rtems_interrupt_catch(): installing old handler

[Ingolf Steinbach]

Hi,

in my code, I am using something like the following (simplified)
code to install and deinstall an ISR (RTEMS 4.6.1 using the
leon2 BSP):

    #include <rtems.h>
    #include <assert.h>
    [...]
    rtems_isr_entry oldInterruptHandler = NULL;
    rtems_isr_entry dummy = NULL;

    rtems_status_code const result =
            rtems_interrupt_catch(
                    newHandler, trapNumber,
                    &oldInterruptHandler);
    assert(RTEMS_SUCCESSFUL == result); /* first assertion */

    /* do something */
    [...]

    /* install the old handler */
    result =
            rtems_interrupt_catch(
                    oldInterruptHandler, trapNumber,
                    &dummy);
    assert(RTEMS_SUCCESSFUL == result); /* second assertion */

The first assertion succeeds. The newHandler ISR is installed
and is indeed called when the associated interrupt is received.

However, the second assertion fails because result indicates
an RTEMS_INVALID_ADRESS error (probably because the first
rtems_interrupt_catch() returned a NULL oldInterruptHandler).

How can I de-install an interrupt handler?

Kind regards
    Ingolf

PS: I know that 4.6.1 is not the latest 4.6.x release but I
    did not find any changes related to the above problem
    in the change logs.
-- 

Ingolf Steinbach                       Jena-Optronik GmbH
ingolf.steinbach at jena-optronik.de       ++49 3641 200-147
PGP: 0x7B3B5661  213C 828E 0C92 16B5  05D0 4D5B A324 EC04