.\" $NetBSD: pthread_rwlock_init.3,v 1.7 2005/06/17 18:26:53 wiz Exp $
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.\" Copyright (c) 1998 Alex Nash
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" $FreeBSD: src/lib/libpthread/man/pthread_rwlock_init.3,v 1.6 2002/09/16 19:29:29 mini Exp $
.\"
.Dd January 30, 2003
.Dt PTHREAD_RWLOCK_INIT 3
.Os
.Sh NAME
.Nm pthread_rwlock_init
.Nd initialize a read/write lock
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_rwlock_init "pthread_rwlock_t * restrict lock" "const pthread_rwlockattr_t * restrict attr"
.Sh DESCRIPTION
The
.Fn pthread_rwlock_init
function is used to initialize a read/write lock, with attributes
specified by
.Fa attr .
If
.Fa attr
is NULL, the default read/write lock attributes are used.
.Pp
The results of calling
.Fn pthread_rwlock_init
with an already initialized lock are undefined.
.Sh RETURN VALUES
If successful, the
.Fn pthread_rwlock_init
function will return zero.
Otherwise an error number will be returned to indicate the error.
.Sh ERRORS
The
.Fn pthread_rwlock_init
function shall fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
The system lacks the resources to initialize another read-write lock.
.It Bq Er ENOMEM
Insufficient memory exists to initialize the read-write lock.
.El
.Pp
The
.Fn pthread_rwlock_init
function may fail if:
.Bl -tag -width Er
.It Bq Er EBUSY
The system has detected an attempt to re-initialize the object
referenced by
.Fa lock ,
a previously initialized but not yet destroyed read/write lock.
.It Bq Er EINVAL
The value specified by
.Fa attr
is invalid.
.El
.Sh SEE ALSO
.Xr pthread_rwlock_destroy 3 ,
.Xr pthread_rwlock_rdlock 3 ,
.Xr pthread_rwlock_unlock 3 ,
.Xr pthread_rwlock_wrlock 3
.Sh STANDARDS
.Fn pthread_rwlock_init
conforms to
.St -p1003.1-96 .
.Sh BUGS
The PTHREAD_PROCESS_SHARED attribute is not supported.