source: mainline/uspace/srv/fs/fat/fat_ops.c@ 32fb10ed

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 32fb10ed was 32fb10ed, checked in by Jakub Jermar <jakub@…>, 18 years ago

Add fat_has_children(). Alse assume that fat_block_get() can never return NULL.
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File size: 9.9 KB
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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 fat_ops.c
35 * @brief Implementation of VFS operations for the FAT file system server.
36 */
37
38#include "fat.h"
39#include "../../vfs/vfs.h"
40#include <libfs.h>
41#include <ipc/ipc.h>
42#include <async.h>
43#include <errno.h>
44#include <string.h>
45#include <byteorder.h>
46#include <libadt/hash_table.h>
47#include <libadt/list.h>
48#include <assert.h>
49
50#define BS_BLOCK 0
51
52#define FIN_KEY_DEV_HANDLE 0
53#define FIN_KEY_INDEX 1
54
55/** Hash table of FAT in-core nodes. */
56hash_table_t fin_hash;
57
58/** List of free FAT in-core nodes. */
59link_t ffn_head;
60
61#define FAT_NAME_LEN 8
62#define FAT_EXT_LEN 3
63
64#define FAT_PAD ' '
65
66#define FAT_DENTRY_UNUSED 0x00
67#define FAT_DENTRY_E5_ESC 0x05
68#define FAT_DENTRY_DOT 0x2e
69#define FAT_DENTRY_ERASED 0xe5
70
71static void dentry_name_canonify(fat_dentry_t *d, char *buf)
72{
73 int i;
74
75 for (i = 0; i < FAT_NAME_LEN; i++) {
76 if (d->name[i] == FAT_PAD) {
77 buf++;
78 break;
79 }
80 if (d->name[i] == FAT_DENTRY_E5_ESC)
81 *buf++ = 0xe5;
82 else
83 *buf++ = d->name[i];
84 }
85 if (d->ext[0] != FAT_PAD)
86 *buf++ = '.';
87 for (i = 0; i < FAT_EXT_LEN; i++) {
88 if (d->ext[i] == FAT_PAD) {
89 *buf = '\0';
90 return;
91 }
92 if (d->ext[i] == FAT_DENTRY_E5_ESC)
93 *buf++ = 0xe5;
94 else
95 *buf++ = d->ext[i];
96 }
97}
98
99/* TODO and also move somewhere else */
100typedef struct {
101 void *data;
102} block_t;
103
104static block_t *block_get(dev_handle_t dev_handle, off_t offset)
105{
106 return NULL; /* TODO */
107}
108
109static block_t *fat_block_get(dev_handle_t dev_handle, fs_index_t index,
110 off_t offset) {
111 return NULL; /* TODO */
112}
113
114static void block_put(block_t *block)
115{
116 /* TODO */
117}
118
119static void fat_node_initialize(fat_node_t *node)
120{
121 node->type = 0;
122 node->index = 0;
123 node->pindex = 0;
124 node->dev_handle = 0;
125 link_initialize(&node->fin_link);
126 link_initialize(&node->ffn_link);
127 node->size = 0;
128 node->lnkcnt = 0;
129 node->refcnt = 0;
130 node->dirty = false;
131}
132
133static uint16_t fat_bps_get(dev_handle_t dev_handle)
134{
135 block_t *bb;
136 uint16_t bps;
137
138 bb = block_get(dev_handle, BS_BLOCK);
139 assert(bb != NULL);
140 bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);
141 block_put(bb);
142
143 return bps;
144}
145
146typedef enum {
147 FAT_DENTRY_SKIP,
148 FAT_DENTRY_LAST,
149 FAT_DENTRY_VALID
150} fat_dentry_clsf_t;
151
152static fat_dentry_clsf_t fat_classify_dentry(fat_dentry_t *d)
153{
154 if (d->attr & FAT_ATTR_VOLLABEL) {
155 /* volume label entry */
156 return FAT_DENTRY_SKIP;
157 }
158 if (d->name[0] == FAT_DENTRY_ERASED) {
159 /* not-currently-used entry */
160 return FAT_DENTRY_SKIP;
161 }
162 if (d->name[0] == FAT_DENTRY_UNUSED) {
163 /* never used entry */
164 return FAT_DENTRY_LAST;
165 }
166 if (d->name[0] == FAT_DENTRY_DOT) {
167 /*
168 * Most likely '.' or '..'.
169 * It cannot occur in a regular file name.
170 */
171 return FAT_DENTRY_SKIP;
172 }
173 return FAT_DENTRY_VALID;
174}
175
176static void fat_sync_node(fat_node_t *node)
177{
178 /* TODO */
179}
180
181/** Instantiate a FAT in-core node.
182 *
183 * FAT stores the info necessary for instantiation of a node in the parent of
184 * that node. This design necessitated the addition of the parent node index
185 * parameter to this otherwise generic libfs API.
186 */
187static void *
188fat_node_get(dev_handle_t dev_handle, fs_index_t index, fs_index_t pindex)
189{
190 link_t *lnk;
191 fat_node_t *node = NULL;
192 block_t *b;
193 unsigned bps;
194 unsigned dps;
195 fat_dentry_t *d;
196 unsigned i, j;
197
198 unsigned long key[] = {
199 [FIN_KEY_DEV_HANDLE] = dev_handle,
200 [FIN_KEY_INDEX] = index
201 };
202
203 lnk = hash_table_find(&fin_hash, key);
204 if (lnk) {
205 /*
206 * The in-core node was found in the hash table.
207 */
208 node = hash_table_get_instance(lnk, fat_node_t, fin_link);
209 if (!node->refcnt++)
210 list_remove(&node->ffn_link);
211 return (void *) node;
212 }
213
214 bps = fat_bps_get(dev_handle);
215 dps = bps / sizeof(fat_dentry_t);
216
217 if (!list_empty(&ffn_head)) {
218 /*
219 * We are going to reuse a node from the free list.
220 */
221 lnk = ffn_head.next;
222 list_remove(lnk);
223 node = list_get_instance(lnk, fat_node_t, ffn_link);
224 assert(!node->refcnt);
225 if (node->dirty)
226 fat_sync_node(node);
227 key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
228 key[FIN_KEY_INDEX] = node->index;
229 hash_table_remove(&fin_hash, key, sizeof(key)/sizeof(*key));
230 } else {
231 /*
232 * We need to allocate a new node.
233 */
234 node = malloc(sizeof(fat_node_t));
235 if (!node)
236 return NULL;
237 }
238 fat_node_initialize(node);
239 node->refcnt++;
240 node->lnkcnt++;
241 node->dev_handle = dev_handle;
242 node->index = index;
243 node->pindex = pindex;
244
245 /*
246 * Because of the design of the FAT file system, we have no clue about
247 * how big (i.e. how many directory entries it contains) is the parent
248 * of the node we are trying to instantiate. However, we know that it
249 * must contain a directory entry for our node of interest. We simply
250 * scan the parent until we find it.
251 */
252 for (i = 0; ; i++) {
253 b = fat_block_get(node->dev_handle, node->pindex, i);
254 for (j = 0; j < dps; j++) {
255 d = ((fat_dentry_t *)b->data) + j;
256 if (d->firstc == node->index)
257 goto found;
258 }
259 block_put(b);
260 }
261
262found:
263 if (!(d->attr & (FAT_ATTR_SUBDIR | FAT_ATTR_VOLLABEL)))
264 node->type = FAT_FILE;
265 if ((d->attr & FAT_ATTR_SUBDIR) || !index)
266 node->type = FAT_DIRECTORY;
267 assert((node->type == FAT_FILE) || (node->type == FAT_DIRECTORY));
268
269 node->size = uint32_t_le2host(d->size);
270 block_put(b);
271
272 key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
273 key[FIN_KEY_INDEX] = node->index;
274 hash_table_insert(&fin_hash, key, &node->fin_link);
275
276 return node;
277}
278
279static void *fat_match(void *prnt, const char *component)
280{
281 fat_node_t *parentp = (fat_node_t *)prnt;
282 char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
283 unsigned i, j;
284 unsigned bps; /* bytes per sector */
285 unsigned dps; /* dentries per sector */
286 unsigned blocks;
287 fat_dentry_t *d;
288 block_t *b;
289
290 bps = fat_bps_get(parentp->dev_handle);
291 dps = bps / sizeof(fat_dentry_t);
292 blocks = parentp->size / bps + (parentp->size % bps != 0);
293 for (i = 0; i < blocks; i++) {
294 unsigned dentries;
295
296 b = fat_block_get(parentp->dev_handle, parentp->index, i);
297 dentries = (i == blocks - 1) ?
298 parentp->size % sizeof(fat_dentry_t) :
299 dps;
300 for (j = 0; j < dentries; j++) {
301 d = ((fat_dentry_t *)b->data) + j;
302 switch (fat_classify_dentry(d)) {
303 case FAT_DENTRY_SKIP:
304 continue;
305 case FAT_DENTRY_LAST:
306 block_put(b);
307 return NULL;
308 default:
309 case FAT_DENTRY_VALID:
310 dentry_name_canonify(d, name);
311 break;
312 }
313 if (strcmp(name, component) == 0) {
314 /* hit */
315 void *node = fat_node_get(parentp->dev_handle,
316 (fs_index_t)uint16_t_le2host(d->firstc),
317 parentp->index);
318 block_put(b);
319 return node;
320 }
321 }
322 block_put(b);
323 }
324
325 return NULL;
326}
327
328static fs_index_t fat_index_get(void *node)
329{
330 fat_node_t *fnodep = (fat_node_t *)node;
331 if (!fnodep)
332 return 0;
333 return fnodep->index;
334}
335
336static size_t fat_size_get(void *node)
337{
338 return ((fat_node_t *)node)->size;
339}
340
341static unsigned fat_lnkcnt_get(void *node)
342{
343 return ((fat_node_t *)node)->lnkcnt;
344}
345
346static bool fat_has_children(void *node)
347{
348 fat_node_t *nodep = (fat_node_t *)node;
349 unsigned bps;
350 unsigned dps;
351 unsigned blocks;
352 block_t *b;
353 unsigned i, j;
354
355 if (nodep->type != FAT_DIRECTORY)
356 return false;
357
358 bps = fat_bps_get(nodep->dev_handle);
359 dps = bps / sizeof(fat_dentry_t);
360
361 blocks = nodep->size / bps + (nodep->size % bps != 0);
362
363 for (i = 0; i < blocks; i++) {
364 unsigned dentries;
365 fat_dentry_t *d;
366
367 b = fat_block_get(nodep->dev_handle, nodep->index, i);
368 dentries = (i == blocks - 1) ?
369 nodep->size % sizeof(fat_dentry_t) :
370 dps;
371 for (j = 0; j < dentries; j++) {
372 d = ((fat_dentry_t *)b->data) + j;
373 switch (fat_classify_dentry(d)) {
374 case FAT_DENTRY_SKIP:
375 continue;
376 case FAT_DENTRY_LAST:
377 block_put(b);
378 return false;
379 default:
380 case FAT_DENTRY_VALID:
381 block_put(b);
382 return true;
383 }
384 block_put(b);
385 return true;
386 }
387 block_put(b);
388 }
389
390 return false;
391}
392
393static void *fat_root_get(dev_handle_t dev_handle)
394{
395 return fat_node_get(dev_handle, 0, 0);
396}
397
398static char fat_plb_get_char(unsigned pos)
399{
400 return fat_reg.plb_ro[pos % PLB_SIZE];
401}
402
403static bool fat_is_directory(void *node)
404{
405 return ((fat_node_t *)node)->type == FAT_DIRECTORY;
406}
407
408static bool fat_is_file(void *node)
409{
410 return ((fat_node_t *)node)->type == FAT_FILE;
411}
412
413/** libfs operations */
414libfs_ops_t fat_libfs_ops = {
415 .match = fat_match,
416 .node_get = fat_node_get,
417 .create = NULL,
418 .destroy = NULL,
419 .link = NULL,
420 .unlink = NULL,
421 .index_get = fat_index_get,
422 .size_get = fat_size_get,
423 .lnkcnt_get = fat_lnkcnt_get,
424 .has_children = fat_has_children,
425 .root_get = fat_root_get,
426 .plb_get_char = fat_plb_get_char,
427 .is_directory = fat_is_directory,
428 .is_file = fat_is_file
429};
430
431void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
432{
433 libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
434}
435
436/**
437 * @}
438 */
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