fixing: ifupdown2 (subprocesses) lives on after control-c + Parsing cmd string with shlex.split instead of string.split

Ticket: CM-9905
Reviewed By: CCR-4363
Testing Done: ^C ifupdown2 while ifreload-ing interfaces test files (~500ifaces) + smoke tests

ifupdown/utils.py

@@ -9,6 +9,15 @@
 import os
 import fcntl
 import re
+import signal
+
+from functools import partial
+
+def signal_handler_f(ps, sig, frame):
+    if ps:
+        ps.send_signal(sig)
+    if sig == signal.SIGINT:
+        raise KeyboardInterrupt
 
 class utils():
 
@@ -58,3 +67,11 @@ class utils():
         else:
             return False
 
+    @classmethod
+    def enable_subprocess_signal_forwarding(cls, ps, sig):
+        signal.signal(sig, partial(signal_handler_f, ps))
+
+    @classmethod
+    def disable_subprocess_signal_forwarding(cls, sig):
+        signal.signal(sig, signal.SIG_DFL)
+