1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993, 1995
5 * The Regents of the University of California.
6 * Copyright (c) 2005 Robert N. M. Watson
7 * Copyright (c) 2012 Giovanni Trematerra
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
35 * $FreeBSD$
36 */
37
38 #include <sys/param.h>
39 #include <sys/event.h>
40 #include <sys/file.h>
41 #include <sys/filedesc.h>
42 #include <sys/filio.h>
43 #include <sys/fcntl.h>
44 #include <sys/kernel.h>
45 #include <sys/lock.h>
46 #include <sys/mutex.h>
47 #include <sys/malloc.h>
48 #include <sys/selinfo.h>
49 #include <sys/pipe.h>
50 #include <sys/proc.h>
51 #include <sys/signalvar.h>
52 #include <sys/sx.h>
53 #include <sys/systm.h>
54 #include <sys/un.h>
55 #include <sys/unistd.h>
56 #include <sys/vnode.h>
57
58 /*
59 * This structure is associated with the FIFO vnode and stores
60 * the state associated with the FIFO.
61 * Notes about locking:
62 * - fi_pipe is invariant since init time.
63 * - fi_readers and fi_writers are protected by the vnode lock.
64 */
65 struct fifoinfo {
66 struct pipe *fi_pipe;
67 long fi_readers;
68 long fi_writers;
69 u_int fi_rgen;
70 u_int fi_wgen;
71 };
72
73 static vop_print_t fifo_print;
74 static vop_open_t fifo_open;
75 static vop_close_t fifo_close;
76 static vop_advlock_t fifo_advlock;
77
78 struct vop_vector fifo_specops = {
79 .vop_default = &default_vnodeops,
80
81 .vop_advlock = fifo_advlock,
82 .vop_close = fifo_close,
83 .vop_create = VOP_PANIC,
84 .vop_getattr = VOP_EBADF,
85 .vop_ioctl = VOP_PANIC,
86 .vop_link = VOP_PANIC,
87 .vop_mkdir = VOP_PANIC,
88 .vop_mknod = VOP_PANIC,
89 .vop_open = fifo_open,
90 .vop_pathconf = VOP_PANIC,
91 .vop_print = fifo_print,
92 .vop_read = VOP_PANIC,
93 .vop_readdir = VOP_PANIC,
94 .vop_readlink = VOP_PANIC,
95 .vop_reallocblks = VOP_PANIC,
96 .vop_reclaim = VOP_NULL,
97 .vop_remove = VOP_PANIC,
98 .vop_rename = VOP_PANIC,
99 .vop_rmdir = VOP_PANIC,
100 .vop_setattr = VOP_EBADF,
101 .vop_symlink = VOP_PANIC,
102 .vop_write = VOP_PANIC,
103 };
104 VFS_VOP_VECTOR_REGISTER(fifo_specops);
105
106 /*
107 * Dispose of fifo resources.
108 */
109 static void
110 fifo_cleanup(struct vnode *vp)
111 {
112 struct fifoinfo *fip;
113
114 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
115 fip = vp->v_fifoinfo;
116 if (fip->fi_readers == 0 && fip->fi_writers == 0) {
117 vp->v_fifoinfo = NULL;
118 pipe_dtor(fip->fi_pipe);
119 free(fip, M_VNODE);
120 }
121 }
122
123 /*
124 * Open called to set up a new instance of a fifo or
125 * to find an active instance of a fifo.
126 */
127 /* ARGSUSED */
128 static int
129 fifo_open(ap)
130 struct vop_open_args /* {
131 struct vnode *a_vp;
132 int a_mode;
133 struct ucred *a_cred;
134 struct thread *a_td;
135 struct file *a_fp;
136 } */ *ap;
137 {
138 struct vnode *vp;
139 struct file *fp;
140 struct thread *td;
141 struct fifoinfo *fip;
142 struct pipe *fpipe;
143 u_int gen;
144 int error, stops_deferred;
145
146 vp = ap->a_vp;
147 fp = ap->a_fp;
148 td = ap->a_td;
149 ASSERT_VOP_ELOCKED(vp, "fifo_open");
150 if (fp == NULL || (ap->a_mode & FEXEC) != 0)
151 return (EINVAL);
152 if ((fip = vp->v_fifoinfo) == NULL) {
153 error = pipe_named_ctor(&fpipe, td);
154 if (error != 0)
155 return (error);
156 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK | M_ZERO);
157 fip->fi_pipe = fpipe;
158 fpipe->pipe_wgen = 0;
159 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
160 vp->v_fifoinfo = fip;
161 }
162 fpipe = fip->fi_pipe;
163 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
164
165 /*
166 * Use the pipe mutex here, in addition to the vnode lock,
167 * in order to allow vnode lock dropping before msleep() calls
168 * and still avoiding missed wakeups.
169 */
170 PIPE_LOCK(fpipe);
171 if (ap->a_mode & FREAD) {
172 fip->fi_readers++;
173 fip->fi_rgen++;
174 if (fip->fi_readers == 1) {
175 fpipe->pipe_state &= ~PIPE_EOF;
176 if (fip->fi_writers > 0) {
177 wakeup(&fip->fi_writers);
178 pipeselwakeup(fpipe);
179 }
180 }
181 fp->f_pipegen = fpipe->pipe_wgen - fip->fi_writers;
182 }
183 if (ap->a_mode & FWRITE) {
184 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
185 PIPE_UNLOCK(fpipe);
186 if (fip->fi_writers == 0)
187 fifo_cleanup(vp);
188 return (ENXIO);
189 }
190 fip->fi_writers++;
191 fip->fi_wgen++;
192 if (fip->fi_writers == 1) {
193 fpipe->pipe_state &= ~PIPE_EOF;
194 if (fip->fi_readers > 0) {
195 wakeup(&fip->fi_readers);
196 pipeselwakeup(fpipe);
197 }
198 }
199 }
200 if ((ap->a_mode & O_NONBLOCK) == 0) {
201 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
202 gen = fip->fi_wgen;
203 VOP_UNLOCK(vp);
204 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
205 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
206 PDROP | PCATCH | PSOCK, "fifoor", 0);
207 sigallowstop(stops_deferred);
208 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
209 if (error != 0 && gen == fip->fi_wgen) {
210 fip->fi_readers--;
211 if (fip->fi_readers == 0) {
212 PIPE_LOCK(fpipe);
213 fpipe->pipe_state |= PIPE_EOF;
214 if (fpipe->pipe_state & PIPE_WANTW)
215 wakeup(fpipe);
216 pipeselwakeup(fpipe);
217 PIPE_UNLOCK(fpipe);
218 fifo_cleanup(vp);
219 }
220 return (error);
221 }
222 PIPE_LOCK(fpipe);
223 /*
224 * We must have got woken up because we had a writer.
225 * That (and not still having one) is the condition
226 * that we must wait for.
227 */
228 }
229 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
230 gen = fip->fi_rgen;
231 VOP_UNLOCK(vp);
232 stops_deferred = sigdeferstop(SIGDEFERSTOP_OFF);
233 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
234 PDROP | PCATCH | PSOCK, "fifoow", 0);
235 sigallowstop(stops_deferred);
236 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
237 if (error != 0 && gen == fip->fi_rgen) {
238 fip->fi_writers--;
239 if (fip->fi_writers == 0) {
240 PIPE_LOCK(fpipe);
241 fpipe->pipe_state |= PIPE_EOF;
242 if (fpipe->pipe_state & PIPE_WANTR)
243 wakeup(fpipe);
244 fpipe->pipe_wgen++;
245 pipeselwakeup(fpipe);
246 PIPE_UNLOCK(fpipe);
247 fifo_cleanup(vp);
248 }
249 return (error);
250 }
251 /*
252 * We must have got woken up because we had
253 * a reader. That (and not still having one)
254 * is the condition that we must wait for.
255 */
256 PIPE_LOCK(fpipe);
257 }
258 }
259 PIPE_UNLOCK(fpipe);
260 KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
261 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
262 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
263 return (0);
264 }
265
266 /*
267 * Device close routine
268 */
269 /* ARGSUSED */
270 static int
271 fifo_close(ap)
272 struct vop_close_args /* {
273 struct vnode *a_vp;
274 int a_fflag;
275 struct ucred *a_cred;
276 struct thread *a_td;
277 } */ *ap;
278 {
279 struct vnode *vp;
280 struct fifoinfo *fip;
281 struct pipe *cpipe;
282
283 vp = ap->a_vp;
284 ASSERT_VOP_ELOCKED(vp, "fifo_close");
285 fip = vp->v_fifoinfo;
286
287 /*
288 * During open, it is possible that the fifo vnode is relocked
289 * after the vnode is instantiated but before VOP_OPEN() is
290 * done. For instance, vn_open_vnode() might need to upgrade
291 * vnode lock, or ffs_vput_pair() needs to unlock vp to sync
292 * dvp. In this case, reclaim can observe us with v_fifoinfo
293 * equal to NULL.
294 */
295 if (fip == NULL)
296 return (0);
297
298 cpipe = fip->fi_pipe;
299 if (ap->a_fflag & FREAD) {
300 fip->fi_readers--;
301 if (fip->fi_readers == 0) {
302 PIPE_LOCK(cpipe);
303 cpipe->pipe_state |= PIPE_EOF;
304 if ((cpipe->pipe_state & PIPE_WANTW)) {
305 cpipe->pipe_state &= ~PIPE_WANTW;
306 wakeup(cpipe);
307 }
308 pipeselwakeup(cpipe);
309 PIPE_UNLOCK(cpipe);
310 }
311 }
312 if (ap->a_fflag & FWRITE) {
313 fip->fi_writers--;
314 if (fip->fi_writers == 0) {
315 PIPE_LOCK(cpipe);
316 cpipe->pipe_state |= PIPE_EOF;
317 if ((cpipe->pipe_state & PIPE_WANTR)) {
318 cpipe->pipe_state &= ~PIPE_WANTR;
319 wakeup(cpipe);
320 }
321 cpipe->pipe_wgen++;
322 pipeselwakeup(cpipe);
323 PIPE_UNLOCK(cpipe);
324 }
325 }
326 fifo_cleanup(vp);
327 return (0);
328 }
329
330 /*
331 * Print out internal contents of a fifo vnode.
332 */
333 int
334 fifo_printinfo(vp)
335 struct vnode *vp;
336 {
337 struct fifoinfo *fip = vp->v_fifoinfo;
338
339 if (fip == NULL){
340 printf(", NULL v_fifoinfo");
341 return (0);
342 }
343 printf(", fifo with %ld readers and %ld writers",
344 fip->fi_readers, fip->fi_writers);
345 return (0);
346 }
347
348 /*
349 * Print out the contents of a fifo vnode.
350 */
351 static int
352 fifo_print(ap)
353 struct vop_print_args /* {
354 struct vnode *a_vp;
355 } */ *ap;
356 {
357 printf(" ");
358 fifo_printinfo(ap->a_vp);
359 printf("\n");
360 return (0);
361 }
362
363 /*
364 * Fifo advisory byte-level locks.
365 */
366 /* ARGSUSED */
367 static int
368 fifo_advlock(ap)
369 struct vop_advlock_args /* {
370 struct vnode *a_vp;
371 caddr_t a_id;
372 int a_op;
373 struct flock *a_fl;
374 int a_flags;
375 } */ *ap;
376 {
377
378 if ((ap->a_flags & F_FLOCK) == 0)
379 return (EINVAL);
380 return (vop_stdadvlock(ap));
381 }
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