GDB Ctrl-C Interrupt Fails WORKAROUND

[Pedro Alves]

Christopher Layne escreveu:
> On Thu, Jun 15, 2006 at 11:04:56AM -0400, Christopher Faylor wrote:
>>> I'm happy for you that CTRL-C works for you.  It does not work for me.
>>>
>>> I'm almost never running gdb from a genuine DOS command prompt.   
>>> Sometimes via ssh, sometimes via a terminal emulator.  CTRL-C doesn't  
>>> work in those.
>>>
>>> Also, if you have "tty" in your CYGWIN variable it doesn't work even  
>> >from a DOS command prompt.
>>
>> Which is exactly what I theorized above.  So, characterizing CTRL-C as
>> not working in gdb is rather an overstatement without more details.
>>
>> Now you know that you can use a standard console window for debugging
>> and all will be well.
>>
>>> Lacking the ability to interrupt a running program severely limits  
>>> gdb's usefulness.  Fortunately there's a workaround available.
>> Yep.  Use a console window.
>>

Is there a reason DebugBreakProcess can't be used from inside
gdb if sending a ctrl-c with GenerateConsoleCtrlEvent (CTRL_C_EVENT, pid)
doesn't work?

> 
> Where in the cygwin source tree would the best place be to look for
> where SIGINT handling is being done at the tty/pty level so that I can
> remove this pointless limitation from my builds?
> 


See gdb/win32-nat.c:win32_stop

and also:
http://sourceware.org/ml/gdb-patches/2007-02/msg00294.html
Look for win32_send_signal in the patch.

Note that DebugBreakProcess only exists on XP or Windows 2003
server onwards.  For WinNT < XP, it should be possible to simulate
it with CreateRemoteThread with entry point set to
DebugBreak or something similar.  The worst case would be that a dll
would have to be injected to load a function that does the
DebugBreak in the debuggee's address space.

Cheers,
Pedro Alves



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