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

    Return      Description

    0           Successful completion.
    [EAGAIN]    The system lacks the necessary resources to
                initialize a mutex.
    [EBUSY]     The implementation has detected an attempt to
                reinitialize mutex (a previously initialized, but
                not yet destroyed, mutex).
    [EINVAL]    The value specified by mutex is not a valid mutex.
    [ENOMEM]    Insufficient memory to initialize the mutex.
    [EPERM]     The caller does not have privileges to perform this
                operation.