2 files changed, 52 insertions, 14 deletions
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index a9ff985..ffbfda1 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -325,6 +325,7 @@ class IOBase(metaclass=abc.ABCMeta):
 
         This is not implemented for read-only and non-blocking streams.
         """
+        self._checkClosed()
         # XXX Should this return the number of bytes written???
 
     __closed = False
@@ -335,10 +336,7 @@ class IOBase(metaclass=abc.ABCMeta):
         This method has no effect if the file is already closed.
         """
         if not self.__closed:
-            try:
-                self.flush()
-            except IOError:
-                pass  # If flush() fails, just give up
+            self.flush()
             self.__closed = True
 
     def __del__(self) -> None:
@@ -705,14 +703,13 @@ class _BufferedIOMixin(BufferedIOBase):
     ### Flush and close ###
 
     def flush(self):
+        if self.closed:
+            raise ValueError("flush of closed file")
         self.raw.flush()
 
     def close(self):
-        if not self.closed and self.raw is not None:
-            try:
-                self.flush()
-            except IOError:
-                pass  # If flush() fails, just give up
+        if self.raw is not None and not self.closed:
+            self.flush()
             self.raw.close()
 
     def detach(self):
@@ -1514,11 +1511,8 @@ class TextIOWrapper(TextIOBase):
         self._telling = self._seekable
 
     def close(self):
-        if self.buffer is not None:
-            try:
-                self.flush()
-            except IOError:
-                pass  # If flush() fails, just give up
+        if self.buffer is not None and not self.closed:
+            self.flush()
             self.buffer.close()
 
     @property
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 71362f0..f6175c8 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -535,6 +535,20 @@ class IOTest(unittest.TestCase):
         with self.open(zero, "r") as f:
             self.assertRaises(OverflowError, f.read)
 
+    def test_flush_error_on_close(self):
+        f = self.open(support.TESTFN, "wb", buffering=0)
+        def bad_flush():
+            raise IOError()
+        f.flush = bad_flush
+        self.assertRaises(IOError, f.close) # exception not swallowed
+
+    def test_multi_close(self):
+        f = self.open(support.TESTFN, "wb", buffering=0)
+        f.close()
+        f.close()
+        f.close()
+        self.assertRaises(ValueError, f.flush)
+
 class CIOTest(IOTest):
     pass
 
@@ -634,6 +648,22 @@ class CommonBufferedTests:
         raw.name = b"dummy"
         self.assertEqual(repr(b), "<%s name=b'dummy'>" % clsname)
 
+    def test_flush_error_on_close(self):
+        raw = self.MockRawIO()
+        def bad_flush():
+            raise IOError()
+        raw.flush = bad_flush
+        b = self.tp(raw)
+        self.assertRaises(IOError, b.close) # exception not swallowed
+
+    def test_multi_close(self):
+        raw = self.MockRawIO()
+        b = self.tp(raw)
+        b.close()
+        b.close()
+        b.close()
+        self.assertRaises(ValueError, b.flush)
+
 
 class BufferedReaderTest(unittest.TestCase, CommonBufferedTests):
     read_mode = "rb"
@@ -2114,6 +2144,20 @@ class TextIOWrapperTest(unittest.TestCase):
             for n in range(20):
                 self.assertEquals(content.count("Thread%03d\n" % n), 1)
 
+    def test_flush_error_on_close(self):
+        txt = self.TextIOWrapper(self.BytesIO(self.testdata), encoding="ascii")
+        def bad_flush():
+            raise IOError()
+        txt.flush = bad_flush
+        self.assertRaises(IOError, txt.close) # exception not swallowed
+
+    def test_multi_close(self):
+        txt = self.TextIOWrapper(self.BytesIO(self.testdata), encoding="ascii")
+        txt.close()
+        txt.close()
+        txt.close()
+        self.assertRaises(ValueError, txt.flush)
+
 class CTextIOWrapperTest(TextIOWrapperTest):
 
     def test_initialization(self):