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 		goto done;
371 	}
372 
373 	if (fstat(p->fd, &idx_sb) != 0) {
374 		err = got_error_from_errno2("fstat", relpath);
375 		goto done;
376 	}
377 	p->len = idx_sb.st_size;
378 	if (p->len < sizeof(p->hdr)) {
379 		err = got_error(GOT_ERR_BAD_PACKIDX);
380 		goto done;
381 	}
382 
383 	p->path_packidx = strdup(relpath);
384 	if (p->path_packidx == NULL) {
385 		err = got_error_from_errno("strdup");
386 		goto done;
387 	}
388 
389 #ifndef GOT_PACK_NO_MMAP
390 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
391 	if (p->map == MAP_FAILED) {
392 		if (errno != ENOMEM) {
393 			err = got_error_from_errno("mmap");
394 			goto done;
395 		}
396 		p->map = NULL; /* fall back to read(2) */
397 	}
398 #endif
399 
400 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
401 done:
402 	if (err) {
403 		if (p)
404 			got_packidx_close(p);
405 	} else
406 		*packidx = p;
407 	free(pack_relpath);
408 	return err;
409 }
410 
411 const struct got_error *
412 got_packidx_close(struct got_packidx *packidx)
413 {
414 	const struct got_error *err = NULL;
415 
416 	free(packidx->path_packidx);
417 	if (packidx->map) {
418 		if (munmap(packidx->map, packidx->len) == -1)
419 			err = got_error_from_errno("munmap");
420 	} else {
421 		free(packidx->hdr.magic);
422 		free(packidx->hdr.version);
423 		free(packidx->hdr.fanout_table);
424 		free(packidx->hdr.sorted_ids);
425 		free(packidx->hdr.crc32);
426 		free(packidx->hdr.offsets);
427 		free(packidx->hdr.large_offsets);
428 		free(packidx->hdr.trailer);
429 	}
430 	if (close(packidx->fd) == -1 && err == NULL)
431 		err = got_error_from_errno("close");
432 	free(packidx);
433 
434 	return err;
435 }
436 
437 const struct got_error *
438 got_packidx_get_packfile_path(char **path_packfile, const char *path_packidx)
439 {
440 	size_t size;
441 
442 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
443 	size = strlen(path_packidx) + 2;
444 	if (size < GOT_PACKFILE_NAMELEN + 1)
445 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
446 
447 	*path_packfile = malloc(size);
448 	if (*path_packfile == NULL)
449 		return got_error_from_errno("malloc");
450 
451 	/* Copy up to and excluding ".idx". */
452 	if (strlcpy(*path_packfile, path_packidx,
453 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
454 		return got_error(GOT_ERR_NO_SPACE);
455 
456 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
457 		return got_error(GOT_ERR_NO_SPACE);
458 
459 	return NULL;
460 }
461 
462 off_t
463 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
464 {
465 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
466 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
467 		uint64_t loffset;
468 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
469 		if (idx < 0 || idx >= packidx->nlargeobj ||
470 		    packidx->hdr.large_offsets == NULL)
471 			return -1;
472 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
473 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
474 	}
475 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
476 }
477 
478 int
479 got_packidx_get_object_idx(struct got_packidx *packidx,
480     struct got_object_id *id)
481 {
482 	u_int8_t id0 = id->sha1[0];
483 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
484 	int left = 0, right = totobj - 1;
485 
486 	if (id0 > 0)
487 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
488 
489 	while (left <= right) {
490 		struct got_packidx_object_id *oid;
491 		int i, cmp;
492 
493 		i = ((left + right) / 2);
494 		oid = &packidx->hdr.sorted_ids[i];
495 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
496 		if (cmp == 0)
497 			return i;
498 		else if (cmp > 0)
499 			left = i + 1;
500 		else if (cmp < 0)
501 			right = i - 1;
502 	}
503 
504 	return -1;
505 }
506 
507 const struct got_error *
508 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
509     struct got_packidx *packidx, const char *id_str_prefix)
510 {
511 	const struct got_error *err = NULL;
512 	u_int8_t id0;
513 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
514 	char hex[3];
515 	size_t prefix_len = strlen(id_str_prefix);
516 	struct got_packidx_object_id *oid;
517 	uint32_t i = 0;
518 
519 	STAILQ_INIT(matched_ids);
520 
521 	if (prefix_len < 2)
522 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
523 
524 	hex[0] = id_str_prefix[0];
525 	hex[1] = id_str_prefix[1];
526 	hex[2] = '\0';
527 	if (!got_parse_xdigit(&id0, hex))
528 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
529 
530 	if (id0 > 0)
531 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
532 	oid = &packidx->hdr.sorted_ids[i];
533 	while (i < totobj && oid->sha1[0] == id0) {
534 		char id_str[SHA1_DIGEST_STRING_LENGTH];
535 		struct got_object_qid *qid;
536 		int cmp;
537 
538 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
539 		        return got_error(GOT_ERR_NO_SPACE);
540 
541 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
542 		if (cmp < 0) {
543 			oid = &packidx->hdr.sorted_ids[++i];
544 			continue;
545 		} else if (cmp > 0)
546 			break;
547 
548 		err = got_object_qid_alloc_partial(&qid);
549 		if (err)
550 			break;
551 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
552 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
553 
554 		oid = &packidx->hdr.sorted_ids[++i];
555 	}
556 
557 	if (err)
558 		got_object_id_queue_free(matched_ids);
559 	return err;
560 }
561 
562 static const struct got_error *
563 pack_stop_privsep_child(struct got_pack *pack)
564 {
565 	const struct got_error *err = NULL;
566 
567 	if (pack->privsep_child == NULL)
568 		return NULL;
569 
570 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
571 	if (err)
572 		return err;
573 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
574 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
575 		err = got_error_from_errno("close");
576 	imsg_clear(pack->privsep_child->ibuf);
577 	free(pack->privsep_child->ibuf);
578 	free(pack->privsep_child);
579 	pack->privsep_child = NULL;
580 	return err;
581 }
582 
583 const struct got_error *
584 got_pack_close(struct got_pack *pack)
585 {
586 	const struct got_error *err = NULL;
587 
588 	err = pack_stop_privsep_child(pack);
589 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
590 		err = got_error_from_errno("munmap");
591 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
592 		err = got_error_from_errno("close");
593 	pack->fd = -1;
594 	free(pack->path_packfile);
595 	pack->path_packfile = NULL;
596 	pack->filesize = 0;
597 	if (pack->delta_cache) {
598 		got_delta_cache_free(pack->delta_cache);
599 		pack->delta_cache = NULL;
600 	}
601 
602 	return err;
603 }
604 
605 const struct got_error *
606 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
607     struct got_pack *pack, off_t offset)
608 {
609 	uint8_t t = 0;
610 	uint64_t s = 0;
611 	uint8_t sizeN;
612 	size_t mapoff = 0;
613 	int i = 0;
614 
615 	*len = 0;
616 
617 	if (offset >= pack->filesize)
618 		return got_error(GOT_ERR_PACK_OFFSET);
619 
620 	if (pack->map) {
621 		mapoff = (size_t)offset;
622 	} else {
623 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
624 			return got_error_from_errno("lseek");
625 	}
626 
627 	do {
628 		/* We do not support size values which don't fit in 64 bit. */
629 		if (i > 9)
630 			return got_error(GOT_ERR_NO_SPACE);
631 
632 		if (pack->map) {
633 			if (mapoff + sizeof(sizeN) >= pack->filesize)
634 				return got_error(GOT_ERR_BAD_PACKFILE);
635 			sizeN = *(pack->map + mapoff);
636 			mapoff += sizeof(sizeN);
637 		} else {
638 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
639 			if (n < 0)
640 				return got_error_from_errno("read");
641 			if (n != sizeof(sizeN))
642 				return got_error(GOT_ERR_BAD_PACKFILE);
643 		}
644 		*len += sizeof(sizeN);
645 
646 		if (i == 0) {
647 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
648 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
649 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
650 		} else {
651 			size_t shift = 4 + 7 * (i - 1);
652 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
653 		}
654 		i++;
655 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
656 
657 	*type = t;
658 	*size = s;
659 	return NULL;
660 }
661 
662 static const struct got_error *
663 open_plain_object(struct got_object **obj, struct got_object_id *id,
664     uint8_t type, off_t offset, size_t size, int idx)
665 {
666 	*obj = calloc(1, sizeof(**obj));
667 	if (*obj == NULL)
668 		return got_error_from_errno("calloc");
669 
670 	(*obj)->type = type;
671 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
672 	(*obj)->pack_idx = idx;
673 	(*obj)->hdrlen = 0;
674 	(*obj)->size = size;
675 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
676 	(*obj)->pack_offset = offset;
677 
678 	return NULL;
679 }
680 
681 static const struct got_error *
682 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
683     off_t delta_offset)
684 {
685 	int64_t o = 0;
686 	uint8_t offN;
687 	int i = 0;
688 
689 	*offset = 0;
690 	*len = 0;
691 
692 	do {
693 		/* We do not support offset values which don't fit in 64 bit. */
694 		if (i > 8)
695 			return got_error(GOT_ERR_NO_SPACE);
696 
697 		if (pack->map) {
698 			size_t mapoff;
699 			mapoff = (size_t)delta_offset + *len;
700 			if (mapoff + sizeof(offN) >= pack->filesize)
701 				return got_error(GOT_ERR_PACK_OFFSET);
702 			offN = *(pack->map + mapoff);
703 		} else {
704 			ssize_t n;
705 			n = read(pack->fd, &offN, sizeof(offN));
706 			if (n < 0)
707 				return got_error_from_errno("read");
708 			if (n != sizeof(offN))
709 				return got_error(GOT_ERR_BAD_PACKFILE);
710 		}
711 		*len += sizeof(offN);
712 
713 		if (i == 0)
714 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
715 		else {
716 			o++;
717 			o <<= 7;
718 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
719 		}
720 		i++;
721 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
722 
723 	*offset = o;
724 	return NULL;
725 }
726 
727 const struct got_error *
728 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
729     struct got_pack *pack, off_t offset, int tslen)
730 {
731 	const struct got_error *err;
732 	int64_t negoffset;
733 	size_t negofflen;
734 
735 	*len = 0;
736 
737 	err = parse_negative_offset(&negoffset, &negofflen, pack,
738 	    offset + tslen);
739 	if (err)
740 		return err;
741 
742 	/* Compute the base object's offset (must be in the same pack file). */
743 	*base_offset = (offset - negoffset);
744 	if (*base_offset <= 0)
745 		return got_error(GOT_ERR_BAD_PACKFILE);
746 
747 	*len = negofflen;
748 	return NULL;
749 }
750 
751 static const struct got_error *
752 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
753     size_t delta_data_offset, struct got_pack *pack)
754 {
755 	const struct got_error *err = NULL;
756 
757 	if (pack->map) {
758 		if (delta_data_offset >= pack->filesize)
759 			return got_error(GOT_ERR_PACK_OFFSET);
760 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
761 		    NULL, NULL, pack->map, delta_data_offset,
762 		    pack->filesize - delta_data_offset);
763 	} else {
764 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
765 			return got_error_from_errno("lseek");
766 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
767 		    NULL, 0, pack->fd);
768 	}
769 	return err;
770 }
771 
772 static const struct got_error *
773 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
774     int delta_type, size_t delta_size, size_t delta_data_offset)
775 {
776 	struct got_delta *delta;
777 
778 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
779 	    delta_data_offset);
780 	if (delta == NULL)
781 		return got_error_from_errno("got_delta_open");
782 	/* delta is freed in got_object_close() */
783 	deltas->nentries++;
784 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
785 	return NULL;
786 }
787 
788 static const struct got_error *
789 resolve_offset_delta(struct got_delta_chain *deltas,
790     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
791     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
792 
793 {
794 	const struct got_error *err;
795 	off_t base_offset;
796 	uint8_t base_type;
797 	uint64_t base_size;
798 	size_t base_tslen;
799 	off_t delta_data_offset;
800 	size_t consumed;
801 
802 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
803 	    delta_offset, tslen);
804 	if (err)
805 		return err;
806 
807 	delta_data_offset = delta_offset + tslen + consumed;
808 	if (delta_data_offset >= pack->filesize)
809 		return got_error(GOT_ERR_PACK_OFFSET);
810 
811 	if (pack->map == NULL) {
812 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
813 		if (delta_data_offset == -1)
814 			return got_error_from_errno("lseek");
815 	}
816 
817 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
818 	    delta_data_offset);
819 	if (err)
820 		return err;
821 
822 	/* An offset delta must be in the same packfile. */
823 	if (base_offset >= pack->filesize)
824 		return got_error(GOT_ERR_PACK_OFFSET);
825 
826 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
827 	    &base_tslen, pack, base_offset);
828 	if (err)
829 		return err;
830 
831 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
832 	    base_tslen, base_type, base_size, recursion - 1);
833 }
834 
835 const struct got_error *
836 got_pack_parse_ref_delta(struct got_object_id *id,
837     struct got_pack *pack, off_t delta_offset, int tslen)
838 {
839 	if (pack->map) {
840 		size_t mapoff = delta_offset + tslen;
841 		if (mapoff + sizeof(*id) >= pack->filesize)
842 			return got_error(GOT_ERR_PACK_OFFSET);
843 		memcpy(id, pack->map + mapoff, sizeof(*id));
844 	} else {
845 		ssize_t n;
846 		n = read(pack->fd, id, sizeof(*id));
847 		if (n < 0)
848 			return got_error_from_errno("read");
849 		if (n != sizeof(*id))
850 			return got_error(GOT_ERR_BAD_PACKFILE);
851 	}
852 
853 	return NULL;
854 }
855 
856 static const struct got_error *
857 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
858     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
859     size_t delta_size, unsigned int recursion)
860 {
861 	const struct got_error *err;
862 	struct got_object_id id;
863 	int idx;
864 	off_t base_offset;
865 	uint8_t base_type;
866 	uint64_t base_size;
867 	size_t base_tslen;
868 	off_t delta_data_offset;
869 
870 	if (delta_offset + tslen >= pack->filesize)
871 		return got_error(GOT_ERR_PACK_OFFSET);
872 
873 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
874 	if (err)
875 		return err;
876 	if (pack->map) {
877 		delta_data_offset = delta_offset + tslen + sizeof(id);
878 	} else {
879 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
880 		if (delta_data_offset == -1)
881 			return got_error_from_errno("lseek");
882 	}
883 
884 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
885 	    delta_data_offset);
886 	if (err)
887 		return err;
888 
889 	/* Delta base must be in the same pack file. */
890 	idx = got_packidx_get_object_idx(packidx, &id);
891 	if (idx == -1)
892 		return got_error(GOT_ERR_NO_OBJ);
893 
894 	base_offset = got_packidx_get_object_offset(packidx, idx);
895 	if (base_offset == (uint64_t)-1)
896 		return got_error(GOT_ERR_BAD_PACKIDX);
897 
898 	if (base_offset >= pack->filesize)
899 		return got_error(GOT_ERR_PACK_OFFSET);
900 
901 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
902 	    &base_tslen, pack, base_offset);
903 	if (err)
904 		return err;
905 
906 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
907 	    base_tslen, base_type, base_size, recursion - 1);
908 }
909 
910 const struct got_error *
911 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
912     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
913     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
914 {
915 	const struct got_error *err = NULL;
916 
917 	if (--recursion == 0)
918 		return got_error(GOT_ERR_RECURSION);
919 
920 	switch (delta_type) {
921 	case GOT_OBJ_TYPE_COMMIT:
922 	case GOT_OBJ_TYPE_TREE:
923 	case GOT_OBJ_TYPE_BLOB:
924 	case GOT_OBJ_TYPE_TAG:
925 		/* Plain types are the final delta base. Recursion ends. */
926 		err = add_delta(deltas, delta_offset, tslen, delta_type,
927 		    delta_size, 0);
928 		break;
929 	case GOT_OBJ_TYPE_OFFSET_DELTA:
930 		err = resolve_offset_delta(deltas, packidx, pack,
931 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
932 		break;
933 	case GOT_OBJ_TYPE_REF_DELTA:
934 		err = resolve_ref_delta(deltas, packidx, pack,
935 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
936 		break;
937 	default:
938 		return got_error(GOT_ERR_OBJ_TYPE);
939 	}
940 
941 	return err;
942 }
943 
944 static const struct got_error *
945 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
946     struct got_pack *pack, struct got_object_id *id, off_t offset,
947     size_t tslen, int delta_type, size_t delta_size, int idx)
948 {
949 	const struct got_error *err = NULL;
950 	int resolved_type;
951 
952 	*obj = calloc(1, sizeof(**obj));
953 	if (*obj == NULL)
954 		return got_error_from_errno("calloc");
955 
956 	(*obj)->flags = 0;
957 	(*obj)->hdrlen = 0;
958 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
959 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
960 	(*obj)->pack_offset = offset + tslen;
961 
962 	STAILQ_INIT(&(*obj)->deltas.entries);
963 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
964 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
965 	(*obj)->pack_idx = idx;
966 
967 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
968 	    offset, tslen, delta_type, delta_size,
969 	    GOT_DELTA_CHAIN_RECURSION_MAX);
970 	if (err)
971 		goto done;
972 
973 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
974 	if (err)
975 		goto done;
976 	(*obj)->type = resolved_type;
977 done:
978 	if (err) {
979 		got_object_close(*obj);
980 		*obj = NULL;
981 	}
982 	return err;
983 }
984 
985 const struct got_error *
986 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
987     struct got_packidx *packidx, int idx, struct got_object_id *id)
988 {
989 	const struct got_error *err = NULL;
990 	off_t offset;
991 	uint8_t type;
992 	uint64_t size;
993 	size_t tslen;
994 
995 	*obj = NULL;
996 
997 	offset = got_packidx_get_object_offset(packidx, idx);
998 	if (offset == (uint64_t)-1)
999 		return got_error(GOT_ERR_BAD_PACKIDX);
1000 
1001 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1002 	    pack, offset);
1003 	if (err)
1004 		return err;
1005 
1006 	switch (type) {
1007 	case GOT_OBJ_TYPE_COMMIT:
1008 	case GOT_OBJ_TYPE_TREE:
1009 	case GOT_OBJ_TYPE_BLOB:
1010 	case GOT_OBJ_TYPE_TAG:
1011 		err = open_plain_object(obj, id, type, offset + tslen,
1012 		    size, idx);
1013 		break;
1014 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1015 	case GOT_OBJ_TYPE_REF_DELTA:
1016 		err = open_delta_object(obj, packidx, pack, id, offset,
1017 		    tslen, type, size, idx);
1018 		break;
1019 	default:
1020 		err = got_error(GOT_ERR_OBJ_TYPE);
1021 		break;
1022 	}
1023 
1024 	return err;
1025 }
1026 
1027 const struct got_error *
1028 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1029     struct got_delta_chain *deltas, struct got_pack *pack)
1030 {
1031 	struct got_delta *delta;
1032 	uint64_t base_size = 0, result_size = 0;
1033 
1034 	*max_size = 0;
1035 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1036 		/* Plain object types are the delta base. */
1037 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1038 		    delta->type != GOT_OBJ_TYPE_TREE &&
1039 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1040 		    delta->type != GOT_OBJ_TYPE_TAG) {
1041 			const struct got_error *err;
1042 			uint8_t *delta_buf;
1043 			size_t delta_len;
1044 			int cached = 1;
1045 
1046 			got_delta_cache_get(&delta_buf, &delta_len,
1047 			    pack->delta_cache, delta->data_offset);
1048 			if (delta_buf == NULL) {
1049 				cached = 0;
1050 				err = read_delta_data(&delta_buf, &delta_len,
1051 				    delta->data_offset, pack);
1052 				if (err)
1053 					return err;
1054 				err = got_delta_cache_add(pack->delta_cache,
1055 				    delta->data_offset, delta_buf, delta_len);
1056 				if (err == NULL)
1057 					cached = 1;
1058 				else if (err->code != GOT_ERR_NO_SPACE) {
1059 					free(delta_buf);
1060 					return err;
1061 				}
1062 			}
1063 			err = got_delta_get_sizes(&base_size, &result_size,
1064 			    delta_buf, delta_len);
1065 			if (!cached)
1066 				free(delta_buf);
1067 			if (err)
1068 				return err;
1069 		} else
1070 			base_size = delta->size;
1071 		if (base_size > *max_size)
1072 			*max_size = base_size;
1073 		if (result_size > *max_size)
1074 			*max_size = result_size;
1075 	}
1076 
1077 	return NULL;
1078 }
1079 
1080 const struct got_error *
1081 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1082     struct got_pack *pack)
1083 {
1084 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1085 		return got_error(GOT_ERR_OBJ_TYPE);
1086 
1087 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1088 }
1089 
1090 const struct got_error *
1091 got_pack_dump_delta_chain_to_file(size_t *result_size,
1092     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1093     FILE *base_file, FILE *accum_file)
1094 {
1095 	const struct got_error *err = NULL;
1096 	struct got_delta *delta;
1097 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1098 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1099 	uint64_t max_size;
1100 	int n = 0;
1101 
1102 	*result_size = 0;
1103 
1104 	if (STAILQ_EMPTY(&deltas->entries))
1105 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1106 
1107 	/* We process small enough files entirely in memory for speed. */
1108 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1109 	if (err)
1110 		return err;
1111 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1112 		accum_buf = malloc(max_size);
1113 		if (accum_buf == NULL)
1114 			return got_error_from_errno("malloc");
1115 		base_file = NULL;
1116 		accum_file = NULL;
1117 	} else {
1118 		if (fseeko(base_file, 0L, SEEK_SET) == -1)
1119 			return got_error_from_errno("fseeko");
1120 		if (fseeko(accum_file, 0L, SEEK_SET) == -1)
1121 			return got_error_from_errno("fseeko");
1122 	}
1123 
1124 	/* Deltas are ordered in ascending order. */
1125 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1126 		int cached = 1;
1127 		if (n == 0) {
1128 			size_t mapoff;
1129 			off_t delta_data_offset;
1130 
1131 			/* Plain object types are the delta base. */
1132 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1133 			    delta->type != GOT_OBJ_TYPE_TREE &&
1134 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1135 			    delta->type != GOT_OBJ_TYPE_TAG) {
1136 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1137 				goto done;
1138 			}
1139 
1140 			delta_data_offset = delta->offset + delta->tslen;
1141 			if (delta_data_offset >= pack->filesize) {
1142 				err = got_error(GOT_ERR_PACK_OFFSET);
1143 				goto done;
1144 			}
1145 			if (pack->map == NULL) {
1146 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1147 				    == -1) {
1148 					err = got_error_from_errno("lseek");
1149 					goto done;
1150 				}
1151 			}
1152 			if (base_file) {
1153 				if (pack->map) {
1154 					mapoff = (size_t)delta_data_offset;
1155 					err = got_inflate_to_file_mmap(
1156 					    &base_bufsz, NULL, NULL, pack->map,
1157 					    mapoff, pack->filesize - mapoff,
1158 					    base_file);
1159 				} else
1160 					err = got_inflate_to_file_fd(
1161 					    &base_bufsz, NULL, NULL, pack->fd,
1162 					    base_file);
1163 			} else {
1164 				if (pack->map) {
1165 					mapoff = (size_t)delta_data_offset;
1166 					err = got_inflate_to_mem_mmap(&base_buf,
1167 					    &base_bufsz, NULL, NULL,
1168 					    pack->map, mapoff,
1169 					    pack->filesize - mapoff);
1170 				} else
1171 					err = got_inflate_to_mem_fd(&base_buf,
1172 					    &base_bufsz, NULL, NULL, max_size,
1173 					    pack->fd);
1174 			}
1175 			if (err)
1176 				goto done;
1177 			n++;
1178 			if (base_file)
1179 				rewind(base_file);
1180 			continue;
1181 		}
1182 
1183 		got_delta_cache_get(&delta_buf, &delta_len,
1184 		    pack->delta_cache, delta->data_offset);
1185 		if (delta_buf == NULL) {
1186 			cached = 0;
1187 			err = read_delta_data(&delta_buf, &delta_len,
1188 			    delta->data_offset, pack);
1189 			if (err)
1190 				goto done;
1191 			err = got_delta_cache_add(pack->delta_cache,
1192 			    delta->data_offset, delta_buf, delta_len);
1193 			if (err == NULL)
1194 				cached = 1;
1195 			else if (err->code != GOT_ERR_NO_SPACE) {
1196 				free(delta_buf);
1197 				goto done;
1198 			}
1199 		}
1200 		if (base_buf) {
1201 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1202 			    delta_buf, delta_len, accum_buf,
1203 			    &accum_size, max_size);
1204 			n++;
1205 		} else {
1206 			err = got_delta_apply(base_file, delta_buf,
1207 			    delta_len,
1208 			    /* Final delta application writes to output file. */
1209 			    ++n < deltas->nentries ? accum_file : outfile,
1210 			    &accum_size);
1211 		}
1212 		if (!cached)
1213 			free(delta_buf);
1214 		if (err)
1215 			goto done;
1216 
1217 		if (n < deltas->nentries) {
1218 			/* Accumulated delta becomes the new base. */
1219 			if (base_buf) {
1220 				uint8_t *tmp = accum_buf;
1221 				/*
1222 				 * Base buffer switches roles with accumulation
1223 				 * buffer. Ensure it can hold the largest
1224 				 * result in the delta chain. The initial
1225 				 * allocation might have been smaller.
1226 				 */
1227 				if (base_bufsz < max_size) {
1228 					uint8_t *p;
1229 					p = reallocarray(base_buf, 1, max_size);
1230 					if (p == NULL) {
1231 						err = got_error_from_errno(
1232 						    "reallocarray");
1233 						goto done;
1234 					}
1235 					base_buf = p;
1236 					base_bufsz = max_size;
1237 				}
1238 				accum_buf = base_buf;
1239 				base_buf = tmp;
1240 			} else {
1241 				FILE *tmp = accum_file;
1242 				accum_file = base_file;
1243 				base_file = tmp;
1244 				rewind(base_file);
1245 				rewind(accum_file);
1246 			}
1247 		}
1248 	}
1249 
1250 done:
1251 	free(base_buf);
1252 	if (accum_buf) {
1253 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1254 		free(accum_buf);
1255 		if (len != accum_size)
1256 			err = got_ferror(outfile, GOT_ERR_IO);
1257 	}
1258 	rewind(outfile);
1259 	if (err == NULL)
1260 		*result_size = accum_size;
1261 	return err;
1262 }
1263 
1264 const struct got_error *
1265 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1266     struct got_delta_chain *deltas, struct got_pack *pack)
1267 {
1268 	const struct got_error *err = NULL;
1269 	struct got_delta *delta;
1270 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1271 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1272 	uint64_t max_size;
1273 	int n = 0;
1274 
1275 	*outbuf = NULL;
1276 	*outlen = 0;
1277 
1278 	if (STAILQ_EMPTY(&deltas->entries))
1279 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1280 
1281 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1282 	if (err)
1283 		return err;
1284 	accum_buf = malloc(max_size);
1285 	if (accum_buf == NULL)
1286 		return got_error_from_errno("malloc");
1287 
1288 	/* Deltas are ordered in ascending order. */
1289 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1290 		int cached = 1;
1291 		if (n == 0) {
1292 			size_t delta_data_offset;
1293 
1294 			/* Plain object types are the delta base. */
1295 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1296 			    delta->type != GOT_OBJ_TYPE_TREE &&
1297 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1298 			    delta->type != GOT_OBJ_TYPE_TAG) {
1299 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1300 				goto done;
1301 			}
1302 
1303 			delta_data_offset = delta->offset + delta->tslen;
1304 			if (delta_data_offset >= pack->filesize) {
1305 				err = got_error(GOT_ERR_PACK_OFFSET);
1306 				goto done;
1307 			}
1308 			if (pack->map) {
1309 				size_t mapoff = (size_t)delta_data_offset;
1310 				err = got_inflate_to_mem_mmap(&base_buf,
1311 				    &base_bufsz, NULL, NULL, pack->map,
1312 				    mapoff, pack->filesize - mapoff);
1313 			} else {
1314 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1315 				    == -1) {
1316 					err = got_error_from_errno("lseek");
1317 					goto done;
1318 				}
1319 				err = got_inflate_to_mem_fd(&base_buf,
1320 				    &base_bufsz, NULL, NULL, max_size,
1321 				    pack->fd);
1322 			}
1323 			if (err)
1324 				goto done;
1325 			n++;
1326 			continue;
1327 		}
1328 
1329 		got_delta_cache_get(&delta_buf, &delta_len,
1330 		    pack->delta_cache, delta->data_offset);
1331 		if (delta_buf == NULL) {
1332 			cached = 0;
1333 			err = read_delta_data(&delta_buf, &delta_len,
1334 			    delta->data_offset, pack);
1335 			if (err)
1336 				goto done;
1337 			err = got_delta_cache_add(pack->delta_cache,
1338 			    delta->data_offset, delta_buf, delta_len);
1339 			if (err == NULL)
1340 				cached = 1;
1341 			else if (err->code != GOT_ERR_NO_SPACE) {
1342 				free(delta_buf);
1343 				goto done;
1344 			}
1345 		}
1346 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1347 		    delta_buf, delta_len, accum_buf,
1348 		    &accum_size, max_size);
1349 		if (!cached)
1350 			free(delta_buf);
1351 		n++;
1352 		if (err)
1353 			goto done;
1354 
1355 		if (n < deltas->nentries) {
1356 			/* Accumulated delta becomes the new base. */
1357 			uint8_t *tmp = accum_buf;
1358 			/*
1359 			 * Base buffer switches roles with accumulation buffer.
1360 			 * Ensure it can hold the largest result in the delta
1361 			 * chain. Initial allocation might have been smaller.
1362 			 */
1363 			if (base_bufsz < max_size) {
1364 				uint8_t *p;
1365 				p = reallocarray(base_buf, 1, max_size);
1366 				if (p == NULL) {
1367 					err = got_error_from_errno(
1368 					    "reallocarray");
1369 					goto done;
1370 				}
1371 				base_buf = p;
1372 				base_bufsz = max_size;
1373 			}
1374 			accum_buf = base_buf;
1375 			base_buf = tmp;
1376 		}
1377 	}
1378 
1379 done:
1380 	free(base_buf);
1381 	if (err) {
1382 		free(accum_buf);
1383 		*outbuf = NULL;
1384 		*outlen = 0;
1385 	} else {
1386 		*outbuf = accum_buf;
1387 		*outlen = accum_size;
1388 	}
1389 	return err;
1390 }
1391 
1392 const struct got_error *
1393 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1394     FILE *outfile, FILE *base_file, FILE *accum_file)
1395 {
1396 	const struct got_error *err = NULL;
1397 
1398 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1399 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1400 
1401 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1402 		if (obj->pack_offset >= pack->filesize)
1403 			return got_error(GOT_ERR_PACK_OFFSET);
1404 
1405 		if (pack->map) {
1406 			size_t mapoff = (size_t)obj->pack_offset;
1407 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1408 			    pack->map, mapoff, pack->filesize - mapoff,
1409 			    outfile);
1410 		} else {
1411 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1412 				return got_error_from_errno("lseek");
1413 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1414 			    pack->fd, outfile);
1415 		}
1416 	} else
1417 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1418 		    &obj->deltas, pack, outfile, base_file, accum_file);
1419 
1420 	return err;
1421 }
1422 
1423 const struct got_error *
1424 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1425     struct got_object *obj, struct got_pack *pack)
1426 {
1427 	const struct got_error *err = NULL;
1428 
1429 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1430 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1431 
1432 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1433 		if (obj->pack_offset >= pack->filesize)
1434 			return got_error(GOT_ERR_PACK_OFFSET);
1435 		if (pack->map) {
1436 			size_t mapoff = (size_t)obj->pack_offset;
1437 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1438 			    pack->map, mapoff, pack->filesize - mapoff);
1439 		} else {
1440 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1441 				return got_error_from_errno("lseek");
1442 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1443 			    obj->size, pack->fd);
1444 		}
1445 	} else
1446 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1447 		    pack);
1448 
1449 	return err;
1450 }