source: mainline/uspace/srv/fs/tmpfs/tmpfs_ops.c@ b5553a2

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since b5553a2 was b5553a2, checked in by Jakub Jermar <jakub@…>, 17 years ago

Introduce the notion of VFS node link counts.
  • Property mode set to 100644
File size: 12.0 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 return EPERM;
191}
192
193void tmpfs_lookup(ipc_callid_t rid, ipc_call_t *request)
194{
195 unsigned next = IPC_GET_ARG1(*request);
196 unsigned last = IPC_GET_ARG2(*request);
197 int dev_handle = IPC_GET_ARG3(*request);
198 int lflag = IPC_GET_ARG4(*request);
199
200 if (last < next)
201 last += PLB_SIZE;
202
203 /*
204 * Initialize TMPFS.
205 */
206 if (!root && !tmpfs_init()) {
207 ipc_answer_0(rid, ENOMEM);
208 return;
209 }
210
211 tmpfs_dentry_t *dtmp = root->child;
212 tmpfs_dentry_t *dcur = root;
213
214 if (PLB_GET_CHAR(next) == '/')
215 next++; /* eat slash */
216
217 char component[NAME_MAX + 1];
218 int len = 0;
219 while (dtmp && next <= last) {
220
221 /* collect the component */
222 if (PLB_GET_CHAR(next) != '/') {
223 if (len + 1 == NAME_MAX) {
224 /* comopnent length overflow */
225 ipc_answer_0(rid, ENAMETOOLONG);
226 return;
227 }
228 component[len++] = PLB_GET_CHAR(next);
229 next++; /* process next character */
230 if (next <= last)
231 continue;
232 }
233
234 assert(len);
235 component[len] = '\0';
236 next++; /* eat slash */
237 len = 0;
238
239 /* match the component */
240 while (dtmp && !match_component(dtmp, component))
241 dtmp = dtmp->sibling;
242
243 /* handle miss: match amongst siblings */
244 if (!dtmp) {
245 if ((next > last) && (lflag & L_CREATE)) {
246 /* no components left and L_CREATE specified */
247 if (dcur->type != TMPFS_DIRECTORY) {
248 ipc_answer_0(rid, ENOTDIR);
249 return;
250 }
251 void *nodep = create_node(dcur,
252 component, lflag);
253 if (nodep) {
254 ipc_answer_5(rid, EOK,
255 tmpfs_reg.fs_handle, dev_handle,
256 TMPFS_GET_INDEX(nodep), 0,
257 TMPFS_GET_LNKCNT(nodep));
258 } else {
259 ipc_answer_0(rid, ENOSPC);
260 }
261 return;
262 }
263 ipc_answer_0(rid, ENOENT);
264 return;
265 }
266
267 /* descend one level */
268 dcur = dtmp;
269 dtmp = dtmp->child;
270 }
271
272 /* handle miss: excessive components */
273 if (!dtmp && next <= last) {
274 if (lflag & L_CREATE) {
275 if (dcur->type != TMPFS_DIRECTORY) {
276 ipc_answer_0(rid, ENOTDIR);
277 return;
278 }
279
280 /* collect next component */
281 while (next <= last) {
282 if (PLB_GET_CHAR(next) == '/') {
283 /* more than one component */
284 ipc_answer_0(rid, ENOENT);
285 return;
286 }
287 if (len + 1 == NAME_MAX) {
288 /* component length overflow */
289 ipc_answer_0(rid, ENAMETOOLONG);
290 return;
291 }
292 component[len++] = PLB_GET_CHAR(next);
293 next++; /* process next character */
294 }
295 assert(len);
296 component[len] = '\0';
297 len = 0;
298
299 void *nodep = create_node(dcur, component, lflag);
300 if (nodep) {
301 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle,
302 dev_handle, TMPFS_GET_INDEX(nodep), 0,
303 TMPFS_GET_LNKCNT(nodep));
304 } else {
305 ipc_answer_0(rid, ENOSPC);
306 }
307 return;
308 }
309 ipc_answer_0(rid, ENOENT);
310 return;
311 }
312
313 /* handle hit */
314 if (lflag & L_DESTROY) {
315 int res = destroy_component(dcur);
316 ipc_answer_0(rid, res);
317 return;
318 }
319 if ((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) {
320 ipc_answer_0(rid, EEXIST);
321 return;
322 }
323 if ((lflag & L_FILE) && (dcur->type != TMPFS_FILE)) {
324 ipc_answer_0(rid, EISDIR);
325 return;
326 }
327 if ((lflag & L_DIRECTORY) && (dcur->type != TMPFS_DIRECTORY)) {
328 ipc_answer_0(rid, ENOTDIR);
329 return;
330 }
331
332 ipc_answer_5(rid, EOK, tmpfs_reg.fs_handle, dev_handle, dcur->index,
333 dcur->size, TMPFS_GET_LNKCNT(dcur));
334}
335
336void tmpfs_read(ipc_callid_t rid, ipc_call_t *request)
337{
338 int dev_handle = IPC_GET_ARG1(*request);
339 unsigned long index = IPC_GET_ARG2(*request);
340 off_t pos = IPC_GET_ARG3(*request);
341
342 /*
343 * Lookup the respective dentry.
344 */
345 link_t *hlp;
346 hlp = hash_table_find(&dentries, &index);
347 if (!hlp) {
348 ipc_answer_0(rid, ENOENT);
349 return;
350 }
351 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
352 dh_link);
353
354 /*
355 * Receive the read request.
356 */
357 ipc_callid_t callid;
358 size_t len;
359 if (!ipc_data_read_receive(&callid, &len)) {
360 ipc_answer_0(callid, EINVAL);
361 ipc_answer_0(rid, EINVAL);
362 return;
363 }
364
365 size_t bytes;
366 if (dentry->type == TMPFS_FILE) {
367 bytes = max(0, min(dentry->size - pos, len));
368 (void) ipc_data_read_finalize(callid, dentry->data + pos,
369 bytes);
370 } else {
371 int i;
372 tmpfs_dentry_t *cur = dentry->child;
373
374 assert(dentry->type == TMPFS_DIRECTORY);
375
376 /*
377 * Yes, we really use O(n) algorithm here.
378 * If it bothers someone, it could be fixed by introducing a
379 * hash table.
380 */
381 for (i = 0, cur = dentry->child; i < pos && cur; i++,
382 cur = cur->sibling)
383 ;
384
385 if (!cur) {
386 ipc_answer_0(callid, ENOENT);
387 ipc_answer_1(rid, ENOENT, 0);
388 return;
389 }
390
391 (void) ipc_data_read_finalize(callid, cur->name,
392 strlen(cur->name) + 1);
393 bytes = 1;
394 }
395
396 /*
397 * Answer the VFS_READ call.
398 */
399 ipc_answer_1(rid, EOK, bytes);
400}
401
402void tmpfs_write(ipc_callid_t rid, ipc_call_t *request)
403{
404 int dev_handle = IPC_GET_ARG1(*request);
405 unsigned long index = IPC_GET_ARG2(*request);
406 off_t pos = IPC_GET_ARG3(*request);
407
408 /*
409 * Lookup the respective dentry.
410 */
411 link_t *hlp;
412 hlp = hash_table_find(&dentries, &index);
413 if (!hlp) {
414 ipc_answer_0(rid, ENOENT);
415 return;
416 }
417 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
418 dh_link);
419
420 /*
421 * Receive the write request.
422 */
423 ipc_callid_t callid;
424 size_t len;
425 if (!ipc_data_write_receive(&callid, &len)) {
426 ipc_answer_0(callid, EINVAL);
427 ipc_answer_0(rid, EINVAL);
428 return;
429 }
430
431 /*
432 * Check whether the file needs to grow.
433 */
434 if (pos + len <= dentry->size) {
435 /* The file size is not changing. */
436 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
437 ipc_answer_2(rid, EOK, len, dentry->size);
438 return;
439 }
440 size_t delta = (pos + len) - dentry->size;
441 /*
442 * At this point, we are deliberately extremely straightforward and
443 * simply realloc the contents of the file on every write that grows the
444 * file. In the end, the situation might not be as bad as it may look:
445 * our heap allocator can save us and just grow the block whenever
446 * possible.
447 */
448 void *newdata = realloc(dentry->data, dentry->size + delta);
449 if (!newdata) {
450 ipc_answer_0(callid, ENOMEM);
451 ipc_answer_2(rid, EOK, 0, dentry->size);
452 return;
453 }
454 /* Clear any newly allocated memory in order to emulate gaps. */
455 memset(newdata + dentry->size, 0, delta);
456 dentry->size += delta;
457 dentry->data = newdata;
458 (void) ipc_data_write_finalize(callid, dentry->data + pos, len);
459 ipc_answer_2(rid, EOK, len, dentry->size);
460}
461
462void tmpfs_truncate(ipc_callid_t rid, ipc_call_t *request)
463{
464 int dev_handle = IPC_GET_ARG1(*request);
465 unsigned long index = IPC_GET_ARG2(*request);
466 size_t size = IPC_GET_ARG3(*request);
467
468 /*
469 * Lookup the respective dentry.
470 */
471 link_t *hlp;
472 hlp = hash_table_find(&dentries, &index);
473 if (!hlp) {
474 ipc_answer_0(rid, ENOENT);
475 return;
476 }
477 tmpfs_dentry_t *dentry = hash_table_get_instance(hlp, tmpfs_dentry_t,
478 dh_link);
479
480 if (size == dentry->size) {
481 ipc_answer_0(rid, EOK);
482 return;
483 }
484
485 void *newdata = realloc(dentry->data, size);
486 if (!newdata) {
487 ipc_answer_0(rid, ENOMEM);
488 return;
489 }
490 if (size > dentry->size) {
491 size_t delta = size - dentry->size;
492 memset(newdata + dentry->size, 0, delta);
493 }
494 dentry->size = size;
495 dentry->data = newdata;
496 ipc_answer_0(rid, EOK);
497}
498
499/**
500 * @}
501 */
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