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/queue.h>
20 #include <sys/tree.h>
21 #include <sys/uio.h>
22 #include <sys/stat.h>
23 #include <sys/time.h>
24 
25 #include <endian.h>
26 #include <stdint.h>
27 #include <imsg.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <sha1.h>
32 #include <time.h>
33 #include <unistd.h>
34 #include <limits.h>
35 #include <zlib.h>
36 
37 #include "got_error.h"
38 #include "got_cancel.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_reference.h"
42 #include "got_repository_admin.h"
43 #include "got_opentemp.h"
44 
45 #include "got_lib_deltify.h"
46 #include "got_lib_delta.h"
47 #include "got_lib_object.h"
48 #include "got_lib_object_idset.h"
49 #include "got_lib_object_cache.h"
50 #include "got_lib_deflate.h"
51 #include "got_lib_pack.h"
52 #include "got_lib_privsep.h"
53 #include "got_lib_repository.h"
54 #include "got_lib_ratelimit.h"
55 
56 #ifndef MIN
57 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
58 #endif
59 
60 #ifndef MAX
61 #define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
62 #endif
63 
64 struct got_pack_meta {
65 	struct got_object_id id;
66 	char	*path;
67 	int	obj_type;
68 	off_t	size;
69 	time_t	mtime;
70 
71 	/* The best delta we picked */
72 	struct got_pack_meta *head;
73 	struct got_pack_meta *prev;
74 	unsigned char *delta_buf; /* if not encoded in delta cache file */
75 	off_t	delta_offset;	/* offset in delta cache file */
76 	off_t	delta_len;	/* encoded delta length */
77 	int	nchain;
78 
79 	int	have_reused_delta;
80 	off_t   reused_delta_offset; /* offset of delta in reused pack file */
81 	struct got_object_id *base_obj_id;
82 
83 	/* Only used for delta window */
84 	struct got_delta_table *dtab;
85 
86 	/* Only used for writing offset deltas */
87 	off_t	off;
88 };
89 
90 struct got_pack_metavec {
91 	struct got_pack_meta **meta;
92 	int nmeta;
93 	int metasz;
94 };
95 
96 static const struct got_error *
97 alloc_meta(struct got_pack_meta **new, struct got_object_id *id,
98     const char *path, int obj_type, time_t mtime)
99 {
100 	const struct got_error *err = NULL;
101 	struct got_pack_meta *m;
102 
103 	*new = NULL;
104 
105 	m = calloc(1, sizeof(*m));
106 	if (m == NULL)
107 		return got_error_from_errno("calloc");
108 
109 	memcpy(&m->id, id, sizeof(m->id));
110 
111 	m->path = strdup(path);
112 	if (m->path == NULL) {
113 		err = got_error_from_errno("strdup");
114 		free(m);
115 		return err;
116 	}
117 
118 	m->obj_type = obj_type;
119 	m->mtime = mtime;
120 	*new = m;
121 	return NULL;
122 }
123 
124 static void
125 clear_meta(struct got_pack_meta *meta)
126 {
127 	if (meta == NULL)
128 		return;
129 	free(meta->path);
130 	meta->path = NULL;
131 	free(meta->delta_buf);
132 	meta->delta_buf = NULL;
133 	free(meta->base_obj_id);
134 	meta->base_obj_id = NULL;
135 }
136 
137 static void
138 free_nmeta(struct got_pack_meta **meta, int nmeta)
139 {
140 	int i;
141 
142 	for (i = 0; i < nmeta; i++)
143 		clear_meta(meta[i]);
144 	free(meta);
145 }
146 
147 static int
148 delta_order_cmp(const void *pa, const void *pb)
149 {
150 	struct got_pack_meta *a, *b;
151 	int cmp;
152 
153 	a = *(struct got_pack_meta **)pa;
154 	b = *(struct got_pack_meta **)pb;
155 
156 	if (a->obj_type != b->obj_type)
157 		return a->obj_type - b->obj_type;
158 	cmp = strcmp(a->path, b->path);
159 	if (cmp != 0)
160 		return cmp;
161 	if (a->mtime != b->mtime)
162 		return a->mtime - b->mtime;
163 	return got_object_id_cmp(&a->id, &b->id);
164 }
165 
166 static off_t
167 delta_size(struct got_delta_instruction *deltas, int ndeltas)
168 {
169 	int i;
170 	off_t size = 32;
171 	for (i = 0; i < ndeltas; i++) {
172 		if (deltas[i].copy)
173 			size += GOT_DELTA_SIZE_SHIFT;
174 		else
175 			size += deltas[i].len + 1;
176 	}
177 	return size;
178 }
179 
180 static const struct got_error *
181 append(unsigned char **p, size_t *len, off_t *sz, void *seg, int nseg)
182 {
183 	char *n;
184 
185 	if (*len + nseg >= *sz) {
186 		while (*len + nseg >= *sz)
187 			*sz += *sz / 2;
188 		n = realloc(*p, *sz);
189 		if (n == NULL)
190 			return got_error_from_errno("realloc");
191 		*p = n;
192 	}
193 	memcpy(*p + *len, seg, nseg);
194 	*len += nseg;
195 	return NULL;
196 }
197 
198 static const struct got_error *
199 encode_delta_in_mem(struct got_pack_meta *m, struct got_raw_object *o,
200     struct got_delta_instruction *deltas, int ndeltas,
201     off_t delta_size, off_t base_size)
202 {
203 	const struct got_error *err;
204 	unsigned char buf[16], *bp;
205 	int i, j;
206 	size_t len = 0;
207 	off_t n;
208 	struct got_delta_instruction *d;
209 
210 	m->delta_buf = malloc(delta_size);
211 	if (m->delta_buf == NULL)
212 		return got_error_from_errno("calloc");
213 
214 	/* base object size */
215 	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
216 	n = base_size >> GOT_DELTA_SIZE_SHIFT;
217 	for (i = 1; n > 0; i++) {
218 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
219 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
220 		n >>= GOT_DELTA_SIZE_SHIFT;
221 	}
222 	err = append(&m->delta_buf, &len, &delta_size, buf, i);
223 	if (err)
224 		return err;
225 
226 	/* target object size */
227 	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
228 	n = o->size >> GOT_DELTA_SIZE_SHIFT;
229 	for (i = 1; n > 0; i++) {
230 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
231 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
232 		n >>= GOT_DELTA_SIZE_SHIFT;
233 	}
234 	err = append(&m->delta_buf, &len, &delta_size, buf, i);
235 	if (err)
236 		return err;
237 
238 	for (j = 0; j < ndeltas; j++) {
239 		d = &deltas[j];
240 		if (d->copy) {
241 			n = d->offset;
242 			bp = &buf[1];
243 			buf[0] = GOT_DELTA_BASE_COPY;
244 			for (i = 0; i < 4; i++) {
245 				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
246 				buf[0] |= 1 << i;
247 				*bp++ = n & 0xff;
248 				n >>= 8;
249 				if (n == 0)
250 					break;
251 			}
252 
253 			n = d->len;
254 			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
255 				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
256 				for (i = 0; i < 3 && n > 0; i++) {
257 					buf[0] |= 1 << (i + 4);
258 					*bp++ = n & 0xff;
259 					n >>= 8;
260 				}
261 			}
262 			err = append(&m->delta_buf, &len, &delta_size,
263 			    buf, bp - buf);
264 			if (err)
265 				return err;
266 		} else if (o->f == NULL) {
267 			n = 0;
268 			while (n != d->len) {
269 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
270 				err = append(&m->delta_buf, &len, &delta_size,
271 				    buf, 1);
272 				if (err)
273 					return err;
274 				err = append(&m->delta_buf, &len, &delta_size,
275 				    o->data + o->hdrlen + d->offset + n,
276 				    buf[0]);
277 				if (err)
278 					return err;
279 				n += buf[0];
280 			}
281 		} else {
282 			char content[128];
283 			size_t r;
284 			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
285 				return got_error_from_errno("fseeko");
286 			n = 0;
287 			while (n != d->len) {
288 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
289 				err = append(&m->delta_buf, &len, &delta_size,
290 				    buf, 1);
291 				if (err)
292 					return err;
293 				r = fread(content, 1, buf[0], o->f);
294 				if (r != buf[0])
295 					return got_ferror(o->f, GOT_ERR_IO);
296 				err = append(&m->delta_buf, &len, &delta_size,
297 				    content, buf[0]);
298 				if (err)
299 					return err;
300 				n += buf[0];
301 			}
302 		}
303 	}
304 
305 	m->delta_len = len;
306 	return NULL;
307 }
308 
309 static const struct got_error *
310 encode_delta(struct got_pack_meta *m, struct got_raw_object *o,
311     struct got_delta_instruction *deltas, int ndeltas,
312     off_t base_size, FILE *f)
313 {
314 	unsigned char buf[16], *bp;
315 	int i, j;
316 	off_t n;
317 	size_t w;
318 	struct got_delta_instruction *d;
319 
320 	/* base object size */
321 	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
322 	n = base_size >> GOT_DELTA_SIZE_SHIFT;
323 	for (i = 1; n > 0; i++) {
324 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
325 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
326 		n >>= GOT_DELTA_SIZE_SHIFT;
327 	}
328 	w = fwrite(buf, 1, i, f);
329 	if (w != i)
330 		return got_ferror(f, GOT_ERR_IO);
331 
332 	/* target object size */
333 	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
334 	n = o->size >> GOT_DELTA_SIZE_SHIFT;
335 	for (i = 1; n > 0; i++) {
336 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
337 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
338 		n >>= GOT_DELTA_SIZE_SHIFT;
339 	}
340 	w = fwrite(buf, 1, i, f);
341 	if (w != i)
342 		return got_ferror(f, GOT_ERR_IO);
343 
344 	for (j = 0; j < ndeltas; j++) {
345 		d = &deltas[j];
346 		if (d->copy) {
347 			n = d->offset;
348 			bp = &buf[1];
349 			buf[0] = GOT_DELTA_BASE_COPY;
350 			for (i = 0; i < 4; i++) {
351 				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
352 				buf[0] |= 1 << i;
353 				*bp++ = n & 0xff;
354 				n >>= 8;
355 				if (n == 0)
356 					break;
357 			}
358 
359 			n = d->len;
360 			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
361 				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
362 				for (i = 0; i < 3 && n > 0; i++) {
363 					buf[0] |= 1 << (i + 4);
364 					*bp++ = n & 0xff;
365 					n >>= 8;
366 				}
367 			}
368 			w = fwrite(buf, 1, bp - buf, f);
369 			if (w != bp - buf)
370 				return got_ferror(f, GOT_ERR_IO);
371 		} else if (o->f == NULL) {
372 			n = 0;
373 			while (n != d->len) {
374 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
375 				w = fwrite(buf, 1, 1, f);
376 				if (w != 1)
377 					return got_ferror(f, GOT_ERR_IO);
378 				w = fwrite(o->data + o->hdrlen + d->offset + n,
379 				    1, buf[0], f);
380 				if (w != buf[0])
381 					return got_ferror(f, GOT_ERR_IO);
382 				n += buf[0];
383 			}
384 		} else {
385 			char content[128];
386 			size_t r;
387 			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
388 				return got_error_from_errno("fseeko");
389 			n = 0;
390 			while (n != d->len) {
391 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
392 				w = fwrite(buf, 1, 1, f);
393 				if (w != 1)
394 					return got_ferror(f, GOT_ERR_IO);
395 				r = fread(content, 1, buf[0], o->f);
396 				if (r != buf[0])
397 					return got_ferror(o->f, GOT_ERR_IO);
398 				w = fwrite(content, 1, buf[0], f);
399 				if (w != buf[0])
400 					return got_ferror(f, GOT_ERR_IO);
401 				n += buf[0];
402 			}
403 		}
404 	}
405 
406 	m->delta_len = ftello(f) - m->delta_offset;
407 	return NULL;
408 }
409 
410 static const struct got_error *
411 report_progress(got_pack_progress_cb progress_cb, void *progress_arg,
412     struct got_ratelimit *rl, int ncolored, int nfound, int ntrees,
413     off_t packfile_size, int ncommits, int nobj_total, int obj_deltify,
414     int nobj_written)
415 {
416 	const struct got_error *err;
417 	int elapsed;
418 
419 	if (progress_cb == NULL)
420 		return NULL;
421 
422 	err = got_ratelimit_check(&elapsed, rl);
423 	if (err || !elapsed)
424 		return err;
425 
426 	return progress_cb(progress_arg, ncolored, nfound, ntrees,
427 	    packfile_size, ncommits, nobj_total, obj_deltify, nobj_written);
428 }
429 
430 static const struct got_error *
431 add_meta(struct got_pack_meta *m, struct got_pack_metavec *v)
432 {
433 	if (v->nmeta == v->metasz){
434 		size_t newsize = 2 * v->metasz;
435 		struct got_pack_meta **new;
436 		new = reallocarray(v->meta, newsize, sizeof(*new));
437 		if (new == NULL)
438 			return got_error_from_errno("reallocarray");
439 		v->meta = new;
440 		v->metasz = newsize; 
441 	}
442 
443 	v->meta[v->nmeta++] = m;
444 	return NULL;
445 }
446 
447 static const struct got_error *
448 reuse_delta(int idx, struct got_pack_meta *m, struct got_pack_metavec *v,
449     struct got_object_idset *idset, struct got_pack *pack,
450     struct got_packidx *packidx, int delta_cache_fd,
451     struct got_repository *repo)
452 {
453 	const struct got_error *err = NULL;
454 	struct got_pack_meta *base = NULL;
455 	struct got_object_id *base_obj_id = NULL;
456 	off_t delta_len = 0, delta_offset = 0, delta_cache_offset = 0;
457 	uint64_t base_size, result_size;
458 
459 	if (m->have_reused_delta)
460 		return NULL;
461 
462 	err = got_object_read_raw_delta(&base_size, &result_size, &delta_len,
463 	    &delta_offset, &delta_cache_offset, &base_obj_id, delta_cache_fd,
464 	    packidx, idx, &m->id, repo);
465 	if (err)
466 		return err;
467 
468 	if (delta_offset + delta_len < delta_offset)
469 		return got_error(GOT_ERR_BAD_PACKFILE);
470 
471 	base = got_object_idset_get(idset, base_obj_id);
472 	if (base == NULL)
473 		goto done;
474 
475 	m->delta_len = delta_len;
476 	m->delta_offset = delta_cache_offset;
477 	m->prev = base;
478 	m->size = result_size;
479 	m->have_reused_delta = 1;
480 	m->reused_delta_offset = delta_offset;
481 	m->base_obj_id = base_obj_id;
482 	base_obj_id = NULL;
483 	err = add_meta(m, v);
484 done:
485 	free(base_obj_id);
486 	return err;
487 }
488 
489 static const struct got_error *
490 find_pack_for_reuse(struct got_packidx **best_packidx,
491     struct got_repository *repo)
492 {
493 	const struct got_error *err = NULL;
494 	struct got_pathlist_entry *pe;
495 	const char *best_packidx_path = NULL;
496 	int nobj_max = 0;
497 
498 	*best_packidx = NULL;
499 
500 	TAILQ_FOREACH(pe, &repo->packidx_paths, entry) {
501 		const char *path_packidx = pe->path;
502 		struct got_packidx *packidx;
503 		int nobj;
504 
505 		err = got_repo_get_packidx(&packidx, path_packidx, repo);
506 		if (err)
507 			break;
508 
509 		nobj = be32toh(packidx->hdr.fanout_table[0xff]);
510 		if (nobj > nobj_max) {
511 			best_packidx_path = path_packidx;
512 			nobj_max = nobj;
513 		}
514 	}
515 
516 	if (best_packidx_path) {
517 		err = got_repo_get_packidx(best_packidx, best_packidx_path,
518 		    repo);
519 	}
520 
521 	return err;
522 }
523 
524 struct search_deltas_arg {
525 	struct got_packidx *packidx;
526 	struct got_pack *pack;
527 	struct got_object_idset *idset;
528 	struct got_pack_metavec *v;
529 	int delta_cache_fd;
530 	struct got_repository *repo;
531 	got_pack_progress_cb progress_cb;
532 	void *progress_arg;
533 	struct got_ratelimit *rl;
534 	got_cancel_cb cancel_cb;
535 	void *cancel_arg;
536 	int ncolored;
537 	int nfound;
538 	int ntrees;
539 	int ncommits;
540 };
541 
542 static const struct got_error *
543 search_delta_for_object(struct got_object_id *id, void *data, void *arg)
544 {
545 	const struct got_error *err;
546 	struct got_pack_meta *m = data;
547 	struct search_deltas_arg *a = arg;
548 	int obj_idx;
549 	struct got_object *obj = NULL;
550 
551 	if (a->cancel_cb) {
552 		err = (*a->cancel_cb)(a->cancel_arg);
553 		if (err)
554 			return err;
555 	}
556 
557 	if (!got_repo_check_packidx_bloom_filter(a->repo,
558 	    a->packidx->path_packidx, id))
559 		return NULL;
560 
561 	obj_idx = got_packidx_get_object_idx(a->packidx, id);
562 	if (obj_idx == -1)
563 		return NULL;
564 
565 	/* TODO:
566 	 * Opening and closing an object just to check its flags
567 	 * is a bit expensive. We could have an imsg which requests
568 	 * plain type/size information for an object without doing
569 	 * work such as traversing the object's entire delta chain
570 	 * to find the base object type, and other such info which
571 	 * we don't really need here.
572 	 */
573 	err = got_object_open_from_packfile(&obj, &m->id, a->pack,
574 	    a->packidx, obj_idx, a->repo);
575 	if (err)
576 		return err;
577 
578 	if (obj->flags & GOT_OBJ_FLAG_DELTIFIED) {
579 		reuse_delta(obj_idx, m, a->v, a->idset, a->pack, a->packidx,
580 		    a->delta_cache_fd, a->repo);
581 		if (err)
582 			goto done;
583 		err = report_progress(a->progress_cb, a->progress_arg, a->rl,
584 		    a->ncolored, a->nfound, a->ntrees, 0L, a->ncommits,
585 		    got_object_idset_num_elements(a->idset), a->v->nmeta, 0);
586 	}
587 done:
588 	got_object_close(obj);
589 	return err;
590 }
591 
592 static const struct got_error *
593 search_deltas(struct got_pack_metavec *v, struct got_object_idset *idset,
594     int delta_cache_fd, int ncolored, int nfound, int ntrees, int ncommits,
595     struct got_repository *repo,
596     got_pack_progress_cb progress_cb, void *progress_arg,
597     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
598 {
599 	const struct got_error *err = NULL;
600 	char *path_packfile = NULL;
601 	struct got_packidx *packidx;
602 	struct got_pack *pack;
603 	struct search_deltas_arg sda;
604 
605 	err = find_pack_for_reuse(&packidx, repo);
606 	if (err)
607 		return err;
608 
609 	if (packidx == NULL)
610 		return NULL;
611 
612 	err = got_packidx_get_packfile_path(&path_packfile,
613 	    packidx->path_packidx);
614 	if (err)
615 		return err;
616 
617 	pack = got_repo_get_cached_pack(repo, path_packfile);
618 	if (pack == NULL) {
619 		err = got_repo_cache_pack(&pack, repo, path_packfile, packidx);
620 		if (err)
621 			goto done;
622 	}
623 
624 	sda.packidx = packidx;
625 	sda.pack = pack;
626 	sda.idset = idset;
627 	sda.v = v;
628 	sda.delta_cache_fd = delta_cache_fd;
629 	sda.repo = repo;
630 	sda.progress_cb = progress_cb;
631 	sda.progress_arg = progress_arg;
632 	sda.rl = rl;
633 	sda.cancel_cb = cancel_cb;
634 	sda.cancel_arg = cancel_arg;
635 	sda.ncolored = ncolored;
636 	sda.nfound = nfound;
637 	sda.ntrees = ntrees;
638 	sda.ncommits = ncommits;
639 	err = got_object_idset_for_each(idset, search_delta_for_object, &sda);
640 done:
641 	free(path_packfile);
642 	return err;
643 }
644 
645 static const struct got_error *
646 pick_deltas(struct got_pack_meta **meta, int nmeta, int ncolored,
647     int nfound, int ntrees, int ncommits, int nreused, FILE *delta_cache,
648     struct got_repository *repo,
649     got_pack_progress_cb progress_cb, void *progress_arg,
650     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
651 {
652 	const struct got_error *err = NULL;
653 	struct got_pack_meta *m = NULL, *base = NULL;
654 	struct got_raw_object *raw = NULL, *base_raw = NULL;
655 	struct got_delta_instruction *deltas = NULL, *best_deltas = NULL;
656 	int i, j, ndeltas, best_ndeltas;
657 	off_t size, best_size;
658 	const int max_base_candidates = 3;
659 	size_t delta_memsize = 0;
660 	const size_t max_delta_memsize = 25 * GOT_DELTA_RESULT_SIZE_CACHED_MAX;
661 	int outfd = -1;
662 
663 	qsort(meta, nmeta, sizeof(struct got_pack_meta *), delta_order_cmp);
664 	for (i = 0; i < nmeta; i++) {
665 		if (cancel_cb) {
666 			err = (*cancel_cb)(cancel_arg);
667 			if (err)
668 				break;
669 		}
670 		err = report_progress(progress_cb, progress_arg, rl,
671 		    ncolored, nfound, ntrees, 0L, ncommits, nreused + nmeta,
672 		    nreused + i, 0);
673 		if (err)
674 			goto done;
675 		m = meta[i];
676 
677 		if (m->obj_type == GOT_OBJ_TYPE_COMMIT ||
678 		    m->obj_type == GOT_OBJ_TYPE_TAG)
679 			continue;
680 
681 		err = got_object_raw_open(&raw, &outfd, repo, &m->id);
682 		if (err)
683 			goto done;
684 		m->size = raw->size;
685 
686 		if (raw->f == NULL) {
687 			err = got_deltify_init_mem(&m->dtab, raw->data,
688 			    raw->hdrlen, raw->size + raw->hdrlen);
689 		} else {
690 			err = got_deltify_init(&m->dtab, raw->f, raw->hdrlen,
691 			    raw->size + raw->hdrlen);
692 		}
693 		if (err)
694 			goto done;
695 
696 		if (i > max_base_candidates) {
697 			struct got_pack_meta *n = NULL;
698 			n = meta[i - (max_base_candidates + 1)];
699 			got_deltify_free(n->dtab);
700 			n->dtab = NULL;
701 		}
702 
703 		best_size = raw->size;
704 		best_ndeltas = 0;
705 		for (j = MAX(0, i - max_base_candidates); j < i; j++) {
706 			if (cancel_cb) {
707 				err = (*cancel_cb)(cancel_arg);
708 				if (err)
709 					goto done;
710 			}
711 			base = meta[j];
712 			/* long chains make unpacking slow, avoid such bases */
713 			if (base->nchain >= 128 ||
714 			    base->obj_type != m->obj_type)
715 				continue;
716 
717 			err = got_object_raw_open(&base_raw, &outfd, repo,
718 			    &base->id);
719 			if (err)
720 				goto done;
721 
722 			if (raw->f == NULL && base_raw->f == NULL) {
723 				err = got_deltify_mem_mem(&deltas, &ndeltas,
724 				    raw->data, raw->hdrlen,
725 				    raw->size + raw->hdrlen,
726 				    base->dtab, base_raw->data,
727 				    base_raw->hdrlen,
728 				    base_raw->size + base_raw->hdrlen);
729 			} else if (raw->f == NULL) {
730 				err = got_deltify_mem_file(&deltas, &ndeltas,
731 				    raw->data, raw->hdrlen,
732 				    raw->size + raw->hdrlen,
733 				    base->dtab, base_raw->f,
734 				    base_raw->hdrlen,
735 				    base_raw->size + base_raw->hdrlen);
736 			} else if (base_raw->f == NULL) {
737 				err = got_deltify_file_mem(&deltas, &ndeltas,
738 				    raw->f, raw->hdrlen,
739 				    raw->size + raw->hdrlen,
740 				    base->dtab, base_raw->data,
741 				    base_raw->hdrlen,
742 				    base_raw->size + base_raw->hdrlen);
743 			} else {
744 				err = got_deltify(&deltas, &ndeltas,
745 				    raw->f, raw->hdrlen,
746 				    raw->size + raw->hdrlen,
747 				    base->dtab, base_raw->f, base_raw->hdrlen,
748 				    base_raw->size + base_raw->hdrlen);
749 			}
750 			got_object_raw_close(base_raw);
751 			base_raw = NULL;
752 			if (err)
753 				goto done;
754 
755 			size = delta_size(deltas, ndeltas);
756 			if (size + 32 < best_size){
757 				/*
758 				 * if we already picked a best delta,
759 				 * replace it.
760 				 */
761 				best_size = size;
762 				free(best_deltas);
763 				best_deltas = deltas;
764 				best_ndeltas = ndeltas;
765 				deltas = NULL;
766 				m->nchain = base->nchain + 1;
767 				m->prev = base;
768 				m->head = base->head;
769 				if (m->head == NULL)
770 					m->head = base;
771 			} else {
772 				free(deltas);
773 				deltas = NULL;
774 				ndeltas = 0;
775 			}
776 		}
777 
778 		if (best_ndeltas > 0) {
779 			if (best_size <= GOT_DELTA_RESULT_SIZE_CACHED_MAX &&
780 			    delta_memsize + best_size <= max_delta_memsize) {
781 				delta_memsize += best_size;
782 				err = encode_delta_in_mem(m, raw, best_deltas,
783 				    best_ndeltas, best_size, m->prev->size);
784 			} else {
785 				m->delta_offset = ftello(delta_cache);
786 				/*
787 				 * TODO:
788 				 * Storing compressed delta data in the delta
789 				 * cache file would probably be more efficient
790 				 * than writing uncompressed delta data here
791 				 * and compressing it while writing the pack
792 				 * file. This would also allow for reusing
793 				 * deltas in their compressed form.
794 				 */
795 				err = encode_delta(m, raw, best_deltas,
796 				    best_ndeltas, m->prev->size, delta_cache);
797 			}
798 			free(best_deltas);
799 			best_deltas = NULL;
800 			best_ndeltas = 0;
801 			if (err)
802 				goto done;
803 		}
804 
805 		got_object_raw_close(raw);
806 		raw = NULL;
807 	}
808 done:
809 	for (i = MAX(0, nmeta - max_base_candidates); i < nmeta; i++) {
810 		got_deltify_free(meta[i]->dtab);
811 		meta[i]->dtab = NULL;
812 	}
813 	if (raw)
814 		got_object_raw_close(raw);
815 	if (base_raw)
816 		got_object_raw_close(base_raw);
817 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
818 		err = got_error_from_errno("close");
819 	free(deltas);
820 	free(best_deltas);
821 	return err;
822 }
823 
824 static const struct got_error *
825 search_packidx(int *found, struct got_object_id *id,
826     struct got_repository *repo)
827 {
828 	const struct got_error *err = NULL;
829 	struct got_packidx *packidx = NULL;
830 	int idx;
831 
832 	*found = 0;
833 
834 	err = got_repo_search_packidx(&packidx, &idx, repo, id);
835 	if (err == NULL)
836 		*found = 1; /* object is already packed */
837 	else if (err->code == GOT_ERR_NO_OBJ)
838 		err = NULL;
839 	return err;
840 }
841 
842 static const int obj_types[] = {
843 	GOT_OBJ_TYPE_ANY,
844 	GOT_OBJ_TYPE_COMMIT,
845 	GOT_OBJ_TYPE_TREE,
846 	GOT_OBJ_TYPE_BLOB,
847 	GOT_OBJ_TYPE_TAG,
848 	GOT_OBJ_TYPE_OFFSET_DELTA,
849 	GOT_OBJ_TYPE_REF_DELTA
850 };
851 
852 static const struct got_error *
853 add_object(int want_meta, struct got_object_idset *idset,
854     struct got_object_id *id, const char *path, int obj_type,
855     time_t mtime, int loose_obj_only, struct got_repository *repo,
856     int *ncolored, int *nfound, int *ntrees,
857     got_pack_progress_cb progress_cb, void *progress_arg,
858     struct got_ratelimit *rl)
859 {
860 	const struct got_error *err;
861 	struct got_pack_meta *m = NULL;
862 
863 	if (loose_obj_only) {
864 		int is_packed;
865 		err = search_packidx(&is_packed, id, repo);
866 		if (err)
867 			return err;
868 		if (is_packed && want_meta)
869 			return NULL;
870 	}
871 
872 	if (want_meta) {
873 		err = alloc_meta(&m, id, path, obj_type, mtime);
874 		if (err)
875 			return err;
876 
877 		(*nfound)++;
878 		err = report_progress(progress_cb, progress_arg, rl,
879 		    *ncolored, *nfound, *ntrees, 0L, 0, 0, 0, 0);
880 		if (err)
881 			return err;
882 	}
883 
884 	return got_object_idset_add(idset, id, m);
885 }
886 
887 static const struct got_error *
888 load_tree_entries(struct got_object_id_queue *ids, int want_meta,
889     struct got_object_idset *idset, struct got_object_id *tree_id,
890     const char *dpath, time_t mtime, struct got_repository *repo,
891     int loose_obj_only, int *ncolored, int *nfound, int *ntrees,
892     got_pack_progress_cb progress_cb, void *progress_arg,
893     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
894 {
895 	const struct got_error *err;
896 	struct got_tree_object *tree;
897 	char *p = NULL;
898 	int i;
899 
900 	err = got_object_open_as_tree(&tree, repo, tree_id);
901 	if (err)
902 		return err;
903 
904 	(*ntrees)++;
905 	err = report_progress(progress_cb, progress_arg, rl,
906 	    *ncolored, *nfound, *ntrees, 0L, 0, 0, 0, 0);
907 	if (err)
908 		return err;
909 
910 	for (i = 0; i < got_object_tree_get_nentries(tree); i++) {
911 		struct got_tree_entry *e = got_object_tree_get_entry(tree, i);
912 		struct got_object_id *id = got_tree_entry_get_id(e);
913 		mode_t mode = got_tree_entry_get_mode(e);
914 
915 		if (cancel_cb) {
916 			err = (*cancel_cb)(cancel_arg);
917 			if (err)
918 				break;
919 		}
920 
921 		if (got_object_tree_entry_is_submodule(e) ||
922 		    got_object_idset_contains(idset, id))
923 			continue;
924 		
925 		if (asprintf(&p, "%s%s%s", dpath, dpath[0] != '\0' ? "/" : "",
926 		    got_tree_entry_get_name(e)) == -1) {
927 			err = got_error_from_errno("asprintf");
928 			break;
929 		}
930 
931 		if (S_ISDIR(mode)) {
932 			struct got_object_qid *qid;
933 			err = got_object_qid_alloc(&qid, id);
934 			if (err)
935 				break;
936 			STAILQ_INSERT_TAIL(ids, qid, entry);
937 		} else if (S_ISREG(mode) || S_ISLNK(mode)) {
938 			err = add_object(want_meta, idset, id, p,
939 			    GOT_OBJ_TYPE_BLOB, mtime, loose_obj_only, repo,
940 			    ncolored, nfound, ntrees,
941 			    progress_cb, progress_arg, rl);
942 			if (err)
943 				break;
944 		}
945 		free(p);
946 		p = NULL;
947 	}
948 
949 	got_object_tree_close(tree);
950 	free(p);
951 	return err;
952 }
953 
954 static const struct got_error *
955 load_tree(int want_meta, struct got_object_idset *idset,
956     struct got_object_id *tree_id, const char *dpath, time_t mtime,
957     struct got_repository *repo, int loose_obj_only,
958     int *ncolored, int *nfound, int *ntrees,
959     got_pack_progress_cb progress_cb, void *progress_arg,
960     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
961 {
962 	const struct got_error *err = NULL;
963 	struct got_object_id_queue tree_ids;
964 	struct got_object_qid *qid;
965 
966 	if (got_object_idset_contains(idset, tree_id))
967 		return NULL;
968 
969 	err = got_object_qid_alloc(&qid, tree_id);
970 	if (err)
971 		return err;
972 
973 	STAILQ_INIT(&tree_ids);
974 	STAILQ_INSERT_TAIL(&tree_ids, qid, entry);
975 
976 	while (!STAILQ_EMPTY(&tree_ids)) {
977 		if (cancel_cb) {
978 			err = (*cancel_cb)(cancel_arg);
979 			if (err)
980 				break;
981 		}
982 
983 		qid = STAILQ_FIRST(&tree_ids);
984 		STAILQ_REMOVE_HEAD(&tree_ids, entry);
985 
986 		if (got_object_idset_contains(idset, qid->id)) {
987 			got_object_qid_free(qid);
988 			continue;
989 		}
990 
991 		err = add_object(want_meta, idset, qid->id, dpath,
992 		    GOT_OBJ_TYPE_TREE, mtime, loose_obj_only, repo,
993 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl);
994 		if (err) {
995 			got_object_qid_free(qid);
996 			break;
997 		}
998 
999 		err = load_tree_entries(&tree_ids, want_meta, idset, qid->id,
1000 		    dpath, mtime, repo, loose_obj_only, ncolored, nfound,
1001 		    ntrees, progress_cb, progress_arg, rl,
1002 		    cancel_cb, cancel_arg);
1003 		got_object_qid_free(qid);
1004 		if (err)
1005 			break;
1006 	}
1007 
1008 	got_object_id_queue_free(&tree_ids);
1009 	return err;
1010 }
1011 
1012 static const struct got_error *
1013 load_commit(int want_meta, struct got_object_idset *idset,
1014     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
1015     int *ncolored, int *nfound, int *ntrees,
1016     got_pack_progress_cb progress_cb, void *progress_arg,
1017     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
1018 {
1019 	const struct got_error *err;
1020 	struct got_commit_object *commit;
1021 
1022 	if (got_object_idset_contains(idset, id))
1023 		return NULL;
1024 
1025 	if (loose_obj_only) {
1026 		int is_packed;
1027 		err = search_packidx(&is_packed, id, repo);
1028 		if (err)
1029 			return err;
1030 		if (is_packed && want_meta)
1031 			return NULL;
1032 	}
1033 
1034 	err = got_object_open_as_commit(&commit, repo, id);
1035 	if (err)
1036 		return err;
1037 
1038 	err = add_object(want_meta, idset, id, "", GOT_OBJ_TYPE_COMMIT,
1039 	    got_object_commit_get_committer_time(commit),
1040 	    loose_obj_only, repo,
1041 	    ncolored, nfound, ntrees, progress_cb, progress_arg, rl);
1042 	if (err)
1043 		goto done;
1044 
1045 	err = load_tree(want_meta, idset, got_object_commit_get_tree_id(commit),
1046 	    "", got_object_commit_get_committer_time(commit),
1047 	    repo, loose_obj_only, ncolored, nfound, ntrees,
1048 	    progress_cb, progress_arg, rl, cancel_cb, cancel_arg);
1049 done:
1050 	got_object_commit_close(commit);
1051 	return err;
1052 }
1053 
1054 static const struct got_error *
1055 load_tag(int want_meta, struct got_object_idset *idset,
1056     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
1057     int *ncolored, int *nfound, int *ntrees,
1058     got_pack_progress_cb progress_cb, void *progress_arg,
1059     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
1060 {
1061 	const struct got_error *err;
1062 	struct got_tag_object *tag = NULL;
1063 
1064 	if (got_object_idset_contains(idset, id))
1065 		return NULL;
1066 
1067 	if (loose_obj_only) {
1068 		int is_packed;
1069 		err = search_packidx(&is_packed, id, repo);
1070 		if (err)
1071 			return err;
1072 		if (is_packed && want_meta)
1073 			return NULL;
1074 	}
1075 
1076 	err = got_object_open_as_tag(&tag, repo, id);
1077 	if (err)
1078 		return err;
1079 
1080 	err = add_object(want_meta, idset, id, "", GOT_OBJ_TYPE_TAG,
1081 	    got_object_tag_get_tagger_time(tag), loose_obj_only, repo,
1082 	    ncolored, nfound, ntrees, progress_cb, progress_arg, rl);
1083 	if (err)
1084 		goto done;
1085 
1086 	switch (got_object_tag_get_object_type(tag)) {
1087 	case GOT_OBJ_TYPE_COMMIT:
1088 		err = load_commit(want_meta, idset,
1089 		    got_object_tag_get_object_id(tag), repo, loose_obj_only,
1090 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1091 		    cancel_cb, cancel_arg);
1092 		break;
1093 	case GOT_OBJ_TYPE_TREE:
1094 		err = load_tree(want_meta, idset,
1095 		    got_object_tag_get_object_id(tag), "",
1096 		    got_object_tag_get_tagger_time(tag), repo, loose_obj_only,
1097 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1098 		    cancel_cb, cancel_arg);
1099 		break;
1100 	default:
1101 		break;
1102 	}
1103 
1104 done:
1105 	got_object_tag_close(tag);
1106 	return err;
1107 }
1108 
1109 enum findtwixt_color {
1110 	COLOR_KEEP = 0,
1111 	COLOR_DROP,
1112 	COLOR_BLANK,
1113 };
1114 static const int findtwixt_colors[] = {
1115 	COLOR_KEEP,
1116 	COLOR_DROP,
1117 	COLOR_BLANK
1118 };
1119 
1120 static const struct got_error *
1121 queue_commit_id(struct got_object_id_queue *ids, struct got_object_id *id,
1122     int color, struct got_repository *repo)
1123 {
1124 	const struct got_error *err;
1125 	struct got_object_qid *qid;
1126 
1127 	err = got_object_qid_alloc(&qid, id);
1128 	if (err)
1129 		return err;
1130 
1131 	STAILQ_INSERT_TAIL(ids, qid, entry);
1132 	qid->data = (void *)&findtwixt_colors[color];
1133 	return NULL;
1134 }
1135 
1136 static const struct got_error *
1137 drop_commit(struct got_object_idset *keep, struct got_object_idset *drop,
1138     struct got_object_id *id, struct got_repository *repo,
1139     got_cancel_cb cancel_cb, void *cancel_arg)
1140 {
1141 	const struct got_error *err = NULL;
1142 	struct got_commit_object *commit;
1143 	const struct got_object_id_queue *parents;
1144 	struct got_object_id_queue ids;
1145 	struct got_object_qid *qid;
1146 
1147 	STAILQ_INIT(&ids);
1148 
1149 	err = got_object_qid_alloc(&qid, id);
1150 	if (err)
1151 		return err;
1152 	STAILQ_INSERT_HEAD(&ids, qid, entry);
1153 
1154 	while (!STAILQ_EMPTY(&ids)) {
1155 		if (cancel_cb) {
1156 			err = (*cancel_cb)(cancel_arg);
1157 			if (err)
1158 				break;
1159 		}
1160 
1161 		qid = STAILQ_FIRST(&ids);
1162 		STAILQ_REMOVE_HEAD(&ids, entry);
1163 
1164 		if (got_object_idset_contains(drop, qid->id)) {
1165 			got_object_qid_free(qid);
1166 			continue;
1167 		}
1168 
1169 		err = got_object_idset_add(drop, qid->id,
1170 		    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1171 		if (err) {
1172 			got_object_qid_free(qid);
1173 			break;
1174 		}
1175 
1176 		if (!got_object_idset_contains(keep, qid->id)) {
1177 			got_object_qid_free(qid);
1178 			continue;
1179 		}
1180 
1181 		err = got_object_open_as_commit(&commit, repo, qid->id);
1182 		got_object_qid_free(qid);
1183 		if (err)
1184 			break;
1185 
1186 		parents = got_object_commit_get_parent_ids(commit);
1187 		if (parents) {
1188 			err = got_object_id_queue_copy(parents, &ids);
1189 			if (err) {
1190 				got_object_commit_close(commit);
1191 				break;
1192 			}
1193 		}
1194 		got_object_commit_close(commit);
1195 	}
1196 
1197 	got_object_id_queue_free(&ids);
1198 	return err;
1199 }
1200 
1201 struct append_id_arg {
1202 	struct got_object_id **array;
1203 	int idx;
1204 };
1205 
1206 static const struct got_error *
1207 append_id(struct got_object_id *id, void *data, void *arg)
1208 {
1209 	struct append_id_arg *a = arg;
1210 
1211 	a->array[a->idx] = got_object_id_dup(id);
1212 	if (a->array[a->idx] == NULL)
1213 		return got_error_from_errno("got_object_id_dup");
1214 
1215 	a->idx++;
1216 	return NULL;
1217 }
1218 
1219 static const struct got_error *
1220 findtwixt(struct got_object_id ***res, int *nres, int *ncolored,
1221     struct got_object_id **head, int nhead,
1222     struct got_object_id **tail, int ntail,
1223     struct got_repository *repo,
1224     got_pack_progress_cb progress_cb, void *progress_arg,
1225     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
1226 {
1227 	const struct got_error *err = NULL;
1228 	struct got_object_id_queue ids;
1229 	struct got_object_idset *keep, *drop;
1230 	struct got_object_qid *qid;
1231 	int i, ncolor, nkeep, obj_type;
1232 
1233 	STAILQ_INIT(&ids);
1234 	*res = NULL;
1235 	*nres = 0;
1236 	*ncolored = 0;
1237 
1238 	keep = got_object_idset_alloc();
1239 	if (keep == NULL)
1240 		return got_error_from_errno("got_object_idset_alloc");
1241 
1242 	drop = got_object_idset_alloc();
1243 	if (drop == NULL) {
1244 		err = got_error_from_errno("got_object_idset_alloc");
1245 		goto done;
1246 	}
1247 
1248 	for (i = 0; i < nhead; i++) {
1249 		struct got_object_id *id = head[i];
1250 		if (id == NULL)
1251 			continue;
1252 		err = got_object_get_type(&obj_type, repo, id);
1253 		if (err)
1254 			return err;
1255 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1256 			continue;
1257 		err = queue_commit_id(&ids, id, COLOR_KEEP, repo);
1258 		if (err)
1259 			goto done;
1260 	}		
1261 	for (i = 0; i < ntail; i++) {
1262 		struct got_object_id *id = tail[i];
1263 		if (id == NULL)
1264 			continue;
1265 		err = got_object_get_type(&obj_type, repo, id);
1266 		if (err)
1267 			return err;
1268 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1269 			continue;
1270 		err = queue_commit_id(&ids, id, COLOR_DROP, repo);
1271 		if (err)
1272 			goto done;
1273 	}
1274 
1275 	while (!STAILQ_EMPTY(&ids)) {
1276 		int qcolor;
1277 		qid = STAILQ_FIRST(&ids);
1278 		qcolor = *((int *)qid->data);
1279 
1280 		if (got_object_idset_contains(drop, qid->id))
1281 			ncolor = COLOR_DROP;
1282 		else if (got_object_idset_contains(keep, qid->id))
1283 			ncolor = COLOR_KEEP;
1284 		else
1285 			ncolor = COLOR_BLANK;
1286 
1287 		(*ncolored)++;
1288 		err = report_progress(progress_cb, progress_arg, rl,
1289 		    *ncolored, 0, 0, 0L, 0, 0, 0, 0);
1290 		if (err)
1291 			goto done;
1292 
1293 		if (ncolor == COLOR_DROP || (ncolor == COLOR_KEEP &&
1294 		    qcolor == COLOR_KEEP)) {
1295 			STAILQ_REMOVE_HEAD(&ids, entry);
1296 			got_object_qid_free(qid);
1297 			continue;
1298 		}
1299 
1300 		if (ncolor == COLOR_KEEP && qcolor == COLOR_DROP) {
1301 			err = drop_commit(keep, drop, qid->id, repo,
1302 			    cancel_cb, cancel_arg);
1303 			if (err)
1304 				goto done;
1305 		} else if (ncolor == COLOR_BLANK) {
1306 			struct got_commit_object *commit;
1307 			struct got_object_id *id;
1308 			const struct got_object_id_queue *parents;
1309 			struct got_object_qid *pid;
1310 
1311 			id = got_object_id_dup(qid->id);
1312 			if (id == NULL) {
1313 				err = got_error_from_errno("got_object_id_dup");
1314 				goto done;
1315 			}
1316 			if (qcolor == COLOR_KEEP)
1317 				err = got_object_idset_add(keep, id,
1318 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1319 			else
1320 				err = got_object_idset_add(drop, id,
1321 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1322 			if (err) {
1323 				free(id);
1324 				goto done;
1325 			}
1326 
1327 			err = got_object_open_as_commit(&commit, repo, id);
1328 			if (err) {
1329 				free(id);
1330 				goto done;
1331 			}
1332 			parents = got_object_commit_get_parent_ids(commit);
1333 			if (parents) {
1334 				STAILQ_FOREACH(pid, parents, entry) {
1335 					err = queue_commit_id(&ids, pid->id,
1336 					    qcolor, repo);
1337 					if (err) {
1338 						free(id);
1339 						goto done;
1340 					}
1341 				}
1342 			}
1343 			got_object_commit_close(commit);
1344 			commit = NULL;
1345 		} else {
1346 			/* should not happen */
1347 			err = got_error_fmt(GOT_ERR_NOT_IMPL,
1348 			    "%s ncolor=%d qcolor=%d", __func__, ncolor, qcolor);
1349 			goto done;
1350 		}
1351 
1352 		STAILQ_REMOVE_HEAD(&ids, entry);
1353 		got_object_qid_free(qid);
1354 	}
1355 
1356 	nkeep = got_object_idset_num_elements(keep);
1357 	if (nkeep > 0) {
1358 		struct append_id_arg arg;
1359 		arg.array = calloc(nkeep, sizeof(struct got_object_id *));
1360 		if (arg.array == NULL) {
1361 			err = got_error_from_errno("calloc");
1362 			goto done;
1363 		}
1364 		arg.idx = 0;
1365 		err = got_object_idset_for_each(keep, append_id, &arg);
1366 		if (err) {
1367 			free(arg.array);
1368 			goto done;
1369 		}
1370 		*res = arg.array;
1371 		*nres = nkeep;
1372 	}
1373 done:
1374 	got_object_idset_free(keep);
1375 	got_object_idset_free(drop);
1376 	got_object_id_queue_free(&ids);
1377 	return err;
1378 }
1379 
1380 static const struct got_error *
1381 load_object_ids(int *ncolored, int *nfound, int *ntrees,
1382     struct got_object_idset *idset, struct got_object_id **theirs, int ntheirs,
1383     struct got_object_id **ours, int nours, struct got_repository *repo,
1384     int loose_obj_only, got_pack_progress_cb progress_cb, void *progress_arg,
1385     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
1386 {
1387 	const struct got_error *err = NULL;
1388 	struct got_object_id **ids = NULL;
1389 	int i, nobj = 0, obj_type;
1390 
1391 	*ncolored = 0;
1392 	*nfound = 0;
1393 	*ntrees = 0;
1394 
1395 	err = findtwixt(&ids, &nobj, ncolored, ours, nours, theirs, ntheirs,
1396 	    repo, progress_cb, progress_arg, rl, cancel_cb, cancel_arg);
1397 	if (err || nobj == 0)
1398 		goto done;
1399 
1400 	for (i = 0; i < ntheirs; i++) {
1401 		struct got_object_id *id = theirs[i];
1402 		if (id == NULL)
1403 			continue;
1404 		err = got_object_get_type(&obj_type, repo, id);
1405 		if (err)
1406 			return err;
1407 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1408 			continue;
1409 		err = load_commit(0, idset, id, repo, loose_obj_only,
1410 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1411 		    cancel_cb, cancel_arg);
1412 		if (err)
1413 			goto done;
1414 	}
1415 
1416 	for (i = 0; i < ntheirs; i++) {
1417 		struct got_object_id *id = theirs[i];
1418 		struct got_pack_meta *m;
1419 		if (id == NULL)
1420 			continue;
1421 		m = got_object_idset_get(idset, id);
1422 		if (m == NULL) {
1423 			err = got_object_get_type(&obj_type, repo, id);
1424 			if (err)
1425 				goto done;
1426 		} else
1427 			obj_type = m->obj_type;
1428 		if (obj_type != GOT_OBJ_TYPE_TAG)
1429 			continue;
1430 		err = load_tag(0, idset, id, repo, loose_obj_only,
1431 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1432 		    cancel_cb, cancel_arg);
1433 		if (err)
1434 			goto done;
1435 	}
1436 
1437 	for (i = 0; i < nobj; i++) {
1438 		err = load_commit(1, idset, ids[i], repo, loose_obj_only,
1439 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1440 		    cancel_cb, cancel_arg);
1441 		if (err)
1442 			goto done;
1443 	}
1444 
1445 	for (i = 0; i < nours; i++) {
1446 		struct got_object_id *id = ours[i];
1447 		struct got_pack_meta *m;
1448 		if (id == NULL)
1449 			continue;
1450 		m = got_object_idset_get(idset, id);
1451 		if (m == NULL) {
1452 			err = got_object_get_type(&obj_type, repo, id);
1453 			if (err)
1454 				goto done;
1455 		} else
1456 			obj_type = m->obj_type;
1457 		if (obj_type != GOT_OBJ_TYPE_TAG)
1458 			continue;
1459 		err = load_tag(1, idset, id, repo, loose_obj_only,
1460 		    ncolored, nfound, ntrees, progress_cb, progress_arg, rl,
1461 		    cancel_cb, cancel_arg);
1462 		if (err)
1463 			goto done;
1464 	}
1465 done:
1466 	for (i = 0; i < nobj; i++) {
1467 		free(ids[i]);
1468 	}
1469 	free(ids);
1470 	return err;
1471 }
1472 
1473 const struct got_error *
1474 hwrite(FILE *f, void *buf, int len, SHA1_CTX *ctx)
1475 {
1476 	size_t n;
1477 
1478 	SHA1Update(ctx, buf, len);
1479 	n = fwrite(buf, 1, len, f);
1480 	if (n != len)
1481 		return got_ferror(f, GOT_ERR_IO);
1482 	return NULL;
1483 }
1484 
1485 static void
1486 putbe32(char *b, uint32_t n)
1487 {
1488 	b[0] = n >> 24;
1489 	b[1] = n >> 16;
1490 	b[2] = n >> 8;
1491 	b[3] = n >> 0;
1492 }
1493 
1494 static int
1495 write_order_cmp(const void *pa, const void *pb)
1496 {
1497 	struct got_pack_meta *a, *b, *ahd, *bhd;
1498 
1499 	a = *(struct got_pack_meta **)pa;
1500 	b = *(struct got_pack_meta **)pb;
1501 	ahd = (a->head == NULL) ? a : a->head;
1502 	bhd = (b->head == NULL) ? b : b->head;
1503 	if (ahd->mtime != bhd->mtime)
1504 		return bhd->mtime - ahd->mtime;
1505 	if (ahd != bhd)
1506 		return (uintptr_t)bhd - (uintptr_t)ahd;
1507 	if (a->nchain != b->nchain)
1508 		return a->nchain - b->nchain;
1509 	return a->mtime - b->mtime;
1510 }
1511 
1512 static int
1513 reuse_write_order_cmp(const void *pa, const void *pb)
1514 {
1515 	struct got_pack_meta *a, *b;
1516 
1517 	a = *(struct got_pack_meta **)pa;
1518 	b = *(struct got_pack_meta **)pb;
1519 
1520 	if (a->reused_delta_offset < b->reused_delta_offset)
1521 		return -1;
1522 	if (a->reused_delta_offset > b->reused_delta_offset)
1523 		return 1;
1524 	return 0;
1525 }
1526 
1527 static const struct got_error *
1528 packhdr(int *hdrlen, char *hdr, size_t bufsize, int obj_type, size_t len)
1529 {
1530 	size_t i;
1531 
1532 	*hdrlen = 0;
1533 
1534 	hdr[0] = obj_type << 4;
1535 	hdr[0] |= len & 0xf;
1536 	len >>= 4;
1537 	for (i = 1; len != 0; i++){
1538 		if (i >= bufsize)
1539 			return got_error(GOT_ERR_NO_SPACE);
1540 		hdr[i - 1] |= GOT_DELTA_SIZE_MORE;
1541 		hdr[i] = len & GOT_DELTA_SIZE_VAL_MASK;
1542 		len >>= GOT_DELTA_SIZE_SHIFT;
1543 	}
1544 
1545 	*hdrlen = i;
1546 	return NULL;
1547 }
1548 
1549 static int
1550 packoff(char *hdr, off_t off)
1551 {
1552 	int i, j;
1553 	char rbuf[8];
1554 
1555 	rbuf[0] = off & GOT_DELTA_SIZE_VAL_MASK;
1556 	for (i = 1; (off >>= GOT_DELTA_SIZE_SHIFT) != 0; i++) {
1557 		rbuf[i] = (--off & GOT_DELTA_SIZE_VAL_MASK) |
1558 		    GOT_DELTA_SIZE_MORE;
1559 	}
1560 
1561 	j = 0;
1562 	while (i > 0)
1563 		hdr[j++] = rbuf[--i];
1564 	return j;
1565 }
1566 
1567 static const struct got_error *
1568 deltahdr(off_t *packfile_size, SHA1_CTX *ctx, FILE *packfile,
1569     struct got_pack_meta *m)
1570 {
1571 	const struct got_error *err;
1572 	char buf[32];
1573 	int nh;
1574 
1575 	if (m->prev->off != 0) {
1576 		err = packhdr(&nh, buf, sizeof(buf),
1577 		    GOT_OBJ_TYPE_OFFSET_DELTA, m->delta_len);
1578 		if (err)
1579 			return err;
1580 		nh += packoff(buf + nh, m->off - m->prev->off);
1581 		err = hwrite(packfile, buf, nh, ctx);
1582 		if (err)
1583 			return err;
1584 		*packfile_size += nh;
1585 	} else {
1586 		err = packhdr(&nh, buf, sizeof(buf),
1587 		    GOT_OBJ_TYPE_REF_DELTA, m->delta_len);
1588 		if (err)
1589 			return err;
1590 		err = hwrite(packfile, buf, nh, ctx);
1591 		if (err)
1592 			return err;
1593 		*packfile_size += nh;
1594 		err = hwrite(packfile, m->prev->id.sha1,
1595 		    sizeof(m->prev->id.sha1), ctx);
1596 		if (err)
1597 			return err;
1598 		*packfile_size += sizeof(m->prev->id.sha1);
1599 	}
1600 
1601 	return NULL;
1602 }
1603 
1604 static const struct got_error *
1605 write_packed_object(off_t *packfile_size, FILE *packfile,
1606     FILE *delta_cache, struct got_pack_meta *m, int *outfd,
1607     SHA1_CTX *ctx, struct got_repository *repo)
1608 {
1609 	const struct got_error *err = NULL;
1610 	struct got_deflate_checksum csum;
1611 	char buf[32];
1612 	int nh;
1613 	struct got_raw_object *raw = NULL;
1614 	off_t outlen;
1615 
1616 	csum.output_sha1 = ctx;
1617 	csum.output_crc = NULL;
1618 
1619 	m->off = ftello(packfile);
1620 	if (m->delta_len == 0) {
1621 		err = got_object_raw_open(&raw, outfd, repo, &m->id);
1622 		if (err)
1623 			goto done;
1624 		err = packhdr(&nh, buf, sizeof(buf),
1625 		    m->obj_type, raw->size);
1626 		if (err)
1627 			goto done;
1628 		err = hwrite(packfile, buf, nh, ctx);
1629 		if (err)
1630 			goto done;
1631 		*packfile_size += nh;
1632 		if (raw->f == NULL) {
1633 			err = got_deflate_to_file_mmap(&outlen,
1634 			    raw->data + raw->hdrlen, 0, raw->size,
1635 			    packfile, &csum);
1636 			if (err)
1637 				goto done;
1638 		} else {
1639 			if (fseeko(raw->f, raw->hdrlen, SEEK_SET)
1640 			    == -1) {
1641 				err = got_error_from_errno("fseeko");
1642 				goto done;
1643 			}
1644 			err = got_deflate_to_file(&outlen, raw->f,
1645 			    raw->size, packfile, &csum);
1646 			if (err)
1647 				goto done;
1648 		}
1649 		*packfile_size += outlen;
1650 		got_object_raw_close(raw);
1651 		raw = NULL;
1652 	} else if (m->delta_buf) {
1653 		err = deltahdr(packfile_size, ctx, packfile, m);
1654 		if (err)
1655 			goto done;
1656 		err = got_deflate_to_file_mmap(&outlen,
1657 		    m->delta_buf, 0, m->delta_len, packfile, &csum);
1658 		if (err)
1659 			goto done;
1660 		*packfile_size += outlen;
1661 		free(m->delta_buf);
1662 		m->delta_buf = NULL;
1663 	} else {
1664 		if (fseeko(delta_cache, m->delta_offset, SEEK_SET)
1665 		    == -1) {
1666 			err = got_error_from_errno("fseeko");
1667 			goto done;
1668 		}
1669 		err = deltahdr(packfile_size, ctx, packfile, m);
1670 		if (err)
1671 			goto done;
1672 		err = got_deflate_to_file(&outlen, delta_cache,
1673 		    m->delta_len, packfile, &csum);
1674 		if (err)
1675 			goto done;
1676 		*packfile_size += outlen;
1677 	}
1678 done:
1679 	if (raw)
1680 		got_object_raw_close(raw);
1681 	return err;
1682 }
1683 
1684 static const struct got_error *
1685 genpack(uint8_t *pack_sha1, FILE *packfile, FILE *delta_cache,
1686     struct got_pack_meta **deltify, int ndeltify,
1687     struct got_pack_meta **reuse, int nreuse,
1688     int ncolored, int nfound, int ntrees, int nours,
1689     struct got_repository *repo,
1690     got_pack_progress_cb progress_cb, void *progress_arg,
1691     struct got_ratelimit *rl,
1692     got_cancel_cb cancel_cb, void *cancel_arg)
1693 {
1694 	const struct got_error *err = NULL;
1695 	int i;
1696 	SHA1_CTX ctx;
1697 	struct got_pack_meta *m;
1698 	char buf[32];
1699 	size_t n;
1700 	off_t packfile_size = 0;
1701 	int outfd = -1;
1702 
1703 	SHA1Init(&ctx);
1704 
1705 	err = hwrite(packfile, "PACK", 4, &ctx);
1706 	if (err)
1707 		return err;
1708 	putbe32(buf, GOT_PACKFILE_VERSION);
1709 	err = hwrite(packfile, buf, 4, &ctx);
1710 	if (err)
1711 		goto done;
1712 	putbe32(buf, ndeltify + nreuse);
1713 	err = hwrite(packfile, buf, 4, &ctx);
1714 	if (err)
1715 		goto done;
1716 
1717 	qsort(deltify, ndeltify, sizeof(struct got_pack_meta *),
1718 	    write_order_cmp);
1719 	for (i = 0; i < ndeltify; i++) {
1720 		err = report_progress(progress_cb, progress_arg, rl,
1721 		    ncolored, nfound, ntrees, packfile_size, nours,
1722 		    ndeltify + nreuse, ndeltify + nreuse, i);
1723 		if (err)
1724 			goto done;
1725 		m = deltify[i];
1726 		err = write_packed_object(&packfile_size, packfile,
1727 		    delta_cache, m, &outfd, &ctx, repo);
1728 		if (err)
1729 			goto done;
1730 	}
1731 
1732 	qsort(reuse, nreuse, sizeof(struct got_pack_meta *),
1733 	    reuse_write_order_cmp);
1734 	for (i = 0; i < nreuse; i++) {
1735 		err = report_progress(progress_cb, progress_arg, rl,
1736 		    ncolored, nfound, ntrees, packfile_size, nours,
1737 		    ndeltify + nreuse, ndeltify + nreuse, ndeltify + i);
1738 		if (err)
1739 			goto done;
1740 		m = reuse[i];
1741 		err = write_packed_object(&packfile_size, packfile,
1742 		    delta_cache, m, &outfd, &ctx, repo);
1743 		if (err)
1744 			goto done;
1745 	}
1746 
1747 	SHA1Final(pack_sha1, &ctx);
1748 	n = fwrite(pack_sha1, 1, SHA1_DIGEST_LENGTH, packfile);
1749 	if (n != SHA1_DIGEST_LENGTH)
1750 		err = got_ferror(packfile, GOT_ERR_IO);
1751 	packfile_size += SHA1_DIGEST_LENGTH;
1752 	packfile_size += sizeof(struct got_packfile_hdr);
1753 	if (progress_cb) {
1754 		err = progress_cb(progress_arg, ncolored, nfound, ntrees,
1755 		    packfile_size, nours, ndeltify + nreuse,
1756 		    ndeltify + nreuse, ndeltify + nreuse);
1757 		if (err)
1758 			goto done;
1759 	}
1760 done:
1761 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
1762 		err = got_error_from_errno("close");
1763 	return err;
1764 }
1765 
1766 static const struct got_error *
1767 remove_unused_object(struct got_object_idset_element *entry, void *arg)
1768 {
1769 	struct got_object_idset *idset = arg;
1770 
1771 	if (got_object_idset_get_element_data(entry) == NULL)
1772 		got_object_idset_remove_element(idset, entry);
1773 
1774 	return NULL;
1775 }
1776 
1777 static const struct got_error *
1778 remove_reused_object(struct got_object_idset_element *entry, void *arg)
1779 {
1780 	struct got_object_idset *idset = arg;
1781 	struct got_pack_meta *m;
1782 
1783 	m = got_object_idset_get_element_data(entry);
1784 	if (m->have_reused_delta)
1785 		got_object_idset_remove_element(idset, entry);
1786 
1787 	return NULL;
1788 }
1789 
1790 static const struct got_error *
1791 add_meta_idset_cb(struct got_object_id *id, void *data, void *arg)
1792 {
1793 	struct got_pack_meta *m = data;
1794 	struct got_pack_metavec *v = arg;
1795 
1796 	return add_meta(m, v);
1797 }
1798 
1799 const struct got_error *
1800 got_pack_create(uint8_t *packsha1, FILE *packfile,
1801     struct got_object_id **theirs, int ntheirs,
1802     struct got_object_id **ours, int nours,
1803     struct got_repository *repo, int loose_obj_only, int allow_empty,
1804     got_pack_progress_cb progress_cb, void *progress_arg,
1805     got_cancel_cb cancel_cb, void *cancel_arg)
1806 {
1807 	const struct got_error *err;
1808 	int delta_cache_fd = -1;
1809 	FILE *delta_cache = NULL;
1810 	struct got_object_idset *idset;
1811 	struct got_ratelimit rl;
1812 	struct got_pack_metavec deltify, reuse;
1813 	int ncolored = 0, nfound = 0, ntrees = 0;
1814 
1815 	memset(&deltify, 0, sizeof(deltify));
1816 	memset(&reuse, 0, sizeof(reuse));
1817 
1818 	got_ratelimit_init(&rl, 0, 500);
1819 
1820 	idset = got_object_idset_alloc();
1821 	if (idset == NULL)
1822 		return got_error_from_errno("got_object_idset_alloc");
1823 
1824 	err = load_object_ids(&ncolored, &nfound, &ntrees, idset, theirs,
1825 	    ntheirs, ours, nours, repo, loose_obj_only,
1826 	    progress_cb, progress_arg, &rl, cancel_cb, cancel_arg);
1827 	if (err)
1828 		return err;
1829 
1830 	err = got_object_idset_for_each_element(idset,
1831 	    remove_unused_object, idset);
1832 	if (err)
1833 		goto done;
1834 
1835 	if (progress_cb) {
1836 		err = progress_cb(progress_arg, ncolored, nfound, ntrees,
1837 		    0L, nours, got_object_idset_num_elements(idset), 0, 0);
1838 		if (err)
1839 			goto done;
1840 	}
1841 
1842 	if (got_object_idset_num_elements(idset) == 0 && !allow_empty) {
1843 		err = got_error(GOT_ERR_CANNOT_PACK);
1844 		goto done;
1845 	}
1846 
1847 	delta_cache_fd = got_opentempfd();
1848 	if (delta_cache_fd == -1) {
1849 		err = got_error_from_errno("got_opentemp");
1850 		goto done;
1851 	}
1852 
1853 	reuse.metasz = 64;
1854 	reuse.meta = calloc(reuse.metasz,
1855 	    sizeof(struct got_pack_meta *));
1856 	if (reuse.meta == NULL) {
1857 		err = got_error_from_errno("calloc");
1858 		goto done;
1859 	}
1860 
1861 	err = search_deltas(&reuse, idset, delta_cache_fd, ncolored, nfound,
1862 	    ntrees, nours, repo, progress_cb, progress_arg, &rl,
1863 	    cancel_cb, cancel_arg);
1864 	if (err)
1865 		goto done;
1866 	if (reuse.nmeta > 0) {
1867 		err = got_object_idset_for_each_element(idset,
1868 		    remove_reused_object, idset);
1869 		if (err)
1870 			goto done;
1871 	}
1872 
1873 	delta_cache = fdopen(delta_cache_fd, "a+");
1874 	if (delta_cache == NULL) {
1875 		err = got_error_from_errno("fdopen");
1876 		goto done;
1877 	}
1878 	delta_cache_fd = -1;
1879 
1880 	if (fseeko(delta_cache, 0L, SEEK_END) == -1) {
1881 		err = got_error_from_errno("fseeko");
1882 		goto done;
1883 	}
1884 
1885 	deltify.meta = calloc(got_object_idset_num_elements(idset),
1886 	    sizeof(struct got_pack_meta *));
1887 	if (deltify.meta == NULL) {
1888 		err = got_error_from_errno("calloc");
1889 		goto done;
1890 	}
1891 	deltify.metasz = got_object_idset_num_elements(idset);
1892 
1893 	err = got_object_idset_for_each(idset, add_meta_idset_cb, &deltify);
1894 	if (err)
1895 		goto done;
1896 	if (deltify.nmeta > 0) {
1897 		err = pick_deltas(deltify.meta, deltify.nmeta, ncolored,
1898 		    nfound, ntrees, nours, reuse.nmeta, delta_cache, repo,
1899 		    progress_cb, progress_arg, &rl, cancel_cb, cancel_arg);
1900 		if (err)
1901 			goto done;
1902 		if (fseeko(delta_cache, 0L, SEEK_SET) == -1) {
1903 			err = got_error_from_errno("fseeko");
1904 			goto done;
1905 		}
1906 	}
1907 
1908 	err = genpack(packsha1, packfile, delta_cache, deltify.meta,
1909 	    deltify.nmeta, reuse.meta, reuse.nmeta, ncolored, nfound, ntrees,
1910 	    nours, repo, progress_cb, progress_arg, &rl,
1911 	    cancel_cb, cancel_arg);
1912 	if (err)
1913 		goto done;
1914 done:
1915 	free_nmeta(deltify.meta, deltify.nmeta);
1916 	free_nmeta(reuse.meta, reuse.nmeta);
1917 	got_object_idset_free(idset);
1918 	if (delta_cache_fd != -1 && close(delta_cache_fd) == -1 && err == NULL)
1919 		err = got_error_from_errno("close");
1920 	if (delta_cache && fclose(delta_cache) == EOF && err == NULL)
1921 		err = got_error_from_errno("fclose");
1922 	return err;
1923 }