Make ctrl_cmd_string method more robust against type of arguments.

Technically speaking we prescribe in the type string that the paramteres
should be str, but users don't like to care about the type of
parameters.

Fixes #228

2 files changed, 13 insertions, 5 deletions

diff --git a/M2Crypto/Engine.py b/M2Crypto/Engine.py
index 96394a2..fa79e46 100644
--- a/M2Crypto/Engine.py
+++ b/M2Crypto/Engine.py
@@ -54,8 +54,11 @@ class Engine(object):
         return m2.engine_finish(self._ptr)
 
     def ctrl_cmd_string(self, cmd, arg, optional=0):
-        # type: (bytes, Optional[bytes], int) -> int
+        # type: (AnyStr, Optional[AnyStr], int) -> None
         """Call ENGINE_ctrl_cmd_string"""
+        cmd = six.ensure_str(cmd)
+        if arg is not None:
+            arg = six.ensure_str(arg)
         if not m2.engine_ctrl_cmd_string(self._ptr, cmd, arg, optional):
             raise EngineError(Err.get_error())
 
@@ -121,10 +124,10 @@ def load_dynamic_engine(id, sopath):
         sopath = sopath.encode('utf8')
     m2.engine_load_dynamic()
     e = Engine('dynamic')
-    e.ctrl_cmd_string(b'SO_PATH', sopath)
-    e.ctrl_cmd_string(b'ID', id)
-    e.ctrl_cmd_string(b'LIST_ADD', '1')
-    e.ctrl_cmd_string(b'LOAD', None)
+    e.ctrl_cmd_string('SO_PATH', sopath)
+    e.ctrl_cmd_string('ID', id)
+    e.ctrl_cmd_string('LIST_ADD', '1')
+    e.ctrl_cmd_string('LOAD', None)
     return e
 
 
diff --git a/tests/test_engine.py b/tests/test_engine.py
index c2c6047..5439ee3 100644
--- a/tests/test_engine.py
+++ b/tests/test_engine.py
@@ -30,6 +30,11 @@ class EngineTestCase(unittest.TestCase):
         Engine.load_dynamic()
         Engine.Engine('dynamic')
 
+    def test_engine_ctrl_cmd_string(self):
+        Engine.load_dynamic()
+        e = Engine.Engine('dynamic')
+        e.ctrl_cmd_string('ID', 'TESTID')
+
     def test_load_private(self):
         Engine.load_openssl()
         e = Engine.Engine('openssl')