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/10.1/sys/fs/fifofs/fifo_vnops.c 268335 2014-07-06 22:47:18Z mjg $
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 || (ap->a_mode & FEXEC) != 0)
147 return (EINVAL);
148 if ((fip = vp->v_fifoinfo) == NULL) {
149 pipe_named_ctor(&fpipe, td);
150 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
151 fip->fi_pipe = fpipe;
152 fpipe->pipe_wgen = fip->fi_readers = fip->fi_writers = 0;
153 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
154 vp->v_fifoinfo = fip;
155 }
156 fpipe = fip->fi_pipe;
157 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
158
159 /*
160 * Use the pipe mutex here, in addition to the vnode lock,
161 * in order to allow vnode lock dropping before msleep() calls
162 * and still avoiding missed wakeups.
163 */
164 PIPE_LOCK(fpipe);
165 if (ap->a_mode & FREAD) {
166 fip->fi_readers++;
167 if (fip->fi_readers == 1) {
168 fpipe->pipe_state &= ~PIPE_EOF;
169 if (fip->fi_writers > 0)
170 wakeup(&fip->fi_writers);
171 }
172 fp->f_seqcount = fpipe->pipe_wgen - fip->fi_writers;
173 }
174 if (ap->a_mode & FWRITE) {
175 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
176 PIPE_UNLOCK(fpipe);
177 if (fip->fi_writers == 0)
178 fifo_cleanup(vp);
179 return (ENXIO);
180 }
181 fip->fi_writers++;
182 if (fip->fi_writers == 1) {
183 fpipe->pipe_state &= ~PIPE_EOF;
184 if (fip->fi_readers > 0)
185 wakeup(&fip->fi_readers);
186 }
187 }
188 if ((ap->a_mode & O_NONBLOCK) == 0) {
189 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
190 VOP_UNLOCK(vp, 0);
191 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
192 PDROP | PCATCH | PSOCK, "fifoor", 0);
193 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
194 if (error) {
195 fip->fi_readers--;
196 if (fip->fi_readers == 0) {
197 PIPE_LOCK(fpipe);
198 fpipe->pipe_state |= PIPE_EOF;
199 if (fpipe->pipe_state & PIPE_WANTW)
200 wakeup(fpipe);
201 PIPE_UNLOCK(fpipe);
202 fifo_cleanup(vp);
203 }
204 return (error);
205 }
206 PIPE_LOCK(fpipe);
207 /*
208 * We must have got woken up because we had a writer.
209 * That (and not still having one) is the condition
210 * that we must wait for.
211 */
212 }
213 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
214 VOP_UNLOCK(vp, 0);
215 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
216 PDROP | PCATCH | PSOCK, "fifoow", 0);
217 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
218 if (error) {
219 fip->fi_writers--;
220 if (fip->fi_writers == 0) {
221 PIPE_LOCK(fpipe);
222 fpipe->pipe_state |= PIPE_EOF;
223 if (fpipe->pipe_state & PIPE_WANTR)
224 wakeup(fpipe);
225 fpipe->pipe_wgen++;
226 PIPE_UNLOCK(fpipe);
227 fifo_cleanup(vp);
228 }
229 return (error);
230 }
231 /*
232 * We must have got woken up because we had
233 * a reader. That (and not still having one)
234 * is the condition that we must wait for.
235 */
236 PIPE_LOCK(fpipe);
237 }
238 }
239 PIPE_UNLOCK(fpipe);
240 KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
241 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
242 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
243 return (0);
244 }
245
246 /*
247 * Device close routine
248 */
249 /* ARGSUSED */
250 static int
251 fifo_close(ap)
252 struct vop_close_args /* {
253 struct vnode *a_vp;
254 int a_fflag;
255 struct ucred *a_cred;
256 struct thread *a_td;
257 } */ *ap;
258 {
259 struct vnode *vp;
260 struct fifoinfo *fip;
261 struct pipe *cpipe;
262
263 vp = ap->a_vp;
264 fip = vp->v_fifoinfo;
265 cpipe = fip->fi_pipe;
266 ASSERT_VOP_ELOCKED(vp, "fifo_close");
267 if (ap->a_fflag & FREAD) {
268 fip->fi_readers--;
269 if (fip->fi_readers == 0) {
270 PIPE_LOCK(cpipe);
271 cpipe->pipe_state |= PIPE_EOF;
272 if ((cpipe->pipe_state & PIPE_WANTW)) {
273 cpipe->pipe_state &= ~PIPE_WANTW;
274 wakeup(cpipe);
275 }
276 pipeselwakeup(cpipe);
277 PIPE_UNLOCK(cpipe);
278 }
279 }
280 if (ap->a_fflag & FWRITE) {
281 fip->fi_writers--;
282 if (fip->fi_writers == 0) {
283 PIPE_LOCK(cpipe);
284 cpipe->pipe_state |= PIPE_EOF;
285 if ((cpipe->pipe_state & PIPE_WANTR)) {
286 cpipe->pipe_state &= ~PIPE_WANTR;
287 wakeup(cpipe);
288 }
289 cpipe->pipe_wgen++;
290 pipeselwakeup(cpipe);
291 PIPE_UNLOCK(cpipe);
292 }
293 }
294 fifo_cleanup(vp);
295 return (0);
296 }
297
298 /*
299 * Print out internal contents of a fifo vnode.
300 */
301 int
302 fifo_printinfo(vp)
303 struct vnode *vp;
304 {
305 register struct fifoinfo *fip = vp->v_fifoinfo;
306
307 if (fip == NULL){
308 printf(", NULL v_fifoinfo");
309 return (0);
310 }
311 printf(", fifo with %ld readers and %ld writers",
312 fip->fi_readers, fip->fi_writers);
313 return (0);
314 }
315
316 /*
317 * Print out the contents of a fifo vnode.
318 */
319 static int
320 fifo_print(ap)
321 struct vop_print_args /* {
322 struct vnode *a_vp;
323 } */ *ap;
324 {
325 printf(" ");
326 fifo_printinfo(ap->a_vp);
327 printf("\n");
328 return (0);
329 }
330
331 /*
332 * Return POSIX pathconf information applicable to fifo's.
333 */
334 static int
335 fifo_pathconf(ap)
336 struct vop_pathconf_args /* {
337 struct vnode *a_vp;
338 int a_name;
339 int *a_retval;
340 } */ *ap;
341 {
342
343 switch (ap->a_name) {
344 case _PC_LINK_MAX:
345 *ap->a_retval = LINK_MAX;
346 return (0);
347 case _PC_PIPE_BUF:
348 *ap->a_retval = PIPE_BUF;
349 return (0);
350 case _PC_CHOWN_RESTRICTED:
351 *ap->a_retval = 1;
352 return (0);
353 default:
354 return (EINVAL);
355 }
356 /* NOTREACHED */
357 }
358
359 /*
360 * Fifo advisory byte-level locks.
361 */
362 /* ARGSUSED */
363 static int
364 fifo_advlock(ap)
365 struct vop_advlock_args /* {
366 struct vnode *a_vp;
367 caddr_t a_id;
368 int a_op;
369 struct flock *a_fl;
370 int a_flags;
371 } */ *ap;
372 {
373
374 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
375 }
376
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