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 <sys/types.h>
18 #include <sys/stat.h>
19 
20 #include <errno.h>
21 #include <ctype.h>
22 #include <dirent.h>
23 #include <limits.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 #include <zlib.h>
29 #include <time.h>
30 #include <libgen.h>
31 
32 #include "got_compat.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_sha1.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 	u_int8_t sha1[SHA1_DIGEST_LENGTH];
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 	/* Cached timestamp for got_ref_cmp_by_commit_timestamp_descending() */
92 	time_t committer_time;
93 };
94 
95 static const struct got_error *
96 alloc_ref(struct got_reference **ref, const char *name,
97     struct got_object_id *id, int flags, time_t mtime)
98 {
99 	const struct got_error *err = NULL;
100 
101 	*ref = calloc(1, sizeof(**ref));
102 	if (*ref == NULL)
103 		return got_error_from_errno("calloc");
104 
105 	memcpy((*ref)->ref.ref.sha1, id->sha1, sizeof((*ref)->ref.ref.sha1));
106 	(*ref)->flags = flags;
107 	(*ref)->ref.ref.name = strdup(name);
108 	(*ref)->mtime = mtime;
109 	if ((*ref)->ref.ref.name == NULL) {
110 		err = got_error_from_errno("strdup");
111 		got_ref_close(*ref);
112 		*ref = NULL;
113 	}
114 	return err;
115 }
116 
117 static const struct got_error *
118 alloc_symref(struct got_reference **ref, const char *name,
119     const char *target_ref, int flags)
120 {
121 	const struct got_error *err = NULL;
122 
123 	*ref = calloc(1, sizeof(**ref));
124 	if (*ref == NULL)
125 		return got_error_from_errno("calloc");
126 
127 	(*ref)->flags = GOT_REF_IS_SYMBOLIC | flags;
128 	(*ref)->ref.symref.name = strdup(name);
129 	if ((*ref)->ref.symref.name == NULL) {
130 		err = got_error_from_errno("strdup");
131 		got_ref_close(*ref);
132 		*ref = NULL;
133 		return err;
134 	}
135 	(*ref)->ref.symref.ref = strdup(target_ref);
136 	if ((*ref)->ref.symref.ref == NULL) {
137 		err = got_error_from_errno("strdup");
138 		got_ref_close(*ref);
139 		*ref = NULL;
140 	}
141 	return err;
142 }
143 
144 static const struct got_error *
145 parse_symref(struct got_reference **ref, const char *name, const char *line)
146 {
147 	if (line[0] == '\0')
148 		return got_error(GOT_ERR_BAD_REF_DATA);
149 
150 	return alloc_symref(ref, name, line, 0);
151 }
152 
153 static const struct got_error *
154 parse_ref_line(struct got_reference **ref, const char *name, const char *line,
155     time_t mtime)
156 {
157 	struct got_object_id id;
158 
159 	if (strncmp(line, "ref: ", 5) == 0) {
160 		line += 5;
161 		return parse_symref(ref, name, line);
162 	}
163 
164 	if (!got_parse_sha1_digest(id.sha1, line))
165 		return got_error(GOT_ERR_BAD_REF_DATA);
166 
167 	return alloc_ref(ref, name, &id, 0, mtime);
168 }
169 
170 static const struct got_error *
171 parse_ref_file(struct got_reference **ref, const char *name,
172     const char *absname, const char *abspath, int lock)
173 {
174 	const struct got_error *err = NULL;
175 	FILE *f;
176 	char *line = NULL;
177 	size_t linesize = 0;
178 	ssize_t linelen;
179 	struct got_lockfile *lf = NULL;
180 	struct stat sb;
181 
182 	if (lock) {
183 		err = got_lockfile_lock(&lf, abspath, -1);
184 		if (err) {
185 			if (err->code == GOT_ERR_ERRNO && errno == ENOENT)
186 				err = got_error_not_ref(name);
187 			return err;
188 		}
189 	}
190 
191 	f = fopen(abspath, "rb");
192 	if (f == NULL) {
193 		if (errno != ENOTDIR && errno != ENOENT)
194 			err = got_error_from_errno2("fopen", abspath);
195 		else
196 			err = got_error_not_ref(name);
197 		if (lock)
198 			got_lockfile_unlock(lf, -1);
199 		return err;
200 	}
201 	if (fstat(fileno(f), &sb) == -1) {
202 		err = got_error_from_errno2("fstat", abspath);
203 		goto done;
204 	}
205 
206 	linelen = getline(&line, &linesize, f);
207 	if (linelen == -1) {
208 		if (feof(f))
209 			err = NULL; /* ignore empty files (could be locks) */
210 		else {
211 			if (errno == EISDIR)
212 				err = got_error(GOT_ERR_NOT_REF);
213 			else if (ferror(f))
214 				err = got_ferror(f, GOT_ERR_IO);
215 			else
216 				err = got_error_from_errno2("getline", abspath);
217 		}
218 		if (lock)
219 			got_lockfile_unlock(lf, -1);
220 		goto done;
221 	}
222 	while (linelen > 0 && line[linelen - 1] == '\n') {
223 		line[linelen - 1] = '\0';
224 		linelen--;
225 	}
226 
227 	err = parse_ref_line(ref, absname, line, sb.st_mtime);
228 	if (lock) {
229 		if (err)
230 			got_lockfile_unlock(lf, -1);
231 		else {
232 			if (*ref)
233 				(*ref)->lf = lf;
234 			else
235 				got_lockfile_unlock(lf, -1);
236 		}
237 	}
238 done:
239 	free(line);
240 	if (fclose(f) == EOF && err == NULL) {
241 		err = got_error_from_errno("fclose");
242 		if (*ref) {
243 			if (lock)
244 				got_ref_unlock(*ref);
245 			got_ref_close(*ref);
246 			*ref = NULL;
247 		}
248 	}
249 	return err;
250 }
251 
252 static int
253 is_well_known_ref(const char *refname)
254 {
255 	return (strcmp(refname, GOT_REF_HEAD) == 0 ||
256 	    strcmp(refname, GOT_REF_ORIG_HEAD) == 0 ||
257 	    strcmp(refname, GOT_REF_MERGE_HEAD) == 0 ||
258 	    strcmp(refname, GOT_REF_FETCH_HEAD) == 0);
259 }
260 
261 static char *
262 get_refs_dir_path(struct got_repository *repo, const char *refname)
263 {
264 	if (is_well_known_ref(refname) || strncmp(refname, "refs/", 5) == 0)
265 		return strdup(got_repo_get_path_git_dir(repo));
266 
267 	return got_repo_get_path_refs(repo);
268 }
269 
270 int
271 got_ref_name_is_valid(const char *name)
272 {
273 	const char *s, *seg;
274 	const char forbidden[] = { ' ', '~', '^', ':', '?', '*', '[' , '\\' };
275 	const char *forbidden_seq[] = { "//", "..", "@{" };
276 	const char *lfs = GOT_LOCKFILE_SUFFIX;
277 	const size_t lfs_len = sizeof(GOT_LOCKFILE_SUFFIX) - 1;
278 	size_t i;
279 
280 	if (name[0] == '@' && name[1] == '\0')
281 		return 0;
282 
283 	s = name;
284 	seg = s;
285 	if (seg[0] == '\0' || seg[0] == '.' || seg[0] == '/')
286 		return 0;
287 	while (*s) {
288 		for (i = 0; i < nitems(forbidden); i++) {
289 			if (*s == forbidden[i])
290 				return 0;
291 		}
292 		for (i = 0; i < nitems(forbidden_seq); i++) {
293 			if (s[0] == forbidden_seq[i][0] &&
294 			    s[1] == forbidden_seq[i][1])
295 				return 0;
296 		}
297 		if (iscntrl((unsigned char)s[0]))
298 			return 0;
299 		if (s[0] == '.' && s[1] == '\0')
300 			return 0;
301 		if (*s == '/') {
302 			const char *nextseg = s + 1;
303 			if (nextseg[0] == '\0' || nextseg[0] == '.' ||
304 			    nextseg[0] == '/')
305 				return 0;
306 			if (seg <= s - lfs_len &&
307 			    strncmp(s - lfs_len, lfs, lfs_len) == 0)
308 				return 0;
309 			seg = nextseg;
310 		}
311 		s++;
312 	}
313 
314 	if (seg <= s - lfs_len &&
315 	    strncmp(s - lfs_len, lfs, lfs_len) == 0)
316 		return 0;
317 
318 	return 1;
319 }
320 
321 const struct got_error *
322 got_ref_alloc(struct got_reference **ref, const char *name,
323     struct got_object_id *id)
324 {
325 	if (!got_ref_name_is_valid(name))
326 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
327 
328 	return alloc_ref(ref, name, id, 0, 0);
329 }
330 
331 const struct got_error *
332 got_ref_alloc_symref(struct got_reference **ref, const char *name,
333 	struct got_reference *target_ref)
334 {
335 	if (!got_ref_name_is_valid(name))
336 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
337 
338 	return alloc_symref(ref, name, got_ref_get_name(target_ref), 0);
339 }
340 
341 static const struct got_error *
342 parse_packed_ref_line(struct got_reference **ref, const char *abs_refname,
343     const char *line, time_t mtime)
344 {
345 	struct got_object_id id;
346 	const char *name;
347 
348 	*ref = NULL;
349 
350 	if (line[0] == '#' || line[0] == '^')
351 		return NULL;
352 
353 	if (!got_parse_sha1_digest(id.sha1, line))
354 		return got_error(GOT_ERR_BAD_REF_DATA);
355 
356 	if (abs_refname) {
357 		if (strcmp(line + SHA1_DIGEST_STRING_LENGTH, abs_refname) != 0)
358 			return NULL;
359 		name = abs_refname;
360 	} else
361 		name = line + SHA1_DIGEST_STRING_LENGTH;
362 
363 	return alloc_ref(ref, name, &id, GOT_REF_IS_PACKED, mtime);
364 }
365 
366 static const struct got_error *
367 open_packed_ref(struct got_reference **ref, FILE *f, const char **subdirs,
368     int nsubdirs, const char *refname, time_t mtime)
369 {
370 	const struct got_error *err = NULL;
371 	char *abs_refname;
372 	char *line = NULL;
373 	size_t linesize = 0;
374 	ssize_t linelen;
375 	int i, ref_is_absolute = (strncmp(refname, "refs/", 5) == 0);
376 
377 	*ref = NULL;
378 
379 	if (ref_is_absolute)
380 		abs_refname = (char *)refname;
381 	do {
382 		linelen = getline(&line, &linesize, f);
383 		if (linelen == -1) {
384 			if (feof(f))
385 				break;
386 			err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
387 			break;
388 		}
389 		if (linelen > 0 && line[linelen - 1] == '\n')
390 			line[linelen - 1] = '\0';
391 		for (i = 0; i < nsubdirs; i++) {
392 			if (!ref_is_absolute &&
393 			    asprintf(&abs_refname, "refs/%s/%s", subdirs[i],
394 			    refname) == -1)
395 				return got_error_from_errno("asprintf");
396 			err = parse_packed_ref_line(ref, abs_refname, line,
397 			    mtime);
398 			if (!ref_is_absolute)
399 				free(abs_refname);
400 			if (err || *ref != NULL)
401 				break;
402 		}
403 		if (err)
404 			break;
405 	} while (*ref == NULL);
406 	free(line);
407 
408 	return err;
409 }
410 
411 static const struct got_error *
412 open_ref(struct got_reference **ref, const char *path_refs, const char *subdir,
413     const char *name, int lock)
414 {
415 	const struct got_error *err = NULL;
416 	char *path = NULL;
417 	char *absname = NULL;
418 	int ref_is_absolute = (strncmp(name, "refs/", 5) == 0);
419 	int ref_is_well_known = (subdir[0] == '\0' && is_well_known_ref(name));
420 
421 	*ref = NULL;
422 
423 	if (!got_ref_name_is_valid(name))
424 		return got_error_path(name, GOT_ERR_BAD_REF_NAME);
425 
426 	if (ref_is_absolute || ref_is_well_known) {
427 		if (asprintf(&path, "%s/%s", path_refs, name) == -1)
428 			return got_error_from_errno("asprintf");
429 		absname = (char *)name;
430 	} else {
431 		if (asprintf(&path, "%s/%s%s%s", path_refs, subdir,
432 		    subdir[0] ? "/" : "", name) == -1)
433 			return got_error_from_errno("asprintf");
434 
435 		if (asprintf(&absname, "refs/%s%s%s",
436 		    subdir, subdir[0] ? "/" : "", name) == -1) {
437 			err = got_error_from_errno("asprintf");
438 			goto done;
439 		}
440 	}
441 
442 	err = parse_ref_file(ref, name, absname, path, lock);
443 done:
444 	if (!ref_is_absolute && !ref_is_well_known)
445 		free(absname);
446 	free(path);
447 	return err;
448 }
449 
450 const struct got_error *
451 got_ref_open(struct got_reference **ref, struct got_repository *repo,
452     const char *refname, int lock)
453 {
454 	const struct got_error *err = NULL;
455 	char *path_refs = NULL;
456 	const char *subdirs[] = {
457 	    GOT_REF_HEADS, GOT_REF_TAGS, GOT_REF_REMOTES
458 	};
459 	size_t i;
460 	int well_known = is_well_known_ref(refname);
461 	struct got_lockfile *lf = NULL;
462 
463 	*ref = NULL;
464 
465 	path_refs = get_refs_dir_path(repo, refname);
466 	if (path_refs == NULL) {
467 		err = got_error_from_errno2("get_refs_dir_path", refname);
468 		goto done;
469 	}
470 
471 	if (well_known) {
472 		err = open_ref(ref, path_refs, "", refname, lock);
473 	} else {
474 		char *packed_refs_path;
475 		FILE *f;
476 
477 		/* Search on-disk refs before packed refs! */
478 		for (i = 0; i < nitems(subdirs); i++) {
479 			err = open_ref(ref, path_refs, subdirs[i], refname,
480 			    lock);
481 			if ((err && err->code != GOT_ERR_NOT_REF) || *ref)
482 				goto done;
483 		}
484 
485 		packed_refs_path = got_repo_get_path_packed_refs(repo);
486 		if (packed_refs_path == NULL) {
487 			err = got_error_from_errno(
488 			    "got_repo_get_path_packed_refs");
489 			goto done;
490 		}
491 
492 		if (lock) {
493 			err = got_lockfile_lock(&lf, packed_refs_path, -1);
494 			if (err)
495 				goto done;
496 		}
497 		f = fopen(packed_refs_path, "rb");
498 		free(packed_refs_path);
499 		if (f != NULL) {
500 			struct stat sb;
501 			if (fstat(fileno(f), &sb) == -1) {
502 				err = got_error_from_errno2("fstat",
503 				    packed_refs_path);
504 				goto done;
505 			}
506 			err = open_packed_ref(ref, f, subdirs, nitems(subdirs),
507 			    refname, sb.st_mtime);
508 			if (!err) {
509 				if (fclose(f) == EOF) {
510 					err = got_error_from_errno("fclose");
511 					got_ref_close(*ref);
512 					*ref = NULL;
513 				} else if (*ref)
514 					(*ref)->lf = lf;
515 			}
516 		}
517 	}
518 done:
519 	if (!err && *ref == NULL)
520 		err = got_error_not_ref(refname);
521 	if (err && lf)
522 		got_lockfile_unlock(lf, -1);
523 	free(path_refs);
524 	return err;
525 }
526 
527 void
528 got_ref_close(struct got_reference *ref)
529 {
530 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
531 		free(ref->ref.symref.name);
532 		free(ref->ref.symref.ref);
533 	} else
534 		free(ref->ref.ref.name);
535 	free(ref);
536 }
537 
538 struct got_reference *
539 got_ref_dup(struct got_reference *ref)
540 {
541 	struct got_reference *ret;
542 
543 	ret = calloc(1, sizeof(*ret));
544 	if (ret == NULL)
545 		return NULL;
546 
547 	ret->flags = ref->flags;
548 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
549 		ret->ref.symref.name = strdup(ref->ref.symref.name);
550 		if (ret->ref.symref.name == NULL) {
551 			free(ret);
552 			return NULL;
553 		}
554 		ret->ref.symref.ref = strdup(ref->ref.symref.ref);
555 		if (ret->ref.symref.ref == NULL) {
556 			free(ret->ref.symref.name);
557 			free(ret);
558 			return NULL;
559 		}
560 	} else {
561 		ret->ref.ref.name = strdup(ref->ref.ref.name);
562 		if (ret->ref.ref.name == NULL) {
563 			free(ret);
564 			return NULL;
565 		}
566 		memcpy(ret->ref.ref.sha1, ref->ref.ref.sha1,
567 		    sizeof(ret->ref.ref.sha1));
568 	}
569 
570 	return ret;
571 }
572 
573 const struct got_error *
574 got_reflist_entry_dup(struct got_reflist_entry **newp,
575     struct got_reflist_entry *re)
576 {
577 	const struct got_error *err = NULL;
578 	struct got_reflist_entry *new;
579 
580 	*newp = NULL;
581 
582 	new = malloc(sizeof(*new));
583 	if (new == NULL)
584 		return got_error_from_errno("malloc");
585 
586 	new->ref = got_ref_dup(re->ref);
587 	if (new->ref == NULL) {
588 		err = got_error_from_errno("got_ref_dup");
589 		free(new);
590 		return err;
591 	}
592 
593 	*newp = new;
594 	return NULL;
595 }
596 
597 const struct got_error *
598 got_ref_resolve_symbolic(struct got_reference **resolved,
599     struct got_repository *repo, struct got_reference *ref)
600 {
601 	struct got_reference *nextref;
602 	const struct got_error *err;
603 
604 	err = got_ref_open(&nextref, repo, ref->ref.symref.ref, 0);
605 	if (err)
606 		return err;
607 
608 	if (nextref->flags & GOT_REF_IS_SYMBOLIC)
609 		err = got_ref_resolve_symbolic(resolved, repo, nextref);
610 	else
611 		*resolved = got_ref_dup(nextref);
612 
613 	got_ref_close(nextref);
614 	return err;
615 }
616 
617 static const struct got_error *
618 ref_resolve(struct got_object_id **id, struct got_repository *repo,
619     struct got_reference *ref, int recursion)
620 {
621 	const struct got_error *err;
622 
623 	if (recursion <= 0)
624 		return got_error_msg(GOT_ERR_RECURSION,
625 		    "reference recursion limit reached");
626 
627 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
628 		struct got_reference *resolved = NULL;
629 		err = got_ref_resolve_symbolic(&resolved, repo, ref);
630 		if (err == NULL)
631 			err = ref_resolve(id, repo, resolved, --recursion);
632 		if (resolved)
633 			got_ref_close(resolved);
634 		return err;
635 	}
636 
637 	*id = calloc(1, sizeof(**id));
638 	if (*id == NULL)
639 		return got_error_from_errno("calloc");
640 	memcpy((*id)->sha1, ref->ref.ref.sha1, sizeof((*id)->sha1));
641 	return NULL;
642 }
643 
644 const struct got_error *
645 got_ref_resolve(struct got_object_id **id, struct got_repository *repo,
646     struct got_reference *ref)
647 {
648 	return ref_resolve(id, repo, ref, GOT_REF_RECURSE_MAX);
649 }
650 
651 char *
652 got_ref_to_str(struct got_reference *ref)
653 {
654 	char *str;
655 
656 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
657 		return strdup(ref->ref.symref.ref);
658 
659 	str = malloc(SHA1_DIGEST_STRING_LENGTH);
660 	if (str == NULL)
661 		return NULL;
662 
663 	if (got_sha1_digest_to_str(ref->ref.ref.sha1, str,
664 	    SHA1_DIGEST_STRING_LENGTH) == NULL) {
665 		free(str);
666 		return NULL;
667 	}
668 
669 	return str;
670 }
671 
672 const char *
673 got_ref_get_name(struct got_reference *ref)
674 {
675 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
676 		return ref->ref.symref.name;
677 
678 	return ref->ref.ref.name;
679 }
680 
681 const char *
682 got_ref_get_symref_target(struct got_reference *ref)
683 {
684 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
685 		return ref->ref.symref.ref;
686 
687 	return NULL;
688 }
689 
690 time_t
691 got_ref_get_mtime(struct got_reference *ref)
692 {
693 	return ref->mtime;
694 }
695 
696 const struct got_error *
697 got_ref_cmp_by_name(void *arg, int *cmp, struct got_reference *re1,
698     struct got_reference* re2)
699 {
700 	const char *name1 = got_ref_get_name(re1);
701 	const char *name2 = got_ref_get_name(re2);
702 
703 	*cmp = got_path_cmp(name1, name2, strlen(name1), strlen(name2));
704 	return NULL;
705 }
706 
707 const struct got_error *
708 got_ref_cmp_tags(void *arg, int *cmp, struct got_reference *ref1,
709     struct got_reference *ref2)
710 {
711 	const struct got_error *err = NULL;
712 	struct got_repository *repo = arg;
713 	struct got_object_id *id1, *id2 = NULL;
714 	struct got_tag_object *tag1 = NULL, *tag2 = NULL;
715 	struct got_commit_object *commit1 = NULL, *commit2 = NULL;
716 	time_t time1, time2;
717 
718 	*cmp = 0;
719 
720 	err = got_ref_resolve(&id1, repo, ref1);
721 	if (err)
722 		return err;
723 	err = got_object_open_as_tag(&tag1, repo, id1);
724 	if (err) {
725 		if (err->code != GOT_ERR_OBJ_TYPE)
726 			goto done;
727 		/* "lightweight" tag */
728 		err = got_object_open_as_commit(&commit1, repo, id1);
729 		if (err)
730 			goto done;
731 		time1 = got_object_commit_get_committer_time(commit1);
732 	} else
733 		time1 = got_object_tag_get_tagger_time(tag1);
734 
735 	err = got_ref_resolve(&id2, repo, ref2);
736 	if (err)
737 		goto done;
738 	err = got_object_open_as_tag(&tag2, repo, id2);
739 	if (err) {
740 		if (err->code != GOT_ERR_OBJ_TYPE)
741 			goto done;
742 		/* "lightweight" tag */
743 		err = got_object_open_as_commit(&commit2, repo, id2);
744 		if (err)
745 			goto done;
746 		time2 = got_object_commit_get_committer_time(commit2);
747 	} else
748 		time2 = got_object_tag_get_tagger_time(tag2);
749 
750 	/* Put latest tags first. */
751 	if (time1 < time2)
752 		*cmp = 1;
753 	else if (time1 > time2)
754 		*cmp = -1;
755 	else
756 		err = got_ref_cmp_by_name(NULL, cmp, ref2, ref1);
757 done:
758 	free(id1);
759 	free(id2);
760 	if (tag1)
761 		got_object_tag_close(tag1);
762 	if (tag2)
763 		got_object_tag_close(tag2);
764 	if (commit1)
765 		got_object_commit_close(commit1);
766 	if (commit2)
767 		got_object_commit_close(commit2);
768 	return err;
769 }
770 
771 static const struct got_error *
772 get_committer_time(struct got_reference *ref, struct got_repository *repo)
773 {
774 	const struct got_error *err = NULL;
775 	int obj_type;
776 	struct got_commit_object *commit = NULL;
777 	struct got_tag_object *tag = NULL;
778 	struct got_object_id *id = NULL;
779 
780 	err = got_ref_resolve(&id, repo, ref);
781 	if (err)
782 		return err;
783 
784 	err = got_object_get_type(&obj_type, repo, id);
785 	if (err)
786 		goto done;
787 
788 	switch (obj_type) {
789 	case GOT_OBJ_TYPE_COMMIT:
790 		err = got_object_open_as_commit(&commit, repo, id);
791 		if (err)
792 			goto done;
793 		ref->committer_time =
794 		    got_object_commit_get_committer_time(commit);
795 		break;
796 	case GOT_OBJ_TYPE_TAG:
797 		err = got_object_open_as_tag(&tag, repo, id);
798 		if (err)
799 			goto done;
800 		ref->committer_time = got_object_tag_get_tagger_time(tag);
801 		break;
802 	default:
803 		/* best effort for other object types */
804 		ref->committer_time = got_ref_get_mtime(ref);
805 		break;
806 	}
807 done:
808 	free(id);
809 	if (commit)
810 		got_object_commit_close(commit);
811 	if (tag)
812 		got_object_tag_close(tag);
813 	return err;
814 }
815 
816 const struct got_error *
817 got_ref_cmp_by_commit_timestamp_descending(void *arg, int *cmp,
818     struct got_reference *ref1, struct got_reference *ref2)
819 {
820 	const struct got_error *err = NULL;
821 	struct got_repository *repo = arg;
822 
823 	*cmp = 0;
824 
825 	if (ref1->committer_time == 0) {
826 		err = get_committer_time(ref1, repo);
827 		if (err)
828 			return err;
829 	}
830 	if (ref2->committer_time == 0) {
831 		err = get_committer_time(ref2, repo);
832 		if (err)
833 			return err;
834 	}
835 
836 	if (ref1->committer_time < ref2->committer_time)
837 		*cmp = 1;
838 	else if (ref2->committer_time < ref1->committer_time)
839 		*cmp = -1;
840 	else
841 		return got_ref_cmp_by_name(arg, cmp, ref1, ref2);
842 
843 	return err;
844 }
845 
846 const struct got_error *
847 got_reflist_insert(struct got_reflist_entry **newp, struct got_reflist_head *refs,
848     struct got_reference *ref, got_ref_cmp_cb cmp_cb, void *cmp_arg)
849 {
850 	const struct got_error *err;
851 	struct got_reflist_entry *new, *re;
852 	int cmp;
853 
854 	*newp = NULL;
855 
856 	new = malloc(sizeof(*new));
857 	if (new == NULL)
858 		return got_error_from_errno("malloc");
859 	new->ref = ref;
860 	*newp = new;
861 
862 	/*
863 	 * We must de-duplicate entries on insert because packed-refs may
864 	 * contain redundant entries. On-disk refs take precedence.
865 	 * This code assumes that on-disk revs are read before packed-refs.
866 	 * We're iterating the list anyway, so insert elements sorted by name.
867 	 *
868 	 * Many callers will provide paths in a somewhat sorted order.
869 	 * Iterating backwards from the tail of the list should be more
870 	 * efficient than traversing through the entire list each time
871 	 * an element is inserted.
872 	 */
873 	re = TAILQ_LAST(refs, got_reflist_head);
874 	while (re) {
875 		err = (*cmp_cb)(cmp_arg, &cmp, re->ref, new->ref);
876 		if (err)
877 			return err;
878 		if (cmp == 0) {
879 			/* duplicate */
880 			free(new);
881 			*newp = NULL;
882 			return NULL;
883 		} else if (cmp < 0) {
884 			TAILQ_INSERT_AFTER(refs, re, new, entry);
885 			return NULL;
886 		}
887 		re = TAILQ_PREV(re, got_reflist_head, entry);
888 	}
889 
890 	TAILQ_INSERT_HEAD(refs, new, entry);
891 	return NULL;
892 }
893 
894 const struct got_error *
895 got_reflist_sort(struct got_reflist_head *refs,
896     got_ref_cmp_cb cmp_cb, void *cmp_arg)
897 {
898 	const struct got_error *err = NULL;
899 	struct got_reflist_entry *re, *tmp, *new;
900 	struct got_reflist_head sorted;
901 
902 	TAILQ_INIT(&sorted);
903 
904 	TAILQ_FOREACH_SAFE(re, refs, entry, tmp) {
905 		struct got_reference *ref = re->ref;
906 		TAILQ_REMOVE(refs, re, entry);
907 		free(re);
908 		err = got_reflist_insert(&new, &sorted, ref, cmp_cb, cmp_arg);
909 		if (err || new == NULL /* duplicate */)
910 			got_ref_close(ref);
911 		if (err)
912 			return err;
913 	}
914 
915 	TAILQ_CONCAT(refs, &sorted, entry);
916 	return NULL;
917 }
918 
919 static const struct got_error *
920 gather_on_disk_refs(struct got_reflist_head *refs, const char *path_refs,
921     const char *subdir, struct got_repository *repo,
922     got_ref_cmp_cb cmp_cb, void *cmp_arg)
923 {
924 	const struct got_error *err = NULL;
925 	DIR *d = NULL;
926 	char *path_subdir;
927 
928 	while (subdir[0] == '/')
929 		subdir++;
930 
931 	if (asprintf(&path_subdir, "%s/%s", path_refs, subdir) == -1)
932 		return got_error_from_errno("asprintf");
933 
934 	d = opendir(path_subdir);
935 	if (d == NULL)
936 		goto done;
937 
938 	for (;;) {
939 		struct dirent *dent;
940 		struct got_reference *ref;
941 		char *child;
942 		int type;
943 
944 		dent = readdir(d);
945 		if (dent == NULL)
946 			break;
947 
948 		if (strcmp(dent->d_name, ".") == 0 ||
949 		    strcmp(dent->d_name, "..") == 0)
950 			continue;
951 
952 		err = got_path_dirent_type(&type, path_subdir, dent);
953 		if (err)
954 			break;
955 
956 		switch (type) {
957 		case DT_REG:
958 			err = open_ref(&ref, path_refs, subdir, dent->d_name,
959 			    0);
960 			if (err)
961 				goto done;
962 			if (ref) {
963 				struct got_reflist_entry *new;
964 				err = got_reflist_insert(&new, refs, ref,
965 				    cmp_cb, cmp_arg);
966 				if (err || new == NULL /* duplicate */)
967 					got_ref_close(ref);
968 				if (err)
969 					goto done;
970 			}
971 			break;
972 		case DT_DIR:
973 			if (asprintf(&child, "%s%s%s", subdir,
974 			    subdir[0] == '\0' ? "" : "/", dent->d_name) == -1) {
975 				err = got_error_from_errno("asprintf");
976 				break;
977 			}
978 			err = gather_on_disk_refs(refs, path_refs, child, repo,
979 			    cmp_cb, cmp_arg);
980 			free(child);
981 			break;
982 		default:
983 			break;
984 		}
985 	}
986 done:
987 	if (d)
988 		closedir(d);
989 	free(path_subdir);
990 	return err;
991 }
992 
993 const struct got_error *
994 got_ref_list(struct got_reflist_head *refs, struct got_repository *repo,
995     const char *ref_namespace, got_ref_cmp_cb cmp_cb, void *cmp_arg)
996 {
997 	const struct got_error *err;
998 	char *packed_refs_path, *path_refs = NULL;
999 	char *abs_namespace = NULL;
1000 	char *buf = NULL, *ondisk_ref_namespace = NULL;
1001 	char *line = NULL;
1002 	FILE *f = NULL;
1003 	struct got_reference *ref;
1004 	struct got_reflist_entry *new;
1005 
1006 	if (ref_namespace == NULL || ref_namespace[0] == '\0') {
1007 		path_refs = get_refs_dir_path(repo, GOT_REF_HEAD);
1008 		if (path_refs == NULL) {
1009 			err = got_error_from_errno("get_refs_dir_path");
1010 			goto done;
1011 		}
1012 		err = open_ref(&ref, path_refs, "", GOT_REF_HEAD, 0);
1013 		if (err)
1014 			goto done;
1015 		err = got_reflist_insert(&new, refs, ref, cmp_cb, cmp_arg);
1016 		if (err || new == NULL /* duplicate */)
1017 			got_ref_close(ref);
1018 		if (err && err->code != GOT_ERR_NOT_REF)
1019 			goto done;
1020 	} else {
1021 		/* Try listing a single reference. */
1022 		const char *refname = ref_namespace;
1023 		path_refs = get_refs_dir_path(repo, refname);
1024 		if (path_refs == NULL) {
1025 			err = got_error_from_errno("get_refs_dir_path");
1026 			goto done;
1027 		}
1028 		err = open_ref(&ref, path_refs, "", refname, 0);
1029 		if (err) {
1030 			if (err->code != GOT_ERR_NOT_REF)
1031 				goto done;
1032 			/* Try to look up references in a given namespace. */
1033 		} else {
1034 			err = got_reflist_insert(&new, refs, ref,
1035 			    cmp_cb, cmp_arg);
1036 			if (err || new == NULL /* duplicate */)
1037 				got_ref_close(ref);
1038 			return err;
1039 		}
1040 	}
1041 
1042 	if (ref_namespace) {
1043 		size_t len;
1044 		/* Canonicalize the path to eliminate double-slashes if any. */
1045 		if (asprintf(&abs_namespace, "/%s", ref_namespace) == -1) {
1046 			err = got_error_from_errno("asprintf");
1047 			goto done;
1048 		}
1049 		len = strlen(abs_namespace) + 1;
1050 		buf = malloc(len);
1051 		if (buf == NULL) {
1052 			err = got_error_from_errno("malloc");
1053 			goto done;
1054 		}
1055 		err = got_canonpath(abs_namespace, buf, len);
1056 		if (err)
1057 			goto done;
1058 		ondisk_ref_namespace = buf;
1059 		while (ondisk_ref_namespace[0] == '/')
1060 			ondisk_ref_namespace++;
1061 		if (strncmp(ondisk_ref_namespace, "refs/", 5) == 0)
1062 			ondisk_ref_namespace += 5;
1063 		else if (strcmp(ondisk_ref_namespace, "refs") == 0)
1064 			ondisk_ref_namespace = "";
1065 	}
1066 
1067 	/* Gather on-disk refs before parsing packed-refs. */
1068 	free(path_refs);
1069 	path_refs = get_refs_dir_path(repo, "");
1070 	if (path_refs == NULL) {
1071 		err = got_error_from_errno("get_refs_dir_path");
1072 		goto done;
1073 	}
1074 	err = gather_on_disk_refs(refs, path_refs,
1075 	    ondisk_ref_namespace ? ondisk_ref_namespace : "", repo,
1076 	    cmp_cb, cmp_arg);
1077 	if (err)
1078 		goto done;
1079 
1080 	/*
1081 	 * The packed-refs file may contain redundant entries, in which
1082 	 * case on-disk refs take precedence.
1083 	 */
1084 	packed_refs_path = got_repo_get_path_packed_refs(repo);
1085 	if (packed_refs_path == NULL) {
1086 		err = got_error_from_errno("got_repo_get_path_packed_refs");
1087 		goto done;
1088 	}
1089 
1090 	f = fopen(packed_refs_path, "r");
1091 	free(packed_refs_path);
1092 	if (f) {
1093 		size_t linesize = 0;
1094 		ssize_t linelen;
1095 		struct stat sb;
1096 
1097 		if (fstat(fileno(f), &sb) == -1) {
1098 			err = got_error_from_errno2("fstat", packed_refs_path);
1099 			goto done;
1100 		}
1101 		for (;;) {
1102 			linelen = getline(&line, &linesize, f);
1103 			if (linelen == -1) {
1104 				if (feof(f))
1105 					break;
1106 				err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
1107 				goto done;
1108 			}
1109 			if (linelen > 0 && line[linelen - 1] == '\n')
1110 				line[linelen - 1] = '\0';
1111 			err = parse_packed_ref_line(&ref, NULL, line,
1112 			    sb.st_mtime);
1113 			if (err)
1114 				goto done;
1115 			if (ref) {
1116 				if (ref_namespace) {
1117 					const char *name;
1118 					name = got_ref_get_name(ref);
1119 					if (!got_path_is_child(name,
1120 					    ref_namespace,
1121 					    strlen(ref_namespace))) {
1122 						got_ref_close(ref);
1123 						continue;
1124 					}
1125 				}
1126 				err = got_reflist_insert(&new, refs, ref,
1127 				    cmp_cb, cmp_arg);
1128 				if (err || new == NULL /* duplicate */)
1129 					got_ref_close(ref);
1130 				if (err)
1131 					goto done;
1132 			}
1133 		}
1134 	}
1135 done:
1136 	free(abs_namespace);
1137 	free(buf);
1138 	free(line);
1139 	free(path_refs);
1140 	if (f && fclose(f) == EOF && err == NULL)
1141 		err = got_error_from_errno("fclose");
1142 	return err;
1143 }
1144 
1145 void
1146 got_ref_list_free(struct got_reflist_head *refs)
1147 {
1148 	struct got_reflist_entry *re;
1149 
1150 	while ((re = TAILQ_FIRST(refs))) {
1151 		TAILQ_REMOVE(refs, re, entry);
1152 		got_ref_close(re->ref);
1153 		free(re);
1154 	}
1155 
1156 }
1157 
1158 int
1159 got_ref_is_symbolic(struct got_reference *ref)
1160 {
1161 	return (ref->flags & GOT_REF_IS_SYMBOLIC);
1162 }
1163 
1164 const struct got_error *
1165 got_ref_change_ref(struct got_reference *ref, struct got_object_id *id)
1166 {
1167 	if (ref->flags & GOT_REF_IS_SYMBOLIC)
1168 		return got_error(GOT_ERR_BAD_REF_TYPE);
1169 
1170 	memcpy(ref->ref.ref.sha1, id->sha1, sizeof(ref->ref.ref.sha1));
1171 	return NULL;
1172 }
1173 
1174 const struct got_error *
1175 got_ref_change_symref(struct got_reference *ref, const char *refname)
1176 {
1177 	char *new_name;
1178 
1179 	if ((ref->flags & GOT_REF_IS_SYMBOLIC) == 0)
1180 		return got_error(GOT_ERR_BAD_REF_TYPE);
1181 
1182 	new_name = strdup(refname);
1183 	if (new_name == NULL)
1184 		return got_error_from_errno("strdup");
1185 
1186 	free(ref->ref.symref.ref);
1187 	ref->ref.symref.ref = new_name;
1188 	return NULL;
1189 }
1190 
1191 const struct got_error *
1192 got_ref_change_symref_to_ref(struct got_reference *symref,
1193     struct got_object_id *id)
1194 {
1195 	if ((symref->flags & GOT_REF_IS_SYMBOLIC) == 0)
1196 		return got_error(GOT_ERR_BAD_REF_TYPE);
1197 
1198 	symref->ref.ref.name = symref->ref.symref.name;
1199 	memcpy(symref->ref.ref.sha1, id->sha1, SHA1_DIGEST_LENGTH);
1200 	symref->flags &= ~GOT_REF_IS_SYMBOLIC;
1201 	return NULL;
1202 }
1203 
1204 const struct got_error *
1205 got_ref_write(struct got_reference *ref, struct got_repository *repo)
1206 {
1207 	const struct got_error *err = NULL, *unlock_err = NULL;
1208 	const char *name = got_ref_get_name(ref);
1209 	char *path_refs = NULL, *path = NULL, *tmppath = NULL;
1210 	struct got_lockfile *lf = NULL;
1211 	FILE *f = NULL;
1212 	size_t n;
1213 	struct stat sb;
1214 
1215 	path_refs = get_refs_dir_path(repo, name);
1216 	if (path_refs == NULL) {
1217 		err = got_error_from_errno2("get_refs_dir_path", name);
1218 		goto done;
1219 	}
1220 
1221 	if (asprintf(&path, "%s/%s", path_refs, name) == -1) {
1222 		err = got_error_from_errno("asprintf");
1223 		goto done;
1224 	}
1225 
1226 	err = got_opentemp_named(&tmppath, &f, path);
1227 	if (err) {
1228 		char *parent;
1229 		if (!(err->code == GOT_ERR_ERRNO && errno == ENOENT))
1230 			goto done;
1231 		err = got_path_dirname(&parent, path);
1232 		if (err)
1233 			goto done;
1234 		err = got_path_mkdir(parent);
1235 		free(parent);
1236 		if (err)
1237 			goto done;
1238 		err = got_opentemp_named(&tmppath, &f, path);
1239 		if (err)
1240 			goto done;
1241 	}
1242 
1243 	if (ref->flags & GOT_REF_IS_SYMBOLIC) {
1244 		n = fprintf(f, "ref: %s\n", ref->ref.symref.ref);
1245 		if (n != strlen(ref->ref.symref.ref) + 6) {
1246 			err = got_ferror(f, GOT_ERR_IO);
1247 			goto done;
1248 		}
1249 	} else {
1250 		char hex[SHA1_DIGEST_STRING_LENGTH];
1251 		if (got_sha1_digest_to_str(ref->ref.ref.sha1, hex,
1252 		    sizeof(hex)) == NULL) {
1253 			err = got_error(GOT_ERR_BAD_REF_DATA);
1254 			goto done;
1255 		}
1256 		n = fprintf(f, "%s\n", hex);
1257 		if (n != sizeof(hex)) {
1258 			err = got_ferror(f, GOT_ERR_IO);
1259 			goto done;
1260 		}
1261 	}
1262 
1263 	if (ref->lf == NULL) {
1264 		err = got_lockfile_lock(&lf, path, -1);
1265 		if (err)
1266 			goto done;
1267 	}
1268 
1269 	/* XXX: check if old content matches our expectations? */
1270 
1271 	if (stat(path, &sb) != 0) {
1272 		if (errno != ENOENT) {
1273 			err = got_error_from_errno2("stat", path);
1274 			goto done;
1275 		}
1276 		sb.st_mode = GOT_DEFAULT_FILE_MODE;
1277 	}
1278 
1279 	if (fchmod(fileno(f), sb.st_mode) != 0) {
1280 		err = got_error_from_errno2("fchmod", tmppath);
1281 		goto done;
1282 	}
1283 
1284 	if (rename(tmppath, path) != 0) {
1285 		err = got_error_from_errno3("rename", tmppath, path);
1286 		goto done;
1287 	}
1288 	free(tmppath);
1289 	tmppath = NULL;
1290 
1291 	if (stat(path, &sb) == -1) {
1292 		err = got_error_from_errno2("stat", path);
1293 		goto done;
1294 	}
1295 	ref->mtime = sb.st_mtime;
1296 done:
1297 	if (ref->lf == NULL && lf)
1298 		unlock_err = got_lockfile_unlock(lf, -1);
1299 	if (f) {
1300 		if (fclose(f) == EOF && err == NULL)
1301 			err = got_error_from_errno("fclose");
1302 	}
1303 	free(path_refs);
1304 	free(path);
1305 	if (tmppath) {
1306 		if (unlink(tmppath) != 0 && err == NULL)
1307 			err = got_error_from_errno2("unlink", tmppath);
1308 		free(tmppath);
1309 	}
1310 	return err ? err : unlock_err;
1311 }
1312 
1313 static const struct got_error *
1314 delete_packed_ref(struct got_reference *delref, struct got_repository *repo)
1315 {
1316 	const struct got_error *err = NULL, *unlock_err = NULL;
1317 	struct got_lockfile *lf = NULL;
1318 	FILE *f = NULL, *tmpf = NULL;
1319 	char *line = NULL, *packed_refs_path, *tmppath = NULL;
1320 	size_t linesize = 0;
1321 	struct got_reflist_head refs;
1322 	int found_delref = 0;
1323 
1324 	/* The packed-refs file does not cotain symbolic references. */
1325 	if (delref->flags & GOT_REF_IS_SYMBOLIC)
1326 		return got_error(GOT_ERR_BAD_REF_DATA);
1327 
1328 	TAILQ_INIT(&refs);
1329 
1330 	packed_refs_path = got_repo_get_path_packed_refs(repo);
1331 	if (packed_refs_path == NULL)
1332 		return got_error_from_errno("got_repo_get_path_packed_refs");
1333 
1334 	err = got_opentemp_named(&tmppath, &tmpf, packed_refs_path);
1335 	if (err)
1336 		goto done;
1337 
1338 	if (delref->lf == NULL) {
1339 		err = got_lockfile_lock(&lf, packed_refs_path, -1);
1340 		if (err)
1341 			goto done;
1342 	}
1343 
1344 	f = fopen(packed_refs_path, "r");
1345 	if (f == NULL) {
1346 		err = got_error_from_errno2("fopen", packed_refs_path);
1347 		goto done;
1348 	}
1349 	for (;;) {
1350 		ssize_t linelen;
1351 		struct got_reference *ref;
1352 		struct got_reflist_entry *new;
1353 
1354 		linelen = getline(&line, &linesize, f);
1355 		if (linelen == -1) {
1356 			if (feof(f))
1357 				break;
1358 			err = got_ferror(f, GOT_ERR_BAD_REF_DATA);
1359 			goto done;
1360 		}
1361 		if (linelen > 0 && line[linelen - 1] == '\n')
1362 			line[linelen - 1] = '\0';
1363 		err = parse_packed_ref_line(&ref, NULL, line, 0);
1364 		if (err)
1365 			goto done;
1366 		if (ref == NULL)
1367 			continue;
1368 
1369 		if (strcmp(ref->ref.ref.name, delref->ref.ref.name) == 0 &&
1370 		    memcmp(ref->ref.ref.sha1, delref->ref.ref.sha1,
1371 		    sizeof(delref->ref.ref.sha1)) == 0) {
1372 			found_delref = 1;
1373 			got_ref_close(ref);
1374 			continue;
1375 		}
1376 
1377 		err = got_reflist_insert(&new, &refs, ref,
1378 		    got_ref_cmp_by_name, NULL);
1379 		if (err || new == NULL /* duplicate */)
1380 			got_ref_close(ref);
1381 		if (err)
1382 			goto done;
1383 	}
1384 
1385 	if (found_delref) {
1386 		struct got_reflist_entry *re;
1387 		size_t n;
1388 		struct stat sb;
1389 
1390 		n = fprintf(tmpf, "%s\n", GOT_PACKED_REFS_HEADER);
1391 		if (n != sizeof(GOT_PACKED_REFS_HEADER)) {
1392 			err = got_ferror(f, GOT_ERR_IO);
1393 			goto done;
1394 		}
1395 
1396 		TAILQ_FOREACH(re, &refs, entry) {
1397 			char hex[SHA1_DIGEST_STRING_LENGTH];
1398 
1399 			if (got_sha1_digest_to_str(re->ref->ref.ref.sha1, hex,
1400 			    sizeof(hex)) == NULL) {
1401 				err = got_error(GOT_ERR_BAD_REF_DATA);
1402 				goto done;
1403 			}
1404 			n = fprintf(tmpf, "%s ", hex);
1405 			if (n != sizeof(hex)) {
1406 				err = got_ferror(f, GOT_ERR_IO);
1407 				goto done;
1408 			}
1409 			n = fprintf(tmpf, "%s\n", re->ref->ref.ref.name);
1410 			if (n != strlen(re->ref->ref.ref.name) + 1) {
1411 				err = got_ferror(f, GOT_ERR_IO);
1412 				goto done;
1413 			}
1414 		}
1415 
1416 		if (fflush(tmpf) != 0) {
1417 			err = got_error_from_errno("fflush");
1418 			goto done;
1419 		}
1420 
1421 		if (fstat(fileno(f), &sb) != 0) {
1422 			if (errno != ENOENT) {
1423 				err = got_error_from_errno2("fstat",
1424 				    packed_refs_path);
1425 				goto done;
1426 			}
1427 			sb.st_mode = GOT_DEFAULT_FILE_MODE;
1428 		}
1429 
1430 		if (fchmod(fileno(tmpf), sb.st_mode) != 0) {
1431 			err = got_error_from_errno2("fchmod", tmppath);
1432 			goto done;
1433 		}
1434 
1435 		if (rename(tmppath, packed_refs_path) != 0) {
1436 			err = got_error_from_errno3("rename", tmppath,
1437 			    packed_refs_path);
1438 			goto done;
1439 		}
1440 	}
1441 done:
1442 	if (delref->lf == NULL && lf)
1443 		unlock_err = got_lockfile_unlock(lf, -1);
1444 	if (f) {
1445 		if (fclose(f) == EOF && err == NULL)
1446 			err = got_error_from_errno("fclose");
1447 	}
1448 	if (tmpf) {
1449 		unlink(tmppath);
1450 		if (fclose(tmpf) == EOF && err == NULL)
1451 			err = got_error_from_errno("fclose");
1452 	}
1453 	free(tmppath);
1454 	free(packed_refs_path);
1455 	free(line);
1456 	got_ref_list_free(&refs);
1457 	return err ? err : unlock_err;
1458 }
1459 
1460 static const struct got_error *
1461 delete_loose_ref(struct got_reference *ref, struct got_repository *repo)
1462 {
1463 	const struct got_error *err = NULL, *unlock_err = NULL;
1464 	const char *name = got_ref_get_name(ref);
1465 	char *path_refs = NULL, *path = NULL;
1466 	struct got_lockfile *lf = NULL;
1467 
1468 	path_refs = get_refs_dir_path(repo, name);
1469 	if (path_refs == NULL) {
1470 		err = got_error_from_errno2("get_refs_dir_path", name);
1471 		goto done;
1472 	}
1473 
1474 	if (asprintf(&path, "%s/%s", path_refs, name) == -1) {
1475 		err = got_error_from_errno("asprintf");
1476 		goto done;
1477 	}
1478 
1479 	if (ref->lf == NULL) {
1480 		err = got_lockfile_lock(&lf, path, -1);
1481 		if (err)
1482 			goto done;
1483 	}
1484 
1485 	/* XXX: check if old content matches our expectations? */
1486 
1487 	if (unlink(path) != 0)
1488 		err = got_error_from_errno2("unlink", path);
1489 done:
1490 	if (ref->lf == NULL && lf)
1491 		unlock_err = got_lockfile_unlock(lf, -1);
1492 
1493 	free(path_refs);
1494 	free(path);
1495 	return err ? err : unlock_err;
1496 }
1497 
1498 const struct got_error *
1499 got_ref_delete(struct got_reference *ref, struct got_repository *repo)
1500 {
1501 	const struct got_error *err = NULL;
1502 	struct got_reference *ref2;
1503 
1504 	if (ref->flags & GOT_REF_IS_PACKED) {
1505 		err = delete_packed_ref(ref, repo);
1506 		if (err)
1507 			return err;
1508 
1509 		err = got_ref_open(&ref2, repo, got_ref_get_name(ref), 0);
1510 		if (err) {
1511 			if (err->code == GOT_ERR_NOT_REF)
1512 				return NULL;
1513 			return err;
1514 		}
1515 
1516 		err = delete_loose_ref(ref2, repo);
1517 		got_ref_close(ref2);
1518 		return err;
1519 	} else {
1520 		err = delete_loose_ref(ref, repo);
1521 		if (err)
1522 			return err;
1523 
1524 		err = got_ref_open(&ref2, repo, got_ref_get_name(ref), 0);
1525 		if (err) {
1526 			if (err->code == GOT_ERR_NOT_REF)
1527 				return NULL;
1528 			return err;
1529 		}
1530 
1531 		err = delete_packed_ref(ref2, repo);
1532 		got_ref_close(ref2);
1533 		return err;
1534 	}
1535 }
1536 
1537 const struct got_error *
1538 got_ref_unlock(struct got_reference *ref)
1539 {
1540 	const struct got_error *err;
1541 	err = got_lockfile_unlock(ref->lf, -1);
1542 	ref->lf = NULL;
1543 	return err;
1544 }
1545 
1546 struct got_reflist_object_id_map {
1547 	struct got_object_idset *idset;
1548 };
1549 
1550 struct got_reflist_object_id_map_entry {
1551 	struct got_reflist_head refs;
1552 };
1553 
1554 static const struct got_error *
1555 add_object_id_map_entry(struct got_object_idset *idset,
1556     struct got_object_id *id, struct got_reflist_entry *re)
1557 {
1558 	const struct got_error *err = NULL;
1559 	struct got_reflist_object_id_map_entry *ent;
1560 	struct got_reflist_entry *new;
1561 
1562 	ent = got_object_idset_get(idset, id);
1563 	if (ent == NULL) {
1564 		ent = malloc(sizeof(*ent));
1565 		if (ent == NULL)
1566 			return got_error_from_errno("malloc");
1567 
1568 		TAILQ_INIT(&ent->refs);
1569 		err = got_object_idset_add(idset, id, ent);
1570 		if (err)
1571 			return err;
1572 	}
1573 
1574 	err = got_reflist_entry_dup(&new, re);
1575 	if (err)
1576 		return err;
1577 
1578 	TAILQ_INSERT_TAIL(&ent->refs, new, entry);
1579 	return NULL;
1580 }
1581 
1582 const struct got_error *
1583 got_reflist_object_id_map_create(struct got_reflist_object_id_map **map,
1584     struct got_reflist_head *refs, struct got_repository *repo)
1585 {
1586 	const struct got_error *err = NULL;
1587 	struct got_object_idset *idset;
1588 	struct got_object_id *id = NULL;
1589 	struct got_reflist_entry *re;
1590 
1591 	idset = got_object_idset_alloc();
1592 	if (idset == NULL)
1593 		return got_error_from_errno("got_object_idset_alloc");
1594 
1595 	*map = malloc(sizeof(**map));
1596 	if (*map == NULL) {
1597 		got_object_idset_free(idset);
1598 		return got_error_from_errno("malloc");
1599 	}
1600 	(*map)->idset = idset;
1601 
1602 	TAILQ_FOREACH(re, refs, entry) {
1603 		struct got_tag_object *tag = NULL;
1604 
1605 		err = got_ref_resolve(&id, repo, re->ref);
1606 		if (err)
1607 			goto done;
1608 
1609 		err = add_object_id_map_entry(idset, id, re);
1610 		if (err)
1611 			goto done;
1612 
1613 		if (strstr(got_ref_get_name(re->ref), "/tags/") == NULL) {
1614 			free(id);
1615 			id = NULL;
1616 			continue;
1617 		}
1618 
1619 		err = got_object_open_as_tag(&tag, repo, id);
1620 		if (err) {
1621 			if (err->code != GOT_ERR_OBJ_TYPE)
1622 				goto done;
1623 			/* Ref points at something other than a tag. */
1624 			err = NULL;
1625 			tag = NULL;
1626 			free(id);
1627 			id = NULL;
1628 			continue;
1629 		}
1630 
1631 		err = add_object_id_map_entry(idset,
1632 		    got_object_tag_get_object_id(tag), re);
1633 		got_object_tag_close(tag);
1634 		if (err)
1635 			goto done;
1636 
1637 		free(id);
1638 		id = NULL;
1639 	}
1640 done:
1641 	free(id);
1642 	if (err) {
1643 		got_reflist_object_id_map_free(*map);
1644 		*map = NULL;
1645 	}
1646 	return err;
1647 }
1648 
1649 struct got_reflist_head *
1650 got_reflist_object_id_map_lookup(struct got_reflist_object_id_map *map,
1651     struct got_object_id *id)
1652 {
1653 	struct got_reflist_object_id_map_entry *ent;
1654 	ent = got_object_idset_get(map->idset, id);
1655 	if (ent)
1656 		return &ent->refs;
1657 	return NULL;
1658 }
1659 
1660 static const struct got_error *
1661 free_id_map_entry(struct got_object_id *id, void *data, void *arg)
1662 {
1663 	struct got_reflist_object_id_map_entry *ent = data;
1664 
1665 	got_ref_list_free(&ent->refs);
1666 	free(ent);
1667 	return NULL;
1668 }
1669 
1670 void
1671 got_reflist_object_id_map_free(struct got_reflist_object_id_map *map)
1672 {
1673 	got_object_idset_for_each(map->idset, free_id_map_entry, NULL);
1674 	got_object_idset_free(map->idset);
1675 	free(map);
1676 }