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 
38 #include "got_sha1_lib.h"
39 #include "got_pack_lib.h"
40 #include "got_path_lib.h"
41 #include "got_delta_lib.h"
42 #include "got_zbuf_lib.h"
43 #include "got_object_lib.h"
44 #include "got_repository_lib.h"
45 
46 #ifndef nitems
47 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
48 #endif
49 
50 #define GOT_PACK_PREFIX		"pack-"
51 #define GOT_PACKFILE_SUFFIX	".pack"
52 #define GOT_PACKIDX_SUFFIX		".idx"
53 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
54 				SHA1_DIGEST_STRING_LENGTH - 1 + \
55 				strlen(GOT_PACKFILE_SUFFIX))
56 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
57 				SHA1_DIGEST_STRING_LENGTH - 1 + \
58 				strlen(GOT_PACKIDX_SUFFIX))
59 
60 #ifndef MIN
61 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
62 #endif
63 
64 static const struct got_error *
65 verify_fanout_table(uint32_t *fanout_table)
66 {
67 	int i;
68 
69 	for (i = 0; i < 0xff - 1; i++) {
70 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
71 			return got_error(GOT_ERR_BAD_PACKIDX);
72 	}
73 
74 	return NULL;
75 }
76 
77 static const struct got_error *
78 get_packfile_size(size_t *size, const char *path_idx)
79 {
80 	struct stat sb;
81 	char *path_pack;
82 	char base_path[PATH_MAX];
83 	char *dot;
84 
85 	if (strlcpy(base_path, path_idx, PATH_MAX) > PATH_MAX)
86 		return got_error(GOT_ERR_NO_SPACE);
87 
88 	dot = strrchr(base_path, '.');
89 	if (dot == NULL)
90 		return got_error(GOT_ERR_BAD_PATH);
91 	*dot = '\0';
92 	if (asprintf(&path_pack, "%s.pack", base_path) == -1)
93 		return got_error(GOT_ERR_NO_MEM);
94 
95 	if (stat(path_pack, &sb) != 0) {
96 		free(path_pack);
97 		return got_error_from_errno();
98 	}
99 
100 	free(path_pack);
101 	*size = sb.st_size;
102 	return 0;
103 }
104 
105 const struct got_error *
106 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
107 {
108 	struct got_packidx_v2_hdr *p;
109 	FILE *f;
110 	const struct got_error *err = NULL;
111 	size_t n, nobj, packfile_size;
112 	SHA1_CTX ctx;
113 	uint8_t sha1[SHA1_DIGEST_LENGTH];
114 
115 	SHA1Init(&ctx);
116 
117 	f = fopen(path, "rb");
118 	if (f == NULL)
119 		return got_error_from_errno();
120 
121 	err = get_packfile_size(&packfile_size, path);
122 	if (err)
123 		return err;
124 
125 	p = calloc(1, sizeof(*p));
126 	if (p == NULL) {
127 		err = got_error(GOT_ERR_NO_MEM);
128 		goto done;
129 	}
130 
131 	n = fread(&p->magic, sizeof(p->magic), 1, f);
132 	if (n != 1) {
133 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
134 		goto done;
135 	}
136 
137 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
138 		err = got_error(GOT_ERR_BAD_PACKIDX);
139 		goto done;
140 	}
141 
142 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
143 
144 	n = fread(&p->version, sizeof(p->version), 1, f);
145 	if (n != 1) {
146 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
147 		goto done;
148 	}
149 
150 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
151 		err = got_error(GOT_ERR_BAD_PACKIDX);
152 		goto done;
153 	}
154 
155 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
156 
157 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
158 	if (n != 1) {
159 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
160 		goto done;
161 	}
162 
163 	err = verify_fanout_table(p->fanout_table);
164 	if (err)
165 		goto done;
166 
167 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
168 
169 	nobj = betoh32(p->fanout_table[0xff]);
170 
171 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
172 	if (p->sorted_ids == NULL) {
173 		err = got_error(GOT_ERR_NO_MEM);
174 		goto done;
175 	}
176 
177 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
178 	if (n != nobj) {
179 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
180 		goto done;
181 	}
182 
183 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
184 	    nobj * sizeof(*p->sorted_ids));
185 
186 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
187 	if (p->crc32 == NULL) {
188 		err = got_error(GOT_ERR_NO_MEM);
189 		goto done;
190 	}
191 
192 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
193 	if (n != nobj) {
194 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
195 		goto done;
196 	}
197 
198 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
199 
200 	p->offsets = calloc(nobj, sizeof(*p->offsets));
201 	if (p->offsets == NULL) {
202 		err = got_error(GOT_ERR_NO_MEM);
203 		goto done;
204 	}
205 
206 	n = fread(p->offsets, sizeof(*p->offsets), 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->offsets, nobj * sizeof(*p->offsets));
213 
214 	/* Large file offsets are contained only in files > 2GB. */
215 	if (packfile_size <= 0x80000000)
216 		goto checksum;
217 
218 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
219 	if (p->large_offsets == NULL) {
220 		err = got_error(GOT_ERR_NO_MEM);
221 		goto done;
222 	}
223 
224 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
225 	if (n != nobj) {
226 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
227 		goto done;
228 	}
229 
230 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
231 	    nobj * sizeof(*p->large_offsets));
232 
233 checksum:
234 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
235 	if (n != 1) {
236 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
237 		goto done;
238 	}
239 
240 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
241 	SHA1Final(sha1, &ctx);
242 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
243 		err = got_error(GOT_ERR_PACKIDX_CSUM);
244 done:
245 	fclose(f);
246 	if (err)
247 		got_packidx_close(p);
248 	else
249 		*packidx = p;
250 	return err;
251 }
252 
253 void
254 got_packidx_close(struct got_packidx_v2_hdr *packidx)
255 {
256 	free(packidx->sorted_ids);
257 	free(packidx->offsets);
258 	free(packidx->crc32);
259 	free(packidx->large_offsets);
260 	free(packidx);
261 }
262 
263 static int
264 is_packidx_filename(const char *name, size_t len)
265 {
266 	if (len != GOT_PACKIDX_NAMELEN)
267 		return 0;
268 
269 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
270 		return 0;
271 
272 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
273 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
274 		return 0;
275 
276 	return 1;
277 }
278 
279 static off_t
280 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
281 {
282 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
283 	uint32_t offset = betoh32(packidx->offsets[idx]);
284 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
285 		uint64_t loffset;
286 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
287 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
288 			return -1;
289 		loffset = betoh64(packidx->large_offsets[idx]);
290 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
291 	}
292 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
293 }
294 
295 static int
296 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id)
297 {
298 	u_int8_t id0 = id->sha1[0];
299 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
300 	int i = 0;
301 
302 	if (id0 > 0)
303 		i = betoh32(packidx->fanout_table[id0 - 1]);
304 
305 	while (i < totobj) {
306 		struct got_object_id *oid = &packidx->sorted_ids[i];
307 		int cmp = got_object_id_cmp(id, oid);
308 
309 		if (cmp == 0)
310 			return i;
311 		i++;
312 	}
313 
314 	return -1;
315 }
316 
317 static struct got_packidx_v2_hdr *
318 dup_packidx(struct got_packidx_v2_hdr *packidx)
319 {
320 	struct got_packidx_v2_hdr *p;
321 	size_t nobj;
322 
323 	p = calloc(1, sizeof(*p));
324 	if (p == NULL)
325 		return NULL;
326 
327 	memcpy(p, packidx, sizeof(*p));
328 	p->sorted_ids = NULL;
329 	p->crc32 = NULL;
330 	p->offsets = NULL;
331 	p->large_offsets = NULL;
332 
333 	nobj = betoh32(p->fanout_table[0xff]);
334 
335 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
336 	if (p->sorted_ids == NULL)
337 		goto err;
338 	memcpy(p->sorted_ids, packidx->sorted_ids, nobj * sizeof(*p->sorted_ids));
339 
340 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
341 	if (p->crc32 == NULL)
342 		goto err;
343 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
344 
345 	p->offsets = calloc(nobj, sizeof(*p->offsets));
346 	if (p->offsets == NULL)
347 		goto err;
348 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
349 
350 	if (p->large_offsets) {
351 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
352 		if (p->large_offsets == NULL)
353 			goto err;
354 		memcpy(p->large_offsets, packidx->large_offsets,
355 		    nobj * sizeof(*p->large_offsets));
356 	}
357 
358 	return p;
359 
360 err:
361 	free(p->large_offsets);
362 	free(p->offsets);
363 	free(p->crc32);
364 	free(p->sorted_ids);
365 	free(p);
366 	return NULL;
367 }
368 
369 static void
370 cache_packidx(struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
371 {
372 	int i;
373 
374 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
375 		if (repo->packidx_cache[i] == NULL)
376 			break;
377 	}
378 
379 	if (i == nitems(repo->packidx_cache)) {
380 		got_packidx_close(repo->packidx_cache[i - 1]);
381 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
382 		    sizeof(repo->packidx_cache) -
383 		    sizeof(repo->packidx_cache[0]));
384 		i = 0;
385 	}
386 
387 	repo->packidx_cache[i] = dup_packidx(packidx);
388 }
389 
390 static const struct got_error *
391 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
392     struct got_repository *repo, struct got_object_id *id)
393 {
394 	const struct got_error *err;
395 	char *path_packdir;
396 	DIR *packdir;
397 	struct dirent *dent;
398 	char *path_packidx;
399 	int i;
400 
401 	/* Search pack index cache. */
402 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
403 		if (repo->packidx_cache[i] == NULL)
404 			break;
405 		*idx = get_object_idx(repo->packidx_cache[i], id);
406 		if (*idx != -1) {
407 			*packidx = dup_packidx(repo->packidx_cache[i]);
408 			if (*packidx == NULL)
409 				return got_error(GOT_ERR_NO_MEM);
410 			return NULL;
411 		}
412 	}
413 	/* No luck. Search the filesystem. */
414 
415 	path_packdir = got_repo_get_path_objects_pack(repo);
416 	if (path_packdir == NULL)
417 		return got_error(GOT_ERR_NO_MEM);
418 
419 	packdir = opendir(path_packdir);
420 	if (packdir == NULL) {
421 		err = got_error_from_errno();
422 		goto done;
423 	}
424 
425 	while ((dent = readdir(packdir)) != NULL) {
426 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
427 			continue;
428 
429 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
430 		    dent->d_name) == -1) {
431 			err = got_error(GOT_ERR_NO_MEM);
432 			goto done;
433 		}
434 
435 		err = got_packidx_open(packidx, path_packidx);
436 		free(path_packidx);
437 		if (err)
438 			goto done;
439 
440 		*idx = get_object_idx(*packidx, id);
441 		if (*idx != -1) {
442 			err = NULL; /* found the object */
443 			cache_packidx(*packidx, repo);
444 			goto done;
445 		}
446 
447 		got_packidx_close(*packidx);
448 		*packidx = NULL;
449 	}
450 
451 	err = got_error(GOT_ERR_NO_OBJ);
452 done:
453 	free(path_packdir);
454 	if (packdir && closedir(packdir) != 0 && err == 0)
455 		err = got_error_from_errno();
456 	return err;
457 }
458 
459 static const struct got_error *
460 get_packfile_path(char **path_packfile, struct got_repository *repo,
461     struct got_packidx_v2_hdr *packidx)
462 {
463 	char *path_packdir;
464 	char hex[SHA1_DIGEST_STRING_LENGTH];
465 	char *sha1str;
466 
467 	path_packdir = got_repo_get_path_objects_pack(repo);
468 	if (path_packdir == NULL)
469 		return got_error(GOT_ERR_NO_MEM);
470 
471 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
472 	    hex, sizeof(hex));
473 	if (sha1str == NULL)
474 		return got_error(GOT_ERR_PACKIDX_CSUM);
475 
476 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
477 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
478 		*path_packfile = NULL;
479 		return got_error(GOT_ERR_NO_MEM);
480 	}
481 
482 	return NULL;
483 }
484 
485 const struct got_error *
486 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
487 {
488 	const struct got_error *err = NULL;
489 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
490 	struct got_packfile_hdr hdr;
491 	size_t n;
492 
493 	n = fread(&hdr, sizeof(hdr), 1, f);
494 	if (n != 1)
495 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
496 
497 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
498 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
499 	    betoh32(hdr.nobjects) != totobj)
500 		err = got_error(GOT_ERR_BAD_PACKFILE);
501 
502 	return err;
503 }
504 
505 #ifdef notyet
506 static const struct got_error *
507 map_packfile_segment(struct got_pack_mapping **map, const char *path_packfile,
508     off_t offset, size_t len)
509 {
510 	const struct got_error *err = NULL;
511 
512 	if (len < GOT_PACK_MAPPING_MIN_SIZE)
513 		len = GOT_PACK_MAPPING_MIN_SIZE;
514 
515 	if (len > GOT_PACK_MAPPING_MAX_SIZE)
516 		return got_error(GOT_ERR_NO_SPACE);
517 
518 	*map = calloc(1, sizeof(**map));
519 	if (*map == NULL)
520 		return got_error(GOT_ERR_NO_MEM);
521 
522 	(*map)->fd = open(path_packfile, O_RDONLY | O_NOFOLLOW);
523 	if ((*map)->fd == -1) {
524 		err = got_error_from_errno();
525 		free((*map));
526 		*map = NULL;
527 		return err;
528 	}
529 
530 	(*map)->addr = mmap(NULL, len, PROT_READ, MAP_PRIVATE, (*map)->fd, offset);
531 	if ((*map)->addr == NULL) {
532 		err = got_error_from_errno();
533 		close((*map)->fd);
534 		free((*map));
535 		*map = NULL;
536 		return err;
537 	}
538 
539 	(*map)->offset = offset;
540 	(*map)->len = len;
541 
542 	return NULL;
543 }
544 #endif
545 
546 static const struct got_error *
547 unmap_packfile_segment(struct got_pack_mapping *map)
548 {
549 	if (munmap(map->addr, map->len) == -1 || close(map->fd) == -1)
550 		return got_error_from_errno();
551 	free(map);
552 	return NULL;
553 }
554 
555 static const struct got_error *
556 open_packfile(FILE **packfile, const char *path_packfile,
557     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
558 {
559 	const struct got_error *err = NULL;
560 
561 	*packfile = NULL;
562 
563 	*packfile = fopen(path_packfile, "rb");
564 	if (*packfile == NULL) {
565 		err = got_error_from_errno();
566 		return err;
567 	}
568 
569 	if (packidx) {
570 		err = read_packfile_hdr(*packfile, packidx);
571 		if (err) {
572 			fclose(*packfile);
573 			*packfile = NULL;
574 		}
575 	}
576 	return err;
577 }
578 
579 const struct got_error *
580 got_pack_close(struct got_pack *pack)
581 {
582 	const struct got_error *err = NULL;
583 	int i;
584 
585 	while (!TAILQ_EMPTY(&pack->mappings)) {
586 		struct got_pack_mapping *map = TAILQ_FIRST(&pack->mappings);
587 		err = unmap_packfile_segment(map);
588 		if (err)
589 			break;
590 		TAILQ_REMOVE(&pack->mappings, map, entry);
591 		pack->nmappings--;
592 	}
593 
594 	if (err == NULL) {
595 		fclose(pack->packfile);
596 		pack->packfile = NULL;
597 		free(pack->path_packfile);
598 		pack->path_packfile = NULL;
599 		pack->filesize = 0;
600 	}
601 
602 	for (i = 0; i < pack->delta_cache.nentries; i++) {
603 		struct got_delta_cache_entry *entry;
604 		entry = &pack->delta_cache.deltas[i];
605 		entry->data_offset = 0;
606 		free(entry->delta_buf);
607 		entry->delta_buf = NULL;
608 		entry->delta_len = 0;
609 	}
610 	pack->delta_cache.nentries = 0;
611 
612 	return err;
613 }
614 
615 static const struct got_error *
616 cache_pack(struct got_pack **packp, const char *path_packfile,
617     struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
618 {
619 	const struct got_error *err = NULL;
620 	struct got_pack *pack = NULL;
621 	int i;
622 
623 	if (packp)
624 		*packp = NULL;
625 
626 	for (i = 0; i < nitems(repo->packs); i++) {
627 		pack = &repo->packs[i];
628 		if (pack->path_packfile == NULL)
629 			break;
630 		if (strcmp(pack->path_packfile, path_packfile) == 0)
631 			return NULL;
632 	}
633 
634 	if (i == nitems(repo->packs) - 1) {
635 		got_pack_close(&repo->packs[i - 1]);
636 		memmove(&repo->packs[1], &repo->packs[0],
637 		    sizeof(repo->packs) - sizeof(repo->packs[0]));
638 		i = 0;
639 	}
640 
641 	pack = &repo->packs[i];
642 
643 	TAILQ_INIT(&pack->mappings);
644 
645 	pack->path_packfile = strdup(path_packfile);
646 	if (pack->path_packfile == NULL) {
647 		err = got_error(GOT_ERR_NO_MEM);
648 		goto done;
649 	}
650 
651 	err = open_packfile(&pack->packfile, path_packfile, repo, packidx);
652 	if (err)
653 		goto done;
654 
655 	err = get_packfile_size(&pack->filesize, path_packfile);
656 done:
657 	if (err) {
658 		if (pack)
659 			free(pack->path_packfile);
660 		free(pack);
661 	} else if (packp)
662 		*packp = pack;
663 	return err;
664 }
665 
666 struct got_pack *
667 get_cached_pack(const char *path_packfile, struct got_repository *repo)
668 {
669 	struct got_pack *pack = NULL;
670 	int i;
671 
672 	for (i = 0; i < nitems(repo->packs); i++) {
673 		pack = &repo->packs[i];
674 		if (pack->path_packfile == NULL)
675 			break;
676 		if (strcmp(pack->path_packfile, path_packfile) == 0)
677 			return pack;
678 	}
679 
680 	return NULL;
681 }
682 
683 static const struct got_error *
684 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
685     FILE *packfile)
686 {
687 	uint8_t t = 0;
688 	uint64_t s = 0;
689 	uint8_t sizeN;
690 	size_t n;
691 	int i = 0;
692 
693 	do {
694 		/* We do not support size values which don't fit in 64 bit. */
695 		if (i > 9)
696 			return got_error(GOT_ERR_NO_SPACE);
697 
698 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
699 		if (n != 1)
700 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
701 
702 		if (i == 0) {
703 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
704 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
705 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
706 		} else {
707 			size_t shift = 4 + 7 * (i - 1);
708 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
709 		}
710 		i++;
711 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
712 
713 	*type = t;
714 	*size = s;
715 	*len = i * sizeof(sizeN);
716 	return NULL;
717 }
718 
719 static const struct got_error *
720 open_plain_object(struct got_object **obj, const char *path_packfile,
721     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
722 {
723 	*obj = calloc(1, sizeof(**obj));
724 	if (*obj == NULL)
725 		return got_error(GOT_ERR_NO_MEM);
726 
727 	(*obj)->path_packfile = strdup(path_packfile);
728 	if ((*obj)->path_packfile == NULL) {
729 		free(*obj);
730 		*obj = NULL;
731 		return got_error(GOT_ERR_NO_MEM);
732 	}
733 
734 	(*obj)->type = type;
735 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
736 	(*obj)->hdrlen = 0;
737 	(*obj)->size = size;
738 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
739 	(*obj)->pack_offset = offset;
740 
741 	return NULL;
742 }
743 
744 static const struct got_error *
745 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
746 {
747 	int64_t o = 0;
748 	uint8_t offN;
749 	size_t n;
750 	int i = 0;
751 
752 	do {
753 		/* We do not support offset values which don't fit in 64 bit. */
754 		if (i > 8)
755 			return got_error(GOT_ERR_NO_SPACE);
756 
757 		n = fread(&offN, sizeof(offN), 1, packfile);
758 		if (n != 1)
759 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
760 
761 		if (i == 0)
762 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
763 		else {
764 			o++;
765 			o <<= 7;
766 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
767 		}
768 		i++;
769 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
770 
771 	*offset = o;
772 	*len = i * sizeof(offN);
773 	return NULL;
774 }
775 
776 static const struct got_error *
777 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
778 {
779 	const struct got_error *err;
780 	int64_t negoffset;
781 	size_t negofflen;
782 
783 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
784 	if (err)
785 		return err;
786 
787 	/* Compute the base object's offset (must be in the same pack file). */
788 	*base_offset = (offset - negoffset);
789 	if (*base_offset <= 0)
790 		return got_error(GOT_ERR_BAD_PACKFILE);
791 
792 	return NULL;
793 }
794 
795 static const struct got_error *
796 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
797     FILE *, const char *, off_t, size_t, int, size_t);
798 
799 static const struct got_error *
800 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
801     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
802     size_t delta_data_offset)
803 {
804 	struct got_delta *delta;
805 
806 	delta = got_delta_open(path_packfile, delta_offset, tslen,
807 	    delta_type, delta_size, delta_data_offset);
808 	if (delta == NULL)
809 		return got_error(GOT_ERR_NO_MEM);
810 	/* delta is freed in got_object_close() */
811 	deltas->nentries++;
812 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
813 	return NULL;
814 }
815 
816 static const struct got_error *
817 resolve_offset_delta(struct got_delta_chain *deltas,
818     struct got_repository *repo, FILE *packfile, const char *path_packfile,
819     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size)
820 
821 {
822 	const struct got_error *err;
823 	off_t base_offset;
824 	uint8_t base_type;
825 	uint64_t base_size;
826 	size_t base_tslen;
827 	off_t delta_data_offset;
828 
829 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
830 	if (err)
831 		return err;
832 
833 	delta_data_offset = ftello(packfile);
834 	if (delta_data_offset == -1)
835 		return got_error_from_errno();
836 
837 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
838 	    delta_type, delta_size, delta_data_offset);
839 	if (err)
840 		return err;
841 
842 	/* An offset delta must be in the same packfile. */
843 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
844 		return got_error_from_errno();
845 
846 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
847 	    packfile);
848 	if (err)
849 		return err;
850 
851 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
852 	    base_offset, base_tslen, base_type, base_size);
853 }
854 
855 static const struct got_error *
856 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
857     FILE *packfile, const char *path_packfile, off_t delta_offset,
858     size_t tslen, int delta_type, size_t delta_size)
859 {
860 	const struct got_error *err;
861 	struct got_object_id id;
862 	struct got_packidx_v2_hdr *packidx;
863 	int idx;
864 	off_t base_offset;
865 	uint8_t base_type;
866 	uint64_t base_size;
867 	size_t base_tslen;
868 	size_t n;
869 	char *path_base_packfile;
870 	struct got_pack *base_pack;
871 	off_t delta_data_offset;
872 
873 	n = fread(&id, sizeof(id), 1, packfile);
874 	if (n != 1)
875 		return got_ferror(packfile, GOT_ERR_IO);
876 
877 	delta_data_offset = ftello(packfile);
878 	if (delta_data_offset == -1)
879 		return got_error_from_errno();
880 
881 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
882 	    delta_type, delta_size, delta_data_offset);
883 	if (err)
884 		return err;
885 
886 	err = search_packidx(&packidx, &idx, repo, &id);
887 	if (err)
888 		return err;
889 
890 	base_offset = get_object_offset(packidx, idx);
891 	if (base_offset == (uint64_t)-1) {
892 		got_packidx_close(packidx);
893 		return got_error(GOT_ERR_BAD_PACKIDX);
894 	}
895 
896 	err = get_packfile_path(&path_base_packfile, repo, packidx);
897 	if (err)
898 		return err;
899 
900 	base_pack = get_cached_pack(path_base_packfile, repo);
901 	if (base_pack == NULL) {
902 		err = cache_pack(&base_pack, path_base_packfile, NULL, repo);
903 		if (err)
904 			goto done;
905 	}
906 
907 	if (fseeko(base_pack->packfile, base_offset, SEEK_SET) != 0) {
908 		err = got_error_from_errno();
909 		goto done;
910 	}
911 
912 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
913 	    base_pack->packfile);
914 	if (err)
915 		goto done;
916 
917 	err = resolve_delta_chain(deltas, repo, base_pack->packfile,
918 	    path_base_packfile, base_offset, base_tslen, base_type,
919 	    base_size);
920 done:
921 	free(path_base_packfile);
922 	return err;
923 }
924 
925 static const struct got_error *
926 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
927     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
928     int delta_type, size_t delta_size)
929 {
930 	const struct got_error *err = NULL;
931 
932 	switch (delta_type) {
933 	case GOT_OBJ_TYPE_COMMIT:
934 	case GOT_OBJ_TYPE_TREE:
935 	case GOT_OBJ_TYPE_BLOB:
936 	case GOT_OBJ_TYPE_TAG:
937 		/* Plain types are the final delta base. Recursion ends. */
938 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
939 		    delta_type, delta_size, 0);
940 		break;
941 	case GOT_OBJ_TYPE_OFFSET_DELTA:
942 		err = resolve_offset_delta(deltas, repo, packfile,
943 		    path_packfile, delta_offset, tslen, delta_type,
944 		    delta_size);
945 		break;
946 	case GOT_OBJ_TYPE_REF_DELTA:
947 		err = resolve_ref_delta(deltas, repo, packfile,
948 		    path_packfile, delta_offset, tslen, delta_type,
949 		    delta_size);
950 		break;
951 	default:
952 		return got_error(GOT_ERR_NOT_IMPL);
953 	}
954 
955 	return err;
956 }
957 
958 static const struct got_error *
959 open_delta_object(struct got_object **obj, struct got_repository *repo,
960     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
961     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
962     int delta_type, size_t delta_size)
963 {
964 	const struct got_error *err = NULL;
965 	int resolved_type;
966 
967 	*obj = calloc(1, sizeof(**obj));
968 	if (*obj == NULL)
969 		return got_error(GOT_ERR_NO_MEM);
970 
971 	(*obj)->flags = 0;
972 	(*obj)->hdrlen = 0;
973 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
974 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
975 	(*obj)->pack_offset = offset + tslen;
976 
977 	(*obj)->path_packfile = strdup(path_packfile);
978 	if ((*obj)->path_packfile == NULL) {
979 		err = got_error(GOT_ERR_NO_MEM);
980 		goto done;
981 	}
982 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
983 
984 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
985 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
986 
987 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
988 	    path_packfile, offset, tslen, delta_type, delta_size);
989 	if (err)
990 		goto done;
991 
992 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
993 	if (err)
994 		goto done;
995 	(*obj)->type = resolved_type;
996 
997 done:
998 	if (err) {
999 		got_object_close(*obj);
1000 		*obj = NULL;
1001 	}
1002 	return err;
1003 }
1004 
1005 static const struct got_error *
1006 open_packed_object(struct got_object **obj, struct got_repository *repo,
1007     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
1008 {
1009 	const struct got_error *err = NULL;
1010 	off_t offset;
1011 	char *path_packfile;
1012 	struct got_pack *pack;
1013 	uint8_t type;
1014 	uint64_t size;
1015 	size_t tslen;
1016 
1017 	*obj = NULL;
1018 
1019 	offset = get_object_offset(packidx, idx);
1020 	if (offset == (uint64_t)-1)
1021 		return got_error(GOT_ERR_BAD_PACKIDX);
1022 
1023 	err = get_packfile_path(&path_packfile, repo, packidx);
1024 	if (err)
1025 		return err;
1026 
1027 	pack = get_cached_pack(path_packfile, repo);
1028 	if (pack == NULL) {
1029 		err = cache_pack(&pack, path_packfile, packidx, repo);
1030 		if (err)
1031 			goto done;
1032 	}
1033 
1034 	if (fseeko(pack->packfile, offset, SEEK_SET) != 0) {
1035 		err = got_error_from_errno();
1036 		goto done;
1037 	}
1038 
1039 	err = parse_object_type_and_size(&type, &size, &tslen, pack->packfile);
1040 	if (err)
1041 		goto done;
1042 
1043 	switch (type) {
1044 	case GOT_OBJ_TYPE_COMMIT:
1045 	case GOT_OBJ_TYPE_TREE:
1046 	case GOT_OBJ_TYPE_BLOB:
1047 	case GOT_OBJ_TYPE_TAG:
1048 		err = open_plain_object(obj, path_packfile, id, type,
1049 		    offset + tslen, size);
1050 		break;
1051 
1052 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1053 	case GOT_OBJ_TYPE_REF_DELTA:
1054 		err = open_delta_object(obj, repo, packidx, path_packfile,
1055 		    pack->packfile, id, offset, tslen, type, size);
1056 		break;
1057 
1058 	default:
1059 		err = got_error(GOT_ERR_NOT_IMPL);
1060 		goto done;
1061 	}
1062 done:
1063 	free(path_packfile);
1064 	return err;
1065 }
1066 
1067 const struct got_error *
1068 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
1069     struct got_repository *repo)
1070 {
1071 	const struct got_error *err = NULL;
1072 	struct got_packidx_v2_hdr *packidx = NULL;
1073 	int idx;
1074 
1075 	err = search_packidx(&packidx, &idx, repo, id);
1076 	if (err)
1077 		return err;
1078 
1079 	err = open_packed_object(obj, repo, packidx, idx, id);
1080 	if (err)
1081 		return err;
1082 
1083 	err = cache_pack(NULL, (*obj)->path_packfile, packidx, repo);
1084 	got_packidx_close(packidx);
1085 	return err;
1086 }
1087 
1088 static const struct got_error *
1089 get_delta_sizes(uint64_t *base_size, uint64_t *result_size,
1090     struct got_delta *delta, FILE *packfile)
1091 {
1092 	const struct got_error *err;
1093 	uint8_t *delta_buf = NULL;
1094 	size_t delta_len = 0;
1095 
1096 	if (fseeko(packfile, delta->data_offset, SEEK_SET) != 0) {
1097 		err = got_error_from_errno();
1098 		return err;
1099 	}
1100 
1101 	err = got_inflate_to_mem(&delta_buf, &delta_len, packfile);
1102 	if (err)
1103 		return err;
1104 
1105 	err = got_delta_get_sizes(base_size, result_size, delta_buf, delta_len);
1106 	free(delta_buf);
1107 	return err;
1108 }
1109 
1110 static const struct got_error *
1111 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
1112     FILE *packfile)
1113 {
1114 	struct got_delta *delta;
1115 	uint64_t base_size = 0, result_size = 0;
1116 
1117 	*max_size = 0;
1118 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
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 			const struct got_error *err;
1125 			err = get_delta_sizes(&base_size, &result_size, delta,
1126 			    packfile);
1127 			if (err)
1128 				return err;
1129 		} else
1130 			base_size = delta->size;
1131 		if (base_size > *max_size)
1132 			*max_size = base_size;
1133 		if (result_size > *max_size)
1134 			*max_size = result_size;
1135 	}
1136 
1137 	return NULL;
1138 }
1139 
1140 void
1141 clear_delta_cache_entry(struct got_delta_cache_entry *entry)
1142 {
1143 	entry->data_offset = 0;
1144 	free(entry->delta_buf);
1145 	entry->delta_buf = NULL;
1146 	entry->delta_len = 0;
1147 }
1148 
1149 const struct got_error *
1150 cache_delta(off_t data_offset, uint8_t *delta_buf, size_t delta_len,
1151     struct got_pack *pack)
1152 {
1153 	int i;
1154 	struct got_delta_cache *cache = &pack->delta_cache;
1155 	struct got_delta_cache_entry *entry;
1156 
1157 	if (cache->nentries == nitems(cache->deltas)) {
1158 		entry = &cache->deltas[cache->nentries - 1];
1159 		clear_delta_cache_entry(entry);
1160 		cache->nentries--;
1161 		memmove(&cache->deltas[1], &cache->deltas[0],
1162 		    sizeof(cache->deltas) - sizeof(cache->deltas[0]));
1163 		i = 0;
1164 	} else
1165 		i = cache->nentries;
1166 
1167 	entry = &cache->deltas[i];
1168 	entry->data_offset = data_offset;
1169 	entry->delta_buf = delta_buf;
1170 	entry->delta_len = delta_len;
1171 	cache->nentries++;
1172 	return NULL;
1173 }
1174 
1175 void
1176 get_cached_delta(uint8_t **delta_buf, size_t *delta_len, off_t data_offset,
1177     struct got_pack *pack)
1178 {
1179 	struct got_delta_cache_entry *entry;
1180 	int i;
1181 
1182 	*delta_buf = NULL;
1183 	*delta_len = 0;
1184 
1185 	for (i = 0; i < nitems(pack->delta_cache.deltas); i++) {
1186 		entry = &pack->delta_cache.deltas[i];
1187 		if (entry->data_offset == 0)
1188 			break;
1189 		if (entry->data_offset == data_offset) {
1190 			*delta_buf = entry->delta_buf;
1191 			*delta_len = entry->delta_len;
1192 			break;
1193 		}
1194 	}
1195 }
1196 
1197 static const struct got_error *
1198 dump_delta_chain_to_file(size_t *result_size, struct got_delta_chain *deltas,
1199     FILE *outfile, struct got_pack *pack, struct got_repository *repo)
1200 {
1201 	const struct got_error *err = NULL;
1202 	struct got_delta *delta;
1203 	FILE *base_file = NULL, *accum_file = NULL;
1204 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1205 	size_t accum_size = 0;
1206 	uint64_t max_size;
1207 	int n = 0;
1208 
1209 	*result_size = 0;
1210 
1211 	if (SIMPLEQ_EMPTY(&deltas->entries))
1212 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1213 
1214 	/* We process small enough files entirely in memory for speed. */
1215 	err = get_delta_chain_max_size(&max_size, deltas, pack->packfile);
1216 	if (err)
1217 		return err;
1218 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1219 		accum_buf = malloc(max_size);
1220 		if (accum_buf == NULL)
1221 			return got_error(GOT_ERR_NO_MEM);
1222 	} else {
1223 		base_file = got_opentemp();
1224 		if (base_file == NULL)
1225 			return got_error_from_errno();
1226 
1227 		accum_file = got_opentemp();
1228 		if (accum_file == NULL) {
1229 			err = got_error_from_errno();
1230 			fclose(base_file);
1231 			return err;
1232 		}
1233 	}
1234 
1235 	/* Deltas are ordered in ascending order. */
1236 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1237 		uint8_t *delta_buf = NULL;
1238 		size_t delta_len = 0;
1239 
1240 		if (n == 0) {
1241 			size_t base_len;
1242 
1243 			/* Plain object types are the delta base. */
1244 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1245 			    delta->type != GOT_OBJ_TYPE_TREE &&
1246 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1247 			    delta->type != GOT_OBJ_TYPE_TAG) {
1248 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1249 				goto done;
1250 			}
1251 
1252 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1253 			    SEEK_SET) != 0) {
1254 				err = got_error_from_errno();
1255 				goto done;
1256 			}
1257 			if (base_file)
1258 				err = got_inflate_to_file(&base_len,
1259 				    pack->packfile, base_file);
1260 			else {
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(GOT_ERR_NO_MEM);
1268 						goto done;
1269 					}
1270 					base_buf = p;
1271 				}
1272 			}
1273 			if (err)
1274 				goto done;
1275 			n++;
1276 			if (base_file)
1277 				rewind(base_file);
1278 			continue;
1279 		}
1280 
1281 		get_cached_delta(&delta_buf, &delta_len, delta->data_offset,
1282 		    pack);
1283 		if (delta_buf == NULL) {
1284 			if (fseeko(pack->packfile, delta->data_offset, SEEK_SET)
1285 			    != 0) {
1286 				err = got_error_from_errno();
1287 				goto done;
1288 			}
1289 
1290 			/* Delta streams should always fit in memory. */
1291 			err = got_inflate_to_mem(&delta_buf, &delta_len,
1292 			    pack->packfile);
1293 			if (err)
1294 				goto done;
1295 
1296 			err = cache_delta(delta->data_offset, delta_buf,
1297 			    delta_len, pack);
1298 			if (err)
1299 				goto done;
1300 		}
1301 		/* delta_buf is now cached */
1302 
1303 		if (base_buf) {
1304 			err = got_delta_apply_in_mem(base_buf, delta_buf,
1305 			    delta_len, accum_buf, &accum_size);
1306 			n++;
1307 		} else {
1308 			err = got_delta_apply(base_file, delta_buf, delta_len,
1309 			    /* Final delta application writes to output file. */
1310 			    ++n < deltas->nentries ? accum_file : outfile,
1311 			    &accum_size);
1312 		}
1313 		if (err)
1314 			goto done;
1315 
1316 		if (n < deltas->nentries) {
1317 			/* Accumulated delta becomes the new base. */
1318 			if (base_buf) {
1319 				uint8_t *tmp = accum_buf;
1320 				accum_buf = base_buf;
1321 				base_buf = tmp;
1322 			} else {
1323 				FILE *tmp = accum_file;
1324 				accum_file = base_file;
1325 				base_file = tmp;
1326 				rewind(base_file);
1327 				rewind(accum_file);
1328 			}
1329 		}
1330 	}
1331 
1332 done:
1333 	free(base_buf);
1334 	if (accum_buf) {
1335 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1336 		free(accum_buf);
1337 		if (len != accum_size)
1338 			return got_ferror(outfile, GOT_ERR_IO);
1339 	}
1340 	if (base_file)
1341 		fclose(base_file);
1342 	if (accum_file)
1343 		fclose(accum_file);
1344 	rewind(outfile);
1345 	if (err == NULL)
1346 		*result_size = accum_size;
1347 	return err;
1348 }
1349 
1350 static const struct got_error *
1351 dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1352     struct got_delta_chain *deltas, struct got_pack *pack,
1353     struct got_repository *repo)
1354 {
1355 	const struct got_error *err = NULL;
1356 	struct got_delta *delta;
1357 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1358 	size_t accum_size;
1359 	uint64_t max_size;
1360 	int n = 0;
1361 
1362 	*outbuf = NULL;
1363 	*outlen = 0;
1364 
1365 	if (SIMPLEQ_EMPTY(&deltas->entries))
1366 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1367 
1368 	err = get_delta_chain_max_size(&max_size, deltas, pack->packfile);
1369 	if (err)
1370 		return err;
1371 	accum_buf = malloc(max_size);
1372 	if (accum_buf == NULL)
1373 		return got_error(GOT_ERR_NO_MEM);
1374 
1375 	/* Deltas are ordered in ascending order. */
1376 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1377 		uint8_t *delta_buf = NULL;
1378 		size_t delta_len = 0;
1379 
1380 		if (n == 0) {
1381 			size_t base_len;
1382 
1383 			/* Plain object types are the delta base. */
1384 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1385 			    delta->type != GOT_OBJ_TYPE_TREE &&
1386 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1387 			    delta->type != GOT_OBJ_TYPE_TAG) {
1388 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1389 				goto done;
1390 			}
1391 
1392 			if (fseeko(pack->packfile, delta->offset + delta->tslen,
1393 			    SEEK_SET) != 0) {
1394 				err = got_error_from_errno();
1395 				goto done;
1396 			}
1397 			err = got_inflate_to_mem(&base_buf, &base_len,
1398 			    pack->packfile);
1399 			if (base_len < max_size) {
1400 				uint8_t *p;
1401 				p = reallocarray(base_buf, 1, max_size);
1402 				if (p == NULL) {
1403 					err = got_error(GOT_ERR_NO_MEM);
1404 					goto done;
1405 				}
1406 				base_buf = p;
1407 			}
1408 			if (err)
1409 				goto done;
1410 			n++;
1411 			continue;
1412 		}
1413 
1414 		get_cached_delta(&delta_buf, &delta_len, delta->data_offset,
1415 		    pack);
1416 		if (delta_buf == NULL) {
1417 			if (fseeko(pack->packfile, delta->data_offset, SEEK_SET)
1418 			    != 0) {
1419 				err = got_error_from_errno();
1420 				goto done;
1421 			}
1422 
1423 			/* Delta streams should always fit in memory. */
1424 			err = got_inflate_to_mem(&delta_buf, &delta_len,
1425 			    pack->packfile);
1426 			if (err)
1427 				goto done;
1428 
1429 			err = cache_delta(delta->data_offset, delta_buf,
1430 			    delta_len, pack);
1431 			if (err)
1432 				goto done;
1433 		}
1434 		/* delta_buf is now cached */
1435 
1436 		err = got_delta_apply_in_mem(base_buf, delta_buf,
1437 		    delta_len, accum_buf, &accum_size);
1438 		n++;
1439 		if (err)
1440 			goto done;
1441 
1442 		if (n < deltas->nentries) {
1443 			/* Accumulated delta becomes the new base. */
1444 			uint8_t *tmp = accum_buf;
1445 			accum_buf = base_buf;
1446 			base_buf = tmp;
1447 		}
1448 	}
1449 
1450 done:
1451 	free(base_buf);
1452 	if (err) {
1453 		free(accum_buf);
1454 		*outbuf = NULL;
1455 		*outlen = 0;
1456 	} else {
1457 		*outbuf = accum_buf;
1458 		*outlen = accum_size;
1459 	}
1460 	return err;
1461 }
1462 
1463 const struct got_error *
1464 got_packfile_extract_object(FILE **f, struct got_object *obj,
1465     struct got_repository *repo)
1466 {
1467 	const struct got_error *err = NULL;
1468 	struct got_pack *pack;
1469 
1470 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1471 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1472 
1473 	*f = got_opentemp();
1474 	if (*f == NULL) {
1475 		err = got_error(GOT_ERR_FILE_OPEN);
1476 		goto done;
1477 	}
1478 
1479 	pack = get_cached_pack(obj->path_packfile, repo);
1480 	if (pack == NULL) {
1481 		err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1482 		if (err)
1483 			goto done;
1484 	}
1485 
1486 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1487 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1488 			err = got_error_from_errno();
1489 			goto done;
1490 		}
1491 
1492 		err = got_inflate_to_file(&obj->size, pack->packfile, *f);
1493 	} else
1494 		err = dump_delta_chain_to_file(&obj->size, &obj->deltas, *f,
1495 		    pack, repo);
1496 done:
1497 	if (err && *f)
1498 		fclose(*f);
1499 	return err;
1500 }
1501 
1502 const struct got_error *
1503 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1504     struct got_object *obj, struct got_repository *repo)
1505 {
1506 	const struct got_error *err = NULL;
1507 	FILE *packfile = NULL;
1508 	struct got_pack *pack;
1509 
1510 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1511 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1512 
1513 	pack = get_cached_pack(obj->path_packfile, repo);
1514 	if (pack == NULL) {
1515 		err = cache_pack(&pack, obj->path_packfile, NULL, repo);
1516 		if (err)
1517 			goto done;
1518 	}
1519 
1520 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1521 		if (fseeko(pack->packfile, obj->pack_offset, SEEK_SET) != 0) {
1522 			err = got_error_from_errno();
1523 			goto done;
1524 		}
1525 
1526 		err = got_inflate_to_mem(buf, len, pack->packfile);
1527 	} else
1528 		err = dump_delta_chain_to_mem(buf, len, &obj->deltas, pack,
1529 		    repo);
1530 done:
1531 	if (packfile)
1532 		fclose(packfile);
1533 	return err;
1534 }