1 /*-
2 * Copyright (c) 1990, 1993, 1995
3 * The Regents of the University of California.
4 * Copyright (c) 2005 Robert N. M. Watson
5 * Copyright (c) 2012 Giovanni Trematerra
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
33 * $FreeBSD: releng/10.0/sys/fs/fifofs/fifo_vnops.c 238936 2012-07-31 05:48:35Z davidxu $
34 */
35
36 #include <sys/param.h>
37 #include <sys/event.h>
38 #include <sys/file.h>
39 #include <sys/filedesc.h>
40 #include <sys/filio.h>
41 #include <sys/fcntl.h>
42 #include <sys/kernel.h>
43 #include <sys/lock.h>
44 #include <sys/mutex.h>
45 #include <sys/malloc.h>
46 #include <sys/selinfo.h>
47 #include <sys/pipe.h>
48 #include <sys/proc.h>
49 #include <sys/signalvar.h>
50 #include <sys/sx.h>
51 #include <sys/systm.h>
52 #include <sys/un.h>
53 #include <sys/unistd.h>
54 #include <sys/vnode.h>
55
56 /*
57 * This structure is associated with the FIFO vnode and stores
58 * the state associated with the FIFO.
59 * Notes about locking:
60 * - fi_pipe is invariant since init time.
61 * - fi_readers and fi_writers are protected by the vnode lock.
62 */
63 struct fifoinfo {
64 struct pipe *fi_pipe;
65 long fi_readers;
66 long fi_writers;
67 };
68
69 static vop_print_t fifo_print;
70 static vop_open_t fifo_open;
71 static vop_close_t fifo_close;
72 static vop_pathconf_t fifo_pathconf;
73 static vop_advlock_t fifo_advlock;
74
75 struct vop_vector fifo_specops = {
76 .vop_default = &default_vnodeops,
77
78 .vop_advlock = fifo_advlock,
79 .vop_close = fifo_close,
80 .vop_create = VOP_PANIC,
81 .vop_getattr = VOP_EBADF,
82 .vop_ioctl = VOP_PANIC,
83 .vop_kqfilter = VOP_PANIC,
84 .vop_link = VOP_PANIC,
85 .vop_mkdir = VOP_PANIC,
86 .vop_mknod = VOP_PANIC,
87 .vop_open = fifo_open,
88 .vop_pathconf = fifo_pathconf,
89 .vop_print = fifo_print,
90 .vop_read = VOP_PANIC,
91 .vop_readdir = VOP_PANIC,
92 .vop_readlink = VOP_PANIC,
93 .vop_reallocblks = VOP_PANIC,
94 .vop_reclaim = VOP_NULL,
95 .vop_remove = VOP_PANIC,
96 .vop_rename = VOP_PANIC,
97 .vop_rmdir = VOP_PANIC,
98 .vop_setattr = VOP_EBADF,
99 .vop_symlink = VOP_PANIC,
100 .vop_write = VOP_PANIC,
101 };
102
103 /*
104 * Dispose of fifo resources.
105 */
106 static void
107 fifo_cleanup(struct vnode *vp)
108 {
109 struct fifoinfo *fip;
110
111 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
112 fip = vp->v_fifoinfo;
113 if (fip->fi_readers == 0 && fip->fi_writers == 0) {
114 vp->v_fifoinfo = NULL;
115 pipe_dtor(fip->fi_pipe);
116 free(fip, M_VNODE);
117 }
118 }
119
120 /*
121 * Open called to set up a new instance of a fifo or
122 * to find an active instance of a fifo.
123 */
124 /* ARGSUSED */
125 static int
126 fifo_open(ap)
127 struct vop_open_args /* {
128 struct vnode *a_vp;
129 int a_mode;
130 struct ucred *a_cred;
131 struct thread *a_td;
132 struct file *a_fp;
133 } */ *ap;
134 {
135 struct vnode *vp;
136 struct file *fp;
137 struct thread *td;
138 struct fifoinfo *fip;
139 struct pipe *fpipe;
140 int error;
141
142 vp = ap->a_vp;
143 fp = ap->a_fp;
144 td = ap->a_td;
145 ASSERT_VOP_ELOCKED(vp, "fifo_open");
146 if (fp == NULL)
147 return (EINVAL);
148 if ((fip = vp->v_fifoinfo) == NULL) {
149 error = pipe_named_ctor(&fpipe, td);
150 if (error != 0)
151 return (error);
152 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
153 fip->fi_pipe = fpipe;
154 fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0;
155 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
156 vp->v_fifoinfo = fip;
157 }
158 fpipe = fip->fi_pipe;
159 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
160
161 /*
162 * Use the pipe mutex here, in addition to the vnode lock,
163 * in order to allow vnode lock dropping before msleep() calls
164 * and still avoiding missed wakeups.
165 */
166 PIPE_LOCK(fpipe);
167 if (ap->a_mode & FREAD) {
168 fip->fi_readers++;
169 if (fip->fi_readers == 1) {
170 fpipe->pipe_state &= ~PIPE_EOF;
171 if (fip->fi_writers > 0)
172 wakeup(&fip->fi_writers);
173 }
174 fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers;
175 }
176 if (ap->a_mode & FWRITE) {
177 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
178 PIPE_UNLOCK(fpipe);
179 if (fip->fi_writers == 0)
180 fifo_cleanup(vp);
181 return (ENXIO);
182 }
183 fip->fi_writers++;
184 if (fip->fi_writers == 1) {
185 fpipe->pipe_state &= ~PIPE_EOF;
186 if (fip->fi_readers > 0)
187 wakeup(&fip->fi_readers);
188 }
189 }
190 if ((ap->a_mode & O_NONBLOCK) == 0) {
191 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
192 VOP_UNLOCK(vp, 0);
193 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
194 PDROP | PCATCH | PSOCK, "fifoor", 0);
195 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
196 if (error) {
197 fip->fi_readers--;
198 if (fip->fi_readers == 0) {
199 PIPE_LOCK(fpipe);
200 fpipe->pipe_state |= PIPE_EOF;
201 if (fpipe->pipe_state & PIPE_WANTW)
202 wakeup(fpipe);
203 PIPE_UNLOCK(fpipe);
204 fifo_cleanup(vp);
205 }
206 return (error);
207 }
208 PIPE_LOCK(fpipe);
209 /*
210 * We must have got woken up because we had a writer.
211 * That (and not still having one) is the condition
212 * that we must wait for.
213 */
214 }
215 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
216 VOP_UNLOCK(vp, 0);
217 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
218 PDROP | PCATCH | PSOCK, "fifoow", 0);
219 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
220 if (error) {
221 fip->fi_writers--;
222 if (fip->fi_writers == 0) {
223 PIPE_LOCK(fpipe);
224 fpipe->pipe_state |= PIPE_EOF;
225 if (fpipe->pipe_state & PIPE_WANTR)
226 wakeup(fpipe);
227 fpipe->pipe_wgen++;
228 PIPE_UNLOCK(fpipe);
229 fifo_cleanup(vp);
230 }
231 return (error);
232 }
233 /*
234 * We must have got woken up because we had
235 * a reader. That (and not still having one)
236 * is the condition that we must wait for.
237 */
238 PIPE_LOCK(fpipe);
239 }
240 }
241 PIPE_UNLOCK(fpipe);
242 KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
243 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
244 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
245 return (0);
246 }
247
248 /*
249 * Device close routine
250 */
251 /* ARGSUSED */
252 static int
253 fifo_close(ap)
254 struct vop_close_args /* {
255 struct vnode *a_vp;
256 int a_fflag;
257 struct ucred *a_cred;
258 struct thread *a_td;
259 } */ *ap;
260 {
261 struct vnode *vp;
262 struct fifoinfo *fip;
263 struct pipe *cpipe;
264
265 vp = ap->a_vp;
266 fip = vp->v_fifoinfo;
267 cpipe = fip->fi_pipe;
268 ASSERT_VOP_ELOCKED(vp, "fifo_close");
269 if (ap->a_fflag & FREAD) {
270 fip->fi_readers--;
271 if (fip->fi_readers == 0) {
272 PIPE_LOCK(cpipe);
273 cpipe->pipe_state |= PIPE_EOF;
274 if ((cpipe->pipe_state & PIPE_WANTW)) {
275 cpipe->pipe_state &= ~PIPE_WANTW;
276 wakeup(cpipe);
277 }
278 pipeselwakeup(cpipe);
279 PIPE_UNLOCK(cpipe);
280 }
281 }
282 if (ap->a_fflag & FWRITE) {
283 fip->fi_writers--;
284 if (fip->fi_writers == 0) {
285 PIPE_LOCK(cpipe);
286 cpipe->pipe_state |= PIPE_EOF;
287 if ((cpipe->pipe_state & PIPE_WANTR)) {
288 cpipe->pipe_state &= ~PIPE_WANTR;
289 wakeup(cpipe);
290 }
291 cpipe->pipe_wgen++;
292 pipeselwakeup(cpipe);
293 PIPE_UNLOCK(cpipe);
294 }
295 }
296 fifo_cleanup(vp);
297 return (0);
298 }
299
300 /*
301 * Print out internal contents of a fifo vnode.
302 */
303 int
304 fifo_printinfo(vp)
305 struct vnode *vp;
306 {
307 register struct fifoinfo *fip = vp->v_fifoinfo;
308
309 if (fip == NULL){
310 printf(", NULL v_fifoinfo");
311 return (0);
312 }
313 printf(", fifo with %ld readers and %ld writers",
314 fip->fi_readers, fip->fi_writers);
315 return (0);
316 }
317
318 /*
319 * Print out the contents of a fifo vnode.
320 */
321 static int
322 fifo_print(ap)
323 struct vop_print_args /* {
324 struct vnode *a_vp;
325 } */ *ap;
326 {
327 printf(" ");
328 fifo_printinfo(ap->a_vp);
329 printf("\n");
330 return (0);
331 }
332
333 /*
334 * Return POSIX pathconf information applicable to fifo's.
335 */
336 static int
337 fifo_pathconf(ap)
338 struct vop_pathconf_args /* {
339 struct vnode *a_vp;
340 int a_name;
341 int *a_retval;
342 } */ *ap;
343 {
344
345 switch (ap->a_name) {
346 case _PC_LINK_MAX:
347 *ap->a_retval = LINK_MAX;
348 return (0);
349 case _PC_PIPE_BUF:
350 *ap->a_retval = PIPE_BUF;
351 return (0);
352 case _PC_CHOWN_RESTRICTED:
353 *ap->a_retval = 1;
354 return (0);
355 default:
356 return (EINVAL);
357 }
358 /* NOTREACHED */
359 }
360
361 /*
362 * Fifo advisory byte-level locks.
363 */
364 /* ARGSUSED */
365 static int
366 fifo_advlock(ap)
367 struct vop_advlock_args /* {
368 struct vnode *a_vp;
369 caddr_t a_id;
370 int a_op;
371 struct flock *a_fl;
372 int a_flags;
373 } */ *ap;
374 {
375
376 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
377 }
378
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