1.\" $NetBSD: pthread_mutexattr.3,v 1.3 2003/07/04 08:36:06 wiz Exp $ 2.\" 3.\" Copyright (c) 2002 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. Neither the name of The NetBSD Foundation nor the names of its 14.\" contributors may be used to endorse or promote products derived 15.\" from this software without specific prior written permission. 16.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26.\" POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>. 29.\" All rights reserved. 30.\" 31.\" Redistribution and use in source and binary forms, with or without 32.\" modification, are permitted provided that the following conditions 33.\" are met: 34.\" 1. Redistributions of source code must retain the above copyright 35.\" notice(s), this list of conditions and the following disclaimer as 36.\" the first lines of this file unmodified other than the possible 37.\" addition of one or more copyright notices. 38.\" 2. Redistributions in binary form must reproduce the above copyright 39.\" notice(s), this list of conditions and the following disclaimer in 40.\" the documentation and/or other materials provided with the 41.\" distribution. 42.\" 43.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 44.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 45.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 46.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 47.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 48.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 49.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 50.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 51.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 52.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 53.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 54.\" 55.\" $FreeBSD: src/lib/libpthread/man/pthread_mutexattr.3,v 1.8 2002/09/16 19:29:29 mini Exp $ 56.Dd January 30, 2003 57.Dt PTHREAD_MUTEXATTR 3 58.Os 59.Sh NAME 60.Nm pthread_mutexattr_init , 61.Nm pthread_mutexattr_destroy , 62.\" .Nm pthread_mutexattr_setprioceiling , 63.\" .Nm pthread_mutexattr_getprioceiling , 64.\" .Nm pthread_mutexattr_setprotocol , 65.\" .Nm pthread_mutexattr_getprotocol , 66.Nm pthread_mutexattr_settype , 67.Nm pthread_mutexattr_gettype 68.Nd mutex attribute operations 69.Sh LIBRARY 70.Lb libpthread 71.Sh SYNOPSIS 72.In pthread.h 73.Ft int 74.Fn pthread_mutexattr_init "pthread_mutexattr_t *attr" 75.Ft int 76.Fn pthread_mutexattr_destroy "pthread_mutexattr_t *attr" 77.\" .Ft int 78.\" .Fn pthread_mutexattr_setprioceiling "pthread_mutexattr_t *attr" "int prioceiling" 79.\" .Ft int 80.\" .Fn pthread_mutexattr_getprioceiling "pthread_mutexattr_t *attr" "int *prioceiling" 81.\" .Ft int 82.\" .Fn pthread_mutexattr_setprotocol "pthread_mutexattr_t *attr" "int protocol" 83.\" .Ft int 84.\" .Fn pthread_mutexattr_getprotocol "pthread_mutexattr_t *attr" "int *protocol" 85.Ft int 86.Fn pthread_mutexattr_settype "pthread_mutexattr_t *attr" "int type" 87.Ft int 88.Fn pthread_mutexattr_gettype "pthread_mutexattr_t *attr" "int *type" 89.Sh DESCRIPTION 90Mutex attributes are used to specify parameters to 91.Fn pthread_mutex_init . 92One attribute object can be used in multiple calls to 93.Fn pthread_mutex_init , 94with or without modifications between calls. 95.Pp 96The 97.Fn pthread_mutexattr_init 98function initializes 99.Fa attr 100with all the default mutex attributes. 101.Pp 102The 103.Fn pthread_mutexattr_destroy 104function destroys 105.Fa attr . 106.Pp 107The 108.Fn pthread_mutexattr_settype 109functions set the mutex type value of the attribute. Valid mutex types are: 110.Dv PTHREAD_MUTEX_NORMAL , 111.Dv PTHREAD_MUTEX_ERRORCHECK , 112.Dv PTHREAD_MUTEX_RECURSIVE , 113and 114.Dv PTHREAD_MUTEX_DEFAULT . 115The default mutex type for 116.Fn pthread_mutexaddr_init 117is 118.Dv PTHREAD_MUTEX_DEFAULT . 119.Pp 120.Dv PTHREAD_MUXEX_NORMAL 121mutexes do not check for usage errors. 122.Dv PTHREAD_MUTEX_NORMAL 123mutexes will deadlock if reentered, and result in undefined behavior if a 124locked mutex is unlocked by another thread. Attempts to unlock an already 125unlocked 126.Dv PTHREAD_MUTEX_NORMAL 127mutex will result in undefined behavior. 128.Pp 129.Dv PTHREAD_MUTEX_ERRORCHECK 130mutexes do check for usage errors. 131If an attempt is made to relock a 132.Dv PTHREAD_MUTEX_ERRORCHECK 133mutex without first dropping the lock an error will be returned. If a thread 134attempts to unlock a 135.Dv PTHREAD_MUTEX_ERRORCHECK 136mutex that is locked by another thread, an error will be returned. If a 137thread attemps to unlock a 138.Dv PTHREAD_MUTEX_ERRORCHECK 139thread that is unlocked, an error will be 140returned. 141.Pp 142.Dv PTHREAD_MUTEX_RECURSIVE 143mutexes allow recursive locking. 144An attempt to relock a 145.Dv PTHREAD_MUTEX_RECURSIVE 146mutex that is already locked by the same thread succeeds. An equivalent 147number of 148.Xr pthread_mutex_unlock 3 149calls are needed before the mutex will wake another thread waiting on this 150lock. If a thread attempts to unlock a 151.Dv PTHREAD_MUTEX_RECURSIVE 152mutex that is locked by another thread, an error will be returned. If a thread attemps to unlock a 153.Dv PTHREAD_MUTEX_RECURSIVE 154thread that is unlocked, an error will be returned. 155.Pp 156.Dv PTHREAD_MUTEX_DEFAULT 157mutexes result in undefined behavior if reentered. 158Unlocking a 159.Dv PTHREAD_MUTEX_DEFAULT 160mutex locked by another thread will result in undefined behavior. Attempts to unlock an already 161unlocked 162.Dv PTHREAD_MUTEX_DEFAULT 163mutex will result in undefined behavior. 164.Pp 165.Fn pthread_mutexattr_gettype 166functions copy the type value of the attribute to the location pointed to by the second parameter. 167.Sh RETURN VALUES 168If successful, these functions return 0. 169Otherwise, an error number is returned to indicate the error. 170.Sh ERRORS 171.Fn pthread_mutexattr_init 172shall fail if: 173.Bl -tag -width Er 174.It Bq Er ENOMEM 175Insufficent memory exists to initialize the mutex attributes object. 176.El 177.Pp 178.Fn pthread_mutexattr_settype 179shall fail if: 180.Bl -tag -width Er 181.It Bq Er EINVAL 182The value specified by 183.Fa type 184is invalid. 185.El 186.Pp 187.\" .Fn pthread_mutexattr_setprioceiling 188.\" may fail if: 189.\" .Bl -tag -width Er 190.\" .It Bq Er EINVAL 191.\" Invalid value for 192.\" .Fa attr , 193.\" or invalid value for 194.\" .Fa prioceiling . 195.\" .El 196.\" .Pp 197.\" .Fn pthread_mutexattr_getprioceiling 198.\" may fail if: 199.\" .Bl -tag -width Er 200.\" .It Bq Er EINVAL 201.\" Invalid value for 202.\" .Fa attr . 203.\" .El 204.\" .Pp 205.\" .Fn pthread_mutexattr_setprotocol 206.\" may fail if: 207.\" .Bl -tag -width Er 208.\" .It Bq Er EINVAL 209.\" Invalid value for 210.\" .Fa attr , 211.\" or invalid value for 212.\" .Fa protocol . 213.\" .El 214.\" .Pp 215.\" .Fn pthread_mutexattr_getprotocol 216.\" may fail if: 217.\" .Bl -tag -width Er 218.\" .It Bq Er EINVAL 219.\" Invalid value for 220.\" .Fa attr . 221.\" .El 222.\" .Pp 223.Pp 224.Fn pthread_mutexattr_destroy , 225.Fn pthread_mutexattr_settype , 226and 227.Fn pthread_mutexattr_gettype 228may fail if: 229.Bl -tag -width Er 230.It Bq Er EINVAL 231Invalid value for 232.Fa attr . 233.El 234.Sh SEE ALSO 235.Xr pthread_mutex_init 3 236.Sh STANDARDS 237.Fn pthread_mutexattr_init , 238.Fn pthread_mutexattr_destroy , 239.Fn pthread_mutexattr_settype , 240.\" .Fn pthread_mutexattr_setprioceiling , 241.\" .Fn pthread_mutexattr_getprioceiling , 242.\" .Fn pthread_mutexattr_setprotocol , 243.\" .Fn pthread_mutexattr_getprotocol , 244and 245.Fn pthread_mutexattr_gettype 246conform to 247.St -p1003.1-96 . 248