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2689 jermar 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 <ipc/ipc.h>
39
#include <async.h>
40
#include <errno.h>
41
#include <stdio.h>
42
#include <stdlib.h>
43
#include <string.h>
44
#include <bool.h>
45
#include <futex.h>
46
#include <rwlock.h>
47
#include <libadt/list.h>
48
#include <unistd.h>
49
#include <ctype.h>
2708 jermar 50
#include <fcntl.h>
2689 jermar 51
#include <assert.h>
52
#include <atomic.h>
53
#include "vfs.h"
54
 
55
/**
56
 * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
57
 * concurrent VFS operation which modifies the file system namespace.
58
 */
59
RWLOCK_INITIALIZE(namespace_rwlock);
60
 
61
atomic_t rootfs_futex = FUTEX_INITIALIZER;
62
vfs_triplet_t rootfs = {
63
    .fs_handle = 0,
64
    .dev_handle = 0,
65
    .index = 0,
66
};
67
 
2691 jermar 68
static int lookup_root(int fs_handle, int dev_handle, vfs_lookup_res_t *result)
2689 jermar 69
{
70
    vfs_pair_t altroot = {
71
        .fs_handle = fs_handle,
72
        .dev_handle = dev_handle,
73
    };
74
 
2700 jermar 75
    return vfs_lookup_internal("/", strlen("/"), L_DIRECTORY, result,
76
        &altroot);
2689 jermar 77
}
78
 
79
void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
80
{
81
    int dev_handle;
82
    vfs_node_t *mp_node = NULL;
83
 
84
    /*
85
     * We expect the library to do the device-name to device-handle
86
     * translation for us, thus the device handle will arrive as ARG1
87
     * in the request.
88
     */
89
    dev_handle = IPC_GET_ARG1(*request);
90
 
91
    /*
92
     * For now, don't make use of ARG2 and ARG3, but they can be used to
93
     * carry mount options in the future.
94
     */
95
 
96
    ipc_callid_t callid;
97
    size_t size;
98
 
99
    /*
100
     * Now, we expect the client to send us data with the name of the file
101
     * system.
102
     */
103
    if (!ipc_data_write_receive(&callid, &size)) {
104
        ipc_answer_0(callid, EINVAL);
105
        ipc_answer_0(rid, EINVAL);
106
        return;
107
    }
108
 
109
    /*
110
     * Don't receive more than is necessary for storing a full file system
111
     * name.
112
     */
113
    if (size < 1 || size > FS_NAME_MAXLEN) {
114
        ipc_answer_0(callid, EINVAL);
115
        ipc_answer_0(rid, EINVAL);
116
        return;
117
    }
118
 
2707 jermar 119
    /* Deliver the file system name. */
2689 jermar 120
    char fs_name[FS_NAME_MAXLEN + 1];
121
    (void) ipc_data_write_finalize(callid, fs_name, size);
122
    fs_name[size] = '\0';
123
 
124
    /*
125
     * Check if we know a file system with the same name as is in fs_name.
126
     * This will also give us its file system handle.
127
     */
128
    int fs_handle = fs_name_to_handle(fs_name, true);
129
    if (!fs_handle) {
130
        ipc_answer_0(rid, ENOENT);
131
        return;
132
    }
133
 
2707 jermar 134
    /* Now, we want the client to send us the mount point. */
2689 jermar 135
    if (!ipc_data_write_receive(&callid, &size)) {
136
        ipc_answer_0(callid, EINVAL);
137
        ipc_answer_0(rid, EINVAL);
138
        return;
139
    }
140
 
2707 jermar 141
    /* Check whether size is reasonable wrt. the mount point. */
2689 jermar 142
    if (size < 1 || size > MAX_PATH_LEN) {
143
        ipc_answer_0(callid, EINVAL);
144
        ipc_answer_0(rid, EINVAL);
145
        return;
146
    }
2707 jermar 147
    /* Allocate buffer for the mount point data being received. */
2689 jermar 148
    uint8_t *buf;
149
    buf = malloc(size);
150
    if (!buf) {
151
        ipc_answer_0(callid, ENOMEM);
152
        ipc_answer_0(rid, ENOMEM);
153
        return;
154
    }
155
 
2707 jermar 156
    /* Deliver the mount point. */
2689 jermar 157
    (void) ipc_data_write_finalize(callid, buf, size);
158
 
159
    /*
160
     * Lookup the root node of the filesystem being mounted.
161
     * In this case, we don't need to take the namespace_futex as the root
162
     * node cannot be removed. However, we do take a reference to it so
163
     * that we can track how many times it has been mounted.
164
     */
165
    int rc;
2691 jermar 166
    vfs_lookup_res_t mr_res;
167
    rc = lookup_root(fs_handle, dev_handle, &mr_res);
2689 jermar 168
    if (rc != EOK) {
169
        free(buf);
170
        ipc_answer_0(rid, rc);
171
        return;
172
    }
2691 jermar 173
    vfs_node_t *mr_node = vfs_node_get(&mr_res);
2689 jermar 174
    if (!mr_node) {
175
        free(buf);
176
        ipc_answer_0(rid, ENOMEM);
177
        return;
178
    }
179
 
2707 jermar 180
    /* Finally, we need to resolve the path to the mountpoint. */
2691 jermar 181
    vfs_lookup_res_t mp_res;
2689 jermar 182
    futex_down(&rootfs_futex);
183
    if (rootfs.fs_handle) {
2707 jermar 184
        /* We already have the root FS. */
2689 jermar 185
        rwlock_write_lock(&namespace_rwlock);
2700 jermar 186
        rc = vfs_lookup_internal(buf, size, L_DIRECTORY, &mp_res,
187
            NULL);
2689 jermar 188
        if (rc != EOK) {
2707 jermar 189
            /* The lookup failed for some reason. */
2689 jermar 190
            rwlock_write_unlock(&namespace_rwlock);
191
            futex_up(&rootfs_futex);
192
            vfs_node_put(mr_node);  /* failed -> drop reference */
193
            free(buf);
194
            ipc_answer_0(rid, rc);
195
            return;
196
        }
2691 jermar 197
        mp_node = vfs_node_get(&mp_res);
2689 jermar 198
        if (!mp_node) {
199
            rwlock_write_unlock(&namespace_rwlock);
200
            futex_up(&rootfs_futex);
201
            vfs_node_put(mr_node);  /* failed -> drop reference */
202
            free(buf);
203
            ipc_answer_0(rid, ENOMEM);
204
            return;
205
        }
206
        /*
207
         * Now we hold a reference to mp_node.
208
         * It will be dropped upon the corresponding VFS_UNMOUNT.
209
         * This prevents the mount point from being deleted.
210
         */
211
        rwlock_write_unlock(&namespace_rwlock);
212
    } else {
2707 jermar 213
        /* We still don't have the root file system mounted. */
2689 jermar 214
        if ((size == 1) && (buf[0] == '/')) {
2707 jermar 215
            /* For this simple, but important case, we are done. */
2691 jermar 216
            rootfs = mr_res.triplet;
2689 jermar 217
            futex_up(&rootfs_futex);
218
            free(buf);
219
            ipc_answer_0(rid, EOK);
220
            return;
221
        } else {
222
            /*
223
             * We can't resolve this without the root filesystem
224
             * being mounted first.
225
             */
226
            futex_up(&rootfs_futex);
227
            free(buf);
228
            vfs_node_put(mr_node);  /* failed -> drop reference */
229
            ipc_answer_0(rid, ENOENT);
230
            return;
231
        }
232
    }
233
    futex_up(&rootfs_futex);
234
 
235
    free(buf);  /* The buffer is not needed anymore. */
236
 
237
    /*
238
     * At this point, we have all necessary pieces: file system and device
239
     * handles, and we know the mount point VFS node and also the root node
240
     * of the file system being mounted.
241
     */
242
 
2691 jermar 243
    int phone = vfs_grab_phone(mp_res.triplet.fs_handle);
2689 jermar 244
    /* Later we can use ARG3 to pass mode/flags. */
2691 jermar 245
    aid_t req1 = async_send_3(phone, VFS_MOUNT,
246
        (ipcarg_t) mp_res.triplet.dev_handle,
247
        (ipcarg_t) mp_res.triplet.index, 0, NULL);
2689 jermar 248
    /* The second call uses the same method. */
249
    aid_t req2 = async_send_3(phone, VFS_MOUNT,
2691 jermar 250
        (ipcarg_t) mr_res.triplet.fs_handle,
251
        (ipcarg_t) mr_res.triplet.dev_handle,
252
        (ipcarg_t) mr_res.triplet.index, NULL);
2689 jermar 253
    vfs_release_phone(phone);
254
 
255
    ipcarg_t rc1;
256
    ipcarg_t rc2;
257
    async_wait_for(req1, &rc1);
258
    async_wait_for(req2, &rc2);
259
 
260
    if ((rc1 != EOK) || (rc2 != EOK)) {
261
        /* Mount failed, drop references to mr_node and mp_node. */
262
        vfs_node_put(mr_node);
263
        if (mp_node)
264
            vfs_node_put(mp_node);
265
    }
266
 
267
    if (rc2 == EOK)
268
        ipc_answer_0(rid, rc1);
269
    else if (rc1 == EOK)
270
        ipc_answer_0(rid, rc2);
271
    else
272
        ipc_answer_0(rid, rc1);
273
}
274
 
275
void vfs_open(ipc_callid_t rid, ipc_call_t *request)
276
{
277
    if (!vfs_files_init()) {
278
        ipc_answer_0(rid, ENOMEM);
279
        return;
280
    }
281
 
282
    /*
2700 jermar 283
     * The POSIX interface is open(path, oflag, mode).
284
     * We can receive oflags and mode along with the VFS_OPEN call; the path
2689 jermar 285
     * will need to arrive in another call.
2700 jermar 286
     *
287
     * We also receive one private, non-POSIX set of flags called lflag
288
     * used to pass information to vfs_lookup_internal().
2689 jermar 289
     */
2700 jermar 290
    int lflag = IPC_GET_ARG1(*request);
291
    int oflag = IPC_GET_ARG2(*request);
292
    int mode = IPC_GET_ARG3(*request);
2689 jermar 293
    size_t len;
294
 
2708 jermar 295
    if (oflag & O_CREAT)
296
        lflag |= L_CREATE;
297
    if (oflag & O_EXCL)
298
        lflag |= L_EXCLUSIVE;
299
 
2689 jermar 300
    ipc_callid_t callid;
301
 
302
    if (!ipc_data_write_receive(&callid, &len)) {
303
        ipc_answer_0(callid, EINVAL);
304
        ipc_answer_0(rid, EINVAL);
305
        return;
306
    }
307
 
308
    /*
309
     * Now we are on the verge of accepting the path.
310
     *
311
     * There is one optimization we could do in the future: copy the path
312
     * directly into the PLB using some kind of a callback.
313
     */
314
    char *path = malloc(len);
315
 
316
    if (!path) {
317
        ipc_answer_0(callid, ENOMEM);
318
        ipc_answer_0(rid, ENOMEM);
319
        return;
320
    }
321
 
322
    int rc;
323
    if ((rc = ipc_data_write_finalize(callid, path, len))) {
324
        ipc_answer_0(rid, rc);
325
        free(path);
326
        return;
327
    }
328
 
329
    /*
330
     * Avoid the race condition in which the file can be deleted before we
331
     * find/create-and-lock the VFS node corresponding to the looked-up
332
     * triplet.
333
     */
2708 jermar 334
    if (lflag & L_CREATE)
335
        rwlock_write_lock(&namespace_rwlock);
336
    else
337
        rwlock_read_lock(&namespace_rwlock);
2689 jermar 338
 
2707 jermar 339
    /* The path is now populated and we can call vfs_lookup_internal(). */
2691 jermar 340
    vfs_lookup_res_t lr;
2700 jermar 341
    rc = vfs_lookup_internal(path, len, lflag, &lr, NULL);
2689 jermar 342
    if (rc) {
2708 jermar 343
        if (lflag & L_CREATE)
344
            rwlock_write_unlock(&namespace_rwlock);
345
        else
346
            rwlock_read_unlock(&namespace_rwlock);
2689 jermar 347
        ipc_answer_0(rid, rc);
348
        free(path);
349
        return;
350
    }
351
 
2707 jermar 352
    /** Path is no longer needed. */
2689 jermar 353
    free(path);
354
 
2691 jermar 355
    vfs_node_t *node = vfs_node_get(&lr);
2708 jermar 356
    if (lflag & L_CREATE)
357
        rwlock_write_unlock(&namespace_rwlock);
358
    else
359
        rwlock_read_unlock(&namespace_rwlock);
2689 jermar 360
 
361
    /*
362
     * Get ourselves a file descriptor and the corresponding vfs_file_t
363
     * structure.
364
     */
365
    int fd = vfs_fd_alloc();
366
    if (fd < 0) {
367
        vfs_node_put(node);
368
        ipc_answer_0(rid, fd);
369
        return;
370
    }
371
    vfs_file_t *file = vfs_file_get(fd);
372
    file->node = node;
373
 
374
    /*
375
     * The following increase in reference count is for the fact that the
376
     * file is being opened and that a file structure is pointing to it.
377
     * It is necessary so that the file will not disappear when
378
     * vfs_node_put() is called. The reference will be dropped by the
379
     * respective VFS_CLOSE.
380
     */
381
    vfs_node_addref(node);
382
    vfs_node_put(node);
383
 
2707 jermar 384
    /* Success! Return the new file descriptor to the client. */
2689 jermar 385
    ipc_answer_1(rid, EOK, fd);
386
}
387
 
388
static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
389
{
390
 
391
    /*
392
     * The following code strongly depends on the fact that the files data
393
     * structure can be only accessed by a single fibril and all file
394
     * operations are serialized (i.e. the reads and writes cannot
395
     * interleave and a file cannot be closed while it is being read).
396
     *
397
     * Additional synchronization needs to be added once the table of
398
     * open files supports parallel access!
399
     */
400
 
401
    int fd = IPC_GET_ARG1(*request);
402
 
2707 jermar 403
    /* Lookup the file structure corresponding to the file descriptor. */
2689 jermar 404
    vfs_file_t *file = vfs_file_get(fd);
405
    if (!file) {
406
        ipc_answer_0(rid, ENOENT);
407
        return;
408
    }
409
 
410
    /*
411
     * Now we need to receive a call with client's
412
     * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
413
     */
414
    ipc_callid_t callid;
415
    int res;
416
    if (read)
417
        res = ipc_data_read_receive(&callid, NULL);
418
    else
419
        res = ipc_data_write_receive(&callid, NULL);
420
    if (!res) {
421
        ipc_answer_0(callid, EINVAL);
422
        ipc_answer_0(rid, EINVAL);
423
        return;
424
    }
425
 
426
    /*
427
     * Lock the open file structure so that no other thread can manipulate
428
     * the same open file at a time.
429
     */
430
    futex_down(&file->lock);
431
 
432
    /*
433
     * Lock the file's node so that no other client can read/write to it at
434
     * the same time.
435
     */
436
    if (read)
437
        rwlock_read_lock(&file->node->contents_rwlock);
438
    else
439
        rwlock_write_lock(&file->node->contents_rwlock);
440
 
441
    int fs_phone = vfs_grab_phone(file->node->fs_handle);  
442
 
2707 jermar 443
    /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
2689 jermar 444
    aid_t msg;
445
    ipc_call_t answer;
446
    msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
447
        file->node->dev_handle, file->node->index, file->pos, &answer);
448
 
449
    /*
450
     * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
451
     * destination FS server. The call will be routed as if sent by
452
     * ourselves. Note that call arguments are immutable in this case so we
453
     * don't have to bother.
454
     */
455
    ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
456
 
457
    vfs_release_phone(fs_phone);
458
 
2707 jermar 459
    /* Wait for reply from the FS server. */
2689 jermar 460
    ipcarg_t rc;
461
    async_wait_for(msg, &rc);
462
    size_t bytes = IPC_GET_ARG1(answer);
463
 
2707 jermar 464
    /* Unlock the VFS node. */
2689 jermar 465
    if (read)
466
        rwlock_read_unlock(&file->node->contents_rwlock);
467
    else {
468
        /* Update the cached version of node's size. */
469
        file->node->size = IPC_GET_ARG2(answer);
470
        rwlock_write_unlock(&file->node->contents_rwlock);
471
    }
472
 
2707 jermar 473
    /* Update the position pointer and unlock the open file. */
2689 jermar 474
    file->pos += bytes;
475
    futex_up(&file->lock);
476
 
477
    /*
478
     * FS server's reply is the final result of the whole operation we
479
     * return to the client.
480
     */
481
    ipc_answer_1(rid, rc, bytes);
482
}
483
 
484
void vfs_read(ipc_callid_t rid, ipc_call_t *request)
485
{
486
    vfs_rdwr(rid, request, true);
487
}
488
 
489
void vfs_write(ipc_callid_t rid, ipc_call_t *request)
490
{
491
    vfs_rdwr(rid, request, false);
492
}
493
 
494
void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
495
{
496
    int fd = (int) IPC_GET_ARG1(*request);
497
    off_t off = (off_t) IPC_GET_ARG2(*request);
498
    int whence = (int) IPC_GET_ARG3(*request);
499
 
500
 
2707 jermar 501
    /* Lookup the file structure corresponding to the file descriptor. */
2689 jermar 502
    vfs_file_t *file = vfs_file_get(fd);
503
    if (!file) {
504
        ipc_answer_0(rid, ENOENT);
505
        return;
506
    }
507
 
508
    off_t newpos;
509
    futex_down(&file->lock);
510
    if (whence == SEEK_SET) {
511
        file->pos = off;
512
        futex_up(&file->lock);
513
        ipc_answer_1(rid, EOK, off);
514
        return;
515
    }
516
    if (whence == SEEK_CUR) {
517
        if (file->pos + off < file->pos) {
518
            futex_up(&file->lock);
519
            ipc_answer_0(rid, EOVERFLOW);
520
            return;
521
        }
522
        file->pos += off;
523
        newpos = file->pos;
524
        futex_up(&file->lock);
525
        ipc_answer_1(rid, EOK, newpos);
526
        return;
527
    }
528
    if (whence == SEEK_END) {
529
        rwlock_read_lock(&file->node->contents_rwlock);
530
        size_t size = file->node->size;
531
        rwlock_read_unlock(&file->node->contents_rwlock);
532
        if (size + off < size) {
533
            futex_up(&file->lock);
534
            ipc_answer_0(rid, EOVERFLOW);
535
            return;
536
        }
537
        newpos = size + off;
538
        futex_up(&file->lock);
539
        ipc_answer_1(rid, EOK, newpos);
540
        return;
541
    }
542
    futex_up(&file->lock);
543
    ipc_answer_0(rid, EINVAL);
544
}
545
 
2693 jermar 546
void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
547
{
548
    int fd = IPC_GET_ARG1(*request);
549
    size_t size = IPC_GET_ARG2(*request);
550
    ipcarg_t rc;
551
 
552
    vfs_file_t *file = vfs_file_get(fd);
553
    if (!file) {
554
        ipc_answer_0(rid, ENOENT);
555
        return;
556
    }
557
    futex_down(&file->lock);
558
 
559
    rwlock_write_lock(&file->node->contents_rwlock);
560
    int fs_phone = vfs_grab_phone(file->node->fs_handle);
2707 jermar 561
    rc = async_req_3_0(fs_phone, VFS_TRUNCATE,
562
        (ipcarg_t)file->node->dev_handle, (ipcarg_t)file->node->index,
563
        (ipcarg_t)size);
2693 jermar 564
    vfs_release_phone(fs_phone);
565
    if (rc == EOK)
566
        file->node->size = size;
567
    rwlock_write_unlock(&file->node->contents_rwlock);
568
 
569
    futex_up(&file->lock);
2698 jermar 570
    ipc_answer_0(rid, rc);
2693 jermar 571
}
572
 
2707 jermar 573
void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
574
{
575
    int mode = IPC_GET_ARG1(*request);
576
    size_t len;
577
 
578
    ipc_callid_t callid;
579
 
580
    if (!ipc_data_write_receive(&callid, &len)) {
581
        ipc_answer_0(callid, EINVAL);
582
        ipc_answer_0(rid, EINVAL);
583
        return;
584
    }
585
 
586
    /*
587
     * Now we are on the verge of accepting the path.
588
     *
589
     * There is one optimization we could do in the future: copy the path
590
     * directly into the PLB using some kind of a callback.
591
     */
592
    char *path = malloc(len);
593
 
594
    if (!path) {
595
        ipc_answer_0(callid, ENOMEM);
596
        ipc_answer_0(rid, ENOMEM);
597
        return;
598
    }
599
 
600
    int rc;
601
    if ((rc = ipc_data_write_finalize(callid, path, len))) {
602
        ipc_answer_0(rid, rc);
603
        free(path);
604
        return;
605
    }
606
 
607
    rwlock_write_lock(&namespace_rwlock);
608
    int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
609
    rc = vfs_lookup_internal(path, len, lflag, NULL, NULL);
610
    rwlock_write_unlock(&namespace_rwlock);
611
    free(path);
612
    ipc_answer_0(rid, rc);
613
}
614
 
2689 jermar 615
/**
616
 * @}
617
 */