source: mainline/uspace/srv/fs/tmpfs/tmpfs_ops.c@ f15cf1a6

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since f15cf1a6 was f15cf1a6, checked in by Jakub Jermar <jakub@…>, 17 years ago

Support for rmdir(), unlink() and the respective VFS operations.
  • 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
208 return EOK;
209}
210
211void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
212{
213 unsigned next = IPC_GET_ARG1(*request);
214 unsigned last = IPC_GET_ARG2(*request);
215 int dev_handle = IPC_GET_ARG3(*request);
216 int lflag = IPC_GET_ARG4(*request);
217
218 if (last < next)
219 last += PLB_SIZE;
220
221 /*
222 * Initialize TMPFS.
223 */
224 if (!root && !tmpfs_init()) {
225 ipc_answer_0(rid, ENOMEM);
226 return;
227 }
228
229 tmpfs_dentry_t *dtmp = root->child;
230 tmpfs_dentry_t *dcur = root;
231
232 if (PLB_GET_CHAR(next) == '/')
233 next++; /* eat slash */
234
235 char component[NAME_MAX + 1];
236 int len = 0;
237 while (dtmp && next <= last) {
238
239 /* collect the component */
240 if (PLB_GET_CHAR(next) != '/') {
241 if (len + 1 == NAME_MAX) {
242 /* comopnent length overflow */
243 ipc_answer_0(rid, ENAMETOOLONG);
244 return;
245 }
246 component[len++] = PLB_GET_CHAR(next);
247 next++; /* process next character */
248 if (next <= last)
249 continue;
250 }
251
252 assert(len);
253 component[len] = '\0';
254 next++; /* eat slash */
255 len = 0;
256
257 /* match the component */
258 while (dtmp && !match_component(dtmp, component))
259 dtmp = dtmp->sibling;
260
261 /* handle miss: match amongst siblings */
262 if (!dtmp) {
263 if ((next > last) && (lflag & L_CREATE)) {
264 /* no components left and L_CREATE specified */
265 if (dcur->type != TMPFS_DIRECTORY) {
266 ipc_answer_0(rid, ENOTDIR);
267 return;
268 }
269 void *nodep = create_node(dcur,
270 component, lflag);
271 if (nodep) {
272 ipc_answer_5(rid, EOK,
273 tmpfs_reg.fs_handle, dev_handle,
274 TMPFS_GET_INDEX(nodep), 0,
275 TMPFS_GET_LNKCNT(nodep));
276 } else {
277 ipc_answer_0(rid, ENOSPC);
278 }
279 return;
280 }
281 ipc_answer_0(rid, ENOENT);
282 return;
283 }
284
285 /* descend one level */
286 dcur = dtmp;
287 dtmp = dtmp->child;
288 }
289
290 /* handle miss: excessive components */
291 if (!dtmp && next <= last) {
292 if (lflag & L_CREATE) {
293 if (dcur->type != TMPFS_DIRECTORY) {
294 ipc_answer_0(rid, ENOTDIR);
295 return;
296 }
297
298 /* collect next component */
299 while (next <= last) {
300 if (PLB_GET_CHAR(next) == '/') {
301 /* more than one component */
302 ipc_answer_0(rid, ENOENT);
303 return;
304 }
305 if (len + 1 == NAME_MAX) {
306 /* component length overflow */
307 ipc_answer_0(rid, ENAMETOOLONG);
308 return;
309 }
310 component[len++] = PLB_GET_CHAR(next);
311 next++; /* process next character */
312 }
313 assert(len);
314 component[len] = '\0';
315 len = 0;
316
317 void *nodep = create_node(dcur, component, lflag);
318 if (nodep) {
319 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
320 dev_handle, TMPFS_GET_INDEX(nodep), 0,
321 TMPFS_GET_LNKCNT(nodep));
322 } else {
323 ipc_answer_0(rid, ENOSPC);
324 }
325 return;
326 }
327 ipc_answer_0(rid, ENOENT);
328 return;
329 }
330
331 /* handle hit */
332 if (lflag & L_DESTROY) {
333 unsigned old_lnkcnt = TMPFS_GET_LNKCNT(dcur);
334 int res = destroy_component(dcur);
335 ipc_answer_5(rid, (ipcarg_t)res, tmpfs_reg.fs_handle,
336 dev_handle, dcur->index, dcur->size, old_lnkcnt);
337 return;
338 }
339 if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
340 ipc_answer_0(rid, EEXIST);
341 return;
342 }
343 if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
344 ipc_answer_0(rid, EISDIR);
345 return;
346 }
347 if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
348 ipc_answer_0(rid, ENOTDIR);
349 return;
350 }
351
352 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
353 dcur->size, TMPFS_GET_LNKCNT(dcur));
354}
355
356void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
357{
358 int dev_handle = IPC_GET_ARG1(*request);
359 unsigned long index = IPC_GET_ARG2(*request);
360 off_t pos = IPC_GET_ARG3(*request);
361
362 /*
363 * Lookup the respective dentry.
364 */
365 link_t *hlp;
366 hlp = hash_table_find(&dentries, &index);
367 if (!hlp) {
368 ipc_answer_0(rid, ENOENT);
369 return;
370 }
371 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
372 dh_link);
373
374 /*
375 * Receive the read request.
376 */
377 ipc_callid_t callid;
378 size_t len;
379 if (!ipc_data_read_receive(&callid, &len)) {
380 ipc_answer_0(callid, EINVAL);
381 ipc_answer_0(rid, EINVAL);
382 return;
383 }
384
385 size_t bytes;
386 if (dentry->type == TMPFS_FILE) {
387 bytes = max(0, min(dentry->size - pos, len));
388 (void) ipc_data_read_finalize(callid, dentry->data + pos,
389 bytes);
390 } else {
391 int i;
392 tmpfs_dentry_t *cur = dentry->child;
393
394 assert(dentry->type == TMPFS_DIRECTORY);
395
396 /*
397 * Yes, we really use O(n) algorithm here.
398 * If it bothers someone, it could be fixed by introducing a
399 * hash table.
400 */
401 for (i = 0, cur = dentry->child; i < pos && cur; i++,
402 cur = cur->sibling)
403 ;
404
405 if (!cur) {
406 ipc_answer_0(callid, ENOENT);
407 ipc_answer_1(rid, ENOENT, 0);
408 return;
409 }
410
411 (void) ipc_data_read_finalize(callid, cur->name,
412 strlen(cur->name) + 1);
413 bytes = 1;
414 }
415
416 /*
417 * Answer the VFS_READ call.
418 */
419 ipc_answer_1(rid, EOK, bytes);
420}
421
422void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
423{
424 int dev_handle = IPC_GET_ARG1(*request);
425 unsigned long index = IPC_GET_ARG2(*request);
426 off_t pos = IPC_GET_ARG3(*request);
427
428 /*
429 * Lookup the respective dentry.
430 */
431 link_t *hlp;
432 hlp = hash_table_find(&dentries, &index);
433 if (!hlp) {
434 ipc_answer_0(rid, ENOENT);
435 return;
436 }
437 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
438 dh_link);
439
440 /*
441 * Receive the write request.
442 */
443 ipc_callid_t callid;
444 size_t len;
445 if (!ipc_data_write_receive(&callid, &len)) {
446 ipc_answer_0(callid, EINVAL);
447 ipc_answer_0(rid, EINVAL);
448 return;
449 }
450
451 /*
452 * Check whether the file needs to grow.
453 */
454 if (pos + len <= dentry->size) {
455 /* The file size is not changing. */
456 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
457 ipc_answer_2(rid, EOK, len, dentry->size);
458 return;
459 }
460 size_t delta = (pos + len) - dentry->size;
461 /*
462 * At this point, we are deliberately extremely straightforward and
463 * simply realloc the contents of the file on every write that grows the
464 * file. In the end, the situation might not be as bad as it may look:
465 * our heap allocator can save us and just grow the block whenever
466 * possible.
467 */
468 void *newdata = realloc(dentry->data, dentry->size + delta);
469 if (!newdata) {
470 ipc_answer_0(callid, ENOMEM);
471 ipc_answer_2(rid, EOK, 0, dentry->size);
472 return;
473 }
474 /* Clear any newly allocated memory in order to emulate gaps. */
475 memset(newdata + dentry->size, 0, delta);
476 dentry->size += delta;
477 dentry->data = newdata;
478 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
479 ipc_answer_2(rid, EOK, len, dentry->size);
480}
481
482void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
483{
484 int dev_handle = IPC_GET_ARG1(*request);
485 unsigned long index = IPC_GET_ARG2(*request);
486 size_t size = IPC_GET_ARG3(*request);
487
488 /*
489 * Lookup the respective dentry.
490 */
491 link_t *hlp;
492 hlp = hash_table_find(&dentries, &index);
493 if (!hlp) {
494 ipc_answer_0(rid, ENOENT);
495 return;
496 }
497 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
498 dh_link);
499
500 if (size == dentry->size) {
501 ipc_answer_0(rid, EOK);
502 return;
503 }
504
505 void *newdata = realloc(dentry->data, size);
506 if (!newdata) {
507 ipc_answer_0(rid, ENOMEM);
508 return;
509 }
510 if (size > dentry->size) {
511 size_t delta = size - dentry->size;
512 memset(newdata + dentry->size, 0, delta);
513 }
514 dentry->size = size;
515 dentry->data = newdata;
516 ipc_answer_0(rid, EOK);
517}
518
519void tmpfs_free(ipc_callid_t rid, ipc_call_t *request)
520{
521 int dev_handle = IPC_GET_ARG1(*request);
522 unsigned long index = IPC_GET_ARG2(*request);
523
524 link_t *hlp;
525 hlp = hash_table_find(&dentries, &index);
526 if (!hlp) {
527 ipc_answer_0(rid, ENOENT);
528 return;
529 }
530 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
531 dh_link);
532
533 assert(!dentry->parent);
534 assert(!dentry->child);
535 assert(!dentry->sibling);
536
537 hash_table_remove(&dentries, &index, 1);
538
539 if (dentry->type == TMPFS_FILE)
540 free(dentry->data);
541 free(dentry->name);
542 free(dentry);
543
544 ipc_answer_0(rid, EOK);
545}
546
547/**
548 * @}
549 */
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