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Date:: Thu Sep 24 00:28:58 2020 UTC
Message:: fix matching the object ID of the first object in a pack index An object ID which appears first in a pack index was wrongly ignored by got_packidx_match_id_str_prefix(). The result was a spurious "object not found" error when this object ID was passed on the command line. Reported by jrick on freenode who was lucky enough to this edge case!
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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)
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 (be32toh(*h->magic) != 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 (be32toh(*h->version) != 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 	for (i = 0; i < nobj; i++) {
262 		uint32_t o = be32toh(h->offsets[i]);
263 		if (o & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX)
264 			p->nlargeobj++;
265 	}
266 	if (p->nlargeobj == 0)
267 		goto checksum;
268 
269 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
270 		err = got_error(GOT_ERR_BAD_PACKIDX);
271 		goto done;
272 	}
273 	if (p->map)
274 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
275 	else {
276 		h->large_offsets = malloc(p->nlargeobj *
277 		    sizeof(*h->large_offsets));
278 		if (h->large_offsets == NULL) {
279 			err = got_error_from_errno("malloc");
280 			goto done;
281 		}
282 		n = read(p->fd, h->large_offsets,
283 		    p->nlargeobj * sizeof(*h->large_offsets));
284 		if (n < 0)
285 			err = got_error_from_errno("read");
286 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
287 			err = got_error(GOT_ERR_BAD_PACKIDX);
288 			goto done;
289 		}
290 	}
291 	if (verify)
292 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
293 		    p->nlargeobj * sizeof(*h->large_offsets));
294 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
295 	offset += p->nlargeobj * sizeof(*h->large_offsets);
296 
297 checksum:
298 	if (remain < sizeof(*h->trailer)) {
299 		err = got_error(GOT_ERR_BAD_PACKIDX);
300 		goto done;
301 	}
302 	if (p->map)
303 		h->trailer =
304 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
305 	else {
306 		h->trailer = malloc(sizeof(*h->trailer));
307 		if (h->trailer == NULL) {
308 			err = got_error_from_errno("malloc");
309 			goto done;
310 		}
311 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
312 		if (n < 0)
313 			err = got_error_from_errno("read");
314 		else if (n != sizeof(*h->trailer)) {
315 			err = got_error(GOT_ERR_BAD_PACKIDX);
316 			goto done;
317 		}
318 	}
319 	if (verify) {
320 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
321 		SHA1Final(sha1, &ctx);
322 		if (memcmp(h->trailer->packidx_sha1, sha1,
323 		    SHA1_DIGEST_LENGTH) != 0)
324 			err = got_error(GOT_ERR_PACKIDX_CSUM);
325 	}
326 done:
327 	return err;
328 }
329 
330 const struct got_error *
331 got_packidx_open(struct got_packidx **packidx, const char *path, int verify)
332 {
333 	const struct got_error *err = NULL;
334 	struct got_packidx *p;
335 	struct stat sb;
336 
337 	*packidx = NULL;
338 
339 	p = calloc(1, sizeof(*p));
340 	if (p == NULL)
341 		return got_error_from_errno("calloc");
342 
343 	p->fd = open(path, O_RDONLY | O_NOFOLLOW);
344 	if (p->fd == -1) {
345 		err = got_error_from_errno2("open", path);
346 		free(p);
347 		return err;
348 	}
349 
350 	if (fstat(p->fd, &sb) != 0) {
351 		err = got_error_from_errno2("fstat", path);
352 		close(p->fd);
353 		free(p);
354 		return err;
355 	}
356 	p->len = sb.st_size;
357 	if (p->len < sizeof(p->hdr)) {
358 		err = got_error(GOT_ERR_BAD_PACKIDX);
359 		close(p->fd);
360 		free(p);
361 		return err;
362 	}
363 
364 	p->path_packidx = strdup(path);
365 	if (p->path_packidx == NULL) {
366 		err = got_error_from_errno("strdup");
367 		goto done;
368 	}
369 
370 #ifndef GOT_PACK_NO_MMAP
371 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
372 	if (p->map == MAP_FAILED) {
373 		if (errno != ENOMEM) {
374 			err = got_error_from_errno("mmap");
375 			goto done;
376 		}
377 		p->map = NULL; /* fall back to read(2) */
378 	}
379 #endif
380 
381 	err = got_packidx_init_hdr(p, verify);
382 done:
383 	if (err)
384 		got_packidx_close(p);
385 	else
386 		*packidx = p;
387 
388 	return err;
389 }
390 
391 const struct got_error *
392 got_packidx_close(struct got_packidx *packidx)
393 {
394 	const struct got_error *err = NULL;
395 
396 	free(packidx->path_packidx);
397 	if (packidx->map) {
398 		if (munmap(packidx->map, packidx->len) == -1)
399 			err = got_error_from_errno("munmap");
400 	} else {
401 		free(packidx->hdr.magic);
402 		free(packidx->hdr.version);
403 		free(packidx->hdr.fanout_table);
404 		free(packidx->hdr.sorted_ids);
405 		free(packidx->hdr.crc32);
406 		free(packidx->hdr.offsets);
407 		free(packidx->hdr.large_offsets);
408 		free(packidx->hdr.trailer);
409 	}
410 	if (close(packidx->fd) != 0 && err == NULL)
411 		err = got_error_from_errno("close");
412 	free(packidx);
413 
414 	return err;
415 }
416 
417 static off_t
418 get_object_offset(struct got_packidx *packidx, int idx)
419 {
420 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
421 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
422 		uint64_t loffset;
423 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
424 		if (idx < 0 || idx >= packidx->nlargeobj ||
425 		    packidx->hdr.large_offsets == NULL)
426 			return -1;
427 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
428 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
429 	}
430 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
431 }
432 
433 int
434 got_packidx_get_object_idx(struct got_packidx *packidx, struct got_object_id *id)
435 {
436 	u_int8_t id0 = id->sha1[0];
437 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
438 	int left = 0, right = totobj - 1;
439 
440 	if (id0 > 0)
441 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
442 
443 	while (left <= right) {
444 		struct got_packidx_object_id *oid;
445 		int i, cmp;
446 
447 		i = ((left + right) / 2);
448 		oid = &packidx->hdr.sorted_ids[i];
449 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
450 		if (cmp == 0)
451 			return i;
452 		else if (cmp > 0)
453 			left = i + 1;
454 		else if (cmp < 0)
455 			right = i - 1;
456 	}
457 
458 	return -1;
459 }
460 
461 const struct got_error *
462 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
463     struct got_packidx *packidx, const char *id_str_prefix)
464 {
465 	const struct got_error *err = NULL;
466 	u_int8_t id0;
467 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
468 	char hex[3];
469 	size_t prefix_len = strlen(id_str_prefix);
470 	struct got_packidx_object_id *oid;
471 	uint32_t i;
472 
473 	SIMPLEQ_INIT(matched_ids);
474 
475 	if (prefix_len < 2)
476 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
477 
478 	hex[0] = id_str_prefix[0];
479 	hex[1] = id_str_prefix[1];
480 	hex[2] = '\0';
481 	if (!got_parse_xdigit(&id0, hex))
482 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
483 
484 	i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
485 	oid = &packidx->hdr.sorted_ids[i];
486 	while (i < totobj && oid->sha1[0] == id0) {
487 		char id_str[SHA1_DIGEST_STRING_LENGTH];
488 		struct got_object_qid *qid;
489 		int cmp;
490 
491 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
492 		        return got_error(GOT_ERR_NO_SPACE);
493 
494 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
495 		if (cmp < 0) {
496 			oid = &packidx->hdr.sorted_ids[++i];
497 			continue;
498 		} else if (cmp > 0)
499 			break;
500 
501 		err = got_object_qid_alloc_partial(&qid);
502 		if (err)
503 			break;
504 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
505 		SIMPLEQ_INSERT_TAIL(matched_ids, qid, entry);
506 
507 		oid = &packidx->hdr.sorted_ids[++i];
508 	}
509 
510 	if (err)
511 		got_object_id_queue_free(matched_ids);
512 	return err;
513 }
514 
515 const struct got_error *
516 got_pack_stop_privsep_child(struct got_pack *pack)
517 {
518 	const struct got_error *err = NULL;
519 
520 	if (pack->privsep_child == NULL)
521 		return NULL;
522 
523 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
524 	if (err)
525 		return err;
526 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
527 	if (close(pack->privsep_child->imsg_fd) != 0 && err == NULL)
528 		err = got_error_from_errno("close");
529 	free(pack->privsep_child);
530 	pack->privsep_child = NULL;
531 	return err;
532 }
533 
534 const struct got_error *
535 got_pack_close(struct got_pack *pack)
536 {
537 	const struct got_error *err = NULL;
538 
539 	err = got_pack_stop_privsep_child(pack);
540 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
541 		err = got_error_from_errno("munmap");
542 	if (pack->fd != -1 && close(pack->fd) != 0 && err == NULL)
543 		err = got_error_from_errno("close");
544 	pack->fd = -1;
545 	free(pack->path_packfile);
546 	pack->path_packfile = NULL;
547 	pack->filesize = 0;
548 	if (pack->delta_cache) {
549 		got_delta_cache_free(pack->delta_cache);
550 		pack->delta_cache = NULL;
551 	}
552 
553 	return err;
554 }
555 
556 const struct got_error *
557 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
558     struct got_pack *pack, off_t offset)
559 {
560 	uint8_t t = 0;
561 	uint64_t s = 0;
562 	uint8_t sizeN;
563 	size_t mapoff = 0;
564 	int i = 0;
565 
566 	*len = 0;
567 
568 	if (offset >= pack->filesize)
569 		return got_error(GOT_ERR_PACK_OFFSET);
570 
571 	if (pack->map) {
572 		mapoff = (size_t)offset;
573 	} else {
574 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
575 			return got_error_from_errno("lseek");
576 	}
577 
578 	do {
579 		/* We do not support size values which don't fit in 64 bit. */
580 		if (i > 9)
581 			return got_error(GOT_ERR_NO_SPACE);
582 
583 		if (pack->map) {
584 			sizeN = *(pack->map + mapoff);
585 			mapoff += sizeof(sizeN);
586 		} else {
587 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
588 			if (n < 0)
589 				return got_error_from_errno("read");
590 			if (n != sizeof(sizeN))
591 				return got_error(GOT_ERR_BAD_PACKFILE);
592 		}
593 		*len += sizeof(sizeN);
594 
595 		if (i == 0) {
596 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
597 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
598 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
599 		} else {
600 			size_t shift = 4 + 7 * (i - 1);
601 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
602 		}
603 		i++;
604 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
605 
606 	*type = t;
607 	*size = s;
608 	return NULL;
609 }
610 
611 static const struct got_error *
612 open_plain_object(struct got_object **obj, struct got_object_id *id,
613     uint8_t type, off_t offset, size_t size, int idx)
614 {
615 	*obj = calloc(1, sizeof(**obj));
616 	if (*obj == NULL)
617 		return got_error_from_errno("calloc");
618 
619 	(*obj)->type = type;
620 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
621 	(*obj)->pack_idx = idx;
622 	(*obj)->hdrlen = 0;
623 	(*obj)->size = size;
624 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
625 	(*obj)->pack_offset = offset;
626 
627 	return NULL;
628 }
629 
630 static const struct got_error *
631 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
632     off_t delta_offset)
633 {
634 	int64_t o = 0;
635 	uint8_t offN;
636 	int i = 0;
637 
638 	*offset = 0;
639 	*len = 0;
640 
641 	do {
642 		/* We do not support offset values which don't fit in 64 bit. */
643 		if (i > 8)
644 			return got_error(GOT_ERR_NO_SPACE);
645 
646 		if (pack->map) {
647 			size_t mapoff;
648 			if (delta_offset >= pack->filesize)
649 				return got_error(GOT_ERR_PACK_OFFSET);
650 			mapoff = (size_t)delta_offset + *len;
651 			offN = *(pack->map + mapoff);
652 		} else {
653 			ssize_t n;
654 			n = read(pack->fd, &offN, sizeof(offN));
655 			if (n < 0)
656 				return got_error_from_errno("read");
657 			if (n != sizeof(offN))
658 				return got_error(GOT_ERR_BAD_PACKFILE);
659 		}
660 		*len += sizeof(offN);
661 
662 		if (i == 0)
663 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
664 		else {
665 			o++;
666 			o <<= 7;
667 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
668 		}
669 		i++;
670 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
671 
672 	*offset = o;
673 	return NULL;
674 }
675 
676 const struct got_error *
677 got_pack_parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
678     off_t offset, int tslen)
679 {
680 	const struct got_error *err;
681 	int64_t negoffset;
682 	size_t negofflen;
683 
684 	*len = 0;
685 
686 	err = parse_negative_offset(&negoffset, &negofflen, pack,
687 	    offset + tslen);
688 	if (err)
689 		return err;
690 
691 	/* Compute the base object's offset (must be in the same pack file). */
692 	*base_offset = (offset - negoffset);
693 	if (*base_offset <= 0)
694 		return got_error(GOT_ERR_BAD_PACKFILE);
695 
696 	*len = negofflen;
697 	return NULL;
698 }
699 
700 static const struct got_error *
701 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
702     size_t delta_data_offset, struct got_pack *pack)
703 {
704 	const struct got_error *err = NULL;
705 
706 	if (pack->map) {
707 		if (delta_data_offset >= pack->filesize)
708 			return got_error(GOT_ERR_PACK_OFFSET);
709 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
710 		    NULL, NULL, pack->map, delta_data_offset,
711 		    pack->filesize - delta_data_offset);
712 	} else {
713 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
714 			return got_error_from_errno("lseek");
715 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
716 		    NULL, 0, pack->fd);
717 	}
718 	return err;
719 }
720 
721 static const struct got_error *
722 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
723     int delta_type, size_t delta_size, size_t delta_data_offset)
724 {
725 	struct got_delta *delta;
726 
727 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
728 	    delta_data_offset);
729 	if (delta == NULL)
730 		return got_error_from_errno("got_delta_open");
731 	/* delta is freed in got_object_close() */
732 	deltas->nentries++;
733 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
734 	return NULL;
735 }
736 
737 static const struct got_error *
738 resolve_offset_delta(struct got_delta_chain *deltas,
739     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
740     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
741 
742 {
743 	const struct got_error *err;
744 	off_t base_offset;
745 	uint8_t base_type;
746 	uint64_t base_size;
747 	size_t base_tslen;
748 	off_t delta_data_offset;
749 	size_t consumed;
750 
751 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
752 	    delta_offset, tslen);
753 	if (err)
754 		return err;
755 
756 	delta_data_offset = delta_offset + tslen + consumed;
757 	if (delta_data_offset >= pack->filesize)
758 		return got_error(GOT_ERR_PACK_OFFSET);
759 
760 	if (pack->map == NULL) {
761 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
762 		if (delta_data_offset == -1)
763 			return got_error_from_errno("lseek");
764 	}
765 
766 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
767 	    delta_data_offset);
768 	if (err)
769 		return err;
770 
771 	/* An offset delta must be in the same packfile. */
772 	if (base_offset >= pack->filesize)
773 		return got_error(GOT_ERR_PACK_OFFSET);
774 
775 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
776 	    &base_tslen, pack, base_offset);
777 	if (err)
778 		return err;
779 
780 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
781 	    base_tslen, base_type, base_size, recursion - 1);
782 }
783 
784 static const struct got_error *
785 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
786     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
787     size_t delta_size, unsigned int recursion)
788 {
789 	const struct got_error *err;
790 	struct got_object_id id;
791 	int idx;
792 	off_t base_offset;
793 	uint8_t base_type;
794 	uint64_t base_size;
795 	size_t base_tslen;
796 	off_t delta_data_offset;
797 
798 	if (delta_offset + tslen >= pack->filesize)
799 		return got_error(GOT_ERR_PACK_OFFSET);
800 
801 	if (pack->map) {
802 		size_t mapoff = delta_offset + tslen;
803 		memcpy(&id, pack->map + mapoff, sizeof(id));
804 		mapoff += sizeof(id);
805 		delta_data_offset = (off_t)mapoff;
806 	} else {
807 		ssize_t n;
808 		n = read(pack->fd, &id, sizeof(id));
809 		if (n < 0)
810 			return got_error_from_errno("read");
811 		if (n != sizeof(id))
812 			return got_error(GOT_ERR_BAD_PACKFILE);
813 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
814 		if (delta_data_offset == -1)
815 			return got_error_from_errno("lseek");
816 	}
817 
818 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
819 	    delta_data_offset);
820 	if (err)
821 		return err;
822 
823 	/* Delta base must be in the same pack file. */
824 	idx = got_packidx_get_object_idx(packidx, &id);
825 	if (idx == -1)
826 		return got_error(GOT_ERR_NO_OBJ);
827 
828 	base_offset = get_object_offset(packidx, idx);
829 	if (base_offset == (uint64_t)-1)
830 		return got_error(GOT_ERR_BAD_PACKIDX);
831 
832 	if (base_offset >= pack->filesize)
833 		return got_error(GOT_ERR_PACK_OFFSET);
834 
835 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
836 	    &base_tslen, pack, base_offset);
837 	if (err)
838 		return err;
839 
840 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
841 	    base_tslen, base_type, base_size, recursion - 1);
842 }
843 
844 const struct got_error *
845 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
846     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
847     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
848 {
849 	const struct got_error *err = NULL;
850 
851 	if (--recursion == 0)
852 		return got_error(GOT_ERR_RECURSION);
853 
854 	switch (delta_type) {
855 	case GOT_OBJ_TYPE_COMMIT:
856 	case GOT_OBJ_TYPE_TREE:
857 	case GOT_OBJ_TYPE_BLOB:
858 	case GOT_OBJ_TYPE_TAG:
859 		/* Plain types are the final delta base. Recursion ends. */
860 		err = add_delta(deltas, delta_offset, tslen, delta_type,
861 		    delta_size, 0);
862 		break;
863 	case GOT_OBJ_TYPE_OFFSET_DELTA:
864 		err = resolve_offset_delta(deltas, packidx, pack,
865 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
866 		break;
867 	case GOT_OBJ_TYPE_REF_DELTA:
868 		err = resolve_ref_delta(deltas, packidx, pack,
869 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
870 		break;
871 	default:
872 		return got_error(GOT_ERR_OBJ_TYPE);
873 	}
874 
875 	return err;
876 }
877 
878 static const struct got_error *
879 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
880     struct got_pack *pack, struct got_object_id *id, off_t offset,
881     size_t tslen, int delta_type, size_t delta_size, int idx)
882 {
883 	const struct got_error *err = NULL;
884 	int resolved_type;
885 
886 	*obj = calloc(1, sizeof(**obj));
887 	if (*obj == NULL)
888 		return got_error_from_errno("calloc");
889 
890 	(*obj)->flags = 0;
891 	(*obj)->hdrlen = 0;
892 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
893 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
894 	(*obj)->pack_offset = offset + tslen;
895 
896 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
897 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
898 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
899 	(*obj)->pack_idx = idx;
900 
901 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
902 	    offset, tslen, delta_type, delta_size,
903 	    GOT_DELTA_CHAIN_RECURSION_MAX);
904 	if (err)
905 		goto done;
906 
907 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
908 	if (err)
909 		goto done;
910 	(*obj)->type = resolved_type;
911 done:
912 	if (err) {
913 		got_object_close(*obj);
914 		*obj = NULL;
915 	}
916 	return err;
917 }
918 
919 const struct got_error *
920 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
921     struct got_packidx *packidx, int idx, struct got_object_id *id)
922 {
923 	const struct got_error *err = NULL;
924 	off_t offset;
925 	uint8_t type;
926 	uint64_t size;
927 	size_t tslen;
928 
929 	*obj = NULL;
930 
931 	offset = get_object_offset(packidx, idx);
932 	if (offset == (uint64_t)-1)
933 		return got_error(GOT_ERR_BAD_PACKIDX);
934 
935 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
936 	    pack, offset);
937 	if (err)
938 		return err;
939 
940 	switch (type) {
941 	case GOT_OBJ_TYPE_COMMIT:
942 	case GOT_OBJ_TYPE_TREE:
943 	case GOT_OBJ_TYPE_BLOB:
944 	case GOT_OBJ_TYPE_TAG:
945 		err = open_plain_object(obj, id, type, offset + tslen,
946 		    size, idx);
947 		break;
948 	case GOT_OBJ_TYPE_OFFSET_DELTA:
949 	case GOT_OBJ_TYPE_REF_DELTA:
950 		err = open_delta_object(obj, packidx, pack, id, offset,
951 		    tslen, type, size, idx);
952 		break;
953 	default:
954 		err = got_error(GOT_ERR_OBJ_TYPE);
955 		break;
956 	}
957 
958 	return err;
959 }
960 
961 const struct got_error *
962 got_pack_get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
963     struct got_pack *pack)
964 {
965 	struct got_delta *delta;
966 	uint64_t base_size = 0, result_size = 0;
967 
968 	*max_size = 0;
969 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
970 		/* Plain object types are the delta base. */
971 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
972 		    delta->type != GOT_OBJ_TYPE_TREE &&
973 		    delta->type != GOT_OBJ_TYPE_BLOB &&
974 		    delta->type != GOT_OBJ_TYPE_TAG) {
975 			const struct got_error *err;
976 			uint8_t *delta_buf;
977 			size_t delta_len;
978 			int cached = 1;
979 
980 			got_delta_cache_get(&delta_buf, &delta_len,
981 			    pack->delta_cache, delta->data_offset);
982 			if (delta_buf == NULL) {
983 				cached = 0;
984 				err = read_delta_data(&delta_buf, &delta_len,
985 				    delta->data_offset, pack);
986 				if (err)
987 					return err;
988 				err = got_delta_cache_add(pack->delta_cache,
989 				    delta->data_offset, delta_buf, delta_len);
990 				if (err == NULL)
991 					cached = 1;
992 				else if (err->code != GOT_ERR_NO_SPACE) {
993 					free(delta_buf);
994 					return err;
995 				}
996 			}
997 			err = got_delta_get_sizes(&base_size, &result_size,
998 			    delta_buf, delta_len);
999 			if (!cached)
1000 				free(delta_buf);
1001 			if (err)
1002 				return err;
1003 		} else
1004 			base_size = delta->size;
1005 		if (base_size > *max_size)
1006 			*max_size = base_size;
1007 		if (result_size > *max_size)
1008 			*max_size = result_size;
1009 	}
1010 
1011 	return NULL;
1012 }
1013 
1014 const struct got_error *
1015 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1016     struct got_pack *pack)
1017 {
1018 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1019 		return got_error(GOT_ERR_OBJ_TYPE);
1020 
1021 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1022 }
1023 
1024 const struct got_error *
1025 got_pack_dump_delta_chain_to_file(size_t *result_size,
1026     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1027     FILE *base_file, FILE *accum_file)
1028 {
1029 	const struct got_error *err = NULL;
1030 	struct got_delta *delta;
1031 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1032 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1033 	uint64_t max_size;
1034 	int n = 0;
1035 
1036 	*result_size = 0;
1037 
1038 	if (SIMPLEQ_EMPTY(&deltas->entries))
1039 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1040 
1041 	/* We process small enough files entirely in memory for speed. */
1042 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1043 	if (err)
1044 		return err;
1045 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1046 		accum_buf = malloc(max_size);
1047 		if (accum_buf == NULL)
1048 			return got_error_from_errno("malloc");
1049 		base_file = NULL;
1050 		accum_file = NULL;
1051 	}
1052 
1053 	/* Deltas are ordered in ascending order. */
1054 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1055 		int cached = 1;
1056 		if (n == 0) {
1057 			size_t mapoff;
1058 			off_t delta_data_offset;
1059 
1060 			/* Plain object types are the delta base. */
1061 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1062 			    delta->type != GOT_OBJ_TYPE_TREE &&
1063 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1064 			    delta->type != GOT_OBJ_TYPE_TAG) {
1065 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1066 				goto done;
1067 			}
1068 
1069 			delta_data_offset = delta->offset + delta->tslen;
1070 			if (delta_data_offset >= pack->filesize) {
1071 				err = got_error(GOT_ERR_PACK_OFFSET);
1072 				goto done;
1073 			}
1074 			if (pack->map == NULL) {
1075 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1076 				    == -1) {
1077 					err = got_error_from_errno("lseek");
1078 					goto done;
1079 				}
1080 			}
1081 			if (base_file) {
1082 				if (pack->map) {
1083 					mapoff = (size_t)delta_data_offset;
1084 					err = got_inflate_to_file_mmap(
1085 					    &base_bufsz, NULL, NULL, pack->map,
1086 					    mapoff, pack->filesize - mapoff,
1087 					    base_file);
1088 				} else
1089 					err = got_inflate_to_file_fd(
1090 					    &base_bufsz, NULL, NULL, pack->fd,
1091 					    base_file);
1092 			} else {
1093 				if (pack->map) {
1094 					mapoff = (size_t)delta_data_offset;
1095 					err = got_inflate_to_mem_mmap(&base_buf,
1096 					    &base_bufsz, NULL, NULL,
1097 					    pack->map, mapoff,
1098 					    pack->filesize - mapoff);
1099 				} else
1100 					err = got_inflate_to_mem_fd(&base_buf,
1101 					    &base_bufsz, NULL, NULL, max_size,
1102 					    pack->fd);
1103 			}
1104 			if (err)
1105 				goto done;
1106 			n++;
1107 			if (base_file)
1108 				rewind(base_file);
1109 			continue;
1110 		}
1111 
1112 		got_delta_cache_get(&delta_buf, &delta_len,
1113 		    pack->delta_cache, delta->data_offset);
1114 		if (delta_buf == NULL) {
1115 			cached = 0;
1116 			err = read_delta_data(&delta_buf, &delta_len,
1117 			    delta->data_offset, pack);
1118 			if (err)
1119 				goto done;
1120 			err = got_delta_cache_add(pack->delta_cache,
1121 			    delta->data_offset, delta_buf, delta_len);
1122 			if (err == NULL)
1123 				cached = 1;
1124 			else if (err->code != GOT_ERR_NO_SPACE) {
1125 				free(delta_buf);
1126 				goto done;
1127 			}
1128 		}
1129 		if (base_buf) {
1130 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1131 			    delta_buf, delta_len, accum_buf,
1132 			    &accum_size, max_size);
1133 			n++;
1134 		} else {
1135 			err = got_delta_apply(base_file, delta_buf,
1136 			    delta_len,
1137 			    /* Final delta application writes to output file. */
1138 			    ++n < deltas->nentries ? accum_file : outfile,
1139 			    &accum_size);
1140 		}
1141 		if (!cached)
1142 			free(delta_buf);
1143 		if (err)
1144 			goto done;
1145 
1146 		if (n < deltas->nentries) {
1147 			/* Accumulated delta becomes the new base. */
1148 			if (base_buf) {
1149 				uint8_t *tmp = accum_buf;
1150 				/*
1151 				 * Base buffer switches roles with accumulation
1152 				 * buffer. Ensure it can hold the largest
1153 				 * result in the delta chain. The initial
1154 				 * allocation might have been smaller.
1155 				 */
1156 				if (base_bufsz < max_size) {
1157 					uint8_t *p;
1158 					p = reallocarray(base_buf, 1, max_size);
1159 					if (p == NULL) {
1160 						err = got_error_from_errno(
1161 						    "reallocarray");
1162 						goto done;
1163 					}
1164 					base_buf = p;
1165 					base_bufsz = max_size;
1166 				}
1167 				accum_buf = base_buf;
1168 				base_buf = tmp;
1169 			} else {
1170 				FILE *tmp = accum_file;
1171 				accum_file = base_file;
1172 				base_file = tmp;
1173 				rewind(base_file);
1174 				rewind(accum_file);
1175 			}
1176 		}
1177 	}
1178 
1179 done:
1180 	free(base_buf);
1181 	if (accum_buf) {
1182 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1183 		free(accum_buf);
1184 		if (len != accum_size)
1185 			err = got_ferror(outfile, GOT_ERR_IO);
1186 	}
1187 	rewind(outfile);
1188 	if (err == NULL)
1189 		*result_size = accum_size;
1190 	return err;
1191 }
1192 
1193 const struct got_error *
1194 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1195     struct got_delta_chain *deltas, struct got_pack *pack)
1196 {
1197 	const struct got_error *err = NULL;
1198 	struct got_delta *delta;
1199 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1200 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1201 	uint64_t max_size;
1202 	int n = 0;
1203 
1204 	*outbuf = NULL;
1205 	*outlen = 0;
1206 
1207 	if (SIMPLEQ_EMPTY(&deltas->entries))
1208 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1209 
1210 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1211 	if (err)
1212 		return err;
1213 	accum_buf = malloc(max_size);
1214 	if (accum_buf == NULL)
1215 		return got_error_from_errno("malloc");
1216 
1217 	/* Deltas are ordered in ascending order. */
1218 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1219 		int cached = 1;
1220 		if (n == 0) {
1221 			size_t delta_data_offset;
1222 
1223 			/* Plain object types are the delta base. */
1224 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1225 			    delta->type != GOT_OBJ_TYPE_TREE &&
1226 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1227 			    delta->type != GOT_OBJ_TYPE_TAG) {
1228 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1229 				goto done;
1230 			}
1231 
1232 			delta_data_offset = delta->offset + delta->tslen;
1233 			if (delta_data_offset >= pack->filesize) {
1234 				err = got_error(GOT_ERR_PACK_OFFSET);
1235 				goto done;
1236 			}
1237 			if (pack->map) {
1238 				size_t mapoff = (size_t)delta_data_offset;
1239 				err = got_inflate_to_mem_mmap(&base_buf,
1240 				    &base_bufsz, NULL, NULL, pack->map,
1241 				    mapoff, pack->filesize - mapoff);
1242 			} else {
1243 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1244 				    == -1) {
1245 					err = got_error_from_errno("lseek");
1246 					goto done;
1247 				}
1248 				err = got_inflate_to_mem_fd(&base_buf,
1249 				    &base_bufsz, NULL, NULL, max_size,
1250 				    pack->fd);
1251 			}
1252 			if (err)
1253 				goto done;
1254 			n++;
1255 			continue;
1256 		}
1257 
1258 		got_delta_cache_get(&delta_buf, &delta_len,
1259 		    pack->delta_cache, delta->data_offset);
1260 		if (delta_buf == NULL) {
1261 			cached = 0;
1262 			err = read_delta_data(&delta_buf, &delta_len,
1263 			    delta->data_offset, pack);
1264 			if (err)
1265 				goto done;
1266 			err = got_delta_cache_add(pack->delta_cache,
1267 			    delta->data_offset, delta_buf, delta_len);
1268 			if (err == NULL)
1269 				cached = 1;
1270 			else if (err->code != GOT_ERR_NO_SPACE) {
1271 				free(delta_buf);
1272 				goto done;
1273 			}
1274 		}
1275 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1276 		    delta_buf, delta_len, accum_buf,
1277 		    &accum_size, max_size);
1278 		if (!cached)
1279 			free(delta_buf);
1280 		n++;
1281 		if (err)
1282 			goto done;
1283 
1284 		if (n < deltas->nentries) {
1285 			/* Accumulated delta becomes the new base. */
1286 			uint8_t *tmp = accum_buf;
1287 			/*
1288 			 * Base buffer switches roles with accumulation buffer.
1289 			 * Ensure it can hold the largest result in the delta
1290 			 * chain. Initial allocation might have been smaller.
1291 			 */
1292 			if (base_bufsz < max_size) {
1293 				uint8_t *p;
1294 				p = reallocarray(base_buf, 1, max_size);
1295 				if (p == NULL) {
1296 					err = got_error_from_errno(
1297 					    "reallocarray");
1298 					goto done;
1299 				}
1300 				base_buf = p;
1301 				base_bufsz = max_size;
1302 			}
1303 			accum_buf = base_buf;
1304 			base_buf = tmp;
1305 		}
1306 	}
1307 
1308 done:
1309 	free(base_buf);
1310 	if (err) {
1311 		free(accum_buf);
1312 		*outbuf = NULL;
1313 		*outlen = 0;
1314 	} else {
1315 		*outbuf = accum_buf;
1316 		*outlen = accum_size;
1317 	}
1318 	return err;
1319 }
1320 
1321 const struct got_error *
1322 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1323     FILE *outfile, FILE *base_file, FILE *accum_file)
1324 {
1325 	const struct got_error *err = NULL;
1326 
1327 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1328 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1329 
1330 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1331 		if (obj->pack_offset >= pack->filesize)
1332 			return got_error(GOT_ERR_PACK_OFFSET);
1333 
1334 		if (pack->map) {
1335 			size_t mapoff = (size_t)obj->pack_offset;
1336 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1337 			    pack->map, mapoff, pack->filesize - mapoff,
1338 			    outfile);
1339 		} else {
1340 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1341 				return got_error_from_errno("lseek");
1342 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1343 			    pack->fd, outfile);
1344 		}
1345 	} else
1346 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1347 		    &obj->deltas, pack, outfile, base_file, accum_file);
1348 
1349 	return err;
1350 }
1351 
1352 const struct got_error *
1353 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1354     struct got_object *obj, struct got_pack *pack)
1355 {
1356 	const struct got_error *err = NULL;
1357 
1358 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1359 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1360 
1361 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1362 		if (obj->pack_offset >= pack->filesize)
1363 			return got_error(GOT_ERR_PACK_OFFSET);
1364 		if (pack->map) {
1365 			size_t mapoff = (size_t)obj->pack_offset;
1366 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1367 			    pack->map, mapoff, pack->filesize - mapoff);
1368 		} else {
1369 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1370 				return got_error_from_errno("lseek");
1371 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1372 			    obj->size, pack->fd);
1373 		}
1374 	} else
1375 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1376 		    pack);
1377 
1378 	return err;
1379 }