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Date:: Fri Dec 31 09:33:01 2021 UTC
Message:: wrap overlong lines
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1 /*
2  * Copyright (c) 2018, 2019, 2020 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 #include <sys/uio.h>
21 #include <sys/mman.h>
22 
23 #include <fcntl.h>
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdint.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <limits.h>
30 #include <sha1.h>
31 #include <endian.h>
32 #include <unistd.h>
33 #include <zlib.h>
34 #include <imsg.h>
35 
36 #include "got_error.h"
37 #include "got_object.h"
38 #include "got_opentemp.h"
39 #include "got_path.h"
40 
41 #include "got_lib_sha1.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_delta_cache.h"
44 #include "got_lib_inflate.h"
45 #include "got_lib_object.h"
46 #include "got_lib_object_parse.h"
47 #include "got_lib_privsep.h"
48 #include "got_lib_pack.h"
49 
50 #ifndef nitems
51 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
52 #endif
53 
54 #ifndef MIN
55 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
56 #endif
57 
58 static const struct got_error *
59 verify_fanout_table(uint32_t *fanout_table)
60 {
61 	int i;
62 
63 	for (i = 0; i < 0xff - 1; i++) {
64 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
65 			return got_error(GOT_ERR_BAD_PACKIDX);
66 	}
67 
68 	return NULL;
69 }
70 
71 const struct got_error *
72 got_packidx_init_hdr(struct got_packidx *p, int verify, off_t packfile_size)
73 {
74 	const struct got_error *err = NULL;
75 	struct got_packidx_v2_hdr *h;
76 	SHA1_CTX ctx;
77 	uint8_t sha1[SHA1_DIGEST_LENGTH];
78 	size_t nobj, len_fanout, len_ids, offset, remain;
79 	ssize_t n;
80 	int i;
81 
82 	SHA1Init(&ctx);
83 
84 	h = &p->hdr;
85 	offset = 0;
86 	remain = p->len;
87 
88 	if (remain < sizeof(*h->magic)) {
89 		err = got_error(GOT_ERR_BAD_PACKIDX);
90 		goto done;
91 	}
92 	if (p->map)
93 		h->magic = (uint32_t *)(p->map + offset);
94 	else {
95 		h->magic = malloc(sizeof(*h->magic));
96 		if (h->magic == NULL) {
97 			err = got_error_from_errno("malloc");
98 			goto done;
99 		}
100 		n = read(p->fd, h->magic, sizeof(*h->magic));
101 		if (n < 0) {
102 			err = got_error_from_errno("read");
103 			goto done;
104 		} else if (n != sizeof(*h->magic)) {
105 			err = got_error(GOT_ERR_BAD_PACKIDX);
106 			goto done;
107 		}
108 	}
109 	if (*h->magic != htobe32(GOT_PACKIDX_V2_MAGIC)) {
110 		err = got_error(GOT_ERR_BAD_PACKIDX);
111 		goto done;
112 	}
113 	offset += sizeof(*h->magic);
114 	remain -= sizeof(*h->magic);
115 
116 	if (verify)
117 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
118 
119 	if (remain < sizeof(*h->version)) {
120 		err = got_error(GOT_ERR_BAD_PACKIDX);
121 		goto done;
122 	}
123 	if (p->map)
124 		h->version = (uint32_t *)(p->map + offset);
125 	else {
126 		h->version = malloc(sizeof(*h->version));
127 		if (h->version == NULL) {
128 			err = got_error_from_errno("malloc");
129 			goto done;
130 		}
131 		n = read(p->fd, h->version, sizeof(*h->version));
132 		if (n < 0) {
133 			err = got_error_from_errno("read");
134 			goto done;
135 		} else if (n != sizeof(*h->version)) {
136 			err = got_error(GOT_ERR_BAD_PACKIDX);
137 			goto done;
138 		}
139 	}
140 	if (*h->version != htobe32(GOT_PACKIDX_VERSION)) {
141 		err = got_error(GOT_ERR_BAD_PACKIDX);
142 		goto done;
143 	}
144 	offset += sizeof(*h->version);
145 	remain -= sizeof(*h->version);
146 
147 	if (verify)
148 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
149 
150 	len_fanout =
151 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
152 	if (remain < len_fanout) {
153 		err = got_error(GOT_ERR_BAD_PACKIDX);
154 		goto done;
155 	}
156 	if (p->map)
157 		h->fanout_table = (uint32_t *)(p->map + offset);
158 	else {
159 		h->fanout_table = malloc(len_fanout);
160 		if (h->fanout_table == NULL) {
161 			err = got_error_from_errno("malloc");
162 			goto done;
163 		}
164 		n = read(p->fd, h->fanout_table, len_fanout);
165 		if (n < 0) {
166 			err = got_error_from_errno("read");
167 			goto done;
168 		} else if (n != len_fanout) {
169 			err = got_error(GOT_ERR_BAD_PACKIDX);
170 			goto done;
171 		}
172 	}
173 	err = verify_fanout_table(h->fanout_table);
174 	if (err)
175 		goto done;
176 	if (verify)
177 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
178 	offset += len_fanout;
179 	remain -= len_fanout;
180 
181 	nobj = be32toh(h->fanout_table[0xff]);
182 	len_ids = nobj * sizeof(*h->sorted_ids);
183 	if (len_ids <= nobj || len_ids > remain) {
184 		err = got_error(GOT_ERR_BAD_PACKIDX);
185 		goto done;
186 	}
187 	if (p->map)
188 		h->sorted_ids =
189 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
190 	else {
191 		h->sorted_ids = malloc(len_ids);
192 		if (h->sorted_ids == NULL) {
193 			err = got_error(GOT_ERR_BAD_PACKIDX);
194 			goto done;
195 		}
196 		n = read(p->fd, h->sorted_ids, len_ids);
197 		if (n < 0)
198 			err = got_error_from_errno("read");
199 		else if (n != len_ids) {
200 			err = got_error(GOT_ERR_BAD_PACKIDX);
201 			goto done;
202 		}
203 	}
204 	if (verify)
205 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
206 	offset += len_ids;
207 	remain -= len_ids;
208 
209 	if (remain < nobj * sizeof(*h->crc32)) {
210 		err = got_error(GOT_ERR_BAD_PACKIDX);
211 		goto done;
212 	}
213 	if (p->map)
214 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
215 	else {
216 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
217 		if (h->crc32 == NULL) {
218 			err = got_error_from_errno("malloc");
219 			goto done;
220 		}
221 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
222 		if (n < 0)
223 			err = got_error_from_errno("read");
224 		else if (n != nobj * sizeof(*h->crc32)) {
225 			err = got_error(GOT_ERR_BAD_PACKIDX);
226 			goto done;
227 		}
228 	}
229 	if (verify)
230 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
231 	remain -= nobj * sizeof(*h->crc32);
232 	offset += nobj * sizeof(*h->crc32);
233 
234 	if (remain < nobj * sizeof(*h->offsets)) {
235 		err = got_error(GOT_ERR_BAD_PACKIDX);
236 		goto done;
237 	}
238 	if (p->map)
239 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
240 	else {
241 		h->offsets = malloc(nobj * sizeof(*h->offsets));
242 		if (h->offsets == NULL) {
243 			err = got_error_from_errno("malloc");
244 			goto done;
245 		}
246 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
247 		if (n < 0)
248 			err = got_error_from_errno("read");
249 		else if (n != nobj * sizeof(*h->offsets)) {
250 			err = got_error(GOT_ERR_BAD_PACKIDX);
251 			goto done;
252 		}
253 	}
254 	if (verify)
255 		SHA1Update(&ctx, (uint8_t *)h->offsets,
256 		    nobj * sizeof(*h->offsets));
257 	remain -= nobj * sizeof(*h->offsets);
258 	offset += nobj * sizeof(*h->offsets);
259 
260 	/* Large file offsets are contained only in files > 2GB. */
261 	if (verify || packfile_size > 0x7fffffff) {
262 		for (i = 0; i < nobj; i++) {
263 			uint32_t o = h->offsets[i];
264 			if (o & htobe32(GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX))
265 				p->nlargeobj++;
266 		}
267 	}
268 	if (p->nlargeobj == 0)
269 		goto checksum;
270 	else if (packfile_size <= 0x7fffffff) {
271 		err = got_error(GOT_ERR_BAD_PACKIDX);
272 		goto done;
273 	}
274 
275 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
276 		err = got_error(GOT_ERR_BAD_PACKIDX);
277 		goto done;
278 	}
279 	if (p->map)
280 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
281 	else {
282 		h->large_offsets = malloc(p->nlargeobj *
283 		    sizeof(*h->large_offsets));
284 		if (h->large_offsets == NULL) {
285 			err = got_error_from_errno("malloc");
286 			goto done;
287 		}
288 		n = read(p->fd, h->large_offsets,
289 		    p->nlargeobj * sizeof(*h->large_offsets));
290 		if (n < 0)
291 			err = got_error_from_errno("read");
292 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
293 			err = got_error(GOT_ERR_BAD_PACKIDX);
294 			goto done;
295 		}
296 	}
297 	if (verify)
298 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
299 		    p->nlargeobj * sizeof(*h->large_offsets));
300 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
301 	offset += p->nlargeobj * sizeof(*h->large_offsets);
302 
303 checksum:
304 	if (remain < sizeof(*h->trailer)) {
305 		err = got_error(GOT_ERR_BAD_PACKIDX);
306 		goto done;
307 	}
308 	if (p->map)
309 		h->trailer =
310 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
311 	else {
312 		h->trailer = malloc(sizeof(*h->trailer));
313 		if (h->trailer == NULL) {
314 			err = got_error_from_errno("malloc");
315 			goto done;
316 		}
317 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
318 		if (n < 0)
319 			err = got_error_from_errno("read");
320 		else if (n != sizeof(*h->trailer)) {
321 			err = got_error(GOT_ERR_BAD_PACKIDX);
322 			goto done;
323 		}
324 	}
325 	if (verify) {
326 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
327 		SHA1Final(sha1, &ctx);
328 		if (memcmp(h->trailer->packidx_sha1, sha1,
329 		    SHA1_DIGEST_LENGTH) != 0)
330 			err = got_error(GOT_ERR_PACKIDX_CSUM);
331 	}
332 done:
333 	return err;
334 }
335 
336 const struct got_error *
337 got_packidx_open(struct got_packidx **packidx,
338     int dir_fd, const char *relpath, int verify)
339 {
340 	const struct got_error *err = NULL;
341 	struct got_packidx *p = NULL;
342 	char *pack_relpath;
343 	struct stat idx_sb, pack_sb;
344 
345 	*packidx = NULL;
346 
347 	err = got_packidx_get_packfile_path(&pack_relpath, relpath);
348 	if (err)
349 		return err;
350 
351 	/*
352 	 * Ensure that a corresponding pack file exists.
353 	 * Some Git repositories have this problem. Git seems to ignore
354 	 * the existence of lonely pack index files but we do not.
355 	 */
356 	if (fstatat(dir_fd, pack_relpath, &pack_sb, 0) == -1) {
357 		if (errno == ENOENT) {
358 			err = got_error_fmt(GOT_ERR_LONELY_PACKIDX,
359 			    "%s", relpath);
360 		} else
361 			err = got_error_from_errno2("fstatat", pack_relpath);
362 		goto done;
363 	}
364 
365 	p = calloc(1, sizeof(*p));
366 	if (p == NULL) {
367 		err = got_error_from_errno("calloc");
368 		goto done;
369 	}
370 
371 	p->fd = openat(dir_fd, relpath, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
372 	if (p->fd == -1) {
373 		err = got_error_from_errno2("openat", relpath);
374 		free(p);
375 		goto done;
376 	}
377 
378 	if (fstat(p->fd, &idx_sb) != 0) {
379 		err = got_error_from_errno2("fstat", relpath);
380 		close(p->fd);
381 		free(p);
382 		goto done;
383 	}
384 	p->len = idx_sb.st_size;
385 	if (p->len < sizeof(p->hdr)) {
386 		err = got_error(GOT_ERR_BAD_PACKIDX);
387 		close(p->fd);
388 		free(p);
389 		goto done;
390 	}
391 
392 	p->path_packidx = strdup(relpath);
393 	if (p->path_packidx == NULL) {
394 		err = got_error_from_errno("strdup");
395 		goto done;
396 	}
397 
398 #ifndef GOT_PACK_NO_MMAP
399 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
400 	if (p->map == MAP_FAILED) {
401 		if (errno != ENOMEM) {
402 			err = got_error_from_errno("mmap");
403 			goto done;
404 		}
405 		p->map = NULL; /* fall back to read(2) */
406 	}
407 #endif
408 
409 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
410 done:
411 	if (err) {
412 		if (p)
413 			got_packidx_close(p);
414 	} else
415 		*packidx = p;
416 	free(pack_relpath);
417 	return err;
418 }
419 
420 const struct got_error *
421 got_packidx_close(struct got_packidx *packidx)
422 {
423 	const struct got_error *err = NULL;
424 
425 	free(packidx->path_packidx);
426 	if (packidx->map) {
427 		if (munmap(packidx->map, packidx->len) == -1)
428 			err = got_error_from_errno("munmap");
429 	} else {
430 		free(packidx->hdr.magic);
431 		free(packidx->hdr.version);
432 		free(packidx->hdr.fanout_table);
433 		free(packidx->hdr.sorted_ids);
434 		free(packidx->hdr.crc32);
435 		free(packidx->hdr.offsets);
436 		free(packidx->hdr.large_offsets);
437 		free(packidx->hdr.trailer);
438 	}
439 	if (close(packidx->fd) == -1 && err == NULL)
440 		err = got_error_from_errno("close");
441 	free(packidx);
442 
443 	return err;
444 }
445 
446 const struct got_error *
447 got_packidx_get_packfile_path(char **path_packfile, const char *path_packidx)
448 {
449 	size_t size;
450 
451 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
452 	size = strlen(path_packidx) + 2;
453 	if (size < GOT_PACKFILE_NAMELEN + 1)
454 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
455 
456 	*path_packfile = malloc(size);
457 	if (*path_packfile == NULL)
458 		return got_error_from_errno("malloc");
459 
460 	/* Copy up to and excluding ".idx". */
461 	if (strlcpy(*path_packfile, path_packidx,
462 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
463 		return got_error(GOT_ERR_NO_SPACE);
464 
465 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
466 		return got_error(GOT_ERR_NO_SPACE);
467 
468 	return NULL;
469 }
470 
471 off_t
472 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
473 {
474 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
475 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
476 		uint64_t loffset;
477 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
478 		if (idx < 0 || idx >= packidx->nlargeobj ||
479 		    packidx->hdr.large_offsets == NULL)
480 			return -1;
481 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
482 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
483 	}
484 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
485 }
486 
487 int
488 got_packidx_get_object_idx(struct got_packidx *packidx,
489     struct got_object_id *id)
490 {
491 	u_int8_t id0 = id->sha1[0];
492 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
493 	int left = 0, right = totobj - 1;
494 
495 	if (id0 > 0)
496 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
497 
498 	while (left <= right) {
499 		struct got_packidx_object_id *oid;
500 		int i, cmp;
501 
502 		i = ((left + right) / 2);
503 		oid = &packidx->hdr.sorted_ids[i];
504 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
505 		if (cmp == 0)
506 			return i;
507 		else if (cmp > 0)
508 			left = i + 1;
509 		else if (cmp < 0)
510 			right = i - 1;
511 	}
512 
513 	return -1;
514 }
515 
516 const struct got_error *
517 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
518     struct got_packidx *packidx, const char *id_str_prefix)
519 {
520 	const struct got_error *err = NULL;
521 	u_int8_t id0;
522 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
523 	char hex[3];
524 	size_t prefix_len = strlen(id_str_prefix);
525 	struct got_packidx_object_id *oid;
526 	uint32_t i;
527 
528 	STAILQ_INIT(matched_ids);
529 
530 	if (prefix_len < 2)
531 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
532 
533 	hex[0] = id_str_prefix[0];
534 	hex[1] = id_str_prefix[1];
535 	hex[2] = '\0';
536 	if (!got_parse_xdigit(&id0, hex))
537 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
538 
539 	i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
540 	oid = &packidx->hdr.sorted_ids[i];
541 	while (i < totobj && oid->sha1[0] == id0) {
542 		char id_str[SHA1_DIGEST_STRING_LENGTH];
543 		struct got_object_qid *qid;
544 		int cmp;
545 
546 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
547 		        return got_error(GOT_ERR_NO_SPACE);
548 
549 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
550 		if (cmp < 0) {
551 			oid = &packidx->hdr.sorted_ids[++i];
552 			continue;
553 		} else if (cmp > 0)
554 			break;
555 
556 		err = got_object_qid_alloc_partial(&qid);
557 		if (err)
558 			break;
559 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
560 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
561 
562 		oid = &packidx->hdr.sorted_ids[++i];
563 	}
564 
565 	if (err)
566 		got_object_id_queue_free(matched_ids);
567 	return err;
568 }
569 
570 static const struct got_error *
571 pack_stop_privsep_child(struct got_pack *pack)
572 {
573 	const struct got_error *err = NULL;
574 
575 	if (pack->privsep_child == NULL)
576 		return NULL;
577 
578 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
579 	if (err)
580 		return err;
581 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
582 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
583 		err = got_error_from_errno("close");
584 	imsg_clear(pack->privsep_child->ibuf);
585 	free(pack->privsep_child->ibuf);
586 	free(pack->privsep_child);
587 	pack->privsep_child = NULL;
588 	return err;
589 }
590 
591 const struct got_error *
592 got_pack_close(struct got_pack *pack)
593 {
594 	const struct got_error *err = NULL;
595 
596 	err = pack_stop_privsep_child(pack);
597 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
598 		err = got_error_from_errno("munmap");
599 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
600 		err = got_error_from_errno("close");
601 	pack->fd = -1;
602 	free(pack->path_packfile);
603 	pack->path_packfile = NULL;
604 	pack->filesize = 0;
605 	if (pack->delta_cache) {
606 		got_delta_cache_free(pack->delta_cache);
607 		pack->delta_cache = NULL;
608 	}
609 
610 	return err;
611 }
612 
613 const struct got_error *
614 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
615     struct got_pack *pack, off_t offset)
616 {
617 	uint8_t t = 0;
618 	uint64_t s = 0;
619 	uint8_t sizeN;
620 	size_t mapoff = 0;
621 	int i = 0;
622 
623 	*len = 0;
624 
625 	if (offset >= pack->filesize)
626 		return got_error(GOT_ERR_PACK_OFFSET);
627 
628 	if (pack->map) {
629 		mapoff = (size_t)offset;
630 	} else {
631 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
632 			return got_error_from_errno("lseek");
633 	}
634 
635 	do {
636 		/* We do not support size values which don't fit in 64 bit. */
637 		if (i > 9)
638 			return got_error(GOT_ERR_NO_SPACE);
639 
640 		if (pack->map) {
641 			sizeN = *(pack->map + mapoff);
642 			mapoff += sizeof(sizeN);
643 		} else {
644 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
645 			if (n < 0)
646 				return got_error_from_errno("read");
647 			if (n != sizeof(sizeN))
648 				return got_error(GOT_ERR_BAD_PACKFILE);
649 		}
650 		*len += sizeof(sizeN);
651 
652 		if (i == 0) {
653 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
654 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
655 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
656 		} else {
657 			size_t shift = 4 + 7 * (i - 1);
658 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
659 		}
660 		i++;
661 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
662 
663 	*type = t;
664 	*size = s;
665 	return NULL;
666 }
667 
668 static const struct got_error *
669 open_plain_object(struct got_object **obj, struct got_object_id *id,
670     uint8_t type, off_t offset, size_t size, int idx)
671 {
672 	*obj = calloc(1, sizeof(**obj));
673 	if (*obj == NULL)
674 		return got_error_from_errno("calloc");
675 
676 	(*obj)->type = type;
677 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
678 	(*obj)->pack_idx = idx;
679 	(*obj)->hdrlen = 0;
680 	(*obj)->size = size;
681 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
682 	(*obj)->pack_offset = offset;
683 
684 	return NULL;
685 }
686 
687 static const struct got_error *
688 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
689     off_t delta_offset)
690 {
691 	int64_t o = 0;
692 	uint8_t offN;
693 	int i = 0;
694 
695 	*offset = 0;
696 	*len = 0;
697 
698 	do {
699 		/* We do not support offset values which don't fit in 64 bit. */
700 		if (i > 8)
701 			return got_error(GOT_ERR_NO_SPACE);
702 
703 		if (pack->map) {
704 			size_t mapoff;
705 			if (delta_offset >= pack->filesize)
706 				return got_error(GOT_ERR_PACK_OFFSET);
707 			mapoff = (size_t)delta_offset + *len;
708 			offN = *(pack->map + mapoff);
709 		} else {
710 			ssize_t n;
711 			n = read(pack->fd, &offN, sizeof(offN));
712 			if (n < 0)
713 				return got_error_from_errno("read");
714 			if (n != sizeof(offN))
715 				return got_error(GOT_ERR_BAD_PACKFILE);
716 		}
717 		*len += sizeof(offN);
718 
719 		if (i == 0)
720 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
721 		else {
722 			o++;
723 			o <<= 7;
724 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
725 		}
726 		i++;
727 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
728 
729 	*offset = o;
730 	return NULL;
731 }
732 
733 const struct got_error *
734 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
735     struct got_pack *pack, off_t offset, int tslen)
736 {
737 	const struct got_error *err;
738 	int64_t negoffset;
739 	size_t negofflen;
740 
741 	*len = 0;
742 
743 	err = parse_negative_offset(&negoffset, &negofflen, pack,
744 	    offset + tslen);
745 	if (err)
746 		return err;
747 
748 	/* Compute the base object's offset (must be in the same pack file). */
749 	*base_offset = (offset - negoffset);
750 	if (*base_offset <= 0)
751 		return got_error(GOT_ERR_BAD_PACKFILE);
752 
753 	*len = negofflen;
754 	return NULL;
755 }
756 
757 static const struct got_error *
758 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
759     size_t delta_data_offset, struct got_pack *pack)
760 {
761 	const struct got_error *err = NULL;
762 
763 	if (pack->map) {
764 		if (delta_data_offset >= pack->filesize)
765 			return got_error(GOT_ERR_PACK_OFFSET);
766 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
767 		    NULL, NULL, pack->map, delta_data_offset,
768 		    pack->filesize - delta_data_offset);
769 	} else {
770 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
771 			return got_error_from_errno("lseek");
772 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
773 		    NULL, 0, pack->fd);
774 	}
775 	return err;
776 }
777 
778 static const struct got_error *
779 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
780     int delta_type, size_t delta_size, size_t delta_data_offset)
781 {
782 	struct got_delta *delta;
783 
784 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
785 	    delta_data_offset);
786 	if (delta == NULL)
787 		return got_error_from_errno("got_delta_open");
788 	/* delta is freed in got_object_close() */
789 	deltas->nentries++;
790 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
791 	return NULL;
792 }
793 
794 static const struct got_error *
795 resolve_offset_delta(struct got_delta_chain *deltas,
796     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
797     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
798 
799 {
800 	const struct got_error *err;
801 	off_t base_offset;
802 	uint8_t base_type;
803 	uint64_t base_size;
804 	size_t base_tslen;
805 	off_t delta_data_offset;
806 	size_t consumed;
807 
808 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
809 	    delta_offset, tslen);
810 	if (err)
811 		return err;
812 
813 	delta_data_offset = delta_offset + tslen + consumed;
814 	if (delta_data_offset >= pack->filesize)
815 		return got_error(GOT_ERR_PACK_OFFSET);
816 
817 	if (pack->map == NULL) {
818 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
819 		if (delta_data_offset == -1)
820 			return got_error_from_errno("lseek");
821 	}
822 
823 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
824 	    delta_data_offset);
825 	if (err)
826 		return err;
827 
828 	/* An offset delta must be in the same packfile. */
829 	if (base_offset >= pack->filesize)
830 		return got_error(GOT_ERR_PACK_OFFSET);
831 
832 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
833 	    &base_tslen, pack, base_offset);
834 	if (err)
835 		return err;
836 
837 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
838 	    base_tslen, base_type, base_size, recursion - 1);
839 }
840 
841 const struct got_error *
842 got_pack_parse_ref_delta(struct got_object_id *id,
843     struct got_pack *pack, off_t delta_offset, int tslen)
844 {
845 	if (pack->map) {
846 		size_t mapoff = delta_offset + tslen;
847 		memcpy(id, pack->map + mapoff, sizeof(*id));
848 	} else {
849 		ssize_t n;
850 		n = read(pack->fd, id, sizeof(*id));
851 		if (n < 0)
852 			return got_error_from_errno("read");
853 		if (n != sizeof(*id))
854 			return got_error(GOT_ERR_BAD_PACKFILE);
855 	}
856 
857 	return NULL;
858 }
859 
860 static const struct got_error *
861 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
862     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
863     size_t delta_size, unsigned int recursion)
864 {
865 	const struct got_error *err;
866 	struct got_object_id id;
867 	int idx;
868 	off_t base_offset;
869 	uint8_t base_type;
870 	uint64_t base_size;
871 	size_t base_tslen;
872 	off_t delta_data_offset;
873 
874 	if (delta_offset + tslen >= pack->filesize)
875 		return got_error(GOT_ERR_PACK_OFFSET);
876 
877 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
878 	if (err)
879 		return err;
880 	if (pack->map) {
881 		delta_data_offset = delta_offset + tslen + sizeof(id);
882 	} else {
883 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
884 		if (delta_data_offset == -1)
885 			return got_error_from_errno("lseek");
886 	}
887 
888 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
889 	    delta_data_offset);
890 	if (err)
891 		return err;
892 
893 	/* Delta base must be in the same pack file. */
894 	idx = got_packidx_get_object_idx(packidx, &id);
895 	if (idx == -1)
896 		return got_error(GOT_ERR_NO_OBJ);
897 
898 	base_offset = got_packidx_get_object_offset(packidx, idx);
899 	if (base_offset == (uint64_t)-1)
900 		return got_error(GOT_ERR_BAD_PACKIDX);
901 
902 	if (base_offset >= pack->filesize)
903 		return got_error(GOT_ERR_PACK_OFFSET);
904 
905 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
906 	    &base_tslen, pack, base_offset);
907 	if (err)
908 		return err;
909 
910 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
911 	    base_tslen, base_type, base_size, recursion - 1);
912 }
913 
914 const struct got_error *
915 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
916     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
917     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
918 {
919 	const struct got_error *err = NULL;
920 
921 	if (--recursion == 0)
922 		return got_error(GOT_ERR_RECURSION);
923 
924 	switch (delta_type) {
925 	case GOT_OBJ_TYPE_COMMIT:
926 	case GOT_OBJ_TYPE_TREE:
927 	case GOT_OBJ_TYPE_BLOB:
928 	case GOT_OBJ_TYPE_TAG:
929 		/* Plain types are the final delta base. Recursion ends. */
930 		err = add_delta(deltas, delta_offset, tslen, delta_type,
931 		    delta_size, 0);
932 		break;
933 	case GOT_OBJ_TYPE_OFFSET_DELTA:
934 		err = resolve_offset_delta(deltas, packidx, pack,
935 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
936 		break;
937 	case GOT_OBJ_TYPE_REF_DELTA:
938 		err = resolve_ref_delta(deltas, packidx, pack,
939 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
940 		break;
941 	default:
942 		return got_error(GOT_ERR_OBJ_TYPE);
943 	}
944 
945 	return err;
946 }
947 
948 static const struct got_error *
949 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
950     struct got_pack *pack, struct got_object_id *id, off_t offset,
951     size_t tslen, int delta_type, size_t delta_size, int idx)
952 {
953 	const struct got_error *err = NULL;
954 	int resolved_type;
955 
956 	*obj = calloc(1, sizeof(**obj));
957 	if (*obj == NULL)
958 		return got_error_from_errno("calloc");
959 
960 	(*obj)->flags = 0;
961 	(*obj)->hdrlen = 0;
962 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
963 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
964 	(*obj)->pack_offset = offset + tslen;
965 
966 	STAILQ_INIT(&(*obj)->deltas.entries);
967 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
968 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
969 	(*obj)->pack_idx = idx;
970 
971 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
972 	    offset, tslen, delta_type, delta_size,
973 	    GOT_DELTA_CHAIN_RECURSION_MAX);
974 	if (err)
975 		goto done;
976 
977 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
978 	if (err)
979 		goto done;
980 	(*obj)->type = resolved_type;
981 done:
982 	if (err) {
983 		got_object_close(*obj);
984 		*obj = NULL;
985 	}
986 	return err;
987 }
988 
989 const struct got_error *
990 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
991     struct got_packidx *packidx, int idx, struct got_object_id *id)
992 {
993 	const struct got_error *err = NULL;
994 	off_t offset;
995 	uint8_t type;
996 	uint64_t size;
997 	size_t tslen;
998 
999 	*obj = NULL;
1000 
1001 	offset = got_packidx_get_object_offset(packidx, idx);
1002 	if (offset == (uint64_t)-1)
1003 		return got_error(GOT_ERR_BAD_PACKIDX);
1004 
1005 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1006 	    pack, offset);
1007 	if (err)
1008 		return err;
1009 
1010 	switch (type) {
1011 	case GOT_OBJ_TYPE_COMMIT:
1012 	case GOT_OBJ_TYPE_TREE:
1013 	case GOT_OBJ_TYPE_BLOB:
1014 	case GOT_OBJ_TYPE_TAG:
1015 		err = open_plain_object(obj, id, type, offset + tslen,
1016 		    size, idx);
1017 		break;
1018 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1019 	case GOT_OBJ_TYPE_REF_DELTA:
1020 		err = open_delta_object(obj, packidx, pack, id, offset,
1021 		    tslen, type, size, idx);
1022 		break;
1023 	default:
1024 		err = got_error(GOT_ERR_OBJ_TYPE);
1025 		break;
1026 	}
1027 
1028 	return err;
1029 }
1030 
1031 const struct got_error *
1032 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1033     struct got_delta_chain *deltas, struct got_pack *pack)
1034 {
1035 	struct got_delta *delta;
1036 	uint64_t base_size = 0, result_size = 0;
1037 
1038 	*max_size = 0;
1039 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
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 			const struct got_error *err;
1046 			uint8_t *delta_buf;
1047 			size_t delta_len;
1048 			int cached = 1;
1049 
1050 			got_delta_cache_get(&delta_buf, &delta_len,
1051 			    pack->delta_cache, delta->data_offset);
1052 			if (delta_buf == NULL) {
1053 				cached = 0;
1054 				err = read_delta_data(&delta_buf, &delta_len,
1055 				    delta->data_offset, pack);
1056 				if (err)
1057 					return err;
1058 				err = got_delta_cache_add(pack->delta_cache,
1059 				    delta->data_offset, delta_buf, delta_len);
1060 				if (err == NULL)
1061 					cached = 1;
1062 				else if (err->code != GOT_ERR_NO_SPACE) {
1063 					free(delta_buf);
1064 					return err;
1065 				}
1066 			}
1067 			err = got_delta_get_sizes(&base_size, &result_size,
1068 			    delta_buf, delta_len);
1069 			if (!cached)
1070 				free(delta_buf);
1071 			if (err)
1072 				return err;
1073 		} else
1074 			base_size = delta->size;
1075 		if (base_size > *max_size)
1076 			*max_size = base_size;
1077 		if (result_size > *max_size)
1078 			*max_size = result_size;
1079 	}
1080 
1081 	return NULL;
1082 }
1083 
1084 const struct got_error *
1085 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1086     struct got_pack *pack)
1087 {
1088 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1089 		return got_error(GOT_ERR_OBJ_TYPE);
1090 
1091 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1092 }
1093 
1094 const struct got_error *
1095 got_pack_dump_delta_chain_to_file(size_t *result_size,
1096     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1097     FILE *base_file, FILE *accum_file)
1098 {
1099 	const struct got_error *err = NULL;
1100 	struct got_delta *delta;
1101 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1102 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1103 	uint64_t max_size;
1104 	int n = 0;
1105 
1106 	*result_size = 0;
1107 
1108 	if (STAILQ_EMPTY(&deltas->entries))
1109 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1110 
1111 	/* We process small enough files entirely in memory for speed. */
1112 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1113 	if (err)
1114 		return err;
1115 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1116 		accum_buf = malloc(max_size);
1117 		if (accum_buf == NULL)
1118 			return got_error_from_errno("malloc");
1119 		base_file = NULL;
1120 		accum_file = NULL;
1121 	}
1122 
1123 	/* Deltas are ordered in ascending order. */
1124 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1125 		int cached = 1;
1126 		if (n == 0) {
1127 			size_t mapoff;
1128 			off_t delta_data_offset;
1129 
1130 			/* Plain object types are the delta base. */
1131 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1132 			    delta->type != GOT_OBJ_TYPE_TREE &&
1133 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1134 			    delta->type != GOT_OBJ_TYPE_TAG) {
1135 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1136 				goto done;
1137 			}
1138 
1139 			delta_data_offset = delta->offset + delta->tslen;
1140 			if (delta_data_offset >= pack->filesize) {
1141 				err = got_error(GOT_ERR_PACK_OFFSET);
1142 				goto done;
1143 			}
1144 			if (pack->map == NULL) {
1145 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1146 				    == -1) {
1147 					err = got_error_from_errno("lseek");
1148 					goto done;
1149 				}
1150 			}
1151 			if (base_file) {
1152 				if (pack->map) {
1153 					mapoff = (size_t)delta_data_offset;
1154 					err = got_inflate_to_file_mmap(
1155 					    &base_bufsz, NULL, NULL, pack->map,
1156 					    mapoff, pack->filesize - mapoff,
1157 					    base_file);
1158 				} else
1159 					err = got_inflate_to_file_fd(
1160 					    &base_bufsz, NULL, NULL, pack->fd,
1161 					    base_file);
1162 			} else {
1163 				if (pack->map) {
1164 					mapoff = (size_t)delta_data_offset;
1165 					err = got_inflate_to_mem_mmap(&base_buf,
1166 					    &base_bufsz, NULL, NULL,
1167 					    pack->map, mapoff,
1168 					    pack->filesize - mapoff);
1169 				} else
1170 					err = got_inflate_to_mem_fd(&base_buf,
1171 					    &base_bufsz, NULL, NULL, max_size,
1172 					    pack->fd);
1173 			}
1174 			if (err)
1175 				goto done;
1176 			n++;
1177 			if (base_file)
1178 				rewind(base_file);
1179 			continue;
1180 		}
1181 
1182 		got_delta_cache_get(&delta_buf, &delta_len,
1183 		    pack->delta_cache, delta->data_offset);
1184 		if (delta_buf == NULL) {
1185 			cached = 0;
1186 			err = read_delta_data(&delta_buf, &delta_len,
1187 			    delta->data_offset, pack);
1188 			if (err)
1189 				goto done;
1190 			err = got_delta_cache_add(pack->delta_cache,
1191 			    delta->data_offset, delta_buf, delta_len);
1192 			if (err == NULL)
1193 				cached = 1;
1194 			else if (err->code != GOT_ERR_NO_SPACE) {
1195 				free(delta_buf);
1196 				goto done;
1197 			}
1198 		}
1199 		if (base_buf) {
1200 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1201 			    delta_buf, delta_len, accum_buf,
1202 			    &accum_size, max_size);
1203 			n++;
1204 		} else {
1205 			err = got_delta_apply(base_file, delta_buf,
1206 			    delta_len,
1207 			    /* Final delta application writes to output file. */
1208 			    ++n < deltas->nentries ? accum_file : outfile,
1209 			    &accum_size);
1210 		}
1211 		if (!cached)
1212 			free(delta_buf);
1213 		if (err)
1214 			goto done;
1215 
1216 		if (n < deltas->nentries) {
1217 			/* Accumulated delta becomes the new base. */
1218 			if (base_buf) {
1219 				uint8_t *tmp = accum_buf;
1220 				/*
1221 				 * Base buffer switches roles with accumulation
1222 				 * buffer. Ensure it can hold the largest
1223 				 * result in the delta chain. The initial
1224 				 * allocation might have been smaller.
1225 				 */
1226 				if (base_bufsz < max_size) {
1227 					uint8_t *p;
1228 					p = reallocarray(base_buf, 1, max_size);
1229 					if (p == NULL) {
1230 						err = got_error_from_errno(
1231 						    "reallocarray");
1232 						goto done;
1233 					}
1234 					base_buf = p;
1235 					base_bufsz = max_size;
1236 				}
1237 				accum_buf = base_buf;
1238 				base_buf = tmp;
1239 			} else {
1240 				FILE *tmp = accum_file;
1241 				accum_file = base_file;
1242 				base_file = tmp;
1243 				rewind(base_file);
1244 				rewind(accum_file);
1245 			}
1246 		}
1247 	}
1248 
1249 done:
1250 	free(base_buf);
1251 	if (accum_buf) {
1252 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1253 		free(accum_buf);
1254 		if (len != accum_size)
1255 			err = got_ferror(outfile, GOT_ERR_IO);
1256 	}
1257 	rewind(outfile);
1258 	if (err == NULL)
1259 		*result_size = accum_size;
1260 	return err;
1261 }
1262 
1263 const struct got_error *
1264 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1265     struct got_delta_chain *deltas, struct got_pack *pack)
1266 {
1267 	const struct got_error *err = NULL;
1268 	struct got_delta *delta;
1269 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1270 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1271 	uint64_t max_size;
1272 	int n = 0;
1273 
1274 	*outbuf = NULL;
1275 	*outlen = 0;
1276 
1277 	if (STAILQ_EMPTY(&deltas->entries))
1278 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1279 
1280 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1281 	if (err)
1282 		return err;
1283 	accum_buf = malloc(max_size);
1284 	if (accum_buf == NULL)
1285 		return got_error_from_errno("malloc");
1286 
1287 	/* Deltas are ordered in ascending order. */
1288 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1289 		int cached = 1;
1290 		if (n == 0) {
1291 			size_t delta_data_offset;
1292 
1293 			/* Plain object types are the delta base. */
1294 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1295 			    delta->type != GOT_OBJ_TYPE_TREE &&
1296 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1297 			    delta->type != GOT_OBJ_TYPE_TAG) {
1298 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1299 				goto done;
1300 			}
1301 
1302 			delta_data_offset = delta->offset + delta->tslen;
1303 			if (delta_data_offset >= pack->filesize) {
1304 				err = got_error(GOT_ERR_PACK_OFFSET);
1305 				goto done;
1306 			}
1307 			if (pack->map) {
1308 				size_t mapoff = (size_t)delta_data_offset;
1309 				err = got_inflate_to_mem_mmap(&base_buf,
1310 				    &base_bufsz, NULL, NULL, pack->map,
1311 				    mapoff, pack->filesize - mapoff);
1312 			} else {
1313 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1314 				    == -1) {
1315 					err = got_error_from_errno("lseek");
1316 					goto done;
1317 				}
1318 				err = got_inflate_to_mem_fd(&base_buf,
1319 				    &base_bufsz, NULL, NULL, max_size,
1320 				    pack->fd);
1321 			}
1322 			if (err)
1323 				goto done;
1324 			n++;
1325 			continue;
1326 		}
1327 
1328 		got_delta_cache_get(&delta_buf, &delta_len,
1329 		    pack->delta_cache, delta->data_offset);
1330 		if (delta_buf == NULL) {
1331 			cached = 0;
1332 			err = read_delta_data(&delta_buf, &delta_len,
1333 			    delta->data_offset, pack);
1334 			if (err)
1335 				goto done;
1336 			err = got_delta_cache_add(pack->delta_cache,
1337 			    delta->data_offset, delta_buf, delta_len);
1338 			if (err == NULL)
1339 				cached = 1;
1340 			else if (err->code != GOT_ERR_NO_SPACE) {
1341 				free(delta_buf);
1342 				goto done;
1343 			}
1344 		}
1345 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1346 		    delta_buf, delta_len, accum_buf,
1347 		    &accum_size, max_size);
1348 		if (!cached)
1349 			free(delta_buf);
1350 		n++;
1351 		if (err)
1352 			goto done;
1353 
1354 		if (n < deltas->nentries) {
1355 			/* Accumulated delta becomes the new base. */
1356 			uint8_t *tmp = accum_buf;
1357 			/*
1358 			 * Base buffer switches roles with accumulation buffer.
1359 			 * Ensure it can hold the largest result in the delta
1360 			 * chain. Initial allocation might have been smaller.
1361 			 */
1362 			if (base_bufsz < max_size) {
1363 				uint8_t *p;
1364 				p = reallocarray(base_buf, 1, max_size);
1365 				if (p == NULL) {
1366 					err = got_error_from_errno(
1367 					    "reallocarray");
1368 					goto done;
1369 				}
1370 				base_buf = p;
1371 				base_bufsz = max_size;
1372 			}
1373 			accum_buf = base_buf;
1374 			base_buf = tmp;
1375 		}
1376 	}
1377 
1378 done:
1379 	free(base_buf);
1380 	if (err) {
1381 		free(accum_buf);
1382 		*outbuf = NULL;
1383 		*outlen = 0;
1384 	} else {
1385 		*outbuf = accum_buf;
1386 		*outlen = accum_size;
1387 	}
1388 	return err;
1389 }
1390 
1391 const struct got_error *
1392 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1393     FILE *outfile, FILE *base_file, FILE *accum_file)
1394 {
1395 	const struct got_error *err = NULL;
1396 
1397 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1398 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1399 
1400 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1401 		if (obj->pack_offset >= pack->filesize)
1402 			return got_error(GOT_ERR_PACK_OFFSET);
1403 
1404 		if (pack->map) {
1405 			size_t mapoff = (size_t)obj->pack_offset;
1406 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1407 			    pack->map, mapoff, pack->filesize - mapoff,
1408 			    outfile);
1409 		} else {
1410 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1411 				return got_error_from_errno("lseek");
1412 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1413 			    pack->fd, outfile);
1414 		}
1415 	} else
1416 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1417 		    &obj->deltas, pack, outfile, base_file, accum_file);
1418 
1419 	return err;
1420 }
1421 
1422 const struct got_error *
1423 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1424     struct got_object *obj, struct got_pack *pack)
1425 {
1426 	const struct got_error *err = NULL;
1427 
1428 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1429 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1430 
1431 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1432 		if (obj->pack_offset >= pack->filesize)
1433 			return got_error(GOT_ERR_PACK_OFFSET);
1434 		if (pack->map) {
1435 			size_t mapoff = (size_t)obj->pack_offset;
1436 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1437 			    pack->map, mapoff, pack->filesize - mapoff);
1438 		} else {
1439 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1440 				return got_error_from_errno("lseek");
1441 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1442 			    obj->size, pack->fd);
1443 		}
1444 	} else
1445 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1446 		    pack);
1447 
1448 	return err;
1449 }