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Date:: Wed Mar 14 00:21:09 2018 UTC
Message:: add a delta cache; saves us from reading + decompressing some deltas
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_lib.h"
37 #include "got_pack_lib.h"
38 #include "got_path_lib.h"
39 #include "got_delta_lib.h"
40 #include "got_zbuf_lib.h"
41 #include "got_object_lib.h"
42 #include "got_repository_lib.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 		int cmp = got_object_id_cmp(id, oid);
306 
307 		if (cmp == 0)
308 			return i;
309 		i++;
310 	}
311 
312 	return -1;
313 }
314 
315 static struct got_packidx_v2_hdr *
316 dup_packidx(struct got_packidx_v2_hdr *packidx)
317 {
318 	struct got_packidx_v2_hdr *p;
319 	size_t nobj;
320 
321 	p = calloc(1, sizeof(*p));
322 	if (p == NULL)
323 		return NULL;
324 
325 	memcpy(p, packidx, sizeof(*p));
326 	p->sorted_ids = NULL;
327 	p->crc32 = NULL;
328 	p->offsets = NULL;
329 	p->large_offsets = NULL;
330 
331 	nobj = betoh32(p->fanout_table[0xff]);
332 
333 	p->sorted_ids = calloc(nobj, sizeof(*p->sorted_ids));
334 	if (p->sorted_ids == NULL)
335 		goto err;
336 	memcpy(p->sorted_ids, packidx->sorted_ids, nobj * sizeof(*p->sorted_ids));
337 
338 	p->crc32 = calloc(nobj, sizeof(*p->crc32));
339 	if (p->crc32 == NULL)
340 		goto err;
341 	memcpy(p->crc32, packidx->crc32, nobj * sizeof(*p->crc32));
342 
343 	p->offsets = calloc(nobj, sizeof(*p->offsets));
344 	if (p->offsets == NULL)
345 		goto err;
346 	memcpy(p->offsets, packidx->offsets, nobj * sizeof(*p->offsets));
347 
348 	if (p->large_offsets) {
349 		p->large_offsets = calloc(nobj, sizeof(*p->large_offsets));
350 		if (p->large_offsets == NULL)
351 			goto err;
352 		memcpy(p->large_offsets, packidx->large_offsets,
353 		    nobj * sizeof(*p->large_offsets));
354 	}
355 
356 	return p;
357 
358 err:
359 	free(p->large_offsets);
360 	free(p->offsets);
361 	free(p->crc32);
362 	free(p->sorted_ids);
363 	free(p);
364 	return NULL;
365 }
366 
367 static void
368 cache_packidx(struct got_packidx_v2_hdr *packidx, struct got_repository *repo)
369 {
370 	int i;
371 
372 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
373 		if (repo->packidx_cache[i] == NULL)
374 			break;
375 	}
376 
377 	if (i == nitems(repo->packidx_cache)) {
378 		got_packidx_close(repo->packidx_cache[i - 1]);
379 		memmove(&repo->packidx_cache[1], &repo->packidx_cache[0],
380 		    sizeof(repo->packidx_cache) -
381 		    sizeof(repo->packidx_cache[0]));
382 		i = 0;
383 	}
384 
385 	repo->packidx_cache[i] = dup_packidx(packidx);
386 }
387 
388 static const struct got_error *
389 search_packidx(struct got_packidx_v2_hdr **packidx, int *idx,
390     struct got_repository *repo, struct got_object_id *id)
391 {
392 	const struct got_error *err;
393 	char *path_packdir;
394 	DIR *packdir;
395 	struct dirent *dent;
396 	char *path_packidx;
397 	int i;
398 
399 	/* Search pack index cache. */
400 	for (i = 0; i < nitems(repo->packidx_cache); i++) {
401 		if (repo->packidx_cache[i] == NULL)
402 			break;
403 		*idx = get_object_idx(repo->packidx_cache[i], id);
404 		if (*idx != -1) {
405 			*packidx = dup_packidx(repo->packidx_cache[i]);
406 			if (*packidx == NULL)
407 				return got_error(GOT_ERR_NO_MEM);
408 			return NULL;
409 		}
410 	}
411 	/* No luck. Search the filesystem. */
412 
413 	path_packdir = got_repo_get_path_objects_pack(repo);
414 	if (path_packdir == NULL)
415 		return got_error(GOT_ERR_NO_MEM);
416 
417 	packdir = opendir(path_packdir);
418 	if (packdir == NULL) {
419 		err = got_error_from_errno();
420 		goto done;
421 	}
422 
423 	while ((dent = readdir(packdir)) != NULL) {
424 		if (!is_packidx_filename(dent->d_name, dent->d_namlen))
425 			continue;
426 
427 		if (asprintf(&path_packidx, "%s/%s", path_packdir,
428 		    dent->d_name) == -1) {
429 			err = got_error(GOT_ERR_NO_MEM);
430 			goto done;
431 		}
432 
433 		err = got_packidx_open(packidx, path_packidx);
434 		free(path_packidx);
435 		if (err)
436 			goto done;
437 
438 		*idx = get_object_idx(*packidx, id);
439 		if (*idx != -1) {
440 			err = NULL; /* found the object */
441 			cache_packidx(*packidx, repo);
442 			goto done;
443 		}
444 
445 		got_packidx_close(*packidx);
446 		*packidx = NULL;
447 	}
448 
449 	err = got_error(GOT_ERR_NO_OBJ);
450 done:
451 	free(path_packdir);
452 	if (packdir && closedir(packdir) != 0 && err == 0)
453 		err = got_error_from_errno();
454 	return err;
455 }
456 
457 static const struct got_error *
458 get_packfile_path(char **path_packfile, struct got_repository *repo,
459     struct got_packidx_v2_hdr *packidx)
460 {
461 	char *path_packdir;
462 	char hex[SHA1_DIGEST_STRING_LENGTH];
463 	char *sha1str;
464 
465 	path_packdir = got_repo_get_path_objects_pack(repo);
466 	if (path_packdir == NULL)
467 		return got_error(GOT_ERR_NO_MEM);
468 
469 	sha1str = got_sha1_digest_to_str(packidx->trailer.packfile_sha1,
470 	    hex, sizeof(hex));
471 	if (sha1str == NULL)
472 		return got_error(GOT_ERR_PACKIDX_CSUM);
473 
474 	if (asprintf(path_packfile, "%s/%s%s%s", path_packdir,
475 	    GOT_PACK_PREFIX, sha1str, GOT_PACKFILE_SUFFIX) == -1) {
476 		*path_packfile = NULL;
477 		return got_error(GOT_ERR_NO_MEM);
478 	}
479 
480 	return NULL;
481 }
482 
483 const struct got_error *
484 read_packfile_hdr(FILE *f, struct got_packidx_v2_hdr *packidx)
485 {
486 	const struct got_error *err = NULL;
487 	uint32_t totobj = betoh32(packidx->fanout_table[0xff]);
488 	struct got_packfile_hdr hdr;
489 	size_t n;
490 
491 	n = fread(&hdr, sizeof(hdr), 1, f);
492 	if (n != 1)
493 		return got_ferror(f, GOT_ERR_BAD_PACKIDX);
494 
495 	if (betoh32(hdr.signature) != GOT_PACKFILE_SIGNATURE ||
496 	    betoh32(hdr.version) != GOT_PACKFILE_VERSION ||
497 	    betoh32(hdr.nobjects) != totobj)
498 		err = got_error(GOT_ERR_BAD_PACKFILE);
499 
500 	return err;
501 }
502 
503 static const struct got_error *
504 open_packfile(FILE **packfile, char **path_packfile,
505     struct got_repository *repo, struct got_packidx_v2_hdr *packidx)
506 {
507 	const struct got_error *err;
508 
509 	*packfile = NULL;
510 
511 	err = get_packfile_path(path_packfile, repo, packidx);
512 	if (err)
513 		return err;
514 
515 	*packfile = fopen(*path_packfile, "rb");
516 	if (*packfile == NULL) {
517 		err = got_error_from_errno();
518 		free(*path_packfile);
519 		return err;
520 	}
521 
522 	err = read_packfile_hdr(*packfile, packidx);
523 	if (err) {
524 		fclose(*packfile);
525 		*packfile = NULL;
526 	}
527 	return err;
528 }
529 
530 static const struct got_error *
531 parse_object_type_and_size(uint8_t *type, uint64_t *size, size_t *len,
532     FILE *packfile)
533 {
534 	uint8_t t = 0;
535 	uint64_t s = 0;
536 	uint8_t sizeN;
537 	size_t n;
538 	int i = 0;
539 
540 	do {
541 		/* We do not support size values which don't fit in 64 bit. */
542 		if (i > 9)
543 			return got_error(GOT_ERR_NO_SPACE);
544 
545 		n = fread(&sizeN, sizeof(sizeN), 1, packfile);
546 		if (n != 1)
547 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
548 
549 		if (i == 0) {
550 			t = (sizeN & GOT_PACK_OBJ_SIZE0_TYPE_MASK) >>
551 			    GOT_PACK_OBJ_SIZE0_TYPE_MASK_SHIFT;
552 			s = (sizeN & GOT_PACK_OBJ_SIZE0_VAL_MASK);
553 		} else {
554 			size_t shift = 4 + 7 * (i - 1);
555 			s |= ((sizeN & GOT_PACK_OBJ_SIZE_VAL_MASK) << shift);
556 		}
557 		i++;
558 	} while (sizeN & GOT_PACK_OBJ_SIZE_MORE);
559 
560 	*type = t;
561 	*size = s;
562 	*len = i * sizeof(sizeN);
563 	return NULL;
564 }
565 
566 static const struct got_error *
567 open_plain_object(struct got_object **obj, const char *path_packfile,
568     struct got_object_id *id, uint8_t type, off_t offset, size_t size)
569 {
570 	*obj = calloc(1, sizeof(**obj));
571 	if (*obj == NULL)
572 		return got_error(GOT_ERR_NO_MEM);
573 
574 	(*obj)->path_packfile = strdup(path_packfile);
575 	if ((*obj)->path_packfile == NULL) {
576 		free(*obj);
577 		*obj = NULL;
578 		return got_error(GOT_ERR_NO_MEM);
579 	}
580 
581 	(*obj)->type = type;
582 	(*obj)->flags = GOT_OBJ_FLAG_PACKED;
583 	(*obj)->hdrlen = 0;
584 	(*obj)->size = size;
585 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
586 	(*obj)->pack_offset = offset;
587 
588 	return NULL;
589 }
590 
591 static const struct got_error *
592 parse_negative_offset(int64_t *offset, size_t *len, FILE *packfile)
593 {
594 	int64_t o = 0;
595 	uint8_t offN;
596 	size_t n;
597 	int i = 0;
598 
599 	do {
600 		/* We do not support offset values which don't fit in 64 bit. */
601 		if (i > 8)
602 			return got_error(GOT_ERR_NO_SPACE);
603 
604 		n = fread(&offN, sizeof(offN), 1, packfile);
605 		if (n != 1)
606 			return got_ferror(packfile, GOT_ERR_BAD_PACKIDX);
607 
608 		if (i == 0)
609 			o = (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
610 		else {
611 			o++;
612 			o <<= 7;
613 			o += (offN & GOT_PACK_OBJ_DELTA_OFF_VAL_MASK);
614 		}
615 		i++;
616 	} while (offN & GOT_PACK_OBJ_DELTA_OFF_MORE);
617 
618 	*offset = o;
619 	*len = i * sizeof(offN);
620 	return NULL;
621 }
622 
623 static const struct got_error *
624 parse_offset_delta(off_t *base_offset, FILE *packfile, off_t offset)
625 {
626 	const struct got_error *err;
627 	int64_t negoffset;
628 	size_t negofflen;
629 
630 	err = parse_negative_offset(&negoffset, &negofflen, packfile);
631 	if (err)
632 		return err;
633 
634 	/* Compute the base object's offset (must be in the same pack file). */
635 	*base_offset = (offset - negoffset);
636 	if (*base_offset <= 0)
637 		return got_error(GOT_ERR_BAD_PACKFILE);
638 
639 	return NULL;
640 }
641 
642 static const struct got_error *
643 resolve_delta_chain(struct got_delta_chain *, struct got_repository *,
644     FILE *, const char *, off_t, size_t, int, size_t);
645 
646 static const struct got_error *
647 add_delta(struct got_delta_chain *deltas, const char *path_packfile,
648     off_t delta_offset, size_t tslen, int delta_type, size_t delta_size,
649     size_t delta_data_offset)
650 {
651 	struct got_delta *delta;
652 
653 	delta = got_delta_open(path_packfile, delta_offset, tslen,
654 	    delta_type, delta_size, delta_data_offset);
655 	if (delta == NULL)
656 		return got_error(GOT_ERR_NO_MEM);
657 	/* delta is freed in got_object_close() */
658 	deltas->nentries++;
659 	SIMPLEQ_INSERT_HEAD(&deltas->entries, delta, entry);
660 	return NULL;
661 }
662 
663 static const struct got_error *
664 resolve_offset_delta(struct got_delta_chain *deltas,
665     struct got_repository *repo, FILE *packfile, const char *path_packfile,
666     off_t delta_offset,size_t tslen, int delta_type, size_t delta_size)
667 
668 {
669 	const struct got_error *err;
670 	off_t base_offset;
671 	uint8_t base_type;
672 	uint64_t base_size;
673 	size_t base_tslen;
674 	off_t delta_data_offset;
675 
676 	err = parse_offset_delta(&base_offset, packfile, delta_offset);
677 	if (err)
678 		return err;
679 
680 	delta_data_offset = ftello(packfile);
681 	if (delta_data_offset == -1)
682 		return got_error_from_errno();
683 
684 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
685 	    delta_type, delta_size, delta_data_offset);
686 	if (err)
687 		return err;
688 
689 	/* An offset delta must be in the same packfile. */
690 	if (fseeko(packfile, base_offset, SEEK_SET) != 0)
691 		return got_error_from_errno();
692 
693 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
694 	    packfile);
695 	if (err)
696 		return err;
697 
698 	return resolve_delta_chain(deltas, repo, packfile, path_packfile,
699 	    base_offset, base_tslen, base_type, base_size);
700 }
701 
702 static const struct got_error *
703 resolve_ref_delta(struct got_delta_chain *deltas, struct got_repository *repo,
704     FILE *packfile, const char *path_packfile, off_t delta_offset,
705     size_t tslen, int delta_type, size_t delta_size)
706 {
707 	const struct got_error *err;
708 	struct got_object_id id;
709 	struct got_packidx_v2_hdr *packidx;
710 	int idx;
711 	off_t base_offset;
712 	uint8_t base_type;
713 	uint64_t base_size;
714 	size_t base_tslen;
715 	size_t n;
716 	FILE *base_packfile;
717 	char *path_base_packfile;
718 	off_t delta_data_offset;
719 
720 	n = fread(&id, sizeof(id), 1, packfile);
721 	if (n != 1)
722 		return got_ferror(packfile, GOT_ERR_IO);
723 
724 	delta_data_offset = ftello(packfile);
725 	if (delta_data_offset == -1)
726 		return got_error_from_errno();
727 
728 	err = add_delta(deltas, path_packfile, delta_offset, tslen,
729 	    delta_type, delta_size, delta_data_offset);
730 	if (err)
731 		return err;
732 
733 	err = search_packidx(&packidx, &idx, repo, &id);
734 	if (err)
735 		return err;
736 
737 	base_offset = get_object_offset(packidx, idx);
738 	if (base_offset == (uint64_t)-1) {
739 		got_packidx_close(packidx);
740 		return got_error(GOT_ERR_BAD_PACKIDX);
741 	}
742 
743 	err = open_packfile(&base_packfile, &path_base_packfile, repo, packidx);
744 	got_packidx_close(packidx);
745 	if (err)
746 		return err;
747 
748 	if (fseeko(base_packfile, base_offset, SEEK_SET) != 0) {
749 		err = got_error_from_errno();
750 		goto done;
751 	}
752 
753 	err = parse_object_type_and_size(&base_type, &base_size, &base_tslen,
754 	    base_packfile);
755 	if (err)
756 		goto done;
757 
758 	err = resolve_delta_chain(deltas, repo, base_packfile,
759 	    path_base_packfile, base_offset, base_tslen, base_type,
760 	    base_size);
761 done:
762 	free(path_base_packfile);
763 	if (base_packfile && fclose(base_packfile) == -1 && err == 0)
764 		err = got_error_from_errno();
765 	return err;
766 }
767 
768 static const struct got_error *
769 resolve_delta_chain(struct got_delta_chain *deltas, struct got_repository *repo,
770     FILE *packfile, const char *path_packfile, off_t delta_offset, size_t tslen,
771     int delta_type, size_t delta_size)
772 {
773 	const struct got_error *err = NULL;
774 
775 	switch (delta_type) {
776 	case GOT_OBJ_TYPE_COMMIT:
777 	case GOT_OBJ_TYPE_TREE:
778 	case GOT_OBJ_TYPE_BLOB:
779 	case GOT_OBJ_TYPE_TAG:
780 		/* Plain types are the final delta base. Recursion ends. */
781 		err = add_delta(deltas, path_packfile, delta_offset, tslen,
782 		    delta_type, delta_size, 0);
783 		break;
784 	case GOT_OBJ_TYPE_OFFSET_DELTA:
785 		err = resolve_offset_delta(deltas, repo, packfile,
786 		    path_packfile, delta_offset, tslen, delta_type,
787 		    delta_size);
788 		break;
789 	case GOT_OBJ_TYPE_REF_DELTA:
790 		err = resolve_ref_delta(deltas, repo, packfile,
791 		    path_packfile, delta_offset, tslen, delta_type,
792 		    delta_size);
793 		break;
794 	default:
795 		return got_error(GOT_ERR_NOT_IMPL);
796 	}
797 
798 	return err;
799 }
800 
801 static const struct got_error *
802 open_delta_object(struct got_object **obj, struct got_repository *repo,
803     struct got_packidx_v2_hdr *packidx, const char *path_packfile,
804     FILE *packfile, struct got_object_id *id, off_t offset, size_t tslen,
805     int delta_type, size_t delta_size)
806 {
807 	const struct got_error *err = NULL;
808 	int resolved_type;
809 
810 	*obj = calloc(1, sizeof(**obj));
811 	if (*obj == NULL)
812 		return got_error(GOT_ERR_NO_MEM);
813 
814 	(*obj)->flags = 0;
815 	(*obj)->hdrlen = 0;
816 	(*obj)->size = 0; /* Not known because deltas aren't applied yet. */
817 	memcpy(&(*obj)->id, id, sizeof((*obj)->id));
818 	(*obj)->pack_offset = offset + tslen;
819 
820 	(*obj)->path_packfile = strdup(path_packfile);
821 	if ((*obj)->path_packfile == NULL) {
822 		err = got_error(GOT_ERR_NO_MEM);
823 		goto done;
824 	}
825 	(*obj)->flags |= GOT_OBJ_FLAG_PACKED;
826 
827 	SIMPLEQ_INIT(&(*obj)->deltas.entries);
828 	(*obj)->flags |= GOT_OBJ_FLAG_DELTIFIED;
829 
830 	err = resolve_delta_chain(&(*obj)->deltas, repo, packfile,
831 	    path_packfile, offset, tslen, delta_type, delta_size);
832 	if (err)
833 		goto done;
834 
835 	err = got_delta_chain_get_base_type(&resolved_type, &(*obj)->deltas);
836 	if (err)
837 		goto done;
838 	(*obj)->type = resolved_type;
839 
840 done:
841 	if (err) {
842 		got_object_close(*obj);
843 		*obj = NULL;
844 	}
845 	return err;
846 }
847 
848 static const struct got_error *
849 open_packed_object(struct got_object **obj, struct got_repository *repo,
850     struct got_packidx_v2_hdr *packidx, int idx, struct got_object_id *id)
851 {
852 	const struct got_error *err = NULL;
853 	off_t offset;
854 	char *path_packfile;
855 	FILE *packfile;
856 	uint8_t type;
857 	uint64_t size;
858 	size_t tslen;
859 
860 	*obj = NULL;
861 
862 	offset = get_object_offset(packidx, idx);
863 	if (offset == (uint64_t)-1)
864 		return got_error(GOT_ERR_BAD_PACKIDX);
865 
866 	err = open_packfile(&packfile, &path_packfile, repo, packidx);
867 	if (err)
868 		return err;
869 
870 	if (fseeko(packfile, offset, SEEK_SET) != 0) {
871 		err = got_error_from_errno();
872 		goto done;
873 	}
874 
875 	err = parse_object_type_and_size(&type, &size, &tslen, packfile);
876 	if (err)
877 		goto done;
878 
879 	switch (type) {
880 	case GOT_OBJ_TYPE_COMMIT:
881 	case GOT_OBJ_TYPE_TREE:
882 	case GOT_OBJ_TYPE_BLOB:
883 	case GOT_OBJ_TYPE_TAG:
884 		err = open_plain_object(obj, path_packfile, id, type,
885 		    offset + tslen, size);
886 		break;
887 
888 	case GOT_OBJ_TYPE_OFFSET_DELTA:
889 	case GOT_OBJ_TYPE_REF_DELTA:
890 		err = open_delta_object(obj, repo, packidx, path_packfile,
891 		    packfile, id, offset, tslen, type, size);
892 		break;
893 
894 	default:
895 		err = got_error(GOT_ERR_NOT_IMPL);
896 		goto done;
897 	}
898 done:
899 	free(path_packfile);
900 	if (packfile && fclose(packfile) == -1 && err == 0)
901 		err = got_error_from_errno();
902 	return err;
903 }
904 
905 const struct got_error *
906 got_packfile_open_object(struct got_object **obj, struct got_object_id *id,
907     struct got_repository *repo)
908 {
909 	const struct got_error *err = NULL;
910 	struct got_packidx_v2_hdr *packidx = NULL;
911 	int idx;
912 
913 	err = search_packidx(&packidx, &idx, repo, id);
914 	if (err)
915 		return err;
916 
917 	err = open_packed_object(obj, repo, packidx, idx, id);
918 	got_packidx_close(packidx);
919 	return err;
920 }
921 
922 static const struct got_error *
923 get_delta_sizes(uint64_t *base_size, uint64_t *result_size,
924     struct got_delta *delta)
925 {
926 	const struct got_error *err;
927 	uint8_t *delta_buf = NULL;
928 	size_t delta_len = 0;
929 	FILE *delta_file;
930 
931 	delta_file = fopen(delta->path_packfile, "rb");
932 	if (delta_file == NULL)
933 		return got_error_from_errno();
934 
935 	if (fseeko(delta_file, delta->data_offset, SEEK_CUR) != 0) {
936 		err = got_error_from_errno();
937 		fclose(delta_file);
938 		return err;
939 	}
940 
941 	err = got_inflate_to_mem(&delta_buf, &delta_len, delta_file);
942 	fclose(delta_file);
943 	if (err)
944 		return err;
945 
946 	err = got_delta_get_sizes(base_size, result_size, delta_buf, delta_len);
947 	free(delta_buf);
948 	return err;
949 }
950 
951 static const struct got_error *
952 get_delta_chain_max_size(uint64_t *max_size, struct got_delta_chain *deltas)
953 {
954 	struct got_delta *delta;
955 	uint64_t base_size = 0, result_size = 0;
956 
957 	*max_size = 0;
958 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
959 		/* Plain object types are the delta base. */
960 		if (delta->type != GOT_OBJ_TYPE_COMMIT &&
961 		    delta->type != GOT_OBJ_TYPE_TREE &&
962 		    delta->type != GOT_OBJ_TYPE_BLOB &&
963 		    delta->type != GOT_OBJ_TYPE_TAG) {
964 			const struct got_error *err;
965 			err = get_delta_sizes(&base_size, &result_size, delta);
966 			if (err)
967 				return err;
968 		} else
969 			base_size = delta->size;
970 		if (base_size > *max_size)
971 			*max_size = base_size;
972 		if (result_size > *max_size)
973 			*max_size = result_size;
974 	}
975 
976 	return NULL;
977 }
978 
979 void
980 clear_delta_cache_entry(struct got_delta_cache_entry *entry)
981 {
982 	entry->data_offset = 0;
983 	free(entry->delta_buf);
984 	entry->delta_buf = NULL;
985 	entry->delta_len = 0;
986 }
987 
988 void
989 add_delta_cache_entry(struct got_delta_cache *cache, off_t data_offset,
990     uint8_t *delta_buf, size_t delta_len)
991 {
992 	int i;
993 	struct got_delta_cache_entry *entry;
994 
995 	for (i = 0; i < nitems(cache->deltas); i++) {
996 		entry = &cache->deltas[i];
997 		if (entry->data_offset == 0)
998 			break;
999 	}
1000 
1001 	if (i == nitems(cache->deltas)) {
1002 		entry = &cache->deltas[i - 1];
1003 		clear_delta_cache_entry(entry);
1004 		memmove(&cache->deltas[1], &cache->deltas[0],
1005 		    sizeof(cache->deltas) - sizeof(cache->deltas[0]));
1006 		i = 0;
1007 	}
1008 
1009 	entry = &cache->deltas[i];
1010 	entry->delta_buf = calloc(1, delta_len);
1011 	if (entry->delta_buf == NULL)
1012 		return;
1013 	entry->data_offset = data_offset;
1014 	memcpy(entry->delta_buf, delta_buf, delta_len);
1015 	entry->delta_len = delta_len;
1016 }
1017 
1018 void
1019 cache_delta(off_t data_offset, uint8_t *delta_buf, size_t delta_len,
1020     const char *path_packfile, struct got_repository *repo)
1021 {
1022 	struct got_delta_cache *cache;
1023 	int i;
1024 
1025 	for (i = 0; i < nitems(repo->delta_cache); i++) {
1026 		cache = &repo->delta_cache[i];
1027 		if (cache->path_packfile == NULL)
1028 			break;
1029 		if (strcmp(cache->path_packfile, path_packfile) == 0) {
1030 			add_delta_cache_entry(cache, data_offset, delta_buf,
1031 			    delta_len);
1032 			return;
1033 		}
1034 	}
1035 
1036 	if (i == nitems(repo->delta_cache)) {
1037 		int j;
1038 		cache = &repo->delta_cache[i - 1];
1039 		free(cache->path_packfile);
1040 		cache->path_packfile = NULL;
1041 		for (j = 0; j < nitems(cache->deltas); j++) {
1042 			struct got_delta_cache_entry *entry = &cache->deltas[j];
1043 			if (entry->data_offset == 0)
1044 				break;
1045 			clear_delta_cache_entry(entry);
1046 		}
1047 		memmove(&repo->delta_cache[1], &repo->delta_cache[0],
1048 		    sizeof(repo->delta_cache) - sizeof(repo->delta_cache[0]));
1049 		i = 0;
1050 	}
1051 
1052 	cache = &repo->delta_cache[i];
1053 	cache->path_packfile = strdup(path_packfile);
1054 	if (cache->path_packfile == NULL)
1055 		return;
1056 	add_delta_cache_entry(cache, data_offset, delta_buf, delta_len);
1057 }
1058 
1059 void
1060 get_cached_delta(uint8_t **delta_buf, size_t *delta_len,
1061     off_t data_offset, const char *path_packfile, struct got_repository *repo)
1062 {
1063 	struct got_delta_cache *cache;
1064 	struct got_delta_cache_entry *entry;
1065 	int i;
1066 
1067 	*delta_buf = NULL;
1068 	*delta_len = 0;
1069 
1070 	for (i = 0; i < nitems(repo->delta_cache); i++) {
1071 		cache = &repo->delta_cache[i];
1072 		if (cache->path_packfile == NULL)
1073 			return;
1074 		if (strcmp(cache->path_packfile, path_packfile) == 0)
1075 			break;
1076 	}
1077 
1078 	if (i == nitems(repo->delta_cache))
1079 		return;
1080 
1081 	for (i = 0; i < nitems(cache->deltas); i++) {
1082 		entry = &cache->deltas[i];
1083 		if (entry->data_offset == 0)
1084 			break;
1085 		if (entry->data_offset == data_offset) {
1086 			*delta_buf = entry->delta_buf;
1087 			*delta_len = entry->delta_len;
1088 			break;
1089 		}
1090 	}
1091 }
1092 
1093 static const struct got_error *
1094 dump_delta_chain(struct got_delta_chain *deltas, FILE *outfile,
1095     const char *path_packfile, struct got_repository *repo)
1096 {
1097 	const struct got_error *err = NULL;
1098 	struct got_delta *delta;
1099 	FILE *base_file = NULL, *accum_file = NULL;
1100 	uint64_t max_size;
1101 	int n = 0;
1102 
1103 	if (SIMPLEQ_EMPTY(&deltas->entries))
1104 		return got_error(GOT_ERR_BAD_DELTA_CHAIN);
1105 
1106 	err = get_delta_chain_max_size(&max_size, deltas);
1107 	if (err)
1108 		return err;
1109 
1110 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
1111 		base_file = fmemopen(NULL, max_size, "w+");
1112 	else
1113 		base_file = got_opentemp();
1114 	if (base_file == NULL)
1115 		return got_error_from_errno();
1116 
1117 	if (max_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
1118 		accum_file = fmemopen(NULL, max_size, "w+");
1119 	else
1120 		accum_file = got_opentemp();
1121 	if (accum_file == NULL) {
1122 		err = got_error_from_errno();
1123 		fclose(base_file);
1124 		return err;
1125 	}
1126 
1127 	/* Deltas are ordered in ascending order. */
1128 	SIMPLEQ_FOREACH(delta, &deltas->entries, entry) {
1129 		uint8_t *delta_buf = NULL;
1130 		size_t delta_len = 0;
1131 		FILE *delta_file;
1132 		int is_cached = 0;
1133 
1134 		delta_file = fopen(delta->path_packfile, "rb");
1135 		if (delta_file == NULL) {
1136 			err = got_error_from_errno();
1137 			goto done;
1138 		}
1139 
1140 		if (n == 0) {
1141 			/* Plain object types are the delta base. */
1142 			if (delta->type != GOT_OBJ_TYPE_COMMIT &&
1143 			    delta->type != GOT_OBJ_TYPE_TREE &&
1144 			    delta->type != GOT_OBJ_TYPE_BLOB &&
1145 			    delta->type != GOT_OBJ_TYPE_TAG) {
1146 				err = got_error(GOT_ERR_BAD_DELTA_CHAIN);
1147 				goto done;
1148 			}
1149 
1150 			if (fseeko(delta_file, delta->offset + delta->tslen,
1151 			    SEEK_SET) != 0) {
1152 				fclose(delta_file);
1153 				err = got_error_from_errno();
1154 				goto done;
1155 			}
1156 			err = got_inflate_to_file(&delta_len, delta_file,
1157 			    base_file);
1158 			fclose(delta_file);
1159 			if (err)
1160 				goto done;
1161 			n++;
1162 			rewind(base_file);
1163 			continue;
1164 		}
1165 
1166 		get_cached_delta(&delta_buf, &delta_len, delta->data_offset,
1167 		    path_packfile, repo);
1168 
1169 		if (delta_buf == NULL) {
1170 			if (fseeko(delta_file, delta->data_offset, SEEK_CUR)
1171 			    != 0) {
1172 				fclose(delta_file);
1173 				err = got_error_from_errno();
1174 				goto done;
1175 			}
1176 
1177 			/* Delta streams should always fit in memory. */
1178 			err = got_inflate_to_mem(&delta_buf, &delta_len,
1179 			    delta_file);
1180 			fclose(delta_file);
1181 			if (err)
1182 				goto done;
1183 
1184 			cache_delta(delta->data_offset, delta_buf, delta_len,
1185 			    path_packfile, repo);
1186 		} else
1187 			is_cached = 1;
1188 
1189 		err = got_delta_apply(base_file, delta_buf, delta_len,
1190 		    /* Final delta application writes to the output file. */
1191 		    ++n < deltas->nentries ? accum_file : outfile);
1192 		if (!is_cached)
1193 			free(delta_buf);
1194 		if (err)
1195 			goto done;
1196 
1197 		if (n < deltas->nentries) {
1198 			/* Accumulated delta becomes the new base. */
1199 			FILE *tmp = accum_file;
1200 			accum_file = base_file;
1201 			base_file = tmp;
1202 			rewind(base_file);
1203 			rewind(accum_file);
1204 		}
1205 	}
1206 
1207 done:
1208 	fclose(base_file);
1209 	fclose(accum_file);
1210 	rewind(outfile);
1211 	return err;
1212 }
1213 
1214 const struct got_error *
1215 got_packfile_extract_object(FILE **f, struct got_object *obj,
1216     struct got_repository *repo)
1217 {
1218 	const struct got_error *err = NULL;
1219 	FILE *packfile = NULL;
1220 
1221 	if ((obj->flags & GOT_OBJ_FLAG_PACKED) == 0)
1222 		return got_error(GOT_ERR_OBJ_NOT_PACKED);
1223 
1224 	*f = got_opentemp();
1225 	if (*f == NULL) {
1226 		err = got_error(GOT_ERR_FILE_OPEN);
1227 		goto done;
1228 	}
1229 
1230 	if ((obj->flags & GOT_OBJ_FLAG_DELTIFIED) == 0) {
1231 		packfile = fopen(obj->path_packfile, "rb");
1232 		if (packfile == NULL) {
1233 			err = got_error_from_errno();
1234 			goto done;
1235 		}
1236 
1237 		if (fseeko(packfile, obj->pack_offset, SEEK_SET) != 0) {
1238 			err = got_error_from_errno();
1239 			goto done;
1240 		}
1241 
1242 		err = got_inflate_to_file(&obj->size, packfile, *f);
1243 	} else
1244 		err = dump_delta_chain(&obj->deltas, *f, obj->path_packfile,
1245 		    repo);
1246 done:
1247 	if (packfile)
1248 		fclose(packfile);
1249 	if (err && *f)
1250 		fclose(*f);
1251 	return err;
1252 }