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Date:: Tue Jan 11 15:37:06 2022 UTC
Message:: fix file corruption regression in 'got checkout' caused by commit db696021 got-read-pack must rewind its files temporary files before reusing them. Problem reported by naddy ok tracey naddy
Actions:: History | Blame | Raw File
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 | O_CLOEXEC);
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,
489     struct got_object_id *id)
490 {
491 	u_int8_t id0 = id->sha1[0];
492 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
493 	int left = 0, right = totobj - 1;
494 
495 	if (id0 > 0)
496 		left = be32toh(packidx->hdr.fanout_table[id0 - 1]);
497 
498 	while (left <= right) {
499 		struct got_packidx_object_id *oid;
500 		int i, cmp;
501 
502 		i = ((left + right) / 2);
503 		oid = &packidx->hdr.sorted_ids[i];
504 		cmp = memcmp(id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
505 		if (cmp == 0)
506 			return i;
507 		else if (cmp > 0)
508 			left = i + 1;
509 		else if (cmp < 0)
510 			right = i - 1;
511 	}
512 
513 	return -1;
514 }
515 
516 const struct got_error *
517 got_packidx_match_id_str_prefix(struct got_object_id_queue *matched_ids,
518     struct got_packidx *packidx, const char *id_str_prefix)
519 {
520 	const struct got_error *err = NULL;
521 	u_int8_t id0;
522 	uint32_t totobj = be32toh(packidx->hdr.fanout_table[0xff]);
523 	char hex[3];
524 	size_t prefix_len = strlen(id_str_prefix);
525 	struct got_packidx_object_id *oid;
526 	uint32_t i = 0;
527 
528 	STAILQ_INIT(matched_ids);
529 
530 	if (prefix_len < 2)
531 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
532 
533 	hex[0] = id_str_prefix[0];
534 	hex[1] = id_str_prefix[1];
535 	hex[2] = '\0';
536 	if (!got_parse_xdigit(&id0, hex))
537 		return got_error_path(id_str_prefix, GOT_ERR_BAD_OBJ_ID_STR);
538 
539 	if (id0 > 0)
540 		i = be32toh(packidx->hdr.fanout_table[id0 - 1]);
541 	oid = &packidx->hdr.sorted_ids[i];
542 	while (i < totobj && oid->sha1[0] == id0) {
543 		char id_str[SHA1_DIGEST_STRING_LENGTH];
544 		struct got_object_qid *qid;
545 		int cmp;
546 
547 		if (!got_sha1_digest_to_str(oid->sha1, id_str, sizeof(id_str)))
548 		        return got_error(GOT_ERR_NO_SPACE);
549 
550 		cmp = strncmp(id_str, id_str_prefix, prefix_len);
551 		if (cmp < 0) {
552 			oid = &packidx->hdr.sorted_ids[++i];
553 			continue;
554 		} else if (cmp > 0)
555 			break;
556 
557 		err = got_object_qid_alloc_partial(&qid);
558 		if (err)
559 			break;
560 		memcpy(qid->id->sha1, oid->sha1, SHA1_DIGEST_LENGTH);
561 		STAILQ_INSERT_TAIL(matched_ids, qid, entry);
562 
563 		oid = &packidx->hdr.sorted_ids[++i];
564 	}
565 
566 	if (err)
567 		got_object_id_queue_free(matched_ids);
568 	return err;
569 }
570 
571 static const struct got_error *
572 pack_stop_privsep_child(struct got_pack *pack)
573 {
574 	const struct got_error *err = NULL;
575 
576 	if (pack->privsep_child == NULL)
577 		return NULL;
578 
579 	err = got_privsep_send_stop(pack->privsep_child->imsg_fd);
580 	if (err)
581 		return err;
582 	err = got_privsep_wait_for_child(pack->privsep_child->pid);
583 	if (close(pack->privsep_child->imsg_fd) == -1 && err == NULL)
584 		err = got_error_from_errno("close");
585 	imsg_clear(pack->privsep_child->ibuf);
586 	free(pack->privsep_child->ibuf);
587 	free(pack->privsep_child);
588 	pack->privsep_child = NULL;
589 	return err;
590 }
591 
592 const struct got_error *
593 got_pack_close(struct got_pack *pack)
594 {
595 	const struct got_error *err = NULL;
596 
597 	err = pack_stop_privsep_child(pack);
598 	if (pack->map && munmap(pack->map, pack->filesize) == -1 && !err)
599 		err = got_error_from_errno("munmap");
600 	if (pack->fd != -1 && close(pack->fd) == -1 && err == NULL)
601 		err = got_error_from_errno("close");
602 	pack->fd = -1;
603 	free(pack->path_packfile);
604 	pack->path_packfile = NULL;
605 	pack->filesize = 0;
606 	if (pack->delta_cache) {
607 		got_delta_cache_free(pack->delta_cache);
608 		pack->delta_cache = NULL;
609 	}
610 
611 	return err;
612 }
613 
614 const struct got_error *
615 got_pack_parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
616     struct got_pack *pack, off_t offset)
617 {
618 	uint8_t t = 0;
619 	uint64_t s = 0;
620 	uint8_t sizeN;
621 	size_t mapoff = 0;
622 	int i = 0;
623 
624 	*len = 0;
625 
626 	if (offset >= pack->filesize)
627 		return got_error(GOT_ERR_PACK_OFFSET);
628 
629 	if (pack->map) {
630 		mapoff = (size_t)offset;
631 	} else {
632 		if (lseek(pack->fd, offset, SEEK_SET) == -1)
633 			return got_error_from_errno("lseek");
634 	}
635 
636 	do {
637 		/* We do not support size values which don't fit in 64 bit. */
638 		if (i > 9)
639 			return got_error(GOT_ERR_NO_SPACE);
640 
641 		if (pack->map) {
642 			if (mapoff + sizeof(sizeN) >= pack->filesize)
643 				return got_error(GOT_ERR_BAD_PACKFILE);
644 			sizeN = *(pack->map + mapoff);
645 			mapoff += sizeof(sizeN);
646 		} else {
647 			ssize_t n = read(pack->fd, &sizeN, sizeof(sizeN));
648 			if (n < 0)
649 				return got_error_from_errno("read");
650 			if (n != sizeof(sizeN))
651 				return got_error(GOT_ERR_BAD_PACKFILE);
652 		}
653 		*len += sizeof(sizeN);
654 
655 		if (i == 0) {
656 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
657 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
658 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
659 		} else {
660 			size_t shift = 4 + 7 * (i - 1);
661 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
662 		}
663 		i++;
664 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
665 
666 	*type = t;
667 	*size = s;
668 	return NULL;
669 }
670 
671 static const struct got_error *
672 open_plain_object(struct got_object **obj, struct got_object_id *id,
673     uint8_t type, off_t offset, size_t size, int idx)
674 {
675 	*obj = calloc(1, sizeof(**obj));
676 	if (*obj == NULL)
677 		return got_error_from_errno("calloc");
678 
679 	(*obj)->type = type;
680 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
681 	(*obj)->pack_idx = idx;
682 	(*obj)->hdrlen = 0;
683 	(*obj)->size = size;
684 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
685 	(*obj)->pack_offset = offset;
686 
687 	return NULL;
688 }
689 
690 static const struct got_error *
691 parse_negative_offset(int64_t *offset, size_t *len, struct got_pack *pack,
692     off_t delta_offset)
693 {
694 	int64_t o = 0;
695 	uint8_t offN;
696 	int i = 0;
697 
698 	*offset = 0;
699 	*len = 0;
700 
701 	do {
702 		/* We do not support offset values which don't fit in 64 bit. */
703 		if (i > 8)
704 			return got_error(GOT_ERR_NO_SPACE);
705 
706 		if (pack->map) {
707 			size_t mapoff;
708 			mapoff = (size_t)delta_offset + *len;
709 			if (mapoff + sizeof(offN) >= pack->filesize)
710 				return got_error(GOT_ERR_PACK_OFFSET);
711 			offN = *(pack->map + mapoff);
712 		} else {
713 			ssize_t n;
714 			n = read(pack->fd, &offN, sizeof(offN));
715 			if (n < 0)
716 				return got_error_from_errno("read");
717 			if (n != sizeof(offN))
718 				return got_error(GOT_ERR_BAD_PACKFILE);
719 		}
720 		*len += sizeof(offN);
721 
722 		if (i == 0)
723 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
724 		else {
725 			o++;
726 			o <<= 7;
727 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
728 		}
729 		i++;
730 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
731 
732 	*offset = o;
733 	return NULL;
734 }
735 
736 const struct got_error *
737 got_pack_parse_offset_delta(off_t *base_offset, size_t *len,
738     struct got_pack *pack, off_t offset, int tslen)
739 {
740 	const struct got_error *err;
741 	int64_t negoffset;
742 	size_t negofflen;
743 
744 	*len = 0;
745 
746 	err = parse_negative_offset(&negoffset, &negofflen, pack,
747 	    offset + tslen);
748 	if (err)
749 		return err;
750 
751 	/* Compute the base object's offset (must be in the same pack file). */
752 	*base_offset = (offset - negoffset);
753 	if (*base_offset <= 0)
754 		return got_error(GOT_ERR_BAD_PACKFILE);
755 
756 	*len = negofflen;
757 	return NULL;
758 }
759 
760 static const struct got_error *
761 read_delta_data(uint8_t **delta_buf, size_t *delta_len,
762     size_t delta_data_offset, struct got_pack *pack)
763 {
764 	const struct got_error *err = NULL;
765 
766 	if (pack->map) {
767 		if (delta_data_offset >= pack->filesize)
768 			return got_error(GOT_ERR_PACK_OFFSET);
769 		err = got_inflate_to_mem_mmap(delta_buf, delta_len,
770 		    NULL, NULL, pack->map, delta_data_offset,
771 		    pack->filesize - delta_data_offset);
772 	} else {
773 		if (lseek(pack->fd, delta_data_offset, SEEK_SET) == -1)
774 			return got_error_from_errno("lseek");
775 		err = got_inflate_to_mem_fd(delta_buf, delta_len, NULL,
776 		    NULL, 0, pack->fd);
777 	}
778 	return err;
779 }
780 
781 static const struct got_error *
782 add_delta(struct got_delta_chain *deltas, off_t delta_offset, size_t tslen,
783     int delta_type, size_t delta_size, size_t delta_data_offset)
784 {
785 	struct got_delta *delta;
786 
787 	delta = got_delta_open(delta_offset, tslen, delta_type, delta_size,
788 	    delta_data_offset);
789 	if (delta == NULL)
790 		return got_error_from_errno("got_delta_open");
791 	/* delta is freed in got_object_close() */
792 	deltas->nentries++;
793 	STAILQ_INSERT_HEAD(&deltas->entries, delta, entry);
794 	return NULL;
795 }
796 
797 static const struct got_error *
798 resolve_offset_delta(struct got_delta_chain *deltas,
799     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
800     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
801 
802 {
803 	const struct got_error *err;
804 	off_t base_offset;
805 	uint8_t base_type;
806 	uint64_t base_size;
807 	size_t base_tslen;
808 	off_t delta_data_offset;
809 	size_t consumed;
810 
811 	err = got_pack_parse_offset_delta(&base_offset, &consumed, pack,
812 	    delta_offset, tslen);
813 	if (err)
814 		return err;
815 
816 	delta_data_offset = delta_offset + tslen + consumed;
817 	if (delta_data_offset >= pack->filesize)
818 		return got_error(GOT_ERR_PACK_OFFSET);
819 
820 	if (pack->map == NULL) {
821 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
822 		if (delta_data_offset == -1)
823 			return got_error_from_errno("lseek");
824 	}
825 
826 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
827 	    delta_data_offset);
828 	if (err)
829 		return err;
830 
831 	/* An offset delta must be in the same packfile. */
832 	if (base_offset >= pack->filesize)
833 		return got_error(GOT_ERR_PACK_OFFSET);
834 
835 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
836 	    &base_tslen, pack, base_offset);
837 	if (err)
838 		return err;
839 
840 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
841 	    base_tslen, base_type, base_size, recursion - 1);
842 }
843 
844 const struct got_error *
845 got_pack_parse_ref_delta(struct got_object_id *id,
846     struct got_pack *pack, off_t delta_offset, int tslen)
847 {
848 	if (pack->map) {
849 		size_t mapoff = delta_offset + tslen;
850 		if (mapoff + sizeof(*id) >= pack->filesize)
851 			return got_error(GOT_ERR_PACK_OFFSET);
852 		memcpy(id, pack->map + mapoff, sizeof(*id));
853 	} else {
854 		ssize_t n;
855 		n = read(pack->fd, id, sizeof(*id));
856 		if (n < 0)
857 			return got_error_from_errno("read");
858 		if (n != sizeof(*id))
859 			return got_error(GOT_ERR_BAD_PACKFILE);
860 	}
861 
862 	return NULL;
863 }
864 
865 static const struct got_error *
866 resolve_ref_delta(struct got_delta_chain *deltas, struct got_packidx *packidx,
867     struct got_pack *pack, off_t delta_offset, size_t tslen, int delta_type,
868     size_t delta_size, unsigned int recursion)
869 {
870 	const struct got_error *err;
871 	struct got_object_id id;
872 	int idx;
873 	off_t base_offset;
874 	uint8_t base_type;
875 	uint64_t base_size;
876 	size_t base_tslen;
877 	off_t delta_data_offset;
878 
879 	if (delta_offset + tslen >= pack->filesize)
880 		return got_error(GOT_ERR_PACK_OFFSET);
881 
882 	err = got_pack_parse_ref_delta(&id, pack, delta_offset, tslen);
883 	if (err)
884 		return err;
885 	if (pack->map) {
886 		delta_data_offset = delta_offset + tslen + sizeof(id);
887 	} else {
888 		delta_data_offset = lseek(pack->fd, 0, SEEK_CUR);
889 		if (delta_data_offset == -1)
890 			return got_error_from_errno("lseek");
891 	}
892 
893 	err = add_delta(deltas, delta_offset, tslen, delta_type, delta_size,
894 	    delta_data_offset);
895 	if (err)
896 		return err;
897 
898 	/* Delta base must be in the same pack file. */
899 	idx = got_packidx_get_object_idx(packidx, &id);
900 	if (idx == -1)
901 		return got_error(GOT_ERR_NO_OBJ);
902 
903 	base_offset = got_packidx_get_object_offset(packidx, idx);
904 	if (base_offset == (uint64_t)-1)
905 		return got_error(GOT_ERR_BAD_PACKIDX);
906 
907 	if (base_offset >= pack->filesize)
908 		return got_error(GOT_ERR_PACK_OFFSET);
909 
910 	err = got_pack_parse_object_type_and_size(&base_type, &base_size,
911 	    &base_tslen, pack, base_offset);
912 	if (err)
913 		return err;
914 
915 	return got_pack_resolve_delta_chain(deltas, packidx, pack, base_offset,
916 	    base_tslen, base_type, base_size, recursion - 1);
917 }
918 
919 const struct got_error *
920 got_pack_resolve_delta_chain(struct got_delta_chain *deltas,
921     struct got_packidx *packidx, struct got_pack *pack, off_t delta_offset,
922     size_t tslen, int delta_type, size_t delta_size, unsigned int recursion)
923 {
924 	const struct got_error *err = NULL;
925 
926 	if (--recursion == 0)
927 		return got_error(GOT_ERR_RECURSION);
928 
929 	switch (delta_type) {
930 	case GOT_OBJ_TYPE_COMMIT:
931 	case GOT_OBJ_TYPE_TREE:
932 	case GOT_OBJ_TYPE_BLOB:
933 	case GOT_OBJ_TYPE_TAG:
934 		/* Plain types are the final delta base. Recursion ends. */
935 		err = add_delta(deltas, delta_offset, tslen, delta_type,
936 		    delta_size, 0);
937 		break;
938 	case GOT_OBJ_TYPE_OFFSET_DELTA:
939 		err = resolve_offset_delta(deltas, packidx, pack,
940 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
941 		break;
942 	case GOT_OBJ_TYPE_REF_DELTA:
943 		err = resolve_ref_delta(deltas, packidx, pack,
944 		    delta_offset, tslen, delta_type, delta_size, recursion - 1);
945 		break;
946 	default:
947 		return got_error(GOT_ERR_OBJ_TYPE);
948 	}
949 
950 	return err;
951 }
952 
953 static const struct got_error *
954 open_delta_object(struct got_object **obj, struct got_packidx *packidx,
955     struct got_pack *pack, struct got_object_id *id, off_t offset,
956     size_t tslen, int delta_type, size_t delta_size, int idx)
957 {
958 	const struct got_error *err = NULL;
959 	int resolved_type;
960 
961 	*obj = calloc(1, sizeof(**obj));
962 	if (*obj == NULL)
963 		return got_error_from_errno("calloc");
964 
965 	(*obj)->flags = 0;
966 	(*obj)->hdrlen = 0;
967 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
968 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
969 	(*obj)->pack_offset = offset + tslen;
970 
971 	STAILQ_INIT(&(*obj)->deltas.entries);
972 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
973 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
974 	(*obj)->pack_idx = idx;
975 
976 	err = got_pack_resolve_delta_chain(&(*obj)->deltas, packidx, pack,
977 	    offset, tslen, delta_type, delta_size,
978 	    GOT_DELTA_CHAIN_RECURSION_MAX);
979 	if (err)
980 		goto done;
981 
982 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
983 	if (err)
984 		goto done;
985 	(*obj)->type = resolved_type;
986 done:
987 	if (err) {
988 		got_object_close(*obj);
989 		*obj = NULL;
990 	}
991 	return err;
992 }
993 
994 const struct got_error *
995 got_packfile_open_object(struct got_object **obj, struct got_pack *pack,
996     struct got_packidx *packidx, int idx, struct got_object_id *id)
997 {
998 	const struct got_error *err = NULL;
999 	off_t offset;
1000 	uint8_t type;
1001 	uint64_t size;
1002 	size_t tslen;
1003 
1004 	*obj = NULL;
1005 
1006 	offset = got_packidx_get_object_offset(packidx, idx);
1007 	if (offset == (uint64_t)-1)
1008 		return got_error(GOT_ERR_BAD_PACKIDX);
1009 
1010 	err = got_pack_parse_object_type_and_size(&type, &size, &tslen,
1011 	    pack, offset);
1012 	if (err)
1013 		return err;
1014 
1015 	switch (type) {
1016 	case GOT_OBJ_TYPE_COMMIT:
1017 	case GOT_OBJ_TYPE_TREE:
1018 	case GOT_OBJ_TYPE_BLOB:
1019 	case GOT_OBJ_TYPE_TAG:
1020 		err = open_plain_object(obj, id, type, offset + tslen,
1021 		    size, idx);
1022 		break;
1023 	case GOT_OBJ_TYPE_OFFSET_DELTA:
1024 	case GOT_OBJ_TYPE_REF_DELTA:
1025 		err = open_delta_object(obj, packidx, pack, id, offset,
1026 		    tslen, type, size, idx);
1027 		break;
1028 	default:
1029 		err = got_error(GOT_ERR_OBJ_TYPE);
1030 		break;
1031 	}
1032 
1033 	return err;
1034 }
1035 
1036 const struct got_error *
1037 got_pack_get_delta_chain_max_size(uint64_t *max_size,
1038     struct got_delta_chain *deltas, struct got_pack *pack)
1039 {
1040 	struct got_delta *delta;
1041 	uint64_t base_size = 0, result_size = 0;
1042 
1043 	*max_size = 0;
1044 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1045 		/* Plain object types are the delta base. */
1046 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1047 		    delta->type != GOT_OBJ_TYPE_TREE &&
1048 		    delta->type != GOT_OBJ_TYPE_BLOB &&
1049 		    delta->type != GOT_OBJ_TYPE_TAG) {
1050 			const struct got_error *err;
1051 			uint8_t *delta_buf;
1052 			size_t delta_len;
1053 			int cached = 1;
1054 
1055 			got_delta_cache_get(&delta_buf, &delta_len,
1056 			    pack->delta_cache, delta->data_offset);
1057 			if (delta_buf == NULL) {
1058 				cached = 0;
1059 				err = read_delta_data(&delta_buf, &delta_len,
1060 				    delta->data_offset, pack);
1061 				if (err)
1062 					return err;
1063 				err = got_delta_cache_add(pack->delta_cache,
1064 				    delta->data_offset, delta_buf, delta_len);
1065 				if (err == NULL)
1066 					cached = 1;
1067 				else if (err->code != GOT_ERR_NO_SPACE) {
1068 					free(delta_buf);
1069 					return err;
1070 				}
1071 			}
1072 			err = got_delta_get_sizes(&base_size, &result_size,
1073 			    delta_buf, delta_len);
1074 			if (!cached)
1075 				free(delta_buf);
1076 			if (err)
1077 				return err;
1078 		} else
1079 			base_size = delta->size;
1080 		if (base_size > *max_size)
1081 			*max_size = base_size;
1082 		if (result_size > *max_size)
1083 			*max_size = result_size;
1084 	}
1085 
1086 	return NULL;
1087 }
1088 
1089 const struct got_error *
1090 got_pack_get_max_delta_object_size(uint64_t *size, struct got_object *obj,
1091     struct got_pack *pack)
1092 {
1093 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0)
1094 		return got_error(GOT_ERR_OBJ_TYPE);
1095 
1096 	return got_pack_get_delta_chain_max_size(size, &obj->deltas, pack);
1097 }
1098 
1099 const struct got_error *
1100 got_pack_dump_delta_chain_to_file(size_t *result_size,
1101     struct got_delta_chain *deltas, struct got_pack *pack, FILE *outfile,
1102     FILE *base_file, FILE *accum_file)
1103 {
1104 	const struct got_error *err = NULL;
1105 	struct got_delta *delta;
1106 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1107 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1108 	uint64_t max_size;
1109 	int n = 0;
1110 
1111 	*result_size = 0;
1112 
1113 	if (STAILQ_EMPTY(&deltas->entries))
1114 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1115 
1116 	/* We process small enough files entirely in memory for speed. */
1117 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1118 	if (err)
1119 		return err;
1120 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX) {
1121 		accum_buf = malloc(max_size);
1122 		if (accum_buf == NULL)
1123 			return got_error_from_errno("malloc");
1124 		base_file = NULL;
1125 		accum_file = NULL;
1126 	} else {
1127 		if (fseeko(base_file, 0L, SEEK_SET) == -1)
1128 			return got_error_from_errno("fseeko");
1129 		if (fseeko(accum_file, 0L, SEEK_SET) == -1)
1130 			return got_error_from_errno("fseeko");
1131 	}
1132 
1133 	/* Deltas are ordered in ascending order. */
1134 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1135 		int cached = 1;
1136 		if (n == 0) {
1137 			size_t mapoff;
1138 			off_t delta_data_offset;
1139 
1140 			/* Plain object types are the delta base. */
1141 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1142 			    delta->type != GOT_OBJ_TYPE_TREE &&
1143 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1144 			    delta->type != GOT_OBJ_TYPE_TAG) {
1145 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1146 				goto done;
1147 			}
1148 
1149 			delta_data_offset = delta->offset + delta->tslen;
1150 			if (delta_data_offset >= pack->filesize) {
1151 				err = got_error(GOT_ERR_PACK_OFFSET);
1152 				goto done;
1153 			}
1154 			if (pack->map == NULL) {
1155 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1156 				    == -1) {
1157 					err = got_error_from_errno("lseek");
1158 					goto done;
1159 				}
1160 			}
1161 			if (base_file) {
1162 				if (pack->map) {
1163 					mapoff = (size_t)delta_data_offset;
1164 					err = got_inflate_to_file_mmap(
1165 					    &base_bufsz, NULL, NULL, pack->map,
1166 					    mapoff, pack->filesize - mapoff,
1167 					    base_file);
1168 				} else
1169 					err = got_inflate_to_file_fd(
1170 					    &base_bufsz, NULL, NULL, pack->fd,
1171 					    base_file);
1172 			} else {
1173 				if (pack->map) {
1174 					mapoff = (size_t)delta_data_offset;
1175 					err = got_inflate_to_mem_mmap(&base_buf,
1176 					    &base_bufsz, NULL, NULL,
1177 					    pack->map, mapoff,
1178 					    pack->filesize - mapoff);
1179 				} else
1180 					err = got_inflate_to_mem_fd(&base_buf,
1181 					    &base_bufsz, NULL, NULL, max_size,
1182 					    pack->fd);
1183 			}
1184 			if (err)
1185 				goto done;
1186 			n++;
1187 			if (base_file)
1188 				rewind(base_file);
1189 			continue;
1190 		}
1191 
1192 		got_delta_cache_get(&delta_buf, &delta_len,
1193 		    pack->delta_cache, delta->data_offset);
1194 		if (delta_buf == NULL) {
1195 			cached = 0;
1196 			err = read_delta_data(&delta_buf, &delta_len,
1197 			    delta->data_offset, pack);
1198 			if (err)
1199 				goto done;
1200 			err = got_delta_cache_add(pack->delta_cache,
1201 			    delta->data_offset, delta_buf, delta_len);
1202 			if (err == NULL)
1203 				cached = 1;
1204 			else if (err->code != GOT_ERR_NO_SPACE) {
1205 				free(delta_buf);
1206 				goto done;
1207 			}
1208 		}
1209 		if (base_buf) {
1210 			err = got_delta_apply_in_mem(base_buf, base_bufsz,
1211 			    delta_buf, delta_len, accum_buf,
1212 			    &accum_size, max_size);
1213 			n++;
1214 		} else {
1215 			err = got_delta_apply(base_file, delta_buf,
1216 			    delta_len,
1217 			    /* Final delta application writes to output file. */
1218 			    ++n < deltas->nentries ? accum_file : outfile,
1219 			    &accum_size);
1220 		}
1221 		if (!cached)
1222 			free(delta_buf);
1223 		if (err)
1224 			goto done;
1225 
1226 		if (n < deltas->nentries) {
1227 			/* Accumulated delta becomes the new base. */
1228 			if (base_buf) {
1229 				uint8_t *tmp = accum_buf;
1230 				/*
1231 				 * Base buffer switches roles with accumulation
1232 				 * buffer. Ensure it can hold the largest
1233 				 * result in the delta chain. The initial
1234 				 * allocation might have been smaller.
1235 				 */
1236 				if (base_bufsz < max_size) {
1237 					uint8_t *p;
1238 					p = reallocarray(base_buf, 1, max_size);
1239 					if (p == NULL) {
1240 						err = got_error_from_errno(
1241 						    "reallocarray");
1242 						goto done;
1243 					}
1244 					base_buf = p;
1245 					base_bufsz = max_size;
1246 				}
1247 				accum_buf = base_buf;
1248 				base_buf = tmp;
1249 			} else {
1250 				FILE *tmp = accum_file;
1251 				accum_file = base_file;
1252 				base_file = tmp;
1253 				rewind(base_file);
1254 				rewind(accum_file);
1255 			}
1256 		}
1257 	}
1258 
1259 done:
1260 	free(base_buf);
1261 	if (accum_buf) {
1262 		size_t len = fwrite(accum_buf, 1, accum_size, outfile);
1263 		free(accum_buf);
1264 		if (len != accum_size)
1265 			err = got_ferror(outfile, GOT_ERR_IO);
1266 	}
1267 	rewind(outfile);
1268 	if (err == NULL)
1269 		*result_size = accum_size;
1270 	return err;
1271 }
1272 
1273 const struct got_error *
1274 got_pack_dump_delta_chain_to_mem(uint8_t **outbuf, size_t *outlen,
1275     struct got_delta_chain *deltas, struct got_pack *pack)
1276 {
1277 	const struct got_error *err = NULL;
1278 	struct got_delta *delta;
1279 	uint8_t *base_buf = NULL, *accum_buf = NULL, *delta_buf;
1280 	size_t base_bufsz = 0, accum_size = 0, delta_len;
1281 	uint64_t max_size;
1282 	int n = 0;
1283 
1284 	*outbuf = NULL;
1285 	*outlen = 0;
1286 
1287 	if (STAILQ_EMPTY(&deltas->entries))
1288 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1289 
1290 	err = got_pack_get_delta_chain_max_size(&max_size, deltas, pack);
1291 	if (err)
1292 		return err;
1293 	accum_buf = malloc(max_size);
1294 	if (accum_buf == NULL)
1295 		return got_error_from_errno("malloc");
1296 
1297 	/* Deltas are ordered in ascending order. */
1298 	STAILQ_FOREACH(delta, &deltas->entries, entry) {
1299 		int cached = 1;
1300 		if (n == 0) {
1301 			size_t delta_data_offset;
1302 
1303 			/* Plain object types are the delta base. */
1304 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1305 			    delta->type != GOT_OBJ_TYPE_TREE &&
1306 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1307 			    delta->type != GOT_OBJ_TYPE_TAG) {
1308 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1309 				goto done;
1310 			}
1311 
1312 			delta_data_offset = delta->offset + delta->tslen;
1313 			if (delta_data_offset >= pack->filesize) {
1314 				err = got_error(GOT_ERR_PACK_OFFSET);
1315 				goto done;
1316 			}
1317 			if (pack->map) {
1318 				size_t mapoff = (size_t)delta_data_offset;
1319 				err = got_inflate_to_mem_mmap(&base_buf,
1320 				    &base_bufsz, NULL, NULL, pack->map,
1321 				    mapoff, pack->filesize - mapoff);
1322 			} else {
1323 				if (lseek(pack->fd, delta_data_offset, SEEK_SET)
1324 				    == -1) {
1325 					err = got_error_from_errno("lseek");
1326 					goto done;
1327 				}
1328 				err = got_inflate_to_mem_fd(&base_buf,
1329 				    &base_bufsz, NULL, NULL, max_size,
1330 				    pack->fd);
1331 			}
1332 			if (err)
1333 				goto done;
1334 			n++;
1335 			continue;
1336 		}
1337 
1338 		got_delta_cache_get(&delta_buf, &delta_len,
1339 		    pack->delta_cache, delta->data_offset);
1340 		if (delta_buf == NULL) {
1341 			cached = 0;
1342 			err = read_delta_data(&delta_buf, &delta_len,
1343 			    delta->data_offset, pack);
1344 			if (err)
1345 				goto done;
1346 			err = got_delta_cache_add(pack->delta_cache,
1347 			    delta->data_offset, delta_buf, delta_len);
1348 			if (err == NULL)
1349 				cached = 1;
1350 			else if (err->code != GOT_ERR_NO_SPACE) {
1351 				free(delta_buf);
1352 				goto done;
1353 			}
1354 		}
1355 		err = got_delta_apply_in_mem(base_buf, base_bufsz,
1356 		    delta_buf, delta_len, accum_buf,
1357 		    &accum_size, max_size);
1358 		if (!cached)
1359 			free(delta_buf);
1360 		n++;
1361 		if (err)
1362 			goto done;
1363 
1364 		if (n < deltas->nentries) {
1365 			/* Accumulated delta becomes the new base. */
1366 			uint8_t *tmp = accum_buf;
1367 			/*
1368 			 * Base buffer switches roles with accumulation buffer.
1369 			 * Ensure it can hold the largest result in the delta
1370 			 * chain. Initial allocation might have been smaller.
1371 			 */
1372 			if (base_bufsz < max_size) {
1373 				uint8_t *p;
1374 				p = reallocarray(base_buf, 1, max_size);
1375 				if (p == NULL) {
1376 					err = got_error_from_errno(
1377 					    "reallocarray");
1378 					goto done;
1379 				}
1380 				base_buf = p;
1381 				base_bufsz = max_size;
1382 			}
1383 			accum_buf = base_buf;
1384 			base_buf = tmp;
1385 		}
1386 	}
1387 
1388 done:
1389 	free(base_buf);
1390 	if (err) {
1391 		free(accum_buf);
1392 		*outbuf = NULL;
1393 		*outlen = 0;
1394 	} else {
1395 		*outbuf = accum_buf;
1396 		*outlen = accum_size;
1397 	}
1398 	return err;
1399 }
1400 
1401 const struct got_error *
1402 got_packfile_extract_object(struct got_pack *pack, struct got_object *obj,
1403     FILE *outfile, FILE *base_file, FILE *accum_file)
1404 {
1405 	const struct got_error *err = NULL;
1406 
1407 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1408 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1409 
1410 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1411 		if (obj->pack_offset >= pack->filesize)
1412 			return got_error(GOT_ERR_PACK_OFFSET);
1413 
1414 		if (pack->map) {
1415 			size_t mapoff = (size_t)obj->pack_offset;
1416 			err = got_inflate_to_file_mmap(&obj->size, NULL, NULL,
1417 			    pack->map, mapoff, pack->filesize - mapoff,
1418 			    outfile);
1419 		} else {
1420 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1421 				return got_error_from_errno("lseek");
1422 			err = got_inflate_to_file_fd(&obj->size, NULL, NULL,
1423 			    pack->fd, outfile);
1424 		}
1425 	} else
1426 		err = got_pack_dump_delta_chain_to_file(&obj->size,
1427 		    &obj->deltas, pack, outfile, base_file, accum_file);
1428 
1429 	return err;
1430 }
1431 
1432 const struct got_error *
1433 got_packfile_extract_object_to_mem(uint8_t **buf, size_t *len,
1434     struct got_object *obj, struct got_pack *pack)
1435 {
1436 	const struct got_error *err = NULL;
1437 
1438 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1439 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1440 
1441 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1442 		if (obj->pack_offset >= pack->filesize)
1443 			return got_error(GOT_ERR_PACK_OFFSET);
1444 		if (pack->map) {
1445 			size_t mapoff = (size_t)obj->pack_offset;
1446 			err = got_inflate_to_mem_mmap(buf, len, NULL, NULL,
1447 			    pack->map, mapoff, pack->filesize - mapoff);
1448 		} else {
1449 			if (lseek(pack->fd, obj->pack_offset, SEEK_SET) == -1)
1450 				return got_error_from_errno("lseek");
1451 			err = got_inflate_to_mem_fd(buf, len, NULL, NULL,
1452 			    obj->size, pack->fd);
1453 		}
1454 	} else
1455 		err = got_pack_dump_delta_chain_to_mem(buf, len, &obj->deltas,
1456 		    pack);
1457 
1458 	return err;
1459 }