source: mainline/uspace/lib/libfs/libfs.c@ 9ad75d5

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 9ad75d5 was 9ad75d5, checked in by Jakub Jermar <jakub@…>, 18 years ago

Improve libfs_lookup() so that has_children() is not called for each character
in the pathname component.
  • Property mode set to 100644
File size: 8.5 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 libfs
30 * @{
31 */
32/**
33 * @file
34 * Glue code which is commonod to all FS implementations.
35 */
36
37#include "libfs.h"
38#include "../../srv/vfs/vfs.h"
39#include <errno.h>
40#include <async.h>
41#include <ipc/ipc.h>
42#include <as.h>
43#include <assert.h>
44#include <dirent.h>
45
46/** Register file system server.
47 *
48 * This function abstracts away the tedious registration protocol from
49 * file system implementations and lets them to reuse this registration glue
50 * code.
51 *
52 * @param vfs_phone Open phone for communication with VFS.
53 * @param reg File system registration structure. It will be
54 * initialized by this function.
55 * @param info VFS info structure supplied by the file system
56 * implementation.
57 * @param conn Connection fibril for handling all calls originating in
58 * VFS.
59 *
60 * @return EOK on success or a non-zero error code on errror.
61 */
62int fs_register(int vfs_phone, fs_reg_t *reg, vfs_info_t *info,
63 async_client_conn_t conn)
64{
65 /*
66 * Tell VFS that we are here and want to get registered.
67 * We use the async framework because VFS will answer the request
68 * out-of-order, when it knows that the operation succeeded or failed.
69 */
70 ipc_call_t answer;
71 aid_t req = async_send_0(vfs_phone, VFS_REGISTER, &answer);
72
73 /*
74 * Send our VFS info structure to VFS.
75 */
76 int rc = ipc_data_write_start(vfs_phone, info, sizeof(*info));
77 if (rc != EOK) {
78 async_wait_for(req, NULL);
79 return rc;
80 }
81
82 /*
83 * Ask VFS for callback connection.
84 */
85 ipc_connect_to_me(vfs_phone, 0, 0, 0, &reg->vfs_phonehash);
86
87 /*
88 * Allocate piece of address space for PLB.
89 */
90 reg->plb_ro = as_get_mappable_page(PLB_SIZE);
91 if (!reg->plb_ro) {
92 async_wait_for(req, NULL);
93 return ENOMEM;
94 }
95
96 /*
97 * Request sharing the Path Lookup Buffer with VFS.
98 */
99 rc = ipc_share_in_start_0_0(vfs_phone, reg->plb_ro, PLB_SIZE);
100 if (rc) {
101 async_wait_for(req, NULL);
102 return rc;
103 }
104
105 /*
106 * Pick up the answer for the request to the VFS_REQUEST call.
107 */
108 async_wait_for(req, NULL);
109 reg->fs_handle = (int) IPC_GET_ARG1(answer);
110
111 /*
112 * Create a connection fibril to handle the callback connection.
113 */
114 async_new_connection(reg->vfs_phonehash, 0, NULL, conn);
115
116 /*
117 * Tell the async framework that other connections are to be handled by
118 * the same connection fibril as well.
119 */
120 async_set_client_connection(conn);
121
122 return IPC_GET_RETVAL(answer);
123}
124
125/** Lookup VFS triplet by name in the file system name space.
126 *
127 * The path passed in the PLB must be in the canonical file system path format
128 * as returned by the canonify() function.
129 *
130 * @param ops libfs operations structure with function pointers to
131 * file system implementation
132 * @param fs_handle File system handle of the file system where to perform
133 * the lookup.
134 * @param rid Request ID of the VFS_LOOKUP request.
135 * @param request VFS_LOOKUP request data itself.
136 */
137void libfs_lookup(libfs_ops_t *ops, fs_handle_t fs_handle, ipc_callid_t rid,
138 ipc_call_t *request)
139{
140 unsigned next = IPC_GET_ARG1(*request);
141 unsigned last = IPC_GET_ARG2(*request);
142 dev_handle_t dev_handle = IPC_GET_ARG3(*request);
143 int lflag = IPC_GET_ARG4(*request);
144 fs_index_t index = IPC_GET_ARG5(*request); /* when L_LINK specified */
145
146 if (last < next)
147 last += PLB_SIZE;
148
149 void *par = NULL;
150 void *cur = ops->root_get(dev_handle);
151
152 if (ops->plb_get_char(next) == '/')
153 next++; /* eat slash */
154
155 char component[NAME_MAX + 1];
156 int len = 0;
157 while (ops->has_children(cur) && next <= last) {
158 void *tmp;
159
160 /* collect the component */
161 while ((ops->plb_get_char(next) != '/') && (next <= last)) {
162 if (len + 1 == NAME_MAX) {
163 /* comopnent length overflow */
164 ipc_answer_0(rid, ENAMETOOLONG);
165 return;
166 }
167 component[len++] = ops->plb_get_char(next);
168 next++; /* process next character */
169 }
170
171 assert(len);
172 component[len] = '\0';
173 next++; /* eat slash */
174 len = 0;
175
176 /* match the component */
177 tmp = ops->match(cur, component);
178
179 /* handle miss: match amongst siblings */
180 if (!tmp) {
181 if (next <= last) {
182 /* there are unprocessed components */
183 ipc_answer_0(rid, ENOENT);
184 return;
185 }
186 /* miss in the last component */
187 if (lflag & (L_CREATE | L_LINK)) {
188 /* request to create a new link */
189 if (!ops->is_directory(cur)) {
190 ipc_answer_0(rid, ENOTDIR);
191 return;
192 }
193 void *nodep;
194 if (lflag & L_CREATE)
195 nodep = ops->create(lflag);
196 else
197 nodep = ops->node_get(dev_handle,
198 index, ops->index_get(cur));
199 if (nodep) {
200 if (!ops->link(cur, nodep, component)) {
201 if (lflag & L_CREATE)
202 ops->destroy(nodep);
203 ipc_answer_0(rid, ENOSPC);
204 } else {
205 ipc_answer_5(rid, EOK,
206 fs_handle, dev_handle,
207 ops->index_get(nodep),
208 ops->size_get(nodep),
209 ops->lnkcnt_get(nodep));
210 }
211 } else {
212 ipc_answer_0(rid, ENOSPC);
213 }
214 return;
215 } else if (lflag & L_PARENT) {
216 /* return parent */
217 ipc_answer_5(rid, EOK, fs_handle, dev_handle,
218 ops->index_get(cur), ops->size_get(cur),
219 ops->lnkcnt_get(cur));
220 }
221 ipc_answer_0(rid, ENOENT);
222 return;
223 }
224
225 /* descend one level */
226 par = cur;
227 cur = tmp;
228 }
229
230 /* handle miss: excessive components */
231 if (!ops->has_children(cur) && next <= last) {
232 if (lflag & (L_CREATE | L_LINK)) {
233 if (!ops->is_directory(cur)) {
234 ipc_answer_0(rid, ENOTDIR);
235 return;
236 }
237
238 /* collect next component */
239 while (next <= last) {
240 if (ops->plb_get_char(next) == '/') {
241 /* more than one component */
242 ipc_answer_0(rid, ENOENT);
243 return;
244 }
245 if (len + 1 == NAME_MAX) {
246 /* component length overflow */
247 ipc_answer_0(rid, ENAMETOOLONG);
248 return;
249 }
250 component[len++] = ops->plb_get_char(next);
251 next++; /* process next character */
252 }
253 assert(len);
254 component[len] = '\0';
255 len = 0;
256
257 void *nodep;
258 if (lflag & L_CREATE)
259 nodep = ops->create(lflag);
260 else
261 nodep = ops->node_get(dev_handle, index,
262 ops->index_get(cur));
263 if (nodep) {
264 if (!ops->link(cur, nodep, component)) {
265 if (lflag & L_CREATE)
266 ops->destroy(nodep);
267 ipc_answer_0(rid, ENOSPC);
268 } else {
269 ipc_answer_5(rid, EOK,
270 fs_handle, dev_handle,
271 ops->index_get(nodep),
272 ops->size_get(nodep),
273 ops->lnkcnt_get(nodep));
274 }
275 } else {
276 ipc_answer_0(rid, ENOSPC);
277 }
278 return;
279 }
280 ipc_answer_0(rid, ENOENT);
281 return;
282 }
283
284 /* handle hit */
285 if (lflag & L_PARENT) {
286 cur = par;
287 if (!cur) {
288 ipc_answer_0(rid, ENOENT);
289 return;
290 }
291 }
292 if (lflag & L_UNLINK) {
293 unsigned old_lnkcnt = ops->lnkcnt_get(cur);
294 int res = ops->unlink(par, cur);
295 ipc_answer_5(rid, (ipcarg_t)res, fs_handle, dev_handle,
296 ops->index_get(cur), ops->size_get(cur), old_lnkcnt);
297 return;
298 }
299 if (((lflag & (L_CREATE | L_EXCLUSIVE)) == (L_CREATE | L_EXCLUSIVE)) ||
300 (lflag & L_LINK)) {
301 ipc_answer_0(rid, EEXIST);
302 return;
303 }
304 if ((lflag & L_FILE) && (ops->is_directory(cur))) {
305 ipc_answer_0(rid, EISDIR);
306 return;
307 }
308 if ((lflag & L_DIRECTORY) && (ops->is_file(cur))) {
309 ipc_answer_0(rid, ENOTDIR);
310 return;
311 }
312
313 ipc_answer_5(rid, EOK, fs_handle, dev_handle, ops->index_get(cur),
314 ops->size_get(cur), ops->lnkcnt_get(cur));
315}
316
317/** @}
318 */
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