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Re: [PATCH 2/4]: Handle SIGINT under Python by raising KeyboardInterrupt
Hi,
On Jul 30, 2012, at 11:10 AM, Tom Tromey wrote:
>>>>>> "Yit" == Khoo Yit Phang <khooyp@cs.umd.edu> writes:
>
> Yit> This looks like it might work, I'll give it a go and get back to
> Yit> you. The only issue I see right now is if immediate_quit is set, it
> Yit> could leave Python in a bad state (among other issues). Perhaps make
> Yit> immediate_quit an argument of check_quit_flag?
>
> I don't think it can cause problems.
>
> handle_sigint calls set_quit_flag. Then it (indirectly) calls
> async_request_quit.
>
> async_request_quit checks immediate_quit and, if it is set, calls quit.
>
> Eventually quit calls throw_exception, which clears the quit flag.
Doesn't throw_exception use a longjmp? Say that we're running inside Python's interpreter, and an Ctrl-C occurs, causing handle_sigint to be called. handle_sigint calls gdb_call_async_signal_handler (sigint_token, immediate_quit), which directly calls sigint_token->proc which is async_request_quit, which in turn calls quit (), which calls throw_exception which calls longjmp to the nearest TRY_CATCH. At this point, we have no idea what the state of Python's interpreter is, and could well easily mangle something since the longjmp can occur at any point.
Yit
July 30, 2012