There are several occasions where standard ngspice suffers from an error, cannot recover internally and then exits. If this is happening to the shared module this would mean that the parent application, the caller, is also forced to exit. Therefore (if not suffering from a segfault) ngspice.dll will call the function controlled_exit as usual, this now calls the callback function 'ControlledExit' (19.3.3.3), which hands over the request for exiting to the caller. The caller now has the task to handle the exit code for ngspice.

If ngspice has been linked at runtime by dlopen/LoadLibrary (see 19.2.2), the callback may close all threads, and then detach ngspice.dll by invoking dlclose/FreeLibrary. The caller may then restart ngspice by another loading and initialization (19.3.2.1).

If ngspice is included during linking the caller (see 19.2.1), there is not yet a good and general solution to error handling, if the error is non-recoverable from inside ngspice.