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Date: Thu, 02 Aug 2012 14:21:56 -0700
From: Daniel Colascione <dancol AT dancol DOT org>
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To: cygwin AT cygwin DOT com
Subject: Re: Ctrl+C not working with windows programs in Cygwin 1.7.16
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On 8/2/2012 2:02 PM, Roger K. Wells wrote:
> On 08/02/2012 04:26 PM, Daniel Colascione wrote:
>> On 8/2/2012 12:32 PM, Marcin Kielar wrote:
>>> Steps to reproduce:
>>>
>>> 1. Start cygwin using cygwin.bat
>>> 2. Run `ping -t google.com`
>>> 3. Try breaking it with Ctrl+C
>> This problem arises from Cygwin's use of CREATE_NEW_PROCESS_GROUP. From =
MSDN:
>>
>> "When a process is created with CREATE_NEW_PROCESS_GROUP specified, an i=
mplicit
>> call to SetConsoleCtrlHandler(NULL,TRUE) is made on behalf of the new pr=
ocess;
>> this means that the new process has CTRL+C disabled. This lets shells ha=
ndle
>> CTRL+C themselves, and selectively pass that signal on to sub-processes.
>> CTRL+BREAK is not disabled, and may be used to interrupt the process/pro=
cess
>> group."
>>
>> SetConsoleCtrlHandler(NULL,TRUE) tells a process and all its children to=
 ignore
>> control-C. This problem only affects programs run in a console --- in a =
pty,
>> Cygwin just terminates Windows processes in response to SIGINT.
>>
> This may be true but it is a recent development.

ISTR a change a little while ago that made Cygwin not send SIGINT to proces=
ses
controlled by actual consoles (as opposed to ptys) under the assumption tha=
t the
Windows console machinery would do the job. It looks like the two changes
interact unpleasantly.



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