1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright (c) 1997, by Sun Microsystems, Inc.
24 * All rights reserved.
25 */
26
27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
28 /* All Rights Reserved */
29
30 /*
31 * This module switches the read and write flush bits for each
32 * M_FLUSH control message it receives. It's intended usage is to
33 * properly flush a STREAMS-based pipe.
34 */
35 #include <sys/types.h>
36 #include <sys/param.h>
37 #include <sys/errno.h>
38 #include <sys/stream.h>
39 #include <sys/stropts.h>
40
41 #include <sys/conf.h>
42 #include <sys/modctl.h>
43
44 /*ARGSUSED*/
45 static int
pipeopen(queue_t * rqp,dev_t * devp,int flag,int sflag,cred_t * crp)46 pipeopen(queue_t *rqp, dev_t *devp, int flag, int sflag, cred_t *crp)
47 {
48 qprocson(rqp);
49 return (0);
50 }
51
52 /*ARGSUSED*/
53 static int
pipeclose(queue_t * q,int cflag,cred_t * crp)54 pipeclose(queue_t *q, int cflag, cred_t *crp)
55 {
56 qprocsoff(q);
57 return (0);
58 }
59
60 /*
61 * Use same put procedure for write and read queues.
62 * If mp is an M_FLUSH message, switch the FLUSHW to FLUSHR and
63 * the FLUSHR to FLUSHW and send the message on. If mp is not an
64 * M_FLUSH message, send it on with out processing.
65 */
66 static int
pipeput(queue_t * qp,mblk_t * mp)67 pipeput(queue_t *qp, mblk_t *mp)
68 {
69 switch (mp->b_datap->db_type) {
70 case M_FLUSH:
71 if (!(*mp->b_rptr & FLUSHR && *mp->b_rptr & FLUSHW)) {
72 if (*mp->b_rptr & FLUSHW) {
73 *mp->b_rptr |= FLUSHR;
74 *mp->b_rptr &= ~FLUSHW;
75 } else {
76 *mp->b_rptr |= FLUSHW;
77 *mp->b_rptr &= ~FLUSHR;
78 }
79 }
80 break;
81
82 default:
83 break;
84 }
85 putnext(qp, mp);
86 return (0);
87 }
88
89 static struct module_info pipe_info = {
90 1003, "pipemod", 0, INFPSZ, STRHIGH, STRLOW
91 };
92
93 static struct qinit piperinit = {
94 pipeput, NULL, pipeopen, pipeclose, NULL, &pipe_info, NULL
95 };
96
97 static struct qinit pipewinit = {
98 pipeput, NULL, NULL, NULL, NULL, &pipe_info, NULL
99 };
100
101 static struct streamtab pipeinfo = { &piperinit, &pipewinit, NULL, NULL };
102
103 static struct fmodsw fsw = {
104 "pipemod",
105 &pipeinfo,
106 D_NEW | D_MP
107 };
108
109 static struct modlstrmod modlstrmod = {
110 &mod_strmodops, "pipe flushing module", &fsw
111 };
112
113 static struct modlinkage modlinkage = {
114 MODREV_1, &modlstrmod, NULL
115 };
116
117 int
_init(void)118 _init(void)
119 {
120 return (mod_install(&modlinkage));
121 }
122
123 int
_fini(void)124 _fini(void)
125 {
126 return (mod_remove(&modlinkage));
127 }
128
129 int
_info(struct modinfo * modinfop)130 _info(struct modinfo *modinfop)
131 {
132 return (mod_info(&modlinkage, modinfop));
133 }
134