Issue #2489: Fix bug in _copy loop that could consume 100% cpu on EOF.

This commit is contained in:
Gregory P. Smith 2012-02-16 00:35:43 -08:00
commit 5b791fb548
3 changed files with 103 additions and 6 deletions

View File

@ -142,15 +142,21 @@ def _copy(master_fd, master_read=_read, stdin_read=_read):
Copies
pty master -> standard output (master_read)
standard input -> pty master (stdin_read)"""
while 1:
rfds, wfds, xfds = select(
[master_fd, STDIN_FILENO], [], [])
fds = [master_fd, STDIN_FILENO]
while True:
rfds, wfds, xfds = select(fds, [], [])
if master_fd in rfds:
data = master_read(master_fd)
os.write(STDOUT_FILENO, data)
if not data: # Reached EOF.
fds.remove(master_fd)
else:
os.write(STDOUT_FILENO, data)
if STDIN_FILENO in rfds:
data = stdin_read(STDIN_FILENO)
_writen(master_fd, data)
if not data:
fds.remove(STDIN_FILENO)
else:
_writen(master_fd, data)
def spawn(argv, master_read=_read, stdin_read=_read):
"""Create a spawned process."""

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@ -8,7 +8,9 @@ import errno
import pty
import os
import sys
import select
import signal
import socket
import unittest
TEST_STRING_1 = b"I wish to buy a fish license.\n"
@ -194,9 +196,96 @@ class PtyTest(unittest.TestCase):
# pty.fork() passed.
class SmallPtyTests(unittest.TestCase):
"""These tests don't spawn children or hang."""
def setUp(self):
self.orig_stdin_fileno = pty.STDIN_FILENO
self.orig_stdout_fileno = pty.STDOUT_FILENO
self.orig_pty_select = pty.select
self.fds = [] # A list of file descriptors to close.
self.select_rfds_lengths = []
self.select_rfds_results = []
def tearDown(self):
pty.STDIN_FILENO = self.orig_stdin_fileno
pty.STDOUT_FILENO = self.orig_stdout_fileno
pty.select = self.orig_pty_select
for fd in self.fds:
try:
os.close(fd)
except:
pass
def _pipe(self):
pipe_fds = os.pipe()
self.fds.extend(pipe_fds)
return pipe_fds
def _mock_select(self, rfds, wfds, xfds):
# This will raise IndexError when no more expected calls exist.
self.assertEqual(self.select_rfds_lengths.pop(0), len(rfds))
return self.select_rfds_results.pop(0), [], []
def test__copy_to_each(self):
"""Test the normal data case on both master_fd and stdin."""
read_from_stdout_fd, mock_stdout_fd = self._pipe()
pty.STDOUT_FILENO = mock_stdout_fd
mock_stdin_fd, write_to_stdin_fd = self._pipe()
pty.STDIN_FILENO = mock_stdin_fd
socketpair = socket.socketpair()
masters = [s.fileno() for s in socketpair]
self.fds.extend(masters)
# Feed data. Smaller than PIPEBUF. These writes will not block.
os.write(masters[1], b'from master')
os.write(write_to_stdin_fd, b'from stdin')
# Expect two select calls, the last one will cause IndexError
pty.select = self._mock_select
self.select_rfds_lengths.append(2)
self.select_rfds_results.append([mock_stdin_fd, masters[0]])
self.select_rfds_lengths.append(2)
with self.assertRaises(IndexError):
pty._copy(masters[0])
# Test that the right data went to the right places.
rfds = select.select([read_from_stdout_fd, masters[1]], [], [], 0)[0]
self.assertEqual([read_from_stdout_fd, masters[1]], rfds)
self.assertEqual(os.read(read_from_stdout_fd, 20), b'from master')
self.assertEqual(os.read(masters[1], 20), b'from stdin')
def test__copy_eof_on_all(self):
"""Test the empty read EOF case on both master_fd and stdin."""
read_from_stdout_fd, mock_stdout_fd = self._pipe()
pty.STDOUT_FILENO = mock_stdout_fd
mock_stdin_fd, write_to_stdin_fd = self._pipe()
pty.STDIN_FILENO = mock_stdin_fd
socketpair = socket.socketpair()
masters = [s.fileno() for s in socketpair]
self.fds.extend(masters)
os.close(masters[1])
socketpair[1].close()
os.close(write_to_stdin_fd)
# Expect two select calls, the last one will cause IndexError
pty.select = self._mock_select
self.select_rfds_lengths.append(2)
self.select_rfds_results.append([mock_stdin_fd, masters[0]])
# We expect that both fds were removed from the fds list as they
# both encountered an EOF before the second select call.
self.select_rfds_lengths.append(0)
with self.assertRaises(IndexError):
pty._copy(masters[0])
def test_main(verbose=None):
try:
run_unittest(PtyTest)
run_unittest(SmallPtyTests, PtyTest)
finally:
reap_children()

View File

@ -466,6 +466,8 @@ Core and Builtins
Library
-------
- Issue #2489: pty.spawn could consume 100% cpu when it encountered an EOF.
- Issue #13014: Fix a possible reference leak in SSLSocket.getpeercert().
- Issue #13777: Add PF_SYSTEM sockets on OS X.