NAME

pthread_mutexattr_getpshared − Obtains the process-shared attribute of a mutex attributes object

SYNOPSIS

#include <pthread.h>
int pthread_mutexattr_getpshared(
        const pthread_mutexattr_t ∗attr,
        int ∗pshared );

LIBRARY

DECthreads POSIX 1003.1c Library (libpthread.so)

PARAMETERS

attrAddress of the mutex attributes object whose process-shared attribute is to be obtained. 

pshared
Location to store the value of the process-shared attribute of attr. 

DESCRIPTION

This routine obtains the value of the process-shared attribute in the mutex attributes object referenced by attr and stores it at the location pshared. The object referenced by attr must be initialized before this routine is called. 

Setting the process-shared attribute to PTHREAD_PROCESS_PRIVATE permits a mutex to 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 process-shared attribute of a mutex attributes object is PTHREAD_PROCESS_PRIVATE. 

Setting the process-shared attribute to PTHREAD_PROCESS_SHARED permits 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 programs. 

RETURN VALUES

If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows:

0Successful completion. 

[EINVAL]
The value specified by attr is not a valid attributes object. 

ERRORS

None

SEE ALSO

Functions: pthread_mutexattr_setpshared(3), pthread_mutexattr_init(3)

Manuals: Guide to DECthreads and Programmer’s Guide