bpo-33038: Fix gzip.GzipFile for file objects with a non-string name attribute. (GH-6095)

Author: bbayles

Lib/gzip.py

@@ -95,9 +95,8 @@ def __init__(self, filename=None, mode=None,
         if filename is None:
             # 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 = getattr(fileobj, 'name', '')
+            if not isinstance(filename, basestring) or filename == '<fdopen>':
                 filename = ''
         if mode is None:
             if hasattr(fileobj, 'mode'): mode = fileobj.mode

Lib/test/test_gzip.py

@@ -6,6 +6,7 @@
 import os
 import io
 import struct
+import tempfile
 gzip = test_support.import_module('gzip')
 
 data1 = """  int length=DEFAULTALLOC, err = Z_OK;
@@ -331,6 +332,12 @@ def test_fileobj_from_fdopen(self):
             with gzip.GzipFile(fileobj=f, mode="w") as g:
                 self.assertEqual(g.name, "")
 
+    def test_fileobj_from_io_open(self):
+        fd = os.open(self.filename, os.O_WRONLY | os.O_CREAT)
+        with io.open(fd, "wb") as f:
+            with gzip.GzipFile(fileobj=f, mode="w") as g:
+                self.assertEqual(g.name, "")
+
     def test_fileobj_mode(self):
         gzip.GzipFile(self.filename, "wb").close()
         with open(self.filename, "r+b") as f:
@@ -359,6 +366,14 @@ def test_read_with_extra(self):
         with gzip.GzipFile(fileobj=io.BytesIO(gzdata)) as f:
             self.assertEqual(f.read(), b'Test')
 
+    def test_fileobj_without_name(self):
+        # Issue #33038: GzipFile should not assume that file objects that have
+        # a .name attribute use a non-None value.
+        with tempfile.SpooledTemporaryFile() as f:
+            with gzip.GzipFile(fileobj=f, mode='wb') as archive:
+                archive.write(b'data')
+                self.assertEqual(archive.name, '')
+
 def test_main(verbose=None):
     test_support.run_unittest(TestGzip)
 

Misc/ACKS

@@ -94,6 +94,7 @@ Michael R Bax
 Anthony Baxter
 Mike Bayer
 Samuel L. Bayer
+Bo Bayles
 Donald Beaudry
 David Beazley
 Carlo Beccarini

Misc/NEWS.d/next/Library/2018-03-10-20-14-36.bpo-33038.yA6CP5.rst

@@ -0,0 +1,2 @@
+gzip.GzipFile no longer produces an AttributeError exception when used with
+a file object with a non-string name attribute. Patch by Bo Bayles.