mirror of https://github.com/python/cpython
Issue #9550: a BufferedReader could issue an additional read when the
original read request had been satisfied, which can block indefinitely when the underlying raw IO channel is e.g. a socket. Report and original patch by Jason V. Miller.
This commit is contained in:
parent
5ea3d93708
commit
32cfedeb1c
|
@ -52,12 +52,14 @@ class MockRawIO:
|
|||
self._read_stack = list(read_stack)
|
||||
self._write_stack = []
|
||||
self._reads = 0
|
||||
self._extraneous_reads = 0
|
||||
|
||||
def read(self, n=None):
|
||||
self._reads += 1
|
||||
try:
|
||||
return self._read_stack.pop(0)
|
||||
except:
|
||||
self._extraneous_reads += 1
|
||||
return b""
|
||||
|
||||
def write(self, b):
|
||||
|
@ -88,6 +90,7 @@ class MockRawIO:
|
|||
try:
|
||||
data = self._read_stack[0]
|
||||
except IndexError:
|
||||
self._extraneous_reads += 1
|
||||
return 0
|
||||
if data is None:
|
||||
del self._read_stack[0]
|
||||
|
@ -824,6 +827,27 @@ class BufferedReaderTest(unittest.TestCase, CommonBufferedTests):
|
|||
self.assertRaises(IOError, bufio.seek, 0)
|
||||
self.assertRaises(IOError, bufio.tell)
|
||||
|
||||
def test_no_extraneous_read(self):
|
||||
# Issue #9550; when the raw IO object has satisfied the read request,
|
||||
# we should not issue any additional reads, otherwise it may block
|
||||
# (e.g. socket).
|
||||
bufsize = 16
|
||||
for n in (2, bufsize - 1, bufsize, bufsize + 1, bufsize * 2):
|
||||
rawio = self.MockRawIO([b"x" * n])
|
||||
bufio = self.tp(rawio, bufsize)
|
||||
self.assertEqual(bufio.read(n), b"x" * n)
|
||||
# Simple case: one raw read is enough to satisfy the request.
|
||||
self.assertEqual(rawio._extraneous_reads, 0,
|
||||
"failed for {}: {} != 0".format(n, rawio._extraneous_reads))
|
||||
# A more complex case where two raw reads are needed to satisfy
|
||||
# the request.
|
||||
rawio = self.MockRawIO([b"x" * (n - 1), b"x"])
|
||||
bufio = self.tp(rawio, bufsize)
|
||||
self.assertEqual(bufio.read(n), b"x" * n)
|
||||
self.assertEqual(rawio._extraneous_reads, 0,
|
||||
"failed for {}: {} != 0".format(n, rawio._extraneous_reads))
|
||||
|
||||
|
||||
class CBufferedReaderTest(BufferedReaderTest):
|
||||
tp = io.BufferedReader
|
||||
|
||||
|
|
|
@ -548,6 +548,7 @@ Trent Mick
|
|||
Aristotelis Mikropoulos
|
||||
Damien Miller
|
||||
Chad Miller
|
||||
Jason V. Miller
|
||||
Jay T. Miller
|
||||
Roman Milner
|
||||
Andrii V. Mishkovskyi
|
||||
|
|
|
@ -70,6 +70,11 @@ Extensions
|
|||
Library
|
||||
-------
|
||||
|
||||
- Issue #9550: a BufferedReader could issue an additional read when the
|
||||
original read request had been satisfied, which could block indefinitely
|
||||
when the underlying raw IO channel was e.g. a socket. Report and original
|
||||
patch by Jason V. Miller.
|
||||
|
||||
- Issue #3757: thread-local objects now support cyclic garbage collection.
|
||||
Thread-local objects involved in reference cycles will be deallocated
|
||||
timely by the cyclic GC, even if the underlying thread is still running.
|
||||
|
|
|
@ -1383,7 +1383,10 @@ _bufferedreader_read_generic(buffered *self, Py_ssize_t n)
|
|||
self->pos = 0;
|
||||
self->raw_pos = 0;
|
||||
self->read_end = 0;
|
||||
while (self->read_end < self->buffer_size) {
|
||||
/* NOTE: when the read is satisfied, we avoid issuing any additional
|
||||
reads, which could block indefinitely (e.g. on a socket).
|
||||
See issue #9550. */
|
||||
while (remaining > 0 && self->read_end < self->buffer_size) {
|
||||
Py_ssize_t r = _bufferedreader_fill_buffer(self);
|
||||
if (r == -1)
|
||||
goto error;
|
||||
|
|
Loading…
Reference in New Issue