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DEFINITIONS
This source file includes following definitions.
- change_bootfs
- vfs_setbootfs
- vfs_clearbootfs
- getdevice
- vfs_lookparent
- vfs_lookup
1 /*
2 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
3 * The President and Fellows of Harvard College.
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 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 /*
31 * VFS operations relating to pathname translation
32 */
33
34 #include <types.h>
35 #include <kern/errno.h>
36 #include <limits.h>
37 #include <lib.h>
38 #include <synch.h>
39 #include <vfs.h>
40 #include <fs.h>
41 #include <vnode.h>
42
43 static struct vnode *bootfs_vnode = NULL;
44
45 /*
46 * Helper function for actually changing bootfs_vnode.
47 */
48 static
49 void
50 change_bootfs(struct vnode *newvn)
51 {
52 struct vnode *oldvn;
53
54 oldvn = bootfs_vnode;
55 bootfs_vnode = newvn;
56
57 if (oldvn != NULL) {
58 VOP_DECREF(oldvn);
59 }
60 }
61
62 /*
63 * Set bootfs_vnode.
64 *
65 * Bootfs_vnode is the vnode used for beginning path translation of
66 * pathnames starting with /.
67 *
68 * It is also incidentally the system's first current directory.
69 */
70 int
71 vfs_setbootfs(const char *fsname)
72 {
73 char tmp[NAME_MAX+1];
74 char *s;
75 int result;
76 struct vnode *newguy;
77
78 vfs_biglock_acquire();
79
80 snprintf(tmp, sizeof(tmp)-1, "%s", fsname);
81 s = strchr(tmp, ':');
82 if (s) {
83 /* If there's a colon, it must be at the end */
84 if (strlen(s)>0) {
85 vfs_biglock_release();
86 return EINVAL;
87 }
88 }
89 else {
90 strcat(tmp, ":");
91 }
92
93 result = vfs_chdir(tmp);
94 if (result) {
95 vfs_biglock_release();
96 return result;
97 }
98
99 result = vfs_getcurdir(&newguy);
100 if (result) {
101 vfs_biglock_release();
102 return result;
103 }
104
105 change_bootfs(newguy);
106
107 vfs_biglock_release();
108 return 0;
109 }
110
111 /*
112 * Clear the bootfs vnode (preparatory to system shutdown).
113 */
114 void
115 vfs_clearbootfs(void)
116 {
117 vfs_biglock_acquire();
118 change_bootfs(NULL);
119 vfs_biglock_release();
120 }
121
122
123 /*
124 * Common code to pull the device name, if any, off the front of a
125 * path and choose the vnode to begin the name lookup relative to.
126 */
127
128 static
129 int
130 getdevice(char *path, char **subpath, struct vnode **startvn)
131 {
132 int slash=-1, colon=-1, i;
133 struct vnode *vn;
134 int result;
135
136 KASSERT(vfs_biglock_do_i_hold());
137
138 /*
139 * Locate the first colon or slash.
140 */
141
142 for (i=0; path[i]; i++) {
143 if (path[i]==':') {
144 colon = i;
145 break;
146 }
147 if (path[i]=='/') {
148 slash = i;
149 break;
150 }
151 }
152
153 if (colon < 0 && slash != 0) {
154 /*
155 * No colon before a slash, so no device name
156 * specified, and the slash isn't leading or is also
157 * absent, so this is a relative path or just a bare
158 * filename. Start from the current directory, and
159 * use the whole thing as the subpath.
160 */
161 *subpath = path;
162 return vfs_getcurdir(startvn);
163 }
164
165 if (colon>0) {
166 /* device:path - get root of device's filesystem */
167 path[colon]=0;
168 while (path[colon+1]=='/') {
169 /* device:/path - skip slash, treat as device:path */
170 colon++;
171 }
172 *subpath = &path[colon+1];
173
174 result = vfs_getroot(path, startvn);
175 if (result) {
176 return result;
177 }
178
179 return 0;
180 }
181
182 /*
183 * We have either /path or :path.
184 *
185 * /path is a path relative to the root of the "boot filesystem".
186 * :path is a path relative to the root of the current filesystem.
187 */
188 KASSERT(colon==0 || slash==0);
189
190 if (path[0]=='/') {
191 if (bootfs_vnode==NULL) {
192 return ENOENT;
193 }
194 VOP_INCREF(bootfs_vnode);
195 *startvn = bootfs_vnode;
196 }
197 else {
198 KASSERT(path[0]==':');
199
200 result = vfs_getcurdir(&vn);
201 if (result) {
202 return result;
203 }
204
205 /*
206 * The current directory may not be a device, so it
207 * must have a fs.
208 */
209 KASSERT(vn->vn_fs!=NULL);
210
211 *startvn = FSOP_GETROOT(vn->vn_fs);
212
213 VOP_DECREF(vn);
214 }
215
216 while (path[1]=='/') {
217 /* ///... or :/... */
218 path++;
219 }
220
221 *subpath = path+1;
222
223 return 0;
224 }
225
226 /*
227 * Name-to-vnode translation.
228 * (In BSD, both of these are subsumed by namei().)
229 */
230
231 int
232 vfs_lookparent(char *path, struct vnode **retval,
233 char *buf, size_t buflen)
234 {
235 struct vnode *startvn;
236 int result;
237
238 vfs_biglock_acquire();
239
240 result = getdevice(path, &path, &startvn);
241 if (result) {
242 vfs_biglock_release();
243 return result;
244 }
245
246 if (strlen(path)==0) {
247 /*
248 * It does not make sense to use just a device name in
249 * a context where "lookparent" is the desired
250 * operation.
251 */
252 result = EINVAL;
253 }
254 else {
255 result = VOP_LOOKPARENT(startvn, path, retval, buf, buflen);
256 }
257
258 VOP_DECREF(startvn);
259
260 vfs_biglock_release();
261 return result;
262 }
263
264 int
265 vfs_lookup(char *path, struct vnode **retval)
266 {
267 struct vnode *startvn;
268 int result;
269
270 vfs_biglock_acquire();
271
272 result = getdevice(path, &path, &startvn);
273 if (result) {
274 vfs_biglock_release();
275 return result;
276 }
277
278 if (strlen(path)==0) {
279 *retval = startvn;
280 vfs_biglock_release();
281 return 0;
282 }
283
284 result = VOP_LOOKUP(startvn, path, retval);
285
286 VOP_DECREF(startvn);
287 vfs_biglock_release();
288 return result;
289 }