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.TH PTHREAD_RWLOCKATTR_GETPSHARED 3C "Mar 23, 2005"
.SH NAME
pthread_rwlockattr_getpshared, pthread_rwlockattr_setpshared \- get or set
process-shared attribute of read-write lock attributes object
.SH SYNOPSIS
.LP
.nf
cc -mt [ \fIflag\fR... ] \fIfile\fR... -lpthread [ \fIlibrary\fR... ]
#include <pthread.h>

\fBint\fR \fBpthread_rwlockattr_getpshared\fR(
     \fBconst pthread_rwlockattr_t *restrict\fR \fIattr\fR,
     \fBint *restrict\fR \fIpshared\fR);
.fi

.LP
.nf
\fBint\fR \fBpthread_rwlockattr_setpshared\fR(\fBpthread_rwlockattr_t *\fR\fIattr\fR,
     \fBint\fR \fIpshared\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fIprocess-shared\fR attribute is set to  \fBPTHREAD_PROCESS_SHARED\fR to
permit a read-write lock to be operated upon by any thread that has access to
the memory where the read-write lock is allocated,  even if the read-write lock
is allocated in memory that is shared by multiple processes. If the
\fIprocess-shared\fR attribute is  \fBPTHREAD_PROCESS_PRIVATE,\fR the
read-write lock will only be operated upon by threads created within the same
process as the thread that initialised the read-write lock; if threads of
differing processes attempt to operate on such a read-write lock, the behaviour
is undefined. The default value of the \fIprocess-shared\fR attribute is
\fBPTHREAD_PROCESS_PRIVATE.\fR
.sp
.LP
The \fBpthread_rwlockattr_getpshared()\fR function obtains the value of the
\fIprocess-shared\fR attribute from the initialised attributes object
referenced by \fIattr\fR. The  \fBpthread_rwlockattr_setpshared()\fR function
is used to set the \fIprocess-shared\fR attribute in an initialised attributes
object referenced by attr.
.SH RETURN VALUES
.sp
.LP
If successful, the  \fBpthread_rwlockattr_setpshared()\fR function returns
\fB0\fR. Otherwise, an error number is returned to indicate the error.
.sp
.LP
Upon successful completion, the  \fBpthread_rwlockattr_getpshared()\fR returns
\fB0\fR and stores the value of the \fIprocess-shared\fR attribute of
\fIattr\fR into the object referenced by the \fIpshared\fR parameter. Otherwise
an error number is returned to indicate the error.
.SH ERRORS
.sp
.LP
The \fBpthread_rwlockattr_getpshared()\fR and
\fBpthread_rwlockattr_setpshared()\fR functions will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIattr\fR  or \fIpshared\fR is invalid.
.RE

.SH ATTRIBUTES
.sp
.LP
See  \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBpthread_rwlock_init\fR(3C), \fBpthread_rwlock_rdlock\fR(3C),
\fBpthread_rwlock_unlock\fR(3C), \fBpthread_rwlock_wrlock\fR(3C),
\fBpthread_rwlockattr_init\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)