Obtains the thread-specific data associated with the specified
    key.

1 - C Binding

    #include <pthread.h>

    void
    *pthread_getspecific (
                pthread_key_t   key);

2 - Arguments

 key

    The context key identifies the thread-specific data to be
    obtained.

3 - Description

    This routine obtains the thread-specific data associated with the
    specified key for the current thread. Obtain this key by calling
    the pthread_key_create() routine. This routine returns the value
    currently bound to the specified key on behalf of the calling
    thread.

    This routine may be called from a thread-specific data destructor
    function.

4 - Return Values

    No errors are returned. This routine returns the thread-specific
    data value associated with the specified key argument. If no
    thread-specific data value is associated with key, or if key is
    not defined, then this routine returns a NULL value.

5 - Associated Routines

       pthread_key_create()
       pthread_setspecific()