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 
21 #include <dirent.h>
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <limits.h>
28 #include <sha1.h>
29 #include <endian.h>
30 #include <zlib.h>
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 #include "got_repository.h"
35 
36 #include "got_sha1_lib.h"
37 #include "got_pack_lib.h"
38 #include "got_path_lib.h"
39 #include "got_delta_lib.h"
40 #include "got_zbuf_lib.h"
41 #include "got_object_lib.h"
42 #include "got_repository_lib.h"
43 
44 #ifndef nitems
45 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
46 #endif
47 
48 #define GOT_PACK_PREFIX		"pack-"
49 #define GOT_PACKFILE_SUFFIX	".pack"
50 #define GOT_PACKIDX_SUFFIX		".idx"
51 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
52 				SHA1_DIGEST_STRING_LENGTH - 1 + \
53 				strlen(GOT_PACKFILE_SUFFIX))
54 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
55 				SHA1_DIGEST_STRING_LENGTH - 1 + \
56 				strlen(GOT_PACKIDX_SUFFIX))
57 
58 #ifndef MIN
59 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
60 #endif
61 
62 static const struct got_error *
63 verify_fanout_table(uint32_t *fanout_table)
64 {
65 	int i;
66 
67 	for (i = 0; i < 0xff - 1; i++) {
68 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
69 			return got_error(GOT_ERR_BAD_PACKIDX);
70 	}
71 
72 	return NULL;
73 }
74 
75 static const struct got_error *
76 get_packfile_size(size_t *size, const char *path_idx)
77 {
78 	struct stat sb;
79 	char *path_pack;
80 	char base_path[PATH_MAX];
81 	char *dot;
82 
83 	if (strlcpy(base_path, path_idx, PATH_MAX) > PATH_MAX)
84 		return got_error(GOT_ERR_NO_SPACE);
85 
86 	dot = strrchr(base_path, '.');
87 	if (dot == NULL)
88 		return got_error(GOT_ERR_BAD_PATH);
89 	*dot = '\0';
90 	if (asprintf(&path_pack, "%s.pack", base_path) == -1)
91 		return got_error(GOT_ERR_NO_MEM);
92 
93 	if (stat(path_pack, &sb) != 0) {
94 		free(path_pack);
95 		return got_error_from_errno();
96 	}
97 
98 	free(path_pack);
99 	*size = sb.st_size;
100 	return 0;
101 }
102 
103 const struct got_error *
104 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
105 {
106 	struct got_packidx_v2_hdr *p;
107 	FILE *f;
108 	const struct got_error *err = NULL;
109 	size_t n, nobj, packfile_size;
110 	SHA1_CTX ctx;
111 	uint8_t sha1[SHA1_DIGEST_LENGTH];
112 
113 	SHA1Init(&ctx);
114 
115 	f = fopen(path, "rb");
116 	if (f == NULL)
117 		return got_error_from_errno();
118 
119 	err = get_packfile_size(&packfile_size, path);
120 	if (err)
121 		return err;
122 
123 	p = calloc(1, sizeof(*p));
124 	if (p == NULL) {
125 		err = got_error(GOT_ERR_NO_MEM);
126 		goto done;
127 	}
128 
129 	n = fread(&p->magic, sizeof(p->magic), 1, f);
130 	if (n != 1) {
131 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
132 		goto done;
133 	}
134 
135 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
136 		err = got_error(GOT_ERR_BAD_PACKIDX);
137 		goto done;
138 	}
139 
140 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
141 
142 	n = fread(&p->version, sizeof(p->version), 1, f);
143 	if (n != 1) {
144 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
145 		goto done;
146 	}
147 
148 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
149 		err = got_error(GOT_ERR_BAD_PACKIDX);
150 		goto done;
151 	}
152 
153 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
154 
155 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
156 	if (n != 1) {
157 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
158 		goto done;
159 	}
160 
161 	err = verify_fanout_table(p->fanout_table);
162 	if (err)
163 		goto done;
164 
165 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
166 
167 	nobj = betoh32(p->fanout_table[0xff]);
168 
169 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
170 	if (p->sorted_ids == NULL) {
171 		err = got_error(GOT_ERR_NO_MEM);
172 		goto done;
173 	}
174 
175 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
176 	if (n != nobj) {
177 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
178 		goto done;
179 	}
180 
181 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
182 	    nobj * sizeof(*p->sorted_ids));
183 
184 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
185 	if (p->crc32 == NULL) {
186 		err = got_error(GOT_ERR_NO_MEM);
187 		goto done;
188 	}
189 
190 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
191 	if (n != nobj) {
192 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
193 		goto done;
194 	}
195 
196 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
197 
198 	p->offsets = calloc(nobj, sizeof(*p->offsets));
199 	if (p->offsets == NULL) {
200 		err = got_error(GOT_ERR_NO_MEM);
201 		goto done;
202 	}
203 
204 	n = fread(p->offsets, sizeof(*p->offsets), nobj, f);
205 	if (n != nobj) {
206 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
207 		goto done;
208 	}
209 
210 	SHA1Update(&ctx, (uint8_t *)p->offsets, nobj * sizeof(*p->offsets));
211 
212 	/* Large file offsets are contained only in files > 2GB. */
213 	if (packfile_size <= 0x80000000)
214 		goto checksum;
215 
216 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
217 	if (p->large_offsets == NULL) {
218 		err = got_error(GOT_ERR_NO_MEM);
219 		goto done;
220 	}
221 
222 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
223 	if (n != nobj) {
224 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
225 		goto done;
226 	}
227 
228 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
229 	    nobj * sizeof(*p->large_offsets));
230 
231 checksum:
232 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
233 	if (n != 1) {
234 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
235 		goto done;
236 	}
237 
238 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
239 	SHA1Final(sha1, &ctx);
240 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
241 		err = got_error(GOT_ERR_PACKIDX_CSUM);
242 done:
243 	fclose(f);
244 	if (err)
245 		got_packidx_close(p);
246 	else
247 		*packidx = p;
248 	return err;
249 }
250 
251 void
252 got_packidx_close(struct got_packidx_v2_hdr *packidx)
253 {
254 	free(packidx->sorted_ids);
255 	free(packidx->offsets);
256 	free(packidx->crc32);
257 	free(packidx->large_offsets);
258 	free(packidx);
259 }
260 
261 static int
262 is_packidx_filename(const char *name, size_t len)
263 {
264 	if (len != GOT_PACKIDX_NAMELEN)
265 		return 0;
266 
267 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
268 		return 0;
269 
270 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
271 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
272 		return 0;
273 
274 	return 1;
275 }
276 
277 static off_t
278 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
279 {
280 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
281 	uint32_t offset = betoh32(packidx->offsets[idx]);
282 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
283 		uint64_t loffset;
284 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
285 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
286 			return -1;
287 		loffset = betoh64(packidx->large_offsets[idx]);
288 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
289 	}
290 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
291 }
292 
293 static int
294 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id)
295 {
296 	u_int8_t id0 = id->sha1[0];
297 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
298 	int i = 0;
299 
300 	if (id0 > 0)
301 		i = betoh32(packidx->fanout_table[id0 - 1]);
302 
303 	while (i < totobj) {
304 		struct got_object_id *oid = &packidx->sorted_ids[i];
305 		int cmp = got_object_id_cmp(id, oid);
306 
307 		if (cmp == 0)
308 			return i;
309 		i++;
310 	}
311 
312 	return -1;
313 }
314 
315 static struct got_packidx_v2_hdr *
316 dup_packidx(struct got_packidx_v2_hdr *packidx)
317 {
318 	struct got_packidx_v2_hdr *p;
319 	size_t nobj;
320 
321 	p = calloc(1, sizeof(*p));
322 	if (p == NULL)
323 		return NULL;
324 
325 	memcpy(p, packidx, sizeof(*p));
326 	p->sorted_ids = NULL;
327 	p->crc32 = NULL;
328 	p->offsets = NULL;
329 	p->large_offsets = NULL;
330 
331 	nobj = betoh32(p->fanout_table[0xff]);
332 
333 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
334 	if (p->sorted_ids == NULL)
335 		goto err;
336 	memcpy(p->sorted_ids, packidx->sorted_ids, nobj * sizeof(*p->sorted_ids));
337 
338 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
339 	if (p->crc32 == NULL)
340 		goto err;
341 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
342 
343 	p->offsets = calloc(nobj, sizeof(*p->offsets));
344 	if (p->offsets == NULL)
345 		goto err;
346 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
347 
348 	if (p->large_offsets) {
349 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
350 		if (p->large_offsets == NULL)
351 			goto err;
352 		memcpy(p->large_offsets, packidx->large_offsets,
353 		    nobj * sizeof(*p->large_offsets));
354 	}
355 
356 	return p;
357 
358 err:
359 	free(p->large_offsets);
360 	free(p->offsets);
361 	free(p->crc32);
362 	free(p->sorted_ids);
363 	free(p);
364 	return NULL;
365 }
366 
367 static const struct got_error *
368 get_packfile_path(char **path_packfile, struct got_repository *repo,
369     struct got_packidx_v2_hdr *packidx)
370 {
371 	char *path_packdir;
372 	char hex[SHA1_DIGEST_STRING_LENGTH];
373 	char *sha1str;
374 
375 	path_packdir = got_repo_get_path_objects_pack(repo);
376 	if (path_packdir == NULL)
377 		return got_error(GOT_ERR_NO_MEM);
378 
379 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
380 	    hex, sizeof(hex));
381 	if (sha1str == NULL)
382 		return got_error(GOT_ERR_PACKIDX_CSUM);
383 
384 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
385 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
386 		*path_packfile = NULL;
387 		return got_error(GOT_ERR_NO_MEM);
388 	}
389 
390 	return NULL;
391 }
392 
393 static const struct got_error *
394 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
395 {
396 	const struct got_error *err = NULL;
397 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
398 	struct got_packfile_hdr hdr;
399 	size_t n;
400 
401 	n = fread(&hdr, sizeof(hdr), 1, f);
402 	if (n != 1)
403 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
404 
405 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
406 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
407 	    betoh32(hdr.nobjects) != totobj)
408 		err = got_error(GOT_ERR_BAD_PACKFILE);
409 
410 	return err;
411 }
412 
413 static const struct got_error *
414 cache_pack(struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
415 {
416 	const struct got_error *err;
417 	FILE *packfile;
418 	char *path_packfile;
419 	int i;
420 
421 	err = get_packfile_path(&path_packfile, repo, packidx);
422 	if (err)
423 		return err;
424 
425 	packfile = fopen(path_packfile, "rb");
426 	if (packfile == NULL) {
427 		err = got_error_from_errno();
428 		free(path_packfile);
429 		return err;
430 	}
431 	err = read_packfile_hdr(packfile, packidx);
432 	if (err) {
433 		fclose(packfile);
434 		return err;
435 	}
436 
437 	for (i = 0; i < nitems(repo->pack_cache); i++) {
438 		if (repo->pack_cache[i].packidx == NULL)
439 			break;
440 	}
441 
442 	if (i == nitems(repo->pack_cache)) {
443 		got_packidx_close(repo->pack_cache[i - 1].packidx);
444 		fclose(repo->pack_cache[i - 1].packfile);
445 		free(repo->pack_cache[i - 1].path_packfile);
446 		memmove(&repo->pack_cache[1], &repo->pack_cache[0],
447 		    sizeof(repo->pack_cache) - sizeof(repo->pack_cache[0]));
448 		i = 0;
449 	}
450 
451 	repo->pack_cache[i].packidx = dup_packidx(packidx);
452 	if (repo->pack_cache[i].packidx != NULL) {
453 		repo->pack_cache[i].packfile = packfile;
454 		repo->pack_cache[i].path_packfile = path_packfile;
455 	} else {
456 		fclose(packfile);
457 		free(path_packfile);
458 	}
459 	return NULL;
460 }
461 
462 static const struct got_error *
463 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
464     struct got_repository *repo, struct got_object_id *id)
465 {
466 	const struct got_error *err;
467 	char *path_packdir;
468 	DIR *packdir;
469 	struct dirent *dent;
470 	char *path_packidx;
471 	int i;
472 
473 	/* Search pack cache. */
474 	for (i = 0; i < nitems(repo->pack_cache); i++) {
475 		if (repo->pack_cache[i].packidx == NULL)
476 			break;
477 		*idx = get_object_idx(repo->pack_cache[i].packidx, id);
478 		if (*idx != -1) {
479 			*packidx = dup_packidx(repo->pack_cache[i].packidx);
480 			if (*packidx == NULL)
481 				return got_error(GOT_ERR_NO_MEM);
482 			return NULL;
483 		}
484 	}
485 	/* No luck. Search the filesystem. */
486 
487 	path_packdir = got_repo_get_path_objects_pack(repo);
488 	if (path_packdir == NULL)
489 		return got_error(GOT_ERR_NO_MEM);
490 
491 	packdir = opendir(path_packdir);
492 	if (packdir == NULL) {
493 		err = got_error_from_errno();
494 		goto done;
495 	}
496 
497 	while ((dent = readdir(packdir)) != NULL) {
498 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
499 			continue;
500 
501 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
502 		    dent->d_name) == -1) {
503 			err = got_error(GOT_ERR_NO_MEM);
504 			goto done;
505 		}
506 
507 		err = got_packidx_open(packidx, path_packidx);
508 		free(path_packidx);
509 		if (err)
510 			goto done;
511 
512 		*idx = get_object_idx(*packidx, id);
513 		if (*idx != -1) {
514 			err = NULL; /* found the object */
515 			cache_pack(*packidx, repo);
516 			goto done;
517 		}
518 
519 		got_packidx_close(*packidx);
520 		*packidx = NULL;
521 	}
522 
523 	err = got_error(GOT_ERR_NO_OBJ);
524 done:
525 	free(path_packdir);
526 	if (packdir && closedir(packdir) != 0 && err == 0)
527 		err = got_error_from_errno();
528 	return err;
529 }
530 
531 static const struct got_error *
532 open_packfile(FILE **packfile, char **path_packfile, int *is_cached,
533     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
534 {
535 	const struct got_error *err;
536 	int i;
537 
538 	*packfile = NULL;
539 	*path_packfile = NULL;
540 	*is_cached = 0;
541 
542 	/* The pack could already be cached after an object search. */
543 	for (i = 0; i < nitems(repo->pack_cache); i++) {
544 		if (repo->pack_cache[i].packidx == NULL)
545 			break;
546 
547 		/* The pack index trailer acts as a cache key. */
548 		if (memcmp(&packidx->trailer,
549 		    &repo->pack_cache[i].packidx->trailer,
550 		    sizeof(packidx->trailer)) != 0)
551 			continue;
552 
553 		*packfile = repo->pack_cache[i].packfile;
554 		*path_packfile = repo->pack_cache[i].path_packfile;
555 		*is_cached = 1;
556 		return NULL;
557 	}
558 	/* No luck. Try the filesystem. */
559 
560 	err = get_packfile_path(path_packfile, repo, packidx);
561 	if (err)
562 		return err;
563 
564 	*packfile = fopen(*path_packfile, "rb");
565 	if (*packfile == NULL) {
566 		err = got_error_from_errno();
567 		free(*path_packfile);
568 		return err;
569 	}
570 
571 	err = read_packfile_hdr(*packfile, packidx);
572 	if (err) {
573 		fclose(*packfile);
574 		*packfile = NULL;
575 	}
576 	return err;
577 }
578 
579 static const struct got_error *
580 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
581     FILE *packfile)
582 {
583 	uint8_t t = 0;
584 	uint64_t s = 0;
585 	uint8_t sizeN;
586 	size_t n;
587 	int i = 0;
588 
589 	do {
590 		/* We do not support size values which don't fit in 64 bit. */
591 		if (i > 9)
592 			return got_error(GOT_ERR_NO_SPACE);
593 
594 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
595 		if (n != 1)
596 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
597 
598 		if (i == 0) {
599 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
600 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
601 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
602 		} else {
603 			size_t shift = 4 + 7 * (i - 1);
604 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
605 		}
606 		i++;
607 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
608 
609 	*type = t;
610 	*size = s;
611 	*len = i * sizeof(sizeN);
612 	return NULL;
613 }
614 
615 static const struct got_error *
616 open_plain_object(struct got_object **obj, const char *path_packfile,
617     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
618 {
619 	*obj = calloc(1, sizeof(**obj));
620 	if (*obj == NULL)
621 		return got_error(GOT_ERR_NO_MEM);
622 
623 	(*obj)->path_packfile = strdup(path_packfile);
624 	if ((*obj)->path_packfile == NULL) {
625 		free(*obj);
626 		*obj = NULL;
627 		return got_error(GOT_ERR_NO_MEM);
628 	}
629 
630 	(*obj)->type = type;
631 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
632 	(*obj)->hdrlen = 0;
633 	(*obj)->size = size;
634 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
635 	(*obj)->pack_offset = offset;
636 
637 	return NULL;
638 }
639 
640 static const struct got_error *
641 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
642 {
643 	int64_t o = 0;
644 	uint8_t offN;
645 	size_t n;
646 	int i = 0;
647 
648 	do {
649 		/* We do not support offset values which don't fit in 64 bit. */
650 		if (i > 8)
651 			return got_error(GOT_ERR_NO_SPACE);
652 
653 		n = fread(&offN, sizeof(offN), 1, packfile);
654 		if (n != 1)
655 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
656 
657 		if (i == 0)
658 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
659 		else {
660 			o++;
661 			o <<= 7;
662 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
663 		}
664 		i++;
665 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
666 
667 	*offset = o;
668 	*len = i * sizeof(offN);
669 	return NULL;
670 }
671 
672 static const struct got_error *
673 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
674 {
675 	const struct got_error *err;
676 	int64_t negoffset;
677 	size_t negofflen;
678 
679 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
680 	if (err)
681 		return err;
682 
683 	/* Compute the base object's offset (must be in the same pack file). */
684 	*base_offset = (offset - negoffset);
685 	if (*base_offset <= 0)
686 		return got_error(GOT_ERR_BAD_PACKFILE);
687 
688 	return NULL;
689 }
690 
691 static const struct got_error *
692 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
693     FILE *, const char *, off_t, size_t, int, size_t);
694 
695 static const struct got_error *
696 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
697     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
698     size_t delta_data_offset)
699 {
700 	struct got_delta *delta;
701 
702 	delta = got_delta_open(path_packfile, delta_offset, tslen,
703 	    delta_type, delta_size, delta_data_offset);
704 	if (delta == NULL)
705 		return got_error(GOT_ERR_NO_MEM);
706 	/* delta is freed in got_object_close() */
707 	deltas->nentries++;
708 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
709 	return NULL;
710 }
711 
712 static const struct got_error *
713 resolve_offset_delta(struct got_delta_chain *deltas,
714     struct got_repository *repo, FILE *packfile, const char *path_packfile,
715     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size)
716 
717 {
718 	const struct got_error *err;
719 	off_t base_offset;
720 	uint8_t base_type;
721 	uint64_t base_size;
722 	size_t base_tslen;
723 	off_t delta_data_offset;
724 
725 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
726 	if (err)
727 		return err;
728 
729 	delta_data_offset = ftello(packfile);
730 	if (delta_data_offset == -1)
731 		return got_error_from_errno();
732 
733 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
734 	    delta_type, delta_size, delta_data_offset);
735 	if (err)
736 		return err;
737 
738 	/* An offset delta must be in the same packfile. */
739 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
740 		return got_error_from_errno();
741 
742 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
743 	    packfile);
744 	if (err)
745 		return err;
746 
747 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
748 	    base_offset, base_tslen, base_type, base_size);
749 }
750 
751 static const struct got_error *
752 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
753     FILE *packfile, const char *path_packfile, off_t delta_offset,
754     size_t tslen, int delta_type, size_t delta_size)
755 {
756 	const struct got_error *err;
757 	struct got_object_id id;
758 	struct got_packidx_v2_hdr *packidx;
759 	int idx;
760 	off_t base_offset;
761 	uint8_t base_type;
762 	uint64_t base_size;
763 	size_t base_tslen;
764 	size_t n;
765 	FILE *base_packfile = NULL;
766 	char *path_base_packfile = NULL;
767 	int pack_cached = 0;
768 	off_t delta_data_offset;
769 
770 	n = fread(&id, sizeof(id), 1, packfile);
771 	if (n != 1)
772 		return got_ferror(packfile, GOT_ERR_IO);
773 
774 	delta_data_offset = ftello(packfile);
775 	if (delta_data_offset == -1)
776 		return got_error_from_errno();
777 
778 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
779 	    delta_type, delta_size, delta_data_offset);
780 	if (err)
781 		return err;
782 
783 	err = search_packidx(&packidx, &idx, repo, &id);
784 	if (err)
785 		return err;
786 
787 	base_offset = get_object_offset(packidx, idx);
788 	if (base_offset == (uint64_t)-1) {
789 		got_packidx_close(packidx);
790 		return got_error(GOT_ERR_BAD_PACKIDX);
791 	}
792 
793 	err = open_packfile(&base_packfile, &path_base_packfile, &pack_cached,
794 	    repo, packidx);
795 	got_packidx_close(packidx);
796 	if (err)
797 		return err;
798 
799 	if (fseeko(base_packfile, base_offset, SEEK_SET) != 0) {
800 		err = got_error_from_errno();
801 		goto done;
802 	}
803 
804 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
805 	    base_packfile);
806 	if (err)
807 		goto done;
808 
809 	err = resolve_delta_chain(deltas, repo, base_packfile,
810 	    path_base_packfile, base_offset, base_tslen, base_type,
811 	    base_size);
812 done:
813 	if (!pack_cached) {
814 		free(path_base_packfile);
815 		if (base_packfile && fclose(base_packfile) == -1 && err == 0)
816 			err = got_error_from_errno();
817 	}
818 	return err;
819 }
820 
821 static const struct got_error *
822 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
823     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
824     int delta_type, size_t delta_size)
825 {
826 	const struct got_error *err = NULL;
827 
828 	switch (delta_type) {
829 	case GOT_OBJ_TYPE_COMMIT:
830 	case GOT_OBJ_TYPE_TREE:
831 	case GOT_OBJ_TYPE_BLOB:
832 	case GOT_OBJ_TYPE_TAG:
833 		/* Plain types are the final delta base. Recursion ends. */
834 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
835 		    delta_type, delta_size, 0);
836 		break;
837 	case GOT_OBJ_TYPE_OFFSET_DELTA:
838 		err = resolve_offset_delta(deltas, repo, packfile,
839 		    path_packfile, delta_offset, tslen, delta_type,
840 		    delta_size);
841 		break;
842 	case GOT_OBJ_TYPE_REF_DELTA:
843 		err = resolve_ref_delta(deltas, repo, packfile,
844 		    path_packfile, delta_offset, tslen, delta_type,
845 		    delta_size);
846 		break;
847 	default:
848 		return got_error(GOT_ERR_NOT_IMPL);
849 	}
850 
851 	return err;
852 }
853 
854 static const struct got_error *
855 open_delta_object(struct got_object **obj, struct got_repository *repo,
856     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
857     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
858     int delta_type, size_t delta_size)
859 {
860 	const struct got_error *err = NULL;
861 	int resolved_type;
862 
863 	*obj = calloc(1, sizeof(**obj));
864 	if (*obj == NULL)
865 		return got_error(GOT_ERR_NO_MEM);
866 
867 	(*obj)->flags = 0;
868 	(*obj)->hdrlen = 0;
869 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
870 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
871 	(*obj)->pack_offset = offset + tslen;
872 
873 	(*obj)->path_packfile = strdup(path_packfile);
874 	if ((*obj)->path_packfile == NULL) {
875 		err = got_error(GOT_ERR_NO_MEM);
876 		goto done;
877 	}
878 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
879 
880 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
881 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
882 
883 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
884 	    path_packfile, offset, tslen, delta_type, delta_size);
885 	if (err)
886 		goto done;
887 
888 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
889 	if (err)
890 		goto done;
891 	(*obj)->type = resolved_type;
892 
893 done:
894 	if (err) {
895 		got_object_close(*obj);
896 		*obj = NULL;
897 	}
898 	return err;
899 }
900 
901 static const struct got_error *
902 open_packed_object(struct got_object **obj, struct got_repository *repo,
903     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
904 {
905 	const struct got_error *err = NULL;
906 	off_t offset;
907 	char *path_packfile = NULL;
908 	FILE *packfile = NULL;
909 	int pack_cached = 0;
910 	uint8_t type;
911 	uint64_t size;
912 	size_t tslen;
913 
914 	*obj = NULL;
915 
916 	offset = get_object_offset(packidx, idx);
917 	if (offset == (uint64_t)-1)
918 		return got_error(GOT_ERR_BAD_PACKIDX);
919 
920 	err = open_packfile(&packfile, &path_packfile, &pack_cached,
921 	    repo, packidx);
922 	if (err)
923 		return err;
924 
925 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
926 		err = got_error_from_errno();
927 		goto done;
928 	}
929 
930 	err = parse_object_type_and_size(&type, &size, &tslen, packfile);
931 	if (err)
932 		goto done;
933 
934 	switch (type) {
935 	case GOT_OBJ_TYPE_COMMIT:
936 	case GOT_OBJ_TYPE_TREE:
937 	case GOT_OBJ_TYPE_BLOB:
938 	case GOT_OBJ_TYPE_TAG:
939 		err = open_plain_object(obj, path_packfile, id, type,
940 		    offset + tslen, size);
941 		break;
942 
943 	case GOT_OBJ_TYPE_OFFSET_DELTA:
944 	case GOT_OBJ_TYPE_REF_DELTA:
945 		err = open_delta_object(obj, repo, packidx, path_packfile,
946 		    packfile, id, offset, tslen, type, size);
947 		break;
948 
949 	default:
950 		err = got_error(GOT_ERR_NOT_IMPL);
951 		goto done;
952 	}
953 done:
954 	if (!pack_cached) {
955 		free(path_packfile);
956 		if (packfile && fclose(packfile) == -1 && err == 0)
957 			err = got_error_from_errno();
958 	}
959 	return err;
960 }
961 
962 const struct got_error *
963 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
964     struct got_repository *repo)
965 {
966 	const struct got_error *err = NULL;
967 	struct got_packidx_v2_hdr *packidx = NULL;
968 	int idx;
969 
970 	err = search_packidx(&packidx, &idx, repo, id);
971 	if (err)
972 		return err;
973 
974 	err = open_packed_object(obj, repo, packidx, idx, id);
975 	got_packidx_close(packidx);
976 	return err;
977 }
978 
979 static const struct got_error *
980 get_delta_sizes(uint64_t *base_size, uint64_t *result_size,
981     struct got_delta *delta, FILE *packfile)
982 {
983 	const struct got_error *err;
984 	uint8_t *delta_buf = NULL;
985 	size_t delta_len = 0;
986 
987 	if (fseeko(packfile, delta->data_offset, SEEK_SET) != 0) {
988 		err = got_error_from_errno();
989 		return err;
990 	}
991 
992 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
993 	if (err)
994 		return err;
995 
996 	err = got_delta_get_sizes(base_size, result_size, delta_buf, delta_len);
997 	free(delta_buf);
998 	return err;
999 }
1000 
1001 static const struct got_error *
1002 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
1003     FILE *packfile)
1004 {
1005 	struct got_delta *delta;
1006 	uint64_t base_size = 0, result_size = 0;
1007 
1008 	*max_size = 0;
1009 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1010 		/* Plain object types are the delta base. */
1011 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1012 		    delta->type != GOT_OBJ_TYPE_TREE &&
1013 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1014 		    delta->type != GOT_OBJ_TYPE_TAG) {
1015 			const struct got_error *err;
1016 			err = get_delta_sizes(&base_size, &result_size, delta,
1017 			    packfile);
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 void
1032 clear_delta_cache_entry(struct got_delta_cache_entry *entry)
1033 {
1034 	entry->data_offset = 0;
1035 	free(entry->delta_buf);
1036 	entry->delta_buf = NULL;
1037 	entry->delta_len = 0;
1038 }
1039 
1040 const struct got_error *
1041 add_delta_cache_entry(struct got_delta_cache *cache, off_t data_offset,
1042     uint8_t *delta_buf, size_t delta_len)
1043 {
1044 	int i;
1045 	struct got_delta_cache_entry *entry;
1046 
1047 	for (i = 0; i < nitems(cache->deltas); i++) {
1048 		entry = &cache->deltas[i];
1049 		if (entry->data_offset == 0)
1050 			break;
1051 	}
1052 
1053 	if (i == nitems(cache->deltas)) {
1054 		entry = &cache->deltas[i - 1];
1055 		clear_delta_cache_entry(entry);
1056 		memmove(&cache->deltas[1], &cache->deltas[0],
1057 		    sizeof(cache->deltas) - sizeof(cache->deltas[0]));
1058 		i = 0;
1059 	}
1060 
1061 	entry = &cache->deltas[i];
1062 	entry->data_offset = data_offset;
1063 	entry->delta_buf = delta_buf;
1064 	entry->delta_len = delta_len;
1065 	return NULL;
1066 }
1067 
1068 const struct got_error *
1069 cache_delta(off_t data_offset, uint8_t *delta_buf, size_t delta_len,
1070     const char *path_packfile, struct got_repository *repo)
1071 {
1072 	struct got_delta_cache *cache;
1073 	int i;
1074 
1075 	for (i = 0; i < nitems(repo->delta_cache); i++) {
1076 		cache = &repo->delta_cache[i];
1077 		if (cache->path_packfile == NULL)
1078 			break;
1079 		if (strcmp(cache->path_packfile, path_packfile) == 0)
1080 			return add_delta_cache_entry(cache, data_offset,
1081 			    delta_buf, delta_len);
1082 	}
1083 
1084 	if (i == nitems(repo->delta_cache)) {
1085 		int j;
1086 		cache = &repo->delta_cache[i - 1];
1087 		free(cache->path_packfile);
1088 		cache->path_packfile = NULL;
1089 		for (j = 0; j < nitems(cache->deltas); j++) {
1090 			struct got_delta_cache_entry *entry = &cache->deltas[j];
1091 			if (entry->data_offset == 0)
1092 				break;
1093 			clear_delta_cache_entry(entry);
1094 		}
1095 		memmove(&repo->delta_cache[1], &repo->delta_cache[0],
1096 		    sizeof(repo->delta_cache) - sizeof(repo->delta_cache[0]));
1097 		i = 0;
1098 	}
1099 
1100 	cache = &repo->delta_cache[i];
1101 	cache->path_packfile = strdup(path_packfile);
1102 	if (cache->path_packfile == NULL)
1103 		return got_error(GOT_ERR_NO_MEM);
1104 	return add_delta_cache_entry(cache, data_offset, delta_buf, delta_len);
1105 }
1106 
1107 void
1108 get_cached_delta(uint8_t **delta_buf, size_t *delta_len,
1109     off_t data_offset, const char *path_packfile, struct got_repository *repo)
1110 {
1111 	struct got_delta_cache *cache;
1112 	struct got_delta_cache_entry *entry;
1113 	int i;
1114 
1115 	*delta_buf = NULL;
1116 	*delta_len = 0;
1117 
1118 	for (i = 0; i < nitems(repo->delta_cache); i++) {
1119 		cache = &repo->delta_cache[i];
1120 		if (cache->path_packfile == NULL)
1121 			return;
1122 		if (strcmp(cache->path_packfile, path_packfile) == 0)
1123 			break;
1124 	}
1125 
1126 	if (i == nitems(repo->delta_cache))
1127 		return;
1128 
1129 	for (i = 0; i < nitems(cache->deltas); i++) {
1130 		entry = &cache->deltas[i];
1131 		if (entry->data_offset == 0)
1132 			break;
1133 		if (entry->data_offset == data_offset) {
1134 			*delta_buf = entry->delta_buf;
1135 			*delta_len = entry->delta_len;
1136 			break;
1137 		}
1138 	}
1139 }
1140 
1141 static const struct got_error *
1142 dump_delta_chain_to_file(struct got_delta_chain *deltas, FILE *outfile,
1143     FILE *packfile, const char *path_packfile, struct got_repository *repo)
1144 {
1145 	const struct got_error *err = NULL;
1146 	struct got_delta *delta;
1147 	FILE *base_file = NULL, *accum_file = NULL;
1148 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1149 	size_t accum_size;
1150 	uint64_t max_size;
1151 	int n = 0;
1152 
1153 	if (SIMPLEQ_EMPTY(&deltas->entries))
1154 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1155 
1156 	/* We process small enough files entirely in memory for speed. */
1157 	err = get_delta_chain_max_size(&max_size, deltas, packfile);
1158 	if (err)
1159 		return err;
1160 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1161 		accum_buf = malloc(max_size);
1162 		if (accum_buf == NULL)
1163 			return got_error(GOT_ERR_NO_MEM);
1164 	} else {
1165 		base_file = got_opentemp();
1166 		if (base_file == NULL)
1167 			return got_error_from_errno();
1168 
1169 		accum_file = got_opentemp();
1170 		if (accum_file == NULL) {
1171 			err = got_error_from_errno();
1172 			fclose(base_file);
1173 			return err;
1174 		}
1175 	}
1176 
1177 	/* Deltas are ordered in ascending order. */
1178 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1179 		uint8_t *delta_buf = NULL;
1180 		size_t delta_len = 0;
1181 
1182 		if (n == 0) {
1183 			size_t base_len;
1184 
1185 			/* Plain object types are the delta base. */
1186 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1187 			    delta->type != GOT_OBJ_TYPE_TREE &&
1188 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1189 			    delta->type != GOT_OBJ_TYPE_TAG) {
1190 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1191 				goto done;
1192 			}
1193 
1194 			if (fseeko(packfile, delta->offset + delta->tslen,
1195 			    SEEK_SET) != 0) {
1196 				err = got_error_from_errno();
1197 				goto done;
1198 			}
1199 			if (base_file)
1200 				err = got_inflate_to_file(&delta_len,
1201 				    packfile, base_file);
1202 			else {
1203 				err = got_inflate_to_mem(&base_buf, &base_len,
1204 				    packfile);
1205 				if (base_len < max_size) {
1206 					uint8_t *p;
1207 					p = reallocarray(base_buf, 1, max_size);
1208 					if (p == NULL) {
1209 						err = got_error(GOT_ERR_NO_MEM);
1210 						goto done;
1211 					}
1212 					base_buf = p;
1213 				}
1214 			}
1215 			if (err)
1216 				goto done;
1217 			n++;
1218 			if (base_file)
1219 				rewind(base_file);
1220 			continue;
1221 		}
1222 
1223 		get_cached_delta(&delta_buf, &delta_len, delta->data_offset,
1224 		    path_packfile, repo);
1225 		if (delta_buf == NULL) {
1226 			if (fseeko(packfile, delta->data_offset, SEEK_SET)
1227 			    != 0) {
1228 				err = got_error_from_errno();
1229 				goto done;
1230 			}
1231 
1232 			/* Delta streams should always fit in memory. */
1233 			err = got_inflate_to_mem(&delta_buf, &delta_len,
1234 			    packfile);
1235 			if (err)
1236 				goto done;
1237 
1238 			err = cache_delta(delta->data_offset, delta_buf,
1239 			    delta_len, path_packfile, repo);
1240 			if (err)
1241 				goto done;
1242 		}
1243 		/* delta_buf is now cached */
1244 
1245 		if (base_buf) {
1246 			err = got_delta_apply_in_mem(base_buf, delta_buf,
1247 			    delta_len, accum_buf, &accum_size);
1248 			n++;
1249 		} else {
1250 			err = got_delta_apply(base_file, delta_buf, delta_len,
1251 			    /* Final delta application writes to output file. */
1252 			    ++n < deltas->nentries ? accum_file : outfile);
1253 		}
1254 		if (err)
1255 			goto done;
1256 
1257 		if (n < deltas->nentries) {
1258 			/* Accumulated delta becomes the new base. */
1259 			if (base_buf) {
1260 				uint8_t *tmp = accum_buf;
1261 				accum_buf = base_buf;
1262 				base_buf = tmp;
1263 			} else {
1264 				FILE *tmp = accum_file;
1265 				accum_file = base_file;
1266 				base_file = tmp;
1267 				rewind(base_file);
1268 				rewind(accum_file);
1269 			}
1270 		}
1271 	}
1272 
1273 done:
1274 	free(base_buf);
1275 	if (accum_buf) {
1276 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1277 		free(accum_buf);
1278 		if (len != accum_size)
1279 			return got_ferror(outfile, GOT_ERR_IO);
1280 	}
1281 	if (base_file)
1282 		fclose(base_file);
1283 	if (accum_file)
1284 		fclose(accum_file);
1285 	rewind(outfile);
1286 	return err;
1287 }
1288 
1289 static const struct got_error *
1290 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1291     struct got_delta_chain *deltas, FILE *packfile, const char *path_packfile,
1292     struct got_repository *repo)
1293 {
1294 	const struct got_error *err = NULL;
1295 	struct got_delta *delta;
1296 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1297 	size_t accum_size;
1298 	uint64_t max_size;
1299 	int n = 0;
1300 
1301 	*outbuf = NULL;
1302 	*outlen = 0;
1303 
1304 	if (SIMPLEQ_EMPTY(&deltas->entries))
1305 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1306 
1307 	err = get_delta_chain_max_size(&max_size, deltas, packfile);
1308 	if (err)
1309 		return err;
1310 	accum_buf = malloc(max_size);
1311 	if (accum_buf == NULL)
1312 		return got_error(GOT_ERR_NO_MEM);
1313 
1314 	/* Deltas are ordered in ascending order. */
1315 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1316 		uint8_t *delta_buf = NULL;
1317 		size_t delta_len = 0;
1318 
1319 		if (n == 0) {
1320 			size_t base_len;
1321 
1322 			/* Plain object types are the delta base. */
1323 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1324 			    delta->type != GOT_OBJ_TYPE_TREE &&
1325 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1326 			    delta->type != GOT_OBJ_TYPE_TAG) {
1327 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1328 				goto done;
1329 			}
1330 
1331 			if (fseeko(packfile, delta->offset + delta->tslen,
1332 			    SEEK_SET) != 0) {
1333 				err = got_error_from_errno();
1334 				goto done;
1335 			}
1336 			err = got_inflate_to_mem(&base_buf, &base_len,
1337 			    packfile);
1338 			if (base_len < max_size) {
1339 				uint8_t *p;
1340 				p = reallocarray(base_buf, 1, max_size);
1341 				if (p == NULL) {
1342 					err = got_error(GOT_ERR_NO_MEM);
1343 					goto done;
1344 				}
1345 				base_buf = p;
1346 			}
1347 			if (err)
1348 				goto done;
1349 			n++;
1350 			continue;
1351 		}
1352 
1353 		get_cached_delta(&delta_buf, &delta_len, delta->data_offset,
1354 		    path_packfile, repo);
1355 		if (delta_buf == NULL) {
1356 			if (fseeko(packfile, delta->data_offset, SEEK_SET)
1357 			    != 0) {
1358 				err = got_error_from_errno();
1359 				goto done;
1360 			}
1361 
1362 			/* Delta streams should always fit in memory. */
1363 			err = got_inflate_to_mem(&delta_buf, &delta_len,
1364 			    packfile);
1365 			if (err)
1366 				goto done;
1367 
1368 			err = cache_delta(delta->data_offset, delta_buf,
1369 			    delta_len, path_packfile, repo);
1370 			if (err)
1371 				goto done;
1372 		}
1373 		/* delta_buf is now cached */
1374 
1375 		err = got_delta_apply_in_mem(base_buf, delta_buf,
1376 		    delta_len, accum_buf, &accum_size);
1377 		n++;
1378 		if (err)
1379 			goto done;
1380 
1381 		if (n < deltas->nentries) {
1382 			/* Accumulated delta becomes the new base. */
1383 			uint8_t *tmp = accum_buf;
1384 			accum_buf = base_buf;
1385 			base_buf = tmp;
1386 		}
1387 	}
1388 
1389 done:
1390 	free(base_buf);
1391 	if (err) {
1392 		free(accum_buf);
1393 		*outbuf = NULL;
1394 		*outlen = 0;
1395 	} else {
1396 		*outbuf = accum_buf;
1397 		*outlen = accum_size;
1398 	}
1399 	return err;
1400 }
1401 
1402 const struct got_error *
1403 got_packfile_extract_object(FILE **f, struct got_object *obj,
1404     struct got_repository *repo)
1405 {
1406 	const struct got_error *err = NULL;
1407 	FILE *packfile = NULL;
1408 
1409 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1410 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1411 
1412 	*f = got_opentemp();
1413 	if (*f == NULL) {
1414 		err = got_error(GOT_ERR_FILE_OPEN);
1415 		goto done;
1416 	}
1417 
1418 	packfile = fopen(obj->path_packfile, "rb");
1419 	if (packfile == NULL) {
1420 		err = got_error_from_errno();
1421 		goto done;
1422 	}
1423 
1424 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1425 		if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
1426 			err = got_error_from_errno();
1427 			goto done;
1428 		}
1429 
1430 		err = got_inflate_to_file(&obj->size, packfile, *f);
1431 	} else
1432 		err = dump_delta_chain_to_file(&obj->deltas, *f, packfile,
1433 		    obj->path_packfile, repo);
1434 done:
1435 	if (packfile)
1436 		fclose(packfile);
1437 	if (err && *f)
1438 		fclose(*f);
1439 	return err;
1440 }
1441 
1442 const struct got_error *
1443 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1444     struct got_object *obj, struct got_repository *repo)
1445 {
1446 	const struct got_error *err = NULL;
1447 	FILE *packfile = NULL;
1448 
1449 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1450 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1451 
1452 	packfile = fopen(obj->path_packfile, "rb");
1453 	if (packfile == NULL) {
1454 		err = got_error_from_errno();
1455 		goto done;
1456 	}
1457 
1458 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1459 		if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
1460 			err = got_error_from_errno();
1461 			goto done;
1462 		}
1463 
1464 		err = got_inflate_to_mem(buf, len, packfile);
1465 	} else
1466 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, packfile,
1467 		    obj->path_packfile, repo);
1468 done:
1469 	if (packfile)
1470 		fclose(packfile);
1471 	return err;
1472 }