Issue #13781: Fix GzipFile to work with os.fdopen()'d file objects.

1 files changed, 4 insertions, 2 deletions

diff --git a/Lib/gzip.py b/Lib/gzip.py
index ba2149ebf9..4462187116 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -156,8 +156,10 @@ class GzipFile(io.BufferedIOBase):
         if fileobj is None:
             fileobj = self.myfileobj = builtins.open(filename, mode or 'rb')
         if filename is None:
-            if hasattr(fileobj, 'name'): filename = fileobj.name
-            else: filename = ''
+            if hasattr(fileobj, 'name') and isinstance(fileobj.name, str):
+                filename = fileobj.name
+            else:
+                filename = ''
         if mode is None:
             if hasattr(fileobj, 'mode'): mode = fileobj.mode
             else: mode = 'rb'