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Date:: Fri Jun 22 19:15:24 2018 UTC
Message:: simplify more code which assumed deltas could span mulitple packs
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1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 #include <sys/mman.h>
21 
22 #include <dirent.h>
23 #include <fcntl.h>
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdint.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <limits.h>
30 #include <sha1.h>
31 #include <endian.h>
32 #include <zlib.h>
33 
34 #include "got_error.h"
35 #include "got_object.h"
36 #include "got_repository.h"
37 #include "got_opentemp.h"
38 
39 #include "got_lib_sha1.h"
40 #include "got_lib_pack.h"
41 #include "got_lib_path.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_zbuf.h"
44 #include "got_lib_object.h"
45 #include "got_lib_repository.h"
46 
47 #ifndef nitems
48 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
49 #endif
50 
51 #define GOT_PACK_PREFIX		"pack-"
52 #define GOT_PACKFILE_SUFFIX	".pack"
53 #define GOT_PACKIDX_SUFFIX		".idx"
54 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
55 				SHA1_DIGEST_STRING_LENGTH - 1 + \
56 				strlen(GOT_PACKFILE_SUFFIX))
57 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
58 				SHA1_DIGEST_STRING_LENGTH - 1 + \
59 				strlen(GOT_PACKIDX_SUFFIX))
60 
61 #ifndef MIN
62 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
63 #endif
64 
65 static const struct got_error *
66 verify_fanout_table(uint32_t *fanout_table)
67 {
68 	int i;
69 
70 	for (i = 0; i < 0xff - 1; i++) {
71 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
72 			return got_error(GOT_ERR_BAD_PACKIDX);
73 	}
74 
75 	return NULL;
76 }
77 
78 static const struct got_error *
79 get_packfile_size(size_t *size, const char *path)
80 {
81 	struct stat sb;
82 	char *dot;
83 
84 	*size = 0;
85 
86 	dot = strrchr(path, '.');
87 	if (dot == NULL)
88 		return got_error(GOT_ERR_BAD_PATH);
89 
90 	/* Path must point to a pack index or to a pack file. */
91 	if (strcmp(dot, GOT_PACKIDX_SUFFIX) == 0) {
92 		const struct got_error *err = NULL;
93 		char *path_pack;
94 		char base_path[PATH_MAX];
95 
96 		/* Convert pack index path to pack file path. */
97 		if (strlcpy(base_path, path, PATH_MAX) > PATH_MAX)
98 			return got_error(GOT_ERR_NO_SPACE);
99 		dot = strrchr(base_path, '.');
100 		if (dot == NULL)
101 			return got_error(GOT_ERR_BAD_PATH);
102 		*dot = '\0';
103 		if (asprintf(&path_pack, "%s.pack", base_path) == -1)
104 			return got_error_from_errno();
105 
106 		if (stat(path_pack, &sb) != 0)
107 			err = got_error_from_errno();
108 		free(path_pack);
109 		if (err)
110 			return err;
111 	} else if (strcmp(dot, GOT_PACKFILE_SUFFIX) == 0) {
112 		if (stat(path, &sb) != 0)
113 			return got_error_from_errno();
114 	} else
115 		return got_error(GOT_ERR_BAD_PATH);
116 
117 	*size = sb.st_size;
118 	return 0;
119 }
120 
121 const struct got_error *
122 got_packidx_open(struct got_packidx **packidx, const char *path)
123 {
124 	struct got_packidx *p;
125 	struct got_packidx_v2_hdr *h;
126 	const struct got_error *err = NULL;
127 	size_t nobj, len_fanout, len_ids, offset, remain;
128 	SHA1_CTX ctx;
129 	uint8_t sha1[SHA1_DIGEST_LENGTH];
130 
131 	*packidx = NULL;
132 
133 	SHA1Init(&ctx);
134 
135 	p = calloc(1, sizeof(*p));
136 	if (p == NULL)
137 		return got_error_from_errno();
138 
139 	p->fd = open(path, O_RDONLY | O_NOFOLLOW, GOT_DEFAULT_FILE_MODE);
140 	if (p->fd == -1)
141 		return got_error_from_errno();
142 
143 	err = get_packfile_size(&p->len, path);
144 	if (err) {
145 		close(p->fd);
146 		free(p);
147 		return err;
148 	}
149 	if (p->len < sizeof(p->hdr)) {
150 		err = got_error(GOT_ERR_BAD_PACKIDX);
151 		close(p->fd);
152 		free(p);
153 		return err;
154 	}
155 
156 	p->path_packidx = strdup(path);
157 	if (p->path_packidx == NULL) {
158 		err = got_error_from_errno();
159 		goto done;
160 	}
161 
162 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
163 	if (p->map == MAP_FAILED) {
164 		err = got_error_from_errno();
165 		goto done;
166 	}
167 	h = &p->hdr;
168 	offset = 0;
169 	remain = p->len;
170 
171 	if (remain < sizeof(*h->magic)) {
172 		err = got_error(GOT_ERR_BAD_PACKIDX);
173 		goto done;
174 	}
175 	h->magic = (uint32_t *)(p->map + offset);
176 	if (betoh32(*h->magic) != GOT_PACKIDX_V2_MAGIC) {
177 		err = got_error(GOT_ERR_BAD_PACKIDX);
178 		goto done;
179 	}
180 	offset += sizeof(*h->magic);
181 	remain -= sizeof(*h->magic);
182 
183 	SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
184 
185 	if (remain < sizeof(*h->version)) {
186 		err = got_error(GOT_ERR_BAD_PACKIDX);
187 		goto done;
188 	}
189 	h->version = (uint32_t *)(p->map + offset);
190 	if (betoh32(*h->version) != GOT_PACKIDX_VERSION) {
191 		err = got_error(GOT_ERR_BAD_PACKIDX);
192 		goto done;
193 	}
194 	offset += sizeof(*h->version);
195 	remain -= sizeof(*h->version);
196 
197 	SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
198 
199 	len_fanout =
200 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
201 	if (remain < len_fanout) {
202 		err = got_error(GOT_ERR_BAD_PACKIDX);
203 		goto done;
204 	}
205 	h->fanout_table = (uint32_t *)(p->map + offset);
206 	err = verify_fanout_table(h->fanout_table);
207 	if (err)
208 		goto done;
209 	SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
210 	offset += len_fanout;
211 	remain -= len_fanout;
212 
213 	nobj = betoh32(h->fanout_table[0xff]);
214 	len_ids = nobj * sizeof(*h->sorted_ids);
215 	if (len_ids <= nobj || len_ids > remain) {
216 		err = got_error(GOT_ERR_BAD_PACKIDX);
217 		goto done;
218 	}
219 	h->sorted_ids =
220 	    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
221 	SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
222 	offset += len_ids;
223 	remain -= len_ids;
224 
225 	if (remain < nobj * sizeof(*h->crc32)) {
226 		err = got_error(GOT_ERR_BAD_PACKIDX);
227 		goto done;
228 	}
229 	h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
230 	SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
231 	remain -= nobj * sizeof(*h->crc32);
232 	offset += nobj * sizeof(*h->crc32);
233 
234 	if (remain < nobj * sizeof(*h->offsets)) {
235 		err = got_error(GOT_ERR_BAD_PACKIDX);
236 		goto done;
237 	}
238 	h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
239 	SHA1Update(&ctx, (uint8_t *)h->offsets, nobj * sizeof(*h->offsets));
240 	remain -= nobj * sizeof(*h->offsets);
241 	offset += nobj * sizeof(*h->offsets);
242 
243 	/* Large file offsets are contained only in files > 2GB. */
244 	if (p->len <= 0x80000000)
245 		goto checksum;
246 
247 	if (remain < nobj * sizeof(*h->large_offsets)) {
248 		err = got_error(GOT_ERR_BAD_PACKIDX);
249 		goto done;
250 	}
251 	h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
252 	SHA1Update(&ctx, (uint8_t*)h->large_offsets,
253 	    nobj * sizeof(*h->large_offsets));
254 	remain -= nobj * sizeof(*h->large_offsets);
255 	offset += nobj * sizeof(*h->large_offsets);
256 
257 checksum:
258 	if (remain < sizeof(*h->trailer)) {
259 		err = got_error(GOT_ERR_BAD_PACKIDX);
260 		goto done;
261 	}
262 	h->trailer =
263 	    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
264 	SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
265 	SHA1Final(sha1, &ctx);
266 	if (memcmp(h->trailer->packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
267 		err = got_error(GOT_ERR_PACKIDX_CSUM);
268 done:
269 	if (err)
270 		got_packidx_close(p);
271 	else
272 		*packidx = p;
273 	return err;
274 }
275 
276 const struct got_error *
277 got_packidx_close(struct got_packidx *packidx)
278 {
279 	const struct got_error *err = NULL;
280 
281 	free(packidx->path_packidx);
282 	if (packidx->map != NULL && packidx->map != MAP_FAILED) {
283 		if (munmap(packidx->map, packidx->len) == -1)
284 			err = got_error_from_errno();
285 	}
286 	close(packidx->fd);
287 	free(packidx);
288 
289 	return err;
290 }
291 
292 static int
293 is_packidx_filename(const char *name, size_t len)
294 {
295 	if (len != GOT_PACKIDX_NAMELEN)
296 		return 0;
297 
298 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
299 		return 0;
300 
301 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
302 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
303 		return 0;
304 
305 	return 1;
306 }
307 
308 static off_t
309 get_object_offset(struct got_packidx *packidx, int idx)
310 {
311 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
312 	uint32_t offset = betoh32(packidx->hdr.offsets[idx]);
313 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
314 		uint64_t loffset;
315 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
316 		if (idx < 0 || idx > totobj ||
317 		    packidx->hdr.large_offsets == NULL)
318 			return -1;
319 		loffset = betoh64(packidx->hdr.large_offsets[idx]);
320 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
321 	}
322 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
323 }
324 
325 static int
326 get_object_idx(struct got_packidx *packidx, struct got_object_id *id,
327     struct got_repository *repo)
328 {
329 	u_int8_t id0 = id->sha1[0];
330 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
331 	int left = 0, right = totobj - 1;
332 
333 	if (id0 > 0)
334 		left = betoh32(packidx->hdr.fanout_table[id0 - 1]);
335 
336 	while (left <= right) {
337 		struct got_packidx_object_id *oid;
338 		int i, cmp;
339 
340 		i = ((left + right) / 2);
341 		oid = &packidx->hdr.sorted_ids[i];
342 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
343 		if (cmp == 0)
344 			return i;
345 		else if (cmp > 0)
346 			left = i + 1;
347 		else if (cmp < 0)
348 			right = i - 1;
349 	}
350 
351 	return -1;
352 }
353 
354 static const struct got_error *
355 cache_packidx(struct got_packidx *packidx, struct got_repository *repo)
356 {
357 	const struct got_error *err = NULL;
358 	int i;
359 
360 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
361 		if (repo->packidx_cache[i] == NULL)
362 			break;
363 	}
364 
365 	if (i == nitems(repo->packidx_cache)) {
366 		err = got_packidx_close(repo->packidx_cache[i - 1]);
367 		if (err)
368 			return err;
369 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
370 		    sizeof(repo->packidx_cache) -
371 		    sizeof(repo->packidx_cache[0]));
372 		i = 0;
373 	}
374 
375 	repo->packidx_cache[i] = packidx;
376 	return NULL;
377 }
378 
379 static const struct got_error *
380 search_packidx(struct got_packidx **packidx, int *idx,
381     struct got_repository *repo, struct got_object_id *id)
382 {
383 	const struct got_error *err;
384 	char *path_packdir;
385 	DIR *packdir;
386 	struct dirent *dent;
387 	char *path_packidx;
388 	int i;
389 
390 	/* Search pack index cache. */
391 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
392 		if (repo->packidx_cache[i] == NULL)
393 			break;
394 		*idx = get_object_idx(repo->packidx_cache[i], id, repo);
395 		if (*idx != -1) {
396 			*packidx = repo->packidx_cache[i];
397 			return NULL;
398 		}
399 	}
400 	/* No luck. Search the filesystem. */
401 
402 	path_packdir = got_repo_get_path_objects_pack(repo);
403 	if (path_packdir == NULL)
404 		return got_error_from_errno();
405 
406 	packdir = opendir(path_packdir);
407 	if (packdir == NULL) {
408 		err = got_error_from_errno();
409 		goto done;
410 	}
411 
412 	while ((dent = readdir(packdir)) != NULL) {
413 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
414 			continue;
415 
416 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
417 		    dent->d_name) == -1) {
418 			err = got_error_from_errno();
419 			goto done;
420 		}
421 
422 		err = got_packidx_open(packidx, path_packidx);
423 		free(path_packidx);
424 		if (err)
425 			goto done;
426 
427 		*idx = get_object_idx(*packidx, id, repo);
428 		if (*idx != -1) {
429 			err = NULL; /* found the object */
430 			err = cache_packidx(*packidx, repo);
431 			goto done;
432 		}
433 
434 		err = got_packidx_close(*packidx);
435 		*packidx = NULL;
436 		if (err)
437 			goto done;
438 	}
439 
440 	err = got_error(GOT_ERR_NO_OBJ);
441 done:
442 	free(path_packdir);
443 	if (packdir && closedir(packdir) != 0 && err == 0)
444 		err = got_error_from_errno();
445 	return err;
446 }
447 
448 static const struct got_error *
449 get_packfile_path(char **path_packfile, struct got_repository *repo,
450     struct got_packidx *packidx)
451 {
452 	size_t size;
453 
454 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
455 	size = strlen(packidx->path_packidx) + 2;
456 	if (size < GOT_PACKFILE_NAMELEN + 1)
457 		return got_error(GOT_ERR_BAD_PATH);
458 
459 	*path_packfile = calloc(size, sizeof(**path_packfile));
460 	if (*path_packfile == NULL)
461 		return got_error_from_errno();
462 
463 	/* Copy up to and excluding ".idx". */
464 	if (strlcpy(*path_packfile, packidx->path_packidx,
465 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
466 		return got_error(GOT_ERR_NO_SPACE);
467 
468 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
469 		return got_error(GOT_ERR_NO_SPACE);
470 
471 	return NULL;
472 }
473 
474 const struct got_error *
475 read_packfile_hdr(int fd, struct got_packidx *packidx)
476 {
477 	const struct got_error *err = NULL;
478 	uint32_t totobj = betoh32(packidx->hdr.fanout_table[0xff]);
479 	struct got_packfile_hdr hdr;
480 	ssize_t n;
481 
482 	n = read(fd, &hdr, sizeof(hdr));
483 	if (n < 0)
484 		return got_error_from_errno();
485 	if (n != sizeof(hdr))
486 		return got_error(GOT_ERR_BAD_PACKFILE);
487 
488 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
489 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
490 	    betoh32(hdr.nobjects) != totobj)
491 		err = got_error(GOT_ERR_BAD_PACKFILE);
492 
493 	return err;
494 }
495 
496 static const struct got_error *
497 open_packfile(int *fd, const char *path_packfile,
498     struct got_repository *repo, struct got_packidx *packidx)
499 {
500 	const struct got_error *err = NULL;
501 
502 	*fd = open(path_packfile, O_RDONLY | O_NOFOLLOW, GOT_DEFAULT_FILE_MODE);
503 	if (*fd == -1)
504 		return got_error_from_errno();
505 
506 	if (packidx) {
507 		err = read_packfile_hdr(*fd, packidx);
508 		if (err) {
509 			close(*fd);
510 			*fd = -1;
511 		}
512 	}
513 	return err;
514 }
515 
516 void
517 got_pack_close(struct got_pack *pack)
518 {
519 	close(pack->fd);
520 	pack->fd = -1;
521 	free(pack->path_packfile);
522 	pack->path_packfile = NULL;
523 	pack->filesize = 0;
524 }
525 
526 static const struct got_error *
527 cache_pack(struct got_pack **packp, const char *path_packfile,
528     struct got_packidx *packidx, struct got_repository *repo)
529 {
530 	const struct got_error *err = NULL;
531 	struct got_pack *pack = NULL;
532 	int i;
533 
534 	if (packp)
535 		*packp = NULL;
536 
537 	for (i = 0; i < nitems(repo->packs); i++) {
538 		pack = &repo->packs[i];
539 		if (pack->path_packfile == NULL)
540 			break;
541 		if (strcmp(pack->path_packfile, path_packfile) == 0)
542 			return NULL;
543 	}
544 
545 	if (i == nitems(repo->packs) - 1) {
546 		got_pack_close(&repo->packs[i - 1]);
547 		memmove(&repo->packs[1], &repo->packs[0],
548 		    sizeof(repo->packs) - sizeof(repo->packs[0]));
549 		i = 0;
550 	}
551 
552 	pack = &repo->packs[i];
553 
554 	pack->path_packfile = strdup(path_packfile);
555 	if (pack->path_packfile == NULL) {
556 		err = got_error_from_errno();
557 		goto done;
558 	}
559 
560 	err = open_packfile(&pack->fd, path_packfile, repo, packidx);
561 	if (err)
562 		goto done;
563 
564 	err = get_packfile_size(&pack->filesize, path_packfile);
565 done:
566 	if (err) {
567 		if (pack) {
568 			free(pack->path_packfile);
569 			memset(pack, 0, sizeof(*pack));
570 		}
571 	} else if (packp)
572 		*packp = pack;
573 	return err;
574 }
575 
576 struct got_pack *
577 get_cached_pack(const char *path_packfile, struct got_repository *repo)
578 {
579 	struct got_pack *pack = NULL;
580 	int i;
581 
582 	for (i = 0; i < nitems(repo->packs); i++) {
583 		pack = &repo->packs[i];
584 		if (pack->path_packfile == NULL)
585 			break;
586 		if (strcmp(pack->path_packfile, path_packfile) == 0)
587 			return pack;
588 	}
589 
590 	return NULL;
591 }
592 
593 static const struct got_error *
594 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len, int fd)
595 {
596 	uint8_t t = 0;
597 	uint64_t s = 0;
598 	uint8_t sizeN;
599 	ssize_t n;
600 	int i = 0;
601 
602 	do {
603 		/* We do not support size values which don't fit in 64 bit. */
604 		if (i > 9)
605 			return got_error(GOT_ERR_NO_SPACE);
606 
607 		n = read(fd, &sizeN, sizeof(sizeN));
608 		if (n < 0)
609 			return got_error_from_errno();
610 		if (n != sizeof(sizeN))
611 			return got_error(GOT_ERR_BAD_PACKFILE);
612 
613 		if (i == 0) {
614 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
615 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
616 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
617 		} else {
618 			size_t shift = 4 + 7 * (i - 1);
619 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
620 		}
621 		i++;
622 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
623 
624 	*type = t;
625 	*size = s;
626 	*len = i * sizeof(sizeN);
627 	return NULL;
628 }
629 
630 static const struct got_error *
631 open_plain_object(struct got_object **obj, const char *path_packfile,
632     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
633 {
634 	*obj = calloc(1, sizeof(**obj));
635 	if (*obj == NULL)
636 		return got_error_from_errno();
637 
638 	(*obj)->path_packfile = strdup(path_packfile);
639 	if ((*obj)->path_packfile == NULL) {
640 		const struct got_error *err = got_error_from_errno();
641 		free(*obj);
642 		*obj = NULL;
643 		return err;
644 	}
645 
646 	(*obj)->type = type;
647 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
648 	(*obj)->hdrlen = 0;
649 	(*obj)->size = size;
650 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
651 	(*obj)->pack_offset = offset;
652 
653 	return NULL;
654 }
655 
656 static const struct got_error *
657 parse_negative_offset(int64_t *offset, size_t *len, int fd)
658 {
659 	int64_t o = 0;
660 	uint8_t offN;
661 	ssize_t n;
662 	int i = 0;
663 
664 	do {
665 		/* We do not support offset values which don't fit in 64 bit. */
666 		if (i > 8)
667 			return got_error(GOT_ERR_NO_SPACE);
668 
669 		n = read(fd, &offN, sizeof(offN));
670 		if (n < 0)
671 			return got_error_from_errno();
672 		if (n != sizeof(offN))
673 			return got_error(GOT_ERR_BAD_PACKFILE);
674 
675 		if (i == 0)
676 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
677 		else {
678 			o++;
679 			o <<= 7;
680 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
681 		}
682 		i++;
683 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
684 
685 	*offset = o;
686 	*len = i * sizeof(offN);
687 	return NULL;
688 }
689 
690 static const struct got_error *
691 parse_offset_delta(off_t *base_offset, int fd, off_t offset)
692 {
693 	const struct got_error *err;
694 	int64_t negoffset;
695 	size_t negofflen;
696 
697 	err = parse_negative_offset(&negoffset, &negofflen, fd);
698 	if (err)
699 		return err;
700 
701 	/* Compute the base object's offset (must be in the same pack file). */
702 	*base_offset = (offset - negoffset);
703 	if (*base_offset <= 0)
704 		return got_error(GOT_ERR_BAD_PACKFILE);
705 
706 	return NULL;
707 }
708 
709 static const struct got_error *
710 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
711     struct got_packidx *, struct got_pack *, off_t, size_t, int,
712     size_t, unsigned int);
713 
714 static const struct got_error *
715 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
716     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
717     size_t delta_data_offset, uint8_t *delta_buf, size_t delta_len)
718 {
719 	struct got_delta *delta;
720 
721 	delta = got_delta_open(path_packfile, delta_offset, tslen,
722 	    delta_type, delta_size, delta_data_offset, delta_buf,
723 	    delta_len);
724 	if (delta == NULL)
725 		return got_error_from_errno();
726 	/* delta is freed in got_object_close() */
727 	deltas->nentries++;
728 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
729 	return NULL;
730 }
731 
732 static const struct got_error *
733 resolve_offset_delta(struct got_delta_chain *deltas,
734     struct got_repository *repo, struct got_packidx *packidx,
735     struct got_pack *pack, off_t delta_offset, size_t tslen,
736     int delta_type, size_t delta_size, unsigned int recursion)
737 
738 {
739 	const struct got_error *err;
740 	off_t base_offset;
741 	uint8_t base_type;
742 	uint64_t base_size;
743 	size_t base_tslen;
744 	off_t delta_data_offset;
745 	uint8_t *delta_buf;
746 	size_t delta_len;
747 
748 	err = parse_offset_delta(&base_offset, pack->fd, delta_offset);
749 	if (err)
750 		return err;
751 
752 	delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
753 	if (delta_data_offset == -1)
754 		return got_error_from_errno();
755 
756 	err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
757 	if (err)
758 		return err;
759 
760 	err = add_delta(deltas, pack->path_packfile, delta_offset, tslen,
761 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
762 	if (err)
763 		return err;
764 
765 	/* An offset delta must be in the same packfile. */
766 	if (base_offset >= pack->filesize)
767 		return got_error(GOT_ERR_PACK_OFFSET);
768 	if (lseek(pack->fd, base_offset, SEEK_SET) == -1)
769 		return got_error_from_errno();
770 
771 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
772 	    pack->fd);
773 	if (err)
774 		return err;
775 
776 	return resolve_delta_chain(deltas, repo, packidx, pack, base_offset,
777 	    base_tslen, base_type, base_size, recursion - 1);
778 }
779 
780 static const struct got_error *
781 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
782     struct got_packidx *packidx, struct got_pack *pack,
783     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
784     unsigned int recursion)
785 {
786 	const struct got_error *err;
787 	struct got_object_id id;
788 	int idx;
789 	off_t base_offset;
790 	uint8_t base_type;
791 	uint64_t base_size;
792 	size_t base_tslen;
793 	ssize_t n;
794 	off_t delta_data_offset;
795 	uint8_t *delta_buf;
796 	size_t delta_len;
797 
798 	n = read(pack->fd, &id, sizeof(id));
799 	if (n < 0)
800 		return got_error_from_errno();
801 	if (n != sizeof(id))
802 		return got_error(GOT_ERR_BAD_PACKFILE);
803 
804 	delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
805 	if (delta_data_offset == -1)
806 		return got_error_from_errno();
807 
808 	err = got_inflate_to_mem_fd(&delta_buf, &delta_len, pack->fd);
809 	if (err)
810 		return err;
811 
812 	err = add_delta(deltas, pack->path_packfile, delta_offset, tslen,
813 	    delta_type, delta_size, delta_data_offset, delta_buf, delta_len);
814 	if (err)
815 		return err;
816 
817 	/* Delta base must be in the same pack file. */
818 	idx = get_object_idx(packidx, &id, repo);
819 	if (idx == -1)
820 		return got_error(GOT_ERR_BAD_PACKFILE);
821 
822 	base_offset = get_object_offset(packidx, idx);
823 	if (base_offset == (uint64_t)-1) {
824 		return got_error(GOT_ERR_BAD_PACKIDX);
825 	}
826 
827 	if (base_offset >= pack->filesize) {
828 		err = got_error(GOT_ERR_PACK_OFFSET);
829 		goto done;
830 	}
831 	if (lseek(pack->fd, base_offset, SEEK_SET) == -1) {
832 		err = got_error_from_errno();
833 		goto done;
834 	}
835 
836 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
837 	    pack->fd);
838 	if (err)
839 		goto done;
840 
841 	err = resolve_delta_chain(deltas, repo, packidx, pack, base_offset,
842 	    base_tslen, base_type, base_size, recursion - 1);
843 done:
844 	return err;
845 }
846 
847 static const struct got_error *
848 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
849     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
850     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
851 {
852 	const struct got_error *err = NULL;
853 
854 	if (--recursion == 0)
855 		return got_error(GOT_ERR_RECURSION);
856 
857 	switch (delta_type) {
858 	case GOT_OBJ_TYPE_COMMIT:
859 	case GOT_OBJ_TYPE_TREE:
860 	case GOT_OBJ_TYPE_BLOB:
861 	case GOT_OBJ_TYPE_TAG:
862 		/* Plain types are the final delta base. Recursion ends. */
863 		err = add_delta(deltas, pack->path_packfile, delta_offset,
864 		    tslen, delta_type, delta_size, 0, NULL, 0);
865 		break;
866 	case GOT_OBJ_TYPE_OFFSET_DELTA:
867 		err = resolve_offset_delta(deltas, repo, packidx, pack,
868 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
869 		break;
870 	case GOT_OBJ_TYPE_REF_DELTA:
871 		err = resolve_ref_delta(deltas, repo, packidx, pack,
872 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
873 		break;
874 	default:
875 		return got_error(GOT_ERR_OBJ_TYPE);
876 	}
877 
878 	return err;
879 }
880 
881 static const struct got_error *
882 open_delta_object(struct got_object **obj, struct got_repository *repo,
883     struct got_packidx *packidx, struct got_pack *pack,
884     struct got_object_id *id, off_t offset, size_t tslen,
885     int delta_type, size_t delta_size)
886 {
887 	const struct got_error *err = NULL;
888 	int resolved_type;
889 
890 	*obj = calloc(1, sizeof(**obj));
891 	if (*obj == NULL)
892 		return got_error_from_errno();
893 
894 	(*obj)->flags = 0;
895 	(*obj)->hdrlen = 0;
896 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
897 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
898 	(*obj)->pack_offset = offset + tslen;
899 
900 	(*obj)->path_packfile = strdup(pack->path_packfile);
901 	if ((*obj)->path_packfile == NULL) {
902 		err = got_error_from_errno();
903 		goto done;
904 	}
905 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
906 
907 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
908 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
909 
910 	err = resolve_delta_chain(&(*obj)->deltas, repo, packidx, pack, offset,
911 	    tslen, delta_type, delta_size, GOT_DELTA_CHAIN_RECURSION_MAX);
912 	if (err)
913 		goto done;
914 
915 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
916 	if (err)
917 		goto done;
918 	(*obj)->type = resolved_type;
919 
920 done:
921 	if (err) {
922 		got_object_close(*obj);
923 		*obj = NULL;
924 	}
925 	return err;
926 }
927 
928 static const struct got_error *
929 open_packed_object(struct got_object **obj, struct got_repository *repo,
930     struct got_packidx *packidx, int idx, struct got_object_id *id)
931 {
932 	const struct got_error *err = NULL;
933 	off_t offset;
934 	char *path_packfile;
935 	struct got_pack *pack;
936 	uint8_t type;
937 	uint64_t size;
938 	size_t tslen;
939 
940 	*obj = NULL;
941 
942 	offset = get_object_offset(packidx, idx);
943 	if (offset == (uint64_t)-1)
944 		return got_error(GOT_ERR_BAD_PACKIDX);
945 
946 	err = get_packfile_path(&path_packfile, repo, packidx);
947 	if (err)
948 		return err;
949 
950 	pack = get_cached_pack(path_packfile, repo);
951 	if (pack == NULL) {
952 		err = cache_pack(&pack, path_packfile, packidx, repo);
953 		if (err)
954 			goto done;
955 	}
956 
957 	if (offset >= pack->filesize) {
958 		err = got_error(GOT_ERR_PACK_OFFSET);
959 		goto done;
960 	}
961 	if (lseek(pack->fd, offset, SEEK_SET) == -1) {
962 		err = got_error_from_errno();
963 		goto done;
964 	}
965 
966 	err = parse_object_type_and_size(&type, &size, &tslen, pack->fd);
967 	if (err)
968 		goto done;
969 
970 	switch (type) {
971 	case GOT_OBJ_TYPE_COMMIT:
972 	case GOT_OBJ_TYPE_TREE:
973 	case GOT_OBJ_TYPE_BLOB:
974 	case GOT_OBJ_TYPE_TAG:
975 		err = open_plain_object(obj, path_packfile, id, type,
976 		    offset + tslen, size);
977 		break;
978 
979 	case GOT_OBJ_TYPE_OFFSET_DELTA:
980 	case GOT_OBJ_TYPE_REF_DELTA:
981 		err = open_delta_object(obj, repo, packidx, pack, id, offset,
982 		    tslen, type, size);
983 		break;
984 
985 	default:
986 		err = got_error(GOT_ERR_OBJ_TYPE);
987 		goto done;
988 	}
989 done:
990 	free(path_packfile);
991 	return err;
992 }
993 
994 const struct got_error *
995 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
996     struct got_repository *repo)
997 {
998 	const struct got_error *err = NULL;
999 	struct got_packidx *packidx = NULL;
1000 	int idx;
1001 
1002 	err = search_packidx(&packidx, &idx, repo, id);
1003 	if (err)
1004 		return err;
1005 
1006 	err = open_packed_object(obj, repo, packidx, idx, id);
1007 	if (err)
1008 		return err;
1009 
1010 	err = cache_pack(NULL, (*obj)->path_packfile, packidx, repo);
1011 	return err;
1012 }
1013 
1014 static const struct got_error *
1015 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
1016 {
1017 	struct got_delta *delta;
1018 	uint64_t base_size = 0, result_size = 0;
1019 
1020 	*max_size = 0;
1021 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1022 		/* Plain object types are the delta base. */
1023 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1024 		    delta->type != GOT_OBJ_TYPE_TREE &&
1025 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1026 		    delta->type != GOT_OBJ_TYPE_TAG) {
1027 			const struct got_error *err;
1028 			err = got_delta_get_sizes(&base_size, &result_size,
1029 			    delta->delta_buf, delta->delta_len);
1030 			if (err)
1031 				return err;
1032 		} else
1033 			base_size = delta->size;
1034 		if (base_size > *max_size)
1035 			*max_size = base_size;
1036 		if (result_size > *max_size)
1037 			*max_size = result_size;
1038 	}
1039 
1040 	return NULL;
1041 }
1042 
1043 static const struct got_error *
1044 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1045     FILE *outfile, struct got_repository *repo)
1046 {
1047 	const struct got_error *err = NULL;
1048 	struct got_delta *delta;
1049 	FILE *base_file = NULL, *accum_file = NULL;
1050 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1051 	size_t accum_size = 0;
1052 	uint64_t max_size;
1053 	int n = 0;
1054 
1055 	*result_size = 0;
1056 
1057 	if (SIMPLEQ_EMPTY(&deltas->entries))
1058 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1059 
1060 	/* We process small enough files entirely in memory for speed. */
1061 	err = get_delta_chain_max_size(&max_size, deltas);
1062 	if (err)
1063 		return err;
1064 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1065 		accum_buf = malloc(max_size);
1066 		if (accum_buf == NULL)
1067 			return got_error_from_errno();
1068 	} else {
1069 		base_file = got_opentemp();
1070 		if (base_file == NULL)
1071 			return got_error_from_errno();
1072 
1073 		accum_file = got_opentemp();
1074 		if (accum_file == NULL) {
1075 			err = got_error_from_errno();
1076 			fclose(base_file);
1077 			return err;
1078 		}
1079 	}
1080 
1081 	/* Deltas are ordered in ascending order. */
1082 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1083 		if (n == 0) {
1084 			struct got_pack *pack;
1085 			size_t base_len;
1086 			off_t delta_data_offset;
1087 
1088 			/* Plain object types are the delta base. */
1089 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1090 			    delta->type != GOT_OBJ_TYPE_TREE &&
1091 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1092 			    delta->type != GOT_OBJ_TYPE_TAG) {
1093 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1094 				goto done;
1095 			}
1096 
1097 			pack = get_cached_pack(delta->path_packfile, repo);
1098 			if (pack == NULL) {
1099 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1100 				goto done;
1101 			}
1102 
1103 			delta_data_offset = delta->offset + delta->tslen;
1104 			if (delta_data_offset >= pack->filesize) {
1105 				err = got_error(GOT_ERR_PACK_OFFSET);
1106 				goto done;
1107 			}
1108 			if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1109 			    == -1) {
1110 				err = got_error_from_errno();
1111 				goto done;
1112 			}
1113 			if (base_file)
1114 				err = got_inflate_to_file_fd(&base_len,
1115 				    pack->fd, base_file);
1116 			else {
1117 				err = got_inflate_to_mem_fd(&base_buf,
1118 				    &base_len, pack->fd);
1119 				if (base_len < max_size) {
1120 					uint8_t *p;
1121 					p = reallocarray(base_buf, 1, max_size);
1122 					if (p == NULL) {
1123 						err = got_error_from_errno();
1124 						goto done;
1125 					}
1126 					base_buf = p;
1127 				}
1128 			}
1129 			if (err)
1130 				goto done;
1131 			n++;
1132 			if (base_file)
1133 				rewind(base_file);
1134 			continue;
1135 		}
1136 
1137 		if (base_buf) {
1138 			err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1139 			    delta->delta_len, accum_buf, &accum_size);
1140 			n++;
1141 		} else {
1142 			err = got_delta_apply(base_file, delta->delta_buf,
1143 			    delta->delta_len,
1144 			    /* Final delta application writes to output file. */
1145 			    ++n < deltas->nentries ? accum_file : outfile,
1146 			    &accum_size);
1147 		}
1148 		if (err)
1149 			goto done;
1150 
1151 		if (n < deltas->nentries) {
1152 			/* Accumulated delta becomes the new base. */
1153 			if (base_buf) {
1154 				uint8_t *tmp = accum_buf;
1155 				accum_buf = base_buf;
1156 				base_buf = tmp;
1157 			} else {
1158 				FILE *tmp = accum_file;
1159 				accum_file = base_file;
1160 				base_file = tmp;
1161 				rewind(base_file);
1162 				rewind(accum_file);
1163 			}
1164 		}
1165 	}
1166 
1167 done:
1168 	free(base_buf);
1169 	if (accum_buf) {
1170 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1171 		free(accum_buf);
1172 		if (len != accum_size)
1173 			return got_ferror(outfile, GOT_ERR_IO);
1174 	}
1175 	if (base_file)
1176 		fclose(base_file);
1177 	if (accum_file)
1178 		fclose(accum_file);
1179 	rewind(outfile);
1180 	if (err == NULL)
1181 		*result_size = accum_size;
1182 	return err;
1183 }
1184 
1185 static const struct got_error *
1186 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1187     struct got_delta_chain *deltas, struct got_repository *repo)
1188 {
1189 	const struct got_error *err = NULL;
1190 	struct got_delta *delta;
1191 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1192 	size_t accum_size;
1193 	uint64_t max_size;
1194 	int n = 0;
1195 
1196 	*outbuf = NULL;
1197 	*outlen = 0;
1198 
1199 	if (SIMPLEQ_EMPTY(&deltas->entries))
1200 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1201 
1202 	err = get_delta_chain_max_size(&max_size, deltas);
1203 	if (err)
1204 		return err;
1205 	accum_buf = malloc(max_size);
1206 	if (accum_buf == NULL)
1207 		return got_error_from_errno();
1208 
1209 	/* Deltas are ordered in ascending order. */
1210 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1211 		if (n == 0) {
1212 			struct got_pack *pack;
1213 			size_t base_len;
1214 			size_t delta_data_offset;
1215 
1216 			/* Plain object types are the delta base. */
1217 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1218 			    delta->type != GOT_OBJ_TYPE_TREE &&
1219 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1220 			    delta->type != GOT_OBJ_TYPE_TAG) {
1221 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1222 				goto done;
1223 			}
1224 
1225 			pack = get_cached_pack(delta->path_packfile, repo);
1226 			if (pack == NULL) {
1227 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1228 				goto done;
1229 			}
1230 
1231 			delta_data_offset = delta->offset + delta->tslen;
1232 			if (delta_data_offset >= pack->filesize) {
1233 				err = got_error(GOT_ERR_PACK_OFFSET);
1234 				goto done;
1235 			}
1236 			if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1237 			    == -1) {
1238 				err = got_error_from_errno();
1239 				goto done;
1240 			}
1241 			err = got_inflate_to_mem_fd(&base_buf, &base_len,
1242 			    pack->fd);
1243 			if (base_len < max_size) {
1244 				uint8_t *p;
1245 				p = reallocarray(base_buf, 1, max_size);
1246 				if (p == NULL) {
1247 					err = got_error_from_errno();
1248 					goto done;
1249 				}
1250 				base_buf = p;
1251 			}
1252 			if (err)
1253 				goto done;
1254 			n++;
1255 			continue;
1256 		}
1257 
1258 		err = got_delta_apply_in_mem(base_buf, delta->delta_buf,
1259 		    delta->delta_len, accum_buf, &accum_size);
1260 		n++;
1261 		if (err)
1262 			goto done;
1263 
1264 		if (n < deltas->nentries) {
1265 			/* Accumulated delta becomes the new base. */
1266 			uint8_t *tmp = accum_buf;
1267 			accum_buf = base_buf;
1268 			base_buf = tmp;
1269 		}
1270 	}
1271 
1272 done:
1273 	free(base_buf);
1274 	if (err) {
1275 		free(accum_buf);
1276 		*outbuf = NULL;
1277 		*outlen = 0;
1278 	} else {
1279 		*outbuf = accum_buf;
1280 		*outlen = accum_size;
1281 	}
1282 	return err;
1283 }
1284 
1285 const struct got_error *
1286 got_packfile_extract_object(FILE **f, struct got_object *obj,
1287     struct got_repository *repo)
1288 {
1289 	const struct got_error *err = NULL;
1290 
1291 	*f = NULL;
1292 
1293 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1294 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1295 
1296 	*f = got_opentemp();
1297 	if (*f == NULL) {
1298 		err = got_error_from_errno();
1299 		goto done;
1300 	}
1301 
1302 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1303 		struct got_pack *pack;
1304 
1305 		pack = get_cached_pack(obj->path_packfile, repo);
1306 		if (pack == NULL) {
1307 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1308 			if (err)
1309 				goto done;
1310 		}
1311 
1312 		if (obj->pack_offset >= pack->filesize) {
1313 			err = got_error(GOT_ERR_PACK_OFFSET);
1314 			goto done;
1315 		}
1316 		if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1) {
1317 			err = got_error_from_errno();
1318 			goto done;
1319 		}
1320 
1321 		err = got_inflate_to_file_fd(&obj->size, pack->fd, *f);
1322 	} else
1323 		err = dump_delta_chain_to_file(&obj->size,
1324 		    &obj->deltas, *f, repo);
1325 done:
1326 	if (err && *f) {
1327 		fclose(*f);
1328 		*f = NULL;
1329 	}
1330 	return err;
1331 }
1332 
1333 const struct got_error *
1334 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1335     struct got_object *obj, struct got_repository *repo)
1336 {
1337 	const struct got_error *err = NULL;
1338 
1339 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1340 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1341 
1342 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1343 		struct got_pack *pack;
1344 
1345 		pack = get_cached_pack(obj->path_packfile, repo);
1346 		if (pack == NULL) {
1347 			err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1348 			if (err)
1349 				goto done;
1350 		}
1351 
1352 		if (obj->pack_offset >= pack->filesize) {
1353 			err = got_error(GOT_ERR_PACK_OFFSET);
1354 			goto done;
1355 		}
1356 		if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1) {
1357 			err = got_error_from_errno();
1358 			goto done;
1359 		}
1360 
1361 		err = got_inflate_to_mem_fd(buf, len, pack->fd);
1362 	} else
1363 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, repo);
1364 done:
1365 	return err;
1366 }