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Date:: Sun Apr 22 12:51:49 2018 UTC
Message:: read object headers with privsep
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 #ifndef MIN
60 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
61 #endif
62 
63 static const struct got_error *
64 verify_fanout_table(uint32_t *fanout_table)
65 {
66 	int i;
67 
68 	for (i = 0; i < 0xff - 1; i++) {
69 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
70 			return got_error(GOT_ERR_BAD_PACKIDX);
71 	}
72 
73 	return NULL;
74 }
75 
76 static const struct got_error *
77 get_packfile_size(size_t *size, const char *path)
78 {
79 	struct stat sb;
80 	char *dot;
81 
82 	*size = 0;
83 
84 	dot = strrchr(path, '.');
85 	if (dot == NULL)
86 		return got_error(GOT_ERR_BAD_PATH);
87 
88 	/* Path must point to a pack index or to a pack file. */
89 	if (strcmp(dot, ".idx") == 0) {
90 		const struct got_error *err = NULL;
91 		char *path_pack;
92 		char base_path[PATH_MAX];
93 
94 		/* Convert pack index path to pack file path. */
95 		if (strlcpy(base_path, path, PATH_MAX) > PATH_MAX)
96 			return got_error(GOT_ERR_NO_SPACE);
97 		dot = strrchr(base_path, '.');
98 		if (dot == NULL)
99 			return got_error(GOT_ERR_BAD_PATH);
100 		*dot = '\0';
101 		if (asprintf(&path_pack, "%s.pack", base_path) == -1)
102 			return got_error_from_errno();
103 
104 		if (stat(path_pack, &sb) != 0)
105 			err = got_error_from_errno();
106 		free(path_pack);
107 		if (err)
108 			return err;
109 	} else if (strcmp(dot, ".pack") == 0) {
110 		if (stat(path, &sb) != 0)
111 			return got_error_from_errno();
112 	} else
113 		return got_error(GOT_ERR_BAD_PATH);
114 
115 	*size = sb.st_size;
116 	return 0;
117 }
118 
119 const struct got_error *
120 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
121 {
122 	struct got_packidx_v2_hdr *p;
123 	FILE *f;
124 	const struct got_error *err = NULL;
125 	size_t n, nobj, packfile_size;
126 	SHA1_CTX ctx;
127 	uint8_t sha1[SHA1_DIGEST_LENGTH];
128 
129 	SHA1Init(&ctx);
130 
131 	f = fopen(path, "rb");
132 	if (f == NULL)
133 		return got_error_from_errno();
134 
135 	err = get_packfile_size(&packfile_size, path);
136 	if (err)
137 		return err;
138 
139 	p = calloc(1, sizeof(*p));
140 	if (p == NULL) {
141 		err = got_error_from_errno();
142 		goto done;
143 	}
144 
145 	n = fread(&p->magic, sizeof(p->magic), 1, f);
146 	if (n != 1) {
147 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
148 		goto done;
149 	}
150 
151 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
152 		err = got_error(GOT_ERR_BAD_PACKIDX);
153 		goto done;
154 	}
155 
156 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
157 
158 	n = fread(&p->version, sizeof(p->version), 1, f);
159 	if (n != 1) {
160 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
161 		goto done;
162 	}
163 
164 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
165 		err = got_error(GOT_ERR_BAD_PACKIDX);
166 		goto done;
167 	}
168 
169 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
170 
171 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
172 	if (n != 1) {
173 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
174 		goto done;
175 	}
176 
177 	err = verify_fanout_table(p->fanout_table);
178 	if (err)
179 		goto done;
180 
181 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
182 
183 	nobj = betoh32(p->fanout_table[0xff]);
184 
185 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
186 	if (p->sorted_ids == NULL) {
187 		err = got_error_from_errno();
188 		goto done;
189 	}
190 
191 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
192 	if (n != nobj) {
193 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
194 		goto done;
195 	}
196 
197 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
198 	    nobj * sizeof(*p->sorted_ids));
199 
200 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
201 	if (p->crc32 == NULL) {
202 		err = got_error_from_errno();
203 		goto done;
204 	}
205 
206 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
207 	if (n != nobj) {
208 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
209 		goto done;
210 	}
211 
212 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
213 
214 	p->offsets = calloc(nobj, sizeof(*p->offsets));
215 	if (p->offsets == NULL) {
216 		err = got_error_from_errno();
217 		goto done;
218 	}
219 
220 	n = fread(p->offsets, sizeof(*p->offsets), nobj, f);
221 	if (n != nobj) {
222 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
223 		goto done;
224 	}
225 
226 	SHA1Update(&ctx, (uint8_t *)p->offsets, nobj * sizeof(*p->offsets));
227 
228 	/* Large file offsets are contained only in files > 2GB. */
229 	if (packfile_size <= 0x80000000)
230 		goto checksum;
231 
232 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
233 	if (p->large_offsets == NULL) {
234 		err = got_error_from_errno();
235 		goto done;
236 	}
237 
238 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
239 	if (n != nobj) {
240 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
241 		goto done;
242 	}
243 
244 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
245 	    nobj * sizeof(*p->large_offsets));
246 
247 checksum:
248 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
249 	if (n != 1) {
250 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
251 		goto done;
252 	}
253 
254 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
255 	SHA1Final(sha1, &ctx);
256 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
257 		err = got_error(GOT_ERR_PACKIDX_CSUM);
258 done:
259 	fclose(f);
260 	if (err)
261 		got_packidx_close(p);
262 	else
263 		*packidx = p;
264 	return err;
265 }
266 
267 void
268 got_packidx_close(struct got_packidx_v2_hdr *packidx)
269 {
270 	free(packidx->sorted_ids);
271 	free(packidx->offsets);
272 	free(packidx->crc32);
273 	free(packidx->large_offsets);
274 	free(packidx);
275 }
276 
277 static int
278 is_packidx_filename(const char *name, size_t len)
279 {
280 	if (len != GOT_PACKIDX_NAMELEN)
281 		return 0;
282 
283 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
284 		return 0;
285 
286 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
287 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
288 		return 0;
289 
290 	return 1;
291 }
292 
293 static off_t
294 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
295 {
296 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
297 	uint32_t offset = betoh32(packidx->offsets[idx]);
298 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
299 		uint64_t loffset;
300 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
301 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
302 			return -1;
303 		loffset = betoh64(packidx->large_offsets[idx]);
304 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
305 	}
306 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
307 }
308 
309 static const struct got_error *
310 get_packfile_path(char **path_packfile, struct got_repository *repo,
311     struct got_packidx_v2_hdr *packidx);
312 
313 static int
314 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id, struct got_repository *repo)
315 {
316 	u_int8_t id0 = id->sha1[0];
317 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
318 	int i = 0;
319 
320 	if (id0 > 0)
321 		i = betoh32(packidx->fanout_table[id0 - 1]);
322 
323 	while (i < totobj) {
324 		struct got_object_id *oid = &packidx->sorted_ids[i];
325 		int cmp = got_object_id_cmp(id, oid);
326 
327 		if (cmp == 0)
328 			return i;
329 		i++;
330 	}
331 
332 	return -1;
333 }
334 
335 static struct got_packidx_v2_hdr *
336 dup_packidx(struct got_packidx_v2_hdr *packidx)
337 {
338 	struct got_packidx_v2_hdr *p;
339 	size_t nobj;
340 
341 	p = calloc(1, sizeof(*p));
342 	if (p == NULL)
343 		return NULL;
344 
345 	memcpy(p, packidx, sizeof(*p));
346 	p->sorted_ids = NULL;
347 	p->crc32 = NULL;
348 	p->offsets = NULL;
349 	p->large_offsets = NULL;
350 
351 	nobj = betoh32(p->fanout_table[0xff]);
352 
353 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
354 	if (p->sorted_ids == NULL)
355 		goto err;
356 	memcpy(p->sorted_ids, packidx->sorted_ids,
357 	    nobj * sizeof(*p->sorted_ids));
358 
359 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
360 	if (p->crc32 == NULL)
361 		goto err;
362 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
363 
364 	p->offsets = calloc(nobj, sizeof(*p->offsets));
365 	if (p->offsets == NULL)
366 		goto err;
367 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
368 
369 	if (p->large_offsets) {
370 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
371 		if (p->large_offsets == NULL)
372 			goto err;
373 		memcpy(p->large_offsets, packidx->large_offsets,
374 		    nobj * sizeof(*p->large_offsets));
375 	}
376 
377 	return p;
378 
379 err:
380 	free(p->large_offsets);
381 	free(p->offsets);
382 	free(p->crc32);
383 	free(p->sorted_ids);
384 	free(p);
385 	return NULL;
386 }
387 
388 static void
389 cache_packidx(struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
390 {
391 	int i;
392 
393 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
394 		if (repo->packidx_cache[i] == NULL)
395 			break;
396 	}
397 
398 	if (i == nitems(repo->packidx_cache)) {
399 		got_packidx_close(repo->packidx_cache[i - 1]);
400 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
401 		    sizeof(repo->packidx_cache) -
402 		    sizeof(repo->packidx_cache[0]));
403 		i = 0;
404 	}
405 
406 	repo->packidx_cache[i] = dup_packidx(packidx);
407 }
408 
409 static const struct got_error *
410 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
411     struct got_repository *repo, struct got_object_id *id)
412 {
413 	const struct got_error *err;
414 	char *path_packdir;
415 	DIR *packdir;
416 	struct dirent *dent;
417 	char *path_packidx;
418 	int i;
419 
420 	/* Search pack index cache. */
421 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
422 		if (repo->packidx_cache[i] == NULL)
423 			break;
424 		*idx = get_object_idx(repo->packidx_cache[i], id, repo);
425 		if (*idx != -1) {
426 			*packidx = repo->packidx_cache[i];
427 			return NULL;
428 		}
429 	}
430 	/* No luck. Search the filesystem. */
431 
432 	path_packdir = got_repo_get_path_objects_pack(repo);
433 	if (path_packdir == NULL)
434 		return got_error_from_errno();
435 
436 	packdir = opendir(path_packdir);
437 	if (packdir == NULL) {
438 		err = got_error_from_errno();
439 		goto done;
440 	}
441 
442 	while ((dent = readdir(packdir)) != NULL) {
443 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
444 			continue;
445 
446 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
447 		    dent->d_name) == -1) {
448 			err = got_error_from_errno();
449 			goto done;
450 		}
451 
452 		err = got_packidx_open(packidx, path_packidx);
453 		free(path_packidx);
454 		if (err)
455 			goto done;
456 
457 		*idx = get_object_idx(*packidx, id, repo);
458 		if (*idx != -1) {
459 			err = NULL; /* found the object */
460 			cache_packidx(*packidx, repo);
461 			goto done;
462 		}
463 
464 		got_packidx_close(*packidx);
465 		*packidx = NULL;
466 	}
467 
468 	err = got_error(GOT_ERR_NO_OBJ);
469 done:
470 	free(path_packdir);
471 	if (packdir && closedir(packdir) != 0 && err == 0)
472 		err = got_error_from_errno();
473 	return err;
474 }
475 
476 static const struct got_error *
477 get_packfile_path(char **path_packfile, struct got_repository *repo,
478     struct got_packidx_v2_hdr *packidx)
479 {
480 	char *path_packdir;
481 	char hex[SHA1_DIGEST_STRING_LENGTH];
482 	char *sha1str;
483 
484 	path_packdir = got_repo_get_path_objects_pack(repo);
485 	if (path_packdir == NULL)
486 		return got_error_from_errno();
487 
488 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
489 	    hex, sizeof(hex));
490 	if (sha1str == NULL)
491 		return got_error(GOT_ERR_PACKIDX_CSUM);
492 
493 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
494 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
495 		*path_packfile = NULL;
496 		return got_error_from_errno();
497 	}
498 
499 	return NULL;
500 }
501 
502 const struct got_error *
503 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
504 {
505 	const struct got_error *err = NULL;
506 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
507 	struct got_packfile_hdr hdr;
508 	size_t n;
509 
510 	n = fread(&hdr, sizeof(hdr), 1, f);
511 	if (n != 1)
512 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
513 
514 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
515 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
516 	    betoh32(hdr.nobjects) != totobj)
517 		err = got_error(GOT_ERR_BAD_PACKFILE);
518 
519 	return err;
520 }
521 
522 static const struct got_error *
523 open_packfile(FILE **packfile, const char *path_packfile,
524     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
525 {
526 	const struct got_error *err = NULL;
527 
528 	*packfile = NULL;
529 
530 	*packfile = fopen(path_packfile, "rb");
531 	if (*packfile == NULL) {
532 		err = got_error_from_errno();
533 		return err;
534 	}
535 
536 	if (packidx) {
537 		err = read_packfile_hdr(*packfile, packidx);
538 		if (err) {
539 			fclose(*packfile);
540 			*packfile = NULL;
541 		}
542 	}
543 	return err;
544 }
545 
546 void
547 got_pack_close(struct got_pack *pack)
548 {
549 	fclose(pack->packfile);
550 	pack->packfile = NULL;
551 	free(pack->path_packfile);
552 	pack->path_packfile = NULL;
553 	pack->filesize = 0;
554 }
555 
556 static const struct got_error *
557 cache_pack(struct got_pack **packp, const char *path_packfile,
558     struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
559 {
560 	const struct got_error *err = NULL;
561 	struct got_pack *pack = NULL;
562 	int i;
563 
564 	if (packp)
565 		*packp = NULL;
566 
567 	for (i = 0; i < nitems(repo->packs); i++) {
568 		pack = &repo->packs[i];
569 		if (pack->path_packfile == NULL)
570 			break;
571 		if (strcmp(pack->path_packfile, path_packfile) == 0)
572 			return NULL;
573 	}
574 
575 	if (i == nitems(repo->packs) - 1) {
576 		got_pack_close(&repo->packs[i - 1]);
577 		memmove(&repo->packs[1], &repo->packs[0],
578 		    sizeof(repo->packs) - sizeof(repo->packs[0]));
579 		i = 0;
580 	}
581 
582 	pack = &repo->packs[i];
583 
584 	pack->path_packfile = strdup(path_packfile);
585 	if (pack->path_packfile == NULL) {
586 		err = got_error_from_errno();
587 		goto done;
588 	}
589 
590 	err = open_packfile(&pack->packfile, path_packfile, repo, packidx);
591 	if (err)
592 		goto done;
593 
594 	err = get_packfile_size(&pack->filesize, path_packfile);
595 done:
596 	if (err) {
597 		if (pack)
598 			free(pack->path_packfile);
599 		free(pack);
600 	} else if (packp)
601 		*packp = pack;
602 	return err;
603 }
604 
605 struct got_pack *
606 get_cached_pack(const char *path_packfile, struct got_repository *repo)
607 {
608 	struct got_pack *pack = NULL;
609 	int i;
610 
611 	for (i = 0; i < nitems(repo->packs); i++) {
612 		pack = &repo->packs[i];
613 		if (pack->path_packfile == NULL)
614 			break;
615 		if (strcmp(pack->path_packfile, path_packfile) == 0)
616 			return pack;
617 	}
618 
619 	return NULL;
620 }
621 
622 static const struct got_error *
623 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
624     FILE *packfile)
625 {
626 	uint8_t t = 0;
627 	uint64_t s = 0;
628 	uint8_t sizeN;
629 	size_t n;
630 	int i = 0;
631 
632 	do {
633 		/* We do not support size values which don't fit in 64 bit. */
634 		if (i > 9)
635 			return got_error(GOT_ERR_NO_SPACE);
636 
637 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
638 		if (n != 1)
639 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
640 
641 		if (i == 0) {
642 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
643 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
644 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
645 		} else {
646 			size_t shift = 4 + 7 * (i - 1);
647 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
648 		}
649 		i++;
650 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
651 
652 	*type = t;
653 	*size = s;
654 	*len = i * sizeof(sizeN);
655 	return NULL;
656 }
657 
658 static const struct got_error *
659 open_plain_object(struct got_object **obj, const char *path_packfile,
660     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
661 {
662 	*obj = calloc(1, sizeof(**obj));
663 	if (*obj == NULL)
664 		return got_error_from_errno();
665 
666 	(*obj)->path_packfile = strdup(path_packfile);
667 	if ((*obj)->path_packfile == NULL) {
668 		const struct got_error *err = got_error_from_errno();
669 		free(*obj);
670 		*obj = NULL;
671 		return err;
672 	}
673 
674 	(*obj)->type = type;
675 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
676 	(*obj)->hdrlen = 0;
677 	(*obj)->size = size;
678 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
679 	(*obj)->pack_offset = offset;
680 
681 	return NULL;
682 }
683 
684 static const struct got_error *
685 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
686 {
687 	int64_t o = 0;
688 	uint8_t offN;
689 	size_t n;
690 	int i = 0;
691 
692 	do {
693 		/* We do not support offset values which don't fit in 64 bit. */
694 		if (i > 8)
695 			return got_error(GOT_ERR_NO_SPACE);
696 
697 		n = fread(&offN, sizeof(offN), 1, packfile);
698 		if (n != 1)
699 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
700 
701 		if (i == 0)
702 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
703 		else {
704 			o++;
705 			o <<= 7;
706 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
707 		}
708 		i++;
709 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
710 
711 	*offset = o;
712 	*len = i * sizeof(offN);
713 	return NULL;
714 }
715 
716 static const struct got_error *
717 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
718 {
719 	const struct got_error *err;
720 	int64_t negoffset;
721 	size_t negofflen;
722 
723 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
724 	if (err)
725 		return err;
726 
727 	/* Compute the base object's offset (must be in the same pack file). */
728 	*base_offset = (offset - negoffset);
729 	if (*base_offset <= 0)
730 		return got_error(GOT_ERR_BAD_PACKFILE);
731 
732 	return NULL;
733 }
734 
735 static const struct got_error *
736 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
737     FILE *, const char *, off_t, size_t, int, size_t, unsigned int);
738 
739 static const struct got_error *
740 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
741     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
742     size_t delta_data_offset, uint8_t *delta_buf, size_t delta_len)
743 {
744 	struct got_delta *delta;
745 
746 	delta = got_delta_open(path_packfile, delta_offset, tslen,
747 	    delta_type, delta_size, delta_data_offset, delta_buf,
748 	    delta_len);
749 	if (delta == NULL)
750 		return got_error_from_errno();
751 	/* delta is freed in got_object_close() */
752 	deltas->nentries++;
753 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
754 	return NULL;
755 }
756 
757 static const struct got_error *
758 resolve_offset_delta(struct got_delta_chain *deltas,
759     struct got_repository *repo, FILE *packfile, const char *path_packfile,
760     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size,
761     unsigned int recursion)
762 
763 {
764 	const struct got_error *err;
765 	off_t base_offset;
766 	uint8_t base_type;
767 	uint64_t base_size;
768 	size_t base_tslen;
769 	off_t delta_data_offset;
770 	uint8_t *delta_buf;
771 	size_t delta_len;
772 
773 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
774 	if (err)
775 		return err;
776 
777 	delta_data_offset = ftello(packfile);
778 	if (delta_data_offset == -1)
779 		return got_error_from_errno();
780 
781 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
782 	if (err)
783 		return err;
784 
785 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
786 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
787 	if (err)
788 		return err;
789 
790 	/* An offset delta must be in the same packfile. */
791 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
792 		return got_error_from_errno();
793 
794 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
795 	    packfile);
796 	if (err)
797 		return err;
798 
799 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
800 	    base_offset, base_tslen, base_type, base_size, recursion - 1);
801 }
802 
803 static const struct got_error *
804 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
805     FILE *packfile, const char *path_packfile, off_t delta_offset,
806     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
807 {
808 	const struct got_error *err;
809 	struct got_object_id id;
810 	struct got_packidx_v2_hdr *packidx;
811 	int idx;
812 	off_t base_offset;
813 	uint8_t base_type;
814 	uint64_t base_size;
815 	size_t base_tslen;
816 	size_t n;
817 	char *path_base_packfile;
818 	struct got_pack *base_pack;
819 	off_t delta_data_offset;
820 	uint8_t *delta_buf;
821 	size_t delta_len;
822 
823 	n = fread(&id, sizeof(id), 1, packfile);
824 	if (n != 1)
825 		return got_ferror(packfile, GOT_ERR_IO);
826 
827 	delta_data_offset = ftello(packfile);
828 	if (delta_data_offset == -1)
829 		return got_error_from_errno();
830 
831 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
832 	if (err)
833 		return err;
834 
835 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
836 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
837 	if (err)
838 		return err;
839 
840 	err = search_packidx(&packidx, &idx, repo, &id);
841 	if (err)
842 		return err;
843 
844 	base_offset = get_object_offset(packidx, idx);
845 	if (base_offset == (uint64_t)-1) {
846 		return got_error(GOT_ERR_BAD_PACKIDX);
847 	}
848 
849 	err = get_packfile_path(&path_base_packfile, repo, packidx);
850 	if (err)
851 		return err;
852 
853 	base_pack = get_cached_pack(path_base_packfile, repo);
854 	if (base_pack == NULL) {
855 		err = cache_pack(&base_pack, path_base_packfile, NULL, repo);
856 		if (err)
857 			goto done;
858 	}
859 
860 	if (fseeko(base_pack->packfile, base_offset, SEEK_SET) != 0) {
861 		err = got_error_from_errno();
862 		goto done;
863 	}
864 
865 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
866 	    base_pack->packfile);
867 	if (err)
868 		goto done;
869 
870 	err = resolve_delta_chain(deltas, repo, base_pack->packfile,
871 	    path_base_packfile, base_offset, base_tslen, base_type,
872 	    base_size, recursion - 1);
873 done:
874 	free(path_base_packfile);
875 	return err;
876 }
877 
878 static const struct got_error *
879 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
880     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
881     int delta_type, size_t delta_size, unsigned int recursion)
882 {
883 	const struct got_error *err = NULL;
884 
885 	if (--recursion == 0)
886 		return got_error(GOT_ERR_RECURSION);
887 
888 	switch (delta_type) {
889 	case GOT_OBJ_TYPE_COMMIT:
890 	case GOT_OBJ_TYPE_TREE:
891 	case GOT_OBJ_TYPE_BLOB:
892 	case GOT_OBJ_TYPE_TAG:
893 		/* Plain types are the final delta base. Recursion ends. */
894 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
895 		    delta_type, delta_size, 0, NULL, 0);
896 		break;
897 	case GOT_OBJ_TYPE_OFFSET_DELTA:
898 		err = resolve_offset_delta(deltas, repo, packfile,
899 		    path_packfile, delta_offset, tslen, delta_type,
900 		    delta_size, recursion - 1);
901 		break;
902 	case GOT_OBJ_TYPE_REF_DELTA:
903 		err = resolve_ref_delta(deltas, repo, packfile,
904 		    path_packfile, delta_offset, tslen, delta_type,
905 		    delta_size, recursion - 1);
906 		break;
907 	default:
908 		return got_error(GOT_ERR_OBJ_TYPE);
909 	}
910 
911 	return err;
912 }
913 
914 static const struct got_error *
915 open_delta_object(struct got_object **obj, struct got_repository *repo,
916     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
917     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
918     int delta_type, size_t delta_size)
919 {
920 	const struct got_error *err = NULL;
921 	int resolved_type;
922 
923 	*obj = calloc(1, sizeof(**obj));
924 	if (*obj == NULL)
925 		return got_error_from_errno();
926 
927 	(*obj)->flags = 0;
928 	(*obj)->hdrlen = 0;
929 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
930 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
931 	(*obj)->pack_offset = offset + tslen;
932 
933 	(*obj)->path_packfile = strdup(path_packfile);
934 	if ((*obj)->path_packfile == NULL) {
935 		err = got_error_from_errno();
936 		goto done;
937 	}
938 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
939 
940 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
941 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
942 
943 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
944 	    path_packfile, offset, tslen, delta_type, delta_size,
945 	    GOT_DELTA_CHAIN_RECURSION_MAX);
946 	if (err)
947 		goto done;
948 
949 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
950 	if (err)
951 		goto done;
952 	(*obj)->type = resolved_type;
953 
954 done:
955 	if (err) {
956 		got_object_close(*obj);
957 		*obj = NULL;
958 	}
959 	return err;
960 }
961 
962 static const struct got_error *
963 open_packed_object(struct got_object **obj, struct got_repository *repo,
964     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
965 {
966 	const struct got_error *err = NULL;
967 	off_t offset;
968 	char *path_packfile;
969 	struct got_pack *pack;
970 	uint8_t type;
971 	uint64_t size;
972 	size_t tslen;
973 
974 	*obj = NULL;
975 
976 	offset = get_object_offset(packidx, idx);
977 	if (offset == (uint64_t)-1)
978 		return got_error(GOT_ERR_BAD_PACKIDX);
979 
980 	err = get_packfile_path(&path_packfile, repo, packidx);
981 	if (err)
982 		return err;
983 
984 	pack = get_cached_pack(path_packfile, repo);
985 	if (pack == NULL) {
986 		err = cache_pack(&pack, path_packfile, packidx, repo);
987 		if (err)
988 			goto done;
989 	}
990 
991 	if (fseeko(pack->packfile, offset, SEEK_SET) != 0) {
992 		err = got_error_from_errno();
993 		goto done;
994 	}
995 
996 	err = parse_object_type_and_size(&type, &size, &tslen, pack->packfile);
997 	if (err)
998 		goto done;
999 
1000 	switch (type) {
1001 	case GOT_OBJ_TYPE_COMMIT:
1002 	case GOT_OBJ_TYPE_TREE:
1003 	case GOT_OBJ_TYPE_BLOB:
1004 	case GOT_OBJ_TYPE_TAG:
1005 		err = open_plain_object(obj, path_packfile, id, type,
1006 		    offset + tslen, size);
1007 		break;
1008 
1009 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1010 	case GOT_OBJ_TYPE_REF_DELTA:
1011 		err = open_delta_object(obj, repo, packidx, path_packfile,
1012 		    pack->packfile, id, offset, tslen, type, size);
1013 		break;
1014 
1015 	default:
1016 		err = got_error(GOT_ERR_OBJ_TYPE);
1017 		goto done;
1018 	}
1019 done:
1020 	free(path_packfile);
1021 	return err;
1022 }
1023 
1024 const struct got_error *
1025 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
1026     struct got_repository *repo)
1027 {
1028 	const struct got_error *err = NULL;
1029 	struct got_packidx_v2_hdr *packidx = NULL;
1030 	int idx;
1031 
1032 	err = search_packidx(&packidx, &idx, repo, id);
1033 	if (err)
1034 		return err;
1035 
1036 	err = open_packed_object(obj, repo, packidx, idx, id);
1037 	if (err)
1038 		return err;
1039 
1040 	err = cache_pack(NULL, (*obj)->path_packfile, packidx, repo);
1041 	return err;
1042 }
1043 
1044 static const struct got_error *
1045 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
1046 {
1047 	struct got_delta *delta;
1048 	uint64_t base_size = 0, result_size = 0;
1049 
1050 	*max_size = 0;
1051 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1052 		/* Plain object types are the delta base. */
1053 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1054 		    delta->type != GOT_OBJ_TYPE_TREE &&
1055 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1056 		    delta->type != GOT_OBJ_TYPE_TAG) {
1057 			const struct got_error *err;
1058 			err = got_delta_get_sizes(&base_size, &result_size,
1059 			    delta->delta_buf, delta->delta_len);
1060 			if (err)
1061 				return err;
1062 		} else
1063 			base_size = delta->size;
1064 		if (base_size > *max_size)
1065 			*max_size = base_size;
1066 		if (result_size > *max_size)
1067 			*max_size = result_size;
1068 	}
1069 
1070 	return NULL;
1071 }
1072 
1073 static const struct got_error *
1074 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1075     FILE *outfile, struct got_repository *repo)
1076 {
1077 	const struct got_error *err = NULL;
1078 	struct got_delta *delta;
1079 	FILE *base_file = NULL, *accum_file = NULL;
1080 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1081 	size_t accum_size = 0;
1082 	uint64_t max_size;
1083 	int n = 0;
1084 
1085 	*result_size = 0;
1086 
1087 	if (SIMPLEQ_EMPTY(&deltas->entries))
1088 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1089 
1090 	/* We process small enough files entirely in memory for speed. */
1091 	err = get_delta_chain_max_size(&max_size, deltas);
1092 	if (err)
1093 		return err;
1094 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1095 		accum_buf = malloc(max_size);
1096 		if (accum_buf == NULL)
1097 			return got_error_from_errno();
1098 	} else {
1099 		base_file = got_opentemp();
1100 		if (base_file == NULL)
1101 			return got_error_from_errno();
1102 
1103 		accum_file = got_opentemp();
1104 		if (accum_file == NULL) {
1105 			err = got_error_from_errno();
1106 			fclose(base_file);
1107 			return err;
1108 		}
1109 	}
1110 
1111 	/* Deltas are ordered in ascending order. */
1112 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1113 		if (n == 0) {
1114 			struct got_pack *pack;
1115 			size_t base_len;
1116 
1117 			/* Plain object types are the delta base. */
1118 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1119 			    delta->type != GOT_OBJ_TYPE_TREE &&
1120 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1121 			    delta->type != GOT_OBJ_TYPE_TAG) {
1122 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1123 				goto done;
1124 			}
1125 
1126 			pack = get_cached_pack(delta->path_packfile, repo);
1127 			if (pack == NULL) {
1128 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1129 				goto done;
1130 			}
1131 
1132 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1133 			    SEEK_SET) != 0) {
1134 				err = got_error_from_errno();
1135 				goto done;
1136 			}
1137 			if (base_file)
1138 				err = got_inflate_to_file(&base_len,
1139 				    pack->packfile, base_file);
1140 			else {
1141 				err = got_inflate_to_mem(&base_buf, &base_len,
1142 				    pack->packfile);
1143 				if (base_len < max_size) {
1144 					uint8_t *p;
1145 					p = reallocarray(base_buf, 1, max_size);
1146 					if (p == NULL) {
1147 						err = got_error_from_errno();
1148 						goto done;
1149 					}
1150 					base_buf = p;
1151 				}
1152 			}
1153 			if (err)
1154 				goto done;
1155 			n++;
1156 			if (base_file)
1157 				rewind(base_file);
1158 			continue;
1159 		}
1160 
1161 		if (base_buf) {
1162 			err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1163 			    delta->delta_len, accum_buf, &accum_size);
1164 			n++;
1165 		} else {
1166 			err = got_delta_apply(base_file, delta->delta_buf,
1167 			    delta->delta_len,
1168 			    /* Final delta application writes to output file. */
1169 			    ++n < deltas->nentries ? accum_file : outfile,
1170 			    &accum_size);
1171 		}
1172 		if (err)
1173 			goto done;
1174 
1175 		if (n < deltas->nentries) {
1176 			/* Accumulated delta becomes the new base. */
1177 			if (base_buf) {
1178 				uint8_t *tmp = accum_buf;
1179 				accum_buf = base_buf;
1180 				base_buf = tmp;
1181 			} else {
1182 				FILE *tmp = accum_file;
1183 				accum_file = base_file;
1184 				base_file = tmp;
1185 				rewind(base_file);
1186 				rewind(accum_file);
1187 			}
1188 		}
1189 	}
1190 
1191 done:
1192 	free(base_buf);
1193 	if (accum_buf) {
1194 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1195 		free(accum_buf);
1196 		if (len != accum_size)
1197 			return got_ferror(outfile, GOT_ERR_IO);
1198 	}
1199 	if (base_file)
1200 		fclose(base_file);
1201 	if (accum_file)
1202 		fclose(accum_file);
1203 	rewind(outfile);
1204 	if (err == NULL)
1205 		*result_size = accum_size;
1206 	return err;
1207 }
1208 
1209 static const struct got_error *
1210 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1211     struct got_delta_chain *deltas, struct got_repository *repo)
1212 {
1213 	const struct got_error *err = NULL;
1214 	struct got_delta *delta;
1215 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1216 	size_t accum_size;
1217 	uint64_t max_size;
1218 	int n = 0;
1219 
1220 	*outbuf = NULL;
1221 	*outlen = 0;
1222 
1223 	if (SIMPLEQ_EMPTY(&deltas->entries))
1224 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1225 
1226 	err = get_delta_chain_max_size(&max_size, deltas);
1227 	if (err)
1228 		return err;
1229 	accum_buf = malloc(max_size);
1230 	if (accum_buf == NULL)
1231 		return got_error_from_errno();
1232 
1233 	/* Deltas are ordered in ascending order. */
1234 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1235 		if (n == 0) {
1236 			struct got_pack *pack;
1237 			size_t base_len;
1238 
1239 			/* Plain object types are the delta base. */
1240 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1241 			    delta->type != GOT_OBJ_TYPE_TREE &&
1242 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1243 			    delta->type != GOT_OBJ_TYPE_TAG) {
1244 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1245 				goto done;
1246 			}
1247 
1248 			pack = get_cached_pack(delta->path_packfile, repo);
1249 			if (pack == NULL) {
1250 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1251 				goto done;
1252 			}
1253 
1254 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1255 			    SEEK_SET) != 0) {
1256 				err = got_error_from_errno();
1257 				goto done;
1258 			}
1259 			err = got_inflate_to_mem(&base_buf, &base_len,
1260 			    pack->packfile);
1261 			if (base_len < max_size) {
1262 				uint8_t *p;
1263 				p = reallocarray(base_buf, 1, max_size);
1264 				if (p == NULL) {
1265 					err = got_error_from_errno();
1266 					goto done;
1267 				}
1268 				base_buf = p;
1269 			}
1270 			if (err)
1271 				goto done;
1272 			n++;
1273 			continue;
1274 		}
1275 
1276 		err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1277 		    delta->delta_len, accum_buf, &accum_size);
1278 		n++;
1279 		if (err)
1280 			goto done;
1281 
1282 		if (n < deltas->nentries) {
1283 			/* Accumulated delta becomes the new base. */
1284 			uint8_t *tmp = accum_buf;
1285 			accum_buf = base_buf;
1286 			base_buf = tmp;
1287 		}
1288 	}
1289 
1290 done:
1291 	free(base_buf);
1292 	if (err) {
1293 		free(accum_buf);
1294 		*outbuf = NULL;
1295 		*outlen = 0;
1296 	} else {
1297 		*outbuf = accum_buf;
1298 		*outlen = accum_size;
1299 	}
1300 	return err;
1301 }
1302 
1303 const struct got_error *
1304 got_packfile_extract_object(FILE **f, struct got_object *obj,
1305     struct got_repository *repo)
1306 {
1307 	const struct got_error *err = NULL;
1308 
1309 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1310 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1311 
1312 	*f = got_opentemp();
1313 	if (*f == NULL) {
1314 		err = got_error(GOT_ERR_FILE_OPEN);
1315 		goto done;
1316 	}
1317 
1318 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1319 		struct got_pack *pack;
1320 
1321 		pack = get_cached_pack(obj->path_packfile, repo);
1322 		if (pack == NULL) {
1323 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1324 			if (err)
1325 				goto done;
1326 		}
1327 
1328 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1329 			err = got_error_from_errno();
1330 			goto done;
1331 		}
1332 
1333 		err = got_inflate_to_file(&obj->size, pack->packfile, *f);
1334 	} else
1335 		err = dump_delta_chain_to_file(&obj->size, &obj->deltas, *f,
1336 		    repo);
1337 done:
1338 	if (err && *f) {
1339 		fclose(*f);
1340 		*f = NULL;
1341 	}
1342 	return err;
1343 }
1344 
1345 const struct got_error *
1346 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1347     struct got_object *obj, struct got_repository *repo)
1348 {
1349 	const struct got_error *err = NULL;
1350 
1351 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1352 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1353 
1354 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1355 		struct got_pack *pack;
1356 
1357 		pack = get_cached_pack(obj->path_packfile, repo);
1358 		if (pack == NULL) {
1359 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1360 			if (err)
1361 				goto done;
1362 		}
1363 
1364 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1365 			err = got_error_from_errno();
1366 			goto done;
1367 		}
1368 
1369 		err = got_inflate_to_mem(buf, len, pack->packfile);
1370 	} else
1371 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, repo);
1372 done:
1373 	return err;
1374 }