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
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
32 * @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
36 #include <sys/param.h>
37 #include <sys/event.h>
39 #include <sys/filedesc.h>
40 #include <sys/filio.h>
41 #include <sys/fcntl.h>
42 #include <sys/kernel.h>
44 #include <sys/mutex.h>
45 #include <sys/malloc.h>
46 #include <sys/selinfo.h>
49 #include <sys/signalvar.h>
51 #include <sys/systm.h>
53 #include <sys/unistd.h>
54 #include <sys/vnode.h>
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 * - fi_wgen and fi_seqcount are protected by the pipe mutex.
72 #define FIFO_UPDWGEN(fip, pip) do { \
73 if ((fip)->fi_wgen == (fip)->fi_seqcount) \
74 (pip)->pipe_state |= PIPE_SAMEWGEN; \
76 (pip)->pipe_state &= ~PIPE_SAMEWGEN; \
79 static vop_print_t fifo_print;
80 static vop_open_t fifo_open;
81 static vop_close_t fifo_close;
82 static vop_pathconf_t fifo_pathconf;
83 static vop_advlock_t fifo_advlock;
85 struct vop_vector fifo_specops = {
86 .vop_default = &default_vnodeops,
88 .vop_advlock = fifo_advlock,
89 .vop_close = fifo_close,
90 .vop_create = VOP_PANIC,
91 .vop_getattr = VOP_EBADF,
92 .vop_ioctl = VOP_PANIC,
93 .vop_kqfilter = VOP_PANIC,
94 .vop_link = VOP_PANIC,
95 .vop_mkdir = VOP_PANIC,
96 .vop_mknod = VOP_PANIC,
97 .vop_open = fifo_open,
98 .vop_pathconf = fifo_pathconf,
99 .vop_print = fifo_print,
100 .vop_read = VOP_PANIC,
101 .vop_readdir = VOP_PANIC,
102 .vop_readlink = VOP_PANIC,
103 .vop_reallocblks = VOP_PANIC,
104 .vop_reclaim = VOP_NULL,
105 .vop_remove = VOP_PANIC,
106 .vop_rename = VOP_PANIC,
107 .vop_rmdir = VOP_PANIC,
108 .vop_setattr = VOP_EBADF,
109 .vop_symlink = VOP_PANIC,
110 .vop_write = VOP_PANIC,
114 * Dispose of fifo resources.
117 fifo_cleanup(struct vnode *vp)
119 struct fifoinfo *fip;
121 ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
122 fip = vp->v_fifoinfo;
123 if (fip->fi_readers == 0 && fip->fi_writers == 0) {
124 vp->v_fifoinfo = NULL;
125 pipe_dtor(fip->fi_pipe);
131 * Open called to set up a new instance of a fifo or
132 * to find an active instance of a fifo.
137 struct vop_open_args /* {
140 struct ucred *a_cred;
148 struct fifoinfo *fip;
155 ASSERT_VOP_ELOCKED(vp, "fifo_open");
158 if ((fip = vp->v_fifoinfo) == NULL) {
159 error = pipe_named_ctor(&fpipe, td);
162 fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
163 fip->fi_pipe = fpipe;
164 fip->fi_wgen = fip->fi_readers = fip->fi_writers = 0;
165 KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
166 vp->v_fifoinfo = fip;
168 fpipe = fip->fi_pipe;
169 KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
172 * Use the pipe mutex here, in addition to the vnode lock,
173 * in order to allow vnode lock dropping before msleep() calls
174 * and still avoiding missed wakeups.
177 if (ap->a_mode & FREAD) {
179 if (fip->fi_readers == 1) {
180 fpipe->pipe_state &= ~PIPE_EOF;
181 if (fip->fi_writers > 0)
182 wakeup(&fip->fi_writers);
184 fip->fi_seqcount = fip->fi_wgen - fip->fi_writers;
185 FIFO_UPDWGEN(fip, fpipe);
187 if (ap->a_mode & FWRITE) {
188 if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
190 if (fip->fi_writers == 0)
195 if (fip->fi_writers == 1) {
196 fpipe->pipe_state &= ~PIPE_EOF;
197 if (fip->fi_readers > 0)
198 wakeup(&fip->fi_readers);
201 if ((ap->a_mode & O_NONBLOCK) == 0) {
202 if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
204 error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
205 PDROP | PCATCH | PSOCK, "fifoor", 0);
206 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
209 if (fip->fi_readers == 0) {
211 fpipe->pipe_state |= PIPE_EOF;
212 if (fpipe->pipe_state & PIPE_WANTW)
221 * We must have got woken up because we had a writer.
222 * That (and not still having one) is the condition
223 * that we must wait for.
226 if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
228 error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
229 PDROP | PCATCH | PSOCK, "fifoow", 0);
230 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
233 if (fip->fi_writers == 0) {
235 fpipe->pipe_state |= PIPE_EOF;
236 if (fpipe->pipe_state & PIPE_WANTR)
239 FIFO_UPDWGEN(fip, fpipe);
246 * We must have got woken up because we had
247 * a reader. That (and not still having one)
248 * is the condition that we must wait for.
254 KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
255 KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
256 finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
261 * Device close routine
266 struct vop_close_args /* {
269 struct ucred *a_cred;
274 struct fifoinfo *fip;
278 fip = vp->v_fifoinfo;
279 cpipe = fip->fi_pipe;
280 ASSERT_VOP_ELOCKED(vp, "fifo_close");
281 if (ap->a_fflag & FREAD) {
283 if (fip->fi_readers == 0) {
285 cpipe->pipe_state |= PIPE_EOF;
286 if (cpipe->pipe_state & PIPE_WANTW)
291 if (ap->a_fflag & FWRITE) {
293 if (fip->fi_writers == 0) {
295 cpipe->pipe_state |= PIPE_EOF;
296 if (cpipe->pipe_state & PIPE_WANTR)
299 FIFO_UPDWGEN(fip, cpipe);
308 * Print out internal contents of a fifo vnode.
314 register struct fifoinfo *fip = vp->v_fifoinfo;
317 printf(", NULL v_fifoinfo");
320 printf(", fifo with %ld readers and %ld writers",
321 fip->fi_readers, fip->fi_writers);
326 * Print out the contents of a fifo vnode.
330 struct vop_print_args /* {
335 fifo_printinfo(ap->a_vp);
341 * Return POSIX pathconf information applicable to fifo's.
345 struct vop_pathconf_args /* {
352 switch (ap->a_name) {
354 *ap->a_retval = LINK_MAX;
357 *ap->a_retval = PIPE_BUF;
359 case _PC_CHOWN_RESTRICTED:
369 * Fifo advisory byte-level locks.
374 struct vop_advlock_args /* {
383 return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);