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 	memcpy(id->hash, oid->hash, idlen);
692 	return NULL;
693 }
694 
695 const struct got_error *
696 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
697     struct got_packidx *packidx, const char *id_str_prefix)
698 {
699 	const struct got_error *err = NULL;
700 	u_int8_t id0;
701 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
702 	char hex[3];
703 	size_t idlen, prefix_len = strlen(id_str_prefix);
704 	struct got_packidx_object_id *oid;
705 	uint32_t i = 0;
706 
707 	idlen = got_hash_digest_length(packidx->algo);
708 
709 	STAILQ_INIT(matched_ids);
710 
711 	if (prefix_len < 2)
712 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
713 
714 	hex[0] = id_str_prefix[0];
715 	hex[1] = id_str_prefix[1];
716 	hex[2] = '\0';
717 	if (!got_parse_xdigit(&id0, hex))
718 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
719 
720 	if (id0 > 0)
721 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
722 	oid = packidx->hdr.sorted_ids + i * idlen;
723 	while (i < totobj && oid->hash[0] == id0) {
724 		char id_str[GOT_OBJECT_ID_HEX_MAXLEN];
725 		struct got_object_qid *qid;
726 		int cmp;
727 
728 		if (!got_hash_digest_to_str(oid->hash, id_str, sizeof(id_str),
729 		    packidx->algo))
730 		        return got_error(GOT_ERR_NO_SPACE);
731 
732 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
733 		if (cmp < 0) {
734 			i++;
735 			oid = packidx->hdr.sorted_ids + i * idlen;
736 			continue;
737 		} else if (cmp > 0)
738 			break;
739 
740 		err = got_object_qid_alloc_partial(&qid);
741 		if (err)
742 			break;
743 		memcpy(qid->id.hash, oid->hash, idlen);
744 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
745 
746 		i++;
747 		oid = packidx->hdr.sorted_ids + i * idlen;
748 	}
749 
750 	if (err)
751 		got_object_id_queue_free(matched_ids);
752 	return err;
753 }
754 
755 static void
756 set_max_datasize(void)
757 {
758 	struct rlimit rl;
759 
760 	if (getrlimit(RLIMIT_DATA, &rl) != 0)
761 		return;
762 
763 	rl.rlim_cur = rl.rlim_max;
764 	setrlimit(RLIMIT_DATA, &rl);
765 }
766 
767 const struct got_error *
768 got_pack_start_privsep_child(struct got_pack *pack, struct got_packidx *packidx)
769 {
770 	const struct got_error *err = NULL;
771 	int imsg_fds[2];
772 	pid_t pid;
773 	struct imsgbuf *ibuf;
774 
775 	ibuf = calloc(1, sizeof(*ibuf));
776 	if (ibuf == NULL)
777 		return got_error_from_errno("calloc");
778 
779 	pack->privsep_child = calloc(1, sizeof(*pack->privsep_child));
780 	if (pack->privsep_child == NULL) {
781 		err = got_error_from_errno("calloc");
782 		free(ibuf);
783 		return err;
784 	}
785 	pack->child_has_tempfiles = 0;
786 	pack->child_has_delta_outfd = 0;
787 
788 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, imsg_fds) == -1) {
789 		err = got_error_from_errno("socketpair");
790 		goto done;
791 	}
792 
793 	pid = fork();
794 	if (pid == -1) {
795 		err = got_error_from_errno("fork");
796 		goto done;
797 	} else if (pid == 0) {
798 		set_max_datasize();
799 		got_privsep_exec_child(imsg_fds, GOT_PATH_PROG_READ_PACK,
800 		    pack->path_packfile);
801 		/* not reached */
802 	}
803 
804 	if (close(imsg_fds[1]) == -1)
805 		return got_error_from_errno("close");
806 	pack->privsep_child->imsg_fd = imsg_fds[0];
807 	pack->privsep_child->pid = pid;
808 	imsg_init(ibuf, imsg_fds[0]);
809 	pack->privsep_child->ibuf = ibuf;
810 
811 	err = got_privsep_init_pack_child(ibuf, pack, packidx);
812 	if (err) {
813 		const struct got_error *child_err;
814 		err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
815 		child_err = got_privsep_wait_for_child(
816 		    pack->privsep_child->pid);
817 		if (child_err && err == NULL)
818 			err = child_err;
819 	}
820 done:
821 	if (err) {
822 		free(ibuf);
823 		free(pack->privsep_child);
824 		pack->privsep_child = NULL;
825 	}
826 	return err;
827 }
828 
829 static const struct got_error *
830 pack_stop_privsep_child(struct got_pack *pack)
831 {
832 	const struct got_error *err = NULL, *close_err = NULL;
833 
834 	if (pack->privsep_child == NULL)
835 		return NULL;
836 
837 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
838 	if (err)
839 		return err;
840 	if (close(pack->privsep_child->imsg_fd) == -1)
841 		close_err = got_error_from_errno("close");
842 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
843 	if (close_err && err == NULL)
844 		err = close_err;
845 	imsg_clear(pack->privsep_child->ibuf);
846 	free(pack->privsep_child->ibuf);
847 	free(pack->privsep_child);
848 	pack->privsep_child = NULL;
849 	return err;
850 }
851 
852 const struct got_error *
853 got_pack_close(struct got_pack *pack)
854 {
855 	const struct got_error *err = NULL;
856 
857 	err = pack_stop_privsep_child(pack);
858 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
859 		err = got_error_from_errno("munmap");
860 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
861 		err = got_error_from_errno("close");
862 	pack->fd = -1;
863 	free(pack->path_packfile);
864 	pack->path_packfile = NULL;
865 	pack->filesize = 0;
866 	if (pack->delta_cache) {
867 		got_delta_cache_free(pack->delta_cache);
868 		pack->delta_cache = NULL;
869 	}
870 
871 	/*
872 	 * Leave accumfd and basefd alone. They are managed by the
873 	 * repository layer and can be reused.
874 	 */
875 
876 	return err;
877 }
878 
879 const struct got_error *
880 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
881     struct got_pack *pack, off_t offset)
882 {
883 	uint8_t t = 0;
884 	uint64_t s = 0;
885 	uint8_t sizeN;
886 	size_t mapoff = 0;
887 	int i = 0;
888 
889 	*len = 0;
890 
891 	if (offset >= pack->filesize)
892 		return got_error(GOT_ERR_PACK_OFFSET);
893 
894 	if (pack->map) {
895 		if (offset > SIZE_MAX) {
896 			return got_error_fmt(GOT_ERR_PACK_OFFSET,
897 			    "offset %lld overflows size_t",
898 			    (long long)offset);
899 		}
900 
901 		mapoff = (size_t)offset;
902 	} else {
903 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
904 			return got_error_from_errno("lseek");
905 	}
906 
907 	do {
908 		/* We do not support size values which don't fit in 64 bit. */
909 		if (i > 9)
910 			return got_error_fmt(GOT_ERR_OBJ_TOO_LARGE,
911 			    "packfile offset %lld", (long long)offset);
912 
913 		if (pack->map) {
914 			if (mapoff + sizeof(sizeN) >= pack->filesize)
915 				return got_error(GOT_ERR_BAD_PACKFILE);
916 			sizeN = *(pack->map + mapoff);
917 			mapoff += sizeof(sizeN);
918 		} else {
919 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
920 			if (n < 0)
921 				return got_error_from_errno("read");
922 			if (n != sizeof(sizeN))
923 				return got_error(GOT_ERR_BAD_PACKFILE);
924 		}
925 		*len += sizeof(sizeN);
926 
927 		if (i == 0) {
928 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
929 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
930 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
931 		} else {
932 			size_t shift = 4 + 7 * (i - 1);
933 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
934 		}
935 		i++;
936 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
937 
938 	*type = t;
939 	*size = s;
940 	return NULL;
941 }
942 
943 static const struct got_error *
944 open_plain_object(struct got_object **obj, struct got_object_id *id,
945     uint8_t type, off_t offset, size_t size, int idx)
946 {
947 	*obj = calloc(1, sizeof(**obj));
948 	if (*obj == NULL)
949 		return got_error_from_errno("calloc");
950 
951 	(*obj)->type = type;
952 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
953 	(*obj)->pack_idx = idx;
954 	(*obj)->hdrlen = 0;
955 	(*obj)->size = size;
956 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
957 	(*obj)->pack_offset = offset;
958 
959 	return NULL;
960 }
961 
962 static const struct got_error *
963 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
964     off_t delta_offset)
965 {
966 	int64_t o = 0;
967 	uint8_t offN;
968 	int i = 0;
969 
970 	*offset = 0;
971 	*len = 0;
972 
973 	do {
974 		/* We do not support offset values which don't fit in 64 bit. */
975 		if (i > 8)
976 			return got_error(GOT_ERR_NO_SPACE);
977 
978 		if (pack->map) {
979 			size_t mapoff;
980 
981 			if (delta_offset + *len > SIZE_MAX) {
982 				return got_error_fmt(GOT_ERR_PACK_OFFSET,
983 				    "mapoff %lld would overflow size_t",
984 				    (long long)delta_offset + *len);
985 			}
986 
987 			mapoff = (size_t)delta_offset + *len;
988 			if (mapoff + sizeof(offN) >= pack->filesize)
989 				return got_error(GOT_ERR_PACK_OFFSET);
990 			offN = *(pack->map + mapoff);
991 		} else {
992 			ssize_t n;
993 			n = read(pack->fd, &offN, sizeof(offN));
994 			if (n < 0)
995 				return got_error_from_errno("read");
996 			if (n != sizeof(offN))
997 				return got_error(GOT_ERR_BAD_PACKFILE);
998 		}
999 		*len += sizeof(offN);
1000 
1001 		if (i == 0)
1002 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
1003 		else {
1004 			o++;
1005 			o <<= 7;
1006 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
1007 		}
1008 		i++;
1009 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
1010 
1011 	*offset = o;
1012 	return NULL;
1013 }
1014 
1015 const struct got_error *
1016 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
1017     struct got_pack *pack, off_t offset, size_t tslen)
1018 {
1019 	const struct got_error *err;
1020 	int64_t negoffset;
1021 	size_t negofflen;
1022 
1023 	*len = 0;
1024 
1025 	err = parse_negative_offset(&negoffset, &negofflen, pack,
1026 	    offset + tslen);
1027 	if (err)
1028 		return err;
1029 
1030 	/* Compute the base object's offset (must be in the same pack file). */
1031 	*base_offset = (offset - negoffset);
1032 	if (*base_offset <= 0)
1033 		return got_error(GOT_ERR_BAD_PACKFILE);
1034 
1035 	*len = negofflen;
1036 	return NULL;
1037 }
1038 
1039 static const struct got_error *
1040 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
1041     size_t *delta_compressed_len, size_t delta_data_offset,
1042     struct got_pack *pack)
1043 {
1044 	const struct got_error *err = NULL;
1045 	size_t consumed = 0;
1046 
1047 	if (pack->map) {
1048 		if (delta_data_offset >= pack->filesize)
1049 			return got_error(GOT_ERR_PACK_OFFSET);
1050 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
1051 		    &consumed, NULL, pack->map, delta_data_offset,
1052 		    pack->filesize - delta_data_offset);
1053 		if (err)
1054 			return err;
1055 	} else {
1056 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
1057 			return got_error_from_errno("lseek");
1058 		err = got_inflate_to_mem_fd(delta_buf, delta_len,
1059 		    &consumed, NULL, 0, pack->fd);
1060 		if (err)
1061 			return err;
1062 	}
1063 
1064 	if (delta_compressed_len)
1065 		*delta_compressed_len = consumed;
1066 
1067 	return NULL;
1068 }
1069 
1070 static const struct got_error *
1071 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
1072     int delta_type, size_t delta_size, off_t delta_data_offset)
1073 {
1074 	struct got_delta *delta;
1075 
1076 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
1077 	    delta_data_offset);
1078 	if (delta == NULL)
1079 		return got_error_from_errno("got_delta_open");
1080 	/* delta is freed in got_object_close() */
1081 	deltas->nentries++;
1082 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
1083 	return NULL;
1084 }
1085 
1086 static const struct got_error *
1087 resolve_offset_delta(struct got_delta_chain *deltas,
1088     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
1089     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
1090 {
1091 	const struct got_error *err;
1092 	off_t base_offset;
1093 	uint8_t base_type;
1094 	uint64_t base_size;
1095 	size_t base_tslen;
1096 	off_t delta_data_offset;
1097 	size_t consumed;
1098 
1099 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
1100 	    delta_offset, tslen);
1101 	if (err)
1102 		return err;
1103 
1104 	delta_data_offset = delta_offset + tslen + consumed;
1105 	if (delta_data_offset >= pack->filesize)
1106 		return got_error(GOT_ERR_PACK_OFFSET);
1107 
1108 	if (pack->map == NULL) {
1109 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
1110 		if (delta_data_offset == -1)
1111 			return got_error_from_errno("lseek");
1112 	}
1113 
1114 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
1115 	    delta_data_offset);
1116 	if (err)
1117 		return err;
1118 
1119 	/* An offset delta must be in the same packfile. */
1120 	if (base_offset >= pack->filesize)
1121 		return got_error(GOT_ERR_PACK_OFFSET);
1122 
1123 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
1124 	    &base_tslen, pack, base_offset);
1125 	if (err)
1126 		return err;
1127 
1128 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
1129 	    base_tslen, base_type, base_size, recursion - 1);
1130 }
1131 
1132 const struct got_error *
1133 got_pack_parse_ref_delta(struct got_object_id *id,
1134     struct got_pack *pack, off_t delta_offset, int tslen)
1135 {
1136 	size_t idlen;
1137 
1138 	idlen = got_hash_digest_length(pack->algo);
1139 	memset(id, 0, sizeof(*id));
1140 
1141 	if (pack->map) {
1142 		size_t mapoff;
1143 
1144 		if (delta_offset + tslen > SIZE_MAX) {
1145 			return got_error_fmt(GOT_ERR_PACK_OFFSET,
1146 			    "mapoff %lld would overflow size_t",
1147 			    (long long)delta_offset + tslen);
1148 		}
1149 
1150 		mapoff = delta_offset + tslen;
1151 		if (mapoff + idlen >= pack->filesize)
1152 			return got_error(GOT_ERR_PACK_OFFSET);
1153 		memcpy(id->hash, pack->map + mapoff, idlen);
1154 	} else {
1155 		ssize_t n;
1156 		n = read(pack->fd, id->hash, idlen);
1157 		if (n < 0)
1158 			return got_error_from_errno("read");
1159 		if (n != sizeof(*id))
1160 			return got_error(GOT_ERR_BAD_PACKFILE);
1161 	}
1162 
1163 	return NULL;
1164 }
1165 
1166 static const struct got_error *
1167 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
1168     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
1169     size_t delta_size, unsigned int recursion)
1170 {
1171 	const struct got_error *err;
1172 	struct got_object_id id;
1173 	int idx;
1174 	off_t base_offset;
1175 	uint8_t base_type;
1176 	uint64_t base_size;
1177 	size_t base_tslen;
1178 	off_t delta_data_offset;
1179 
1180 	if (delta_offset + tslen >= pack->filesize)
1181 		return got_error(GOT_ERR_PACK_OFFSET);
1182 
1183 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
1184 	if (err)
1185 		return err;
1186 	if (pack->map) {
1187 		delta_data_offset = delta_offset + tslen + sizeof(id);
1188 	} else {
1189 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
1190 		if (delta_data_offset == -1)
1191 			return got_error_from_errno("lseek");
1192 	}
1193 
1194 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
1195 	    delta_data_offset);
1196 	if (err)
1197 		return err;
1198 
1199 	/* Delta base must be in the same pack file. */
1200 	idx = got_packidx_get_object_idx(packidx, &id);
1201 	if (idx == -1)
1202 		return got_error(GOT_ERR_NO_OBJ);
1203 
1204 	base_offset = got_packidx_get_object_offset(packidx, idx);
1205 	if (base_offset == -1)
1206 		return got_error(GOT_ERR_BAD_PACKIDX);
1207 
1208 	if (base_offset >= pack->filesize)
1209 		return got_error(GOT_ERR_PACK_OFFSET);
1210 
1211 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
1212 	    &base_tslen, pack, base_offset);
1213 	if (err)
1214 		return err;
1215 
1216 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
1217 	    base_tslen, base_type, base_size, recursion - 1);
1218 }
1219 
1220 const struct got_error *
1221 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
1222     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
1223     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
1224 {
1225 	const struct got_error *err = NULL;
1226 
1227 	if (--recursion == 0)
1228 		return got_error(GOT_ERR_RECURSION);
1229 
1230 	switch (delta_type) {
1231 	case GOT_OBJ_TYPE_COMMIT:
1232 	case GOT_OBJ_TYPE_TREE:
1233 	case GOT_OBJ_TYPE_BLOB:
1234 	case GOT_OBJ_TYPE_TAG:
1235 		/* Plain types are the final delta base. Recursion ends. */
1236 		err = add_delta(deltas, delta_offset, tslen, delta_type,
1237 		    delta_size, 0);
1238 		break;
1239 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1240 		err = resolve_offset_delta(deltas, packidx, pack,
1241 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1242 		break;
1243 	case GOT_OBJ_TYPE_REF_DELTA:
1244 		err = resolve_ref_delta(deltas, packidx, pack,
1245 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
1246 		break;
1247 	default:
1248 		return got_error(GOT_ERR_OBJ_TYPE);
1249 	}
1250 
1251 	return err;
1252 }
1253 
1254 static const struct got_error *
1255 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
1256     struct got_pack *pack, struct got_object_id *id, off_t offset,
1257     size_t tslen, int delta_type, size_t delta_size, int idx)
1258 {
1259 	const struct got_error *err = NULL;
1260 	int resolved_type;
1261 
1262 	*obj = calloc(1, sizeof(**obj));
1263 	if (*obj == NULL)
1264 		return got_error_from_errno("calloc");
1265 
1266 	(*obj)->flags = 0;
1267 	(*obj)->hdrlen = 0;
1268 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
1269 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
1270 	(*obj)->pack_offset = offset + tslen;
1271 
1272 	STAILQ_INIT(&(*obj)->deltas.entries);
1273 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
1274 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
1275 	(*obj)->pack_idx = idx;
1276 
1277 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
1278 	    offset, tslen, delta_type, delta_size,
1279 	    GOT_DELTA_CHAIN_RECURSION_MAX);
1280 	if (err)
1281 		goto done;
1282 
1283 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
1284 	if (err)
1285 		goto done;
1286 	(*obj)->type = resolved_type;
1287 done:
1288 	if (err) {
1289 		got_object_close(*obj);
1290 		*obj = NULL;
1291 	}
1292 	return err;
1293 }
1294 
1295 const struct got_error *
1296 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
1297     struct got_packidx *packidx, int idx, struct got_object_id *id)
1298 {
1299 	const struct got_error *err = NULL;
1300 	off_t offset;
1301 	uint8_t type;
1302 	uint64_t size;
1303 	size_t tslen;
1304 
1305 	*obj = NULL;
1306 
1307 	offset = got_packidx_get_object_offset(packidx, idx);
1308 	if (offset == -1)
1309 		return got_error(GOT_ERR_BAD_PACKIDX);
1310 
1311 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1312 	    pack, offset);
1313 	if (err)
1314 		return err;
1315 
1316 	switch (type) {
1317 	case GOT_OBJ_TYPE_COMMIT:
1318 	case GOT_OBJ_TYPE_TREE:
1319 	case GOT_OBJ_TYPE_BLOB:
1320 	case GOT_OBJ_TYPE_TAG:
1321 		err = open_plain_object(obj, id, type, offset + tslen,
1322 		    size, idx);
1323 		break;
1324 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1325 	case GOT_OBJ_TYPE_REF_DELTA:
1326 		err = open_delta_object(obj, packidx, pack, id, offset,
1327 		    tslen, type, size, idx);
1328 		break;
1329 	default:
1330 		err = got_error(GOT_ERR_OBJ_TYPE);
1331 		break;
1332 	}
1333 
1334 	return err;
1335 }
1336 
1337 const struct got_error *
1338 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1339     struct got_delta_chain *deltas, struct got_pack *pack)
1340 {
1341 	struct got_delta *delta;
1342 	uint64_t base_size = 0, result_size = 0;
1343 
1344 	*max_size = 0;
1345 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1346 		/* Plain object types are the delta base. */
1347 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1348 		    delta->type != GOT_OBJ_TYPE_TREE &&
1349 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1350 		    delta->type != GOT_OBJ_TYPE_TAG) {
1351 			const struct got_error *err;
1352 			uint8_t *delta_buf = NULL;
1353 			size_t delta_len;
1354 			int cached = 1;
1355 
1356 			if (pack->delta_cache) {
1357 				got_delta_cache_get(&delta_buf, &delta_len,
1358 				    pack->delta_cache, delta->data_offset);
1359 			}
1360 			if (delta_buf == NULL) {
1361 				cached = 0;
1362 				err = read_delta_data(&delta_buf, &delta_len,
1363 				    NULL, delta->data_offset, pack);
1364 				if (err)
1365 					return err;
1366 			}
1367 			if (pack->delta_cache && !cached) {
1368 				err = got_delta_cache_add(pack->delta_cache,
1369 				    delta->data_offset, delta_buf, delta_len);
1370 				if (err == NULL)
1371 					cached = 1;
1372 				else if (err->code != GOT_ERR_NO_SPACE) {
1373 					free(delta_buf);
1374 					return err;
1375 				}
1376 			}
1377 			err = got_delta_get_sizes(&base_size, &result_size,
1378 			    delta_buf, delta_len);
1379 			if (!cached)
1380 				free(delta_buf);
1381 			if (err)
1382 				return err;
1383 		} else
1384 			base_size = delta->size;
1385 		if (base_size > *max_size)
1386 			*max_size = base_size;
1387 		if (result_size > *max_size)
1388 			*max_size = result_size;
1389 	}
1390 
1391 	return NULL;
1392 }
1393 
1394 const struct got_error *
1395 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1396     struct got_pack *pack)
1397 {
1398 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1399 		return got_error(GOT_ERR_OBJ_TYPE);
1400 
1401 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1402 }
1403 
1404 const struct got_error *
1405 got_pack_dump_delta_chain_to_file(size_t *result_size,
1406     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1407     FILE *base_file, FILE *accum_file)
1408 {
1409 	const struct got_error *err = NULL;
1410 	struct got_delta *delta;
1411 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1412 	size_t base_bufsz = 0, accum_bufsz = 0, accum_size = 0, delta_len;
1413 	/* We process small enough files entirely in memory for speed. */
1414 	const size_t max_bufsize = GOT_DELTA_RESULT_SIZE_CACHED_MAX;
1415 	uint64_t max_size = 0;
1416 	int n = 0;
1417 
1418 	*result_size = 0;
1419 
1420 	if (STAILQ_EMPTY(&deltas->entries))
1421 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1422 
1423 	if (fseeko(base_file, 0L, SEEK_SET) == -1)
1424 		return got_error_from_errno("fseeko");
1425 	if (fseeko(accum_file, 0L, SEEK_SET) == -1)
1426 		return got_error_from_errno("fseeko");
1427 
1428 	/* Deltas are ordered in ascending order. */
1429 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1430 		uint8_t *delta_buf = NULL;
1431 		uint64_t base_size, result_size = 0;
1432 		int cached = 1;
1433 		if (n == 0) {
1434 			size_t mapoff;
1435 			off_t delta_data_offset;
1436 
1437 			/* Plain object types are the delta base. */
1438 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1439 			    delta->type != GOT_OBJ_TYPE_TREE &&
1440 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1441 			    delta->type != GOT_OBJ_TYPE_TAG) {
1442 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1443 				goto done;
1444 			}
1445 
1446 			delta_data_offset = delta->offset + delta->tslen;
1447 			if (delta_data_offset >= pack->filesize) {
1448 				err = got_error(GOT_ERR_PACK_OFFSET);
1449 				goto done;
1450 			}
1451 			if (pack->map == NULL) {
1452 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1453 				    == -1) {
1454 					err = got_error_from_errno("lseek");
1455 					goto done;
1456 				}
1457 			}
1458 			if (delta->size > max_size)
1459 				max_size = delta->size;
1460 			if (max_size > max_bufsize) {
1461 				if (pack->map) {
1462 					if (delta_data_offset > SIZE_MAX) {
1463 						return got_error_fmt(
1464 						    GOT_ERR_RANGE,
1465 						    "delta offset %lld "
1466 						    "overflows size_t",
1467 						    (long long)
1468 						    delta_data_offset);
1469 					}
1470 
1471 					mapoff = delta_data_offset;
1472 					err = got_inflate_to_file_mmap(
1473 					    &base_bufsz, NULL, NULL, pack->map,
1474 					    mapoff, pack->filesize - mapoff,
1475 					    base_file);
1476 				} else
1477 					err = got_inflate_to_file_fd(
1478 					    &base_bufsz, NULL, NULL, pack->fd,
1479 					    base_file);
1480 			} else {
1481 				accum_buf = malloc(max_size);
1482 				if (accum_buf == NULL) {
1483 					err = got_error_from_errno("malloc");
1484 					goto done;
1485 				}
1486 				accum_bufsz = max_size;
1487 				if (pack->map) {
1488 					if (delta_data_offset > SIZE_MAX) {
1489 						return got_error_fmt(
1490 						    GOT_ERR_RANGE,
1491 						    "delta offset %lld "
1492 						    "overflows size_t",
1493 						    (long long)
1494 						    delta_data_offset);
1495 					}
1496 
1497 					mapoff = delta_data_offset;
1498 					err = got_inflate_to_mem_mmap(&base_buf,
1499 					    &base_bufsz, NULL, NULL,
1500 					    pack->map, mapoff,
1501 					    pack->filesize - mapoff);
1502 				} else
1503 					err = got_inflate_to_mem_fd(&base_buf,
1504 					    &base_bufsz, NULL, NULL, max_size,
1505 					    pack->fd);
1506 			}
1507 			if (err)
1508 				goto done;
1509 			n++;
1510 			if (base_buf == NULL)
1511 				rewind(base_file);
1512 			continue;
1513 		}
1514 
1515 		if (pack->delta_cache) {
1516 			got_delta_cache_get(&delta_buf, &delta_len,
1517 			    pack->delta_cache, delta->data_offset);
1518 		}
1519 		if (delta_buf == NULL) {
1520 			cached = 0;
1521 			err = read_delta_data(&delta_buf, &delta_len, NULL,
1522 			    delta->data_offset, pack);
1523 			if (err)
1524 				goto done;
1525 		}
1526 		if (pack->delta_cache && !cached) {
1527 			err = got_delta_cache_add(pack->delta_cache,
1528 			    delta->data_offset, delta_buf, delta_len);
1529 			if (err == NULL)
1530 				cached = 1;
1531 			else if (err->code != GOT_ERR_NO_SPACE) {
1532 				free(delta_buf);
1533 				goto done;
1534 			}
1535 		}
1536 
1537 		err = got_delta_get_sizes(&base_size, &result_size,
1538 		    delta_buf, delta_len);
1539 		if (err) {
1540 			if (!cached)
1541 				free(delta_buf);
1542 			goto done;
1543 		}
1544 		if (base_size > max_size)
1545 			max_size = base_size;
1546 		if (result_size > max_size)
1547 			max_size = result_size;
1548 
1549 		if (base_buf && max_size > max_bufsize) {
1550 			/* Switch from buffers to temporary files. */
1551 			size_t w = fwrite(base_buf, 1, base_bufsz,
1552 			    base_file);
1553 			if (w != base_bufsz) {
1554 				err = got_ferror(outfile, GOT_ERR_IO);
1555 				if (!cached)
1556 					free(delta_buf);
1557 				goto done;
1558 			}
1559 			free(base_buf);
1560 			base_buf = NULL;
1561 			free(accum_buf);
1562 			accum_buf = NULL;
1563 		}
1564 
1565 		if (base_buf && max_size > base_bufsz) {
1566 			uint8_t *p = realloc(base_buf, max_size);
1567 			if (p == NULL) {
1568 				err = got_error_from_errno("realloc");
1569 				if (!cached)
1570 					free(delta_buf);
1571 				goto done;
1572 			}
1573 			base_buf = p;
1574 			base_bufsz = max_size;
1575 		}
1576 
1577 		if (accum_buf && max_size > accum_bufsz) {
1578 			uint8_t *p = realloc(accum_buf, max_size);
1579 			if (p == NULL) {
1580 				err = got_error_from_errno("realloc");
1581 				if (!cached)
1582 					free(delta_buf);
1583 				goto done;
1584 			}
1585 			accum_buf = p;
1586 			accum_bufsz = max_size;
1587 		}
1588 
1589 		if (base_buf) {
1590 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1591 			    delta_buf, delta_len, accum_buf,
1592 			    &accum_size, max_size);
1593 			n++;
1594 		} else {
1595 			err = got_delta_apply(base_file, delta_buf,
1596 			    delta_len,
1597 			    /* Final delta application writes to output file. */
1598 			    ++n < deltas->nentries ? accum_file : outfile,
1599 			    &accum_size);
1600 		}
1601 		if (!cached)
1602 			free(delta_buf);
1603 		if (err)
1604 			goto done;
1605 
1606 		if (n < deltas->nentries) {
1607 			/* Accumulated delta becomes the new base. */
1608 			if (base_buf) {
1609 				uint8_t *tmp = accum_buf;
1610 				size_t tmp_size = accum_bufsz;
1611 				accum_buf = base_buf;
1612 				accum_bufsz = base_bufsz;
1613 				base_buf = tmp;
1614 				base_bufsz = tmp_size;
1615 			} else {
1616 				FILE *tmp = accum_file;
1617 				accum_file = base_file;
1618 				base_file = tmp;
1619 				rewind(base_file);
1620 				rewind(accum_file);
1621 			}
1622 		}
1623 	}
1624 
1625 done:
1626 	free(base_buf);
1627 	if (accum_buf) {
1628 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1629 		free(accum_buf);
1630 		if (len != accum_size)
1631 			err = got_ferror(outfile, GOT_ERR_IO);
1632 	}
1633 	rewind(outfile);
1634 	if (err == NULL)
1635 		*result_size = accum_size;
1636 	return err;
1637 }
1638 
1639 const struct got_error *
1640 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1641     struct got_delta_chain *deltas, struct got_pack *pack)
1642 {
1643 	const struct got_error *err = NULL;
1644 	struct got_delta *delta;
1645 	uint8_t *base_buf = NULL, *accum_buf = NULL;
1646 	size_t base_bufsz = 0, accum_bufsz = 0, accum_size = 0, delta_len;
1647 	uint64_t max_size = 0;
1648 	int n = 0;
1649 
1650 	*outbuf = NULL;
1651 	*outlen = 0;
1652 
1653 	if (STAILQ_EMPTY(&deltas->entries))
1654 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1655 
1656 	/* Deltas are ordered in ascending order. */
1657 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1658 		uint8_t *delta_buf = NULL;
1659 		uint64_t base_size, result_size = 0;
1660 		int cached = 1;
1661 		if (n == 0) {
1662 			off_t delta_data_offset;
1663 
1664 			/* Plain object types are the delta base. */
1665 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1666 			    delta->type != GOT_OBJ_TYPE_TREE &&
1667 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1668 			    delta->type != GOT_OBJ_TYPE_TAG) {
1669 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1670 				goto done;
1671 			}
1672 
1673 			delta_data_offset = delta->offset + delta->tslen;
1674 			if (delta_data_offset >= pack->filesize) {
1675 				err = got_error(GOT_ERR_PACK_OFFSET);
1676 				goto done;
1677 			}
1678 
1679 			if (delta->size > max_size)
1680 				max_size = delta->size;
1681 
1682 			if (pack->map) {
1683 				size_t mapoff;
1684 
1685 				if (delta_data_offset > SIZE_MAX) {
1686 					return got_error_fmt(GOT_ERR_RANGE,
1687 					    "delta %lld offset would "
1688 					    "overflow size_t",
1689 					    (long long)delta_data_offset);
1690 				}
1691 
1692 				mapoff = delta_data_offset;
1693 				err = got_inflate_to_mem_mmap(&base_buf,
1694 				    &base_bufsz, NULL, NULL, pack->map,
1695 				    mapoff, pack->filesize - mapoff);
1696 			} else {
1697 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1698 				    == -1) {
1699 					err = got_error_from_errno("lseek");
1700 					goto done;
1701 				}
1702 				err = got_inflate_to_mem_fd(&base_buf,
1703 				    &base_bufsz, NULL, NULL, max_size,
1704 				    pack->fd);
1705 			}
1706 			if (err)
1707 				goto done;
1708 			n++;
1709 			continue;
1710 		}
1711 
1712 		if (pack->delta_cache) {
1713 			got_delta_cache_get(&delta_buf, &delta_len,
1714 			    pack->delta_cache, delta->data_offset);
1715 		}
1716 		if (delta_buf == NULL) {
1717 			cached = 0;
1718 			err = read_delta_data(&delta_buf, &delta_len, NULL,
1719 			    delta->data_offset, pack);
1720 			if (err)
1721 				goto done;
1722 		}
1723 		if (pack->delta_cache && !cached) {
1724 			err = got_delta_cache_add(pack->delta_cache,
1725 			    delta->data_offset, delta_buf, delta_len);
1726 			if (err == NULL)
1727 				cached = 1;
1728 			else if (err->code != GOT_ERR_NO_SPACE) {
1729 				free(delta_buf);
1730 				goto done;
1731 			}
1732 		}
1733 
1734 		err = got_delta_get_sizes(&base_size, &result_size,
1735 		    delta_buf, delta_len);
1736 		if (err) {
1737 			if (!cached)
1738 				free(delta_buf);
1739 			goto done;
1740 		}
1741 		if (base_size > max_size)
1742 			max_size = base_size;
1743 		if (result_size > max_size)
1744 			max_size = result_size;
1745 
1746 		if (max_size > base_bufsz) {
1747 			uint8_t *p = realloc(base_buf, max_size);
1748 			if (p == NULL) {
1749 				err = got_error_from_errno("realloc");
1750 				if (!cached)
1751 					free(delta_buf);
1752 				goto done;
1753 			}
1754 			base_buf = p;
1755 			base_bufsz = max_size;
1756 		}
1757 
1758 		if (max_size > accum_bufsz) {
1759 			uint8_t *p = realloc(accum_buf, max_size);
1760 			if (p == NULL) {
1761 				err = got_error_from_errno("realloc");
1762 				if (!cached)
1763 					free(delta_buf);
1764 				goto done;
1765 			}
1766 			accum_buf = p;
1767 			accum_bufsz = max_size;
1768 		}
1769 
1770 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1771 		    delta_buf, delta_len, accum_buf,
1772 		    &accum_size, max_size);
1773 		if (!cached)
1774 			free(delta_buf);
1775 		n++;
1776 		if (err)
1777 			goto done;
1778 
1779 		if (n < deltas->nentries) {
1780 			/* Accumulated delta becomes the new base. */
1781 			uint8_t *tmp = accum_buf;
1782 			size_t tmp_size = accum_bufsz;
1783 			accum_buf = base_buf;
1784 			accum_bufsz = base_bufsz;
1785 			base_buf = tmp;
1786 			base_bufsz = tmp_size;
1787 		}
1788 	}
1789 
1790 done:
1791 	free(base_buf);
1792 	if (err) {
1793 		free(accum_buf);
1794 		*outbuf = NULL;
1795 		*outlen = 0;
1796 	} else {
1797 		*outbuf = accum_buf;
1798 		*outlen = accum_size;
1799 	}
1800 	return err;
1801 }
1802 
1803 const struct got_error *
1804 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1805     FILE *outfile, FILE *base_file, FILE *accum_file)
1806 {
1807 	const struct got_error *err = NULL;
1808 
1809 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1810 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1811 
1812 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1813 		if (obj->pack_offset >= pack->filesize)
1814 			return got_error(GOT_ERR_PACK_OFFSET);
1815 
1816 		if (pack->map) {
1817 			size_t mapoff;
1818 
1819 			if (obj->pack_offset > SIZE_MAX) {
1820 				return got_error_fmt(GOT_ERR_RANGE,
1821 				    "pack offset %lld would overflow size_t",
1822 				    (long long)obj->pack_offset);
1823 			}
1824 
1825 			mapoff = obj->pack_offset;
1826 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1827 			    pack->map, mapoff, pack->filesize - mapoff,
1828 			    outfile);
1829 		} else {
1830 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1831 				return got_error_from_errno("lseek");
1832 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1833 			    pack->fd, outfile);
1834 		}
1835 	} else
1836 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1837 		    &obj->deltas, pack, outfile, base_file, accum_file);
1838 
1839 	return err;
1840 }
1841 
1842 const struct got_error *
1843 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1844     struct got_object *obj, struct got_pack *pack)
1845 {
1846 	const struct got_error *err = NULL;
1847 
1848 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1849 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1850 
1851 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1852 		if (obj->pack_offset >= pack->filesize)
1853 			return got_error(GOT_ERR_PACK_OFFSET);
1854 		if (pack->map) {
1855 			size_t mapoff;
1856 
1857 			if (obj->pack_offset > SIZE_MAX) {
1858 				return got_error_fmt(GOT_ERR_RANGE,
1859 				    "pack offset %lld would overflow size_t",
1860 				    (long long)obj->pack_offset);
1861 			}
1862 
1863 			mapoff = obj->pack_offset;
1864 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1865 			    pack->map, mapoff, pack->filesize - mapoff);
1866 		} else {
1867 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1868 				return got_error_from_errno("lseek");
1869 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1870 			    obj->size, pack->fd);
1871 		}
1872 	} else
1873 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1874 		    pack);
1875 
1876 	return err;
1877 }
1878 
1879 static const struct got_error *
1880 read_raw_delta_data(uint8_t **delta_buf, size_t *delta_len,
1881     size_t *delta_len_compressed, uint64_t *base_size, uint64_t *result_size,
1882     off_t delta_data_offset, struct got_pack *pack, struct got_packidx *packidx)
1883 {
1884 	const struct got_error *err = NULL;
1885 
1886 	/* Validate decompression and obtain the decompressed size. */
1887 	err = read_delta_data(delta_buf, delta_len, delta_len_compressed,
1888 	    delta_data_offset, pack);
1889 	if (err)
1890 		return err;
1891 
1892 	/* Read delta base/result sizes from head of delta stream. */
1893 	err = got_delta_get_sizes(base_size, result_size,
1894 	    *delta_buf, *delta_len);
1895 	if (err)
1896 		goto done;
1897 
1898 	/* Discard decompressed delta and read it again in compressed form. */
1899 	free(*delta_buf);
1900 	*delta_buf = malloc(*delta_len_compressed);
1901 	if (*delta_buf == NULL) {
1902 		err = got_error_from_errno("malloc");
1903 		goto done;
1904 	}
1905 	if (pack->map) {
1906 		if (delta_data_offset >= pack->filesize) {
1907 			err = got_error(GOT_ERR_PACK_OFFSET);
1908 			goto done;
1909 		}
1910 		memcpy(*delta_buf, pack->map + delta_data_offset,
1911 		    *delta_len_compressed);
1912 	} else {
1913 		ssize_t n;
1914 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1) {
1915 			err = got_error_from_errno("lseek");
1916 			goto done;
1917 		}
1918 		n = read(pack->fd, *delta_buf, *delta_len_compressed);
1919 		if (n < 0) {
1920 			err = got_error_from_errno("read");
1921 			goto done;
1922 		} else if (n != *delta_len_compressed) {
1923 			err = got_error(GOT_ERR_IO);
1924 			goto done;
1925 		}
1926 	}
1927 done:
1928 	if (err) {
1929 		free(*delta_buf);
1930 		*delta_buf = NULL;
1931 		*delta_len = 0;
1932 		*delta_len_compressed = 0;
1933 		*base_size = 0;
1934 		*result_size = 0;
1935 	}
1936 	return err;
1937 }
1938 
1939 const struct got_error *
1940 got_packfile_extract_raw_delta(uint8_t **delta_buf, size_t *delta_size,
1941     size_t *delta_compressed_size, off_t *delta_offset,
1942     off_t *delta_data_offset, off_t *base_offset,
1943     struct got_object_id *base_id, uint64_t *base_size, uint64_t *result_size,
1944     struct got_pack *pack, struct got_packidx *packidx, int idx)
1945 {
1946 	const struct got_error *err = NULL;
1947 	off_t offset;
1948 	uint8_t type;
1949 	uint64_t size;
1950 	size_t tslen, delta_hdrlen;
1951 
1952 	*delta_buf = NULL;
1953 	*delta_size = 0;
1954 	*delta_compressed_size = 0;
1955 	*delta_offset = 0;
1956 	*delta_data_offset = 0;
1957 	*base_offset = 0;
1958 	*base_size = 0;
1959 	*result_size = 0;
1960 
1961 	offset = got_packidx_get_object_offset(packidx, idx);
1962 	if (offset == -1)
1963 		return got_error(GOT_ERR_BAD_PACKIDX);
1964 
1965 	if (offset >= pack->filesize)
1966 		return got_error(GOT_ERR_PACK_OFFSET);
1967 
1968 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1969 	    pack, offset);
1970 	if (err)
1971 		return err;
1972 
1973 	if (tslen + size < tslen || offset + size < size ||
1974 	    tslen + offset < tslen)
1975 		return got_error(GOT_ERR_PACK_OFFSET);
1976 
1977 	switch (type) {
1978 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1979 		err = got_pack_parse_offset_delta(base_offset, &delta_hdrlen,
1980 		    pack, offset, tslen);
1981 		if (err)
1982 			return err;
1983 		break;
1984 	case GOT_OBJ_TYPE_REF_DELTA:
1985 		err = got_pack_parse_ref_delta(base_id, pack, offset, tslen);
1986 		if (err)
1987 			return err;
1988 		delta_hdrlen = SHA1_DIGEST_LENGTH;
1989 		break;
1990 	default:
1991 		return got_error_fmt(GOT_ERR_OBJ_TYPE,
1992 		    "non-delta object type %d found at offset %lld",
1993 		    type, (long long)offset);
1994 	}
1995 
1996 	if (tslen + delta_hdrlen < delta_hdrlen ||
1997 	    offset + delta_hdrlen < delta_hdrlen)
1998 		return got_error(GOT_ERR_BAD_DELTA);
1999 
2000 	*delta_data_offset = offset + tslen + delta_hdrlen;
2001 	err = read_raw_delta_data(delta_buf, delta_size, delta_compressed_size,
2002 	    base_size, result_size, *delta_data_offset, pack, packidx);
2003 	if (err)
2004 		return err;
2005 
2006 	if (*delta_size != size) {
2007 		err = got_error(GOT_ERR_BAD_DELTA);
2008 		goto done;
2009 	}
2010 
2011 	*delta_offset = offset;
2012 done:
2013 	if (err) {
2014 		free(*delta_buf);
2015 		*delta_buf = NULL;
2016 		*delta_size = 0;
2017 		*delta_compressed_size = 0;
2018 		*delta_offset = 0;
2019 		*base_offset = 0;
2020 		*base_size = 0;
2021 		*result_size = 0;
2022 	}
2023 	return err;
2024 }