source: mainline/uspace/srv/vfs/vfs_ops.c@ c31d773

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since c31d773 was c31d773, checked in by Jakub Jermar <jakub@…>, 17 years ago

Grab the nodes_futex when manipulating node link counts in rename() and
_unlink().

Fix VFS futex definitions and declarations by replacing atomic_t by futex_t.
  • Property mode set to 100644
File size: 21.1 KB
Line 
1/*
2 * Copyright (c) 2008 Jakub Jermar
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup fs
30 * @{
31 */
32
33/**
34 * @file vfs_ops.c
35 * @brief Operations that VFS offers to its clients.
36 */
37
38#include "vfs.h"
39#include <ipc/ipc.h>
40#include <async.h>
41#include <errno.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <bool.h>
46#include <futex.h>
47#include <rwlock.h>
48#include <libadt/list.h>
49#include <unistd.h>
50#include <ctype.h>
51#include <fcntl.h>
52#include <assert.h>
53#include <vfs/canonify.h>
54
55/* Forward declarations of static functions. */
56static int vfs_truncate_internal(int, int, unsigned long, size_t);
57
58/**
59 * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
60 * concurrent VFS operation which modifies the file system namespace.
61 */
62RWLOCK_INITIALIZE(namespace_rwlock);
63
64futex_t rootfs_futex = FUTEX_INITIALIZER;
65vfs_triplet_t rootfs = {
66 .fs_handle = 0,
67 .dev_handle = 0,
68 .index = 0,
69};
70
71static int lookup_root(int fs_handle, int dev_handle, vfs_lookup_res_t *result)
72{
73 vfs_pair_t altroot = {
74 .fs_handle = fs_handle,
75 .dev_handle = dev_handle,
76 };
77
78 return vfs_lookup_internal("/", L_DIRECTORY, result, &altroot);
79}
80
81void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
82{
83 int dev_handle;
84 vfs_node_t *mp_node = NULL;
85
86 /*
87 * We expect the library to do the device-name to device-handle
88 * translation for us, thus the device handle will arrive as ARG1
89 * in the request.
90 */
91 dev_handle = IPC_GET_ARG1(*request);
92
93 /*
94 * For now, don't make use of ARG2 and ARG3, but they can be used to
95 * carry mount options in the future.
96 */
97
98 ipc_callid_t callid;
99 size_t size;
100
101 /*
102 * Now, we expect the client to send us data with the name of the file
103 * system.
104 */
105 if (!ipc_data_write_receive(&callid, &size)) {
106 ipc_answer_0(callid, EINVAL);
107 ipc_answer_0(rid, EINVAL);
108 return;
109 }
110
111 /*
112 * Don't receive more than is necessary for storing a full file system
113 * name.
114 */
115 if (size < 1 || size > FS_NAME_MAXLEN) {
116 ipc_answer_0(callid, EINVAL);
117 ipc_answer_0(rid, EINVAL);
118 return;
119 }
120
121 /* Deliver the file system name. */
122 char fs_name[FS_NAME_MAXLEN + 1];
123 (void) ipc_data_write_finalize(callid, fs_name, size);
124 fs_name[size] = '\0';
125
126 /*
127 * Check if we know a file system with the same name as is in fs_name.
128 * This will also give us its file system handle.
129 */
130 int fs_handle = fs_name_to_handle(fs_name, true);
131 if (!fs_handle) {
132 ipc_answer_0(rid, ENOENT);
133 return;
134 }
135
136 /* Now, we want the client to send us the mount point. */
137 if (!ipc_data_write_receive(&callid, &size)) {
138 ipc_answer_0(callid, EINVAL);
139 ipc_answer_0(rid, EINVAL);
140 return;
141 }
142
143 /* Check whether size is reasonable wrt. the mount point. */
144 if (size < 1 || size > MAX_PATH_LEN) {
145 ipc_answer_0(callid, EINVAL);
146 ipc_answer_0(rid, EINVAL);
147 return;
148 }
149 /* Allocate buffer for the mount point data being received. */
150 uint8_t *buf;
151 buf = malloc(size + 1);
152 if (!buf) {
153 ipc_answer_0(callid, ENOMEM);
154 ipc_answer_0(rid, ENOMEM);
155 return;
156 }
157
158 /* Deliver the mount point. */
159 (void) ipc_data_write_finalize(callid, buf, size);
160 buf[size] = '\0';
161
162 /*
163 * Lookup the root node of the filesystem being mounted.
164 * In this case, we don't need to take the namespace_futex as the root
165 * node cannot be removed. However, we do take a reference to it so
166 * that we can track how many times it has been mounted.
167 */
168 int rc;
169 vfs_lookup_res_t mr_res;
170 rc = lookup_root(fs_handle, dev_handle, &mr_res);
171 if (rc != EOK) {
172 free(buf);
173 ipc_answer_0(rid, rc);
174 return;
175 }
176 vfs_node_t *mr_node = vfs_node_get(&mr_res);
177 if (!mr_node) {
178 free(buf);
179 ipc_answer_0(rid, ENOMEM);
180 return;
181 }
182
183 /* Finally, we need to resolve the path to the mountpoint. */
184 vfs_lookup_res_t mp_res;
185 futex_down(&rootfs_futex);
186 if (rootfs.fs_handle) {
187 /* We already have the root FS. */
188 rwlock_write_lock(&namespace_rwlock);
189 rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
190 if (rc != EOK) {
191 /* The lookup failed for some reason. */
192 rwlock_write_unlock(&namespace_rwlock);
193 futex_up(&rootfs_futex);
194 vfs_node_put(mr_node); /* failed -> drop reference */
195 free(buf);
196 ipc_answer_0(rid, rc);
197 return;
198 }
199 mp_node = vfs_node_get(&mp_res);
200 if (!mp_node) {
201 rwlock_write_unlock(&namespace_rwlock);
202 futex_up(&rootfs_futex);
203 vfs_node_put(mr_node); /* failed -> drop reference */
204 free(buf);
205 ipc_answer_0(rid, ENOMEM);
206 return;
207 }
208 /*
209 * Now we hold a reference to mp_node.
210 * It will be dropped upon the corresponding VFS_UNMOUNT.
211 * This prevents the mount point from being deleted.
212 */
213 rwlock_write_unlock(&namespace_rwlock);
214 } else {
215 /* We still don't have the root file system mounted. */
216 if ((size == 1) && (buf[0] == '/')) {
217 /* For this simple, but important case, we are done. */
218 rootfs = mr_res.triplet;
219 futex_up(&rootfs_futex);
220 free(buf);
221 ipc_answer_0(rid, EOK);
222 return;
223 } else {
224 /*
225 * We can't resolve this without the root filesystem
226 * being mounted first.
227 */
228 futex_up(&rootfs_futex);
229 free(buf);
230 vfs_node_put(mr_node); /* failed -> drop reference */
231 ipc_answer_0(rid, ENOENT);
232 return;
233 }
234 }
235 futex_up(&rootfs_futex);
236
237 free(buf); /* The buffer is not needed anymore. */
238
239 /*
240 * At this point, we have all necessary pieces: file system and device
241 * handles, and we know the mount point VFS node and also the root node
242 * of the file system being mounted.
243 */
244
245 int phone = vfs_grab_phone(mp_res.triplet.fs_handle);
246 /* Later we can use ARG3 to pass mode/flags. */
247 aid_t req1 = async_send_3(phone, VFS_MOUNT,
248 (ipcarg_t) mp_res.triplet.dev_handle,
249 (ipcarg_t) mp_res.triplet.index, 0, NULL);
250 /* The second call uses the same method. */
251 aid_t req2 = async_send_3(phone, VFS_MOUNT,
252 (ipcarg_t) mr_res.triplet.fs_handle,
253 (ipcarg_t) mr_res.triplet.dev_handle,
254 (ipcarg_t) mr_res.triplet.index, NULL);
255 vfs_release_phone(phone);
256
257 ipcarg_t rc1;
258 ipcarg_t rc2;
259 async_wait_for(req1, &rc1);
260 async_wait_for(req2, &rc2);
261
262 if ((rc1 != EOK) || (rc2 != EOK)) {
263 /* Mount failed, drop references to mr_node and mp_node. */
264 vfs_node_put(mr_node);
265 if (mp_node)
266 vfs_node_put(mp_node);
267 }
268
269 if (rc2 == EOK)
270 ipc_answer_0(rid, rc1);
271 else if (rc1 == EOK)
272 ipc_answer_0(rid, rc2);
273 else
274 ipc_answer_0(rid, rc1);
275}
276
277void vfs_open(ipc_callid_t rid, ipc_call_t *request)
278{
279 if (!vfs_files_init()) {
280 ipc_answer_0(rid, ENOMEM);
281 return;
282 }
283
284 /*
285 * The POSIX interface is open(path, oflag, mode).
286 * We can receive oflags and mode along with the VFS_OPEN call; the path
287 * will need to arrive in another call.
288 *
289 * We also receive one private, non-POSIX set of flags called lflag
290 * used to pass information to vfs_lookup_internal().
291 */
292 int lflag = IPC_GET_ARG1(*request);
293 int oflag = IPC_GET_ARG2(*request);
294 int mode = IPC_GET_ARG3(*request);
295 size_t len;
296
297 if (oflag & O_CREAT)
298 lflag |= L_CREATE;
299 if (oflag & O_EXCL)
300 lflag |= L_EXCLUSIVE;
301
302 ipc_callid_t callid;
303
304 if (!ipc_data_write_receive(&callid, &len)) {
305 ipc_answer_0(callid, EINVAL);
306 ipc_answer_0(rid, EINVAL);
307 return;
308 }
309 char *path = malloc(len + 1);
310 if (!path) {
311 ipc_answer_0(callid, ENOMEM);
312 ipc_answer_0(rid, ENOMEM);
313 return;
314 }
315 int rc;
316 if ((rc = ipc_data_write_finalize(callid, path, len))) {
317 ipc_answer_0(rid, rc);
318 free(path);
319 return;
320 }
321 path[len] = '\0';
322
323 /*
324 * Avoid the race condition in which the file can be deleted before we
325 * find/create-and-lock the VFS node corresponding to the looked-up
326 * triplet.
327 */
328 if (lflag & L_CREATE)
329 rwlock_write_lock(&namespace_rwlock);
330 else
331 rwlock_read_lock(&namespace_rwlock);
332
333 /* The path is now populated and we can call vfs_lookup_internal(). */
334 vfs_lookup_res_t lr;
335 rc = vfs_lookup_internal(path, lflag, &lr, NULL);
336 if (rc) {
337 if (lflag & L_CREATE)
338 rwlock_write_unlock(&namespace_rwlock);
339 else
340 rwlock_read_unlock(&namespace_rwlock);
341 ipc_answer_0(rid, rc);
342 free(path);
343 return;
344 }
345
346 /* Path is no longer needed. */
347 free(path);
348
349 vfs_node_t *node = vfs_node_get(&lr);
350 if (lflag & L_CREATE)
351 rwlock_write_unlock(&namespace_rwlock);
352 else
353 rwlock_read_unlock(&namespace_rwlock);
354
355 /* Truncate the file if requested and if necessary. */
356 if (oflag & O_TRUNC) {
357 rwlock_write_lock(&node->contents_rwlock);
358 if (node->size) {
359 rc = vfs_truncate_internal(node->fs_handle,
360 node->dev_handle, node->index, 0);
361 if (rc) {
362 rwlock_write_unlock(&node->contents_rwlock);
363 vfs_node_put(node);
364 ipc_answer_0(rid, rc);
365 return;
366 }
367 node->size = 0;
368 }
369 rwlock_write_unlock(&node->contents_rwlock);
370 }
371
372 /*
373 * Get ourselves a file descriptor and the corresponding vfs_file_t
374 * structure.
375 */
376 int fd = vfs_fd_alloc();
377 if (fd < 0) {
378 vfs_node_put(node);
379 ipc_answer_0(rid, fd);
380 return;
381 }
382 vfs_file_t *file = vfs_file_get(fd);
383 file->node = node;
384 if (oflag & O_APPEND)
385 file->append = true;
386
387 /*
388 * The following increase in reference count is for the fact that the
389 * file is being opened and that a file structure is pointing to it.
390 * It is necessary so that the file will not disappear when
391 * vfs_node_put() is called. The reference will be dropped by the
392 * respective VFS_CLOSE.
393 */
394 vfs_node_addref(node);
395 vfs_node_put(node);
396
397 /* Success! Return the new file descriptor to the client. */
398 ipc_answer_1(rid, EOK, fd);
399}
400
401void vfs_close(ipc_callid_t rid, ipc_call_t *request)
402{
403 int fd = IPC_GET_ARG1(*request);
404 if (fd >= MAX_OPEN_FILES) {
405 ipc_answer_0(rid, EBADF);
406 return;
407 }
408 vfs_fd_free(fd);
409 ipc_answer_0(rid, EOK);
410}
411
412static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
413{
414
415 /*
416 * The following code strongly depends on the fact that the files data
417 * structure can be only accessed by a single fibril and all file
418 * operations are serialized (i.e. the reads and writes cannot
419 * interleave and a file cannot be closed while it is being read).
420 *
421 * Additional synchronization needs to be added once the table of
422 * open files supports parallel access!
423 */
424
425 int fd = IPC_GET_ARG1(*request);
426
427 /* Lookup the file structure corresponding to the file descriptor. */
428 vfs_file_t *file = vfs_file_get(fd);
429 if (!file) {
430 ipc_answer_0(rid, ENOENT);
431 return;
432 }
433
434 /*
435 * Now we need to receive a call with client's
436 * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
437 */
438 ipc_callid_t callid;
439 int res;
440 if (read)
441 res = ipc_data_read_receive(&callid, NULL);
442 else
443 res = ipc_data_write_receive(&callid, NULL);
444 if (!res) {
445 ipc_answer_0(callid, EINVAL);
446 ipc_answer_0(rid, EINVAL);
447 return;
448 }
449
450 /*
451 * Lock the open file structure so that no other thread can manipulate
452 * the same open file at a time.
453 */
454 futex_down(&file->lock);
455
456 /*
457 * Lock the file's node so that no other client can read/write to it at
458 * the same time.
459 */
460 if (read)
461 rwlock_read_lock(&file->node->contents_rwlock);
462 else
463 rwlock_write_lock(&file->node->contents_rwlock);
464
465 int fs_phone = vfs_grab_phone(file->node->fs_handle);
466
467 /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
468 aid_t msg;
469 ipc_call_t answer;
470 if (!read && file->append)
471 file->pos = file->node->size;
472 msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
473 file->node->dev_handle, file->node->index, file->pos, &answer);
474
475 /*
476 * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
477 * destination FS server. The call will be routed as if sent by
478 * ourselves. Note that call arguments are immutable in this case so we
479 * don't have to bother.
480 */
481 ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
482
483 vfs_release_phone(fs_phone);
484
485 /* Wait for reply from the FS server. */
486 ipcarg_t rc;
487 async_wait_for(msg, &rc);
488 size_t bytes = IPC_GET_ARG1(answer);
489
490 /* Unlock the VFS node. */
491 if (read)
492 rwlock_read_unlock(&file->node->contents_rwlock);
493 else {
494 /* Update the cached version of node's size. */
495 if (rc == EOK)
496 file->node->size = IPC_GET_ARG2(answer);
497 rwlock_write_unlock(&file->node->contents_rwlock);
498 }
499
500 /* Update the position pointer and unlock the open file. */
501 if (rc == EOK)
502 file->pos += bytes;
503 futex_up(&file->lock);
504
505 /*
506 * FS server's reply is the final result of the whole operation we
507 * return to the client.
508 */
509 ipc_answer_1(rid, rc, bytes);
510}
511
512void vfs_read(ipc_callid_t rid, ipc_call_t *request)
513{
514 vfs_rdwr(rid, request, true);
515}
516
517void vfs_write(ipc_callid_t rid, ipc_call_t *request)
518{
519 vfs_rdwr(rid, request, false);
520}
521
522void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
523{
524 int fd = (int) IPC_GET_ARG1(*request);
525 off_t off = (off_t) IPC_GET_ARG2(*request);
526 int whence = (int) IPC_GET_ARG3(*request);
527
528
529 /* Lookup the file structure corresponding to the file descriptor. */
530 vfs_file_t *file = vfs_file_get(fd);
531 if (!file) {
532 ipc_answer_0(rid, ENOENT);
533 return;
534 }
535
536 off_t newpos;
537 futex_down(&file->lock);
538 if (whence == SEEK_SET) {
539 file->pos = off;
540 futex_up(&file->lock);
541 ipc_answer_1(rid, EOK, off);
542 return;
543 }
544 if (whence == SEEK_CUR) {
545 if (file->pos + off < file->pos) {
546 futex_up(&file->lock);
547 ipc_answer_0(rid, EOVERFLOW);
548 return;
549 }
550 file->pos += off;
551 newpos = file->pos;
552 futex_up(&file->lock);
553 ipc_answer_1(rid, EOK, newpos);
554 return;
555 }
556 if (whence == SEEK_END) {
557 rwlock_read_lock(&file->node->contents_rwlock);
558 size_t size = file->node->size;
559 rwlock_read_unlock(&file->node->contents_rwlock);
560 if (size + off < size) {
561 futex_up(&file->lock);
562 ipc_answer_0(rid, EOVERFLOW);
563 return;
564 }
565 newpos = size + off;
566 futex_up(&file->lock);
567 ipc_answer_1(rid, EOK, newpos);
568 return;
569 }
570 futex_up(&file->lock);
571 ipc_answer_0(rid, EINVAL);
572}
573
574int vfs_truncate_internal(int fs_handle, int dev_handle, unsigned long index,
575 size_t size)
576{
577 ipcarg_t rc;
578 int fs_phone;
579
580 fs_phone = vfs_grab_phone(fs_handle);
581 rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)dev_handle,
582 (ipcarg_t)index, (ipcarg_t)size);
583 vfs_release_phone(fs_phone);
584 return (int)rc;
585}
586
587void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
588{
589 int fd = IPC_GET_ARG1(*request);
590 size_t size = IPC_GET_ARG2(*request);
591 int rc;
592
593 vfs_file_t *file = vfs_file_get(fd);
594 if (!file) {
595 ipc_answer_0(rid, ENOENT);
596 return;
597 }
598 futex_down(&file->lock);
599
600 rwlock_write_lock(&file->node->contents_rwlock);
601 rc = vfs_truncate_internal(file->node->fs_handle,
602 file->node->dev_handle, file->node->index, size);
603 if (rc == EOK)
604 file->node->size = size;
605 rwlock_write_unlock(&file->node->contents_rwlock);
606
607 futex_up(&file->lock);
608 ipc_answer_0(rid, (ipcarg_t)rc);
609}
610
611void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
612{
613 int mode = IPC_GET_ARG1(*request);
614
615 size_t len;
616 ipc_callid_t callid;
617
618 if (!ipc_data_write_receive(&callid, &len)) {
619 ipc_answer_0(callid, EINVAL);
620 ipc_answer_0(rid, EINVAL);
621 return;
622 }
623 char *path = malloc(len + 1);
624 if (!path) {
625 ipc_answer_0(callid, ENOMEM);
626 ipc_answer_0(rid, ENOMEM);
627 return;
628 }
629 int rc;
630 if ((rc = ipc_data_write_finalize(callid, path, len))) {
631 ipc_answer_0(rid, rc);
632 free(path);
633 return;
634 }
635 path[len] = '\0';
636
637 rwlock_write_lock(&namespace_rwlock);
638 int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
639 rc = vfs_lookup_internal(path, lflag, NULL, NULL);
640 rwlock_write_unlock(&namespace_rwlock);
641 free(path);
642 ipc_answer_0(rid, rc);
643}
644
645void vfs_unlink(ipc_callid_t rid, ipc_call_t *request)
646{
647 int lflag = IPC_GET_ARG1(*request);
648
649 size_t len;
650 ipc_callid_t callid;
651
652 if (!ipc_data_write_receive(&callid, &len)) {
653 ipc_answer_0(callid, EINVAL);
654 ipc_answer_0(rid, EINVAL);
655 return;
656 }
657 char *path = malloc(len + 1);
658 if (!path) {
659 ipc_answer_0(callid, ENOMEM);
660 ipc_answer_0(rid, ENOMEM);
661 return;
662 }
663 int rc;
664 if ((rc = ipc_data_write_finalize(callid, path, len))) {
665 ipc_answer_0(rid, rc);
666 free(path);
667 return;
668 }
669 path[len] = '\0';
670
671 rwlock_write_lock(&namespace_rwlock);
672 lflag &= L_DIRECTORY; /* sanitize lflag */
673 vfs_lookup_res_t lr;
674 rc = vfs_lookup_internal(path, lflag | L_UNLINK, &lr, NULL);
675 free(path);
676 if (rc != EOK) {
677 rwlock_write_unlock(&namespace_rwlock);
678 ipc_answer_0(rid, rc);
679 return;
680 }
681
682 /*
683 * The name has already been unlinked by vfs_lookup_internal().
684 * We have to get and put the VFS node to ensure that it is
685 * VFS_DESTROY'ed after the last reference to it is dropped.
686 */
687 vfs_node_t *node = vfs_node_get(&lr);
688 futex_down(&nodes_futex);
689 node->lnkcnt--;
690 futex_up(&nodes_futex);
691 rwlock_write_unlock(&namespace_rwlock);
692 vfs_node_put(node);
693 ipc_answer_0(rid, EOK);
694}
695
696void vfs_rename(ipc_callid_t rid, ipc_call_t *request)
697{
698 size_t len;
699 ipc_callid_t callid;
700 int rc;
701
702 /* Retrieve the old path. */
703 if (!ipc_data_write_receive(&callid, &len)) {
704 ipc_answer_0(callid, EINVAL);
705 ipc_answer_0(rid, EINVAL);
706 return;
707 }
708 char *old = malloc(len + 1);
709 if (!old) {
710 ipc_answer_0(callid, ENOMEM);
711 ipc_answer_0(rid, ENOMEM);
712 return;
713 }
714 if ((rc = ipc_data_write_finalize(callid, old, len))) {
715 ipc_answer_0(rid, rc);
716 free(old);
717 return;
718 }
719 old[len] = '\0';
720
721 /* Retrieve the new path. */
722 if (!ipc_data_write_receive(&callid, &len)) {
723 ipc_answer_0(callid, EINVAL);
724 ipc_answer_0(rid, EINVAL);
725 free(old);
726 return;
727 }
728 char *new = malloc(len + 1);
729 if (!new) {
730 ipc_answer_0(callid, ENOMEM);
731 ipc_answer_0(rid, ENOMEM);
732 free(old);
733 return;
734 }
735 if ((rc = ipc_data_write_finalize(callid, new, len))) {
736 ipc_answer_0(rid, rc);
737 free(old);
738 free(new);
739 return;
740 }
741 new[len] = '\0';
742
743 char *oldc = canonify(old, &len);
744 char *newc = canonify(new, NULL);
745 if (!oldc || !newc) {
746 ipc_answer_0(rid, EINVAL);
747 free(old);
748 free(new);
749 return;
750 }
751 if (!strncmp(newc, oldc, len)) {
752 /* oldc is a prefix of newc */
753 ipc_answer_0(rid, EINVAL);
754 free(old);
755 free(new);
756 return;
757 }
758
759 vfs_lookup_res_t old_lr;
760 vfs_lookup_res_t new_lr;
761 vfs_lookup_res_t new_par_lr;
762 rwlock_write_lock(&namespace_rwlock);
763 /* Lookup the node belonging to the old file name. */
764 rc = vfs_lookup_internal(oldc, L_NONE, &old_lr, NULL);
765 if (rc != EOK) {
766 rwlock_write_unlock(&namespace_rwlock);
767 ipc_answer_0(rid, rc);
768 free(old);
769 free(new);
770 return;
771 }
772 vfs_node_t *old_node = vfs_node_get(&old_lr);
773 if (!old_node) {
774 rwlock_write_unlock(&namespace_rwlock);
775 ipc_answer_0(rid, ENOMEM);
776 free(old);
777 free(new);
778 return;
779 }
780 /* Lookup parent of the new file name. */
781 rc = vfs_lookup_internal(newc, L_PARENT, &new_par_lr, NULL);
782 if (rc != EOK) {
783 rwlock_write_unlock(&namespace_rwlock);
784 ipc_answer_0(rid, rc);
785 free(old);
786 free(new);
787 return;
788 }
789 /* Check whether linking to the same file system instance. */
790 if ((old_node->fs_handle != new_par_lr.triplet.fs_handle) ||
791 (old_node->dev_handle != new_par_lr.triplet.dev_handle)) {
792 rwlock_write_unlock(&namespace_rwlock);
793 ipc_answer_0(rid, EXDEV); /* different file systems */
794 free(old);
795 free(new);
796 return;
797 }
798 /* Destroy the old link for the new name. */
799 vfs_node_t *new_node = NULL;
800 rc = vfs_lookup_internal(newc, L_UNLINK, &new_lr, NULL);
801 switch (rc) {
802 case ENOENT:
803 /* simply not in our way */
804 break;
805 case EOK:
806 new_node = vfs_node_get(&new_lr);
807 if (!new_node) {
808 rwlock_write_unlock(&namespace_rwlock);
809 ipc_answer_0(rid, ENOMEM);
810 free(old);
811 free(new);
812 return;
813 }
814 futex_down(&nodes_futex);
815 new_node->lnkcnt--;
816 futex_up(&nodes_futex);
817 break;
818 default:
819 rwlock_write_unlock(&namespace_rwlock);
820 ipc_answer_0(rid, ENOTEMPTY);
821 free(old);
822 free(new);
823 return;
824 }
825 /* Create the new link for the new name. */
826 rc = vfs_lookup_internal(newc, L_LINK, NULL, NULL, old_node->index);
827 if (rc != EOK) {
828 rwlock_write_unlock(&namespace_rwlock);
829 if (new_node)
830 vfs_node_put(new_node);
831 ipc_answer_0(rid, rc);
832 free(old);
833 free(new);
834 return;
835 }
836 futex_down(&nodes_futex);
837 old_node->lnkcnt++;
838 futex_up(&nodes_futex);
839 /* Destroy the link for the old name. */
840 rc = vfs_lookup_internal(oldc, L_UNLINK, NULL, NULL);
841 if (rc != EOK) {
842 rwlock_write_unlock(&namespace_rwlock);
843 vfs_node_put(old_node);
844 if (new_node)
845 vfs_node_put(new_node);
846 ipc_answer_0(rid, rc);
847 free(old);
848 free(new);
849 return;
850 }
851 futex_down(&nodes_futex);
852 old_node->lnkcnt--;
853 futex_up(&nodes_futex);
854 rwlock_write_unlock(&namespace_rwlock);
855 vfs_node_put(old_node);
856 if (new_node)
857 vfs_node_put(new_node);
858 free(old);
859 free(new);
860 ipc_answer_0(rid, EOK);
861}
862
863/**
864 * @}
865 */
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