Ctrl+C not working with windows programs in Cygwin 1.7.16

Daniel Colascione dancol@dancol.org
Thu Aug 2 21:35:00 GMT 2012

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 implicit
>> call to SetConsoleCtrlHandler(NULL,TRUE) is made on behalf of the new process;
>> this means that the new process has CTRL+C disabled. This lets shells handle
>> 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/process
>> 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 processes
controlled by actual consoles (as opposed to ptys) under the assumption that the
Windows console machinery would do the job. It looks like the two changes
interact unpleasantly.

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