source: mainline/uspace/srv/fs/tmpfs/tmpfs_ops.c@ 72bde81

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 72bde81 was 72bde81, checked in by Jakub Jermar <jakub@…>, 17 years ago

Support for mkdir().
  • Property mode set to 100644
File size: 13.4 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 tmpfs_ops.c
35 * @brief Implementation of VFS operations for the TMPFS file system
36 * server.
37 */
38
39#include "tmpfs.h"
40#include "../../vfs/vfs.h"
41#include <ipc/ipc.h>
42#include <async.h>
43#include <errno.h>
44#include <atomic.h>
45#include <stdlib.h>
46#include <string.h>
47#include <stdio.h>
48#include <dirent.h>
49#include <assert.h>
50#include <sys/types.h>
51#include <libadt/hash_table.h>
52#include <as.h>
53
54#define min(a, b) ((a) < (b) ? (a) : (b))
55#define max(a, b) ((a) > (b) ? (a) : (b))
56
57#define PLB_GET_CHAR(i) (tmpfs_reg.plb_ro[(i) % PLB_SIZE])
58
59#define DENTRIES_BUCKETS 256
60
61/*
62 * Hash table of all directory entries.
63 */
64hash_table_t dentries;
65
66static hash_index_t dentries_hash(unsigned long *key)
67{
68 return *key % DENTRIES_BUCKETS;
69}
70
71static int dentries_compare(unsigned long *key, hash_count_t keys,
72 link_t *item)
73{
74 tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
75 dh_link);
76 return dentry->index == *key;
77}
78
79static void dentries_remove_callback(link_t *item)
80{
81}
82
83/** TMPFS dentries hash table operations. */
84hash_table_operations_t dentries_ops = {
85 .hash = dentries_hash,
86 .compare = dentries_compare,
87 .remove_callback = dentries_remove_callback
88};
89
90unsigned tmpfs_next_index = 1;
91
92static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
93{
94 dentry->index = 0;
95 dentry->parent = NULL;
96 dentry->sibling = NULL;
97 dentry->child = NULL;
98 dentry->name = NULL;
99 dentry->type = TMPFS_NONE;
100 dentry->size = 0;
101 dentry->data = NULL;
102 link_initialize(&dentry->dh_link);
103}
104
105/*
106 * For now, we don't distinguish between different dev_handles/instances. All
107 * requests resolve to the only instance, rooted in the following variable.
108 */
109static tmpfs_dentry_t *root;
110
111static bool tmpfs_init(void)
112{
113 if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
114 return false;
115
116 root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
117 if (!root)
118 return false;
119 tmpfs_dentry_initialize(root);
120 root->index = tmpfs_next_index++;
121 root->name = "";
122 root->type = TMPFS_DIRECTORY;
123 hash_table_insert(&dentries, &root->index, &root->dh_link);
124
125 /*
126 * This is only for debugging. Once we can create files and directories
127 * using VFS, we can get rid of this.
128 */
129 tmpfs_dentry_t *d;
130 d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
131 if (!d) {
132 free(root);
133 root = NULL;
134 return false;
135 }
136 tmpfs_dentry_initialize(d);
137 d->index = tmpfs_next_index++;
138 root->child = d;
139 d->parent = root;
140 d->type = TMPFS_DIRECTORY;
141 d->name = "dir1";
142 hash_table_insert(&dentries, &d->index, &d->dh_link);
143
144 d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
145 if (!d) {
146 free(root->child);
147 free(root);
148 root = NULL;
149 return false;
150 }
151 tmpfs_dentry_initialize(d);
152 d->index = tmpfs_next_index++;
153 root->child->sibling = d;
154 d->parent = root;
155 d->type = TMPFS_DIRECTORY;
156 d->name = "dir2";
157 hash_table_insert(&dentries, &d->index, &d->dh_link);
158
159 d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
160 if (!d) {
161 free(root->child->sibling);
162 free(root->child);
163 free(root);
164 root = NULL;
165 return false;
166 }
167 tmpfs_dentry_initialize(d);
168 d->index = tmpfs_next_index++;
169 root->child->child = d;
170 d->parent = root->child;
171 d->type = TMPFS_FILE;
172 d->name = "file1";
173 d->data = "This is the contents of /dir1/file1.\n";
174 d->size = strlen(d->data);
175 hash_table_insert(&dentries, &d->index, &d->dh_link);
176
177 d = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
178 if (!d) {
179 free(root->child->sibling);
180 free(root->child->child);
181 free(root->child);
182 free(root);
183 root = NULL;
184 return false;
185 }
186 tmpfs_dentry_initialize(d);
187 d->index = tmpfs_next_index++;
188 root->child->sibling->child = d;
189 d->parent = root->child->sibling;
190 d->type = TMPFS_FILE;
191 d->name = "file2";
192 d->data = "This is the contents of /dir2/file2.\n";
193 d->size = strlen(d->data);
194 hash_table_insert(&dentries, &d->index, &d->dh_link);
195
196 return true;
197}
198
199/** Compare one component of path to a directory entry.
200 *
201 * @param dentry Directory entry to compare the path component with.
202 * @param component Array of characters holding component name.
203 *
204 * @return True on match, false otherwise.
205 */
206static bool match_component(tmpfs_dentry_t *dentry, const char *component)
207{
208 return !strcmp(dentry->name, component);
209}
210
211static unsigned long create_node(tmpfs_dentry_t *dentry,
212 const char *component, int lflag)
213{
214 assert(dentry->type == TMPFS_DIRECTORY);
215 assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
216
217 tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
218 if (!node)
219 return 0;
220 size_t len = strlen(component);
221 char *name = malloc(len + 1);
222 if (!name) {
223 free(node);
224 return 0;
225 }
226 strcpy(name, component);
227
228 tmpfs_dentry_initialize(node);
229 node->index = tmpfs_next_index++;
230 node->name = name;
231 node->parent = dentry;
232 if (lflag & L_DIRECTORY)
233 node->type = TMPFS_DIRECTORY;
234 else
235 node->type = TMPFS_FILE;
236
237 /* Insert the new node into the namespace. */
238 if (dentry->child) {
239 tmpfs_dentry_t *tmp = dentry->child;
240 while (tmp->sibling)
241 tmp = tmp->sibling;
242 tmp->sibling = node;
243 } else {
244 dentry->child = node;
245 }
246
247 /* Insert the new node into the dentry hash table. */
248 hash_table_insert(&dentries, &node->index, &node->dh_link);
249 return node->index;
250}
251
252static int destroy_component(tmpfs_dentry_t *dentry)
253{
254 return EPERM;
255}
256
257void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
258{
259 unsigned next = IPC_GET_ARG1(*request);
260 unsigned last = IPC_GET_ARG2(*request);
261 int dev_handle = IPC_GET_ARG3(*request);
262 int lflag = IPC_GET_ARG4(*request);
263
264 if (last < next)
265 last += PLB_SIZE;
266
267 /*
268 * Initialize TMPFS.
269 */
270 if (!root && !tmpfs_init()) {
271 ipc_answer_0(rid, ENOMEM);
272 return;
273 }
274
275 tmpfs_dentry_t *dtmp = root->child;
276 tmpfs_dentry_t *dcur = root;
277
278 if (PLB_GET_CHAR(next) == '/')
279 next++; /* eat slash */
280
281 char component[NAME_MAX + 1];
282 int len = 0;
283 while (dtmp && next <= last) {
284
285 /* collect the component */
286 if (PLB_GET_CHAR(next) != '/') {
287 if (len + 1 == NAME_MAX) {
288 /* comopnent length overflow */
289 ipc_answer_0(rid, ENAMETOOLONG);
290 return;
291 }
292 component[len++] = PLB_GET_CHAR(next);
293 next++; /* process next character */
294 if (next <= last)
295 continue;
296 }
297
298 assert(len);
299 component[len] = '\0';
300 next++; /* eat slash */
301 len = 0;
302
303 /* match the component */
304 while (dtmp && !match_component(dtmp, component))
305 dtmp = dtmp->sibling;
306
307 /* handle miss: match amongst siblings */
308 if (!dtmp) {
309 if ((next > last) && (lflag & L_CREATE)) {
310 /* no components left and L_CREATE specified */
311 if (dcur->type != TMPFS_DIRECTORY) {
312 ipc_answer_0(rid, ENOTDIR);
313 return;
314 }
315 unsigned long index = create_node(dcur,
316 component, lflag);
317 if (index > 0) {
318 ipc_answer_4(rid, EOK,
319 tmpfs_reg.fs_handle, dev_handle,
320 index, 0);
321 } else {
322 ipc_answer_0(rid, ENOSPC);
323 }
324 return;
325 }
326 ipc_answer_0(rid, ENOENT);
327 return;
328 }
329
330 /* descent one level */
331 dcur = dtmp;
332 dtmp = dtmp->child;
333 }
334
335 /* handle miss: excessive components */
336 if (!dtmp && next <= last) {
337 if (lflag & L_CREATE) {
338 if (dcur->type != TMPFS_DIRECTORY) {
339 ipc_answer_0(rid, ENOTDIR);
340 return;
341 }
342
343 /* collect next component */
344 while (next <= last) {
345 if (PLB_GET_CHAR(next) == '/') {
346 /* more than one component */
347 ipc_answer_0(rid, ENOENT);
348 return;
349 }
350 if (len + 1 == NAME_MAX) {
351 /* component length overflow */
352 ipc_answer_0(rid, ENAMETOOLONG);
353 return;
354 }
355 component[len++] = PLB_GET_CHAR(next);
356 next++; /* process next character */
357 }
358 assert(len);
359 component[len] = '\0';
360 len = 0;
361
362 unsigned long index;
363 index = create_node(dcur, component, lflag);
364 if (index) {
365 ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle,
366 dev_handle, index, 0);
367 } else {
368 ipc_answer_0(rid, ENOSPC);
369 }
370 return;
371 }
372 ipc_answer_0(rid, ENOENT);
373 return;
374 }
375
376 /* handle hit */
377 if (lflag & L_DESTROY) {
378 int res = destroy_component(dcur);
379 ipc_answer_0(rid, res);
380 return;
381 }
382 if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
383 ipc_answer_0(rid, EEXIST);
384 return;
385 }
386 if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
387 ipc_answer_0(rid, EISDIR);
388 return;
389 }
390 if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
391 ipc_answer_0(rid, ENOTDIR);
392 return;
393 }
394
395 ipc_answer_4(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
396 dcur->size);
397}
398
399void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
400{
401 int dev_handle = IPC_GET_ARG1(*request);
402 unsigned long index = IPC_GET_ARG2(*request);
403 off_t pos = IPC_GET_ARG3(*request);
404
405 /*
406 * Lookup the respective dentry.
407 */
408 link_t *hlp;
409 hlp = hash_table_find(&dentries, &index);
410 if (!hlp) {
411 ipc_answer_0(rid, ENOENT);
412 return;
413 }
414 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
415 dh_link);
416
417 /*
418 * Receive the read request.
419 */
420 ipc_callid_t callid;
421 size_t len;
422 if (!ipc_data_read_receive(&callid, &len)) {
423 ipc_answer_0(callid, EINVAL);
424 ipc_answer_0(rid, EINVAL);
425 return;
426 }
427
428 size_t bytes;
429 if (dentry->type == TMPFS_FILE) {
430 bytes = max(0, min(dentry->size - pos, len));
431 (void) ipc_data_read_finalize(callid, dentry->data + pos,
432 bytes);
433 } else {
434 int i;
435 tmpfs_dentry_t *cur = dentry->child;
436
437 assert(dentry->type == TMPFS_DIRECTORY);
438
439 /*
440 * Yes, we really use O(n) algorithm here.
441 * If it bothers someone, it could be fixed by introducing a
442 * hash table.
443 */
444 for (i = 0, cur = dentry->child; i < pos && cur; i++,
445 cur = cur->sibling)
446 ;
447
448 if (!cur) {
449 ipc_answer_0(callid, ENOENT);
450 ipc_answer_1(rid, ENOENT, 0);
451 return;
452 }
453
454 (void) ipc_data_read_finalize(callid, cur->name,
455 strlen(cur->name) + 1);
456 bytes = 1;
457 }
458
459 /*
460 * Answer the VFS_READ call.
461 */
462 ipc_answer_1(rid, EOK, bytes);
463}
464
465void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
466{
467 int dev_handle = IPC_GET_ARG1(*request);
468 unsigned long index = IPC_GET_ARG2(*request);
469 off_t pos = IPC_GET_ARG3(*request);
470
471 /*
472 * Lookup the respective dentry.
473 */
474 link_t *hlp;
475 hlp = hash_table_find(&dentries, &index);
476 if (!hlp) {
477 ipc_answer_0(rid, ENOENT);
478 return;
479 }
480 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
481 dh_link);
482
483 /*
484 * Receive the write request.
485 */
486 ipc_callid_t callid;
487 size_t len;
488 if (!ipc_data_write_receive(&callid, &len)) {
489 ipc_answer_0(callid, EINVAL);
490 ipc_answer_0(rid, EINVAL);
491 return;
492 }
493
494 /*
495 * Check whether the file needs to grow.
496 */
497 if (pos + len <= dentry->size) {
498 /* The file size is not changing. */
499 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
500 ipc_answer_1(rid, EOK, len);
501 return;
502 }
503 size_t delta = (pos + len) - dentry->size;
504 /*
505 * At this point, we are deliberately extremely straightforward and
506 * simply realloc the contents of the file on every write that grows the
507 * file. In the end, the situation might not be as bad as it may look:
508 * our heap allocator can save us and just grow the block whenever
509 * possible.
510 */
511 void *newdata = realloc(dentry->data, dentry->size + delta);
512 if (!newdata) {
513 ipc_answer_0(callid, ENOMEM);
514 ipc_answer_1(rid, EOK, 0);
515 return;
516 }
517 /* Clear any newly allocated memory in order to emulate gaps. */
518 memset(newdata + dentry->size, 0, delta);
519 dentry->size += delta;
520 dentry->data = newdata;
521 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
522 ipc_answer_2(rid, EOK, len, dentry->size);
523}
524
525void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
526{
527 int dev_handle = IPC_GET_ARG1(*request);
528 unsigned long index = IPC_GET_ARG2(*request);
529 size_t size = IPC_GET_ARG3(*request);
530
531 /*
532 * Lookup the respective dentry.
533 */
534 link_t *hlp;
535 hlp = hash_table_find(&dentries, &index);
536 if (!hlp) {
537 ipc_answer_0(rid, ENOENT);
538 return;
539 }
540 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
541 dh_link);
542
543 if (size == dentry->size) {
544 ipc_answer_0(rid, EOK);
545 return;
546 }
547
548 void *newdata = realloc(dentry->data, size);
549 if (!newdata) {
550 ipc_answer_0(rid, ENOMEM);
551 return;
552 }
553 if (size > dentry->size) {
554 size_t delta = size - dentry->size;
555 memset(newdata + dentry->size, 0, delta);
556 }
557 dentry->size = size;
558 dentry->data = newdata;
559 ipc_answer_0(rid, EOK);
560}
561
562/**
563 * @}
564 */
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