1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
|
/*-
* Copyright (c) 1990, 1993, 1995
* The Regents of the University of California.
* Copyright (c) 2005 Robert N. M. Watson
* Copyright (c) 2012 Giovanni Trematerra
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/event.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/malloc.h>
#include <sys/selinfo.h>
#include <sys/pipe.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/un.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <fs/fifofs/fifo.h>
/*
* This structure is associated with the FIFO vnode and stores
* the state associated with the FIFO.
* Notes about locking:
* - fi_pipe is invariant since init time.
* - fi_readers and fi_writers are protected by the vnode lock.
* - fi_wgen is protected by the pipe mutex.
*/
struct fifoinfo {
struct pipe *fi_pipe;
long fi_readers;
long fi_writers;
int fi_wgen;
};
static vop_print_t fifo_print;
static vop_open_t fifo_open;
static vop_close_t fifo_close;
static vop_pathconf_t fifo_pathconf;
static vop_advlock_t fifo_advlock;
struct vop_vector fifo_specops = {
.vop_default = &default_vnodeops,
.vop_advlock = fifo_advlock,
.vop_close = fifo_close,
.vop_create = VOP_PANIC,
.vop_getattr = VOP_EBADF,
.vop_ioctl = VOP_PANIC,
.vop_kqfilter = VOP_PANIC,
.vop_link = VOP_PANIC,
.vop_mkdir = VOP_PANIC,
.vop_mknod = VOP_PANIC,
.vop_open = fifo_open,
.vop_pathconf = fifo_pathconf,
.vop_print = fifo_print,
.vop_read = VOP_PANIC,
.vop_readdir = VOP_PANIC,
.vop_readlink = VOP_PANIC,
.vop_reallocblks = VOP_PANIC,
.vop_reclaim = VOP_NULL,
.vop_remove = VOP_PANIC,
.vop_rename = VOP_PANIC,
.vop_rmdir = VOP_PANIC,
.vop_setattr = VOP_EBADF,
.vop_symlink = VOP_PANIC,
.vop_write = VOP_PANIC,
};
/*
* Dispose of fifo resources.
*/
static void
fifo_cleanup(struct vnode *vp)
{
struct fifoinfo *fip;
ASSERT_VOP_ELOCKED(vp, "fifo_cleanup");
fip = vp->v_fifoinfo;
if (fip->fi_readers == 0 && fip->fi_writers == 0) {
vp->v_fifoinfo = NULL;
pipe_dtor(fip->fi_pipe);
free(fip, M_VNODE);
}
}
/*
* Open called to set up a new instance of a fifo or
* to find an active instance of a fifo.
*/
/* ARGSUSED */
static int
fifo_open(ap)
struct vop_open_args /* {
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct thread *a_td;
struct file *a_fp;
} */ *ap;
{
struct vnode *vp;
struct file *fp;
struct thread *td;
struct fifoinfo *fip;
struct pipe *fpipe;
int error;
vp = ap->a_vp;
fp = ap->a_fp;
td = ap->a_td;
ASSERT_VOP_ELOCKED(vp, "fifo_open");
if (fp == NULL)
return (EINVAL);
if ((fip = vp->v_fifoinfo) == NULL) {
error = pipe_named_ctor(&fpipe, td);
if (error != 0)
return (error);
fip = malloc(sizeof(*fip), M_VNODE, M_WAITOK);
fip->fi_pipe = fpipe;
fip->fi_wgen = fip->fi_readers = fip->fi_writers = 0;
KASSERT(vp->v_fifoinfo == NULL, ("fifo_open: v_fifoinfo race"));
vp->v_fifoinfo = fip;
}
fpipe = fip->fi_pipe;
KASSERT(fpipe != NULL, ("fifo_open: pipe is NULL"));
/*
* Use the pipe mutex here, in addition to the vnode lock,
* in order to allow vnode lock dropping before msleep() calls
* and still avoiding missed wakeups.
*/
PIPE_LOCK(fpipe);
if (ap->a_mode & FREAD) {
fip->fi_readers++;
if (fip->fi_readers == 1) {
fpipe->pipe_state &= ~PIPE_EOF;
if (fip->fi_writers > 0)
wakeup(&fip->fi_writers);
}
fp->f_seqcount = fip->fi_wgen - fip->fi_writers;
}
if (ap->a_mode & FWRITE) {
if ((ap->a_mode & O_NONBLOCK) && fip->fi_readers == 0) {
PIPE_UNLOCK(fpipe);
if (fip->fi_writers == 0)
fifo_cleanup(vp);
return (ENXIO);
}
fip->fi_writers++;
if (fip->fi_writers == 1) {
fpipe->pipe_state &= ~PIPE_EOF;
if (fip->fi_readers > 0)
wakeup(&fip->fi_readers);
}
}
if ((ap->a_mode & O_NONBLOCK) == 0) {
if ((ap->a_mode & FREAD) && fip->fi_writers == 0) {
VOP_UNLOCK(vp, 0);
error = msleep(&fip->fi_readers, PIPE_MTX(fpipe),
PDROP | PCATCH | PSOCK, "fifoor", 0);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (error) {
fip->fi_readers--;
if (fip->fi_readers == 0) {
PIPE_LOCK(fpipe);
fpipe->pipe_state |= PIPE_EOF;
if (fpipe->pipe_state & PIPE_WANTW)
wakeup(fpipe);
PIPE_UNLOCK(fpipe);
fifo_cleanup(vp);
}
return (error);
}
PIPE_LOCK(fpipe);
/*
* We must have got woken up because we had a writer.
* That (and not still having one) is the condition
* that we must wait for.
*/
}
if ((ap->a_mode & FWRITE) && fip->fi_readers == 0) {
VOP_UNLOCK(vp, 0);
error = msleep(&fip->fi_writers, PIPE_MTX(fpipe),
PDROP | PCATCH | PSOCK, "fifoow", 0);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
if (error) {
fip->fi_writers--;
if (fip->fi_writers == 0) {
PIPE_LOCK(fpipe);
fpipe->pipe_state |= PIPE_EOF;
if (fpipe->pipe_state & PIPE_WANTR)
wakeup(fpipe);
fip->fi_wgen++;
PIPE_UNLOCK(fpipe);
fifo_cleanup(vp);
}
return (error);
}
/*
* We must have got woken up because we had
* a reader. That (and not still having one)
* is the condition that we must wait for.
*/
PIPE_LOCK(fpipe);
}
}
PIPE_UNLOCK(fpipe);
KASSERT(fp != NULL, ("can't fifo/vnode bypass"));
KASSERT(fp->f_ops == &badfileops, ("not badfileops in fifo_open"));
finit(fp, fp->f_flag, DTYPE_FIFO, fpipe, &pipeops);
return (0);
}
/*
* Device close routine
*/
/* ARGSUSED */
static int
fifo_close(ap)
struct vop_close_args /* {
struct vnode *a_vp;
int a_fflag;
struct ucred *a_cred;
struct thread *a_td;
} */ *ap;
{
struct vnode *vp;
struct fifoinfo *fip;
struct pipe *cpipe;
vp = ap->a_vp;
fip = vp->v_fifoinfo;
cpipe = fip->fi_pipe;
ASSERT_VOP_ELOCKED(vp, "fifo_close");
if (ap->a_fflag & FREAD) {
fip->fi_readers--;
if (fip->fi_readers == 0) {
PIPE_LOCK(cpipe);
cpipe->pipe_state |= PIPE_EOF;
if (cpipe->pipe_state & PIPE_WANTW)
wakeup(cpipe);
PIPE_UNLOCK(cpipe);
}
}
if (ap->a_fflag & FWRITE) {
fip->fi_writers--;
if (fip->fi_writers == 0) {
PIPE_LOCK(cpipe);
cpipe->pipe_state |= PIPE_EOF;
if (cpipe->pipe_state & PIPE_WANTR)
wakeup(cpipe);
fip->fi_wgen++;
PIPE_UNLOCK(cpipe);
}
}
fifo_cleanup(vp);
return (0);
}
/*
* Print out internal contents of a fifo vnode.
*/
int
fifo_printinfo(vp)
struct vnode *vp;
{
register struct fifoinfo *fip = vp->v_fifoinfo;
if (fip == NULL){
printf(", NULL v_fifoinfo");
return (0);
}
printf(", fifo with %ld readers and %ld writers",
fip->fi_readers, fip->fi_writers);
return (0);
}
/*
* Print out the contents of a fifo vnode.
*/
static int
fifo_print(ap)
struct vop_print_args /* {
struct vnode *a_vp;
} */ *ap;
{
printf(" ");
fifo_printinfo(ap->a_vp);
printf("\n");
return (0);
}
/*
* Return POSIX pathconf information applicable to fifo's.
*/
static int
fifo_pathconf(ap)
struct vop_pathconf_args /* {
struct vnode *a_vp;
int a_name;
int *a_retval;
} */ *ap;
{
switch (ap->a_name) {
case _PC_LINK_MAX:
*ap->a_retval = LINK_MAX;
return (0);
case _PC_PIPE_BUF:
*ap->a_retval = PIPE_BUF;
return (0);
case _PC_CHOWN_RESTRICTED:
*ap->a_retval = 1;
return (0);
default:
return (EINVAL);
}
/* NOTREACHED */
}
/*
* Fifo advisory byte-level locks.
*/
/* ARGSUSED */
static int
fifo_advlock(ap)
struct vop_advlock_args /* {
struct vnode *a_vp;
caddr_t a_id;
int a_op;
struct flock *a_fl;
int a_flags;
} */ *ap;
{
return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
}
int
fifo_iseof(struct file *fp)
{
struct fifoinfo *fip;
KASSERT(fp->f_vnode != NULL, ("fifo_iseof: no vnode info"));
KASSERT(fp->f_vnode->v_fifoinfo != NULL, ("fifo_iseof: no fifoinfo"));
fip = fp->f_vnode->v_fifoinfo;
PIPE_LOCK_ASSERT(fip->fi_pipe, MA_OWNED);
return (fp->f_seqcount == fip->fi_wgen);
}
|