The function int pthread_mutexattr_init(pthread_mutexattr_t *attr) initializes a mutex attributes object 'attr' with the default value for all of the attributes defined by the implementation. Results are undefined if it is called specifying an already initialized 'attr' attributes object. After a mutex attributes object has been used to initialize one or more mutexes, any function affecting the attributes object (including destruction) shall not affect any previously initialized mutexes. Upon success it returns 0. If it fails, an error number shall be returned: [ENOMEM] - Insufficient memory exists to initialize the mutex attributes object.