Cygwin: pty: Fix Ctrl-C handling further for non-cygwin apps.

- The recent commit: "Cygwin: pty: Fix Ctrl-C handling for non-cygwin
  apps in background." causes the problem that cmd.exe is terminated
  by Ctrl-C even if it is running in pseudo console. This patch fixes
  the issue.

winsup/cygwin/fhandler_tty.cc

@@ -2251,7 +2251,41 @@ fhandler_pty_master::write (const void *ptr, size_t len)
 
       if ((ti.c_lflag & ISIG) && memchr (buf, '\003', nlen))
 	{
-	  get_ttyp ()->kill_pgrp (SIGINT);
+	  /* If the process is started with CREATE_NEW_PROCESS_GROUP
+	     flag, Ctrl-C will not be sent to that process. Therefore,
+	     send Ctrl-break event to that process here. */
+	  DWORD wpid = 0;
+	  winpids pids ((DWORD) 0);
+	  for (unsigned i = 0; i < pids.npids; i++)
+	    {
+	      _pinfo *p = pids[i];
+	      if (p->ctty == get_ttyp ()->ntty
+		  && p->pgid == get_ttyp ()->getpgid ()
+		  && (p->process_state & PID_NEW_PG))
+		{
+		  wpid = p->dwProcessId;
+		  break;
+		}
+	    }
+	  pinfo pinfo_resume = pinfo (myself->ppid);
+	  DWORD resume_pid;
+	  if (pinfo_resume)
+	    resume_pid = pinfo_resume->dwProcessId;
+	  else
+	    resume_pid = get_console_process_id (myself->dwProcessId, false);
+	  if (wpid && resume_pid)
+	    {
+	      WaitForSingleObject (pcon_mutex, INFINITE);
+	      FreeConsole ();
+	      AttachConsole (wpid);
+	      /* CTRL_C_EVENT does not work for the process started with
+		 CREATE_NEW_PROCESS_GROUP flag, so send CTRL_BREAK_EVENT
+		 instead. */
+	      GenerateConsoleCtrlEvent (CTRL_BREAK_EVENT, wpid);
+	      FreeConsole ();
+	      AttachConsole (resume_pid);
+	      ReleaseMutex (pcon_mutex);
+	    }
 	  if (!(ti.c_lflag & NOFLSH))
 	    get_ttyp ()->discard_input = true;
 	}

winsup/cygwin/include/sys/cygwin.h

@@ -274,6 +274,8 @@ enum
   PID_NEW	       = 0x01000, /* Available. */
   PID_ALLPIDS	       = 0x02000, /* used by pinfo scanner */
   PID_PROCINFO	       = 0x08000, /* caller just asks for process info */
+  PID_NEW_PG	       = 0x10000, /* Process created with
+				     CREATE_NEW_PROCESS_GROUOP flag */
   PID_EXITED	       = 0x40000000, /* Free entry. */
   PID_REAPED	       = 0x80000000  /* Reaped */
 };

winsup/cygwin/spawn.cc

@@ -575,6 +575,9 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	c_flags |= CREATE_NEW_PROCESS_GROUP;
       refresh_cygheap ();
 
+      if (c_flags & CREATE_NEW_PROCESS_GROUP)
+	myself->process_state |= PID_NEW_PG;
+
       if (mode == _P_DETACH)
 	/* all set */;
       else if (mode != _P_OVERLAY || !my_wr_proc_pipe)