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 * $FreeBSD$
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 u_int fi_rgen;
68 u_int fi_wgen;
69 };
70
71 static vop_print_t fifo_print;
72 static vop_open_t fifo_open;
73 static vop_close_t fifo_close;
74 static vop_advlock_t fifo_advlock;
75
76 struct vop_vector fifo_specops = {
77 .vop_default = &default_vnodeops,
78
79 .vop_advlock = fifo_advlock,
80 .vop_close = fifo_close,
81 .vop_create = VOP_PANIC,
82 .vop_getattr = VOP_EBADF,
83 .vop_ioctl = VOP_PANIC,
84 .vop_kqfilter = VOP_PANIC,
85 .vop_link = VOP_PANIC,
86 .vop_mkdir = VOP_PANIC,
87 .vop_mknod = VOP_PANIC,
88 .vop_open = fifo_open,
89 .vop_pathconf = VOP_PANIC,
90 .vop_print = fifo_print,
91 .vop_read = VOP_PANIC,
92 .vop_readdir = VOP_PANIC,
93 .vop_readlink = VOP_PANIC,
94 .vop_reallocblks = VOP_PANIC,
95 .vop_reclaim = VOP_NULL,
96 .vop_remove = VOP_PANIC,
97 .vop_rename = VOP_PANIC,
98 .vop_rmdir = VOP_PANIC,
99 .vop_setattr = VOP_EBADF,
100 .vop_symlink = VOP_PANIC,
101 .vop_write = VOP_PANIC,
102 };
103
104 /*
105 * Dispose of fifo resources.
106 */
107 static void
108 fifo_cleanup(struct vnode *vp)
109 {
110 struct fifoinfo *fip;
111
112 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
113 fip = vp->v_fifoinfo;
114 if (fip->fi_readers == 0 && fip->fi_writers == 0) {
115 vp->v_fifoinfo = NULL;
116 pipe_dtor(fip->fi_pipe);
117 free(fip, M_VNODE);
118 }
119 }
120
121 /*
122 * Open called to set up a new instance of a fifo or
123 * to find an active instance of a fifo.
124 */
125 /* ARGSUSED */
126 static int
127 fifo_open(ap)
128 struct vop_open_args /* {
129 struct vnode *a_vp;
130 int a_mode;
131 struct ucred *a_cred;
132 struct thread *a_td;
133 struct file *a_fp;
134 } */ *ap;
135 {
136 struct vnode *vp;
137 struct file *fp;
138 struct thread *td;
139 struct fifoinfo *fip;
140 struct pipe *fpipe;
141 u_int gen;
142 int error, stops_deferred;
143
144 vp = ap->a_vp;
145 fp = ap->a_fp;
146 td = ap->a_td;
147 ASSERT_VOP_ELOCKED(vp, "fifo_open");
148 if (fp == NULL || (ap->a_mode & FEXEC) != 0)
149 return (EINVAL);
150 if ((fip = vp->v_fifoinfo) == NULL) {
151 pipe_named_ctor(&fpipe, td);
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 fip->fi_rgen++;
170 if (fip->fi_readers == 1) {
171 fpipe->pipe_state &= ~PIPE_EOF;
172 if (fip->fi_writers > 0)
173 wakeup(&fip->fi_writers);
174 }
175 fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers;
176 }
177 if (ap->a_mode & FWRITE) {
178 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
179 PIPE_UNLOCK(fpipe);
180 if (fip->fi_writers == 0)
181 fifo_cleanup(vp);
182 return (ENXIO);
183 }
184 fip->fi_writers++;
185 fip->fi_wgen++;
186 if (fip->fi_writers == 1) {
187 fpipe->pipe_state &= ~PIPE_EOF;
188 if (fip->fi_readers > 0)
189 wakeup(&fip->fi_readers);
190 }
191 }
192 if ((ap->a_mode & O_NONBLOCK) == 0) {
193 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
194 gen = fip->fi_wgen;
195 VOP_UNLOCK(vp, 0);
196 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
197 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
198 PDROP | PCATCH | PSOCK, "fifoor", 0);
199 sigallowstop(stops_deferred);
200 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
201 if (error != 0 && gen == fip->fi_wgen) {
202 fip->fi_readers--;
203 if (fip->fi_readers == 0) {
204 PIPE_LOCK(fpipe);
205 fpipe->pipe_state |= PIPE_EOF;
206 if (fpipe->pipe_state & PIPE_WANTW)
207 wakeup(fpipe);
208 PIPE_UNLOCK(fpipe);
209 fifo_cleanup(vp);
210 }
211 return (error);
212 }
213 PIPE_LOCK(fpipe);
214 /*
215 * We must have got woken up because we had a writer.
216 * That (and not still having one) is the condition
217 * that we must wait for.
218 */
219 }
220 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
221 gen = fip->fi_rgen;
222 VOP_UNLOCK(vp, 0);
223 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
224 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
225 PDROP | PCATCH | PSOCK, "fifoow", 0);
226 sigallowstop(stops_deferred);
227 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
228 if (error != 0 && gen == fip->fi_rgen) {
229 fip->fi_writers--;
230 if (fip->fi_writers == 0) {
231 PIPE_LOCK(fpipe);
232 fpipe->pipe_state |= PIPE_EOF;
233 if (fpipe->pipe_state & PIPE_WANTR)
234 wakeup(fpipe);
235 fpipe->pipe_wgen++;
236 PIPE_UNLOCK(fpipe);
237 fifo_cleanup(vp);
238 }
239 return (error);
240 }
241 /*
242 * We must have got woken up because we had
243 * a reader. That (and not still having one)
244 * is the condition that we must wait for.
245 */
246 PIPE_LOCK(fpipe);
247 }
248 }
249 PIPE_UNLOCK(fpipe);
250 KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
251 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
252 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
253 return (0);
254 }
255
256 /*
257 * Device close routine
258 */
259 /* ARGSUSED */
260 static int
261 fifo_close(ap)
262 struct vop_close_args /* {
263 struct vnode *a_vp;
264 int a_fflag;
265 struct ucred *a_cred;
266 struct thread *a_td;
267 } */ *ap;
268 {
269 struct vnode *vp;
270 struct fifoinfo *fip;
271 struct pipe *cpipe;
272
273 vp = ap->a_vp;
274 fip = vp->v_fifoinfo;
275 cpipe = fip->fi_pipe;
276 ASSERT_VOP_ELOCKED(vp, "fifo_close");
277 if (ap->a_fflag & FREAD) {
278 fip->fi_readers--;
279 if (fip->fi_readers == 0) {
280 PIPE_LOCK(cpipe);
281 cpipe->pipe_state |= PIPE_EOF;
282 if ((cpipe->pipe_state & PIPE_WANTW)) {
283 cpipe->pipe_state &= ~PIPE_WANTW;
284 wakeup(cpipe);
285 }
286 pipeselwakeup(cpipe);
287 PIPE_UNLOCK(cpipe);
288 }
289 }
290 if (ap->a_fflag & FWRITE) {
291 fip->fi_writers--;
292 if (fip->fi_writers == 0) {
293 PIPE_LOCK(cpipe);
294 cpipe->pipe_state |= PIPE_EOF;
295 if ((cpipe->pipe_state & PIPE_WANTR)) {
296 cpipe->pipe_state &= ~PIPE_WANTR;
297 wakeup(cpipe);
298 }
299 cpipe->pipe_wgen++;
300 pipeselwakeup(cpipe);
301 PIPE_UNLOCK(cpipe);
302 }
303 }
304 fifo_cleanup(vp);
305 return (0);
306 }
307
308 /*
309 * Print out internal contents of a fifo vnode.
310 */
311 int
312 fifo_printinfo(vp)
313 struct vnode *vp;
314 {
315 struct fifoinfo *fip = vp->v_fifoinfo;
316
317 if (fip == NULL){
318 printf(", NULL v_fifoinfo");
319 return (0);
320 }
321 printf(", fifo with %ld readers and %ld writers",
322 fip->fi_readers, fip->fi_writers);
323 return (0);
324 }
325
326 /*
327 * Print out the contents of a fifo vnode.
328 */
329 static int
330 fifo_print(ap)
331 struct vop_print_args /* {
332 struct vnode *a_vp;
333 } */ *ap;
334 {
335 printf(" ");
336 fifo_printinfo(ap->a_vp);
337 printf("\n");
338 return (0);
339 }
340
341 /*
342 * Fifo advisory byte-level locks.
343 */
344 /* ARGSUSED */
345 static int
346 fifo_advlock(ap)
347 struct vop_advlock_args /* {
348 struct vnode *a_vp;
349 caddr_t a_id;
350 int a_op;
351 struct flock *a_fl;
352 int a_flags;
353 } */ *ap;
354 {
355
356 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
357 }
358
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