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.TH PTHREAD_MUTEXATTR_GETTYPE "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH PROLOG

This manual page is part of the POSIX Programmer's Manual.

The Linux implementation of this interface may differ (consult

the corresponding Linux manual page for details of Linux behavior),

or the interface may not be implemented on Linux.

.SH NAME

pthread_mutexattr_gettype,

pthread_mutexattr_settype

\(em get and set the mutex type attribute

.SH SYNOPSIS

.LP

.nf

#include <pthread.h>

.P

int pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict \fIattr\fP,

    int *restrict \fItype\fP);

int pthread_mutexattr_settype(pthread_mutexattr_t *\fIattr\fP, int \fItype\fP);

.fi

.SH DESCRIPTION

The

\fIpthread_mutexattr_gettype\fR()

and

\fIpthread_mutexattr_settype\fR()

functions, respectively, shall get and set the mutex

.IR type

attribute. This attribute is set in the

.IR type

parameter to these functions. The default value of the

.IR type

attribute is PTHREAD_MUTEX_DEFAULT.

.P

The type of mutex is contained in the

.IR type

attribute of the mutex attributes. Valid mutex types include:

.sp

.RS

PTHREAD_MUTEX_NORMAL

PTHREAD_MUTEX_ERRORCHECK

PTHREAD_MUTEX_RECURSIVE

PTHREAD_MUTEX_DEFAULT

.RE

.P

The mutex type affects the behavior of calls which lock and unlock the

mutex. See

.IR "\fIpthread_mutex_lock\fR\^(\|)"

for details. An implementation may map PTHREAD_MUTEX_DEFAULT to one of

the other mutex types.

.P

The behavior is undefined if the value specified by the

.IR attr

argument to

\fIpthread_mutexattr_gettype\fR()

or

\fIpthread_mutexattr_settype\fR()

does not refer to an initialized mutex attributes object.

.SH "RETURN VALUE"

Upon successful completion, the

\fIpthread_mutexattr_gettype\fR()

function shall return zero and store the value of the

.IR type

attribute of

.IR attr

into the object referenced by the

.IR type

parameter. Otherwise, an error shall be returned to indicate the error.

.P

If successful, the

\fIpthread_mutexattr_settype\fR()

function shall return zero; otherwise, an error number shall be

returned to indicate the error.

.SH ERRORS

The

\fIpthread_mutexattr_settype\fR()

function shall fail if:

.TP

.BR EINVAL

The value

.IR type

is invalid.

.P

These functions shall not return an error code of

.BR [EINTR] .

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

It is advised that an application should not use a

PTHREAD_MUTEX_RECURSIVE mutex with condition variables

because the implicit unlock performed for a

\fIpthread_cond_timedwait\fR()

or

\fIpthread_cond_wait\fR()

may not actually release the mutex (if it had been locked multiple

times). If this happens, no other thread can satisfy the condition of

the predicate.

.SH RATIONALE

If an implementation detects that the value specified by the

.IR attr

argument to

\fIpthread_mutexattr_gettype\fR()

or

\fIpthread_mutexattr_settype\fR()

does not refer to an initialized mutex attributes object, it is

recommended that the function should fail and report an

.BR [EINVAL] 

error.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIpthread_cond_timedwait\fR\^(\|)",

.IR "\fIpthread_mutex_lock\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "\fB<pthread.h>\fP"

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology

-- Portable Operating System Interface (POSIX), The Open Group Base

Specifications Issue 7, Copyright (C) 2013 by the Institute of

Electrical and Electronics Engineers, Inc and The Open Group.

(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the

event of any discrepancy between this version and the original IEEE and

The Open Group Standard, the original IEEE and The Open Group Standard

is the referee document. The original Standard can be obtained online at

http://www.unix.org/online.html .

Any typographical or formatting errors that appear

in this page are most likely

to have been introduced during the conversion of the source files to

man page format. To report such errors, see

https://www.kernel.org/doc/man-pages/reporting_bugs.html .