NAME

       pthread_mutexattr_getpshared,  pthread_mutexattr_setpshared - get/set process-shared mutex
       attribute

LIBRARY

       POSIX threads library (libpthread, -lpthread)

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

       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.

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

       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.

       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.

       pthread_mutexattr_getpshared() places the value of the  process-shared  attribute  of  the
       mutex attributes object referred to by attr in the location pointed to by pshared.

       pthread_mutexattr_setpshared() sets the value of the process-shared attribute of the mutex
       attributes object referred to by attr to the value specified in pshared.

       If attr does not refer  to  an  initialized  mutex  attributes  object,  the  behavior  is
       undefined.

RETURN VALUE

       On success, these functions return 0.  On error, they return a positive error number.

ERRORS

       pthread_mutexattr_setpshared() can fail with the following errors:

       EINVAL The value specified in pshared is invalid.

       ENOTSUP
              pshared  is PTHREAD_PROCESS_SHARED but the implementation does not support process-
              shared mutexes.

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001.

SEE ALSO

       pthread_mutexattr_init(3), pthreads(7)