struct strbuf line = STRBUF_INIT;
1046 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1047
1048 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1049 unsigned char sha1[20];
1050 const char *refname;
1051 const char *traits;
1052
1053 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1054 if (strstr(traits, " fully-peeled "))
1055 peeled = PEELED_FULLY;
1056 else if (strstr(traits, " peeled "))
1057 peeled = PEELED_TAGS;
1058 /* perhaps other traits later as well */
1059 continue;
1060 }
1061
1062 refname = parse_ref_line(&line, sha1);
1063 if (refname) {
1064 int flag = REF_ISPACKED;
1065
1066 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1067 if (!refname_is_safe(refname))
1068 die("packed refname is dangerous: %s", refname);
1069 hashclr(sha1);
1070 flag |= REF_BAD_NAME | REF_ISBROKEN;
1071 }
1072 last = create_ref_entry(refname, sha1, flag, 0);
1073 if (peeled == PEELED_FULLY ||
1074 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1075 last->flag |= REF_KNOWS_PEELED;
1076 add_ref(dir, last);
1077 continue;
1078 }
1079 if (last &&
1080 line.buf[0] == '^' &&
1081 line.len == PEELED_LINE_LENGTH &&
1082 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1083 !get_sha1_hex(line.buf + 1, sha1)) {
1084 hashcpy(last->u.value.peeled.hash, sha1);
1085 /*
1086 * Regardless of what the file header said,
1087 * we definitely know the value of *this*
1088 * reference:
1089 */
1090 last->flag |= REF_KNOWS_PEELED;
1091 }
1092 }
1093
1094 strbuf_release(&line);
1095}
1096
1097/*
1098 * Get the packed_ref_cache for the specified ref_cache, creating it
1099 * if necessary.
1100 */
1101static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1102{
1103 char *packed_refs_file;
1104
1105 if (*refs->name)
1106 packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
1107 else
1108 packed_refs_file = git_pathdup("packed-refs");
1109
1110 if (refs->packed &&
1111 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1112 clear_packed_ref_cache(refs);
1113
1114 if (!refs->packed) {
1115 FILE *f;
1116
1117 refs->packed = xcalloc(1, sizeof(*refs->packed));
1118 acquire_packed_ref_cache(refs->packed);
1119 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1120 f = fopen(packed_refs_file, "r");
1121 if (f) {
1122 stat_validity_update(&refs->packed->validity, fileno(f));
1123 read_packed_refs(f, get_ref_dir(refs->packed->root));
1124 fclose(f);
1125 }
1126 }
1127 free(packed_refs_file);
1128 return refs->packed;
1129}
1130
1131static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1132{
1133 return get_ref_dir(packed_ref_cache->root);
1134}
1135
1136static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1137{
1138 return get_packed_ref_dir(get_packed_ref_cache(refs));
1139}
1140
1141/*
1142 * Add a reference to the in-memory packed reference cache. This may
1143 * only be called while the packed-refs file is locked (see
1144 * lock_packed_refs()). To actually write the packed-refs file, call
1145 * commit_packed_refs().
1146 */
1147static void add_packed_ref(const char *refname, const unsigned char *sha1)
1148{
1149 struct packed_ref_cache *packed_ref_cache =
1150 get_packed_ref_cache(&ref_cache);
1151
1152 if (!packed_ref_cache->lock)
1153 die("internal error: packed refs not locked");
1154 add_ref(get_packed_ref_dir(packed_ref_cache),
1155 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1156}
1157
1158/*
1159 * Read the loose references from the namespace dirname into dir
1160 * (without recursing). dirname must end with '/'. dir must be the
1161 * directory entry corresponding to dirname.
1162 */
1163static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1164{
1165 struct ref_cache *refs = dir->ref_cache;
1166 DIR *d;
1167 struct dirent *de;
1168 int dirnamelen = strlen(dirname);
1169 struct strbuf refname;
1170 struct strbuf path = STRBUF_INIT;
1171 size_t path_baselen;
1172
1173 if (*refs->name)
1174 strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
1175 else
1176 strbuf_git_path(&path, "%s", dirname);
1177 path_baselen = path.len;
1178
1179 d = opendir(path.buf);
1180 if (!d) {
1181 strbuf_release(&path);
1182 return;
1183 }
1184
1185 strbuf_init(&refname, dirnamelen + 257);
1186 strbuf_add(&refname, dirname, dirnamelen);
1187
1188 while ((de = readdir(d)) != NULL) {
1189 unsigned char sha1[20];
1190 struct stat st;
1191 int flag;
1192
1193 if (de->d_name[0] == '.')
1194 continue;
1195 if (ends_with(de->d_name, ".lock"))
1196 continue;
1197 strbuf_addstr(&refname, de->d_name);
1198 strbuf_addstr(&path, de->d_name);
1199 if (stat(path.buf, &st) < 0) {
1200 ; /* silently ignore */
1201 } else if (S_ISDIR(st.st_mode)) {
1202 strbuf_addch(&refname, '/');
1203 add_entry_to_dir(dir,
1204 create_dir_entry(refs, refname.buf,
1205 refname.len, 1));
1206 } else {
1207 int read_ok;
1208
1209 if (*refs->name) {
1210 hashclr(sha1);
1211 flag = 0;
1212 read_ok = !resolve_gitlink_ref(refs->name,
1213 refname.buf, sha1);
1214 } else {
1215 read_ok = !read_ref_full(refname.buf,
1216 RESOLVE_REF_READING,
1217 sha1, &flag);
1218 }
1219
1220 if (!read_ok) {
1221 hashclr(sha1);
1222 flag |= REF_ISBROKEN;
1223 } else if (is_null_sha1(sha1)) {
1224 /*
1225 * It is so astronomically unlikely
1226 * that NULL_SHA1 is the SHA-1 of an
1227 * actual object that we consider its
1228 * appearance in a loose reference
1229 * file to be repo corruption
1230 * (probably due to a software bug).
1231 */
1232 flag |= REF_ISBROKEN;
1233 }
1234
1235 if (check_refname_format(refname.buf,
1236 REFNAME_ALLOW_ONELEVEL)) {
1237 if (!refname_is_safe(refname.buf))
1238 die("loose refname is dangerous: %s", refname.buf);
1239 hashclr(sha1);
1240 flag |= REF_BAD_NAME | REF_ISBROKEN;
1241 }
1242 add_entry_to_dir(dir,
1243 create_ref_entry(refname.buf, sha1, flag, 0));
1244 }
1245 strbuf_setlen(&refname, dirnamelen);
1246 strbuf_setlen(&path, path_baselen);
1247 }
1248 strbuf_release(&refname);
1249 strbuf_release(&path);
1250 closedir(d);
1251}
1252
1253static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1254{
1255 if (!refs->loose) {
1256 /*
1257 * Mark the top-level directory complete because we
1258 * are about to read the only subdirectory that can
1259 * hold references:
1260 */
1261 refs->loose = create_dir_entry(refs, "", 0, 0);
1262 /*
1263 * Create an incomplete entry for "refs/":
1264 */
1265 add_entry_to_dir(get_ref_dir(refs->loose),
1266 create_dir_entry(refs, "refs/", 5, 1));
1267 }
1268 return get_ref_dir(refs->loose);
1269}
1270
7bd9bcf3
MH
1271#define MAXREFLEN (1024)
1272
1273/*
1274 * Called by resolve_gitlink_ref_recursive() after it failed to read
1275 * from the loose refs in ref_cache refs. Find <refname> in the
1276 * packed-refs file for the submodule.
1277 */
1278static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1279 const char *refname, unsigned char *sha1)
1280{
1281 struct ref_entry *ref;
1282 struct ref_dir *dir = get_packed_refs(refs);
1283
1284 ref = find_ref(dir, refname);
1285 if (ref == NULL)
1286 return -1;
1287
1288 hashcpy(sha1, ref->u.value.oid.hash);
1289 return 0;
1290}
1291
1292static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1293 const char *refname, unsigned char *sha1,
1294 int recursion)
1295{
1296 int fd, len;
1297 char buffer[128], *p;
1298 char *path;
1299
2d0663b2 1300 if (recursion > SYMREF_MAXDEPTH || strlen(refname) > MAXREFLEN)
7bd9bcf3
MH
1301 return -1;
1302 path = *refs->name
1303 ? git_pathdup_submodule(refs->name, "%s", refname)
1304 : git_pathdup("%s", refname);
1305 fd = open(path, O_RDONLY);
1306 free(path);
1307 if (fd < 0)
1308 return resolve_gitlink_packed_ref(refs, refname, sha1);
1309
1310 len = read(fd, buffer, sizeof(buffer)-1);
1311 close(fd);
1312 if (len < 0)
1313 return -1;
1314 while (len && isspace(buffer[len-1]))
1315 len--;
1316 buffer[len] = 0;
1317
1318 /* Was it a detached head or an old-fashioned symlink? */
1319 if (!get_sha1_hex(buffer, sha1))
1320 return 0;
1321
1322 /* Symref? */
1323 if (strncmp(buffer, "ref:", 4))
1324 return -1;
1325 p = buffer + 4;
1326 while (isspace(*p))
1327 p++;
1328
1329 return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1330}
1331
1332int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1333{
1334 int len = strlen(path), retval;
a2d5156c 1335 struct strbuf submodule = STRBUF_INIT;
7bd9bcf3
MH
1336 struct ref_cache *refs;
1337
1338 while (len && path[len-1] == '/')
1339 len--;
1340 if (!len)
1341 return -1;
a2d5156c
JK
1342
1343 strbuf_add(&submodule, path, len);
1344 refs = lookup_ref_cache(submodule.buf);
1345 if (!refs) {
1346 if (!is_nonbare_repository_dir(&submodule)) {
1347 strbuf_release(&submodule);
1348 return -1;
1349 }
1350 refs = create_ref_cache(submodule.buf);
1351 }
1352 strbuf_release(&submodule);
7bd9bcf3
MH
1353
1354 retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1355 return retval;
1356}
1357
1358/*
1359 * Return the ref_entry for the given refname from the packed
1360 * references. If it does not exist, return NULL.
1361 */
1362static struct ref_entry *get_packed_ref(const char *refname)
1363{
1364 return find_ref(get_packed_refs(&ref_cache), refname);
1365}
1366
1367/*
419c6f4c 1368 * A loose ref file doesn't exist; check for a packed ref.
7bd9bcf3
MH
1369 */
1370static int resolve_missing_loose_ref(const char *refname,
7bd9bcf3 1371 unsigned char *sha1,
89e82389 1372 unsigned int *flags)
7bd9bcf3
MH
1373{
1374 struct ref_entry *entry;
1375
1376 /*
1377 * The loose reference file does not exist; check for a packed
1378 * reference.
1379 */
1380 entry = get_packed_ref(refname);
1381 if (entry) {
1382 hashcpy(sha1, entry->u.value.oid.hash);
a70a93b7 1383 *flags |= REF_ISPACKED;
7bd9bcf3
MH
1384 return 0;
1385 }
419c6f4c
MH
1386 /* refname is not a packed reference. */
1387 return -1;
7bd9bcf3
MH
1388}
1389
2d0663b2 1390int read_raw_ref(const char *refname, unsigned char *sha1,
92b38093 1391 struct strbuf *referent, unsigned int *type)
7bd9bcf3 1392{
42a38cf7
MH
1393 struct strbuf sb_contents = STRBUF_INIT;
1394 struct strbuf sb_path = STRBUF_INIT;
7048653a
DT
1395 const char *path;
1396 const char *buf;
1397 struct stat st;
1398 int fd;
42a38cf7
MH
1399 int ret = -1;
1400 int save_errno;
7bd9bcf3 1401
fa96ea1b 1402 *type = 0;
42a38cf7
MH
1403 strbuf_reset(&sb_path);
1404 strbuf_git_path(&sb_path, "%s", refname);
1405 path = sb_path.buf;
7bd9bcf3 1406
7048653a
DT
1407stat_ref:
1408 /*
1409 * We might have to loop back here to avoid a race
1410 * condition: first we lstat() the file, then we try
1411 * to read it as a link or as a file. But if somebody
1412 * changes the type of the file (file <-> directory
1413 * <-> symlink) between the lstat() and reading, then
1414 * we don't want to report that as an error but rather
1415 * try again starting with the lstat().
1416 */
7bd9bcf3 1417
7048653a
DT
1418 if (lstat(path, &st) < 0) {
1419 if (errno != ENOENT)
42a38cf7 1420 goto out;
3a0b6b9a 1421 if (resolve_missing_loose_ref(refname, sha1, type)) {
7048653a 1422 errno = ENOENT;
42a38cf7 1423 goto out;
7bd9bcf3 1424 }
42a38cf7
MH
1425 ret = 0;
1426 goto out;
7bd9bcf3 1427 }
7bd9bcf3 1428
7048653a
DT
1429 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1430 if (S_ISLNK(st.st_mode)) {
42a38cf7
MH
1431 strbuf_reset(&sb_contents);
1432 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
7048653a 1433 if (errno == ENOENT || errno == EINVAL)
7bd9bcf3
MH
1434 /* inconsistent with lstat; retry */
1435 goto stat_ref;
1436 else
42a38cf7 1437 goto out;
7bd9bcf3 1438 }
42a38cf7
MH
1439 if (starts_with(sb_contents.buf, "refs/") &&
1440 !check_refname_format(sb_contents.buf, 0)) {
92b38093 1441 strbuf_swap(&sb_contents, referent);
3a0b6b9a 1442 *type |= REF_ISSYMREF;
42a38cf7
MH
1443 ret = 0;
1444 goto out;
7bd9bcf3 1445 }
7048653a 1446 }
7bd9bcf3 1447
7048653a
DT
1448 /* Is it a directory? */
1449 if (S_ISDIR(st.st_mode)) {
e167a567
MH
1450 /*
1451 * Even though there is a directory where the loose
1452 * ref is supposed to be, there could still be a
1453 * packed ref:
1454 */
3a0b6b9a 1455 if (resolve_missing_loose_ref(refname, sha1, type)) {
e167a567
MH
1456 errno = EISDIR;
1457 goto out;
1458 }
1459 ret = 0;
42a38cf7 1460 goto out;
7048653a
DT
1461 }
1462
1463 /*
1464 * Anything else, just open it and try to use it as
1465 * a ref
1466 */
1467 fd = open(path, O_RDONLY);
1468 if (fd < 0) {
1469 if (errno == ENOENT)
1470 /* inconsistent with lstat; retry */
1471 goto stat_ref;
1472 else
42a38cf7 1473 goto out;
7048653a 1474 }
42a38cf7
MH
1475 strbuf_reset(&sb_contents);
1476 if (strbuf_read(&sb_contents, fd, 256) < 0) {
7048653a
DT
1477 int save_errno = errno;
1478 close(fd);
1479 errno = save_errno;
42a38cf7 1480 goto out;
7048653a
DT
1481 }
1482 close(fd);
42a38cf7
MH
1483 strbuf_rtrim(&sb_contents);
1484 buf = sb_contents.buf;
7048653a
DT
1485 if (starts_with(buf, "ref:")) {
1486 buf += 4;
7bd9bcf3
MH
1487 while (isspace(*buf))
1488 buf++;
7048653a 1489
92b38093
MH
1490 strbuf_reset(referent);
1491 strbuf_addstr(referent, buf);
3a0b6b9a 1492 *type |= REF_ISSYMREF;
42a38cf7
MH
1493 ret = 0;
1494 goto out;
7bd9bcf3 1495 }
7bd9bcf3 1496
7048653a
DT
1497 /*
1498 * Please note that FETCH_HEAD has additional
1499 * data after the sha.
1500 */
1501 if (get_sha1_hex(buf, sha1) ||
1502 (buf[40] != '\0' && !isspace(buf[40]))) {
3a0b6b9a 1503 *type |= REF_ISBROKEN;
7048653a 1504 errno = EINVAL;
42a38cf7 1505 goto out;
7048653a
DT
1506 }
1507
42a38cf7 1508 ret = 0;
7bd9bcf3 1509
42a38cf7
MH
1510out:
1511 save_errno = errno;
7bd9bcf3
MH
1512 strbuf_release(&sb_path);
1513 strbuf_release(&sb_contents);
42a38cf7 1514 errno = save_errno;
7bd9bcf3
MH
1515 return ret;
1516}
1517
8415d247
MH
1518static void unlock_ref(struct ref_lock *lock)
1519{
1520 /* Do not free lock->lk -- atexit() still looks at them */
1521 if (lock->lk)
1522 rollback_lock_file(lock->lk);
1523 free(lock->ref_name);
8415d247
MH
1524 free(lock);
1525}
1526
92b1551b
MH
1527/*
1528 * Lock refname, without following symrefs, and set *lock_p to point
1529 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1530 * and type similarly to read_raw_ref().
1531 *
1532 * The caller must verify that refname is a "safe" reference name (in
1533 * the sense of refname_is_safe()) before calling this function.
1534 *
1535 * If the reference doesn't already exist, verify that refname doesn't
1536 * have a D/F conflict with any existing references. extras and skip
1537 * are passed to verify_refname_available_dir() for this check.
1538 *
1539 * If mustexist is not set and the reference is not found or is
1540 * broken, lock the reference anyway but clear sha1.
1541 *
1542 * Return 0 on success. On failure, write an error message to err and
1543 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1544 *
1545 * Implementation note: This function is basically
1546 *
1547 * lock reference
1548 * read_raw_ref()
1549 *
1550 * but it includes a lot more code to
1551 * - Deal with possible races with other processes
1552 * - Avoid calling verify_refname_available_dir() when it can be
1553 * avoided, namely if we were successfully able to read the ref
1554 * - Generate informative error messages in the case of failure
1555 */
1556static int lock_raw_ref(const char *refname, int mustexist,
1557 const struct string_list *extras,
1558 const struct string_list *skip,
1559 struct ref_lock **lock_p,
1560 struct strbuf *referent,
1561 unsigned int *type,
1562 struct strbuf *err)
1563{
1564 struct ref_lock *lock;
1565 struct strbuf ref_file = STRBUF_INIT;
1566 int attempts_remaining = 3;
1567 int ret = TRANSACTION_GENERIC_ERROR;
1568
1569 assert(err);
1570 *type = 0;
1571
1572 /* First lock the file so it can't change out from under us. */
1573
1574 *lock_p = lock = xcalloc(1, sizeof(*lock));
1575
1576 lock->ref_name = xstrdup(refname);
92b1551b
MH
1577 strbuf_git_path(&ref_file, "%s", refname);
1578
1579retry:
1580 switch (safe_create_leading_directories(ref_file.buf)) {
1581 case SCLD_OK:
1582 break; /* success */
1583 case SCLD_EXISTS:
1584 /*
1585 * Suppose refname is "refs/foo/bar". We just failed
1586 * to create the containing directory, "refs/foo",
1587 * because there was a non-directory in the way. This
1588 * indicates a D/F conflict, probably because of
1589 * another reference such as "refs/foo". There is no
1590 * reason to expect this error to be transitory.
1591 */
1592 if (verify_refname_available(refname, extras, skip, err)) {
1593 if (mustexist) {
1594 /*
1595 * To the user the relevant error is
1596 * that the "mustexist" reference is
1597 * missing:
1598 */
1599 strbuf_reset(err);
1600 strbuf_addf(err, "unable to resolve reference '%s'",
1601 refname);
1602 } else {
1603 /*
1604 * The error message set by
1605 * verify_refname_available_dir() is OK.
1606 */
1607 ret = TRANSACTION_NAME_CONFLICT;
1608 }
1609 } else {
1610 /*
1611 * The file that is in the way isn't a loose
1612 * reference. Report it as a low-level
1613 * failure.
1614 */
1615 strbuf_addf(err, "unable to create lock file %s.lock; "
1616 "non-directory in the way",
1617 ref_file.buf);
1618 }
1619 goto error_return;
1620 case SCLD_VANISHED:
1621 /* Maybe another process was tidying up. Try again. */
1622 if (--attempts_remaining > 0)
1623 goto retry;
1624 /* fall through */
1625 default:
1626 strbuf_addf(err, "unable to create directory for %s",
1627 ref_file.buf);
1628 goto error_return;
1629 }
1630
1631 if (!lock->lk)
1632 lock->lk = xcalloc(1, sizeof(struct lock_file));
1633
1634 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1635 if (errno == ENOENT && --attempts_remaining > 0) {
1636 /*
1637 * Maybe somebody just deleted one of the
1638 * directories leading to ref_file. Try
1639 * again:
1640 */
1641 goto retry;
1642 } else {
1643 unable_to_lock_message(ref_file.buf, errno, err);
1644 goto error_return;
1645 }
1646 }
1647
1648 /*
1649 * Now we hold the lock and can read the reference without
1650 * fear that its value will change.
1651 */
1652
1653 if (read_raw_ref(refname, lock->old_oid.hash, referent, type)) {
1654 if (errno == ENOENT) {
1655 if (mustexist) {
1656 /* Garden variety missing reference. */
1657 strbuf_addf(err, "unable to resolve reference '%s'",
1658 refname);
1659 goto error_return;
1660 } else {
1661 /*
1662 * Reference is missing, but that's OK. We
1663 * know that there is not a conflict with
1664 * another loose reference because
1665 * (supposing that we are trying to lock
1666 * reference "refs/foo/bar"):
1667 *
1668 * - We were successfully able to create
1669 * the lockfile refs/foo/bar.lock, so we
1670 * know there cannot be a loose reference
1671 * named "refs/foo".
1672 *
1673 * - We got ENOENT and not EISDIR, so we
1674 * know that there cannot be a loose
1675 * reference named "refs/foo/bar/baz".
1676 */
1677 }
1678 } else if (errno == EISDIR) {
1679 /*
1680 * There is a directory in the way. It might have
1681 * contained references that have been deleted. If
1682 * we don't require that the reference already
1683 * exists, try to remove the directory so that it
1684 * doesn't cause trouble when we want to rename the
1685 * lockfile into place later.
1686 */
1687 if (mustexist) {
1688 /* Garden variety missing reference. */
1689 strbuf_addf(err, "unable to resolve reference '%s'",
1690 refname);
1691 goto error_return;
1692 } else if (remove_dir_recursively(&ref_file,
1693 REMOVE_DIR_EMPTY_ONLY)) {
1694 if (verify_refname_available_dir(
1695 refname, extras, skip,
1696 get_loose_refs(&ref_cache),
1697 err)) {
1698 /*
1699 * The error message set by
1700 * verify_refname_available() is OK.
1701 */
1702 ret = TRANSACTION_NAME_CONFLICT;
1703 goto error_return;
1704 } else {
1705 /*
1706 * We can't delete the directory,
1707 * but we also don't know of any
1708 * references that it should
1709 * contain.
1710 */
1711 strbuf_addf(err, "there is a non-empty directory '%s' "
1712 "blocking reference '%s'",
1713 ref_file.buf, refname);
1714 goto error_return;
1715 }
1716 }
1717 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1718 strbuf_addf(err, "unable to resolve reference '%s': "
1719 "reference broken", refname);
1720 goto error_return;
1721 } else {
1722 strbuf_addf(err, "unable to resolve reference '%s': %s",
1723 refname, strerror(errno));
1724 goto error_return;
1725 }
1726
1727 /*
1728 * If the ref did not exist and we are creating it,
1729 * make sure there is no existing packed ref whose
1730 * name begins with our refname, nor a packed ref
1731 * whose name is a proper prefix of our refname.
1732 */
1733 if (verify_refname_available_dir(
1734 refname, extras, skip,
1735 get_packed_refs(&ref_cache),
1736 err)) {
1737 goto error_return;
1738 }
1739 }
1740
1741 ret = 0;
1742 goto out;
1743
1744error_return:
1745 unlock_ref(lock);
1746 *lock_p = NULL;
1747
1748out:
1749 strbuf_release(&ref_file);
1750 return ret;
1751}
1752
7bd9bcf3
MH
1753/*
1754 * Peel the entry (if possible) and return its new peel_status. If
1755 * repeel is true, re-peel the entry even if there is an old peeled
1756 * value that is already stored in it.
1757 *
1758 * It is OK to call this function with a packed reference entry that
1759 * might be stale and might even refer to an object that has since
1760 * been garbage-collected. In such a case, if the entry has
1761 * REF_KNOWS_PEELED then leave the status unchanged and return
1762 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1763 */
1764static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1765{
1766 enum peel_status status;
1767
1768 if (entry->flag & REF_KNOWS_PEELED) {
1769 if (repeel) {
1770 entry->flag &= ~REF_KNOWS_PEELED;
1771 oidclr(&entry->u.value.peeled);
1772 } else {
1773 return is_null_oid(&entry->u.value.peeled) ?
1774 PEEL_NON_TAG : PEEL_PEELED;
1775 }
1776 }
1777 if (entry->flag & REF_ISBROKEN)
1778 return PEEL_BROKEN;
1779 if (entry->flag & REF_ISSYMREF)
1780 return PEEL_IS_SYMREF;
1781
1782 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1783 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1784 entry->flag |= REF_KNOWS_PEELED;
1785 return status;
1786}
1787
1788int peel_ref(const char *refname, unsigned char *sha1)
1789{
1790 int flag;
1791 unsigned char base[20];
1792
1793 if (current_ref && (current_ref->name == refname
1794 || !strcmp(current_ref->name, refname))) {
1795 if (peel_entry(current_ref, 0))
1796 return -1;
1797 hashcpy(sha1, current_ref->u.value.peeled.hash);
1798 return 0;
1799 }
1800
1801 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1802 return -1;
1803
1804 /*
1805 * If the reference is packed, read its ref_entry from the
1806 * cache in the hope that we already know its peeled value.
1807 * We only try this optimization on packed references because
1808 * (a) forcing the filling of the loose reference cache could
1809 * be expensive and (b) loose references anyway usually do not
1810 * have REF_KNOWS_PEELED.
1811 */
1812 if (flag & REF_ISPACKED) {
1813 struct ref_entry *r = get_packed_ref(refname);
1814 if (r) {
1815 if (peel_entry(r, 0))
1816 return -1;
1817 hashcpy(sha1, r->u.value.peeled.hash);
1818 return 0;
1819 }
1820 }
1821
1822 return peel_object(base, sha1);
1823}
1824
1825/*
1826 * Call fn for each reference in the specified ref_cache, omitting
1827 * references not in the containing_dir of base. fn is called for all
1828 * references, including broken ones. If fn ever returns a non-zero
1829 * value, stop the iteration and return that value; otherwise, return
1830 * 0.
1831 */
1832static int do_for_each_entry(struct ref_cache *refs, const char *base,
1833 each_ref_entry_fn fn, void *cb_data)
1834{
1835 struct packed_ref_cache *packed_ref_cache;
1836 struct ref_dir *loose_dir;
1837 struct ref_dir *packed_dir;
1838 int retval = 0;
1839
1840 /*
1841 * We must make sure that all loose refs are read before accessing the
1842 * packed-refs file; this avoids a race condition in which loose refs
1843 * are migrated to the packed-refs file by a simultaneous process, but
1844 * our in-memory view is from before the migration. get_packed_ref_cache()
1845 * takes care of making sure our view is up to date with what is on
1846 * disk.
1847 */
1848 loose_dir = get_loose_refs(refs);
1849 if (base && *base) {
1850 loose_dir = find_containing_dir(loose_dir, base, 0);
1851 }
1852 if (loose_dir)
1853 prime_ref_dir(loose_dir);
1854
1855 packed_ref_cache = get_packed_ref_cache(refs);
1856 acquire_packed_ref_cache(packed_ref_cache);
1857 packed_dir = get_packed_ref_dir(packed_ref_cache);
1858 if (base && *base) {
1859 packed_dir = find_containing_dir(packed_dir, base, 0);
1860 }
1861
1862 if (packed_dir && loose_dir) {
1863 sort_ref_dir(packed_dir);
1864 sort_ref_dir(loose_dir);
1865 retval = do_for_each_entry_in_dirs(
1866 packed_dir, loose_dir, fn, cb_data);
1867 } else if (packed_dir) {
1868 sort_ref_dir(packed_dir);
1869 retval = do_for_each_entry_in_dir(
1870 packed_dir, 0, fn, cb_data);
1871 } else if (loose_dir) {
1872 sort_ref_dir(loose_dir);
1873 retval = do_for_each_entry_in_dir(
1874 loose_dir, 0, fn, cb_data);
1875 }
1876
1877 release_packed_ref_cache(packed_ref_cache);
1878 return retval;
1879}
1880
1881/*
1882 * Call fn for each reference in the specified ref_cache for which the
1883 * refname begins with base. If trim is non-zero, then trim that many
1884 * characters off the beginning of each refname before passing the
1885 * refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
1886 * broken references in the iteration. If fn ever returns a non-zero
1887 * value, stop the iteration and return that value; otherwise, return
1888 * 0.
1889 */
93770590
DT
1890int do_for_each_ref(const char *submodule, const char *base,
1891 each_ref_fn fn, int trim, int flags, void *cb_data)
7bd9bcf3
MH
1892{
1893 struct ref_entry_cb data;
93770590
DT
1894 struct ref_cache *refs;
1895
1896 refs = get_ref_cache(submodule);
7bd9bcf3
MH
1897 data.base = base;
1898 data.trim = trim;
1899 data.flags = flags;
1900 data.fn = fn;
1901 data.cb_data = cb_data;
1902
1903 if (ref_paranoia < 0)
1904 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1905 if (ref_paranoia)
1906 data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1907
1908 return do_for_each_entry(refs, base, do_one_ref, &data);
1909}
1910
7bd9bcf3
MH
1911/*
1912 * Verify that the reference locked by lock has the value old_sha1.
1913 * Fail if the reference doesn't exist and mustexist is set. Return 0
1914 * on success. On error, write an error message to err, set errno, and
1915 * return a negative value.
1916 */
1917static int verify_lock(struct ref_lock *lock,
1918 const unsigned char *old_sha1, int mustexist,
1919 struct strbuf *err)
1920{
1921 assert(err);
1922
1923 if (read_ref_full(lock->ref_name,
1924 mustexist ? RESOLVE_REF_READING : 0,
1925 lock->old_oid.hash, NULL)) {
6294dcb4
JK
1926 if (old_sha1) {
1927 int save_errno = errno;
0568c8e9 1928 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
6294dcb4
JK
1929 errno = save_errno;
1930 return -1;
1931 } else {
1932 hashclr(lock->old_oid.hash);
1933 return 0;
1934 }
7bd9bcf3 1935 }
6294dcb4 1936 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
0568c8e9 1937 strbuf_addf(err, "ref '%s' is at %s but expected %s",
7bd9bcf3
MH
1938 lock->ref_name,
1939 sha1_to_hex(lock->old_oid.hash),
1940 sha1_to_hex(old_sha1));
1941 errno = EBUSY;
1942 return -1;
1943 }
1944 return 0;
1945}
1946
1947static int remove_empty_directories(struct strbuf *path)
1948{
1949 /*
1950 * we want to create a file but there is a directory there;
1951 * if that is an empty directory (or a directory that contains
1952 * only empty directories), remove them.
1953 */
1954 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
1955}
1956
1957/*
1958 * Locks a ref returning the lock on success and NULL on failure.
1959 * On failure errno is set to something meaningful.
1960 */
1961static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1962 const unsigned char *old_sha1,
1963 const struct string_list *extras,
1964 const struct string_list *skip,
bcb497d0 1965 unsigned int flags, int *type,
7bd9bcf3
MH
1966 struct strbuf *err)
1967{
1968 struct strbuf ref_file = STRBUF_INIT;
7bd9bcf3
MH
1969 struct ref_lock *lock;
1970 int last_errno = 0;
7a418f3a 1971 int lflags = LOCK_NO_DEREF;
7bd9bcf3 1972 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
7a418f3a 1973 int resolve_flags = RESOLVE_REF_NO_RECURSE;
7bd9bcf3 1974 int attempts_remaining = 3;
7a418f3a 1975 int resolved;
7bd9bcf3
MH
1976
1977 assert(err);
1978
1979 lock = xcalloc(1, sizeof(struct ref_lock));
1980
1981 if (mustexist)
1982 resolve_flags |= RESOLVE_REF_READING;
2859dcd4 1983 if (flags & REF_DELETING)
7bd9bcf3 1984 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
7bd9bcf3 1985
7a418f3a
MH
1986 strbuf_git_path(&ref_file, "%s", refname);
1987 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
1988 lock->old_oid.hash, type);
1989 if (!resolved && errno == EISDIR) {
7bd9bcf3
MH
1990 /*
1991 * we are trying to lock foo but we used to
1992 * have foo/bar which now does not exist;
1993 * it is normal for the empty directory 'foo'
1994 * to remain.
1995 */
7a418f3a 1996 if (remove_empty_directories(&ref_file)) {
7bd9bcf3 1997 last_errno = errno;
7a418f3a 1998 if (!verify_refname_available_dir(refname, extras, skip,
7bd9bcf3
MH
1999 get_loose_refs(&ref_cache), err))
2000 strbuf_addf(err, "there are still refs under '%s'",
7a418f3a 2001 refname);
7bd9bcf3
MH
2002 goto error_return;
2003 }
7a418f3a
MH
2004 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2005 lock->old_oid.hash, type);
7bd9bcf3 2006 }
7a418f3a 2007 if (!resolved) {
7bd9bcf3
MH
2008 last_errno = errno;
2009 if (last_errno != ENOTDIR ||
7a418f3a 2010 !verify_refname_available_dir(refname, extras, skip,
7bd9bcf3 2011 get_loose_refs(&ref_cache), err))
0568c8e9 2012 strbuf_addf(err, "unable to resolve reference '%s': %s",
7a418f3a 2013 refname, strerror(last_errno));
7bd9bcf3
MH
2014
2015 goto error_return;
2016 }
2859dcd4 2017
7bd9bcf3
MH
2018 /*
2019 * If the ref did not exist and we are creating it, make sure
2020 * there is no existing packed ref whose name begins with our
2021 * refname, nor a packed ref whose name is a proper prefix of
2022 * our refname.
2023 */
2024 if (is_null_oid(&lock->old_oid) &&
2025 verify_refname_available_dir(refname, extras, skip,
2026 get_packed_refs(&ref_cache), err)) {
2027 last_errno = ENOTDIR;
2028 goto error_return;
2029 }
2030
2031 lock->lk = xcalloc(1, sizeof(struct lock_file));
2032
7bd9bcf3 2033 lock->ref_name = xstrdup(refname);
7bd9bcf3
MH
2034
2035 retry:
2036 switch (safe_create_leading_directories_const(ref_file.buf)) {
2037 case SCLD_OK:
2038 break; /* success */
2039 case SCLD_VANISHED:
2040 if (--attempts_remaining > 0)
2041 goto retry;
2042 /* fall through */
2043 default:
2044 last_errno = errno;
0568c8e9 2045 strbuf_addf(err, "unable to create directory for '%s'",
7bd9bcf3
MH
2046 ref_file.buf);
2047 goto error_return;
2048 }
2049
2050 if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
2051 last_errno = errno;
2052 if (errno == ENOENT && --attempts_remaining > 0)
2053 /*
2054 * Maybe somebody just deleted one of the
2055 * directories leading to ref_file. Try
2056 * again:
2057 */
2058 goto retry;
2059 else {
2060 unable_to_lock_message(ref_file.buf, errno, err);
2061 goto error_return;
2062 }
2063 }
6294dcb4 2064 if (verify_lock(lock, old_sha1, mustexist, err)) {
7bd9bcf3
MH
2065 last_errno = errno;
2066 goto error_return;
2067 }
2068 goto out;
2069
2070 error_return:
2071 unlock_ref(lock);
2072 lock = NULL;
2073
2074 out:
2075 strbuf_release(&ref_file);
7bd9bcf3
MH
2076 errno = last_errno;
2077 return lock;
2078}
2079
2080/*
2081 * Write an entry to the packed-refs file for the specified refname.
2082 * If peeled is non-NULL, write it as the entry's peeled value.
2083 */
2084static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2085 unsigned char *peeled)
2086{
2087 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2088 if (peeled)
2089 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2090}
2091
2092/*
2093 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2094 */
2095static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2096{
2097 enum peel_status peel_status = peel_entry(entry, 0);
2098
2099 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2100 error("internal error: %s is not a valid packed reference!",
2101 entry->name);
2102 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2103 peel_status == PEEL_PEELED ?
2104 entry->u.value.peeled.hash : NULL);
2105 return 0;
2106}
2107
2108/*
2109 * Lock the packed-refs file for writing. Flags is passed to
2110 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2111 * errno appropriately and return a nonzero value.
2112 */
2113static int lock_packed_refs(int flags)
2114{
2115 static int timeout_configured = 0;
2116 static int timeout_value = 1000;
2117
2118 struct packed_ref_cache *packed_ref_cache;
2119
2120 if (!timeout_configured) {
2121 git_config_get_int("core.packedrefstimeout", &timeout_value);
2122 timeout_configured = 1;
2123 }
2124
2125 if (hold_lock_file_for_update_timeout(
2126 &packlock, git_path("packed-refs"),
2127 flags, timeout_value) < 0)
2128 return -1;
2129 /*
2130 * Get the current packed-refs while holding the lock. If the
2131 * packed-refs file has been modified since we last read it,
2132 * this will automatically invalidate the cache and re-read
2133 * the packed-refs file.
2134 */
2135 packed_ref_cache = get_packed_ref_cache(&ref_cache);
2136 packed_ref_cache->lock = &packlock;
2137 /* Increment the reference count to prevent it from being freed: */
2138 acquire_packed_ref_cache(packed_ref_cache);
2139 return 0;
2140}
2141
2142/*
2143 * Write the current version of the packed refs cache from memory to
2144 * disk. The packed-refs file must already be locked for writing (see
2145 * lock_packed_refs()). Return zero on success. On errors, set errno
2146 * and return a nonzero value
2147 */
2148static int commit_packed_refs(void)
2149{
2150 struct packed_ref_cache *packed_ref_cache =
2151 get_packed_ref_cache(&ref_cache);
2152 int error = 0;
2153 int save_errno = 0;
2154 FILE *out;
2155
2156 if (!packed_ref_cache->lock)
2157 die("internal error: packed-refs not locked");
2158
2159 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2160 if (!out)
2161 die_errno("unable to fdopen packed-refs descriptor");
2162
2163 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2164 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2165 0, write_packed_entry_fn, out);
2166
2167 if (commit_lock_file(packed_ref_cache->lock)) {
2168 save_errno = errno;
2169 error = -1;
2170 }
2171 packed_ref_cache->lock = NULL;
2172 release_packed_ref_cache(packed_ref_cache);
2173 errno = save_errno;
2174 return error;
2175}
2176
2177/*
2178 * Rollback the lockfile for the packed-refs file, and discard the
2179 * in-memory packed reference cache. (The packed-refs file will be
2180 * read anew if it is needed again after this function is called.)
2181 */
2182static void rollback_packed_refs(void)
2183{
2184 struct packed_ref_cache *packed_ref_cache =
2185 get_packed_ref_cache(&ref_cache);
2186
2187 if (!packed_ref_cache->lock)
2188 die("internal error: packed-refs not locked");
2189 rollback_lock_file(packed_ref_cache->lock);
2190 packed_ref_cache->lock = NULL;
2191 release_packed_ref_cache(packed_ref_cache);
2192 clear_packed_ref_cache(&ref_cache);
2193}
2194
2195struct ref_to_prune {
2196 struct ref_to_prune *next;
2197 unsigned char sha1[20];
2198 char name[FLEX_ARRAY];
2199};
2200
2201struct pack_refs_cb_data {
2202 unsigned int flags;
2203 struct ref_dir *packed_refs;
2204 struct ref_to_prune *ref_to_prune;
2205};
2206
2207/*
2208 * An each_ref_entry_fn that is run over loose references only. If
2209 * the loose reference can be packed, add an entry in the packed ref
2210 * cache. If the reference should be pruned, also add it to
2211 * ref_to_prune in the pack_refs_cb_data.
2212 */
2213static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2214{
2215 struct pack_refs_cb_data *cb = cb_data;
2216 enum peel_status peel_status;
2217 struct ref_entry *packed_entry;
2218 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2219
2220 /* Do not pack per-worktree refs: */
2221 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2222 return 0;
2223
2224 /* ALWAYS pack tags */
2225 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2226 return 0;
2227
2228 /* Do not pack symbolic or broken refs: */
2229 if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
2230 return 0;
2231
2232 /* Add a packed ref cache entry equivalent to the loose entry. */
2233 peel_status = peel_entry(entry, 1);
2234 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2235 die("internal error peeling reference %s (%s)",
2236 entry->name, oid_to_hex(&entry->u.value.oid));
2237 packed_entry = find_ref(cb->packed_refs, entry->name);
2238 if (packed_entry) {
2239 /* Overwrite existing packed entry with info from loose entry */
2240 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2241 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2242 } else {
2243 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2244 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2245 add_ref(cb->packed_refs, packed_entry);
2246 }
2247 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2248
2249 /* Schedule the loose reference for pruning if requested. */
2250 if ((cb->flags & PACK_REFS_PRUNE)) {
96ffc06f
JK
2251 struct ref_to_prune *n;
2252 FLEX_ALLOC_STR(n, name, entry->name);
7bd9bcf3 2253 hashcpy(n->sha1, entry->u.value.oid.hash);
7bd9bcf3
MH
2254 n->next = cb->ref_to_prune;
2255 cb->ref_to_prune = n;
2256 }
2257 return 0;
2258}
2259
2260/*
2261 * Remove empty parents, but spare refs/ and immediate subdirs.
2262 * Note: munges *name.
2263 */
2264static void try_remove_empty_parents(char *name)
2265{
2266 char *p, *q;
2267 int i;
2268 p = name;
2269 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2270 while (*p && *p != '/')
2271 p++;
2272 /* tolerate duplicate slashes; see check_refname_format() */
2273 while (*p == '/')
2274 p++;
2275 }
2276 for (q = p; *q; q++)
2277 ;
2278 while (1) {
2279 while (q > p && *q != '/')
2280 q--;
2281 while (q > p && *(q-1) == '/')
2282 q--;
2283 if (q == p)
2284 break;
2285 *q = '\0';
2286 if (rmdir(git_path("%s", name)))
2287 break;
2288 }
2289}
2290
2291/* make sure nobody touched the ref, and unlink */
2292static void prune_ref(struct ref_to_prune *r)
2293{
2294 struct ref_transaction *transaction;
2295 struct strbuf err = STRBUF_INIT;
2296
2297 if (check_refname_format(r->name, 0))
2298 return;
2299
2300 transaction = ref_transaction_begin(&err);
2301 if (!transaction ||
2302 ref_transaction_delete(transaction, r->name, r->sha1,
c52ce248 2303 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
7bd9bcf3
MH
2304 ref_transaction_commit(transaction, &err)) {
2305 ref_transaction_free(transaction);
2306 error("%s", err.buf);
2307 strbuf_release(&err);
2308 return;
2309 }
2310 ref_transaction_free(transaction);
2311 strbuf_release(&err);
2312 try_remove_empty_parents(r->name);
2313}
2314
2315static void prune_refs(struct ref_to_prune *r)
2316{
2317 while (r) {
2318 prune_ref(r);
2319 r = r->next;
2320 }
2321}
2322
2323int pack_refs(unsigned int flags)
2324{
2325 struct pack_refs_cb_data cbdata;
2326
2327 memset(&cbdata, 0, sizeof(cbdata));
2328 cbdata.flags = flags;
2329
2330 lock_packed_refs(LOCK_DIE_ON_ERROR);
2331 cbdata.packed_refs = get_packed_refs(&ref_cache);
2332
2333 do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2334 pack_if_possible_fn, &cbdata);
2335
2336 if (commit_packed_refs())
2337 die_errno("unable to overwrite old ref-pack file");
2338
2339 prune_refs(cbdata.ref_to_prune);
2340 return 0;
2341}
2342
2343/*
2344 * Rewrite the packed-refs file, omitting any refs listed in
2345 * 'refnames'. On error, leave packed-refs unchanged, write an error
2346 * message to 'err', and return a nonzero value.
2347 *
2348 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2349 */
2350static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
2351{
2352 struct ref_dir *packed;
2353 struct string_list_item *refname;
2354 int ret, needs_repacking = 0, removed = 0;
2355
2356 assert(err);
2357
2358 /* Look for a packed ref */
2359 for_each_string_list_item(refname, refnames) {
2360 if (get_packed_ref(refname->string)) {
2361 needs_repacking = 1;
2362 break;
2363 }
2364 }
2365
2366 /* Avoid locking if we have nothing to do */
2367 if (!needs_repacking)
2368 return 0; /* no refname exists in packed refs */
2369
2370 if (lock_packed_refs(0)) {
2371 unable_to_lock_message(git_path("packed-refs"), errno, err);
2372 return -1;
2373 }
2374 packed = get_packed_refs(&ref_cache);
2375
2376 /* Remove refnames from the cache */
2377 for_each_string_list_item(refname, refnames)
2378 if (remove_entry(packed, refname->string) != -1)
2379 removed = 1;
2380 if (!removed) {
2381 /*
2382 * All packed entries disappeared while we were
2383 * acquiring the lock.
2384 */
2385 rollback_packed_refs();
2386 return 0;
2387 }
2388
2389 /* Write what remains */
2390 ret = commit_packed_refs();
2391 if (ret)
2392 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2393 strerror(errno));
2394 return ret;
2395}
2396
2397static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2398{
2399 assert(err);
2400
2401 if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2402 /*
2403 * loose. The loose file name is the same as the
2404 * lockfile name, minus ".lock":
2405 */
2406 char *loose_filename = get_locked_file_path(lock->lk);
2407 int res = unlink_or_msg(loose_filename, err);
2408 free(loose_filename);
2409 if (res)
2410 return 1;
2411 }
2412 return 0;
2413}
2414
2415int delete_refs(struct string_list *refnames)
2416{
2417 struct strbuf err = STRBUF_INIT;
2418 int i, result = 0;
2419
2420 if (!refnames->nr)
2421 return 0;
2422
2423 result = repack_without_refs(refnames, &err);
2424 if (result) {
2425 /*
2426 * If we failed to rewrite the packed-refs file, then
2427 * it is unsafe to try to remove loose refs, because
2428 * doing so might expose an obsolete packed value for
2429 * a reference that might even point at an object that
2430 * has been garbage collected.
2431 */
2432 if (refnames->nr == 1)
2433 error(_("could not delete reference %s: %s"),
2434 refnames->items[0].string, err.buf);
2435 else
2436 error(_("could not delete references: %s"), err.buf);
2437
2438 goto out;
2439 }
2440
2441 for (i = 0; i < refnames->nr; i++) {
2442 const char *refname = refnames->items[i].string;
2443
2444 if (delete_ref(refname, NULL, 0))
2445 result |= error(_("could not remove reference %s"), refname);
2446 }
2447
2448out:
2449 strbuf_release(&err);
2450 return result;
2451}
2452
2453/*
2454 * People using contrib's git-new-workdir have .git/logs/refs ->
2455 * /some/other/path/.git/logs/refs, and that may live on another device.
2456 *
2457 * IOW, to avoid cross device rename errors, the temporary renamed log must
2458 * live into logs/refs.
2459 */
2460#define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
2461
2462static int rename_tmp_log(const char *newrefname)
2463{
2464 int attempts_remaining = 4;
2465 struct strbuf path = STRBUF_INIT;
2466 int ret = -1;
2467
2468 retry:
2469 strbuf_reset(&path);
2470 strbuf_git_path(&path, "logs/%s", newrefname);
2471 switch (safe_create_leading_directories_const(path.buf)) {
2472 case SCLD_OK:
2473 break; /* success */
2474 case SCLD_VANISHED:
2475 if (--attempts_remaining > 0)
2476 goto retry;
2477 /* fall through */
2478 default:
2479 error("unable to create directory for %s", newrefname);
2480 goto out;
2481 }
2482
2483 if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
2484 if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2485 /*
2486 * rename(a, b) when b is an existing
2487 * directory ought to result in ISDIR, but
2488 * Solaris 5.8 gives ENOTDIR. Sheesh.
2489 */
2490 if (remove_empty_directories(&path)) {
2491 error("Directory not empty: logs/%s", newrefname);
2492 goto out;
2493 }
2494 goto retry;
2495 } else if (errno == ENOENT && --attempts_remaining > 0) {
2496 /*
2497 * Maybe another process just deleted one of
2498 * the directories in the path to newrefname.
2499 * Try again from the beginning.
2500 */
2501 goto retry;
2502 } else {
2503 error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2504 newrefname, strerror(errno));
2505 goto out;
2506 }
2507 }
2508 ret = 0;
2509out:
2510 strbuf_release(&path);
2511 return ret;
2512}
2513
2514int verify_refname_available(const char *newname,
3a8af7be
MH
2515 const struct string_list *extras,
2516 const struct string_list *skip,
7bd9bcf3
MH
2517 struct strbuf *err)
2518{
2519 struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
2520 struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
2521
2522 if (verify_refname_available_dir(newname, extras, skip,
2523 packed_refs, err) ||
2524 verify_refname_available_dir(newname, extras, skip,
2525 loose_refs, err))
2526 return -1;
2527
2528 return 0;
2529}
2530
7bd9bcf3
MH
2531static int write_ref_to_lockfile(struct ref_lock *lock,
2532 const unsigned char *sha1, struct strbuf *err);
2533static int commit_ref_update(struct ref_lock *lock,
2534 const unsigned char *sha1, const char *logmsg,
5d9b2de4 2535 struct strbuf *err);
7bd9bcf3
MH
2536
2537int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2538{
2539 unsigned char sha1[20], orig_sha1[20];
2540 int flag = 0, logmoved = 0;
2541 struct ref_lock *lock;
2542 struct stat loginfo;
2543 int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
7bd9bcf3
MH
2544 struct strbuf err = STRBUF_INIT;
2545
2546 if (log && S_ISLNK(loginfo.st_mode))
2547 return error("reflog for %s is a symlink", oldrefname);
2548
12fd3496
DT
2549 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2550 orig_sha1, &flag))
e711b1af
MH
2551 return error("refname %s not found", oldrefname);
2552
7bd9bcf3
MH
2553 if (flag & REF_ISSYMREF)
2554 return error("refname %s is a symbolic ref, renaming it is not supported",
2555 oldrefname);
7bd9bcf3
MH
2556 if (!rename_ref_available(oldrefname, newrefname))
2557 return 1;
2558
2559 if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2560 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2561 oldrefname, strerror(errno));
2562
2563 if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2564 error("unable to delete old %s", oldrefname);
2565 goto rollback;
2566 }
2567
12fd3496
DT
2568 /*
2569 * Since we are doing a shallow lookup, sha1 is not the
2570 * correct value to pass to delete_ref as old_sha1. But that
2571 * doesn't matter, because an old_sha1 check wouldn't add to
2572 * the safety anyway; we want to delete the reference whatever
2573 * its current value.
2574 */
2575 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2576 sha1, NULL) &&
2577 delete_ref(newrefname, NULL, REF_NODEREF)) {
7bd9bcf3
MH
2578 if (errno==EISDIR) {
2579 struct strbuf path = STRBUF_INIT;
2580 int result;
2581
2582 strbuf_git_path(&path, "%s", newrefname);
2583 result = remove_empty_directories(&path);
2584 strbuf_release(&path);
2585
2586 if (result) {
2587 error("Directory not empty: %s", newrefname);
2588 goto rollback;
2589 }
2590 } else {
2591 error("unable to delete existing %s", newrefname);
2592 goto rollback;
2593 }
2594 }
2595
2596 if (log && rename_tmp_log(newrefname))
2597 goto rollback;
2598
2599 logmoved = log;
2600
12fd3496
DT
2601 lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, REF_NODEREF,
2602 NULL, &err);
7bd9bcf3
MH
2603 if (!lock) {
2604 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2605 strbuf_release(&err);
2606 goto rollback;
2607 }
2608 hashcpy(lock->old_oid.hash, orig_sha1);
2609
2610 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2611 commit_ref_update(lock, orig_sha1, logmsg, &err)) {
7bd9bcf3
MH
2612 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2613 strbuf_release(&err);
2614 goto rollback;
2615 }
2616
2617 return 0;
2618
2619 rollback:
12fd3496
DT
2620 lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, REF_NODEREF,
2621 NULL, &err);
7bd9bcf3
MH
2622 if (!lock) {
2623 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2624 strbuf_release(&err);
2625 goto rollbacklog;
2626 }
2627
2628 flag = log_all_ref_updates;
2629 log_all_ref_updates = 0;
2630 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2631 commit_ref_update(lock, orig_sha1, NULL, &err)) {
7bd9bcf3
MH
2632 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2633 strbuf_release(&err);
2634 }
2635 log_all_ref_updates = flag;
2636
2637 rollbacklog:
2638 if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2639 error("unable to restore logfile %s from %s: %s",
2640 oldrefname, newrefname, strerror(errno));
2641 if (!logmoved && log &&
2642 rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2643 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2644 oldrefname, strerror(errno));
2645
2646 return 1;
2647}
2648
2649static int close_ref(struct ref_lock *lock)
2650{
2651 if (close_lock_file(lock->lk))
2652 return -1;
2653 return 0;
2654}
2655
2656static int commit_ref(struct ref_lock *lock)
2657{
5387c0d8
MH
2658 char *path = get_locked_file_path(lock->lk);
2659 struct stat st;
2660
2661 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2662 /*
2663 * There is a directory at the path we want to rename
2664 * the lockfile to. Hopefully it is empty; try to
2665 * delete it.
2666 */
2667 size_t len = strlen(path);
2668 struct strbuf sb_path = STRBUF_INIT;
2669
2670 strbuf_attach(&sb_path, path, len, len);
2671
2672 /*
2673 * If this fails, commit_lock_file() will also fail
2674 * and will report the problem.
2675 */
2676 remove_empty_directories(&sb_path);
2677 strbuf_release(&sb_path);
2678 } else {
2679 free(path);
2680 }
2681
7bd9bcf3
MH
2682 if (commit_lock_file(lock->lk))
2683 return -1;
2684 return 0;
2685}
2686
2687/*
2688 * Create a reflog for a ref. If force_create = 0, the reflog will
2689 * only be created for certain refs (those for which
2690 * should_autocreate_reflog returns non-zero. Otherwise, create it
2691 * regardless of the ref name. Fill in *err and return -1 on failure.
2692 */
2693static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
2694{
2695 int logfd, oflags = O_APPEND | O_WRONLY;
2696
2697 strbuf_git_path(logfile, "logs/%s", refname);
2698 if (force_create || should_autocreate_reflog(refname)) {
2699 if (safe_create_leading_directories(logfile->buf) < 0) {
0568c8e9 2700 strbuf_addf(err, "unable to create directory for '%s': "
7bd9bcf3
MH
2701 "%s", logfile->buf, strerror(errno));
2702 return -1;
2703 }
2704 oflags |= O_CREAT;
2705 }
2706
2707 logfd = open(logfile->buf, oflags, 0666);
2708 if (logfd < 0) {
2709 if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
2710 return 0;
2711
2712 if (errno == EISDIR) {
2713 if (remove_empty_directories(logfile)) {
0568c8e9 2714 strbuf_addf(err, "there are still logs under "
7bd9bcf3
MH
2715 "'%s'", logfile->buf);
2716 return -1;
2717 }
2718 logfd = open(logfile->buf, oflags, 0666);
2719 }
2720
2721 if (logfd < 0) {
0568c8e9 2722 strbuf_addf(err, "unable to append to '%s': %s",
7bd9bcf3
MH
2723 logfile->buf, strerror(errno));
2724 return -1;
2725 }
2726 }
2727
2728 adjust_shared_perm(logfile->buf);
2729 close(logfd);
2730 return 0;
2731}
2732
2733
2734int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
2735{
2736 int ret;
2737 struct strbuf sb = STRBUF_INIT;
2738
2739 ret = log_ref_setup(refname, &sb, err, force_create);
2740 strbuf_release(&sb);
2741 return ret;
2742}
2743
2744static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
2745 const unsigned char *new_sha1,
2746 const char *committer, const char *msg)
2747{
2748 int msglen, written;
2749 unsigned maxlen, len;
2750 char *logrec;
2751
2752 msglen = msg ? strlen(msg) : 0;
2753 maxlen = strlen(committer) + msglen + 100;
2754 logrec = xmalloc(maxlen);
2755 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
2756 sha1_to_hex(old_sha1),
2757 sha1_to_hex(new_sha1),
2758 committer);
2759 if (msglen)
2760 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
2761
2762 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
2763 free(logrec);
2764 if (written != len)
2765 return -1;
2766
2767 return 0;
2768}
2769
2770static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
2771 const unsigned char *new_sha1, const char *msg,
2772 struct strbuf *logfile, int flags,
2773 struct strbuf *err)
2774{
2775 int logfd, result, oflags = O_APPEND | O_WRONLY;
2776
2777 if (log_all_ref_updates < 0)
2778 log_all_ref_updates = !is_bare_repository();
2779
2780 result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
2781
2782 if (result)
2783 return result;
2784
2785 logfd = open(logfile->buf, oflags);
2786 if (logfd < 0)
2787 return 0;
2788 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
2789 git_committer_info(0), msg);
2790 if (result) {
0568c8e9 2791 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
2792 strerror(errno));
2793 close(logfd);
2794 return -1;
2795 }
2796 if (close(logfd)) {
0568c8e9 2797 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
2798 strerror(errno));
2799 return -1;
2800 }
2801 return 0;
2802}
2803
2804static int log_ref_write(const char *refname, const unsigned char *old_sha1,
2805 const unsigned char *new_sha1, const char *msg,
2806 int flags, struct strbuf *err)
5f3c3a4e
DT
2807{
2808 return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
2809 err);
2810}
2811
2812int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
2813 const unsigned char *new_sha1, const char *msg,
2814 int flags, struct strbuf *err)
7bd9bcf3
MH
2815{
2816 struct strbuf sb = STRBUF_INIT;
2817 int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
2818 err);
2819 strbuf_release(&sb);
2820 return ret;
2821}
2822
2823/*
2824 * Write sha1 into the open lockfile, then close the lockfile. On
2825 * errors, rollback the lockfile, fill in *err and
2826 * return -1.
2827 */
2828static int write_ref_to_lockfile(struct ref_lock *lock,
2829 const unsigned char *sha1, struct strbuf *err)
2830{
2831 static char term = '\n';
2832 struct object *o;
2833 int fd;
2834
2835 o = parse_object(sha1);
2836 if (!o) {
2837 strbuf_addf(err,
0568c8e9 2838 "trying to write ref '%s' with nonexistent object %s",
7bd9bcf3
MH
2839 lock->ref_name, sha1_to_hex(sha1));
2840 unlock_ref(lock);
2841 return -1;
2842 }
2843 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
2844 strbuf_addf(err,
0568c8e9 2845 "trying to write non-commit object %s to branch '%s'",
7bd9bcf3
MH
2846 sha1_to_hex(sha1), lock->ref_name);
2847 unlock_ref(lock);
2848 return -1;
2849 }
2850 fd = get_lock_file_fd(lock->lk);
2851 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
2852 write_in_full(fd, &term, 1) != 1 ||
2853 close_ref(lock) < 0) {
2854 strbuf_addf(err,
0568c8e9 2855 "couldn't write '%s'", get_lock_file_path(lock->lk));
7bd9bcf3
MH
2856 unlock_ref(lock);
2857 return -1;
2858 }
2859 return 0;
2860}
2861
2862/*
2863 * Commit a change to a loose reference that has already been written
2864 * to the loose reference lockfile. Also update the reflogs if
2865 * necessary, using the specified lockmsg (which can be NULL).
2866 */
2867static int commit_ref_update(struct ref_lock *lock,
2868 const unsigned char *sha1, const char *logmsg,
5d9b2de4 2869 struct strbuf *err)
7bd9bcf3
MH
2870{
2871 clear_loose_ref_cache(&ref_cache);
7a418f3a 2872 if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
7bd9bcf3 2873 char *old_msg = strbuf_detach(err, NULL);
0568c8e9 2874 strbuf_addf(err, "cannot update the ref '%s': %s",
7bd9bcf3
MH
2875 lock->ref_name, old_msg);
2876 free(old_msg);
2877 unlock_ref(lock);
2878 return -1;
2879 }
7a418f3a
MH
2880
2881 if (strcmp(lock->ref_name, "HEAD") != 0) {
7bd9bcf3
MH
2882 /*
2883 * Special hack: If a branch is updated directly and HEAD
2884 * points to it (may happen on the remote side of a push
2885 * for example) then logically the HEAD reflog should be
2886 * updated too.
2887 * A generic solution implies reverse symref information,
2888 * but finding all symrefs pointing to the given branch
2889 * would be rather costly for this rare event (the direct
2890 * update of a branch) to be worth it. So let's cheat and
2891 * check with HEAD only which should cover 99% of all usage
2892 * scenarios (even 100% of the default ones).
2893 */
2894 unsigned char head_sha1[20];
2895 int head_flag;
2896 const char *head_ref;
7a418f3a 2897
7bd9bcf3
MH
2898 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
2899 head_sha1, &head_flag);
2900 if (head_ref && (head_flag & REF_ISSYMREF) &&
2901 !strcmp(head_ref, lock->ref_name)) {
2902 struct strbuf log_err = STRBUF_INIT;
2903 if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
2904 logmsg, 0, &log_err)) {
2905 error("%s", log_err.buf);
2906 strbuf_release(&log_err);
2907 }
2908 }
2909 }
7a418f3a 2910
5d9b2de4 2911 if (commit_ref(lock)) {
0568c8e9 2912 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
7bd9bcf3
MH
2913 unlock_ref(lock);
2914 return -1;
2915 }
2916
2917 unlock_ref(lock);
2918 return 0;
2919}
2920
370e5ad6 2921static int create_ref_symlink(struct ref_lock *lock, const char *target)
7bd9bcf3 2922{
370e5ad6 2923 int ret = -1;
7bd9bcf3 2924#ifndef NO_SYMLINK_HEAD
370e5ad6
JK
2925 char *ref_path = get_locked_file_path(lock->lk);
2926 unlink(ref_path);
2927 ret = symlink(target, ref_path);
2928 free(ref_path);
2929
2930 if (ret)
7bd9bcf3 2931 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
7bd9bcf3 2932#endif
370e5ad6
JK
2933 return ret;
2934}
7bd9bcf3 2935
370e5ad6
JK
2936static void update_symref_reflog(struct ref_lock *lock, const char *refname,
2937 const char *target, const char *logmsg)
2938{
2939 struct strbuf err = STRBUF_INIT;
2940 unsigned char new_sha1[20];
b9badadd 2941 if (logmsg && !read_ref(target, new_sha1) &&
370e5ad6 2942 log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
7bd9bcf3
MH
2943 error("%s", err.buf);
2944 strbuf_release(&err);
2945 }
370e5ad6 2946}
7bd9bcf3 2947
370e5ad6
JK
2948static int create_symref_locked(struct ref_lock *lock, const char *refname,
2949 const char *target, const char *logmsg)
2950{
2951 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
2952 update_symref_reflog(lock, refname, target, logmsg);
2953 return 0;
2954 }
2955
2956 if (!fdopen_lock_file(lock->lk, "w"))
2957 return error("unable to fdopen %s: %s",
2958 lock->lk->tempfile.filename.buf, strerror(errno));
2959
396da8f7
JK
2960 update_symref_reflog(lock, refname, target, logmsg);
2961
370e5ad6
JK
2962 /* no error check; commit_ref will check ferror */
2963 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
2964 if (commit_ref(lock) < 0)
2965 return error("unable to write symref for %s: %s", refname,
2966 strerror(errno));
7bd9bcf3
MH
2967 return 0;
2968}
2969
370e5ad6
JK
2970int create_symref(const char *refname, const char *target, const char *logmsg)
2971{
2972 struct strbuf err = STRBUF_INIT;
2973 struct ref_lock *lock;
2974 int ret;
2975
2976 lock = lock_ref_sha1_basic(refname, NULL, NULL, NULL, REF_NODEREF, NULL,
2977 &err);
2978 if (!lock) {
2979 error("%s", err.buf);
2980 strbuf_release(&err);
2981 return -1;
2982 }
2983
2984 ret = create_symref_locked(lock, refname, target, logmsg);
2985 unlock_ref(lock);
2986 return ret;
2987}
2988
2233066e
KY
2989int set_worktree_head_symref(const char *gitdir, const char *target)
2990{
2991 static struct lock_file head_lock;
2992 struct ref_lock *lock;
2233066e
KY
2993 struct strbuf head_path = STRBUF_INIT;
2994 const char *head_rel;
2995 int ret;
2996
2997 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
2998 if (hold_lock_file_for_update(&head_lock, head_path.buf,
2999 LOCK_NO_DEREF) < 0) {
18eb3a9c
KY
3000 struct strbuf err = STRBUF_INIT;
3001 unable_to_lock_message(head_path.buf, errno, &err);
2233066e
KY
3002 error("%s", err.buf);
3003 strbuf_release(&err);
3004 strbuf_release(&head_path);
3005 return -1;
3006 }
3007
3008 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3009 linked trees */
3010 head_rel = remove_leading_path(head_path.buf,
3011 absolute_path(get_git_common_dir()));
3012 /* to make use of create_symref_locked(), initialize ref_lock */
3013 lock = xcalloc(1, sizeof(struct ref_lock));
3014 lock->lk = &head_lock;
3015 lock->ref_name = xstrdup(head_rel);
2233066e
KY
3016
3017 ret = create_symref_locked(lock, head_rel, target, NULL);
3018
3019 unlock_ref(lock); /* will free lock */
3020 strbuf_release(&head_path);
3021 return ret;
3022}
3023
7bd9bcf3
MH
3024int reflog_exists(const char *refname)
3025{
3026 struct stat st;
3027
3028 return !lstat(git_path("logs/%s", refname), &st) &&
3029 S_ISREG(st.st_mode);
3030}
3031
3032int delete_reflog(const char *refname)
3033{
3034 return remove_path(git_path("logs/%s", refname));
3035}
3036
3037static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3038{
3039 unsigned char osha1[20], nsha1[20];
3040 char *email_end, *message;
3041 unsigned long timestamp;
3042 int tz;
3043
3044 /* old SP new SP name <email> SP time TAB msg LF */
3045 if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3046 get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3047 get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3048 !(email_end = strchr(sb->buf + 82, '>')) ||
3049 email_end[1] != ' ' ||
3050 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3051 !message || message[0] != ' ' ||
3052 (message[1] != '+' && message[1] != '-') ||
3053 !isdigit(message[2]) || !isdigit(message[3]) ||
3054 !isdigit(message[4]) || !isdigit(message[5]))
3055 return 0; /* corrupt? */
3056 email_end[1] = '\0';
3057 tz = strtol(message + 1, NULL, 10);
3058 if (message[6] != '\t')
3059 message += 6;
3060 else
3061 message += 7;
3062 return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3063}
3064
3065static char *find_beginning_of_line(char *bob, char *scan)
3066{
3067 while (bob < scan && *(--scan) != '\n')
3068 ; /* keep scanning backwards */
3069 /*
3070 * Return either beginning of the buffer, or LF at the end of
3071 * the previous line.
3072 */
3073 return scan;
3074}
3075
3076int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3077{
3078 struct strbuf sb = STRBUF_INIT;
3079 FILE *logfp;
3080 long pos;
3081 int ret = 0, at_tail = 1;
3082
3083 logfp = fopen(git_path("logs/%s", refname), "r");
3084 if (!logfp)
3085 return -1;
3086
3087 /* Jump to the end */
3088 if (fseek(logfp, 0, SEEK_END) < 0)
3089 return error("cannot seek back reflog for %s: %s",
3090 refname, strerror(errno));
3091 pos = ftell(logfp);
3092 while (!ret && 0 < pos) {
3093 int cnt;
3094 size_t nread;
3095 char buf[BUFSIZ];
3096 char *endp, *scanp;
3097
3098 /* Fill next block from the end */
3099 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3100 if (fseek(logfp, pos - cnt, SEEK_SET))
3101 return error("cannot seek back reflog for %s: %s",
3102 refname, strerror(errno));
3103 nread = fread(buf, cnt, 1, logfp);
3104 if (nread != 1)
3105 return error("cannot read %d bytes from reflog for %s: %s",
3106 cnt, refname, strerror(errno));
3107 pos -= cnt;
3108
3109 scanp = endp = buf + cnt;
3110 if (at_tail && scanp[-1] == '\n')
3111 /* Looking at the final LF at the end of the file */
3112 scanp--;
3113 at_tail = 0;
3114
3115 while (buf < scanp) {
3116 /*
3117 * terminating LF of the previous line, or the beginning
3118 * of the buffer.
3119 */
3120 char *bp;
3121
3122 bp = find_beginning_of_line(buf, scanp);
3123
3124 if (*bp == '\n') {
3125 /*
3126 * The newline is the end of the previous line,
3127 * so we know we have complete line starting
3128 * at (bp + 1). Prefix it onto any prior data
3129 * we collected for the line and process it.
3130 */
3131 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3132 scanp = bp;
3133 endp = bp + 1;
3134 ret = show_one_reflog_ent(&sb, fn, cb_data);
3135 strbuf_reset(&sb);
3136 if (ret)
3137 break;
3138 } else if (!pos) {
3139 /*
3140 * We are at the start of the buffer, and the
3141 * start of the file; there is no previous
3142 * line, and we have everything for this one.
3143 * Process it, and we can end the loop.
3144 */
3145 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3146 ret = show_one_reflog_ent(&sb, fn, cb_data);
3147 strbuf_reset(&sb);
3148 break;
3149 }
3150
3151 if (bp == buf) {
3152 /*
3153 * We are at the start of the buffer, and there
3154 * is more file to read backwards. Which means
3155 * we are in the middle of a line. Note that we
3156 * may get here even if *bp was a newline; that
3157 * just means we are at the exact end of the
3158 * previous line, rather than some spot in the
3159 * middle.
3160 *
3161 * Save away what we have to be combined with
3162 * the data from the next read.
3163 */
3164 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3165 break;
3166 }
3167 }
3168
3169 }
3170 if (!ret && sb.len)
3171 die("BUG: reverse reflog parser had leftover data");
3172
3173 fclose(logfp);
3174 strbuf_release(&sb);
3175 return ret;
3176}
3177
3178int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3179{
3180 FILE *logfp;
3181 struct strbuf sb = STRBUF_INIT;
3182 int ret = 0;
3183
3184 logfp = fopen(git_path("logs/%s", refname), "r");
3185 if (!logfp)
3186 return -1;
3187
3188 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3189 ret = show_one_reflog_ent(&sb, fn, cb_data);
3190 fclose(logfp);
3191 strbuf_release(&sb);
3192 return ret;
3193}
3194/*
3195 * Call fn for each reflog in the namespace indicated by name. name
3196 * must be empty or end with '/'. Name will be used as a scratch
3197 * space, but its contents will be restored before return.
3198 */
3199static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3200{
3201 DIR *d = opendir(git_path("logs/%s", name->buf));
3202 int retval = 0;
3203 struct dirent *de;
3204 int oldlen = name->len;
3205
3206 if (!d)
3207 return name->len ? errno : 0;
3208
3209 while ((de = readdir(d)) != NULL) {
3210 struct stat st;
3211
3212 if (de->d_name[0] == '.')
3213 continue;
3214 if (ends_with(de->d_name, ".lock"))
3215 continue;
3216 strbuf_addstr(name, de->d_name);
3217 if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3218 ; /* silently ignore */
3219 } else {
3220 if (S_ISDIR(st.st_mode)) {
3221 strbuf_addch(name, '/');
3222 retval = do_for_each_reflog(name, fn, cb_data);
3223 } else {
3224 struct object_id oid;
3225
3226 if (read_ref_full(name->buf, 0, oid.hash, NULL))
3227 retval = error("bad ref for %s", name->buf);
3228 else
3229 retval = fn(name->buf, &oid, 0, cb_data);
3230 }
3231 if (retval)
3232 break;
3233 }
3234 strbuf_setlen(name, oldlen);
3235 }
3236 closedir(d);
3237 return retval;
3238}
3239
3240int for_each_reflog(each_ref_fn fn, void *cb_data)
3241{
3242 int retval;
3243 struct strbuf name;
3244 strbuf_init(&name, PATH_MAX);
3245 retval = do_for_each_reflog(&name, fn, cb_data);
3246 strbuf_release(&name);
3247 return retval;
3248}
3249
3250static int ref_update_reject_duplicates(struct string_list *refnames,
3251 struct strbuf *err)
3252{
3253 int i, n = refnames->nr;
3254
3255 assert(err);
3256
3257 for (i = 1; i < n; i++)
3258 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3259 strbuf_addf(err,
0568c8e9 3260 "multiple updates for ref '%s' not allowed.",
7bd9bcf3
MH
3261 refnames->items[i].string);
3262 return 1;
3263 }
3264 return 0;
3265}
3266
165056b2 3267/*
92b1551b
MH
3268 * If update is a direct update of head_ref (the reference pointed to
3269 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3270 */
3271static int split_head_update(struct ref_update *update,
3272 struct ref_transaction *transaction,
3273 const char *head_ref,
3274 struct string_list *affected_refnames,
3275 struct strbuf *err)
3276{
3277 struct string_list_item *item;
3278 struct ref_update *new_update;
3279
3280 if ((update->flags & REF_LOG_ONLY) ||
3281 (update->flags & REF_ISPRUNING) ||
3282 (update->flags & REF_UPDATE_VIA_HEAD))
3283 return 0;
3284
3285 if (strcmp(update->refname, head_ref))
3286 return 0;
3287
3288 /*
3289 * First make sure that HEAD is not already in the
3290 * transaction. This insertion is O(N) in the transaction
3291 * size, but it happens at most once per transaction.
3292 */
3293 item = string_list_insert(affected_refnames, "HEAD");
3294 if (item->util) {
3295 /* An entry already existed */
3296 strbuf_addf(err,
3297 "multiple updates for 'HEAD' (including one "
3298 "via its referent '%s') are not allowed",
3299 update->refname);
3300 return TRANSACTION_NAME_CONFLICT;
3301 }
3302
3303 new_update = ref_transaction_add_update(
3304 transaction, "HEAD",
3305 update->flags | REF_LOG_ONLY | REF_NODEREF,
3306 update->new_sha1, update->old_sha1,
3307 update->msg);
3308
3309 item->util = new_update;
3310
3311 return 0;
3312}
3313
3314/*
3315 * update is for a symref that points at referent and doesn't have
3316 * REF_NODEREF set. Split it into two updates:
3317 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3318 * - A new, separate update for the referent reference
3319 * Note that the new update will itself be subject to splitting when
3320 * the iteration gets to it.
3321 */
3322static int split_symref_update(struct ref_update *update,
3323 const char *referent,
3324 struct ref_transaction *transaction,
3325 struct string_list *affected_refnames,
3326 struct strbuf *err)
3327{
3328 struct string_list_item *item;
3329 struct ref_update *new_update;
3330 unsigned int new_flags;
3331
3332 /*
3333 * First make sure that referent is not already in the
3334 * transaction. This insertion is O(N) in the transaction
3335 * size, but it happens at most once per symref in a
3336 * transaction.
3337 */
3338 item = string_list_insert(affected_refnames, referent);
3339 if (item->util) {
3340 /* An entry already existed */
3341 strbuf_addf(err,
3342 "multiple updates for '%s' (including one "
3343 "via symref '%s') are not allowed",
3344 referent, update->refname);
3345 return TRANSACTION_NAME_CONFLICT;
3346 }
3347
3348 new_flags = update->flags;
3349 if (!strcmp(update->refname, "HEAD")) {
3350 /*
3351 * Record that the new update came via HEAD, so that
3352 * when we process it, split_head_update() doesn't try
3353 * to add another reflog update for HEAD. Note that
3354 * this bit will be propagated if the new_update
3355 * itself needs to be split.
3356 */
3357 new_flags |= REF_UPDATE_VIA_HEAD;
3358 }
3359
3360 new_update = ref_transaction_add_update(
3361 transaction, referent, new_flags,
3362 update->new_sha1, update->old_sha1,
3363 update->msg);
3364
6e30b2f6
MH
3365 new_update->parent_update = update;
3366
3367 /*
3368 * Change the symbolic ref update to log only. Also, it
3369 * doesn't need to check its old SHA-1 value, as that will be
3370 * done when new_update is processed.
3371 */
92b1551b 3372 update->flags |= REF_LOG_ONLY | REF_NODEREF;
6e30b2f6 3373 update->flags &= ~REF_HAVE_OLD;
92b1551b
MH
3374
3375 item->util = new_update;
3376
3377 return 0;
3378}
3379
6e30b2f6
MH
3380/*
3381 * Return the refname under which update was originally requested.
3382 */
3383static const char *original_update_refname(struct ref_update *update)
3384{
3385 while (update->parent_update)
3386 update = update->parent_update;
3387
3388 return update->refname;
3389}
3390
92b1551b
MH
3391/*
3392 * Prepare for carrying out update:
3393 * - Lock the reference referred to by update.
3394 * - Read the reference under lock.
3395 * - Check that its old SHA-1 value (if specified) is correct, and in
3396 * any case record it in update->lock->old_oid for later use when
3397 * writing the reflog.
3398 * - If it is a symref update without REF_NODEREF, split it up into a
3399 * REF_LOG_ONLY update of the symref and add a separate update for
3400 * the referent to transaction.
3401 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3402 * update of HEAD.
165056b2
MH
3403 */
3404static int lock_ref_for_update(struct ref_update *update,
3405 struct ref_transaction *transaction,
92b1551b 3406 const char *head_ref,
165056b2
MH
3407 struct string_list *affected_refnames,
3408 struct strbuf *err)
3409{
92b1551b
MH
3410 struct strbuf referent = STRBUF_INIT;
3411 int mustexist = (update->flags & REF_HAVE_OLD) &&
3412 !is_null_sha1(update->old_sha1);
165056b2 3413 int ret;
92b1551b 3414 struct ref_lock *lock;
165056b2 3415
92b1551b 3416 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
165056b2 3417 update->flags |= REF_DELETING;
92b1551b
MH
3418
3419 if (head_ref) {
3420 ret = split_head_update(update, transaction, head_ref,
3421 affected_refnames, err);
3422 if (ret)
3423 return ret;
3424 }
3425
3426 ret = lock_raw_ref(update->refname, mustexist,
3427 affected_refnames, NULL,
3428 &update->lock, &referent,
3429 &update->type, err);
3430
3431 if (ret) {
165056b2
MH
3432 char *reason;
3433
165056b2
MH
3434 reason = strbuf_detach(err, NULL);
3435 strbuf_addf(err, "cannot lock ref '%s': %s",
3436 update->refname, reason);
3437 free(reason);
3438 return ret;
3439 }
92b1551b
MH
3440
3441 lock = update->lock;
3442
8169d0d0 3443 if (update->type & REF_ISSYMREF) {
6e30b2f6
MH
3444 if (update->flags & REF_NODEREF) {
3445 /*
3446 * We won't be reading the referent as part of
3447 * the transaction, so we have to read it here
3448 * to record and possibly check old_sha1:
3449 */
3450 if (read_ref_full(update->refname,
3451 mustexist ? RESOLVE_REF_READING : 0,
3452 lock->old_oid.hash, NULL)) {
3453 if (update->flags & REF_HAVE_OLD) {
3454 strbuf_addf(err, "cannot lock ref '%s': "
3455 "can't resolve old value",
3456 update->refname);
3457 return TRANSACTION_GENERIC_ERROR;
3458 } else {
3459 hashclr(lock->old_oid.hash);
3460 }
3461 }
3462 if ((update->flags & REF_HAVE_OLD) &&
3463 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3464 strbuf_addf(err, "cannot lock ref '%s': "
3465 "is at %s but expected %s",
3466 update->refname,
3467 sha1_to_hex(lock->old_oid.hash),
3468 sha1_to_hex(update->old_sha1));
8169d0d0 3469 return TRANSACTION_GENERIC_ERROR;
8169d0d0 3470 }
92b1551b 3471
6e30b2f6
MH
3472 } else {
3473 /*
3474 * Create a new update for the reference this
3475 * symref is pointing at. Also, we will record
3476 * and verify old_sha1 for this update as part
3477 * of processing the split-off update, so we
3478 * don't have to do it here.
3479 */
92b1551b
MH
3480 ret = split_symref_update(update, referent.buf, transaction,
3481 affected_refnames, err);
3482 if (ret)
3483 return ret;
3484 }
6e30b2f6
MH
3485 } else {
3486 struct ref_update *parent_update;
8169d0d0 3487
6e30b2f6
MH
3488 /*
3489 * If this update is happening indirectly because of a
3490 * symref update, record the old SHA-1 in the parent
3491 * update:
3492 */
3493 for (parent_update = update->parent_update;
3494 parent_update;
3495 parent_update = parent_update->parent_update) {
3496 oidcpy(&parent_update->lock->old_oid, &lock->old_oid);
3497 }
3498
3499 if ((update->flags & REF_HAVE_OLD) &&
3500 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3501 if (is_null_sha1(update->old_sha1))
3502 strbuf_addf(err, "cannot lock ref '%s': reference already exists",
3503 original_update_refname(update));
3504 else
3505 strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
3506 original_update_refname(update),
3507 sha1_to_hex(lock->old_oid.hash),
3508 sha1_to_hex(update->old_sha1));
3509
3510 return TRANSACTION_GENERIC_ERROR;
3511 }
92b1551b
MH
3512 }
3513
165056b2
MH
3514 if ((update->flags & REF_HAVE_NEW) &&
3515 !(update->flags & REF_DELETING) &&
3516 !(update->flags & REF_LOG_ONLY)) {
92b1551b
MH
3517 if (!(update->type & REF_ISSYMREF) &&
3518 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
165056b2
MH
3519 /*
3520 * The reference already has the desired
3521 * value, so we don't need to write it.
3522 */
92b1551b 3523 } else if (write_ref_to_lockfile(lock, update->new_sha1,
165056b2
MH
3524 err)) {
3525 char *write_err = strbuf_detach(err, NULL);
3526
3527 /*
3528 * The lock was freed upon failure of
3529 * write_ref_to_lockfile():
3530 */
3531 update->lock = NULL;
3532 strbuf_addf(err,
3533 "cannot update the ref '%s': %s",
3534 update->refname, write_err);
3535 free(write_err);
3536 return TRANSACTION_GENERIC_ERROR;
3537 } else {
3538 update->flags |= REF_NEEDS_COMMIT;
3539 }
3540 }
3541 if (!(update->flags & REF_NEEDS_COMMIT)) {
3542 /*
3543 * We didn't call write_ref_to_lockfile(), so
3544 * the lockfile is still open. Close it to
3545 * free up the file descriptor:
3546 */
92b1551b 3547 if (close_ref(lock)) {
165056b2
MH
3548 strbuf_addf(err, "couldn't close '%s.lock'",
3549 update->refname);
3550 return TRANSACTION_GENERIC_ERROR;
3551 }
3552 }
3553 return 0;
3554}
3555
7bd9bcf3
MH
3556int ref_transaction_commit(struct ref_transaction *transaction,
3557 struct strbuf *err)
3558{
3559 int ret = 0, i;
7bd9bcf3
MH
3560 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3561 struct string_list_item *ref_to_delete;
3562 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
92b1551b
MH
3563 char *head_ref = NULL;
3564 int head_type;
3565 struct object_id head_oid;
7bd9bcf3
MH
3566
3567 assert(err);
3568
3569 if (transaction->state != REF_TRANSACTION_OPEN)
3570 die("BUG: commit called for transaction that is not open");
3571
efe47281 3572 if (!transaction->nr) {
7bd9bcf3
MH
3573 transaction->state = REF_TRANSACTION_CLOSED;
3574 return 0;
3575 }
3576
92b1551b
MH
3577 /*
3578 * Fail if a refname appears more than once in the
3579 * transaction. (If we end up splitting up any updates using
3580 * split_symref_update() or split_head_update(), those
3581 * functions will check that the new updates don't have the
3582 * same refname as any existing ones.)
3583 */
3584 for (i = 0; i < transaction->nr; i++) {
3585 struct ref_update *update = transaction->updates[i];
3586 struct string_list_item *item =
3587 string_list_append(&affected_refnames, update->refname);
3588
3589 /*
3590 * We store a pointer to update in item->util, but at
3591 * the moment we never use the value of this field
3592 * except to check whether it is non-NULL.
3593 */
3594 item->util = update;
3595 }
7bd9bcf3
MH
3596 string_list_sort(&affected_refnames);
3597 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3598 ret = TRANSACTION_GENERIC_ERROR;
3599 goto cleanup;
3600 }
3601
92b1551b
MH
3602 /*
3603 * Special hack: If a branch is updated directly and HEAD
3604 * points to it (may happen on the remote side of a push
3605 * for example) then logically the HEAD reflog should be
3606 * updated too.
3607 *
3608 * A generic solution would require reverse symref lookups,
3609 * but finding all symrefs pointing to a given branch would be
3610 * rather costly for this rare event (the direct update of a
3611 * branch) to be worth it. So let's cheat and check with HEAD
3612 * only, which should cover 99% of all usage scenarios (even
3613 * 100% of the default ones).
3614 *
3615 * So if HEAD is a symbolic reference, then record the name of
3616 * the reference that it points to. If we see an update of
3617 * head_ref within the transaction, then split_head_update()
3618 * arranges for the reflog of HEAD to be updated, too.
3619 */
3620 head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
3621 head_oid.hash, &head_type);
3622
3623 if (head_ref && !(head_type & REF_ISSYMREF)) {
3624 free(head_ref);
3625 head_ref = NULL;
3626 }
3627
7bd9bcf3
MH
3628 /*
3629 * Acquire all locks, verify old values if provided, check
3630 * that new values are valid, and write new values to the
3631 * lockfiles, ready to be activated. Only keep one lockfile
3632 * open at a time to avoid running out of file descriptors.
3633 */
efe47281
MH
3634 for (i = 0; i < transaction->nr; i++) {
3635 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3636
92b1551b 3637 ret = lock_ref_for_update(update, transaction, head_ref,
165056b2
MH
3638 &affected_refnames, err);
3639 if (ret)
7bd9bcf3 3640 goto cleanup;
7bd9bcf3
MH
3641 }
3642
3643 /* Perform updates first so live commits remain referenced */
efe47281
MH
3644 for (i = 0; i < transaction->nr; i++) {
3645 struct ref_update *update = transaction->updates[i];
92b1551b 3646 struct ref_lock *lock = update->lock;
7bd9bcf3 3647
d99aa884
DT
3648 if (update->flags & REF_NEEDS_COMMIT ||
3649 update->flags & REF_LOG_ONLY) {
92b1551b
MH
3650 if (log_ref_write(lock->ref_name, lock->old_oid.hash,
3651 update->new_sha1,
3652 update->msg, update->flags, err)) {
3653 char *old_msg = strbuf_detach(err, NULL);
3654
3655 strbuf_addf(err, "cannot update the ref '%s': %s",
3656 lock->ref_name, old_msg);
3657 free(old_msg);
3658 unlock_ref(lock);
7bd9bcf3
MH
3659 update->lock = NULL;
3660 ret = TRANSACTION_GENERIC_ERROR;
3661 goto cleanup;
92b1551b
MH
3662 }
3663 }
3664 if (update->flags & REF_NEEDS_COMMIT) {
3665 clear_loose_ref_cache(&ref_cache);
3666 if (commit_ref(lock)) {
3667 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3668 unlock_ref(lock);
7bd9bcf3 3669 update->lock = NULL;
92b1551b
MH
3670 ret = TRANSACTION_GENERIC_ERROR;
3671 goto cleanup;
7bd9bcf3
MH
3672 }
3673 }
3674 }
7bd9bcf3 3675 /* Perform deletes now that updates are safely completed */
efe47281
MH
3676 for (i = 0; i < transaction->nr; i++) {
3677 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3678
d99aa884
DT
3679 if (update->flags & REF_DELETING &&
3680 !(update->flags & REF_LOG_ONLY)) {
7bd9bcf3
MH
3681 if (delete_ref_loose(update->lock, update->type, err)) {
3682 ret = TRANSACTION_GENERIC_ERROR;
3683 goto cleanup;
3684 }
3685
3686 if (!(update->flags & REF_ISPRUNING))
3687 string_list_append(&refs_to_delete,
3688 update->lock->ref_name);
3689 }
3690 }
3691
3692 if (repack_without_refs(&refs_to_delete, err)) {
3693 ret = TRANSACTION_GENERIC_ERROR;
3694 goto cleanup;
3695 }
3696 for_each_string_list_item(ref_to_delete, &refs_to_delete)
3697 unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
3698 clear_loose_ref_cache(&ref_cache);
3699
3700cleanup:
3701 transaction->state = REF_TRANSACTION_CLOSED;
3702
efe47281
MH
3703 for (i = 0; i < transaction->nr; i++)
3704 if (transaction->updates[i]->lock)
3705 unlock_ref(transaction->updates[i]->lock);
7bd9bcf3 3706 string_list_clear(&refs_to_delete, 0);
92b1551b 3707 free(head_ref);
7bd9bcf3 3708 string_list_clear(&affected_refnames, 0);
92b1551b 3709
7bd9bcf3
MH
3710 return ret;
3711}
3712
3713static int ref_present(const char *refname,
3714 const struct object_id *oid, int flags, void *cb_data)
3715{
3716 struct string_list *affected_refnames = cb_data;
3717
3718 return string_list_has_string(affected_refnames, refname);
3719}
3720
3721int initial_ref_transaction_commit(struct ref_transaction *transaction,
3722 struct strbuf *err)
3723{
3724 int ret = 0, i;
7bd9bcf3
MH
3725 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
3726
3727 assert(err);
3728
3729 if (transaction->state != REF_TRANSACTION_OPEN)
3730 die("BUG: commit called for transaction that is not open");
3731
3732 /* Fail if a refname appears more than once in the transaction: */
efe47281
MH
3733 for (i = 0; i < transaction->nr; i++)
3734 string_list_append(&affected_refnames,
3735 transaction->updates[i]->refname);
7bd9bcf3
MH
3736 string_list_sort(&affected_refnames);
3737 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3738 ret = TRANSACTION_GENERIC_ERROR;
3739 goto cleanup;
3740 }
3741
3742 /*
3743 * It's really undefined to call this function in an active
3744 * repository or when there are existing references: we are
3745 * only locking and changing packed-refs, so (1) any
3746 * simultaneous processes might try to change a reference at
3747 * the same time we do, and (2) any existing loose versions of
3748 * the references that we are setting would have precedence
3749 * over our values. But some remote helpers create the remote
3750 * "HEAD" and "master" branches before calling this function,
3751 * so here we really only check that none of the references
3752 * that we are creating already exists.
3753 */
3754 if (for_each_rawref(ref_present, &affected_refnames))
3755 die("BUG: initial ref transaction called with existing refs");
3756
efe47281
MH
3757 for (i = 0; i < transaction->nr; i++) {
3758 struct ref_update *update = transaction->updates[i];
7bd9bcf3
MH
3759
3760 if ((update->flags & REF_HAVE_OLD) &&
3761 !is_null_sha1(update->old_sha1))
3762 die("BUG: initial ref transaction with old_sha1 set");
3763 if (verify_refname_available(update->refname,
3764 &affected_refnames, NULL,
3765 err)) {
3766 ret = TRANSACTION_NAME_CONFLICT;
3767 goto cleanup;
3768 }
3769 }
3770
3771 if (lock_packed_refs(0)) {
3772 strbuf_addf(err, "unable to lock packed-refs file: %s",
3773 strerror(errno));
3774 ret = TRANSACTION_GENERIC_ERROR;
3775 goto cleanup;
3776 }
3777
efe47281
MH
3778 for (i = 0; i < transaction->nr; i++) {
3779 struct ref_update *update = transaction->updates[i];
7bd9bcf3
MH
3780
3781 if ((update->flags & REF_HAVE_NEW) &&
3782 !is_null_sha1(update->new_sha1))
3783 add_packed_ref(update->refname, update->new_sha1);
3784 }
3785
3786 if (commit_packed_refs()) {
3787 strbuf_addf(err, "unable to commit packed-refs file: %s",
3788 strerror(errno));
3789 ret = TRANSACTION_GENERIC_ERROR;
3790 goto cleanup;
3791 }
3792
3793cleanup:
3794 transaction->state = REF_TRANSACTION_CLOSED;
3795 string_list_clear(&affected_refnames, 0);
3796 return ret;
3797}
3798
3799struct expire_reflog_cb {
3800 unsigned int flags;
3801 reflog_expiry_should_prune_fn *should_prune_fn;
3802 void *policy_cb;
3803 FILE *newlog;
3804 unsigned char last_kept_sha1[20];
3805};
3806
3807static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
3808 const char *email, unsigned long timestamp, int tz,
3809 const char *message, void *cb_data)
3810{
3811 struct expire_reflog_cb *cb = cb_data;
3812 struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
3813
3814 if (cb->flags & EXPIRE_REFLOGS_REWRITE)
3815 osha1 = cb->last_kept_sha1;
3816
3817 if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
3818 message, policy_cb)) {
3819 if (!cb->newlog)
3820 printf("would prune %s", message);
3821 else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
3822 printf("prune %s", message);
3823 } else {
3824 if (cb->newlog) {
3825 fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
3826 sha1_to_hex(osha1), sha1_to_hex(nsha1),
3827 email, timestamp, tz, message);
3828 hashcpy(cb->last_kept_sha1, nsha1);
3829 }
3830 if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
3831 printf("keep %s", message);
3832 }
3833 return 0;
3834}
3835
3836int reflog_expire(const char *refname, const unsigned char *sha1,
3837 unsigned int flags,
3838 reflog_expiry_prepare_fn prepare_fn,
3839 reflog_expiry_should_prune_fn should_prune_fn,
3840 reflog_expiry_cleanup_fn cleanup_fn,
3841 void *policy_cb_data)
3842{
3843 static struct lock_file reflog_lock;
3844 struct expire_reflog_cb cb;
3845 struct ref_lock *lock;
3846 char *log_file;
3847 int status = 0;
3848 int type;
3849 struct strbuf err = STRBUF_INIT;
3850
3851 memset(&cb, 0, sizeof(cb));
3852 cb.flags = flags;
3853 cb.policy_cb = policy_cb_data;
3854 cb.should_prune_fn = should_prune_fn;
3855
3856 /*
3857 * The reflog file is locked by holding the lock on the
3858 * reference itself, plus we might need to update the
3859 * reference if --updateref was specified:
3860 */
41d796ed
DT
3861 lock = lock_ref_sha1_basic(refname, sha1, NULL, NULL, REF_NODEREF,
3862 &type, &err);
7bd9bcf3
MH
3863 if (!lock) {
3864 error("cannot lock ref '%s': %s", refname, err.buf);
3865 strbuf_release(&err);
3866 return -1;
3867 }
3868 if (!reflog_exists(refname)) {
3869 unlock_ref(lock);
3870 return 0;
3871 }
3872
3873 log_file = git_pathdup("logs/%s", refname);
3874 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3875 /*
3876 * Even though holding $GIT_DIR/logs/$reflog.lock has
3877 * no locking implications, we use the lock_file
3878 * machinery here anyway because it does a lot of the
3879 * work we need, including cleaning up if the program
3880 * exits unexpectedly.
3881 */
3882 if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
3883 struct strbuf err = STRBUF_INIT;
3884 unable_to_lock_message(log_file, errno, &err);
3885 error("%s", err.buf);
3886 strbuf_release(&err);
3887 goto failure;
3888 }
3889 cb.newlog = fdopen_lock_file(&reflog_lock, "w");
3890 if (!cb.newlog) {
3891 error("cannot fdopen %s (%s)",
3892 get_lock_file_path(&reflog_lock), strerror(errno));
3893 goto failure;
3894 }
3895 }
3896
3897 (*prepare_fn)(refname, sha1, cb.policy_cb);
3898 for_each_reflog_ent(refname, expire_reflog_ent, &cb);
3899 (*cleanup_fn)(cb.policy_cb);
3900
3901 if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
3902 /*
3903 * It doesn't make sense to adjust a reference pointed
3904 * to by a symbolic ref based on expiring entries in
3905 * the symbolic reference's reflog. Nor can we update
3906 * a reference if there are no remaining reflog
3907 * entries.
3908 */
3909 int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
3910 !(type & REF_ISSYMREF) &&
3911 !is_null_sha1(cb.last_kept_sha1);
3912
3913 if (close_lock_file(&reflog_lock)) {
3914 status |= error("couldn't write %s: %s", log_file,
3915 strerror(errno));
3916 } else if (update &&
3917 (write_in_full(get_lock_file_fd(lock->lk),
3918 sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
3919 write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
3920 close_ref(lock) < 0)) {
3921 status |= error("couldn't write %s",
3922 get_lock_file_path(lock->lk));
3923 rollback_lock_file(&reflog_lock);
3924 } else if (commit_lock_file(&reflog_lock)) {
e0048d3e 3925 status |= error("unable to write reflog '%s' (%s)",
7bd9bcf3
MH
3926 log_file, strerror(errno));
3927 } else if (update && commit_ref(lock)) {
3928 status |= error("couldn't set %s", lock->ref_name);
3929 }
3930 }
3931 free(log_file);
3932 unlock_ref(lock);
3933 return status;
3934
3935 failure:
3936 rollback_lock_file(&reflog_lock);
3937 free(log_file);
3938 unlock_ref(lock);
3939 return -1;
3940}