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	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	.\" $FreeBSD$
	26	.\"
	27	.Dd August 4, 1998
	28	.Dt PTHREAD_RWLOCK_INIT 3
	29	.Os
	30	.Sh NAME
	31	.Nm pthread_rwlock_init
	32	.Nd initialize a read/write lock
	33	.Sh SYNOPSIS
	34	.In pthread.h
	35	.Ft int
	36	.Fn pthread_rwlock_init "pthread_rwlock_t lock" "const pthread_rwlockattr_t attr"
	37	.Sh DESCRIPTION
	38	The
	39	.Fn pthread_rwlock_init
	40	function is used to initialize a read/write lock, with attributes
	41	specified by
	42	.Fa attr .
	43	If
	44	.Fa attr
	45	is NULL, the default read/write lock attributes are used.
	46	.Pp
	47	The results of calling
	48	.Fn pthread_rwlock_init
	49	with an already initialized lock are undefined.
	50	.Sh RETURN VALUES
	51	If successful, the
	52	.Fn pthread_rwlock_init
	53	function will return zero.
	54	Otherwise an error number will be returned
	55	to indicate the error.
	56	.Sh ERRORS
	57	The
	58	.Fn pthread_rwlock_init
	59	function will fail if:
	60	.Bl -tag -width Er
	61	.It Bq Er EAGAIN
	62	The system lacked the necessary resources (other than memory) to
	63	initialize the lock.
	64	.It Bq Er ENOMEM
	65	Insufficient memory exists to initialize the lock.
	66	.It Bq Er EPERM
	67	The caller does not have sufficient privilege to perform the
	68	operation.
	69	.El
	70	.Pp
	71	The
	72	.Fn pthread_rwlock_init
	73	function may fail if:
	74	.Bl -tag -width Er
	75	.It Bq Er EBUSY
	76	The system has detected an attempt to re-initialize the object
	77	referenced by
	78	.Fa lock ,
	79	a previously initialized but not yet destroyed read/write lock.
	80	.It Bq Er EINVAL
	81	The value specified by
	82	.Fa attr
	83	is 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
	90	The
	91	.Fn pthread_rwlock_init
	92	function is expected to conform to
	93	.St -susv2 .
	94	.Sh HISTORY
	95	The
	96	.Fn pthread_rwlock_init
	97	function first appeared in
	98	.Fx 3.0 .
	99	.Sh BUGS
	100	The PTHREAD_PROCESS_SHARED attribute is not supported.