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Btrfs-progs: add support for the compression property
[btrfs-progs-unstable/devel.git] / send-utils.c
blob1772d2c5c0f3a0a3053619966f793afff99fd0c9
1 /*
2 * Copyright (C) 2012 Alexander Block. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <unistd.h>
20 #include <fcntl.h>
21 #include <sys/ioctl.h>
22 #include <uuid/uuid.h>
23
24 #include "ctree.h"
25 #include "send-utils.h"
26 #include "ioctl.h"
27 #include "btrfs-list.h"
28
29 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
30 u64 subvol_id);
31
32 static int btrfs_get_root_id_by_sub_path(int mnt_fd, const char *sub_path,
33 u64 *root_id)
34 {
35 int ret;
36 int subvol_fd;
37
38 subvol_fd = openat(mnt_fd, sub_path, O_RDONLY);
39 if (subvol_fd < 0) {
40 ret = -errno;
41 fprintf(stderr, "ERROR: open %s failed. %s\n", sub_path,
42 strerror(-ret));
43 return ret;
44 }
45
46 ret = btrfs_list_get_path_rootid(subvol_fd, root_id);
47 close(subvol_fd);
48 return ret;
49 }
50
51 static int btrfs_read_root_item_raw(int mnt_fd, u64 root_id, size_t buf_len,
52 u32 *read_len, void *buf)
53 {
54 int ret;
55 struct btrfs_ioctl_search_args args;
56 struct btrfs_ioctl_search_key *sk = &args.key;
57 struct btrfs_ioctl_search_header *sh;
58 unsigned long off = 0;
59 int found = 0;
60 int i;
61
62 *read_len = 0;
63 memset(&args, 0, sizeof(args));
64
65 sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
66
67 /*
68 * there may be more than one ROOT_ITEM key if there are
69 * snapshots pending deletion, we have to loop through
70 * them.
71 */
72 sk->min_objectid = root_id;
73 sk->max_objectid = root_id;
74 sk->max_type = BTRFS_ROOT_ITEM_KEY;
75 sk->min_type = BTRFS_ROOT_ITEM_KEY;
76 sk->max_offset = (u64)-1;
77 sk->max_transid = (u64)-1;
78 sk->nr_items = 4096;
79
80 while (1) {
81 ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
82 if (ret < 0) {
83 fprintf(stderr,
84 "ERROR: can't perform the search - %s\n",
85 strerror(errno));
86 return 0;
87 }
88 /* the ioctl returns the number of item it found in nr_items */
89 if (sk->nr_items == 0)
90 break;
91
92 off = 0;
93 for (i = 0; i < sk->nr_items; i++) {
94 struct btrfs_root_item *item;
95 sh = (struct btrfs_ioctl_search_header *)(args.buf +
96 off);
97
98 off += sizeof(*sh);
99 item = (struct btrfs_root_item *)(args.buf + off);
100 off += sh->len;
101
102 sk->min_objectid = sh->objectid;
103 sk->min_type = sh->type;
104 sk->min_offset = sh->offset;
105
106 if (sh->objectid > root_id)
107 break;
108
109 if (sh->objectid == root_id &&
110 sh->type == BTRFS_ROOT_ITEM_KEY) {
111 if (sh->len > buf_len) {
112 /* btrfs-progs is too old for kernel */
113 fprintf(stderr,
114 "ERROR: buf for read_root_item_raw() is too small, get newer btrfs tools!\n");
115 return -EOVERFLOW;
116 }
117 memcpy(buf, item, sh->len);
118 *read_len = sh->len;
119 found = 1;
120 }
121 }
122 if (sk->min_offset < (u64)-1)
123 sk->min_offset++;
124 else
125 break;
126
127 if (sk->min_type != BTRFS_ROOT_ITEM_KEY ||
128 sk->min_objectid != root_id)
129 break;
130 }
131
132 return found ? 0 : -ENOENT;
133 }
134
135 /*
136 * Read a root item from the tree. In case we detect a root item smaller then
137 * sizeof(root_item), we know it's an old version of the root structure and
138 * initialize all new fields to zero. The same happens if we detect mismatching
139 * generation numbers as then we know the root was once mounted with an older
140 * kernel that was not aware of the root item structure change.
141 */
142 static int btrfs_read_root_item(int mnt_fd, u64 root_id,
143 struct btrfs_root_item *item)
144 {
145 int ret;
146 u32 read_len;
147
148 ret = btrfs_read_root_item_raw(mnt_fd, root_id, sizeof(*item),
149 &read_len, item);
150 if (ret)
151 return ret;
152
153 if (read_len < sizeof(*item) ||
154 btrfs_root_generation(item) != btrfs_root_generation_v2(item))
155 memset(&item->generation_v2, 0,
156 sizeof(*item) - offsetof(struct btrfs_root_item,
157 generation_v2));
158
159 return 0;
160 }
161
162 static struct rb_node *tree_insert(struct rb_root *root,
163 struct subvol_info *si,
164 enum subvol_search_type type)
165 {
166 struct rb_node **p = &root->rb_node;
167 struct rb_node *parent = NULL;
168 struct subvol_info *entry;
169 __s64 comp;
170
171 while (*p) {
172 parent = *p;
173 if (type == subvol_search_by_received_uuid) {
174 entry = rb_entry(parent, struct subvol_info,
175 rb_received_node);
176
177 comp = memcmp(entry->received_uuid, si->received_uuid,
178 BTRFS_UUID_SIZE);
179 if (!comp) {
180 if (entry->stransid < si->stransid)
181 comp = -1;
182 else if (entry->stransid > si->stransid)
183 comp = 1;
184 else
185 comp = 0;
186 }
187 } else if (type == subvol_search_by_uuid) {
188 entry = rb_entry(parent, struct subvol_info,
189 rb_local_node);
190 comp = memcmp(entry->uuid, si->uuid, BTRFS_UUID_SIZE);
191 } else if (type == subvol_search_by_root_id) {
192 entry = rb_entry(parent, struct subvol_info,
193 rb_root_id_node);
194 comp = entry->root_id - si->root_id;
195 } else if (type == subvol_search_by_path) {
196 entry = rb_entry(parent, struct subvol_info,
197 rb_path_node);
198 comp = strcmp(entry->path, si->path);
199 } else {
200 BUG();
201 }
202
203 if (comp < 0)
204 p = &(*p)->rb_left;
205 else if (comp > 0)
206 p = &(*p)->rb_right;
207 else
208 return parent;
209 }
210
211 if (type == subvol_search_by_received_uuid) {
212 rb_link_node(&si->rb_received_node, parent, p);
213 rb_insert_color(&si->rb_received_node, root);
214 } else if (type == subvol_search_by_uuid) {
215 rb_link_node(&si->rb_local_node, parent, p);
216 rb_insert_color(&si->rb_local_node, root);
217 } else if (type == subvol_search_by_root_id) {
218 rb_link_node(&si->rb_root_id_node, parent, p);
219 rb_insert_color(&si->rb_root_id_node, root);
220 } else if (type == subvol_search_by_path) {
221 rb_link_node(&si->rb_path_node, parent, p);
222 rb_insert_color(&si->rb_path_node, root);
223 }
224 return NULL;
225 }
226
227 int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id)
228 {
229 if (path_len < 1)
230 return -EOVERFLOW;
231 path[0] = '\0';
232 path_len--;
233 path[path_len] = '\0';
234 return btrfs_subvolid_resolve_sub(fd, path, &path_len, subvol_id);
235 }
236
237 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
238 u64 subvol_id)
239 {
240 int ret;
241 struct btrfs_ioctl_search_args search_arg;
242 struct btrfs_ioctl_ino_lookup_args ino_lookup_arg;
243 struct btrfs_ioctl_search_header *search_header;
244 struct btrfs_root_ref *backref_item;
245
246 if (subvol_id == BTRFS_FS_TREE_OBJECTID) {
247 if (*path_len < 1)
248 return -EOVERFLOW;
249 *path = '\0';
250 (*path_len)--;
251 return 0;
252 }
253
254 memset(&search_arg, 0, sizeof(search_arg));
255 search_arg.key.tree_id = BTRFS_ROOT_TREE_OBJECTID;
256 search_arg.key.min_objectid = subvol_id;
257 search_arg.key.max_objectid = subvol_id;
258 search_arg.key.min_type = BTRFS_ROOT_BACKREF_KEY;
259 search_arg.key.max_type = BTRFS_ROOT_BACKREF_KEY;
260 search_arg.key.max_offset = (u64)-1;
261 search_arg.key.max_transid = (u64)-1;
262 search_arg.key.nr_items = 1;
263 ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
264 if (ret) {
265 fprintf(stderr,
266 "ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %s\n",
267 (unsigned long long)subvol_id, ret, strerror(errno));
268 return ret;
269 }
270
271 if (search_arg.key.nr_items < 1) {
272 fprintf(stderr,
273 "failed to lookup subvol_id %llu!\n",
274 (unsigned long long)subvol_id);
275 return -ENOENT;
276 }
277 search_header = (struct btrfs_ioctl_search_header *)search_arg.buf;
278 backref_item = (struct btrfs_root_ref *)(search_header + 1);
279 if (search_header->offset != BTRFS_FS_TREE_OBJECTID) {
280 int sub_ret;
281
282 sub_ret = btrfs_subvolid_resolve_sub(fd, path, path_len,
283 search_header->offset);
284 if (sub_ret)
285 return sub_ret;
286 if (*path_len < 1)
287 return -EOVERFLOW;
288 strcat(path, "/");
289 (*path_len)--;
290 }
291
292 if (btrfs_stack_root_ref_dirid(backref_item) !=
293 BTRFS_FIRST_FREE_OBJECTID) {
294 int len;
295
296 memset(&ino_lookup_arg, 0, sizeof(ino_lookup_arg));
297 ino_lookup_arg.treeid = search_header->offset;
298 ino_lookup_arg.objectid =
299 btrfs_stack_root_ref_dirid(backref_item);
300 ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_lookup_arg);
301 if (ret) {
302 fprintf(stderr,
303 "ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %s\n",
304 ret, strerror(errno));
305 return ret;
306 }
307
308 len = strlen(ino_lookup_arg.name);
309 if (*path_len < len)
310 return -EOVERFLOW;
311 strcat(path, ino_lookup_arg.name);
312 (*path_len) -= len;
313 }
314
315 if (*path_len < btrfs_stack_root_ref_name_len(backref_item))
316 return -EOVERFLOW;
317 strncat(path, (char *)(backref_item + 1),
318 btrfs_stack_root_ref_name_len(backref_item));
319 (*path_len) -= btrfs_stack_root_ref_name_len(backref_item);
320 return 0;
321 }
322
323 static int count_bytes(void *buf, int len, char b)
324 {
325 int cnt = 0;
326 int i;
327
328 for (i = 0; i < len; i++) {
329 if (((char *)buf)[i] == b)
330 cnt++;
331 }
332 return cnt;
333 }
334
335 void subvol_uuid_search_add(struct subvol_uuid_search *s,
336 struct subvol_info *si)
337 {
338 int cnt;
339
340 tree_insert(&s->root_id_subvols, si, subvol_search_by_root_id);
341 tree_insert(&s->path_subvols, si, subvol_search_by_path);
342
343 cnt = count_bytes(si->uuid, BTRFS_UUID_SIZE, 0);
344 if (cnt != BTRFS_UUID_SIZE)
345 tree_insert(&s->local_subvols, si, subvol_search_by_uuid);
346 cnt = count_bytes(si->received_uuid, BTRFS_UUID_SIZE, 0);
347 if (cnt != BTRFS_UUID_SIZE)
348 tree_insert(&s->received_subvols, si,
349 subvol_search_by_received_uuid);
350 }
351
352 static struct subvol_info *tree_search(struct rb_root *root,
353 u64 root_id, const u8 *uuid,
354 u64 stransid, const char *path,
355 enum subvol_search_type type)
356 {
357 struct rb_node *n = root->rb_node;
358 struct subvol_info *entry;
359 __s64 comp;
360
361 while (n) {
362 if (type == subvol_search_by_received_uuid) {
363 entry = rb_entry(n, struct subvol_info,
364 rb_received_node);
365 comp = memcmp(entry->received_uuid, uuid,
366 BTRFS_UUID_SIZE);
367 if (!comp) {
368 if (entry->stransid < stransid)
369 comp = -1;
370 else if (entry->stransid > stransid)
371 comp = 1;
372 else
373 comp = 0;
374 }
375 } else if (type == subvol_search_by_uuid) {
376 entry = rb_entry(n, struct subvol_info, rb_local_node);
377 comp = memcmp(entry->uuid, uuid, BTRFS_UUID_SIZE);
378 } else if (type == subvol_search_by_root_id) {
379 entry = rb_entry(n, struct subvol_info,
380 rb_root_id_node);
381 comp = entry->root_id - root_id;
382 } else if (type == subvol_search_by_path) {
383 entry = rb_entry(n, struct subvol_info, rb_path_node);
384 comp = strcmp(entry->path, path);
385 } else {
386 BUG();
387 }
388 if (comp < 0)
389 n = n->rb_left;
390 else if (comp > 0)
391 n = n->rb_right;
392 else
393 return entry;
394 }
395 return NULL;
396 }
397
398 /*
399 * this function will be only called if kernel dosen't support uuid tree.
400 */
401 static struct subvol_info *subvol_uuid_search_old(struct subvol_uuid_search *s,
402 u64 root_id, const u8 *uuid, u64 transid,
403 const char *path,
404 enum subvol_search_type type)
405 {
406 struct rb_root *root;
407 if (type == subvol_search_by_received_uuid)
408 root = &s->received_subvols;
409 else if (type == subvol_search_by_uuid)
410 root = &s->local_subvols;
411 else if (type == subvol_search_by_root_id)
412 root = &s->root_id_subvols;
413 else if (type == subvol_search_by_path)
414 root = &s->path_subvols;
415 else
416 return NULL;
417 return tree_search(root, root_id, uuid, transid, path, type);
418 }
419
420 struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
421 u64 root_id, const u8 *uuid, u64 transid,
422 const char *path,
423 enum subvol_search_type type)
424 {
425 int ret = 0;
426 struct btrfs_root_item root_item;
427 struct subvol_info *info = NULL;
428
429 if (!s->uuid_tree_existed)
430 return subvol_uuid_search_old(s, root_id, uuid, transid,
431 path, type);
432 switch (type) {
433 case subvol_search_by_received_uuid:
434 ret = btrfs_lookup_uuid_received_subvol_item(s->mnt_fd, uuid,
435 &root_id);
436 break;
437 case subvol_search_by_uuid:
438 ret = btrfs_lookup_uuid_subvol_item(s->mnt_fd, uuid, &root_id);
439 break;
440 case subvol_search_by_root_id:
441 break;
442 case subvol_search_by_path:
443 ret = btrfs_get_root_id_by_sub_path(s->mnt_fd, path, &root_id);
444 break;
445 default:
446 ret = -EINVAL;
447 break;
448 }
449
450 if (ret)
451 goto out;
452
453 ret = btrfs_read_root_item(s->mnt_fd, root_id, &root_item);
454 if (ret)
455 goto out;
456
457 info = calloc(1, sizeof(*info));
458 info->root_id = root_id;
459 memcpy(info->uuid, root_item.uuid, BTRFS_UUID_SIZE);
460 memcpy(info->received_uuid, root_item.received_uuid, BTRFS_UUID_SIZE);
461 memcpy(info->parent_uuid, root_item.parent_uuid, BTRFS_UUID_SIZE);
462 info->ctransid = btrfs_root_ctransid(&root_item);
463 info->otransid = btrfs_root_otransid(&root_item);
464 info->stransid = btrfs_root_stransid(&root_item);
465 info->rtransid = btrfs_root_rtransid(&root_item);
466 if (type == subvol_search_by_path) {
467 info->path = strdup(path);
468 } else {
469 info->path = malloc(BTRFS_PATH_NAME_MAX);
470 ret = btrfs_subvolid_resolve(s->mnt_fd, info->path,
471 BTRFS_PATH_NAME_MAX, root_id);
472 }
473
474 out:
475 if (ret && info) {
476 free(info->path);
477 free(info);
478 info = NULL;
479 }
480
481 return info;
482 }
483
484 static int is_uuid_tree_supported(int fd)
485 {
486 int ret;
487 struct btrfs_ioctl_search_args args;
488 struct btrfs_ioctl_search_key *sk = &args.key;
489
490 memset(&args, 0, sizeof(args));
491
492 sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
493
494 sk->min_objectid = BTRFS_UUID_TREE_OBJECTID;
495 sk->max_objectid = BTRFS_UUID_TREE_OBJECTID;
496 sk->max_type = BTRFS_ROOT_ITEM_KEY;
497 sk->min_type = BTRFS_ROOT_ITEM_KEY;
498 sk->max_offset = (u64)-1;
499 sk->max_transid = (u64)-1;
500 sk->nr_items = 1;
501
502 ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
503 if (ret < 0)
504 return ret;
505
506 /* the ioctl returns the number of item it found in nr_items */
507 if (sk->nr_items == 0)
508 return 0;
509
510 return 1;
511 }
512
513 /*
514 * this function is mainly used to read all root items
515 * it will be only used when we use older kernel which uuid
516 * tree is not supported yet
517 */
518 int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
519 {
520 int ret;
521 struct btrfs_ioctl_search_args args;
522 struct btrfs_ioctl_search_key *sk = &args.key;
523 struct btrfs_ioctl_search_header *sh;
524 struct btrfs_root_item *root_item_ptr;
525 struct btrfs_root_item root_item;
526 struct subvol_info *si = NULL;
527 int root_item_valid = 0;
528 unsigned long off = 0;
529 int i;
530 int e;
531 char *path;
532
533 s->mnt_fd = mnt_fd;
534
535 s->root_id_subvols = RB_ROOT;
536 s->local_subvols = RB_ROOT;
537 s->received_subvols = RB_ROOT;
538 s->path_subvols = RB_ROOT;
539
540 ret = is_uuid_tree_supported(mnt_fd);
541 if (ret < 0) {
542 fprintf(stderr,
543 "ERROR: check if we support uuid tree fails- %s\n",
544 strerror(errno));
545 return ret;
546 } else if (ret) {
547 /* uuid tree is supported */
548 s->uuid_tree_existed = 1;
549 return 0;
550 }
551 memset(&args, 0, sizeof(args));
552
553 sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
554
555 sk->max_objectid = (u64)-1;
556 sk->max_offset = (u64)-1;
557 sk->max_transid = (u64)-1;
558 sk->min_type = BTRFS_ROOT_ITEM_KEY;
559 sk->max_type = BTRFS_ROOT_BACKREF_KEY;
560 sk->nr_items = 4096;
561
562 while (1) {
563 ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
564 e = errno;
565 if (ret < 0) {
566 fprintf(stderr, "ERROR: can't perform the search- %s\n",
567 strerror(e));
568 return ret;
569 }
570 if (sk->nr_items == 0)
571 break;
572
573 off = 0;
574
575 for (i = 0; i < sk->nr_items; i++) {
576 sh = (struct btrfs_ioctl_search_header *)(args.buf +
577 off);
578 off += sizeof(*sh);
579
580 if ((sh->objectid != 5 &&
581 sh->objectid < BTRFS_FIRST_FREE_OBJECTID) ||
582 sh->objectid > BTRFS_LAST_FREE_OBJECTID)
583 goto skip;
584
585 if (sh->type == BTRFS_ROOT_ITEM_KEY) {
586 /* older kernels don't have uuids+times */
587 if (sh->len < sizeof(root_item)) {
588 root_item_valid = 0;
589 goto skip;
590 }
591 root_item_ptr = (struct btrfs_root_item *)
592 (args.buf + off);
593 memcpy(&root_item, root_item_ptr,
594 sizeof(root_item));
595 root_item_valid = 1;
596 } else if (sh->type == BTRFS_ROOT_BACKREF_KEY ||
597 root_item_valid) {
598 if (!root_item_valid)
599 goto skip;
600
601 path = btrfs_list_path_for_root(mnt_fd,
602 sh->objectid);
603 if (!path)
604 path = strdup("");
605 if (IS_ERR(path)) {
606 ret = PTR_ERR(path);
607 fprintf(stderr, "ERROR: unable to "
608 "resolve path "
609 "for root %llu\n",
610 sh->objectid);
611 goto out;
612 }
613
614 si = calloc(1, sizeof(*si));
615 si->root_id = sh->objectid;
616 memcpy(si->uuid, root_item.uuid,
617 BTRFS_UUID_SIZE);
618 memcpy(si->parent_uuid, root_item.parent_uuid,
619 BTRFS_UUID_SIZE);
620 memcpy(si->received_uuid,
621 root_item.received_uuid,
622 BTRFS_UUID_SIZE);
623 si->ctransid = btrfs_root_ctransid(&root_item);
624 si->otransid = btrfs_root_otransid(&root_item);
625 si->stransid = btrfs_root_stransid(&root_item);
626 si->rtransid = btrfs_root_rtransid(&root_item);
627 si->path = path;
628 subvol_uuid_search_add(s, si);
629 root_item_valid = 0;
630 } else {
631 goto skip;
632 }
633
634 skip:
635 off += sh->len;
636
637 /*
638 * record the mins in sk so we can make sure the
639 * next search doesn't repeat this root
640 */
641 sk->min_objectid = sh->objectid;
642 sk->min_offset = sh->offset;
643 sk->min_type = sh->type;
644 }
645 sk->nr_items = 4096;
646 if (sk->min_offset < (u64)-1)
647 sk->min_offset++;
648 else if (sk->min_objectid < (u64)-1) {
649 sk->min_objectid++;
650 sk->min_offset = 0;
651 sk->min_type = 0;
652 } else
653 break;
654 }
655
656 out:
657 return ret;
658 }
659
660 void subvol_uuid_search_finit(struct subvol_uuid_search *s)
661 {
662 struct rb_root *root = &s->root_id_subvols;
663 struct rb_node *node;
664
665 if (!s->uuid_tree_existed)
666 return;
667
668 while ((node = rb_first(root))) {
669 struct subvol_info *entry =
670 rb_entry(node, struct subvol_info, rb_root_id_node);
671
672 free(entry->path);
673 rb_erase(node, root);
674 free(entry);
675 }
676
677 s->root_id_subvols = RB_ROOT;
678 s->local_subvols = RB_ROOT;
679 s->received_subvols = RB_ROOT;
680 s->path_subvols = RB_ROOT;
681 }
682
683 char *path_cat(const char *p1, const char *p2)
684 {
685 int p1_len = strlen(p1);
686 int p2_len = strlen(p2);
687 char *new = malloc(p1_len + p2_len + 2);
688
689 if (p1_len && p1[p1_len - 1] == '/')
690 p1_len--;
691 if (p2_len && p2[p2_len - 1] == '/')
692 p2_len--;
693 sprintf(new, "%.*s/%.*s", p1_len, p1, p2_len, p2);
694 return new;
695 }
696
697 char *path_cat3(const char *p1, const char *p2, const char *p3)
698 {
699 int p1_len = strlen(p1);
700 int p2_len = strlen(p2);
701 int p3_len = strlen(p3);
702 char *new = malloc(p1_len + p2_len + p3_len + 3);
703
704 if (p1_len && p1[p1_len - 1] == '/')
705 p1_len--;
706 if (p2_len && p2[p2_len - 1] == '/')
707 p2_len--;
708 if (p3_len && p3[p3_len - 1] == '/')
709 p3_len--;
710 sprintf(new, "%.*s/%.*s/%.*s", p1_len, p1, p2_len, p2, p3_len, p3);
711 return new;
712 }
(deprecated) Btrfs progs developments and patch integration