source: mainline/uspace/srv/fs/fat/fat_ops.c@ 74ea3c6

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 74ea3c6 was 74ea3c6, checked in by Jakub Jermar <jakub@…>, 18 years ago

Add fat_root_get() and fat_plb_get_char().
  • Property mode set to 100644
File size: 8.8 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 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
146static void fat_sync_node(fat_node_t *node)
147{
148 /* TODO */
149}
150
151/** Instantiate a FAT in-core node.
152 *
153 * FAT stores the info necessary for instantiation of a node in the parent of
154 * that node. This design necessitated the addition of the parent node index
155 * parameter to this otherwise generic libfs API.
156 */
157static void *
158fat_node_get(dev_handle_t dev_handle, fs_index_t index, fs_index_t pindex)
159{
160 link_t *lnk;
161 fat_node_t *node = NULL;
162 block_t *b;
163 unsigned bps;
164 unsigned dps;
165 fat_dentry_t *d;
166 unsigned i, j;
167
168 unsigned long key[] = {
169 [FIN_KEY_DEV_HANDLE] = dev_handle,
170 [FIN_KEY_INDEX] = index
171 };
172
173 lnk = hash_table_find(&fin_hash, key);
174 if (lnk) {
175 /*
176 * The in-core node was found in the hash table.
177 */
178 node = hash_table_get_instance(lnk, fat_node_t, fin_link);
179 if (!node->refcnt++)
180 list_remove(&node->ffn_link);
181 return (void *) node;
182 }
183
184 bps = fat_bps_get(dev_handle);
185 dps = bps / sizeof(fat_dentry_t);
186
187 if (!list_empty(&ffn_head)) {
188 /*
189 * We are going to reuse a node from the free list.
190 */
191 lnk = ffn_head.next;
192 list_remove(lnk);
193 node = list_get_instance(lnk, fat_node_t, ffn_link);
194 assert(!node->refcnt);
195 if (node->dirty)
196 fat_sync_node(node);
197 key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
198 key[FIN_KEY_INDEX] = node->index;
199 hash_table_remove(&fin_hash, key, sizeof(key)/sizeof(*key));
200 } else {
201 /*
202 * We need to allocate a new node.
203 */
204 node = malloc(sizeof(fat_node_t));
205 if (!node)
206 return NULL;
207 }
208 fat_node_initialize(node);
209 node->refcnt++;
210 node->lnkcnt++;
211 node->dev_handle = dev_handle;
212 node->index = index;
213 node->pindex = pindex;
214
215 /*
216 * Because of the design of the FAT file system, we have no clue about
217 * how big (i.e. how many directory entries it contains) is the parent
218 * of the node we are trying to instantiate. However, we know that it
219 * must contain a directory entry for our node of interest. We simply
220 * scan the parent until we find it.
221 */
222 for (i = 0; ; i++) {
223 b = fat_block_get(node->dev_handle, node->pindex, i);
224 if (!b) {
225 node->refcnt--;
226 list_append(&node->ffn_link, &ffn_head);
227 return NULL;
228 }
229 for (j = 0; j < dps; j++) {
230 d = ((fat_dentry_t *)b->data) + j;
231 if (d->firstc == node->index)
232 goto found;
233 }
234 block_put(b);
235 }
236
237found:
238 if (!(d->attr & (FAT_ATTR_SUBDIR | FAT_ATTR_VOLLABEL)))
239 node->type = FAT_FILE;
240 if ((d->attr & FAT_ATTR_SUBDIR) || !index)
241 node->type = FAT_DIRECTORY;
242 assert((node->type == FAT_FILE) || (node->type == FAT_DIRECTORY));
243
244 node->size = uint32_t_le2host(d->size);
245 block_put(b);
246
247 key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
248 key[FIN_KEY_INDEX] = node->index;
249 hash_table_insert(&fin_hash, key, &node->fin_link);
250
251 return node;
252}
253
254static void *fat_match(void *prnt, const char *component)
255{
256 fat_node_t *parentp = (fat_node_t *)prnt;
257 char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
258 unsigned i, j;
259 unsigned bps; /* bytes per sector */
260 unsigned dps; /* dentries per sector */
261 unsigned blocks;
262 fat_dentry_t *d;
263 block_t *b;
264
265 bps = fat_bps_get(parentp->dev_handle);
266 dps = bps / sizeof(fat_dentry_t);
267 blocks = parentp->size / bps + (parentp->size % bps != 0);
268 for (i = 0; i < blocks; i++) {
269 unsigned dentries;
270
271 b = fat_block_get(parentp->dev_handle, parentp->index, i);
272 if (!b)
273 return NULL;
274
275 dentries = (i == blocks - 1) ?
276 parentp->size % sizeof(fat_dentry_t) :
277 dps;
278 for (j = 0; j < dentries; j++) {
279 d = ((fat_dentry_t *)b->data) + j;
280 if (d->attr & FAT_ATTR_VOLLABEL) {
281 /* volume label entry */
282 continue;
283 }
284 if (d->name[0] == FAT_DENTRY_ERASED) {
285 /* not-currently-used entry */
286 continue;
287 }
288 if (d->name[0] == FAT_DENTRY_UNUSED) {
289 /* never used entry */
290 block_put(b);
291 return NULL;
292 }
293 if (d->name[0] == FAT_DENTRY_DOT) {
294 /*
295 * Most likely '.' or '..'.
296 * It cannot occur in a regular file name.
297 */
298 continue;
299 }
300
301 dentry_name_canonify(d, name);
302 if (strcmp(name, component) == 0) {
303 /* hit */
304 void *node = fat_node_get(parentp->dev_handle,
305 (fs_index_t)uint16_t_le2host(d->firstc),
306 parentp->index);
307 block_put(b);
308 return node;
309 }
310 }
311 block_put(b);
312 }
313
314 return NULL;
315}
316
317static fs_index_t fat_index_get(void *node)
318{
319 fat_node_t *fnodep = (fat_node_t *)node;
320 if (!fnodep)
321 return 0;
322 return fnodep->index;
323}
324
325static size_t fat_size_get(void *node)
326{
327 return ((fat_node_t *)node)->size;
328}
329
330static unsigned fat_lnkcnt_get(void *node)
331{
332 return ((fat_node_t *)node)->lnkcnt;
333}
334
335static void *fat_root_get(dev_handle_t dev_handle)
336{
337 return fat_node_get(dev_handle, 0, 0);
338}
339
340static char fat_plb_get_char(unsigned pos)
341{
342 return fat_reg.plb_ro[pos % PLB_SIZE];
343}
344
345static bool fat_is_directory(void *node)
346{
347 return ((fat_node_t *)node)->type == FAT_DIRECTORY;
348}
349
350static bool fat_is_file(void *node)
351{
352 return ((fat_node_t *)node)->type == FAT_FILE;
353}
354
355/** libfs operations */
356libfs_ops_t fat_libfs_ops = {
357 .match = fat_match,
358 .node_get = fat_node_get,
359 .create = NULL,
360 .destroy = NULL,
361 .link = NULL,
362 .unlink = NULL,
363 .index_get = fat_index_get,
364 .size_get = fat_size_get,
365 .lnkcnt_get = fat_lnkcnt_get,
366 .has_children = NULL,
367 .root_get = fat_root_get,
368 .plb_get_char = fat_plb_get_char,
369 .is_directory = fat_is_directory,
370 .is_file = fat_is_file
371};
372
373void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
374{
375 libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
376}
377
378/**
379 * @}
380 */
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