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Date:: Fri Mar 9 16:01:49 2018 UTC
Message:: add a pack index cache; speeds tree listing up quite a lot
Actions:: History | Blame | Raw File
1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/stat.h>
19 #include <sys/queue.h>
20 
21 #include <dirent.h>
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <limits.h>
28 #include <sha1.h>
29 #include <endian.h>
30 #include <zlib.h>
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 #include "got_repository.h"
35 
36 #include "got_sha1_priv.h"
37 #include "got_pack_priv.h"
38 #include "got_path_priv.h"
39 #include "got_delta_priv.h"
40 #include "got_zb_priv.h"
41 #include "got_object_priv.h"
42 #include "got_repository_priv.h"
43 
44 #ifndef nitems
45 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
46 #endif
47 
48 #define GOT_PACK_PREFIX		"pack-"
49 #define GOT_PACKFILE_SUFFIX	".pack"
50 #define GOT_PACKIDX_SUFFIX		".idx"
51 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
52 				SHA1_DIGEST_STRING_LENGTH - 1 + \
53 				strlen(GOT_PACKFILE_SUFFIX))
54 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
55 				SHA1_DIGEST_STRING_LENGTH - 1 + \
56 				strlen(GOT_PACKIDX_SUFFIX))
57 
58 #ifndef MIN
59 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
60 #endif
61 
62 static const struct got_error *
63 verify_fanout_table(uint32_t *fanout_table)
64 {
65 	int i;
66 
67 	for (i = 0; i < 0xff - 1; i++) {
68 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
69 			return got_error(GOT_ERR_BAD_PACKIDX);
70 	}
71 
72 	return NULL;
73 }
74 
75 static const struct got_error *
76 get_packfile_size(size_t *size, const char *path_idx)
77 {
78 	struct stat sb;
79 	char *path_pack;
80 	char base_path[PATH_MAX];
81 	char *dot;
82 
83 	if (strlcpy(base_path, path_idx, PATH_MAX) > PATH_MAX)
84 		return got_error(GOT_ERR_NO_SPACE);
85 
86 	dot = strrchr(base_path, '.');
87 	if (dot == NULL)
88 		return got_error(GOT_ERR_BAD_PATH);
89 	*dot = '\0';
90 	if (asprintf(&path_pack, "%s.pack", base_path) == -1)
91 		return got_error(GOT_ERR_NO_MEM);
92 
93 	if (stat(path_pack, &sb) != 0) {
94 		free(path_pack);
95 		return got_error_from_errno();
96 	}
97 
98 	free(path_pack);
99 	*size = sb.st_size;
100 	return 0;
101 }
102 
103 const struct got_error *
104 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
105 {
106 	struct got_packidx_v2_hdr *p;
107 	FILE *f;
108 	const struct got_error *err = NULL;
109 	size_t n, nobj, packfile_size;
110 	SHA1_CTX ctx;
111 	uint8_t sha1[SHA1_DIGEST_LENGTH];
112 
113 	SHA1Init(&ctx);
114 
115 	f = fopen(path, "rb");
116 	if (f == NULL)
117 		return got_error(GOT_ERR_BAD_PATH);
118 
119 	err = get_packfile_size(&packfile_size, path);
120 	if (err)
121 		return err;
122 
123 	p = calloc(1, sizeof(*p));
124 	if (p == NULL) {
125 		err = got_error(GOT_ERR_NO_MEM);
126 		goto done;
127 	}
128 
129 	n = fread(&p->magic, sizeof(p->magic), 1, f);
130 	if (n != 1) {
131 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
132 		goto done;
133 	}
134 
135 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
136 		err = got_error(GOT_ERR_BAD_PACKIDX);
137 		goto done;
138 	}
139 
140 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
141 
142 	n = fread(&p->version, sizeof(p->version), 1, f);
143 	if (n != 1) {
144 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
145 		goto done;
146 	}
147 
148 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
149 		err = got_error(GOT_ERR_BAD_PACKIDX);
150 		goto done;
151 	}
152 
153 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
154 
155 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
156 	if (n != 1) {
157 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
158 		goto done;
159 	}
160 
161 	err = verify_fanout_table(p->fanout_table);
162 	if (err)
163 		goto done;
164 
165 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
166 
167 	nobj = betoh32(p->fanout_table[0xff]);
168 
169 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
170 	if (p->sorted_ids == NULL) {
171 		err = got_error(GOT_ERR_NO_MEM);
172 		goto done;
173 	}
174 
175 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
176 	if (n != nobj) {
177 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
178 		goto done;
179 	}
180 
181 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
182 	    nobj * sizeof(*p->sorted_ids));
183 
184 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
185 	if (p->crc32 == NULL) {
186 		err = got_error(GOT_ERR_NO_MEM);
187 		goto done;
188 	}
189 
190 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
191 	if (n != nobj) {
192 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
193 		goto done;
194 	}
195 
196 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
197 
198 	p->offsets = calloc(nobj, sizeof(*p->offsets));
199 	if (p->offsets == NULL) {
200 		err = got_error(GOT_ERR_NO_MEM);
201 		goto done;
202 	}
203 
204 	n = fread(p->offsets, sizeof(*p->offsets), nobj, f);
205 	if (n != nobj) {
206 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
207 		goto done;
208 	}
209 
210 	SHA1Update(&ctx, (uint8_t *)p->offsets, nobj * sizeof(*p->offsets));
211 
212 	/* Large file offsets are contained only in files > 2GB. */
213 	if (packfile_size <= 0x80000000)
214 		goto checksum;
215 
216 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
217 	if (p->large_offsets == NULL) {
218 		err = got_error(GOT_ERR_NO_MEM);
219 		goto done;
220 	}
221 
222 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
223 	if (n != nobj) {
224 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
225 		goto done;
226 	}
227 
228 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
229 	    nobj * sizeof(*p->large_offsets));
230 
231 checksum:
232 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
233 	if (n != 1) {
234 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
235 		goto done;
236 	}
237 
238 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
239 	SHA1Final(sha1, &ctx);
240 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
241 		err = got_error(GOT_ERR_PACKIDX_CSUM);
242 done:
243 	fclose(f);
244 	if (err)
245 		got_packidx_close(p);
246 	else
247 		*packidx = p;
248 	return err;
249 }
250 
251 void
252 got_packidx_close(struct got_packidx_v2_hdr *packidx)
253 {
254 	free(packidx->sorted_ids);
255 	free(packidx->offsets);
256 	free(packidx->crc32);
257 	free(packidx->large_offsets);
258 	free(packidx);
259 }
260 
261 static int
262 is_packidx_filename(const char *name, size_t len)
263 {
264 	if (len != GOT_PACKIDX_NAMELEN)
265 		return 0;
266 
267 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
268 		return 0;
269 
270 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
271 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
272 		return 0;
273 
274 	return 1;
275 }
276 
277 static off_t
278 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
279 {
280 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
281 	uint32_t offset = betoh32(packidx->offsets[idx]);
282 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
283 		uint64_t loffset;
284 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
285 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
286 			return -1;
287 		loffset = betoh64(packidx->large_offsets[idx]);
288 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
289 	}
290 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
291 }
292 
293 static int
294 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id)
295 {
296 	u_int8_t id0 = id->sha1[0];
297 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
298 	int i = 0;
299 
300 	if (id0 > 0)
301 		i = betoh32(packidx->fanout_table[id0 - 1]);
302 
303 	while (i < totobj) {
304 		struct got_object_id *oid = &packidx->sorted_ids[i];
305 		uint32_t offset;
306 		int cmp = got_object_id_cmp(id, oid);
307 
308 		if (cmp == 0)
309 			return i;
310 		i++;
311 	}
312 
313 	return -1;
314 }
315 
316 static struct got_packidx_v2_hdr *
317 dup_packidx(struct got_packidx_v2_hdr *packidx)
318 {
319 	struct got_packidx_v2_hdr *p;
320 	size_t nobj;
321 
322 	p = calloc(1, sizeof(*p));
323 	if (p == NULL)
324 		return NULL;
325 
326 	memcpy(p, packidx, sizeof(*p));
327 	p->sorted_ids = NULL;
328 	p->crc32 = NULL;
329 	p->offsets = NULL;
330 	p->large_offsets = NULL;
331 
332 	nobj = betoh32(p->fanout_table[0xff]);
333 
334 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
335 	if (p->sorted_ids == NULL)
336 		goto err;
337 	memcpy(p->sorted_ids, packidx->sorted_ids, nobj * sizeof(*p->sorted_ids));
338 
339 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
340 	if (p->crc32 == NULL)
341 		goto err;
342 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
343 
344 	p->offsets = calloc(nobj, sizeof(*p->offsets));
345 	if (p->offsets == NULL)
346 		goto err;
347 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
348 
349 	if (p->large_offsets) {
350 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
351 		if (p->large_offsets == NULL)
352 			goto err;
353 		memcpy(p->large_offsets, packidx->large_offsets,
354 		    nobj * sizeof(*p->large_offsets));
355 	}
356 
357 	return p;
358 
359 err:
360 	free(p->large_offsets);
361 	free(p->offsets);
362 	free(p->crc32);
363 	free(p->sorted_ids);
364 	free(p);
365 	return NULL;
366 }
367 
368 static void
369 cache_packidx(struct got_packidx_v2_hdr *packidx,
370     struct got_repository *repo)
371 {
372 	struct got_packidx_v2_hdr *p;
373 	int i;
374 
375 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
376 		if (repo->packidx_cache[i] == NULL)
377 			break;
378 	}
379 
380 	if (i == nitems(repo->packidx_cache)) {
381 		got_packidx_close(repo->packidx_cache[i - 1]);
382 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
383 		    sizeof(repo->packidx_cache) -
384 		    sizeof(repo->packidx_cache[0]));
385 		i = 0;
386 	}
387 
388 	repo->packidx_cache[i] = dup_packidx(packidx);
389 }
390 
391 static const struct got_error *
392 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
393     struct got_repository *repo, struct got_object_id *id)
394 {
395 	const struct got_error *err;
396 	char *path_packdir;
397 	DIR *packdir;
398 	struct dirent *dent;
399 	char *path_packidx;
400 	int i;
401 
402 	/* Search pack index cache. */
403 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
404 		if (repo->packidx_cache[i] == NULL)
405 			break;
406 		*idx = get_object_idx(repo->packidx_cache[i], id);
407 		if (*idx != -1) {
408 			*packidx = dup_packidx(repo->packidx_cache[i]);
409 			if (*packidx == NULL)
410 				*idx = -1;
411 			return NULL;
412 		}
413 	}
414 	/* No luck. Search the filesystem. */
415 
416 	path_packdir = got_repo_get_path_objects_pack(repo);
417 	if (path_packdir == NULL)
418 		return got_error(GOT_ERR_NO_MEM);
419 
420 	packdir = opendir(path_packdir);
421 	if (packdir == NULL) {
422 		err = got_error_from_errno();
423 		goto done;
424 	}
425 
426 	while ((dent = readdir(packdir)) != NULL) {
427 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
428 			continue;
429 
430 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
431 		    dent->d_name) == -1) {
432 			err = got_error(GOT_ERR_NO_MEM);
433 			goto done;
434 		}
435 
436 		err = got_packidx_open(packidx, path_packidx);
437 		free(path_packidx);
438 		if (err)
439 			goto done;
440 
441 		*idx = get_object_idx(*packidx, id);
442 		if (*idx != -1) {
443 			err = NULL; /* found the object */
444 			cache_packidx(*packidx, repo);
445 			goto done;
446 		}
447 
448 		got_packidx_close(*packidx);
449 		*packidx = NULL;
450 	}
451 
452 	err = got_error(GOT_ERR_NO_OBJ);
453 done:
454 	free(path_packdir);
455 	if (packdir && closedir(packdir) != 0 && err == 0)
456 		err = got_error_from_errno();
457 	return err;
458 }
459 
460 static const struct got_error *
461 get_packfile_path(char **path_packfile, struct got_repository *repo,
462     struct got_packidx_v2_hdr *packidx)
463 {
464 	char *path_packdir;
465 	char hex[SHA1_DIGEST_STRING_LENGTH];
466 	char *sha1str;
467 	char *path_packidx;
468 
469 	*path_packfile = NULL;
470 
471 	path_packdir = got_repo_get_path_objects_pack(repo);
472 	if (path_packdir == NULL)
473 		return got_error(GOT_ERR_NO_MEM);
474 
475 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
476 	    hex, sizeof(hex));
477 	if (sha1str == NULL)
478 		return got_error(GOT_ERR_PACKIDX_CSUM);
479 
480 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
481 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
482 		*path_packfile = NULL;
483 		return got_error(GOT_ERR_NO_MEM);
484 	}
485 
486 	return NULL;
487 }
488 
489 const struct got_error *
490 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
491 {
492 	const struct got_error *err = NULL;
493 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
494 	struct got_packfile_hdr hdr;
495 	size_t n;
496 
497 	n = fread(&hdr, sizeof(hdr), 1, f);
498 	if (n != 1)
499 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
500 
501 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
502 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
503 	    betoh32(hdr.nobjects) != totobj)
504 		err = got_error(GOT_ERR_BAD_PACKFILE);
505 
506 	return err;
507 }
508 
509 static const struct got_error *
510 open_packfile(FILE **packfile, char **path_packfile,
511     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
512 {
513 	const struct got_error *err;
514 
515 	*packfile = NULL;
516 
517 	err = get_packfile_path(path_packfile, repo, packidx);
518 	if (err)
519 		return err;
520 
521 	*packfile = fopen(*path_packfile, "rb");
522 	if (*packfile == NULL) {
523 		err = got_error_from_errno();
524 		free(*path_packfile);
525 		return err;
526 	}
527 
528 	err = read_packfile_hdr(*packfile, packidx);
529 	if (err) {
530 		fclose(*packfile);
531 		*packfile = NULL;
532 	}
533 	return err;
534 }
535 
536 static const struct got_error *
537 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
538     FILE *packfile)
539 {
540 	uint8_t t = 0;
541 	uint64_t s = 0;
542 	uint8_t sizeN;
543 	size_t n;
544 	int i = 0;
545 
546 	do {
547 		/* We do not support size values which don't fit in 64 bit. */
548 		if (i > 9)
549 			return got_error(GOT_ERR_NO_SPACE);
550 
551 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
552 		if (n != 1)
553 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
554 
555 		if (i == 0) {
556 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
557 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
558 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
559 		} else {
560 			size_t shift = 4 + 7 * (i - 1);
561 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
562 		}
563 		i++;
564 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
565 
566 	*type = t;
567 	*size = s;
568 	*len = i * sizeof(sizeN);
569 	return NULL;
570 }
571 
572 static const struct got_error *
573 open_plain_object(struct got_object **obj, const char *path_packfile,
574     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
575 {
576 	*obj = calloc(1, sizeof(**obj));
577 	if (*obj == NULL)
578 		return got_error(GOT_ERR_NO_MEM);
579 
580 	(*obj)->path_packfile = strdup(path_packfile);
581 	if ((*obj)->path_packfile == NULL) {
582 		free(*obj);
583 		*obj = NULL;
584 		return got_error(GOT_ERR_NO_MEM);
585 	}
586 
587 	(*obj)->type = type;
588 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
589 	(*obj)->hdrlen = 0;
590 	(*obj)->size = size;
591 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
592 	(*obj)->pack_offset = offset;
593 
594 	return NULL;
595 }
596 
597 static const struct got_error *
598 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
599 {
600 	int64_t o = 0;
601 	uint8_t offN;
602 	size_t n;
603 	int i = 0;
604 
605 	do {
606 		/* We do not support offset values which don't fit in 64 bit. */
607 		if (i > 8)
608 			return got_error(GOT_ERR_NO_SPACE);
609 
610 		n = fread(&offN, sizeof(offN), 1, packfile);
611 		if (n != 1)
612 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
613 
614 		if (i == 0)
615 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
616 		else {
617 			o++;
618 			o <<= 7;
619 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
620 		}
621 		i++;
622 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
623 
624 	*offset = o;
625 	*len = i * sizeof(offN);
626 	return NULL;
627 }
628 
629 static const struct got_error *
630 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
631 {
632 	const struct got_error *err;
633 	int64_t negoffset;
634 	size_t negofflen;
635 
636 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
637 	if (err)
638 		return err;
639 
640 	/* Compute the base object's offset (must be in the same pack file). */
641 	*base_offset = (offset - negoffset);
642 	if (*base_offset <= 0)
643 		return got_error(GOT_ERR_BAD_PACKFILE);
644 
645 	return NULL;
646 }
647 
648 static const struct got_error *
649 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
650     FILE *, const char *, off_t, size_t, int, size_t);
651 
652 static const struct got_error *
653 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
654     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
655     size_t delta_data_offset)
656 {
657 	struct got_delta *delta;
658 
659 	delta = got_delta_open(path_packfile, delta_offset, tslen,
660 	    delta_type, delta_size, delta_data_offset);
661 	if (delta == NULL)
662 		return got_error(GOT_ERR_NO_MEM);
663 	/* delta is freed in got_object_close() */
664 	deltas->nentries++;
665 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
666 	return NULL;
667 }
668 
669 static const struct got_error *
670 resolve_offset_delta(struct got_delta_chain *deltas,
671     struct got_repository *repo, FILE *packfile, const char *path_packfile,
672     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size)
673 
674 {
675 	const struct got_error *err;
676 	off_t base_offset;
677 	uint8_t base_type;
678 	uint64_t base_size;
679 	size_t base_tslen;
680 	off_t delta_data_offset;
681 
682 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
683 	if (err)
684 		return err;
685 
686 	delta_data_offset = ftello(packfile);
687 	if (delta_data_offset == -1)
688 		return got_error_from_errno();
689 
690 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
691 	    delta_type, delta_size, delta_data_offset);
692 	if (err)
693 		return err;
694 
695 	/* An offset delta must be in the same packfile. */
696 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
697 		return got_error_from_errno();
698 
699 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
700 	    packfile);
701 	if (err)
702 		return err;
703 
704 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
705 	    base_offset, base_tslen, base_type, base_size);
706 }
707 
708 static const struct got_error *
709 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
710     FILE *packfile, const char *path_packfile, off_t delta_offset,
711     size_t tslen, int delta_type, size_t delta_size)
712 {
713 	const struct got_error *err;
714 	struct got_object_id id;
715 	struct got_packidx_v2_hdr *packidx;
716 	int idx;
717 	off_t base_offset;
718 	uint8_t base_type;
719 	uint64_t base_size;
720 	size_t base_tslen;
721 	size_t n;
722 	FILE *base_packfile;
723 	char *path_base_packfile;
724 	off_t delta_data_offset;
725 
726 	n = fread(&id, sizeof(id), 1, packfile);
727 	if (n != 1)
728 		return got_ferror(packfile, GOT_ERR_IO);
729 
730 	delta_data_offset = ftello(packfile);
731 	if (delta_data_offset == -1)
732 		return got_error_from_errno();
733 
734 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
735 	    delta_type, delta_size, delta_data_offset);
736 	if (err)
737 		return err;
738 
739 	err = search_packidx(&packidx, &idx, repo, &id);
740 	if (err)
741 		return err;
742 
743 	base_offset = get_object_offset(packidx, idx);
744 	if (base_offset == (uint64_t)-1) {
745 		got_packidx_close(packidx);
746 		return got_error(GOT_ERR_BAD_PACKIDX);
747 	}
748 
749 	err = open_packfile(&base_packfile, &path_base_packfile, repo, packidx);
750 	got_packidx_close(packidx);
751 	if (err)
752 		return err;
753 
754 	if (fseeko(base_packfile, base_offset, SEEK_SET) != 0) {
755 		err = got_error_from_errno();
756 		goto done;
757 	}
758 
759 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
760 	    base_packfile);
761 	if (err)
762 		goto done;
763 
764 	err = resolve_delta_chain(deltas, repo, base_packfile,
765 	    path_base_packfile, base_offset, base_tslen, base_type,
766 	    base_size);
767 done:
768 	free(path_base_packfile);
769 	if (base_packfile && fclose(base_packfile) == -1 && err == 0)
770 		err = got_error_from_errno();
771 	return err;
772 }
773 
774 static const struct got_error *
775 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
776     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
777     int delta_type, size_t delta_size)
778 {
779 	const struct got_error *err = NULL;
780 
781 	switch (delta_type) {
782 	case GOT_OBJ_TYPE_COMMIT:
783 	case GOT_OBJ_TYPE_TREE:
784 	case GOT_OBJ_TYPE_BLOB:
785 	case GOT_OBJ_TYPE_TAG:
786 		/* Plain types are the final delta base. Recursion ends. */
787 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
788 		    delta_type, delta_size, 0);
789 		break;
790 	case GOT_OBJ_TYPE_OFFSET_DELTA:
791 		err = resolve_offset_delta(deltas, repo, packfile,
792 		    path_packfile, delta_offset, tslen, delta_type,
793 		    delta_size);
794 		break;
795 	case GOT_OBJ_TYPE_REF_DELTA:
796 		err = resolve_ref_delta(deltas, repo, packfile,
797 		    path_packfile, delta_offset, tslen, delta_type,
798 		    delta_size);
799 		break;
800 	default:
801 		return got_error(GOT_ERR_NOT_IMPL);
802 	}
803 
804 	return err;
805 }
806 
807 static const struct got_error *
808 open_delta_object(struct got_object **obj, struct got_repository *repo,
809     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
810     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
811     int delta_type, size_t delta_size)
812 {
813 	const struct got_error *err = NULL;
814 	struct got_object_id base_id;
815 	uint8_t base_type;
816 	int resolved_type;
817 	uint64_t base_size;
818 	size_t base_tslen;
819 
820 	*obj = calloc(1, sizeof(**obj));
821 	if (*obj == NULL)
822 		return got_error(GOT_ERR_NO_MEM);
823 
824 	(*obj)->flags = 0;
825 	(*obj)->hdrlen = 0;
826 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
827 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
828 	(*obj)->pack_offset = offset + tslen;
829 
830 	(*obj)->path_packfile = strdup(path_packfile);
831 	if ((*obj)->path_packfile == NULL) {
832 		err = got_error(GOT_ERR_NO_MEM);
833 		goto done;
834 	}
835 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
836 
837 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
838 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
839 
840 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
841 	    path_packfile, offset, tslen, delta_type, delta_size);
842 	if (err)
843 		goto done;
844 
845 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
846 	if (err)
847 		goto done;
848 	(*obj)->type = resolved_type;
849 
850 done:
851 	if (err) {
852 		got_object_close(*obj);
853 		*obj = NULL;
854 	}
855 	return err;
856 }
857 
858 static const struct got_error *
859 open_packed_object(struct got_object **obj, struct got_repository *repo,
860     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
861 {
862 	const struct got_error *err = NULL;
863 	off_t offset;
864 	char *path_packfile;
865 	FILE *packfile;
866 	uint8_t type;
867 	uint64_t size;
868 	size_t tslen;
869 
870 	*obj = NULL;
871 
872 	offset = get_object_offset(packidx, idx);
873 	if (offset == (uint64_t)-1)
874 		return got_error(GOT_ERR_BAD_PACKIDX);
875 
876 	err = open_packfile(&packfile, &path_packfile, repo, packidx);
877 	if (err)
878 		return err;
879 
880 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
881 		err = got_error_from_errno();
882 		goto done;
883 	}
884 
885 	err = parse_object_type_and_size(&type, &size, &tslen, packfile);
886 	if (err)
887 		goto done;
888 
889 	switch (type) {
890 	case GOT_OBJ_TYPE_COMMIT:
891 	case GOT_OBJ_TYPE_TREE:
892 	case GOT_OBJ_TYPE_BLOB:
893 	case GOT_OBJ_TYPE_TAG:
894 		err = open_plain_object(obj, path_packfile, id, type,
895 		    offset + tslen, size);
896 		break;
897 
898 	case GOT_OBJ_TYPE_OFFSET_DELTA:
899 	case GOT_OBJ_TYPE_REF_DELTA:
900 		err = open_delta_object(obj, repo, packidx, path_packfile,
901 		    packfile, id, offset, tslen, type, size);
902 		break;
903 
904 	default:
905 		err = got_error(GOT_ERR_NOT_IMPL);
906 		goto done;
907 	}
908 done:
909 	free(path_packfile);
910 	if (packfile && fclose(packfile) == -1 && err == 0)
911 		err = got_error_from_errno();
912 	return err;
913 }
914 
915 const struct got_error *
916 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
917     struct got_repository *repo)
918 {
919 	const struct got_error *err = NULL;
920 	struct got_packidx_v2_hdr *packidx = NULL;
921 	int idx;
922 
923 	err = search_packidx(&packidx, &idx, repo, id);
924 	if (err)
925 		return err;
926 
927 	err = open_packed_object(obj, repo, packidx, idx, id);
928 	got_packidx_close(packidx);
929 	return err;
930 }
931 
932 static const struct got_error *
933 dump_delta_chain(struct got_delta_chain *deltas, FILE *outfile)
934 {
935 	const struct got_error *err = NULL;
936 	struct got_delta *delta;
937 	FILE *base_file, *accum_file;
938 	int n = 0;
939 
940 	if (SIMPLEQ_EMPTY(&deltas->entries))
941 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
942 
943 	base_file = got_opentemp();
944 	if (base_file == NULL)
945 		return got_error_from_errno();
946 
947 	accum_file = got_opentemp();
948 	if (accum_file == NULL) {
949 		err = got_error_from_errno();
950 		fclose(base_file);
951 		return err;
952 	}
953 
954 	/* Deltas are ordered in ascending order. */
955 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
956 		uint8_t *delta_buf = NULL;
957 		size_t delta_len = 0;
958 		FILE *delta_file;
959 
960 		delta_file = fopen(delta->path_packfile, "rb");
961 		if (delta_file == NULL) {
962 			err = got_error_from_errno();
963 			goto done;
964 		}
965 
966 
967 		if (n == 0) {
968 			/* Plain object types are the delta base. */
969 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
970 			    delta->type != GOT_OBJ_TYPE_TREE &&
971 			    delta->type != GOT_OBJ_TYPE_BLOB &&
972 			    delta->type != GOT_OBJ_TYPE_TAG) {
973 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
974 				goto done;
975 			}
976 
977 			if (fseeko(delta_file, delta->offset + delta->tslen,
978 			    SEEK_SET) != 0) {
979 				fclose(delta_file);
980 				err = got_error_from_errno();
981 				goto done;
982 			}
983 			err = got_inflate_to_file(&delta_len, delta_file,
984 			    base_file);
985 			fclose(delta_file);
986 			if (err)
987 				goto done;
988 			n++;
989 			rewind(base_file);
990 			continue;
991 		}
992 
993 		if (fseeko(delta_file, delta->data_offset, SEEK_CUR) != 0) {
994 			fclose(delta_file);
995 			err = got_error_from_errno();
996 			goto done;
997 		}
998 
999 		/* Delta streams should always fit in memory. */
1000 		err = got_inflate_to_mem(&delta_buf, &delta_len, delta_file);
1001 		fclose(delta_file);
1002 		if (err)
1003 			goto done;
1004 
1005 		err = got_delta_apply(base_file, delta_buf, delta_len,
1006 		    /* Final delta application writes to the output file. */
1007 		    ++n < deltas->nentries ? accum_file : outfile);
1008 		free(delta_buf);
1009 		if (err)
1010 			goto done;
1011 
1012 		if (n < deltas->nentries) {
1013 			/* Accumulated delta becomes the new base. */
1014 			FILE *tmp = accum_file;
1015 			accum_file = base_file;
1016 			base_file = tmp;
1017 			rewind(base_file);
1018 			rewind(accum_file);
1019 		}
1020 	}
1021 
1022 done:
1023 	fclose(base_file);
1024 	fclose(accum_file);
1025 	rewind(outfile);
1026 	return err;
1027 }
1028 
1029 const struct got_error *
1030 got_packfile_extract_object(FILE **f, struct got_object *obj,
1031     struct got_repository *repo)
1032 {
1033 	const struct got_error *err = NULL;
1034 	FILE *packfile = NULL;
1035 
1036 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1037 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1038 
1039 	*f = got_opentemp();
1040 	if (*f == NULL) {
1041 		err = got_error(GOT_ERR_FILE_OPEN);
1042 		goto done;
1043 	}
1044 
1045 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1046 		packfile = fopen(obj->path_packfile, "rb");
1047 		if (packfile == NULL) {
1048 			err = got_error_from_errno();
1049 			goto done;
1050 		}
1051 
1052 		if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
1053 			err = got_error_from_errno();
1054 			goto done;
1055 		}
1056 
1057 		err = got_inflate_to_file(&obj->size, packfile, *f);
1058 	} else
1059 		err = dump_delta_chain(&obj->deltas, *f);
1060 done:
1061 	if (packfile)
1062 		fclose(packfile);
1063 	if (err && *f)
1064 		fclose(*f);
1065 	return err;
1066 }