Gotweb

Blob

Date:: Tue Jan 23 16:49:03 2018 UTC
Message:: add support for opening ref delta objects
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 #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 static const struct got_error *
312 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
313     struct got_repository *repo, struct got_object_id *id)
314 {
315 	const struct got_error *err;
316 	char *path_packdir;
317 	DIR *packdir;
318 	struct dirent *dent;
319 	char *path_packidx;
320 
321 	path_packdir = got_repo_get_path_objects_pack(repo);
322 	if (path_packdir == NULL)
323 		return got_error(GOT_ERR_NO_MEM);
324 
325 	packdir = opendir(path_packdir);
326 	if (packdir == NULL) {
327 		err = got_error_from_errno();
328 		goto done;
329 	}
330 
331 	while ((dent = readdir(packdir)) != NULL) {
332 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
333 			continue;
334 
335 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
336 		    dent->d_name) == -1) {
337 			err = got_error(GOT_ERR_NO_MEM);
338 			goto done;
339 		}
340 
341 		err = got_packidx_open(packidx, path_packidx);
342 		free(path_packidx);
343 		if (err)
344 			goto done;
345 
346 		*idx = get_object_idx(*packidx, id);
347 		if (*idx != -1) {
348 			err = NULL; /* found the object */
349 			goto done;
350 		}
351 
352 		got_packidx_close(*packidx);
353 		*packidx = NULL;
354 	}
355 
356 	err = got_error(GOT_ERR_NO_OBJ);
357 done:
358 	free(path_packdir);
359 	if (closedir(packdir) != 0 && err == 0)
360 		err = got_error_from_errno();
361 	return err;
362 }
363 
364 const struct got_error *
365 get_packfile_path(char **path_packfile, struct got_repository *repo,
366     struct got_packidx_v2_hdr *packidx)
367 {
368 	char *path_packdir;
369 	char hex[SHA1_DIGEST_STRING_LENGTH];
370 	char *sha1str;
371 	char *path_packidx;
372 
373 	*path_packfile = NULL;
374 
375 	path_packdir = got_repo_get_path_objects_pack(repo);
376 	if (path_packdir == NULL)
377 		return got_error(GOT_ERR_NO_MEM);
378 
379 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
380 	    hex, sizeof(hex));
381 	if (sha1str == NULL)
382 		return got_error(GOT_ERR_PACKIDX_CSUM);
383 
384 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
385 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
386 		*path_packfile = NULL;
387 		return got_error(GOT_ERR_NO_MEM);
388 	}
389 
390 	return NULL;
391 }
392 
393 const struct got_error *
394 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
395 {
396 	const struct got_error *err = NULL;
397 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
398 	struct got_packfile_hdr hdr;
399 	size_t n;
400 
401 	n = fread(&hdr, sizeof(hdr), 1, f);
402 	if (n != 1)
403 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
404 
405 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
406 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
407 	    betoh32(hdr.nobjects) != totobj)
408 		err = got_error(GOT_ERR_BAD_PACKFILE);
409 
410 	return err;
411 }
412 
413 static const struct got_error *
414 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
415     FILE *packfile)
416 {
417 	uint8_t t = 0;
418 	uint64_t s = 0;
419 	uint8_t sizeN;
420 	size_t n;
421 	int i = 0;
422 
423 	do {
424 		/* We do not support size values which don't fit in 64 bit. */
425 		if (i > 9)
426 			return got_error(GOT_ERR_NO_SPACE);
427 
428 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
429 		if (n != 1)
430 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
431 
432 		if (i == 0) {
433 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
434 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
435 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
436 		} else {
437 			size_t shift = 4 + 7 * (i - 1);
438 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
439 		}
440 		i++;
441 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
442 
443 	*type = t;
444 	*size = s;
445 	*len = i * sizeof(sizeN);
446 	return NULL;
447 }
448 
449 static const struct got_error *
450 open_plain_object(struct got_object **obj, const char *path_packfile,
451     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
452 {
453 	*obj = calloc(1, sizeof(**obj));
454 	if (*obj == NULL)
455 		return got_error(GOT_ERR_NO_MEM);
456 
457 	(*obj)->path_packfile = strdup(path_packfile);
458 	if ((*obj)->path_packfile == NULL) {
459 		free(*obj);
460 		*obj = NULL;
461 		return got_error(GOT_ERR_NO_MEM);
462 	}
463 
464 	(*obj)->type = type;
465 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
466 	(*obj)->hdrlen = 0;
467 	(*obj)->size = size;
468 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
469 	(*obj)->pack_offset = offset;
470 
471 	return NULL;
472 }
473 
474 static const struct got_error *
475 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
476 {
477 	int64_t o = 0;
478 	uint8_t offN;
479 	size_t n;
480 	int i = 0;
481 
482 	do {
483 		/* We do not support offset values which don't fit in 64 bit. */
484 		if (i > 8)
485 			return got_error(GOT_ERR_NO_SPACE);
486 
487 		n = fread(&offN, sizeof(offN), 1, packfile);
488 		if (n != 1)
489 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
490 
491 		if (i == 0)
492 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
493 		else {
494 			o++;
495 			o <<= 7;
496 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
497 		}
498 		i++;
499 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
500 
501 	*offset = o;
502 	*len = i * sizeof(offN);
503 	return NULL;
504 }
505 
506 static const struct got_error *
507 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
508 {
509 	const struct got_error *err;
510 	int64_t negoffset;
511 	size_t negofflen;
512 
513 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
514 	if (err)
515 		return err;
516 
517 	/* Compute the base object's offset (must be in the same pack file). */
518 	*base_offset = (offset - negoffset);
519 	if (*base_offset <= 0)
520 		return got_error(GOT_ERR_BAD_PACKFILE);
521 
522 	return NULL;
523 }
524 
525 static const struct got_error *resolve_delta_chain(struct got_delta_chain *,
526     struct got_repository *repo, FILE *, const char *, int, off_t, size_t);
527 
528 static const struct got_error *
529 resolve_offset_delta(struct got_delta_chain *deltas,
530     struct got_repository *repo, FILE *packfile, const char *path_packfile,
531     off_t delta_offset)
532 {
533 	const struct got_error *err;
534 	off_t base_offset;
535 	uint8_t base_type;
536 	uint64_t base_size;
537 	size_t base_tslen;
538 
539 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
540 	if (err)
541 		return err;
542 
543 	/* An offset delta must be in the same packfile. */
544 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
545 		return got_error_from_errno();
546 
547 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
548 	    packfile);
549 	if (err)
550 		return err;
551 
552 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
553 	    base_type, base_offset + base_tslen, base_size);
554 }
555 
556 static const struct got_error *
557 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
558     FILE *packfile, const char *path_packfile, off_t delta_offset)
559 {
560 	const struct got_error *err;
561 	struct got_object_id id;
562 	struct got_packidx_v2_hdr *packidx;
563 	int idx;
564 	off_t base_offset;
565 	uint8_t base_type;
566 	uint64_t base_size;
567 	size_t base_tslen;
568 	size_t n;
569 	FILE *base_packfile;
570 	char *path_base_packfile;
571 
572 	n = fread(&id, sizeof(id), 1, packfile);
573 	if (n != 1)
574 		return got_ferror(packfile, GOT_ERR_IO);
575 
576 	err = search_packidx(&packidx, &idx, repo, &id);
577 	if (err)
578 		return err;
579 
580 	base_offset = get_object_offset(packidx, idx);
581 	if (base_offset == (uint64_t)-1) {
582 		got_packidx_close(packidx);
583 		return got_error(GOT_ERR_BAD_PACKIDX);
584 	}
585 
586 	err = get_packfile_path(&path_base_packfile, repo, packidx);
587 	got_packidx_close(packidx);
588 	if (err)
589 		return err;
590 
591 	base_packfile = fopen(path_base_packfile, "rb");
592 	if (base_packfile == NULL) {
593 		err = got_error_from_errno();
594 		goto done;
595 	}
596 
597 	if (fseeko(base_packfile, base_offset, SEEK_SET) != 0) {
598 		err = got_error_from_errno();
599 		goto done;
600 	}
601 
602 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
603 	    base_packfile);
604 	if (err)
605 		goto done;
606 
607 	err = resolve_delta_chain(deltas, repo, base_packfile,
608 	    path_base_packfile, base_type, base_offset + base_tslen, base_size);
609 done:
610 	free(path_base_packfile);
611 	if (base_packfile && fclose(base_packfile) == -1 && err == 0)
612 		err = got_error_from_errno();
613 	return err;
614 }
615 
616 static const struct got_error *
617 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
618     FILE *packfile, const char *path_packfile, int delta_type,
619     off_t delta_offset, size_t delta_size)
620 {
621 	const struct got_error *err = NULL;
622 	struct got_delta *delta;
623 
624 	delta = got_delta_open(path_packfile, delta_type, delta_offset,
625 	    delta_size);
626 	if (delta == NULL)
627 		return got_error(GOT_ERR_NO_MEM);
628 	deltas->nentries++;
629 	SIMPLEQ_INSERT_TAIL(&deltas->entries, delta, entry);
630 	/* In case of error below, delta is freed in got_object_close(). */
631 
632 	switch (delta_type) {
633 	case GOT_OBJ_TYPE_COMMIT:
634 	case GOT_OBJ_TYPE_TREE:
635 	case GOT_OBJ_TYPE_BLOB:
636 	case GOT_OBJ_TYPE_TAG:
637 		/* Plain types are the final delta base. Recursion ends. */
638 		break;
639 	case GOT_OBJ_TYPE_OFFSET_DELTA:
640 		err = resolve_offset_delta(deltas, repo, packfile,
641 		    path_packfile, delta_offset);
642 		break;
643 	case GOT_OBJ_TYPE_REF_DELTA:
644 		err = resolve_ref_delta(deltas, repo, packfile, path_packfile,
645 		    delta_offset);
646 		break;
647 	default:
648 		return got_error(GOT_ERR_NOT_IMPL);
649 	}
650 
651 	return err;
652 }
653 
654 static const struct got_error *
655 open_delta_object(struct got_object **obj, struct got_repository *repo,
656     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
657     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
658     int delta_type, size_t delta_size)
659 {
660 	const struct got_error *err = NULL;
661 	struct got_object_id base_id;
662 	uint8_t base_type;
663 	int resolved_type;
664 	uint64_t base_size;
665 	size_t base_tslen;
666 
667 	*obj = calloc(1, sizeof(**obj));
668 	if (*obj == NULL)
669 		return got_error(GOT_ERR_NO_MEM);
670 
671 	(*obj)->flags = 0;
672 	(*obj)->hdrlen = 0;
673 	(*obj)->size = 0; /* Not yet known because deltas aren't combined. */
674 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
675 	(*obj)->pack_offset = offset + tslen;
676 
677 	(*obj)->path_packfile = strdup(path_packfile);
678 	if ((*obj)->path_packfile == NULL) {
679 		err = got_error(GOT_ERR_NO_MEM);
680 		goto done;
681 	}
682 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
683 
684 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
685 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
686 
687 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
688 	    path_packfile, delta_type, offset, delta_size);
689 	if (err)
690 		goto done;
691 
692 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
693 	if (err)
694 		goto done;
695 	(*obj)->type = resolved_type;
696 
697 done:
698 	if (err) {
699 		got_object_close(*obj);
700 		*obj = NULL;
701 	}
702 	return err;
703 }
704 
705 static const struct got_error *
706 open_packed_object(struct got_object **obj, struct got_repository *repo,
707     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
708 {
709 	const struct got_error *err = NULL;
710 	off_t offset;
711 	char *path_packfile;
712 	FILE *packfile;
713 	uint8_t type;
714 	uint64_t size;
715 	size_t tslen;
716 
717 	*obj = NULL;
718 
719 	offset = get_object_offset(packidx, idx);
720 	if (offset == (uint64_t)-1)
721 		return got_error(GOT_ERR_BAD_PACKIDX);
722 
723 	err = get_packfile_path(&path_packfile, repo, packidx);
724 	if (err)
725 		return err;
726 
727 	packfile = fopen(path_packfile, "rb");
728 	if (packfile == NULL) {
729 		err = got_error_from_errno();
730 		goto done;
731 	}
732 
733 	err = read_packfile_hdr(packfile, packidx);
734 	if (err)
735 		goto done;
736 
737 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
738 		err = got_error_from_errno();
739 		goto done;
740 	}
741 
742 	err = parse_object_type_and_size(&type, &size, &tslen, packfile);
743 	if (err)
744 		goto done;
745 
746 	switch (type) {
747 	case GOT_OBJ_TYPE_COMMIT:
748 	case GOT_OBJ_TYPE_TREE:
749 	case GOT_OBJ_TYPE_BLOB:
750 		err = open_plain_object(obj, path_packfile, id, type,
751 		    offset + tslen, size);
752 		break;
753 
754 	case GOT_OBJ_TYPE_OFFSET_DELTA:
755 	case GOT_OBJ_TYPE_REF_DELTA:
756 		err = open_delta_object(obj, repo, packidx, path_packfile,
757 		    packfile, id, offset, tslen, type, size);
758 		break;
759 
760 	case GOT_OBJ_TYPE_TAG:
761 	default:
762 		err = got_error(GOT_ERR_NOT_IMPL);
763 		goto done;
764 	}
765 done:
766 	free(path_packfile);
767 	if (packfile && fclose(packfile) == -1 && err == 0)
768 		err = got_error_from_errno();
769 	return err;
770 }
771 
772 const struct got_error *
773 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
774     struct got_repository *repo)
775 {
776 	const struct got_error *err = NULL;
777 	struct got_packidx_v2_hdr *packidx = NULL;
778 	int idx;
779 
780 	err = search_packidx(&packidx, &idx, repo, id);
781 	if (err)
782 		return err;
783 
784 	err = open_packed_object(obj, repo, packidx, idx, id);
785 	got_packidx_close(packidx);
786 	return err;
787 }
788 
789 static const struct got_error *
790 dump_plain_object(FILE *infile, uint8_t type, size_t size, FILE *outfile)
791 {
792 	size_t n;
793 
794 	while (size > 0) {
795 		uint8_t data[2048];
796 		size_t len = MIN(size, sizeof(data));
797 
798 		n = fread(data, len, 1, infile);
799 		if (n != 1)
800 			return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
801 
802 		n = fwrite(data, len, 1, outfile);
803 		if (n != 1)
804 			return got_ferror(outfile, GOT_ERR_IO);
805 
806 		size -= len;
807 	}
808 
809 	rewind(outfile);
810 	return NULL;
811 }
812 
813 static const struct got_error *
814 dump_ref_delta_object(struct got_repository *repo, FILE *infile, uint8_t type,
815     size_t size, FILE *outfile)
816 {
817 	const struct got_error *err = NULL;
818 	struct got_object_id base_id;
819 	struct got_object *base_obj;
820 	size_t n;
821 
822 	if (size < sizeof(base_id))
823 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
824 
825 	n = fread(&base_id, sizeof(base_id), 1, infile);
826 	if (n != 1)
827 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
828 
829 	size -= sizeof(base_id);
830 	if (size <= 0)
831 		return got_ferror(infile, GOT_ERR_BAD_PACKFILE);
832 
833 	err = got_object_open(&base_obj, repo, &base_id);
834 	if (err)
835 		return err;
836 
837 	err = got_delta_apply(repo, infile, size, base_obj, outfile);
838 	got_object_close(base_obj);
839 	return err;
840 }
841 
842 const struct got_error *
843 got_packfile_extract_object(FILE **f, struct got_object *obj,
844     struct got_repository *repo)
845 {
846 	const struct got_error *err = NULL;
847 	FILE *packfile = NULL;
848 
849 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
850 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
851 
852 	*f = got_opentemp();
853 	if (*f == NULL) {
854 		err = got_error(GOT_ERR_FILE_OPEN);
855 		goto done;
856 	}
857 
858 	packfile = fopen(obj->path_packfile, "rb");
859 	if (packfile == NULL) {
860 		err = got_error_from_errno();
861 		goto done;
862 	}
863 
864 	if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
865 		err = got_error_from_errno();
866 		goto done;
867 	}
868 
869 	switch (obj->type) {
870 	case GOT_OBJ_TYPE_COMMIT:
871 	case GOT_OBJ_TYPE_TREE:
872 	case GOT_OBJ_TYPE_BLOB:
873 		err = dump_plain_object(packfile, obj->type, obj->size, *f);
874 		break;
875 	case GOT_OBJ_TYPE_REF_DELTA:
876 		err = dump_ref_delta_object(repo, packfile, obj->type,
877 		    obj->size, *f);
878 		break;
879 	case GOT_OBJ_TYPE_TAG:
880 	case GOT_OBJ_TYPE_OFFSET_DELTA:
881 	default:
882 		err = got_error(GOT_ERR_NOT_IMPL);
883 		goto done;
884 	}
885 done:
886 	if (packfile)
887 		fclose(packfile);
888 	if (err && *f)
889 		fclose(*f);
890 	return err;
891 }