1 files changed, 23 insertions, 24 deletions
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index fec1c6f..fcd548d 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -6,6 +6,7 @@ import os
 import abc
 import codecs
 import warnings
+import errno
 # Import _thread instead of threading to reduce startup cost
 try:
     from _thread import allocate_lock as Lock
@@ -717,8 +718,11 @@ class _BufferedIOMixin(BufferedIOBase):
 
     def close(self):
         if self.raw is not None and not self.closed:
-            self.flush()
-            self.raw.close()
+            try:
+                # may raise BlockingIOError or BrokenPipeError etc
+                self.flush()
+            finally:
+                self.raw.close()
 
     def detach(self):
         if self.raw is None:
@@ -1077,13 +1081,9 @@ class BufferedWriter(_BufferedIOMixin):
             # XXX we can implement some more tricks to try and avoid
             # partial writes
             if len(self._write_buf) > self.buffer_size:
-                # We're full, so let's pre-flush the buffer
-                try:
-                    self._flush_unlocked()
-                except BlockingIOError as e:
-                    # We can't accept anything else.
-                    # XXX Why not just let the exception pass through?
-                    raise BlockingIOError(e.errno, e.strerror, 0)
+                # We're full, so let's pre-flush the buffer.  (This may
+                # raise BlockingIOError with characters_written == 0.)
+                self._flush_unlocked()
             before = len(self._write_buf)
             self._write_buf.extend(b)
             written = len(self._write_buf) - before
@@ -1114,22 +1114,21 @@ class BufferedWriter(_BufferedIOMixin):
     def _flush_unlocked(self):
         if self.closed:
             raise ValueError("flush of closed file")
-        written = 0
-        try:
-            while self._write_buf:
-                try:
-                    n = self.raw.write(self._write_buf)
-                except InterruptedError:
-                    continue
-                if n > len(self._write_buf) or n < 0:
-                    raise IOError("write() returned incorrect number of bytes")
-                del self._write_buf[:n]
-                written += n
-        except BlockingIOError as e:
-            n = e.characters_written
+        while self._write_buf:
+            try:
+                n = self.raw.write(self._write_buf)
+            except InterruptedError:
+                continue
+            except BlockingIOError:
+                raise RuntimeError("self.raw should implement RawIOBase: it "
+                                   "should not raise BlockingIOError")
+            if n is None:
+                raise BlockingIOError(
+                    errno.EAGAIN,
+                    "write could not complete without blocking", 0)
+            if n > len(self._write_buf) or n < 0:
+                raise IOError("write() returned incorrect number of bytes")
             del self._write_buf[:n]
-            written += n
-            raise BlockingIOError(e.errno, e.strerror, written)
 
     def tell(self):
         return _BufferedIOMixin.tell(self) + len(self._write_buf)