PTHREAD_MUTEXATTR_GETPSHARED(3P)

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.

NAME
pthread_mutexattr_getpshared, pthread_mutexattr_setpshared — get and set the process-shared attribute

SYNOPSIS

#include <pthread.h>

int pthread_mutexattr_getpshared(const pthread_mutexattr_t
    *restrict attr, int *restrict pshared);
int pthread_mutexattr_setpshared(pthread_mutexattr_t *attr,
    int pshared);

DESCRIPTION
The pthread_mutexattr_getpshared() function shall obtain the value of the process-shared attribute from the attributes object referenced by attr.

The pthread_mutexattr_setpshared() function shall set the process-shared attribute in an initialized attributes object referenced by attr.

The process-shared attribute is set to PTHREAD_PROCESS_SHARED to permit a mutex to be operated upon by any thread that has access to the memory where the mutex is allocated, even if the mutex is allocated in memory that is shared by multiple processes. See Section 2.9.9, Synchronization Object Copies and Alternative Mappings for further requirements. The default value of the attribute shall be PTHREAD_PROCESS_PRIVATE.

The behavior is undefined if the value specified by the attr argument to pthread_mutexattr_getpshared() or pthread_mutexattr_setpshared() does not refer to an initialized mutex attributes object.

RETURN VALUE
Upon successful completion, pthread_mutexattr_setpshared() shall return zero; otherwise, an error number shall be returned to indicate the error.

Upon successful completion, pthread_mutexattr_getpshared() shall return zero and store the value of the process-shared attribute of attr into the object referenced by the pshared parameter. Otherwise, an error number shall be returned to indicate the error.

ERRORS
The pthread_mutexattr_setpshared() function may fail if:

EINVAL
    The new value specified for the attribute is outside the range of legal values for that attribute.

These functions shall not return an error code of [EINTR].

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
None.

RATIONALE
If an implementation detects that the value specified by the attr argument to pthread_mutexattr_getpshared() or pthread_mutexattr_setpshared() does not refer to an initialized mutex attributes object, it is recommended that the function should fail and report an [EINVAL] error.

FUTURE DIRECTIONS
None.

SEE ALSO
pthread_cond_destroy(), pthread_create(), pthread_mutex_destroy(), pthread_mutexattr_destroy()

The Base Definitions volume of POSIX.1-2017, <pthread.h>

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/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 .