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

1 files changed, 6 insertions, 2 deletions

diff --git a/Lib/gzip.py b/Lib/gzip.py
index 2bcb4dbfb0..8fdac8397d 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -88,8 +88,12 @@ class GzipFile(io.BufferedIOBase):
         if fileobj is None:
             fileobj = self.myfileobj = __builtin__.open(filename, mode or 'rb')
         if filename is None:
-            if hasattr(fileobj, 'name'): filename = fileobj.name
-            else: filename = ''
+            # Issue #13781: os.fdopen() creates a fileobj with a bogus name
+            # attribute. Avoid saving this in the gzip header's filename field.
+            if hasattr(fileobj, 'name') and fileobj.name != '<fdopen>':
+                filename = fileobj.name
+            else:
+                filename = ''
         if mode is None:
             if hasattr(fileobj, 'mode'): mode = fileobj.mode
             else: mode = 'rb'