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Date:: Thu Jul 15 07:48:40 2021 UTC
Message:: don't scan pack index offsets for large values if pack file is < 2GB This saves an iteration over the entire h->offsets array when opening a pack index which should not contain large offsets in the first place. ok millert@
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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 
23 #include <fcntl.h>
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdint.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <limits.h>
30 #include <sha1.h>
31 #include <endian.h>
32 #include <unistd.h>
33 #include <zlib.h>
34 #include <imsg.h>
35 
36 #include "got_error.h"
37 #include "got_object.h"
38 #include "got_opentemp.h"
39 #include "got_path.h"
40 
41 #include "got_lib_sha1.h"
42 #include "got_lib_delta.h"
43 #include "got_lib_delta_cache.h"
44 #include "got_lib_inflate.h"
45 #include "got_lib_object.h"
46 #include "got_lib_object_parse.h"
47 #include "got_lib_privsep.h"
48 #include "got_lib_pack.h"
49 
50 #ifndef nitems
51 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
52 #endif
53 
54 #ifndef MIN
55 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
56 #endif
57 
58 static const struct got_error *
59 verify_fanout_table(uint32_t *fanout_table)
60 {
61 	int i;
62 
63 	for (i = 0; i < 0xff - 1; i++) {
64 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
65 			return got_error(GOT_ERR_BAD_PACKIDX);
66 	}
67 
68 	return NULL;
69 }
70 
71 const struct got_error *
72 got_packidx_init_hdr(struct got_packidx *p, int verify, off_t packfile_size)
73 {
74 	const struct got_error *err = NULL;
75 	struct got_packidx_v2_hdr *h;
76 	SHA1_CTX ctx;
77 	uint8_t sha1[SHA1_DIGEST_LENGTH];
78 	size_t nobj, len_fanout, len_ids, offset, remain;
79 	ssize_t n;
80 	int i;
81 
82 	SHA1Init(&ctx);
83 
84 	h = &p->hdr;
85 	offset = 0;
86 	remain = p->len;
87 
88 	if (remain < sizeof(*h->magic)) {
89 		err = got_error(GOT_ERR_BAD_PACKIDX);
90 		goto done;
91 	}
92 	if (p->map)
93 		h->magic = (uint32_t *)(p->map + offset);
94 	else {
95 		h->magic = malloc(sizeof(*h->magic));
96 		if (h->magic == NULL) {
97 			err = got_error_from_errno("malloc");
98 			goto done;
99 		}
100 		n = read(p->fd, h->magic, sizeof(*h->magic));
101 		if (n < 0) {
102 			err = got_error_from_errno("read");
103 			goto done;
104 		} else if (n != sizeof(*h->magic)) {
105 			err = got_error(GOT_ERR_BAD_PACKIDX);
106 			goto done;
107 		}
108 	}
109 	if (*h->magic != htobe32(GOT_PACKIDX_V2_MAGIC)) {
110 		err = got_error(GOT_ERR_BAD_PACKIDX);
111 		goto done;
112 	}
113 	offset += sizeof(*h->magic);
114 	remain -= sizeof(*h->magic);
115 
116 	if (verify)
117 		SHA1Update(&ctx, (uint8_t *)h->magic, sizeof(*h->magic));
118 
119 	if (remain < sizeof(*h->version)) {
120 		err = got_error(GOT_ERR_BAD_PACKIDX);
121 		goto done;
122 	}
123 	if (p->map)
124 		h->version = (uint32_t *)(p->map + offset);
125 	else {
126 		h->version = malloc(sizeof(*h->version));
127 		if (h->version == NULL) {
128 			err = got_error_from_errno("malloc");
129 			goto done;
130 		}
131 		n = read(p->fd, h->version, sizeof(*h->version));
132 		if (n < 0) {
133 			err = got_error_from_errno("read");
134 			goto done;
135 		} else if (n != sizeof(*h->version)) {
136 			err = got_error(GOT_ERR_BAD_PACKIDX);
137 			goto done;
138 		}
139 	}
140 	if (*h->version != htobe32(GOT_PACKIDX_VERSION)) {
141 		err = got_error(GOT_ERR_BAD_PACKIDX);
142 		goto done;
143 	}
144 	offset += sizeof(*h->version);
145 	remain -= sizeof(*h->version);
146 
147 	if (verify)
148 		SHA1Update(&ctx, (uint8_t *)h->version, sizeof(*h->version));
149 
150 	len_fanout =
151 	    sizeof(*h->fanout_table) * GOT_PACKIDX_V2_FANOUT_TABLE_ITEMS;
152 	if (remain < len_fanout) {
153 		err = got_error(GOT_ERR_BAD_PACKIDX);
154 		goto done;
155 	}
156 	if (p->map)
157 		h->fanout_table = (uint32_t *)(p->map + offset);
158 	else {
159 		h->fanout_table = malloc(len_fanout);
160 		if (h->fanout_table == NULL) {
161 			err = got_error_from_errno("malloc");
162 			goto done;
163 		}
164 		n = read(p->fd, h->fanout_table, len_fanout);
165 		if (n < 0) {
166 			err = got_error_from_errno("read");
167 			goto done;
168 		} else if (n != len_fanout) {
169 			err = got_error(GOT_ERR_BAD_PACKIDX);
170 			goto done;
171 		}
172 	}
173 	err = verify_fanout_table(h->fanout_table);
174 	if (err)
175 		goto done;
176 	if (verify)
177 		SHA1Update(&ctx, (uint8_t *)h->fanout_table, len_fanout);
178 	offset += len_fanout;
179 	remain -= len_fanout;
180 
181 	nobj = be32toh(h->fanout_table[0xff]);
182 	len_ids = nobj * sizeof(*h->sorted_ids);
183 	if (len_ids <= nobj || len_ids > remain) {
184 		err = got_error(GOT_ERR_BAD_PACKIDX);
185 		goto done;
186 	}
187 	if (p->map)
188 		h->sorted_ids =
189 		    (struct got_packidx_object_id *)((uint8_t*)(p->map + offset));
190 	else {
191 		h->sorted_ids = malloc(len_ids);
192 		if (h->sorted_ids == NULL) {
193 			err = got_error(GOT_ERR_BAD_PACKIDX);
194 			goto done;
195 		}
196 		n = read(p->fd, h->sorted_ids, len_ids);
197 		if (n < 0)
198 			err = got_error_from_errno("read");
199 		else if (n != len_ids) {
200 			err = got_error(GOT_ERR_BAD_PACKIDX);
201 			goto done;
202 		}
203 	}
204 	if (verify)
205 		SHA1Update(&ctx, (uint8_t *)h->sorted_ids, len_ids);
206 	offset += len_ids;
207 	remain -= len_ids;
208 
209 	if (remain < nobj * sizeof(*h->crc32)) {
210 		err = got_error(GOT_ERR_BAD_PACKIDX);
211 		goto done;
212 	}
213 	if (p->map)
214 		h->crc32 = (uint32_t *)((uint8_t*)(p->map + offset));
215 	else {
216 		h->crc32 = malloc(nobj * sizeof(*h->crc32));
217 		if (h->crc32 == NULL) {
218 			err = got_error_from_errno("malloc");
219 			goto done;
220 		}
221 		n = read(p->fd, h->crc32, nobj * sizeof(*h->crc32));
222 		if (n < 0)
223 			err = got_error_from_errno("read");
224 		else if (n != nobj * sizeof(*h->crc32)) {
225 			err = got_error(GOT_ERR_BAD_PACKIDX);
226 			goto done;
227 		}
228 	}
229 	if (verify)
230 		SHA1Update(&ctx, (uint8_t *)h->crc32, nobj * sizeof(*h->crc32));
231 	remain -= nobj * sizeof(*h->crc32);
232 	offset += nobj * sizeof(*h->crc32);
233 
234 	if (remain < nobj * sizeof(*h->offsets)) {
235 		err = got_error(GOT_ERR_BAD_PACKIDX);
236 		goto done;
237 	}
238 	if (p->map)
239 		h->offsets = (uint32_t *)((uint8_t*)(p->map + offset));
240 	else {
241 		h->offsets = malloc(nobj * sizeof(*h->offsets));
242 		if (h->offsets == NULL) {
243 			err = got_error_from_errno("malloc");
244 			goto done;
245 		}
246 		n = read(p->fd, h->offsets, nobj * sizeof(*h->offsets));
247 		if (n < 0)
248 			err = got_error_from_errno("read");
249 		else if (n != nobj * sizeof(*h->offsets)) {
250 			err = got_error(GOT_ERR_BAD_PACKIDX);
251 			goto done;
252 		}
253 	}
254 	if (verify)
255 		SHA1Update(&ctx, (uint8_t *)h->offsets,
256 		    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 		SHA1Update(&ctx, (uint8_t*)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 < sizeof(*h->trailer)) {
305 		err = got_error(GOT_ERR_BAD_PACKIDX);
306 		goto done;
307 	}
308 	if (p->map)
309 		h->trailer =
310 		    (struct got_packidx_trailer *)((uint8_t*)(p->map + offset));
311 	else {
312 		h->trailer = malloc(sizeof(*h->trailer));
313 		if (h->trailer == NULL) {
314 			err = got_error_from_errno("malloc");
315 			goto done;
316 		}
317 		n = read(p->fd, h->trailer, sizeof(*h->trailer));
318 		if (n < 0)
319 			err = got_error_from_errno("read");
320 		else if (n != sizeof(*h->trailer)) {
321 			err = got_error(GOT_ERR_BAD_PACKIDX);
322 			goto done;
323 		}
324 	}
325 	if (verify) {
326 		SHA1Update(&ctx, h->trailer->packfile_sha1, SHA1_DIGEST_LENGTH);
327 		SHA1Final(sha1, &ctx);
328 		if (memcmp(h->trailer->packidx_sha1, sha1,
329 		    SHA1_DIGEST_LENGTH) != 0)
330 			err = got_error(GOT_ERR_PACKIDX_CSUM);
331 	}
332 done:
333 	return err;
334 }
335 
336 const struct got_error *
337 got_packidx_open(struct got_packidx **packidx,
338     int dir_fd, const char *relpath, int verify)
339 {
340 	const struct got_error *err = NULL;
341 	struct got_packidx *p = NULL;
342 	char *pack_relpath;
343 	struct stat idx_sb, pack_sb;
344 
345 	*packidx = NULL;
346 
347 	err = got_packidx_get_packfile_path(&pack_relpath, relpath);
348 	if (err)
349 		return err;
350 
351 	/*
352 	 * Ensure that a corresponding pack file exists.
353 	 * Some Git repositories have this problem. Git seems to ignore
354 	 * the existence of lonely pack index files but we do not.
355 	 */
356 	if (fstatat(dir_fd, pack_relpath, &pack_sb, 0) == -1) {
357 		if (errno == ENOENT) {
358 			err = got_error_fmt(GOT_ERR_LONELY_PACKIDX,
359 			    "%s", relpath);
360 		} else
361 			err = got_error_from_errno2("fstatat", pack_relpath);
362 		goto done;
363 	}
364 
365 	p = calloc(1, sizeof(*p));
366 	if (p == NULL) {
367 		err = got_error_from_errno("calloc");
368 		goto done;
369 	}
370 
371 	p->fd = openat(dir_fd, relpath, O_RDONLY | O_NOFOLLOW);
372 	if (p->fd == -1) {
373 		err = got_error_from_errno2("openat", relpath);
374 		free(p);
375 		goto done;
376 	}
377 
378 	if (fstat(p->fd, &idx_sb) != 0) {
379 		err = got_error_from_errno2("fstat", relpath);
380 		close(p->fd);
381 		free(p);
382 		goto done;
383 	}
384 	p->len = idx_sb.st_size;
385 	if (p->len < sizeof(p->hdr)) {
386 		err = got_error(GOT_ERR_BAD_PACKIDX);
387 		close(p->fd);
388 		free(p);
389 		goto done;
390 	}
391 
392 	p->path_packidx = strdup(relpath);
393 	if (p->path_packidx == NULL) {
394 		err = got_error_from_errno("strdup");
395 		goto done;
396 	}
397 
398 #ifndef GOT_PACK_NO_MMAP
399 	p->map = mmap(NULL, p->len, PROT_READ, MAP_PRIVATE, p->fd, 0);
400 	if (p->map == MAP_FAILED) {
401 		if (errno != ENOMEM) {
402 			err = got_error_from_errno("mmap");
403 			goto done;
404 		}
405 		p->map = NULL; /* fall back to read(2) */
406 	}
407 #endif
408 
409 	err = got_packidx_init_hdr(p, verify, pack_sb.st_size);
410 done:
411 	if (err) {
412 		if (p)
413 			got_packidx_close(p);
414 	} else
415 		*packidx = p;
416 	free(pack_relpath);
417 	return err;
418 }
419 
420 const struct got_error *
421 got_packidx_close(struct got_packidx *packidx)
422 {
423 	const struct got_error *err = NULL;
424 
425 	free(packidx->path_packidx);
426 	if (packidx->map) {
427 		if (munmap(packidx->map, packidx->len) == -1)
428 			err = got_error_from_errno("munmap");
429 	} else {
430 		free(packidx->hdr.magic);
431 		free(packidx->hdr.version);
432 		free(packidx->hdr.fanout_table);
433 		free(packidx->hdr.sorted_ids);
434 		free(packidx->hdr.crc32);
435 		free(packidx->hdr.offsets);
436 		free(packidx->hdr.large_offsets);
437 		free(packidx->hdr.trailer);
438 	}
439 	if (close(packidx->fd) == -1 && err == NULL)
440 		err = got_error_from_errno("close");
441 	free(packidx);
442 
443 	return err;
444 }
445 
446 const struct got_error *
447 got_packidx_get_packfile_path(char **path_packfile, const char *path_packidx)
448 {
449 	size_t size;
450 
451 	/* Packfile path contains ".pack" instead of ".idx", so add one byte. */
452 	size = strlen(path_packidx) + 2;
453 	if (size < GOT_PACKFILE_NAMELEN + 1)
454 		return got_error_path(path_packidx, GOT_ERR_BAD_PATH);
455 
456 	*path_packfile = malloc(size);
457 	if (*path_packfile == NULL)
458 		return got_error_from_errno("malloc");
459 
460 	/* Copy up to and excluding ".idx". */
461 	if (strlcpy(*path_packfile, path_packidx,
462 	    size - strlen(GOT_PACKIDX_SUFFIX) - 1) >= size)
463 		return got_error(GOT_ERR_NO_SPACE);
464 
465 	if (strlcat(*path_packfile, GOT_PACKFILE_SUFFIX, size) >= size)
466 		return got_error(GOT_ERR_NO_SPACE);
467 
468 	return NULL;
469 }
470 
471 off_t
472 got_packidx_get_object_offset(struct got_packidx *packidx, int idx)
473 {
474 	uint32_t offset = be32toh(packidx->hdr.offsets[idx]);
475 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
476 		uint64_t loffset;
477 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
478 		if (idx < 0 || idx >= packidx->nlargeobj ||
479 		    packidx->hdr.large_offsets == NULL)
480 			return -1;
481 		loffset = be64toh(packidx->hdr.large_offsets[idx]);
482 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
483 	}
484 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
485 }
486 
487 int
488 got_packidx_get_object_idx(struct got_packidx *packidx, struct got_object_id *id)
489 {
490 	u_int8_t id0 = id->sha1[0];
491 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
492 	int left = 0, right = totobj - 1;
493 
494 	if (id0 > 0)
495 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
496 
497 	while (left <= right) {
498 		struct got_packidx_object_id *oid;
499 		int i, cmp;
500 
501 		i = ((left + right) / 2);
502 		oid = &packidx->hdr.sorted_ids[i];
503 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
504 		if (cmp == 0)
505 			return i;
506 		else if (cmp > 0)
507 			left = i + 1;
508 		else if (cmp < 0)
509 			right = i - 1;
510 	}
511 
512 	return -1;
513 }
514 
515 const struct got_error *
516 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
517     struct got_packidx *packidx, const char *id_str_prefix)
518 {
519 	const struct got_error *err = NULL;
520 	u_int8_t id0;
521 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
522 	char hex[3];
523 	size_t prefix_len = strlen(id_str_prefix);
524 	struct got_packidx_object_id *oid;
525 	uint32_t i;
526 
527 	STAILQ_INIT(matched_ids);
528 
529 	if (prefix_len < 2)
530 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
531 
532 	hex[0] = id_str_prefix[0];
533 	hex[1] = id_str_prefix[1];
534 	hex[2] = '\0';
535 	if (!got_parse_xdigit(&id0, hex))
536 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
537 
538 	i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
539 	oid = &packidx->hdr.sorted_ids[i];
540 	while (i < totobj && oid->sha1[0] == id0) {
541 		char id_str[SHA1_DIGEST_STRING_LENGTH];
542 		struct got_object_qid *qid;
543 		int cmp;
544 
545 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
546 		        return got_error(GOT_ERR_NO_SPACE);
547 
548 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
549 		if (cmp < 0) {
550 			oid = &packidx->hdr.sorted_ids[++i];
551 			continue;
552 		} else if (cmp > 0)
553 			break;
554 
555 		err = got_object_qid_alloc_partial(&qid);
556 		if (err)
557 			break;
558 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
559 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
560 
561 		oid = &packidx->hdr.sorted_ids[++i];
562 	}
563 
564 	if (err)
565 		got_object_id_queue_free(matched_ids);
566 	return err;
567 }
568 
569 static const struct got_error *
570 pack_stop_privsep_child(struct got_pack *pack)
571 {
572 	const struct got_error *err = NULL;
573 
574 	if (pack->privsep_child == NULL)
575 		return NULL;
576 
577 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
578 	if (err)
579 		return err;
580 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
581 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
582 		err = got_error_from_errno("close");
583 	imsg_clear(pack->privsep_child->ibuf);
584 	free(pack->privsep_child->ibuf);
585 	free(pack->privsep_child);
586 	pack->privsep_child = NULL;
587 	return err;
588 }
589 
590 const struct got_error *
591 got_pack_close(struct got_pack *pack)
592 {
593 	const struct got_error *err = NULL;
594 
595 	err = pack_stop_privsep_child(pack);
596 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
597 		err = got_error_from_errno("munmap");
598 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
599 		err = got_error_from_errno("close");
600 	pack->fd = -1;
601 	free(pack->path_packfile);
602 	pack->path_packfile = NULL;
603 	pack->filesize = 0;
604 	if (pack->delta_cache) {
605 		got_delta_cache_free(pack->delta_cache);
606 		pack->delta_cache = NULL;
607 	}
608 
609 	return err;
610 }
611 
612 const struct got_error *
613 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
614     struct got_pack *pack, off_t offset)
615 {
616 	uint8_t t = 0;
617 	uint64_t s = 0;
618 	uint8_t sizeN;
619 	size_t mapoff = 0;
620 	int i = 0;
621 
622 	*len = 0;
623 
624 	if (offset >= pack->filesize)
625 		return got_error(GOT_ERR_PACK_OFFSET);
626 
627 	if (pack->map) {
628 		mapoff = (size_t)offset;
629 	} else {
630 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
631 			return got_error_from_errno("lseek");
632 	}
633 
634 	do {
635 		/* We do not support size values which don't fit in 64 bit. */
636 		if (i > 9)
637 			return got_error(GOT_ERR_NO_SPACE);
638 
639 		if (pack->map) {
640 			sizeN = *(pack->map + mapoff);
641 			mapoff += sizeof(sizeN);
642 		} else {
643 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
644 			if (n < 0)
645 				return got_error_from_errno("read");
646 			if (n != sizeof(sizeN))
647 				return got_error(GOT_ERR_BAD_PACKFILE);
648 		}
649 		*len += sizeof(sizeN);
650 
651 		if (i == 0) {
652 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
653 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
654 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
655 		} else {
656 			size_t shift = 4 + 7 * (i - 1);
657 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
658 		}
659 		i++;
660 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
661 
662 	*type = t;
663 	*size = s;
664 	return NULL;
665 }
666 
667 static const struct got_error *
668 open_plain_object(struct got_object **obj, struct got_object_id *id,
669     uint8_t type, off_t offset, size_t size, int idx)
670 {
671 	*obj = calloc(1, sizeof(**obj));
672 	if (*obj == NULL)
673 		return got_error_from_errno("calloc");
674 
675 	(*obj)->type = type;
676 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
677 	(*obj)->pack_idx = idx;
678 	(*obj)->hdrlen = 0;
679 	(*obj)->size = size;
680 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
681 	(*obj)->pack_offset = offset;
682 
683 	return NULL;
684 }
685 
686 static const struct got_error *
687 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
688     off_t delta_offset)
689 {
690 	int64_t o = 0;
691 	uint8_t offN;
692 	int i = 0;
693 
694 	*offset = 0;
695 	*len = 0;
696 
697 	do {
698 		/* We do not support offset values which don't fit in 64 bit. */
699 		if (i > 8)
700 			return got_error(GOT_ERR_NO_SPACE);
701 
702 		if (pack->map) {
703 			size_t mapoff;
704 			if (delta_offset >= pack->filesize)
705 				return got_error(GOT_ERR_PACK_OFFSET);
706 			mapoff = (size_t)delta_offset + *len;
707 			offN = *(pack->map + mapoff);
708 		} else {
709 			ssize_t n;
710 			n = read(pack->fd, &offN, sizeof(offN));
711 			if (n < 0)
712 				return got_error_from_errno("read");
713 			if (n != sizeof(offN))
714 				return got_error(GOT_ERR_BAD_PACKFILE);
715 		}
716 		*len += sizeof(offN);
717 
718 		if (i == 0)
719 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
720 		else {
721 			o++;
722 			o <<= 7;
723 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
724 		}
725 		i++;
726 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
727 
728 	*offset = o;
729 	return NULL;
730 }
731 
732 const struct got_error *
733 got_pack_parse_offset_delta(off_t *base_offset, size_t *len, struct got_pack *pack,
734     off_t offset, int tslen)
735 {
736 	const struct got_error *err;
737 	int64_t negoffset;
738 	size_t negofflen;
739 
740 	*len = 0;
741 
742 	err = parse_negative_offset(&negoffset, &negofflen, pack,
743 	    offset + tslen);
744 	if (err)
745 		return err;
746 
747 	/* Compute the base object's offset (must be in the same pack file). */
748 	*base_offset = (offset - negoffset);
749 	if (*base_offset <= 0)
750 		return got_error(GOT_ERR_BAD_PACKFILE);
751 
752 	*len = negofflen;
753 	return NULL;
754 }
755 
756 static const struct got_error *
757 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
758     size_t delta_data_offset, struct got_pack *pack)
759 {
760 	const struct got_error *err = NULL;
761 
762 	if (pack->map) {
763 		if (delta_data_offset >= pack->filesize)
764 			return got_error(GOT_ERR_PACK_OFFSET);
765 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
766 		    NULL, NULL, pack->map, delta_data_offset,
767 		    pack->filesize - delta_data_offset);
768 	} else {
769 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
770 			return got_error_from_errno("lseek");
771 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
772 		    NULL, 0, pack->fd);
773 	}
774 	return err;
775 }
776 
777 static const struct got_error *
778 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
779     int delta_type, size_t delta_size, size_t delta_data_offset)
780 {
781 	struct got_delta *delta;
782 
783 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
784 	    delta_data_offset);
785 	if (delta == NULL)
786 		return got_error_from_errno("got_delta_open");
787 	/* delta is freed in got_object_close() */
788 	deltas->nentries++;
789 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
790 	return NULL;
791 }
792 
793 static const struct got_error *
794 resolve_offset_delta(struct got_delta_chain *deltas,
795     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
796     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
797 
798 {
799 	const struct got_error *err;
800 	off_t base_offset;
801 	uint8_t base_type;
802 	uint64_t base_size;
803 	size_t base_tslen;
804 	off_t delta_data_offset;
805 	size_t consumed;
806 
807 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
808 	    delta_offset, tslen);
809 	if (err)
810 		return err;
811 
812 	delta_data_offset = delta_offset + tslen + consumed;
813 	if (delta_data_offset >= pack->filesize)
814 		return got_error(GOT_ERR_PACK_OFFSET);
815 
816 	if (pack->map == NULL) {
817 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
818 		if (delta_data_offset == -1)
819 			return got_error_from_errno("lseek");
820 	}
821 
822 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
823 	    delta_data_offset);
824 	if (err)
825 		return err;
826 
827 	/* An offset delta must be in the same packfile. */
828 	if (base_offset >= pack->filesize)
829 		return got_error(GOT_ERR_PACK_OFFSET);
830 
831 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
832 	    &base_tslen, pack, base_offset);
833 	if (err)
834 		return err;
835 
836 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
837 	    base_tslen, base_type, base_size, recursion - 1);
838 }
839 
840 const struct got_error *
841 got_pack_parse_ref_delta(struct got_object_id *id,
842     struct got_pack *pack, off_t delta_offset, int tslen)
843 {
844 	if (pack->map) {
845 		size_t mapoff = delta_offset + tslen;
846 		memcpy(id, pack->map + mapoff, sizeof(*id));
847 	} else {
848 		ssize_t n;
849 		n = read(pack->fd, id, sizeof(*id));
850 		if (n < 0)
851 			return got_error_from_errno("read");
852 		if (n != sizeof(*id))
853 			return got_error(GOT_ERR_BAD_PACKFILE);
854 	}
855 
856 	return NULL;
857 }
858 
859 static const struct got_error *
860 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
861     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
862     size_t delta_size, unsigned int recursion)
863 {
864 	const struct got_error *err;
865 	struct got_object_id id;
866 	int idx;
867 	off_t base_offset;
868 	uint8_t base_type;
869 	uint64_t base_size;
870 	size_t base_tslen;
871 	off_t delta_data_offset;
872 
873 	if (delta_offset + tslen >= pack->filesize)
874 		return got_error(GOT_ERR_PACK_OFFSET);
875 
876 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
877 	if (err)
878 		return err;
879 	if (pack->map) {
880 		delta_data_offset = delta_offset + tslen + sizeof(id);
881 	} else {
882 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
883 		if (delta_data_offset == -1)
884 			return got_error_from_errno("lseek");
885 	}
886 
887 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
888 	    delta_data_offset);
889 	if (err)
890 		return err;
891 
892 	/* Delta base must be in the same pack file. */
893 	idx = got_packidx_get_object_idx(packidx, &id);
894 	if (idx == -1)
895 		return got_error(GOT_ERR_NO_OBJ);
896 
897 	base_offset = got_packidx_get_object_offset(packidx, idx);
898 	if (base_offset == (uint64_t)-1)
899 		return got_error(GOT_ERR_BAD_PACKIDX);
900 
901 	if (base_offset >= pack->filesize)
902 		return got_error(GOT_ERR_PACK_OFFSET);
903 
904 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
905 	    &base_tslen, pack, base_offset);
906 	if (err)
907 		return err;
908 
909 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
910 	    base_tslen, base_type, base_size, recursion - 1);
911 }
912 
913 const struct got_error *
914 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
915     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
916     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
917 {
918 	const struct got_error *err = NULL;
919 
920 	if (--recursion == 0)
921 		return got_error(GOT_ERR_RECURSION);
922 
923 	switch (delta_type) {
924 	case GOT_OBJ_TYPE_COMMIT:
925 	case GOT_OBJ_TYPE_TREE:
926 	case GOT_OBJ_TYPE_BLOB:
927 	case GOT_OBJ_TYPE_TAG:
928 		/* Plain types are the final delta base. Recursion ends. */
929 		err = add_delta(deltas, delta_offset, tslen, delta_type,
930 		    delta_size, 0);
931 		break;
932 	case GOT_OBJ_TYPE_OFFSET_DELTA:
933 		err = resolve_offset_delta(deltas, packidx, pack,
934 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
935 		break;
936 	case GOT_OBJ_TYPE_REF_DELTA:
937 		err = resolve_ref_delta(deltas, packidx, pack,
938 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
939 		break;
940 	default:
941 		return got_error(GOT_ERR_OBJ_TYPE);
942 	}
943 
944 	return err;
945 }
946 
947 static const struct got_error *
948 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
949     struct got_pack *pack, struct got_object_id *id, off_t offset,
950     size_t tslen, int delta_type, size_t delta_size, int idx)
951 {
952 	const struct got_error *err = NULL;
953 	int resolved_type;
954 
955 	*obj = calloc(1, sizeof(**obj));
956 	if (*obj == NULL)
957 		return got_error_from_errno("calloc");
958 
959 	(*obj)->flags = 0;
960 	(*obj)->hdrlen = 0;
961 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
962 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
963 	(*obj)->pack_offset = offset + tslen;
964 
965 	STAILQ_INIT(&(*obj)->deltas.entries);
966 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
967 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
968 	(*obj)->pack_idx = idx;
969 
970 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
971 	    offset, tslen, delta_type, delta_size,
972 	    GOT_DELTA_CHAIN_RECURSION_MAX);
973 	if (err)
974 		goto done;
975 
976 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
977 	if (err)
978 		goto done;
979 	(*obj)->type = resolved_type;
980 done:
981 	if (err) {
982 		got_object_close(*obj);
983 		*obj = NULL;
984 	}
985 	return err;
986 }
987 
988 const struct got_error *
989 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
990     struct got_packidx *packidx, int idx, struct got_object_id *id)
991 {
992 	const struct got_error *err = NULL;
993 	off_t offset;
994 	uint8_t type;
995 	uint64_t size;
996 	size_t tslen;
997 
998 	*obj = NULL;
999 
1000 	offset = got_packidx_get_object_offset(packidx, idx);
1001 	if (offset == (uint64_t)-1)
1002 		return got_error(GOT_ERR_BAD_PACKIDX);
1003 
1004 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1005 	    pack, offset);
1006 	if (err)
1007 		return err;
1008 
1009 	switch (type) {
1010 	case GOT_OBJ_TYPE_COMMIT:
1011 	case GOT_OBJ_TYPE_TREE:
1012 	case GOT_OBJ_TYPE_BLOB:
1013 	case GOT_OBJ_TYPE_TAG:
1014 		err = open_plain_object(obj, id, type, offset + tslen,
1015 		    size, idx);
1016 		break;
1017 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1018 	case GOT_OBJ_TYPE_REF_DELTA:
1019 		err = open_delta_object(obj, packidx, pack, id, offset,
1020 		    tslen, type, size, idx);
1021 		break;
1022 	default:
1023 		err = got_error(GOT_ERR_OBJ_TYPE);
1024 		break;
1025 	}
1026 
1027 	return err;
1028 }
1029 
1030 const struct got_error *
1031 got_pack_get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas,
1032     struct got_pack *pack)
1033 {
1034 	struct got_delta *delta;
1035 	uint64_t base_size = 0, result_size = 0;
1036 
1037 	*max_size = 0;
1038 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1039 		/* Plain object types are the delta base. */
1040 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1041 		    delta->type != GOT_OBJ_TYPE_TREE &&
1042 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1043 		    delta->type != GOT_OBJ_TYPE_TAG) {
1044 			const struct got_error *err;
1045 			uint8_t *delta_buf;
1046 			size_t delta_len;
1047 			int cached = 1;
1048 
1049 			got_delta_cache_get(&delta_buf, &delta_len,
1050 			    pack->delta_cache, delta->data_offset);
1051 			if (delta_buf == NULL) {
1052 				cached = 0;
1053 				err = read_delta_data(&delta_buf, &delta_len,
1054 				    delta->data_offset, pack);
1055 				if (err)
1056 					return err;
1057 				err = got_delta_cache_add(pack->delta_cache,
1058 				    delta->data_offset, delta_buf, delta_len);
1059 				if (err == NULL)
1060 					cached = 1;
1061 				else if (err->code != GOT_ERR_NO_SPACE) {
1062 					free(delta_buf);
1063 					return err;
1064 				}
1065 			}
1066 			err = got_delta_get_sizes(&base_size, &result_size,
1067 			    delta_buf, delta_len);
1068 			if (!cached)
1069 				free(delta_buf);
1070 			if (err)
1071 				return err;
1072 		} else
1073 			base_size = delta->size;
1074 		if (base_size > *max_size)
1075 			*max_size = base_size;
1076 		if (result_size > *max_size)
1077 			*max_size = result_size;
1078 	}
1079 
1080 	return NULL;
1081 }
1082 
1083 const struct got_error *
1084 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1085     struct got_pack *pack)
1086 {
1087 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1088 		return got_error(GOT_ERR_OBJ_TYPE);
1089 
1090 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1091 }
1092 
1093 const struct got_error *
1094 got_pack_dump_delta_chain_to_file(size_t *result_size,
1095     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1096     FILE *base_file, FILE *accum_file)
1097 {
1098 	const struct got_error *err = NULL;
1099 	struct got_delta *delta;
1100 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1101 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1102 	uint64_t max_size;
1103 	int n = 0;
1104 
1105 	*result_size = 0;
1106 
1107 	if (STAILQ_EMPTY(&deltas->entries))
1108 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1109 
1110 	/* We process small enough files entirely in memory for speed. */
1111 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1112 	if (err)
1113 		return err;
1114 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1115 		accum_buf = malloc(max_size);
1116 		if (accum_buf == NULL)
1117 			return got_error_from_errno("malloc");
1118 		base_file = NULL;
1119 		accum_file = NULL;
1120 	}
1121 
1122 	/* Deltas are ordered in ascending order. */
1123 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1124 		int cached = 1;
1125 		if (n == 0) {
1126 			size_t mapoff;
1127 			off_t delta_data_offset;
1128 
1129 			/* Plain object types are the delta base. */
1130 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1131 			    delta->type != GOT_OBJ_TYPE_TREE &&
1132 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1133 			    delta->type != GOT_OBJ_TYPE_TAG) {
1134 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1135 				goto done;
1136 			}
1137 
1138 			delta_data_offset = delta->offset + delta->tslen;
1139 			if (delta_data_offset >= pack->filesize) {
1140 				err = got_error(GOT_ERR_PACK_OFFSET);
1141 				goto done;
1142 			}
1143 			if (pack->map == NULL) {
1144 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1145 				    == -1) {
1146 					err = got_error_from_errno("lseek");
1147 					goto done;
1148 				}
1149 			}
1150 			if (base_file) {
1151 				if (pack->map) {
1152 					mapoff = (size_t)delta_data_offset;
1153 					err = got_inflate_to_file_mmap(
1154 					    &base_bufsz, NULL, NULL, pack->map,
1155 					    mapoff, pack->filesize - mapoff,
1156 					    base_file);
1157 				} else
1158 					err = got_inflate_to_file_fd(
1159 					    &base_bufsz, NULL, NULL, pack->fd,
1160 					    base_file);
1161 			} else {
1162 				if (pack->map) {
1163 					mapoff = (size_t)delta_data_offset;
1164 					err = got_inflate_to_mem_mmap(&base_buf,
1165 					    &base_bufsz, NULL, NULL,
1166 					    pack->map, mapoff,
1167 					    pack->filesize - mapoff);
1168 				} else
1169 					err = got_inflate_to_mem_fd(&base_buf,
1170 					    &base_bufsz, NULL, NULL, max_size,
1171 					    pack->fd);
1172 			}
1173 			if (err)
1174 				goto done;
1175 			n++;
1176 			if (base_file)
1177 				rewind(base_file);
1178 			continue;
1179 		}
1180 
1181 		got_delta_cache_get(&delta_buf, &delta_len,
1182 		    pack->delta_cache, delta->data_offset);
1183 		if (delta_buf == NULL) {
1184 			cached = 0;
1185 			err = read_delta_data(&delta_buf, &delta_len,
1186 			    delta->data_offset, pack);
1187 			if (err)
1188 				goto done;
1189 			err = got_delta_cache_add(pack->delta_cache,
1190 			    delta->data_offset, delta_buf, delta_len);
1191 			if (err == NULL)
1192 				cached = 1;
1193 			else if (err->code != GOT_ERR_NO_SPACE) {
1194 				free(delta_buf);
1195 				goto done;
1196 			}
1197 		}
1198 		if (base_buf) {
1199 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1200 			    delta_buf, delta_len, accum_buf,
1201 			    &accum_size, max_size);
1202 			n++;
1203 		} else {
1204 			err = got_delta_apply(base_file, delta_buf,
1205 			    delta_len,
1206 			    /* Final delta application writes to output file. */
1207 			    ++n < deltas->nentries ? accum_file : outfile,
1208 			    &accum_size);
1209 		}
1210 		if (!cached)
1211 			free(delta_buf);
1212 		if (err)
1213 			goto done;
1214 
1215 		if (n < deltas->nentries) {
1216 			/* Accumulated delta becomes the new base. */
1217 			if (base_buf) {
1218 				uint8_t *tmp = accum_buf;
1219 				/*
1220 				 * Base buffer switches roles with accumulation
1221 				 * buffer. Ensure it can hold the largest
1222 				 * result in the delta chain. The initial
1223 				 * allocation might have been smaller.
1224 				 */
1225 				if (base_bufsz < max_size) {
1226 					uint8_t *p;
1227 					p = reallocarray(base_buf, 1, max_size);
1228 					if (p == NULL) {
1229 						err = got_error_from_errno(
1230 						    "reallocarray");
1231 						goto done;
1232 					}
1233 					base_buf = p;
1234 					base_bufsz = max_size;
1235 				}
1236 				accum_buf = base_buf;
1237 				base_buf = tmp;
1238 			} else {
1239 				FILE *tmp = accum_file;
1240 				accum_file = base_file;
1241 				base_file = tmp;
1242 				rewind(base_file);
1243 				rewind(accum_file);
1244 			}
1245 		}
1246 	}
1247 
1248 done:
1249 	free(base_buf);
1250 	if (accum_buf) {
1251 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1252 		free(accum_buf);
1253 		if (len != accum_size)
1254 			err = got_ferror(outfile, GOT_ERR_IO);
1255 	}
1256 	rewind(outfile);
1257 	if (err == NULL)
1258 		*result_size = accum_size;
1259 	return err;
1260 }
1261 
1262 const struct got_error *
1263 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1264     struct got_delta_chain *deltas, struct got_pack *pack)
1265 {
1266 	const struct got_error *err = NULL;
1267 	struct got_delta *delta;
1268 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1269 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1270 	uint64_t max_size;
1271 	int n = 0;
1272 
1273 	*outbuf = NULL;
1274 	*outlen = 0;
1275 
1276 	if (STAILQ_EMPTY(&deltas->entries))
1277 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1278 
1279 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1280 	if (err)
1281 		return err;
1282 	accum_buf = malloc(max_size);
1283 	if (accum_buf == NULL)
1284 		return got_error_from_errno("malloc");
1285 
1286 	/* Deltas are ordered in ascending order. */
1287 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1288 		int cached = 1;
1289 		if (n == 0) {
1290 			size_t delta_data_offset;
1291 
1292 			/* Plain object types are the delta base. */
1293 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1294 			    delta->type != GOT_OBJ_TYPE_TREE &&
1295 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1296 			    delta->type != GOT_OBJ_TYPE_TAG) {
1297 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1298 				goto done;
1299 			}
1300 
1301 			delta_data_offset = delta->offset + delta->tslen;
1302 			if (delta_data_offset >= pack->filesize) {
1303 				err = got_error(GOT_ERR_PACK_OFFSET);
1304 				goto done;
1305 			}
1306 			if (pack->map) {
1307 				size_t mapoff = (size_t)delta_data_offset;
1308 				err = got_inflate_to_mem_mmap(&base_buf,
1309 				    &base_bufsz, NULL, NULL, pack->map,
1310 				    mapoff, pack->filesize - mapoff);
1311 			} else {
1312 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1313 				    == -1) {
1314 					err = got_error_from_errno("lseek");
1315 					goto done;
1316 				}
1317 				err = got_inflate_to_mem_fd(&base_buf,
1318 				    &base_bufsz, NULL, NULL, max_size,
1319 				    pack->fd);
1320 			}
1321 			if (err)
1322 				goto done;
1323 			n++;
1324 			continue;
1325 		}
1326 
1327 		got_delta_cache_get(&delta_buf, &delta_len,
1328 		    pack->delta_cache, delta->data_offset);
1329 		if (delta_buf == NULL) {
1330 			cached = 0;
1331 			err = read_delta_data(&delta_buf, &delta_len,
1332 			    delta->data_offset, pack);
1333 			if (err)
1334 				goto done;
1335 			err = got_delta_cache_add(pack->delta_cache,
1336 			    delta->data_offset, delta_buf, delta_len);
1337 			if (err == NULL)
1338 				cached = 1;
1339 			else if (err->code != GOT_ERR_NO_SPACE) {
1340 				free(delta_buf);
1341 				goto done;
1342 			}
1343 		}
1344 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1345 		    delta_buf, delta_len, accum_buf,
1346 		    &accum_size, max_size);
1347 		if (!cached)
1348 			free(delta_buf);
1349 		n++;
1350 		if (err)
1351 			goto done;
1352 
1353 		if (n < deltas->nentries) {
1354 			/* Accumulated delta becomes the new base. */
1355 			uint8_t *tmp = accum_buf;
1356 			/*
1357 			 * Base buffer switches roles with accumulation buffer.
1358 			 * Ensure it can hold the largest result in the delta
1359 			 * chain. Initial allocation might have been smaller.
1360 			 */
1361 			if (base_bufsz < max_size) {
1362 				uint8_t *p;
1363 				p = reallocarray(base_buf, 1, max_size);
1364 				if (p == NULL) {
1365 					err = got_error_from_errno(
1366 					    "reallocarray");
1367 					goto done;
1368 				}
1369 				base_buf = p;
1370 				base_bufsz = max_size;
1371 			}
1372 			accum_buf = base_buf;
1373 			base_buf = tmp;
1374 		}
1375 	}
1376 
1377 done:
1378 	free(base_buf);
1379 	if (err) {
1380 		free(accum_buf);
1381 		*outbuf = NULL;
1382 		*outlen = 0;
1383 	} else {
1384 		*outbuf = accum_buf;
1385 		*outlen = accum_size;
1386 	}
1387 	return err;
1388 }
1389 
1390 const struct got_error *
1391 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1392     FILE *outfile, FILE *base_file, FILE *accum_file)
1393 {
1394 	const struct got_error *err = NULL;
1395 
1396 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1397 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1398 
1399 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1400 		if (obj->pack_offset >= pack->filesize)
1401 			return got_error(GOT_ERR_PACK_OFFSET);
1402 
1403 		if (pack->map) {
1404 			size_t mapoff = (size_t)obj->pack_offset;
1405 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1406 			    pack->map, mapoff, pack->filesize - mapoff,
1407 			    outfile);
1408 		} else {
1409 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1410 				return got_error_from_errno("lseek");
1411 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1412 			    pack->fd, outfile);
1413 		}
1414 	} else
1415 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1416 		    &obj->deltas, pack, outfile, base_file, accum_file);
1417 
1418 	return err;
1419 }
1420 
1421 const struct got_error *
1422 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1423     struct got_object *obj, struct got_pack *pack)
1424 {
1425 	const struct got_error *err = NULL;
1426 
1427 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1428 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1429 
1430 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1431 		if (obj->pack_offset >= pack->filesize)
1432 			return got_error(GOT_ERR_PACK_OFFSET);
1433 		if (pack->map) {
1434 			size_t mapoff = (size_t)obj->pack_offset;
1435 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1436 			    pack->map, mapoff, pack->filesize - mapoff);
1437 		} else {
1438 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1439 				return got_error_from_errno("lseek");
1440 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1441 			    obj->size, pack->fd);
1442 		}
1443 	} else
1444 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1445 		    pack);
1446 
1447 	return err;
1448 }