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 | O_CLOEXEC);
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,
485     struct got_object_id *id)
486 {
487 	u_int8_t id0 = id->sha1[0];
488 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
489 	int left = 0, right = totobj - 1;
490 
491 	if (id0 > 0)
492 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
493 
494 	while (left <= right) {
495 		struct got_packidx_object_id *oid;
496 		int i, cmp;
497 
498 		i = ((left + right) / 2);
499 		oid = &packidx->hdr.sorted_ids[i];
500 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
501 		if (cmp == 0)
502 			return i;
503 		else if (cmp > 0)
504 			left = i + 1;
505 		else if (cmp < 0)
506 			right = i - 1;
507 	}
508 
509 	return -1;
510 }
511 
512 const struct got_error *
513 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
514     struct got_packidx *packidx, const char *id_str_prefix)
515 {
516 	const struct got_error *err = NULL;
517 	u_int8_t id0;
518 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
519 	char hex[3];
520 	size_t prefix_len = strlen(id_str_prefix);
521 	struct got_packidx_object_id *oid;
522 	uint32_t i = 0;
523 
524 	STAILQ_INIT(matched_ids);
525 
526 	if (prefix_len < 2)
527 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
528 
529 	hex[0] = id_str_prefix[0];
530 	hex[1] = id_str_prefix[1];
531 	hex[2] = '\0';
532 	if (!got_parse_xdigit(&id0, hex))
533 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
534 
535 	if (id0 > 0)
536 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
537 	oid = &packidx->hdr.sorted_ids[i];
538 	while (i < totobj && oid->sha1[0] == id0) {
539 		char id_str[SHA1_DIGEST_STRING_LENGTH];
540 		struct got_object_qid *qid;
541 		int cmp;
542 
543 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
544 		        return got_error(GOT_ERR_NO_SPACE);
545 
546 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
547 		if (cmp < 0) {
548 			oid = &packidx->hdr.sorted_ids[++i];
549 			continue;
550 		} else if (cmp > 0)
551 			break;
552 
553 		err = got_object_qid_alloc_partial(&qid);
554 		if (err)
555 			break;
556 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
557 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
558 
559 		oid = &packidx->hdr.sorted_ids[++i];
560 	}
561 
562 	if (err)
563 		got_object_id_queue_free(matched_ids);
564 	return err;
565 }
566 
567 static const struct got_error *
568 pack_stop_privsep_child(struct got_pack *pack)
569 {
570 	const struct got_error *err = NULL;
571 
572 	if (pack->privsep_child == NULL)
573 		return NULL;
574 
575 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
576 	if (err)
577 		return err;
578 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
579 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
580 		err = got_error_from_errno("close");
581 	imsg_clear(pack->privsep_child->ibuf);
582 	free(pack->privsep_child->ibuf);
583 	free(pack->privsep_child);
584 	pack->privsep_child = NULL;
585 	return err;
586 }
587 
588 const struct got_error *
589 got_pack_close(struct got_pack *pack)
590 {
591 	const struct got_error *err = NULL;
592 
593 	err = pack_stop_privsep_child(pack);
594 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
595 		err = got_error_from_errno("munmap");
596 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
597 		err = got_error_from_errno("close");
598 	pack->fd = -1;
599 	free(pack->path_packfile);
600 	pack->path_packfile = NULL;
601 	pack->filesize = 0;
602 	if (pack->delta_cache) {
603 		got_delta_cache_free(pack->delta_cache);
604 		pack->delta_cache = NULL;
605 	}
606 
607 	return err;
608 }
609 
610 const struct got_error *
611 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
612     struct got_pack *pack, off_t offset)
613 {
614 	uint8_t t = 0;
615 	uint64_t s = 0;
616 	uint8_t sizeN;
617 	size_t mapoff = 0;
618 	int i = 0;
619 
620 	*len = 0;
621 
622 	if (offset >= pack->filesize)
623 		return got_error(GOT_ERR_PACK_OFFSET);
624 
625 	if (pack->map) {
626 		mapoff = (size_t)offset;
627 	} else {
628 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
629 			return got_error_from_errno("lseek");
630 	}
631 
632 	do {
633 		/* We do not support size values which don't fit in 64 bit. */
634 		if (i > 9)
635 			return got_error(GOT_ERR_NO_SPACE);
636 
637 		if (pack->map) {
638 			sizeN = *(pack->map + mapoff);
639 			mapoff += sizeof(sizeN);
640 		} else {
641 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
642 			if (n < 0)
643 				return got_error_from_errno("read");
644 			if (n != sizeof(sizeN))
645 				return got_error(GOT_ERR_BAD_PACKFILE);
646 		}
647 		*len += sizeof(sizeN);
648 
649 		if (i == 0) {
650 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
651 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
652 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
653 		} else {
654 			size_t shift = 4 + 7 * (i - 1);
655 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
656 		}
657 		i++;
658 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
659 
660 	*type = t;
661 	*size = s;
662 	return NULL;
663 }
664 
665 static const struct got_error *
666 open_plain_object(struct got_object **obj, struct got_object_id *id,
667     uint8_t type, off_t offset, size_t size, int idx)
668 {
669 	*obj = calloc(1, sizeof(**obj));
670 	if (*obj == NULL)
671 		return got_error_from_errno("calloc");
672 
673 	(*obj)->type = type;
674 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
675 	(*obj)->pack_idx = idx;
676 	(*obj)->hdrlen = 0;
677 	(*obj)->size = size;
678 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
679 	(*obj)->pack_offset = offset;
680 
681 	return NULL;
682 }
683 
684 static const struct got_error *
685 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
686     off_t delta_offset)
687 {
688 	int64_t o = 0;
689 	uint8_t offN;
690 	int i = 0;
691 
692 	*offset = 0;
693 	*len = 0;
694 
695 	do {
696 		/* We do not support offset values which don't fit in 64 bit. */
697 		if (i > 8)
698 			return got_error(GOT_ERR_NO_SPACE);
699 
700 		if (pack->map) {
701 			size_t mapoff;
702 			if (delta_offset >= pack->filesize)
703 				return got_error(GOT_ERR_PACK_OFFSET);
704 			mapoff = (size_t)delta_offset + *len;
705 			offN = *(pack->map + mapoff);
706 		} else {
707 			ssize_t n;
708 			n = read(pack->fd, &offN, sizeof(offN));
709 			if (n < 0)
710 				return got_error_from_errno("read");
711 			if (n != sizeof(offN))
712 				return got_error(GOT_ERR_BAD_PACKFILE);
713 		}
714 		*len += sizeof(offN);
715 
716 		if (i == 0)
717 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
718 		else {
719 			o++;
720 			o <<= 7;
721 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
722 		}
723 		i++;
724 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
725 
726 	*offset = o;
727 	return NULL;
728 }
729 
730 const struct got_error *
731 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
732     struct got_pack *pack, off_t offset, int tslen)
733 {
734 	const struct got_error *err;
735 	int64_t negoffset;
736 	size_t negofflen;
737 
738 	*len = 0;
739 
740 	err = parse_negative_offset(&negoffset, &negofflen, pack,
741 	    offset + tslen);
742 	if (err)
743 		return err;
744 
745 	/* Compute the base object's offset (must be in the same pack file). */
746 	*base_offset = (offset - negoffset);
747 	if (*base_offset <= 0)
748 		return got_error(GOT_ERR_BAD_PACKFILE);
749 
750 	*len = negofflen;
751 	return NULL;
752 }
753 
754 static const struct got_error *
755 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
756     size_t delta_data_offset, struct got_pack *pack)
757 {
758 	const struct got_error *err = NULL;
759 
760 	if (pack->map) {
761 		if (delta_data_offset >= pack->filesize)
762 			return got_error(GOT_ERR_PACK_OFFSET);
763 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
764 		    NULL, NULL, pack->map, delta_data_offset,
765 		    pack->filesize - delta_data_offset);
766 	} else {
767 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
768 			return got_error_from_errno("lseek");
769 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
770 		    NULL, 0, pack->fd);
771 	}
772 	return err;
773 }
774 
775 static const struct got_error *
776 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
777     int delta_type, size_t delta_size, size_t delta_data_offset)
778 {
779 	struct got_delta *delta;
780 
781 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
782 	    delta_data_offset);
783 	if (delta == NULL)
784 		return got_error_from_errno("got_delta_open");
785 	/* delta is freed in got_object_close() */
786 	deltas->nentries++;
787 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
788 	return NULL;
789 }
790 
791 static const struct got_error *
792 resolve_offset_delta(struct got_delta_chain *deltas,
793     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
794     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
795 
796 {
797 	const struct got_error *err;
798 	off_t base_offset;
799 	uint8_t base_type;
800 	uint64_t base_size;
801 	size_t base_tslen;
802 	off_t delta_data_offset;
803 	size_t consumed;
804 
805 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
806 	    delta_offset, tslen);
807 	if (err)
808 		return err;
809 
810 	delta_data_offset = delta_offset + tslen + consumed;
811 	if (delta_data_offset >= pack->filesize)
812 		return got_error(GOT_ERR_PACK_OFFSET);
813 
814 	if (pack->map == NULL) {
815 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
816 		if (delta_data_offset == -1)
817 			return got_error_from_errno("lseek");
818 	}
819 
820 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
821 	    delta_data_offset);
822 	if (err)
823 		return err;
824 
825 	/* An offset delta must be in the same packfile. */
826 	if (base_offset >= pack->filesize)
827 		return got_error(GOT_ERR_PACK_OFFSET);
828 
829 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
830 	    &base_tslen, pack, base_offset);
831 	if (err)
832 		return err;
833 
834 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
835 	    base_tslen, base_type, base_size, recursion - 1);
836 }
837 
838 const struct got_error *
839 got_pack_parse_ref_delta(struct got_object_id *id,
840     struct got_pack *pack, off_t delta_offset, int tslen)
841 {
842 	if (pack->map) {
843 		size_t mapoff = delta_offset + tslen;
844 		memcpy(id, pack->map + mapoff, sizeof(*id));
845 	} else {
846 		ssize_t n;
847 		n = read(pack->fd, id, sizeof(*id));
848 		if (n < 0)
849 			return got_error_from_errno("read");
850 		if (n != sizeof(*id))
851 			return got_error(GOT_ERR_BAD_PACKFILE);
852 	}
853 
854 	return NULL;
855 }
856 
857 static const struct got_error *
858 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
859     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
860     size_t delta_size, unsigned int recursion)
861 {
862 	const struct got_error *err;
863 	struct got_object_id id;
864 	int idx;
865 	off_t base_offset;
866 	uint8_t base_type;
867 	uint64_t base_size;
868 	size_t base_tslen;
869 	off_t delta_data_offset;
870 
871 	if (delta_offset + tslen >= pack->filesize)
872 		return got_error(GOT_ERR_PACK_OFFSET);
873 
874 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
875 	if (err)
876 		return err;
877 	if (pack->map) {
878 		delta_data_offset = delta_offset + tslen + sizeof(id);
879 	} else {
880 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
881 		if (delta_data_offset == -1)
882 			return got_error_from_errno("lseek");
883 	}
884 
885 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
886 	    delta_data_offset);
887 	if (err)
888 		return err;
889 
890 	/* Delta base must be in the same pack file. */
891 	idx = got_packidx_get_object_idx(packidx, &id);
892 	if (idx == -1)
893 		return got_error(GOT_ERR_NO_OBJ);
894 
895 	base_offset = got_packidx_get_object_offset(packidx, idx);
896 	if (base_offset == (uint64_t)-1)
897 		return got_error(GOT_ERR_BAD_PACKIDX);
898 
899 	if (base_offset >= pack->filesize)
900 		return got_error(GOT_ERR_PACK_OFFSET);
901 
902 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
903 	    &base_tslen, pack, base_offset);
904 	if (err)
905 		return err;
906 
907 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
908 	    base_tslen, base_type, base_size, recursion - 1);
909 }
910 
911 const struct got_error *
912 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
913     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
914     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
915 {
916 	const struct got_error *err = NULL;
917 
918 	if (--recursion == 0)
919 		return got_error(GOT_ERR_RECURSION);
920 
921 	switch (delta_type) {
922 	case GOT_OBJ_TYPE_COMMIT:
923 	case GOT_OBJ_TYPE_TREE:
924 	case GOT_OBJ_TYPE_BLOB:
925 	case GOT_OBJ_TYPE_TAG:
926 		/* Plain types are the final delta base. Recursion ends. */
927 		err = add_delta(deltas, delta_offset, tslen, delta_type,
928 		    delta_size, 0);
929 		break;
930 	case GOT_OBJ_TYPE_OFFSET_DELTA:
931 		err = resolve_offset_delta(deltas, packidx, pack,
932 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
933 		break;
934 	case GOT_OBJ_TYPE_REF_DELTA:
935 		err = resolve_ref_delta(deltas, packidx, pack,
936 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
937 		break;
938 	default:
939 		return got_error(GOT_ERR_OBJ_TYPE);
940 	}
941 
942 	return err;
943 }
944 
945 static const struct got_error *
946 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
947     struct got_pack *pack, struct got_object_id *id, off_t offset,
948     size_t tslen, int delta_type, size_t delta_size, int idx)
949 {
950 	const struct got_error *err = NULL;
951 	int resolved_type;
952 
953 	*obj = calloc(1, sizeof(**obj));
954 	if (*obj == NULL)
955 		return got_error_from_errno("calloc");
956 
957 	(*obj)->flags = 0;
958 	(*obj)->hdrlen = 0;
959 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
960 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
961 	(*obj)->pack_offset = offset + tslen;
962 
963 	STAILQ_INIT(&(*obj)->deltas.entries);
964 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
965 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
966 	(*obj)->pack_idx = idx;
967 
968 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
969 	    offset, tslen, delta_type, delta_size,
970 	    GOT_DELTA_CHAIN_RECURSION_MAX);
971 	if (err)
972 		goto done;
973 
974 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
975 	if (err)
976 		goto done;
977 	(*obj)->type = resolved_type;
978 done:
979 	if (err) {
980 		got_object_close(*obj);
981 		*obj = NULL;
982 	}
983 	return err;
984 }
985 
986 const struct got_error *
987 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
988     struct got_packidx *packidx, int idx, struct got_object_id *id)
989 {
990 	const struct got_error *err = NULL;
991 	off_t offset;
992 	uint8_t type;
993 	uint64_t size;
994 	size_t tslen;
995 
996 	*obj = NULL;
997 
998 	offset = got_packidx_get_object_offset(packidx, idx);
999 	if (offset == (uint64_t)-1)
1000 		return got_error(GOT_ERR_BAD_PACKIDX);
1001 
1002 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1003 	    pack, offset);
1004 	if (err)
1005 		return err;
1006 
1007 	switch (type) {
1008 	case GOT_OBJ_TYPE_COMMIT:
1009 	case GOT_OBJ_TYPE_TREE:
1010 	case GOT_OBJ_TYPE_BLOB:
1011 	case GOT_OBJ_TYPE_TAG:
1012 		err = open_plain_object(obj, id, type, offset + tslen,
1013 		    size, idx);
1014 		break;
1015 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1016 	case GOT_OBJ_TYPE_REF_DELTA:
1017 		err = open_delta_object(obj, packidx, pack, id, offset,
1018 		    tslen, type, size, idx);
1019 		break;
1020 	default:
1021 		err = got_error(GOT_ERR_OBJ_TYPE);
1022 		break;
1023 	}
1024 
1025 	return err;
1026 }
1027 
1028 const struct got_error *
1029 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1030     struct got_delta_chain *deltas, struct got_pack *pack)
1031 {
1032 	struct got_delta *delta;
1033 	uint64_t base_size = 0, result_size = 0;
1034 
1035 	*max_size = 0;
1036 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1037 		/* Plain object types are the delta base. */
1038 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1039 		    delta->type != GOT_OBJ_TYPE_TREE &&
1040 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1041 		    delta->type != GOT_OBJ_TYPE_TAG) {
1042 			const struct got_error *err;
1043 			uint8_t *delta_buf;
1044 			size_t delta_len;
1045 			int cached = 1;
1046 
1047 			got_delta_cache_get(&delta_buf, &delta_len,
1048 			    pack->delta_cache, delta->data_offset);
1049 			if (delta_buf == NULL) {
1050 				cached = 0;
1051 				err = read_delta_data(&delta_buf, &delta_len,
1052 				    delta->data_offset, pack);
1053 				if (err)
1054 					return err;
1055 				err = got_delta_cache_add(pack->delta_cache,
1056 				    delta->data_offset, delta_buf, delta_len);
1057 				if (err == NULL)
1058 					cached = 1;
1059 				else if (err->code != GOT_ERR_NO_SPACE) {
1060 					free(delta_buf);
1061 					return err;
1062 				}
1063 			}
1064 			err = got_delta_get_sizes(&base_size, &result_size,
1065 			    delta_buf, delta_len);
1066 			if (!cached)
1067 				free(delta_buf);
1068 			if (err)
1069 				return err;
1070 		} else
1071 			base_size = delta->size;
1072 		if (base_size > *max_size)
1073 			*max_size = base_size;
1074 		if (result_size > *max_size)
1075 			*max_size = result_size;
1076 	}
1077 
1078 	return NULL;
1079 }
1080 
1081 const struct got_error *
1082 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1083     struct got_pack *pack)
1084 {
1085 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1086 		return got_error(GOT_ERR_OBJ_TYPE);
1087 
1088 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1089 }
1090 
1091 const struct got_error *
1092 got_pack_dump_delta_chain_to_file(size_t *result_size,
1093     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1094     FILE *base_file, FILE *accum_file)
1095 {
1096 	const struct got_error *err = NULL;
1097 	struct got_delta *delta;
1098 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1099 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1100 	uint64_t max_size;
1101 	int n = 0;
1102 
1103 	*result_size = 0;
1104 
1105 	if (STAILQ_EMPTY(&deltas->entries))
1106 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1107 
1108 	/* We process small enough files entirely in memory for speed. */
1109 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1110 	if (err)
1111 		return err;
1112 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1113 		accum_buf = malloc(max_size);
1114 		if (accum_buf == NULL)
1115 			return got_error_from_errno("malloc");
1116 		base_file = NULL;
1117 		accum_file = NULL;
1118 	}
1119 
1120 	/* Deltas are ordered in ascending order. */
1121 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1122 		int cached = 1;
1123 		if (n == 0) {
1124 			size_t mapoff;
1125 			off_t delta_data_offset;
1126 
1127 			/* Plain object types are the delta base. */
1128 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1129 			    delta->type != GOT_OBJ_TYPE_TREE &&
1130 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1131 			    delta->type != GOT_OBJ_TYPE_TAG) {
1132 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1133 				goto done;
1134 			}
1135 
1136 			delta_data_offset = delta->offset + delta->tslen;
1137 			if (delta_data_offset >= pack->filesize) {
1138 				err = got_error(GOT_ERR_PACK_OFFSET);
1139 				goto done;
1140 			}
1141 			if (pack->map == NULL) {
1142 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1143 				    == -1) {
1144 					err = got_error_from_errno("lseek");
1145 					goto done;
1146 				}
1147 			}
1148 			if (base_file) {
1149 				if (pack->map) {
1150 					mapoff = (size_t)delta_data_offset;
1151 					err = got_inflate_to_file_mmap(
1152 					    &base_bufsz, NULL, NULL, pack->map,
1153 					    mapoff, pack->filesize - mapoff,
1154 					    base_file);
1155 				} else
1156 					err = got_inflate_to_file_fd(
1157 					    &base_bufsz, NULL, NULL, pack->fd,
1158 					    base_file);
1159 			} else {
1160 				if (pack->map) {
1161 					mapoff = (size_t)delta_data_offset;
1162 					err = got_inflate_to_mem_mmap(&base_buf,
1163 					    &base_bufsz, NULL, NULL,
1164 					    pack->map, mapoff,
1165 					    pack->filesize - mapoff);
1166 				} else
1167 					err = got_inflate_to_mem_fd(&base_buf,
1168 					    &base_bufsz, NULL, NULL, max_size,
1169 					    pack->fd);
1170 			}
1171 			if (err)
1172 				goto done;
1173 			n++;
1174 			if (base_file)
1175 				rewind(base_file);
1176 			continue;
1177 		}
1178 
1179 		got_delta_cache_get(&delta_buf, &delta_len,
1180 		    pack->delta_cache, delta->data_offset);
1181 		if (delta_buf == NULL) {
1182 			cached = 0;
1183 			err = read_delta_data(&delta_buf, &delta_len,
1184 			    delta->data_offset, pack);
1185 			if (err)
1186 				goto done;
1187 			err = got_delta_cache_add(pack->delta_cache,
1188 			    delta->data_offset, delta_buf, delta_len);
1189 			if (err == NULL)
1190 				cached = 1;
1191 			else if (err->code != GOT_ERR_NO_SPACE) {
1192 				free(delta_buf);
1193 				goto done;
1194 			}
1195 		}
1196 		if (base_buf) {
1197 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1198 			    delta_buf, delta_len, accum_buf,
1199 			    &accum_size, max_size);
1200 			n++;
1201 		} else {
1202 			err = got_delta_apply(base_file, delta_buf,
1203 			    delta_len,
1204 			    /* Final delta application writes to output file. */
1205 			    ++n < deltas->nentries ? accum_file : outfile,
1206 			    &accum_size);
1207 		}
1208 		if (!cached)
1209 			free(delta_buf);
1210 		if (err)
1211 			goto done;
1212 
1213 		if (n < deltas->nentries) {
1214 			/* Accumulated delta becomes the new base. */
1215 			if (base_buf) {
1216 				uint8_t *tmp = accum_buf;
1217 				/*
1218 				 * Base buffer switches roles with accumulation
1219 				 * buffer. Ensure it can hold the largest
1220 				 * result in the delta chain. The initial
1221 				 * allocation might have been smaller.
1222 				 */
1223 				if (base_bufsz < max_size) {
1224 					uint8_t *p;
1225 					p = reallocarray(base_buf, 1, max_size);
1226 					if (p == NULL) {
1227 						err = got_error_from_errno(
1228 						    "reallocarray");
1229 						goto done;
1230 					}
1231 					base_buf = p;
1232 					base_bufsz = max_size;
1233 				}
1234 				accum_buf = base_buf;
1235 				base_buf = tmp;
1236 			} else {
1237 				FILE *tmp = accum_file;
1238 				accum_file = base_file;
1239 				base_file = tmp;
1240 				rewind(base_file);
1241 				rewind(accum_file);
1242 			}
1243 		}
1244 	}
1245 
1246 done:
1247 	free(base_buf);
1248 	if (accum_buf) {
1249 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1250 		free(accum_buf);
1251 		if (len != accum_size)
1252 			err = got_ferror(outfile, GOT_ERR_IO);
1253 	}
1254 	rewind(outfile);
1255 	if (err == NULL)
1256 		*result_size = accum_size;
1257 	return err;
1258 }
1259 
1260 const struct got_error *
1261 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1262     struct got_delta_chain *deltas, struct got_pack *pack)
1263 {
1264 	const struct got_error *err = NULL;
1265 	struct got_delta *delta;
1266 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1267 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1268 	uint64_t max_size;
1269 	int n = 0;
1270 
1271 	*outbuf = NULL;
1272 	*outlen = 0;
1273 
1274 	if (STAILQ_EMPTY(&deltas->entries))
1275 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1276 
1277 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1278 	if (err)
1279 		return err;
1280 	accum_buf = malloc(max_size);
1281 	if (accum_buf == NULL)
1282 		return got_error_from_errno("malloc");
1283 
1284 	/* Deltas are ordered in ascending order. */
1285 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1286 		int cached = 1;
1287 		if (n == 0) {
1288 			size_t delta_data_offset;
1289 
1290 			/* Plain object types are the delta base. */
1291 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1292 			    delta->type != GOT_OBJ_TYPE_TREE &&
1293 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1294 			    delta->type != GOT_OBJ_TYPE_TAG) {
1295 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1296 				goto done;
1297 			}
1298 
1299 			delta_data_offset = delta->offset + delta->tslen;
1300 			if (delta_data_offset >= pack->filesize) {
1301 				err = got_error(GOT_ERR_PACK_OFFSET);
1302 				goto done;
1303 			}
1304 			if (pack->map) {
1305 				size_t mapoff = (size_t)delta_data_offset;
1306 				err = got_inflate_to_mem_mmap(&base_buf,
1307 				    &base_bufsz, NULL, NULL, pack->map,
1308 				    mapoff, pack->filesize - mapoff);
1309 			} else {
1310 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1311 				    == -1) {
1312 					err = got_error_from_errno("lseek");
1313 					goto done;
1314 				}
1315 				err = got_inflate_to_mem_fd(&base_buf,
1316 				    &base_bufsz, NULL, NULL, max_size,
1317 				    pack->fd);
1318 			}
1319 			if (err)
1320 				goto done;
1321 			n++;
1322 			continue;
1323 		}
1324 
1325 		got_delta_cache_get(&delta_buf, &delta_len,
1326 		    pack->delta_cache, delta->data_offset);
1327 		if (delta_buf == NULL) {
1328 			cached = 0;
1329 			err = read_delta_data(&delta_buf, &delta_len,
1330 			    delta->data_offset, pack);
1331 			if (err)
1332 				goto done;
1333 			err = got_delta_cache_add(pack->delta_cache,
1334 			    delta->data_offset, delta_buf, delta_len);
1335 			if (err == NULL)
1336 				cached = 1;
1337 			else if (err->code != GOT_ERR_NO_SPACE) {
1338 				free(delta_buf);
1339 				goto done;
1340 			}
1341 		}
1342 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1343 		    delta_buf, delta_len, accum_buf,
1344 		    &accum_size, max_size);
1345 		if (!cached)
1346 			free(delta_buf);
1347 		n++;
1348 		if (err)
1349 			goto done;
1350 
1351 		if (n < deltas->nentries) {
1352 			/* Accumulated delta becomes the new base. */
1353 			uint8_t *tmp = accum_buf;
1354 			/*
1355 			 * Base buffer switches roles with accumulation buffer.
1356 			 * Ensure it can hold the largest result in the delta
1357 			 * chain. Initial allocation might have been smaller.
1358 			 */
1359 			if (base_bufsz < max_size) {
1360 				uint8_t *p;
1361 				p = reallocarray(base_buf, 1, max_size);
1362 				if (p == NULL) {
1363 					err = got_error_from_errno(
1364 					    "reallocarray");
1365 					goto done;
1366 				}
1367 				base_buf = p;
1368 				base_bufsz = max_size;
1369 			}
1370 			accum_buf = base_buf;
1371 			base_buf = tmp;
1372 		}
1373 	}
1374 
1375 done:
1376 	free(base_buf);
1377 	if (err) {
1378 		free(accum_buf);
1379 		*outbuf = NULL;
1380 		*outlen = 0;
1381 	} else {
1382 		*outbuf = accum_buf;
1383 		*outlen = accum_size;
1384 	}
1385 	return err;
1386 }
1387 
1388 const struct got_error *
1389 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1390     FILE *outfile, FILE *base_file, FILE *accum_file)
1391 {
1392 	const struct got_error *err = NULL;
1393 
1394 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1395 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1396 
1397 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1398 		if (obj->pack_offset >= pack->filesize)
1399 			return got_error(GOT_ERR_PACK_OFFSET);
1400 
1401 		if (pack->map) {
1402 			size_t mapoff = (size_t)obj->pack_offset;
1403 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1404 			    pack->map, mapoff, pack->filesize - mapoff,
1405 			    outfile);
1406 		} else {
1407 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1408 				return got_error_from_errno("lseek");
1409 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1410 			    pack->fd, outfile);
1411 		}
1412 	} else
1413 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1414 		    &obj->deltas, pack, outfile, base_file, accum_file);
1415 
1416 	return err;
1417 }
1418 
1419 const struct got_error *
1420 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1421     struct got_object *obj, struct got_pack *pack)
1422 {
1423 	const struct got_error *err = NULL;
1424 
1425 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1426 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1427 
1428 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1429 		if (obj->pack_offset >= pack->filesize)
1430 			return got_error(GOT_ERR_PACK_OFFSET);
1431 		if (pack->map) {
1432 			size_t mapoff = (size_t)obj->pack_offset;
1433 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1434 			    pack->map, mapoff, pack->filesize - mapoff);
1435 		} else {
1436 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1437 				return got_error_from_errno("lseek");
1438 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1439 			    obj->size, pack->fd);
1440 		}
1441 	} else
1442 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1443 		    pack);
1444 
1445 	return err;
1446 }