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Date:: Tue Jan 7 11:14:52 2020 UTC
Message:: add support for first-parent history traversal to got-read-pack
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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 <zlib.h>
33 #include <imsg.h>
34 
35 #include "got_error.h"
36 #include "got_object.h"
37 #include "got_opentemp.h"
38 #include "got_path.h"
39 
40 #include "got_lib_sha1.h"
41 #include "got_lib_delta.h"
42 #include "got_lib_delta_cache.h"
43 #include "got_lib_inflate.h"
44 #include "got_lib_object.h"
45 #include "got_lib_object_parse.h"
46 #include "got_lib_privsep.h"
47 #include "got_lib_pack.h"
48 
49 #ifndef nitems
50 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
51 #endif
52 
53 #ifndef MIN
54 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
55 #endif
56 
57 static const struct got_error *
58 verify_fanout_table(uint32_t *fanout_table)
59 {
60 	int i;
61 
62 	for (i = 0; i < 0xff - 1; i++) {
63 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
64 			return got_error(GOT_ERR_BAD_PACKIDX);
65 	}
66 
67 	return NULL;
68 }
69 
70 const struct got_error *
71 got_packidx_init_hdr(struct got_packidx *p, int verify)
72 {
73 	const struct got_error *err = NULL;
74 	struct got_packidx_v2_hdr *h;
75 	SHA1_CTX ctx;
76 	uint8_t sha1[SHA1_DIGEST_LENGTH];
77 	size_t nobj, len_fanout, len_ids, offset, remain;
78 	ssize_t n;
79 	int i;
80 
81 	SHA1Init(&ctx);
82 
83 	h = &p->hdr;
84 	offset = 0;
85 	remain = p->len;
86 
87 	if (remain < sizeof(*h->magic)) {
88 		err = got_error(GOT_ERR_BAD_PACKIDX);
89 		goto done;
90 	}
91 	if (p->map)
92 		h->magic = (uint32_t *)(p->map + offset);
93 	else {
94 		h->magic = malloc(sizeof(*h->magic));
95 		if (h->magic == NULL) {
96 			err = got_error_from_errno("malloc");
97 			goto done;
98 		}
99 		n = read(p->fd, h->magic, sizeof(*h->magic));
100 		if (n < 0) {
101 			err = got_error_from_errno("read");
102 			goto done;
103 		} else if (n != sizeof(*h->magic)) {
104 			err = got_error(GOT_ERR_BAD_PACKIDX);
105 			goto done;
106 		}
107 	}
108 	if (betoh32(*h->magic) != GOT_PACKIDX_V2_MAGIC) {
109 		err = got_error(GOT_ERR_BAD_PACKIDX);
110 		goto done;
111 	}
112 	offset += sizeof(*h->magic);
113 	remain -= sizeof(*h->magic);
114 
115 	if (verify)
116 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
117 
118 	if (remain < sizeof(*h->version)) {
119 		err = got_error(GOT_ERR_BAD_PACKIDX);
120 		goto done;
121 	}
122 	if (p->map)
123 		h->version = (uint32_t *)(p->map + offset);
124 	else {
125 		h->version = malloc(sizeof(*h->version));
126 		if (h->version == NULL) {
127 			err = got_error_from_errno("malloc");
128 			goto done;
129 		}
130 		n = read(p->fd, h->version, sizeof(*h->version));
131 		if (n < 0) {
132 			err = got_error_from_errno("read");
133 			goto done;
134 		} else if (n != sizeof(*h->version)) {
135 			err = got_error(GOT_ERR_BAD_PACKIDX);
136 			goto done;
137 		}
138 	}
139 	if (betoh32(*h->version) != GOT_PACKIDX_VERSION) {
140 		err = got_error(GOT_ERR_BAD_PACKIDX);
141 		goto done;
142 	}
143 	offset += sizeof(*h->version);
144 	remain -= sizeof(*h->version);
145 
146 	if (verify)
147 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
148 
149 	len_fanout =
150 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
151 	if (remain < len_fanout) {
152 		err = got_error(GOT_ERR_BAD_PACKIDX);
153 		goto done;
154 	}
155 	if (p->map)
156 		h->fanout_table = (uint32_t *)(p->map + offset);
157 	else {
158 		h->fanout_table = malloc(len_fanout);
159 		if (h->fanout_table == NULL) {
160 			err = got_error_from_errno("malloc");
161 			goto done;
162 		}
163 		n = read(p->fd, h->fanout_table, len_fanout);
164 		if (n < 0) {
165 			err = got_error_from_errno("read");
166 			goto done;
167 		} else if (n != len_fanout) {
168 			err = got_error(GOT_ERR_BAD_PACKIDX);
169 			goto done;
170 		}
171 	}
172 	err = verify_fanout_table(h->fanout_table);
173 	if (err)
174 		goto done;
175 	if (verify)
176 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
177 	offset += len_fanout;
178 	remain -= len_fanout;
179 
180 	nobj = betoh32(h->fanout_table[0xff]);
181 	len_ids = nobj * sizeof(*h->sorted_ids);
182 	if (len_ids <= nobj || len_ids > remain) {
183 		err = got_error(GOT_ERR_BAD_PACKIDX);
184 		goto done;
185 	}
186 	if (p->map)
187 		h->sorted_ids =
188 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
189 	else {
190 		h->sorted_ids = malloc(len_ids);
191 		if (h->sorted_ids == NULL) {
192 			err = got_error(GOT_ERR_BAD_PACKIDX);
193 			goto done;
194 		}
195 		n = read(p->fd, h->sorted_ids, len_ids);
196 		if (n < 0)
197 			err = got_error_from_errno("read");
198 		else if (n != len_ids) {
199 			err = got_error(GOT_ERR_BAD_PACKIDX);
200 			goto done;
201 		}
202 	}
203 	if (verify)
204 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
205 	offset += len_ids;
206 	remain -= len_ids;
207 
208 	if (remain < nobj * sizeof(*h->crc32)) {
209 		err = got_error(GOT_ERR_BAD_PACKIDX);
210 		goto done;
211 	}
212 	if (p->map)
213 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
214 	else {
215 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
216 		if (h->crc32 == NULL) {
217 			err = got_error_from_errno("malloc");
218 			goto done;
219 		}
220 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
221 		if (n < 0)
222 			err = got_error_from_errno("read");
223 		else if (n != nobj * sizeof(*h->crc32)) {
224 			err = got_error(GOT_ERR_BAD_PACKIDX);
225 			goto done;
226 		}
227 	}
228 	if (verify)
229 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
230 	remain -= nobj * sizeof(*h->crc32);
231 	offset += nobj * sizeof(*h->crc32);
232 
233 	if (remain < nobj * sizeof(*h->offsets)) {
234 		err = got_error(GOT_ERR_BAD_PACKIDX);
235 		goto done;
236 	}
237 	if (p->map)
238 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
239 	else {
240 		h->offsets = malloc(nobj * sizeof(*h->offsets));
241 		if (h->offsets == NULL) {
242 			err = got_error_from_errno("malloc");
243 			goto done;
244 		}
245 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
246 		if (n < 0)
247 			err = got_error_from_errno("read");
248 		else if (n != nobj * sizeof(*h->offsets)) {
249 			err = got_error(GOT_ERR_BAD_PACKIDX);
250 			goto done;
251 		}
252 	}
253 	if (verify)
254 		SHA1Update(&ctx, (uint8_t *)h->offsets,
255 		    nobj * sizeof(*h->offsets));
256 	remain -= nobj * sizeof(*h->offsets);
257 	offset += nobj * sizeof(*h->offsets);
258 
259 	/* Large file offsets are contained only in files > 2GB. */
260 	for (i = 0; i < nobj; i++) {
261 		uint32_t o = betoh32(h->offsets[i]);
262 		if (o & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX)
263 			p->nlargeobj++;
264 	}
265 	if (p->nlargeobj == 0)
266 		goto checksum;
267 
268 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
269 		err = got_error(GOT_ERR_BAD_PACKIDX);
270 		goto done;
271 	}
272 	if (p->map)
273 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
274 	else {
275 		h->large_offsets = malloc(p->nlargeobj *
276 		    sizeof(*h->large_offsets));
277 		if (h->large_offsets == NULL) {
278 			err = got_error_from_errno("malloc");
279 			goto done;
280 		}
281 		n = read(p->fd, h->large_offsets,
282 		    p->nlargeobj * sizeof(*h->large_offsets));
283 		if (n < 0)
284 			err = got_error_from_errno("read");
285 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
286 			err = got_error(GOT_ERR_BAD_PACKIDX);
287 			goto done;
288 		}
289 	}
290 	if (verify)
291 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
292 		    p->nlargeobj * sizeof(*h->large_offsets));
293 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
294 	offset += p->nlargeobj * sizeof(*h->large_offsets);
295 
296 checksum:
297 	if (remain < sizeof(*h->trailer)) {
298 		err = got_error(GOT_ERR_BAD_PACKIDX);
299 		goto done;
300 	}
301 	if (p->map)
302 		h->trailer =
303 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
304 	else {
305 		h->trailer = malloc(sizeof(*h->trailer));
306 		if (h->trailer == NULL) {
307 			err = got_error_from_errno("malloc");
308 			goto done;
309 		}
310 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
311 		if (n < 0)
312 			err = got_error_from_errno("read");
313 		else if (n != sizeof(*h->trailer)) {
314 			err = got_error(GOT_ERR_BAD_PACKIDX);
315 			goto done;
316 		}
317 	}
318 	if (verify) {
319 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
320 		SHA1Final(sha1, &ctx);
321 		if (memcmp(h->trailer->packidx_sha1, sha1,
322 		    SHA1_DIGEST_LENGTH) != 0)
323 			err = got_error(GOT_ERR_PACKIDX_CSUM);
324 	}
325 done:
326 	return err;
327 }
328 
329 const struct got_error *
330 got_packidx_open(struct got_packidx **packidx, const char *path, int verify)
331 {
332 	const struct got_error *err = NULL;
333 	struct got_packidx *p;
334 	struct stat sb;
335 
336 	*packidx = NULL;
337 
338 	p = calloc(1, sizeof(*p));
339 	if (p == NULL)
340 		return got_error_from_errno("calloc");
341 
342 	p->fd = open(path, O_RDONLY | O_NOFOLLOW);
343 	if (p->fd == -1) {
344 		err = got_error_from_errno2("open", path);
345 		free(p);
346 		return err;
347 	}
348 
349 	if (fstat(p->fd, &sb) != 0) {
350 		err = got_error_from_errno2("fstat", path);
351 		close(p->fd);
352 		free(p);
353 		return err;
354 	}
355 	p->len = sb.st_size;
356 	if (p->len < sizeof(p->hdr)) {
357 		err = got_error(GOT_ERR_BAD_PACKIDX);
358 		close(p->fd);
359 		free(p);
360 		return err;
361 	}
362 
363 	p->path_packidx = strdup(path);
364 	if (p->path_packidx == NULL) {
365 		err = got_error_from_errno("strdup");
366 		goto done;
367 	}
368 
369 #ifndef GOT_PACK_NO_MMAP
370 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
371 	if (p->map == MAP_FAILED) {
372 		if (errno != ENOMEM) {
373 			err = got_error_from_errno("mmap");
374 			goto done;
375 		}
376 		p->map = NULL; /* fall back to read(2) */
377 	}
378 #endif
379 
380 	err = got_packidx_init_hdr(p, verify);
381 done:
382 	if (err)
383 		got_packidx_close(p);
384 	else
385 		*packidx = p;
386 
387 	return err;
388 }
389 
390 const struct got_error *
391 got_packidx_close(struct got_packidx *packidx)
392 {
393 	const struct got_error *err = NULL;
394 
395 	free(packidx->path_packidx);
396 	if (packidx->map) {
397 		if (munmap(packidx->map, packidx->len) == -1)
398 			err = got_error_from_errno("munmap");
399 	} else {
400 		free(packidx->hdr.magic);
401 		free(packidx->hdr.version);
402 		free(packidx->hdr.fanout_table);
403 		free(packidx->hdr.sorted_ids);
404 		free(packidx->hdr.crc32);
405 		free(packidx->hdr.offsets);
406 		free(packidx->hdr.large_offsets);
407 		free(packidx->hdr.trailer);
408 	}
409 	if (close(packidx->fd) != 0 && err == NULL)
410 		err = got_error_from_errno("close");
411 	free(packidx);
412 
413 	return err;
414 }
415 
416 static off_t
417 get_object_offset(struct got_packidx *packidx, int idx)
418 {
419 	uint32_t offset = betoh32(packidx->hdr.offsets[idx]);
420 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
421 		uint64_t loffset;
422 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
423 		if (idx < 0 || idx >= packidx->nlargeobj ||
424 		    packidx->hdr.large_offsets == NULL)
425 			return -1;
426 		loffset = betoh64(packidx->hdr.large_offsets[idx]);
427 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
428 	}
429 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
430 }
431 
432 int
433 got_packidx_get_object_idx_sha1(struct got_packidx *packidx, uint8_t *sha1)
434 {
435 	u_int8_t id0 = sha1[0];
436 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
437 	int left = 0, right = totobj - 1;
438 
439 	if (id0 > 0)
440 		left = betoh32(packidx->hdr.fanout_table[id0 - 1]);
441 
442 	while (left <= right) {
443 		struct got_packidx_object_id *oid;
444 		int i, cmp;
445 
446 		i = ((left + right) / 2);
447 		oid = &packidx->hdr.sorted_ids[i];
448 		cmp = memcmp(sha1, oid->sha1, SHA1_DIGEST_LENGTH);
449 		if (cmp == 0)
450 			return i;
451 		else if (cmp > 0)
452 			left = i + 1;
453 		else if (cmp < 0)
454 			right = i - 1;
455 	}
456 
457 	return -1;
458 }
459 
460 int
461 got_packidx_get_object_idx(struct got_packidx *packidx, struct got_object_id *id)
462 {
463 	return got_packidx_get_object_idx_sha1(packidx, id->sha1);
464 }
465 
466 const struct got_error *
467 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
468     struct got_packidx *packidx, const char *id_str_prefix)
469 {
470 	const struct got_error *err = NULL;
471 	u_int8_t id0;
472 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
473 	char hex[3];
474 	size_t prefix_len = strlen(id_str_prefix);
475 	struct got_packidx_object_id *oid;
476 	int i;
477 
478 	SIMPLEQ_INIT(matched_ids);
479 
480 	if (prefix_len < 2)
481 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
482 
483 	hex[0] = id_str_prefix[0];
484 	hex[1] = id_str_prefix[1];
485 	hex[2] = '\0';
486 	if (!got_parse_xdigit(&id0, hex))
487 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
488 
489 	i = betoh32(packidx->hdr.fanout_table[id0 - 1]);
490 	if (i == 0)
491 		return NULL;
492 
493 	oid = &packidx->hdr.sorted_ids[i];
494 	while (i < totobj && oid->sha1[0] == id0) {
495 		char id_str[SHA1_DIGEST_STRING_LENGTH];
496 		struct got_object_qid *qid;
497 		int cmp;
498 
499 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
500 		        return got_error(GOT_ERR_NO_SPACE);
501 
502 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
503 		if (cmp < 0) {
504 			oid = &packidx->hdr.sorted_ids[++i];
505 			continue;
506 		} else if (cmp > 0)
507 			break;
508 
509 		err = got_object_qid_alloc_partial(&qid);
510 		if (err)
511 			break;
512 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
513 		SIMPLEQ_INSERT_TAIL(matched_ids, qid, entry);
514 
515 		oid = &packidx->hdr.sorted_ids[++i];
516 	}
517 
518 	if (err)
519 		got_object_id_queue_free(matched_ids);
520 	return err;
521 }
522 
523 const struct got_error *
524 got_pack_stop_privsep_child(struct got_pack *pack)
525 {
526 	const struct got_error *err = NULL;
527 
528 	if (pack->privsep_child == NULL)
529 		return NULL;
530 
531 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
532 	if (err)
533 		return err;
534 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
535 	if (close(pack->privsep_child->imsg_fd) != 0 && err == NULL)
536 		err = got_error_from_errno("close");
537 	free(pack->privsep_child);
538 	pack->privsep_child = NULL;
539 	return err;
540 }
541 
542 const struct got_error *
543 got_pack_close(struct got_pack *pack)
544 {
545 	const struct got_error *err = NULL;
546 
547 	err = got_pack_stop_privsep_child(pack);
548 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
549 		err = got_error_from_errno("munmap");
550 	if (pack->fd != -1 && close(pack->fd) != 0 && err == NULL)
551 		err = got_error_from_errno("close");
552 	pack->fd = -1;
553 	free(pack->path_packfile);
554 	pack->path_packfile = NULL;
555 	pack->filesize = 0;
556 	if (pack->delta_cache) {
557 		got_delta_cache_free(pack->delta_cache);
558 		pack->delta_cache = NULL;
559 	}
560 
561 	return err;
562 }
563 
564 static const struct got_error *
565 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
566     struct got_pack *pack, off_t offset)
567 {
568 	uint8_t t = 0;
569 	uint64_t s = 0;
570 	uint8_t sizeN;
571 	size_t mapoff = 0;
572 	int i = 0;
573 
574 	*len = 0;
575 
576 	if (offset >= pack->filesize)
577 		return got_error(GOT_ERR_PACK_OFFSET);
578 
579 	if (pack->map) {
580 		mapoff = (size_t)offset;
581 	} else {
582 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
583 			return got_error_from_errno("lseek");
584 	}
585 
586 	do {
587 		/* We do not support size values which don't fit in 64 bit. */
588 		if (i > 9)
589 			return got_error(GOT_ERR_NO_SPACE);
590 
591 		if (pack->map) {
592 			sizeN = *(pack->map + mapoff);
593 			mapoff += sizeof(sizeN);
594 		} else {
595 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
596 			if (n < 0)
597 				return got_error_from_errno("read");
598 			if (n != sizeof(sizeN))
599 				return got_error(GOT_ERR_BAD_PACKFILE);
600 		}
601 		*len += sizeof(sizeN);
602 
603 		if (i == 0) {
604 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
605 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
606 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
607 		} else {
608 			size_t shift = 4 + 7 * (i - 1);
609 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
610 		}
611 		i++;
612 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
613 
614 	*type = t;
615 	*size = s;
616 	return NULL;
617 }
618 
619 static const struct got_error *
620 open_plain_object(struct got_object **obj, struct got_object_id *id,
621     uint8_t type, off_t offset, size_t size, int idx)
622 {
623 	*obj = calloc(1, sizeof(**obj));
624 	if (*obj == NULL)
625 		return got_error_from_errno("calloc");
626 
627 	(*obj)->type = type;
628 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
629 	(*obj)->pack_idx = idx;
630 	(*obj)->hdrlen = 0;
631 	(*obj)->size = size;
632 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
633 	(*obj)->pack_offset = offset;
634 
635 	return NULL;
636 }
637 
638 static const struct got_error *
639 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
640     off_t delta_offset)
641 {
642 	int64_t o = 0;
643 	uint8_t offN;
644 	int i = 0;
645 
646 	*offset = 0;
647 	*len = 0;
648 
649 	do {
650 		/* We do not support offset values which don't fit in 64 bit. */
651 		if (i > 8)
652 			return got_error(GOT_ERR_NO_SPACE);
653 
654 		if (pack->map) {
655 			size_t mapoff;
656 			if (delta_offset >= pack->filesize)
657 				return got_error(GOT_ERR_PACK_OFFSET);
658 			mapoff = (size_t)delta_offset + *len;
659 			offN = *(pack->map + mapoff);
660 		} else {
661 			ssize_t n;
662 			n = read(pack->fd, &offN, sizeof(offN));
663 			if (n < 0)
664 				return got_error_from_errno("read");
665 			if (n != sizeof(offN))
666 				return got_error(GOT_ERR_BAD_PACKFILE);
667 		}
668 		*len += sizeof(offN);
669 
670 		if (i == 0)
671 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
672 		else {
673 			o++;
674 			o <<= 7;
675 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
676 		}
677 		i++;
678 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
679 
680 	*offset = o;
681 	return NULL;
682 }
683 
684 static const struct got_error *
685 parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
686     off_t offset, int tslen)
687 {
688 	const struct got_error *err;
689 	int64_t negoffset;
690 	size_t negofflen;
691 
692 	*len = 0;
693 
694 	err = parse_negative_offset(&negoffset, &negofflen, pack,
695 	    offset + tslen);
696 	if (err)
697 		return err;
698 
699 	/* Compute the base object's offset (must be in the same pack file). */
700 	*base_offset = (offset - negoffset);
701 	if (*base_offset <= 0)
702 		return got_error(GOT_ERR_BAD_PACKFILE);
703 
704 	*len = negofflen;
705 	return NULL;
706 }
707 
708 static const struct got_error *
709 resolve_delta_chain(struct got_delta_chain *, struct got_packidx *,
710     struct got_pack *, off_t, size_t, int, size_t, unsigned int);
711 
712 static const struct got_error *
713 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
714     size_t delta_data_offset, struct got_pack *pack)
715 {
716 	const struct got_error *err = NULL;
717 
718 	if (pack->map) {
719 		if (delta_data_offset >= pack->filesize)
720 			return got_error(GOT_ERR_PACK_OFFSET);
721 		err = got_inflate_to_mem_mmap(delta_buf, delta_len, pack->map,
722 		    delta_data_offset, pack->filesize - delta_data_offset);
723 	} else {
724 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
725 			return got_error_from_errno("lseek");
726 		err = got_inflate_to_mem_fd(delta_buf, delta_len, pack->fd);
727 	}
728 	return err;
729 }
730 
731 static const struct got_error *
732 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
733     int delta_type, size_t delta_size, size_t delta_data_offset)
734 {
735 	struct got_delta *delta;
736 
737 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
738 	    delta_data_offset);
739 	if (delta == NULL)
740 		return got_error_from_errno("got_delta_open");
741 	/* delta is freed in got_object_close() */
742 	deltas->nentries++;
743 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
744 	return NULL;
745 }
746 
747 static const struct got_error *
748 resolve_offset_delta(struct got_delta_chain *deltas,
749     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
750     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
751 
752 {
753 	const struct got_error *err;
754 	off_t base_offset;
755 	uint8_t base_type;
756 	uint64_t base_size;
757 	size_t base_tslen;
758 	off_t delta_data_offset;
759 	size_t consumed;
760 
761 	err = parse_offset_delta(&base_offset, &consumed, pack,
762 	    delta_offset, tslen);
763 	if (err)
764 		return err;
765 
766 	delta_data_offset = delta_offset + tslen + consumed;
767 	if (delta_data_offset >= pack->filesize)
768 		return got_error(GOT_ERR_PACK_OFFSET);
769 
770 	if (pack->map == NULL) {
771 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
772 		if (delta_data_offset == -1)
773 			return got_error_from_errno("lseek");
774 	}
775 
776 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
777 	    delta_data_offset);
778 	if (err)
779 		return err;
780 
781 	/* An offset delta must be in the same packfile. */
782 	if (base_offset >= pack->filesize)
783 		return got_error(GOT_ERR_PACK_OFFSET);
784 
785 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
786 	    pack, base_offset);
787 	if (err)
788 		return err;
789 
790 	return resolve_delta_chain(deltas, packidx, pack, base_offset,
791 	    base_tslen, base_type, base_size, recursion - 1);
792 }
793 
794 static const struct got_error *
795 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
796     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
797     size_t delta_size, unsigned int recursion)
798 {
799 	const struct got_error *err;
800 	struct got_object_id id;
801 	int idx;
802 	off_t base_offset;
803 	uint8_t base_type;
804 	uint64_t base_size;
805 	size_t base_tslen;
806 	off_t delta_data_offset;
807 	uint8_t *delta_buf;
808 	size_t delta_len;
809 
810 	if (delta_offset + tslen >= pack->filesize)
811 		return got_error(GOT_ERR_PACK_OFFSET);
812 
813 	if (pack->map) {
814 		size_t mapoff = delta_offset + tslen;
815 		memcpy(&id, pack->map + mapoff, sizeof(id));
816 		mapoff += sizeof(id);
817 		delta_data_offset = (off_t)mapoff;
818 		err = got_inflate_to_mem_mmap(&delta_buf, &delta_len, pack->map,
819 		    mapoff, pack->filesize - mapoff);
820 		if (err)
821 			return err;
822 	} else {
823 		ssize_t n;
824 		n = read(pack->fd, &id, sizeof(id));
825 		if (n < 0)
826 			return got_error_from_errno("read");
827 		if (n != sizeof(id))
828 			return got_error(GOT_ERR_BAD_PACKFILE);
829 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
830 		if (delta_data_offset == -1)
831 			return got_error_from_errno("lseek");
832 		err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
833 		if (err)
834 			return err;
835 	}
836 
837 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
838 	    delta_data_offset);
839 	if (err)
840 		return err;
841 
842 	/* Delta base must be in the same pack file. */
843 	idx = got_packidx_get_object_idx(packidx, &id);
844 	if (idx == -1)
845 		return got_error(GOT_ERR_BAD_PACKFILE);
846 
847 	base_offset = get_object_offset(packidx, idx);
848 	if (base_offset == (uint64_t)-1)
849 		return got_error(GOT_ERR_BAD_PACKIDX);
850 
851 	if (base_offset >= pack->filesize)
852 		return got_error(GOT_ERR_PACK_OFFSET);
853 
854 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
855 	    pack, base_offset);
856 	if (err)
857 		return err;
858 
859 	return resolve_delta_chain(deltas, packidx, pack, base_offset,
860 	    base_tslen, base_type, base_size, recursion - 1);
861 }
862 
863 static const struct got_error *
864 resolve_delta_chain(struct got_delta_chain *deltas, struct got_packidx *packidx,
865     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
866     size_t delta_size, unsigned int recursion)
867 {
868 	const struct got_error *err = NULL;
869 
870 	if (--recursion == 0)
871 		return got_error(GOT_ERR_RECURSION);
872 
873 	switch (delta_type) {
874 	case GOT_OBJ_TYPE_COMMIT:
875 	case GOT_OBJ_TYPE_TREE:
876 	case GOT_OBJ_TYPE_BLOB:
877 	case GOT_OBJ_TYPE_TAG:
878 		/* Plain types are the final delta base. Recursion ends. */
879 		err = add_delta(deltas, delta_offset, tslen, delta_type,
880 		    delta_size, 0);
881 		break;
882 	case GOT_OBJ_TYPE_OFFSET_DELTA:
883 		err = resolve_offset_delta(deltas, packidx, pack,
884 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
885 		break;
886 	case GOT_OBJ_TYPE_REF_DELTA:
887 		err = resolve_ref_delta(deltas, packidx, pack,
888 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
889 		break;
890 	default:
891 		return got_error(GOT_ERR_OBJ_TYPE);
892 	}
893 
894 	return err;
895 }
896 
897 static const struct got_error *
898 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
899     struct got_pack *pack, struct got_object_id *id, off_t offset,
900     size_t tslen, int delta_type, size_t delta_size, int idx)
901 {
902 	const struct got_error *err = NULL;
903 	int resolved_type;
904 
905 	*obj = calloc(1, sizeof(**obj));
906 	if (*obj == NULL)
907 		return got_error_from_errno("calloc");
908 
909 	(*obj)->flags = 0;
910 	(*obj)->hdrlen = 0;
911 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
912 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
913 	(*obj)->pack_offset = offset + tslen;
914 
915 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
916 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
917 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
918 	(*obj)->pack_idx = idx;
919 
920 	err = resolve_delta_chain(&(*obj)->deltas, packidx, pack, offset,
921 	    tslen, delta_type, delta_size, GOT_DELTA_CHAIN_RECURSION_MAX);
922 	if (err)
923 		goto done;
924 
925 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
926 	if (err)
927 		goto done;
928 	(*obj)->type = resolved_type;
929 done:
930 	if (err) {
931 		got_object_close(*obj);
932 		*obj = NULL;
933 	}
934 	return err;
935 }
936 
937 const struct got_error *
938 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
939     struct got_packidx *packidx, int idx, struct got_object_id *id)
940 {
941 	const struct got_error *err = NULL;
942 	off_t offset;
943 	uint8_t type;
944 	uint64_t size;
945 	size_t tslen;
946 
947 	*obj = NULL;
948 
949 	offset = get_object_offset(packidx, idx);
950 	if (offset == (uint64_t)-1)
951 		return got_error(GOT_ERR_BAD_PACKIDX);
952 
953 	err = parse_object_type_and_size(&type, &size, &tslen, pack, offset);
954 	if (err)
955 		return err;
956 
957 	switch (type) {
958 	case GOT_OBJ_TYPE_COMMIT:
959 	case GOT_OBJ_TYPE_TREE:
960 	case GOT_OBJ_TYPE_BLOB:
961 	case GOT_OBJ_TYPE_TAG:
962 		err = open_plain_object(obj, id, type, offset + tslen,
963 		    size, idx);
964 		break;
965 	case GOT_OBJ_TYPE_OFFSET_DELTA:
966 	case GOT_OBJ_TYPE_REF_DELTA:
967 		err = open_delta_object(obj, packidx, pack, id, offset,
968 		    tslen, type, size, idx);
969 		break;
970 	default:
971 		err = got_error(GOT_ERR_OBJ_TYPE);
972 		break;
973 	}
974 
975 	return err;
976 }
977 
978 static const struct got_error *
979 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
980     struct got_pack *pack)
981 {
982 	struct got_delta *delta;
983 	uint64_t base_size = 0, result_size = 0;
984 
985 	*max_size = 0;
986 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
987 		/* Plain object types are the delta base. */
988 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
989 		    delta->type != GOT_OBJ_TYPE_TREE &&
990 		    delta->type != GOT_OBJ_TYPE_BLOB &&
991 		    delta->type != GOT_OBJ_TYPE_TAG) {
992 			const struct got_error *err;
993 			uint8_t *delta_buf;
994 			size_t delta_len;
995 			int cached = 1;
996 
997 			got_delta_cache_get(&delta_buf, &delta_len,
998 			    pack->delta_cache, delta->data_offset);
999 			if (delta_buf == NULL) {
1000 				cached = 0;
1001 				err = read_delta_data(&delta_buf, &delta_len,
1002 				    delta->data_offset, pack);
1003 				if (err)
1004 					return err;
1005 				err = got_delta_cache_add(pack->delta_cache,
1006 				    delta->data_offset, delta_buf, delta_len);
1007 				if (err == NULL)
1008 					cached = 1;
1009 				else if (err->code != GOT_ERR_NO_SPACE) {
1010 					free(delta_buf);
1011 					return err;
1012 				}
1013 			}
1014 			err = got_delta_get_sizes(&base_size, &result_size,
1015 			    delta_buf, delta_len);
1016 			if (!cached)
1017 				free(delta_buf);
1018 			if (err)
1019 				return err;
1020 		} else
1021 			base_size = delta->size;
1022 		if (base_size > *max_size)
1023 			*max_size = base_size;
1024 		if (result_size > *max_size)
1025 			*max_size = result_size;
1026 	}
1027 
1028 	return NULL;
1029 }
1030 
1031 const struct got_error *
1032 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1033     struct got_pack *pack)
1034 {
1035 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1036 		return got_error(GOT_ERR_OBJ_TYPE);
1037 
1038 	return get_delta_chain_max_size(size, &obj->deltas, pack);
1039 }
1040 
1041 static const struct got_error *
1042 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1043     struct got_pack *pack, FILE *outfile, FILE *base_file, FILE *accum_file)
1044 {
1045 	const struct got_error *err = NULL;
1046 	struct got_delta *delta;
1047 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1048 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1049 	uint64_t max_size;
1050 	int n = 0;
1051 
1052 	*result_size = 0;
1053 
1054 	if (SIMPLEQ_EMPTY(&deltas->entries))
1055 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1056 
1057 	/* We process small enough files entirely in memory for speed. */
1058 	err = get_delta_chain_max_size(&max_size, deltas, pack);
1059 	if (err)
1060 		return err;
1061 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1062 		accum_buf = malloc(max_size);
1063 		if (accum_buf == NULL)
1064 			return got_error_from_errno("malloc");
1065 		base_file = NULL;
1066 		accum_file = NULL;
1067 	}
1068 
1069 	/* Deltas are ordered in ascending order. */
1070 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1071 		int cached = 1;
1072 		if (n == 0) {
1073 			size_t mapoff;
1074 			off_t delta_data_offset;
1075 
1076 			/* Plain object types are the delta base. */
1077 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1078 			    delta->type != GOT_OBJ_TYPE_TREE &&
1079 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1080 			    delta->type != GOT_OBJ_TYPE_TAG) {
1081 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1082 				goto done;
1083 			}
1084 
1085 			delta_data_offset = delta->offset + delta->tslen;
1086 			if (delta_data_offset >= pack->filesize) {
1087 				err = got_error(GOT_ERR_PACK_OFFSET);
1088 				goto done;
1089 			}
1090 			if (pack->map == NULL) {
1091 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1092 				    == -1) {
1093 					err = got_error_from_errno("lseek");
1094 					goto done;
1095 				}
1096 			}
1097 			if (base_file) {
1098 				if (pack->map) {
1099 					mapoff = (size_t)delta_data_offset;
1100 					err = got_inflate_to_file_mmap(
1101 					    &base_bufsz, pack->map, mapoff,
1102 					    pack->filesize - mapoff, base_file);
1103 				} else
1104 					err = got_inflate_to_file_fd(
1105 					    &base_bufsz, pack->fd, base_file);
1106 			} else {
1107 				if (pack->map) {
1108 					mapoff = (size_t)delta_data_offset;
1109 					err = got_inflate_to_mem_mmap(&base_buf,
1110 					    &base_bufsz, pack->map, mapoff,
1111 					    pack->filesize - mapoff);
1112 				} else
1113 					err = got_inflate_to_mem_fd(&base_buf,
1114 					    &base_bufsz, pack->fd);
1115 			}
1116 			if (err)
1117 				goto done;
1118 			n++;
1119 			if (base_file)
1120 				rewind(base_file);
1121 			continue;
1122 		}
1123 
1124 		got_delta_cache_get(&delta_buf, &delta_len,
1125 		    pack->delta_cache, delta->data_offset);
1126 		if (delta_buf == NULL) {
1127 			cached = 0;
1128 			err = read_delta_data(&delta_buf, &delta_len,
1129 			    delta->data_offset, pack);
1130 			if (err)
1131 				goto done;
1132 			err = got_delta_cache_add(pack->delta_cache,
1133 			    delta->data_offset, delta_buf, delta_len);
1134 			if (err == NULL)
1135 				cached = 1;
1136 			else if (err->code != GOT_ERR_NO_SPACE) {
1137 				free(delta_buf);
1138 				goto done;
1139 			}
1140 		}
1141 		if (base_buf) {
1142 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1143 			    delta_buf, delta_len, accum_buf,
1144 			    &accum_size, max_size);
1145 			n++;
1146 		} else {
1147 			err = got_delta_apply(base_file, delta_buf,
1148 			    delta_len,
1149 			    /* Final delta application writes to output file. */
1150 			    ++n < deltas->nentries ? accum_file : outfile,
1151 			    &accum_size);
1152 		}
1153 		if (!cached)
1154 			free(delta_buf);
1155 		if (err)
1156 			goto done;
1157 
1158 		if (n < deltas->nentries) {
1159 			/* Accumulated delta becomes the new base. */
1160 			if (base_buf) {
1161 				uint8_t *tmp = accum_buf;
1162 				/*
1163 				 * Base buffer switches roles with accumulation
1164 				 * buffer. Ensure it can hold the largest
1165 				 * result in the delta chain. The initial
1166 				 * allocation might have been smaller.
1167 				 */
1168 				if (base_bufsz < max_size) {
1169 					uint8_t *p;
1170 					p = reallocarray(base_buf, 1, max_size);
1171 					if (p == NULL) {
1172 						err = got_error_from_errno(
1173 						    "reallocarray");
1174 						goto done;
1175 					}
1176 					base_buf = p;
1177 					base_bufsz = max_size;
1178 				}
1179 				accum_buf = base_buf;
1180 				base_buf = tmp;
1181 			} else {
1182 				FILE *tmp = accum_file;
1183 				accum_file = base_file;
1184 				base_file = tmp;
1185 				rewind(base_file);
1186 				rewind(accum_file);
1187 			}
1188 		}
1189 	}
1190 
1191 done:
1192 	free(base_buf);
1193 	if (accum_buf) {
1194 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1195 		free(accum_buf);
1196 		if (len != accum_size)
1197 			err = got_ferror(outfile, GOT_ERR_IO);
1198 	}
1199 	rewind(outfile);
1200 	if (err == NULL)
1201 		*result_size = accum_size;
1202 	return err;
1203 }
1204 
1205 static const struct got_error *
1206 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1207     struct got_delta_chain *deltas, struct got_pack *pack)
1208 {
1209 	const struct got_error *err = NULL;
1210 	struct got_delta *delta;
1211 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1212 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1213 	uint64_t max_size;
1214 	int n = 0;
1215 
1216 	*outbuf = NULL;
1217 	*outlen = 0;
1218 
1219 	if (SIMPLEQ_EMPTY(&deltas->entries))
1220 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1221 
1222 	err = get_delta_chain_max_size(&max_size, deltas, pack);
1223 	if (err)
1224 		return err;
1225 	accum_buf = malloc(max_size);
1226 	if (accum_buf == NULL)
1227 		return got_error_from_errno("malloc");
1228 
1229 	/* Deltas are ordered in ascending order. */
1230 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1231 		int cached = 1;
1232 		if (n == 0) {
1233 			size_t delta_data_offset;
1234 
1235 			/* Plain object types are the delta base. */
1236 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1237 			    delta->type != GOT_OBJ_TYPE_TREE &&
1238 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1239 			    delta->type != GOT_OBJ_TYPE_TAG) {
1240 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1241 				goto done;
1242 			}
1243 
1244 			delta_data_offset = delta->offset + delta->tslen;
1245 			if (delta_data_offset >= pack->filesize) {
1246 				err = got_error(GOT_ERR_PACK_OFFSET);
1247 				goto done;
1248 			}
1249 			if (pack->map) {
1250 				size_t mapoff = (size_t)delta_data_offset;
1251 				err = got_inflate_to_mem_mmap(&base_buf,
1252 				    &base_bufsz, pack->map, mapoff,
1253 				    pack->filesize - mapoff);
1254 			} else {
1255 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1256 				    == -1) {
1257 					err = got_error_from_errno("lseek");
1258 					goto done;
1259 				}
1260 				err = got_inflate_to_mem_fd(&base_buf,
1261 				    &base_bufsz, pack->fd);
1262 			}
1263 			if (err)
1264 				goto done;
1265 			n++;
1266 			continue;
1267 		}
1268 
1269 		got_delta_cache_get(&delta_buf, &delta_len,
1270 		    pack->delta_cache, delta->data_offset);
1271 		if (delta_buf == NULL) {
1272 			cached = 0;
1273 			err = read_delta_data(&delta_buf, &delta_len,
1274 			    delta->data_offset, pack);
1275 			if (err)
1276 				goto done;
1277 			err = got_delta_cache_add(pack->delta_cache,
1278 			    delta->data_offset, delta_buf, delta_len);
1279 			if (err == NULL)
1280 				cached = 1;
1281 			else if (err->code != GOT_ERR_NO_SPACE) {
1282 				free(delta_buf);
1283 				goto done;
1284 			}
1285 		}
1286 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1287 		    delta_buf, delta_len, accum_buf,
1288 		    &accum_size, max_size);
1289 		if (!cached)
1290 			free(delta_buf);
1291 		n++;
1292 		if (err)
1293 			goto done;
1294 
1295 		if (n < deltas->nentries) {
1296 			/* Accumulated delta becomes the new base. */
1297 			uint8_t *tmp = accum_buf;
1298 			/*
1299 			 * Base buffer switches roles with accumulation buffer.
1300 			 * Ensure it can hold the largest result in the delta
1301 			 * chain. Initial allocation might have been smaller.
1302 			 */
1303 			if (base_bufsz < max_size) {
1304 				uint8_t *p;
1305 				p = reallocarray(base_buf, 1, max_size);
1306 				if (p == NULL) {
1307 					err = got_error_from_errno(
1308 					    "reallocarray");
1309 					goto done;
1310 				}
1311 				base_buf = p;
1312 				base_bufsz = max_size;
1313 			}
1314 			accum_buf = base_buf;
1315 			base_buf = tmp;
1316 		}
1317 	}
1318 
1319 done:
1320 	free(base_buf);
1321 	if (err) {
1322 		free(accum_buf);
1323 		*outbuf = NULL;
1324 		*outlen = 0;
1325 	} else {
1326 		*outbuf = accum_buf;
1327 		*outlen = accum_size;
1328 	}
1329 	return err;
1330 }
1331 
1332 const struct got_error *
1333 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1334     FILE *outfile, FILE *base_file, FILE *accum_file)
1335 {
1336 	const struct got_error *err = NULL;
1337 
1338 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1339 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1340 
1341 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1342 		if (obj->pack_offset >= pack->filesize)
1343 			return got_error(GOT_ERR_PACK_OFFSET);
1344 
1345 		if (pack->map) {
1346 			size_t mapoff = (size_t)obj->pack_offset;
1347 			err = got_inflate_to_file_mmap(&obj->size, pack->map,
1348 			    mapoff, pack->filesize - mapoff, outfile);
1349 		} else {
1350 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1351 				return got_error_from_errno("lseek");
1352 			err = got_inflate_to_file_fd(&obj->size, pack->fd,
1353 			    outfile);
1354 		}
1355 	} else
1356 		err = dump_delta_chain_to_file(&obj->size, &obj->deltas, pack,
1357 		    outfile, base_file, accum_file);
1358 
1359 	return err;
1360 }
1361 
1362 const struct got_error *
1363 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1364     struct got_object *obj, struct got_pack *pack)
1365 {
1366 	const struct got_error *err = NULL;
1367 
1368 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1369 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1370 
1371 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1372 		if (obj->pack_offset >= pack->filesize)
1373 			return got_error(GOT_ERR_PACK_OFFSET);
1374 		if (pack->map) {
1375 			size_t mapoff = (size_t)obj->pack_offset;
1376 			err = got_inflate_to_mem_mmap(buf, len, pack->map,
1377 			    mapoff, pack->filesize - mapoff);
1378 		} else {
1379 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1380 				return got_error_from_errno("lseek");
1381 			err = got_inflate_to_mem_fd(buf, len, pack->fd);
1382 		}
1383 	} else
1384 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, pack);
1385 
1386 	return err;
1387 }