Close #17666: Fix reading gzip files with an extra field.

1 files changed, 7 insertions, 0 deletions

diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index ebd4c43855..37fe8538a7 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -403,6 +403,13 @@ class TestGzip(BaseTest):
             with gzip.GzipFile(fileobj=io.BytesIO(truncated[:i])) as f:
                 self.assertRaises(EOFError, f.read, 1)
 
+    def test_read_with_extra(self):
+        # Gzip data with an extra field
+        gzdata = (b'\x1f\x8b\x08\x04\xb2\x17cQ\x02\xff'
+                  b'\x05\x00Extra'
+                  b'\x0bI-.\x01\x002\xd1Mx\x04\x00\x00\x00')
+        with gzip.GzipFile(fileobj=io.BytesIO(gzdata)) as f:
+            self.assertEqual(f.read(), b'Test')
 
 class TestOpen(BaseTest):
     def test_binary_modes(self):