#2959: allow multiple close() calls for GzipFile.

Lib/gzip.py

@@ -306,6 +306,8 @@ class GzipFile:
             raise IOError, "Incorrect length of data produced"
 
     def close(self):
+        if self.fileobj is None:
+            return
         if self.mode == WRITE:
             self.fileobj.write(self.compress.flush())
             write32u(self.fileobj, self.crc)

Lib/test/test_gzip.py

@@ -24,14 +24,14 @@ data2 = """/* zlibmodule.c -- gzip-compatible data compression */
 class TestGzip(unittest.TestCase):
     filename = test_support.TESTFN
 
-    def setUp (self):
+    def setUp(self):
         test_support.unlink(self.filename)
 
-    def tearDown (self):
+    def tearDown(self):
         test_support.unlink(self.filename)
 
 
-    def test_write (self):
+    def test_write(self):
         f = gzip.GzipFile(self.filename, 'wb') ; f.write(data1 * 50)
 
         # Try flush and fileno.
@@ -41,6 +41,9 @@ class TestGzip(unittest.TestCase):
             os.fsync(f.fileno())
         f.close()
 
+        # Test multiple close() calls.
+        f.close()
+
     def test_read(self):
         self.test_write()
         # Try reading.

Misc/NEWS

@@ -59,6 +59,10 @@ Extension Modules
 Library
 -------
 
+- Issue #2959: For consistency with other file-like objects, gzip's
+  GzipFile.close() can now be called multiple times without raising
+  an exception.
+
 - Issue #1390: Raise ValueError in toxml when an invalid comment would
   otherwise be produced.