refs: introduce an iterator interface
[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"
3bc581b9 4#include "../iterator.h"
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5#include "../lockfile.h"
6#include "../object.h"
7#include "../dir.h"
8
9struct ref_lock {
10 char *ref_name;
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11 struct lock_file *lk;
12 struct object_id old_oid;
13};
14
15struct ref_entry;
16
17/*
18 * Information used (along with the information in ref_entry) to
19 * describe a single cached reference. This data structure only
20 * occurs embedded in a union in struct ref_entry, and only when
21 * (ref_entry->flag & REF_DIR) is zero.
22 */
23struct ref_value {
24 /*
25 * The name of the object to which this reference resolves
26 * (which may be a tag object). If REF_ISBROKEN, this is
27 * null. If REF_ISSYMREF, then this is the name of the object
28 * referred to by the last reference in the symlink chain.
29 */
30 struct object_id oid;
31
32 /*
33 * If REF_KNOWS_PEELED, then this field holds the peeled value
34 * of this reference, or null if the reference is known not to
35 * be peelable. See the documentation for peel_ref() for an
36 * exact definition of "peelable".
37 */
38 struct object_id peeled;
39};
40
41struct ref_cache;
42
43/*
44 * Information used (along with the information in ref_entry) to
45 * describe a level in the hierarchy of references. This data
46 * structure only occurs embedded in a union in struct ref_entry, and
47 * only when (ref_entry.flag & REF_DIR) is set. In that case,
48 * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
49 * in the directory have already been read:
50 *
51 * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
52 * or packed references, already read.
53 *
54 * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
55 * references that hasn't been read yet (nor has any of its
56 * subdirectories).
57 *
58 * Entries within a directory are stored within a growable array of
59 * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
60 * sorted are sorted by their component name in strcmp() order and the
61 * remaining entries are unsorted.
62 *
63 * Loose references are read lazily, one directory at a time. When a
64 * directory of loose references is read, then all of the references
65 * in that directory are stored, and REF_INCOMPLETE stubs are created
66 * for any subdirectories, but the subdirectories themselves are not
67 * read. The reading is triggered by get_ref_dir().
68 */
69struct ref_dir {
70 int nr, alloc;
71
72 /*
73 * Entries with index 0 <= i < sorted are sorted by name. New
74 * entries are appended to the list unsorted, and are sorted
75 * only when required; thus we avoid the need to sort the list
76 * after the addition of every reference.
77 */
78 int sorted;
79
80 /* A pointer to the ref_cache that contains this ref_dir. */
81 struct ref_cache *ref_cache;
82
83 struct ref_entry **entries;
84};
85
86/*
87 * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
88 * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
89 * public values; see refs.h.
90 */
91
92/*
93 * The field ref_entry->u.value.peeled of this value entry contains
94 * the correct peeled value for the reference, which might be
95 * null_sha1 if the reference is not a tag or if it is broken.
96 */
97#define REF_KNOWS_PEELED 0x10
98
99/* ref_entry represents a directory of references */
100#define REF_DIR 0x20
101
102/*
103 * Entry has not yet been read from disk (used only for REF_DIR
104 * entries representing loose references)
105 */
106#define REF_INCOMPLETE 0x40
107
108/*
109 * A ref_entry represents either a reference or a "subdirectory" of
110 * references.
111 *
112 * Each directory in the reference namespace is represented by a
113 * ref_entry with (flags & REF_DIR) set and containing a subdir member
114 * that holds the entries in that directory that have been read so
115 * far. If (flags & REF_INCOMPLETE) is set, then the directory and
116 * its subdirectories haven't been read yet. REF_INCOMPLETE is only
117 * used for loose reference directories.
118 *
119 * References are represented by a ref_entry with (flags & REF_DIR)
120 * unset and a value member that describes the reference's value. The
121 * flag member is at the ref_entry level, but it is also needed to
122 * interpret the contents of the value field (in other words, a
123 * ref_value object is not very much use without the enclosing
124 * ref_entry).
125 *
126 * Reference names cannot end with slash and directories' names are
127 * always stored with a trailing slash (except for the top-level
128 * directory, which is always denoted by ""). This has two nice
129 * consequences: (1) when the entries in each subdir are sorted
130 * lexicographically by name (as they usually are), the references in
131 * a whole tree can be generated in lexicographic order by traversing
132 * the tree in left-to-right, depth-first order; (2) the names of
133 * references and subdirectories cannot conflict, and therefore the
134 * presence of an empty subdirectory does not block the creation of a
135 * similarly-named reference. (The fact that reference names with the
136 * same leading components can conflict *with each other* is a
137 * separate issue that is regulated by verify_refname_available().)
138 *
139 * Please note that the name field contains the fully-qualified
140 * reference (or subdirectory) name. Space could be saved by only
141 * storing the relative names. But that would require the full names
142 * to be generated on the fly when iterating in do_for_each_ref(), and
143 * would break callback functions, who have always been able to assume
144 * that the name strings that they are passed will not be freed during
145 * the iteration.
146 */
147struct ref_entry {
148 unsigned char flag; /* ISSYMREF? ISPACKED? */
149 union {
150 struct ref_value value; /* if not (flags&REF_DIR) */
151 struct ref_dir subdir; /* if (flags&REF_DIR) */
152 } u;
153 /*
154 * The full name of the reference (e.g., "refs/heads/master")
155 * or the full name of the directory with a trailing slash
156 * (e.g., "refs/heads/"):
157 */
158 char name[FLEX_ARRAY];
159};
160
161static void read_loose_refs(const char *dirname, struct ref_dir *dir);
162static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
163static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
164 const char *dirname, size_t len,
165 int incomplete);
166static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
167
168static struct ref_dir *get_ref_dir(struct ref_entry *entry)
169{
170 struct ref_dir *dir;
171 assert(entry->flag & REF_DIR);
172 dir = &entry->u.subdir;
173 if (entry->flag & REF_INCOMPLETE) {
174 read_loose_refs(entry->name, dir);
175
176 /*
177 * Manually add refs/bisect, which, being
178 * per-worktree, might not appear in the directory
179 * listing for refs/ in the main repo.
180 */
181 if (!strcmp(entry->name, "refs/")) {
182 int pos = search_ref_dir(dir, "refs/bisect/", 12);
183 if (pos < 0) {
184 struct ref_entry *child_entry;
185 child_entry = create_dir_entry(dir->ref_cache,
186 "refs/bisect/",
187 12, 1);
188 add_entry_to_dir(dir, child_entry);
189 read_loose_refs("refs/bisect",
190 &child_entry->u.subdir);
191 }
192 }
193 entry->flag &= ~REF_INCOMPLETE;
194 }
195 return dir;
196}
197
198static struct ref_entry *create_ref_entry(const char *refname,
199 const unsigned char *sha1, int flag,
200 int check_name)
201{
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202 struct ref_entry *ref;
203
204 if (check_name &&
205 check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
206 die("Reference has invalid format: '%s'", refname);
96ffc06f 207 FLEX_ALLOC_STR(ref, name, refname);
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208 hashcpy(ref->u.value.oid.hash, sha1);
209 oidclr(&ref->u.value.peeled);
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210 ref->flag = flag;
211 return ref;
212}
213
214static void clear_ref_dir(struct ref_dir *dir);
215
216static void free_ref_entry(struct ref_entry *entry)
217{
218 if (entry->flag & REF_DIR) {
219 /*
220 * Do not use get_ref_dir() here, as that might
221 * trigger the reading of loose refs.
222 */
223 clear_ref_dir(&entry->u.subdir);
224 }
225 free(entry);
226}
227
228/*
229 * Add a ref_entry to the end of dir (unsorted). Entry is always
230 * stored directly in dir; no recursion into subdirectories is
231 * done.
232 */
233static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
234{
235 ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
236 dir->entries[dir->nr++] = entry;
237 /* optimize for the case that entries are added in order */
238 if (dir->nr == 1 ||
239 (dir->nr == dir->sorted + 1 &&
240 strcmp(dir->entries[dir->nr - 2]->name,
241 dir->entries[dir->nr - 1]->name) < 0))
242 dir->sorted = dir->nr;
243}
244
245/*
246 * Clear and free all entries in dir, recursively.
247 */
248static void clear_ref_dir(struct ref_dir *dir)
249{
250 int i;
251 for (i = 0; i < dir->nr; i++)
252 free_ref_entry(dir->entries[i]);
253 free(dir->entries);
254 dir->sorted = dir->nr = dir->alloc = 0;
255 dir->entries = NULL;
256}
257
258/*
259 * Create a struct ref_entry object for the specified dirname.
260 * dirname is the name of the directory with a trailing slash (e.g.,
261 * "refs/heads/") or "" for the top-level directory.
262 */
263static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
264 const char *dirname, size_t len,
265 int incomplete)
266{
267 struct ref_entry *direntry;
96ffc06f 268 FLEX_ALLOC_MEM(direntry, name, dirname, len);
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269 direntry->u.subdir.ref_cache = ref_cache;
270 direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
271 return direntry;
272}
273
274static int ref_entry_cmp(const void *a, const void *b)
275{
276 struct ref_entry *one = *(struct ref_entry **)a;
277 struct ref_entry *two = *(struct ref_entry **)b;
278 return strcmp(one->name, two->name);
279}
280
281static void sort_ref_dir(struct ref_dir *dir);
282
283struct string_slice {
284 size_t len;
285 const char *str;
286};
287
288static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
289{
290 const struct string_slice *key = key_;
291 const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
292 int cmp = strncmp(key->str, ent->name, key->len);
293 if (cmp)
294 return cmp;
295 return '\0' - (unsigned char)ent->name[key->len];
296}
297
298/*
299 * Return the index of the entry with the given refname from the
300 * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
301 * no such entry is found. dir must already be complete.
302 */
303static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
304{
305 struct ref_entry **r;
306 struct string_slice key;
307
308 if (refname == NULL || !dir->nr)
309 return -1;
310
311 sort_ref_dir(dir);
312 key.len = len;
313 key.str = refname;
314 r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
315 ref_entry_cmp_sslice);
316
317 if (r == NULL)
318 return -1;
319
320 return r - dir->entries;
321}
322
323/*
324 * Search for a directory entry directly within dir (without
325 * recursing). Sort dir if necessary. subdirname must be a directory
326 * name (i.e., end in '/'). If mkdir is set, then create the
327 * directory if it is missing; otherwise, return NULL if the desired
328 * directory cannot be found. dir must already be complete.
329 */
330static struct ref_dir *search_for_subdir(struct ref_dir *dir,
331 const char *subdirname, size_t len,
332 int mkdir)
333{
334 int entry_index = search_ref_dir(dir, subdirname, len);
335 struct ref_entry *entry;
336 if (entry_index == -1) {
337 if (!mkdir)
338 return NULL;
339 /*
340 * Since dir is complete, the absence of a subdir
341 * means that the subdir really doesn't exist;
342 * therefore, create an empty record for it but mark
343 * the record complete.
344 */
345 entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
346 add_entry_to_dir(dir, entry);
347 } else {
348 entry = dir->entries[entry_index];
349 }
350 return get_ref_dir(entry);
351}
352
353/*
354 * If refname is a reference name, find the ref_dir within the dir
355 * tree that should hold refname. If refname is a directory name
356 * (i.e., ends in '/'), then return that ref_dir itself. dir must
357 * represent the top-level directory and must already be complete.
358 * Sort ref_dirs and recurse into subdirectories as necessary. If
359 * mkdir is set, then create any missing directories; otherwise,
360 * return NULL if the desired directory cannot be found.
361 */
362static struct ref_dir *find_containing_dir(struct ref_dir *dir,
363 const char *refname, int mkdir)
364{
365 const char *slash;
366 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
367 size_t dirnamelen = slash - refname + 1;
368 struct ref_dir *subdir;
369 subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
370 if (!subdir) {
371 dir = NULL;
372 break;
373 }
374 dir = subdir;
375 }
376
377 return dir;
378}
379
380/*
381 * Find the value entry with the given name in dir, sorting ref_dirs
382 * and recursing into subdirectories as necessary. If the name is not
383 * found or it corresponds to a directory entry, return NULL.
384 */
385static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
386{
387 int entry_index;
388 struct ref_entry *entry;
389 dir = find_containing_dir(dir, refname, 0);
390 if (!dir)
391 return NULL;
392 entry_index = search_ref_dir(dir, refname, strlen(refname));
393 if (entry_index == -1)
394 return NULL;
395 entry = dir->entries[entry_index];
396 return (entry->flag & REF_DIR) ? NULL : entry;
397}
398
399/*
400 * Remove the entry with the given name from dir, recursing into
401 * subdirectories as necessary. If refname is the name of a directory
402 * (i.e., ends with '/'), then remove the directory and its contents.
403 * If the removal was successful, return the number of entries
404 * remaining in the directory entry that contained the deleted entry.
405 * If the name was not found, return -1. Please note that this
406 * function only deletes the entry from the cache; it does not delete
407 * it from the filesystem or ensure that other cache entries (which
408 * might be symbolic references to the removed entry) are updated.
409 * Nor does it remove any containing dir entries that might be made
410 * empty by the removal. dir must represent the top-level directory
411 * and must already be complete.
412 */
413static int remove_entry(struct ref_dir *dir, const char *refname)
414{
415 int refname_len = strlen(refname);
416 int entry_index;
417 struct ref_entry *entry;
418 int is_dir = refname[refname_len - 1] == '/';
419 if (is_dir) {
420 /*
421 * refname represents a reference directory. Remove
422 * the trailing slash; otherwise we will get the
423 * directory *representing* refname rather than the
424 * one *containing* it.
425 */
426 char *dirname = xmemdupz(refname, refname_len - 1);
427 dir = find_containing_dir(dir, dirname, 0);
428 free(dirname);
429 } else {
430 dir = find_containing_dir(dir, refname, 0);
431 }
432 if (!dir)
433 return -1;
434 entry_index = search_ref_dir(dir, refname, refname_len);
435 if (entry_index == -1)
436 return -1;
437 entry = dir->entries[entry_index];
438
439 memmove(&dir->entries[entry_index],
440 &dir->entries[entry_index + 1],
441 (dir->nr - entry_index - 1) * sizeof(*dir->entries)
442 );
443 dir->nr--;
444 if (dir->sorted > entry_index)
445 dir->sorted--;
446 free_ref_entry(entry);
447 return dir->nr;
448}
449
450/*
451 * Add a ref_entry to the ref_dir (unsorted), recursing into
452 * subdirectories as necessary. dir must represent the top-level
453 * directory. Return 0 on success.
454 */
455static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
456{
457 dir = find_containing_dir(dir, ref->name, 1);
458 if (!dir)
459 return -1;
460 add_entry_to_dir(dir, ref);
461 return 0;
462}
463
464/*
465 * Emit a warning and return true iff ref1 and ref2 have the same name
466 * and the same sha1. Die if they have the same name but different
467 * sha1s.
468 */
469static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
470{
471 if (strcmp(ref1->name, ref2->name))
472 return 0;
473
474 /* Duplicate name; make sure that they don't conflict: */
475
476 if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
477 /* This is impossible by construction */
478 die("Reference directory conflict: %s", ref1->name);
479
480 if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
481 die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
482
483 warning("Duplicated ref: %s", ref1->name);
484 return 1;
485}
486
487/*
488 * Sort the entries in dir non-recursively (if they are not already
489 * sorted) and remove any duplicate entries.
490 */
491static void sort_ref_dir(struct ref_dir *dir)
492{
493 int i, j;
494 struct ref_entry *last = NULL;
495
496 /*
497 * This check also prevents passing a zero-length array to qsort(),
498 * which is a problem on some platforms.
499 */
500 if (dir->sorted == dir->nr)
501 return;
502
503 qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
504
505 /* Remove any duplicates: */
506 for (i = 0, j = 0; j < dir->nr; j++) {
507 struct ref_entry *entry = dir->entries[j];
508 if (last && is_dup_ref(last, entry))
509 free_ref_entry(entry);
510 else
511 last = dir->entries[i++] = entry;
512 }
513 dir->sorted = dir->nr = i;
514}
515
7bd9bcf3 516/*
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517 * Return true if refname, which has the specified oid and flags, can
518 * be resolved to an object in the database. If the referred-to object
519 * does not exist, emit a warning and return false.
7bd9bcf3 520 */
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521static int ref_resolves_to_object(const char *refname,
522 const struct object_id *oid,
523 unsigned int flags)
7bd9bcf3 524{
a8739244 525 if (flags & REF_ISBROKEN)
7bd9bcf3 526 return 0;
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527 if (!has_sha1_file(oid->hash)) {
528 error("%s does not point to a valid object!", refname);
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529 return 0;
530 }
531 return 1;
532}
533
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534/*
535 * Return true if the reference described by entry can be resolved to
536 * an object in the database; otherwise, emit a warning and return
537 * false.
538 */
539static int entry_resolves_to_object(struct ref_entry *entry)
540{
541 return ref_resolves_to_object(entry->name,
542 &entry->u.value.oid, entry->flag);
543}
544
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545/*
546 * current_ref is a performance hack: when iterating over references
547 * using the for_each_ref*() functions, current_ref is set to the
548 * current reference's entry before calling the callback function. If
549 * the callback function calls peel_ref(), then peel_ref() first
550 * checks whether the reference to be peeled is the current reference
551 * (it usually is) and if so, returns that reference's peeled version
552 * if it is available. This avoids a refname lookup in a common case.
553 */
554static struct ref_entry *current_ref;
555
556typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
557
558struct ref_entry_cb {
4633a846 559 const char *prefix;
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560 int trim;
561 int flags;
562 each_ref_fn *fn;
563 void *cb_data;
564};
565
566/*
567 * Handle one reference in a do_for_each_ref*()-style iteration,
568 * calling an each_ref_fn for each entry.
569 */
570static int do_one_ref(struct ref_entry *entry, void *cb_data)
571{
572 struct ref_entry_cb *data = cb_data;
573 struct ref_entry *old_current_ref;
574 int retval;
575
4633a846 576 if (!starts_with(entry->name, data->prefix))
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577 return 0;
578
579 if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
ffeef642 580 !entry_resolves_to_object(entry))
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581 return 0;
582
583 /* Store the old value, in case this is a recursive call: */
584 old_current_ref = current_ref;
585 current_ref = entry;
586 retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
587 entry->flag, data->cb_data);
588 current_ref = old_current_ref;
589 return retval;
590}
591
592/*
593 * Call fn for each reference in dir that has index in the range
594 * offset <= index < dir->nr. Recurse into subdirectories that are in
595 * that index range, sorting them before iterating. This function
596 * does not sort dir itself; it should be sorted beforehand. fn is
597 * called for all references, including broken ones.
598 */
599static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
600 each_ref_entry_fn fn, void *cb_data)
601{
602 int i;
603 assert(dir->sorted == dir->nr);
604 for (i = offset; i < dir->nr; i++) {
605 struct ref_entry *entry = dir->entries[i];
606 int retval;
607 if (entry->flag & REF_DIR) {
608 struct ref_dir *subdir = get_ref_dir(entry);
609 sort_ref_dir(subdir);
610 retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
611 } else {
612 retval = fn(entry, cb_data);
613 }
614 if (retval)
615 return retval;
616 }
617 return 0;
618}
619
620/*
621 * Call fn for each reference in the union of dir1 and dir2, in order
622 * by refname. Recurse into subdirectories. If a value entry appears
623 * in both dir1 and dir2, then only process the version that is in
624 * dir2. The input dirs must already be sorted, but subdirs will be
625 * sorted as needed. fn is called for all references, including
626 * broken ones.
627 */
628static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
629 struct ref_dir *dir2,
630 each_ref_entry_fn fn, void *cb_data)
631{
632 int retval;
633 int i1 = 0, i2 = 0;
634
635 assert(dir1->sorted == dir1->nr);
636 assert(dir2->sorted == dir2->nr);
637 while (1) {
638 struct ref_entry *e1, *e2;
639 int cmp;
640 if (i1 == dir1->nr) {
641 return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
642 }
643 if (i2 == dir2->nr) {
644 return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
645 }
646 e1 = dir1->entries[i1];
647 e2 = dir2->entries[i2];
648 cmp = strcmp(e1->name, e2->name);
649 if (cmp == 0) {
650 if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
651 /* Both are directories; descend them in parallel. */
652 struct ref_dir *subdir1 = get_ref_dir(e1);
653 struct ref_dir *subdir2 = get_ref_dir(e2);
654 sort_ref_dir(subdir1);
655 sort_ref_dir(subdir2);
656 retval = do_for_each_entry_in_dirs(
657 subdir1, subdir2, fn, cb_data);
658 i1++;
659 i2++;
660 } else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
661 /* Both are references; ignore the one from dir1. */
662 retval = fn(e2, cb_data);
663 i1++;
664 i2++;
665 } else {
666 die("conflict between reference and directory: %s",
667 e1->name);
668 }
669 } else {
670 struct ref_entry *e;
671 if (cmp < 0) {
672 e = e1;
673 i1++;
674 } else {
675 e = e2;
676 i2++;
677 }
678 if (e->flag & REF_DIR) {
679 struct ref_dir *subdir = get_ref_dir(e);
680 sort_ref_dir(subdir);
681 retval = do_for_each_entry_in_dir(
682 subdir, 0, fn, cb_data);
683 } else {
684 retval = fn(e, cb_data);
685 }
686 }
687 if (retval)
688 return retval;
689 }
690}
691
692/*
693 * Load all of the refs from the dir into our in-memory cache. The hard work
694 * of loading loose refs is done by get_ref_dir(), so we just need to recurse
695 * through all of the sub-directories. We do not even need to care about
696 * sorting, as traversal order does not matter to us.
697 */
698static void prime_ref_dir(struct ref_dir *dir)
699{
700 int i;
701 for (i = 0; i < dir->nr; i++) {
702 struct ref_entry *entry = dir->entries[i];
703 if (entry->flag & REF_DIR)
704 prime_ref_dir(get_ref_dir(entry));
705 }
706}
707
3bc581b9
MH
708/*
709 * A level in the reference hierarchy that is currently being iterated
710 * through.
711 */
712struct cache_ref_iterator_level {
713 /*
714 * The ref_dir being iterated over at this level. The ref_dir
715 * is sorted before being stored here.
716 */
717 struct ref_dir *dir;
718
719 /*
720 * The index of the current entry within dir (which might
721 * itself be a directory). If index == -1, then the iteration
722 * hasn't yet begun. If index == dir->nr, then the iteration
723 * through this level is over.
724 */
725 int index;
726};
727
728/*
729 * Represent an iteration through a ref_dir in the memory cache. The
730 * iteration recurses through subdirectories.
731 */
732struct cache_ref_iterator {
733 struct ref_iterator base;
734
735 /*
736 * The number of levels currently on the stack. This is always
737 * at least 1, because when it becomes zero the iteration is
738 * ended and this struct is freed.
739 */
740 size_t levels_nr;
741
742 /* The number of levels that have been allocated on the stack */
743 size_t levels_alloc;
744
745 /*
746 * A stack of levels. levels[0] is the uppermost level that is
747 * being iterated over in this iteration. (This is not
748 * necessary the top level in the references hierarchy. If we
749 * are iterating through a subtree, then levels[0] will hold
750 * the ref_dir for that subtree, and subsequent levels will go
751 * on from there.)
752 */
753 struct cache_ref_iterator_level *levels;
754};
755
756static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
757{
758 struct cache_ref_iterator *iter =
759 (struct cache_ref_iterator *)ref_iterator;
760
761 while (1) {
762 struct cache_ref_iterator_level *level =
763 &iter->levels[iter->levels_nr - 1];
764 struct ref_dir *dir = level->dir;
765 struct ref_entry *entry;
766
767 if (level->index == -1)
768 sort_ref_dir(dir);
769
770 if (++level->index == level->dir->nr) {
771 /* This level is exhausted; pop up a level */
772 if (--iter->levels_nr == 0)
773 return ref_iterator_abort(ref_iterator);
774
775 continue;
776 }
777
778 entry = dir->entries[level->index];
779
780 if (entry->flag & REF_DIR) {
781 /* push down a level */
782 ALLOC_GROW(iter->levels, iter->levels_nr + 1,
783 iter->levels_alloc);
784
785 level = &iter->levels[iter->levels_nr++];
786 level->dir = get_ref_dir(entry);
787 level->index = -1;
788 } else {
789 iter->base.refname = entry->name;
790 iter->base.oid = &entry->u.value.oid;
791 iter->base.flags = entry->flag;
792 return ITER_OK;
793 }
794 }
795}
796
797static enum peel_status peel_entry(struct ref_entry *entry, int repeel);
798
799static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
800 struct object_id *peeled)
801{
802 struct cache_ref_iterator *iter =
803 (struct cache_ref_iterator *)ref_iterator;
804 struct cache_ref_iterator_level *level;
805 struct ref_entry *entry;
806
807 level = &iter->levels[iter->levels_nr - 1];
808
809 if (level->index == -1)
810 die("BUG: peel called before advance for cache iterator");
811
812 entry = level->dir->entries[level->index];
813
814 if (peel_entry(entry, 0))
815 return -1;
816 hashcpy(peeled->hash, entry->u.value.peeled.hash);
817 return 0;
818}
819
820static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
821{
822 struct cache_ref_iterator *iter =
823 (struct cache_ref_iterator *)ref_iterator;
824
825 free(iter->levels);
826 base_ref_iterator_free(ref_iterator);
827 return ITER_DONE;
828}
829
830static struct ref_iterator_vtable cache_ref_iterator_vtable = {
831 cache_ref_iterator_advance,
832 cache_ref_iterator_peel,
833 cache_ref_iterator_abort
834};
835
836static struct ref_iterator *cache_ref_iterator_begin(struct ref_dir *dir)
837{
838 struct cache_ref_iterator *iter;
839 struct ref_iterator *ref_iterator;
840 struct cache_ref_iterator_level *level;
841
842 iter = xcalloc(1, sizeof(*iter));
843 ref_iterator = &iter->base;
844 base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
845 ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
846
847 iter->levels_nr = 1;
848 level = &iter->levels[0];
849 level->index = -1;
850 level->dir = dir;
851
852 return ref_iterator;
853}
854
7bd9bcf3
MH
855struct nonmatching_ref_data {
856 const struct string_list *skip;
857 const char *conflicting_refname;
858};
859
860static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
861{
862 struct nonmatching_ref_data *data = vdata;
863
864 if (data->skip && string_list_has_string(data->skip, entry->name))
865 return 0;
866
867 data->conflicting_refname = entry->name;
868 return 1;
869}
870
871/*
872 * Return 0 if a reference named refname could be created without
873 * conflicting with the name of an existing reference in dir.
874 * See verify_refname_available for more information.
875 */
876static int verify_refname_available_dir(const char *refname,
877 const struct string_list *extras,
878 const struct string_list *skip,
879 struct ref_dir *dir,
880 struct strbuf *err)
881{
882 const char *slash;
0845122c 883 const char *extra_refname;
7bd9bcf3
MH
884 int pos;
885 struct strbuf dirname = STRBUF_INIT;
886 int ret = -1;
887
888 /*
889 * For the sake of comments in this function, suppose that
890 * refname is "refs/foo/bar".
891 */
892
893 assert(err);
894
895 strbuf_grow(&dirname, strlen(refname) + 1);
896 for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
897 /* Expand dirname to the new prefix, not including the trailing slash: */
898 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
899
900 /*
901 * We are still at a leading dir of the refname (e.g.,
902 * "refs/foo"; if there is a reference with that name,
903 * it is a conflict, *unless* it is in skip.
904 */
905 if (dir) {
906 pos = search_ref_dir(dir, dirname.buf, dirname.len);
907 if (pos >= 0 &&
908 (!skip || !string_list_has_string(skip, dirname.buf))) {
909 /*
910 * We found a reference whose name is
911 * a proper prefix of refname; e.g.,
912 * "refs/foo", and is not in skip.
913 */
914 strbuf_addf(err, "'%s' exists; cannot create '%s'",
915 dirname.buf, refname);
916 goto cleanup;
917 }
918 }
919
920 if (extras && string_list_has_string(extras, dirname.buf) &&
921 (!skip || !string_list_has_string(skip, dirname.buf))) {
922 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
923 refname, dirname.buf);
924 goto cleanup;
925 }
926
927 /*
928 * Otherwise, we can try to continue our search with
929 * the next component. So try to look up the
930 * directory, e.g., "refs/foo/". If we come up empty,
931 * we know there is nothing under this whole prefix,
932 * but even in that case we still have to continue the
933 * search for conflicts with extras.
934 */
935 strbuf_addch(&dirname, '/');
936 if (dir) {
937 pos = search_ref_dir(dir, dirname.buf, dirname.len);
938 if (pos < 0) {
939 /*
940 * There was no directory "refs/foo/",
941 * so there is nothing under this
942 * whole prefix. So there is no need
943 * to continue looking for conflicting
944 * references. But we need to continue
945 * looking for conflicting extras.
946 */
947 dir = NULL;
948 } else {
949 dir = get_ref_dir(dir->entries[pos]);
950 }
951 }
952 }
953
954 /*
955 * We are at the leaf of our refname (e.g., "refs/foo/bar").
956 * There is no point in searching for a reference with that
957 * name, because a refname isn't considered to conflict with
958 * itself. But we still need to check for references whose
959 * names are in the "refs/foo/bar/" namespace, because they
960 * *do* conflict.
961 */
962 strbuf_addstr(&dirname, refname + dirname.len);
963 strbuf_addch(&dirname, '/');
964
965 if (dir) {
966 pos = search_ref_dir(dir, dirname.buf, dirname.len);
967
968 if (pos >= 0) {
969 /*
970 * We found a directory named "$refname/"
971 * (e.g., "refs/foo/bar/"). It is a problem
972 * iff it contains any ref that is not in
973 * "skip".
974 */
975 struct nonmatching_ref_data data;
976
977 data.skip = skip;
978 data.conflicting_refname = NULL;
979 dir = get_ref_dir(dir->entries[pos]);
980 sort_ref_dir(dir);
981 if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
982 strbuf_addf(err, "'%s' exists; cannot create '%s'",
983 data.conflicting_refname, refname);
984 goto cleanup;
985 }
986 }
987 }
988
0845122c
DT
989 extra_refname = find_descendant_ref(dirname.buf, extras, skip);
990 if (extra_refname)
991 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
992 refname, extra_refname);
993 else
994 ret = 0;
7bd9bcf3
MH
995
996cleanup:
997 strbuf_release(&dirname);
998 return ret;
999}
1000
1001struct packed_ref_cache {
1002 struct ref_entry *root;
1003
1004 /*
1005 * Count of references to the data structure in this instance,
1006 * including the pointer from ref_cache::packed if any. The
1007 * data will not be freed as long as the reference count is
1008 * nonzero.
1009 */
1010 unsigned int referrers;
1011
1012 /*
1013 * Iff the packed-refs file associated with this instance is
1014 * currently locked for writing, this points at the associated
1015 * lock (which is owned by somebody else). The referrer count
1016 * is also incremented when the file is locked and decremented
1017 * when it is unlocked.
1018 */
1019 struct lock_file *lock;
1020
1021 /* The metadata from when this packed-refs cache was read */
1022 struct stat_validity validity;
1023};
1024
1025/*
1026 * Future: need to be in "struct repository"
1027 * when doing a full libification.
1028 */
1029static struct ref_cache {
1030 struct ref_cache *next;
1031 struct ref_entry *loose;
1032 struct packed_ref_cache *packed;
1033 /*
1034 * The submodule name, or "" for the main repo. We allocate
1035 * length 1 rather than FLEX_ARRAY so that the main ref_cache
1036 * is initialized correctly.
1037 */
1038 char name[1];
1039} ref_cache, *submodule_ref_caches;
1040
1041/* Lock used for the main packed-refs file: */
1042static struct lock_file packlock;
1043
1044/*
1045 * Increment the reference count of *packed_refs.
1046 */
1047static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
1048{
1049 packed_refs->referrers++;
1050}
1051
1052/*
1053 * Decrease the reference count of *packed_refs. If it goes to zero,
1054 * free *packed_refs and return true; otherwise return false.
1055 */
1056static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
1057{
1058 if (!--packed_refs->referrers) {
1059 free_ref_entry(packed_refs->root);
1060 stat_validity_clear(&packed_refs->validity);
1061 free(packed_refs);
1062 return 1;
1063 } else {
1064 return 0;
1065 }
1066}
1067
1068static void clear_packed_ref_cache(struct ref_cache *refs)
1069{
1070 if (refs->packed) {
1071 struct packed_ref_cache *packed_refs = refs->packed;
1072
1073 if (packed_refs->lock)
1074 die("internal error: packed-ref cache cleared while locked");
1075 refs->packed = NULL;
1076 release_packed_ref_cache(packed_refs);
1077 }
1078}
1079
1080static void clear_loose_ref_cache(struct ref_cache *refs)
1081{
1082 if (refs->loose) {
1083 free_ref_entry(refs->loose);
1084 refs->loose = NULL;
1085 }
1086}
1087
a2d5156c
JK
1088/*
1089 * Create a new submodule ref cache and add it to the internal
1090 * set of caches.
1091 */
7bd9bcf3
MH
1092static struct ref_cache *create_ref_cache(const char *submodule)
1093{
7bd9bcf3
MH
1094 struct ref_cache *refs;
1095 if (!submodule)
1096 submodule = "";
96ffc06f 1097 FLEX_ALLOC_STR(refs, name, submodule);
a2d5156c
JK
1098 refs->next = submodule_ref_caches;
1099 submodule_ref_caches = refs;
7bd9bcf3
MH
1100 return refs;
1101}
1102
a2d5156c 1103static struct ref_cache *lookup_ref_cache(const char *submodule)
7bd9bcf3
MH
1104{
1105 struct ref_cache *refs;
1106
1107 if (!submodule || !*submodule)
1108 return &ref_cache;
1109
1110 for (refs = submodule_ref_caches; refs; refs = refs->next)
1111 if (!strcmp(submodule, refs->name))
1112 return refs;
a2d5156c
JK
1113 return NULL;
1114}
7bd9bcf3 1115
a2d5156c
JK
1116/*
1117 * Return a pointer to a ref_cache for the specified submodule. For
2eed2780
MH
1118 * the main repository, use submodule==NULL; such a call cannot fail.
1119 * For a submodule, the submodule must exist and be a nonbare
1120 * repository, otherwise return NULL.
1121 *
1122 * The returned structure will be allocated and initialized but not
1123 * necessarily populated; it should not be freed.
a2d5156c
JK
1124 */
1125static struct ref_cache *get_ref_cache(const char *submodule)
1126{
1127 struct ref_cache *refs = lookup_ref_cache(submodule);
2eed2780
MH
1128
1129 if (!refs) {
1130 struct strbuf submodule_sb = STRBUF_INIT;
1131
1132 strbuf_addstr(&submodule_sb, submodule);
1133 if (is_nonbare_repository_dir(&submodule_sb))
1134 refs = create_ref_cache(submodule);
1135 strbuf_release(&submodule_sb);
1136 }
1137
7bd9bcf3
MH
1138 return refs;
1139}
1140
1141/* The length of a peeled reference line in packed-refs, including EOL: */
1142#define PEELED_LINE_LENGTH 42
1143
1144/*
1145 * The packed-refs header line that we write out. Perhaps other
1146 * traits will be added later. The trailing space is required.
1147 */
1148static const char PACKED_REFS_HEADER[] =
1149 "# pack-refs with: peeled fully-peeled \n";
1150
1151/*
1152 * Parse one line from a packed-refs file. Write the SHA1 to sha1.
1153 * Return a pointer to the refname within the line (null-terminated),
1154 * or NULL if there was a problem.
1155 */
1156static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
1157{
1158 const char *ref;
1159
1160 /*
1161 * 42: the answer to everything.
1162 *
1163 * In this case, it happens to be the answer to
1164 * 40 (length of sha1 hex representation)
1165 * +1 (space in between hex and name)
1166 * +1 (newline at the end of the line)
1167 */
1168 if (line->len <= 42)
1169 return NULL;
1170
1171 if (get_sha1_hex(line->buf, sha1) < 0)
1172 return NULL;
1173 if (!isspace(line->buf[40]))
1174 return NULL;
1175
1176 ref = line->buf + 41;
1177 if (isspace(*ref))
1178 return NULL;
1179
1180 if (line->buf[line->len - 1] != '\n')
1181 return NULL;
1182 line->buf[--line->len] = 0;
1183
1184 return ref;
1185}
1186
1187/*
1188 * Read f, which is a packed-refs file, into dir.
1189 *
1190 * A comment line of the form "# pack-refs with: " may contain zero or
1191 * more traits. We interpret the traits as follows:
1192 *
1193 * No traits:
1194 *
1195 * Probably no references are peeled. But if the file contains a
1196 * peeled value for a reference, we will use it.
1197 *
1198 * peeled:
1199 *
1200 * References under "refs/tags/", if they *can* be peeled, *are*
1201 * peeled in this file. References outside of "refs/tags/" are
1202 * probably not peeled even if they could have been, but if we find
1203 * a peeled value for such a reference we will use it.
1204 *
1205 * fully-peeled:
1206 *
1207 * All references in the file that can be peeled are peeled.
1208 * Inversely (and this is more important), any references in the
1209 * file for which no peeled value is recorded is not peelable. This
1210 * trait should typically be written alongside "peeled" for
1211 * compatibility with older clients, but we do not require it
1212 * (i.e., "peeled" is a no-op if "fully-peeled" is set).
1213 */
1214static void read_packed_refs(FILE *f, struct ref_dir *dir)
1215{
1216 struct ref_entry *last = NULL;
1217 struct strbuf line = STRBUF_INIT;
1218 enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
1219
1220 while (strbuf_getwholeline(&line, f, '\n') != EOF) {
1221 unsigned char sha1[20];
1222 const char *refname;
1223 const char *traits;
1224
1225 if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
1226 if (strstr(traits, " fully-peeled "))
1227 peeled = PEELED_FULLY;
1228 else if (strstr(traits, " peeled "))
1229 peeled = PEELED_TAGS;
1230 /* perhaps other traits later as well */
1231 continue;
1232 }
1233
1234 refname = parse_ref_line(&line, sha1);
1235 if (refname) {
1236 int flag = REF_ISPACKED;
1237
1238 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1239 if (!refname_is_safe(refname))
1240 die("packed refname is dangerous: %s", refname);
1241 hashclr(sha1);
1242 flag |= REF_BAD_NAME | REF_ISBROKEN;
1243 }
1244 last = create_ref_entry(refname, sha1, flag, 0);
1245 if (peeled == PEELED_FULLY ||
1246 (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
1247 last->flag |= REF_KNOWS_PEELED;
1248 add_ref(dir, last);
1249 continue;
1250 }
1251 if (last &&
1252 line.buf[0] == '^' &&
1253 line.len == PEELED_LINE_LENGTH &&
1254 line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
1255 !get_sha1_hex(line.buf + 1, sha1)) {
1256 hashcpy(last->u.value.peeled.hash, sha1);
1257 /*
1258 * Regardless of what the file header said,
1259 * we definitely know the value of *this*
1260 * reference:
1261 */
1262 last->flag |= REF_KNOWS_PEELED;
1263 }
1264 }
1265
1266 strbuf_release(&line);
1267}
1268
1269/*
1270 * Get the packed_ref_cache for the specified ref_cache, creating it
1271 * if necessary.
1272 */
1273static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
1274{
1275 char *packed_refs_file;
1276
1277 if (*refs->name)
1278 packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
1279 else
1280 packed_refs_file = git_pathdup("packed-refs");
1281
1282 if (refs->packed &&
1283 !stat_validity_check(&refs->packed->validity, packed_refs_file))
1284 clear_packed_ref_cache(refs);
1285
1286 if (!refs->packed) {
1287 FILE *f;
1288
1289 refs->packed = xcalloc(1, sizeof(*refs->packed));
1290 acquire_packed_ref_cache(refs->packed);
1291 refs->packed->root = create_dir_entry(refs, "", 0, 0);
1292 f = fopen(packed_refs_file, "r");
1293 if (f) {
1294 stat_validity_update(&refs->packed->validity, fileno(f));
1295 read_packed_refs(f, get_ref_dir(refs->packed->root));
1296 fclose(f);
1297 }
1298 }
1299 free(packed_refs_file);
1300 return refs->packed;
1301}
1302
1303static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
1304{
1305 return get_ref_dir(packed_ref_cache->root);
1306}
1307
1308static struct ref_dir *get_packed_refs(struct ref_cache *refs)
1309{
1310 return get_packed_ref_dir(get_packed_ref_cache(refs));
1311}
1312
1313/*
1314 * Add a reference to the in-memory packed reference cache. This may
1315 * only be called while the packed-refs file is locked (see
1316 * lock_packed_refs()). To actually write the packed-refs file, call
1317 * commit_packed_refs().
1318 */
1319static void add_packed_ref(const char *refname, const unsigned char *sha1)
1320{
1321 struct packed_ref_cache *packed_ref_cache =
1322 get_packed_ref_cache(&ref_cache);
1323
1324 if (!packed_ref_cache->lock)
1325 die("internal error: packed refs not locked");
1326 add_ref(get_packed_ref_dir(packed_ref_cache),
1327 create_ref_entry(refname, sha1, REF_ISPACKED, 1));
1328}
1329
1330/*
1331 * Read the loose references from the namespace dirname into dir
1332 * (without recursing). dirname must end with '/'. dir must be the
1333 * directory entry corresponding to dirname.
1334 */
1335static void read_loose_refs(const char *dirname, struct ref_dir *dir)
1336{
1337 struct ref_cache *refs = dir->ref_cache;
1338 DIR *d;
1339 struct dirent *de;
1340 int dirnamelen = strlen(dirname);
1341 struct strbuf refname;
1342 struct strbuf path = STRBUF_INIT;
1343 size_t path_baselen;
1344
1345 if (*refs->name)
1346 strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
1347 else
1348 strbuf_git_path(&path, "%s", dirname);
1349 path_baselen = path.len;
1350
1351 d = opendir(path.buf);
1352 if (!d) {
1353 strbuf_release(&path);
1354 return;
1355 }
1356
1357 strbuf_init(&refname, dirnamelen + 257);
1358 strbuf_add(&refname, dirname, dirnamelen);
1359
1360 while ((de = readdir(d)) != NULL) {
1361 unsigned char sha1[20];
1362 struct stat st;
1363 int flag;
1364
1365 if (de->d_name[0] == '.')
1366 continue;
1367 if (ends_with(de->d_name, ".lock"))
1368 continue;
1369 strbuf_addstr(&refname, de->d_name);
1370 strbuf_addstr(&path, de->d_name);
1371 if (stat(path.buf, &st) < 0) {
1372 ; /* silently ignore */
1373 } else if (S_ISDIR(st.st_mode)) {
1374 strbuf_addch(&refname, '/');
1375 add_entry_to_dir(dir,
1376 create_dir_entry(refs, refname.buf,
1377 refname.len, 1));
1378 } else {
1379 int read_ok;
1380
1381 if (*refs->name) {
1382 hashclr(sha1);
1383 flag = 0;
1384 read_ok = !resolve_gitlink_ref(refs->name,
1385 refname.buf, sha1);
1386 } else {
1387 read_ok = !read_ref_full(refname.buf,
1388 RESOLVE_REF_READING,
1389 sha1, &flag);
1390 }
1391
1392 if (!read_ok) {
1393 hashclr(sha1);
1394 flag |= REF_ISBROKEN;
1395 } else if (is_null_sha1(sha1)) {
1396 /*
1397 * It is so astronomically unlikely
1398 * that NULL_SHA1 is the SHA-1 of an
1399 * actual object that we consider its
1400 * appearance in a loose reference
1401 * file to be repo corruption
1402 * (probably due to a software bug).
1403 */
1404 flag |= REF_ISBROKEN;
1405 }
1406
1407 if (check_refname_format(refname.buf,
1408 REFNAME_ALLOW_ONELEVEL)) {
1409 if (!refname_is_safe(refname.buf))
1410 die("loose refname is dangerous: %s", refname.buf);
1411 hashclr(sha1);
1412 flag |= REF_BAD_NAME | REF_ISBROKEN;
1413 }
1414 add_entry_to_dir(dir,
1415 create_ref_entry(refname.buf, sha1, flag, 0));
1416 }
1417 strbuf_setlen(&refname, dirnamelen);
1418 strbuf_setlen(&path, path_baselen);
1419 }
1420 strbuf_release(&refname);
1421 strbuf_release(&path);
1422 closedir(d);
1423}
1424
1425static struct ref_dir *get_loose_refs(struct ref_cache *refs)
1426{
1427 if (!refs->loose) {
1428 /*
1429 * Mark the top-level directory complete because we
1430 * are about to read the only subdirectory that can
1431 * hold references:
1432 */
1433 refs->loose = create_dir_entry(refs, "", 0, 0);
1434 /*
1435 * Create an incomplete entry for "refs/":
1436 */
1437 add_entry_to_dir(get_ref_dir(refs->loose),
1438 create_dir_entry(refs, "refs/", 5, 1));
1439 }
1440 return get_ref_dir(refs->loose);
1441}
1442
7bd9bcf3
MH
1443#define MAXREFLEN (1024)
1444
1445/*
1446 * Called by resolve_gitlink_ref_recursive() after it failed to read
1447 * from the loose refs in ref_cache refs. Find <refname> in the
1448 * packed-refs file for the submodule.
1449 */
1450static int resolve_gitlink_packed_ref(struct ref_cache *refs,
1451 const char *refname, unsigned char *sha1)
1452{
1453 struct ref_entry *ref;
1454 struct ref_dir *dir = get_packed_refs(refs);
1455
1456 ref = find_ref(dir, refname);
1457 if (ref == NULL)
1458 return -1;
1459
1460 hashcpy(sha1, ref->u.value.oid.hash);
1461 return 0;
1462}
1463
1464static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
1465 const char *refname, unsigned char *sha1,
1466 int recursion)
1467{
1468 int fd, len;
1469 char buffer[128], *p;
1470 char *path;
1471
2d0663b2 1472 if (recursion > SYMREF_MAXDEPTH || strlen(refname) > MAXREFLEN)
7bd9bcf3
MH
1473 return -1;
1474 path = *refs->name
1475 ? git_pathdup_submodule(refs->name, "%s", refname)
1476 : git_pathdup("%s", refname);
1477 fd = open(path, O_RDONLY);
1478 free(path);
1479 if (fd < 0)
1480 return resolve_gitlink_packed_ref(refs, refname, sha1);
1481
1482 len = read(fd, buffer, sizeof(buffer)-1);
1483 close(fd);
1484 if (len < 0)
1485 return -1;
1486 while (len && isspace(buffer[len-1]))
1487 len--;
1488 buffer[len] = 0;
1489
1490 /* Was it a detached head or an old-fashioned symlink? */
1491 if (!get_sha1_hex(buffer, sha1))
1492 return 0;
1493
1494 /* Symref? */
1495 if (strncmp(buffer, "ref:", 4))
1496 return -1;
1497 p = buffer + 4;
1498 while (isspace(*p))
1499 p++;
1500
1501 return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
1502}
1503
1504int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
1505{
1506 int len = strlen(path), retval;
a2d5156c 1507 struct strbuf submodule = STRBUF_INIT;
7bd9bcf3
MH
1508 struct ref_cache *refs;
1509
1510 while (len && path[len-1] == '/')
1511 len--;
1512 if (!len)
1513 return -1;
a2d5156c
JK
1514
1515 strbuf_add(&submodule, path, len);
2eed2780 1516 refs = get_ref_cache(submodule.buf);
a2d5156c 1517 if (!refs) {
2eed2780
MH
1518 strbuf_release(&submodule);
1519 return -1;
a2d5156c
JK
1520 }
1521 strbuf_release(&submodule);
7bd9bcf3
MH
1522
1523 retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
1524 return retval;
1525}
1526
1527/*
1528 * Return the ref_entry for the given refname from the packed
1529 * references. If it does not exist, return NULL.
1530 */
1531static struct ref_entry *get_packed_ref(const char *refname)
1532{
1533 return find_ref(get_packed_refs(&ref_cache), refname);
1534}
1535
1536/*
419c6f4c 1537 * A loose ref file doesn't exist; check for a packed ref.
7bd9bcf3
MH
1538 */
1539static int resolve_missing_loose_ref(const char *refname,
7bd9bcf3 1540 unsigned char *sha1,
89e82389 1541 unsigned int *flags)
7bd9bcf3
MH
1542{
1543 struct ref_entry *entry;
1544
1545 /*
1546 * The loose reference file does not exist; check for a packed
1547 * reference.
1548 */
1549 entry = get_packed_ref(refname);
1550 if (entry) {
1551 hashcpy(sha1, entry->u.value.oid.hash);
a70a93b7 1552 *flags |= REF_ISPACKED;
7bd9bcf3
MH
1553 return 0;
1554 }
419c6f4c
MH
1555 /* refname is not a packed reference. */
1556 return -1;
7bd9bcf3
MH
1557}
1558
2d0663b2 1559int read_raw_ref(const char *refname, unsigned char *sha1,
92b38093 1560 struct strbuf *referent, unsigned int *type)
7bd9bcf3 1561{
42a38cf7
MH
1562 struct strbuf sb_contents = STRBUF_INIT;
1563 struct strbuf sb_path = STRBUF_INIT;
7048653a
DT
1564 const char *path;
1565 const char *buf;
1566 struct stat st;
1567 int fd;
42a38cf7
MH
1568 int ret = -1;
1569 int save_errno;
7bd9bcf3 1570
fa96ea1b 1571 *type = 0;
42a38cf7
MH
1572 strbuf_reset(&sb_path);
1573 strbuf_git_path(&sb_path, "%s", refname);
1574 path = sb_path.buf;
7bd9bcf3 1575
7048653a
DT
1576stat_ref:
1577 /*
1578 * We might have to loop back here to avoid a race
1579 * condition: first we lstat() the file, then we try
1580 * to read it as a link or as a file. But if somebody
1581 * changes the type of the file (file <-> directory
1582 * <-> symlink) between the lstat() and reading, then
1583 * we don't want to report that as an error but rather
1584 * try again starting with the lstat().
1585 */
7bd9bcf3 1586
7048653a
DT
1587 if (lstat(path, &st) < 0) {
1588 if (errno != ENOENT)
42a38cf7 1589 goto out;
3a0b6b9a 1590 if (resolve_missing_loose_ref(refname, sha1, type)) {
7048653a 1591 errno = ENOENT;
42a38cf7 1592 goto out;
7bd9bcf3 1593 }
42a38cf7
MH
1594 ret = 0;
1595 goto out;
7bd9bcf3 1596 }
7bd9bcf3 1597
7048653a
DT
1598 /* Follow "normalized" - ie "refs/.." symlinks by hand */
1599 if (S_ISLNK(st.st_mode)) {
42a38cf7
MH
1600 strbuf_reset(&sb_contents);
1601 if (strbuf_readlink(&sb_contents, path, 0) < 0) {
7048653a 1602 if (errno == ENOENT || errno == EINVAL)
7bd9bcf3
MH
1603 /* inconsistent with lstat; retry */
1604 goto stat_ref;
1605 else
42a38cf7 1606 goto out;
7bd9bcf3 1607 }
42a38cf7
MH
1608 if (starts_with(sb_contents.buf, "refs/") &&
1609 !check_refname_format(sb_contents.buf, 0)) {
92b38093 1610 strbuf_swap(&sb_contents, referent);
3a0b6b9a 1611 *type |= REF_ISSYMREF;
42a38cf7
MH
1612 ret = 0;
1613 goto out;
7bd9bcf3 1614 }
7048653a 1615 }
7bd9bcf3 1616
7048653a
DT
1617 /* Is it a directory? */
1618 if (S_ISDIR(st.st_mode)) {
e167a567
MH
1619 /*
1620 * Even though there is a directory where the loose
1621 * ref is supposed to be, there could still be a
1622 * packed ref:
1623 */
3a0b6b9a 1624 if (resolve_missing_loose_ref(refname, sha1, type)) {
e167a567
MH
1625 errno = EISDIR;
1626 goto out;
1627 }
1628 ret = 0;
42a38cf7 1629 goto out;
7048653a
DT
1630 }
1631
1632 /*
1633 * Anything else, just open it and try to use it as
1634 * a ref
1635 */
1636 fd = open(path, O_RDONLY);
1637 if (fd < 0) {
1638 if (errno == ENOENT)
1639 /* inconsistent with lstat; retry */
1640 goto stat_ref;
1641 else
42a38cf7 1642 goto out;
7048653a 1643 }
42a38cf7
MH
1644 strbuf_reset(&sb_contents);
1645 if (strbuf_read(&sb_contents, fd, 256) < 0) {
7048653a
DT
1646 int save_errno = errno;
1647 close(fd);
1648 errno = save_errno;
42a38cf7 1649 goto out;
7048653a
DT
1650 }
1651 close(fd);
42a38cf7
MH
1652 strbuf_rtrim(&sb_contents);
1653 buf = sb_contents.buf;
7048653a
DT
1654 if (starts_with(buf, "ref:")) {
1655 buf += 4;
7bd9bcf3
MH
1656 while (isspace(*buf))
1657 buf++;
7048653a 1658
92b38093
MH
1659 strbuf_reset(referent);
1660 strbuf_addstr(referent, buf);
3a0b6b9a 1661 *type |= REF_ISSYMREF;
42a38cf7
MH
1662 ret = 0;
1663 goto out;
7bd9bcf3 1664 }
7bd9bcf3 1665
7048653a
DT
1666 /*
1667 * Please note that FETCH_HEAD has additional
1668 * data after the sha.
1669 */
1670 if (get_sha1_hex(buf, sha1) ||
1671 (buf[40] != '\0' && !isspace(buf[40]))) {
3a0b6b9a 1672 *type |= REF_ISBROKEN;
7048653a 1673 errno = EINVAL;
42a38cf7 1674 goto out;
7048653a
DT
1675 }
1676
42a38cf7 1677 ret = 0;
7bd9bcf3 1678
42a38cf7
MH
1679out:
1680 save_errno = errno;
7bd9bcf3
MH
1681 strbuf_release(&sb_path);
1682 strbuf_release(&sb_contents);
42a38cf7 1683 errno = save_errno;
7bd9bcf3
MH
1684 return ret;
1685}
1686
8415d247
MH
1687static void unlock_ref(struct ref_lock *lock)
1688{
1689 /* Do not free lock->lk -- atexit() still looks at them */
1690 if (lock->lk)
1691 rollback_lock_file(lock->lk);
1692 free(lock->ref_name);
8415d247
MH
1693 free(lock);
1694}
1695
92b1551b
MH
1696/*
1697 * Lock refname, without following symrefs, and set *lock_p to point
1698 * at a newly-allocated lock object. Fill in lock->old_oid, referent,
1699 * and type similarly to read_raw_ref().
1700 *
1701 * The caller must verify that refname is a "safe" reference name (in
1702 * the sense of refname_is_safe()) before calling this function.
1703 *
1704 * If the reference doesn't already exist, verify that refname doesn't
1705 * have a D/F conflict with any existing references. extras and skip
1706 * are passed to verify_refname_available_dir() for this check.
1707 *
1708 * If mustexist is not set and the reference is not found or is
1709 * broken, lock the reference anyway but clear sha1.
1710 *
1711 * Return 0 on success. On failure, write an error message to err and
1712 * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
1713 *
1714 * Implementation note: This function is basically
1715 *
1716 * lock reference
1717 * read_raw_ref()
1718 *
1719 * but it includes a lot more code to
1720 * - Deal with possible races with other processes
1721 * - Avoid calling verify_refname_available_dir() when it can be
1722 * avoided, namely if we were successfully able to read the ref
1723 * - Generate informative error messages in the case of failure
1724 */
1725static int lock_raw_ref(const char *refname, int mustexist,
1726 const struct string_list *extras,
1727 const struct string_list *skip,
1728 struct ref_lock **lock_p,
1729 struct strbuf *referent,
1730 unsigned int *type,
1731 struct strbuf *err)
1732{
1733 struct ref_lock *lock;
1734 struct strbuf ref_file = STRBUF_INIT;
1735 int attempts_remaining = 3;
1736 int ret = TRANSACTION_GENERIC_ERROR;
1737
1738 assert(err);
1739 *type = 0;
1740
1741 /* First lock the file so it can't change out from under us. */
1742
1743 *lock_p = lock = xcalloc(1, sizeof(*lock));
1744
1745 lock->ref_name = xstrdup(refname);
92b1551b
MH
1746 strbuf_git_path(&ref_file, "%s", refname);
1747
1748retry:
1749 switch (safe_create_leading_directories(ref_file.buf)) {
1750 case SCLD_OK:
1751 break; /* success */
1752 case SCLD_EXISTS:
1753 /*
1754 * Suppose refname is "refs/foo/bar". We just failed
1755 * to create the containing directory, "refs/foo",
1756 * because there was a non-directory in the way. This
1757 * indicates a D/F conflict, probably because of
1758 * another reference such as "refs/foo". There is no
1759 * reason to expect this error to be transitory.
1760 */
1761 if (verify_refname_available(refname, extras, skip, err)) {
1762 if (mustexist) {
1763 /*
1764 * To the user the relevant error is
1765 * that the "mustexist" reference is
1766 * missing:
1767 */
1768 strbuf_reset(err);
1769 strbuf_addf(err, "unable to resolve reference '%s'",
1770 refname);
1771 } else {
1772 /*
1773 * The error message set by
1774 * verify_refname_available_dir() is OK.
1775 */
1776 ret = TRANSACTION_NAME_CONFLICT;
1777 }
1778 } else {
1779 /*
1780 * The file that is in the way isn't a loose
1781 * reference. Report it as a low-level
1782 * failure.
1783 */
1784 strbuf_addf(err, "unable to create lock file %s.lock; "
1785 "non-directory in the way",
1786 ref_file.buf);
1787 }
1788 goto error_return;
1789 case SCLD_VANISHED:
1790 /* Maybe another process was tidying up. Try again. */
1791 if (--attempts_remaining > 0)
1792 goto retry;
1793 /* fall through */
1794 default:
1795 strbuf_addf(err, "unable to create directory for %s",
1796 ref_file.buf);
1797 goto error_return;
1798 }
1799
1800 if (!lock->lk)
1801 lock->lk = xcalloc(1, sizeof(struct lock_file));
1802
1803 if (hold_lock_file_for_update(lock->lk, ref_file.buf, LOCK_NO_DEREF) < 0) {
1804 if (errno == ENOENT && --attempts_remaining > 0) {
1805 /*
1806 * Maybe somebody just deleted one of the
1807 * directories leading to ref_file. Try
1808 * again:
1809 */
1810 goto retry;
1811 } else {
1812 unable_to_lock_message(ref_file.buf, errno, err);
1813 goto error_return;
1814 }
1815 }
1816
1817 /*
1818 * Now we hold the lock and can read the reference without
1819 * fear that its value will change.
1820 */
1821
1822 if (read_raw_ref(refname, lock->old_oid.hash, referent, type)) {
1823 if (errno == ENOENT) {
1824 if (mustexist) {
1825 /* Garden variety missing reference. */
1826 strbuf_addf(err, "unable to resolve reference '%s'",
1827 refname);
1828 goto error_return;
1829 } else {
1830 /*
1831 * Reference is missing, but that's OK. We
1832 * know that there is not a conflict with
1833 * another loose reference because
1834 * (supposing that we are trying to lock
1835 * reference "refs/foo/bar"):
1836 *
1837 * - We were successfully able to create
1838 * the lockfile refs/foo/bar.lock, so we
1839 * know there cannot be a loose reference
1840 * named "refs/foo".
1841 *
1842 * - We got ENOENT and not EISDIR, so we
1843 * know that there cannot be a loose
1844 * reference named "refs/foo/bar/baz".
1845 */
1846 }
1847 } else if (errno == EISDIR) {
1848 /*
1849 * There is a directory in the way. It might have
1850 * contained references that have been deleted. If
1851 * we don't require that the reference already
1852 * exists, try to remove the directory so that it
1853 * doesn't cause trouble when we want to rename the
1854 * lockfile into place later.
1855 */
1856 if (mustexist) {
1857 /* Garden variety missing reference. */
1858 strbuf_addf(err, "unable to resolve reference '%s'",
1859 refname);
1860 goto error_return;
1861 } else if (remove_dir_recursively(&ref_file,
1862 REMOVE_DIR_EMPTY_ONLY)) {
1863 if (verify_refname_available_dir(
1864 refname, extras, skip,
1865 get_loose_refs(&ref_cache),
1866 err)) {
1867 /*
1868 * The error message set by
1869 * verify_refname_available() is OK.
1870 */
1871 ret = TRANSACTION_NAME_CONFLICT;
1872 goto error_return;
1873 } else {
1874 /*
1875 * We can't delete the directory,
1876 * but we also don't know of any
1877 * references that it should
1878 * contain.
1879 */
1880 strbuf_addf(err, "there is a non-empty directory '%s' "
1881 "blocking reference '%s'",
1882 ref_file.buf, refname);
1883 goto error_return;
1884 }
1885 }
1886 } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
1887 strbuf_addf(err, "unable to resolve reference '%s': "
1888 "reference broken", refname);
1889 goto error_return;
1890 } else {
1891 strbuf_addf(err, "unable to resolve reference '%s': %s",
1892 refname, strerror(errno));
1893 goto error_return;
1894 }
1895
1896 /*
1897 * If the ref did not exist and we are creating it,
1898 * make sure there is no existing packed ref whose
1899 * name begins with our refname, nor a packed ref
1900 * whose name is a proper prefix of our refname.
1901 */
1902 if (verify_refname_available_dir(
1903 refname, extras, skip,
1904 get_packed_refs(&ref_cache),
1905 err)) {
1906 goto error_return;
1907 }
1908 }
1909
1910 ret = 0;
1911 goto out;
1912
1913error_return:
1914 unlock_ref(lock);
1915 *lock_p = NULL;
1916
1917out:
1918 strbuf_release(&ref_file);
1919 return ret;
1920}
1921
7bd9bcf3
MH
1922/*
1923 * Peel the entry (if possible) and return its new peel_status. If
1924 * repeel is true, re-peel the entry even if there is an old peeled
1925 * value that is already stored in it.
1926 *
1927 * It is OK to call this function with a packed reference entry that
1928 * might be stale and might even refer to an object that has since
1929 * been garbage-collected. In such a case, if the entry has
1930 * REF_KNOWS_PEELED then leave the status unchanged and return
1931 * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
1932 */
1933static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
1934{
1935 enum peel_status status;
1936
1937 if (entry->flag & REF_KNOWS_PEELED) {
1938 if (repeel) {
1939 entry->flag &= ~REF_KNOWS_PEELED;
1940 oidclr(&entry->u.value.peeled);
1941 } else {
1942 return is_null_oid(&entry->u.value.peeled) ?
1943 PEEL_NON_TAG : PEEL_PEELED;
1944 }
1945 }
1946 if (entry->flag & REF_ISBROKEN)
1947 return PEEL_BROKEN;
1948 if (entry->flag & REF_ISSYMREF)
1949 return PEEL_IS_SYMREF;
1950
1951 status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
1952 if (status == PEEL_PEELED || status == PEEL_NON_TAG)
1953 entry->flag |= REF_KNOWS_PEELED;
1954 return status;
1955}
1956
1957int peel_ref(const char *refname, unsigned char *sha1)
1958{
1959 int flag;
1960 unsigned char base[20];
1961
1962 if (current_ref && (current_ref->name == refname
1963 || !strcmp(current_ref->name, refname))) {
1964 if (peel_entry(current_ref, 0))
1965 return -1;
1966 hashcpy(sha1, current_ref->u.value.peeled.hash);
1967 return 0;
1968 }
1969
1970 if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
1971 return -1;
1972
1973 /*
1974 * If the reference is packed, read its ref_entry from the
1975 * cache in the hope that we already know its peeled value.
1976 * We only try this optimization on packed references because
1977 * (a) forcing the filling of the loose reference cache could
1978 * be expensive and (b) loose references anyway usually do not
1979 * have REF_KNOWS_PEELED.
1980 */
1981 if (flag & REF_ISPACKED) {
1982 struct ref_entry *r = get_packed_ref(refname);
1983 if (r) {
1984 if (peel_entry(r, 0))
1985 return -1;
1986 hashcpy(sha1, r->u.value.peeled.hash);
1987 return 0;
1988 }
1989 }
1990
1991 return peel_object(base, sha1);
1992}
1993
3bc581b9
MH
1994struct files_ref_iterator {
1995 struct ref_iterator base;
1996
1997 struct packed_ref_cache *packed_ref_cache;
1998 struct ref_iterator *iter0;
1999 unsigned int flags;
2000};
2001
2002static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
2003{
2004 struct files_ref_iterator *iter =
2005 (struct files_ref_iterator *)ref_iterator;
2006 int ok;
2007
2008 while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
2009 if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
2010 !ref_resolves_to_object(iter->iter0->refname,
2011 iter->iter0->oid,
2012 iter->iter0->flags))
2013 continue;
2014
2015 iter->base.refname = iter->iter0->refname;
2016 iter->base.oid = iter->iter0->oid;
2017 iter->base.flags = iter->iter0->flags;
2018 return ITER_OK;
2019 }
2020
2021 iter->iter0 = NULL;
2022 if (ref_iterator_abort(ref_iterator) != ITER_DONE)
2023 ok = ITER_ERROR;
2024
2025 return ok;
2026}
2027
2028static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
2029 struct object_id *peeled)
2030{
2031 struct files_ref_iterator *iter =
2032 (struct files_ref_iterator *)ref_iterator;
2033
2034 return ref_iterator_peel(iter->iter0, peeled);
2035}
2036
2037static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
2038{
2039 struct files_ref_iterator *iter =
2040 (struct files_ref_iterator *)ref_iterator;
2041 int ok = ITER_DONE;
2042
2043 if (iter->iter0)
2044 ok = ref_iterator_abort(iter->iter0);
2045
2046 release_packed_ref_cache(iter->packed_ref_cache);
2047 base_ref_iterator_free(ref_iterator);
2048 return ok;
2049}
2050
2051static struct ref_iterator_vtable files_ref_iterator_vtable = {
2052 files_ref_iterator_advance,
2053 files_ref_iterator_peel,
2054 files_ref_iterator_abort
2055};
2056
2057struct ref_iterator *files_ref_iterator_begin(
2058 const char *submodule,
2059 const char *prefix, unsigned int flags)
2060{
2061 struct ref_cache *refs = get_ref_cache(submodule);
2062 struct ref_dir *loose_dir, *packed_dir;
2063 struct ref_iterator *loose_iter, *packed_iter;
2064 struct files_ref_iterator *iter;
2065 struct ref_iterator *ref_iterator;
2066
2067 if (!refs)
2068 return empty_ref_iterator_begin();
2069
2070 if (ref_paranoia < 0)
2071 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
2072 if (ref_paranoia)
2073 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
2074
2075 iter = xcalloc(1, sizeof(*iter));
2076 ref_iterator = &iter->base;
2077 base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable);
2078
2079 /*
2080 * We must make sure that all loose refs are read before
2081 * accessing the packed-refs file; this avoids a race
2082 * condition if loose refs are migrated to the packed-refs
2083 * file by a simultaneous process, but our in-memory view is
2084 * from before the migration. We ensure this as follows:
2085 * First, we call prime_ref_dir(), which pre-reads the loose
2086 * references for the subtree into the cache. (If they've
2087 * already been read, that's OK; we only need to guarantee
2088 * that they're read before the packed refs, not *how much*
2089 * before.) After that, we call get_packed_ref_cache(), which
2090 * internally checks whether the packed-ref cache is up to
2091 * date with what is on disk, and re-reads it if not.
2092 */
2093
2094 loose_dir = get_loose_refs(refs);
2095
2096 if (prefix && *prefix)
2097 loose_dir = find_containing_dir(loose_dir, prefix, 0);
2098
2099 if (loose_dir) {
2100 prime_ref_dir(loose_dir);
2101 loose_iter = cache_ref_iterator_begin(loose_dir);
2102 } else {
2103 /* There's nothing to iterate over. */
2104 loose_iter = empty_ref_iterator_begin();
2105 }
2106
2107 iter->packed_ref_cache = get_packed_ref_cache(refs);
2108 acquire_packed_ref_cache(iter->packed_ref_cache);
2109 packed_dir = get_packed_ref_dir(iter->packed_ref_cache);
2110
2111 if (prefix && *prefix)
2112 packed_dir = find_containing_dir(packed_dir, prefix, 0);
2113
2114 if (packed_dir) {
2115 packed_iter = cache_ref_iterator_begin(packed_dir);
2116 } else {
2117 /* There's nothing to iterate over. */
2118 packed_iter = empty_ref_iterator_begin();
2119 }
2120
2121 iter->iter0 = overlay_ref_iterator_begin(loose_iter, packed_iter);
2122 iter->flags = flags;
2123
2124 return ref_iterator;
2125}
2126
7bd9bcf3
MH
2127/*
2128 * Call fn for each reference in the specified ref_cache, omitting
4633a846
MH
2129 * references not in the containing_dir of prefix. Call fn for all
2130 * references, including broken ones. If fn ever returns a non-zero
7bd9bcf3
MH
2131 * value, stop the iteration and return that value; otherwise, return
2132 * 0.
2133 */
4633a846 2134static int do_for_each_entry(struct ref_cache *refs, const char *prefix,
7bd9bcf3
MH
2135 each_ref_entry_fn fn, void *cb_data)
2136{
2137 struct packed_ref_cache *packed_ref_cache;
2138 struct ref_dir *loose_dir;
2139 struct ref_dir *packed_dir;
2140 int retval = 0;
2141
2142 /*
2143 * We must make sure that all loose refs are read before accessing the
2144 * packed-refs file; this avoids a race condition in which loose refs
2145 * are migrated to the packed-refs file by a simultaneous process, but
2146 * our in-memory view is from before the migration. get_packed_ref_cache()
2147 * takes care of making sure our view is up to date with what is on
2148 * disk.
2149 */
2150 loose_dir = get_loose_refs(refs);
4633a846
MH
2151 if (prefix && *prefix) {
2152 loose_dir = find_containing_dir(loose_dir, prefix, 0);
7bd9bcf3
MH
2153 }
2154 if (loose_dir)
2155 prime_ref_dir(loose_dir);
2156
2157 packed_ref_cache = get_packed_ref_cache(refs);
2158 acquire_packed_ref_cache(packed_ref_cache);
2159 packed_dir = get_packed_ref_dir(packed_ref_cache);
4633a846
MH
2160 if (prefix && *prefix) {
2161 packed_dir = find_containing_dir(packed_dir, prefix, 0);
7bd9bcf3
MH
2162 }
2163
2164 if (packed_dir && loose_dir) {
2165 sort_ref_dir(packed_dir);
2166 sort_ref_dir(loose_dir);
2167 retval = do_for_each_entry_in_dirs(
2168 packed_dir, loose_dir, fn, cb_data);
2169 } else if (packed_dir) {
2170 sort_ref_dir(packed_dir);
2171 retval = do_for_each_entry_in_dir(
2172 packed_dir, 0, fn, cb_data);
2173 } else if (loose_dir) {
2174 sort_ref_dir(loose_dir);
2175 retval = do_for_each_entry_in_dir(
2176 loose_dir, 0, fn, cb_data);
2177 }
2178
2179 release_packed_ref_cache(packed_ref_cache);
2180 return retval;
2181}
2182
4633a846 2183int do_for_each_ref(const char *submodule, const char *prefix,
93770590 2184 each_ref_fn fn, int trim, int flags, void *cb_data)
7bd9bcf3
MH
2185{
2186 struct ref_entry_cb data;
93770590
DT
2187 struct ref_cache *refs;
2188
2189 refs = get_ref_cache(submodule);
2eed2780
MH
2190 if (!refs)
2191 return 0;
2192
4633a846 2193 data.prefix = prefix;
7bd9bcf3
MH
2194 data.trim = trim;
2195 data.flags = flags;
2196 data.fn = fn;
2197 data.cb_data = cb_data;
2198
2199 if (ref_paranoia < 0)
2200 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
2201 if (ref_paranoia)
2202 data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
2203
4633a846 2204 return do_for_each_entry(refs, prefix, do_one_ref, &data);
7bd9bcf3
MH
2205}
2206
7bd9bcf3
MH
2207/*
2208 * Verify that the reference locked by lock has the value old_sha1.
2209 * Fail if the reference doesn't exist and mustexist is set. Return 0
2210 * on success. On error, write an error message to err, set errno, and
2211 * return a negative value.
2212 */
2213static int verify_lock(struct ref_lock *lock,
2214 const unsigned char *old_sha1, int mustexist,
2215 struct strbuf *err)
2216{
2217 assert(err);
2218
2219 if (read_ref_full(lock->ref_name,
2220 mustexist ? RESOLVE_REF_READING : 0,
2221 lock->old_oid.hash, NULL)) {
6294dcb4
JK
2222 if (old_sha1) {
2223 int save_errno = errno;
0568c8e9 2224 strbuf_addf(err, "can't verify ref '%s'", lock->ref_name);
6294dcb4
JK
2225 errno = save_errno;
2226 return -1;
2227 } else {
2228 hashclr(lock->old_oid.hash);
2229 return 0;
2230 }
7bd9bcf3 2231 }
6294dcb4 2232 if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
0568c8e9 2233 strbuf_addf(err, "ref '%s' is at %s but expected %s",
7bd9bcf3
MH
2234 lock->ref_name,
2235 sha1_to_hex(lock->old_oid.hash),
2236 sha1_to_hex(old_sha1));
2237 errno = EBUSY;
2238 return -1;
2239 }
2240 return 0;
2241}
2242
2243static int remove_empty_directories(struct strbuf *path)
2244{
2245 /*
2246 * we want to create a file but there is a directory there;
2247 * if that is an empty directory (or a directory that contains
2248 * only empty directories), remove them.
2249 */
2250 return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
2251}
2252
2253/*
2254 * Locks a ref returning the lock on success and NULL on failure.
2255 * On failure errno is set to something meaningful.
2256 */
2257static struct ref_lock *lock_ref_sha1_basic(const char *refname,
2258 const unsigned char *old_sha1,
2259 const struct string_list *extras,
2260 const struct string_list *skip,
bcb497d0 2261 unsigned int flags, int *type,
7bd9bcf3
MH
2262 struct strbuf *err)
2263{
2264 struct strbuf ref_file = STRBUF_INIT;
7bd9bcf3
MH
2265 struct ref_lock *lock;
2266 int last_errno = 0;
7a418f3a 2267 int lflags = LOCK_NO_DEREF;
7bd9bcf3 2268 int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
7a418f3a 2269 int resolve_flags = RESOLVE_REF_NO_RECURSE;
7bd9bcf3 2270 int attempts_remaining = 3;
7a418f3a 2271 int resolved;
7bd9bcf3
MH
2272
2273 assert(err);
2274
2275 lock = xcalloc(1, sizeof(struct ref_lock));
2276
2277 if (mustexist)
2278 resolve_flags |= RESOLVE_REF_READING;
2859dcd4 2279 if (flags & REF_DELETING)
7bd9bcf3 2280 resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
7bd9bcf3 2281
7a418f3a
MH
2282 strbuf_git_path(&ref_file, "%s", refname);
2283 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2284 lock->old_oid.hash, type);
2285 if (!resolved && errno == EISDIR) {
7bd9bcf3
MH
2286 /*
2287 * we are trying to lock foo but we used to
2288 * have foo/bar which now does not exist;
2289 * it is normal for the empty directory 'foo'
2290 * to remain.
2291 */
7a418f3a 2292 if (remove_empty_directories(&ref_file)) {
7bd9bcf3 2293 last_errno = errno;
7a418f3a 2294 if (!verify_refname_available_dir(refname, extras, skip,
7bd9bcf3
MH
2295 get_loose_refs(&ref_cache), err))
2296 strbuf_addf(err, "there are still refs under '%s'",
7a418f3a 2297 refname);
7bd9bcf3
MH
2298 goto error_return;
2299 }
7a418f3a
MH
2300 resolved = !!resolve_ref_unsafe(refname, resolve_flags,
2301 lock->old_oid.hash, type);
7bd9bcf3 2302 }
7a418f3a 2303 if (!resolved) {
7bd9bcf3
MH
2304 last_errno = errno;
2305 if (last_errno != ENOTDIR ||
7a418f3a 2306 !verify_refname_available_dir(refname, extras, skip,
7bd9bcf3 2307 get_loose_refs(&ref_cache), err))
0568c8e9 2308 strbuf_addf(err, "unable to resolve reference '%s': %s",
7a418f3a 2309 refname, strerror(last_errno));
7bd9bcf3
MH
2310
2311 goto error_return;
2312 }
2859dcd4 2313
7bd9bcf3
MH
2314 /*
2315 * If the ref did not exist and we are creating it, make sure
2316 * there is no existing packed ref whose name begins with our
2317 * refname, nor a packed ref whose name is a proper prefix of
2318 * our refname.
2319 */
2320 if (is_null_oid(&lock->old_oid) &&
2321 verify_refname_available_dir(refname, extras, skip,
2322 get_packed_refs(&ref_cache), err)) {
2323 last_errno = ENOTDIR;
2324 goto error_return;
2325 }
2326
2327 lock->lk = xcalloc(1, sizeof(struct lock_file));
2328
7bd9bcf3 2329 lock->ref_name = xstrdup(refname);
7bd9bcf3
MH
2330
2331 retry:
2332 switch (safe_create_leading_directories_const(ref_file.buf)) {
2333 case SCLD_OK:
2334 break; /* success */
2335 case SCLD_VANISHED:
2336 if (--attempts_remaining > 0)
2337 goto retry;
2338 /* fall through */
2339 default:
2340 last_errno = errno;
0568c8e9 2341 strbuf_addf(err, "unable to create directory for '%s'",
7bd9bcf3
MH
2342 ref_file.buf);
2343 goto error_return;
2344 }
2345
2346 if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
2347 last_errno = errno;
2348 if (errno == ENOENT && --attempts_remaining > 0)
2349 /*
2350 * Maybe somebody just deleted one of the
2351 * directories leading to ref_file. Try
2352 * again:
2353 */
2354 goto retry;
2355 else {
2356 unable_to_lock_message(ref_file.buf, errno, err);
2357 goto error_return;
2358 }
2359 }
6294dcb4 2360 if (verify_lock(lock, old_sha1, mustexist, err)) {
7bd9bcf3
MH
2361 last_errno = errno;
2362 goto error_return;
2363 }
2364 goto out;
2365
2366 error_return:
2367 unlock_ref(lock);
2368 lock = NULL;
2369
2370 out:
2371 strbuf_release(&ref_file);
7bd9bcf3
MH
2372 errno = last_errno;
2373 return lock;
2374}
2375
2376/*
2377 * Write an entry to the packed-refs file for the specified refname.
2378 * If peeled is non-NULL, write it as the entry's peeled value.
2379 */
2380static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
2381 unsigned char *peeled)
2382{
2383 fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
2384 if (peeled)
2385 fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
2386}
2387
2388/*
2389 * An each_ref_entry_fn that writes the entry to a packed-refs file.
2390 */
2391static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
2392{
2393 enum peel_status peel_status = peel_entry(entry, 0);
2394
2395 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2396 error("internal error: %s is not a valid packed reference!",
2397 entry->name);
2398 write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
2399 peel_status == PEEL_PEELED ?
2400 entry->u.value.peeled.hash : NULL);
2401 return 0;
2402}
2403
2404/*
2405 * Lock the packed-refs file for writing. Flags is passed to
2406 * hold_lock_file_for_update(). Return 0 on success. On errors, set
2407 * errno appropriately and return a nonzero value.
2408 */
2409static int lock_packed_refs(int flags)
2410{
2411 static int timeout_configured = 0;
2412 static int timeout_value = 1000;
2413
2414 struct packed_ref_cache *packed_ref_cache;
2415
2416 if (!timeout_configured) {
2417 git_config_get_int("core.packedrefstimeout", &timeout_value);
2418 timeout_configured = 1;
2419 }
2420
2421 if (hold_lock_file_for_update_timeout(
2422 &packlock, git_path("packed-refs"),
2423 flags, timeout_value) < 0)
2424 return -1;
2425 /*
2426 * Get the current packed-refs while holding the lock. If the
2427 * packed-refs file has been modified since we last read it,
2428 * this will automatically invalidate the cache and re-read
2429 * the packed-refs file.
2430 */
2431 packed_ref_cache = get_packed_ref_cache(&ref_cache);
2432 packed_ref_cache->lock = &packlock;
2433 /* Increment the reference count to prevent it from being freed: */
2434 acquire_packed_ref_cache(packed_ref_cache);
2435 return 0;
2436}
2437
2438/*
2439 * Write the current version of the packed refs cache from memory to
2440 * disk. The packed-refs file must already be locked for writing (see
2441 * lock_packed_refs()). Return zero on success. On errors, set errno
2442 * and return a nonzero value
2443 */
2444static int commit_packed_refs(void)
2445{
2446 struct packed_ref_cache *packed_ref_cache =
2447 get_packed_ref_cache(&ref_cache);
2448 int error = 0;
2449 int save_errno = 0;
2450 FILE *out;
2451
2452 if (!packed_ref_cache->lock)
2453 die("internal error: packed-refs not locked");
2454
2455 out = fdopen_lock_file(packed_ref_cache->lock, "w");
2456 if (!out)
2457 die_errno("unable to fdopen packed-refs descriptor");
2458
2459 fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
2460 do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
2461 0, write_packed_entry_fn, out);
2462
2463 if (commit_lock_file(packed_ref_cache->lock)) {
2464 save_errno = errno;
2465 error = -1;
2466 }
2467 packed_ref_cache->lock = NULL;
2468 release_packed_ref_cache(packed_ref_cache);
2469 errno = save_errno;
2470 return error;
2471}
2472
2473/*
2474 * Rollback the lockfile for the packed-refs file, and discard the
2475 * in-memory packed reference cache. (The packed-refs file will be
2476 * read anew if it is needed again after this function is called.)
2477 */
2478static void rollback_packed_refs(void)
2479{
2480 struct packed_ref_cache *packed_ref_cache =
2481 get_packed_ref_cache(&ref_cache);
2482
2483 if (!packed_ref_cache->lock)
2484 die("internal error: packed-refs not locked");
2485 rollback_lock_file(packed_ref_cache->lock);
2486 packed_ref_cache->lock = NULL;
2487 release_packed_ref_cache(packed_ref_cache);
2488 clear_packed_ref_cache(&ref_cache);
2489}
2490
2491struct ref_to_prune {
2492 struct ref_to_prune *next;
2493 unsigned char sha1[20];
2494 char name[FLEX_ARRAY];
2495};
2496
2497struct pack_refs_cb_data {
2498 unsigned int flags;
2499 struct ref_dir *packed_refs;
2500 struct ref_to_prune *ref_to_prune;
2501};
2502
2503/*
2504 * An each_ref_entry_fn that is run over loose references only. If
2505 * the loose reference can be packed, add an entry in the packed ref
2506 * cache. If the reference should be pruned, also add it to
2507 * ref_to_prune in the pack_refs_cb_data.
2508 */
2509static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
2510{
2511 struct pack_refs_cb_data *cb = cb_data;
2512 enum peel_status peel_status;
2513 struct ref_entry *packed_entry;
2514 int is_tag_ref = starts_with(entry->name, "refs/tags/");
2515
2516 /* Do not pack per-worktree refs: */
2517 if (ref_type(entry->name) != REF_TYPE_NORMAL)
2518 return 0;
2519
2520 /* ALWAYS pack tags */
2521 if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
2522 return 0;
2523
2524 /* Do not pack symbolic or broken refs: */
ffeef642 2525 if ((entry->flag & REF_ISSYMREF) || !entry_resolves_to_object(entry))
7bd9bcf3
MH
2526 return 0;
2527
2528 /* Add a packed ref cache entry equivalent to the loose entry. */
2529 peel_status = peel_entry(entry, 1);
2530 if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
2531 die("internal error peeling reference %s (%s)",
2532 entry->name, oid_to_hex(&entry->u.value.oid));
2533 packed_entry = find_ref(cb->packed_refs, entry->name);
2534 if (packed_entry) {
2535 /* Overwrite existing packed entry with info from loose entry */
2536 packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
2537 oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
2538 } else {
2539 packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
2540 REF_ISPACKED | REF_KNOWS_PEELED, 0);
2541 add_ref(cb->packed_refs, packed_entry);
2542 }
2543 oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
2544
2545 /* Schedule the loose reference for pruning if requested. */
2546 if ((cb->flags & PACK_REFS_PRUNE)) {
96ffc06f
JK
2547 struct ref_to_prune *n;
2548 FLEX_ALLOC_STR(n, name, entry->name);
7bd9bcf3 2549 hashcpy(n->sha1, entry->u.value.oid.hash);
7bd9bcf3
MH
2550 n->next = cb->ref_to_prune;
2551 cb->ref_to_prune = n;
2552 }
2553 return 0;
2554}
2555
2556/*
2557 * Remove empty parents, but spare refs/ and immediate subdirs.
2558 * Note: munges *name.
2559 */
2560static void try_remove_empty_parents(char *name)
2561{
2562 char *p, *q;
2563 int i;
2564 p = name;
2565 for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
2566 while (*p && *p != '/')
2567 p++;
2568 /* tolerate duplicate slashes; see check_refname_format() */
2569 while (*p == '/')
2570 p++;
2571 }
2572 for (q = p; *q; q++)
2573 ;
2574 while (1) {
2575 while (q > p && *q != '/')
2576 q--;
2577 while (q > p && *(q-1) == '/')
2578 q--;
2579 if (q == p)
2580 break;
2581 *q = '\0';
2582 if (rmdir(git_path("%s", name)))
2583 break;
2584 }
2585}
2586
2587/* make sure nobody touched the ref, and unlink */
2588static void prune_ref(struct ref_to_prune *r)
2589{
2590 struct ref_transaction *transaction;
2591 struct strbuf err = STRBUF_INIT;
2592
2593 if (check_refname_format(r->name, 0))
2594 return;
2595
2596 transaction = ref_transaction_begin(&err);
2597 if (!transaction ||
2598 ref_transaction_delete(transaction, r->name, r->sha1,
c52ce248 2599 REF_ISPRUNING | REF_NODEREF, NULL, &err) ||
7bd9bcf3
MH
2600 ref_transaction_commit(transaction, &err)) {
2601 ref_transaction_free(transaction);
2602 error("%s", err.buf);
2603 strbuf_release(&err);
2604 return;
2605 }
2606 ref_transaction_free(transaction);
2607 strbuf_release(&err);
2608 try_remove_empty_parents(r->name);
2609}
2610
2611static void prune_refs(struct ref_to_prune *r)
2612{
2613 while (r) {
2614 prune_ref(r);
2615 r = r->next;
2616 }
2617}
2618
2619int pack_refs(unsigned int flags)
2620{
2621 struct pack_refs_cb_data cbdata;
2622
2623 memset(&cbdata, 0, sizeof(cbdata));
2624 cbdata.flags = flags;
2625
2626 lock_packed_refs(LOCK_DIE_ON_ERROR);
2627 cbdata.packed_refs = get_packed_refs(&ref_cache);
2628
2629 do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
2630 pack_if_possible_fn, &cbdata);
2631
2632 if (commit_packed_refs())
2633 die_errno("unable to overwrite old ref-pack file");
2634
2635 prune_refs(cbdata.ref_to_prune);
2636 return 0;
2637}
2638
2639/*
2640 * Rewrite the packed-refs file, omitting any refs listed in
2641 * 'refnames'. On error, leave packed-refs unchanged, write an error
2642 * message to 'err', and return a nonzero value.
2643 *
2644 * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
2645 */
2646static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
2647{
2648 struct ref_dir *packed;
2649 struct string_list_item *refname;
2650 int ret, needs_repacking = 0, removed = 0;
2651
2652 assert(err);
2653
2654 /* Look for a packed ref */
2655 for_each_string_list_item(refname, refnames) {
2656 if (get_packed_ref(refname->string)) {
2657 needs_repacking = 1;
2658 break;
2659 }
2660 }
2661
2662 /* Avoid locking if we have nothing to do */
2663 if (!needs_repacking)
2664 return 0; /* no refname exists in packed refs */
2665
2666 if (lock_packed_refs(0)) {
2667 unable_to_lock_message(git_path("packed-refs"), errno, err);
2668 return -1;
2669 }
2670 packed = get_packed_refs(&ref_cache);
2671
2672 /* Remove refnames from the cache */
2673 for_each_string_list_item(refname, refnames)
2674 if (remove_entry(packed, refname->string) != -1)
2675 removed = 1;
2676 if (!removed) {
2677 /*
2678 * All packed entries disappeared while we were
2679 * acquiring the lock.
2680 */
2681 rollback_packed_refs();
2682 return 0;
2683 }
2684
2685 /* Write what remains */
2686 ret = commit_packed_refs();
2687 if (ret)
2688 strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
2689 strerror(errno));
2690 return ret;
2691}
2692
2693static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
2694{
2695 assert(err);
2696
2697 if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
2698 /*
2699 * loose. The loose file name is the same as the
2700 * lockfile name, minus ".lock":
2701 */
2702 char *loose_filename = get_locked_file_path(lock->lk);
2703 int res = unlink_or_msg(loose_filename, err);
2704 free(loose_filename);
2705 if (res)
2706 return 1;
2707 }
2708 return 0;
2709}
2710
c5f04ddd 2711int delete_refs(struct string_list *refnames, unsigned int flags)
7bd9bcf3
MH
2712{
2713 struct strbuf err = STRBUF_INIT;
2714 int i, result = 0;
2715
2716 if (!refnames->nr)
2717 return 0;
2718
2719 result = repack_without_refs(refnames, &err);
2720 if (result) {
2721 /*
2722 * If we failed to rewrite the packed-refs file, then
2723 * it is unsafe to try to remove loose refs, because
2724 * doing so might expose an obsolete packed value for
2725 * a reference that might even point at an object that
2726 * has been garbage collected.
2727 */
2728 if (refnames->nr == 1)
2729 error(_("could not delete reference %s: %s"),
2730 refnames->items[0].string, err.buf);
2731 else
2732 error(_("could not delete references: %s"), err.buf);
2733
2734 goto out;
2735 }
2736
2737 for (i = 0; i < refnames->nr; i++) {
2738 const char *refname = refnames->items[i].string;
2739
c5f04ddd 2740 if (delete_ref(refname, NULL, flags))
7bd9bcf3
MH
2741 result |= error(_("could not remove reference %s"), refname);
2742 }
2743
2744out:
2745 strbuf_release(&err);
2746 return result;
2747}
2748
2749/*
2750 * People using contrib's git-new-workdir have .git/logs/refs ->
2751 * /some/other/path/.git/logs/refs, and that may live on another device.
2752 *
2753 * IOW, to avoid cross device rename errors, the temporary renamed log must
2754 * live into logs/refs.
2755 */
2756#define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
2757
2758static int rename_tmp_log(const char *newrefname)
2759{
2760 int attempts_remaining = 4;
2761 struct strbuf path = STRBUF_INIT;
2762 int ret = -1;
2763
2764 retry:
2765 strbuf_reset(&path);
2766 strbuf_git_path(&path, "logs/%s", newrefname);
2767 switch (safe_create_leading_directories_const(path.buf)) {
2768 case SCLD_OK:
2769 break; /* success */
2770 case SCLD_VANISHED:
2771 if (--attempts_remaining > 0)
2772 goto retry;
2773 /* fall through */
2774 default:
2775 error("unable to create directory for %s", newrefname);
2776 goto out;
2777 }
2778
2779 if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
2780 if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
2781 /*
2782 * rename(a, b) when b is an existing
2783 * directory ought to result in ISDIR, but
2784 * Solaris 5.8 gives ENOTDIR. Sheesh.
2785 */
2786 if (remove_empty_directories(&path)) {
2787 error("Directory not empty: logs/%s", newrefname);
2788 goto out;
2789 }
2790 goto retry;
2791 } else if (errno == ENOENT && --attempts_remaining > 0) {
2792 /*
2793 * Maybe another process just deleted one of
2794 * the directories in the path to newrefname.
2795 * Try again from the beginning.
2796 */
2797 goto retry;
2798 } else {
2799 error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
2800 newrefname, strerror(errno));
2801 goto out;
2802 }
2803 }
2804 ret = 0;
2805out:
2806 strbuf_release(&path);
2807 return ret;
2808}
2809
2810int verify_refname_available(const char *newname,
3a8af7be
MH
2811 const struct string_list *extras,
2812 const struct string_list *skip,
7bd9bcf3
MH
2813 struct strbuf *err)
2814{
2815 struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
2816 struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
2817
2818 if (verify_refname_available_dir(newname, extras, skip,
2819 packed_refs, err) ||
2820 verify_refname_available_dir(newname, extras, skip,
2821 loose_refs, err))
2822 return -1;
2823
2824 return 0;
2825}
2826
7bd9bcf3
MH
2827static int write_ref_to_lockfile(struct ref_lock *lock,
2828 const unsigned char *sha1, struct strbuf *err);
2829static int commit_ref_update(struct ref_lock *lock,
2830 const unsigned char *sha1, const char *logmsg,
5d9b2de4 2831 struct strbuf *err);
7bd9bcf3
MH
2832
2833int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
2834{
2835 unsigned char sha1[20], orig_sha1[20];
2836 int flag = 0, logmoved = 0;
2837 struct ref_lock *lock;
2838 struct stat loginfo;
2839 int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
7bd9bcf3
MH
2840 struct strbuf err = STRBUF_INIT;
2841
2842 if (log && S_ISLNK(loginfo.st_mode))
2843 return error("reflog for %s is a symlink", oldrefname);
2844
12fd3496
DT
2845 if (!resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2846 orig_sha1, &flag))
e711b1af
MH
2847 return error("refname %s not found", oldrefname);
2848
7bd9bcf3
MH
2849 if (flag & REF_ISSYMREF)
2850 return error("refname %s is a symbolic ref, renaming it is not supported",
2851 oldrefname);
7bd9bcf3
MH
2852 if (!rename_ref_available(oldrefname, newrefname))
2853 return 1;
2854
2855 if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
2856 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
2857 oldrefname, strerror(errno));
2858
2859 if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
2860 error("unable to delete old %s", oldrefname);
2861 goto rollback;
2862 }
2863
12fd3496
DT
2864 /*
2865 * Since we are doing a shallow lookup, sha1 is not the
2866 * correct value to pass to delete_ref as old_sha1. But that
2867 * doesn't matter, because an old_sha1 check wouldn't add to
2868 * the safety anyway; we want to delete the reference whatever
2869 * its current value.
2870 */
2871 if (!read_ref_full(newrefname, RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
2872 sha1, NULL) &&
2873 delete_ref(newrefname, NULL, REF_NODEREF)) {
7bd9bcf3
MH
2874 if (errno==EISDIR) {
2875 struct strbuf path = STRBUF_INIT;
2876 int result;
2877
2878 strbuf_git_path(&path, "%s", newrefname);
2879 result = remove_empty_directories(&path);
2880 strbuf_release(&path);
2881
2882 if (result) {
2883 error("Directory not empty: %s", newrefname);
2884 goto rollback;
2885 }
2886 } else {
2887 error("unable to delete existing %s", newrefname);
2888 goto rollback;
2889 }
2890 }
2891
2892 if (log && rename_tmp_log(newrefname))
2893 goto rollback;
2894
2895 logmoved = log;
2896
12fd3496
DT
2897 lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, REF_NODEREF,
2898 NULL, &err);
7bd9bcf3
MH
2899 if (!lock) {
2900 error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
2901 strbuf_release(&err);
2902 goto rollback;
2903 }
2904 hashcpy(lock->old_oid.hash, orig_sha1);
2905
2906 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2907 commit_ref_update(lock, orig_sha1, logmsg, &err)) {
7bd9bcf3
MH
2908 error("unable to write current sha1 into %s: %s", newrefname, err.buf);
2909 strbuf_release(&err);
2910 goto rollback;
2911 }
2912
2913 return 0;
2914
2915 rollback:
12fd3496
DT
2916 lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, REF_NODEREF,
2917 NULL, &err);
7bd9bcf3
MH
2918 if (!lock) {
2919 error("unable to lock %s for rollback: %s", oldrefname, err.buf);
2920 strbuf_release(&err);
2921 goto rollbacklog;
2922 }
2923
2924 flag = log_all_ref_updates;
2925 log_all_ref_updates = 0;
2926 if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
5d9b2de4 2927 commit_ref_update(lock, orig_sha1, NULL, &err)) {
7bd9bcf3
MH
2928 error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
2929 strbuf_release(&err);
2930 }
2931 log_all_ref_updates = flag;
2932
2933 rollbacklog:
2934 if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
2935 error("unable to restore logfile %s from %s: %s",
2936 oldrefname, newrefname, strerror(errno));
2937 if (!logmoved && log &&
2938 rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
2939 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
2940 oldrefname, strerror(errno));
2941
2942 return 1;
2943}
2944
2945static int close_ref(struct ref_lock *lock)
2946{
2947 if (close_lock_file(lock->lk))
2948 return -1;
2949 return 0;
2950}
2951
2952static int commit_ref(struct ref_lock *lock)
2953{
5387c0d8
MH
2954 char *path = get_locked_file_path(lock->lk);
2955 struct stat st;
2956
2957 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
2958 /*
2959 * There is a directory at the path we want to rename
2960 * the lockfile to. Hopefully it is empty; try to
2961 * delete it.
2962 */
2963 size_t len = strlen(path);
2964 struct strbuf sb_path = STRBUF_INIT;
2965
2966 strbuf_attach(&sb_path, path, len, len);
2967
2968 /*
2969 * If this fails, commit_lock_file() will also fail
2970 * and will report the problem.
2971 */
2972 remove_empty_directories(&sb_path);
2973 strbuf_release(&sb_path);
2974 } else {
2975 free(path);
2976 }
2977
7bd9bcf3
MH
2978 if (commit_lock_file(lock->lk))
2979 return -1;
2980 return 0;
2981}
2982
2983/*
2984 * Create a reflog for a ref. If force_create = 0, the reflog will
2985 * only be created for certain refs (those for which
2986 * should_autocreate_reflog returns non-zero. Otherwise, create it
2987 * regardless of the ref name. Fill in *err and return -1 on failure.
2988 */
2989static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
2990{
2991 int logfd, oflags = O_APPEND | O_WRONLY;
2992
2993 strbuf_git_path(logfile, "logs/%s", refname);
2994 if (force_create || should_autocreate_reflog(refname)) {
2995 if (safe_create_leading_directories(logfile->buf) < 0) {
0568c8e9 2996 strbuf_addf(err, "unable to create directory for '%s': "
7bd9bcf3
MH
2997 "%s", logfile->buf, strerror(errno));
2998 return -1;
2999 }
3000 oflags |= O_CREAT;
3001 }
3002
3003 logfd = open(logfile->buf, oflags, 0666);
3004 if (logfd < 0) {
3005 if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
3006 return 0;
3007
3008 if (errno == EISDIR) {
3009 if (remove_empty_directories(logfile)) {
0568c8e9 3010 strbuf_addf(err, "there are still logs under "
7bd9bcf3
MH
3011 "'%s'", logfile->buf);
3012 return -1;
3013 }
3014 logfd = open(logfile->buf, oflags, 0666);
3015 }
3016
3017 if (logfd < 0) {
0568c8e9 3018 strbuf_addf(err, "unable to append to '%s': %s",
7bd9bcf3
MH
3019 logfile->buf, strerror(errno));
3020 return -1;
3021 }
3022 }
3023
3024 adjust_shared_perm(logfile->buf);
3025 close(logfd);
3026 return 0;
3027}
3028
3029
3030int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
3031{
3032 int ret;
3033 struct strbuf sb = STRBUF_INIT;
3034
3035 ret = log_ref_setup(refname, &sb, err, force_create);
3036 strbuf_release(&sb);
3037 return ret;
3038}
3039
3040static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
3041 const unsigned char *new_sha1,
3042 const char *committer, const char *msg)
3043{
3044 int msglen, written;
3045 unsigned maxlen, len;
3046 char *logrec;
3047
3048 msglen = msg ? strlen(msg) : 0;
3049 maxlen = strlen(committer) + msglen + 100;
3050 logrec = xmalloc(maxlen);
3051 len = xsnprintf(logrec, maxlen, "%s %s %s\n",
3052 sha1_to_hex(old_sha1),
3053 sha1_to_hex(new_sha1),
3054 committer);
3055 if (msglen)
3056 len += copy_reflog_msg(logrec + len - 1, msg) - 1;
3057
3058 written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
3059 free(logrec);
3060 if (written != len)
3061 return -1;
3062
3063 return 0;
3064}
3065
3066static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
3067 const unsigned char *new_sha1, const char *msg,
3068 struct strbuf *logfile, int flags,
3069 struct strbuf *err)
3070{
3071 int logfd, result, oflags = O_APPEND | O_WRONLY;
3072
3073 if (log_all_ref_updates < 0)
3074 log_all_ref_updates = !is_bare_repository();
3075
3076 result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
3077
3078 if (result)
3079 return result;
3080
3081 logfd = open(logfile->buf, oflags);
3082 if (logfd < 0)
3083 return 0;
3084 result = log_ref_write_fd(logfd, old_sha1, new_sha1,
3085 git_committer_info(0), msg);
3086 if (result) {
0568c8e9 3087 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
3088 strerror(errno));
3089 close(logfd);
3090 return -1;
3091 }
3092 if (close(logfd)) {
0568c8e9 3093 strbuf_addf(err, "unable to append to '%s': %s", logfile->buf,
7bd9bcf3
MH
3094 strerror(errno));
3095 return -1;
3096 }
3097 return 0;
3098}
3099
3100static int log_ref_write(const char *refname, const unsigned char *old_sha1,
3101 const unsigned char *new_sha1, const char *msg,
3102 int flags, struct strbuf *err)
5f3c3a4e
DT
3103{
3104 return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
3105 err);
3106}
3107
3108int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
3109 const unsigned char *new_sha1, const char *msg,
3110 int flags, struct strbuf *err)
7bd9bcf3
MH
3111{
3112 struct strbuf sb = STRBUF_INIT;
3113 int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
3114 err);
3115 strbuf_release(&sb);
3116 return ret;
3117}
3118
3119/*
3120 * Write sha1 into the open lockfile, then close the lockfile. On
3121 * errors, rollback the lockfile, fill in *err and
3122 * return -1.
3123 */
3124static int write_ref_to_lockfile(struct ref_lock *lock,
3125 const unsigned char *sha1, struct strbuf *err)
3126{
3127 static char term = '\n';
3128 struct object *o;
3129 int fd;
3130
3131 o = parse_object(sha1);
3132 if (!o) {
3133 strbuf_addf(err,
0568c8e9 3134 "trying to write ref '%s' with nonexistent object %s",
7bd9bcf3
MH
3135 lock->ref_name, sha1_to_hex(sha1));
3136 unlock_ref(lock);
3137 return -1;
3138 }
3139 if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
3140 strbuf_addf(err,
0568c8e9 3141 "trying to write non-commit object %s to branch '%s'",
7bd9bcf3
MH
3142 sha1_to_hex(sha1), lock->ref_name);
3143 unlock_ref(lock);
3144 return -1;
3145 }
3146 fd = get_lock_file_fd(lock->lk);
3147 if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
3148 write_in_full(fd, &term, 1) != 1 ||
3149 close_ref(lock) < 0) {
3150 strbuf_addf(err,
0568c8e9 3151 "couldn't write '%s'", get_lock_file_path(lock->lk));
7bd9bcf3
MH
3152 unlock_ref(lock);
3153 return -1;
3154 }
3155 return 0;
3156}
3157
3158/*
3159 * Commit a change to a loose reference that has already been written
3160 * to the loose reference lockfile. Also update the reflogs if
3161 * necessary, using the specified lockmsg (which can be NULL).
3162 */
3163static int commit_ref_update(struct ref_lock *lock,
3164 const unsigned char *sha1, const char *logmsg,
5d9b2de4 3165 struct strbuf *err)
7bd9bcf3
MH
3166{
3167 clear_loose_ref_cache(&ref_cache);
7a418f3a 3168 if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, 0, err)) {
7bd9bcf3 3169 char *old_msg = strbuf_detach(err, NULL);
0568c8e9 3170 strbuf_addf(err, "cannot update the ref '%s': %s",
7bd9bcf3
MH
3171 lock->ref_name, old_msg);
3172 free(old_msg);
3173 unlock_ref(lock);
3174 return -1;
3175 }
7a418f3a
MH
3176
3177 if (strcmp(lock->ref_name, "HEAD") != 0) {
7bd9bcf3
MH
3178 /*
3179 * Special hack: If a branch is updated directly and HEAD
3180 * points to it (may happen on the remote side of a push
3181 * for example) then logically the HEAD reflog should be
3182 * updated too.
3183 * A generic solution implies reverse symref information,
3184 * but finding all symrefs pointing to the given branch
3185 * would be rather costly for this rare event (the direct
3186 * update of a branch) to be worth it. So let's cheat and
3187 * check with HEAD only which should cover 99% of all usage
3188 * scenarios (even 100% of the default ones).
3189 */
3190 unsigned char head_sha1[20];
3191 int head_flag;
3192 const char *head_ref;
7a418f3a 3193
7bd9bcf3
MH
3194 head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
3195 head_sha1, &head_flag);
3196 if (head_ref && (head_flag & REF_ISSYMREF) &&
3197 !strcmp(head_ref, lock->ref_name)) {
3198 struct strbuf log_err = STRBUF_INIT;
3199 if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
3200 logmsg, 0, &log_err)) {
3201 error("%s", log_err.buf);
3202 strbuf_release(&log_err);
3203 }
3204 }
3205 }
7a418f3a 3206
5d9b2de4 3207 if (commit_ref(lock)) {
0568c8e9 3208 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
7bd9bcf3
MH
3209 unlock_ref(lock);
3210 return -1;
3211 }
3212
3213 unlock_ref(lock);
3214 return 0;
3215}
3216
370e5ad6 3217static int create_ref_symlink(struct ref_lock *lock, const char *target)
7bd9bcf3 3218{
370e5ad6 3219 int ret = -1;
7bd9bcf3 3220#ifndef NO_SYMLINK_HEAD
370e5ad6
JK
3221 char *ref_path = get_locked_file_path(lock->lk);
3222 unlink(ref_path);
3223 ret = symlink(target, ref_path);
3224 free(ref_path);
3225
3226 if (ret)
7bd9bcf3 3227 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
7bd9bcf3 3228#endif
370e5ad6
JK
3229 return ret;
3230}
7bd9bcf3 3231
370e5ad6
JK
3232static void update_symref_reflog(struct ref_lock *lock, const char *refname,
3233 const char *target, const char *logmsg)
3234{
3235 struct strbuf err = STRBUF_INIT;
3236 unsigned char new_sha1[20];
b9badadd 3237 if (logmsg && !read_ref(target, new_sha1) &&
370e5ad6 3238 log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
7bd9bcf3
MH
3239 error("%s", err.buf);
3240 strbuf_release(&err);
3241 }
370e5ad6 3242}
7bd9bcf3 3243
370e5ad6
JK
3244static int create_symref_locked(struct ref_lock *lock, const char *refname,
3245 const char *target, const char *logmsg)
3246{
3247 if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
3248 update_symref_reflog(lock, refname, target, logmsg);
3249 return 0;
3250 }
3251
3252 if (!fdopen_lock_file(lock->lk, "w"))
3253 return error("unable to fdopen %s: %s",
3254 lock->lk->tempfile.filename.buf, strerror(errno));
3255
396da8f7
JK
3256 update_symref_reflog(lock, refname, target, logmsg);
3257
370e5ad6
JK
3258 /* no error check; commit_ref will check ferror */
3259 fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
3260 if (commit_ref(lock) < 0)
3261 return error("unable to write symref for %s: %s", refname,
3262 strerror(errno));
7bd9bcf3
MH
3263 return 0;
3264}
3265
370e5ad6
JK
3266int create_symref(const char *refname, const char *target, const char *logmsg)
3267{
3268 struct strbuf err = STRBUF_INIT;
3269 struct ref_lock *lock;
3270 int ret;
3271
3272 lock = lock_ref_sha1_basic(refname, NULL, NULL, NULL, REF_NODEREF, NULL,
3273 &err);
3274 if (!lock) {
3275 error("%s", err.buf);
3276 strbuf_release(&err);
3277 return -1;
3278 }
3279
3280 ret = create_symref_locked(lock, refname, target, logmsg);
3281 unlock_ref(lock);
3282 return ret;
3283}
3284
2233066e
KY
3285int set_worktree_head_symref(const char *gitdir, const char *target)
3286{
3287 static struct lock_file head_lock;
3288 struct ref_lock *lock;
2233066e
KY
3289 struct strbuf head_path = STRBUF_INIT;
3290 const char *head_rel;
3291 int ret;
3292
3293 strbuf_addf(&head_path, "%s/HEAD", absolute_path(gitdir));
3294 if (hold_lock_file_for_update(&head_lock, head_path.buf,
3295 LOCK_NO_DEREF) < 0) {
18eb3a9c
KY
3296 struct strbuf err = STRBUF_INIT;
3297 unable_to_lock_message(head_path.buf, errno, &err);
2233066e
KY
3298 error("%s", err.buf);
3299 strbuf_release(&err);
3300 strbuf_release(&head_path);
3301 return -1;
3302 }
3303
3304 /* head_rel will be "HEAD" for the main tree, "worktrees/wt/HEAD" for
3305 linked trees */
3306 head_rel = remove_leading_path(head_path.buf,
3307 absolute_path(get_git_common_dir()));
3308 /* to make use of create_symref_locked(), initialize ref_lock */
3309 lock = xcalloc(1, sizeof(struct ref_lock));
3310 lock->lk = &head_lock;
3311 lock->ref_name = xstrdup(head_rel);
2233066e
KY
3312
3313 ret = create_symref_locked(lock, head_rel, target, NULL);
3314
3315 unlock_ref(lock); /* will free lock */
3316 strbuf_release(&head_path);
3317 return ret;
3318}
3319
7bd9bcf3
MH
3320int reflog_exists(const char *refname)
3321{
3322 struct stat st;
3323
3324 return !lstat(git_path("logs/%s", refname), &st) &&
3325 S_ISREG(st.st_mode);
3326}
3327
3328int delete_reflog(const char *refname)
3329{
3330 return remove_path(git_path("logs/%s", refname));
3331}
3332
3333static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
3334{
3335 unsigned char osha1[20], nsha1[20];
3336 char *email_end, *message;
3337 unsigned long timestamp;
3338 int tz;
3339
3340 /* old SP new SP name <email> SP time TAB msg LF */
3341 if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
3342 get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
3343 get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
3344 !(email_end = strchr(sb->buf + 82, '>')) ||
3345 email_end[1] != ' ' ||
3346 !(timestamp = strtoul(email_end + 2, &message, 10)) ||
3347 !message || message[0] != ' ' ||
3348 (message[1] != '+' && message[1] != '-') ||
3349 !isdigit(message[2]) || !isdigit(message[3]) ||
3350 !isdigit(message[4]) || !isdigit(message[5]))
3351 return 0; /* corrupt? */
3352 email_end[1] = '\0';
3353 tz = strtol(message + 1, NULL, 10);
3354 if (message[6] != '\t')
3355 message += 6;
3356 else
3357 message += 7;
3358 return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
3359}
3360
3361static char *find_beginning_of_line(char *bob, char *scan)
3362{
3363 while (bob < scan && *(--scan) != '\n')
3364 ; /* keep scanning backwards */
3365 /*
3366 * Return either beginning of the buffer, or LF at the end of
3367 * the previous line.
3368 */
3369 return scan;
3370}
3371
3372int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3373{
3374 struct strbuf sb = STRBUF_INIT;
3375 FILE *logfp;
3376 long pos;
3377 int ret = 0, at_tail = 1;
3378
3379 logfp = fopen(git_path("logs/%s", refname), "r");
3380 if (!logfp)
3381 return -1;
3382
3383 /* Jump to the end */
3384 if (fseek(logfp, 0, SEEK_END) < 0)
3385 return error("cannot seek back reflog for %s: %s",
3386 refname, strerror(errno));
3387 pos = ftell(logfp);
3388 while (!ret && 0 < pos) {
3389 int cnt;
3390 size_t nread;
3391 char buf[BUFSIZ];
3392 char *endp, *scanp;
3393
3394 /* Fill next block from the end */
3395 cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
3396 if (fseek(logfp, pos - cnt, SEEK_SET))
3397 return error("cannot seek back reflog for %s: %s",
3398 refname, strerror(errno));
3399 nread = fread(buf, cnt, 1, logfp);
3400 if (nread != 1)
3401 return error("cannot read %d bytes from reflog for %s: %s",
3402 cnt, refname, strerror(errno));
3403 pos -= cnt;
3404
3405 scanp = endp = buf + cnt;
3406 if (at_tail && scanp[-1] == '\n')
3407 /* Looking at the final LF at the end of the file */
3408 scanp--;
3409 at_tail = 0;
3410
3411 while (buf < scanp) {
3412 /*
3413 * terminating LF of the previous line, or the beginning
3414 * of the buffer.
3415 */
3416 char *bp;
3417
3418 bp = find_beginning_of_line(buf, scanp);
3419
3420 if (*bp == '\n') {
3421 /*
3422 * The newline is the end of the previous line,
3423 * so we know we have complete line starting
3424 * at (bp + 1). Prefix it onto any prior data
3425 * we collected for the line and process it.
3426 */
3427 strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
3428 scanp = bp;
3429 endp = bp + 1;
3430 ret = show_one_reflog_ent(&sb, fn, cb_data);
3431 strbuf_reset(&sb);
3432 if (ret)
3433 break;
3434 } else if (!pos) {
3435 /*
3436 * We are at the start of the buffer, and the
3437 * start of the file; there is no previous
3438 * line, and we have everything for this one.
3439 * Process it, and we can end the loop.
3440 */
3441 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3442 ret = show_one_reflog_ent(&sb, fn, cb_data);
3443 strbuf_reset(&sb);
3444 break;
3445 }
3446
3447 if (bp == buf) {
3448 /*
3449 * We are at the start of the buffer, and there
3450 * is more file to read backwards. Which means
3451 * we are in the middle of a line. Note that we
3452 * may get here even if *bp was a newline; that
3453 * just means we are at the exact end of the
3454 * previous line, rather than some spot in the
3455 * middle.
3456 *
3457 * Save away what we have to be combined with
3458 * the data from the next read.
3459 */
3460 strbuf_splice(&sb, 0, 0, buf, endp - buf);
3461 break;
3462 }
3463 }
3464
3465 }
3466 if (!ret && sb.len)
3467 die("BUG: reverse reflog parser had leftover data");
3468
3469 fclose(logfp);
3470 strbuf_release(&sb);
3471 return ret;
3472}
3473
3474int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
3475{
3476 FILE *logfp;
3477 struct strbuf sb = STRBUF_INIT;
3478 int ret = 0;
3479
3480 logfp = fopen(git_path("logs/%s", refname), "r");
3481 if (!logfp)
3482 return -1;
3483
3484 while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
3485 ret = show_one_reflog_ent(&sb, fn, cb_data);
3486 fclose(logfp);
3487 strbuf_release(&sb);
3488 return ret;
3489}
3490/*
3491 * Call fn for each reflog in the namespace indicated by name. name
3492 * must be empty or end with '/'. Name will be used as a scratch
3493 * space, but its contents will be restored before return.
3494 */
3495static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
3496{
3497 DIR *d = opendir(git_path("logs/%s", name->buf));
3498 int retval = 0;
3499 struct dirent *de;
3500 int oldlen = name->len;
3501
3502 if (!d)
3503 return name->len ? errno : 0;
3504
3505 while ((de = readdir(d)) != NULL) {
3506 struct stat st;
3507
3508 if (de->d_name[0] == '.')
3509 continue;
3510 if (ends_with(de->d_name, ".lock"))
3511 continue;
3512 strbuf_addstr(name, de->d_name);
3513 if (stat(git_path("logs/%s", name->buf), &st) < 0) {
3514 ; /* silently ignore */
3515 } else {
3516 if (S_ISDIR(st.st_mode)) {
3517 strbuf_addch(name, '/');
3518 retval = do_for_each_reflog(name, fn, cb_data);
3519 } else {
3520 struct object_id oid;
3521
3522 if (read_ref_full(name->buf, 0, oid.hash, NULL))
3523 retval = error("bad ref for %s", name->buf);
3524 else
3525 retval = fn(name->buf, &oid, 0, cb_data);
3526 }
3527 if (retval)
3528 break;
3529 }
3530 strbuf_setlen(name, oldlen);
3531 }
3532 closedir(d);
3533 return retval;
3534}
3535
3536int for_each_reflog(each_ref_fn fn, void *cb_data)
3537{
3538 int retval;
3539 struct strbuf name;
3540 strbuf_init(&name, PATH_MAX);
3541 retval = do_for_each_reflog(&name, fn, cb_data);
3542 strbuf_release(&name);
3543 return retval;
3544}
3545
3546static int ref_update_reject_duplicates(struct string_list *refnames,
3547 struct strbuf *err)
3548{
3549 int i, n = refnames->nr;
3550
3551 assert(err);
3552
3553 for (i = 1; i < n; i++)
3554 if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
3555 strbuf_addf(err,
0568c8e9 3556 "multiple updates for ref '%s' not allowed.",
7bd9bcf3
MH
3557 refnames->items[i].string);
3558 return 1;
3559 }
3560 return 0;
3561}
3562
165056b2 3563/*
92b1551b
MH
3564 * If update is a direct update of head_ref (the reference pointed to
3565 * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
3566 */
3567static int split_head_update(struct ref_update *update,
3568 struct ref_transaction *transaction,
3569 const char *head_ref,
3570 struct string_list *affected_refnames,
3571 struct strbuf *err)
3572{
3573 struct string_list_item *item;
3574 struct ref_update *new_update;
3575
3576 if ((update->flags & REF_LOG_ONLY) ||
3577 (update->flags & REF_ISPRUNING) ||
3578 (update->flags & REF_UPDATE_VIA_HEAD))
3579 return 0;
3580
3581 if (strcmp(update->refname, head_ref))
3582 return 0;
3583
3584 /*
3585 * First make sure that HEAD is not already in the
3586 * transaction. This insertion is O(N) in the transaction
3587 * size, but it happens at most once per transaction.
3588 */
3589 item = string_list_insert(affected_refnames, "HEAD");
3590 if (item->util) {
3591 /* An entry already existed */
3592 strbuf_addf(err,
3593 "multiple updates for 'HEAD' (including one "
3594 "via its referent '%s') are not allowed",
3595 update->refname);
3596 return TRANSACTION_NAME_CONFLICT;
3597 }
3598
3599 new_update = ref_transaction_add_update(
3600 transaction, "HEAD",
3601 update->flags | REF_LOG_ONLY | REF_NODEREF,
3602 update->new_sha1, update->old_sha1,
3603 update->msg);
3604
3605 item->util = new_update;
3606
3607 return 0;
3608}
3609
3610/*
3611 * update is for a symref that points at referent and doesn't have
3612 * REF_NODEREF set. Split it into two updates:
3613 * - The original update, but with REF_LOG_ONLY and REF_NODEREF set
3614 * - A new, separate update for the referent reference
3615 * Note that the new update will itself be subject to splitting when
3616 * the iteration gets to it.
3617 */
3618static int split_symref_update(struct ref_update *update,
3619 const char *referent,
3620 struct ref_transaction *transaction,
3621 struct string_list *affected_refnames,
3622 struct strbuf *err)
3623{
3624 struct string_list_item *item;
3625 struct ref_update *new_update;
3626 unsigned int new_flags;
3627
3628 /*
3629 * First make sure that referent is not already in the
3630 * transaction. This insertion is O(N) in the transaction
3631 * size, but it happens at most once per symref in a
3632 * transaction.
3633 */
3634 item = string_list_insert(affected_refnames, referent);
3635 if (item->util) {
3636 /* An entry already existed */
3637 strbuf_addf(err,
3638 "multiple updates for '%s' (including one "
3639 "via symref '%s') are not allowed",
3640 referent, update->refname);
3641 return TRANSACTION_NAME_CONFLICT;
3642 }
3643
3644 new_flags = update->flags;
3645 if (!strcmp(update->refname, "HEAD")) {
3646 /*
3647 * Record that the new update came via HEAD, so that
3648 * when we process it, split_head_update() doesn't try
3649 * to add another reflog update for HEAD. Note that
3650 * this bit will be propagated if the new_update
3651 * itself needs to be split.
3652 */
3653 new_flags |= REF_UPDATE_VIA_HEAD;
3654 }
3655
3656 new_update = ref_transaction_add_update(
3657 transaction, referent, new_flags,
3658 update->new_sha1, update->old_sha1,
3659 update->msg);
3660
6e30b2f6
MH
3661 new_update->parent_update = update;
3662
3663 /*
3664 * Change the symbolic ref update to log only. Also, it
3665 * doesn't need to check its old SHA-1 value, as that will be
3666 * done when new_update is processed.
3667 */
92b1551b 3668 update->flags |= REF_LOG_ONLY | REF_NODEREF;
6e30b2f6 3669 update->flags &= ~REF_HAVE_OLD;
92b1551b
MH
3670
3671 item->util = new_update;
3672
3673 return 0;
3674}
3675
6e30b2f6
MH
3676/*
3677 * Return the refname under which update was originally requested.
3678 */
3679static const char *original_update_refname(struct ref_update *update)
3680{
3681 while (update->parent_update)
3682 update = update->parent_update;
3683
3684 return update->refname;
3685}
3686
92b1551b
MH
3687/*
3688 * Prepare for carrying out update:
3689 * - Lock the reference referred to by update.
3690 * - Read the reference under lock.
3691 * - Check that its old SHA-1 value (if specified) is correct, and in
3692 * any case record it in update->lock->old_oid for later use when
3693 * writing the reflog.
3694 * - If it is a symref update without REF_NODEREF, split it up into a
3695 * REF_LOG_ONLY update of the symref and add a separate update for
3696 * the referent to transaction.
3697 * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
3698 * update of HEAD.
165056b2
MH
3699 */
3700static int lock_ref_for_update(struct ref_update *update,
3701 struct ref_transaction *transaction,
92b1551b 3702 const char *head_ref,
165056b2
MH
3703 struct string_list *affected_refnames,
3704 struct strbuf *err)
3705{
92b1551b
MH
3706 struct strbuf referent = STRBUF_INIT;
3707 int mustexist = (update->flags & REF_HAVE_OLD) &&
3708 !is_null_sha1(update->old_sha1);
165056b2 3709 int ret;
92b1551b 3710 struct ref_lock *lock;
165056b2 3711
92b1551b 3712 if ((update->flags & REF_HAVE_NEW) && is_null_sha1(update->new_sha1))
165056b2 3713 update->flags |= REF_DELETING;
92b1551b
MH
3714
3715 if (head_ref) {
3716 ret = split_head_update(update, transaction, head_ref,
3717 affected_refnames, err);
3718 if (ret)
3719 return ret;
3720 }
3721
3722 ret = lock_raw_ref(update->refname, mustexist,
3723 affected_refnames, NULL,
3724 &update->lock, &referent,
3725 &update->type, err);
3726
3727 if (ret) {
165056b2
MH
3728 char *reason;
3729
165056b2
MH
3730 reason = strbuf_detach(err, NULL);
3731 strbuf_addf(err, "cannot lock ref '%s': %s",
3732 update->refname, reason);
3733 free(reason);
3734 return ret;
3735 }
92b1551b
MH
3736
3737 lock = update->lock;
3738
8169d0d0 3739 if (update->type & REF_ISSYMREF) {
6e30b2f6
MH
3740 if (update->flags & REF_NODEREF) {
3741 /*
3742 * We won't be reading the referent as part of
3743 * the transaction, so we have to read it here
3744 * to record and possibly check old_sha1:
3745 */
3746 if (read_ref_full(update->refname,
3747 mustexist ? RESOLVE_REF_READING : 0,
3748 lock->old_oid.hash, NULL)) {
3749 if (update->flags & REF_HAVE_OLD) {
3750 strbuf_addf(err, "cannot lock ref '%s': "
3751 "can't resolve old value",
3752 update->refname);
3753 return TRANSACTION_GENERIC_ERROR;
3754 } else {
3755 hashclr(lock->old_oid.hash);
3756 }
3757 }
3758 if ((update->flags & REF_HAVE_OLD) &&
3759 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3760 strbuf_addf(err, "cannot lock ref '%s': "
3761 "is at %s but expected %s",
3762 update->refname,
3763 sha1_to_hex(lock->old_oid.hash),
3764 sha1_to_hex(update->old_sha1));
8169d0d0 3765 return TRANSACTION_GENERIC_ERROR;
8169d0d0 3766 }
92b1551b 3767
6e30b2f6
MH
3768 } else {
3769 /*
3770 * Create a new update for the reference this
3771 * symref is pointing at. Also, we will record
3772 * and verify old_sha1 for this update as part
3773 * of processing the split-off update, so we
3774 * don't have to do it here.
3775 */
92b1551b
MH
3776 ret = split_symref_update(update, referent.buf, transaction,
3777 affected_refnames, err);
3778 if (ret)
3779 return ret;
3780 }
6e30b2f6
MH
3781 } else {
3782 struct ref_update *parent_update;
8169d0d0 3783
6e30b2f6
MH
3784 /*
3785 * If this update is happening indirectly because of a
3786 * symref update, record the old SHA-1 in the parent
3787 * update:
3788 */
3789 for (parent_update = update->parent_update;
3790 parent_update;
3791 parent_update = parent_update->parent_update) {
3792 oidcpy(&parent_update->lock->old_oid, &lock->old_oid);
3793 }
3794
3795 if ((update->flags & REF_HAVE_OLD) &&
3796 hashcmp(lock->old_oid.hash, update->old_sha1)) {
3797 if (is_null_sha1(update->old_sha1))
3798 strbuf_addf(err, "cannot lock ref '%s': reference already exists",
3799 original_update_refname(update));
3800 else
3801 strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s",
3802 original_update_refname(update),
3803 sha1_to_hex(lock->old_oid.hash),
3804 sha1_to_hex(update->old_sha1));
3805
3806 return TRANSACTION_GENERIC_ERROR;
3807 }
92b1551b
MH
3808 }
3809
165056b2
MH
3810 if ((update->flags & REF_HAVE_NEW) &&
3811 !(update->flags & REF_DELETING) &&
3812 !(update->flags & REF_LOG_ONLY)) {
92b1551b
MH
3813 if (!(update->type & REF_ISSYMREF) &&
3814 !hashcmp(lock->old_oid.hash, update->new_sha1)) {
165056b2
MH
3815 /*
3816 * The reference already has the desired
3817 * value, so we don't need to write it.
3818 */
92b1551b 3819 } else if (write_ref_to_lockfile(lock, update->new_sha1,
165056b2
MH
3820 err)) {
3821 char *write_err = strbuf_detach(err, NULL);
3822
3823 /*
3824 * The lock was freed upon failure of
3825 * write_ref_to_lockfile():
3826 */
3827 update->lock = NULL;
3828 strbuf_addf(err,
3829 "cannot update the ref '%s': %s",
3830 update->refname, write_err);
3831 free(write_err);
3832 return TRANSACTION_GENERIC_ERROR;
3833 } else {
3834 update->flags |= REF_NEEDS_COMMIT;
3835 }
3836 }
3837 if (!(update->flags & REF_NEEDS_COMMIT)) {
3838 /*
3839 * We didn't call write_ref_to_lockfile(), so
3840 * the lockfile is still open. Close it to
3841 * free up the file descriptor:
3842 */
92b1551b 3843 if (close_ref(lock)) {
165056b2
MH
3844 strbuf_addf(err, "couldn't close '%s.lock'",
3845 update->refname);
3846 return TRANSACTION_GENERIC_ERROR;
3847 }
3848 }
3849 return 0;
3850}
3851
7bd9bcf3
MH
3852int ref_transaction_commit(struct ref_transaction *transaction,
3853 struct strbuf *err)
3854{
3855 int ret = 0, i;
7bd9bcf3
MH
3856 struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
3857 struct string_list_item *ref_to_delete;
3858 struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
92b1551b
MH
3859 char *head_ref = NULL;
3860 int head_type;
3861 struct object_id head_oid;
7bd9bcf3
MH
3862
3863 assert(err);
3864
3865 if (transaction->state != REF_TRANSACTION_OPEN)
3866 die("BUG: commit called for transaction that is not open");
3867
efe47281 3868 if (!transaction->nr) {
7bd9bcf3
MH
3869 transaction->state = REF_TRANSACTION_CLOSED;
3870 return 0;
3871 }
3872
92b1551b
MH
3873 /*
3874 * Fail if a refname appears more than once in the
3875 * transaction. (If we end up splitting up any updates using
3876 * split_symref_update() or split_head_update(), those
3877 * functions will check that the new updates don't have the
3878 * same refname as any existing ones.)
3879 */
3880 for (i = 0; i < transaction->nr; i++) {
3881 struct ref_update *update = transaction->updates[i];
3882 struct string_list_item *item =
3883 string_list_append(&affected_refnames, update->refname);
3884
3885 /*
3886 * We store a pointer to update in item->util, but at
3887 * the moment we never use the value of this field
3888 * except to check whether it is non-NULL.
3889 */
3890 item->util = update;
3891 }
7bd9bcf3
MH
3892 string_list_sort(&affected_refnames);
3893 if (ref_update_reject_duplicates(&affected_refnames, err)) {
3894 ret = TRANSACTION_GENERIC_ERROR;
3895 goto cleanup;
3896 }
3897
92b1551b
MH
3898 /*
3899 * Special hack: If a branch is updated directly and HEAD
3900 * points to it (may happen on the remote side of a push
3901 * for example) then logically the HEAD reflog should be
3902 * updated too.
3903 *
3904 * A generic solution would require reverse symref lookups,
3905 * but finding all symrefs pointing to a given branch would be
3906 * rather costly for this rare event (the direct update of a
3907 * branch) to be worth it. So let's cheat and check with HEAD
3908 * only, which should cover 99% of all usage scenarios (even
3909 * 100% of the default ones).
3910 *
3911 * So if HEAD is a symbolic reference, then record the name of
3912 * the reference that it points to. If we see an update of
3913 * head_ref within the transaction, then split_head_update()
3914 * arranges for the reflog of HEAD to be updated, too.
3915 */
3916 head_ref = resolve_refdup("HEAD", RESOLVE_REF_NO_RECURSE,
3917 head_oid.hash, &head_type);
3918
3919 if (head_ref && !(head_type & REF_ISSYMREF)) {
3920 free(head_ref);
3921 head_ref = NULL;
3922 }
3923
7bd9bcf3
MH
3924 /*
3925 * Acquire all locks, verify old values if provided, check
3926 * that new values are valid, and write new values to the
3927 * lockfiles, ready to be activated. Only keep one lockfile
3928 * open at a time to avoid running out of file descriptors.
3929 */
efe47281
MH
3930 for (i = 0; i < transaction->nr; i++) {
3931 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3932
92b1551b 3933 ret = lock_ref_for_update(update, transaction, head_ref,
165056b2
MH
3934 &affected_refnames, err);
3935 if (ret)
7bd9bcf3 3936 goto cleanup;
7bd9bcf3
MH
3937 }
3938
3939 /* Perform updates first so live commits remain referenced */
efe47281
MH
3940 for (i = 0; i < transaction->nr; i++) {
3941 struct ref_update *update = transaction->updates[i];
92b1551b 3942 struct ref_lock *lock = update->lock;
7bd9bcf3 3943
d99aa884
DT
3944 if (update->flags & REF_NEEDS_COMMIT ||
3945 update->flags & REF_LOG_ONLY) {
92b1551b
MH
3946 if (log_ref_write(lock->ref_name, lock->old_oid.hash,
3947 update->new_sha1,
3948 update->msg, update->flags, err)) {
3949 char *old_msg = strbuf_detach(err, NULL);
3950
3951 strbuf_addf(err, "cannot update the ref '%s': %s",
3952 lock->ref_name, old_msg);
3953 free(old_msg);
3954 unlock_ref(lock);
7bd9bcf3
MH
3955 update->lock = NULL;
3956 ret = TRANSACTION_GENERIC_ERROR;
3957 goto cleanup;
92b1551b
MH
3958 }
3959 }
3960 if (update->flags & REF_NEEDS_COMMIT) {
3961 clear_loose_ref_cache(&ref_cache);
3962 if (commit_ref(lock)) {
3963 strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
3964 unlock_ref(lock);
7bd9bcf3 3965 update->lock = NULL;
92b1551b
MH
3966 ret = TRANSACTION_GENERIC_ERROR;
3967 goto cleanup;
7bd9bcf3
MH
3968 }
3969 }
3970 }
7bd9bcf3 3971 /* Perform deletes now that updates are safely completed */
efe47281
MH
3972 for (i = 0; i < transaction->nr; i++) {
3973 struct ref_update *update = transaction->updates[i];
7bd9bcf3 3974
d99aa884
DT
3975 if (update->flags & REF_DELETING &&
3976 !(update->flags & REF_LOG_ONLY)) {
7bd9bcf3
MH
3977 if (delete_ref_loose(update->lock, update->type, err)) {
3978 ret = TRANSACTION_GENERIC_ERROR;