tests: kill for windows in killdaemons.py checks return values

The return values of the windll calls are checked and when an error is
indicated, it is raised. The handle is still closed properly.

tests/killdaemons.py

@@ -4,13 +4,30 b' import os, sys, time, errno, signal'
 
 if os.name =='nt':
     import ctypes
+
+    def _check(ret, expectederr=None):
+        if ret == 0:
+            winerrno = ctypes.GetLastError()
+            if winerrno == expectederr:
+                return True
+            raise ctypes.WinError(winerrno)
+
     def kill(pid, logfn, tryhard=True):
         logfn('# Killing daemon process %d' % pid)
         PROCESS_TERMINATE = 1
         handle = ctypes.windll.kernel32.OpenProcess(
                 PROCESS_TERMINATE, False, pid)
-        ctypes.windll.kernel32.TerminateProcess(handle, -1)
-        ctypes.windll.kernel32.CloseHandle(handle)
+        if handle == 0:
+            # TODO: call _check(0, expected) to check if "process not found"
+            return # process not found, already finished
+        try:
+            _check(ctypes.windll.kernel32.TerminateProcess(handle, -1), 5)
+            #      windows error 5 when process does not exist or no access TODO
+        except: #re-raises
+            ctypes.windll.kernel32.CloseHandle(handle) # no _check, keep error
+            raise
+        _check(ctypes.windll.kernel32.CloseHandle(handle))
+
 else:
     def kill(pid, logfn, tryhard=True):
         try: