NAME

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

SYNOPSIS

[TSH] #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. If the process-shared attribute is PTHREAD_PROCESS_PRIVATE, the mutex shall only be operated upon by threads created within the same process as the thread that initialized the mutex; if threads of differing processes attempt to operate on such a mutex, the behavior is undefined. 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].

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

XBD <pthread.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Threads Extension.

Issue 6

The pthread_mutexattr_getpshared() and pthread_mutexattr_setpshared() functions are marked as part of the Threads and Thread Process-Shared Synchronization options.

The restrict keyword is added to the pthread_mutexattr_getpshared() prototype for alignment with the ISO/IEC 9899:1999 standard.

Issue 7

The pthread_mutexattr_getpshared() and pthread_mutexattr_setpshared() functions are moved from the Threads option.

The [EINVAL] error for an uninitialized mutex attributes object is removed; this condition results in undefined behavior.