1 /*
2  * Copyright (c) 2018, 2019, 2020 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/uio.h>
21 #include <sys/mman.h>
22 #include <sys/resource.h>
23 #include <sys/socket.h>
24 
25 #include <fcntl.h>
26 #include <errno.h>
27 #include <stdio.h>
28 #include <stdint.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <limits.h>
32 #include <sha1.h>
33 #include <sha2.h>
34 #include <endian.h>
35 #include <unistd.h>
36 #include <zlib.h>
37 #include <imsg.h>
38 
39 #include "got_error.h"
40 #include "got_object.h"
41 #include "got_path.h"
42 
43 #include "got_lib_hash.h"
44 #include "got_lib_delta.h"
45 #include "got_lib_delta_cache.h"
46 #include "got_lib_inflate.h"
47 #include "got_lib_object.h"
48 #include "got_lib_object_parse.h"
49 #include "got_lib_privsep.h"
50 #include "got_lib_pack.h"
51 
52 #ifndef nitems
53 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
54 #endif
55 
56 #ifndef MIN
57 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
58 #endif
59 
60 static const struct got_error *
61 verify_fanout_table(uint32_t *fanout_table)
62 {
63 	int i;
64 
65 	for (i = 0; i < 0xff - 1; i++) {
66 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
67 			return got_error(GOT_ERR_BAD_PACKIDX);
68 	}
69 
70 	return NULL;
71 }
72 
73 const struct got_error *
74 got_packidx_init_hdr(struct got_packidx *p, int verify, off_t packfile_size)
75 {
76 	const struct got_error *err = NULL;
77 	struct got_packidx_v2_hdr *h;
78 	struct got_hash ctx;
79 	uint8_t hash[GOT_OBJECT_ID_MAXLEN];
80 	size_t nobj, len_fanout, len_ids, offset, remain;
81 	ssize_t n;
82 	int i;
83 
84 	got_hash_init(&ctx, p->algo);
85 
86 	h = &p->hdr;
87 	offset = 0;
88 	remain = p->len;
89 
90 	if (remain < sizeof(*h->magic)) {
91 		err = got_error(GOT_ERR_BAD_PACKIDX);
92 		goto done;
93 	}
94 	if (p->map)
95 		h->magic = (uint32_t *)(p->map + offset);
96 	else {
97 		h->magic = malloc(sizeof(*h->magic));
98 		if (h->magic == NULL) {
99 			err = got_error_from_errno("malloc");
100 			goto done;
101 		}
102 		n = read(p->fd, h->magic, sizeof(*h->magic));
103 		if (n < 0) {
104 			err = got_error_from_errno("read");
105 			goto done;
106 		} else if (n != sizeof(*h->magic)) {
107 			err = got_error(GOT_ERR_BAD_PACKIDX);
108 			goto done;
109 		}
110 	}
111 	if (*h->magic != htobe32(GOT_PACKIDX_V2_MAGIC)) {
112 		err = got_error(GOT_ERR_BAD_PACKIDX);
113 		goto done;
114 	}
115 	offset += sizeof(*h->magic);
116 	remain -= sizeof(*h->magic);
117 
118 	if (verify)
119 		got_hash_update(&ctx, h->magic, sizeof(*h->magic));
120 
121 	if (remain < sizeof(*h->version)) {
122 		err = got_error(GOT_ERR_BAD_PACKIDX);
123 		goto done;
124 	}
125 	if (p->map)
126 		h->version = (uint32_t *)(p->map + offset);
127 	else {
128 		h->version = malloc(sizeof(*h->version));
129 		if (h->version == NULL) {
130 			err = got_error_from_errno("malloc");
131 			goto done;
132 		}
133 		n = read(p->fd, h->version, sizeof(*h->version));
134 		if (n < 0) {
135 			err = got_error_from_errno("read");
136 			goto done;
137 		} else if (n != sizeof(*h->version)) {
138 			err = got_error(GOT_ERR_BAD_PACKIDX);
139 			goto done;
140 		}
141 	}
142 	if (*h->version != htobe32(GOT_PACKIDX_VERSION)) {
143 		err = got_error(GOT_ERR_BAD_PACKIDX);
144 		goto done;
145 	}
146 	offset += sizeof(*h->version);
147 	remain -= sizeof(*h->version);
148 
149 	if (verify)
150 		got_hash_update(&ctx, h->version, sizeof(*h->version));
151 
152 	len_fanout =
153 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
154 	if (remain < len_fanout) {
155 		err = got_error(GOT_ERR_BAD_PACKIDX);
156 		goto done;
157 	}
158 	if (p->map)
159 		h->fanout_table = (uint32_t *)(p->map + offset);
160 	else {
161 		h->fanout_table = malloc(len_fanout);
162 		if (h->fanout_table == NULL) {
163 			err = got_error_from_errno("malloc");
164 			goto done;
165 		}
166 		n = read(p->fd, h->fanout_table, len_fanout);
167 		if (n < 0) {
168 			err = got_error_from_errno("read");
169 			goto done;
170 		} else if (n != len_fanout) {
171 			err = got_error(GOT_ERR_BAD_PACKIDX);
172 			goto done;
173 		}
174 	}
175 	err = verify_fanout_table(h->fanout_table);
176 	if (err)
177 		goto done;
178 	if (verify)
179 		got_hash_update(&ctx, h->fanout_table, len_fanout);
180 	offset += len_fanout;
181 	remain -= len_fanout;
182 
183 	nobj = be32toh(h->fanout_table[0xff]);
184 	len_ids = nobj * got_hash_digest_length(p->algo);
185 	if (len_ids <= nobj || len_ids > remain) {
186 		err = got_error(GOT_ERR_BAD_PACKIDX);
187 		goto done;
188 	}
189 	if (p->map)
190 		h->sorted_ids = p->map + offset;
191 	else {
192 		h->sorted_ids = malloc(len_ids);
193 		if (h->sorted_ids == NULL) {
194 			err = got_error(GOT_ERR_BAD_PACKIDX);
195 			goto done;
196 		}
197 		n = read(p->fd, h->sorted_ids, len_ids);
198 		if (n < 0)
199 			err = got_error_from_errno("read");
200 		else if (n != len_ids) {
201 			err = got_error(GOT_ERR_BAD_PACKIDX);
202 			goto done;
203 		}
204 	}
205 	if (verify)
206 		got_hash_update(&ctx, h->sorted_ids, len_ids);
207 	offset += len_ids;
208 	remain -= len_ids;
209 
210 	if (remain < nobj * sizeof(*h->crc32)) {
211 		err = got_error(GOT_ERR_BAD_PACKIDX);
212 		goto done;
213 	}
214 	if (p->map)
215 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
216 	else {
217 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
218 		if (h->crc32 == NULL) {
219 			err = got_error_from_errno("malloc");
220 			goto done;
221 		}
222 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
223 		if (n < 0)
224 			err = got_error_from_errno("read");
225 		else if (n != nobj * sizeof(*h->crc32)) {
226 			err = got_error(GOT_ERR_BAD_PACKIDX);
227 			goto done;
228 		}
229 	}
230 	if (verify)
231 		got_hash_update(&ctx, h->crc32, nobj * sizeof(*h->crc32));
232 	remain -= nobj * sizeof(*h->crc32);
233 	offset += nobj * sizeof(*h->crc32);
234 
235 	if (remain < nobj * sizeof(*h->offsets)) {
236 		err = got_error(GOT_ERR_BAD_PACKIDX);
237 		goto done;
238 	}
239 	if (p->map)
240 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
241 	else {
242 		h->offsets = malloc(nobj * sizeof(*h->offsets));
243 		if (h->offsets == NULL) {
244 			err = got_error_from_errno("malloc");
245 			goto done;
246 		}
247 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
248 		if (n < 0)
249 			err = got_error_from_errno("read");
250 		else if (n != nobj * sizeof(*h->offsets)) {
251 			err = got_error(GOT_ERR_BAD_PACKIDX);
252 			goto done;
253 		}
254 	}
255 	if (verify)
256 		got_hash_update(&ctx, h->offsets, nobj * sizeof(*h->offsets));
257 	remain -= nobj * sizeof(*h->offsets);
258 	offset += nobj * sizeof(*h->offsets);
259 
260 	/* Large file offsets are contained only in files > 2GB. */
261 	if (verify || packfile_size > 0x7fffffff) {
262 		for (i = 0; i < nobj; i++) {
263 			uint32_t o = h->offsets[i];
264 			if (o & htobe32(GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX))
265 				p->nlargeobj++;
266 		}
267 	}
268 	if (p->nlargeobj == 0)
269 		goto checksum;
270 	else if (packfile_size <= 0x7fffffff) {
271 		err = got_error(GOT_ERR_BAD_PACKIDX);
272 		goto done;
273 	}
274 
275 	if (remain < p->nlargeobj * sizeof(*h->large_offsets)) {
276 		err = got_error(GOT_ERR_BAD_PACKIDX);
277 		goto done;
278 	}
279 	if (p->map)
280 		h->large_offsets = (uint64_t *)((uint8_t*)(p->map + offset));
281 	else {
282 		h->large_offsets = malloc(p->nlargeobj *
283 		    sizeof(*h->large_offsets));
284 		if (h->large_offsets == NULL) {
285 			err = got_error_from_errno("malloc");
286 			goto done;
287 		}
288 		n = read(p->fd, h->large_offsets,
289 		    p->nlargeobj * sizeof(*h->large_offsets));
290 		if (n < 0)
291 			err = got_error_from_errno("read");
292 		else if (n != p->nlargeobj * sizeof(*h->large_offsets)) {
293 			err = got_error(GOT_ERR_BAD_PACKIDX);
294 			goto done;
295 		}
296 	}
297 	if (verify)
298 		got_hash_update(&ctx, h->large_offsets,
299 		    p->nlargeobj * sizeof(*h->large_offsets));
300 	remain -= p->nlargeobj * sizeof(*h->large_offsets);
301 	offset += p->nlargeobj * sizeof(*h->large_offsets);
302 
303 checksum:
304 	if (remain < 2 * got_hash_digest_length(p->algo)) {
305 		err = got_error(GOT_ERR_BAD_PACKIDX);
306 		goto done;
307 	}
308 	if (p->map) {
309 		const uint8_t *base = p->map + offset;
310 
311 		memcpy(&h->trailer.packfile_hash, base,
312 		    got_hash_digest_length(p->algo));
313 		base += got_hash_digest_length(p->algo);
314 		memcpy(&h->trailer.packidx_hash, base,
315 		    got_hash_digest_length(p->algo));
316 	} else {
317 		err = NULL;
318 		n = read(p->fd, &h->trailer.packfile_hash,
319 		    got_hash_digest_length(p->algo));
320 		if (n < 0)
321 			err = got_error_from_errno("read");
322 		else if (n != got_hash_digest_length(p->algo))
323 			err = got_error(GOT_ERR_BAD_PACKIDX);
324 		if (err)
325 			goto done;
326 
327 		n = read(p->fd, &h->trailer.packidx_hash,
328 		    got_hash_digest_length(p->algo));
329 		if (n < 0)
330 			err = got_error_from_errno("read");
331 		else if (n != got_hash_digest_length(p->algo))
332 			err = got_error(GOT_ERR_BAD_PACKIDX);
333 		if (err)
334 			goto done;
335 	}
336 	if (verify) {
337 		got_hash_update(&ctx, h->trailer.packfile_hash,
338 		    got_hash_digest_length(p->algo));
339 		got_hash_final(&ctx, hash);
340 		if (got_hash_cmp(&ctx, hash, h->trailer.packidx_hash) != 0)
341 			err = got_error(GOT_ERR_PACKIDX_CSUM);
342 	}
343 done:
344 	return err;
345 }
346 
347 const struct got_error *
348 got_packidx_open(struct got_packidx **packidx,
349     int dir_fd, const char *relpath, int verify,
350     enum got_hash_algorithm algo)
351 {
352 	const struct got_error *err = NULL;
353 	struct got_packidx *p = NULL;
354 	char *pack_relpath;
355 	struct stat idx_sb, pack_sb;
356 
357 	*packidx = NULL;
358 
359 	err = got_packidx_get_packfile_path(&pack_relpath, relpath);
360 	if (err)
361 		return err;
362 
363 	/*
364 	 * Ensure that a corresponding pack file exists.
365 	 * Some Git repositories have this problem. Git seems to ignore
366 	 * the existence of lonely pack index files but we do not.
367 	 */
368 	if (fstatat(dir_fd, pack_relpath, &pack_sb, 0) == -1) {
369 		if (errno == ENOENT) {
370 			err = got_error_fmt(GOT_ERR_LONELY_PACKIDX,
371 			    "%s", relpath);
372 		} else
373 			err = got_error_from_errno2("fstatat", pack_relpath);
374 		goto done;
375 	}
376 
377 	p = calloc(1, sizeof(*p));
378 	if (p == NULL) {
379 		err = got_error_from_errno("calloc");
380 		goto done;
381 	}
382 
383 	p->algo = algo;
384 
385 	p->fd = openat(dir_fd, relpath, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
386 	if (p->fd == -1) {
387 		err = got_error_from_errno2("openat", relpath);
388 		goto done;
389 	}
390 
391 	if (fstat(p->fd, &idx_sb) != 0) {
392 		err = got_error_from_errno2("fstat", relpath);
393 		goto done;
394 	}
395 	p->len = idx_sb.st_size;
396 	if (p->len < sizeof(p->hdr)) {
397 		err = got_error(GOT_ERR_BAD_PACKIDX);
398 		goto done;
399 	}
400 
401 	p->path_packidx = strdup(relpath);
402 	if (p->path_packidx == NULL) {
403 		err = got_error_from_errno("strdup");
404 		goto done;
405 	}
406 
407 #ifndef GOT_PACK_NO_MMAP
408 	if (p->len > 0 && p->len <= SIZE_MAX) {
409 		p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
410 		if (p->map == MAP_FAILED) {
411 			if (errno != ENOMEM) {
412 				err = got_error_from_errno("mmap");
413 				goto done;
414 			}
415 			p->map = NULL; /* fall back to read(2) */
416 		}
417 	}
418 #endif
419 
420 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
421 done:
422 	if (err) {
423 		if (p)
424 			got_packidx_close(p);
425 	} else
426 		*packidx = p;
427 	free(pack_relpath);
428 	return err;
429 }
430 
431 const struct got_error *
432 got_packidx_close(struct got_packidx *packidx)
433 {
434 	const struct got_error *err = NULL;
435 
436 	free(packidx->path_packidx);
437 	if (packidx->map) {
438 		if (munmap(packidx->map, packidx->len) == -1)
439 			err = got_error_from_errno("munmap");
440 	} else {
441 		free(packidx->hdr.magic);
442 		free(packidx->hdr.version);
443 		free(packidx->hdr.fanout_table);
444 		free(packidx->hdr.sorted_ids);
445 		free(packidx->hdr.crc32);
446 		free(packidx->hdr.offsets);
447 		free(packidx->hdr.large_offsets);
448 	}
449 	if (close(packidx->fd) == -1 && err == NULL)
450 		err = got_error_from_errno("close");
451 	free(packidx->sorted_offsets);
452 	free(packidx->sorted_large_offsets);
453 	free(packidx);
454 
455 	return err;
456 }
457 
458 static const struct got_error *
459 packfile_path(char **path_packfile, const char *path_packidx)
460 {
461 	size_t size;
462 
463 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
464 	size = strlen(path_packidx) + 2;
465 	if (size < GOT_PACKFILE_NAMELEN + 1)
466 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
467 
468 	*path_packfile = malloc(size);
469 	if (*path_packfile == NULL)
470 		return got_error_from_errno("malloc");
471 
472 	/* Copy up to and excluding ".idx". */
473 	if (strlcpy(*path_packfile, path_packidx,
474 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
475 		return got_error(GOT_ERR_NO_SPACE);
476 
477 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
478 		return got_error(GOT_ERR_NO_SPACE);
479 
480 	return NULL;
481 }
482 
483 const struct got_error *
484 got_packidx_get_packfile_path(char **path_packfile, const char *path)
485 {
486 	const struct got_error *err;
487 
488 	err = packfile_path(path_packfile, path);
489 	if (err) {
490 		fprintf(stderr, "%s: failed for path %s: %s\n",
491 		    __func__, path, err->msg);
492 	}
493 	return err;
494 }
495 
496 off_t
497 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
498 {
499 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
500 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
501 		uint64_t loffset;
502 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
503 		if (idx < 0 || idx >= packidx->nlargeobj ||
504 		    packidx->hdr.large_offsets == NULL)
505 			return -1;
506 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
507 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
508 	}
509 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
510 }
511 
512 int
513 got_packidx_get_object_idx(struct got_packidx *packidx,
514     struct got_object_id *id)
515 {
516 	u_int8_t id0 = id->hash[0];
517 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
518 	int left = 0, right = totobj - 1;
519 	size_t idlen;
520 
521 	idlen = got_hash_digest_length(packidx->algo);
522 
523 	if (id0 > 0)
524 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
525 
526 	while (left <= right) {
527 		struct got_packidx_object_id *oid;
528 		int i, cmp;
529 
530 		i = ((left + right) / 2);
531 		oid = packidx->hdr.sorted_ids + idlen * i;
532 		cmp = memcmp(id->hash, oid->hash, idlen);
533 		if (cmp == 0)
534 			return i;
535 		else if (cmp > 0)
536 			left = i + 1;
537 		else if (cmp < 0)
538 			right = i - 1;
539 	}
540 
541 	return -1;
542 }
543 
544 static int
545 offset_cmp(const void *pa, const void *pb)
546 {
547 	const struct got_pack_offset_index *a, *b;
548 
549 	a = (const struct got_pack_offset_index *)pa;
550 	b = (const struct got_pack_offset_index *)pb;
551 
552 	if (a->offset < b->offset)
553 		return -1;
554 	else if (a->offset > b->offset)
555 		return 1;
556 
557 	return 0;
558 }
559 
560 static int
561 large_offset_cmp(const void *pa, const void *pb)
562 {
563 	const struct got_pack_large_offset_index *a, *b;
564 
565 	a = (const struct got_pack_large_offset_index *)pa;
566 	b = (const struct got_pack_large_offset_index *)pb;
567 
568 	if (a->offset < b->offset)
569 		return -1;
570 	else if (a->offset > b->offset)
571 		return 1;
572 
573 	return 0;
574 }
575 
576 static const struct got_error *
577 build_offset_index(struct got_packidx *p)
578 {
579 	uint32_t nobj = be32toh(p->hdr.fanout_table[0xff]);
580 	unsigned int i, j, k;
581 
582 	p->sorted_offsets = calloc(nobj - p->nlargeobj,
583 	    sizeof(p->sorted_offsets[0]));
584 	if (p->sorted_offsets == NULL)
585 		return got_error_from_errno("calloc");
586 
587 	if (p->nlargeobj > 0) {
588 		p->sorted_large_offsets = calloc(p->nlargeobj,
589 		    sizeof(p->sorted_large_offsets[0]));
590 		if (p->sorted_large_offsets == NULL)
591 			return got_error_from_errno("calloc");
592 	}
593 
594 	j = 0;
595 	k = 0;
596 	for (i = 0; i < nobj; i++) {
597 		uint32_t offset = be32toh(p->hdr.offsets[i]);
598 		if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
599 			uint64_t loffset;
600 			uint32_t idx;
601 			idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
602 			if (idx >= p->nlargeobj ||
603 			    p->nlargeobj == 0 ||
604 			    p->hdr.large_offsets == NULL)
605 				return got_error(GOT_ERR_BAD_PACKIDX);
606 			loffset = be64toh(p->hdr.large_offsets[idx]);
607 			p->sorted_large_offsets[j].offset = loffset;
608 			p->sorted_large_offsets[j].idx = i;
609 			j++;
610 		} else {
611 			p->sorted_offsets[k].offset = offset;
612 			p->sorted_offsets[k].idx = i;
613 			k++;
614 		}
615 	}
616 	if (j != p->nlargeobj || k != nobj - p->nlargeobj)
617 		return got_error(GOT_ERR_BAD_PACKIDX);
618 
619 	qsort(p->sorted_offsets, nobj - p->nlargeobj,
620 	    sizeof(p->sorted_offsets[0]), offset_cmp);
621 
622 	if (p->sorted_large_offsets)
623 		qsort(p->sorted_large_offsets, p->nlargeobj,
624 		    sizeof(p->sorted_large_offsets[0]), large_offset_cmp);
625 
626 	return NULL;
627 }
628 
629 const struct got_error *
630 got_packidx_get_offset_idx(int *idx, struct got_packidx *packidx, off_t offset)
631 {
632 	const struct got_error *err;
633 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
634 	int i, left, right;
635 
636 	*idx = -1;
637 
638 	if (packidx->sorted_offsets == NULL) {
639 		err = build_offset_index(packidx);
640 		if (err)
641 			return err;
642 	}
643 
644 	if (offset >= 0x7fffffff) {
645 		uint64_t lo;
646 		left = 0, right = packidx->nlargeobj - 1;
647 		while (left <= right) {
648 			i = ((left + right) / 2);
649 			lo = packidx->sorted_large_offsets[i].offset;
650 			if (lo == offset) {
651 				*idx = packidx->sorted_large_offsets[i].idx;
652 				break;
653 			} else if (offset > lo)
654 				left = i + 1;
655 			else if (offset < lo)
656 				right = i - 1;
657 		}
658 	} else {
659 		uint32_t o;
660 		left = 0, right = totobj - packidx->nlargeobj - 1;
661 		while (left <= right) {
662 			i = ((left + right) / 2);
663 			o = packidx->sorted_offsets[i].offset;
664 			if (o == offset) {
665 				*idx = packidx->sorted_offsets[i].idx;
666 				break;
667 			} else if (offset > o)
668 				left = i + 1;
669 			else if (offset < o)
670 				right = i - 1;
671 		}
672 	}
673 
674 	return NULL;
675 }
676 
677 const struct got_error *
678 got_packidx_get_object_id(struct got_object_id *id,
679     struct got_packidx *packidx, int idx)
680 {
681 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
682 	struct got_packidx_object_id *oid;
683 	size_t idlen;
684 
685 	idlen = got_hash_digest_length(packidx->algo);
686 
687 	if (idx < 0 || idx >= totobj)
688 		return got_error(GOT_ERR_NO_OBJ);
689 
690 	oid = packidx->hdr.sorted_ids + (idx * idlen);
691 
692 	memset(id, 0, sizeof(*id));
693 	memcpy(id->hash, oid->hash, idlen);
694 	return NULL;
695 }
696 
697 const struct got_error *
698 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
699     struct got_packidx *packidx, const char *id_str_prefix)
700 {
701 	const struct got_error *err = NULL;
702 	u_int8_t id0;
703 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
704 	char hex[3];
705 	size_t idlen, prefix_len = strlen(id_str_prefix);
706 	struct got_packidx_object_id *oid;
707 	uint32_t i = 0;
708 
709 	idlen = got_hash_digest_length(packidx->algo);
710 
711 	STAILQ_INIT(matched_ids);
712 
713 	if (prefix_len < 2)
714 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
715 
716 	hex[0] = id_str_prefix[0];
717 	hex[1] = id_str_prefix[1];
718 	hex[2] = '\0';
719 	if (!got_parse_xdigit(&id0, hex))
720 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
721 
722 	if (id0 > 0)
723 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
724 	oid = packidx->hdr.sorted_ids + i * idlen;
725 	while (i < totobj && oid->hash[0] == id0) {
726 		char id_str[GOT_OBJECT_ID_HEX_MAXLEN];
727 		struct got_object_qid *qid;
728 		int cmp;
729 
730 		if (!got_hash_digest_to_str(oid->hash, id_str, sizeof(id_str),
731 		    packidx->algo))
732 		        return got_error(GOT_ERR_NO_SPACE);
733 
734 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
735 		if (cmp < 0) {
736 			i++;
737 			oid = packidx->hdr.sorted_ids + i * idlen;
738 			continue;
739 		} else if (cmp > 0)
740 			break;
741 
742 		err = got_object_qid_alloc_partial(&qid);
743 		if (err)
744 			break;
745 		memcpy(qid->id.hash, oid->hash, idlen);
746 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
747 
748 		i++;
749 		oid = packidx->hdr.sorted_ids + i * idlen;
750 	}
751 
752 	if (err)
753 		got_object_id_queue_free(matched_ids);
754 	return err;
755 }
756 
757 static void
758 set_max_datasize(void)
759 {
760 	struct rlimit rl;
761 
762 	if (getrlimit(RLIMIT_DATA, &rl) != 0)
763 		return;
764 
765 	rl.rlim_cur = rl.rlim_max;
766 	setrlimit(RLIMIT_DATA, &rl);
767 }
768 
769 const struct got_error *
770 got_pack_start_privsep_child(struct got_pack *pack, struct got_packidx *packidx)
771 {
772 	const struct got_error *err = NULL;
773 	int imsg_fds[2];
774 	pid_t pid;
775 	struct imsgbuf *ibuf;
776 
777 	ibuf = calloc(1, sizeof(*ibuf));
778 	if (ibuf == NULL)
779 		return got_error_from_errno("calloc");
780 
781 	pack->privsep_child = calloc(1, sizeof(*pack->privsep_child));
782 	if (pack->privsep_child == NULL) {
783 		err = got_error_from_errno("calloc");
784 		free(ibuf);
785 		return err;
786 	}
787 	pack->child_has_tempfiles = 0;
788 	pack->child_has_delta_outfd = 0;
789 
790 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1) {
791 		err = got_error_from_errno("socketpair");
792 		goto done;
793 	}
794 
795 	pid = fork();
796 	if (pid == -1) {
797 		err = got_error_from_errno("fork");
798 		goto done;
799 	} else if (pid == 0) {
800 		set_max_datasize();
801 		got_privsep_exec_child(imsg_fds, GOT_PATH_PROG_READ_PACK,
802 		    pack->path_packfile);
803 		/* not reached */
804 	}
805 
806 	if (close(imsg_fds[1]) == -1)
807 		return got_error_from_errno("close");
808 	pack->privsep_child->imsg_fd = imsg_fds[0];
809 	pack->privsep_child->pid = pid;
810 	imsg_init(ibuf, imsg_fds[0]);
811 	pack->privsep_child->ibuf = ibuf;
812 
813 	err = got_privsep_init_pack_child(ibuf, pack, packidx);
814 	if (err) {
815 		const struct got_error *child_err;
816 		err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
817 		child_err = got_privsep_wait_for_child(
818 		    pack->privsep_child->pid);
819 		if (child_err && err == NULL)
820 			err = child_err;
821 	}
822 done:
823 	if (err) {
824 		free(ibuf);
825 		free(pack->privsep_child);
826 		pack->privsep_child = NULL;
827 	}
828 	return err;
829 }
830 
831 static const struct got_error *
832 pack_stop_privsep_child(struct got_pack *pack)
833 {
834 	const struct got_error *err = NULL, *close_err = NULL;
835 
836 	if (pack->privsep_child == NULL)
837 		return NULL;
838 
839 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
840 	if (err)
841 		return err;
842 	if (close(pack->privsep_child->imsg_fd) == -1)
843 		close_err = got_error_from_errno("close");
844 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
845 	if (close_err && err == NULL)
846 		err = close_err;
847 	imsg_clear(pack->privsep_child->ibuf);
848 	free(pack->privsep_child->ibuf);
849 	free(pack->privsep_child);
850 	pack->privsep_child = NULL;
851 	return err;
852 }
853 
854 const struct got_error *
855 got_pack_close(struct got_pack *pack)
856 {
857 	const struct got_error *err = NULL;
858 
859 	err = pack_stop_privsep_child(pack);
860 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
861 		err = got_error_from_errno("munmap");
862 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
863 		err = got_error_from_errno("close");
864 	pack->fd = -1;
865 	free(pack->path_packfile);
866 	pack->path_packfile = NULL;
867 	pack->filesize = 0;
868 	if (pack->delta_cache) {
869 		got_delta_cache_free(pack->delta_cache);
870 		pack->delta_cache = NULL;
871 	}
872 
873 	/*
874 	 * Leave accumfd and basefd alone. They are managed by the
875 	 * repository layer and can be reused.
876 	 */
877 
878 	return err;
879 }
880 
881 const struct got_error *
882 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
883     struct got_pack *pack, off_t offset)
884 {
885 	uint8_t t = 0;
886 	uint64_t s = 0;
887 	uint8_t sizeN;
888 	size_t mapoff = 0;
889 	int i = 0;
890 
891 	*len = 0;
892 
893 	if (offset >= pack->filesize)
894 		return got_error(GOT_ERR_PACK_OFFSET);
895 
896 	if (pack->map) {
897 		if (offset > SIZE_MAX) {
898 			return got_error_fmt(GOT_ERR_PACK_OFFSET,
899 			    "offset %lld overflows size_t",
900 			    (long long)offset);
901 		}
902 
903 		mapoff = (size_t)offset;
904 	} else {
905 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
906 			return got_error_from_errno("lseek");
907 	}
908 
909 	do {
910 		/* We do not support size values which don't fit in 64 bit. */
911 		if (i > 9)
912 			return got_error_fmt(GOT_ERR_OBJ_TOO_LARGE,
913 			    "packfile offset %lld", (long long)offset);
914 
915 		if (pack->map) {
916 			if (mapoff + sizeof(sizeN) >= pack->filesize)
917 				return got_error(GOT_ERR_BAD_PACKFILE);
918 			sizeN = *(pack->map + mapoff);
919 			mapoff += sizeof(sizeN);
920 		} else {
921 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
922 			if (n < 0)
923 				return got_error_from_errno("read");
924 			if (n != sizeof(sizeN))
925 				return got_error(GOT_ERR_BAD_PACKFILE);
926 		}
927 		*len += sizeof(sizeN);
928 
929 		if (i == 0) {
930 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
931 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
932 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
933 		} else {
934 			size_t shift = 4 + 7 * (i - 1);
935 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
936 		}
937 		i++;
938 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
939 
940 	*type = t;
941 	*size = s;
942 	return NULL;
943 }
944 
945 static const struct got_error *
946 open_plain_object(struct got_object **obj, struct got_object_id *id,
947     uint8_t type, off_t offset, size_t size, int idx)
948 {
949 	*obj = calloc(1, sizeof(**obj));
950 	if (*obj == NULL)
951 		return got_error_from_errno("calloc");
952 
953 	(*obj)->type = type;
954 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
955 	(*obj)->pack_idx = idx;
956 	(*obj)->hdrlen = 0;
957 	(*obj)->size = size;
958 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
959 	(*obj)->pack_offset = offset;
960 
961 	return NULL;
962 }
963 
964 static const struct got_error *
965 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
966     off_t delta_offset)
967 {
968 	int64_t o = 0;
969 	uint8_t offN;
970 	int i = 0;
971 
972 	*offset = 0;
973 	*len = 0;
974 
975 	do {
976 		/* We do not support offset values which don't fit in 64 bit. */
977 		if (i > 8)
978 			return got_error(GOT_ERR_NO_SPACE);
979 
980 		if (pack->map) {
981 			size_t mapoff;
982 
983 			if (delta_offset + *len > SIZE_MAX) {
984 				return got_error_fmt(GOT_ERR_PACK_OFFSET,
985 				    "mapoff %lld would overflow size_t",
986 				    (long long)delta_offset + *len);
987 			}
988 
989 			mapoff = (size_t)delta_offset + *len;
990 			if (mapoff + sizeof(offN) >= pack->filesize)
991 				return got_error(GOT_ERR_PACK_OFFSET);
992 			offN = *(pack->map + mapoff);
993 		} else {
994 			ssize_t n;
995 			n = read(pack->fd, &offN, sizeof(offN));
996 			if (n < 0)
997 				return got_error_from_errno("read");
998 			if (n != sizeof(offN))
999 				return got_error(GOT_ERR_BAD_PACKFILE);
1000 		}
1001 		*len += sizeof(offN);
1002 
1003 		if (i == 0)
1004 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
1005 		else {
1006 			o++;
1007 			o <<= 7;
1008 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
1009 		}
1010 		i++;
1011 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
1012 
1013 	*offset = o;
1014 	return NULL;
1015 }
1016 
1017 const struct got_error *
1018 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
1019     struct got_pack *pack, off_t offset, size_t tslen)
1020 {
1021 	const struct got_error *err;
1022 	int64_t negoffset;
1023 	size_t negofflen;
1024 
1025 	*len = 0;
1026 
1027 	err = parse_negative_offset(&negoffset, &negofflen, pack,
1028 	    offset + tslen);
1029 	if (err)
1030 		return err;
1031 
1032 	/* Compute the base object's offset (must be in the same pack file). */
1033 	*base_offset = (offset - negoffset);
1034 	if (*base_offset <= 0)
1035 		return got_error(GOT_ERR_BAD_PACKFILE);
1036 
1037 	*len = negofflen;
1038 	return NULL;
1039 }
1040 
1041 static const struct got_error *
1042 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
1043     size_t *delta_compressed_len, size_t delta_data_offset,
1044     struct got_pack *pack)
1045 {
1046 	const struct got_error *err = NULL;
1047 	size_t consumed = 0;
1048 
1049 	if (pack->map) {
1050 		if (delta_data_offset >= pack->filesize)
1051 			return got_error(GOT_ERR_PACK_OFFSET);
1052 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
1053 		    &consumed, NULL, pack->map, delta_data_offset,
1054 		    pack->filesize - delta_data_offset);
1055 		if (err)
1056 			return err;
1057 	} else {
1058 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
1059 			return got_error_from_errno("lseek");
1060 		err = got_inflate_to_mem_fd(delta_buf, delta_len,
1061 		    &consumed, NULL, 0, pack->fd);
1062 		if (err)
1063 			return err;
1064 	}
1065 
1066 	if (delta_compressed_len)
1067 		*delta_compressed_len = consumed;
1068 
1069 	return NULL;
1070 }
1071 
1072 static const struct got_error *
1073 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
1074     int delta_type, size_t delta_size, off_t delta_data_offset)
1075 {
1076 	struct got_delta *delta;
1077 
1078 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
1079 	    delta_data_offset);
1080 	if (delta == NULL)
1081 		return got_error_from_errno("got_delta_open");
1082 	/* delta is freed in got_object_close() */
1083 	deltas->nentries++;
1084 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
1085 	return NULL;
1086 }
1087 
1088 static const struct got_error *
1089 resolve_offset_delta(struct got_delta_chain *deltas,
1090     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
1091     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
1092 {
1093 	const struct got_error *err;
1094 	off_t base_offset;
1095 	uint8_t base_type;
1096 	uint64_t base_size;
1097 	size_t base_tslen;
1098 	off_t delta_data_offset;
1099 	size_t consumed;
1100 
1101 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
1102 	    delta_offset, tslen);
1103 	if (err)
1104 		return err;
1105 
1106 	delta_data_offset = delta_offset + tslen + consumed;
1107 	if (delta_data_offset >= pack->filesize)
1108 		return got_error(GOT_ERR_PACK_OFFSET);
1109 
1110 	if (pack->map == NULL) {
1111 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
1112 		if (delta_data_offset == -1)
1113 			return got_error_from_errno("lseek");
1114 	}
1115 
1116 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
1117 	    delta_data_offset);
1118 	if (err)
1119 		return err;
1120 
1121 	/* An offset delta must be in the same packfile. */
1122 	if (base_offset >= pack->filesize)
1123 		return got_error(GOT_ERR_PACK_OFFSET);
1124 
1125 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
1126 	    &base_tslen, pack, base_offset);
1127 	if (err)
1128 		return err;
1129 
1130 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
1131 	    base_tslen, base_type, base_size, recursion - 1);
1132 }
1133 
1134 const struct got_error *
1135 got_pack_parse_ref_delta(struct got_object_id *id,
1136     struct got_pack *pack, off_t delta_offset, int tslen)
1137 {
1138 	size_t idlen;
1139 
1140 	idlen = got_hash_digest_length(pack->algo);
1141 	memset(id, 0, sizeof(*id));
1142 	id->algo = pack->algo;
1143 
1144 	if (pack->map) {
1145 		size_t mapoff;
1146 
1147 		if (delta_offset + tslen > SIZE_MAX) {
1148 			return got_error_fmt(GOT_ERR_PACK_OFFSET,
1149 			    "mapoff %lld would overflow size_t",
1150 			    (long long)delta_offset + tslen);
1151 		}
1152 
1153 		mapoff = delta_offset + tslen;
1154 		if (mapoff + idlen >= pack->filesize)
1155 			return got_error(GOT_ERR_PACK_OFFSET);
1156 		memcpy(id->hash, pack->map + mapoff, idlen);
1157 	} else {
1158 		ssize_t n;
1159 		n = read(pack->fd, id->hash, idlen);
1160 		if (n < 0)
1161 			return got_error_from_errno("read");
1162 		if (n != sizeof(*id))
1163 			return got_error(GOT_ERR_BAD_PACKFILE);
1164 	}
1165 
1166 	return NULL;
1167 }
1168 
1169 static const struct got_error *
1170 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
1171     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
1172     size_t delta_size, unsigned int recursion)
1173 {
1174 	const struct got_error *err;
1175 	struct got_object_id id;
1176 	int idx;
1177 	off_t base_offset;
1178 	uint8_t base_type;
1179 	uint64_t base_size;
1180 	size_t base_tslen;
1181 	off_t delta_data_offset;
1182 
1183 	if (delta_offset + tslen >= pack->filesize)
1184 		return got_error(GOT_ERR_PACK_OFFSET);
1185 
1186 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
1187 	if (err)
1188 		return err;
1189 	if (pack->map) {
1190 		delta_data_offset = delta_offset + tslen + sizeof(id);
1191 	} else {
1192 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
1193 		if (delta_data_offset == -1)
1194 			return got_error_from_errno("lseek");
1195 	}
1196 
1197 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
1198 	    delta_data_offset);
1199 	if (err)
1200 		return err;
1201 
1202 	/* Delta base must be in the same pack file. */
1203 	idx = got_packidx_get_object_idx(packidx, &id);
1204 	if (idx == -1)
1205 		return got_error(GOT_ERR_NO_OBJ);
1206 
1207 	base_offset = got_packidx_get_object_offset(packidx, idx);
1208 	if (base_offset == -1)
1209 		return got_error(GOT_ERR_BAD_PACKIDX);
1210 
1211 	if (base_offset >= pack->filesize)
1212 		return got_error(GOT_ERR_PACK_OFFSET);
1213 
1214 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
1215 	    &base_tslen, pack, base_offset);
1216 	if (err)
1217 		return err;
1218 
1219 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
1220 	    base_tslen, base_type, base_size, recursion - 1);
1221 }
1222 
1223 const struct got_error *
1224 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
1225     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
1226     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
1227 {
1228 	const struct got_error *err = NULL;
1229 
1230 	if (--recursion == 0)
1231 		return got_error(GOT_ERR_RECURSION);
1232 
1233 	switch (delta_type) {
1234 	case GOT_OBJ_TYPE_COMMIT:
1235 	case GOT_OBJ_TYPE_TREE:
1236 	case GOT_OBJ_TYPE_BLOB:
1237 	case GOT_OBJ_TYPE_TAG:
1238 		/* Plain types are the final delta base. Recursion ends. */
1239 		err = add_delta(deltas, delta_offset, tslen, delta_type,
1240 		    delta_size, 0);
1241 		break;
1242 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1243 		err = resolve_offset_delta(deltas, packidx, pack,
1244 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1245 		break;
1246 	case GOT_OBJ_TYPE_REF_DELTA:
1247 		err = resolve_ref_delta(deltas, packidx, pack,
1248 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1249 		break;
1250 	default:
1251 		return got_error(GOT_ERR_OBJ_TYPE);
1252 	}
1253 
1254 	return err;
1255 }
1256 
1257 static const struct got_error *
1258 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
1259     struct got_pack *pack, struct got_object_id *id, off_t offset,
1260     size_t tslen, int delta_type, size_t delta_size, int idx)
1261 {
1262 	const struct got_error *err = NULL;
1263 	int resolved_type;
1264 
1265 	*obj = calloc(1, sizeof(**obj));
1266 	if (*obj == NULL)
1267 		return got_error_from_errno("calloc");
1268 
1269 	(*obj)->flags = 0;
1270 	(*obj)->hdrlen = 0;
1271 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
1272 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
1273 	(*obj)->pack_offset = offset + tslen;
1274 
1275 	STAILQ_INIT(&(*obj)->deltas.entries);
1276 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
1277 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
1278 	(*obj)->pack_idx = idx;
1279 
1280 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
1281 	    offset, tslen, delta_type, delta_size,
1282 	    GOT_DELTA_CHAIN_RECURSION_MAX);
1283 	if (err)
1284 		goto done;
1285 
1286 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
1287 	if (err)
1288 		goto done;
1289 	(*obj)->type = resolved_type;
1290 done:
1291 	if (err) {
1292 		got_object_close(*obj);
1293 		*obj = NULL;
1294 	}
1295 	return err;
1296 }
1297 
1298 const struct got_error *
1299 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
1300     struct got_packidx *packidx, int idx, struct got_object_id *id)
1301 {
1302 	const struct got_error *err = NULL;
1303 	off_t offset;
1304 	uint8_t type;
1305 	uint64_t size;
1306 	size_t tslen;
1307 
1308 	*obj = NULL;
1309 
1310 	offset = got_packidx_get_object_offset(packidx, idx);
1311 	if (offset == -1)
1312 		return got_error(GOT_ERR_BAD_PACKIDX);
1313 
1314 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1315 	    pack, offset);
1316 	if (err)
1317 		return err;
1318 
1319 	switch (type) {
1320 	case GOT_OBJ_TYPE_COMMIT:
1321 	case GOT_OBJ_TYPE_TREE:
1322 	case GOT_OBJ_TYPE_BLOB:
1323 	case GOT_OBJ_TYPE_TAG:
1324 		err = open_plain_object(obj, id, type, offset + tslen,
1325 		    size, idx);
1326 		break;
1327 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1328 	case GOT_OBJ_TYPE_REF_DELTA:
1329 		err = open_delta_object(obj, packidx, pack, id, offset,
1330 		    tslen, type, size, idx);
1331 		break;
1332 	default:
1333 		err = got_error(GOT_ERR_OBJ_TYPE);
1334 		break;
1335 	}
1336 
1337 	return err;
1338 }
1339 
1340 const struct got_error *
1341 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1342     struct got_delta_chain *deltas, struct got_pack *pack)
1343 {
1344 	struct got_delta *delta;
1345 	uint64_t base_size = 0, result_size = 0;
1346 
1347 	*max_size = 0;
1348 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1349 		/* Plain object types are the delta base. */
1350 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1351 		    delta->type != GOT_OBJ_TYPE_TREE &&
1352 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1353 		    delta->type != GOT_OBJ_TYPE_TAG) {
1354 			const struct got_error *err;
1355 			uint8_t *delta_buf = NULL;
1356 			size_t delta_len;
1357 			int cached = 1;
1358 
1359 			if (pack->delta_cache) {
1360 				got_delta_cache_get(&delta_buf, &delta_len,
1361 				    pack->delta_cache, delta->data_offset);
1362 			}
1363 			if (delta_buf == NULL) {
1364 				cached = 0;
1365 				err = read_delta_data(&delta_buf, &delta_len,
1366 				    NULL, delta->data_offset, pack);
1367 				if (err)
1368 					return err;
1369 			}
1370 			if (pack->delta_cache && !cached) {
1371 				err = got_delta_cache_add(pack->delta_cache,
1372 				    delta->data_offset, delta_buf, delta_len);
1373 				if (err == NULL)
1374 					cached = 1;
1375 				else if (err->code != GOT_ERR_NO_SPACE) {
1376 					free(delta_buf);
1377 					return err;
1378 				}
1379 			}
1380 			err = got_delta_get_sizes(&base_size, &result_size,
1381 			    delta_buf, delta_len);
1382 			if (!cached)
1383 				free(delta_buf);
1384 			if (err)
1385 				return err;
1386 		} else
1387 			base_size = delta->size;
1388 		if (base_size > *max_size)
1389 			*max_size = base_size;
1390 		if (result_size > *max_size)
1391 			*max_size = result_size;
1392 	}
1393 
1394 	return NULL;
1395 }
1396 
1397 const struct got_error *
1398 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1399     struct got_pack *pack)
1400 {
1401 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1402 		return got_error(GOT_ERR_OBJ_TYPE);
1403 
1404 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1405 }
1406 
1407 const struct got_error *
1408 got_pack_dump_delta_chain_to_file(size_t *result_size,
1409     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1410     FILE *base_file, FILE *accum_file)
1411 {
1412 	const struct got_error *err = NULL;
1413 	struct got_delta *delta;
1414 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1415 	size_t base_bufsz = 0, accum_bufsz = 0, accum_size = 0, delta_len;
1416 	/* We process small enough files entirely in memory for speed. */
1417 	const size_t max_bufsize = GOT_DELTA_RESULT_SIZE_CACHED_MAX;
1418 	uint64_t max_size = 0;
1419 	int n = 0;
1420 
1421 	*result_size = 0;
1422 
1423 	if (STAILQ_EMPTY(&deltas->entries))
1424 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1425 
1426 	if (fseeko(base_file, 0L, SEEK_SET) == -1)
1427 		return got_error_from_errno("fseeko");
1428 	if (fseeko(accum_file, 0L, SEEK_SET) == -1)
1429 		return got_error_from_errno("fseeko");
1430 
1431 	/* Deltas are ordered in ascending order. */
1432 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1433 		uint8_t *delta_buf = NULL;
1434 		uint64_t base_size, result_size = 0;
1435 		int cached = 1;
1436 		if (n == 0) {
1437 			size_t mapoff;
1438 			off_t delta_data_offset;
1439 
1440 			/* Plain object types are the delta base. */
1441 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1442 			    delta->type != GOT_OBJ_TYPE_TREE &&
1443 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1444 			    delta->type != GOT_OBJ_TYPE_TAG) {
1445 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1446 				goto done;
1447 			}
1448 
1449 			delta_data_offset = delta->offset + delta->tslen;
1450 			if (delta_data_offset >= pack->filesize) {
1451 				err = got_error(GOT_ERR_PACK_OFFSET);
1452 				goto done;
1453 			}
1454 			if (pack->map == NULL) {
1455 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1456 				    == -1) {
1457 					err = got_error_from_errno("lseek");
1458 					goto done;
1459 				}
1460 			}
1461 			if (delta->size > max_size)
1462 				max_size = delta->size;
1463 			if (max_size > max_bufsize) {
1464 				if (pack->map) {
1465 					if (delta_data_offset > SIZE_MAX) {
1466 						return got_error_fmt(
1467 						    GOT_ERR_RANGE,
1468 						    "delta offset %lld "
1469 						    "overflows size_t",
1470 						    (long long)
1471 						    delta_data_offset);
1472 					}
1473 
1474 					mapoff = delta_data_offset;
1475 					err = got_inflate_to_file_mmap(
1476 					    &base_bufsz, NULL, NULL, pack->map,
1477 					    mapoff, pack->filesize - mapoff,
1478 					    base_file);
1479 				} else
1480 					err = got_inflate_to_file_fd(
1481 					    &base_bufsz, NULL, NULL, pack->fd,
1482 					    base_file);
1483 			} else {
1484 				accum_buf = malloc(max_size);
1485 				if (accum_buf == NULL) {
1486 					err = got_error_from_errno("malloc");
1487 					goto done;
1488 				}
1489 				accum_bufsz = max_size;
1490 				if (pack->map) {
1491 					if (delta_data_offset > SIZE_MAX) {
1492 						return got_error_fmt(
1493 						    GOT_ERR_RANGE,
1494 						    "delta offset %lld "
1495 						    "overflows size_t",
1496 						    (long long)
1497 						    delta_data_offset);
1498 					}
1499 
1500 					mapoff = delta_data_offset;
1501 					err = got_inflate_to_mem_mmap(&base_buf,
1502 					    &base_bufsz, NULL, NULL,
1503 					    pack->map, mapoff,
1504 					    pack->filesize - mapoff);
1505 				} else
1506 					err = got_inflate_to_mem_fd(&base_buf,
1507 					    &base_bufsz, NULL, NULL, max_size,
1508 					    pack->fd);
1509 			}
1510 			if (err)
1511 				goto done;
1512 			n++;
1513 			if (base_buf == NULL)
1514 				rewind(base_file);
1515 			continue;
1516 		}
1517 
1518 		if (pack->delta_cache) {
1519 			got_delta_cache_get(&delta_buf, &delta_len,
1520 			    pack->delta_cache, delta->data_offset);
1521 		}
1522 		if (delta_buf == NULL) {
1523 			cached = 0;
1524 			err = read_delta_data(&delta_buf, &delta_len, NULL,
1525 			    delta->data_offset, pack);
1526 			if (err)
1527 				goto done;
1528 		}
1529 		if (pack->delta_cache && !cached) {
1530 			err = got_delta_cache_add(pack->delta_cache,
1531 			    delta->data_offset, delta_buf, delta_len);
1532 			if (err == NULL)
1533 				cached = 1;
1534 			else if (err->code != GOT_ERR_NO_SPACE) {
1535 				free(delta_buf);
1536 				goto done;
1537 			}
1538 		}
1539 
1540 		err = got_delta_get_sizes(&base_size, &result_size,
1541 		    delta_buf, delta_len);
1542 		if (err) {
1543 			if (!cached)
1544 				free(delta_buf);
1545 			goto done;
1546 		}
1547 		if (base_size > max_size)
1548 			max_size = base_size;
1549 		if (result_size > max_size)
1550 			max_size = result_size;
1551 
1552 		if (base_buf && max_size > max_bufsize) {
1553 			/* Switch from buffers to temporary files. */
1554 			size_t w = fwrite(base_buf, 1, base_bufsz,
1555 			    base_file);
1556 			if (w != base_bufsz) {
1557 				err = got_ferror(outfile, GOT_ERR_IO);
1558 				if (!cached)
1559 					free(delta_buf);
1560 				goto done;
1561 			}
1562 			free(base_buf);
1563 			base_buf = NULL;
1564 			free(accum_buf);
1565 			accum_buf = NULL;
1566 		}
1567 
1568 		if (base_buf && max_size > base_bufsz) {
1569 			uint8_t *p = realloc(base_buf, max_size);
1570 			if (p == NULL) {
1571 				err = got_error_from_errno("realloc");
1572 				if (!cached)
1573 					free(delta_buf);
1574 				goto done;
1575 			}
1576 			base_buf = p;
1577 			base_bufsz = max_size;
1578 		}
1579 
1580 		if (accum_buf && max_size > accum_bufsz) {
1581 			uint8_t *p = realloc(accum_buf, max_size);
1582 			if (p == NULL) {
1583 				err = got_error_from_errno("realloc");
1584 				if (!cached)
1585 					free(delta_buf);
1586 				goto done;
1587 			}
1588 			accum_buf = p;
1589 			accum_bufsz = max_size;
1590 		}
1591 
1592 		if (base_buf) {
1593 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1594 			    delta_buf, delta_len, accum_buf,
1595 			    &accum_size, max_size);
1596 			n++;
1597 		} else {
1598 			err = got_delta_apply(base_file, delta_buf,
1599 			    delta_len,
1600 			    /* Final delta application writes to output file. */
1601 			    ++n < deltas->nentries ? accum_file : outfile,
1602 			    &accum_size);
1603 		}
1604 		if (!cached)
1605 			free(delta_buf);
1606 		if (err)
1607 			goto done;
1608 
1609 		if (n < deltas->nentries) {
1610 			/* Accumulated delta becomes the new base. */
1611 			if (base_buf) {
1612 				uint8_t *tmp = accum_buf;
1613 				size_t tmp_size = accum_bufsz;
1614 				accum_buf = base_buf;
1615 				accum_bufsz = base_bufsz;
1616 				base_buf = tmp;
1617 				base_bufsz = tmp_size;
1618 			} else {
1619 				FILE *tmp = accum_file;
1620 				accum_file = base_file;
1621 				base_file = tmp;
1622 				rewind(base_file);
1623 				rewind(accum_file);
1624 			}
1625 		}
1626 	}
1627 
1628 done:
1629 	free(base_buf);
1630 	if (accum_buf) {
1631 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1632 		free(accum_buf);
1633 		if (len != accum_size)
1634 			err = got_ferror(outfile, GOT_ERR_IO);
1635 	}
1636 	rewind(outfile);
1637 	if (err == NULL)
1638 		*result_size = accum_size;
1639 	return err;
1640 }
1641 
1642 const struct got_error *
1643 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1644     struct got_delta_chain *deltas, struct got_pack *pack)
1645 {
1646 	const struct got_error *err = NULL;
1647 	struct got_delta *delta;
1648 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1649 	size_t base_bufsz = 0, accum_bufsz = 0, accum_size = 0, delta_len;
1650 	uint64_t max_size = 0;
1651 	int n = 0;
1652 
1653 	*outbuf = NULL;
1654 	*outlen = 0;
1655 
1656 	if (STAILQ_EMPTY(&deltas->entries))
1657 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1658 
1659 	/* Deltas are ordered in ascending order. */
1660 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1661 		uint8_t *delta_buf = NULL;
1662 		uint64_t base_size, result_size = 0;
1663 		int cached = 1;
1664 		if (n == 0) {
1665 			off_t delta_data_offset;
1666 
1667 			/* Plain object types are the delta base. */
1668 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1669 			    delta->type != GOT_OBJ_TYPE_TREE &&
1670 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1671 			    delta->type != GOT_OBJ_TYPE_TAG) {
1672 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1673 				goto done;
1674 			}
1675 
1676 			delta_data_offset = delta->offset + delta->tslen;
1677 			if (delta_data_offset >= pack->filesize) {
1678 				err = got_error(GOT_ERR_PACK_OFFSET);
1679 				goto done;
1680 			}
1681 
1682 			if (delta->size > max_size)
1683 				max_size = delta->size;
1684 
1685 			if (pack->map) {
1686 				size_t mapoff;
1687 
1688 				if (delta_data_offset > SIZE_MAX) {
1689 					return got_error_fmt(GOT_ERR_RANGE,
1690 					    "delta %lld offset would "
1691 					    "overflow size_t",
1692 					    (long long)delta_data_offset);
1693 				}
1694 
1695 				mapoff = delta_data_offset;
1696 				err = got_inflate_to_mem_mmap(&base_buf,
1697 				    &base_bufsz, NULL, NULL, pack->map,
1698 				    mapoff, pack->filesize - mapoff);
1699 			} else {
1700 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1701 				    == -1) {
1702 					err = got_error_from_errno("lseek");
1703 					goto done;
1704 				}
1705 				err = got_inflate_to_mem_fd(&base_buf,
1706 				    &base_bufsz, NULL, NULL, max_size,
1707 				    pack->fd);
1708 			}
1709 			if (err)
1710 				goto done;
1711 			n++;
1712 			continue;
1713 		}
1714 
1715 		if (pack->delta_cache) {
1716 			got_delta_cache_get(&delta_buf, &delta_len,
1717 			    pack->delta_cache, delta->data_offset);
1718 		}
1719 		if (delta_buf == NULL) {
1720 			cached = 0;
1721 			err = read_delta_data(&delta_buf, &delta_len, NULL,
1722 			    delta->data_offset, pack);
1723 			if (err)
1724 				goto done;
1725 		}
1726 		if (pack->delta_cache && !cached) {
1727 			err = got_delta_cache_add(pack->delta_cache,
1728 			    delta->data_offset, delta_buf, delta_len);
1729 			if (err == NULL)
1730 				cached = 1;
1731 			else if (err->code != GOT_ERR_NO_SPACE) {
1732 				free(delta_buf);
1733 				goto done;
1734 			}
1735 		}
1736 
1737 		err = got_delta_get_sizes(&base_size, &result_size,
1738 		    delta_buf, delta_len);
1739 		if (err) {
1740 			if (!cached)
1741 				free(delta_buf);
1742 			goto done;
1743 		}
1744 		if (base_size > max_size)
1745 			max_size = base_size;
1746 		if (result_size > max_size)
1747 			max_size = result_size;
1748 
1749 		if (max_size > base_bufsz) {
1750 			uint8_t *p = realloc(base_buf, max_size);
1751 			if (p == NULL) {
1752 				err = got_error_from_errno("realloc");
1753 				if (!cached)
1754 					free(delta_buf);
1755 				goto done;
1756 			}
1757 			base_buf = p;
1758 			base_bufsz = max_size;
1759 		}
1760 
1761 		if (max_size > accum_bufsz) {
1762 			uint8_t *p = realloc(accum_buf, max_size);
1763 			if (p == NULL) {
1764 				err = got_error_from_errno("realloc");
1765 				if (!cached)
1766 					free(delta_buf);
1767 				goto done;
1768 			}
1769 			accum_buf = p;
1770 			accum_bufsz = max_size;
1771 		}
1772 
1773 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1774 		    delta_buf, delta_len, accum_buf,
1775 		    &accum_size, max_size);
1776 		if (!cached)
1777 			free(delta_buf);
1778 		n++;
1779 		if (err)
1780 			goto done;
1781 
1782 		if (n < deltas->nentries) {
1783 			/* Accumulated delta becomes the new base. */
1784 			uint8_t *tmp = accum_buf;
1785 			size_t tmp_size = accum_bufsz;
1786 			accum_buf = base_buf;
1787 			accum_bufsz = base_bufsz;
1788 			base_buf = tmp;
1789 			base_bufsz = tmp_size;
1790 		}
1791 	}
1792 
1793 done:
1794 	free(base_buf);
1795 	if (err) {
1796 		free(accum_buf);
1797 		*outbuf = NULL;
1798 		*outlen = 0;
1799 	} else {
1800 		*outbuf = accum_buf;
1801 		*outlen = accum_size;
1802 	}
1803 	return err;
1804 }
1805 
1806 const struct got_error *
1807 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1808     FILE *outfile, FILE *base_file, FILE *accum_file)
1809 {
1810 	const struct got_error *err = NULL;
1811 
1812 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1813 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1814 
1815 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1816 		if (obj->pack_offset >= pack->filesize)
1817 			return got_error(GOT_ERR_PACK_OFFSET);
1818 
1819 		if (pack->map) {
1820 			size_t mapoff;
1821 
1822 			if (obj->pack_offset > SIZE_MAX) {
1823 				return got_error_fmt(GOT_ERR_RANGE,
1824 				    "pack offset %lld would overflow size_t",
1825 				    (long long)obj->pack_offset);
1826 			}
1827 
1828 			mapoff = obj->pack_offset;
1829 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1830 			    pack->map, mapoff, pack->filesize - mapoff,
1831 			    outfile);
1832 		} else {
1833 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1834 				return got_error_from_errno("lseek");
1835 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1836 			    pack->fd, outfile);
1837 		}
1838 	} else
1839 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1840 		    &obj->deltas, pack, outfile, base_file, accum_file);
1841 
1842 	return err;
1843 }
1844 
1845 const struct got_error *
1846 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1847     struct got_object *obj, struct got_pack *pack)
1848 {
1849 	const struct got_error *err = NULL;
1850 
1851 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1852 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1853 
1854 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1855 		if (obj->pack_offset >= pack->filesize)
1856 			return got_error(GOT_ERR_PACK_OFFSET);
1857 		if (pack->map) {
1858 			size_t mapoff;
1859 
1860 			if (obj->pack_offset > SIZE_MAX) {
1861 				return got_error_fmt(GOT_ERR_RANGE,
1862 				    "pack offset %lld would overflow size_t",
1863 				    (long long)obj->pack_offset);
1864 			}
1865 
1866 			mapoff = obj->pack_offset;
1867 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1868 			    pack->map, mapoff, pack->filesize - mapoff);
1869 		} else {
1870 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1871 				return got_error_from_errno("lseek");
1872 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1873 			    obj->size, pack->fd);
1874 		}
1875 	} else
1876 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1877 		    pack);
1878 
1879 	return err;
1880 }
1881 
1882 static const struct got_error *
1883 read_raw_delta_data(uint8_t **delta_buf, size_t *delta_len,
1884     size_t *delta_len_compressed, uint64_t *base_size, uint64_t *result_size,
1885     off_t delta_data_offset, struct got_pack *pack, struct got_packidx *packidx)
1886 {
1887 	const struct got_error *err = NULL;
1888 
1889 	/* Validate decompression and obtain the decompressed size. */
1890 	err = read_delta_data(delta_buf, delta_len, delta_len_compressed,
1891 	    delta_data_offset, pack);
1892 	if (err)
1893 		return err;
1894 
1895 	/* Read delta base/result sizes from head of delta stream. */
1896 	err = got_delta_get_sizes(base_size, result_size,
1897 	    *delta_buf, *delta_len);
1898 	if (err)
1899 		goto done;
1900 
1901 	/* Discard decompressed delta and read it again in compressed form. */
1902 	free(*delta_buf);
1903 	*delta_buf = malloc(*delta_len_compressed);
1904 	if (*delta_buf == NULL) {
1905 		err = got_error_from_errno("malloc");
1906 		goto done;
1907 	}
1908 	if (pack->map) {
1909 		if (delta_data_offset >= pack->filesize) {
1910 			err = got_error(GOT_ERR_PACK_OFFSET);
1911 			goto done;
1912 		}
1913 		memcpy(*delta_buf, pack->map + delta_data_offset,
1914 		    *delta_len_compressed);
1915 	} else {
1916 		ssize_t n;
1917 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1) {
1918 			err = got_error_from_errno("lseek");
1919 			goto done;
1920 		}
1921 		n = read(pack->fd, *delta_buf, *delta_len_compressed);
1922 		if (n < 0) {
1923 			err = got_error_from_errno("read");
1924 			goto done;
1925 		} else if (n != *delta_len_compressed) {
1926 			err = got_error(GOT_ERR_IO);
1927 			goto done;
1928 		}
1929 	}
1930 done:
1931 	if (err) {
1932 		free(*delta_buf);
1933 		*delta_buf = NULL;
1934 		*delta_len = 0;
1935 		*delta_len_compressed = 0;
1936 		*base_size = 0;
1937 		*result_size = 0;
1938 	}
1939 	return err;
1940 }
1941 
1942 const struct got_error *
1943 got_packfile_extract_raw_delta(uint8_t **delta_buf, size_t *delta_size,
1944     size_t *delta_compressed_size, off_t *delta_offset,
1945     off_t *delta_data_offset, off_t *base_offset,
1946     struct got_object_id *base_id, uint64_t *base_size, uint64_t *result_size,
1947     struct got_pack *pack, struct got_packidx *packidx, int idx)
1948 {
1949 	const struct got_error *err = NULL;
1950 	off_t offset;
1951 	uint8_t type;
1952 	uint64_t size;
1953 	size_t tslen, delta_hdrlen;
1954 
1955 	*delta_buf = NULL;
1956 	*delta_size = 0;
1957 	*delta_compressed_size = 0;
1958 	*delta_offset = 0;
1959 	*delta_data_offset = 0;
1960 	*base_offset = 0;
1961 	*base_size = 0;
1962 	*result_size = 0;
1963 
1964 	offset = got_packidx_get_object_offset(packidx, idx);
1965 	if (offset == -1)
1966 		return got_error(GOT_ERR_BAD_PACKIDX);
1967 
1968 	if (offset >= pack->filesize)
1969 		return got_error(GOT_ERR_PACK_OFFSET);
1970 
1971 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1972 	    pack, offset);
1973 	if (err)
1974 		return err;
1975 
1976 	if (tslen + size < tslen || offset + size < size ||
1977 	    tslen + offset < tslen)
1978 		return got_error(GOT_ERR_PACK_OFFSET);
1979 
1980 	switch (type) {
1981 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1982 		err = got_pack_parse_offset_delta(base_offset, &delta_hdrlen,
1983 		    pack, offset, tslen);
1984 		if (err)
1985 			return err;
1986 		break;
1987 	case GOT_OBJ_TYPE_REF_DELTA:
1988 		err = got_pack_parse_ref_delta(base_id, pack, offset, tslen);
1989 		if (err)
1990 			return err;
1991 		delta_hdrlen = SHA1_DIGEST_LENGTH;
1992 		break;
1993 	default:
1994 		return got_error_fmt(GOT_ERR_OBJ_TYPE,
1995 		    "non-delta object type %d found at offset %lld",
1996 		    type, (long long)offset);
1997 	}
1998 
1999 	if (tslen + delta_hdrlen < delta_hdrlen ||
2000 	    offset + delta_hdrlen < delta_hdrlen)
2001 		return got_error(GOT_ERR_BAD_DELTA);
2002 
2003 	*delta_data_offset = offset + tslen + delta_hdrlen;
2004 	err = read_raw_delta_data(delta_buf, delta_size, delta_compressed_size,
2005 	    base_size, result_size, *delta_data_offset, pack, packidx);
2006 	if (err)
2007 		return err;
2008 
2009 	if (*delta_size != size) {
2010 		err = got_error(GOT_ERR_BAD_DELTA);
2011 		goto done;
2012 	}
2013 
2014 	*delta_offset = offset;
2015 done:
2016 	if (err) {
2017 		free(*delta_buf);
2018 		*delta_buf = NULL;
2019 		*delta_size = 0;
2020 		*delta_compressed_size = 0;
2021 		*delta_offset = 0;
2022 		*base_offset = 0;
2023 		*base_size = 0;
2024 		*result_size = 0;
2025 	}
2026 	return err;
2027 }