Re: C-g crash redux

[Chong Yidong]

>> Emacs can be made to crash simply by evaluating (sit-for 4) in the scratch
>> buffer and typing C-g before four seconds elapse.
>>
>> It's due to this change:
>>
>> 2006-08-01  Kim F. Storm  <address@hidden>
>>
>>      * process.c (wait_reading_process_output_unwind): New function.
>>      Restores waiting_for_user_input_p to saved value.
>>      (wait_reading_process_output): Unwind protect waiting_for_user_input_p
>>      instead of save/restore old value on stack.
>>
>> Presumably wait_reading_process_output is interrupted before it can do:
>>
>>   unbind_to (count, Qnil);
>
> Huh?  Is that really possible?
>
> What kind of interrupt can cause unwind_protect forms NOT to be run?

Typing C-g, which runs interrupt_signal, runs quit_throw_to_read_char
instead of Fsignal during when waiting_for_input is set (as it is
during wait_reading_process_output).  If I understand correctly, the
purpose is to enable read-char to return a `C-g' character; and that's
why it's both undesirable and unnecesssary to use a
record_unwind_protect inside wait_reading_process_output.

I'll go ahead and revert the 2006-08-01 change.