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.TH PTHREAD_MUTEXATTR_GETPSHARED 3 2017-09-13 "Linux" "Linux Programmer's Manual"

.SH NAME

pthread_mutexattr_getpshared, pthread_mutexattr_setpshared \- get/set

process-shared mutex attribute

.SH SYNOPSIS

.nf

.B #include <pthread.h>

.PP

.BI "int pthread_mutexattr_getpshared(const pthread_mutexattr_t *" attr ,

.BI "                                 int *" pshared );

.BI "int pthread_mutexattr_setpshared(pthread_mutexattr_t *" attr ,

.BI "                                 int " pshared );

.fi

.PP

Compile and link with \fI\-pthread\fP.

.SH DESCRIPTION

These functions get and set the process-shared attribute

in a mutex attributes object.

This attribute must be appropriately set to ensure correct,

efficient operation of a mutex created using this attributes object.

.PP

The process-shared attribute can have one of the following values:

.TP

.B PTHREAD_PROCESS_PRIVATE

Mutexes created with this attributes object are to be shared

only among threads in the same process that initialized the mutex.

This is the default value for the process-shared mutex attribute.

.TP

.B PTHREAD_PROCESS_SHARED

Mutexes created with this attributes object can be shared between

any threads that have access to the memory containing the object,

including threads in different processes.

.PP

.BR pthread_mutexattr_getpshared ()

places the value of the process-shared attribute of

the mutex attributes object referred to by

.IR attr

in the location pointed to by

.IR pshared .

.PP

.BR pthread_mutexattr_setpshared ()

sets the value of the process-shared attribute of

the mutex attributes object referred to by

.IR attr

to the value specified in

.BR pshared .

.PP

If

.I attr

does not refer to an initialized mutex attributes object,

the behavior is undefined.

.SH RETURN VALUE

On success, these functions return 0.

On error, they return a positive error number.

.SH ERRORS

.BR pthread_mutexattr_setpshared ()

can fail with the following errors:

.TP

.B EINVAL

The value specified in

.I pshared

is invalid.

.TP

.B ENOTSUP

.I pshared is

.BR PTHREAD_PROCESS_SHARED

but the implementation does not support process-shared mutexes.

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH SEE ALSO

.ad l

.nh

.BR pthread_mutexattr_init (3),

.BR pthreads (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.