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.\"
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" A full copy of the text of the CDDL should have accompanied this
.\" source. A copy of the CDDL is also available via the Internet at
.\" http://www.illumos.org/license/CDDL.
.\"
.\"
.\" Copyright (c) 2014, Joyent, Inc.
.\"
.Dd "Dec 22, 2014"
.Dt PTHREAD_MUTEXATTR_GETROBUST 3C
.Os
.Sh NAME
.Nm pthread_mutexattr_getrobust ,
.Nm pthrad_mutexattr_setrobust
.Nd get and set the mutex robust attribute
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fo pthread_mutexattr_getrobust
.Fa "const pthread_mutexattr_t *attr"
.Fa "int *robust"
.Fc
.Ft int
.Fo pthread_mutexattr_setrobust
.Fa "pthread_mutexattr_t *attr"
.Fa "int robust"
.Fc
.Sh DESCRIPTION
The
.Fn pthread_mutexattr_getrobust
and
.Fn pthread_mtuexattr_setrobust
functions obtain and set a mutex's
.Em robust
attribute, putting it in, or obtaining it from
.Va robust .
The valid values for
.Va robust
include:
.Bl -tag -width Dv
.It Sy PTHREAD_MUTEX_STALLED
The mutex referred to by
.Va attr
is a traditional mutex.
When a thread holding an intra-process lock or a process holding an
inter-process lock crashes or terminates without unlocking the mutex, then the
lock will be
.Sy stalled .
For another thread or process to obtain the lock, something else must
unlock it.
.It Sy PTHREAD_MUTEX_ROBUST
The mutex referred to by
.Va attr
is considered a robust mutex.
When a process holding an inter-process lock crashes or terminates without
unlocking the mutex, the attempt to lock it will return
.Er EOWNERDEAD .
This allows the new owner the chance to fix the internal state and call
.Xr pthread_mutex_consistent 3C
prior to unlocking the lock, allowing normal operation to proceed.
Any crashes while in this state cause the next owner to obtain
.Er EOWNERDEAD .
.El
.Sh RETURN VALUES
Upon successful completion, the
.Fn pthread_mutexattr_getrobust
function will return
.Sy 0
and update
.Fa robust
with the current value of the robust attribute.
Upon successful completion, the
.Fn pthread_mutexattr_setrobust
function will return
.Sy 0
and update the robust property of the attributes pointed to by
.Va attr
to
.Va robust .
If either function fails, an error code will be returned to indicate the
error.
Valid errors are defined below.
.Sh ERRORS
The
.Fn pthread_mutexattr_getrobust
function will fail if:
.Bl -tag -width Er
.It Er EINVAL
.Va attr
is invalid or a null pointer,
.Va robust
is a null pointer.
.El
.Lp
The
.Fn pthread_mutexattr_setrobust
function will fail if:
.Bl -tag -width Er
.It Er EINVAL
.Va attr
is invalid or a null pointer,
.Va robust
is not one of
.Sy PTHREAD_MUTEX_STALLED
or
.Sy PTHREAD_MUTEX_ROBUST .
.El
.Sh INTERFACE STABILITY
.Sy Committed
.Sh MT-LEVEL
.Sy MT-Safe
.Sh SEE ALSO
.Xr pthread_mutex_consistent 3C ,
.Xr pthread 3HEAD ,
.Xr libpthread 3LIB ,
.Xr attributes 5 ,
.Xr mutex 5
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