source: mainline/uspace/srv/fs/tmpfs/tmpfs_ops.c@ 07e01e6

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 07e01e6 was 75c426b4, checked in by Jakub Jermar <jakub@…>, 17 years ago

Remove duplicate initialization.
  • Property mode set to 100644
File size: 13.1 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 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#define TMPFS_GET_INDEX(x) (((tmpfs_dentry_t *)(x))->index)
62#define TMPFS_GET_LNKCNT(x) 1
63
64/*
65 * Hash table of all directory entries.
66 */
67hash_table_t dentries;
68
69static hash_index_t dentries_hash(unsigned long *key)
70{
71 return *key % DENTRIES_BUCKETS;
72}
73
74static int dentries_compare(unsigned long *key, hash_count_t keys,
75 link_t *item)
76{
77 tmpfs_dentry_t *dentry = hash_table_get_instance(item, tmpfs_dentry_t,
78 dh_link);
79 return dentry->index == *key;
80}
81
82static void dentries_remove_callback(link_t *item)
83{
84}
85
86/** TMPFS dentries hash table operations. */
87hash_table_operations_t dentries_ops = {
88 .hash = dentries_hash,
89 .compare = dentries_compare,
90 .remove_callback = dentries_remove_callback
91};
92
93unsigned tmpfs_next_index = 1;
94
95static void tmpfs_dentry_initialize(tmpfs_dentry_t *dentry)
96{
97 dentry->index = 0;
98 dentry->parent = NULL;
99 dentry->sibling = NULL;
100 dentry->child = NULL;
101 dentry->name = NULL;
102 dentry->type = TMPFS_NONE;
103 dentry->size = 0;
104 dentry->data = NULL;
105 link_initialize(&dentry->dh_link);
106}
107
108/*
109 * For now, we don't distinguish between different dev_handles/instances. All
110 * requests resolve to the only instance, rooted in the following variable.
111 */
112static tmpfs_dentry_t *root;
113
114static bool tmpfs_init(void)
115{
116 if (!hash_table_create(&dentries, DENTRIES_BUCKETS, 1, &dentries_ops))
117 return false;
118
119 root = (tmpfs_dentry_t *) malloc(sizeof(tmpfs_dentry_t));
120 if (!root)
121 return false;
122 tmpfs_dentry_initialize(root);
123 root->index = tmpfs_next_index++;
124 root->name = "";
125 root->type = TMPFS_DIRECTORY;
126 hash_table_insert(&dentries, &root->index, &root->dh_link);
127
128 return true;
129}
130
131/** Compare one component of path to a directory entry.
132 *
133 * @param nodep Node to compare the path component with.
134 * @param component Array of characters holding component name.
135 *
136 * @return True on match, false otherwise.
137 */
138static bool match_component(void *nodep, const char *component)
139{
140 tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
141
142 return !strcmp(dentry->name, component);
143}
144
145static void *create_node(void *nodep,
146 const char *component, int lflag)
147{
148 tmpfs_dentry_t *dentry = (tmpfs_dentry_t *) nodep;
149
150 assert(dentry->type == TMPFS_DIRECTORY);
151 assert((lflag & L_FILE) ^ (lflag & L_DIRECTORY));
152
153 tmpfs_dentry_t *node = malloc(sizeof(tmpfs_dentry_t));
154 if (!node)
155 return NULL;
156 size_t len = strlen(component);
157 char *name = malloc(len + 1);
158 if (!name) {
159 free(node);
160 return NULL;
161 }
162 strcpy(name, component);
163
164 tmpfs_dentry_initialize(node);
165 node->index = tmpfs_next_index++;
166 node->name = name;
167 node->parent = dentry;
168 if (lflag & L_DIRECTORY)
169 node->type = TMPFS_DIRECTORY;
170 else
171 node->type = TMPFS_FILE;
172
173 /* Insert the new node into the namespace. */
174 if (dentry->child) {
175 tmpfs_dentry_t *tmp = dentry->child;
176 while (tmp->sibling)
177 tmp = tmp->sibling;
178 tmp->sibling = node;
179 } else {
180 dentry->child = node;
181 }
182
183 /* Insert the new node into the dentry hash table. */
184 hash_table_insert(&dentries, &node->index, &node->dh_link);
185 return (void *) node;
186}
187
188static int destroy_component(void *nodeptr)
189{
190 tmpfs_dentry_t *dentry = (tmpfs_dentry_t *)nodeptr;
191
192 if (dentry->child)
193 return ENOTEMPTY;
194
195 if (!dentry->parent)
196 return EBUSY;
197
198 if (dentry->parent->child == dentry) {
199 dentry->parent->child = dentry->sibling;
200 } else {
201 /* TODO: consider doubly linked list for organizing siblings. */
202 tmpfs_dentry_t *tmp = dentry->parent->child;
203 while (tmp->sibling != dentry)
204 tmp = tmp->sibling;
205 tmp->sibling = dentry->sibling;
206 }
207 dentry->sibling = NULL;
208 dentry->parent = NULL;
209
210 return EOK;
211}
212
213void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
214{
215 unsigned next = IPC_GET_ARG1(*request);
216 unsigned last = IPC_GET_ARG2(*request);
217 int dev_handle = IPC_GET_ARG3(*request);
218 int lflag = IPC_GET_ARG4(*request);
219
220 if (last < next)
221 last += PLB_SIZE;
222
223 /*
224 * Initialize TMPFS.
225 */
226 if (!root && !tmpfs_init()) {
227 ipc_answer_0(rid, ENOMEM);
228 return;
229 }
230
231 tmpfs_dentry_t *dtmp = root->child;
232 tmpfs_dentry_t *dcur = root;
233
234 if (PLB_GET_CHAR(next) == '/')
235 next++; /* eat slash */
236
237 char component[NAME_MAX + 1];
238 int len = 0;
239 while (dtmp && next <= last) {
240
241 /* collect the component */
242 if (PLB_GET_CHAR(next) != '/') {
243 if (len + 1 == NAME_MAX) {
244 /* comopnent length overflow */
245 ipc_answer_0(rid, ENAMETOOLONG);
246 return;
247 }
248 component[len++] = PLB_GET_CHAR(next);
249 next++; /* process next character */
250 if (next <= last)
251 continue;
252 }
253
254 assert(len);
255 component[len] = '\0';
256 next++; /* eat slash */
257 len = 0;
258
259 /* match the component */
260 while (dtmp && !match_component(dtmp, component))
261 dtmp = dtmp->sibling;
262
263 /* handle miss: match amongst siblings */
264 if (!dtmp) {
265 if ((next > last) && (lflag & L_CREATE)) {
266 /* no components left and L_CREATE specified */
267 if (dcur->type != TMPFS_DIRECTORY) {
268 ipc_answer_0(rid, ENOTDIR);
269 return;
270 }
271 void *nodep = create_node(dcur,
272 component, lflag);
273 if (nodep) {
274 ipc_answer_5(rid, EOK,
275 tmpfs_reg.fs_handle, dev_handle,
276 TMPFS_GET_INDEX(nodep), 0,
277 TMPFS_GET_LNKCNT(nodep));
278 } else {
279 ipc_answer_0(rid, ENOSPC);
280 }
281 return;
282 }
283 ipc_answer_0(rid, ENOENT);
284 return;
285 }
286
287 /* descend one level */
288 dcur = dtmp;
289 dtmp = dtmp->child;
290 }
291
292 /* handle miss: excessive components */
293 if (!dtmp && next <= last) {
294 if (lflag & L_CREATE) {
295 if (dcur->type != TMPFS_DIRECTORY) {
296 ipc_answer_0(rid, ENOTDIR);
297 return;
298 }
299
300 /* collect next component */
301 while (next <= last) {
302 if (PLB_GET_CHAR(next) == '/') {
303 /* more than one component */
304 ipc_answer_0(rid, ENOENT);
305 return;
306 }
307 if (len + 1 == NAME_MAX) {
308 /* component length overflow */
309 ipc_answer_0(rid, ENAMETOOLONG);
310 return;
311 }
312 component[len++] = PLB_GET_CHAR(next);
313 next++; /* process next character */
314 }
315 assert(len);
316 component[len] = '\0';
317 len = 0;
318
319 void *nodep = create_node(dcur, component, lflag);
320 if (nodep) {
321 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
322 dev_handle, TMPFS_GET_INDEX(nodep), 0,
323 TMPFS_GET_LNKCNT(nodep));
324 } else {
325 ipc_answer_0(rid, ENOSPC);
326 }
327 return;
328 }
329 ipc_answer_0(rid, ENOENT);
330 return;
331 }
332
333 /* handle hit */
334 if (lflag & L_DESTROY) {
335 unsigned old_lnkcnt = TMPFS_GET_LNKCNT(dcur);
336 int res = destroy_component(dcur);
337 ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
338 dev_handle, dcur->index, dcur->size, old_lnkcnt);
339 return;
340 }
341 if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
342 ipc_answer_0(rid, EEXIST);
343 return;
344 }
345 if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
346 ipc_answer_0(rid, EISDIR);
347 return;
348 }
349 if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
350 ipc_answer_0(rid, ENOTDIR);
351 return;
352 }
353
354 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
355 dcur->size, TMPFS_GET_LNKCNT(dcur));
356}
357
358void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
359{
360 int dev_handle = IPC_GET_ARG1(*request);
361 unsigned long index = IPC_GET_ARG2(*request);
362 off_t pos = IPC_GET_ARG3(*request);
363
364 /*
365 * Lookup the respective dentry.
366 */
367 link_t *hlp;
368 hlp = hash_table_find(&dentries, &index);
369 if (!hlp) {
370 ipc_answer_0(rid, ENOENT);
371 return;
372 }
373 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
374 dh_link);
375
376 /*
377 * Receive the read request.
378 */
379 ipc_callid_t callid;
380 size_t len;
381 if (!ipc_data_read_receive(&callid, &len)) {
382 ipc_answer_0(callid, EINVAL);
383 ipc_answer_0(rid, EINVAL);
384 return;
385 }
386
387 size_t bytes;
388 if (dentry->type == TMPFS_FILE) {
389 bytes = max(0, min(dentry->size - pos, len));
390 (void) ipc_data_read_finalize(callid, dentry->data + pos,
391 bytes);
392 } else {
393 int i;
394 tmpfs_dentry_t *cur;
395
396 assert(dentry->type == TMPFS_DIRECTORY);
397
398 /*
399 * Yes, we really use O(n) algorithm here.
400 * If it bothers someone, it could be fixed by introducing a
401 * hash table.
402 */
403 for (i = 0, cur = dentry->child; i < pos && cur; i++,
404 cur = cur->sibling)
405 ;
406
407 if (!cur) {
408 ipc_answer_0(callid, ENOENT);
409 ipc_answer_1(rid, ENOENT, 0);
410 return;
411 }
412
413 (void) ipc_data_read_finalize(callid, cur->name,
414 strlen(cur->name) + 1);
415 bytes = 1;
416 }
417
418 /*
419 * Answer the VFS_READ call.
420 */
421 ipc_answer_1(rid, EOK, bytes);
422}
423
424void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
425{
426 int dev_handle = IPC_GET_ARG1(*request);
427 unsigned long index = IPC_GET_ARG2(*request);
428 off_t pos = IPC_GET_ARG3(*request);
429
430 /*
431 * Lookup the respective dentry.
432 */
433 link_t *hlp;
434 hlp = hash_table_find(&dentries, &index);
435 if (!hlp) {
436 ipc_answer_0(rid, ENOENT);
437 return;
438 }
439 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
440 dh_link);
441
442 /*
443 * Receive the write request.
444 */
445 ipc_callid_t callid;
446 size_t len;
447 if (!ipc_data_write_receive(&callid, &len)) {
448 ipc_answer_0(callid, EINVAL);
449 ipc_answer_0(rid, EINVAL);
450 return;
451 }
452
453 /*
454 * Check whether the file needs to grow.
455 */
456 if (pos + len <= dentry->size) {
457 /* The file size is not changing. */
458 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
459 ipc_answer_2(rid, EOK, len, dentry->size);
460 return;
461 }
462 size_t delta = (pos + len) - dentry->size;
463 /*
464 * At this point, we are deliberately extremely straightforward and
465 * simply realloc the contents of the file on every write that grows the
466 * file. In the end, the situation might not be as bad as it may look:
467 * our heap allocator can save us and just grow the block whenever
468 * possible.
469 */
470 void *newdata = realloc(dentry->data, dentry->size + delta);
471 if (!newdata) {
472 ipc_answer_0(callid, ENOMEM);
473 ipc_answer_2(rid, EOK, 0, dentry->size);
474 return;
475 }
476 /* Clear any newly allocated memory in order to emulate gaps. */
477 memset(newdata + dentry->size, 0, delta);
478 dentry->size += delta;
479 dentry->data = newdata;
480 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
481 ipc_answer_2(rid, EOK, len, dentry->size);
482}
483
484void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
485{
486 int dev_handle = IPC_GET_ARG1(*request);
487 unsigned long index = IPC_GET_ARG2(*request);
488 size_t size = IPC_GET_ARG3(*request);
489
490 /*
491 * Lookup the respective dentry.
492 */
493 link_t *hlp;
494 hlp = hash_table_find(&dentries, &index);
495 if (!hlp) {
496 ipc_answer_0(rid, ENOENT);
497 return;
498 }
499 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
500 dh_link);
501
502 if (size == dentry->size) {
503 ipc_answer_0(rid, EOK);
504 return;
505 }
506
507 void *newdata = realloc(dentry->data, size);
508 if (!newdata) {
509 ipc_answer_0(rid, ENOMEM);
510 return;
511 }
512 if (size > dentry->size) {
513 size_t delta = size - dentry->size;
514 memset(newdata + dentry->size, 0, delta);
515 }
516 dentry->size = size;
517 dentry->data = newdata;
518 ipc_answer_0(rid, EOK);
519}
520
521void tmpfs_free(ipc_callid_t rid, ipc_call_t *request)
522{
523 int dev_handle = IPC_GET_ARG1(*request);
524 unsigned long index = IPC_GET_ARG2(*request);
525
526 link_t *hlp;
527 hlp = hash_table_find(&dentries, &index);
528 if (!hlp) {
529 ipc_answer_0(rid, ENOENT);
530 return;
531 }
532 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
533 dh_link);
534
535 assert(!dentry->parent);
536 assert(!dentry->child);
537 assert(!dentry->sibling);
538
539 hash_table_remove(&dentries, &index, 1);
540
541 if (dentry->type == TMPFS_FILE)
542 free(dentry->data);
543 free(dentry->name);
544 free(dentry);
545
546 ipc_answer_0(rid, EOK);
547}
548
549/**
550 * @}
551 */
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