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Date:: Sun Oct 17 15:49:30 2021 UTC
Message:: portable: tree/queue header fixes sys/{tree,queue}.h are looked up via configure, and therefore are included via that mechanism.
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1 /*
2  * Copyright (c) 2020 Ori Bernstein
3  * Copyright (c) 2021 Stefan Sperling <stsp@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/uio.h>
20 #include <sys/stat.h>
21 
22 #include <stdint.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 #include <limits.h>
27 #include <zlib.h>
28 
29 #if defined(__FreeBSD__)
30 #include <unistd.h>
31 #endif
32 
33 #include "got_error.h"
34 #include "got_cancel.h"
35 #include "got_object.h"
36 #include "got_path.h"
37 #include "got_reference.h"
38 #include "got_repository_admin.h"
39 #include "got_opentemp.h"
40 
41 #include "got_lib_deltify.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_object.h"
44 #include "got_lib_object_idset.h"
45 #include "got_lib_object_cache.h"
46 #include "got_lib_deflate.h"
47 #include "got_lib_pack.h"
48 #include "got_lib_privsep.h"
49 #include "got_lib_repository.h"
50 
51 #ifndef MIN
52 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
53 #endif
54 
55 #ifndef MAX
56 #define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
57 #endif
58 
59 struct got_pack_meta {
60 	struct got_object_id id;
61 	char	*path;
62 	int	obj_type;
63 	off_t	size;
64 	time_t	mtime;
65 
66 	/* The best delta we picked */
67 	struct got_pack_meta *head;
68 	struct got_pack_meta *prev;
69 	off_t	delta_offset;	/* offset in delta cache file */
70 	off_t	delta_len;	/* length in delta cache file */
71 	int	nchain;
72 
73 	/* Only used for delta window */
74 	struct got_delta_table *dtab;
75 
76 	/* Only used for writing offset deltas */
77 	off_t	off;
78 };
79 
80 struct got_pack_metavec {
81 	struct got_pack_meta **meta;
82 	int nmeta;
83 	int metasz;
84 };
85 
86 static const struct got_error *
87 alloc_meta(struct got_pack_meta **new, struct got_object_id *id,
88     const char *path, int obj_type, time_t mtime)
89 {
90 	const struct got_error *err = NULL;
91 	struct got_pack_meta *m;
92 
93 	*new = NULL;
94 
95 	m = calloc(1, sizeof(*m));
96 	if (m == NULL)
97 		return got_error_from_errno("calloc");
98 
99 	memcpy(&m->id, id, sizeof(m->id));
100 
101 	m->path = strdup(path);
102 	if (m->path == NULL) {
103 		err = got_error_from_errno("strdup");
104 		free(m);
105 		return err;
106 	}
107 
108 	m->obj_type = obj_type;
109 	m->mtime = mtime;
110 	*new = m;
111 	return NULL;
112 }
113 
114 static void
115 clear_meta(struct got_pack_meta *meta)
116 {
117 	if (meta == NULL)
118 		return;
119 	free(meta->path);
120 	meta->path = NULL;
121 }
122 
123 static void
124 free_nmeta(struct got_pack_meta **meta, int nmeta)
125 {
126 	int i;
127 
128 	for (i = 0; i < nmeta; i++)
129 		clear_meta(meta[i]);
130 	free(meta);
131 }
132 
133 static int
134 delta_order_cmp(const void *pa, const void *pb)
135 {
136 	struct got_pack_meta *a, *b;
137 	int cmp;
138 
139 	a = *(struct got_pack_meta **)pa;
140 	b = *(struct got_pack_meta **)pb;
141 
142 	if (a->obj_type != b->obj_type)
143 		return a->obj_type - b->obj_type;
144 	cmp = strcmp(a->path, b->path);
145 	if (cmp != 0)
146 		return cmp;
147 	if (a->mtime != b->mtime)
148 		return a->mtime - b->mtime;
149 	return got_object_id_cmp(&a->id, &b->id);
150 }
151 
152 static int
153 delta_size(struct got_delta_instruction *deltas, int ndeltas)
154 {
155 	int i, size = 32;
156 	for (i = 0; i < ndeltas; i++) {
157 		if (deltas[i].copy)
158 			size += GOT_DELTA_SIZE_SHIFT;
159 		else
160 			size += deltas[i].len + 1;
161 	}
162 	return size;
163 }
164 
165 static const struct got_error *
166 encode_delta(struct got_pack_meta *m, struct got_raw_object *o,
167     struct got_delta_instruction *deltas, int ndeltas,
168     off_t base_size, FILE *f)
169 {
170 	unsigned char buf[16], *bp;
171 	int i, j;
172 	off_t n;
173 	size_t w;
174 	struct got_delta_instruction *d;
175 
176 	/* base object size */
177 	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
178 	n = base_size >> GOT_DELTA_SIZE_SHIFT;
179 	for (i = 1; n > 0; i++) {
180 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
181 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
182 		n >>= GOT_DELTA_SIZE_SHIFT;
183 	}
184 	w = fwrite(buf, 1, i, f);
185 	if (w != i)
186 		return got_ferror(f, GOT_ERR_IO);
187 
188 	/* target object size */
189 	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
190 	n = o->size >> GOT_DELTA_SIZE_SHIFT;
191 	for (i = 1; n > 0; i++) {
192 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
193 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
194 		n >>= GOT_DELTA_SIZE_SHIFT;
195 	}
196 	w = fwrite(buf, 1, i, f);
197 	if (w != i)
198 		return got_ferror(f, GOT_ERR_IO);
199 
200 	for (j = 0; j < ndeltas; j++) {
201 		d = &deltas[j];
202 		if (d->copy) {
203 			n = d->offset;
204 			bp = &buf[1];
205 			buf[0] = GOT_DELTA_BASE_COPY;
206 			for (i = 0; i < 4; i++) {
207 				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
208 				buf[0] |= 1 << i;
209 				*bp++ = n & 0xff;
210 				n >>= 8;
211 				if (n == 0)
212 					break;
213 			}
214 
215 			n = d->len;
216 			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
217 				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
218 				for (i = 0; i < 3 && n > 0; i++) {
219 					buf[0] |= 1 << (i + 4);
220 					*bp++ = n & 0xff;
221 					n >>= 8;
222 				}
223 			}
224 			w = fwrite(buf, 1, bp - buf, f);
225 			if (w != bp - buf)
226 				return got_ferror(f, GOT_ERR_IO);
227 		} else {
228 			char content[128];
229 			size_t r;
230 			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
231 				return got_error_from_errno("fseeko");
232 			n = 0;
233 			while (n != d->len) {
234 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
235 				w = fwrite(buf, 1, 1, f);
236 				if (w != 1)
237 					return got_ferror(f, GOT_ERR_IO);
238 				r = fread(content, 1, buf[0], o->f);
239 				if (r != buf[0])
240 					return got_ferror(o->f, GOT_ERR_IO);
241 				w = fwrite(content, 1, buf[0], f);
242 				if (w != buf[0])
243 					return got_ferror(f, GOT_ERR_IO);
244 				n += buf[0];
245 			}
246 		}
247 	}
248 
249 	return NULL;
250 }
251 
252 
253 static const struct got_error *
254 pick_deltas(struct got_pack_meta **meta, int nmeta, int nours,
255     FILE *delta_cache, struct got_repository *repo,
256     got_pack_progress_cb progress_cb, void *progress_arg,
257     got_cancel_cb cancel_cb, void *cancel_arg)
258 {
259 	const struct got_error *err = NULL;
260 	struct got_pack_meta *m = NULL, *base = NULL;
261 	struct got_raw_object *raw = NULL, *base_raw = NULL;
262 	struct got_delta_instruction *deltas = NULL, *best_deltas = NULL;
263 	int i, j, size, best_size, ndeltas, best_ndeltas;
264 	const int max_base_candidates = 10;
265 	int outfd = -1;
266 
267 	qsort(meta, nmeta, sizeof(struct got_pack_meta *), delta_order_cmp);
268 	for (i = 0; i < nmeta; i++) {
269 		if (cancel_cb) {
270 			err = (*cancel_cb)(cancel_arg);
271 			if (err)
272 				break;
273 		}
274 		if (progress_cb) {
275 			err = progress_cb(progress_arg, 0L, nours, nmeta, i, 0);
276 			if (err)
277 				goto done;
278 		}
279 		m = meta[i];
280 
281 		if (m->obj_type == GOT_OBJ_TYPE_COMMIT ||
282 		    m->obj_type == GOT_OBJ_TYPE_TAG)
283 			continue;
284 
285 		err = got_object_raw_open(&raw, &outfd, repo, &m->id);
286 		if (err)
287 			goto done;
288 		m->size = raw->size;
289 
290 		err = got_deltify_init(&m->dtab, raw->f, raw->hdrlen,
291 		    raw->size + raw->hdrlen);
292 		if (err)
293 			goto done;
294 
295 		if (i > max_base_candidates) {
296 			struct got_pack_meta *n = NULL;
297 			n = meta[i - (max_base_candidates + 1)];
298 			got_deltify_free(n->dtab);
299 			n->dtab = NULL;
300 		}
301 
302 		best_size = raw->size;
303 		best_ndeltas = 0;
304 		for (j = MAX(0, i - max_base_candidates); j < i; j++) {
305 			if (cancel_cb) {
306 				err = (*cancel_cb)(cancel_arg);
307 				if (err)
308 					goto done;
309 			}
310 			base = meta[j];
311 			/* long chains make unpacking slow, avoid such bases */
312 			if (base->nchain >= 32 ||
313 			    base->obj_type != m->obj_type)
314 				continue;
315 
316 			err = got_object_raw_open(&base_raw, &outfd, repo,
317 			    &base->id);
318 			if (err)
319 				goto done;
320 			err = got_deltify(&deltas, &ndeltas,
321 			    raw->f, raw->hdrlen, raw->size + raw->hdrlen,
322 			    base->dtab, base_raw->f, base_raw->hdrlen,
323 			    base_raw->size + base_raw->hdrlen);
324 			got_object_raw_close(base_raw);
325 			base_raw = NULL;
326 			if (err)
327 				goto done;
328 
329 			size = delta_size(deltas, ndeltas);
330 			if (size + 32 < best_size){
331 				/*
332 				 * if we already picked a best delta,
333 				 * replace it.
334 				 */
335 				best_size = size;
336 				free(best_deltas);
337 				best_deltas = deltas;
338 				best_ndeltas = ndeltas;
339 				deltas = NULL;
340 				m->nchain = base->nchain + 1;
341 				m->prev = base;
342 				m->head = base->head;
343 				if (m->head == NULL)
344 					m->head = base;
345 			} else {
346 				free(deltas);
347 				deltas = NULL;
348 				ndeltas = 0;
349 			}
350 		}
351 
352 		if (best_ndeltas > 0) {
353 			m->delta_offset = ftello(delta_cache);
354 			err = encode_delta(m, raw, best_deltas,
355 			    best_ndeltas, m->prev->size, delta_cache);
356 			free(best_deltas);
357 			best_deltas = NULL;
358 			best_ndeltas = 0;
359 			if (err)
360 				goto done;
361 			m->delta_len = ftello(delta_cache) - m->delta_offset;
362 		}
363 
364 		got_object_raw_close(raw);
365 		raw = NULL;
366 	}
367 done:
368 	for (i = MAX(0, nmeta - max_base_candidates); i < nmeta; i++) {
369 		got_deltify_free(meta[i]->dtab);
370 		meta[i]->dtab = NULL;
371 	}
372 	if (raw)
373 		got_object_raw_close(raw);
374 	if (base_raw)
375 		got_object_raw_close(base_raw);
376 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
377 		err = got_error_from_errno("close");
378 	free(deltas);
379 	free(best_deltas);
380 	return err;
381 }
382 
383 static const struct got_error *
384 search_packidx(int *found, struct got_object_id *id,
385     struct got_repository *repo)
386 {
387 	const struct got_error *err = NULL;
388 	struct got_packidx *packidx = NULL;
389 	int idx;
390 
391 	*found = 0;
392 
393 	err = got_repo_search_packidx(&packidx, &idx, repo, id);
394 	if (err == NULL)
395 		*found = 1; /* object is already packed */
396 	else if (err->code == GOT_ERR_NO_OBJ)
397 		err = NULL;
398 	return err;
399 }
400 
401 static const int obj_types[] = {
402 	GOT_OBJ_TYPE_ANY,
403 	GOT_OBJ_TYPE_COMMIT,
404 	GOT_OBJ_TYPE_TREE,
405 	GOT_OBJ_TYPE_BLOB,
406 	GOT_OBJ_TYPE_TAG,
407 	GOT_OBJ_TYPE_OFFSET_DELTA,
408 	GOT_OBJ_TYPE_REF_DELTA
409 };
410 
411 static const struct got_error *
412 add_meta(struct got_pack_metavec *v, struct got_object_idset *idset,
413     struct got_object_id *id, const char *path, int obj_type,
414     time_t mtime, int loose_obj_only, struct got_repository *repo)
415 {
416 	const struct got_error *err;
417 	struct got_pack_meta *m;
418 
419 	if (loose_obj_only) {
420 		int is_packed;
421 		err = search_packidx(&is_packed, id, repo);
422 		if (err)
423 			return err;
424 		if (is_packed)
425 			return NULL;
426 	}
427 
428 	err = got_object_idset_add(idset, id, (void *)&obj_types[obj_type]);
429 	if (err)
430 		return err;
431 
432 	if (v == NULL)
433 		return NULL;
434 
435 	err = alloc_meta(&m, id, path, obj_type, mtime);
436 	if (err)
437 		goto done;
438 
439 	if (v->nmeta == v->metasz){
440 		size_t newsize = 2 * v->metasz;
441 		struct got_pack_meta **new;
442 		new = reallocarray(v->meta, newsize, sizeof(*new));
443 		if (new == NULL) {
444 			err = got_error_from_errno("reallocarray");
445 			goto done;
446 		}
447 		v->meta = new;
448 		v->metasz = newsize; 
449 	}
450 done:
451 	if (err) {
452 		clear_meta(m);
453 		free(m);
454 	} else
455 		v->meta[v->nmeta++] = m;
456 
457 	return err;
458 }
459 
460 static const struct got_error *
461 load_tree_entries(struct got_object_id_queue *ids, struct got_pack_metavec *v,
462     struct got_object_idset *idset, struct got_object_id *tree_id,
463     const char *dpath, time_t mtime, struct got_repository *repo,
464     int loose_obj_only, got_cancel_cb cancel_cb, void *cancel_arg)
465 {
466 	const struct got_error *err;
467 	struct got_tree_object *tree;
468 	char *p = NULL;
469 	int i;
470 
471 	err = got_object_open_as_tree(&tree, repo, tree_id);
472 	if (err)
473 		return err;
474 
475 	for (i = 0; i < got_object_tree_get_nentries(tree); i++) {
476 		struct got_tree_entry *e = got_object_tree_get_entry(tree, i);
477 		struct got_object_id *id = got_tree_entry_get_id(e);
478 		mode_t mode = got_tree_entry_get_mode(e);
479 
480 		if (cancel_cb) {
481 			err = (*cancel_cb)(cancel_arg);
482 			if (err)
483 				break;
484 		}
485 
486 		if (got_object_tree_entry_is_submodule(e) ||
487 		    got_object_idset_contains(idset, id))
488 			continue;
489 		
490 		if (asprintf(&p, "%s%s%s", dpath, dpath[0] != '\0' ? "/" : "",
491 		    got_tree_entry_get_name(e)) == -1) {
492 			err = got_error_from_errno("asprintf");
493 			break;
494 		}
495 
496 		if (S_ISDIR(mode)) {
497 			struct got_object_qid *qid;
498 			err = got_object_qid_alloc(&qid, id);
499 			if (err)
500 				break;
501 			STAILQ_INSERT_TAIL(ids, qid, entry);
502 		} else if (S_ISREG(mode) || S_ISLNK(mode)) {
503 			err = add_meta(v, idset, id, p, GOT_OBJ_TYPE_BLOB,
504 			    mtime, loose_obj_only, repo);
505 			if (err)
506 				break;
507 		}
508 		free(p);
509 		p = NULL;
510 	}
511 
512 	got_object_tree_close(tree);
513 	free(p);
514 	return err;
515 }
516 
517 static const struct got_error *
518 load_tree(struct got_pack_metavec *v, struct got_object_idset *idset,
519     struct got_object_id *tree_id, const char *dpath, time_t mtime,
520     int loose_obj_only, struct got_repository *repo,
521     got_cancel_cb cancel_cb, void *cancel_arg)
522 {
523 	const struct got_error *err = NULL;
524 	struct got_object_id_queue tree_ids;
525 	struct got_object_qid *qid;
526 
527 	if (got_object_idset_contains(idset, tree_id))
528 		return NULL;
529 
530 	err = got_object_qid_alloc(&qid, tree_id);
531 	if (err)
532 		return err;
533 
534 	STAILQ_INIT(&tree_ids);
535 	STAILQ_INSERT_TAIL(&tree_ids, qid, entry);
536 
537 	while (!STAILQ_EMPTY(&tree_ids)) {
538 		if (cancel_cb) {
539 			err = (*cancel_cb)(cancel_arg);
540 			if (err)
541 				break;
542 		}
543 
544 		qid = STAILQ_FIRST(&tree_ids);
545 		STAILQ_REMOVE_HEAD(&tree_ids, entry);
546 
547 		if (got_object_idset_contains(idset, qid->id)) {
548 			got_object_qid_free(qid);
549 			continue;
550 		}
551 
552 		err = add_meta(v, idset, qid->id, dpath, GOT_OBJ_TYPE_TREE,
553 		    mtime, loose_obj_only, repo);
554 		if (err) {
555 			got_object_qid_free(qid);
556 			break;
557 		}
558 
559 		err = load_tree_entries(&tree_ids, v, idset, qid->id, dpath,
560 		    mtime, repo, loose_obj_only, cancel_cb, cancel_arg);
561 		got_object_qid_free(qid);
562 		if (err)
563 			break;
564 	}
565 
566 	got_object_id_queue_free(&tree_ids);
567 	return err;
568 }
569 
570 static const struct got_error *
571 load_commit(struct got_pack_metavec *v, struct got_object_idset *idset,
572     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
573     got_cancel_cb cancel_cb, void *cancel_arg)
574 {
575 	const struct got_error *err;
576 	struct got_commit_object *commit;
577 
578 	if (got_object_idset_contains(idset, id))
579 		return NULL;
580 
581 	if (loose_obj_only) {
582 		int is_packed;
583 		err = search_packidx(&is_packed, id, repo);
584 		if (err)
585 			return err;
586 		if (is_packed)
587 			return NULL;
588 	}
589 
590 	err = got_object_open_as_commit(&commit, repo, id);
591 	if (err)
592 		return err;
593 
594 	err = add_meta(v, idset, id, "", GOT_OBJ_TYPE_COMMIT,
595 	    got_object_commit_get_committer_time(commit),
596 	    loose_obj_only, repo);
597 	if (err)
598 		goto done;
599 
600 	err = load_tree(v, idset, got_object_commit_get_tree_id(commit),
601 	    "", got_object_commit_get_committer_time(commit),
602 	    loose_obj_only, repo, cancel_cb, cancel_arg);
603 done:
604 	got_object_commit_close(commit);
605 	return err;
606 }
607 
608 static const struct got_error *
609 load_tag(struct got_pack_metavec *v, struct got_object_idset *idset,
610     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
611     got_cancel_cb cancel_cb, void *cancel_arg)
612 {
613 	const struct got_error *err;
614 	struct got_tag_object *tag = NULL;
615 
616 	if (got_object_idset_contains(idset, id))
617 		return NULL;
618 
619 	if (loose_obj_only) {
620 		int is_packed;
621 		err = search_packidx(&is_packed, id, repo);
622 		if (err)
623 			return err;
624 		if (is_packed)
625 			return NULL;
626 	}
627 
628 	err = got_object_open_as_tag(&tag, repo, id);
629 	if (err)
630 		return err;
631 
632 	err = add_meta(v, idset, id, "", GOT_OBJ_TYPE_TAG,
633 	    got_object_tag_get_tagger_time(tag),
634 	    loose_obj_only, repo);
635 	if (err)
636 		goto done;
637 
638 	switch (got_object_tag_get_object_type(tag)) {
639 	case GOT_OBJ_TYPE_COMMIT:
640 		err = load_commit(v, idset,
641 		    got_object_tag_get_object_id(tag), repo,
642 		    loose_obj_only, cancel_cb, cancel_arg);
643 		break;
644 	case GOT_OBJ_TYPE_TREE:
645 		err = load_tree(v, idset, got_object_tag_get_object_id(tag),
646 		    "", got_object_tag_get_tagger_time(tag),
647 		    loose_obj_only, repo, cancel_cb, cancel_arg);
648 		break;
649 	default:
650 		break;
651 	}
652 
653 done:
654 	got_object_tag_close(tag);
655 	return err;
656 }
657 
658 enum findtwixt_color {
659 	COLOR_KEEP = 0,
660 	COLOR_DROP,
661 	COLOR_BLANK,
662 };
663 static const int findtwixt_colors[] = {
664 	COLOR_KEEP,
665 	COLOR_DROP,
666 	COLOR_BLANK
667 };
668 
669 static const struct got_error *
670 queue_commit_id(struct got_object_id_queue *ids, struct got_object_id *id,
671     int color, struct got_repository *repo)
672 {
673 	const struct got_error *err;
674 	struct got_object_qid *qid;
675 
676 	err = got_object_qid_alloc(&qid, id);
677 	if (err)
678 		return err;
679 
680 	STAILQ_INSERT_TAIL(ids, qid, entry);
681 	qid->data = (void *)&findtwixt_colors[color];
682 	return NULL;
683 }
684 
685 static const struct got_error *
686 drop_commit(struct got_object_idset *keep, struct got_object_idset *drop,
687     struct got_object_id *id, struct got_repository *repo,
688     got_cancel_cb cancel_cb, void *cancel_arg)
689 {
690 	const struct got_error *err = NULL;
691 	struct got_commit_object *commit;
692 	const struct got_object_id_queue *parents;
693 	struct got_object_id_queue ids;
694 	struct got_object_qid *qid;
695 
696 	STAILQ_INIT(&ids);
697 
698 	err = got_object_qid_alloc(&qid, id);
699 	if (err)
700 		return err;
701 	STAILQ_INSERT_HEAD(&ids, qid, entry);
702 
703 	while (!STAILQ_EMPTY(&ids)) {
704 		if (cancel_cb) {
705 			err = (*cancel_cb)(cancel_arg);
706 			if (err)
707 				break;
708 		}
709 
710 		qid = STAILQ_FIRST(&ids);
711 		STAILQ_REMOVE_HEAD(&ids, entry);
712 
713 		if (got_object_idset_contains(drop, qid->id)) {
714 			got_object_qid_free(qid);
715 			continue;
716 		}
717 
718 		err = got_object_idset_add(drop, qid->id,
719 		    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
720 		if (err) {
721 			got_object_qid_free(qid);
722 			break;
723 		}
724 
725 		if (!got_object_idset_contains(keep, qid->id)) {
726 			got_object_qid_free(qid);
727 			continue;
728 		}
729 
730 		err = got_object_open_as_commit(&commit, repo, qid->id);
731 		got_object_qid_free(qid);
732 		if (err)
733 			break;
734 
735 		parents = got_object_commit_get_parent_ids(commit);
736 		if (parents) {
737 			err = got_object_id_queue_copy(parents, &ids);
738 			if (err) {
739 				got_object_commit_close(commit);
740 				break;
741 			}
742 		}
743 		got_object_commit_close(commit);
744 	}
745 
746 	got_object_id_queue_free(&ids);
747 	return err;
748 }
749 
750 struct append_id_arg {
751 	struct got_object_id **array;
752 	int idx;
753 };
754 
755 static const struct got_error *
756 append_id(struct got_object_id *id, void *data, void *arg)
757 {
758 	struct append_id_arg *a = arg;
759 
760 	a->array[a->idx] = got_object_id_dup(id);
761 	if (a->array[a->idx] == NULL)
762 		return got_error_from_errno("got_object_id_dup");
763 
764 	a->idx++;
765 	return NULL;
766 }
767 
768 static const struct got_error *
769 findtwixt(struct got_object_id ***res, int *nres,
770     struct got_object_id **head, int nhead,
771     struct got_object_id **tail, int ntail,
772     struct got_repository *repo,
773     got_cancel_cb cancel_cb, void *cancel_arg)
774 {
775 	const struct got_error *err = NULL;
776 	struct got_object_id_queue ids;
777 	struct got_object_idset *keep, *drop;
778 	struct got_object_qid *qid;
779 	int i, ncolor, nkeep, obj_type;
780 
781 	STAILQ_INIT(&ids);
782 	*res = NULL;
783 	*nres = 0;
784 
785 	keep = got_object_idset_alloc();
786 	if (keep == NULL)
787 		return got_error_from_errno("got_object_idset_alloc");
788 
789 	drop = got_object_idset_alloc();
790 	if (drop == NULL) {
791 		err = got_error_from_errno("got_object_idset_alloc");
792 		goto done;
793 	}
794 
795 	for (i = 0; i < nhead; i++) {
796 		struct got_object_id *id = head[i];
797 		if (id == NULL)
798 			continue;
799 		err = got_object_get_type(&obj_type, repo, id);
800 		if (err)
801 			return err;
802 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
803 			continue;
804 		err = queue_commit_id(&ids, id, COLOR_KEEP, repo);
805 		if (err)
806 			goto done;
807 	}		
808 	for (i = 0; i < ntail; i++) {
809 		struct got_object_id *id = tail[i];
810 		if (id == NULL)
811 			continue;
812 		err = got_object_get_type(&obj_type, repo, id);
813 		if (err)
814 			return err;
815 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
816 			continue;
817 		err = queue_commit_id(&ids, id, COLOR_DROP, repo);
818 		if (err)
819 			goto done;
820 	}
821 
822 	while (!STAILQ_EMPTY(&ids)) {
823 		int qcolor;
824 		qid = STAILQ_FIRST(&ids);
825 		qcolor = *((int *)qid->data);
826 
827 		if (got_object_idset_contains(drop, qid->id))
828 			ncolor = COLOR_DROP;
829 		else if (got_object_idset_contains(keep, qid->id))
830 			ncolor = COLOR_KEEP;
831 		else
832 			ncolor = COLOR_BLANK;
833 
834 		if (ncolor == COLOR_DROP || (ncolor == COLOR_KEEP &&
835 		    qcolor == COLOR_KEEP)) {
836 			STAILQ_REMOVE_HEAD(&ids, entry);
837 			got_object_qid_free(qid);
838 			continue;
839 		}
840 
841 		if (ncolor == COLOR_KEEP && qcolor == COLOR_DROP) {
842 			err = drop_commit(keep, drop, qid->id, repo,
843 			    cancel_cb, cancel_arg);
844 			if (err)
845 				goto done;
846 		} else if (ncolor == COLOR_BLANK) {
847 			struct got_commit_object *commit;
848 			struct got_object_id *id;
849 			const struct got_object_id_queue *parents;
850 			struct got_object_qid *pid;
851 
852 			id = got_object_id_dup(qid->id);
853 			if (id == NULL) {
854 				err = got_error_from_errno("got_object_id_dup");
855 				goto done;
856 			}
857 			if (qcolor == COLOR_KEEP)
858 				err = got_object_idset_add(keep, id,
859 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
860 			else
861 				err = got_object_idset_add(drop, id,
862 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
863 			if (err) {
864 				free(id);
865 				goto done;
866 			}
867 
868 			err = got_object_open_as_commit(&commit, repo, id);
869 			if (err) {
870 				free(id);
871 				goto done;
872 			}
873 			parents = got_object_commit_get_parent_ids(commit);
874 			if (parents) {
875 				STAILQ_FOREACH(pid, parents, entry) {
876 					err = queue_commit_id(&ids, pid->id,
877 					    qcolor, repo);
878 					if (err) {
879 						free(id);
880 						goto done;
881 					}
882 				}
883 			}
884 			got_object_commit_close(commit);
885 			commit = NULL;
886 		} else {
887 			/* should not happen */
888 			err = got_error_fmt(GOT_ERR_NOT_IMPL,
889 			    "%s ncolor=%d qcolor=%d", __func__, ncolor, qcolor);
890 			goto done;
891 		}
892 
893 		STAILQ_REMOVE_HEAD(&ids, entry);
894 		got_object_qid_free(qid);
895 	}
896 
897 	nkeep = got_object_idset_num_elements(keep);
898 	if (nkeep > 0) {
899 		struct append_id_arg arg;
900 		arg.array = calloc(nkeep, sizeof(struct got_object_id *));
901 		if (arg.array == NULL) {
902 			err = got_error_from_errno("calloc");
903 			goto done;
904 		}
905 		arg.idx = 0;
906 		err = got_object_idset_for_each(keep, append_id, &arg);
907 		if (err) {
908 			free(arg.array);
909 			goto done;
910 		}
911 		*res = arg.array;
912 		*nres = nkeep;
913 	}
914 done:
915 	got_object_idset_free(keep);
916 	got_object_idset_free(drop);
917 	got_object_id_queue_free(&ids);
918 	return err;
919 }
920 
921 static const struct got_error *
922 read_meta(struct got_pack_meta ***meta, int *nmeta,
923     struct got_object_id **theirs, int ntheirs,
924     struct got_object_id **ours, int nours, struct got_repository *repo,
925     int loose_obj_only, got_pack_progress_cb progress_cb, void *progress_arg,
926     got_cancel_cb cancel_cb, void *cancel_arg)
927 {
928 	const struct got_error *err = NULL;
929 	struct got_object_id **ids = NULL;
930 	struct got_object_idset *idset;
931 	int i, nobj = 0, obj_type;
932 	struct got_pack_metavec v;
933 
934 	*meta = NULL;
935 	*nmeta = 0;
936 
937 	idset = got_object_idset_alloc();
938 	if (idset == NULL)
939 		return got_error_from_errno("got_object_idset_alloc");
940 
941 	v.nmeta = 0;
942 	v.metasz = 64;
943 	v.meta = calloc(v.metasz, sizeof(struct got_pack_meta *));
944 	if (v.meta == NULL) {
945 		err = got_error_from_errno("calloc");
946 		goto done;
947 	}
948 
949 	err = findtwixt(&ids, &nobj, ours, nours, theirs, ntheirs, repo,
950 	    cancel_cb, cancel_arg);
951 	if (err || nobj == 0)
952 		goto done;
953 
954 	for (i = 0; i < ntheirs; i++) {
955 		struct got_object_id *id = theirs[i];
956 		if (id == NULL)
957 			continue;
958 		err = got_object_get_type(&obj_type, repo, id);
959 		if (err)
960 			return err;
961 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
962 			continue;
963 		err = load_commit(NULL, idset, id, repo,
964 		    loose_obj_only, cancel_cb, cancel_arg);
965 		if (err)
966 			goto done;
967 		if (progress_cb) {
968 			err = progress_cb(progress_arg, 0L, nours,
969 			    v.nmeta, 0, 0);
970 			if (err)
971 				goto done;
972 		}
973 	}
974 
975 	for (i = 0; i < ntheirs; i++) {
976 		struct got_object_id *id = theirs[i];
977 		int *cached_type;
978 		if (id == NULL)
979 			continue;
980 		cached_type = got_object_idset_get(idset, id);
981 		if (cached_type == NULL) {
982 			err = got_object_get_type(&obj_type, repo, id);
983 			if (err)
984 				goto done;
985 		} else
986 			obj_type = *cached_type;
987 		if (obj_type != GOT_OBJ_TYPE_TAG)
988 			continue;
989 		err = load_tag(NULL, idset, id, repo,
990 		    loose_obj_only, cancel_cb, cancel_arg);
991 		if (err)
992 			goto done;
993 		if (progress_cb) {
994 			err = progress_cb(progress_arg, 0L, nours,
995 			    v.nmeta, 0, 0);
996 			if (err)
997 				goto done;
998 		}
999 	}
1000 
1001 	for (i = 0; i < nobj; i++) {
1002 		err = load_commit(&v, idset, ids[i], repo,
1003 		    loose_obj_only, cancel_cb, cancel_arg);
1004 		if (err)
1005 			goto done;
1006 		if (progress_cb) {
1007 			err = progress_cb(progress_arg, 0L, nours,
1008 			    v.nmeta, 0, 0);
1009 			if (err)
1010 				goto done;
1011 		}
1012 	}
1013 
1014 	for (i = 0; i < nours; i++) {
1015 		struct got_object_id *id = ours[i];
1016 		int *cached_type;
1017 		if (id == NULL)
1018 			continue;
1019 		cached_type = got_object_idset_get(idset, id);
1020 		if (cached_type == NULL) {
1021 			err = got_object_get_type(&obj_type, repo, id);
1022 			if (err)
1023 				goto done;
1024 		} else
1025 			obj_type = *cached_type;
1026 		if (obj_type != GOT_OBJ_TYPE_TAG)
1027 			continue;
1028 		err = load_tag(&v, idset, id, repo,
1029 		    loose_obj_only, cancel_cb, cancel_arg);
1030 		if (err)
1031 			goto done;
1032 		if (progress_cb) {
1033 			err = progress_cb(progress_arg, 0L, nours,
1034 			    v.nmeta, 0, 0);
1035 			if (err)
1036 				goto done;
1037 		}
1038 	}
1039 
1040 done:
1041 	for (i = 0; i < nobj; i++) {
1042 		free(ids[i]);
1043 	}
1044 	free(ids);
1045 	got_object_idset_free(idset);
1046 	if (err == NULL) {
1047 		*meta = v.meta;
1048 		*nmeta = v.nmeta;
1049 	} else
1050 		free(v.meta);
1051 
1052 	return err;
1053 }
1054 
1055 const struct got_error *
1056 hwrite(FILE *f, void *buf, int len, SHA1_CTX *ctx)
1057 {
1058 	size_t n;
1059 
1060 	SHA1Update(ctx, buf, len);
1061 	n = fwrite(buf, 1, len, f);
1062 	if (n != len)
1063 		return got_ferror(f, GOT_ERR_IO);
1064 	return NULL;
1065 }
1066 
1067 static void
1068 putbe32(char *b, uint32_t n)
1069 {
1070 	b[0] = n >> 24;
1071 	b[1] = n >> 16;
1072 	b[2] = n >> 8;
1073 	b[3] = n >> 0;
1074 }
1075 
1076 static int
1077 write_order_cmp(const void *pa, const void *pb)
1078 {
1079 	struct got_pack_meta *a, *b, *ahd, *bhd;
1080 
1081 	a = *(struct got_pack_meta **)pa;
1082 	b = *(struct got_pack_meta **)pb;
1083 	ahd = (a->head == NULL) ? a : a->head;
1084 	bhd = (b->head == NULL) ? b : b->head;
1085 	if (ahd->mtime != bhd->mtime)
1086 		return bhd->mtime - ahd->mtime;
1087 	if (ahd != bhd)
1088 		return (uintptr_t)bhd - (uintptr_t)ahd;
1089 	if (a->nchain != b->nchain)
1090 		return a->nchain - b->nchain;
1091 	return a->mtime - b->mtime;
1092 }
1093 
1094 static const struct got_error *
1095 packhdr(int *hdrlen, char *hdr, size_t bufsize, int obj_type, size_t len)
1096 {
1097 	size_t i;
1098 
1099 	*hdrlen = 0;
1100 
1101 	hdr[0] = obj_type << 4;
1102 	hdr[0] |= len & 0xf;
1103 	len >>= 4;
1104 	for (i = 1; len != 0; i++){
1105 		if (i >= bufsize)
1106 			return got_error(GOT_ERR_NO_SPACE);
1107 		hdr[i - 1] |= GOT_DELTA_SIZE_MORE;
1108 		hdr[i] = len & GOT_DELTA_SIZE_VAL_MASK;
1109 		len >>= GOT_DELTA_SIZE_SHIFT;
1110 	}
1111 
1112 	*hdrlen = i;
1113 	return NULL;
1114 }
1115 
1116 static int
1117 packoff(char *hdr, off_t off)
1118 {
1119 	int i, j;
1120 	char rbuf[8];
1121 
1122 	rbuf[0] = off & GOT_DELTA_SIZE_VAL_MASK;
1123 	for (i = 1; (off >>= GOT_DELTA_SIZE_SHIFT) != 0; i++) {
1124 		rbuf[i] = (--off & GOT_DELTA_SIZE_VAL_MASK) |
1125 		    GOT_DELTA_SIZE_MORE;
1126 	}
1127 
1128 	j = 0;
1129 	while (i > 0)
1130 		hdr[j++] = rbuf[--i];
1131 	return j;
1132 }
1133 
1134 static const struct got_error *
1135 genpack(uint8_t *pack_sha1, FILE *packfile, FILE *delta_cache,
1136     struct got_pack_meta **meta, int nmeta, int nours,
1137     int use_offset_deltas, struct got_repository *repo,
1138     got_pack_progress_cb progress_cb, void *progress_arg,
1139     got_cancel_cb cancel_cb, void *cancel_arg)
1140 {
1141 	const struct got_error *err = NULL;
1142 	int i, nh;
1143 	SHA1_CTX ctx;
1144 	struct got_pack_meta *m;
1145 	struct got_raw_object *raw = NULL;
1146 	FILE *delta_file = NULL;
1147 	char buf[32];
1148 	size_t outlen, n;
1149 	struct got_deflate_checksum csum;
1150 	off_t packfile_size = 0;
1151 	int outfd = -1;
1152 
1153 	SHA1Init(&ctx);
1154 	csum.output_sha1 = &ctx;
1155 	csum.output_crc = NULL;
1156 
1157 	err = hwrite(packfile, "PACK", 4, &ctx);
1158 	if (err)
1159 		return err;
1160 	putbe32(buf, GOT_PACKFILE_VERSION);
1161 	err = hwrite(packfile, buf, 4, &ctx);
1162 	if (err)
1163 		goto done;
1164 	putbe32(buf, nmeta);
1165 	err = hwrite(packfile, buf, 4, &ctx);
1166 	if (err)
1167 		goto done;
1168 	qsort(meta, nmeta, sizeof(struct got_pack_meta *), write_order_cmp);
1169 	for (i = 0; i < nmeta; i++) {
1170 		if (progress_cb) {
1171 			err = progress_cb(progress_arg, packfile_size, nours,
1172 			    nmeta, nmeta, i);
1173 			if (err)
1174 				goto done;
1175 		}
1176 		m = meta[i];
1177 		m->off = ftello(packfile);
1178 		err = got_object_raw_open(&raw, &outfd, repo, &m->id);
1179 		if (err)
1180 			goto done;
1181 		if (m->delta_len == 0) {
1182 			err = packhdr(&nh, buf, sizeof(buf),
1183 			    m->obj_type, raw->size);
1184 			if (err)
1185 				goto done;
1186 			err = hwrite(packfile, buf, nh, &ctx);
1187 			if (err)
1188 				goto done;
1189 			packfile_size += nh;
1190 			if (fseeko(raw->f, raw->hdrlen, SEEK_SET) == -1) {
1191 				err = got_error_from_errno("fseeko");
1192 				goto done;
1193 			}
1194 			err = got_deflate_to_file(&outlen, raw->f, packfile,
1195 			    &csum);
1196 			if (err)
1197 				goto done;
1198 			packfile_size += outlen;
1199 		} else {
1200 			off_t remain;
1201 			if (delta_file == NULL) {
1202 				delta_file = got_opentemp();
1203 				if (delta_file == NULL) {
1204 					err = got_error_from_errno(
1205 					    "got_opentemp");
1206 					goto done;
1207 				}
1208 			}
1209 			if (ftruncate(fileno(delta_file), 0L) == -1) {
1210 				err = got_error_from_errno("ftruncate");
1211 				goto done;
1212 			}
1213 			if (fseeko(delta_file, 0L, SEEK_SET) == -1) {
1214 				err = got_error_from_errno("fseeko");
1215 				goto done;
1216 			}
1217 			if (fseeko(delta_cache, m->delta_offset, SEEK_SET)
1218 			    == -1) {
1219 				err = got_error_from_errno("fseeko");
1220 				goto done;
1221 			}
1222 			remain = m->delta_len;
1223 			while (remain > 0) {
1224 				char delta_buf[8192];
1225 				size_t r, w, n;
1226 				n = MIN(remain, sizeof(delta_buf));
1227 				r = fread(delta_buf, 1, n, delta_cache);
1228 				if (r != n) {
1229 					err = got_ferror(delta_cache,
1230 					    GOT_ERR_IO);
1231 					goto done;
1232 				}
1233 				w = fwrite(delta_buf, 1, n, delta_file);
1234 				if (w != n) {
1235 					err = got_ferror(delta_file,
1236 					    GOT_ERR_IO);
1237 					goto done;
1238 				}
1239 				remain -= n;
1240 			}
1241 			if (use_offset_deltas && m->prev->off != 0) {
1242 				err = packhdr(&nh, buf, sizeof(buf),
1243 				    GOT_OBJ_TYPE_OFFSET_DELTA, m->delta_len);
1244 				if (err)
1245 					goto done;
1246 				nh += packoff(buf + nh,
1247 				    m->off - m->prev->off);
1248 				err = hwrite(packfile, buf, nh, &ctx);
1249 				if (err)
1250 					goto done;
1251 				packfile_size += nh;
1252 			} else {
1253 				err = packhdr(&nh, buf, sizeof(buf),
1254 				    GOT_OBJ_TYPE_REF_DELTA, m->delta_len);
1255 				err = hwrite(packfile, buf, nh, &ctx);
1256 				if (err)
1257 					goto done;
1258 				packfile_size += nh;
1259 				err = hwrite(packfile, m->prev->id.sha1,
1260 				    sizeof(m->prev->id.sha1), &ctx);
1261 				packfile_size += sizeof(m->prev->id.sha1);
1262 				if (err)
1263 					goto done;
1264 			}
1265 			if (fseeko(delta_file, 0L, SEEK_SET) == -1) {
1266 				err = got_error_from_errno("fseeko");
1267 				goto done;
1268 			}
1269 			err = got_deflate_to_file(&outlen, delta_file,
1270 			    packfile, &csum);
1271 			if (err)
1272 				goto done;
1273 			packfile_size += outlen;
1274 		}
1275 		got_object_raw_close(raw);
1276 		raw = NULL;
1277 	}
1278 	SHA1Final(pack_sha1, &ctx);
1279 	n = fwrite(pack_sha1, 1, SHA1_DIGEST_LENGTH, packfile);
1280 	if (n != SHA1_DIGEST_LENGTH)
1281 		err = got_ferror(packfile, GOT_ERR_IO);
1282 	packfile_size += SHA1_DIGEST_LENGTH;
1283 	packfile_size += sizeof(struct got_packfile_hdr);
1284 	err = progress_cb(progress_arg, packfile_size, nours,
1285 	    nmeta, nmeta, nmeta);
1286 	if (err)
1287 		goto done;
1288 done:
1289 	if (delta_file && fclose(delta_file) == EOF && err == NULL)
1290 		err = got_error_from_errno("fclose");
1291 	if (raw)
1292 		got_object_raw_close(raw);
1293 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
1294 		err = got_error_from_errno("close");
1295 	return err;
1296 }
1297 
1298 const struct got_error *
1299 got_pack_create(uint8_t *packsha1, FILE *packfile,
1300     struct got_object_id **theirs, int ntheirs,
1301     struct got_object_id **ours, int nours,
1302     struct got_repository *repo, int loose_obj_only, int allow_empty,
1303     got_pack_progress_cb progress_cb, void *progress_arg,
1304     got_cancel_cb cancel_cb, void *cancel_arg)
1305 {
1306 	const struct got_error *err;
1307 	struct got_pack_meta **meta;
1308 	int nmeta;
1309 	FILE *delta_cache = NULL;
1310 
1311 	err = read_meta(&meta, &nmeta, theirs, ntheirs, ours, nours, repo,
1312 	    loose_obj_only, progress_cb, progress_arg, cancel_cb, cancel_arg);
1313 	if (err)
1314 		return err;
1315 
1316 	if (nmeta == 0 && !allow_empty) {
1317 		err = got_error(GOT_ERR_CANNOT_PACK);
1318 		goto done;
1319 	}
1320 
1321 	delta_cache = got_opentemp();
1322 	if (delta_cache == NULL) {
1323 		err = got_error_from_errno("got_opentemp");
1324 		goto done;
1325 	}
1326 
1327 	if (nmeta > 0) {
1328 		err = pick_deltas(meta, nmeta, nours, delta_cache, repo,
1329 		    progress_cb, progress_arg, cancel_cb, cancel_arg);
1330 		if (err)
1331 			goto done;
1332 		if (fseeko(delta_cache, 0L, SEEK_SET) == -1) {
1333 			err = got_error_from_errno("fseeko");
1334 			goto done;
1335 		}
1336 	}
1337 
1338 	err = genpack(packsha1, packfile, delta_cache, meta, nmeta, nours, 1,
1339 	    repo, progress_cb, progress_arg, cancel_cb, cancel_arg);
1340 	if (err)
1341 		goto done;
1342 done:
1343 	free_nmeta(meta, nmeta);
1344 	if (delta_cache && fclose(delta_cache) == EOF && err == NULL)
1345 		err = got_error_from_errno("fclose");
1346 	return err;
1347 }