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Date:: Tue Jan 23 14:19:45 2018 UTC
Message:: model delta chains in a better way
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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 #include "got_sha1.h"
36 #include "pack.h"
37 #include "path.h"
38 #include "delta.h"
39 #include "object.h"
40 
41 #define GOT_PACK_PREFIX		"pack-"
42 #define GOT_PACKFILE_SUFFIX	".pack"
43 #define GOT_PACKIDX_SUFFIX		".idx"
44 #define GOT_PACKFILE_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
45 				SHA1_DIGEST_STRING_LENGTH - 1 + \
46 				strlen(GOT_PACKFILE_SUFFIX))
47 #define GOT_PACKIDX_NAMELEN	(strlen(GOT_PACK_PREFIX) + \
48 				SHA1_DIGEST_STRING_LENGTH - 1 + \
49 				strlen(GOT_PACKIDX_SUFFIX))
50 
51 #ifndef MIN
52 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
53 #endif
54 
55 static const struct got_error *
56 verify_fanout_table(uint32_t *fanout_table)
57 {
58 	int i;
59 
60 	for (i = 0; i < 0xff - 1; i++) {
61 		if (be32toh(fanout_table[i]) > be32toh(fanout_table[i + 1]))
62 			return got_error(GOT_ERR_BAD_PACKIDX);
63 	}
64 
65 	return NULL;
66 }
67 
68 static const struct got_error *
69 get_packfile_size(size_t *size, const char *path_idx)
70 {
71 	struct stat sb;
72 	char *path_pack;
73 	char base_path[PATH_MAX];
74 	char *dot;
75 
76 	if (strlcpy(base_path, path_idx, PATH_MAX) > PATH_MAX)
77 		return got_error(GOT_ERR_NO_SPACE);
78 
79 	dot = strrchr(base_path, '.');
80 	if (dot == NULL)
81 		return got_error(GOT_ERR_BAD_PATH);
82 	*dot = '\0';
83 	if (asprintf(&path_pack, "%s.pack", base_path) == -1)
84 		return got_error(GOT_ERR_NO_MEM);
85 
86 	if (stat(path_pack, &sb) != 0) {
87 		free(path_pack);
88 		return got_error_from_errno();
89 	}
90 
91 	free(path_pack);
92 	*size = sb.st_size;
93 	return 0;
94 }
95 
96 const struct got_error *
97 got_packidx_open(struct got_packidx_v2_hdr **packidx, const char *path)
98 {
99 	struct got_packidx_v2_hdr *p;
100 	FILE *f;
101 	const struct got_error *err = NULL;
102 	size_t n, nobj, packfile_size;
103 	SHA1_CTX ctx;
104 	uint8_t sha1[SHA1_DIGEST_LENGTH];
105 
106 	SHA1Init(&ctx);
107 
108 	f = fopen(path, "rb");
109 	if (f == NULL)
110 		return got_error(GOT_ERR_BAD_PATH);
111 
112 	err = get_packfile_size(&packfile_size, path);
113 	if (err)
114 		return err;
115 
116 	p = calloc(1, sizeof(*p));
117 	if (p == NULL) {
118 		err = got_error(GOT_ERR_NO_MEM);
119 		goto done;
120 	}
121 
122 	n = fread(&p->magic, sizeof(p->magic), 1, f);
123 	if (n != 1) {
124 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
125 		goto done;
126 	}
127 
128 	if (betoh32(p->magic) != GOT_PACKIDX_V2_MAGIC) {
129 		err = got_error(GOT_ERR_BAD_PACKIDX);
130 		goto done;
131 	}
132 
133 	SHA1Update(&ctx, (uint8_t *)&p->magic, sizeof(p->magic));
134 
135 	n = fread(&p->version, sizeof(p->version), 1, f);
136 	if (n != 1) {
137 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
138 		goto done;
139 	}
140 
141 	if (betoh32(p->version) != GOT_PACKIDX_VERSION) {
142 		err = got_error(GOT_ERR_BAD_PACKIDX);
143 		goto done;
144 	}
145 
146 	SHA1Update(&ctx, (uint8_t *)&p->version, sizeof(p->version));
147 
148 	n = fread(&p->fanout_table, sizeof(p->fanout_table), 1, f);
149 	if (n != 1) {
150 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
151 		goto done;
152 	}
153 
154 	err = verify_fanout_table(p->fanout_table);
155 	if (err)
156 		goto done;
157 
158 	SHA1Update(&ctx, (uint8_t *)p->fanout_table, sizeof(p->fanout_table));
159 
160 	nobj = betoh32(p->fanout_table[0xff]);
161 
162 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
163 	if (p->sorted_ids == NULL) {
164 		err = got_error(GOT_ERR_NO_MEM);
165 		goto done;
166 	}
167 
168 	n = fread(p->sorted_ids, sizeof(*p->sorted_ids), nobj, f);
169 	if (n != nobj) {
170 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
171 		goto done;
172 	}
173 
174 	SHA1Update(&ctx, (uint8_t *)p->sorted_ids,
175 	    nobj * sizeof(*p->sorted_ids));
176 
177 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
178 	if (p->crc32 == NULL) {
179 		err = got_error(GOT_ERR_NO_MEM);
180 		goto done;
181 	}
182 
183 	n = fread(p->crc32, sizeof(*p->crc32), nobj, f);
184 	if (n != nobj) {
185 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
186 		goto done;
187 	}
188 
189 	SHA1Update(&ctx, (uint8_t *)p->crc32, nobj * sizeof(*p->crc32));
190 
191 	p->offsets = calloc(nobj, sizeof(*p->offsets));
192 	if (p->offsets == NULL) {
193 		err = got_error(GOT_ERR_NO_MEM);
194 		goto done;
195 	}
196 
197 	n = fread(p->offsets, sizeof(*p->offsets), nobj, f);
198 	if (n != nobj) {
199 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
200 		goto done;
201 	}
202 
203 	SHA1Update(&ctx, (uint8_t *)p->offsets, nobj * sizeof(*p->offsets));
204 
205 	/* Large file offsets are contained only in files > 2GB. */
206 	if (packfile_size <= 0x80000000)
207 		goto checksum;
208 
209 	p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
210 	if (p->large_offsets == NULL) {
211 		err = got_error(GOT_ERR_NO_MEM);
212 		goto done;
213 	}
214 
215 	n = fread(p->large_offsets, sizeof(*p->large_offsets), nobj, f);
216 	if (n != nobj) {
217 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
218 		goto done;
219 	}
220 
221 	SHA1Update(&ctx, (uint8_t*)p->large_offsets,
222 	    nobj * sizeof(*p->large_offsets));
223 
224 checksum:
225 	n = fread(&p->trailer, sizeof(p->trailer), 1, f);
226 	if (n != 1) {
227 		err = got_ferror(f, GOT_ERR_BAD_PACKIDX);
228 		goto done;
229 	}
230 
231 	SHA1Update(&ctx, p->trailer.packfile_sha1, SHA1_DIGEST_LENGTH);
232 	SHA1Final(sha1, &ctx);
233 	if (memcmp(p->trailer.packidx_sha1, sha1, SHA1_DIGEST_LENGTH) != 0)
234 		err = got_error(GOT_ERR_PACKIDX_CSUM);
235 done:
236 	fclose(f);
237 	if (err)
238 		got_packidx_close(p);
239 	else
240 		*packidx = p;
241 	return err;
242 }
243 
244 void
245 got_packidx_close(struct got_packidx_v2_hdr *packidx)
246 {
247 	free(packidx->sorted_ids);
248 	free(packidx->offsets);
249 	free(packidx->crc32);
250 	free(packidx->large_offsets);
251 	free(packidx);
252 }
253 
254 static int
255 is_packidx_filename(const char *name, size_t len)
256 {
257 	if (len != GOT_PACKIDX_NAMELEN)
258 		return 0;
259 
260 	if (strncmp(name, GOT_PACK_PREFIX, strlen(GOT_PACK_PREFIX)) != 0)
261 		return 0;
262 
263 	if (strcmp(name + strlen(GOT_PACK_PREFIX) +
264 	    SHA1_DIGEST_STRING_LENGTH - 1, GOT_PACKIDX_SUFFIX) != 0)
265 		return 0;
266 
267 	return 1;
268 }
269 
270 static off_t
271 get_object_offset(struct got_packidx_v2_hdr *packidx, int idx)
272 {
273 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
274 	uint32_t offset = betoh32(packidx->offsets[idx]);
275 	if (offset & GOT_PACKIDX_OFFSET_VAL_IS_LARGE_IDX) {
276 		uint64_t loffset;
277 		idx = offset & GOT_PACKIDX_OFFSET_VAL_MASK;
278 		if (idx < 0 || idx > totobj || packidx->large_offsets == NULL)
279 			return -1;
280 		loffset = betoh64(packidx->large_offsets[idx]);
281 		return (loffset > INT64_MAX ? -1 : (off_t)loffset);
282 	}
283 	return (off_t)(offset & GOT_PACKIDX_OFFSET_VAL_MASK);
284 }
285 
286 static int
287 get_object_idx(struct got_packidx_v2_hdr *packidx, struct got_object_id *id)
288 {
289 	u_int8_t id0 = id->sha1[0];
290 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
291 	int i = 0;
292 
293 	if (id0 > 0)
294 		i = betoh32(packidx->fanout_table[id0 - 1]);
295 
296 	while (i < totobj) {
297 		struct got_object_id *oid = &packidx->sorted_ids[i];
298 		uint32_t offset;
299 		int cmp = got_object_id_cmp(id, oid);
300 
301 		if (cmp == 0)
302 			return i;
303 		else if (cmp > 0)
304 			break;
305 		i++;
306 	}
307 
308 	return -1;
309 }
310 
311 const struct got_error *
312 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
313 {
314 	const struct got_error *err = NULL;
315 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
316 	struct got_packfile_hdr hdr;
317 	size_t n;
318 
319 	n = fread(&hdr, sizeof(hdr), 1, f);
320 	if (n != 1)
321 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
322 
323 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
324 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
325 	    betoh32(hdr.nobjects) != totobj)
326 		err = got_error(GOT_ERR_BAD_PACKFILE);
327 
328 	return err;
329 }
330 
331 static const struct got_error *
332 decode_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
333     FILE *packfile)
334 {
335 	uint8_t t = 0;
336 	uint64_t s = 0;
337 	uint8_t sizeN;
338 	size_t n;
339 	int i = 0;
340 
341 	do {
342 		/* We do not support size values which don't fit in 64 bit. */
343 		if (i > 9)
344 			return got_error(GOT_ERR_NO_SPACE);
345 
346 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
347 		if (n != 1)
348 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
349 
350 		if (i == 0) {
351 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
352 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
353 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
354 		} else {
355 			size_t shift = 4 + 7 * (i - 1);
356 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
357 		}
358 		i++;
359 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
360 
361 	*type = t;
362 	*size = s;
363 	*len = i * sizeof(sizeN);
364 	return NULL;
365 }
366 
367 static const struct got_error *
368 open_plain_object(struct got_object **obj, const char *path_packfile,
369     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
370 {
371 	*obj = calloc(1, sizeof(**obj));
372 	if (*obj == NULL)
373 		return got_error(GOT_ERR_NO_MEM);
374 
375 	(*obj)->path_packfile = strdup(path_packfile);
376 	if ((*obj)->path_packfile == NULL) {
377 		free(*obj);
378 		*obj = NULL;
379 		return got_error(GOT_ERR_NO_MEM);
380 	}
381 
382 	(*obj)->type = type;
383 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
384 	(*obj)->hdrlen = 0;
385 	(*obj)->size = size;
386 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
387 	(*obj)->pack_offset = offset;
388 
389 	return NULL;
390 }
391 
392 static const struct got_error *
393 decode_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
394 {
395 	int64_t o = 0;
396 	uint8_t offN;
397 	size_t n;
398 	int i = 0;
399 
400 	do {
401 		/* We do not support offset values which don't fit in 64 bit. */
402 		if (i > 8)
403 			return got_error(GOT_ERR_NO_SPACE);
404 
405 		n = fread(&offN, sizeof(offN), 1, packfile);
406 		if (n != 1)
407 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
408 
409 		if (i == 0)
410 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
411 		else {
412 			o++;
413 			o <<= 7;
414 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
415 		}
416 		i++;
417 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
418 
419 	*offset = o;
420 	*len = i * sizeof(offN);
421 	return NULL;
422 }
423 
424 static const struct got_error *
425 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
426 {
427 	const struct got_error *err;
428 	int64_t negoffset;
429 	size_t negofflen;
430 
431 	err = decode_negative_offset(&negoffset, &negofflen, packfile);
432 	if (err)
433 		return err;
434 
435 	/* Compute the base object's offset (must be in the same pack file). */
436 	*base_offset = (offset - negoffset);
437 	if (*base_offset <= 0)
438 		return got_error(GOT_ERR_BAD_PACKFILE);
439 
440 	return NULL;
441 }
442 
443 static const struct got_error *resolve_delta_chain(struct got_delta_chain *,
444     FILE *, const char *, int, off_t, size_t);
445 
446 static const struct got_error *
447 resolve_offset_delta(struct got_delta_chain *deltas, FILE *packfile,
448     const char *path_packfile, off_t delta_offset)
449 {
450 	const struct got_error *err;
451 	off_t base_offset;
452 	uint8_t base_type;
453 	uint64_t base_size;
454 	size_t base_tslen;
455 
456 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
457 	if (err)
458 		return err;
459 
460 	/* An offset delta must be in the same packfile. */
461 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
462 		return got_error_from_errno();
463 
464 	err = decode_object_type_and_size(&base_type, &base_size, &base_tslen,
465 	    packfile);
466 	if (err)
467 		return err;
468 
469 	return resolve_delta_chain(deltas, packfile, path_packfile,
470 	    base_type, base_offset + base_tslen, base_size);
471 }
472 
473 static const struct got_error *
474 resolve_delta_chain(struct got_delta_chain *deltas, FILE *packfile,
475     const char *path_packfile, int delta_type, off_t delta_offset,
476     size_t delta_size)
477 {
478 	const struct got_error *err = NULL;
479 	struct got_delta *delta;
480 
481 	delta = got_delta_open(path_packfile, delta_type, delta_offset,
482 	    delta_size);
483 	if (delta == NULL)
484 		return got_error(GOT_ERR_NO_MEM);
485 	deltas->nentries++;
486 	SIMPLEQ_INSERT_TAIL(&deltas->entries, delta, entry);
487 	/* In case of error below, delta is freed in got_object_close(). */
488 
489 	switch (delta_type) {
490 	case GOT_OBJ_TYPE_COMMIT:
491 	case GOT_OBJ_TYPE_TREE:
492 	case GOT_OBJ_TYPE_BLOB:
493 	case GOT_OBJ_TYPE_TAG:
494 		/* Plain types are the final delta base. Recursion ends. */
495 		break;
496 	case GOT_OBJ_TYPE_OFFSET_DELTA:
497 		err = resolve_offset_delta(deltas, packfile, path_packfile,
498 		    delta_offset);
499 		break;
500 	case GOT_OBJ_TYPE_REF_DELTA:
501 	default:
502 		return got_error(GOT_ERR_NOT_IMPL);
503 	}
504 
505 	return err;
506 }
507 
508 static const struct got_error *
509 open_offset_delta_object(struct got_object **obj,
510     struct got_repository *repo, struct got_packidx_v2_hdr *packidx,
511     const char *path_packfile, FILE *packfile, struct got_object_id *id,
512     off_t offset, size_t tslen, size_t delta_size)
513 {
514 	const struct got_error *err = NULL;
515 	struct got_object_id base_id;
516 	uint8_t base_type;
517 	int resolved_type;
518 	uint64_t base_size;
519 	size_t base_tslen;
520 
521 	*obj = calloc(1, sizeof(**obj));
522 	if (*obj == NULL)
523 		return got_error(GOT_ERR_NO_MEM);
524 
525 	(*obj)->flags = 0;
526 	(*obj)->hdrlen = 0;
527 	(*obj)->size = 0; /* Not yet known because deltas aren't combined. */
528 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
529 	(*obj)->pack_offset = offset + tslen;
530 
531 	(*obj)->path_packfile = strdup(path_packfile);
532 	if ((*obj)->path_packfile == NULL) {
533 		err = got_error(GOT_ERR_NO_MEM);
534 		goto done;
535 	}
536 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
537 
538 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
539 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
540 
541 	err = resolve_delta_chain(&(*obj)->deltas, packfile, path_packfile,
542 	    GOT_OBJ_TYPE_OFFSET_DELTA, offset, delta_size);
543 	if (err)
544 		goto done;
545 
546 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
547 	if (err)
548 		goto done;
549 	(*obj)->type = resolved_type;
550 
551 done:
552 	if (err) {
553 		got_object_close(*obj);
554 		*obj = NULL;
555 	}
556 	return err;
557 }
558 
559 static const struct got_error *
560 open_packed_object(struct got_object **obj, struct got_repository *repo,
561     const char *path_packdir, struct got_packidx_v2_hdr *packidx,
562     struct got_object_id *id)
563 {
564 	const struct got_error *err = NULL;
565 	int idx = get_object_idx(packidx, id);
566 	off_t offset;
567 	char hex[SHA1_DIGEST_STRING_LENGTH];
568 	char *sha1str;
569 	char *path_packfile;
570 	FILE *packfile;
571 	uint8_t type;
572 	uint64_t size;
573 	size_t tslen;
574 
575 	*obj = NULL;
576 	if (idx == -1) /* object not found in pack index */
577 		return NULL;
578 
579 	offset = get_object_offset(packidx, idx);
580 	if (offset == (uint64_t)-1)
581 		return got_error(GOT_ERR_BAD_PACKIDX);
582 
583 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
584 	    hex, sizeof(hex));
585 	if (sha1str == NULL)
586 		return got_error(GOT_ERR_PACKIDX_CSUM);
587 
588 	if (asprintf(&path_packfile, "%s/%s%s%s", path_packdir,
589 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1)
590 		return got_error(GOT_ERR_NO_MEM);
591 
592 	packfile = fopen(path_packfile, "rb");
593 	if (packfile == NULL) {
594 		err = got_error_from_errno();
595 		goto done;
596 	}
597 
598 	err = read_packfile_hdr(packfile, packidx);
599 	if (err)
600 		goto done;
601 
602 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
603 		err = got_error_from_errno();
604 		goto done;
605 	}
606 
607 	err = decode_object_type_and_size(&type, &size, &tslen, packfile);
608 	if (err)
609 		goto done;
610 
611 	switch (type) {
612 	case GOT_OBJ_TYPE_COMMIT:
613 	case GOT_OBJ_TYPE_TREE:
614 	case GOT_OBJ_TYPE_BLOB:
615 		err = open_plain_object(obj, path_packfile, id, type,
616 		    offset + tslen, size);
617 		break;
618 
619 	case GOT_OBJ_TYPE_OFFSET_DELTA:
620 		err = open_offset_delta_object(obj, repo, packidx,
621 		    path_packfile, packfile, id, offset, tslen, size);
622 		break;
623 
624 	case GOT_OBJ_TYPE_REF_DELTA:
625 	case GOT_OBJ_TYPE_TAG:
626 	default:
627 		err = got_error(GOT_ERR_NOT_IMPL);
628 		goto done;
629 	}
630 done:
631 	free(path_packfile);
632 	if (packfile && fclose(packfile) == -1 && err == 0)
633 		err = got_error_from_errno();
634 	return err;
635 }
636 
637 const struct got_error *
638 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
639     struct got_repository *repo)
640 {
641 	const struct got_error *err = NULL;
642 	DIR *packdir = NULL;
643 	struct dirent *dent;
644 	char *path_packdir = got_repo_get_path_objects_pack(repo);
645 
646 	if (path_packdir == NULL) {
647 		err = got_error(GOT_ERR_NO_MEM);
648 		goto done;
649 	}
650 
651 	packdir = opendir(path_packdir);
652 	if (packdir == NULL) {
653 		err = got_error_from_errno();
654 		goto done;
655 	}
656 
657 	while ((dent = readdir(packdir)) != NULL) {
658 		struct got_packidx_v2_hdr *packidx;
659 		char *path_packidx, *path_object;
660 
661 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
662 			continue;
663 
664 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
665 		    dent->d_name) == -1) {
666 			err = got_error(GOT_ERR_NO_MEM);
667 			goto done;
668 		}
669 
670 		err = got_packidx_open(&packidx, path_packidx);
671 		free(path_packidx);
672 		if (err)
673 			goto done;
674 
675 		err = open_packed_object(obj, repo, path_packdir, packidx, id);
676 		got_packidx_close(packidx);
677 		if (err)
678 			goto done;
679 		if (*obj != NULL)
680 			break;
681 	}
682 
683 done:
684 	free(path_packdir);
685 	if (packdir && closedir(packdir) != 0 && err == 0)
686 		err = got_error_from_errno();
687 	return err;
688 }
689 
690 static const struct got_error *
691 dump_plain_object(FILE *infile, uint8_t type, size_t size, FILE *outfile)
692 {
693 	size_t n;
694 
695 	while (size > 0) {
696 		uint8_t data[2048];
697 		size_t len = MIN(size, sizeof(data));
698 
699 		n = fread(data, len, 1, infile);
700 		if (n != 1)
701 			return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
702 
703 		n = fwrite(data, len, 1, outfile);
704 		if (n != 1)
705 			return got_ferror(outfile, GOT_ERR_IO);
706 
707 		size -= len;
708 	}
709 
710 	rewind(outfile);
711 	return NULL;
712 }
713 
714 static const struct got_error *
715 dump_ref_delta_object(struct got_repository *repo, FILE *infile, uint8_t type,
716     size_t size, FILE *outfile)
717 {
718 	const struct got_error *err = NULL;
719 	struct got_object_id base_id;
720 	struct got_object *base_obj;
721 	size_t n;
722 
723 	if (size < sizeof(base_id))
724 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
725 
726 	n = fread(&base_id, sizeof(base_id), 1, infile);
727 	if (n != 1)
728 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
729 
730 	size -= sizeof(base_id);
731 	if (size <= 0)
732 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
733 
734 	err = got_object_open(&base_obj, repo, &base_id);
735 	if (err)
736 		return err;
737 
738 	err = got_delta_apply(repo, infile, size, base_obj, outfile);
739 	got_object_close(base_obj);
740 	return err;
741 }
742 
743 const struct got_error *
744 got_packfile_extract_object(FILE **f, struct got_object *obj,
745     struct got_repository *repo)
746 {
747 	const struct got_error *err = NULL;
748 	FILE *packfile = NULL;
749 
750 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
751 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
752 
753 	*f = got_opentemp();
754 	if (*f == NULL) {
755 		err = got_error(GOT_ERR_FILE_OPEN);
756 		goto done;
757 	}
758 
759 	packfile = fopen(obj->path_packfile, "rb");
760 	if (packfile == NULL) {
761 		err = got_error_from_errno();
762 		goto done;
763 	}
764 
765 	if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
766 		err = got_error_from_errno();
767 		goto done;
768 	}
769 
770 	switch (obj->type) {
771 	case GOT_OBJ_TYPE_COMMIT:
772 	case GOT_OBJ_TYPE_TREE:
773 	case GOT_OBJ_TYPE_BLOB:
774 		err = dump_plain_object(packfile, obj->type, obj->size, *f);
775 		break;
776 	case GOT_OBJ_TYPE_REF_DELTA:
777 		err = dump_ref_delta_object(repo, packfile, obj->type,
778 		    obj->size, *f);
779 		break;
780 	case GOT_OBJ_TYPE_TAG:
781 	case GOT_OBJ_TYPE_OFFSET_DELTA:
782 	default:
783 		err = got_error(GOT_ERR_NOT_IMPL);
784 		goto done;
785 	}
786 done:
787 	if (packfile)
788 		fclose(packfile);
789 	if (err && *f)
790 		fclose(*f);
791 	return err;
792 }