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Date:: Mon Apr 2 10:46:33 2018 UTC
Message:: put a limit on delta chain recursion
Actions:: History | Blame | Raw File
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 <fcntl.h>
23 #include <errno.h>
24 #include <stdio.h>
25 #include <stdint.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <limits.h>
29 #include <sha1.h>
30 #include <endian.h>
31 #include <zlib.h>
32 
33 #include "got_error.h"
34 #include "got_object.h"
35 #include "got_repository.h"
36 
37 #include "got_lib_sha1.h"
38 #include "got_lib_pack.h"
39 #include "got_lib_path.h"
40 #include "got_lib_delta.h"
41 #include "got_lib_zbuf.h"
42 #include "got_lib_object.h"
43 #include "got_lib_repository.h"
44 
45 #ifndef nitems
46 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
47 #endif
48 
49 #define GOT_PACK_PREFIX		"pack-"
50 #define GOT_PACKFILE_SUFFIX	".pack"
51 #define GOT_PACKIDX_SUFFIX		".idx"
52 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
53 				SHA1_DIGEST_STRING_LENGTH - 1 + \
54 				strlen(GOT_PACKFILE_SUFFIX))
55 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
56 				SHA1_DIGEST_STRING_LENGTH - 1 + \
57 				strlen(GOT_PACKIDX_SUFFIX))
58 
59 #define GOT_DELTA_CHAIN_RECURSION_MAX	100
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, ".idx") == 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, ".pack") == 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_v2_hdr **packidx, const char *path)
123 {
124 	struct got_packidx_v2_hdr *p;
125 	FILE *f;
126 	const struct got_error *err = NULL;
127 	size_t n, nobj, packfile_size;
128 	SHA1_CTX ctx;
129 	uint8_t sha1[SHA1_DIGEST_LENGTH];
130 
131 	SHA1Init(&ctx);
132 
133 	f = fopen(path, "rb");
134 	if (f == NULL)
135 		return got_error_from_errno();
136 
137 	err = get_packfile_size(&packfile_size, path);
138 	if (err)
139 		return err;
140 
141 	p = calloc(1, sizeof(*p));
142 	if (p == NULL) {
143 		err = got_error_from_errno();
144 		goto done;
145 	}
146 
147 	n = fread(&p->magic, sizeof(p->magic), 1, f);
148 	if (n != 1) {
149 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
150 		goto done;
151 	}
152 
153 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
154 		err = got_error(GOT_ERR_BAD_PACKIDX);
155 		goto done;
156 	}
157 
158 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
159 
160 	n = fread(&p->version, sizeof(p->version), 1, f);
161 	if (n != 1) {
162 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
163 		goto done;
164 	}
165 
166 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
167 		err = got_error(GOT_ERR_BAD_PACKIDX);
168 		goto done;
169 	}
170 
171 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
172 
173 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
174 	if (n != 1) {
175 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
176 		goto done;
177 	}
178 
179 	err = verify_fanout_table(p->fanout_table);
180 	if (err)
181 		goto done;
182 
183 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
184 
185 	nobj = betoh32(p->fanout_table[0xff]);
186 
187 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
188 	if (p->sorted_ids == NULL) {
189 		err = got_error_from_errno();
190 		goto done;
191 	}
192 
193 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
194 	if (n != nobj) {
195 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
196 		goto done;
197 	}
198 
199 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
200 	    nobj * sizeof(*p->sorted_ids));
201 
202 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
203 	if (p->crc32 == NULL) {
204 		err = got_error_from_errno();
205 		goto done;
206 	}
207 
208 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
209 	if (n != nobj) {
210 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
211 		goto done;
212 	}
213 
214 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
215 
216 	p->offsets = calloc(nobj, sizeof(*p->offsets));
217 	if (p->offsets == NULL) {
218 		err = got_error_from_errno();
219 		goto done;
220 	}
221 
222 	n = fread(p->offsets, sizeof(*p->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->offsets, nobj * sizeof(*p->offsets));
229 
230 	/* Large file offsets are contained only in files > 2GB. */
231 	if (packfile_size <= 0x80000000)
232 		goto checksum;
233 
234 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
235 	if (p->large_offsets == NULL) {
236 		err = got_error_from_errno();
237 		goto done;
238 	}
239 
240 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
241 	if (n != nobj) {
242 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
243 		goto done;
244 	}
245 
246 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
247 	    nobj * sizeof(*p->large_offsets));
248 
249 checksum:
250 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
251 	if (n != 1) {
252 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
253 		goto done;
254 	}
255 
256 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
257 	SHA1Final(sha1, &ctx);
258 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
259 		err = got_error(GOT_ERR_PACKIDX_CSUM);
260 done:
261 	fclose(f);
262 	if (err)
263 		got_packidx_close(p);
264 	else
265 		*packidx = p;
266 	return err;
267 }
268 
269 void
270 got_packidx_close(struct got_packidx_v2_hdr *packidx)
271 {
272 	free(packidx->sorted_ids);
273 	free(packidx->offsets);
274 	free(packidx->crc32);
275 	free(packidx->large_offsets);
276 	free(packidx);
277 }
278 
279 static int
280 is_packidx_filename(const char *name, size_t len)
281 {
282 	if (len != GOT_PACKIDX_NAMELEN)
283 		return 0;
284 
285 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
286 		return 0;
287 
288 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
289 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
290 		return 0;
291 
292 	return 1;
293 }
294 
295 static off_t
296 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
297 {
298 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
299 	uint32_t offset = betoh32(packidx->offsets[idx]);
300 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
301 		uint64_t loffset;
302 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
303 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
304 			return -1;
305 		loffset = betoh64(packidx->large_offsets[idx]);
306 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
307 	}
308 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
309 }
310 
311 static const struct got_error *
312 get_packfile_path(char **path_packfile, struct got_repository *repo,
313     struct got_packidx_v2_hdr *packidx);
314 
315 static int
316 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id, struct got_repository *repo)
317 {
318 	u_int8_t id0 = id->sha1[0];
319 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
320 	int i = 0;
321 
322 	if (id0 > 0)
323 		i = betoh32(packidx->fanout_table[id0 - 1]);
324 
325 	while (i < totobj) {
326 		struct got_object_id *oid = &packidx->sorted_ids[i];
327 		int cmp = got_object_id_cmp(id, oid);
328 
329 		if (cmp == 0)
330 			return i;
331 		i++;
332 	}
333 
334 	return -1;
335 }
336 
337 static struct got_packidx_v2_hdr *
338 dup_packidx(struct got_packidx_v2_hdr *packidx)
339 {
340 	struct got_packidx_v2_hdr *p;
341 	size_t nobj;
342 
343 	p = calloc(1, sizeof(*p));
344 	if (p == NULL)
345 		return NULL;
346 
347 	memcpy(p, packidx, sizeof(*p));
348 	p->sorted_ids = NULL;
349 	p->crc32 = NULL;
350 	p->offsets = NULL;
351 	p->large_offsets = NULL;
352 
353 	nobj = betoh32(p->fanout_table[0xff]);
354 
355 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
356 	if (p->sorted_ids == NULL)
357 		goto err;
358 	memcpy(p->sorted_ids, packidx->sorted_ids,
359 	    nobj * sizeof(*p->sorted_ids));
360 
361 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
362 	if (p->crc32 == NULL)
363 		goto err;
364 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
365 
366 	p->offsets = calloc(nobj, sizeof(*p->offsets));
367 	if (p->offsets == NULL)
368 		goto err;
369 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
370 
371 	if (p->large_offsets) {
372 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
373 		if (p->large_offsets == NULL)
374 			goto err;
375 		memcpy(p->large_offsets, packidx->large_offsets,
376 		    nobj * sizeof(*p->large_offsets));
377 	}
378 
379 	return p;
380 
381 err:
382 	free(p->large_offsets);
383 	free(p->offsets);
384 	free(p->crc32);
385 	free(p->sorted_ids);
386 	free(p);
387 	return NULL;
388 }
389 
390 static void
391 cache_packidx(struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
392 {
393 	int i;
394 
395 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
396 		if (repo->packidx_cache[i] == NULL)
397 			break;
398 	}
399 
400 	if (i == nitems(repo->packidx_cache)) {
401 		got_packidx_close(repo->packidx_cache[i - 1]);
402 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
403 		    sizeof(repo->packidx_cache) -
404 		    sizeof(repo->packidx_cache[0]));
405 		i = 0;
406 	}
407 
408 	repo->packidx_cache[i] = dup_packidx(packidx);
409 }
410 
411 static const struct got_error *
412 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
413     struct got_repository *repo, struct got_object_id *id)
414 {
415 	const struct got_error *err;
416 	char *path_packdir;
417 	DIR *packdir;
418 	struct dirent *dent;
419 	char *path_packidx;
420 	int i;
421 
422 	/* Search pack index cache. */
423 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
424 		if (repo->packidx_cache[i] == NULL)
425 			break;
426 		*idx = get_object_idx(repo->packidx_cache[i], id, repo);
427 		if (*idx != -1) {
428 			*packidx = repo->packidx_cache[i];
429 			return NULL;
430 		}
431 	}
432 	/* No luck. Search the filesystem. */
433 
434 	path_packdir = got_repo_get_path_objects_pack(repo);
435 	if (path_packdir == NULL)
436 		return got_error_from_errno();
437 
438 	packdir = opendir(path_packdir);
439 	if (packdir == NULL) {
440 		err = got_error_from_errno();
441 		goto done;
442 	}
443 
444 	while ((dent = readdir(packdir)) != NULL) {
445 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
446 			continue;
447 
448 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
449 		    dent->d_name) == -1) {
450 			err = got_error_from_errno();
451 			goto done;
452 		}
453 
454 		err = got_packidx_open(packidx, path_packidx);
455 		free(path_packidx);
456 		if (err)
457 			goto done;
458 
459 		*idx = get_object_idx(*packidx, id, repo);
460 		if (*idx != -1) {
461 			err = NULL; /* found the object */
462 			cache_packidx(*packidx, repo);
463 			goto done;
464 		}
465 
466 		got_packidx_close(*packidx);
467 		*packidx = NULL;
468 	}
469 
470 	err = got_error(GOT_ERR_NO_OBJ);
471 done:
472 	free(path_packdir);
473 	if (packdir && closedir(packdir) != 0 && err == 0)
474 		err = got_error_from_errno();
475 	return err;
476 }
477 
478 static const struct got_error *
479 get_packfile_path(char **path_packfile, struct got_repository *repo,
480     struct got_packidx_v2_hdr *packidx)
481 {
482 	char *path_packdir;
483 	char hex[SHA1_DIGEST_STRING_LENGTH];
484 	char *sha1str;
485 
486 	path_packdir = got_repo_get_path_objects_pack(repo);
487 	if (path_packdir == NULL)
488 		return got_error_from_errno();
489 
490 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
491 	    hex, sizeof(hex));
492 	if (sha1str == NULL)
493 		return got_error(GOT_ERR_PACKIDX_CSUM);
494 
495 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
496 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
497 		*path_packfile = NULL;
498 		return got_error_from_errno();
499 	}
500 
501 	return NULL;
502 }
503 
504 const struct got_error *
505 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
506 {
507 	const struct got_error *err = NULL;
508 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
509 	struct got_packfile_hdr hdr;
510 	size_t n;
511 
512 	n = fread(&hdr, sizeof(hdr), 1, f);
513 	if (n != 1)
514 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
515 
516 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
517 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
518 	    betoh32(hdr.nobjects) != totobj)
519 		err = got_error(GOT_ERR_BAD_PACKFILE);
520 
521 	return err;
522 }
523 
524 static const struct got_error *
525 open_packfile(FILE **packfile, const char *path_packfile,
526     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
527 {
528 	const struct got_error *err = NULL;
529 
530 	*packfile = NULL;
531 
532 	*packfile = fopen(path_packfile, "rb");
533 	if (*packfile == NULL) {
534 		err = got_error_from_errno();
535 		return err;
536 	}
537 
538 	if (packidx) {
539 		err = read_packfile_hdr(*packfile, packidx);
540 		if (err) {
541 			fclose(*packfile);
542 			*packfile = NULL;
543 		}
544 	}
545 	return err;
546 }
547 
548 void
549 got_pack_close(struct got_pack *pack)
550 {
551 	fclose(pack->packfile);
552 	pack->packfile = NULL;
553 	free(pack->path_packfile);
554 	pack->path_packfile = NULL;
555 	pack->filesize = 0;
556 }
557 
558 static const struct got_error *
559 cache_pack(struct got_pack **packp, const char *path_packfile,
560     struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
561 {
562 	const struct got_error *err = NULL;
563 	struct got_pack *pack = NULL;
564 	int i;
565 
566 	if (packp)
567 		*packp = NULL;
568 
569 	for (i = 0; i < nitems(repo->packs); i++) {
570 		pack = &repo->packs[i];
571 		if (pack->path_packfile == NULL)
572 			break;
573 		if (strcmp(pack->path_packfile, path_packfile) == 0)
574 			return NULL;
575 	}
576 
577 	if (i == nitems(repo->packs) - 1) {
578 		got_pack_close(&repo->packs[i - 1]);
579 		memmove(&repo->packs[1], &repo->packs[0],
580 		    sizeof(repo->packs) - sizeof(repo->packs[0]));
581 		i = 0;
582 	}
583 
584 	pack = &repo->packs[i];
585 
586 	pack->path_packfile = strdup(path_packfile);
587 	if (pack->path_packfile == NULL) {
588 		err = got_error_from_errno();
589 		goto done;
590 	}
591 
592 	err = open_packfile(&pack->packfile, path_packfile, repo, packidx);
593 	if (err)
594 		goto done;
595 
596 	err = get_packfile_size(&pack->filesize, path_packfile);
597 done:
598 	if (err) {
599 		if (pack)
600 			free(pack->path_packfile);
601 		free(pack);
602 	} else if (packp)
603 		*packp = pack;
604 	return err;
605 }
606 
607 struct got_pack *
608 get_cached_pack(const char *path_packfile, struct got_repository *repo)
609 {
610 	struct got_pack *pack = NULL;
611 	int i;
612 
613 	for (i = 0; i < nitems(repo->packs); i++) {
614 		pack = &repo->packs[i];
615 		if (pack->path_packfile == NULL)
616 			break;
617 		if (strcmp(pack->path_packfile, path_packfile) == 0)
618 			return pack;
619 	}
620 
621 	return NULL;
622 }
623 
624 static const struct got_error *
625 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
626     FILE *packfile)
627 {
628 	uint8_t t = 0;
629 	uint64_t s = 0;
630 	uint8_t sizeN;
631 	size_t n;
632 	int i = 0;
633 
634 	do {
635 		/* We do not support size values which don't fit in 64 bit. */
636 		if (i > 9)
637 			return got_error(GOT_ERR_NO_SPACE);
638 
639 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
640 		if (n != 1)
641 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
642 
643 		if (i == 0) {
644 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
645 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
646 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
647 		} else {
648 			size_t shift = 4 + 7 * (i - 1);
649 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
650 		}
651 		i++;
652 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
653 
654 	*type = t;
655 	*size = s;
656 	*len = i * sizeof(sizeN);
657 	return NULL;
658 }
659 
660 static const struct got_error *
661 open_plain_object(struct got_object **obj, const char *path_packfile,
662     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
663 {
664 	*obj = calloc(1, sizeof(**obj));
665 	if (*obj == NULL)
666 		return got_error_from_errno();
667 
668 	(*obj)->path_packfile = strdup(path_packfile);
669 	if ((*obj)->path_packfile == NULL) {
670 		const struct got_error *err = got_error_from_errno();
671 		free(*obj);
672 		*obj = NULL;
673 		return err;
674 	}
675 
676 	(*obj)->type = type;
677 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
678 	(*obj)->hdrlen = 0;
679 	(*obj)->size = size;
680 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
681 	(*obj)->pack_offset = offset;
682 
683 	return NULL;
684 }
685 
686 static const struct got_error *
687 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
688 {
689 	int64_t o = 0;
690 	uint8_t offN;
691 	size_t n;
692 	int i = 0;
693 
694 	do {
695 		/* We do not support offset values which don't fit in 64 bit. */
696 		if (i > 8)
697 			return got_error(GOT_ERR_NO_SPACE);
698 
699 		n = fread(&offN, sizeof(offN), 1, packfile);
700 		if (n != 1)
701 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
702 
703 		if (i == 0)
704 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
705 		else {
706 			o++;
707 			o <<= 7;
708 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
709 		}
710 		i++;
711 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
712 
713 	*offset = o;
714 	*len = i * sizeof(offN);
715 	return NULL;
716 }
717 
718 static const struct got_error *
719 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
720 {
721 	const struct got_error *err;
722 	int64_t negoffset;
723 	size_t negofflen;
724 
725 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
726 	if (err)
727 		return err;
728 
729 	/* Compute the base object's offset (must be in the same pack file). */
730 	*base_offset = (offset - negoffset);
731 	if (*base_offset <= 0)
732 		return got_error(GOT_ERR_BAD_PACKFILE);
733 
734 	return NULL;
735 }
736 
737 static const struct got_error *
738 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
739     FILE *, const char *, off_t, size_t, int, size_t, unsigned int);
740 
741 static const struct got_error *
742 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
743     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
744     size_t delta_data_offset, uint8_t *delta_buf, size_t delta_len)
745 {
746 	struct got_delta *delta;
747 
748 	delta = got_delta_open(path_packfile, delta_offset, tslen,
749 	    delta_type, delta_size, delta_data_offset, delta_buf,
750 	    delta_len);
751 	if (delta == NULL)
752 		return got_error_from_errno();
753 	/* delta is freed in got_object_close() */
754 	deltas->nentries++;
755 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
756 	return NULL;
757 }
758 
759 static const struct got_error *
760 resolve_offset_delta(struct got_delta_chain *deltas,
761     struct got_repository *repo, FILE *packfile, const char *path_packfile,
762     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size,
763     unsigned int recursion)
764 
765 {
766 	const struct got_error *err;
767 	off_t base_offset;
768 	uint8_t base_type;
769 	uint64_t base_size;
770 	size_t base_tslen;
771 	off_t delta_data_offset;
772 	uint8_t *delta_buf;
773 	size_t delta_len;
774 
775 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
776 	if (err)
777 		return err;
778 
779 	delta_data_offset = ftello(packfile);
780 	if (delta_data_offset == -1)
781 		return got_error_from_errno();
782 
783 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
784 	if (err)
785 		return err;
786 
787 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
788 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
789 	if (err)
790 		return err;
791 
792 	/* An offset delta must be in the same packfile. */
793 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
794 		return got_error_from_errno();
795 
796 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
797 	    packfile);
798 	if (err)
799 		return err;
800 
801 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
802 	    base_offset, base_tslen, base_type, base_size, recursion - 1);
803 }
804 
805 static const struct got_error *
806 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
807     FILE *packfile, const char *path_packfile, off_t delta_offset,
808     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
809 {
810 	const struct got_error *err;
811 	struct got_object_id id;
812 	struct got_packidx_v2_hdr *packidx;
813 	int idx;
814 	off_t base_offset;
815 	uint8_t base_type;
816 	uint64_t base_size;
817 	size_t base_tslen;
818 	size_t n;
819 	char *path_base_packfile;
820 	struct got_pack *base_pack;
821 	off_t delta_data_offset;
822 	uint8_t *delta_buf;
823 	size_t delta_len;
824 
825 	n = fread(&id, sizeof(id), 1, packfile);
826 	if (n != 1)
827 		return got_ferror(packfile, GOT_ERR_IO);
828 
829 	delta_data_offset = ftello(packfile);
830 	if (delta_data_offset == -1)
831 		return got_error_from_errno();
832 
833 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
834 	if (err)
835 		return err;
836 
837 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
838 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
839 	if (err)
840 		return err;
841 
842 	err = search_packidx(&packidx, &idx, repo, &id);
843 	if (err)
844 		return err;
845 
846 	base_offset = get_object_offset(packidx, idx);
847 	if (base_offset == (uint64_t)-1) {
848 		return got_error(GOT_ERR_BAD_PACKIDX);
849 	}
850 
851 	err = get_packfile_path(&path_base_packfile, repo, packidx);
852 	if (err)
853 		return err;
854 
855 	base_pack = get_cached_pack(path_base_packfile, repo);
856 	if (base_pack == NULL) {
857 		err = cache_pack(&base_pack, path_base_packfile, NULL, repo);
858 		if (err)
859 			goto done;
860 	}
861 
862 	if (fseeko(base_pack->packfile, base_offset, SEEK_SET) != 0) {
863 		err = got_error_from_errno();
864 		goto done;
865 	}
866 
867 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
868 	    base_pack->packfile);
869 	if (err)
870 		goto done;
871 
872 	err = resolve_delta_chain(deltas, repo, base_pack->packfile,
873 	    path_base_packfile, base_offset, base_tslen, base_type,
874 	    base_size, recursion - 1);
875 done:
876 	free(path_base_packfile);
877 	return err;
878 }
879 
880 static const struct got_error *
881 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
882     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
883     int delta_type, size_t delta_size, unsigned int recursion)
884 {
885 	const struct got_error *err = NULL;
886 
887 	if (--recursion == 0)
888 		return got_error(GOT_ERR_RECURSION);
889 
890 	switch (delta_type) {
891 	case GOT_OBJ_TYPE_COMMIT:
892 	case GOT_OBJ_TYPE_TREE:
893 	case GOT_OBJ_TYPE_BLOB:
894 	case GOT_OBJ_TYPE_TAG:
895 		/* Plain types are the final delta base. Recursion ends. */
896 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
897 		    delta_type, delta_size, 0, NULL, 0);
898 		break;
899 	case GOT_OBJ_TYPE_OFFSET_DELTA:
900 		err = resolve_offset_delta(deltas, repo, packfile,
901 		    path_packfile, delta_offset, tslen, delta_type,
902 		    delta_size, recursion - 1);
903 		break;
904 	case GOT_OBJ_TYPE_REF_DELTA:
905 		err = resolve_ref_delta(deltas, repo, packfile,
906 		    path_packfile, delta_offset, tslen, delta_type,
907 		    delta_size, recursion - 1);
908 		break;
909 	default:
910 		return got_error(GOT_ERR_OBJ_TYPE);
911 	}
912 
913 	return err;
914 }
915 
916 static const struct got_error *
917 open_delta_object(struct got_object **obj, struct got_repository *repo,
918     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
919     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
920     int delta_type, size_t delta_size)
921 {
922 	const struct got_error *err = NULL;
923 	int resolved_type;
924 
925 	*obj = calloc(1, sizeof(**obj));
926 	if (*obj == NULL)
927 		return got_error_from_errno();
928 
929 	(*obj)->flags = 0;
930 	(*obj)->hdrlen = 0;
931 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
932 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
933 	(*obj)->pack_offset = offset + tslen;
934 
935 	(*obj)->path_packfile = strdup(path_packfile);
936 	if ((*obj)->path_packfile == NULL) {
937 		err = got_error_from_errno();
938 		goto done;
939 	}
940 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
941 
942 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
943 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
944 
945 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
946 	    path_packfile, offset, tslen, delta_type, delta_size,
947 	    GOT_DELTA_CHAIN_RECURSION_MAX);
948 	if (err)
949 		goto done;
950 
951 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
952 	if (err)
953 		goto done;
954 	(*obj)->type = resolved_type;
955 
956 done:
957 	if (err) {
958 		got_object_close(*obj);
959 		*obj = NULL;
960 	}
961 	return err;
962 }
963 
964 static const struct got_error *
965 open_packed_object(struct got_object **obj, struct got_repository *repo,
966     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
967 {
968 	const struct got_error *err = NULL;
969 	off_t offset;
970 	char *path_packfile;
971 	struct got_pack *pack;
972 	uint8_t type;
973 	uint64_t size;
974 	size_t tslen;
975 
976 	*obj = NULL;
977 
978 	offset = get_object_offset(packidx, idx);
979 	if (offset == (uint64_t)-1)
980 		return got_error(GOT_ERR_BAD_PACKIDX);
981 
982 	err = get_packfile_path(&path_packfile, repo, packidx);
983 	if (err)
984 		return err;
985 
986 	pack = get_cached_pack(path_packfile, repo);
987 	if (pack == NULL) {
988 		err = cache_pack(&pack, path_packfile, packidx, repo);
989 		if (err)
990 			goto done;
991 	}
992 
993 	if (fseeko(pack->packfile, offset, SEEK_SET) != 0) {
994 		err = got_error_from_errno();
995 		goto done;
996 	}
997 
998 	err = parse_object_type_and_size(&type, &size, &tslen, pack->packfile);
999 	if (err)
1000 		goto done;
1001 
1002 	switch (type) {
1003 	case GOT_OBJ_TYPE_COMMIT:
1004 	case GOT_OBJ_TYPE_TREE:
1005 	case GOT_OBJ_TYPE_BLOB:
1006 	case GOT_OBJ_TYPE_TAG:
1007 		err = open_plain_object(obj, path_packfile, id, type,
1008 		    offset + tslen, size);
1009 		break;
1010 
1011 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1012 	case GOT_OBJ_TYPE_REF_DELTA:
1013 		err = open_delta_object(obj, repo, packidx, path_packfile,
1014 		    pack->packfile, id, offset, tslen, type, size);
1015 		break;
1016 
1017 	default:
1018 		err = got_error(GOT_ERR_OBJ_TYPE);
1019 		goto done;
1020 	}
1021 done:
1022 	free(path_packfile);
1023 	return err;
1024 }
1025 
1026 const struct got_error *
1027 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
1028     struct got_repository *repo)
1029 {
1030 	const struct got_error *err = NULL;
1031 	struct got_packidx_v2_hdr *packidx = NULL;
1032 	int idx;
1033 
1034 	err = search_packidx(&packidx, &idx, repo, id);
1035 	if (err)
1036 		return err;
1037 
1038 	err = open_packed_object(obj, repo, packidx, idx, id);
1039 	if (err)
1040 		return err;
1041 
1042 	err = cache_pack(NULL, (*obj)->path_packfile, packidx, repo);
1043 	return err;
1044 }
1045 
1046 static const struct got_error *
1047 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
1048 {
1049 	struct got_delta *delta;
1050 	uint64_t base_size = 0, result_size = 0;
1051 
1052 	*max_size = 0;
1053 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1054 		/* Plain object types are the delta base. */
1055 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1056 		    delta->type != GOT_OBJ_TYPE_TREE &&
1057 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1058 		    delta->type != GOT_OBJ_TYPE_TAG) {
1059 			const struct got_error *err;
1060 			err = got_delta_get_sizes(&base_size, &result_size,
1061 			    delta->delta_buf, delta->delta_len);
1062 			if (err)
1063 				return err;
1064 		} else
1065 			base_size = delta->size;
1066 		if (base_size > *max_size)
1067 			*max_size = base_size;
1068 		if (result_size > *max_size)
1069 			*max_size = result_size;
1070 	}
1071 
1072 	return NULL;
1073 }
1074 
1075 static const struct got_error *
1076 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1077     FILE *outfile, struct got_repository *repo)
1078 {
1079 	const struct got_error *err = NULL;
1080 	struct got_delta *delta;
1081 	FILE *base_file = NULL, *accum_file = NULL;
1082 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1083 	size_t accum_size = 0;
1084 	uint64_t max_size;
1085 	int n = 0;
1086 
1087 	*result_size = 0;
1088 
1089 	if (SIMPLEQ_EMPTY(&deltas->entries))
1090 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1091 
1092 	/* We process small enough files entirely in memory for speed. */
1093 	err = get_delta_chain_max_size(&max_size, deltas);
1094 	if (err)
1095 		return err;
1096 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1097 		accum_buf = malloc(max_size);
1098 		if (accum_buf == NULL)
1099 			return got_error_from_errno();
1100 	} else {
1101 		base_file = got_opentemp();
1102 		if (base_file == NULL)
1103 			return got_error_from_errno();
1104 
1105 		accum_file = got_opentemp();
1106 		if (accum_file == NULL) {
1107 			err = got_error_from_errno();
1108 			fclose(base_file);
1109 			return err;
1110 		}
1111 	}
1112 
1113 	/* Deltas are ordered in ascending order. */
1114 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1115 		if (n == 0) {
1116 			struct got_pack *pack;
1117 			size_t base_len;
1118 
1119 			/* Plain object types are the delta base. */
1120 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1121 			    delta->type != GOT_OBJ_TYPE_TREE &&
1122 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1123 			    delta->type != GOT_OBJ_TYPE_TAG) {
1124 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1125 				goto done;
1126 			}
1127 
1128 			pack = get_cached_pack(delta->path_packfile, repo);
1129 			if (pack == NULL) {
1130 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1131 				goto done;
1132 			}
1133 
1134 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1135 			    SEEK_SET) != 0) {
1136 				err = got_error_from_errno();
1137 				goto done;
1138 			}
1139 			if (base_file)
1140 				err = got_inflate_to_file(&base_len,
1141 				    pack->packfile, base_file);
1142 			else {
1143 				err = got_inflate_to_mem(&base_buf, &base_len,
1144 				    pack->packfile);
1145 				if (base_len < max_size) {
1146 					uint8_t *p;
1147 					p = reallocarray(base_buf, 1, max_size);
1148 					if (p == NULL) {
1149 						err = got_error_from_errno();
1150 						goto done;
1151 					}
1152 					base_buf = p;
1153 				}
1154 			}
1155 			if (err)
1156 				goto done;
1157 			n++;
1158 			if (base_file)
1159 				rewind(base_file);
1160 			continue;
1161 		}
1162 
1163 		if (base_buf) {
1164 			err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1165 			    delta->delta_len, accum_buf, &accum_size);
1166 			n++;
1167 		} else {
1168 			err = got_delta_apply(base_file, delta->delta_buf,
1169 			    delta->delta_len,
1170 			    /* Final delta application writes to output file. */
1171 			    ++n < deltas->nentries ? accum_file : outfile,
1172 			    &accum_size);
1173 		}
1174 		if (err)
1175 			goto done;
1176 
1177 		if (n < deltas->nentries) {
1178 			/* Accumulated delta becomes the new base. */
1179 			if (base_buf) {
1180 				uint8_t *tmp = accum_buf;
1181 				accum_buf = base_buf;
1182 				base_buf = tmp;
1183 			} else {
1184 				FILE *tmp = accum_file;
1185 				accum_file = base_file;
1186 				base_file = tmp;
1187 				rewind(base_file);
1188 				rewind(accum_file);
1189 			}
1190 		}
1191 	}
1192 
1193 done:
1194 	free(base_buf);
1195 	if (accum_buf) {
1196 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1197 		free(accum_buf);
1198 		if (len != accum_size)
1199 			return got_ferror(outfile, GOT_ERR_IO);
1200 	}
1201 	if (base_file)
1202 		fclose(base_file);
1203 	if (accum_file)
1204 		fclose(accum_file);
1205 	rewind(outfile);
1206 	if (err == NULL)
1207 		*result_size = accum_size;
1208 	return err;
1209 }
1210 
1211 static const struct got_error *
1212 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1213     struct got_delta_chain *deltas, struct got_repository *repo)
1214 {
1215 	const struct got_error *err = NULL;
1216 	struct got_delta *delta;
1217 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1218 	size_t accum_size;
1219 	uint64_t max_size;
1220 	int n = 0;
1221 
1222 	*outbuf = NULL;
1223 	*outlen = 0;
1224 
1225 	if (SIMPLEQ_EMPTY(&deltas->entries))
1226 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1227 
1228 	err = get_delta_chain_max_size(&max_size, deltas);
1229 	if (err)
1230 		return err;
1231 	accum_buf = malloc(max_size);
1232 	if (accum_buf == NULL)
1233 		return got_error_from_errno();
1234 
1235 	/* Deltas are ordered in ascending order. */
1236 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1237 		if (n == 0) {
1238 			struct got_pack *pack;
1239 			size_t base_len;
1240 
1241 			/* Plain object types are the delta base. */
1242 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1243 			    delta->type != GOT_OBJ_TYPE_TREE &&
1244 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1245 			    delta->type != GOT_OBJ_TYPE_TAG) {
1246 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1247 				goto done;
1248 			}
1249 
1250 			pack = get_cached_pack(delta->path_packfile, repo);
1251 			if (pack == NULL) {
1252 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1253 				goto done;
1254 			}
1255 
1256 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1257 			    SEEK_SET) != 0) {
1258 				err = got_error_from_errno();
1259 				goto done;
1260 			}
1261 			err = got_inflate_to_mem(&base_buf, &base_len,
1262 			    pack->packfile);
1263 			if (base_len < max_size) {
1264 				uint8_t *p;
1265 				p = reallocarray(base_buf, 1, max_size);
1266 				if (p == NULL) {
1267 					err = got_error_from_errno();
1268 					goto done;
1269 				}
1270 				base_buf = p;
1271 			}
1272 			if (err)
1273 				goto done;
1274 			n++;
1275 			continue;
1276 		}
1277 
1278 		err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1279 		    delta->delta_len, accum_buf, &accum_size);
1280 		n++;
1281 		if (err)
1282 			goto done;
1283 
1284 		if (n < deltas->nentries) {
1285 			/* Accumulated delta becomes the new base. */
1286 			uint8_t *tmp = accum_buf;
1287 			accum_buf = base_buf;
1288 			base_buf = tmp;
1289 		}
1290 	}
1291 
1292 done:
1293 	free(base_buf);
1294 	if (err) {
1295 		free(accum_buf);
1296 		*outbuf = NULL;
1297 		*outlen = 0;
1298 	} else {
1299 		*outbuf = accum_buf;
1300 		*outlen = accum_size;
1301 	}
1302 	return err;
1303 }
1304 
1305 const struct got_error *
1306 got_packfile_extract_object(FILE **f, struct got_object *obj,
1307     struct got_repository *repo)
1308 {
1309 	const struct got_error *err = NULL;
1310 
1311 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1312 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1313 
1314 	*f = got_opentemp();
1315 	if (*f == NULL) {
1316 		err = got_error(GOT_ERR_FILE_OPEN);
1317 		goto done;
1318 	}
1319 
1320 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1321 		struct got_pack *pack;
1322 
1323 		pack = get_cached_pack(obj->path_packfile, repo);
1324 		if (pack == NULL) {
1325 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1326 			if (err)
1327 				goto done;
1328 		}
1329 
1330 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1331 			err = got_error_from_errno();
1332 			goto done;
1333 		}
1334 
1335 		err = got_inflate_to_file(&obj->size, pack->packfile, *f);
1336 	} else
1337 		err = dump_delta_chain_to_file(&obj->size, &obj->deltas, *f,
1338 		    repo);
1339 done:
1340 	if (err && *f) {
1341 		fclose(*f);
1342 		*f = NULL;
1343 	}
1344 	return err;
1345 }
1346 
1347 const struct got_error *
1348 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1349     struct got_object *obj, struct got_repository *repo)
1350 {
1351 	const struct got_error *err = NULL;
1352 
1353 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1354 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1355 
1356 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1357 		struct got_pack *pack;
1358 
1359 		pack = get_cached_pack(obj->path_packfile, repo);
1360 		if (pack == NULL) {
1361 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1362 			if (err)
1363 				goto done;
1364 		}
1365 
1366 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1367 			err = got_error_from_errno();
1368 			goto done;
1369 		}
1370 
1371 		err = got_inflate_to_mem(buf, len, pack->packfile);
1372 	} else
1373 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, repo);
1374 done:
1375 	return err;
1376 }