call close on the underlying stream even if flush raises (#16597)

2 files changed, 35 insertions, 4 deletions

diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 86f3c4c..ac7832e 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -340,8 +340,10 @@ class IOBase:
         This method has no effect if the file is already closed.
         """
         if not self.__closed:
-            self.flush()
-            self.__closed = True
+            try:
+                self.flush()
+            finally:
+                self.__closed = True
 
     def __del__(self):
         """Destructor.  Calls close()."""
@@ -1568,8 +1570,10 @@ class TextIOWrapper(TextIOBase):
 
     def close(self):
         if self.buffer is not None and not self.closed:
-            self.flush()
-            self.buffer.close()
+            try:
+                self.flush()
+            finally:
+                self.buffer.close()
 
     @property
     def closed(self):
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index d10f52a..6132bae 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -573,6 +573,7 @@ class IOTest(unittest.TestCase):
             raise IOError()
         f.flush = bad_flush
         self.assertRaises(IOError, f.close) # exception not swallowed
+        self.assertTrue(f.closed)
 
     def test_multi_close(self):
         f = self.open(support.TESTFN, "wb", buffering=0)
@@ -732,6 +733,21 @@ class CommonBufferedTests:
         raw.flush = bad_flush
         b = self.tp(raw)
         self.assertRaises(IOError, b.close) # exception not swallowed
+        self.assertTrue(b.closed)
+
+    def test_close_error_on_close(self):
+        raw = self.MockRawIO()
+        def bad_flush():
+            raise IOError('flush')
+        def bad_close():
+            raise IOError('close')
+        raw.close = bad_close
+        b = self.tp(raw)
+        b.flush = bad_flush
+        with self.assertRaises(IOError) as err: # exception not swallowed
+            b.close()
+        self.assertEqual(err.exception.args, ('close',))
+        self.assertFalse(b.closed)
 
     def test_multi_close(self):
         raw = self.MockRawIO()
@@ -1230,6 +1246,16 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
                                      DeprecationWarning)):
             self.tp(self.MockRawIO(), 8, 12)
 
+    def test_write_error_on_close(self):
+        raw = self.MockRawIO()
+        def bad_write(b):
+            raise IOError()
+        raw.write = bad_write
+        b = self.tp(raw)
+        b.write(b'spam')
+        self.assertRaises(IOError, b.close) # exception not swallowed
+        self.assertTrue(b.closed)
+
 
 class CBufferedWriterTest(BufferedWriterTest, SizeofTest):
     tp = io.BufferedWriter
@@ -2378,6 +2404,7 @@ class TextIOWrapperTest(unittest.TestCase):
             raise IOError()
         txt.flush = bad_flush
         self.assertRaises(IOError, txt.close) # exception not swallowed
+        self.assertTrue(txt.closed)
 
     def test_multi_close(self):
         txt = self.TextIOWrapper(self.BytesIO(self.testdata), encoding="ascii")