Issue #13322: Fix BufferedWriter.write() to ensure that BlockingIOError is
raised when the wrapped raw file is non-blocking and the write would block.
Previous code assumed that the raw write() would raise BlockingIOError, but
RawIOBase.write() is defined to returned None when the call would block.
Patch by sbt.
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 76a2d5f..34d0c4c 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -8,6 +8,7 @@
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
@@ -720,8 +721,11 @@
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:
@@ -1074,13 +1078,9 @@
# 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
@@ -1111,24 +1111,23 @@
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 IOError as e:
- if e.errno != EINTR:
- raise
- 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 BlockingIOError:
+ raise RuntimeError("self.raw should implement RawIOBase: it "
+ "should not raise BlockingIOError")
+ except IOError as e:
+ if e.errno != EINTR:
+ raise
+ continue
+ 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)