1 /*
2  * Copyright (c) 2018 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/mman.h>
21 
22 #include <dirent.h>
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 
34 #include "got_error.h"
35 #include "got_object.h"
36 #include "got_repository.h"
37 #include "got_opentemp.h"
38 
39 #include "got_lib_sha1.h"
40 #include "got_lib_pack.h"
41 #include "got_lib_path.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_inflate.h"
44 #include "got_lib_object.h"
45 #include "got_lib_repository.h"
46 
47 #ifndef nitems
48 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
49 #endif
50 
51 #define GOT_PACK_PREFIX		"pack-"
52 #define GOT_PACKFILE_SUFFIX	".pack"
53 #define GOT_PACKIDX_SUFFIX		".idx"
54 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
55 				SHA1_DIGEST_STRING_LENGTH - 1 + \
56 				strlen(GOT_PACKFILE_SUFFIX))
57 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
58 				SHA1_DIGEST_STRING_LENGTH - 1 + \
59 				strlen(GOT_PACKIDX_SUFFIX))
60 
61 #ifndef MIN
62 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
63 #endif
64 
65 static const struct got_error *
66 verify_fanout_table(uint32_t *fanout_table)
67 {
68 	int i;
69 
70 	for (i = 0; i < 0xff - 1; i++) {
71 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
72 			return got_error(GOT_ERR_BAD_PACKIDX);
73 	}
74 
75 	return NULL;
76 }
77 
78 static const struct got_error *
79 get_packfile_size(size_t *size, const char *path)
80 {
81 	struct stat sb;
82 	char *dot;
83 
84 	*size = 0;
85 
86 	dot = strrchr(path, '.');
87 	if (dot == NULL)
88 		return got_error(GOT_ERR_BAD_PATH);
89 
90 	/* Path must point to a pack index or to a pack file. */
91 	if (strcmp(dot, GOT_PACKIDX_SUFFIX) == 0) {
92 		const struct got_error *err = NULL;
93 		char *path_pack;
94 		char base_path[PATH_MAX];
95 
96 		/* Convert pack index path to pack file path. */
97 		if (strlcpy(base_path, path, PATH_MAX) > PATH_MAX)
98 			return got_error(GOT_ERR_NO_SPACE);
99 		dot = strrchr(base_path, '.');
100 		if (dot == NULL)
101 			return got_error(GOT_ERR_BAD_PATH);
102 		*dot = '\0';
103 		if (asprintf(&path_pack, "%s.pack", base_path) == -1)
104 			return got_error_from_errno();
105 
106 		if (stat(path_pack, &sb) != 0)
107 			err = got_error_from_errno();
108 		free(path_pack);
109 		if (err)
110 			return err;
111 	} else if (strcmp(dot, GOT_PACKFILE_SUFFIX) == 0) {
112 		if (stat(path, &sb) != 0)
113 			return got_error_from_errno();
114 	} else
115 		return got_error(GOT_ERR_BAD_PATH);
116 
117 	*size = sb.st_size;
118 	return 0;
119 }
120 
121 const struct got_error *
122 got_packidx_open(struct got_packidx **packidx, const char *path, int verify)
123 {
124 	struct got_packidx *p;
125 	struct got_packidx_v2_hdr *h;
126 	const struct got_error *err = NULL;
127 	size_t nobj, len_fanout, len_ids, offset, remain;
128 	ssize_t n;
129 	SHA1_CTX ctx;
130 	uint8_t sha1[SHA1_DIGEST_LENGTH];
131 
132 	*packidx = NULL;
133 
134 	SHA1Init(&ctx);
135 
136 	p = calloc(1, sizeof(*p));
137 	if (p == NULL)
138 		return got_error_from_errno();
139 
140 	p->fd = open(path, O_RDONLY | O_NOFOLLOW, GOT_DEFAULT_FILE_MODE);
141 	if (p->fd == -1)
142 		return got_error_from_errno();
143 
144 	err = get_packfile_size(&p->len, path);
145 	if (err) {
146 		close(p->fd);
147 		free(p);
148 		return err;
149 	}
150 	if (p->len < sizeof(p->hdr)) {
151 		err = got_error(GOT_ERR_BAD_PACKIDX);
152 		close(p->fd);
153 		free(p);
154 		return err;
155 	}
156 
157 	p->path_packidx = strdup(path);
158 	if (p->path_packidx == NULL) {
159 		err = got_error_from_errno();
160 		goto done;
161 	}
162 
163 #ifndef GOT_PACK_NO_MMAP
164 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
165 	if (p->map == MAP_FAILED)
166 		p->map = NULL; /* fall back to read(2) */
167 #endif
168 
169 	h = &p->hdr;
170 	offset = 0;
171 	remain = p->len;
172 
173 	if (remain < sizeof(*h->magic)) {
174 		err = got_error(GOT_ERR_BAD_PACKIDX);
175 		goto done;
176 	}
177 	if (p->map)
178 		h->magic = (uint32_t *)(p->map + offset);
179 	else {
180 		h->magic = malloc(sizeof(*h->magic));
181 		if (h->magic == NULL) {
182 			err = got_error_from_errno();
183 			goto done;
184 		}
185 		n = read(p->fd, h->magic, sizeof(*h->magic));
186 		if (n != sizeof(*h->magic)) {
187 			err = got_error(GOT_ERR_BAD_PACKIDX);
188 			goto done;
189 		}
190 	}
191 	if (betoh32(*h->magic) != GOT_PACKIDX_V2_MAGIC) {
192 		err = got_error(GOT_ERR_BAD_PACKIDX);
193 		goto done;
194 	}
195 	offset += sizeof(*h->magic);
196 	remain -= sizeof(*h->magic);
197 
198 	if (verify)
199 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
200 
201 	if (remain < sizeof(*h->version)) {
202 		err = got_error(GOT_ERR_BAD_PACKIDX);
203 		goto done;
204 	}
205 	if (p->map)
206 		h->version = (uint32_t *)(p->map + offset);
207 	else {
208 		h->version = malloc(sizeof(*h->version));
209 		if (h->version == NULL) {
210 			err = got_error_from_errno();
211 			goto done;
212 		}
213 		n = read(p->fd, h->version, sizeof(*h->version));
214 		if (n != sizeof(*h->version)) {
215 			err = got_error(GOT_ERR_BAD_PACKIDX);
216 			goto done;
217 		}
218 	}
219 	if (betoh32(*h->version) != GOT_PACKIDX_VERSION) {
220 		err = got_error(GOT_ERR_BAD_PACKIDX);
221 		goto done;
222 	}
223 	offset += sizeof(*h->version);
224 	remain -= sizeof(*h->version);
225 
226 	if (verify)
227 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
228 
229 	len_fanout =
230 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
231 	if (remain < len_fanout) {
232 		err = got_error(GOT_ERR_BAD_PACKIDX);
233 		goto done;
234 	}
235 	if (p->map)
236 		h->fanout_table = (uint32_t *)(p->map + offset);
237 	else {
238 		h->fanout_table = malloc(len_fanout);
239 		if (h->fanout_table == NULL) {
240 			err = got_error_from_errno();
241 			goto done;
242 		}
243 		n = read(p->fd, h->fanout_table, len_fanout);
244 		if (n != len_fanout) {
245 			err = got_error(GOT_ERR_BAD_PACKIDX);
246 			goto done;
247 		}
248 	}
249 	err = verify_fanout_table(h->fanout_table);
250 	if (err)
251 		goto done;
252 	if (verify)
253 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
254 	offset += len_fanout;
255 	remain -= len_fanout;
256 
257 	nobj = betoh32(h->fanout_table[0xff]);
258 	len_ids = nobj * sizeof(*h->sorted_ids);
259 	if (len_ids <= nobj || len_ids > remain) {
260 		err = got_error(GOT_ERR_BAD_PACKIDX);
261 		goto done;
262 	}
263 	if (p->map)
264 		h->sorted_ids =
265 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
266 	else {
267 		h->sorted_ids = malloc(len_ids);
268 		if (h->sorted_ids == NULL) {
269 			err = got_error(GOT_ERR_BAD_PACKIDX);
270 			goto done;
271 		}
272 		n = read(p->fd, h->sorted_ids, len_ids);
273 		if (n != len_ids) {
274 			err = got_error(GOT_ERR_BAD_PACKIDX);
275 			goto done;
276 		}
277 	}
278 	if (verify)
279 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
280 	offset += len_ids;
281 	remain -= len_ids;
282 
283 	if (remain < nobj * sizeof(*h->crc32)) {
284 		err = got_error(GOT_ERR_BAD_PACKIDX);
285 		goto done;
286 	}
287 	if (p->map)
288 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
289 	else {
290 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
291 		if (h->crc32 == NULL) {
292 			err = got_error_from_errno();
293 			goto done;
294 		}
295 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
296 		if (n != nobj * sizeof(*h->crc32)) {
297 			err = got_error(GOT_ERR_BAD_PACKIDX);
298 			goto done;
299 		}
300 	}
301 	if (verify)
302 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
303 	remain -= nobj * sizeof(*h->crc32);
304 	offset += nobj * sizeof(*h->crc32);
305 
306 	if (remain < nobj * sizeof(*h->offsets)) {
307 		err = got_error(GOT_ERR_BAD_PACKIDX);
308 		goto done;
309 	}
310 	if (p->map)
311 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
312 	else {
313 		h->offsets = malloc(nobj * sizeof(*h->offsets));
314 		if (h->offsets == NULL) {
315 			err = got_error_from_errno();
316 			goto done;
317 		}
318 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
319 		if (n != nobj * sizeof(*h->offsets)) {
320 			err = got_error(GOT_ERR_BAD_PACKIDX);
321 			goto done;
322 		}
323 	}
324 	if (verify)
325 		SHA1Update(&ctx, (uint8_t *)h->offsets,
326 		    nobj * sizeof(*h->offsets));
327 	remain -= nobj * sizeof(*h->offsets);
328 	offset += nobj * sizeof(*h->offsets);
329 
330 	/* Large file offsets are contained only in files > 2GB. */
331 	if (p->len <= 0x80000000)
332 		goto checksum;
333 
334 	if (remain < nobj * sizeof(*h->large_offsets)) {
335 		err = got_error(GOT_ERR_BAD_PACKIDX);
336 		goto done;
337 	}
338 	if (p->map)
339 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
340 	else {
341 		h->offsets = malloc(nobj * sizeof(*h->large_offsets));
342 		if (h->offsets == NULL) {
343 			err = got_error_from_errno();
344 			goto done;
345 		}
346 		n = read(p->fd, h->large_offsets,
347 		    nobj * sizeof(*h->large_offsets));
348 		if (n != nobj * sizeof(*h->large_offsets)) {
349 			err = got_error(GOT_ERR_BAD_PACKIDX);
350 			goto done;
351 		}
352 	}
353 	if (verify)
354 		SHA1Update(&ctx, (uint8_t*)h->large_offsets,
355 		    nobj * sizeof(*h->large_offsets));
356 	remain -= nobj * sizeof(*h->large_offsets);
357 	offset += nobj * sizeof(*h->large_offsets);
358 
359 checksum:
360 	if (remain < sizeof(*h->trailer)) {
361 		err = got_error(GOT_ERR_BAD_PACKIDX);
362 		goto done;
363 	}
364 	if (p->map)
365 		h->trailer =
366 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
367 	else {
368 		h->trailer = malloc(sizeof(*h->trailer));
369 		if (h->trailer == NULL) {
370 			err = got_error_from_errno();
371 			goto done;
372 		}
373 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
374 		if (n != sizeof(*h->trailer)) {
375 			err = got_error(GOT_ERR_BAD_PACKIDX);
376 			goto done;
377 		}
378 	}
379 	if (verify) {
380 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
381 		SHA1Final(sha1, &ctx);
382 		if (memcmp(h->trailer->packidx_sha1, sha1,
383 		    SHA1_DIGEST_LENGTH) != 0)
384 			err = got_error(GOT_ERR_PACKIDX_CSUM);
385 	}
386 done:
387 	if (err)
388 		got_packidx_close(p);
389 	else
390 		*packidx = p;
391 	return err;
392 }
393 
394 const struct got_error *
395 got_packidx_close(struct got_packidx *packidx)
396 {
397 	const struct got_error *err = NULL;
398 
399 	free(packidx->path_packidx);
400 	if (packidx->map) {
401 		if (munmap(packidx->map, packidx->len) == -1)
402 			err = got_error_from_errno();
403 	} else {
404 		free(packidx->hdr.magic);
405 		free(packidx->hdr.version);
406 		free(packidx->hdr.fanout_table);
407 		free(packidx->hdr.sorted_ids);
408 		free(packidx->hdr.crc32);
409 		free(packidx->hdr.offsets);
410 		free(packidx->hdr.large_offsets);
411 		free(packidx->hdr.trailer);
412 	}
413 	close(packidx->fd);
414 	free(packidx);
415 
416 	return err;
417 }
418 
419 static int
420 is_packidx_filename(const char *name, size_t len)
421 {
422 	if (len != GOT_PACKIDX_NAMELEN)
423 		return 0;
424 
425 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
426 		return 0;
427 
428 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
429 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
430 		return 0;
431 
432 	return 1;
433 }
434 
435 static off_t
436 get_object_offset(struct got_packidx *packidx, int idx)
437 {
438 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
439 	uint32_t offset = betoh32(packidx->hdr.offsets[idx]);
440 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
441 		uint64_t loffset;
442 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
443 		if (idx < 0 || idx > totobj ||
444 		    packidx->hdr.large_offsets == NULL)
445 			return -1;
446 		loffset = betoh64(packidx->hdr.large_offsets[idx]);
447 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
448 	}
449 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
450 }
451 
452 static int
453 get_object_idx(struct got_packidx *packidx, struct got_object_id *id,
454     struct got_repository *repo)
455 {
456 	u_int8_t id0 = id->sha1[0];
457 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
458 	int left = 0, right = totobj - 1;
459 
460 	if (id0 > 0)
461 		left = betoh32(packidx->hdr.fanout_table[id0 - 1]);
462 
463 	while (left <= right) {
464 		struct got_packidx_object_id *oid;
465 		int i, cmp;
466 
467 		i = ((left + right) / 2);
468 		oid = &packidx->hdr.sorted_ids[i];
469 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
470 		if (cmp == 0)
471 			return i;
472 		else if (cmp > 0)
473 			left = i + 1;
474 		else if (cmp < 0)
475 			right = i - 1;
476 	}
477 
478 	return -1;
479 }
480 
481 static const struct got_error *
482 cache_packidx(struct got_packidx *packidx, struct got_repository *repo)
483 {
484 	const struct got_error *err = NULL;
485 	int i;
486 
487 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
488 		if (repo->packidx_cache[i] == NULL)
489 			break;
490 	}
491 
492 	if (i == nitems(repo->packidx_cache)) {
493 		err = got_packidx_close(repo->packidx_cache[i - 1]);
494 		if (err)
495 			return err;
496 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
497 		    sizeof(repo->packidx_cache) -
498 		    sizeof(repo->packidx_cache[0]));
499 		i = 0;
500 	}
501 
502 	repo->packidx_cache[i] = packidx;
503 	return NULL;
504 }
505 
506 static const struct got_error *
507 search_packidx(struct got_packidx **packidx, int *idx,
508     struct got_repository *repo, struct got_object_id *id)
509 {
510 	const struct got_error *err;
511 	char *path_packdir;
512 	DIR *packdir;
513 	struct dirent *dent;
514 	char *path_packidx;
515 	int i;
516 
517 	/* Search pack index cache. */
518 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
519 		if (repo->packidx_cache[i] == NULL)
520 			break;
521 		*idx = get_object_idx(repo->packidx_cache[i], id, repo);
522 		if (*idx != -1) {
523 			*packidx = repo->packidx_cache[i];
524 			return NULL;
525 		}
526 	}
527 	/* No luck. Search the filesystem. */
528 
529 	path_packdir = got_repo_get_path_objects_pack(repo);
530 	if (path_packdir == NULL)
531 		return got_error_from_errno();
532 
533 	packdir = opendir(path_packdir);
534 	if (packdir == NULL) {
535 		err = got_error_from_errno();
536 		goto done;
537 	}
538 
539 	while ((dent = readdir(packdir)) != NULL) {
540 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
541 			continue;
542 
543 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
544 		    dent->d_name) == -1) {
545 			err = got_error_from_errno();
546 			goto done;
547 		}
548 
549 		err = got_packidx_open(packidx, path_packidx, 0);
550 		free(path_packidx);
551 		if (err)
552 			goto done;
553 
554 		*idx = get_object_idx(*packidx, id, repo);
555 		if (*idx != -1) {
556 			err = NULL; /* found the object */
557 			err = cache_packidx(*packidx, repo);
558 			goto done;
559 		}
560 
561 		err = got_packidx_close(*packidx);
562 		*packidx = NULL;
563 		if (err)
564 			goto done;
565 	}
566 
567 	err = got_error(GOT_ERR_NO_OBJ);
568 done:
569 	free(path_packdir);
570 	if (packdir && closedir(packdir) != 0 && err == 0)
571 		err = got_error_from_errno();
572 	return err;
573 }
574 
575 static const struct got_error *
576 get_packfile_path(char **path_packfile, struct got_repository *repo,
577     struct got_packidx *packidx)
578 {
579 	size_t size;
580 
581 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
582 	size = strlen(packidx->path_packidx) + 2;
583 	if (size < GOT_PACKFILE_NAMELEN + 1)
584 		return got_error(GOT_ERR_BAD_PATH);
585 
586 	*path_packfile = calloc(size, sizeof(**path_packfile));
587 	if (*path_packfile == NULL)
588 		return got_error_from_errno();
589 
590 	/* Copy up to and excluding ".idx". */
591 	if (strlcpy(*path_packfile, packidx->path_packidx,
592 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
593 		return got_error(GOT_ERR_NO_SPACE);
594 
595 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
596 		return got_error(GOT_ERR_NO_SPACE);
597 
598 	return NULL;
599 }
600 
601 static const struct got_error *
602 read_packfile_hdr(int fd, struct got_packidx *packidx)
603 {
604 	const struct got_error *err = NULL;
605 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
606 	struct got_packfile_hdr hdr;
607 	ssize_t n;
608 
609 	n = read(fd, &hdr, sizeof(hdr));
610 	if (n < 0)
611 		return got_error_from_errno();
612 	if (n != sizeof(hdr))
613 		return got_error(GOT_ERR_BAD_PACKFILE);
614 
615 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
616 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
617 	    betoh32(hdr.nobjects) != totobj)
618 		err = got_error(GOT_ERR_BAD_PACKFILE);
619 
620 	return err;
621 }
622 
623 static const struct got_error *
624 open_packfile(int *fd, const char *path_packfile,
625     struct got_repository *repo, struct got_packidx *packidx)
626 {
627 	const struct got_error *err = NULL;
628 
629 	*fd = open(path_packfile, O_RDONLY | O_NOFOLLOW, GOT_DEFAULT_FILE_MODE);
630 	if (*fd == -1)
631 		return got_error_from_errno();
632 
633 	if (packidx) {
634 		err = read_packfile_hdr(*fd, packidx);
635 		if (err) {
636 			close(*fd);
637 			*fd = -1;
638 		}
639 	}
640 	return err;
641 }
642 
643 const struct got_error *
644 got_pack_close(struct got_pack *pack)
645 {
646 	const struct got_error *err = NULL;
647 
648 	if (munmap(pack->map, pack->filesize) == -1)
649 		err = got_error_from_errno();
650 	close(pack->fd);
651 	pack->fd = -1;
652 	free(pack->path_packfile);
653 	pack->path_packfile = NULL;
654 	pack->filesize = 0;
655 
656 	return err;
657 }
658 
659 static const struct got_error *
660 cache_pack(struct got_pack **packp, const char *path_packfile,
661     struct got_packidx *packidx, struct got_repository *repo)
662 {
663 	const struct got_error *err = NULL;
664 	struct got_pack *pack = NULL;
665 	int i;
666 
667 	if (packp)
668 		*packp = NULL;
669 
670 	for (i = 0; i < nitems(repo->packs); i++) {
671 		pack = &repo->packs[i];
672 		if (pack->path_packfile == NULL)
673 			break;
674 		if (strcmp(pack->path_packfile, path_packfile) == 0)
675 			return NULL;
676 	}
677 
678 	if (i == nitems(repo->packs) - 1) {
679 		err = got_pack_close(&repo->packs[i - 1]);
680 		if (err)
681 			return err;
682 		memmove(&repo->packs[1], &repo->packs[0],
683 		    sizeof(repo->packs) - sizeof(repo->packs[0]));
684 		i = 0;
685 	}
686 
687 	pack = &repo->packs[i];
688 
689 	pack->path_packfile = strdup(path_packfile);
690 	if (pack->path_packfile == NULL) {
691 		err = got_error_from_errno();
692 		goto done;
693 	}
694 
695 	err = open_packfile(&pack->fd, path_packfile, repo, packidx);
696 	if (err)
697 		goto done;
698 
699 	err = get_packfile_size(&pack->filesize, path_packfile);
700 	if (err)
701 		goto done;
702 
703 #ifndef GOT_PACK_NO_MMAP
704 	pack->map = mmap(NULL, pack->filesize, PROT_READ, MAP_PRIVATE,
705 	    pack->fd, 0);
706 	if (pack->map == MAP_FAILED)
707 		pack->map = NULL; /* fall back to read(2) */
708 #endif
709 done:
710 	if (err) {
711 		if (pack) {
712 			free(pack->path_packfile);
713 			memset(pack, 0, sizeof(*pack));
714 		}
715 	} else if (packp)
716 		*packp = pack;
717 	return err;
718 }
719 
720 struct got_pack *
721 get_cached_pack(const char *path_packfile, struct got_repository *repo)
722 {
723 	struct got_pack *pack = NULL;
724 	int i;
725 
726 	for (i = 0; i < nitems(repo->packs); i++) {
727 		pack = &repo->packs[i];
728 		if (pack->path_packfile == NULL)
729 			break;
730 		if (strcmp(pack->path_packfile, path_packfile) == 0)
731 			return pack;
732 	}
733 
734 	return NULL;
735 }
736 
737 static const struct got_error *
738 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
739     struct got_pack *pack, off_t offset)
740 {
741 	uint8_t t = 0;
742 	uint64_t s = 0;
743 	uint8_t sizeN;
744 	size_t mapoff = 0;
745 	int i = 0;
746 
747 	*len = 0;
748 
749 	if (offset >= pack->filesize)
750 		return got_error(GOT_ERR_PACK_OFFSET);
751 
752 	if (pack->map) {
753 		mapoff = (size_t)offset;
754 	} else {
755 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
756 			return got_error_from_errno();
757 	}
758 
759 	do {
760 		/* We do not support size values which don't fit in 64 bit. */
761 		if (i > 9)
762 			return got_error(GOT_ERR_NO_SPACE);
763 
764 		if (pack->map) {
765 			sizeN = *(pack->map + mapoff);
766 			mapoff += sizeof(sizeN);
767 		} else {
768 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
769 			if (n < 0)
770 				return got_error_from_errno();
771 			if (n != sizeof(sizeN))
772 				return got_error(GOT_ERR_BAD_PACKFILE);
773 		}
774 		*len += sizeof(sizeN);
775 
776 		if (i == 0) {
777 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
778 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
779 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
780 		} else {
781 			size_t shift = 4 + 7 * (i - 1);
782 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
783 		}
784 		i++;
785 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
786 
787 	*type = t;
788 	*size = s;
789 	return NULL;
790 }
791 
792 static const struct got_error *
793 open_plain_object(struct got_object **obj, const char *path_packfile,
794     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
795 {
796 	*obj = calloc(1, sizeof(**obj));
797 	if (*obj == NULL)
798 		return got_error_from_errno();
799 
800 	(*obj)->path_packfile = strdup(path_packfile);
801 	if ((*obj)->path_packfile == NULL) {
802 		const struct got_error *err = got_error_from_errno();
803 		free(*obj);
804 		*obj = NULL;
805 		return err;
806 	}
807 
808 	(*obj)->type = type;
809 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
810 	(*obj)->hdrlen = 0;
811 	(*obj)->size = size;
812 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
813 	(*obj)->pack_offset = offset;
814 
815 	return NULL;
816 }
817 
818 static const struct got_error *
819 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
820     off_t delta_offset)
821 {
822 	int64_t o = 0;
823 	uint8_t offN;
824 	int i = 0;
825 
826 	*len = 0;
827 
828 	do {
829 		/* We do not support offset values which don't fit in 64 bit. */
830 		if (i > 8)
831 			return got_error(GOT_ERR_NO_SPACE);
832 
833 		if (pack->map) {
834 			size_t mapoff;
835 			if (delta_offset >= pack->filesize)
836 				return got_error(GOT_ERR_PACK_OFFSET);
837 			mapoff = (size_t)delta_offset + *len;
838 			offN = *(pack->map + mapoff);
839 		} else {
840 			ssize_t n;
841 			n = read(pack->fd, &offN, sizeof(offN));
842 			if (n < 0)
843 				return got_error_from_errno();
844 			if (n != sizeof(offN))
845 				return got_error(GOT_ERR_BAD_PACKFILE);
846 		}
847 		*len += sizeof(offN);
848 
849 		if (i == 0)
850 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
851 		else {
852 			o++;
853 			o <<= 7;
854 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
855 		}
856 		i++;
857 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
858 
859 	*offset = o;
860 	return NULL;
861 }
862 
863 static const struct got_error *
864 parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
865     off_t offset, int tslen)
866 {
867 	const struct got_error *err;
868 	int64_t negoffset;
869 	size_t negofflen;
870 
871 	*len = 0;
872 
873 	err = parse_negative_offset(&negoffset, &negofflen, pack,
874 	    offset + tslen);
875 	if (err)
876 		return err;
877 
878 	/* Compute the base object's offset (must be in the same pack file). */
879 	*base_offset = (offset - negoffset);
880 	if (*base_offset <= 0)
881 		return got_error(GOT_ERR_BAD_PACKFILE);
882 
883 	*len = negofflen;
884 	return NULL;
885 }
886 
887 static const struct got_error *
888 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
889     struct got_packidx *, struct got_pack *, off_t, size_t, int,
890     size_t, unsigned int);
891 
892 static const struct got_error *
893 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
894     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
895     size_t delta_data_offset, uint8_t *delta_buf, size_t delta_len)
896 {
897 	struct got_delta *delta;
898 
899 	delta = got_delta_open(path_packfile, delta_offset, tslen,
900 	    delta_type, delta_size, delta_data_offset, delta_buf,
901 	    delta_len);
902 	if (delta == NULL)
903 		return got_error_from_errno();
904 	/* delta is freed in got_object_close() */
905 	deltas->nentries++;
906 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
907 	return NULL;
908 }
909 
910 static const struct got_error *
911 resolve_offset_delta(struct got_delta_chain *deltas,
912     struct got_repository *repo, struct got_packidx *packidx,
913     struct got_pack *pack, off_t delta_offset, size_t tslen,
914     int delta_type, size_t delta_size, unsigned int recursion)
915 
916 {
917 	const struct got_error *err;
918 	off_t base_offset;
919 	uint8_t base_type;
920 	uint64_t base_size;
921 	size_t base_tslen;
922 	off_t delta_data_offset;
923 	uint8_t *delta_buf;
924 	size_t delta_len, consumed;
925 
926 	err = parse_offset_delta(&base_offset, &consumed, pack,
927 	    delta_offset, tslen);
928 	if (err)
929 		return err;
930 
931 	delta_data_offset = delta_offset + tslen + consumed;
932 	if (delta_data_offset >= pack->filesize)
933 		return got_error(GOT_ERR_PACK_OFFSET);
934 
935 	if (pack->map == NULL) {
936 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
937 		if (delta_data_offset == -1)
938 			return got_error_from_errno();
939 	}
940 
941 	if (pack->map) {
942 		size_t mapoff = (size_t)delta_data_offset;
943 		err = got_inflate_to_mem_mmap(&delta_buf, &delta_len, pack->map,
944 		    mapoff, pack->filesize - mapoff);
945 		if (err)
946 			return err;
947 	} else {
948 
949 		err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
950 		if (err)
951 			return err;
952 	}
953 
954 	err = add_delta(deltas, pack->path_packfile, delta_offset, tslen,
955 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
956 	if (err)
957 		return err;
958 
959 	/* An offset delta must be in the same packfile. */
960 	if (base_offset >= pack->filesize)
961 		return got_error(GOT_ERR_PACK_OFFSET);
962 
963 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
964 	    pack, base_offset);
965 	if (err)
966 		return err;
967 
968 	return resolve_delta_chain(deltas, repo, packidx, pack, base_offset,
969 	    base_tslen, base_type, base_size, recursion - 1);
970 }
971 
972 static const struct got_error *
973 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
974     struct got_packidx *packidx, struct got_pack *pack,
975     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
976     unsigned int recursion)
977 {
978 	const struct got_error *err;
979 	struct got_object_id id;
980 	int idx;
981 	off_t base_offset;
982 	uint8_t base_type;
983 	uint64_t base_size;
984 	size_t base_tslen;
985 	off_t delta_data_offset;
986 	uint8_t *delta_buf;
987 	size_t delta_len;
988 
989 	if (delta_offset >= pack->filesize)
990 		return got_error(GOT_ERR_PACK_OFFSET);
991 	delta_data_offset = delta_offset + tslen + sizeof(id);
992 	if (delta_data_offset >= pack->filesize)
993 		return got_error(GOT_ERR_PACK_OFFSET);
994 
995 	if (pack->map == NULL) {
996 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
997 		if (delta_data_offset == -1)
998 			return got_error_from_errno();
999 	}
1000 
1001 
1002 	if (pack->map) {
1003 		size_t mapoff = (size_t)delta_offset;
1004 		memcpy(&id, pack->map + mapoff, sizeof(id));
1005 		mapoff += sizeof(id);
1006 		err = got_inflate_to_mem_mmap(&delta_buf, &delta_len, pack->map,
1007 		    mapoff, pack->filesize - delta_data_offset);
1008 		if (err)
1009 			return err;
1010 	} else {
1011 		ssize_t n = read(pack->fd, &id, sizeof(id));
1012 		if (n < 0)
1013 			return got_error_from_errno();
1014 		if (n != sizeof(id))
1015 			return got_error(GOT_ERR_BAD_PACKFILE);
1016 		err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
1017 		if (err)
1018 			return err;
1019 	}
1020 
1021 	err = add_delta(deltas, pack->path_packfile, delta_offset, tslen,
1022 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
1023 	if (err)
1024 		return err;
1025 
1026 	/* Delta base must be in the same pack file. */
1027 	idx = get_object_idx(packidx, &id, repo);
1028 	if (idx == -1)
1029 		return got_error(GOT_ERR_BAD_PACKFILE);
1030 
1031 	base_offset = get_object_offset(packidx, idx);
1032 	if (base_offset == (uint64_t)-1) {
1033 		return got_error(GOT_ERR_BAD_PACKIDX);
1034 	}
1035 
1036 	if (base_offset >= pack->filesize) {
1037 		err = got_error(GOT_ERR_PACK_OFFSET);
1038 		goto done;
1039 	}
1040 
1041 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
1042 	    pack, base_offset);
1043 	if (err)
1044 		goto done;
1045 
1046 	err = resolve_delta_chain(deltas, repo, packidx, pack, base_offset,
1047 	    base_tslen, base_type, base_size, recursion - 1);
1048 done:
1049 	return err;
1050 }
1051 
1052 static const struct got_error *
1053 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
1054     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
1055     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
1056 {
1057 	const struct got_error *err = NULL;
1058 
1059 	if (--recursion == 0)
1060 		return got_error(GOT_ERR_RECURSION);
1061 
1062 	switch (delta_type) {
1063 	case GOT_OBJ_TYPE_COMMIT:
1064 	case GOT_OBJ_TYPE_TREE:
1065 	case GOT_OBJ_TYPE_BLOB:
1066 	case GOT_OBJ_TYPE_TAG:
1067 		/* Plain types are the final delta base. Recursion ends. */
1068 		err = add_delta(deltas, pack->path_packfile, delta_offset,
1069 		    tslen, delta_type, delta_size, 0, NULL, 0);
1070 		break;
1071 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1072 		err = resolve_offset_delta(deltas, repo, packidx, pack,
1073 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1074 		break;
1075 	case GOT_OBJ_TYPE_REF_DELTA:
1076 		err = resolve_ref_delta(deltas, repo, packidx, pack,
1077 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1078 		break;
1079 	default:
1080 		return got_error(GOT_ERR_OBJ_TYPE);
1081 	}
1082 
1083 	return err;
1084 }
1085 
1086 static const struct got_error *
1087 open_delta_object(struct got_object **obj, struct got_repository *repo,
1088     struct got_packidx *packidx, struct got_pack *pack,
1089     struct got_object_id *id, off_t offset, size_t tslen,
1090     int delta_type, size_t delta_size)
1091 {
1092 	const struct got_error *err = NULL;
1093 	int resolved_type;
1094 
1095 	*obj = calloc(1, sizeof(**obj));
1096 	if (*obj == NULL)
1097 		return got_error_from_errno();
1098 
1099 	(*obj)->flags = 0;
1100 	(*obj)->hdrlen = 0;
1101 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
1102 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
1103 	(*obj)->pack_offset = offset + tslen;
1104 
1105 	(*obj)->path_packfile = strdup(pack->path_packfile);
1106 	if ((*obj)->path_packfile == NULL) {
1107 		err = got_error_from_errno();
1108 		goto done;
1109 	}
1110 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
1111 
1112 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
1113 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
1114 
1115 	err = resolve_delta_chain(&(*obj)->deltas, repo, packidx, pack, offset,
1116 	    tslen, delta_type, delta_size, GOT_DELTA_CHAIN_RECURSION_MAX);
1117 	if (err)
1118 		goto done;
1119 
1120 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
1121 	if (err)
1122 		goto done;
1123 	(*obj)->type = resolved_type;
1124 
1125 done:
1126 	if (err) {
1127 		got_object_close(*obj);
1128 		*obj = NULL;
1129 	}
1130 	return err;
1131 }
1132 
1133 static const struct got_error *
1134 open_packed_object(struct got_object **obj, struct got_repository *repo,
1135     struct got_packidx *packidx, int idx, struct got_object_id *id)
1136 {
1137 	const struct got_error *err = NULL;
1138 	off_t offset;
1139 	char *path_packfile;
1140 	struct got_pack *pack;
1141 	uint8_t type;
1142 	uint64_t size;
1143 	size_t tslen;
1144 
1145 	*obj = NULL;
1146 
1147 	offset = get_object_offset(packidx, idx);
1148 	if (offset == (uint64_t)-1)
1149 		return got_error(GOT_ERR_BAD_PACKIDX);
1150 
1151 	err = get_packfile_path(&path_packfile, repo, packidx);
1152 	if (err)
1153 		return err;
1154 
1155 	pack = get_cached_pack(path_packfile, repo);
1156 	if (pack == NULL) {
1157 		err = cache_pack(&pack, path_packfile, packidx, repo);
1158 		if (err)
1159 			goto done;
1160 	}
1161 
1162 	err = parse_object_type_and_size(&type, &size, &tslen, pack, offset);
1163 	if (err)
1164 		goto done;
1165 
1166 	switch (type) {
1167 	case GOT_OBJ_TYPE_COMMIT:
1168 	case GOT_OBJ_TYPE_TREE:
1169 	case GOT_OBJ_TYPE_BLOB:
1170 	case GOT_OBJ_TYPE_TAG:
1171 		err = open_plain_object(obj, path_packfile, id, type,
1172 		    offset + tslen, size);
1173 		break;
1174 
1175 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1176 	case GOT_OBJ_TYPE_REF_DELTA:
1177 		err = open_delta_object(obj, repo, packidx, pack, id, offset,
1178 		    tslen, type, size);
1179 		break;
1180 
1181 	default:
1182 		err = got_error(GOT_ERR_OBJ_TYPE);
1183 		goto done;
1184 	}
1185 done:
1186 	free(path_packfile);
1187 	return err;
1188 }
1189 
1190 const struct got_error *
1191 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
1192     struct got_repository *repo)
1193 {
1194 	const struct got_error *err = NULL;
1195 	struct got_packidx *packidx = NULL;
1196 	int idx;
1197 
1198 	err = search_packidx(&packidx, &idx, repo, id);
1199 	if (err)
1200 		return err;
1201 
1202 	err = open_packed_object(obj, repo, packidx, idx, id);
1203 	if (err)
1204 		return err;
1205 
1206 	err = cache_pack(NULL, (*obj)->path_packfile, packidx, repo);
1207 	return err;
1208 }
1209 
1210 static const struct got_error *
1211 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
1212 {
1213 	struct got_delta *delta;
1214 	uint64_t base_size = 0, result_size = 0;
1215 
1216 	*max_size = 0;
1217 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1218 		/* Plain object types are the delta base. */
1219 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1220 		    delta->type != GOT_OBJ_TYPE_TREE &&
1221 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1222 		    delta->type != GOT_OBJ_TYPE_TAG) {
1223 			const struct got_error *err;
1224 			err = got_delta_get_sizes(&base_size, &result_size,
1225 			    delta->delta_buf, delta->delta_len);
1226 			if (err)
1227 				return err;
1228 		} else
1229 			base_size = delta->size;
1230 		if (base_size > *max_size)
1231 			*max_size = base_size;
1232 		if (result_size > *max_size)
1233 			*max_size = result_size;
1234 	}
1235 
1236 	return NULL;
1237 }
1238 
1239 static const struct got_error *
1240 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1241     FILE *outfile, struct got_repository *repo)
1242 {
1243 	const struct got_error *err = NULL;
1244 	struct got_delta *delta;
1245 	FILE *base_file = NULL, *accum_file = NULL;
1246 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1247 	size_t accum_size = 0;
1248 	uint64_t max_size;
1249 	int n = 0;
1250 
1251 	*result_size = 0;
1252 
1253 	if (SIMPLEQ_EMPTY(&deltas->entries))
1254 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1255 
1256 	/* We process small enough files entirely in memory for speed. */
1257 	err = get_delta_chain_max_size(&max_size, deltas);
1258 	if (err)
1259 		return err;
1260 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1261 		accum_buf = malloc(max_size);
1262 		if (accum_buf == NULL)
1263 			return got_error_from_errno();
1264 	} else {
1265 		base_file = got_opentemp();
1266 		if (base_file == NULL)
1267 			return got_error_from_errno();
1268 
1269 		accum_file = got_opentemp();
1270 		if (accum_file == NULL) {
1271 			err = got_error_from_errno();
1272 			fclose(base_file);
1273 			return err;
1274 		}
1275 	}
1276 
1277 	/* Deltas are ordered in ascending order. */
1278 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1279 		if (n == 0) {
1280 			struct got_pack *pack;
1281 			size_t base_len, mapoff;
1282 			off_t delta_data_offset;
1283 
1284 			/* Plain object types are the delta base. */
1285 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1286 			    delta->type != GOT_OBJ_TYPE_TREE &&
1287 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1288 			    delta->type != GOT_OBJ_TYPE_TAG) {
1289 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1290 				goto done;
1291 			}
1292 
1293 			pack = get_cached_pack(delta->path_packfile, repo);
1294 			if (pack == NULL) {
1295 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1296 				goto done;
1297 			}
1298 
1299 			delta_data_offset = delta->offset + delta->tslen;
1300 			if (delta_data_offset >= pack->filesize) {
1301 				err = got_error(GOT_ERR_PACK_OFFSET);
1302 				goto done;
1303 			}
1304 			if (pack->map == NULL) {
1305 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1306 				    == -1) {
1307 					err = got_error_from_errno();
1308 					goto done;
1309 				}
1310 			}
1311 			if (base_file) {
1312 				if (pack->map) {
1313 					mapoff = (size_t)delta_data_offset;
1314 					err = got_inflate_to_file_mmap(
1315 					    &base_len, pack->map, mapoff,
1316 					    pack->filesize - mapoff, base_file);
1317 				} else
1318 					err = got_inflate_to_file_fd(&base_len,
1319 					    pack->fd, base_file);
1320 			} else {
1321 				if (pack->map) {
1322 					mapoff = (size_t)delta_data_offset;
1323 					err = got_inflate_to_mem_mmap(&base_buf,
1324 					    &base_len, pack->map, mapoff,
1325 					    pack->filesize - mapoff);
1326 				} else
1327 					err = got_inflate_to_mem_fd(&base_buf,
1328 					    &base_len, pack->fd);
1329 				if (base_len < max_size) {
1330 					uint8_t *p;
1331 					p = reallocarray(base_buf, 1, max_size);
1332 					if (p == NULL) {
1333 						err = got_error_from_errno();
1334 						goto done;
1335 					}
1336 					base_buf = p;
1337 				}
1338 			}
1339 			if (err)
1340 				goto done;
1341 			n++;
1342 			if (base_file)
1343 				rewind(base_file);
1344 			continue;
1345 		}
1346 
1347 		if (base_buf) {
1348 			err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1349 			    delta->delta_len, accum_buf, &accum_size);
1350 			n++;
1351 		} else {
1352 			err = got_delta_apply(base_file, delta->delta_buf,
1353 			    delta->delta_len,
1354 			    /* Final delta application writes to output file. */
1355 			    ++n < deltas->nentries ? accum_file : outfile,
1356 			    &accum_size);
1357 		}
1358 		if (err)
1359 			goto done;
1360 
1361 		if (n < deltas->nentries) {
1362 			/* Accumulated delta becomes the new base. */
1363 			if (base_buf) {
1364 				uint8_t *tmp = accum_buf;
1365 				accum_buf = base_buf;
1366 				base_buf = tmp;
1367 			} else {
1368 				FILE *tmp = accum_file;
1369 				accum_file = base_file;
1370 				base_file = tmp;
1371 				rewind(base_file);
1372 				rewind(accum_file);
1373 			}
1374 		}
1375 	}
1376 
1377 done:
1378 	free(base_buf);
1379 	if (accum_buf) {
1380 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1381 		free(accum_buf);
1382 		if (len != accum_size)
1383 			return got_ferror(outfile, GOT_ERR_IO);
1384 	}
1385 	if (base_file)
1386 		fclose(base_file);
1387 	if (accum_file)
1388 		fclose(accum_file);
1389 	rewind(outfile);
1390 	if (err == NULL)
1391 		*result_size = accum_size;
1392 	return err;
1393 }
1394 
1395 static const struct got_error *
1396 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1397     struct got_delta_chain *deltas, struct got_repository *repo)
1398 {
1399 	const struct got_error *err = NULL;
1400 	struct got_delta *delta;
1401 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1402 	size_t accum_size;
1403 	uint64_t max_size;
1404 	int n = 0;
1405 
1406 	*outbuf = NULL;
1407 	*outlen = 0;
1408 
1409 	if (SIMPLEQ_EMPTY(&deltas->entries))
1410 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1411 
1412 	err = get_delta_chain_max_size(&max_size, deltas);
1413 	if (err)
1414 		return err;
1415 	accum_buf = malloc(max_size);
1416 	if (accum_buf == NULL)
1417 		return got_error_from_errno();
1418 
1419 	/* Deltas are ordered in ascending order. */
1420 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1421 		if (n == 0) {
1422 			struct got_pack *pack;
1423 			size_t base_len;
1424 			size_t delta_data_offset;
1425 
1426 			/* Plain object types are the delta base. */
1427 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1428 			    delta->type != GOT_OBJ_TYPE_TREE &&
1429 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1430 			    delta->type != GOT_OBJ_TYPE_TAG) {
1431 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1432 				goto done;
1433 			}
1434 
1435 			pack = get_cached_pack(delta->path_packfile, repo);
1436 			if (pack == NULL) {
1437 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1438 				goto done;
1439 			}
1440 
1441 			delta_data_offset = delta->offset + delta->tslen;
1442 			if (delta_data_offset >= pack->filesize) {
1443 				err = got_error(GOT_ERR_PACK_OFFSET);
1444 				goto done;
1445 			}
1446 			if (pack->map) {
1447 				size_t mapoff = (size_t)delta_data_offset;
1448 				err = got_inflate_to_mem_mmap(&base_buf,
1449 				    &base_len, pack->map, mapoff,
1450 				    pack->filesize - mapoff);
1451 			} else {
1452 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1453 				    == -1) {
1454 					err = got_error_from_errno();
1455 					goto done;
1456 				}
1457 				err = got_inflate_to_mem_fd(&base_buf,
1458 				    &base_len, pack->fd);
1459 			}
1460 			if (err)
1461 				goto done;
1462 			if (base_len < max_size) {
1463 				uint8_t *p;
1464 				p = reallocarray(base_buf, 1, max_size);
1465 				if (p == NULL) {
1466 					err = got_error_from_errno();
1467 					goto done;
1468 				}
1469 				base_buf = p;
1470 			}
1471 			n++;
1472 			continue;
1473 		}
1474 
1475 		err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1476 		    delta->delta_len, accum_buf, &accum_size);
1477 		n++;
1478 		if (err)
1479 			goto done;
1480 
1481 		if (n < deltas->nentries) {
1482 			/* Accumulated delta becomes the new base. */
1483 			uint8_t *tmp = accum_buf;
1484 			accum_buf = base_buf;
1485 			base_buf = tmp;
1486 		}
1487 	}
1488 
1489 done:
1490 	free(base_buf);
1491 	if (err) {
1492 		free(accum_buf);
1493 		*outbuf = NULL;
1494 		*outlen = 0;
1495 	} else {
1496 		*outbuf = accum_buf;
1497 		*outlen = accum_size;
1498 	}
1499 	return err;
1500 }
1501 
1502 const struct got_error *
1503 got_packfile_extract_object(FILE **f, struct got_object *obj,
1504     struct got_repository *repo)
1505 {
1506 	const struct got_error *err = NULL;
1507 
1508 	*f = NULL;
1509 
1510 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1511 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1512 
1513 	*f = got_opentemp();
1514 	if (*f == NULL) {
1515 		err = got_error_from_errno();
1516 		goto done;
1517 	}
1518 
1519 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1520 		struct got_pack *pack;
1521 
1522 		pack = get_cached_pack(obj->path_packfile, repo);
1523 		if (pack == NULL) {
1524 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1525 			if (err)
1526 				goto done;
1527 		}
1528 
1529 		if (obj->pack_offset >= pack->filesize) {
1530 			err = got_error(GOT_ERR_PACK_OFFSET);
1531 			goto done;
1532 		}
1533 
1534 		if (pack->map) {
1535 			size_t mapoff = (size_t)obj->pack_offset;
1536 			err = got_inflate_to_file_mmap(&obj->size, pack->map,
1537 			    mapoff, pack->filesize - mapoff, *f);
1538 		} else {
1539 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1) {
1540 				err = got_error_from_errno();
1541 				goto done;
1542 			}
1543 			err = got_inflate_to_file_fd(&obj->size, pack->fd, *f);
1544 		}
1545 	} else
1546 		err = dump_delta_chain_to_file(&obj->size,
1547 		    &obj->deltas, *f, repo);
1548 done:
1549 	if (err && *f) {
1550 		fclose(*f);
1551 		*f = NULL;
1552 	}
1553 	return err;
1554 }
1555 
1556 const struct got_error *
1557 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1558     struct got_object *obj, struct got_repository *repo)
1559 {
1560 	const struct got_error *err = NULL;
1561 
1562 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1563 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1564 
1565 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1566 		struct got_pack *pack;
1567 
1568 		pack = get_cached_pack(obj->path_packfile, repo);
1569 		if (pack == NULL) {
1570 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1571 			if (err)
1572 				goto done;
1573 		}
1574 
1575 		if (obj->pack_offset >= pack->filesize) {
1576 			err = got_error(GOT_ERR_PACK_OFFSET);
1577 			goto done;
1578 		}
1579 		if (pack->map) {
1580 			size_t mapoff = (size_t)obj->pack_offset;
1581 			err = got_inflate_to_mem_mmap(buf, len, pack->map,
1582 			    mapoff, pack->filesize - mapoff);
1583 		} else {
1584 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1) {
1585 				err = got_error_from_errno();
1586 				goto done;
1587 			}
1588 			err = got_inflate_to_mem_fd(buf, len, pack->fd);
1589 		}
1590 	} else
1591 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, repo);
1592 done:
1593 	return err;
1594 }