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Date:: Mon Mar 14 13:22:20 2022 UTC
Message:: cache a list of known pack index files when the repository is opened Avoids overhead due to readdir calls while searching a pack index. ok op@
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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/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 <limits.h>
34 #include <zlib.h>
35 
36 #include "got_error.h"
37 #include "got_cancel.h"
38 #include "got_object.h"
39 #include "got_path.h"
40 #include "got_reference.h"
41 #include "got_repository_admin.h"
42 #include "got_opentemp.h"
43 
44 #include "got_lib_deltify.h"
45 #include "got_lib_delta.h"
46 #include "got_lib_object.h"
47 #include "got_lib_object_idset.h"
48 #include "got_lib_object_cache.h"
49 #include "got_lib_deflate.h"
50 #include "got_lib_pack.h"
51 #include "got_lib_privsep.h"
52 #include "got_lib_repository.h"
53 #include "got_lib_ratelimit.h"
54 
55 #ifndef MIN
56 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
57 #endif
58 
59 #ifndef MAX
60 #define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
61 #endif
62 
63 struct got_pack_meta {
64 	struct got_object_id id;
65 	char	*path;
66 	int	obj_type;
67 	off_t	size;
68 	time_t	mtime;
69 
70 	/* The best delta we picked */
71 	struct got_pack_meta *head;
72 	struct got_pack_meta *prev;
73 	unsigned char *delta_buf; /* if not encoded in delta cache file */
74 	off_t	delta_offset;	/* offset in delta cache file */
75 	off_t	delta_len;	/* encoded delta length */
76 	int	nchain;
77 
78 	int	have_reused_delta;
79 	off_t   reused_delta_offset; /* offset of delta in reused pack file */
80 	struct got_object_id *base_obj_id;
81 
82 	/* Only used for delta window */
83 	struct got_delta_table *dtab;
84 
85 	/* Only used for writing offset deltas */
86 	off_t	off;
87 };
88 
89 struct got_pack_metavec {
90 	struct got_pack_meta **meta;
91 	int nmeta;
92 	int metasz;
93 };
94 
95 static const struct got_error *
96 alloc_meta(struct got_pack_meta **new, struct got_object_id *id,
97     const char *path, int obj_type, time_t mtime)
98 {
99 	const struct got_error *err = NULL;
100 	struct got_pack_meta *m;
101 
102 	*new = NULL;
103 
104 	m = calloc(1, sizeof(*m));
105 	if (m == NULL)
106 		return got_error_from_errno("calloc");
107 
108 	memcpy(&m->id, id, sizeof(m->id));
109 
110 	m->path = strdup(path);
111 	if (m->path == NULL) {
112 		err = got_error_from_errno("strdup");
113 		free(m);
114 		return err;
115 	}
116 
117 	m->obj_type = obj_type;
118 	m->mtime = mtime;
119 	*new = m;
120 	return NULL;
121 }
122 
123 static void
124 clear_meta(struct got_pack_meta *meta)
125 {
126 	if (meta == NULL)
127 		return;
128 	free(meta->path);
129 	meta->path = NULL;
130 	free(meta->delta_buf);
131 	meta->delta_buf = NULL;
132 	free(meta->base_obj_id);
133 	meta->base_obj_id = NULL;
134 }
135 
136 static void
137 free_nmeta(struct got_pack_meta **meta, int nmeta)
138 {
139 	int i;
140 
141 	for (i = 0; i < nmeta; i++)
142 		clear_meta(meta[i]);
143 	free(meta);
144 }
145 
146 static int
147 delta_order_cmp(const void *pa, const void *pb)
148 {
149 	struct got_pack_meta *a, *b;
150 	int cmp;
151 
152 	a = *(struct got_pack_meta **)pa;
153 	b = *(struct got_pack_meta **)pb;
154 
155 	if (a->obj_type != b->obj_type)
156 		return a->obj_type - b->obj_type;
157 	cmp = strcmp(a->path, b->path);
158 	if (cmp != 0)
159 		return cmp;
160 	if (a->mtime != b->mtime)
161 		return a->mtime - b->mtime;
162 	return got_object_id_cmp(&a->id, &b->id);
163 }
164 
165 static off_t
166 delta_size(struct got_delta_instruction *deltas, int ndeltas)
167 {
168 	int i;
169 	off_t size = 32;
170 	for (i = 0; i < ndeltas; i++) {
171 		if (deltas[i].copy)
172 			size += GOT_DELTA_SIZE_SHIFT;
173 		else
174 			size += deltas[i].len + 1;
175 	}
176 	return size;
177 }
178 
179 static const struct got_error *
180 append(unsigned char **p, size_t *len, off_t *sz, void *seg, int nseg)
181 {
182 	char *n;
183 
184 	if (*len + nseg >= *sz) {
185 		while (*len + nseg >= *sz)
186 			*sz += *sz / 2;
187 		n = realloc(*p, *sz);
188 		if (n == NULL)
189 			return got_error_from_errno("realloc");
190 		*p = n;
191 	}
192 	memcpy(*p + *len, seg, nseg);
193 	*len += nseg;
194 	return NULL;
195 }
196 
197 static const struct got_error *
198 encode_delta_in_mem(struct got_pack_meta *m, struct got_raw_object *o,
199     struct got_delta_instruction *deltas, int ndeltas,
200     off_t delta_size, off_t base_size)
201 {
202 	const struct got_error *err;
203 	unsigned char buf[16], *bp;
204 	int i, j;
205 	size_t len = 0;
206 	off_t n;
207 	struct got_delta_instruction *d;
208 
209 	m->delta_buf = malloc(delta_size);
210 	if (m->delta_buf == NULL)
211 		return got_error_from_errno("calloc");
212 
213 	/* base object size */
214 	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
215 	n = base_size >> GOT_DELTA_SIZE_SHIFT;
216 	for (i = 1; n > 0; i++) {
217 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
218 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
219 		n >>= GOT_DELTA_SIZE_SHIFT;
220 	}
221 	err = append(&m->delta_buf, &len, &delta_size, buf, i);
222 	if (err)
223 		return err;
224 
225 	/* target object size */
226 	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
227 	n = o->size >> GOT_DELTA_SIZE_SHIFT;
228 	for (i = 1; n > 0; i++) {
229 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
230 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
231 		n >>= GOT_DELTA_SIZE_SHIFT;
232 	}
233 	err = append(&m->delta_buf, &len, &delta_size, buf, i);
234 	if (err)
235 		return err;
236 
237 	for (j = 0; j < ndeltas; j++) {
238 		d = &deltas[j];
239 		if (d->copy) {
240 			n = d->offset;
241 			bp = &buf[1];
242 			buf[0] = GOT_DELTA_BASE_COPY;
243 			for (i = 0; i < 4; i++) {
244 				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
245 				buf[0] |= 1 << i;
246 				*bp++ = n & 0xff;
247 				n >>= 8;
248 				if (n == 0)
249 					break;
250 			}
251 
252 			n = d->len;
253 			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
254 				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
255 				for (i = 0; i < 3 && n > 0; i++) {
256 					buf[0] |= 1 << (i + 4);
257 					*bp++ = n & 0xff;
258 					n >>= 8;
259 				}
260 			}
261 			err = append(&m->delta_buf, &len, &delta_size,
262 			    buf, bp - buf);
263 			if (err)
264 				return err;
265 		} else if (o->f == NULL) {
266 			n = 0;
267 			while (n != d->len) {
268 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
269 				err = append(&m->delta_buf, &len, &delta_size,
270 				    buf, 1);
271 				if (err)
272 					return err;
273 				err = append(&m->delta_buf, &len, &delta_size,
274 				    o->data + o->hdrlen + d->offset + n,
275 				    buf[0]);
276 				if (err)
277 					return err;
278 				n += buf[0];
279 			}
280 		} else {
281 			char content[128];
282 			size_t r;
283 			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
284 				return got_error_from_errno("fseeko");
285 			n = 0;
286 			while (n != d->len) {
287 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
288 				err = append(&m->delta_buf, &len, &delta_size,
289 				    buf, 1);
290 				if (err)
291 					return err;
292 				r = fread(content, 1, buf[0], o->f);
293 				if (r != buf[0])
294 					return got_ferror(o->f, GOT_ERR_IO);
295 				err = append(&m->delta_buf, &len, &delta_size,
296 				    content, buf[0]);
297 				if (err)
298 					return err;
299 				n += buf[0];
300 			}
301 		}
302 	}
303 
304 	m->delta_len = len;
305 	return NULL;
306 }
307 
308 static const struct got_error *
309 encode_delta(struct got_pack_meta *m, struct got_raw_object *o,
310     struct got_delta_instruction *deltas, int ndeltas,
311     off_t base_size, FILE *f)
312 {
313 	unsigned char buf[16], *bp;
314 	int i, j;
315 	off_t n;
316 	size_t w;
317 	struct got_delta_instruction *d;
318 
319 	/* base object size */
320 	buf[0] = base_size & GOT_DELTA_SIZE_VAL_MASK;
321 	n = base_size >> GOT_DELTA_SIZE_SHIFT;
322 	for (i = 1; n > 0; i++) {
323 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
324 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
325 		n >>= GOT_DELTA_SIZE_SHIFT;
326 	}
327 	w = fwrite(buf, 1, i, f);
328 	if (w != i)
329 		return got_ferror(f, GOT_ERR_IO);
330 
331 	/* target object size */
332 	buf[0] = o->size & GOT_DELTA_SIZE_VAL_MASK;
333 	n = o->size >> GOT_DELTA_SIZE_SHIFT;
334 	for (i = 1; n > 0; i++) {
335 		buf[i - 1] |= GOT_DELTA_SIZE_MORE;
336 		buf[i] = n & GOT_DELTA_SIZE_VAL_MASK;
337 		n >>= GOT_DELTA_SIZE_SHIFT;
338 	}
339 	w = fwrite(buf, 1, i, f);
340 	if (w != i)
341 		return got_ferror(f, GOT_ERR_IO);
342 
343 	for (j = 0; j < ndeltas; j++) {
344 		d = &deltas[j];
345 		if (d->copy) {
346 			n = d->offset;
347 			bp = &buf[1];
348 			buf[0] = GOT_DELTA_BASE_COPY;
349 			for (i = 0; i < 4; i++) {
350 				/* DELTA_COPY_OFF1 ... DELTA_COPY_OFF4 */
351 				buf[0] |= 1 << i;
352 				*bp++ = n & 0xff;
353 				n >>= 8;
354 				if (n == 0)
355 					break;
356 			}
357 
358 			n = d->len;
359 			if (n != GOT_DELTA_COPY_DEFAULT_LEN) {
360 				/* DELTA_COPY_LEN1 ... DELTA_COPY_LEN3 */
361 				for (i = 0; i < 3 && n > 0; i++) {
362 					buf[0] |= 1 << (i + 4);
363 					*bp++ = n & 0xff;
364 					n >>= 8;
365 				}
366 			}
367 			w = fwrite(buf, 1, bp - buf, f);
368 			if (w != bp - buf)
369 				return got_ferror(f, GOT_ERR_IO);
370 		} else if (o->f == NULL) {
371 			n = 0;
372 			while (n != d->len) {
373 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
374 				w = fwrite(buf, 1, 1, f);
375 				if (w != 1)
376 					return got_ferror(f, GOT_ERR_IO);
377 				w = fwrite(o->data + o->hdrlen + d->offset + n,
378 				    1, buf[0], f);
379 				if (w != buf[0])
380 					return got_ferror(f, GOT_ERR_IO);
381 				n += buf[0];
382 			}
383 		} else {
384 			char content[128];
385 			size_t r;
386 			if (fseeko(o->f, o->hdrlen + d->offset, SEEK_SET) == -1)
387 				return got_error_from_errno("fseeko");
388 			n = 0;
389 			while (n != d->len) {
390 				buf[0] = (d->len - n < 127) ? d->len - n : 127;
391 				w = fwrite(buf, 1, 1, f);
392 				if (w != 1)
393 					return got_ferror(f, GOT_ERR_IO);
394 				r = fread(content, 1, buf[0], o->f);
395 				if (r != buf[0])
396 					return got_ferror(o->f, GOT_ERR_IO);
397 				w = fwrite(content, 1, buf[0], f);
398 				if (w != buf[0])
399 					return got_ferror(f, GOT_ERR_IO);
400 				n += buf[0];
401 			}
402 		}
403 	}
404 
405 	m->delta_len = ftello(f) - m->delta_offset;
406 	return NULL;
407 }
408 
409 static const struct got_error *
410 report_progress(got_pack_progress_cb progress_cb, void *progress_arg,
411     struct got_ratelimit *rl, off_t packfile_size, int ncommits,
412     int nobj_total, int obj_deltify, int nobj_written)
413 {
414 	const struct got_error *err;
415 	int elapsed;
416 
417 	if (progress_cb == NULL)
418 		return NULL;
419 
420 	err = got_ratelimit_check(&elapsed, rl);
421 	if (err || !elapsed)
422 		return err;
423 
424 	return progress_cb(progress_arg, packfile_size, ncommits,
425 	    nobj_total, obj_deltify, nobj_written);
426 }
427 
428 static const struct got_error *
429 add_meta(struct got_pack_meta *m, struct got_pack_metavec *v)
430 {
431 	if (v->nmeta == v->metasz){
432 		size_t newsize = 2 * v->metasz;
433 		struct got_pack_meta **new;
434 		new = reallocarray(v->meta, newsize, sizeof(*new));
435 		if (new == NULL)
436 			return got_error_from_errno("reallocarray");
437 		v->meta = new;
438 		v->metasz = newsize; 
439 	}
440 
441 	v->meta[v->nmeta++] = m;
442 	return NULL;
443 }
444 
445 static const struct got_error *
446 reuse_delta(int idx, struct got_pack_meta *m, struct got_pack_metavec *v,
447     struct got_object_idset *idset, struct got_pack *pack,
448     struct got_packidx *packidx, int delta_cache_fd,
449     struct got_repository *repo)
450 {
451 	const struct got_error *err = NULL;
452 	struct got_pack_meta *base = NULL;
453 	struct got_object_id *base_obj_id = NULL;
454 	off_t delta_len = 0, delta_offset = 0, delta_cache_offset = 0;
455 	uint64_t base_size, result_size;
456 
457 	if (m->have_reused_delta)
458 		return NULL;
459 
460 	err = got_object_read_raw_delta(&base_size, &result_size, &delta_len,
461 	    &delta_offset, &delta_cache_offset, &base_obj_id, delta_cache_fd,
462 	    packidx, idx, &m->id, repo);
463 	if (err)
464 		return err;
465 
466 	if (delta_offset + delta_len < delta_offset)
467 		return got_error(GOT_ERR_BAD_PACKFILE);
468 
469 	base = got_object_idset_get(idset, base_obj_id);
470 	if (base == NULL)
471 		goto done;
472 
473 	m->delta_len = delta_len;
474 	m->delta_offset = delta_cache_offset;
475 	m->prev = base;
476 	m->size = result_size;
477 	m->have_reused_delta = 1;
478 	m->reused_delta_offset = delta_offset;
479 	m->base_obj_id = base_obj_id;
480 	base_obj_id = NULL;
481 	err = add_meta(m, v);
482 done:
483 	free(base_obj_id);
484 	return err;
485 }
486 
487 static const struct got_error *
488 find_pack_for_reuse(struct got_packidx **best_packidx,
489     struct got_repository *repo)
490 {
491 	const struct got_error *err = NULL;
492 	struct got_pathlist_entry *pe;
493 	const char *best_packidx_path = NULL;
494 	int nobj_max = 0;
495 
496 	*best_packidx = NULL;
497 
498 	TAILQ_FOREACH(pe, &repo->packidx_paths, entry) {
499 		const char *path_packidx = pe->path;
500 		struct got_packidx *packidx;
501 		int nobj;
502 
503 		err = got_repo_get_packidx(&packidx, path_packidx, repo);
504 		if (err)
505 			break;
506 
507 		nobj = be32toh(packidx->hdr.fanout_table[0xff]);
508 		if (nobj > nobj_max) {
509 			best_packidx_path = path_packidx;
510 			nobj_max = nobj;
511 		}
512 	}
513 
514 	if (best_packidx_path) {
515 		err = got_repo_get_packidx(best_packidx, best_packidx_path,
516 		    repo);
517 	}
518 
519 	return err;
520 }
521 
522 struct search_deltas_arg {
523 	struct got_packidx *packidx;
524 	struct got_pack *pack;
525 	struct got_object_idset *idset;
526 	struct got_pack_metavec *v;
527 	int delta_cache_fd;
528 	struct got_repository *repo;
529 	got_pack_progress_cb progress_cb;
530 	void *progress_arg;
531 	struct got_ratelimit *rl;
532 	got_cancel_cb cancel_cb;
533 	void *cancel_arg;
534 	int ncommits;
535 };
536 
537 static const struct got_error *
538 search_delta_for_object(struct got_object_id *id, void *data, void *arg)
539 {
540 	const struct got_error *err;
541 	struct got_pack_meta *m = data;
542 	struct search_deltas_arg *a = arg;
543 	int obj_idx;
544 	struct got_object *obj = NULL;
545 
546 	if (a->cancel_cb) {
547 		err = (*a->cancel_cb)(a->cancel_arg);
548 		if (err)
549 			return err;
550 	}
551 
552 	if (!got_repo_check_packidx_bloom_filter(a->repo,
553 	    a->packidx->path_packidx, id))
554 		return NULL;
555 
556 	obj_idx = got_packidx_get_object_idx(a->packidx, id);
557 	if (obj_idx == -1)
558 		return NULL;
559 
560 	/* TODO:
561 	 * Opening and closing an object just to check its flags
562 	 * is a bit expensive. We could have an imsg which requests
563 	 * plain type/size information for an object without doing
564 	 * work such as traversing the object's entire delta chain
565 	 * to find the base object type, and other such info which
566 	 * we don't really need here.
567 	 */
568 	err = got_object_open_from_packfile(&obj, &m->id, a->pack,
569 	    a->packidx, obj_idx, a->repo);
570 	if (err)
571 		return err;
572 
573 	if (obj->flags & GOT_OBJ_FLAG_DELTIFIED) {
574 		reuse_delta(obj_idx, m, a->v, a->idset, a->pack, a->packidx,
575 		    a->delta_cache_fd, a->repo);
576 		if (err)
577 			goto done;
578 		err = report_progress(a->progress_cb, a->progress_arg, a->rl,
579 		    0L, a->ncommits, got_object_idset_num_elements(a->idset),
580 		    a->v->nmeta, 0);
581 	}
582 done:
583 	got_object_close(obj);
584 	return err;
585 }
586 
587 static const struct got_error *
588 search_deltas(struct got_pack_metavec *v, struct got_object_idset *idset,
589     int delta_cache_fd, int ncommits, struct got_repository *repo,
590     got_pack_progress_cb progress_cb, void *progress_arg,
591     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
592 {
593 	const struct got_error *err = NULL;
594 	char *path_packfile = NULL;
595 	struct got_packidx *packidx;
596 	struct got_pack *pack;
597 	struct search_deltas_arg sda;
598 
599 	err = find_pack_for_reuse(&packidx, repo);
600 	if (err)
601 		return err;
602 
603 	if (packidx == NULL)
604 		return NULL;
605 
606 	err = got_packidx_get_packfile_path(&path_packfile,
607 	    packidx->path_packidx);
608 	if (err)
609 		return err;
610 
611 	pack = got_repo_get_cached_pack(repo, path_packfile);
612 	if (pack == NULL) {
613 		err = got_repo_cache_pack(&pack, repo, path_packfile, packidx);
614 		if (err)
615 			goto done;
616 	}
617 
618 	sda.packidx = packidx;
619 	sda.pack = pack;
620 	sda.idset = idset;
621 	sda.v = v;
622 	sda.delta_cache_fd = delta_cache_fd;
623 	sda.repo = repo;
624 	sda.progress_cb = progress_cb;
625 	sda.progress_arg = progress_arg;
626 	sda.rl = rl;
627 	sda.cancel_cb = cancel_cb;
628 	sda.cancel_arg = cancel_arg;
629 	sda.ncommits = ncommits;
630 	err = got_object_idset_for_each(idset, search_delta_for_object, &sda);
631 done:
632 	free(path_packfile);
633 	return err;
634 }
635 
636 static const struct got_error *
637 pick_deltas(struct got_pack_meta **meta, int nmeta, int ncommits,
638     int nreused, FILE *delta_cache, struct got_repository *repo,
639     got_pack_progress_cb progress_cb, void *progress_arg,
640     struct got_ratelimit *rl, got_cancel_cb cancel_cb, void *cancel_arg)
641 {
642 	const struct got_error *err = NULL;
643 	struct got_pack_meta *m = NULL, *base = NULL;
644 	struct got_raw_object *raw = NULL, *base_raw = NULL;
645 	struct got_delta_instruction *deltas = NULL, *best_deltas = NULL;
646 	int i, j, ndeltas, best_ndeltas;
647 	off_t size, best_size;
648 	const int max_base_candidates = 3;
649 	size_t delta_memsize = 0;
650 	const size_t max_delta_memsize = 25 * GOT_DELTA_RESULT_SIZE_CACHED_MAX;
651 	int outfd = -1;
652 
653 	qsort(meta, nmeta, sizeof(struct got_pack_meta *), delta_order_cmp);
654 	for (i = 0; i < nmeta; i++) {
655 		if (cancel_cb) {
656 			err = (*cancel_cb)(cancel_arg);
657 			if (err)
658 				break;
659 		}
660 		err = report_progress(progress_cb, progress_arg, rl,
661 		    0L, ncommits, nreused + nmeta, nreused + i, 0);
662 		if (err)
663 			goto done;
664 		m = meta[i];
665 
666 		if (m->obj_type == GOT_OBJ_TYPE_COMMIT ||
667 		    m->obj_type == GOT_OBJ_TYPE_TAG)
668 			continue;
669 
670 		err = got_object_raw_open(&raw, &outfd, repo, &m->id);
671 		if (err)
672 			goto done;
673 		m->size = raw->size;
674 
675 		if (raw->f == NULL) {
676 			err = got_deltify_init_mem(&m->dtab, raw->data,
677 			    raw->hdrlen, raw->size + raw->hdrlen);
678 		} else {
679 			err = got_deltify_init(&m->dtab, raw->f, raw->hdrlen,
680 			    raw->size + raw->hdrlen);
681 		}
682 		if (err)
683 			goto done;
684 
685 		if (i > max_base_candidates) {
686 			struct got_pack_meta *n = NULL;
687 			n = meta[i - (max_base_candidates + 1)];
688 			got_deltify_free(n->dtab);
689 			n->dtab = NULL;
690 		}
691 
692 		best_size = raw->size;
693 		best_ndeltas = 0;
694 		for (j = MAX(0, i - max_base_candidates); j < i; j++) {
695 			if (cancel_cb) {
696 				err = (*cancel_cb)(cancel_arg);
697 				if (err)
698 					goto done;
699 			}
700 			base = meta[j];
701 			/* long chains make unpacking slow, avoid such bases */
702 			if (base->nchain >= 128 ||
703 			    base->obj_type != m->obj_type)
704 				continue;
705 
706 			err = got_object_raw_open(&base_raw, &outfd, repo,
707 			    &base->id);
708 			if (err)
709 				goto done;
710 
711 			if (raw->f == NULL && base_raw->f == NULL) {
712 				err = got_deltify_mem_mem(&deltas, &ndeltas,
713 				    raw->data, raw->hdrlen,
714 				    raw->size + raw->hdrlen,
715 				    base->dtab, base_raw->data,
716 				    base_raw->hdrlen,
717 				    base_raw->size + base_raw->hdrlen);
718 			} else if (raw->f == NULL) {
719 				err = got_deltify_mem_file(&deltas, &ndeltas,
720 				    raw->data, raw->hdrlen,
721 				    raw->size + raw->hdrlen,
722 				    base->dtab, base_raw->f,
723 				    base_raw->hdrlen,
724 				    base_raw->size + base_raw->hdrlen);
725 			} else if (base_raw->f == NULL) {
726 				err = got_deltify_file_mem(&deltas, &ndeltas,
727 				    raw->f, raw->hdrlen,
728 				    raw->size + raw->hdrlen,
729 				    base->dtab, base_raw->data,
730 				    base_raw->hdrlen,
731 				    base_raw->size + base_raw->hdrlen);
732 			} else {
733 				err = got_deltify(&deltas, &ndeltas,
734 				    raw->f, raw->hdrlen,
735 				    raw->size + raw->hdrlen,
736 				    base->dtab, base_raw->f, base_raw->hdrlen,
737 				    base_raw->size + base_raw->hdrlen);
738 			}
739 			got_object_raw_close(base_raw);
740 			base_raw = NULL;
741 			if (err)
742 				goto done;
743 
744 			size = delta_size(deltas, ndeltas);
745 			if (size + 32 < best_size){
746 				/*
747 				 * if we already picked a best delta,
748 				 * replace it.
749 				 */
750 				best_size = size;
751 				free(best_deltas);
752 				best_deltas = deltas;
753 				best_ndeltas = ndeltas;
754 				deltas = NULL;
755 				m->nchain = base->nchain + 1;
756 				m->prev = base;
757 				m->head = base->head;
758 				if (m->head == NULL)
759 					m->head = base;
760 			} else {
761 				free(deltas);
762 				deltas = NULL;
763 				ndeltas = 0;
764 			}
765 		}
766 
767 		if (best_ndeltas > 0) {
768 			if (best_size <= GOT_DELTA_RESULT_SIZE_CACHED_MAX &&
769 			    delta_memsize + best_size <= max_delta_memsize) {
770 				delta_memsize += best_size;
771 				err = encode_delta_in_mem(m, raw, best_deltas,
772 				    best_ndeltas, best_size, m->prev->size);
773 			} else {
774 				m->delta_offset = ftello(delta_cache);
775 				/*
776 				 * TODO:
777 				 * Storing compressed delta data in the delta
778 				 * cache file would probably be more efficient
779 				 * than writing uncompressed delta data here
780 				 * and compressing it while writing the pack
781 				 * file. This would also allow for reusing
782 				 * deltas in their compressed form.
783 				 */
784 				err = encode_delta(m, raw, best_deltas,
785 				    best_ndeltas, m->prev->size, delta_cache);
786 			}
787 			free(best_deltas);
788 			best_deltas = NULL;
789 			best_ndeltas = 0;
790 			if (err)
791 				goto done;
792 		}
793 
794 		got_object_raw_close(raw);
795 		raw = NULL;
796 	}
797 done:
798 	for (i = MAX(0, nmeta - max_base_candidates); i < nmeta; i++) {
799 		got_deltify_free(meta[i]->dtab);
800 		meta[i]->dtab = NULL;
801 	}
802 	if (raw)
803 		got_object_raw_close(raw);
804 	if (base_raw)
805 		got_object_raw_close(base_raw);
806 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
807 		err = got_error_from_errno("close");
808 	free(deltas);
809 	free(best_deltas);
810 	return err;
811 }
812 
813 static const struct got_error *
814 search_packidx(int *found, struct got_object_id *id,
815     struct got_repository *repo)
816 {
817 	const struct got_error *err = NULL;
818 	struct got_packidx *packidx = NULL;
819 	int idx;
820 
821 	*found = 0;
822 
823 	err = got_repo_search_packidx(&packidx, &idx, repo, id);
824 	if (err == NULL)
825 		*found = 1; /* object is already packed */
826 	else if (err->code == GOT_ERR_NO_OBJ)
827 		err = NULL;
828 	return err;
829 }
830 
831 static const int obj_types[] = {
832 	GOT_OBJ_TYPE_ANY,
833 	GOT_OBJ_TYPE_COMMIT,
834 	GOT_OBJ_TYPE_TREE,
835 	GOT_OBJ_TYPE_BLOB,
836 	GOT_OBJ_TYPE_TAG,
837 	GOT_OBJ_TYPE_OFFSET_DELTA,
838 	GOT_OBJ_TYPE_REF_DELTA
839 };
840 
841 static const struct got_error *
842 add_object(int want_meta, struct got_object_idset *idset,
843     struct got_object_id *id, const char *path, int obj_type,
844     time_t mtime, int loose_obj_only, struct got_repository *repo)
845 {
846 	const struct got_error *err;
847 	struct got_pack_meta *m = NULL;
848 
849 	if (loose_obj_only) {
850 		int is_packed;
851 		err = search_packidx(&is_packed, id, repo);
852 		if (err)
853 			return err;
854 		if (is_packed)
855 			return NULL;
856 	}
857 
858 	if (want_meta) {
859 		err = alloc_meta(&m, id, path, obj_type, mtime);
860 		if (err)
861 			return err;
862 	}
863 
864 	return got_object_idset_add(idset, id, m);
865 }
866 
867 static const struct got_error *
868 load_tree_entries(struct got_object_id_queue *ids, int want_meta,
869     struct got_object_idset *idset, struct got_object_id *tree_id,
870     const char *dpath, time_t mtime, struct got_repository *repo,
871     int loose_obj_only, got_cancel_cb cancel_cb, void *cancel_arg)
872 {
873 	const struct got_error *err;
874 	struct got_tree_object *tree;
875 	char *p = NULL;
876 	int i;
877 
878 	err = got_object_open_as_tree(&tree, repo, tree_id);
879 	if (err)
880 		return err;
881 
882 	for (i = 0; i < got_object_tree_get_nentries(tree); i++) {
883 		struct got_tree_entry *e = got_object_tree_get_entry(tree, i);
884 		struct got_object_id *id = got_tree_entry_get_id(e);
885 		mode_t mode = got_tree_entry_get_mode(e);
886 
887 		if (cancel_cb) {
888 			err = (*cancel_cb)(cancel_arg);
889 			if (err)
890 				break;
891 		}
892 
893 		if (got_object_tree_entry_is_submodule(e) ||
894 		    got_object_idset_contains(idset, id))
895 			continue;
896 		
897 		if (asprintf(&p, "%s%s%s", dpath, dpath[0] != '\0' ? "/" : "",
898 		    got_tree_entry_get_name(e)) == -1) {
899 			err = got_error_from_errno("asprintf");
900 			break;
901 		}
902 
903 		if (S_ISDIR(mode)) {
904 			struct got_object_qid *qid;
905 			err = got_object_qid_alloc(&qid, id);
906 			if (err)
907 				break;
908 			STAILQ_INSERT_TAIL(ids, qid, entry);
909 		} else if (S_ISREG(mode) || S_ISLNK(mode)) {
910 			err = add_object(want_meta, idset, id, p,
911 			    GOT_OBJ_TYPE_BLOB, mtime, loose_obj_only, repo);
912 			if (err)
913 				break;
914 		}
915 		free(p);
916 		p = NULL;
917 	}
918 
919 	got_object_tree_close(tree);
920 	free(p);
921 	return err;
922 }
923 
924 static const struct got_error *
925 load_tree(int want_meta, struct got_object_idset *idset,
926     struct got_object_id *tree_id, const char *dpath, time_t mtime,
927     int loose_obj_only, struct got_repository *repo,
928     got_cancel_cb cancel_cb, void *cancel_arg)
929 {
930 	const struct got_error *err = NULL;
931 	struct got_object_id_queue tree_ids;
932 	struct got_object_qid *qid;
933 
934 	if (got_object_idset_contains(idset, tree_id))
935 		return NULL;
936 
937 	err = got_object_qid_alloc(&qid, tree_id);
938 	if (err)
939 		return err;
940 
941 	STAILQ_INIT(&tree_ids);
942 	STAILQ_INSERT_TAIL(&tree_ids, qid, entry);
943 
944 	while (!STAILQ_EMPTY(&tree_ids)) {
945 		if (cancel_cb) {
946 			err = (*cancel_cb)(cancel_arg);
947 			if (err)
948 				break;
949 		}
950 
951 		qid = STAILQ_FIRST(&tree_ids);
952 		STAILQ_REMOVE_HEAD(&tree_ids, entry);
953 
954 		if (got_object_idset_contains(idset, qid->id)) {
955 			got_object_qid_free(qid);
956 			continue;
957 		}
958 
959 		err = add_object(want_meta, idset, qid->id, dpath,
960 		    GOT_OBJ_TYPE_TREE, mtime, loose_obj_only, repo);
961 		if (err) {
962 			got_object_qid_free(qid);
963 			break;
964 		}
965 
966 		err = load_tree_entries(&tree_ids, want_meta, idset, qid->id,
967 		    dpath, mtime, repo, loose_obj_only, cancel_cb, cancel_arg);
968 		got_object_qid_free(qid);
969 		if (err)
970 			break;
971 	}
972 
973 	got_object_id_queue_free(&tree_ids);
974 	return err;
975 }
976 
977 static const struct got_error *
978 load_commit(int want_meta, struct got_object_idset *idset,
979     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
980     got_cancel_cb cancel_cb, void *cancel_arg)
981 {
982 	const struct got_error *err;
983 	struct got_commit_object *commit;
984 
985 	if (got_object_idset_contains(idset, id))
986 		return NULL;
987 
988 	if (loose_obj_only) {
989 		int is_packed;
990 		err = search_packidx(&is_packed, id, repo);
991 		if (err)
992 			return err;
993 		if (is_packed)
994 			return NULL;
995 	}
996 
997 	err = got_object_open_as_commit(&commit, repo, id);
998 	if (err)
999 		return err;
1000 
1001 	err = add_object(want_meta, idset, id, "", GOT_OBJ_TYPE_COMMIT,
1002 	    got_object_commit_get_committer_time(commit),
1003 	    loose_obj_only, repo);
1004 	if (err)
1005 		goto done;
1006 
1007 	err = load_tree(want_meta, idset, got_object_commit_get_tree_id(commit),
1008 	    "", got_object_commit_get_committer_time(commit),
1009 	    loose_obj_only, repo, cancel_cb, cancel_arg);
1010 done:
1011 	got_object_commit_close(commit);
1012 	return err;
1013 }
1014 
1015 static const struct got_error *
1016 load_tag(int want_meta, struct got_object_idset *idset,
1017     struct got_object_id *id, struct got_repository *repo, int loose_obj_only,
1018     got_cancel_cb cancel_cb, void *cancel_arg)
1019 {
1020 	const struct got_error *err;
1021 	struct got_tag_object *tag = NULL;
1022 
1023 	if (got_object_idset_contains(idset, id))
1024 		return NULL;
1025 
1026 	if (loose_obj_only) {
1027 		int is_packed;
1028 		err = search_packidx(&is_packed, id, repo);
1029 		if (err)
1030 			return err;
1031 		if (is_packed)
1032 			return NULL;
1033 	}
1034 
1035 	err = got_object_open_as_tag(&tag, repo, id);
1036 	if (err)
1037 		return err;
1038 
1039 	err = add_object(want_meta, idset, id, "", GOT_OBJ_TYPE_TAG,
1040 	    got_object_tag_get_tagger_time(tag),
1041 	    loose_obj_only, repo);
1042 	if (err)
1043 		goto done;
1044 
1045 	switch (got_object_tag_get_object_type(tag)) {
1046 	case GOT_OBJ_TYPE_COMMIT:
1047 		err = load_commit(want_meta, idset,
1048 		    got_object_tag_get_object_id(tag), repo,
1049 		    loose_obj_only, cancel_cb, cancel_arg);
1050 		break;
1051 	case GOT_OBJ_TYPE_TREE:
1052 		err = load_tree(want_meta, idset,
1053 		    got_object_tag_get_object_id(tag), "",
1054 		    got_object_tag_get_tagger_time(tag),
1055 		    loose_obj_only, repo, cancel_cb, cancel_arg);
1056 		break;
1057 	default:
1058 		break;
1059 	}
1060 
1061 done:
1062 	got_object_tag_close(tag);
1063 	return err;
1064 }
1065 
1066 enum findtwixt_color {
1067 	COLOR_KEEP = 0,
1068 	COLOR_DROP,
1069 	COLOR_BLANK,
1070 };
1071 static const int findtwixt_colors[] = {
1072 	COLOR_KEEP,
1073 	COLOR_DROP,
1074 	COLOR_BLANK
1075 };
1076 
1077 static const struct got_error *
1078 queue_commit_id(struct got_object_id_queue *ids, struct got_object_id *id,
1079     int color, struct got_repository *repo)
1080 {
1081 	const struct got_error *err;
1082 	struct got_object_qid *qid;
1083 
1084 	err = got_object_qid_alloc(&qid, id);
1085 	if (err)
1086 		return err;
1087 
1088 	STAILQ_INSERT_TAIL(ids, qid, entry);
1089 	qid->data = (void *)&findtwixt_colors[color];
1090 	return NULL;
1091 }
1092 
1093 static const struct got_error *
1094 drop_commit(struct got_object_idset *keep, struct got_object_idset *drop,
1095     struct got_object_id *id, struct got_repository *repo,
1096     got_cancel_cb cancel_cb, void *cancel_arg)
1097 {
1098 	const struct got_error *err = NULL;
1099 	struct got_commit_object *commit;
1100 	const struct got_object_id_queue *parents;
1101 	struct got_object_id_queue ids;
1102 	struct got_object_qid *qid;
1103 
1104 	STAILQ_INIT(&ids);
1105 
1106 	err = got_object_qid_alloc(&qid, id);
1107 	if (err)
1108 		return err;
1109 	STAILQ_INSERT_HEAD(&ids, qid, entry);
1110 
1111 	while (!STAILQ_EMPTY(&ids)) {
1112 		if (cancel_cb) {
1113 			err = (*cancel_cb)(cancel_arg);
1114 			if (err)
1115 				break;
1116 		}
1117 
1118 		qid = STAILQ_FIRST(&ids);
1119 		STAILQ_REMOVE_HEAD(&ids, entry);
1120 
1121 		if (got_object_idset_contains(drop, qid->id)) {
1122 			got_object_qid_free(qid);
1123 			continue;
1124 		}
1125 
1126 		err = got_object_idset_add(drop, qid->id,
1127 		    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1128 		if (err) {
1129 			got_object_qid_free(qid);
1130 			break;
1131 		}
1132 
1133 		if (!got_object_idset_contains(keep, qid->id)) {
1134 			got_object_qid_free(qid);
1135 			continue;
1136 		}
1137 
1138 		err = got_object_open_as_commit(&commit, repo, qid->id);
1139 		got_object_qid_free(qid);
1140 		if (err)
1141 			break;
1142 
1143 		parents = got_object_commit_get_parent_ids(commit);
1144 		if (parents) {
1145 			err = got_object_id_queue_copy(parents, &ids);
1146 			if (err) {
1147 				got_object_commit_close(commit);
1148 				break;
1149 			}
1150 		}
1151 		got_object_commit_close(commit);
1152 	}
1153 
1154 	got_object_id_queue_free(&ids);
1155 	return err;
1156 }
1157 
1158 struct append_id_arg {
1159 	struct got_object_id **array;
1160 	int idx;
1161 };
1162 
1163 static const struct got_error *
1164 append_id(struct got_object_id *id, void *data, void *arg)
1165 {
1166 	struct append_id_arg *a = arg;
1167 
1168 	a->array[a->idx] = got_object_id_dup(id);
1169 	if (a->array[a->idx] == NULL)
1170 		return got_error_from_errno("got_object_id_dup");
1171 
1172 	a->idx++;
1173 	return NULL;
1174 }
1175 
1176 static const struct got_error *
1177 findtwixt(struct got_object_id ***res, int *nres,
1178     struct got_object_id **head, int nhead,
1179     struct got_object_id **tail, int ntail,
1180     struct got_repository *repo,
1181     got_cancel_cb cancel_cb, void *cancel_arg)
1182 {
1183 	const struct got_error *err = NULL;
1184 	struct got_object_id_queue ids;
1185 	struct got_object_idset *keep, *drop;
1186 	struct got_object_qid *qid;
1187 	int i, ncolor, nkeep, obj_type;
1188 
1189 	STAILQ_INIT(&ids);
1190 	*res = NULL;
1191 	*nres = 0;
1192 
1193 	keep = got_object_idset_alloc();
1194 	if (keep == NULL)
1195 		return got_error_from_errno("got_object_idset_alloc");
1196 
1197 	drop = got_object_idset_alloc();
1198 	if (drop == NULL) {
1199 		err = got_error_from_errno("got_object_idset_alloc");
1200 		goto done;
1201 	}
1202 
1203 	for (i = 0; i < nhead; i++) {
1204 		struct got_object_id *id = head[i];
1205 		if (id == NULL)
1206 			continue;
1207 		err = got_object_get_type(&obj_type, repo, id);
1208 		if (err)
1209 			return err;
1210 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1211 			continue;
1212 		err = queue_commit_id(&ids, id, COLOR_KEEP, repo);
1213 		if (err)
1214 			goto done;
1215 	}		
1216 	for (i = 0; i < ntail; i++) {
1217 		struct got_object_id *id = tail[i];
1218 		if (id == NULL)
1219 			continue;
1220 		err = got_object_get_type(&obj_type, repo, id);
1221 		if (err)
1222 			return err;
1223 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1224 			continue;
1225 		err = queue_commit_id(&ids, id, COLOR_DROP, repo);
1226 		if (err)
1227 			goto done;
1228 	}
1229 
1230 	while (!STAILQ_EMPTY(&ids)) {
1231 		int qcolor;
1232 		qid = STAILQ_FIRST(&ids);
1233 		qcolor = *((int *)qid->data);
1234 
1235 		if (got_object_idset_contains(drop, qid->id))
1236 			ncolor = COLOR_DROP;
1237 		else if (got_object_idset_contains(keep, qid->id))
1238 			ncolor = COLOR_KEEP;
1239 		else
1240 			ncolor = COLOR_BLANK;
1241 
1242 		if (ncolor == COLOR_DROP || (ncolor == COLOR_KEEP &&
1243 		    qcolor == COLOR_KEEP)) {
1244 			STAILQ_REMOVE_HEAD(&ids, entry);
1245 			got_object_qid_free(qid);
1246 			continue;
1247 		}
1248 
1249 		if (ncolor == COLOR_KEEP && qcolor == COLOR_DROP) {
1250 			err = drop_commit(keep, drop, qid->id, repo,
1251 			    cancel_cb, cancel_arg);
1252 			if (err)
1253 				goto done;
1254 		} else if (ncolor == COLOR_BLANK) {
1255 			struct got_commit_object *commit;
1256 			struct got_object_id *id;
1257 			const struct got_object_id_queue *parents;
1258 			struct got_object_qid *pid;
1259 
1260 			id = got_object_id_dup(qid->id);
1261 			if (id == NULL) {
1262 				err = got_error_from_errno("got_object_id_dup");
1263 				goto done;
1264 			}
1265 			if (qcolor == COLOR_KEEP)
1266 				err = got_object_idset_add(keep, id,
1267 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1268 			else
1269 				err = got_object_idset_add(drop, id,
1270 				    (void *)&obj_types[GOT_OBJ_TYPE_COMMIT]);
1271 			if (err) {
1272 				free(id);
1273 				goto done;
1274 			}
1275 
1276 			err = got_object_open_as_commit(&commit, repo, id);
1277 			if (err) {
1278 				free(id);
1279 				goto done;
1280 			}
1281 			parents = got_object_commit_get_parent_ids(commit);
1282 			if (parents) {
1283 				STAILQ_FOREACH(pid, parents, entry) {
1284 					err = queue_commit_id(&ids, pid->id,
1285 					    qcolor, repo);
1286 					if (err) {
1287 						free(id);
1288 						goto done;
1289 					}
1290 				}
1291 			}
1292 			got_object_commit_close(commit);
1293 			commit = NULL;
1294 		} else {
1295 			/* should not happen */
1296 			err = got_error_fmt(GOT_ERR_NOT_IMPL,
1297 			    "%s ncolor=%d qcolor=%d", __func__, ncolor, qcolor);
1298 			goto done;
1299 		}
1300 
1301 		STAILQ_REMOVE_HEAD(&ids, entry);
1302 		got_object_qid_free(qid);
1303 	}
1304 
1305 	nkeep = got_object_idset_num_elements(keep);
1306 	if (nkeep > 0) {
1307 		struct append_id_arg arg;
1308 		arg.array = calloc(nkeep, sizeof(struct got_object_id *));
1309 		if (arg.array == NULL) {
1310 			err = got_error_from_errno("calloc");
1311 			goto done;
1312 		}
1313 		arg.idx = 0;
1314 		err = got_object_idset_for_each(keep, append_id, &arg);
1315 		if (err) {
1316 			free(arg.array);
1317 			goto done;
1318 		}
1319 		*res = arg.array;
1320 		*nres = nkeep;
1321 	}
1322 done:
1323 	got_object_idset_free(keep);
1324 	got_object_idset_free(drop);
1325 	got_object_id_queue_free(&ids);
1326 	return err;
1327 }
1328 
1329 static const struct got_error *
1330 load_object_ids(struct got_object_idset *idset,
1331     struct got_object_id **theirs, int ntheirs,
1332     struct got_object_id **ours, int nours, struct got_repository *repo,
1333     int loose_obj_only, got_cancel_cb cancel_cb, void *cancel_arg)
1334 {
1335 	const struct got_error *err = NULL;
1336 	struct got_object_id **ids = NULL;
1337 	int i, nobj = 0, obj_type;
1338 
1339 	err = findtwixt(&ids, &nobj, ours, nours, theirs, ntheirs, repo,
1340 	    cancel_cb, cancel_arg);
1341 	if (err || nobj == 0)
1342 		goto done;
1343 
1344 	for (i = 0; i < ntheirs; i++) {
1345 		struct got_object_id *id = theirs[i];
1346 		if (id == NULL)
1347 			continue;
1348 		err = got_object_get_type(&obj_type, repo, id);
1349 		if (err)
1350 			return err;
1351 		if (obj_type != GOT_OBJ_TYPE_COMMIT)
1352 			continue;
1353 		err = load_commit(0, idset, id, repo,
1354 		    loose_obj_only, cancel_cb, cancel_arg);
1355 		if (err)
1356 			goto done;
1357 	}
1358 
1359 	for (i = 0; i < ntheirs; i++) {
1360 		struct got_object_id *id = theirs[i];
1361 		struct got_pack_meta *m;
1362 		if (id == NULL)
1363 			continue;
1364 		m = got_object_idset_get(idset, id);
1365 		if (m == NULL) {
1366 			err = got_object_get_type(&obj_type, repo, id);
1367 			if (err)
1368 				goto done;
1369 		} else
1370 			obj_type = m->obj_type;
1371 		if (obj_type != GOT_OBJ_TYPE_TAG)
1372 			continue;
1373 		err = load_tag(0, idset, id, repo,
1374 		    loose_obj_only, cancel_cb, cancel_arg);
1375 		if (err)
1376 			goto done;
1377 	}
1378 
1379 	for (i = 0; i < nobj; i++) {
1380 		err = load_commit(1, idset, ids[i], repo,
1381 		    loose_obj_only, cancel_cb, cancel_arg);
1382 		if (err)
1383 			goto done;
1384 	}
1385 
1386 	for (i = 0; i < nours; i++) {
1387 		struct got_object_id *id = ours[i];
1388 		struct got_pack_meta *m;
1389 		if (id == NULL)
1390 			continue;
1391 		m = got_object_idset_get(idset, id);
1392 		if (m == NULL) {
1393 			err = got_object_get_type(&obj_type, repo, id);
1394 			if (err)
1395 				goto done;
1396 		} else
1397 			obj_type = m->obj_type;
1398 		if (obj_type != GOT_OBJ_TYPE_TAG)
1399 			continue;
1400 		err = load_tag(1, idset, id, repo,
1401 		    loose_obj_only, cancel_cb, cancel_arg);
1402 		if (err)
1403 			goto done;
1404 	}
1405 done:
1406 	for (i = 0; i < nobj; i++) {
1407 		free(ids[i]);
1408 	}
1409 	free(ids);
1410 	return err;
1411 }
1412 
1413 const struct got_error *
1414 hwrite(FILE *f, void *buf, int len, SHA1_CTX *ctx)
1415 {
1416 	size_t n;
1417 
1418 	SHA1Update(ctx, buf, len);
1419 	n = fwrite(buf, 1, len, f);
1420 	if (n != len)
1421 		return got_ferror(f, GOT_ERR_IO);
1422 	return NULL;
1423 }
1424 
1425 static void
1426 putbe32(char *b, uint32_t n)
1427 {
1428 	b[0] = n >> 24;
1429 	b[1] = n >> 16;
1430 	b[2] = n >> 8;
1431 	b[3] = n >> 0;
1432 }
1433 
1434 static int
1435 write_order_cmp(const void *pa, const void *pb)
1436 {
1437 	struct got_pack_meta *a, *b, *ahd, *bhd;
1438 
1439 	a = *(struct got_pack_meta **)pa;
1440 	b = *(struct got_pack_meta **)pb;
1441 	ahd = (a->head == NULL) ? a : a->head;
1442 	bhd = (b->head == NULL) ? b : b->head;
1443 	if (ahd->mtime != bhd->mtime)
1444 		return bhd->mtime - ahd->mtime;
1445 	if (ahd != bhd)
1446 		return (uintptr_t)bhd - (uintptr_t)ahd;
1447 	if (a->nchain != b->nchain)
1448 		return a->nchain - b->nchain;
1449 	return a->mtime - b->mtime;
1450 }
1451 
1452 static int
1453 reuse_write_order_cmp(const void *pa, const void *pb)
1454 {
1455 	struct got_pack_meta *a, *b;
1456 
1457 	a = *(struct got_pack_meta **)pa;
1458 	b = *(struct got_pack_meta **)pb;
1459 
1460 	if (a->reused_delta_offset < b->reused_delta_offset)
1461 		return -1;
1462 	if (a->reused_delta_offset > b->reused_delta_offset)
1463 		return 1;
1464 	return 0;
1465 }
1466 
1467 static const struct got_error *
1468 packhdr(int *hdrlen, char *hdr, size_t bufsize, int obj_type, size_t len)
1469 {
1470 	size_t i;
1471 
1472 	*hdrlen = 0;
1473 
1474 	hdr[0] = obj_type << 4;
1475 	hdr[0] |= len & 0xf;
1476 	len >>= 4;
1477 	for (i = 1; len != 0; i++){
1478 		if (i >= bufsize)
1479 			return got_error(GOT_ERR_NO_SPACE);
1480 		hdr[i - 1] |= GOT_DELTA_SIZE_MORE;
1481 		hdr[i] = len & GOT_DELTA_SIZE_VAL_MASK;
1482 		len >>= GOT_DELTA_SIZE_SHIFT;
1483 	}
1484 
1485 	*hdrlen = i;
1486 	return NULL;
1487 }
1488 
1489 static int
1490 packoff(char *hdr, off_t off)
1491 {
1492 	int i, j;
1493 	char rbuf[8];
1494 
1495 	rbuf[0] = off & GOT_DELTA_SIZE_VAL_MASK;
1496 	for (i = 1; (off >>= GOT_DELTA_SIZE_SHIFT) != 0; i++) {
1497 		rbuf[i] = (--off & GOT_DELTA_SIZE_VAL_MASK) |
1498 		    GOT_DELTA_SIZE_MORE;
1499 	}
1500 
1501 	j = 0;
1502 	while (i > 0)
1503 		hdr[j++] = rbuf[--i];
1504 	return j;
1505 }
1506 
1507 static const struct got_error *
1508 deltahdr(off_t *packfile_size, SHA1_CTX *ctx, FILE *packfile,
1509     struct got_pack_meta *m)
1510 {
1511 	const struct got_error *err;
1512 	char buf[32];
1513 	int nh;
1514 
1515 	if (m->prev->off != 0) {
1516 		err = packhdr(&nh, buf, sizeof(buf),
1517 		    GOT_OBJ_TYPE_OFFSET_DELTA, m->delta_len);
1518 		if (err)
1519 			return err;
1520 		nh += packoff(buf + nh, m->off - m->prev->off);
1521 		err = hwrite(packfile, buf, nh, ctx);
1522 		if (err)
1523 			return err;
1524 		*packfile_size += nh;
1525 	} else {
1526 		err = packhdr(&nh, buf, sizeof(buf),
1527 		    GOT_OBJ_TYPE_REF_DELTA, m->delta_len);
1528 		if (err)
1529 			return err;
1530 		err = hwrite(packfile, buf, nh, ctx);
1531 		if (err)
1532 			return err;
1533 		*packfile_size += nh;
1534 		err = hwrite(packfile, m->prev->id.sha1,
1535 		    sizeof(m->prev->id.sha1), ctx);
1536 		if (err)
1537 			return err;
1538 		*packfile_size += sizeof(m->prev->id.sha1);
1539 	}
1540 
1541 	return NULL;
1542 }
1543 
1544 static const struct got_error *
1545 write_packed_object(off_t *packfile_size, FILE *packfile,
1546     FILE *delta_cache, struct got_pack_meta *m, int *outfd,
1547     SHA1_CTX *ctx, struct got_repository *repo)
1548 {
1549 	const struct got_error *err = NULL;
1550 	struct got_deflate_checksum csum;
1551 	char buf[32];
1552 	int nh;
1553 	struct got_raw_object *raw = NULL;
1554 	off_t outlen;
1555 
1556 	csum.output_sha1 = ctx;
1557 	csum.output_crc = NULL;
1558 
1559 	m->off = ftello(packfile);
1560 	if (m->delta_len == 0) {
1561 		err = got_object_raw_open(&raw, outfd, repo, &m->id);
1562 		if (err)
1563 			goto done;
1564 		err = packhdr(&nh, buf, sizeof(buf),
1565 		    m->obj_type, raw->size);
1566 		if (err)
1567 			goto done;
1568 		err = hwrite(packfile, buf, nh, ctx);
1569 		if (err)
1570 			goto done;
1571 		*packfile_size += nh;
1572 		if (raw->f == NULL) {
1573 			err = got_deflate_to_file_mmap(&outlen,
1574 			    raw->data + raw->hdrlen, 0, raw->size,
1575 			    packfile, &csum);
1576 			if (err)
1577 				goto done;
1578 		} else {
1579 			if (fseeko(raw->f, raw->hdrlen, SEEK_SET)
1580 			    == -1) {
1581 				err = got_error_from_errno("fseeko");
1582 				goto done;
1583 			}
1584 			err = got_deflate_to_file(&outlen, raw->f,
1585 			    raw->size, packfile, &csum);
1586 			if (err)
1587 				goto done;
1588 		}
1589 		*packfile_size += outlen;
1590 		got_object_raw_close(raw);
1591 		raw = NULL;
1592 	} else if (m->delta_buf) {
1593 		err = deltahdr(packfile_size, ctx, packfile, m);
1594 		if (err)
1595 			goto done;
1596 		err = got_deflate_to_file_mmap(&outlen,
1597 		    m->delta_buf, 0, m->delta_len, packfile, &csum);
1598 		if (err)
1599 			goto done;
1600 		*packfile_size += outlen;
1601 		free(m->delta_buf);
1602 		m->delta_buf = NULL;
1603 	} else {
1604 		if (fseeko(delta_cache, m->delta_offset, SEEK_SET)
1605 		    == -1) {
1606 			err = got_error_from_errno("fseeko");
1607 			goto done;
1608 		}
1609 		err = deltahdr(packfile_size, ctx, packfile, m);
1610 		if (err)
1611 			goto done;
1612 		err = got_deflate_to_file(&outlen, delta_cache,
1613 		    m->delta_len, packfile, &csum);
1614 		if (err)
1615 			goto done;
1616 		*packfile_size += outlen;
1617 	}
1618 done:
1619 	if (raw)
1620 		got_object_raw_close(raw);
1621 	return err;
1622 }
1623 
1624 static const struct got_error *
1625 genpack(uint8_t *pack_sha1, FILE *packfile, FILE *delta_cache,
1626     struct got_pack_meta **deltify, int ndeltify,
1627     struct got_pack_meta **reuse, int nreuse,
1628     int nours, struct got_repository *repo,
1629     got_pack_progress_cb progress_cb, void *progress_arg,
1630     struct got_ratelimit *rl,
1631     got_cancel_cb cancel_cb, void *cancel_arg)
1632 {
1633 	const struct got_error *err = NULL;
1634 	int i;
1635 	SHA1_CTX ctx;
1636 	struct got_pack_meta *m;
1637 	char buf[32];
1638 	size_t n;
1639 	off_t packfile_size = 0;
1640 	int outfd = -1;
1641 
1642 	SHA1Init(&ctx);
1643 
1644 	err = hwrite(packfile, "PACK", 4, &ctx);
1645 	if (err)
1646 		return err;
1647 	putbe32(buf, GOT_PACKFILE_VERSION);
1648 	err = hwrite(packfile, buf, 4, &ctx);
1649 	if (err)
1650 		goto done;
1651 	putbe32(buf, ndeltify + nreuse);
1652 	err = hwrite(packfile, buf, 4, &ctx);
1653 	if (err)
1654 		goto done;
1655 
1656 	qsort(deltify, ndeltify, sizeof(struct got_pack_meta *),
1657 	    write_order_cmp);
1658 	for (i = 0; i < ndeltify; i++) {
1659 		err = report_progress(progress_cb, progress_arg, rl,
1660 		    packfile_size, nours, ndeltify + nreuse,
1661 		    ndeltify + nreuse, i);
1662 		if (err)
1663 			goto done;
1664 		m = deltify[i];
1665 		err = write_packed_object(&packfile_size, packfile,
1666 		    delta_cache, m, &outfd, &ctx, repo);
1667 		if (err)
1668 			goto done;
1669 	}
1670 
1671 	qsort(reuse, nreuse, sizeof(struct got_pack_meta *),
1672 	    reuse_write_order_cmp);
1673 	for (i = 0; i < nreuse; i++) {
1674 		err = report_progress(progress_cb, progress_arg, rl,
1675 		    packfile_size, nours, ndeltify + nreuse,
1676 		    ndeltify + nreuse, ndeltify + i);
1677 		if (err)
1678 			goto done;
1679 		m = reuse[i];
1680 		err = write_packed_object(&packfile_size, packfile,
1681 		    delta_cache, m, &outfd, &ctx, repo);
1682 		if (err)
1683 			goto done;
1684 	}
1685 
1686 	SHA1Final(pack_sha1, &ctx);
1687 	n = fwrite(pack_sha1, 1, SHA1_DIGEST_LENGTH, packfile);
1688 	if (n != SHA1_DIGEST_LENGTH)
1689 		err = got_ferror(packfile, GOT_ERR_IO);
1690 	packfile_size += SHA1_DIGEST_LENGTH;
1691 	packfile_size += sizeof(struct got_packfile_hdr);
1692 	if (progress_cb) {
1693 		err = progress_cb(progress_arg, packfile_size, nours,
1694 		    ndeltify + nreuse, ndeltify + nreuse,
1695 		    ndeltify + nreuse);
1696 		if (err)
1697 			goto done;
1698 	}
1699 done:
1700 	if (outfd != -1 && close(outfd) == -1 && err == NULL)
1701 		err = got_error_from_errno("close");
1702 	return err;
1703 }
1704 
1705 static const struct got_error *
1706 remove_unused_object(struct got_object_idset_element *entry, void *arg)
1707 {
1708 	struct got_object_idset *idset = arg;
1709 
1710 	if (got_object_idset_get_element_data(entry) == NULL)
1711 		got_object_idset_remove_element(idset, entry);
1712 
1713 	return NULL;
1714 }
1715 
1716 static const struct got_error *
1717 remove_reused_object(struct got_object_idset_element *entry, void *arg)
1718 {
1719 	struct got_object_idset *idset = arg;
1720 	struct got_pack_meta *m;
1721 
1722 	m = got_object_idset_get_element_data(entry);
1723 	if (m->have_reused_delta)
1724 		got_object_idset_remove_element(idset, entry);
1725 
1726 	return NULL;
1727 }
1728 
1729 static const struct got_error *
1730 add_meta_idset_cb(struct got_object_id *id, void *data, void *arg)
1731 {
1732 	struct got_pack_meta *m = data;
1733 	struct got_pack_metavec *v = arg;
1734 
1735 	return add_meta(m, v);
1736 }
1737 
1738 const struct got_error *
1739 got_pack_create(uint8_t *packsha1, FILE *packfile,
1740     struct got_object_id **theirs, int ntheirs,
1741     struct got_object_id **ours, int nours,
1742     struct got_repository *repo, int loose_obj_only, int allow_empty,
1743     got_pack_progress_cb progress_cb, void *progress_arg,
1744     got_cancel_cb cancel_cb, void *cancel_arg)
1745 {
1746 	const struct got_error *err;
1747 	int delta_cache_fd = -1;
1748 	FILE *delta_cache = NULL;
1749 	struct got_object_idset *idset;
1750 	struct got_ratelimit rl;
1751 	struct got_pack_metavec deltify, reuse;
1752 
1753 	memset(&deltify, 0, sizeof(deltify));
1754 	memset(&reuse, 0, sizeof(reuse));
1755 
1756 	got_ratelimit_init(&rl, 0, 500);
1757 
1758 	idset = got_object_idset_alloc();
1759 	if (idset == NULL)
1760 		return got_error_from_errno("got_object_idset_alloc");
1761 
1762 	err = load_object_ids(idset, theirs, ntheirs, ours, nours,
1763 	    repo, loose_obj_only, cancel_cb, cancel_arg);
1764 	if (err)
1765 		return err;
1766 
1767 	err = got_object_idset_for_each_element(idset,
1768 	    remove_unused_object, idset);
1769 	if (err)
1770 		goto done;
1771 
1772 	if (progress_cb) {
1773 		err = progress_cb(progress_arg, 0L, nours,
1774 		    got_object_idset_num_elements(idset), 0, 0);
1775 		if (err)
1776 			goto done;
1777 	}
1778 
1779 	if (got_object_idset_num_elements(idset) == 0 && !allow_empty) {
1780 		err = got_error(GOT_ERR_CANNOT_PACK);
1781 		goto done;
1782 	}
1783 
1784 	delta_cache_fd = got_opentempfd();
1785 	if (delta_cache_fd == -1) {
1786 		err = got_error_from_errno("got_opentemp");
1787 		goto done;
1788 	}
1789 
1790 	reuse.metasz = 64;
1791 	reuse.meta = calloc(reuse.metasz,
1792 	    sizeof(struct got_pack_meta *));
1793 	if (reuse.meta == NULL) {
1794 		err = got_error_from_errno("calloc");
1795 		goto done;
1796 	}
1797 
1798 	err = search_deltas(&reuse, idset, delta_cache_fd, nours, repo,
1799 	    progress_cb, progress_arg, &rl, cancel_cb, cancel_arg);
1800 	if (err)
1801 		goto done;
1802 	if (reuse.nmeta > 0) {
1803 		err = got_object_idset_for_each_element(idset,
1804 		    remove_reused_object, idset);
1805 		if (err)
1806 			goto done;
1807 	}
1808 
1809 	delta_cache = fdopen(delta_cache_fd, "a+");
1810 	if (delta_cache == NULL) {
1811 		err = got_error_from_errno("fdopen");
1812 		goto done;
1813 	}
1814 	delta_cache_fd = -1;
1815 
1816 	if (fseeko(delta_cache, 0L, SEEK_END) == -1) {
1817 		err = got_error_from_errno("fseeko");
1818 		goto done;
1819 	}
1820 
1821 	deltify.meta = calloc(got_object_idset_num_elements(idset),
1822 	    sizeof(struct got_pack_meta *));
1823 	if (deltify.meta == NULL) {
1824 		err = got_error_from_errno("calloc");
1825 		goto done;
1826 	}
1827 	deltify.metasz = got_object_idset_num_elements(idset);
1828 
1829 	err = got_object_idset_for_each(idset, add_meta_idset_cb, &deltify);
1830 	if (err)
1831 		goto done;
1832 	if (deltify.nmeta > 0) {
1833 		err = pick_deltas(deltify.meta, deltify.nmeta, nours,
1834 		    reuse.nmeta, delta_cache, repo,
1835 		    progress_cb, progress_arg, &rl, cancel_cb, cancel_arg);
1836 		if (err)
1837 			goto done;
1838 		if (fseeko(delta_cache, 0L, SEEK_SET) == -1) {
1839 			err = got_error_from_errno("fseeko");
1840 			goto done;
1841 		}
1842 	}
1843 
1844 	err = genpack(packsha1, packfile, delta_cache, deltify.meta,
1845 	    deltify.nmeta, reuse.meta, reuse.nmeta, nours, repo,
1846 	    progress_cb, progress_arg, &rl, cancel_cb, cancel_arg);
1847 	if (err)
1848 		goto done;
1849 done:
1850 	free_nmeta(deltify.meta, deltify.nmeta);
1851 	free_nmeta(reuse.meta, reuse.nmeta);
1852 	got_object_idset_free(idset);
1853 	if (delta_cache_fd != -1 && close(delta_cache_fd) == -1 && err == NULL)
1854 		err = got_error_from_errno("close");
1855 	if (delta_cache && fclose(delta_cache) == EOF && err == NULL)
1856 		err = got_error_from_errno("fclose");
1857 	return err;
1858 }