1 /*
2  * Copyright (c) 2018, 2019 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #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 <zlib.h>
33 #include <imsg.h>
34 
35 #include "got_error.h"
36 #include "got_object.h"
37 #include "got_opentemp.h"
38 #include "got_path.h"
39 
40 #include "got_lib_sha1.h"
41 #include "got_lib_delta.h"
42 #include "got_lib_inflate.h"
43 #include "got_lib_object.h"
44 #include "got_lib_privsep.h"
45 #include "got_lib_pack.h"
46 
47 #ifndef nitems
48 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
49 #endif
50 
51 #ifndef MIN
52 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
53 #endif
54 
55 static const struct got_error *
56 verify_fanout_table(uint32_t *fanout_table)
57 {
58 	int i;
59 
60 	for (i = 0; i < 0xff - 1; i++) {
61 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
62 			return got_error(GOT_ERR_BAD_PACKIDX);
63 	}
64 
65 	return NULL;
66 }
67 
68 const struct got_error *
69 got_pack_get_packfile_size(size_t *size, const char *path)
70 {
71 	struct stat sb;
72 	char *dot;
73 
74 	*size = 0;
75 
76 	dot = strrchr(path, '.');
77 	if (dot == NULL)
78 		return got_error(GOT_ERR_BAD_PATH);
79 
80 	/* Path must point to a pack index or to a pack file. */
81 	if (strcmp(dot, GOT_PACKIDX_SUFFIX) == 0) {
82 		const struct got_error *err = NULL;
83 		char *path_pack;
84 		char base_path[PATH_MAX];
85 
86 		/* Convert pack index path to pack file path. */
87 		if (strlcpy(base_path, path, PATH_MAX) > PATH_MAX)
88 			return got_error(GOT_ERR_NO_SPACE);
89 		dot = strrchr(base_path, '.');
90 		if (dot == NULL)
91 			return got_error(GOT_ERR_BAD_PATH);
92 		*dot = '\0';
93 		if (asprintf(&path_pack, "%s.pack", base_path) == -1)
94 			return got_error_prefix_errno("asprintf");
95 
96 		if (stat(path_pack, &sb) != 0)
97 			err = got_error_prefix_errno("asprintf");
98 		free(path_pack);
99 		if (err)
100 			return err;
101 	} else if (strcmp(dot, GOT_PACKFILE_SUFFIX) == 0) {
102 		if (stat(path, &sb) != 0)
103 			return got_error_prefix_errno2("stat", path);
104 	} else
105 		return got_error(GOT_ERR_BAD_PATH);
106 
107 	*size = sb.st_size;
108 	return 0;
109 }
110 
111 const struct got_error *
112 got_packidx_init_hdr(struct got_packidx *p, int verify)
113 {
114 	const struct got_error *err = NULL;
115 	struct got_packidx_v2_hdr *h;
116 	SHA1_CTX ctx;
117 	uint8_t sha1[SHA1_DIGEST_LENGTH];
118 	size_t nobj, len_fanout, len_ids, offset, remain;
119 	ssize_t n;
120 
121 	SHA1Init(&ctx);
122 
123 	h = &p->hdr;
124 	offset = 0;
125 	remain = p->len;
126 
127 	if (remain < sizeof(*h->magic)) {
128 		err = got_error(GOT_ERR_BAD_PACKIDX);
129 		goto done;
130 	}
131 	if (p->map)
132 		h->magic = (uint32_t *)(p->map + offset);
133 	else {
134 		h->magic = malloc(sizeof(*h->magic));
135 		if (h->magic == NULL) {
136 			err = got_error_prefix_errno("malloc");
137 			goto done;
138 		}
139 		n = read(p->fd, h->magic, sizeof(*h->magic));
140 		if (n < 0)
141 			err = got_error_prefix_errno("read");
142 		else if (n != sizeof(*h->magic)) {
143 			err = got_error(GOT_ERR_BAD_PACKIDX);
144 			goto done;
145 		}
146 	}
147 	if (betoh32(*h->magic) != GOT_PACKIDX_V2_MAGIC) {
148 		err = got_error(GOT_ERR_BAD_PACKIDX);
149 		goto done;
150 	}
151 	offset += sizeof(*h->magic);
152 	remain -= sizeof(*h->magic);
153 
154 	if (verify)
155 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
156 
157 	if (remain < sizeof(*h->version)) {
158 		err = got_error(GOT_ERR_BAD_PACKIDX);
159 		goto done;
160 	}
161 	if (p->map)
162 		h->version = (uint32_t *)(p->map + offset);
163 	else {
164 		h->version = malloc(sizeof(*h->version));
165 		if (h->version == NULL) {
166 			err = got_error_prefix_errno("malloc");
167 			goto done;
168 		}
169 		n = read(p->fd, h->version, sizeof(*h->version));
170 		if (n < 0)
171 			err = got_error_prefix_errno("read");
172 		else if (n != sizeof(*h->version)) {
173 			err = got_error(GOT_ERR_BAD_PACKIDX);
174 			goto done;
175 		}
176 	}
177 	if (betoh32(*h->version) != GOT_PACKIDX_VERSION) {
178 		err = got_error(GOT_ERR_BAD_PACKIDX);
179 		goto done;
180 	}
181 	offset += sizeof(*h->version);
182 	remain -= sizeof(*h->version);
183 
184 	if (verify)
185 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
186 
187 	len_fanout =
188 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
189 	if (remain < len_fanout) {
190 		err = got_error(GOT_ERR_BAD_PACKIDX);
191 		goto done;
192 	}
193 	if (p->map)
194 		h->fanout_table = (uint32_t *)(p->map + offset);
195 	else {
196 		h->fanout_table = malloc(len_fanout);
197 		if (h->fanout_table == NULL) {
198 			err = got_error_prefix_errno("malloc");
199 			goto done;
200 		}
201 		n = read(p->fd, h->fanout_table, len_fanout);
202 		if (n < 0)
203 			err = got_error_prefix_errno("read");
204 		else if (n != len_fanout) {
205 			err = got_error(GOT_ERR_BAD_PACKIDX);
206 			goto done;
207 		}
208 	}
209 	err = verify_fanout_table(h->fanout_table);
210 	if (err)
211 		goto done;
212 	if (verify)
213 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
214 	offset += len_fanout;
215 	remain -= len_fanout;
216 
217 	nobj = betoh32(h->fanout_table[0xff]);
218 	len_ids = nobj * sizeof(*h->sorted_ids);
219 	if (len_ids <= nobj || len_ids > remain) {
220 		err = got_error(GOT_ERR_BAD_PACKIDX);
221 		goto done;
222 	}
223 	if (p->map)
224 		h->sorted_ids =
225 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
226 	else {
227 		h->sorted_ids = malloc(len_ids);
228 		if (h->sorted_ids == NULL) {
229 			err = got_error(GOT_ERR_BAD_PACKIDX);
230 			goto done;
231 		}
232 		n = read(p->fd, h->sorted_ids, len_ids);
233 		if (n < 0)
234 			err = got_error_prefix_errno("read");
235 		else if (n != len_ids) {
236 			err = got_error(GOT_ERR_BAD_PACKIDX);
237 			goto done;
238 		}
239 	}
240 	if (verify)
241 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
242 	offset += len_ids;
243 	remain -= len_ids;
244 
245 	if (remain < nobj * sizeof(*h->crc32)) {
246 		err = got_error(GOT_ERR_BAD_PACKIDX);
247 		goto done;
248 	}
249 	if (p->map)
250 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
251 	else {
252 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
253 		if (h->crc32 == NULL) {
254 			err = got_error_prefix_errno("malloc");
255 			goto done;
256 		}
257 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
258 		if (n < 0)
259 			err = got_error_prefix_errno("read");
260 		else if (n != nobj * sizeof(*h->crc32)) {
261 			err = got_error(GOT_ERR_BAD_PACKIDX);
262 			goto done;
263 		}
264 	}
265 	if (verify)
266 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
267 	remain -= nobj * sizeof(*h->crc32);
268 	offset += nobj * sizeof(*h->crc32);
269 
270 	if (remain < nobj * sizeof(*h->offsets)) {
271 		err = got_error(GOT_ERR_BAD_PACKIDX);
272 		goto done;
273 	}
274 	if (p->map)
275 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
276 	else {
277 		h->offsets = malloc(nobj * sizeof(*h->offsets));
278 		if (h->offsets == NULL) {
279 			err = got_error_prefix_errno("malloc");
280 			goto done;
281 		}
282 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
283 		if (n < 0)
284 			err = got_error_prefix_errno("read");
285 		else if (n != nobj * sizeof(*h->offsets)) {
286 			err = got_error(GOT_ERR_BAD_PACKIDX);
287 			goto done;
288 		}
289 	}
290 	if (verify)
291 		SHA1Update(&ctx, (uint8_t *)h->offsets,
292 		    nobj * sizeof(*h->offsets));
293 	remain -= nobj * sizeof(*h->offsets);
294 	offset += nobj * sizeof(*h->offsets);
295 
296 	/* Large file offsets are contained only in files > 2GB. */
297 	if (p->len <= 0x80000000)
298 		goto checksum;
299 
300 	if (remain < nobj * sizeof(*h->large_offsets)) {
301 		err = got_error(GOT_ERR_BAD_PACKIDX);
302 		goto done;
303 	}
304 	if (p->map)
305 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
306 	else {
307 		h->offsets = malloc(nobj * sizeof(*h->large_offsets));
308 		if (h->offsets == NULL) {
309 			err = got_error_prefix_errno("malloc");
310 			goto done;
311 		}
312 		n = read(p->fd, h->large_offsets,
313 		    nobj * sizeof(*h->large_offsets));
314 		if (n < 0)
315 			err = got_error_prefix_errno("read");
316 		else if (n != nobj * sizeof(*h->large_offsets)) {
317 			err = got_error(GOT_ERR_BAD_PACKIDX);
318 			goto done;
319 		}
320 	}
321 	if (verify)
322 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
323 		    nobj * sizeof(*h->large_offsets));
324 	remain -= nobj * sizeof(*h->large_offsets);
325 	offset += nobj * sizeof(*h->large_offsets);
326 
327 checksum:
328 	if (remain < sizeof(*h->trailer)) {
329 		err = got_error(GOT_ERR_BAD_PACKIDX);
330 		goto done;
331 	}
332 	if (p->map)
333 		h->trailer =
334 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
335 	else {
336 		h->trailer = malloc(sizeof(*h->trailer));
337 		if (h->trailer == NULL) {
338 			err = got_error_prefix_errno("malloc");
339 			goto done;
340 		}
341 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
342 		if (n < 0)
343 			err = got_error_prefix_errno("read");
344 		else if (n != sizeof(*h->trailer)) {
345 			err = got_error(GOT_ERR_BAD_PACKIDX);
346 			goto done;
347 		}
348 	}
349 	if (verify) {
350 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
351 		SHA1Final(sha1, &ctx);
352 		if (memcmp(h->trailer->packidx_sha1, sha1,
353 		    SHA1_DIGEST_LENGTH) != 0)
354 			err = got_error(GOT_ERR_PACKIDX_CSUM);
355 	}
356 done:
357 	return err;
358 }
359 
360 const struct got_error *
361 got_packidx_open(struct got_packidx **packidx, const char *path, int verify)
362 {
363 	const struct got_error *err = NULL;
364 	struct got_packidx *p;
365 
366 	*packidx = NULL;
367 
368 	p = calloc(1, sizeof(*p));
369 	if (p == NULL)
370 		return got_error_prefix_errno("calloc");
371 
372 	p->fd = open(path, O_RDONLY | O_NOFOLLOW);
373 	if (p->fd == -1)
374 		return got_error_prefix_errno2("open", path);
375 
376 	err = got_pack_get_packfile_size(&p->len, path);
377 	if (err) {
378 		close(p->fd);
379 		free(p);
380 		return err;
381 	}
382 	if (p->len < sizeof(p->hdr)) {
383 		err = got_error(GOT_ERR_BAD_PACKIDX);
384 		close(p->fd);
385 		free(p);
386 		return err;
387 	}
388 
389 	p->path_packidx = strdup(path);
390 	if (p->path_packidx == NULL) {
391 		err = got_error_prefix_errno("strdup");
392 		goto done;
393 	}
394 
395 #ifndef GOT_PACK_NO_MMAP
396 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
397 	if (p->map == MAP_FAILED) {
398 		if (errno != ENOMEM) {
399 			err = got_error_prefix_errno("mmap");
400 			goto done;
401 		}
402 		p->map = NULL; /* fall back to read(2) */
403 	}
404 #endif
405 
406 	err = got_packidx_init_hdr(p, verify);
407 done:
408 	if (err)
409 		got_packidx_close(p);
410 	else
411 		*packidx = p;
412 
413 	return err;
414 }
415 
416 const struct got_error *
417 got_packidx_close(struct got_packidx *packidx)
418 {
419 	const struct got_error *err = NULL;
420 
421 	free(packidx->path_packidx);
422 	if (packidx->map) {
423 		if (munmap(packidx->map, packidx->len) == -1)
424 			err = got_error_prefix_errno("munmap");
425 	} else {
426 		free(packidx->hdr.magic);
427 		free(packidx->hdr.version);
428 		free(packidx->hdr.fanout_table);
429 		free(packidx->hdr.sorted_ids);
430 		free(packidx->hdr.crc32);
431 		free(packidx->hdr.offsets);
432 		free(packidx->hdr.large_offsets);
433 		free(packidx->hdr.trailer);
434 	}
435 	if (close(packidx->fd) != 0 && err == NULL)
436 		err = got_error_prefix_errno("close");
437 	free(packidx);
438 
439 	return err;
440 }
441 
442 static off_t
443 get_object_offset(struct got_packidx *packidx, int idx)
444 {
445 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
446 	uint32_t offset = betoh32(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 > totobj ||
451 		    packidx->hdr.large_offsets == NULL)
452 			return -1;
453 		loffset = betoh64(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 = betoh32(packidx->hdr.fanout_table[0xff]);
464 	int left = 0, right = totobj - 1;
465 
466 	if (id0 > 0)
467 		left = betoh32(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_pack_stop_privsep_child(struct got_pack *pack)
489 {
490 	const struct got_error *err = NULL;
491 
492 	if (pack->privsep_child == NULL)
493 		return NULL;
494 
495 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
496 	if (err)
497 		return err;
498 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
499 	if (close(pack->privsep_child->imsg_fd) != 0 && err == NULL)
500 		err = got_error_prefix_errno("close");
501 	free(pack->privsep_child);
502 	pack->privsep_child = NULL;
503 	return err;
504 }
505 
506 const struct got_error *
507 got_pack_close(struct got_pack *pack)
508 {
509 	const struct got_error *err = NULL;
510 
511 	err = got_pack_stop_privsep_child(pack);
512 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
513 		err = got_error_prefix_errno("munmap");
514 	if (pack->fd != -1 && close(pack->fd) != 0 && err == NULL)
515 		err = got_error_prefix_errno("close");
516 	pack->fd = -1;
517 	free(pack->path_packfile);
518 	pack->path_packfile = NULL;
519 	pack->filesize = 0;
520 
521 	return err;
522 }
523 
524 static const struct got_error *
525 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
526     struct got_pack *pack, off_t offset)
527 {
528 	uint8_t t = 0;
529 	uint64_t s = 0;
530 	uint8_t sizeN;
531 	size_t mapoff = 0;
532 	int i = 0;
533 
534 	*len = 0;
535 
536 	if (offset >= pack->filesize)
537 		return got_error(GOT_ERR_PACK_OFFSET);
538 
539 	if (pack->map) {
540 		mapoff = (size_t)offset;
541 	} else {
542 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
543 			return got_error_prefix_errno("lseek");
544 	}
545 
546 	do {
547 		/* We do not support size values which don't fit in 64 bit. */
548 		if (i > 9)
549 			return got_error(GOT_ERR_NO_SPACE);
550 
551 		if (pack->map) {
552 			sizeN = *(pack->map + mapoff);
553 			mapoff += sizeof(sizeN);
554 		} else {
555 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
556 			if (n < 0)
557 				return got_error_prefix_errno("read");
558 			if (n != sizeof(sizeN))
559 				return got_error(GOT_ERR_BAD_PACKFILE);
560 		}
561 		*len += sizeof(sizeN);
562 
563 		if (i == 0) {
564 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
565 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
566 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
567 		} else {
568 			size_t shift = 4 + 7 * (i - 1);
569 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
570 		}
571 		i++;
572 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
573 
574 	*type = t;
575 	*size = s;
576 	return NULL;
577 }
578 
579 static const struct got_error *
580 open_plain_object(struct got_object **obj, const char *path_packfile,
581     struct got_object_id *id, uint8_t type, off_t offset, size_t size, int idx)
582 {
583 	*obj = calloc(1, sizeof(**obj));
584 	if (*obj == NULL)
585 		return got_error_prefix_errno("calloc");
586 
587 	(*obj)->path_packfile = strdup(path_packfile);
588 	if ((*obj)->path_packfile == NULL) {
589 		const struct got_error *err = got_error_prefix_errno("strdup");
590 		free(*obj);
591 		*obj = NULL;
592 		return err;
593 	}
594 
595 	(*obj)->type = type;
596 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
597 	(*obj)->pack_idx = idx;
598 	(*obj)->hdrlen = 0;
599 	(*obj)->size = size;
600 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
601 	(*obj)->pack_offset = offset;
602 
603 	return NULL;
604 }
605 
606 static const struct got_error *
607 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
608     off_t delta_offset)
609 {
610 	int64_t o = 0;
611 	uint8_t offN;
612 	int i = 0;
613 
614 	*len = 0;
615 
616 	do {
617 		/* We do not support offset values which don't fit in 64 bit. */
618 		if (i > 8)
619 			return got_error(GOT_ERR_NO_SPACE);
620 
621 		if (pack->map) {
622 			size_t mapoff;
623 			if (delta_offset >= pack->filesize)
624 				return got_error(GOT_ERR_PACK_OFFSET);
625 			mapoff = (size_t)delta_offset + *len;
626 			offN = *(pack->map + mapoff);
627 		} else {
628 			ssize_t n;
629 			n = read(pack->fd, &offN, sizeof(offN));
630 			if (n < 0)
631 				return got_error_prefix_errno("read");
632 			if (n != sizeof(offN))
633 				return got_error(GOT_ERR_BAD_PACKFILE);
634 		}
635 		*len += sizeof(offN);
636 
637 		if (i == 0)
638 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
639 		else {
640 			o++;
641 			o <<= 7;
642 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
643 		}
644 		i++;
645 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
646 
647 	*offset = o;
648 	return NULL;
649 }
650 
651 static const struct got_error *
652 parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
653     off_t offset, int tslen)
654 {
655 	const struct got_error *err;
656 	int64_t negoffset;
657 	size_t negofflen;
658 
659 	*len = 0;
660 
661 	err = parse_negative_offset(&negoffset, &negofflen, pack,
662 	    offset + tslen);
663 	if (err)
664 		return err;
665 
666 	/* Compute the base object's offset (must be in the same pack file). */
667 	*base_offset = (offset - negoffset);
668 	if (*base_offset <= 0)
669 		return got_error(GOT_ERR_BAD_PACKFILE);
670 
671 	*len = negofflen;
672 	return NULL;
673 }
674 
675 static const struct got_error *
676 resolve_delta_chain(struct got_delta_chain *, struct got_packidx *,
677     struct got_pack *, off_t, size_t, int, size_t, unsigned int);
678 
679 static const struct got_error *
680 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
681     int delta_type, size_t delta_size, size_t delta_data_offset,
682     uint8_t *delta_buf, size_t delta_len)
683 {
684 	struct got_delta *delta;
685 
686 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
687 	    delta_data_offset, delta_buf,
688 	    delta_len);
689 	if (delta == NULL)
690 		return got_error_prefix_errno("got_delta_open");
691 	/* delta is freed in got_object_close() */
692 	deltas->nentries++;
693 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
694 	return NULL;
695 }
696 
697 static const struct got_error *
698 resolve_offset_delta(struct got_delta_chain *deltas,
699     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
700     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
701 
702 {
703 	const struct got_error *err;
704 	off_t base_offset;
705 	uint8_t base_type;
706 	uint64_t base_size;
707 	size_t base_tslen;
708 	off_t delta_data_offset;
709 	uint8_t *delta_buf;
710 	size_t delta_len, consumed;
711 
712 	err = parse_offset_delta(&base_offset, &consumed, pack,
713 	    delta_offset, tslen);
714 	if (err)
715 		return err;
716 
717 	delta_data_offset = delta_offset + tslen + consumed;
718 	if (delta_data_offset >= pack->filesize)
719 		return got_error(GOT_ERR_PACK_OFFSET);
720 
721 	if (pack->map == NULL) {
722 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
723 		if (delta_data_offset == -1)
724 			return got_error_prefix_errno("lseek");
725 	}
726 
727 	if (pack->map) {
728 		size_t mapoff = (size_t)delta_data_offset;
729 		err = got_inflate_to_mem_mmap(&delta_buf, &delta_len, pack->map,
730 		    mapoff, pack->filesize - mapoff);
731 		if (err)
732 			return err;
733 	} else {
734 
735 		err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
736 		if (err)
737 			return err;
738 	}
739 
740 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
741 	    delta_data_offset, delta_buf, delta_len);
742 	if (err)
743 		goto done;
744 
745 	/* An offset delta must be in the same packfile. */
746 	if (base_offset >= pack->filesize) {
747 		err = got_error(GOT_ERR_PACK_OFFSET);
748 		goto done;
749 	}
750 
751 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
752 	    pack, base_offset);
753 	if (err)
754 		goto done;
755 
756 	err = resolve_delta_chain(deltas, packidx, pack, base_offset,
757 	    base_tslen, base_type, base_size, recursion - 1);
758 done:
759 	if (err)
760 		free(delta_buf);
761 	return err;
762 }
763 
764 static const struct got_error *
765 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
766     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
767     size_t delta_size, unsigned int recursion)
768 {
769 	const struct got_error *err;
770 	struct got_object_id id;
771 	int idx;
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 	uint8_t *delta_buf = NULL;
778 	size_t delta_len;
779 
780 	if (delta_offset >= pack->filesize)
781 		return got_error(GOT_ERR_PACK_OFFSET);
782 	delta_data_offset = delta_offset + tslen;
783 	if (delta_data_offset >= pack->filesize)
784 		return got_error(GOT_ERR_PACK_OFFSET);
785 
786 	if (pack->map == NULL) {
787 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
788 		if (delta_data_offset == -1)
789 			return got_error_prefix_errno("lseek");
790 	}
791 
792 	if (pack->map) {
793 		size_t mapoff = (size_t)delta_data_offset;
794 		memcpy(&id, pack->map + mapoff, sizeof(id));
795 		mapoff += sizeof(id);
796 		err = got_inflate_to_mem_mmap(&delta_buf, &delta_len, pack->map,
797 		    mapoff, pack->filesize - mapoff);
798 		if (err)
799 			goto done;
800 	} else {
801 		ssize_t n = read(pack->fd, &id, sizeof(id));
802 		if (n < 0)
803 			return got_error_prefix_errno("read");
804 		if (n != sizeof(id))
805 			return got_error(GOT_ERR_BAD_PACKFILE);
806 		err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
807 		if (err)
808 			goto done;
809 	}
810 
811 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
812 	    delta_data_offset, delta_buf, delta_len);
813 	if (err)
814 		goto done;
815 
816 	/* Delta base must be in the same pack file. */
817 	idx = got_packidx_get_object_idx(packidx, &id);
818 	if (idx == -1) {
819 		err = got_error(GOT_ERR_BAD_PACKFILE);
820 		goto done;
821 	}
822 
823 	base_offset = get_object_offset(packidx, idx);
824 	if (base_offset == (uint64_t)-1) {
825 		err = got_error(GOT_ERR_BAD_PACKIDX);
826 		goto done;
827 	}
828 
829 	if (base_offset >= pack->filesize) {
830 		err = got_error(GOT_ERR_PACK_OFFSET);
831 		goto done;
832 	}
833 
834 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
835 	    pack, base_offset);
836 	if (err)
837 		goto done;
838 
839 	err = resolve_delta_chain(deltas, packidx, pack, base_offset,
840 	    base_tslen, base_type, base_size, recursion - 1);
841 done:
842 	if (err)
843 		free(delta_buf);
844 	return err;
845 }
846 
847 static const struct got_error *
848 resolve_delta_chain(struct got_delta_chain *deltas, struct got_packidx *packidx,
849     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
850     size_t delta_size, unsigned int recursion)
851 {
852 	const struct got_error *err = NULL;
853 
854 	if (--recursion == 0)
855 		return got_error(GOT_ERR_RECURSION);
856 
857 	switch (delta_type) {
858 	case GOT_OBJ_TYPE_COMMIT:
859 	case GOT_OBJ_TYPE_TREE:
860 	case GOT_OBJ_TYPE_BLOB:
861 	case GOT_OBJ_TYPE_TAG:
862 		/* Plain types are the final delta base. Recursion ends. */
863 		err = add_delta(deltas, delta_offset, tslen, delta_type,
864 		    delta_size, 0, NULL, 0);
865 		break;
866 	case GOT_OBJ_TYPE_OFFSET_DELTA:
867 		err = resolve_offset_delta(deltas, packidx, pack,
868 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
869 		break;
870 	case GOT_OBJ_TYPE_REF_DELTA:
871 		err = resolve_ref_delta(deltas, packidx, pack,
872 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
873 		break;
874 	default:
875 		return got_error(GOT_ERR_OBJ_TYPE);
876 	}
877 
878 	return err;
879 }
880 
881 static const struct got_error *
882 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
883     struct got_pack *pack, struct got_object_id *id, off_t offset,
884     size_t tslen, int delta_type, size_t delta_size, int idx)
885 {
886 	const struct got_error *err = NULL;
887 	int resolved_type;
888 
889 	*obj = calloc(1, sizeof(**obj));
890 	if (*obj == NULL)
891 		return got_error_prefix_errno("calloc");
892 
893 	(*obj)->flags = 0;
894 	(*obj)->hdrlen = 0;
895 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
896 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
897 	(*obj)->pack_offset = offset + tslen;
898 
899 	(*obj)->path_packfile = strdup(pack->path_packfile);
900 	if ((*obj)->path_packfile == NULL) {
901 		err = got_error_prefix_errno("strdup");
902 		goto done;
903 	}
904 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
905 	(*obj)->pack_idx = idx;
906 
907 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
908 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
909 
910 	err = resolve_delta_chain(&(*obj)->deltas, packidx, pack, offset,
911 	    tslen, delta_type, delta_size, GOT_DELTA_CHAIN_RECURSION_MAX);
912 	if (err)
913 		goto done;
914 
915 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
916 	if (err)
917 		goto done;
918 	(*obj)->type = resolved_type;
919 done:
920 	if (err) {
921 		got_object_close(*obj);
922 		*obj = NULL;
923 	}
924 	return err;
925 }
926 
927 const struct got_error *
928 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
929     struct got_packidx *packidx, int idx, struct got_object_id *id)
930 {
931 	const struct got_error *err = NULL;
932 	off_t offset;
933 	uint8_t type;
934 	uint64_t size;
935 	size_t tslen;
936 
937 	*obj = NULL;
938 
939 	offset = get_object_offset(packidx, idx);
940 	if (offset == (uint64_t)-1)
941 		return got_error(GOT_ERR_BAD_PACKIDX);
942 
943 	err = parse_object_type_and_size(&type, &size, &tslen, pack, offset);
944 	if (err)
945 		return err;
946 
947 	switch (type) {
948 	case GOT_OBJ_TYPE_COMMIT:
949 	case GOT_OBJ_TYPE_TREE:
950 	case GOT_OBJ_TYPE_BLOB:
951 	case GOT_OBJ_TYPE_TAG:
952 		err = open_plain_object(obj, pack->path_packfile, id, type,
953 		    offset + tslen, size, idx);
954 		break;
955 	case GOT_OBJ_TYPE_OFFSET_DELTA:
956 	case GOT_OBJ_TYPE_REF_DELTA:
957 		err = open_delta_object(obj, packidx, pack, id, offset,
958 		    tslen, type, size, idx);
959 		break;
960 	default:
961 		err = got_error(GOT_ERR_OBJ_TYPE);
962 		break;
963 	}
964 
965 	return err;
966 }
967 
968 static const struct got_error *
969 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
970 {
971 	struct got_delta *delta;
972 	uint64_t base_size = 0, result_size = 0;
973 
974 	*max_size = 0;
975 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
976 		/* Plain object types are the delta base. */
977 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
978 		    delta->type != GOT_OBJ_TYPE_TREE &&
979 		    delta->type != GOT_OBJ_TYPE_BLOB &&
980 		    delta->type != GOT_OBJ_TYPE_TAG) {
981 			const struct got_error *err;
982 			err = got_delta_get_sizes(&base_size, &result_size,
983 			    delta->delta_buf, delta->delta_len);
984 			if (err)
985 				return err;
986 		} else
987 			base_size = delta->size;
988 		if (base_size > *max_size)
989 			*max_size = base_size;
990 		if (result_size > *max_size)
991 			*max_size = result_size;
992 	}
993 
994 	return NULL;
995 }
996 
997 const struct got_error *
998 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj)
999 {
1000 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1001 		return got_error(GOT_ERR_OBJ_TYPE);
1002 
1003 	return get_delta_chain_max_size(size, &obj->deltas);
1004 }
1005 
1006 static const struct got_error *
1007 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1008     struct got_pack *pack, FILE *outfile, FILE *base_file, FILE *accum_file)
1009 {
1010 	const struct got_error *err = NULL;
1011 	struct got_delta *delta;
1012 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1013 	size_t base_bufsz = 0, accum_size = 0;
1014 	uint64_t max_size;
1015 	int n = 0;
1016 
1017 	*result_size = 0;
1018 
1019 	if (SIMPLEQ_EMPTY(&deltas->entries))
1020 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1021 
1022 	/* We process small enough files entirely in memory for speed. */
1023 	err = get_delta_chain_max_size(&max_size, deltas);
1024 	if (err)
1025 		return err;
1026 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1027 		accum_buf = malloc(max_size);
1028 		if (accum_buf == NULL)
1029 			return got_error_prefix_errno("malloc");
1030 		base_file = NULL;
1031 		accum_file = NULL;
1032 	}
1033 
1034 	/* Deltas are ordered in ascending order. */
1035 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1036 		if (n == 0) {
1037 			size_t mapoff;
1038 			off_t delta_data_offset;
1039 
1040 			/* Plain object types are the delta base. */
1041 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1042 			    delta->type != GOT_OBJ_TYPE_TREE &&
1043 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1044 			    delta->type != GOT_OBJ_TYPE_TAG) {
1045 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1046 				goto done;
1047 			}
1048 
1049 			delta_data_offset = delta->offset + delta->tslen;
1050 			if (delta_data_offset >= pack->filesize) {
1051 				err = got_error(GOT_ERR_PACK_OFFSET);
1052 				goto done;
1053 			}
1054 			if (pack->map == NULL) {
1055 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1056 				    == -1) {
1057 					err = got_error_prefix_errno("lseek");
1058 					goto done;
1059 				}
1060 			}
1061 			if (base_file) {
1062 				if (pack->map) {
1063 					mapoff = (size_t)delta_data_offset;
1064 					err = got_inflate_to_file_mmap(
1065 					    &base_bufsz, pack->map, mapoff,
1066 					    pack->filesize - mapoff, base_file);
1067 				} else
1068 					err = got_inflate_to_file_fd(
1069 					    &base_bufsz, pack->fd, base_file);
1070 			} else {
1071 				if (pack->map) {
1072 					mapoff = (size_t)delta_data_offset;
1073 					err = got_inflate_to_mem_mmap(&base_buf,
1074 					    &base_bufsz, pack->map, mapoff,
1075 					    pack->filesize - mapoff);
1076 				} else
1077 					err = got_inflate_to_mem_fd(&base_buf,
1078 					    &base_bufsz, pack->fd);
1079 			}
1080 			if (err)
1081 				goto done;
1082 			n++;
1083 			if (base_file)
1084 				rewind(base_file);
1085 			continue;
1086 		}
1087 
1088 		if (base_buf) {
1089 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1090 			    delta->delta_buf, delta->delta_len, accum_buf,
1091 			    &accum_size, max_size);
1092 			n++;
1093 		} else {
1094 			err = got_delta_apply(base_file, delta->delta_buf,
1095 			    delta->delta_len,
1096 			    /* Final delta application writes to output file. */
1097 			    ++n < deltas->nentries ? accum_file : outfile,
1098 			    &accum_size);
1099 		}
1100 		if (err)
1101 			goto done;
1102 
1103 		if (n < deltas->nentries) {
1104 			/* Accumulated delta becomes the new base. */
1105 			if (base_buf) {
1106 				uint8_t *tmp = accum_buf;
1107 				/*
1108 				 * Base buffer switches roles with accumulation
1109 				 * buffer. Ensure it can hold the largest
1110 				 * result in the delta chain. The initial
1111 				 * allocation might have been smaller.
1112 				 */
1113 				if (base_bufsz < max_size) {
1114 					uint8_t *p;
1115 					p = reallocarray(base_buf, 1, max_size);
1116 					if (p == NULL) {
1117 						err = got_error_prefix_errno(
1118 						    "reallocarray");
1119 						goto done;
1120 					}
1121 					base_buf = p;
1122 					base_bufsz = max_size;
1123 				}
1124 				accum_buf = base_buf;
1125 				base_buf = tmp;
1126 			} else {
1127 				FILE *tmp = accum_file;
1128 				accum_file = base_file;
1129 				base_file = tmp;
1130 				rewind(base_file);
1131 				rewind(accum_file);
1132 			}
1133 		}
1134 	}
1135 
1136 done:
1137 	free(base_buf);
1138 	if (accum_buf) {
1139 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1140 		free(accum_buf);
1141 		if (len != accum_size)
1142 			err = got_ferror(outfile, GOT_ERR_IO);
1143 	}
1144 	rewind(outfile);
1145 	if (err == NULL)
1146 		*result_size = accum_size;
1147 	return err;
1148 }
1149 
1150 static const struct got_error *
1151 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1152     struct got_delta_chain *deltas, struct got_pack *pack)
1153 {
1154 	const struct got_error *err = NULL;
1155 	struct got_delta *delta;
1156 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1157 	size_t base_bufsz = 0, accum_size = 0;
1158 	uint64_t max_size;
1159 	int n = 0;
1160 
1161 	*outbuf = NULL;
1162 	*outlen = 0;
1163 
1164 	if (SIMPLEQ_EMPTY(&deltas->entries))
1165 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1166 
1167 	err = get_delta_chain_max_size(&max_size, deltas);
1168 	if (err)
1169 		return err;
1170 	accum_buf = malloc(max_size);
1171 	if (accum_buf == NULL)
1172 		return got_error_prefix_errno("malloc");
1173 
1174 	/* Deltas are ordered in ascending order. */
1175 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1176 		if (n == 0) {
1177 			size_t delta_data_offset;
1178 
1179 			/* Plain object types are the delta base. */
1180 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1181 			    delta->type != GOT_OBJ_TYPE_TREE &&
1182 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1183 			    delta->type != GOT_OBJ_TYPE_TAG) {
1184 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1185 				goto done;
1186 			}
1187 
1188 			delta_data_offset = delta->offset + delta->tslen;
1189 			if (delta_data_offset >= pack->filesize) {
1190 				err = got_error(GOT_ERR_PACK_OFFSET);
1191 				goto done;
1192 			}
1193 			if (pack->map) {
1194 				size_t mapoff = (size_t)delta_data_offset;
1195 				err = got_inflate_to_mem_mmap(&base_buf,
1196 				    &base_bufsz, pack->map, mapoff,
1197 				    pack->filesize - mapoff);
1198 			} else {
1199 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1200 				    == -1) {
1201 					err = got_error_prefix_errno("lseek");
1202 					goto done;
1203 				}
1204 				err = got_inflate_to_mem_fd(&base_buf,
1205 				    &base_bufsz, pack->fd);
1206 			}
1207 			if (err)
1208 				goto done;
1209 			n++;
1210 			continue;
1211 		}
1212 
1213 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1214 		    delta->delta_buf, delta->delta_len, accum_buf,
1215 		    &accum_size, max_size);
1216 		n++;
1217 		if (err)
1218 			goto done;
1219 
1220 		if (n < deltas->nentries) {
1221 			/* Accumulated delta becomes the new base. */
1222 			uint8_t *tmp = accum_buf;
1223 			/*
1224 			 * Base buffer switches roles with accumulation buffer.
1225 			 * Ensure it can hold the largest result in the delta
1226 			 * chain. Initial allocation might have been smaller.
1227 			 */
1228 			if (base_bufsz < max_size) {
1229 				uint8_t *p;
1230 				p = reallocarray(base_buf, 1, max_size);
1231 				if (p == NULL) {
1232 					err = got_error_prefix_errno(
1233 					    "reallocarray");
1234 					goto done;
1235 				}
1236 				base_buf = p;
1237 				base_bufsz = max_size;
1238 			}
1239 			accum_buf = base_buf;
1240 			base_buf = tmp;
1241 		}
1242 	}
1243 
1244 done:
1245 	free(base_buf);
1246 	if (err) {
1247 		free(accum_buf);
1248 		*outbuf = NULL;
1249 		*outlen = 0;
1250 	} else {
1251 		*outbuf = accum_buf;
1252 		*outlen = accum_size;
1253 	}
1254 	return err;
1255 }
1256 
1257 const struct got_error *
1258 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1259     FILE *outfile, FILE *base_file, FILE *accum_file)
1260 {
1261 	const struct got_error *err = NULL;
1262 
1263 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1264 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1265 
1266 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1267 		if (obj->pack_offset >= pack->filesize)
1268 			return got_error(GOT_ERR_PACK_OFFSET);
1269 
1270 		if (pack->map) {
1271 			size_t mapoff = (size_t)obj->pack_offset;
1272 			err = got_inflate_to_file_mmap(&obj->size, pack->map,
1273 			    mapoff, pack->filesize - mapoff, outfile);
1274 		} else {
1275 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1276 				return got_error_prefix_errno("lseek");
1277 			err = got_inflate_to_file_fd(&obj->size, pack->fd,
1278 			    outfile);
1279 		}
1280 	} else
1281 		err = dump_delta_chain_to_file(&obj->size, &obj->deltas, pack,
1282 		    outfile, base_file, accum_file);
1283 
1284 	return err;
1285 }
1286 
1287 const struct got_error *
1288 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1289     struct got_object *obj, struct got_pack *pack)
1290 {
1291 	const struct got_error *err = NULL;
1292 
1293 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1294 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1295 
1296 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1297 		if (obj->pack_offset >= pack->filesize)
1298 			return got_error(GOT_ERR_PACK_OFFSET);
1299 		if (pack->map) {
1300 			size_t mapoff = (size_t)obj->pack_offset;
1301 			err = got_inflate_to_mem_mmap(buf, len, pack->map,
1302 			    mapoff, pack->filesize - mapoff);
1303 		} else {
1304 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1305 				return got_error_prefix_errno("lseek");
1306 			err = got_inflate_to_mem_fd(buf, len, pack->fd);
1307 		}
1308 	} else
1309 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, pack);
1310 
1311 	return err;
1312 }