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/uio.h>
20 #include <sys/mman.h>
21 
22 #include <fcntl.h>
23 #include <errno.h>
24 #include <stdio.h>
25 #include <stdint.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <limits.h>
29 #include <unistd.h>
30 #include <zlib.h>
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 #include "got_opentemp.h"
35 #include "got_path.h"
36 
37 #include "got_lib_sha1.h"
38 #include "got_lib_delta.h"
39 #include "got_lib_delta_cache.h"
40 #include "got_lib_inflate.h"
41 #include "got_lib_object.h"
42 #include "got_lib_object_parse.h"
43 #include "got_lib_privsep.h"
44 #include "got_lib_pack.h"
45 
46 #ifndef nitems
47 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
48 #endif
49 
50 #ifndef MIN
51 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
52 #endif
53 
54 static const struct got_error *
55 verify_fanout_table(uint32_t *fanout_table)
56 {
57 	int i;
58 
59 	for (i = 0; i < 0xff - 1; i++) {
60 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
61 			return got_error(GOT_ERR_BAD_PACKIDX);
62 	}
63 
64 	return NULL;
65 }
66 
67 const struct got_error *
68 got_packidx_init_hdr(struct got_packidx *p, int verify, off_t packfile_size)
69 {
70 	const struct got_error *err = NULL;
71 	struct got_packidx_v2_hdr *h;
72 	SHA1_CTX ctx;
73 	uint8_t sha1[SHA1_DIGEST_LENGTH];
74 	size_t nobj, len_fanout, len_ids, offset, remain;
75 	ssize_t n;
76 	int i;
77 
78 	SHA1Init(&ctx);
79 
80 	h = &p->hdr;
81 	offset = 0;
82 	remain = p->len;
83 
84 	if (remain < sizeof(*h->magic)) {
85 		err = got_error(GOT_ERR_BAD_PACKIDX);
86 		goto done;
87 	}
88 	if (p->map)
89 		h->magic = (uint32_t *)(p->map + offset);
90 	else {
91 		h->magic = malloc(sizeof(*h->magic));
92 		if (h->magic == NULL) {
93 			err = got_error_from_errno("malloc");
94 			goto done;
95 		}
96 		n = read(p->fd, h->magic, sizeof(*h->magic));
97 		if (n < 0) {
98 			err = got_error_from_errno("read");
99 			goto done;
100 		} else if (n != sizeof(*h->magic)) {
101 			err = got_error(GOT_ERR_BAD_PACKIDX);
102 			goto done;
103 		}
104 	}
105 	if (*h->magic != htobe32(GOT_PACKIDX_V2_MAGIC)) {
106 		err = got_error(GOT_ERR_BAD_PACKIDX);
107 		goto done;
108 	}
109 	offset += sizeof(*h->magic);
110 	remain -= sizeof(*h->magic);
111 
112 	if (verify)
113 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
114 
115 	if (remain < sizeof(*h->version)) {
116 		err = got_error(GOT_ERR_BAD_PACKIDX);
117 		goto done;
118 	}
119 	if (p->map)
120 		h->version = (uint32_t *)(p->map + offset);
121 	else {
122 		h->version = malloc(sizeof(*h->version));
123 		if (h->version == NULL) {
124 			err = got_error_from_errno("malloc");
125 			goto done;
126 		}
127 		n = read(p->fd, h->version, sizeof(*h->version));
128 		if (n < 0) {
129 			err = got_error_from_errno("read");
130 			goto done;
131 		} else if (n != sizeof(*h->version)) {
132 			err = got_error(GOT_ERR_BAD_PACKIDX);
133 			goto done;
134 		}
135 	}
136 	if (*h->version != htobe32(GOT_PACKIDX_VERSION)) {
137 		err = got_error(GOT_ERR_BAD_PACKIDX);
138 		goto done;
139 	}
140 	offset += sizeof(*h->version);
141 	remain -= sizeof(*h->version);
142 
143 	if (verify)
144 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
145 
146 	len_fanout =
147 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
148 	if (remain < len_fanout) {
149 		err = got_error(GOT_ERR_BAD_PACKIDX);
150 		goto done;
151 	}
152 	if (p->map)
153 		h->fanout_table = (uint32_t *)(p->map + offset);
154 	else {
155 		h->fanout_table = malloc(len_fanout);
156 		if (h->fanout_table == NULL) {
157 			err = got_error_from_errno("malloc");
158 			goto done;
159 		}
160 		n = read(p->fd, h->fanout_table, len_fanout);
161 		if (n < 0) {
162 			err = got_error_from_errno("read");
163 			goto done;
164 		} else if (n != len_fanout) {
165 			err = got_error(GOT_ERR_BAD_PACKIDX);
166 			goto done;
167 		}
168 	}
169 	err = verify_fanout_table(h->fanout_table);
170 	if (err)
171 		goto done;
172 	if (verify)
173 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
174 	offset += len_fanout;
175 	remain -= len_fanout;
176 
177 	nobj = be32toh(h->fanout_table[0xff]);
178 	len_ids = nobj * sizeof(*h->sorted_ids);
179 	if (len_ids <= nobj || len_ids > remain) {
180 		err = got_error(GOT_ERR_BAD_PACKIDX);
181 		goto done;
182 	}
183 	if (p->map)
184 		h->sorted_ids =
185 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
186 	else {
187 		h->sorted_ids = malloc(len_ids);
188 		if (h->sorted_ids == NULL) {
189 			err = got_error(GOT_ERR_BAD_PACKIDX);
190 			goto done;
191 		}
192 		n = read(p->fd, h->sorted_ids, len_ids);
193 		if (n < 0)
194 			err = got_error_from_errno("read");
195 		else if (n != len_ids) {
196 			err = got_error(GOT_ERR_BAD_PACKIDX);
197 			goto done;
198 		}
199 	}
200 	if (verify)
201 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
202 	offset += len_ids;
203 	remain -= len_ids;
204 
205 	if (remain < nobj * sizeof(*h->crc32)) {
206 		err = got_error(GOT_ERR_BAD_PACKIDX);
207 		goto done;
208 	}
209 	if (p->map)
210 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
211 	else {
212 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
213 		if (h->crc32 == NULL) {
214 			err = got_error_from_errno("malloc");
215 			goto done;
216 		}
217 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
218 		if (n < 0)
219 			err = got_error_from_errno("read");
220 		else if (n != nobj * sizeof(*h->crc32)) {
221 			err = got_error(GOT_ERR_BAD_PACKIDX);
222 			goto done;
223 		}
224 	}
225 	if (verify)
226 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
227 	remain -= nobj * sizeof(*h->crc32);
228 	offset += nobj * sizeof(*h->crc32);
229 
230 	if (remain < nobj * sizeof(*h->offsets)) {
231 		err = got_error(GOT_ERR_BAD_PACKIDX);
232 		goto done;
233 	}
234 	if (p->map)
235 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
236 	else {
237 		h->offsets = malloc(nobj * sizeof(*h->offsets));
238 		if (h->offsets == NULL) {
239 			err = got_error_from_errno("malloc");
240 			goto done;
241 		}
242 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
243 		if (n < 0)
244 			err = got_error_from_errno("read");
245 		else if (n != nobj * sizeof(*h->offsets)) {
246 			err = got_error(GOT_ERR_BAD_PACKIDX);
247 			goto done;
248 		}
249 	}
250 	if (verify)
251 		SHA1Update(&ctx, (uint8_t *)h->offsets,
252 		    nobj * sizeof(*h->offsets));
253 	remain -= nobj * sizeof(*h->offsets);
254 	offset += nobj * sizeof(*h->offsets);
255 
256 	/* Large file offsets are contained only in files > 2GB. */
257 	if (verify || packfile_size > 0x7fffffff) {
258 		for (i = 0; i < nobj; i++) {
259 			uint32_t o = h->offsets[i];
260 			if (o & htobe32(GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX))
261 				p->nlargeobj++;
262 		}
263 	}
264 	if (p->nlargeobj == 0)
265 		goto checksum;
266 	else if (packfile_size <= 0x7fffffff) {
267 		err = got_error(GOT_ERR_BAD_PACKIDX);
268 		goto done;
269 	}
270 
271 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
272 		err = got_error(GOT_ERR_BAD_PACKIDX);
273 		goto done;
274 	}
275 	if (p->map)
276 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
277 	else {
278 		h->large_offsets = malloc(p->nlargeobj *
279 		    sizeof(*h->large_offsets));
280 		if (h->large_offsets == NULL) {
281 			err = got_error_from_errno("malloc");
282 			goto done;
283 		}
284 		n = read(p->fd, h->large_offsets,
285 		    p->nlargeobj * sizeof(*h->large_offsets));
286 		if (n < 0)
287 			err = got_error_from_errno("read");
288 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
289 			err = got_error(GOT_ERR_BAD_PACKIDX);
290 			goto done;
291 		}
292 	}
293 	if (verify)
294 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
295 		    p->nlargeobj * sizeof(*h->large_offsets));
296 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
297 	offset += p->nlargeobj * sizeof(*h->large_offsets);
298 
299 checksum:
300 	if (remain < sizeof(*h->trailer)) {
301 		err = got_error(GOT_ERR_BAD_PACKIDX);
302 		goto done;
303 	}
304 	if (p->map)
305 		h->trailer =
306 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
307 	else {
308 		h->trailer = malloc(sizeof(*h->trailer));
309 		if (h->trailer == NULL) {
310 			err = got_error_from_errno("malloc");
311 			goto done;
312 		}
313 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
314 		if (n < 0)
315 			err = got_error_from_errno("read");
316 		else if (n != sizeof(*h->trailer)) {
317 			err = got_error(GOT_ERR_BAD_PACKIDX);
318 			goto done;
319 		}
320 	}
321 	if (verify) {
322 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
323 		SHA1Final(sha1, &ctx);
324 		if (memcmp(h->trailer->packidx_sha1, sha1,
325 		    SHA1_DIGEST_LENGTH) != 0)
326 			err = got_error(GOT_ERR_PACKIDX_CSUM);
327 	}
328 done:
329 	return err;
330 }
331 
332 const struct got_error *
333 got_packidx_open(struct got_packidx **packidx,
334     int dir_fd, const char *relpath, int verify)
335 {
336 	const struct got_error *err = NULL;
337 	struct got_packidx *p = NULL;
338 	char *pack_relpath;
339 	struct stat idx_sb, pack_sb;
340 
341 	*packidx = NULL;
342 
343 	err = got_packidx_get_packfile_path(&pack_relpath, relpath);
344 	if (err)
345 		return err;
346 
347 	/*
348 	 * Ensure that a corresponding pack file exists.
349 	 * Some Git repositories have this problem. Git seems to ignore
350 	 * the existence of lonely pack index files but we do not.
351 	 */
352 	if (fstatat(dir_fd, pack_relpath, &pack_sb, 0) == -1) {
353 		if (errno == ENOENT) {
354 			err = got_error_fmt(GOT_ERR_LONELY_PACKIDX,
355 			    "%s", relpath);
356 		} else
357 			err = got_error_from_errno2("fstatat", pack_relpath);
358 		goto done;
359 	}
360 
361 	p = calloc(1, sizeof(*p));
362 	if (p == NULL) {
363 		err = got_error_from_errno("calloc");
364 		goto done;
365 	}
366 
367 	p->fd = openat(dir_fd, relpath, O_RDONLY | O_NOFOLLOW);
368 	if (p->fd == -1) {
369 		err = got_error_from_errno2("openat", relpath);
370 		free(p);
371 		goto done;
372 	}
373 
374 	if (fstat(p->fd, &idx_sb) != 0) {
375 		err = got_error_from_errno2("fstat", relpath);
376 		close(p->fd);
377 		free(p);
378 		goto done;
379 	}
380 	p->len = idx_sb.st_size;
381 	if (p->len < sizeof(p->hdr)) {
382 		err = got_error(GOT_ERR_BAD_PACKIDX);
383 		close(p->fd);
384 		free(p);
385 		goto done;
386 	}
387 
388 	p->path_packidx = strdup(relpath);
389 	if (p->path_packidx == NULL) {
390 		err = got_error_from_errno("strdup");
391 		goto done;
392 	}
393 
394 #ifndef GOT_PACK_NO_MMAP
395 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
396 	if (p->map == MAP_FAILED) {
397 		if (errno != ENOMEM) {
398 			err = got_error_from_errno("mmap");
399 			goto done;
400 		}
401 		p->map = NULL; /* fall back to read(2) */
402 	}
403 #endif
404 
405 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
406 done:
407 	if (err) {
408 		if (p)
409 			got_packidx_close(p);
410 	} else
411 		*packidx = p;
412 	free(pack_relpath);
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_from_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) == -1 && err == NULL)
436 		err = got_error_from_errno("close");
437 	free(packidx);
438 
439 	return err;
440 }
441 
442 const struct got_error *
443 got_packidx_get_packfile_path(char **path_packfile, const char *path_packidx)
444 {
445 	size_t size;
446 
447 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
448 	size = strlen(path_packidx) + 2;
449 	if (size < GOT_PACKFILE_NAMELEN + 1)
450 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
451 
452 	*path_packfile = malloc(size);
453 	if (*path_packfile == NULL)
454 		return got_error_from_errno("malloc");
455 
456 	/* Copy up to and excluding ".idx". */
457 	if (strlcpy(*path_packfile, path_packidx,
458 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
459 		return got_error(GOT_ERR_NO_SPACE);
460 
461 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
462 		return got_error(GOT_ERR_NO_SPACE);
463 
464 	return NULL;
465 }
466 
467 off_t
468 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
469 {
470 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
471 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
472 		uint64_t loffset;
473 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
474 		if (idx < 0 || idx >= packidx->nlargeobj ||
475 		    packidx->hdr.large_offsets == NULL)
476 			return -1;
477 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
478 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
479 	}
480 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
481 }
482 
483 int
484 got_packidx_get_object_idx(struct got_packidx *packidx, struct got_object_id *id)
485 {
486 	u_int8_t id0 = id->sha1[0];
487 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
488 	int left = 0, right = totobj - 1;
489 
490 	if (id0 > 0)
491 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
492 
493 	while (left <= right) {
494 		struct got_packidx_object_id *oid;
495 		int i, cmp;
496 
497 		i = ((left + right) / 2);
498 		oid = &packidx->hdr.sorted_ids[i];
499 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
500 		if (cmp == 0)
501 			return i;
502 		else if (cmp > 0)
503 			left = i + 1;
504 		else if (cmp < 0)
505 			right = i - 1;
506 	}
507 
508 	return -1;
509 }
510 
511 const struct got_error *
512 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
513     struct got_packidx *packidx, const char *id_str_prefix)
514 {
515 	const struct got_error *err = NULL;
516 	u_int8_t id0;
517 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
518 	char hex[3];
519 	size_t prefix_len = strlen(id_str_prefix);
520 	struct got_packidx_object_id *oid;
521 	uint32_t i;
522 
523 	STAILQ_INIT(matched_ids);
524 
525 	if (prefix_len < 2)
526 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
527 
528 	hex[0] = id_str_prefix[0];
529 	hex[1] = id_str_prefix[1];
530 	hex[2] = '\0';
531 	if (!got_parse_xdigit(&id0, hex))
532 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
533 
534 	i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
535 	oid = &packidx->hdr.sorted_ids[i];
536 	while (i < totobj && oid->sha1[0] == id0) {
537 		char id_str[SHA1_DIGEST_STRING_LENGTH];
538 		struct got_object_qid *qid;
539 		int cmp;
540 
541 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
542 		        return got_error(GOT_ERR_NO_SPACE);
543 
544 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
545 		if (cmp < 0) {
546 			oid = &packidx->hdr.sorted_ids[++i];
547 			continue;
548 		} else if (cmp > 0)
549 			break;
550 
551 		err = got_object_qid_alloc_partial(&qid);
552 		if (err)
553 			break;
554 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
555 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
556 
557 		oid = &packidx->hdr.sorted_ids[++i];
558 	}
559 
560 	if (err)
561 		got_object_id_queue_free(matched_ids);
562 	return err;
563 }
564 
565 static const struct got_error *
566 pack_stop_privsep_child(struct got_pack *pack)
567 {
568 	const struct got_error *err = NULL;
569 
570 	if (pack->privsep_child == NULL)
571 		return NULL;
572 
573 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
574 	if (err)
575 		return err;
576 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
577 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
578 		err = got_error_from_errno("close");
579 	imsg_clear(pack->privsep_child->ibuf);
580 	free(pack->privsep_child->ibuf);
581 	free(pack->privsep_child);
582 	pack->privsep_child = NULL;
583 	return err;
584 }
585 
586 const struct got_error *
587 got_pack_close(struct got_pack *pack)
588 {
589 	const struct got_error *err = NULL;
590 
591 	err = pack_stop_privsep_child(pack);
592 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
593 		err = got_error_from_errno("munmap");
594 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
595 		err = got_error_from_errno("close");
596 	pack->fd = -1;
597 	free(pack->path_packfile);
598 	pack->path_packfile = NULL;
599 	pack->filesize = 0;
600 	if (pack->delta_cache) {
601 		got_delta_cache_free(pack->delta_cache);
602 		pack->delta_cache = NULL;
603 	}
604 
605 	return err;
606 }
607 
608 const struct got_error *
609 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
610     struct got_pack *pack, off_t offset)
611 {
612 	uint8_t t = 0;
613 	uint64_t s = 0;
614 	uint8_t sizeN;
615 	size_t mapoff = 0;
616 	int i = 0;
617 
618 	*len = 0;
619 
620 	if (offset >= pack->filesize)
621 		return got_error(GOT_ERR_PACK_OFFSET);
622 
623 	if (pack->map) {
624 		mapoff = (size_t)offset;
625 	} else {
626 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
627 			return got_error_from_errno("lseek");
628 	}
629 
630 	do {
631 		/* We do not support size values which don't fit in 64 bit. */
632 		if (i > 9)
633 			return got_error(GOT_ERR_NO_SPACE);
634 
635 		if (pack->map) {
636 			sizeN = *(pack->map + mapoff);
637 			mapoff += sizeof(sizeN);
638 		} else {
639 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
640 			if (n < 0)
641 				return got_error_from_errno("read");
642 			if (n != sizeof(sizeN))
643 				return got_error(GOT_ERR_BAD_PACKFILE);
644 		}
645 		*len += sizeof(sizeN);
646 
647 		if (i == 0) {
648 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
649 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
650 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
651 		} else {
652 			size_t shift = 4 + 7 * (i - 1);
653 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
654 		}
655 		i++;
656 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
657 
658 	*type = t;
659 	*size = s;
660 	return NULL;
661 }
662 
663 static const struct got_error *
664 open_plain_object(struct got_object **obj, struct got_object_id *id,
665     uint8_t type, off_t offset, size_t size, int idx)
666 {
667 	*obj = calloc(1, sizeof(**obj));
668 	if (*obj == NULL)
669 		return got_error_from_errno("calloc");
670 
671 	(*obj)->type = type;
672 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
673 	(*obj)->pack_idx = idx;
674 	(*obj)->hdrlen = 0;
675 	(*obj)->size = size;
676 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
677 	(*obj)->pack_offset = offset;
678 
679 	return NULL;
680 }
681 
682 static const struct got_error *
683 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
684     off_t delta_offset)
685 {
686 	int64_t o = 0;
687 	uint8_t offN;
688 	int i = 0;
689 
690 	*offset = 0;
691 	*len = 0;
692 
693 	do {
694 		/* We do not support offset values which don't fit in 64 bit. */
695 		if (i > 8)
696 			return got_error(GOT_ERR_NO_SPACE);
697 
698 		if (pack->map) {
699 			size_t mapoff;
700 			if (delta_offset >= pack->filesize)
701 				return got_error(GOT_ERR_PACK_OFFSET);
702 			mapoff = (size_t)delta_offset + *len;
703 			offN = *(pack->map + mapoff);
704 		} else {
705 			ssize_t n;
706 			n = read(pack->fd, &offN, sizeof(offN));
707 			if (n < 0)
708 				return got_error_from_errno("read");
709 			if (n != sizeof(offN))
710 				return got_error(GOT_ERR_BAD_PACKFILE);
711 		}
712 		*len += sizeof(offN);
713 
714 		if (i == 0)
715 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
716 		else {
717 			o++;
718 			o <<= 7;
719 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
720 		}
721 		i++;
722 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
723 
724 	*offset = o;
725 	return NULL;
726 }
727 
728 const struct got_error *
729 got_pack_parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
730     off_t offset, int tslen)
731 {
732 	const struct got_error *err;
733 	int64_t negoffset;
734 	size_t negofflen;
735 
736 	*len = 0;
737 
738 	err = parse_negative_offset(&negoffset, &negofflen, pack,
739 	    offset + tslen);
740 	if (err)
741 		return err;
742 
743 	/* Compute the base object's offset (must be in the same pack file). */
744 	*base_offset = (offset - negoffset);
745 	if (*base_offset <= 0)
746 		return got_error(GOT_ERR_BAD_PACKFILE);
747 
748 	*len = negofflen;
749 	return NULL;
750 }
751 
752 static const struct got_error *
753 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
754     size_t delta_data_offset, struct got_pack *pack)
755 {
756 	const struct got_error *err = NULL;
757 
758 	if (pack->map) {
759 		if (delta_data_offset >= pack->filesize)
760 			return got_error(GOT_ERR_PACK_OFFSET);
761 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
762 		    NULL, NULL, pack->map, delta_data_offset,
763 		    pack->filesize - delta_data_offset);
764 	} else {
765 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
766 			return got_error_from_errno("lseek");
767 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
768 		    NULL, 0, pack->fd);
769 	}
770 	return err;
771 }
772 
773 static const struct got_error *
774 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
775     int delta_type, size_t delta_size, size_t delta_data_offset)
776 {
777 	struct got_delta *delta;
778 
779 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
780 	    delta_data_offset);
781 	if (delta == NULL)
782 		return got_error_from_errno("got_delta_open");
783 	/* delta is freed in got_object_close() */
784 	deltas->nentries++;
785 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
786 	return NULL;
787 }
788 
789 static const struct got_error *
790 resolve_offset_delta(struct got_delta_chain *deltas,
791     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
792     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
793 
794 {
795 	const struct got_error *err;
796 	off_t base_offset;
797 	uint8_t base_type;
798 	uint64_t base_size;
799 	size_t base_tslen;
800 	off_t delta_data_offset;
801 	size_t consumed;
802 
803 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
804 	    delta_offset, tslen);
805 	if (err)
806 		return err;
807 
808 	delta_data_offset = delta_offset + tslen + consumed;
809 	if (delta_data_offset >= pack->filesize)
810 		return got_error(GOT_ERR_PACK_OFFSET);
811 
812 	if (pack->map == NULL) {
813 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
814 		if (delta_data_offset == -1)
815 			return got_error_from_errno("lseek");
816 	}
817 
818 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
819 	    delta_data_offset);
820 	if (err)
821 		return err;
822 
823 	/* An offset delta must be in the same packfile. */
824 	if (base_offset >= pack->filesize)
825 		return got_error(GOT_ERR_PACK_OFFSET);
826 
827 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
828 	    &base_tslen, pack, base_offset);
829 	if (err)
830 		return err;
831 
832 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
833 	    base_tslen, base_type, base_size, recursion - 1);
834 }
835 
836 const struct got_error *
837 got_pack_parse_ref_delta(struct got_object_id *id,
838     struct got_pack *pack, off_t delta_offset, int tslen)
839 {
840 	if (pack->map) {
841 		size_t mapoff = delta_offset + tslen;
842 		memcpy(id, pack->map + mapoff, sizeof(*id));
843 	} else {
844 		ssize_t n;
845 		n = read(pack->fd, id, sizeof(*id));
846 		if (n < 0)
847 			return got_error_from_errno("read");
848 		if (n != sizeof(*id))
849 			return got_error(GOT_ERR_BAD_PACKFILE);
850 	}
851 
852 	return NULL;
853 }
854 
855 static const struct got_error *
856 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
857     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
858     size_t delta_size, unsigned int recursion)
859 {
860 	const struct got_error *err;
861 	struct got_object_id id;
862 	int idx;
863 	off_t base_offset;
864 	uint8_t base_type;
865 	uint64_t base_size;
866 	size_t base_tslen;
867 	off_t delta_data_offset;
868 
869 	if (delta_offset + tslen >= pack->filesize)
870 		return got_error(GOT_ERR_PACK_OFFSET);
871 
872 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
873 	if (err)
874 		return err;
875 	if (pack->map) {
876 		delta_data_offset = delta_offset + tslen + sizeof(id);
877 	} else {
878 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
879 		if (delta_data_offset == -1)
880 			return got_error_from_errno("lseek");
881 	}
882 
883 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
884 	    delta_data_offset);
885 	if (err)
886 		return err;
887 
888 	/* Delta base must be in the same pack file. */
889 	idx = got_packidx_get_object_idx(packidx, &id);
890 	if (idx == -1)
891 		return got_error(GOT_ERR_NO_OBJ);
892 
893 	base_offset = got_packidx_get_object_offset(packidx, idx);
894 	if (base_offset == (uint64_t)-1)
895 		return got_error(GOT_ERR_BAD_PACKIDX);
896 
897 	if (base_offset >= pack->filesize)
898 		return got_error(GOT_ERR_PACK_OFFSET);
899 
900 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
901 	    &base_tslen, pack, base_offset);
902 	if (err)
903 		return err;
904 
905 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
906 	    base_tslen, base_type, base_size, recursion - 1);
907 }
908 
909 const struct got_error *
910 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
911     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
912     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
913 {
914 	const struct got_error *err = NULL;
915 
916 	if (--recursion == 0)
917 		return got_error(GOT_ERR_RECURSION);
918 
919 	switch (delta_type) {
920 	case GOT_OBJ_TYPE_COMMIT:
921 	case GOT_OBJ_TYPE_TREE:
922 	case GOT_OBJ_TYPE_BLOB:
923 	case GOT_OBJ_TYPE_TAG:
924 		/* Plain types are the final delta base. Recursion ends. */
925 		err = add_delta(deltas, delta_offset, tslen, delta_type,
926 		    delta_size, 0);
927 		break;
928 	case GOT_OBJ_TYPE_OFFSET_DELTA:
929 		err = resolve_offset_delta(deltas, packidx, pack,
930 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
931 		break;
932 	case GOT_OBJ_TYPE_REF_DELTA:
933 		err = resolve_ref_delta(deltas, packidx, pack,
934 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
935 		break;
936 	default:
937 		return got_error(GOT_ERR_OBJ_TYPE);
938 	}
939 
940 	return err;
941 }
942 
943 static const struct got_error *
944 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
945     struct got_pack *pack, struct got_object_id *id, off_t offset,
946     size_t tslen, int delta_type, size_t delta_size, int idx)
947 {
948 	const struct got_error *err = NULL;
949 	int resolved_type;
950 
951 	*obj = calloc(1, sizeof(**obj));
952 	if (*obj == NULL)
953 		return got_error_from_errno("calloc");
954 
955 	(*obj)->flags = 0;
956 	(*obj)->hdrlen = 0;
957 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
958 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
959 	(*obj)->pack_offset = offset + tslen;
960 
961 	STAILQ_INIT(&(*obj)->deltas.entries);
962 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
963 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
964 	(*obj)->pack_idx = idx;
965 
966 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
967 	    offset, tslen, delta_type, delta_size,
968 	    GOT_DELTA_CHAIN_RECURSION_MAX);
969 	if (err)
970 		goto done;
971 
972 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
973 	if (err)
974 		goto done;
975 	(*obj)->type = resolved_type;
976 done:
977 	if (err) {
978 		got_object_close(*obj);
979 		*obj = NULL;
980 	}
981 	return err;
982 }
983 
984 const struct got_error *
985 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
986     struct got_packidx *packidx, int idx, struct got_object_id *id)
987 {
988 	const struct got_error *err = NULL;
989 	off_t offset;
990 	uint8_t type;
991 	uint64_t size;
992 	size_t tslen;
993 
994 	*obj = NULL;
995 
996 	offset = got_packidx_get_object_offset(packidx, idx);
997 	if (offset == (uint64_t)-1)
998 		return got_error(GOT_ERR_BAD_PACKIDX);
999 
1000 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1001 	    pack, offset);
1002 	if (err)
1003 		return err;
1004 
1005 	switch (type) {
1006 	case GOT_OBJ_TYPE_COMMIT:
1007 	case GOT_OBJ_TYPE_TREE:
1008 	case GOT_OBJ_TYPE_BLOB:
1009 	case GOT_OBJ_TYPE_TAG:
1010 		err = open_plain_object(obj, id, type, offset + tslen,
1011 		    size, idx);
1012 		break;
1013 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1014 	case GOT_OBJ_TYPE_REF_DELTA:
1015 		err = open_delta_object(obj, packidx, pack, id, offset,
1016 		    tslen, type, size, idx);
1017 		break;
1018 	default:
1019 		err = got_error(GOT_ERR_OBJ_TYPE);
1020 		break;
1021 	}
1022 
1023 	return err;
1024 }
1025 
1026 const struct got_error *
1027 got_pack_get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
1028     struct got_pack *pack)
1029 {
1030 	struct got_delta *delta;
1031 	uint64_t base_size = 0, result_size = 0;
1032 
1033 	*max_size = 0;
1034 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1035 		/* Plain object types are the delta base. */
1036 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1037 		    delta->type != GOT_OBJ_TYPE_TREE &&
1038 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1039 		    delta->type != GOT_OBJ_TYPE_TAG) {
1040 			const struct got_error *err;
1041 			uint8_t *delta_buf;
1042 			size_t delta_len;
1043 			int cached = 1;
1044 
1045 			got_delta_cache_get(&delta_buf, &delta_len,
1046 			    pack->delta_cache, delta->data_offset);
1047 			if (delta_buf == NULL) {
1048 				cached = 0;
1049 				err = read_delta_data(&delta_buf, &delta_len,
1050 				    delta->data_offset, pack);
1051 				if (err)
1052 					return err;
1053 				err = got_delta_cache_add(pack->delta_cache,
1054 				    delta->data_offset, delta_buf, delta_len);
1055 				if (err == NULL)
1056 					cached = 1;
1057 				else if (err->code != GOT_ERR_NO_SPACE) {
1058 					free(delta_buf);
1059 					return err;
1060 				}
1061 			}
1062 			err = got_delta_get_sizes(&base_size, &result_size,
1063 			    delta_buf, delta_len);
1064 			if (!cached)
1065 				free(delta_buf);
1066 			if (err)
1067 				return err;
1068 		} else
1069 			base_size = delta->size;
1070 		if (base_size > *max_size)
1071 			*max_size = base_size;
1072 		if (result_size > *max_size)
1073 			*max_size = result_size;
1074 	}
1075 
1076 	return NULL;
1077 }
1078 
1079 const struct got_error *
1080 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1081     struct got_pack *pack)
1082 {
1083 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1084 		return got_error(GOT_ERR_OBJ_TYPE);
1085 
1086 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1087 }
1088 
1089 const struct got_error *
1090 got_pack_dump_delta_chain_to_file(size_t *result_size,
1091     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1092     FILE *base_file, FILE *accum_file)
1093 {
1094 	const struct got_error *err = NULL;
1095 	struct got_delta *delta;
1096 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1097 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1098 	uint64_t max_size;
1099 	int n = 0;
1100 
1101 	*result_size = 0;
1102 
1103 	if (STAILQ_EMPTY(&deltas->entries))
1104 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1105 
1106 	/* We process small enough files entirely in memory for speed. */
1107 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1108 	if (err)
1109 		return err;
1110 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1111 		accum_buf = malloc(max_size);
1112 		if (accum_buf == NULL)
1113 			return got_error_from_errno("malloc");
1114 		base_file = NULL;
1115 		accum_file = NULL;
1116 	}
1117 
1118 	/* Deltas are ordered in ascending order. */
1119 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1120 		int cached = 1;
1121 		if (n == 0) {
1122 			size_t mapoff;
1123 			off_t delta_data_offset;
1124 
1125 			/* Plain object types are the delta base. */
1126 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1127 			    delta->type != GOT_OBJ_TYPE_TREE &&
1128 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1129 			    delta->type != GOT_OBJ_TYPE_TAG) {
1130 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1131 				goto done;
1132 			}
1133 
1134 			delta_data_offset = delta->offset + delta->tslen;
1135 			if (delta_data_offset >= pack->filesize) {
1136 				err = got_error(GOT_ERR_PACK_OFFSET);
1137 				goto done;
1138 			}
1139 			if (pack->map == NULL) {
1140 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1141 				    == -1) {
1142 					err = got_error_from_errno("lseek");
1143 					goto done;
1144 				}
1145 			}
1146 			if (base_file) {
1147 				if (pack->map) {
1148 					mapoff = (size_t)delta_data_offset;
1149 					err = got_inflate_to_file_mmap(
1150 					    &base_bufsz, NULL, NULL, pack->map,
1151 					    mapoff, pack->filesize - mapoff,
1152 					    base_file);
1153 				} else
1154 					err = got_inflate_to_file_fd(
1155 					    &base_bufsz, NULL, NULL, pack->fd,
1156 					    base_file);
1157 			} else {
1158 				if (pack->map) {
1159 					mapoff = (size_t)delta_data_offset;
1160 					err = got_inflate_to_mem_mmap(&base_buf,
1161 					    &base_bufsz, NULL, NULL,
1162 					    pack->map, mapoff,
1163 					    pack->filesize - mapoff);
1164 				} else
1165 					err = got_inflate_to_mem_fd(&base_buf,
1166 					    &base_bufsz, NULL, NULL, max_size,
1167 					    pack->fd);
1168 			}
1169 			if (err)
1170 				goto done;
1171 			n++;
1172 			if (base_file)
1173 				rewind(base_file);
1174 			continue;
1175 		}
1176 
1177 		got_delta_cache_get(&delta_buf, &delta_len,
1178 		    pack->delta_cache, delta->data_offset);
1179 		if (delta_buf == NULL) {
1180 			cached = 0;
1181 			err = read_delta_data(&delta_buf, &delta_len,
1182 			    delta->data_offset, pack);
1183 			if (err)
1184 				goto done;
1185 			err = got_delta_cache_add(pack->delta_cache,
1186 			    delta->data_offset, delta_buf, delta_len);
1187 			if (err == NULL)
1188 				cached = 1;
1189 			else if (err->code != GOT_ERR_NO_SPACE) {
1190 				free(delta_buf);
1191 				goto done;
1192 			}
1193 		}
1194 		if (base_buf) {
1195 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1196 			    delta_buf, delta_len, accum_buf,
1197 			    &accum_size, max_size);
1198 			n++;
1199 		} else {
1200 			err = got_delta_apply(base_file, delta_buf,
1201 			    delta_len,
1202 			    /* Final delta application writes to output file. */
1203 			    ++n < deltas->nentries ? accum_file : outfile,
1204 			    &accum_size);
1205 		}
1206 		if (!cached)
1207 			free(delta_buf);
1208 		if (err)
1209 			goto done;
1210 
1211 		if (n < deltas->nentries) {
1212 			/* Accumulated delta becomes the new base. */
1213 			if (base_buf) {
1214 				uint8_t *tmp = accum_buf;
1215 				/*
1216 				 * Base buffer switches roles with accumulation
1217 				 * buffer. Ensure it can hold the largest
1218 				 * result in the delta chain. The initial
1219 				 * allocation might have been smaller.
1220 				 */
1221 				if (base_bufsz < max_size) {
1222 					uint8_t *p;
1223 					p = reallocarray(base_buf, 1, max_size);
1224 					if (p == NULL) {
1225 						err = got_error_from_errno(
1226 						    "reallocarray");
1227 						goto done;
1228 					}
1229 					base_buf = p;
1230 					base_bufsz = max_size;
1231 				}
1232 				accum_buf = base_buf;
1233 				base_buf = tmp;
1234 			} else {
1235 				FILE *tmp = accum_file;
1236 				accum_file = base_file;
1237 				base_file = tmp;
1238 				rewind(base_file);
1239 				rewind(accum_file);
1240 			}
1241 		}
1242 	}
1243 
1244 done:
1245 	free(base_buf);
1246 	if (accum_buf) {
1247 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1248 		free(accum_buf);
1249 		if (len != accum_size)
1250 			err = got_ferror(outfile, GOT_ERR_IO);
1251 	}
1252 	rewind(outfile);
1253 	if (err == NULL)
1254 		*result_size = accum_size;
1255 	return err;
1256 }
1257 
1258 const struct got_error *
1259 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1260     struct got_delta_chain *deltas, struct got_pack *pack)
1261 {
1262 	const struct got_error *err = NULL;
1263 	struct got_delta *delta;
1264 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1265 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1266 	uint64_t max_size;
1267 	int n = 0;
1268 
1269 	*outbuf = NULL;
1270 	*outlen = 0;
1271 
1272 	if (STAILQ_EMPTY(&deltas->entries))
1273 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1274 
1275 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1276 	if (err)
1277 		return err;
1278 	accum_buf = malloc(max_size);
1279 	if (accum_buf == NULL)
1280 		return got_error_from_errno("malloc");
1281 
1282 	/* Deltas are ordered in ascending order. */
1283 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1284 		int cached = 1;
1285 		if (n == 0) {
1286 			size_t delta_data_offset;
1287 
1288 			/* Plain object types are the delta base. */
1289 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1290 			    delta->type != GOT_OBJ_TYPE_TREE &&
1291 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1292 			    delta->type != GOT_OBJ_TYPE_TAG) {
1293 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1294 				goto done;
1295 			}
1296 
1297 			delta_data_offset = delta->offset + delta->tslen;
1298 			if (delta_data_offset >= pack->filesize) {
1299 				err = got_error(GOT_ERR_PACK_OFFSET);
1300 				goto done;
1301 			}
1302 			if (pack->map) {
1303 				size_t mapoff = (size_t)delta_data_offset;
1304 				err = got_inflate_to_mem_mmap(&base_buf,
1305 				    &base_bufsz, NULL, NULL, pack->map,
1306 				    mapoff, pack->filesize - mapoff);
1307 			} else {
1308 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1309 				    == -1) {
1310 					err = got_error_from_errno("lseek");
1311 					goto done;
1312 				}
1313 				err = got_inflate_to_mem_fd(&base_buf,
1314 				    &base_bufsz, NULL, NULL, max_size,
1315 				    pack->fd);
1316 			}
1317 			if (err)
1318 				goto done;
1319 			n++;
1320 			continue;
1321 		}
1322 
1323 		got_delta_cache_get(&delta_buf, &delta_len,
1324 		    pack->delta_cache, delta->data_offset);
1325 		if (delta_buf == NULL) {
1326 			cached = 0;
1327 			err = read_delta_data(&delta_buf, &delta_len,
1328 			    delta->data_offset, pack);
1329 			if (err)
1330 				goto done;
1331 			err = got_delta_cache_add(pack->delta_cache,
1332 			    delta->data_offset, delta_buf, delta_len);
1333 			if (err == NULL)
1334 				cached = 1;
1335 			else if (err->code != GOT_ERR_NO_SPACE) {
1336 				free(delta_buf);
1337 				goto done;
1338 			}
1339 		}
1340 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1341 		    delta_buf, delta_len, accum_buf,
1342 		    &accum_size, max_size);
1343 		if (!cached)
1344 			free(delta_buf);
1345 		n++;
1346 		if (err)
1347 			goto done;
1348 
1349 		if (n < deltas->nentries) {
1350 			/* Accumulated delta becomes the new base. */
1351 			uint8_t *tmp = accum_buf;
1352 			/*
1353 			 * Base buffer switches roles with accumulation buffer.
1354 			 * Ensure it can hold the largest result in the delta
1355 			 * chain. Initial allocation might have been smaller.
1356 			 */
1357 			if (base_bufsz < max_size) {
1358 				uint8_t *p;
1359 				p = reallocarray(base_buf, 1, max_size);
1360 				if (p == NULL) {
1361 					err = got_error_from_errno(
1362 					    "reallocarray");
1363 					goto done;
1364 				}
1365 				base_buf = p;
1366 				base_bufsz = max_size;
1367 			}
1368 			accum_buf = base_buf;
1369 			base_buf = tmp;
1370 		}
1371 	}
1372 
1373 done:
1374 	free(base_buf);
1375 	if (err) {
1376 		free(accum_buf);
1377 		*outbuf = NULL;
1378 		*outlen = 0;
1379 	} else {
1380 		*outbuf = accum_buf;
1381 		*outlen = accum_size;
1382 	}
1383 	return err;
1384 }
1385 
1386 const struct got_error *
1387 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1388     FILE *outfile, FILE *base_file, FILE *accum_file)
1389 {
1390 	const struct got_error *err = NULL;
1391 
1392 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1393 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1394 
1395 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1396 		if (obj->pack_offset >= pack->filesize)
1397 			return got_error(GOT_ERR_PACK_OFFSET);
1398 
1399 		if (pack->map) {
1400 			size_t mapoff = (size_t)obj->pack_offset;
1401 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1402 			    pack->map, mapoff, pack->filesize - mapoff,
1403 			    outfile);
1404 		} else {
1405 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1406 				return got_error_from_errno("lseek");
1407 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1408 			    pack->fd, outfile);
1409 		}
1410 	} else
1411 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1412 		    &obj->deltas, pack, outfile, base_file, accum_file);
1413 
1414 	return err;
1415 }
1416 
1417 const struct got_error *
1418 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1419     struct got_object *obj, struct got_pack *pack)
1420 {
1421 	const struct got_error *err = NULL;
1422 
1423 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1424 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1425 
1426 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1427 		if (obj->pack_offset >= pack->filesize)
1428 			return got_error(GOT_ERR_PACK_OFFSET);
1429 		if (pack->map) {
1430 			size_t mapoff = (size_t)obj->pack_offset;
1431 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1432 			    pack->map, mapoff, pack->filesize - mapoff);
1433 		} else {
1434 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1435 				return got_error_from_errno("lseek");
1436 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1437 			    obj->size, pack->fd);
1438 		}
1439 	} else
1440 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1441 		    pack);
1442 
1443 	return err;
1444 }