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 /*
  32  * This module switches the read and write flush bits for each
  33  * M_FLUSH control message it receives. It's intended usage is to
  34  * properly flush a STREAMS-based pipe.
  35  */
  36 #include <sys/types.h>
  37 #include <sys/param.h>
  38 #include <sys/errno.h>
  39 #include <sys/stream.h>
  40 #include <sys/stropts.h>
  41 
  42 #include <sys/conf.h>
  43 #include <sys/modctl.h>
  44 
  45 /*ARGSUSED*/
  46 static int
  47 pipeopen(queue_t *rqp, dev_t *devp, int flag, int sflag, cred_t *crp)
  48 {
  49         qprocson(rqp);
  50         return (0);
  51 }
  52 
  53 /*ARGSUSED*/
  54 static int
  55 pipeclose(queue_t *q, int cflag, cred_t *crp)
  56 {
  57         qprocsoff(q);
  58         return (0);
  59 }
  60 
  61 /*
  62  * Use same put procedure for write and read queues.
  63  * If mp is an M_FLUSH message, switch the FLUSHW to FLUSHR and
  64  * the FLUSHR to FLUSHW and send the message on.  If mp is not an
  65  * M_FLUSH message, send it on with out processing.
  66  */
  67 static int
  68 pipeput(queue_t *qp, mblk_t *mp)
  69 {
  70         switch (mp->b_datap->db_type) {
  71         case M_FLUSH:
  72                 if (!(*mp->b_rptr & FLUSHR && *mp->b_rptr & FLUSHW)) {
  73                         if (*mp->b_rptr & FLUSHW) {
  74                                 *mp->b_rptr |= FLUSHR;
  75                                 *mp->b_rptr &= ~FLUSHW;
  76                         } else {
  77                                 *mp->b_rptr |= FLUSHW;
  78                                 *mp->b_rptr &= ~FLUSHR;
  79                         }
  80                 }
  81                 break;
  82 
  83         default:
  84                 break;
  85         }
  86         putnext(qp, mp);
  87         return (0);
  88 }
  89 
  90 static struct module_info pipe_info = {
  91         1003, "pipemod", 0, INFPSZ, STRHIGH, STRLOW
  92 };
  93 
  94 static struct qinit piperinit = {
  95         pipeput, NULL, pipeopen, pipeclose, NULL, &pipe_info, NULL
  96 };
  97 
  98 static struct qinit pipewinit = {
  99         pipeput, NULL, NULL, NULL, NULL, &pipe_info, NULL
 100 };
 101 
 102 static struct streamtab pipeinfo = { &piperinit, &pipewinit, NULL, NULL };
 103 
 104 static struct fmodsw fsw = {
 105         "pipemod",
 106         &pipeinfo,
 107         D_NEW | D_MP
 108 };
 109 
 110 static struct modlstrmod modlstrmod = {
 111         &mod_strmodops, "pipe flushing module", &fsw
 112 };
 113 
 114 static struct modlinkage modlinkage = {
 115         MODREV_1, { &modlstrmod, NULL }
 116 };
 117 
 118 int
 119 _init(void)
 120 {
 121         return (mod_install(&modlinkage));
 122 }
 123 
 124 int
 125 _fini(void)
 126 {
 127         return (mod_remove(&modlinkage));
 128 }
 129 
 130 int
 131 _info(struct modinfo *modinfop)
 132 {
 133         return (mod_info(&modlinkage, modinfop));
 134 }