[Python-checkins] cpython (merge 3.2 -> default): Issue #13322: Fix BufferedWriter.write() to ensure that BlockingIOError is
antoine.pitrou
python-checkins at python.org
Mon Nov 21 20:31:12 CET 2011
http://hg.python.org/cpython/rev/3cd1985ed04f
changeset: 73666:3cd1985ed04f
parent: 73664:d6d15fcf5eb6
parent: 73665:ac2c4c62b486
user: Antoine Pitrou <solipsis at pitrou.net>
date: Mon Nov 21 20:22:01 2011 +0100
summary:
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.
files:
Lib/_pyio.py | 47 ++++++++--------
Lib/test/test_io.py | 80 ++++++++++++++++++++++++++-
Misc/ACKS | 1 +
Misc/NEWS | 6 ++
Modules/_io/bufferedio.c | 78 ++++++++++++++++-----------
5 files changed, 152 insertions(+), 60 deletions(-)
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -6,6 +6,7 @@
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
@@ -717,8 +718,11 @@
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:
@@ -1077,13 +1081,9 @@
# 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
@@ -1114,22 +1114,21 @@
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)
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -42,7 +42,10 @@
import threading
except ImportError:
threading = None
-
+try:
+ import fcntl
+except ImportError:
+ fcntl = None
def _default_chunk_size():
"""Get the default TextIOWrapper chunk size"""
@@ -242,9 +245,14 @@
except ValueError:
pass
else:
- self._blocker_char = None
- self._write_stack.append(b[:n])
- raise self.BlockingIOError(0, "test blocking", n)
+ if n > 0:
+ # write data up to the first blocker
+ self._write_stack.append(b[:n])
+ return n
+ else:
+ # cancel blocker and indicate would block
+ self._blocker_char = None
+ return None
self._write_stack.append(b)
return len(b)
@@ -2753,6 +2761,70 @@
with self.open(support.TESTFN, **kwargs) as f:
self.assertRaises(TypeError, pickle.dumps, f, protocol)
+ @unittest.skipUnless(fcntl, 'fcntl required for this test')
+ def test_nonblock_pipe_write_bigbuf(self):
+ self._test_nonblock_pipe_write(16*1024)
+
+ @unittest.skipUnless(fcntl, 'fcntl required for this test')
+ def test_nonblock_pipe_write_smallbuf(self):
+ self._test_nonblock_pipe_write(1024)
+
+ def _set_non_blocking(self, fd):
+ flags = fcntl.fcntl(fd, fcntl.F_GETFL)
+ self.assertNotEqual(flags, -1)
+ res = fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
+ self.assertEqual(res, 0)
+
+ def _test_nonblock_pipe_write(self, bufsize):
+ sent = []
+ received = []
+ r, w = os.pipe()
+ self._set_non_blocking(r)
+ self._set_non_blocking(w)
+
+ # To exercise all code paths in the C implementation we need
+ # to play with buffer sizes. For instance, if we choose a
+ # buffer size less than or equal to _PIPE_BUF (4096 on Linux)
+ # then we will never get a partial write of the buffer.
+ rf = self.open(r, mode='rb', closefd=True, buffering=bufsize)
+ wf = self.open(w, mode='wb', closefd=True, buffering=bufsize)
+
+ with rf, wf:
+ for N in 9999, 73, 7574:
+ try:
+ i = 0
+ while True:
+ msg = bytes([i % 26 + 97]) * N
+ sent.append(msg)
+ wf.write(msg)
+ i += 1
+
+ except self.BlockingIOError as e:
+ self.assertEqual(e.args[0], errno.EAGAIN)
+ self.assertEqual(e.args[2], e.characters_written)
+ sent[-1] = sent[-1][:e.characters_written]
+ received.append(rf.read())
+ msg = b'BLOCKED'
+ wf.write(msg)
+ sent.append(msg)
+
+ while True:
+ try:
+ wf.flush()
+ break
+ except self.BlockingIOError as e:
+ self.assertEqual(e.args[0], errno.EAGAIN)
+ self.assertEqual(e.args[2], e.characters_written)
+ self.assertEqual(e.characters_written, 0)
+ received.append(rf.read())
+
+ received += iter(rf.read, None)
+
+ sent, received = b''.join(sent), b''.join(received)
+ self.assertTrue(sent == received)
+ self.assertTrue(wf.closed)
+ self.assertTrue(rf.closed)
+
class CMiscIOTest(MiscIOTest):
io = io
diff --git a/Misc/ACKS b/Misc/ACKS
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -860,6 +860,7 @@
Mark Sapiro
Ty Sarna
Ben Sayer
+sbt
Andrew Schaaf
Michael Scharf
Andreas Schawo
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -384,6 +384,12 @@
Library
-------
+- 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.
+
- Issue #13358: HTMLParser now calls handle_data only once for each CDATA.
- Issue #4147: minidom's toprettyxml no longer adds whitespace around a text
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -596,7 +596,7 @@
/* Forward decls */
static PyObject *
-_bufferedwriter_flush_unlocked(buffered *, int);
+_bufferedwriter_flush_unlocked(buffered *);
static Py_ssize_t
_bufferedreader_fill_buffer(buffered *self);
static void
@@ -618,6 +618,18 @@
* Helpers
*/
+/* Sets the current error to BlockingIOError */
+static void
+_set_BlockingIOError(char *msg, Py_ssize_t written)
+{
+ PyObject *err;
+ err = PyObject_CallFunction(PyExc_BlockingIOError, "isn",
+ errno, msg, written);
+ if (err)
+ PyErr_SetObject(PyExc_BlockingIOError, err);
+ Py_XDECREF(err);
+}
+
/* Returns the address of the `written` member if a BlockingIOError was
raised, NULL otherwise. The error is always re-raised. */
static Py_ssize_t *
@@ -772,7 +784,7 @@
{
PyObject *res;
- res = _bufferedwriter_flush_unlocked(self, 0);
+ res = _bufferedwriter_flush_unlocked(self);
if (res == NULL)
return NULL;
Py_DECREF(res);
@@ -1188,7 +1200,7 @@
/* Fallback: invoke raw seek() method and clear buffer */
if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 0);
+ res = _bufferedwriter_flush_unlocked(self);
if (res == NULL)
goto end;
Py_CLEAR(res);
@@ -1807,6 +1819,7 @@
Py_buffer buf;
PyObject *memobj, *res;
Py_ssize_t n;
+ int errnum;
/* NOTE: the buffer needn't be released as its object is NULL. */
if (PyBuffer_FillInfo(&buf, NULL, start, len, 1, PyBUF_CONTIG_RO) == -1)
return -1;
@@ -1819,11 +1832,21 @@
raised (see issue #10956).
*/
do {
+ errno = 0;
res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_write, memobj, NULL);
+ errnum = errno;
} while (res == NULL && _trap_eintr());
Py_DECREF(memobj);
if (res == NULL)
return -1;
+ if (res == Py_None) {
+ /* Non-blocking stream would have blocked. Special return code!
+ Being paranoid we reset errno in case it is changed by code
+ triggered by a decref. errno is used by _set_BlockingIOError(). */
+ Py_DECREF(res);
+ errno = errnum;
+ return -2;
+ }
n = PyNumber_AsSsize_t(res, PyExc_ValueError);
Py_DECREF(res);
if (n < 0 || n > len) {
@@ -1840,7 +1863,7 @@
/* `restore_pos` is 1 if we need to restore the raw stream position at
the end, 0 otherwise. */
static PyObject *
-_bufferedwriter_flush_unlocked(buffered *self, int restore_pos)
+_bufferedwriter_flush_unlocked(buffered *self)
{
Py_ssize_t written = 0;
Py_off_t n, rewind;
@@ -1862,14 +1885,11 @@
Py_SAFE_DOWNCAST(self->write_end - self->write_pos,
Py_off_t, Py_ssize_t));
if (n == -1) {
- Py_ssize_t *w = _buffered_check_blocking_error();
- if (w == NULL)
- goto error;
- self->write_pos += *w;
- self->raw_pos = self->write_pos;
- written += *w;
- *w = written;
- /* Already re-raised */
+ goto error;
+ }
+ else if (n == -2) {
+ _set_BlockingIOError("write could not complete without blocking",
+ 0);
goto error;
}
self->write_pos += n;
@@ -1882,16 +1902,6 @@
goto error;
}
- if (restore_pos) {
- Py_off_t forward = rewind - written;
- if (forward != 0) {
- n = _buffered_raw_seek(self, forward, 1);
- if (n < 0) {
- goto error;
- }
- self->raw_pos += forward;
- }
- }
_bufferedwriter_reset_buf(self);
end:
@@ -1944,7 +1954,7 @@
}
/* First write the current buffer */
- res = _bufferedwriter_flush_unlocked(self, 0);
+ res = _bufferedwriter_flush_unlocked(self);
if (res == NULL) {
Py_ssize_t *w = _buffered_check_blocking_error();
if (w == NULL)
@@ -1967,14 +1977,19 @@
PyErr_Clear();
memcpy(self->buffer + self->write_end, buf.buf, buf.len);
self->write_end += buf.len;
+ self->pos += buf.len;
written = buf.len;
goto end;
}
/* Buffer as much as possible. */
memcpy(self->buffer + self->write_end, buf.buf, avail);
self->write_end += avail;
- /* Already re-raised */
- *w = avail;
+ self->pos += avail;
+ /* XXX Modifying the existing exception e using the pointer w
+ will change e.characters_written but not e.args[2].
+ Therefore we just replace with a new error. */
+ _set_BlockingIOError("write could not complete without blocking",
+ avail);
goto error;
}
Py_CLEAR(res);
@@ -1999,11 +2014,9 @@
Py_ssize_t n = _bufferedwriter_raw_write(
self, (char *) buf.buf + written, buf.len - written);
if (n == -1) {
- Py_ssize_t *w = _buffered_check_blocking_error();
- if (w == NULL)
- goto error;
- written += *w;
- remaining -= *w;
+ goto error;
+ } else if (n == -2) {
+ /* Write failed because raw file is non-blocking */
if (remaining > self->buffer_size) {
/* Can't buffer everything, still buffer as much as possible */
memcpy(self->buffer,
@@ -2011,8 +2024,9 @@
self->raw_pos = 0;
ADJUST_POSITION(self, self->buffer_size);
self->write_end = self->buffer_size;
- *w = written + self->buffer_size;
- /* Already re-raised */
+ written += self->buffer_size;
+ _set_BlockingIOError("write could not complete without "
+ "blocking", written);
goto error;
}
PyErr_Clear();
--
Repository URL: http://hg.python.org/cpython
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