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Date:: Wed Jan 26 10:33:21 2022 UTC
Message:: fix double-free and double-close issues in error paths of got_packidx_open()
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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 		goto done;
375 	}
376 
377 	if (fstat(p->fd, &idx_sb) != 0) {
378 		err = got_error_from_errno2("fstat", relpath);
379 		goto done;
380 	}
381 	p->len = idx_sb.st_size;
382 	if (p->len < sizeof(p->hdr)) {
383 		err = got_error(GOT_ERR_BAD_PACKIDX);
384 		goto done;
385 	}
386 
387 	p->path_packidx = strdup(relpath);
388 	if (p->path_packidx == NULL) {
389 		err = got_error_from_errno("strdup");
390 		goto done;
391 	}
392 
393 #ifndef GOT_PACK_NO_MMAP
394 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
395 	if (p->map == MAP_FAILED) {
396 		if (errno != ENOMEM) {
397 			err = got_error_from_errno("mmap");
398 			goto done;
399 		}
400 		p->map = NULL; /* fall back to read(2) */
401 	}
402 #endif
403 
404 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
405 done:
406 	if (err) {
407 		if (p)
408 			got_packidx_close(p);
409 	} else
410 		*packidx = p;
411 	free(pack_relpath);
412 	return err;
413 }
414 
415 const struct got_error *
416 got_packidx_close(struct got_packidx *packidx)
417 {
418 	const struct got_error *err = NULL;
419 
420 	free(packidx->path_packidx);
421 	if (packidx->map) {
422 		if (munmap(packidx->map, packidx->len) == -1)
423 			err = got_error_from_errno("munmap");
424 	} else {
425 		free(packidx->hdr.magic);
426 		free(packidx->hdr.version);
427 		free(packidx->hdr.fanout_table);
428 		free(packidx->hdr.sorted_ids);
429 		free(packidx->hdr.crc32);
430 		free(packidx->hdr.offsets);
431 		free(packidx->hdr.large_offsets);
432 		free(packidx->hdr.trailer);
433 	}
434 	if (close(packidx->fd) == -1 && err == NULL)
435 		err = got_error_from_errno("close");
436 	free(packidx);
437 
438 	return err;
439 }
440 
441 const struct got_error *
442 got_packidx_get_packfile_path(char **path_packfile, const char *path_packidx)
443 {
444 	size_t size;
445 
446 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
447 	size = strlen(path_packidx) + 2;
448 	if (size < GOT_PACKFILE_NAMELEN + 1)
449 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
450 
451 	*path_packfile = malloc(size);
452 	if (*path_packfile == NULL)
453 		return got_error_from_errno("malloc");
454 
455 	/* Copy up to and excluding ".idx". */
456 	if (strlcpy(*path_packfile, path_packidx,
457 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
458 		return got_error(GOT_ERR_NO_SPACE);
459 
460 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
461 		return got_error(GOT_ERR_NO_SPACE);
462 
463 	return NULL;
464 }
465 
466 off_t
467 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
468 {
469 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
470 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
471 		uint64_t loffset;
472 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
473 		if (idx < 0 || idx >= packidx->nlargeobj ||
474 		    packidx->hdr.large_offsets == NULL)
475 			return -1;
476 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
477 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
478 	}
479 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
480 }
481 
482 int
483 got_packidx_get_object_idx(struct got_packidx *packidx,
484     struct got_object_id *id)
485 {
486 	u_int8_t id0 = id->sha1[0];
487 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
488 	int left = 0, right = totobj - 1;
489 
490 	if (id0 > 0)
491 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
492 
493 	while (left <= right) {
494 		struct got_packidx_object_id *oid;
495 		int i, cmp;
496 
497 		i = ((left + right) / 2);
498 		oid = &packidx->hdr.sorted_ids[i];
499 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
500 		if (cmp == 0)
501 			return i;
502 		else if (cmp > 0)
503 			left = i + 1;
504 		else if (cmp < 0)
505 			right = i - 1;
506 	}
507 
508 	return -1;
509 }
510 
511 const struct got_error *
512 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
513     struct got_packidx *packidx, const char *id_str_prefix)
514 {
515 	const struct got_error *err = NULL;
516 	u_int8_t id0;
517 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
518 	char hex[3];
519 	size_t prefix_len = strlen(id_str_prefix);
520 	struct got_packidx_object_id *oid;
521 	uint32_t i = 0;
522 
523 	STAILQ_INIT(matched_ids);
524 
525 	if (prefix_len < 2)
526 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
527 
528 	hex[0] = id_str_prefix[0];
529 	hex[1] = id_str_prefix[1];
530 	hex[2] = '\0';
531 	if (!got_parse_xdigit(&id0, hex))
532 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
533 
534 	if (id0 > 0)
535 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
536 	oid = &packidx->hdr.sorted_ids[i];
537 	while (i < totobj && oid->sha1[0] == id0) {
538 		char id_str[SHA1_DIGEST_STRING_LENGTH];
539 		struct got_object_qid *qid;
540 		int cmp;
541 
542 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
543 		        return got_error(GOT_ERR_NO_SPACE);
544 
545 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
546 		if (cmp < 0) {
547 			oid = &packidx->hdr.sorted_ids[++i];
548 			continue;
549 		} else if (cmp > 0)
550 			break;
551 
552 		err = got_object_qid_alloc_partial(&qid);
553 		if (err)
554 			break;
555 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
556 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
557 
558 		oid = &packidx->hdr.sorted_ids[++i];
559 	}
560 
561 	if (err)
562 		got_object_id_queue_free(matched_ids);
563 	return err;
564 }
565 
566 static const struct got_error *
567 pack_stop_privsep_child(struct got_pack *pack)
568 {
569 	const struct got_error *err = NULL;
570 
571 	if (pack->privsep_child == NULL)
572 		return NULL;
573 
574 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
575 	if (err)
576 		return err;
577 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
578 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
579 		err = got_error_from_errno("close");
580 	imsg_clear(pack->privsep_child->ibuf);
581 	free(pack->privsep_child->ibuf);
582 	free(pack->privsep_child);
583 	pack->privsep_child = NULL;
584 	return err;
585 }
586 
587 const struct got_error *
588 got_pack_close(struct got_pack *pack)
589 {
590 	const struct got_error *err = NULL;
591 
592 	err = pack_stop_privsep_child(pack);
593 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
594 		err = got_error_from_errno("munmap");
595 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
596 		err = got_error_from_errno("close");
597 	pack->fd = -1;
598 	free(pack->path_packfile);
599 	pack->path_packfile = NULL;
600 	pack->filesize = 0;
601 	if (pack->delta_cache) {
602 		got_delta_cache_free(pack->delta_cache);
603 		pack->delta_cache = NULL;
604 	}
605 
606 	return err;
607 }
608 
609 const struct got_error *
610 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
611     struct got_pack *pack, off_t offset)
612 {
613 	uint8_t t = 0;
614 	uint64_t s = 0;
615 	uint8_t sizeN;
616 	size_t mapoff = 0;
617 	int i = 0;
618 
619 	*len = 0;
620 
621 	if (offset >= pack->filesize)
622 		return got_error(GOT_ERR_PACK_OFFSET);
623 
624 	if (pack->map) {
625 		mapoff = (size_t)offset;
626 	} else {
627 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
628 			return got_error_from_errno("lseek");
629 	}
630 
631 	do {
632 		/* We do not support size values which don't fit in 64 bit. */
633 		if (i > 9)
634 			return got_error(GOT_ERR_NO_SPACE);
635 
636 		if (pack->map) {
637 			if (mapoff + sizeof(sizeN) >= pack->filesize)
638 				return got_error(GOT_ERR_BAD_PACKFILE);
639 			sizeN = *(pack->map + mapoff);
640 			mapoff += sizeof(sizeN);
641 		} else {
642 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
643 			if (n < 0)
644 				return got_error_from_errno("read");
645 			if (n != sizeof(sizeN))
646 				return got_error(GOT_ERR_BAD_PACKFILE);
647 		}
648 		*len += sizeof(sizeN);
649 
650 		if (i == 0) {
651 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
652 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
653 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
654 		} else {
655 			size_t shift = 4 + 7 * (i - 1);
656 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
657 		}
658 		i++;
659 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
660 
661 	*type = t;
662 	*size = s;
663 	return NULL;
664 }
665 
666 static const struct got_error *
667 open_plain_object(struct got_object **obj, struct got_object_id *id,
668     uint8_t type, off_t offset, size_t size, int idx)
669 {
670 	*obj = calloc(1, sizeof(**obj));
671 	if (*obj == NULL)
672 		return got_error_from_errno("calloc");
673 
674 	(*obj)->type = type;
675 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
676 	(*obj)->pack_idx = idx;
677 	(*obj)->hdrlen = 0;
678 	(*obj)->size = size;
679 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
680 	(*obj)->pack_offset = offset;
681 
682 	return NULL;
683 }
684 
685 static const struct got_error *
686 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
687     off_t delta_offset)
688 {
689 	int64_t o = 0;
690 	uint8_t offN;
691 	int i = 0;
692 
693 	*offset = 0;
694 	*len = 0;
695 
696 	do {
697 		/* We do not support offset values which don't fit in 64 bit. */
698 		if (i > 8)
699 			return got_error(GOT_ERR_NO_SPACE);
700 
701 		if (pack->map) {
702 			size_t mapoff;
703 			mapoff = (size_t)delta_offset + *len;
704 			if (mapoff + sizeof(offN) >= pack->filesize)
705 				return got_error(GOT_ERR_PACK_OFFSET);
706 			offN = *(pack->map + mapoff);
707 		} else {
708 			ssize_t n;
709 			n = read(pack->fd, &offN, sizeof(offN));
710 			if (n < 0)
711 				return got_error_from_errno("read");
712 			if (n != sizeof(offN))
713 				return got_error(GOT_ERR_BAD_PACKFILE);
714 		}
715 		*len += sizeof(offN);
716 
717 		if (i == 0)
718 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
719 		else {
720 			o++;
721 			o <<= 7;
722 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
723 		}
724 		i++;
725 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
726 
727 	*offset = o;
728 	return NULL;
729 }
730 
731 const struct got_error *
732 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
733     struct got_pack *pack, off_t offset, int tslen)
734 {
735 	const struct got_error *err;
736 	int64_t negoffset;
737 	size_t negofflen;
738 
739 	*len = 0;
740 
741 	err = parse_negative_offset(&negoffset, &negofflen, pack,
742 	    offset + tslen);
743 	if (err)
744 		return err;
745 
746 	/* Compute the base object's offset (must be in the same pack file). */
747 	*base_offset = (offset - negoffset);
748 	if (*base_offset <= 0)
749 		return got_error(GOT_ERR_BAD_PACKFILE);
750 
751 	*len = negofflen;
752 	return NULL;
753 }
754 
755 static const struct got_error *
756 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
757     size_t delta_data_offset, struct got_pack *pack)
758 {
759 	const struct got_error *err = NULL;
760 
761 	if (pack->map) {
762 		if (delta_data_offset >= pack->filesize)
763 			return got_error(GOT_ERR_PACK_OFFSET);
764 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
765 		    NULL, NULL, pack->map, delta_data_offset,
766 		    pack->filesize - delta_data_offset);
767 	} else {
768 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
769 			return got_error_from_errno("lseek");
770 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
771 		    NULL, 0, pack->fd);
772 	}
773 	return err;
774 }
775 
776 static const struct got_error *
777 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
778     int delta_type, size_t delta_size, size_t delta_data_offset)
779 {
780 	struct got_delta *delta;
781 
782 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
783 	    delta_data_offset);
784 	if (delta == NULL)
785 		return got_error_from_errno("got_delta_open");
786 	/* delta is freed in got_object_close() */
787 	deltas->nentries++;
788 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
789 	return NULL;
790 }
791 
792 static const struct got_error *
793 resolve_offset_delta(struct got_delta_chain *deltas,
794     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
795     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
796 
797 {
798 	const struct got_error *err;
799 	off_t base_offset;
800 	uint8_t base_type;
801 	uint64_t base_size;
802 	size_t base_tslen;
803 	off_t delta_data_offset;
804 	size_t consumed;
805 
806 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
807 	    delta_offset, tslen);
808 	if (err)
809 		return err;
810 
811 	delta_data_offset = delta_offset + tslen + consumed;
812 	if (delta_data_offset >= pack->filesize)
813 		return got_error(GOT_ERR_PACK_OFFSET);
814 
815 	if (pack->map == NULL) {
816 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
817 		if (delta_data_offset == -1)
818 			return got_error_from_errno("lseek");
819 	}
820 
821 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
822 	    delta_data_offset);
823 	if (err)
824 		return err;
825 
826 	/* An offset delta must be in the same packfile. */
827 	if (base_offset >= pack->filesize)
828 		return got_error(GOT_ERR_PACK_OFFSET);
829 
830 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
831 	    &base_tslen, pack, base_offset);
832 	if (err)
833 		return err;
834 
835 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
836 	    base_tslen, base_type, base_size, recursion - 1);
837 }
838 
839 const struct got_error *
840 got_pack_parse_ref_delta(struct got_object_id *id,
841     struct got_pack *pack, off_t delta_offset, int tslen)
842 {
843 	if (pack->map) {
844 		size_t mapoff = delta_offset + tslen;
845 		if (mapoff + sizeof(*id) >= pack->filesize)
846 			return got_error(GOT_ERR_PACK_OFFSET);
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 	} else {
1122 		if (fseeko(base_file, 0L, SEEK_SET) == -1)
1123 			return got_error_from_errno("fseeko");
1124 		if (fseeko(accum_file, 0L, SEEK_SET) == -1)
1125 			return got_error_from_errno("fseeko");
1126 	}
1127 
1128 	/* Deltas are ordered in ascending order. */
1129 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1130 		int cached = 1;
1131 		if (n == 0) {
1132 			size_t mapoff;
1133 			off_t delta_data_offset;
1134 
1135 			/* Plain object types are the delta base. */
1136 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1137 			    delta->type != GOT_OBJ_TYPE_TREE &&
1138 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1139 			    delta->type != GOT_OBJ_TYPE_TAG) {
1140 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1141 				goto done;
1142 			}
1143 
1144 			delta_data_offset = delta->offset + delta->tslen;
1145 			if (delta_data_offset >= pack->filesize) {
1146 				err = got_error(GOT_ERR_PACK_OFFSET);
1147 				goto done;
1148 			}
1149 			if (pack->map == NULL) {
1150 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1151 				    == -1) {
1152 					err = got_error_from_errno("lseek");
1153 					goto done;
1154 				}
1155 			}
1156 			if (base_file) {
1157 				if (pack->map) {
1158 					mapoff = (size_t)delta_data_offset;
1159 					err = got_inflate_to_file_mmap(
1160 					    &base_bufsz, NULL, NULL, pack->map,
1161 					    mapoff, pack->filesize - mapoff,
1162 					    base_file);
1163 				} else
1164 					err = got_inflate_to_file_fd(
1165 					    &base_bufsz, NULL, NULL, pack->fd,
1166 					    base_file);
1167 			} else {
1168 				if (pack->map) {
1169 					mapoff = (size_t)delta_data_offset;
1170 					err = got_inflate_to_mem_mmap(&base_buf,
1171 					    &base_bufsz, NULL, NULL,
1172 					    pack->map, mapoff,
1173 					    pack->filesize - mapoff);
1174 				} else
1175 					err = got_inflate_to_mem_fd(&base_buf,
1176 					    &base_bufsz, NULL, NULL, max_size,
1177 					    pack->fd);
1178 			}
1179 			if (err)
1180 				goto done;
1181 			n++;
1182 			if (base_file)
1183 				rewind(base_file);
1184 			continue;
1185 		}
1186 
1187 		got_delta_cache_get(&delta_buf, &delta_len,
1188 		    pack->delta_cache, delta->data_offset);
1189 		if (delta_buf == NULL) {
1190 			cached = 0;
1191 			err = read_delta_data(&delta_buf, &delta_len,
1192 			    delta->data_offset, pack);
1193 			if (err)
1194 				goto done;
1195 			err = got_delta_cache_add(pack->delta_cache,
1196 			    delta->data_offset, delta_buf, delta_len);
1197 			if (err == NULL)
1198 				cached = 1;
1199 			else if (err->code != GOT_ERR_NO_SPACE) {
1200 				free(delta_buf);
1201 				goto done;
1202 			}
1203 		}
1204 		if (base_buf) {
1205 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1206 			    delta_buf, delta_len, accum_buf,
1207 			    &accum_size, max_size);
1208 			n++;
1209 		} else {
1210 			err = got_delta_apply(base_file, delta_buf,
1211 			    delta_len,
1212 			    /* Final delta application writes to output file. */
1213 			    ++n < deltas->nentries ? accum_file : outfile,
1214 			    &accum_size);
1215 		}
1216 		if (!cached)
1217 			free(delta_buf);
1218 		if (err)
1219 			goto done;
1220 
1221 		if (n < deltas->nentries) {
1222 			/* Accumulated delta becomes the new base. */
1223 			if (base_buf) {
1224 				uint8_t *tmp = accum_buf;
1225 				/*
1226 				 * Base buffer switches roles with accumulation
1227 				 * buffer. Ensure it can hold the largest
1228 				 * result in the delta chain. The initial
1229 				 * allocation might have been smaller.
1230 				 */
1231 				if (base_bufsz < max_size) {
1232 					uint8_t *p;
1233 					p = reallocarray(base_buf, 1, max_size);
1234 					if (p == NULL) {
1235 						err = got_error_from_errno(
1236 						    "reallocarray");
1237 						goto done;
1238 					}
1239 					base_buf = p;
1240 					base_bufsz = max_size;
1241 				}
1242 				accum_buf = base_buf;
1243 				base_buf = tmp;
1244 			} else {
1245 				FILE *tmp = accum_file;
1246 				accum_file = base_file;
1247 				base_file = tmp;
1248 				rewind(base_file);
1249 				rewind(accum_file);
1250 			}
1251 		}
1252 	}
1253 
1254 done:
1255 	free(base_buf);
1256 	if (accum_buf) {
1257 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1258 		free(accum_buf);
1259 		if (len != accum_size)
1260 			err = got_ferror(outfile, GOT_ERR_IO);
1261 	}
1262 	rewind(outfile);
1263 	if (err == NULL)
1264 		*result_size = accum_size;
1265 	return err;
1266 }
1267 
1268 const struct got_error *
1269 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1270     struct got_delta_chain *deltas, struct got_pack *pack)
1271 {
1272 	const struct got_error *err = NULL;
1273 	struct got_delta *delta;
1274 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1275 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1276 	uint64_t max_size;
1277 	int n = 0;
1278 
1279 	*outbuf = NULL;
1280 	*outlen = 0;
1281 
1282 	if (STAILQ_EMPTY(&deltas->entries))
1283 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1284 
1285 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1286 	if (err)
1287 		return err;
1288 	accum_buf = malloc(max_size);
1289 	if (accum_buf == NULL)
1290 		return got_error_from_errno("malloc");
1291 
1292 	/* Deltas are ordered in ascending order. */
1293 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1294 		int cached = 1;
1295 		if (n == 0) {
1296 			size_t delta_data_offset;
1297 
1298 			/* Plain object types are the delta base. */
1299 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1300 			    delta->type != GOT_OBJ_TYPE_TREE &&
1301 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1302 			    delta->type != GOT_OBJ_TYPE_TAG) {
1303 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1304 				goto done;
1305 			}
1306 
1307 			delta_data_offset = delta->offset + delta->tslen;
1308 			if (delta_data_offset >= pack->filesize) {
1309 				err = got_error(GOT_ERR_PACK_OFFSET);
1310 				goto done;
1311 			}
1312 			if (pack->map) {
1313 				size_t mapoff = (size_t)delta_data_offset;
1314 				err = got_inflate_to_mem_mmap(&base_buf,
1315 				    &base_bufsz, NULL, NULL, pack->map,
1316 				    mapoff, pack->filesize - mapoff);
1317 			} else {
1318 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1319 				    == -1) {
1320 					err = got_error_from_errno("lseek");
1321 					goto done;
1322 				}
1323 				err = got_inflate_to_mem_fd(&base_buf,
1324 				    &base_bufsz, NULL, NULL, max_size,
1325 				    pack->fd);
1326 			}
1327 			if (err)
1328 				goto done;
1329 			n++;
1330 			continue;
1331 		}
1332 
1333 		got_delta_cache_get(&delta_buf, &delta_len,
1334 		    pack->delta_cache, delta->data_offset);
1335 		if (delta_buf == NULL) {
1336 			cached = 0;
1337 			err = read_delta_data(&delta_buf, &delta_len,
1338 			    delta->data_offset, pack);
1339 			if (err)
1340 				goto done;
1341 			err = got_delta_cache_add(pack->delta_cache,
1342 			    delta->data_offset, delta_buf, delta_len);
1343 			if (err == NULL)
1344 				cached = 1;
1345 			else if (err->code != GOT_ERR_NO_SPACE) {
1346 				free(delta_buf);
1347 				goto done;
1348 			}
1349 		}
1350 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1351 		    delta_buf, delta_len, accum_buf,
1352 		    &accum_size, max_size);
1353 		if (!cached)
1354 			free(delta_buf);
1355 		n++;
1356 		if (err)
1357 			goto done;
1358 
1359 		if (n < deltas->nentries) {
1360 			/* Accumulated delta becomes the new base. */
1361 			uint8_t *tmp = accum_buf;
1362 			/*
1363 			 * Base buffer switches roles with accumulation buffer.
1364 			 * Ensure it can hold the largest result in the delta
1365 			 * chain. Initial allocation might have been smaller.
1366 			 */
1367 			if (base_bufsz < max_size) {
1368 				uint8_t *p;
1369 				p = reallocarray(base_buf, 1, max_size);
1370 				if (p == NULL) {
1371 					err = got_error_from_errno(
1372 					    "reallocarray");
1373 					goto done;
1374 				}
1375 				base_buf = p;
1376 				base_bufsz = max_size;
1377 			}
1378 			accum_buf = base_buf;
1379 			base_buf = tmp;
1380 		}
1381 	}
1382 
1383 done:
1384 	free(base_buf);
1385 	if (err) {
1386 		free(accum_buf);
1387 		*outbuf = NULL;
1388 		*outlen = 0;
1389 	} else {
1390 		*outbuf = accum_buf;
1391 		*outlen = accum_size;
1392 	}
1393 	return err;
1394 }
1395 
1396 const struct got_error *
1397 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1398     FILE *outfile, FILE *base_file, FILE *accum_file)
1399 {
1400 	const struct got_error *err = NULL;
1401 
1402 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1403 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1404 
1405 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1406 		if (obj->pack_offset >= pack->filesize)
1407 			return got_error(GOT_ERR_PACK_OFFSET);
1408 
1409 		if (pack->map) {
1410 			size_t mapoff = (size_t)obj->pack_offset;
1411 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1412 			    pack->map, mapoff, pack->filesize - mapoff,
1413 			    outfile);
1414 		} else {
1415 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1416 				return got_error_from_errno("lseek");
1417 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1418 			    pack->fd, outfile);
1419 		}
1420 	} else
1421 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1422 		    &obj->deltas, pack, outfile, base_file, accum_file);
1423 
1424 	return err;
1425 }
1426 
1427 const struct got_error *
1428 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1429     struct got_object *obj, struct got_pack *pack)
1430 {
1431 	const struct got_error *err = NULL;
1432 
1433 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1434 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1435 
1436 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1437 		if (obj->pack_offset >= pack->filesize)
1438 			return got_error(GOT_ERR_PACK_OFFSET);
1439 		if (pack->map) {
1440 			size_t mapoff = (size_t)obj->pack_offset;
1441 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1442 			    pack->map, mapoff, pack->filesize - mapoff);
1443 		} else {
1444 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1445 				return got_error_from_errno("lseek");
1446 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1447 			    obj->size, pack->fd);
1448 		}
1449 	} else
1450 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1451 		    pack);
1452 
1453 	return err;
1454 }