Merge pull request hardbyte#924 from bmeisels/fileno_slcan_fix

Slcan: fix fileno issue with windows

Author: mergify[bot]

can/interfaces/slcan.py

@@ -10,6 +10,7 @@
 from typing import Any, Optional, Tuple
 from can import typechecking
 
+import io
 import time
 import logging
 
@@ -252,10 +253,12 @@ def shutdown(self) -> None:
         self.serialPortOrig.close()
 
     def fileno(self) -> int:
-        if hasattr(self.serialPortOrig, "fileno"):
+        try:
             return self.serialPortOrig.fileno()
-        # Return an invalid file descriptor on Windows
-        return -1
+        except io.UnsupportedOperation:
+            raise NotImplementedError(
+                "fileno is not implemented using current CAN bus on this platform"
+            )
 
     def get_version(
         self, timeout: Optional[float]