1.\" Copyright (c) 1998 Alex Nash 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.Dd August 17, 2018 26.Dt PTHREAD_RWLOCK_INIT 3 27.Os 28.Sh NAME 29.Nm pthread_rwlock_init 30.Nd initialize a read/write lock 31.Sh LIBRARY 32.Lb libpthread 33.Sh SYNOPSIS 34.In pthread.h 35.Ft int 36.Fn pthread_rwlock_init "pthread_rwlock_t *restrict lock" "const pthread_rwlockattr_t *restrict attr" 37.Sh DESCRIPTION 38The 39.Fn pthread_rwlock_init 40function is used to initialize a read/write lock, with attributes 41specified by 42.Fa attr . 43If 44.Fa attr 45is NULL, the default read/write lock attributes are used. 46.Pp 47The results of calling 48.Fn pthread_rwlock_init 49with an already initialized lock are undefined. 50.Sh RETURN VALUES 51If successful, the 52.Fn pthread_rwlock_init 53function will return zero. 54Otherwise an error number will be returned 55to indicate the error. 56.Sh ERRORS 57The 58.Fn pthread_rwlock_init 59function will fail if: 60.Bl -tag -width Er 61.It Bq Er EAGAIN 62The system lacked the necessary resources (other than memory) to 63initialize the lock. 64.It Bq Er ENOMEM 65Insufficient memory exists to initialize the lock. 66.It Bq Er EPERM 67The caller does not have sufficient privilege to perform the 68operation. 69.El 70.Pp 71The 72.Fn pthread_rwlock_init 73function may fail if: 74.Bl -tag -width Er 75.It Bq Er EBUSY 76The system has detected an attempt to re-initialize the object 77referenced by 78.Fa lock , 79a previously initialized but not yet destroyed read/write lock. 80.It Bq Er EINVAL 81The value specified by 82.Fa attr 83is invalid. 84.El 85.Sh SEE ALSO 86.Xr pthread_rwlock_destroy 3 , 87.Xr pthread_rwlockattr_init 3 , 88.Xr pthread_rwlockattr_setpshared 3 89.Sh STANDARDS 90The 91.Fn pthread_rwlock_init 92function is expected to conform to 93.St -susv2 . 94.Sh HISTORY 95The 96.Fn pthread_rwlock_init 97function first appeared in 98.Fx 3.0 . 99