1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "got_compat.h"
18 
19 #include <sys/types.h>
20 #include <sys/queue.h>
21 #include <sys/stat.h>
22 
23 #include <errno.h>
24 #include <dirent.h>
25 #include <limits.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30 #include <zlib.h>
31 #include <time.h>
32 #include <libgen.h>
33 
34 #include "got_error.h"
35 #include "got_object.h"
36 #include "got_repository.h"
37 #include "got_reference.h"
38 #include "got_opentemp.h"
39 #include "got_path.h"
40 
41 #include "got_lib_hash.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_inflate.h"
44 #include "got_lib_object.h"
45 #include "got_lib_object_idset.h"
46 #include "got_lib_lockfile.h"
47 
48 #ifndef nitems
49 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
50 #endif
51 
52 #define GOT_REF_HEADS	"heads"
53 #define GOT_REF_TAGS	"tags"
54 #define GOT_REF_REMOTES	"remotes"
55 
56 /*
57  * We do not resolve tags yet, and don't yet care about sorting refs either,
58  * so packed-refs files we write contain a minimal header which disables all
59  * packed-refs "traits" supported by Git.
60  */
61 #define GOT_PACKED_REFS_HEADER	"# pack-refs with:"
62 
63 /* A symbolic reference. */
64 struct got_symref {
65 	char *name;
66 	char *ref;
67 };
68 
69 #define GOT_REF_RECURSE_MAX	20
70 
71 /* A non-symbolic reference (there is no better designation). */
72 struct got_ref {
73 	char *name;
74 	struct got_object_id id;
75 };
76 
77 /* A reference which points to an arbitrary object. */
78 struct got_reference {
79 	unsigned int flags;
80 #define GOT_REF_IS_SYMBOLIC	0x01
81 #define GOT_REF_IS_PACKED	0x02
82 
83 	union {
84 		struct got_ref ref;
85 		struct got_symref symref;
86 	} ref;
87 
88 	struct got_lockfile *lf;
89 	time_t mtime;
90 
91 	/*
92 	 * Cached timestamp for got_ref_cmp_by_commit_timestamp_descending()
93 	 * and got_ref_cmp_tags().
94 	 */
95 	time_t committer_time;
96 };
97 
98 static const struct got_error *
99 alloc_ref(struct got_reference **ref, const char *name,
100     struct got_object_id *id, int flags, time_t mtime)
101 {
102 	const struct got_error *err = NULL;
103 
104 	*ref = calloc(1, sizeof(**ref));
105 	if (*ref == NULL)
106 		return got_error_from_errno("calloc");
107 
108 	memcpy(&(*ref)->ref.ref.id, id, sizeof((*ref)->ref.ref.id));
109 	(*ref)->flags = flags;
110 	(*ref)->ref.ref.name = strdup(name);
111 	(*ref)->mtime = mtime;
112 	if ((*ref)->ref.ref.name == NULL) {
113 		err = got_error_from_errno("strdup");
114 		got_ref_close(*ref);
115 		*ref = NULL;
116 	}
117 	return err;
118 }
119 
120 static const struct got_error *
121 alloc_symref(struct got_reference **ref, const char *name,
122     const char *target_ref, int flags)
123 {
124 	const struct got_error *err = NULL;
125 
126 	*ref = calloc(1, sizeof(**ref));
127 	if (*ref == NULL)
128 		return got_error_from_errno("calloc");
129 
130 	(*ref)->flags = GOT_REF_IS_SYMBOLIC | flags;
131 	(*ref)->ref.symref.name = strdup(name);
132 	if ((*ref)->ref.symref.name == NULL) {
133 		err = got_error_from_errno("strdup");
134 		got_ref_close(*ref);
135 		*ref = NULL;
136 		return err;
137 	}
138 	(*ref)->ref.symref.ref = strdup(target_ref);
139 	if ((*ref)->ref.symref.ref == NULL) {
140 		err = got_error_from_errno("strdup");
141 		got_ref_close(*ref);
142 		*ref = NULL;
143 	}
144 	return err;
145 }
146 
147 static const struct got_error *
148 parse_symref(struct got_reference **ref, const char *name, const char *line)
149 {
150 	if (line[0] == '\0')
151 		return got_error(GOT_ERR_BAD_REF_DATA);
152 
153 	return alloc_symref(ref, name, line, 0);
154 }
155 
156 static const struct got_error *
157 parse_ref_line(struct got_reference **ref, const char *name, const char *line,
158     time_t mtime, enum got_hash_algorithm algo)
159 {
160 	struct got_object_id id;
161 
162 	if (strncmp(line, "ref: ", 5) == 0) {
163 		line += 5;
164 		return parse_symref(ref, name, line);
165 	}
166 
167 	if (!got_parse_object_id(&id, line, algo))
168 		return got_error(GOT_ERR_BAD_REF_DATA);
169 
170 	return alloc_ref(ref, name, &id, 0, mtime);
171 }
172 
173 static const struct got_error *
174 parse_ref_file(struct got_reference **ref, const char *name,
175     const char *absname, const char *abspath, int lock,
176     enum got_hash_algorithm algo)
177 {
178 	const struct got_error *err = NULL;
179 	FILE *f;
180 	char *line = NULL;
181 	size_t linesize = 0;
182 	ssize_t linelen;
183 	struct got_lockfile *lf = NULL;
184 	struct stat sb;
185 
186 	if (lock) {
187 		err = got_lockfile_lock(&lf, abspath, -1);
188 		if (err) {
189 			if (err->code == GOT_ERR_ERRNO && errno == ENOENT)
190 				err = got_error_not_ref(name);
191 			return err;
192 		}
193 	}
194 
195 	f = fopen(abspath, "rbe");
196 	if (f == NULL) {
197 		if (errno != ENOTDIR && errno != ENOENT)
198 			err = got_error_from_errno2("fopen", abspath);
199 		else
200 			err = got_error_not_ref(name);
201 		if (lock)
202 			got_lockfile_unlock(lf, -1);
203 		return err;
204 	}
205 	if (fstat(fileno(f), &sb) == -1) {
206 		err = got_error_from_errno2("fstat", abspath);
207 		goto done;
208 	}
209 
210 	linelen = getline(&line, &linesize, f);
211 	if (linelen == -1) {
212 		if (feof(f))
213 			err = NULL; /* ignore empty files (could be locks) */
214 		else {
215 			if (errno == EISDIR)
216 				err = got_error(GOT_ERR_NOT_REF);
217 			else if (ferror(f))
218 				err = got_ferror(f, GOT_ERR_IO);
219 			else
220 				err = got_error_from_errno2("getline", abspath);
221 		}
222 		if (lock)
223 			got_lockfile_unlock(lf, -1);
224 		goto done;
225 	}
226 	while (linelen > 0 && line[linelen - 1] == '\n') {
227 		line[linelen - 1] = '\0';
228 		linelen--;
229 	}
230 
231 	err = parse_ref_line(ref, absname, line, sb.st_mtime, algo);
232 	if (lock) {
233 		if (err)
234 			got_lockfile_unlock(lf, -1);
235 		else {
236 			if (*ref)
237 				(*ref)->lf = lf;
238 			else
239 				got_lockfile_unlock(lf, -1);
240 		}
241 	}
242 done:
243 	free(line);
244 	if (fclose(f) == EOF && err == NULL) {
245 		err = got_error_from_errno("fclose");
246 		if (*ref) {
247 			if (lock)
248 				got_ref_unlock(*ref);
249 			got_ref_close(*ref);
250 			*ref = NULL;
251 		}
252 	}
253 	return err;
254 }
255 
256 static int
257 is_well_known_ref(const char *refname)
258 {
259 	return (strcmp(refname, GOT_REF_HEAD) == 0 ||
260 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
261 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
262 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0);
263 }
264 
265 static char *
266 get_refs_dir_path(struct got_repository *repo, const char *refname)
267 {
268 	if (is_well_known_ref(refname) || strncmp(refname, "refs/", 5) == 0)
269 		return strdup(got_repo_get_path_git_dir(repo));
270 
271 	return got_repo_get_path_refs(repo);
272 }
273 
274 const struct got_error *
275 got_ref_alloc(struct got_reference **ref, const char *name,
276     struct got_object_id *id)
277 {
278 	if (!got_ref_name_is_valid(name))
279 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
280 
281 	return alloc_ref(ref, name, id, 0, 0);
282 }
283 
284 const struct got_error *
285 got_ref_alloc_symref(struct got_reference **ref, const char *name,
286 	struct got_reference *target_ref)
287 {
288 	if (!got_ref_name_is_valid(name))
289 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
290 
291 	return alloc_symref(ref, name, got_ref_get_name(target_ref), 0);
292 }
293 
294 static const struct got_error *
295 parse_packed_ref_line(struct got_reference **ref, const char *abs_refname,
296     const char *line, time_t mtime, enum got_hash_algorithm algo)
297 {
298 	struct got_object_id id;
299 	const char *name;
300 
301 	*ref = NULL;
302 
303 	if (line[0] == '#' || line[0] == '^')
304 		return NULL;
305 
306 	if (!got_parse_object_id(&id, line, algo))
307 		return got_error(GOT_ERR_BAD_REF_DATA);
308 
309 	if (abs_refname) {
310 		if (strcmp(line + SHA1_DIGEST_STRING_LENGTH, abs_refname) != 0)
311 			return NULL;
312 		name = abs_refname;
313 	} else
314 		name = line + SHA1_DIGEST_STRING_LENGTH;
315 
316 	return alloc_ref(ref, name, &id, GOT_REF_IS_PACKED, mtime);
317 }
318 
319 static const struct got_error *
320 open_packed_ref(struct got_reference **ref, FILE *f, const char **subdirs,
321     int nsubdirs, const char *refname, time_t mtime,
322     enum got_hash_algorithm algo)
323 {
324 	const struct got_error *err = NULL;
325 	char *abs_refname;
326 	char *line = NULL;
327 	size_t linesize = 0;
328 	ssize_t linelen;
329 	int i, ref_is_absolute = (strncmp(refname, "refs/", 5) == 0);
330 
331 	*ref = NULL;
332 
333 	if (ref_is_absolute)
334 		abs_refname = (char *)refname;
335 	do {
336 		linelen = getline(&line, &linesize, f);
337 		if (linelen == -1) {
338 			if (feof(f))
339 				break;
340 			err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
341 			break;
342 		}
343 		if (linelen > 0 && line[linelen - 1] == '\n')
344 			line[linelen - 1] = '\0';
345 		for (i = 0; i < nsubdirs; i++) {
346 			if (!ref_is_absolute &&
347 			    asprintf(&abs_refname, "refs/%s/%s", subdirs[i],
348 			    refname) == -1)
349 				return got_error_from_errno("asprintf");
350 			err = parse_packed_ref_line(ref, abs_refname, line,
351 			    mtime, algo);
352 			if (!ref_is_absolute)
353 				free(abs_refname);
354 			if (err || *ref != NULL)
355 				break;
356 		}
357 		if (err)
358 			break;
359 	} while (*ref == NULL);
360 	free(line);
361 
362 	return err;
363 }
364 
365 static const struct got_error *
366 open_ref(struct got_reference **ref, const char *path_refs, const char *subdir,
367     const char *name, int lock, enum got_hash_algorithm algo)
368 {
369 	const struct got_error *err = NULL;
370 	char *path = NULL;
371 	char *absname = NULL;
372 	int ref_is_absolute = (strncmp(name, "refs/", 5) == 0);
373 	int ref_is_well_known = (subdir[0] == '\0' && is_well_known_ref(name));
374 
375 	*ref = NULL;
376 
377 	if (!got_ref_name_is_valid(name))
378 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
379 
380 	if (ref_is_absolute || ref_is_well_known) {
381 		if (asprintf(&path, "%s/%s", path_refs, name) == -1)
382 			return got_error_from_errno("asprintf");
383 		absname = (char *)name;
384 	} else {
385 		if (asprintf(&path, "%s/%s%s%s", path_refs, subdir,
386 		    subdir[0] ? "/" : "", name) == -1)
387 			return got_error_from_errno("asprintf");
388 
389 		if (asprintf(&absname, "refs/%s%s%s",
390 		    subdir, subdir[0] ? "/" : "", name) == -1) {
391 			err = got_error_from_errno("asprintf");
392 			goto done;
393 		}
394 	}
395 
396 	err = parse_ref_file(ref, name, absname, path, lock, algo);
397 done:
398 	if (!ref_is_absolute && !ref_is_well_known)
399 		free(absname);
400 	free(path);
401 	return err;
402 }
403 
404 const struct got_error *
405 got_ref_open(struct got_reference **ref, struct got_repository *repo,
406     const char *refname, int lock)
407 {
408 	const struct got_error *err = NULL;
409 	char *packed_refs_path = NULL, *path_refs = NULL;
410 	const char *subdirs[] = {
411 	    GOT_REF_HEADS, GOT_REF_TAGS, GOT_REF_REMOTES
412 	};
413 	size_t i;
414 	int well_known = is_well_known_ref(refname);
415 	struct got_lockfile *lf = NULL;
416 
417 	*ref = NULL;
418 
419 	path_refs = get_refs_dir_path(repo, refname);
420 	if (path_refs == NULL) {
421 		err = got_error_from_errno2("get_refs_dir_path", refname);
422 		goto done;
423 	}
424 
425 	if (well_known) {
426 		err = open_ref(ref, path_refs, "", refname, lock,
427 		    got_repo_get_object_format(repo));
428 	} else {
429 		FILE *f;
430 
431 		/* Search on-disk refs before packed refs! */
432 		for (i = 0; i < nitems(subdirs); i++) {
433 			err = open_ref(ref, path_refs, subdirs[i], refname,
434 			    lock, got_repo_get_object_format(repo));
435 			if ((err && err->code != GOT_ERR_NOT_REF) || *ref)
436 				goto done;
437 		}
438 
439 		packed_refs_path = got_repo_get_path_packed_refs(repo);
440 		if (packed_refs_path == NULL) {
441 			err = got_error_from_errno(
442 			    "got_repo_get_path_packed_refs");
443 			goto done;
444 		}
445 
446 		if (lock) {
447 			err = got_lockfile_lock(&lf, packed_refs_path, -1);
448 			if (err)
449 				goto done;
450 		}
451 		f = fopen(packed_refs_path, "rbe");
452 		if (f != NULL) {
453 			struct stat sb;
454 			if (fstat(fileno(f), &sb) == -1) {
455 				err = got_error_from_errno2("fstat",
456 				    packed_refs_path);
457 				goto done;
458 			}
459 			err = open_packed_ref(ref, f, subdirs, nitems(subdirs),
460 			    refname, sb.st_mtime,
461 			    got_repo_get_object_format(repo));
462 			if (!err) {
463 				if (fclose(f) == EOF) {
464 					err = got_error_from_errno("fclose");
465 					got_ref_close(*ref);
466 					*ref = NULL;
467 				} else if (*ref)
468 					(*ref)->lf = lf;
469 			}
470 		}
471 	}
472 done:
473 	if (!err && *ref == NULL)
474 		err = got_error_not_ref(refname);
475 	if (err && lf)
476 		got_lockfile_unlock(lf, -1);
477 	free(packed_refs_path);
478 	free(path_refs);
479 	return err;
480 }
481 
482 void
483 got_ref_close(struct got_reference *ref)
484 {
485 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
486 		free(ref->ref.symref.name);
487 		free(ref->ref.symref.ref);
488 	} else
489 		free(ref->ref.ref.name);
490 	free(ref);
491 }
492 
493 struct got_reference *
494 got_ref_dup(struct got_reference *ref)
495 {
496 	struct got_reference *ret;
497 
498 	ret = calloc(1, sizeof(*ret));
499 	if (ret == NULL)
500 		return NULL;
501 
502 	ret->flags = ref->flags;
503 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
504 		ret->ref.symref.name = strdup(ref->ref.symref.name);
505 		if (ret->ref.symref.name == NULL) {
506 			free(ret);
507 			return NULL;
508 		}
509 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
510 		if (ret->ref.symref.ref == NULL) {
511 			free(ret->ref.symref.name);
512 			free(ret);
513 			return NULL;
514 		}
515 	} else {
516 		ret->ref.ref.name = strdup(ref->ref.ref.name);
517 		if (ret->ref.ref.name == NULL) {
518 			free(ret);
519 			return NULL;
520 		}
521 		memcpy(&ret->ref.ref.id, &ref->ref.ref.id,
522 		    sizeof(ret->ref.ref.id));
523 	}
524 
525 	return ret;
526 }
527 
528 const struct got_error *
529 got_reflist_entry_dup(struct got_reflist_entry **newp,
530     struct got_reflist_entry *re)
531 {
532 	const struct got_error *err = NULL;
533 	struct got_reflist_entry *new;
534 
535 	*newp = NULL;
536 
537 	new = malloc(sizeof(*new));
538 	if (new == NULL)
539 		return got_error_from_errno("malloc");
540 
541 	new->ref = got_ref_dup(re->ref);
542 	if (new->ref == NULL) {
543 		err = got_error_from_errno("got_ref_dup");
544 		free(new);
545 		return err;
546 	}
547 
548 	*newp = new;
549 	return NULL;
550 }
551 
552 const struct got_error *
553 got_ref_resolve_symbolic(struct got_reference **resolved,
554     struct got_repository *repo, struct got_reference *ref)
555 {
556 	struct got_reference *nextref;
557 	const struct got_error *err;
558 
559 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref, 0);
560 	if (err)
561 		return err;
562 
563 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
564 		err = got_ref_resolve_symbolic(resolved, repo, nextref);
565 	else
566 		*resolved = got_ref_dup(nextref);
567 
568 	got_ref_close(nextref);
569 	return err;
570 }
571 
572 static const struct got_error *
573 ref_resolve(struct got_object_id **id, struct got_repository *repo,
574     struct got_reference *ref, int recursion)
575 {
576 	const struct got_error *err;
577 
578 	if (recursion <= 0)
579 		return got_error_msg(GOT_ERR_RECURSION,
580 		    "reference recursion limit reached");
581 
582 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
583 		struct got_reference *resolved = NULL;
584 		err = got_ref_resolve_symbolic(&resolved, repo, ref);
585 		if (err == NULL)
586 			err = ref_resolve(id, repo, resolved, --recursion);
587 		if (resolved)
588 			got_ref_close(resolved);
589 		return err;
590 	}
591 
592 	*id = calloc(1, sizeof(**id));
593 	if (*id == NULL)
594 		return got_error_from_errno("calloc");
595 	memcpy(*id, &ref->ref.ref.id, sizeof(**id));
596 	return NULL;
597 }
598 
599 const struct got_error *
600 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
601     struct got_reference *ref)
602 {
603 	return ref_resolve(id, repo, ref, GOT_REF_RECURSE_MAX);
604 }
605 
606 char *
607 got_ref_to_str(struct got_reference *ref)
608 {
609 	char *str;
610 
611 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
612 		return strdup(ref->ref.symref.ref);
613 
614 	if (got_object_id_str(&str, &ref->ref.ref.id) != NULL)
615 		return NULL;
616 
617 	return str;
618 }
619 
620 const char *
621 got_ref_get_name(struct got_reference *ref)
622 {
623 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
624 		return ref->ref.symref.name;
625 
626 	return ref->ref.ref.name;
627 }
628 
629 const char *
630 got_ref_get_symref_target(struct got_reference *ref)
631 {
632 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
633 		return ref->ref.symref.ref;
634 
635 	return NULL;
636 }
637 
638 time_t
639 got_ref_get_mtime(struct got_reference *ref)
640 {
641 	return ref->mtime;
642 }
643 
644 const struct got_error *
645 got_ref_cmp_by_name(void *arg, int *cmp, struct got_reference *re1,
646     struct got_reference* re2)
647 {
648 	const char *name1 = got_ref_get_name(re1);
649 	const char *name2 = got_ref_get_name(re2);
650 
651 	*cmp = got_path_cmp(name1, name2, strlen(name1), strlen(name2));
652 	return NULL;
653 }
654 
655 static const struct got_error *
656 get_committer_time(struct got_reference *ref, struct got_repository *repo)
657 {
658 	const struct got_error *err = NULL;
659 	int obj_type;
660 	struct got_commit_object *commit = NULL;
661 	struct got_tag_object *tag = NULL;
662 	struct got_object_id *id = NULL;
663 
664 	err = got_ref_resolve(&id, repo, ref);
665 	if (err)
666 		return err;
667 
668 	err = got_object_get_type(&obj_type, repo, id);
669 	if (err)
670 		goto done;
671 
672 	switch (obj_type) {
673 	case GOT_OBJ_TYPE_COMMIT:
674 		err = got_object_open_as_commit(&commit, repo, id);
675 		if (err)
676 			goto done;
677 		ref->committer_time =
678 		    got_object_commit_get_committer_time(commit);
679 		break;
680 	case GOT_OBJ_TYPE_TAG:
681 		err = got_object_open_as_tag(&tag, repo, id);
682 		if (err)
683 			goto done;
684 		ref->committer_time = got_object_tag_get_tagger_time(tag);
685 		break;
686 	default:
687 		/* best effort for other object types */
688 		ref->committer_time = got_ref_get_mtime(ref);
689 		break;
690 	}
691 done:
692 	free(id);
693 	if (commit)
694 		got_object_commit_close(commit);
695 	if (tag)
696 		got_object_tag_close(tag);
697 	return err;
698 }
699 
700 const struct got_error *
701 got_ref_cmp_tags(void *arg, int *cmp, struct got_reference *ref1,
702     struct got_reference *ref2)
703 {
704 	const struct got_error *err = NULL;
705 	struct got_repository *repo = arg;
706 
707 	*cmp = 0;
708 
709 	if (ref1->committer_time == 0) {
710 		err = get_committer_time(ref1, repo);
711 		if (err)
712 			return err;
713 	}
714 	if (ref2->committer_time == 0) {
715 		err = get_committer_time(ref2, repo);
716 		if (err)
717 			return err;
718 	}
719 
720 	/* Put latest tags first. */
721 	if (ref1->committer_time < ref2->committer_time)
722 		*cmp = 1;
723 	else if (ref1->committer_time > ref2->committer_time)
724 		*cmp = -1;
725 	else
726 		err = got_ref_cmp_by_name(NULL, cmp, ref2, ref1);
727 
728 	return err;
729 }
730 
731 const struct got_error *
732 got_ref_cmp_by_commit_timestamp_descending(void *arg, int *cmp,
733     struct got_reference *ref1, struct got_reference *ref2)
734 {
735 	const struct got_error *err = NULL;
736 	struct got_repository *repo = arg;
737 
738 	*cmp = 0;
739 
740 	if (ref1->committer_time == 0) {
741 		err = get_committer_time(ref1, repo);
742 		if (err)
743 			return err;
744 	}
745 	if (ref2->committer_time == 0) {
746 		err = get_committer_time(ref2, repo);
747 		if (err)
748 			return err;
749 	}
750 
751 	if (ref1->committer_time < ref2->committer_time)
752 		*cmp = 1;
753 	else if (ref2->committer_time < ref1->committer_time)
754 		*cmp = -1;
755 	else
756 		return got_ref_cmp_by_name(arg, cmp, ref1, ref2);
757 
758 	return err;
759 }
760 
761 const struct got_error *
762 got_reflist_insert(struct got_reflist_entry **newp,
763     struct got_reflist_head *refs, struct got_reference *ref,
764     got_ref_cmp_cb cmp_cb, void *cmp_arg)
765 {
766 	const struct got_error *err;
767 	struct got_reflist_entry *new, *re;
768 	int cmp;
769 
770 	*newp = NULL;
771 
772 	if (cmp_cb != got_ref_cmp_by_name && (ref->flags & GOT_REF_IS_PACKED)) {
773 		/*
774 		 * If we are not sorting elements by name then we must still
775 		 * detect collisions between a packed ref and an on-disk ref
776 		 * using the same name. On-disk refs take precedence and are
777 		 * already present on the list before packed refs get added.
778 		 */
779 		TAILQ_FOREACH(re, refs, entry) {
780 			err = got_ref_cmp_by_name(NULL, &cmp, re->ref, ref);
781 			if (err)
782 				return err;
783 			if (cmp == 0)
784 				return NULL;
785 		}
786 	}
787 
788 	new = malloc(sizeof(*new));
789 	if (new == NULL)
790 		return got_error_from_errno("malloc");
791 	new->ref = ref;
792 	*newp = new;
793 
794 	/*
795 	 * We must de-duplicate entries on insert because packed-refs may
796 	 * contain redundant entries. On-disk refs take precedence.
797 	 * This code assumes that on-disk revs are read before packed-refs.
798 	 * We're iterating the list anyway, so insert elements sorted by name.
799 	 *
800 	 * Many callers will provide paths in a somewhat sorted order.
801 	 * Iterating backwards from the tail of the list should be more
802 	 * efficient than traversing through the entire list each time
803 	 * an element is inserted.
804 	 */
805 	re = TAILQ_LAST(refs, got_reflist_head);
806 	while (re) {
807 		err = (*cmp_cb)(cmp_arg, &cmp, re->ref, new->ref);
808 		if (err)
809 			return err;
810 		if (cmp == 0) {
811 			/* duplicate */
812 			free(new);
813 			*newp = NULL;
814 			return NULL;
815 		} else if (cmp < 0) {
816 			TAILQ_INSERT_AFTER(refs, re, new, entry);
817 			return NULL;
818 		}
819 		re = TAILQ_PREV(re, got_reflist_head, entry);
820 	}
821 
822 	TAILQ_INSERT_HEAD(refs, new, entry);
823 	return NULL;
824 }
825 
826 const struct got_error *
827 got_reflist_sort(struct got_reflist_head *refs,
828     got_ref_cmp_cb cmp_cb, void *cmp_arg)
829 {
830 	const struct got_error *err = NULL;
831 	struct got_reflist_entry *re, *tmp, *new;
832 	struct got_reflist_head sorted;
833 
834 	TAILQ_INIT(&sorted);
835 
836 	TAILQ_FOREACH_SAFE(re, refs, entry, tmp) {
837 		struct got_reference *ref = re->ref;
838 		TAILQ_REMOVE(refs, re, entry);
839 		free(re);
840 		err = got_reflist_insert(&new, &sorted, ref, cmp_cb, cmp_arg);
841 		if (err || new == NULL /* duplicate */)
842 			got_ref_close(ref);
843 		if (err)
844 			return err;
845 	}
846 
847 	TAILQ_CONCAT(refs, &sorted, entry);
848 	return NULL;
849 }
850 
851 static const struct got_error *
852 gather_on_disk_refs(struct got_reflist_head *refs, const char *path_refs,
853     const char *subdir, struct got_repository *repo,
854     got_ref_cmp_cb cmp_cb, void *cmp_arg)
855 {
856 	const struct got_error *err = NULL;
857 	DIR *d = NULL;
858 	char *path_subdir;
859 
860 	while (subdir[0] == '/')
861 		subdir++;
862 
863 	if (asprintf(&path_subdir, "%s/%s", path_refs, subdir) == -1)
864 		return got_error_from_errno("asprintf");
865 
866 	d = opendir(path_subdir);
867 	if (d == NULL)
868 		goto done;
869 
870 	for (;;) {
871 		struct dirent *dent;
872 		struct got_reference *ref;
873 		char *child;
874 		int type;
875 
876 		dent = readdir(d);
877 		if (dent == NULL)
878 			break;
879 
880 		if (strcmp(dent->d_name, ".") == 0 ||
881 		    strcmp(dent->d_name, "..") == 0)
882 			continue;
883 
884 		err = got_path_dirent_type(&type, path_subdir, dent);
885 		if (err)
886 			break;
887 
888 		switch (type) {
889 		case DT_REG:
890 			err = open_ref(&ref, path_refs, subdir, dent->d_name,
891 			    0, got_repo_get_object_format(repo));
892 			if (err && err->code == GOT_ERR_BAD_REF_NAME)
893 				break;
894 			if (err)
895 				goto done;
896 			if (ref) {
897 				struct got_reflist_entry *new;
898 				err = got_reflist_insert(&new, refs, ref,
899 				    cmp_cb, cmp_arg);
900 				if (err || new == NULL /* duplicate */)
901 					got_ref_close(ref);
902 				if (err)
903 					goto done;
904 			}
905 			break;
906 		case DT_DIR:
907 			if (asprintf(&child, "%s%s%s", subdir,
908 			    subdir[0] == '\0' ? "" : "/", dent->d_name) == -1) {
909 				err = got_error_from_errno("asprintf");
910 				break;
911 			}
912 			err = gather_on_disk_refs(refs, path_refs, child, repo,
913 			    cmp_cb, cmp_arg);
914 			free(child);
915 			break;
916 		default:
917 			break;
918 		}
919 	}
920 done:
921 	if (d)
922 		closedir(d);
923 	free(path_subdir);
924 	return err;
925 }
926 
927 const struct got_error *
928 got_ref_list(struct got_reflist_head *refs, struct got_repository *repo,
929     const char *ref_namespace, got_ref_cmp_cb cmp_cb, void *cmp_arg)
930 {
931 	const struct got_error *err;
932 	char *packed_refs_path = NULL, *path_refs = NULL;
933 	char *abs_namespace = NULL, *buf = NULL;
934 	const char *ondisk_ref_namespace = NULL;
935 	char *line = NULL;
936 	FILE *f = NULL;
937 	struct got_reference *ref;
938 	struct got_reflist_entry *new;
939 
940 	if (ref_namespace == NULL || ref_namespace[0] == '\0') {
941 		path_refs = get_refs_dir_path(repo, GOT_REF_HEAD);
942 		if (path_refs == NULL) {
943 			err = got_error_from_errno("get_refs_dir_path");
944 			goto done;
945 		}
946 		err = open_ref(&ref, path_refs, "", GOT_REF_HEAD, 0,
947 		    got_repo_get_object_format(repo));
948 		if (err)
949 			goto done;
950 		err = got_reflist_insert(&new, refs, ref, cmp_cb, cmp_arg);
951 		if (err || new == NULL /* duplicate */)
952 			got_ref_close(ref);
953 		if (err && err->code != GOT_ERR_NOT_REF)
954 			goto done;
955 	} else {
956 		/* Try listing a single reference. */
957 		const char *refname = ref_namespace;
958 		path_refs = get_refs_dir_path(repo, refname);
959 		if (path_refs == NULL) {
960 			err = got_error_from_errno("get_refs_dir_path");
961 			goto done;
962 		}
963 		err = open_ref(&ref, path_refs, "", refname, 0,
964 		    got_repo_get_object_format(repo));
965 		if (err) {
966 			if (err->code != GOT_ERR_NOT_REF)
967 				goto done;
968 			/* Try to look up references in a given namespace. */
969 		} else {
970 			err = got_reflist_insert(&new, refs, ref,
971 			    cmp_cb, cmp_arg);
972 			if (err || new == NULL /* duplicate */)
973 				got_ref_close(ref);
974 			return err;
975 		}
976 	}
977 
978 	if (ref_namespace) {
979 		size_t len;
980 		/* Canonicalize the path to eliminate double-slashes if any. */
981 		if (asprintf(&abs_namespace, "/%s", ref_namespace) == -1) {
982 			err = got_error_from_errno("asprintf");
983 			goto done;
984 		}
985 		len = strlen(abs_namespace) + 1;
986 		buf = malloc(len);
987 		if (buf == NULL) {
988 			err = got_error_from_errno("malloc");
989 			goto done;
990 		}
991 		err = got_canonpath(abs_namespace, buf, len);
992 		if (err)
993 			goto done;
994 		ondisk_ref_namespace = buf;
995 		while (ondisk_ref_namespace[0] == '/')
996 			ondisk_ref_namespace++;
997 		if (strncmp(ondisk_ref_namespace, "refs/", 5) == 0)
998 			ondisk_ref_namespace += 5;
999 		else if (strcmp(ondisk_ref_namespace, "refs") == 0)
1000 			ondisk_ref_namespace = "";
1001 	}
1002 
1003 	/* Gather on-disk refs before parsing packed-refs. */
1004 	free(path_refs);
1005 	path_refs = get_refs_dir_path(repo, "");
1006 	if (path_refs == NULL) {
1007 		err = got_error_from_errno("get_refs_dir_path");
1008 		goto done;
1009 	}
1010 	err = gather_on_disk_refs(refs, path_refs,
1011 	    ondisk_ref_namespace ? ondisk_ref_namespace : "", repo,
1012 	    cmp_cb, cmp_arg);
1013 	if (err)
1014 		goto done;
1015 
1016 	/*
1017 	 * The packed-refs file may contain redundant entries, in which
1018 	 * case on-disk refs take precedence.
1019 	 */
1020 	packed_refs_path = got_repo_get_path_packed_refs(repo);
1021 	if (packed_refs_path == NULL) {
1022 		err = got_error_from_errno("got_repo_get_path_packed_refs");
1023 		goto done;
1024 	}
1025 
1026 	f = fopen(packed_refs_path, "re");
1027 	if (f) {
1028 		size_t linesize = 0;
1029 		ssize_t linelen;
1030 		struct stat sb;
1031 
1032 		if (fstat(fileno(f), &sb) == -1) {
1033 			err = got_error_from_errno2("fstat", packed_refs_path);
1034 			goto done;
1035 		}
1036 		for (;;) {
1037 			linelen = getline(&line, &linesize, f);
1038 			if (linelen == -1) {
1039 				if (feof(f))
1040 					break;
1041 				err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
1042 				goto done;
1043 			}
1044 			if (linelen > 0 && line[linelen - 1] == '\n')
1045 				line[linelen - 1] = '\0';
1046 			err = parse_packed_ref_line(&ref, NULL, line,
1047 			    sb.st_mtime, got_repo_get_object_format(repo));
1048 			if (err)
1049 				goto done;
1050 			if (ref) {
1051 				if (ref_namespace) {
1052 					const char *name;
1053 					name = got_ref_get_name(ref);
1054 					if (!got_path_is_child(name,
1055 					    ref_namespace,
1056 					    strlen(ref_namespace))) {
1057 						got_ref_close(ref);
1058 						continue;
1059 					}
1060 				}
1061 				err = got_reflist_insert(&new, refs, ref,
1062 				    cmp_cb, cmp_arg);
1063 				if (err || new == NULL /* duplicate */)
1064 					got_ref_close(ref);
1065 				if (err)
1066 					goto done;
1067 			}
1068 		}
1069 	}
1070 done:
1071 	free(packed_refs_path);
1072 	free(abs_namespace);
1073 	free(buf);
1074 	free(line);
1075 	free(path_refs);
1076 	if (f && fclose(f) == EOF && err == NULL)
1077 		err = got_error_from_errno("fclose");
1078 	return err;
1079 }
1080 
1081 void
1082 got_ref_list_free(struct got_reflist_head *refs)
1083 {
1084 	struct got_reflist_entry *re;
1085 
1086 	while ((re = TAILQ_FIRST(refs))) {
1087 		TAILQ_REMOVE(refs, re, entry);
1088 		got_ref_close(re->ref);
1089 		free(re);
1090 	}
1091 }
1092 
1093 int
1094 got_ref_is_symbolic(struct got_reference *ref)
1095 {
1096 	return (ref->flags & GOT_REF_IS_SYMBOLIC);
1097 }
1098 
1099 const struct got_error *
1100 got_ref_change_ref(struct got_reference *ref, struct got_object_id *id)
1101 {
1102 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
1103 		return got_error(GOT_ERR_BAD_REF_TYPE);
1104 
1105 	memcpy(&ref->ref.ref.id, id, sizeof(ref->ref.ref.id));
1106 	return NULL;
1107 }
1108 
1109 const struct got_error *
1110 got_ref_change_symref(struct got_reference *ref, const char *refname)
1111 {
1112 	char *new_name;
1113 
1114 	if ((ref->flags & GOT_REF_IS_SYMBOLIC) == 0)
1115 		return got_error(GOT_ERR_BAD_REF_TYPE);
1116 
1117 	new_name = strdup(refname);
1118 	if (new_name == NULL)
1119 		return got_error_from_errno("strdup");
1120 
1121 	free(ref->ref.symref.ref);
1122 	ref->ref.symref.ref = new_name;
1123 	return NULL;
1124 }
1125 
1126 const struct got_error *
1127 got_ref_change_symref_to_ref(struct got_reference *symref,
1128     struct got_object_id *id)
1129 {
1130 	if ((symref->flags & GOT_REF_IS_SYMBOLIC) == 0)
1131 		return got_error(GOT_ERR_BAD_REF_TYPE);
1132 
1133 	symref->ref.ref.name = symref->ref.symref.name;
1134 	memcpy(&symref->ref.ref.id, id, sizeof(symref->ref.ref.id));
1135 	symref->flags &= ~GOT_REF_IS_SYMBOLIC;
1136 	return NULL;
1137 }
1138 
1139 const struct got_error *
1140 got_ref_write(struct got_reference *ref, struct got_repository *repo)
1141 {
1142 	const struct got_error *err = NULL, *unlock_err = NULL;
1143 	const char *name = got_ref_get_name(ref);
1144 	char *path_refs = NULL, *path = NULL, *tmppath = NULL;
1145 	struct got_lockfile *lf = NULL;
1146 	FILE *f = NULL;
1147 	size_t n;
1148 	struct stat sb;
1149 
1150 	path_refs = get_refs_dir_path(repo, name);
1151 	if (path_refs == NULL) {
1152 		err = got_error_from_errno2("get_refs_dir_path", name);
1153 		goto done;
1154 	}
1155 
1156 	if (asprintf(&path, "%s/%s", path_refs, name) == -1) {
1157 		err = got_error_from_errno("asprintf");
1158 		goto done;
1159 	}
1160 
1161 	err = got_opentemp_named(&tmppath, &f, path, "");
1162 	if (err) {
1163 		char *parent;
1164 		if (!(err->code == GOT_ERR_ERRNO && errno == ENOENT))
1165 			goto done;
1166 		err = got_path_dirname(&parent, path);
1167 		if (err)
1168 			goto done;
1169 		err = got_path_mkdir(parent);
1170 		free(parent);
1171 		if (err)
1172 			goto done;
1173 		err = got_opentemp_named(&tmppath, &f, path, "");
1174 		if (err)
1175 			goto done;
1176 	}
1177 
1178 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
1179 		n = fprintf(f, "ref: %s\n", ref->ref.symref.ref);
1180 		if (n != strlen(ref->ref.symref.ref) + 6) {
1181 			err = got_ferror(f, GOT_ERR_IO);
1182 			goto done;
1183 		}
1184 	} else {
1185 		char *hex;
1186 		size_t len;
1187 
1188 		err = got_object_id_str(&hex, &ref->ref.ref.id);
1189 		if (err)
1190 			goto done;
1191 		len = strlen(hex);
1192 		n = fprintf(f, "%s\n", hex);
1193 		free(hex);
1194 		if (n != len + 1) {
1195 			err = got_ferror(f, GOT_ERR_IO);
1196 			goto done;
1197 		}
1198 	}
1199 
1200 	if (ref->lf == NULL) {
1201 		err = got_lockfile_lock(&lf, path, -1);
1202 		if (err)
1203 			goto done;
1204 	}
1205 
1206 	/* XXX: check if old content matches our expectations? */
1207 
1208 	if (stat(path, &sb) != 0) {
1209 		if (errno != ENOENT) {
1210 			err = got_error_from_errno2("stat", path);
1211 			goto done;
1212 		}
1213 		sb.st_mode = GOT_DEFAULT_FILE_MODE;
1214 	}
1215 
1216 	if (fchmod(fileno(f), sb.st_mode) != 0) {
1217 		err = got_error_from_errno2("fchmod", tmppath);
1218 		goto done;
1219 	}
1220 
1221 	if (rename(tmppath, path) != 0) {
1222 		err = got_error_from_errno3("rename", tmppath, path);
1223 		goto done;
1224 	}
1225 	free(tmppath);
1226 	tmppath = NULL;
1227 
1228 	if (stat(path, &sb) == -1) {
1229 		err = got_error_from_errno2("stat", path);
1230 		goto done;
1231 	}
1232 	ref->mtime = sb.st_mtime;
1233 done:
1234 	if (ref->lf == NULL && lf)
1235 		unlock_err = got_lockfile_unlock(lf, -1);
1236 	if (f) {
1237 		if (fclose(f) == EOF && err == NULL)
1238 			err = got_error_from_errno("fclose");
1239 	}
1240 	free(path_refs);
1241 	free(path);
1242 	if (tmppath) {
1243 		if (unlink(tmppath) == -1 && err == NULL)
1244 			err = got_error_from_errno2("unlink", tmppath);
1245 		free(tmppath);
1246 	}
1247 	return err ? err : unlock_err;
1248 }
1249 
1250 static const struct got_error *
1251 delete_packed_ref(struct got_reference *delref, struct got_repository *repo)
1252 {
1253 	const struct got_error *err = NULL, *unlock_err = NULL;
1254 	struct got_lockfile *lf = NULL;
1255 	FILE *f = NULL, *tmpf = NULL;
1256 	char *line = NULL, *packed_refs_path, *tmppath = NULL;
1257 	size_t linesize = 0;
1258 	struct got_reflist_head refs;
1259 	int found_delref = 0;
1260 
1261 	/* The packed-refs file does not cotain symbolic references. */
1262 	if (delref->flags & GOT_REF_IS_SYMBOLIC)
1263 		return got_error(GOT_ERR_BAD_REF_DATA);
1264 
1265 	TAILQ_INIT(&refs);
1266 
1267 	packed_refs_path = got_repo_get_path_packed_refs(repo);
1268 	if (packed_refs_path == NULL)
1269 		return got_error_from_errno("got_repo_get_path_packed_refs");
1270 
1271 	err = got_opentemp_named(&tmppath, &tmpf, packed_refs_path, "");
1272 	if (err)
1273 		goto done;
1274 
1275 	if (delref->lf == NULL) {
1276 		err = got_lockfile_lock(&lf, packed_refs_path, -1);
1277 		if (err)
1278 			goto done;
1279 	}
1280 
1281 	f = fopen(packed_refs_path, "re");
1282 	if (f == NULL) {
1283 		err = got_error_from_errno2("fopen", packed_refs_path);
1284 		goto done;
1285 	}
1286 	for (;;) {
1287 		ssize_t linelen;
1288 		struct got_reference *ref;
1289 		struct got_reflist_entry *new;
1290 
1291 		linelen = getline(&line, &linesize, f);
1292 		if (linelen == -1) {
1293 			if (feof(f))
1294 				break;
1295 			err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
1296 			goto done;
1297 		}
1298 		if (linelen > 0 && line[linelen - 1] == '\n')
1299 			line[linelen - 1] = '\0';
1300 		err = parse_packed_ref_line(&ref, NULL, line, 0,
1301 		    got_repo_get_object_format(repo));
1302 		if (err)
1303 			goto done;
1304 		if (ref == NULL)
1305 			continue;
1306 
1307 		if (strcmp(ref->ref.ref.name, delref->ref.ref.name) == 0 &&
1308 		    got_object_id_cmp(&ref->ref.ref.id,
1309 		    &delref->ref.ref.id) == 0) {
1310 			found_delref = 1;
1311 			got_ref_close(ref);
1312 			continue;
1313 		}
1314 
1315 		err = got_reflist_insert(&new, &refs, ref,
1316 		    got_ref_cmp_by_name, NULL);
1317 		if (err || new == NULL /* duplicate */)
1318 			got_ref_close(ref);
1319 		if (err)
1320 			goto done;
1321 	}
1322 
1323 	if (found_delref) {
1324 		struct got_reflist_entry *re;
1325 		size_t n;
1326 		struct stat sb;
1327 
1328 		n = fprintf(tmpf, "%s\n", GOT_PACKED_REFS_HEADER);
1329 		if (n != sizeof(GOT_PACKED_REFS_HEADER)) {
1330 			err = got_ferror(f, GOT_ERR_IO);
1331 			goto done;
1332 		}
1333 
1334 		TAILQ_FOREACH(re, &refs, entry) {
1335 			char *hex;
1336 			size_t len;
1337 
1338 			err = got_object_id_str(&hex, &re->ref->ref.ref.id);
1339 			if (err)
1340 				goto done;
1341 			len = strlen(hex);
1342 			n = fprintf(tmpf, "%s ", hex);
1343 			free(hex);
1344 			if (n != len + 1) {
1345 				err = got_ferror(f, GOT_ERR_IO);
1346 				goto done;
1347 			}
1348 
1349 			n = fprintf(tmpf, "%s\n", re->ref->ref.ref.name);
1350 			if (n != strlen(re->ref->ref.ref.name) + 1) {
1351 				err = got_ferror(f, GOT_ERR_IO);
1352 				goto done;
1353 			}
1354 		}
1355 
1356 		if (fflush(tmpf) != 0) {
1357 			err = got_error_from_errno("fflush");
1358 			goto done;
1359 		}
1360 
1361 		if (fstat(fileno(f), &sb) != 0) {
1362 			if (errno != ENOENT) {
1363 				err = got_error_from_errno2("fstat",
1364 				    packed_refs_path);
1365 				goto done;
1366 			}
1367 			sb.st_mode = GOT_DEFAULT_FILE_MODE;
1368 		}
1369 
1370 		if (fchmod(fileno(tmpf), sb.st_mode) != 0) {
1371 			err = got_error_from_errno2("fchmod", tmppath);
1372 			goto done;
1373 		}
1374 
1375 		if (rename(tmppath, packed_refs_path) != 0) {
1376 			err = got_error_from_errno3("rename", tmppath,
1377 			    packed_refs_path);
1378 			goto done;
1379 		}
1380 		free(tmppath);
1381 		tmppath = NULL;
1382 	}
1383 done:
1384 	if (delref->lf == NULL && lf)
1385 		unlock_err = got_lockfile_unlock(lf, -1);
1386 	if (f) {
1387 		if (fclose(f) == EOF && err == NULL)
1388 			err = got_error_from_errno("fclose");
1389 	}
1390 	if (tmppath && unlink(tmppath) == -1 && err == NULL)
1391 		err = got_error_from_errno2("unlink", tmppath);
1392 	if (tmpf && fclose(tmpf) == EOF && err == NULL)
1393 		err = got_error_from_errno("fclose");
1394 	free(tmppath);
1395 	free(packed_refs_path);
1396 	free(line);
1397 	got_ref_list_free(&refs);
1398 	return err ? err : unlock_err;
1399 }
1400 
1401 static const struct got_error *
1402 delete_loose_ref(struct got_reference *ref, struct got_repository *repo)
1403 {
1404 	const struct got_error *err = NULL, *unlock_err = NULL;
1405 	const char *name = got_ref_get_name(ref);
1406 	char *path_refs = NULL, *path = NULL;
1407 	struct got_lockfile *lf = NULL;
1408 
1409 	path_refs = get_refs_dir_path(repo, name);
1410 	if (path_refs == NULL) {
1411 		err = got_error_from_errno2("get_refs_dir_path", name);
1412 		goto done;
1413 	}
1414 
1415 	if (asprintf(&path, "%s/%s", path_refs, name) == -1) {
1416 		err = got_error_from_errno("asprintf");
1417 		goto done;
1418 	}
1419 
1420 	if (ref->lf == NULL) {
1421 		err = got_lockfile_lock(&lf, path, -1);
1422 		if (err)
1423 			goto done;
1424 	}
1425 
1426 	/* XXX: check if old content matches our expectations? */
1427 
1428 	if (unlink(path) == -1)
1429 		err = got_error_from_errno2("unlink", path);
1430 done:
1431 	if (ref->lf == NULL && lf)
1432 		unlock_err = got_lockfile_unlock(lf, -1);
1433 
1434 	free(path_refs);
1435 	free(path);
1436 	return err ? err : unlock_err;
1437 }
1438 
1439 const struct got_error *
1440 got_ref_delete(struct got_reference *ref, struct got_repository *repo)
1441 {
1442 	const struct got_error *err = NULL;
1443 	struct got_reference *ref2;
1444 
1445 	if (ref->flags & GOT_REF_IS_PACKED) {
1446 		err = delete_packed_ref(ref, repo);
1447 		if (err)
1448 			return err;
1449 
1450 		err = got_ref_open(&ref2, repo, got_ref_get_name(ref), 0);
1451 		if (err) {
1452 			if (err->code == GOT_ERR_NOT_REF)
1453 				return NULL;
1454 			return err;
1455 		}
1456 
1457 		err = delete_loose_ref(ref2, repo);
1458 		got_ref_close(ref2);
1459 		return err;
1460 	} else {
1461 		err = delete_loose_ref(ref, repo);
1462 		if (err)
1463 			return err;
1464 
1465 		err = got_ref_open(&ref2, repo, got_ref_get_name(ref), 0);
1466 		if (err) {
1467 			if (err->code == GOT_ERR_NOT_REF)
1468 				return NULL;
1469 			return err;
1470 		}
1471 
1472 		err = delete_packed_ref(ref2, repo);
1473 		got_ref_close(ref2);
1474 		return err;
1475 	}
1476 }
1477 
1478 const struct got_error *
1479 got_ref_unlock(struct got_reference *ref)
1480 {
1481 	const struct got_error *err;
1482 	err = got_lockfile_unlock(ref->lf, -1);
1483 	ref->lf = NULL;
1484 	return err;
1485 }
1486 
1487 struct got_reflist_object_id_map {
1488 	struct got_object_idset *idset;
1489 };
1490 
1491 struct got_reflist_object_id_map_entry {
1492 	struct got_reflist_head refs;
1493 };
1494 
1495 static const struct got_error *
1496 add_object_id_map_entry(struct got_object_idset *idset,
1497     struct got_object_id *id, struct got_reflist_entry *re)
1498 {
1499 	const struct got_error *err = NULL;
1500 	struct got_reflist_object_id_map_entry *ent;
1501 	struct got_reflist_entry *new;
1502 
1503 	ent = got_object_idset_get(idset, id);
1504 	if (ent == NULL) {
1505 		ent = malloc(sizeof(*ent));
1506 		if (ent == NULL)
1507 			return got_error_from_errno("malloc");
1508 
1509 		TAILQ_INIT(&ent->refs);
1510 		err = got_object_idset_add(idset, id, ent);
1511 		if (err) {
1512 			free(ent);
1513 			return err;
1514 		}
1515 	}
1516 
1517 	err = got_reflist_entry_dup(&new, re);
1518 	if (err)
1519 		return err;
1520 
1521 	TAILQ_INSERT_TAIL(&ent->refs, new, entry);
1522 	return NULL;
1523 }
1524 
1525 const struct got_error *
1526 got_reflist_object_id_map_create(struct got_reflist_object_id_map **map,
1527     struct got_reflist_head *refs, struct got_repository *repo)
1528 {
1529 	const struct got_error *err = NULL;
1530 	struct got_object_idset *idset;
1531 	struct got_object_id *id = NULL;
1532 	struct got_reflist_entry *re;
1533 
1534 	idset = got_object_idset_alloc();
1535 	if (idset == NULL)
1536 		return got_error_from_errno("got_object_idset_alloc");
1537 
1538 	*map = malloc(sizeof(**map));
1539 	if (*map == NULL) {
1540 		got_object_idset_free(idset);
1541 		return got_error_from_errno("malloc");
1542 	}
1543 	(*map)->idset = idset;
1544 
1545 	TAILQ_FOREACH(re, refs, entry) {
1546 		struct got_tag_object *tag = NULL;
1547 
1548 		err = got_ref_resolve(&id, repo, re->ref);
1549 		if (err)
1550 			goto done;
1551 
1552 		err = add_object_id_map_entry(idset, id, re);
1553 		if (err)
1554 			goto done;
1555 
1556 		if (strstr(got_ref_get_name(re->ref), "/tags/") == NULL) {
1557 			free(id);
1558 			id = NULL;
1559 			continue;
1560 		}
1561 
1562 		err = got_object_open_as_tag(&tag, repo, id);
1563 		if (err) {
1564 			if (err->code != GOT_ERR_OBJ_TYPE)
1565 				goto done;
1566 			/* Ref points at something other than a tag. */
1567 			err = NULL;
1568 			tag = NULL;
1569 			free(id);
1570 			id = NULL;
1571 			continue;
1572 		}
1573 
1574 		err = add_object_id_map_entry(idset,
1575 		    got_object_tag_get_object_id(tag), re);
1576 		got_object_tag_close(tag);
1577 		if (err)
1578 			goto done;
1579 
1580 		free(id);
1581 		id = NULL;
1582 	}
1583 done:
1584 	free(id);
1585 	if (err) {
1586 		got_reflist_object_id_map_free(*map);
1587 		*map = NULL;
1588 	}
1589 	return err;
1590 }
1591 
1592 struct got_reflist_head *
1593 got_reflist_object_id_map_lookup(struct got_reflist_object_id_map *map,
1594     struct got_object_id *id)
1595 {
1596 	struct got_reflist_object_id_map_entry *ent;
1597 	ent = got_object_idset_get(map->idset, id);
1598 	if (ent)
1599 		return &ent->refs;
1600 	return NULL;
1601 }
1602 
1603 static const struct got_error *
1604 free_id_map_entry(struct got_object_id *id, void *data, void *arg)
1605 {
1606 	struct got_reflist_object_id_map_entry *ent = data;
1607 
1608 	got_ref_list_free(&ent->refs);
1609 	free(ent);
1610 	return NULL;
1611 }
1612 
1613 void
1614 got_reflist_object_id_map_free(struct got_reflist_object_id_map *map)
1615 {
1616 	got_object_idset_for_each(map->idset, free_id_map_entry, NULL);
1617 	got_object_idset_free(map->idset);
1618 	free(map);
1619 }