1 /*
2  * Copyright (c) 2018, 2019, 2020 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 #include <sys/uio.h>
21 #include <sys/mman.h>
22 
23 #include <fcntl.h>
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdint.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <limits.h>
30 #include <sha1.h>
31 #include <endian.h>
32 #include <unistd.h>
33 #include <zlib.h>
34 #include <imsg.h>
35 
36 #include "got_error.h"
37 #include "got_object.h"
38 #include "got_opentemp.h"
39 #include "got_path.h"
40 
41 #include "got_lib_sha1.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_delta_cache.h"
44 #include "got_lib_inflate.h"
45 #include "got_lib_object.h"
46 #include "got_lib_object_parse.h"
47 #include "got_lib_privsep.h"
48 #include "got_lib_pack.h"
49 
50 #ifndef nitems
51 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
52 #endif
53 
54 #ifndef MIN
55 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
56 #endif
57 
58 static const struct got_error *
59 verify_fanout_table(uint32_t *fanout_table)
60 {
61 	int i;
62 
63 	for (i = 0; i < 0xff - 1; i++) {
64 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
65 			return got_error(GOT_ERR_BAD_PACKIDX);
66 	}
67 
68 	return NULL;
69 }
70 
71 const struct got_error *
72 got_packidx_init_hdr(struct got_packidx *p, int verify)
73 {
74 	const struct got_error *err = NULL;
75 	struct got_packidx_v2_hdr *h;
76 	SHA1_CTX ctx;
77 	uint8_t sha1[SHA1_DIGEST_LENGTH];
78 	size_t nobj, len_fanout, len_ids, offset, remain;
79 	ssize_t n;
80 	int i;
81 
82 	SHA1Init(&ctx);
83 
84 	h = &p->hdr;
85 	offset = 0;
86 	remain = p->len;
87 
88 	if (remain < sizeof(*h->magic)) {
89 		err = got_error(GOT_ERR_BAD_PACKIDX);
90 		goto done;
91 	}
92 	if (p->map)
93 		h->magic = (uint32_t *)(p->map + offset);
94 	else {
95 		h->magic = malloc(sizeof(*h->magic));
96 		if (h->magic == NULL) {
97 			err = got_error_from_errno("malloc");
98 			goto done;
99 		}
100 		n = read(p->fd, h->magic, sizeof(*h->magic));
101 		if (n < 0) {
102 			err = got_error_from_errno("read");
103 			goto done;
104 		} else if (n != sizeof(*h->magic)) {
105 			err = got_error(GOT_ERR_BAD_PACKIDX);
106 			goto done;
107 		}
108 	}
109 	if (*h->magic != htobe32(GOT_PACKIDX_V2_MAGIC)) {
110 		err = got_error(GOT_ERR_BAD_PACKIDX);
111 		goto done;
112 	}
113 	offset += sizeof(*h->magic);
114 	remain -= sizeof(*h->magic);
115 
116 	if (verify)
117 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
118 
119 	if (remain < sizeof(*h->version)) {
120 		err = got_error(GOT_ERR_BAD_PACKIDX);
121 		goto done;
122 	}
123 	if (p->map)
124 		h->version = (uint32_t *)(p->map + offset);
125 	else {
126 		h->version = malloc(sizeof(*h->version));
127 		if (h->version == NULL) {
128 			err = got_error_from_errno("malloc");
129 			goto done;
130 		}
131 		n = read(p->fd, h->version, sizeof(*h->version));
132 		if (n < 0) {
133 			err = got_error_from_errno("read");
134 			goto done;
135 		} else if (n != sizeof(*h->version)) {
136 			err = got_error(GOT_ERR_BAD_PACKIDX);
137 			goto done;
138 		}
139 	}
140 	if (*h->version != htobe32(GOT_PACKIDX_VERSION)) {
141 		err = got_error(GOT_ERR_BAD_PACKIDX);
142 		goto done;
143 	}
144 	offset += sizeof(*h->version);
145 	remain -= sizeof(*h->version);
146 
147 	if (verify)
148 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
149 
150 	len_fanout =
151 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
152 	if (remain < len_fanout) {
153 		err = got_error(GOT_ERR_BAD_PACKIDX);
154 		goto done;
155 	}
156 	if (p->map)
157 		h->fanout_table = (uint32_t *)(p->map + offset);
158 	else {
159 		h->fanout_table = malloc(len_fanout);
160 		if (h->fanout_table == NULL) {
161 			err = got_error_from_errno("malloc");
162 			goto done;
163 		}
164 		n = read(p->fd, h->fanout_table, len_fanout);
165 		if (n < 0) {
166 			err = got_error_from_errno("read");
167 			goto done;
168 		} else if (n != len_fanout) {
169 			err = got_error(GOT_ERR_BAD_PACKIDX);
170 			goto done;
171 		}
172 	}
173 	err = verify_fanout_table(h->fanout_table);
174 	if (err)
175 		goto done;
176 	if (verify)
177 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
178 	offset += len_fanout;
179 	remain -= len_fanout;
180 
181 	nobj = be32toh(h->fanout_table[0xff]);
182 	len_ids = nobj * sizeof(*h->sorted_ids);
183 	if (len_ids <= nobj || len_ids > remain) {
184 		err = got_error(GOT_ERR_BAD_PACKIDX);
185 		goto done;
186 	}
187 	if (p->map)
188 		h->sorted_ids =
189 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
190 	else {
191 		h->sorted_ids = malloc(len_ids);
192 		if (h->sorted_ids == NULL) {
193 			err = got_error(GOT_ERR_BAD_PACKIDX);
194 			goto done;
195 		}
196 		n = read(p->fd, h->sorted_ids, len_ids);
197 		if (n < 0)
198 			err = got_error_from_errno("read");
199 		else if (n != len_ids) {
200 			err = got_error(GOT_ERR_BAD_PACKIDX);
201 			goto done;
202 		}
203 	}
204 	if (verify)
205 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
206 	offset += len_ids;
207 	remain -= len_ids;
208 
209 	if (remain < nobj * sizeof(*h->crc32)) {
210 		err = got_error(GOT_ERR_BAD_PACKIDX);
211 		goto done;
212 	}
213 	if (p->map)
214 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
215 	else {
216 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
217 		if (h->crc32 == NULL) {
218 			err = got_error_from_errno("malloc");
219 			goto done;
220 		}
221 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
222 		if (n < 0)
223 			err = got_error_from_errno("read");
224 		else if (n != nobj * sizeof(*h->crc32)) {
225 			err = got_error(GOT_ERR_BAD_PACKIDX);
226 			goto done;
227 		}
228 	}
229 	if (verify)
230 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
231 	remain -= nobj * sizeof(*h->crc32);
232 	offset += nobj * sizeof(*h->crc32);
233 
234 	if (remain < nobj * sizeof(*h->offsets)) {
235 		err = got_error(GOT_ERR_BAD_PACKIDX);
236 		goto done;
237 	}
238 	if (p->map)
239 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
240 	else {
241 		h->offsets = malloc(nobj * sizeof(*h->offsets));
242 		if (h->offsets == NULL) {
243 			err = got_error_from_errno("malloc");
244 			goto done;
245 		}
246 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
247 		if (n < 0)
248 			err = got_error_from_errno("read");
249 		else if (n != nobj * sizeof(*h->offsets)) {
250 			err = got_error(GOT_ERR_BAD_PACKIDX);
251 			goto done;
252 		}
253 	}
254 	if (verify)
255 		SHA1Update(&ctx, (uint8_t *)h->offsets,
256 		    nobj * sizeof(*h->offsets));
257 	remain -= nobj * sizeof(*h->offsets);
258 	offset += nobj * sizeof(*h->offsets);
259 
260 	/* Large file offsets are contained only in files > 2GB. */
261 	for (i = 0; i < nobj; i++) {
262 		uint32_t o = h->offsets[i];
263 		if (o & htobe32(GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX))
264 			p->nlargeobj++;
265 	}
266 	if (p->nlargeobj == 0)
267 		goto checksum;
268 
269 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
270 		err = got_error(GOT_ERR_BAD_PACKIDX);
271 		goto done;
272 	}
273 	if (p->map)
274 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
275 	else {
276 		h->large_offsets = malloc(p->nlargeobj *
277 		    sizeof(*h->large_offsets));
278 		if (h->large_offsets == NULL) {
279 			err = got_error_from_errno("malloc");
280 			goto done;
281 		}
282 		n = read(p->fd, h->large_offsets,
283 		    p->nlargeobj * sizeof(*h->large_offsets));
284 		if (n < 0)
285 			err = got_error_from_errno("read");
286 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
287 			err = got_error(GOT_ERR_BAD_PACKIDX);
288 			goto done;
289 		}
290 	}
291 	if (verify)
292 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
293 		    p->nlargeobj * sizeof(*h->large_offsets));
294 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
295 	offset += p->nlargeobj * sizeof(*h->large_offsets);
296 
297 checksum:
298 	if (remain < sizeof(*h->trailer)) {
299 		err = got_error(GOT_ERR_BAD_PACKIDX);
300 		goto done;
301 	}
302 	if (p->map)
303 		h->trailer =
304 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
305 	else {
306 		h->trailer = malloc(sizeof(*h->trailer));
307 		if (h->trailer == NULL) {
308 			err = got_error_from_errno("malloc");
309 			goto done;
310 		}
311 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
312 		if (n < 0)
313 			err = got_error_from_errno("read");
314 		else if (n != sizeof(*h->trailer)) {
315 			err = got_error(GOT_ERR_BAD_PACKIDX);
316 			goto done;
317 		}
318 	}
319 	if (verify) {
320 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
321 		SHA1Final(sha1, &ctx);
322 		if (memcmp(h->trailer->packidx_sha1, sha1,
323 		    SHA1_DIGEST_LENGTH) != 0)
324 			err = got_error(GOT_ERR_PACKIDX_CSUM);
325 	}
326 done:
327 	return err;
328 }
329 
330 const struct got_error *
331 got_packidx_open(struct got_packidx **packidx,
332     int dir_fd, const char *relpath, int verify)
333 {
334 	const struct got_error *err = NULL;
335 	struct got_packidx *p;
336 	struct stat sb;
337 
338 	*packidx = NULL;
339 
340 	p = calloc(1, sizeof(*p));
341 	if (p == NULL)
342 		return got_error_from_errno("calloc");
343 
344 	p->fd = openat(dir_fd, relpath, O_RDONLY | O_NOFOLLOW);
345 	if (p->fd == -1) {
346 		err = got_error_from_errno2("openat", relpath);
347 		free(p);
348 		return err;
349 	}
350 
351 	if (fstat(p->fd, &sb) != 0) {
352 		err = got_error_from_errno2("fstat", relpath);
353 		close(p->fd);
354 		free(p);
355 		return err;
356 	}
357 	p->len = sb.st_size;
358 	if (p->len < sizeof(p->hdr)) {
359 		err = got_error(GOT_ERR_BAD_PACKIDX);
360 		close(p->fd);
361 		free(p);
362 		return err;
363 	}
364 
365 	p->path_packidx = strdup(relpath);
366 	if (p->path_packidx == NULL) {
367 		err = got_error_from_errno("strdup");
368 		goto done;
369 	}
370 
371 #ifndef GOT_PACK_NO_MMAP
372 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
373 	if (p->map == MAP_FAILED) {
374 		if (errno != ENOMEM) {
375 			err = got_error_from_errno("mmap");
376 			goto done;
377 		}
378 		p->map = NULL; /* fall back to read(2) */
379 	}
380 #endif
381 
382 	err = got_packidx_init_hdr(p, verify);
383 done:
384 	if (err)
385 		got_packidx_close(p);
386 	else
387 		*packidx = p;
388 
389 	return err;
390 }
391 
392 const struct got_error *
393 got_packidx_close(struct got_packidx *packidx)
394 {
395 	const struct got_error *err = NULL;
396 
397 	free(packidx->path_packidx);
398 	if (packidx->map) {
399 		if (munmap(packidx->map, packidx->len) == -1)
400 			err = got_error_from_errno("munmap");
401 	} else {
402 		free(packidx->hdr.magic);
403 		free(packidx->hdr.version);
404 		free(packidx->hdr.fanout_table);
405 		free(packidx->hdr.sorted_ids);
406 		free(packidx->hdr.crc32);
407 		free(packidx->hdr.offsets);
408 		free(packidx->hdr.large_offsets);
409 		free(packidx->hdr.trailer);
410 	}
411 	if (close(packidx->fd) == -1 && err == NULL)
412 		err = got_error_from_errno("close");
413 	free(packidx);
414 
415 	return err;
416 }
417 
418 const struct got_error *
419 got_packidx_get_packfile_path(char **path_packfile, struct got_packidx *packidx)
420 {
421 	size_t size;
422 
423 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
424 	size = strlen(packidx->path_packidx) + 2;
425 	if (size < GOT_PACKFILE_NAMELEN + 1)
426 		return got_error_path(packidx->path_packidx, GOT_ERR_BAD_PATH);
427 
428 	*path_packfile = malloc(size);
429 	if (*path_packfile == NULL)
430 		return got_error_from_errno("malloc");
431 
432 	/* Copy up to and excluding ".idx". */
433 	if (strlcpy(*path_packfile, packidx->path_packidx,
434 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
435 		return got_error(GOT_ERR_NO_SPACE);
436 
437 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
438 		return got_error(GOT_ERR_NO_SPACE);
439 
440 	return NULL;
441 }
442 
443 off_t
444 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
445 {
446 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
447 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
448 		uint64_t loffset;
449 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
450 		if (idx < 0 || idx >= packidx->nlargeobj ||
451 		    packidx->hdr.large_offsets == NULL)
452 			return -1;
453 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
454 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
455 	}
456 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
457 }
458 
459 int
460 got_packidx_get_object_idx(struct got_packidx *packidx, struct got_object_id *id)
461 {
462 	u_int8_t id0 = id->sha1[0];
463 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
464 	int left = 0, right = totobj - 1;
465 
466 	if (id0 > 0)
467 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
468 
469 	while (left <= right) {
470 		struct got_packidx_object_id *oid;
471 		int i, cmp;
472 
473 		i = ((left + right) / 2);
474 		oid = &packidx->hdr.sorted_ids[i];
475 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
476 		if (cmp == 0)
477 			return i;
478 		else if (cmp > 0)
479 			left = i + 1;
480 		else if (cmp < 0)
481 			right = i - 1;
482 	}
483 
484 	return -1;
485 }
486 
487 const struct got_error *
488 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
489     struct got_packidx *packidx, const char *id_str_prefix)
490 {
491 	const struct got_error *err = NULL;
492 	u_int8_t id0;
493 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
494 	char hex[3];
495 	size_t prefix_len = strlen(id_str_prefix);
496 	struct got_packidx_object_id *oid;
497 	uint32_t i;
498 
499 	SIMPLEQ_INIT(matched_ids);
500 
501 	if (prefix_len < 2)
502 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
503 
504 	hex[0] = id_str_prefix[0];
505 	hex[1] = id_str_prefix[1];
506 	hex[2] = '\0';
507 	if (!got_parse_xdigit(&id0, hex))
508 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
509 
510 	i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
511 	oid = &packidx->hdr.sorted_ids[i];
512 	while (i < totobj && oid->sha1[0] == id0) {
513 		char id_str[SHA1_DIGEST_STRING_LENGTH];
514 		struct got_object_qid *qid;
515 		int cmp;
516 
517 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
518 		        return got_error(GOT_ERR_NO_SPACE);
519 
520 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
521 		if (cmp < 0) {
522 			oid = &packidx->hdr.sorted_ids[++i];
523 			continue;
524 		} else if (cmp > 0)
525 			break;
526 
527 		err = got_object_qid_alloc_partial(&qid);
528 		if (err)
529 			break;
530 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
531 		SIMPLEQ_INSERT_TAIL(matched_ids, qid, entry);
532 
533 		oid = &packidx->hdr.sorted_ids[++i];
534 	}
535 
536 	if (err)
537 		got_object_id_queue_free(matched_ids);
538 	return err;
539 }
540 
541 static const struct got_error *
542 pack_stop_privsep_child(struct got_pack *pack)
543 {
544 	const struct got_error *err = NULL;
545 
546 	if (pack->privsep_child == NULL)
547 		return NULL;
548 
549 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
550 	if (err)
551 		return err;
552 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
553 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
554 		err = got_error_from_errno("close");
555 	imsg_clear(pack->privsep_child->ibuf);
556 	free(pack->privsep_child->ibuf);
557 	free(pack->privsep_child);
558 	pack->privsep_child = NULL;
559 	return err;
560 }
561 
562 const struct got_error *
563 got_pack_close(struct got_pack *pack)
564 {
565 	const struct got_error *err = NULL;
566 
567 	err = pack_stop_privsep_child(pack);
568 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
569 		err = got_error_from_errno("munmap");
570 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
571 		err = got_error_from_errno("close");
572 	pack->fd = -1;
573 	free(pack->path_packfile);
574 	pack->path_packfile = NULL;
575 	pack->filesize = 0;
576 	if (pack->delta_cache) {
577 		got_delta_cache_free(pack->delta_cache);
578 		pack->delta_cache = NULL;
579 	}
580 
581 	return err;
582 }
583 
584 const struct got_error *
585 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
586     struct got_pack *pack, off_t offset)
587 {
588 	uint8_t t = 0;
589 	uint64_t s = 0;
590 	uint8_t sizeN;
591 	size_t mapoff = 0;
592 	int i = 0;
593 
594 	*len = 0;
595 
596 	if (offset >= pack->filesize)
597 		return got_error(GOT_ERR_PACK_OFFSET);
598 
599 	if (pack->map) {
600 		mapoff = (size_t)offset;
601 	} else {
602 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
603 			return got_error_from_errno("lseek");
604 	}
605 
606 	do {
607 		/* We do not support size values which don't fit in 64 bit. */
608 		if (i > 9)
609 			return got_error(GOT_ERR_NO_SPACE);
610 
611 		if (pack->map) {
612 			sizeN = *(pack->map + mapoff);
613 			mapoff += sizeof(sizeN);
614 		} else {
615 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
616 			if (n < 0)
617 				return got_error_from_errno("read");
618 			if (n != sizeof(sizeN))
619 				return got_error(GOT_ERR_BAD_PACKFILE);
620 		}
621 		*len += sizeof(sizeN);
622 
623 		if (i == 0) {
624 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
625 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
626 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
627 		} else {
628 			size_t shift = 4 + 7 * (i - 1);
629 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
630 		}
631 		i++;
632 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
633 
634 	*type = t;
635 	*size = s;
636 	return NULL;
637 }
638 
639 static const struct got_error *
640 open_plain_object(struct got_object **obj, struct got_object_id *id,
641     uint8_t type, off_t offset, size_t size, int idx)
642 {
643 	*obj = calloc(1, sizeof(**obj));
644 	if (*obj == NULL)
645 		return got_error_from_errno("calloc");
646 
647 	(*obj)->type = type;
648 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
649 	(*obj)->pack_idx = idx;
650 	(*obj)->hdrlen = 0;
651 	(*obj)->size = size;
652 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
653 	(*obj)->pack_offset = offset;
654 
655 	return NULL;
656 }
657 
658 static const struct got_error *
659 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
660     off_t delta_offset)
661 {
662 	int64_t o = 0;
663 	uint8_t offN;
664 	int i = 0;
665 
666 	*offset = 0;
667 	*len = 0;
668 
669 	do {
670 		/* We do not support offset values which don't fit in 64 bit. */
671 		if (i > 8)
672 			return got_error(GOT_ERR_NO_SPACE);
673 
674 		if (pack->map) {
675 			size_t mapoff;
676 			if (delta_offset >= pack->filesize)
677 				return got_error(GOT_ERR_PACK_OFFSET);
678 			mapoff = (size_t)delta_offset + *len;
679 			offN = *(pack->map + mapoff);
680 		} else {
681 			ssize_t n;
682 			n = read(pack->fd, &offN, sizeof(offN));
683 			if (n < 0)
684 				return got_error_from_errno("read");
685 			if (n != sizeof(offN))
686 				return got_error(GOT_ERR_BAD_PACKFILE);
687 		}
688 		*len += sizeof(offN);
689 
690 		if (i == 0)
691 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
692 		else {
693 			o++;
694 			o <<= 7;
695 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
696 		}
697 		i++;
698 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
699 
700 	*offset = o;
701 	return NULL;
702 }
703 
704 const struct got_error *
705 got_pack_parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
706     off_t offset, int tslen)
707 {
708 	const struct got_error *err;
709 	int64_t negoffset;
710 	size_t negofflen;
711 
712 	*len = 0;
713 
714 	err = parse_negative_offset(&negoffset, &negofflen, pack,
715 	    offset + tslen);
716 	if (err)
717 		return err;
718 
719 	/* Compute the base object's offset (must be in the same pack file). */
720 	*base_offset = (offset - negoffset);
721 	if (*base_offset <= 0)
722 		return got_error(GOT_ERR_BAD_PACKFILE);
723 
724 	*len = negofflen;
725 	return NULL;
726 }
727 
728 static const struct got_error *
729 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
730     size_t delta_data_offset, struct got_pack *pack)
731 {
732 	const struct got_error *err = NULL;
733 
734 	if (pack->map) {
735 		if (delta_data_offset >= pack->filesize)
736 			return got_error(GOT_ERR_PACK_OFFSET);
737 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
738 		    NULL, NULL, pack->map, delta_data_offset,
739 		    pack->filesize - delta_data_offset);
740 	} else {
741 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
742 			return got_error_from_errno("lseek");
743 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
744 		    NULL, 0, pack->fd);
745 	}
746 	return err;
747 }
748 
749 static const struct got_error *
750 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
751     int delta_type, size_t delta_size, size_t delta_data_offset)
752 {
753 	struct got_delta *delta;
754 
755 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
756 	    delta_data_offset);
757 	if (delta == NULL)
758 		return got_error_from_errno("got_delta_open");
759 	/* delta is freed in got_object_close() */
760 	deltas->nentries++;
761 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
762 	return NULL;
763 }
764 
765 static const struct got_error *
766 resolve_offset_delta(struct got_delta_chain *deltas,
767     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
768     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
769 
770 {
771 	const struct got_error *err;
772 	off_t base_offset;
773 	uint8_t base_type;
774 	uint64_t base_size;
775 	size_t base_tslen;
776 	off_t delta_data_offset;
777 	size_t consumed;
778 
779 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
780 	    delta_offset, tslen);
781 	if (err)
782 		return err;
783 
784 	delta_data_offset = delta_offset + tslen + consumed;
785 	if (delta_data_offset >= pack->filesize)
786 		return got_error(GOT_ERR_PACK_OFFSET);
787 
788 	if (pack->map == NULL) {
789 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
790 		if (delta_data_offset == -1)
791 			return got_error_from_errno("lseek");
792 	}
793 
794 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
795 	    delta_data_offset);
796 	if (err)
797 		return err;
798 
799 	/* An offset delta must be in the same packfile. */
800 	if (base_offset >= pack->filesize)
801 		return got_error(GOT_ERR_PACK_OFFSET);
802 
803 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
804 	    &base_tslen, pack, base_offset);
805 	if (err)
806 		return err;
807 
808 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
809 	    base_tslen, base_type, base_size, recursion - 1);
810 }
811 
812 static const struct got_error *
813 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
814     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
815     size_t delta_size, unsigned int recursion)
816 {
817 	const struct got_error *err;
818 	struct got_object_id id;
819 	int idx;
820 	off_t base_offset;
821 	uint8_t base_type;
822 	uint64_t base_size;
823 	size_t base_tslen;
824 	off_t delta_data_offset;
825 
826 	if (delta_offset + tslen >= pack->filesize)
827 		return got_error(GOT_ERR_PACK_OFFSET);
828 
829 	if (pack->map) {
830 		size_t mapoff = delta_offset + tslen;
831 		memcpy(&id, pack->map + mapoff, sizeof(id));
832 		mapoff += sizeof(id);
833 		delta_data_offset = (off_t)mapoff;
834 	} else {
835 		ssize_t n;
836 		n = read(pack->fd, &id, sizeof(id));
837 		if (n < 0)
838 			return got_error_from_errno("read");
839 		if (n != sizeof(id))
840 			return got_error(GOT_ERR_BAD_PACKFILE);
841 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
842 		if (delta_data_offset == -1)
843 			return got_error_from_errno("lseek");
844 	}
845 
846 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
847 	    delta_data_offset);
848 	if (err)
849 		return err;
850 
851 	/* Delta base must be in the same pack file. */
852 	idx = got_packidx_get_object_idx(packidx, &id);
853 	if (idx == -1)
854 		return got_error(GOT_ERR_NO_OBJ);
855 
856 	base_offset = got_packidx_get_object_offset(packidx, idx);
857 	if (base_offset == (uint64_t)-1)
858 		return got_error(GOT_ERR_BAD_PACKIDX);
859 
860 	if (base_offset >= pack->filesize)
861 		return got_error(GOT_ERR_PACK_OFFSET);
862 
863 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
864 	    &base_tslen, pack, base_offset);
865 	if (err)
866 		return err;
867 
868 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
869 	    base_tslen, base_type, base_size, recursion - 1);
870 }
871 
872 const struct got_error *
873 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
874     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
875     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
876 {
877 	const struct got_error *err = NULL;
878 
879 	if (--recursion == 0)
880 		return got_error(GOT_ERR_RECURSION);
881 
882 	switch (delta_type) {
883 	case GOT_OBJ_TYPE_COMMIT:
884 	case GOT_OBJ_TYPE_TREE:
885 	case GOT_OBJ_TYPE_BLOB:
886 	case GOT_OBJ_TYPE_TAG:
887 		/* Plain types are the final delta base. Recursion ends. */
888 		err = add_delta(deltas, delta_offset, tslen, delta_type,
889 		    delta_size, 0);
890 		break;
891 	case GOT_OBJ_TYPE_OFFSET_DELTA:
892 		err = resolve_offset_delta(deltas, packidx, pack,
893 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
894 		break;
895 	case GOT_OBJ_TYPE_REF_DELTA:
896 		err = resolve_ref_delta(deltas, packidx, pack,
897 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
898 		break;
899 	default:
900 		return got_error(GOT_ERR_OBJ_TYPE);
901 	}
902 
903 	return err;
904 }
905 
906 static const struct got_error *
907 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
908     struct got_pack *pack, struct got_object_id *id, off_t offset,
909     size_t tslen, int delta_type, size_t delta_size, int idx)
910 {
911 	const struct got_error *err = NULL;
912 	int resolved_type;
913 
914 	*obj = calloc(1, sizeof(**obj));
915 	if (*obj == NULL)
916 		return got_error_from_errno("calloc");
917 
918 	(*obj)->flags = 0;
919 	(*obj)->hdrlen = 0;
920 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
921 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
922 	(*obj)->pack_offset = offset + tslen;
923 
924 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
925 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
926 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
927 	(*obj)->pack_idx = idx;
928 
929 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
930 	    offset, tslen, delta_type, delta_size,
931 	    GOT_DELTA_CHAIN_RECURSION_MAX);
932 	if (err)
933 		goto done;
934 
935 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
936 	if (err)
937 		goto done;
938 	(*obj)->type = resolved_type;
939 done:
940 	if (err) {
941 		got_object_close(*obj);
942 		*obj = NULL;
943 	}
944 	return err;
945 }
946 
947 const struct got_error *
948 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
949     struct got_packidx *packidx, int idx, struct got_object_id *id)
950 {
951 	const struct got_error *err = NULL;
952 	off_t offset;
953 	uint8_t type;
954 	uint64_t size;
955 	size_t tslen;
956 
957 	*obj = NULL;
958 
959 	offset = got_packidx_get_object_offset(packidx, idx);
960 	if (offset == (uint64_t)-1)
961 		return got_error(GOT_ERR_BAD_PACKIDX);
962 
963 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
964 	    pack, offset);
965 	if (err)
966 		return err;
967 
968 	switch (type) {
969 	case GOT_OBJ_TYPE_COMMIT:
970 	case GOT_OBJ_TYPE_TREE:
971 	case GOT_OBJ_TYPE_BLOB:
972 	case GOT_OBJ_TYPE_TAG:
973 		err = open_plain_object(obj, id, type, offset + tslen,
974 		    size, idx);
975 		break;
976 	case GOT_OBJ_TYPE_OFFSET_DELTA:
977 	case GOT_OBJ_TYPE_REF_DELTA:
978 		err = open_delta_object(obj, packidx, pack, id, offset,
979 		    tslen, type, size, idx);
980 		break;
981 	default:
982 		err = got_error(GOT_ERR_OBJ_TYPE);
983 		break;
984 	}
985 
986 	return err;
987 }
988 
989 const struct got_error *
990 got_pack_get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
991     struct got_pack *pack)
992 {
993 	struct got_delta *delta;
994 	uint64_t base_size = 0, result_size = 0;
995 
996 	*max_size = 0;
997 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
998 		/* Plain object types are the delta base. */
999 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1000 		    delta->type != GOT_OBJ_TYPE_TREE &&
1001 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1002 		    delta->type != GOT_OBJ_TYPE_TAG) {
1003 			const struct got_error *err;
1004 			uint8_t *delta_buf;
1005 			size_t delta_len;
1006 			int cached = 1;
1007 
1008 			got_delta_cache_get(&delta_buf, &delta_len,
1009 			    pack->delta_cache, delta->data_offset);
1010 			if (delta_buf == NULL) {
1011 				cached = 0;
1012 				err = read_delta_data(&delta_buf, &delta_len,
1013 				    delta->data_offset, pack);
1014 				if (err)
1015 					return err;
1016 				err = got_delta_cache_add(pack->delta_cache,
1017 				    delta->data_offset, delta_buf, delta_len);
1018 				if (err == NULL)
1019 					cached = 1;
1020 				else if (err->code != GOT_ERR_NO_SPACE) {
1021 					free(delta_buf);
1022 					return err;
1023 				}
1024 			}
1025 			err = got_delta_get_sizes(&base_size, &result_size,
1026 			    delta_buf, delta_len);
1027 			if (!cached)
1028 				free(delta_buf);
1029 			if (err)
1030 				return err;
1031 		} else
1032 			base_size = delta->size;
1033 		if (base_size > *max_size)
1034 			*max_size = base_size;
1035 		if (result_size > *max_size)
1036 			*max_size = result_size;
1037 	}
1038 
1039 	return NULL;
1040 }
1041 
1042 const struct got_error *
1043 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1044     struct got_pack *pack)
1045 {
1046 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1047 		return got_error(GOT_ERR_OBJ_TYPE);
1048 
1049 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1050 }
1051 
1052 const struct got_error *
1053 got_pack_dump_delta_chain_to_file(size_t *result_size,
1054     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1055     FILE *base_file, FILE *accum_file)
1056 {
1057 	const struct got_error *err = NULL;
1058 	struct got_delta *delta;
1059 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1060 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1061 	uint64_t max_size;
1062 	int n = 0;
1063 
1064 	*result_size = 0;
1065 
1066 	if (SIMPLEQ_EMPTY(&deltas->entries))
1067 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1068 
1069 	/* We process small enough files entirely in memory for speed. */
1070 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1071 	if (err)
1072 		return err;
1073 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1074 		accum_buf = malloc(max_size);
1075 		if (accum_buf == NULL)
1076 			return got_error_from_errno("malloc");
1077 		base_file = NULL;
1078 		accum_file = NULL;
1079 	}
1080 
1081 	/* Deltas are ordered in ascending order. */
1082 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1083 		int cached = 1;
1084 		if (n == 0) {
1085 			size_t mapoff;
1086 			off_t delta_data_offset;
1087 
1088 			/* Plain object types are the delta base. */
1089 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1090 			    delta->type != GOT_OBJ_TYPE_TREE &&
1091 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1092 			    delta->type != GOT_OBJ_TYPE_TAG) {
1093 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1094 				goto done;
1095 			}
1096 
1097 			delta_data_offset = delta->offset + delta->tslen;
1098 			if (delta_data_offset >= pack->filesize) {
1099 				err = got_error(GOT_ERR_PACK_OFFSET);
1100 				goto done;
1101 			}
1102 			if (pack->map == NULL) {
1103 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1104 				    == -1) {
1105 					err = got_error_from_errno("lseek");
1106 					goto done;
1107 				}
1108 			}
1109 			if (base_file) {
1110 				if (pack->map) {
1111 					mapoff = (size_t)delta_data_offset;
1112 					err = got_inflate_to_file_mmap(
1113 					    &base_bufsz, NULL, NULL, pack->map,
1114 					    mapoff, pack->filesize - mapoff,
1115 					    base_file);
1116 				} else
1117 					err = got_inflate_to_file_fd(
1118 					    &base_bufsz, NULL, NULL, pack->fd,
1119 					    base_file);
1120 			} else {
1121 				if (pack->map) {
1122 					mapoff = (size_t)delta_data_offset;
1123 					err = got_inflate_to_mem_mmap(&base_buf,
1124 					    &base_bufsz, NULL, NULL,
1125 					    pack->map, mapoff,
1126 					    pack->filesize - mapoff);
1127 				} else
1128 					err = got_inflate_to_mem_fd(&base_buf,
1129 					    &base_bufsz, NULL, NULL, max_size,
1130 					    pack->fd);
1131 			}
1132 			if (err)
1133 				goto done;
1134 			n++;
1135 			if (base_file)
1136 				rewind(base_file);
1137 			continue;
1138 		}
1139 
1140 		got_delta_cache_get(&delta_buf, &delta_len,
1141 		    pack->delta_cache, delta->data_offset);
1142 		if (delta_buf == NULL) {
1143 			cached = 0;
1144 			err = read_delta_data(&delta_buf, &delta_len,
1145 			    delta->data_offset, pack);
1146 			if (err)
1147 				goto done;
1148 			err = got_delta_cache_add(pack->delta_cache,
1149 			    delta->data_offset, delta_buf, delta_len);
1150 			if (err == NULL)
1151 				cached = 1;
1152 			else if (err->code != GOT_ERR_NO_SPACE) {
1153 				free(delta_buf);
1154 				goto done;
1155 			}
1156 		}
1157 		if (base_buf) {
1158 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1159 			    delta_buf, delta_len, accum_buf,
1160 			    &accum_size, max_size);
1161 			n++;
1162 		} else {
1163 			err = got_delta_apply(base_file, delta_buf,
1164 			    delta_len,
1165 			    /* Final delta application writes to output file. */
1166 			    ++n < deltas->nentries ? accum_file : outfile,
1167 			    &accum_size);
1168 		}
1169 		if (!cached)
1170 			free(delta_buf);
1171 		if (err)
1172 			goto done;
1173 
1174 		if (n < deltas->nentries) {
1175 			/* Accumulated delta becomes the new base. */
1176 			if (base_buf) {
1177 				uint8_t *tmp = accum_buf;
1178 				/*
1179 				 * Base buffer switches roles with accumulation
1180 				 * buffer. Ensure it can hold the largest
1181 				 * result in the delta chain. The initial
1182 				 * allocation might have been smaller.
1183 				 */
1184 				if (base_bufsz < max_size) {
1185 					uint8_t *p;
1186 					p = reallocarray(base_buf, 1, max_size);
1187 					if (p == NULL) {
1188 						err = got_error_from_errno(
1189 						    "reallocarray");
1190 						goto done;
1191 					}
1192 					base_buf = p;
1193 					base_bufsz = max_size;
1194 				}
1195 				accum_buf = base_buf;
1196 				base_buf = tmp;
1197 			} else {
1198 				FILE *tmp = accum_file;
1199 				accum_file = base_file;
1200 				base_file = tmp;
1201 				rewind(base_file);
1202 				rewind(accum_file);
1203 			}
1204 		}
1205 	}
1206 
1207 done:
1208 	free(base_buf);
1209 	if (accum_buf) {
1210 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1211 		free(accum_buf);
1212 		if (len != accum_size)
1213 			err = got_ferror(outfile, GOT_ERR_IO);
1214 	}
1215 	rewind(outfile);
1216 	if (err == NULL)
1217 		*result_size = accum_size;
1218 	return err;
1219 }
1220 
1221 const struct got_error *
1222 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1223     struct got_delta_chain *deltas, struct got_pack *pack)
1224 {
1225 	const struct got_error *err = NULL;
1226 	struct got_delta *delta;
1227 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1228 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1229 	uint64_t max_size;
1230 	int n = 0;
1231 
1232 	*outbuf = NULL;
1233 	*outlen = 0;
1234 
1235 	if (SIMPLEQ_EMPTY(&deltas->entries))
1236 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1237 
1238 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1239 	if (err)
1240 		return err;
1241 	accum_buf = malloc(max_size);
1242 	if (accum_buf == NULL)
1243 		return got_error_from_errno("malloc");
1244 
1245 	/* Deltas are ordered in ascending order. */
1246 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1247 		int cached = 1;
1248 		if (n == 0) {
1249 			size_t delta_data_offset;
1250 
1251 			/* Plain object types are the delta base. */
1252 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1253 			    delta->type != GOT_OBJ_TYPE_TREE &&
1254 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1255 			    delta->type != GOT_OBJ_TYPE_TAG) {
1256 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1257 				goto done;
1258 			}
1259 
1260 			delta_data_offset = delta->offset + delta->tslen;
1261 			if (delta_data_offset >= pack->filesize) {
1262 				err = got_error(GOT_ERR_PACK_OFFSET);
1263 				goto done;
1264 			}
1265 			if (pack->map) {
1266 				size_t mapoff = (size_t)delta_data_offset;
1267 				err = got_inflate_to_mem_mmap(&base_buf,
1268 				    &base_bufsz, NULL, NULL, pack->map,
1269 				    mapoff, pack->filesize - mapoff);
1270 			} else {
1271 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1272 				    == -1) {
1273 					err = got_error_from_errno("lseek");
1274 					goto done;
1275 				}
1276 				err = got_inflate_to_mem_fd(&base_buf,
1277 				    &base_bufsz, NULL, NULL, max_size,
1278 				    pack->fd);
1279 			}
1280 			if (err)
1281 				goto done;
1282 			n++;
1283 			continue;
1284 		}
1285 
1286 		got_delta_cache_get(&delta_buf, &delta_len,
1287 		    pack->delta_cache, delta->data_offset);
1288 		if (delta_buf == NULL) {
1289 			cached = 0;
1290 			err = read_delta_data(&delta_buf, &delta_len,
1291 			    delta->data_offset, pack);
1292 			if (err)
1293 				goto done;
1294 			err = got_delta_cache_add(pack->delta_cache,
1295 			    delta->data_offset, delta_buf, delta_len);
1296 			if (err == NULL)
1297 				cached = 1;
1298 			else if (err->code != GOT_ERR_NO_SPACE) {
1299 				free(delta_buf);
1300 				goto done;
1301 			}
1302 		}
1303 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1304 		    delta_buf, delta_len, accum_buf,
1305 		    &accum_size, max_size);
1306 		if (!cached)
1307 			free(delta_buf);
1308 		n++;
1309 		if (err)
1310 			goto done;
1311 
1312 		if (n < deltas->nentries) {
1313 			/* Accumulated delta becomes the new base. */
1314 			uint8_t *tmp = accum_buf;
1315 			/*
1316 			 * Base buffer switches roles with accumulation buffer.
1317 			 * Ensure it can hold the largest result in the delta
1318 			 * chain. Initial allocation might have been smaller.
1319 			 */
1320 			if (base_bufsz < max_size) {
1321 				uint8_t *p;
1322 				p = reallocarray(base_buf, 1, max_size);
1323 				if (p == NULL) {
1324 					err = got_error_from_errno(
1325 					    "reallocarray");
1326 					goto done;
1327 				}
1328 				base_buf = p;
1329 				base_bufsz = max_size;
1330 			}
1331 			accum_buf = base_buf;
1332 			base_buf = tmp;
1333 		}
1334 	}
1335 
1336 done:
1337 	free(base_buf);
1338 	if (err) {
1339 		free(accum_buf);
1340 		*outbuf = NULL;
1341 		*outlen = 0;
1342 	} else {
1343 		*outbuf = accum_buf;
1344 		*outlen = accum_size;
1345 	}
1346 	return err;
1347 }
1348 
1349 const struct got_error *
1350 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1351     FILE *outfile, FILE *base_file, FILE *accum_file)
1352 {
1353 	const struct got_error *err = NULL;
1354 
1355 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1356 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1357 
1358 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1359 		if (obj->pack_offset >= pack->filesize)
1360 			return got_error(GOT_ERR_PACK_OFFSET);
1361 
1362 		if (pack->map) {
1363 			size_t mapoff = (size_t)obj->pack_offset;
1364 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1365 			    pack->map, mapoff, pack->filesize - mapoff,
1366 			    outfile);
1367 		} else {
1368 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1369 				return got_error_from_errno("lseek");
1370 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1371 			    pack->fd, outfile);
1372 		}
1373 	} else
1374 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1375 		    &obj->deltas, pack, outfile, base_file, accum_file);
1376 
1377 	return err;
1378 }
1379 
1380 const struct got_error *
1381 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1382     struct got_object *obj, struct got_pack *pack)
1383 {
1384 	const struct got_error *err = NULL;
1385 
1386 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1387 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1388 
1389 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1390 		if (obj->pack_offset >= pack->filesize)
1391 			return got_error(GOT_ERR_PACK_OFFSET);
1392 		if (pack->map) {
1393 			size_t mapoff = (size_t)obj->pack_offset;
1394 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1395 			    pack->map, mapoff, pack->filesize - mapoff);
1396 		} else {
1397 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1398 				return got_error_from_errno("lseek");
1399 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1400 			    obj->size, pack->fd);
1401 		}
1402 	} else
1403 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1404 		    pack);
1405 
1406 	return err;
1407 }