Re: [PATCH v2] Cygwin: pinfo: Fix exit code for non-cygwin apps which reads console.

[Takashi Yano <takashi.yano@nifty.ne.jp>]

On Mon, 28 Feb 2022 10:21:32 +0100
Corinna Vinschen wrote:
> Hi Takashi,
> 
> On Feb 27 09:46, Takashi Yano wrote:
> > - The recent commit "Cygwin: pinfo: Fix exit code when non-cygwin app
> >   exits by Ctrl-C." did not fix enough the issue. If a non-cygwin app
> >   is reading the console, it will not return STATUS_CONTROL_C_EXIT
> >   even if it is terminated by Ctrl-C. As a result, the previous patch
> >   does not take effect.
> >   This patch solves this issue by setting sigExeced to SIGINT in
> >   ctrl_c_handler(). In addition, sigExeced will be cleared if the app
> >   does not terminated within predetermined time period. The reason is
> >   that the app does not seem to be terminated by the signal sigExeced.
> > [...]
> > --- a/winsup/cygwin/spawn.cc
> > +++ b/winsup/cygwin/spawn.cc
> > @@ -953,7 +953,15 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
> >  	  if (sem)
> >  	    __posix_spawn_sem_release (sem, 0);
> >  	  if (ptys_need_cleanup || cons_need_cleanup)
> > -	    WaitForSingleObject (pi.hProcess, INFINITE);
> > +	    {
> > +	      LONG prev_sigExeced = sigExeced;
> > +	      while (WaitForSingleObject (pi.hProcess, 100) == WAIT_TIMEOUT)
> > +		/* If child process does not exit in predetermined time
> > +		   period, the process does not seem to be terminated by
> > +		   the signal sigExeced. Therefore, clear sigExeced here. */
> > +		prev_sigExeced =
> > +		  InterlockedCompareExchange (&sigExeced, 0, prev_sigExeced);
> > +	    }
> >  	  if (ptys_need_cleanup)
> >  	    {
> >  	      fhandler_pty_slave::cleanup_for_non_cygwin_app (&ptys_handle_set,
> 
> Is it really necessary to run the InterlockedCompareExchange in a loop?
> What about
> 
>   if (WFMO(..., 100) == WAIT_TIMEOUT)
>     {
>       InterlockedCompareExchange (&sigExeced, 0, prev_sigExeced);
>       WFMO(..., INFINITE);
>     }
> 
> ?

If non-cygwin app ignores Ctrl-C (like cmd.exe), and if
you hit Ctrl-C twice or more, sigExeced should be cleared
everytime on Ctrl-C. Your code clears sigExeced only once,
doesn't it?

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>