cpython: 994659efa292 (original) (raw)

Mercurial > cpython

changeset 74974:994659efa292 3.2

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

Gregory P. Smith greg@krypto.org
date	Thu, 16 Feb 2012 00:29:12 -0800
parents	824ddf6a30f2
children	72c8b54c1050
files	Lib/pty.py Lib/test/test_pty.py
diffstat	2 files changed, 101 insertions(+), 6 deletions(-)[+] [-] Lib/pty.py 16 Lib/test/test_pty.py 91

line wrap: on

line diff

--- a/Lib/pty.py +++ b/Lib/pty.py @@ -142,15 +142,21 @@ def _copy(master_fd, master_read=_read, Copies pty master -> standard output (master_read) standard input -> pty master (stdin_read)"""

while 1:
```
   rfds, wfds, xfds = select([](#l1.8)
```

           [master_fd, STDIN_FILENO], [], [])[](#l1.9)

fds = [master_fd, STDIN_FILENO]
while True:

   rfds, wfds, xfds = select(fds, [], [])[](#l1.12)
   if master_fd in rfds:[](#l1.13)
       data = master_read(master_fd)[](#l1.14)

       os.write(STDOUT_FILENO, data)[](#l1.15)

       if not data:  # Reached EOF.[](#l1.16)

           fds.remove(master_fd)[](#l1.17)

```
       else:[](#l1.18)
```

           os.write(STDOUT_FILENO, data)[](#l1.19)
   if STDIN_FILENO in rfds:[](#l1.20)
       data = stdin_read(STDIN_FILENO)[](#l1.21)

       _writen(master_fd, data)[](#l1.22)

```
       if not data:[](#l1.23)
```

           fds.remove(STDIN_FILENO)[](#l1.24)

```
       else:[](#l1.25)
```

           _writen(master_fd, data)[](#l1.26)

def spawn(argv, master_read=_read, stdin_read=_read): """Create a spawned process."""

--- a/Lib/test/test_pty.py +++ b/Lib/test/test_pty.py @@ -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[](#l2.22)

   self.orig_stdout_fileno = pty.STDOUT_FILENO[](#l2.23)

   self.orig_pty_select = pty.select[](#l2.24)

   self.fds = []  # A list of file descriptors to close.[](#l2.25)

   self.select_rfds_lengths = [][](#l2.26)

   self.select_rfds_results = [][](#l2.27)

def tearDown(self):

   pty.STDIN_FILENO = self.orig_stdin_fileno[](#l2.30)

   pty.STDOUT_FILENO = self.orig_stdout_fileno[](#l2.31)

   pty.select = self.orig_pty_select[](#l2.32)

```
   for fd in self.fds:[](#l2.33)
```
```
       try:[](#l2.34)
```
```
           os.close(fd)[](#l2.35)
```
```
       except:[](#l2.36)
```
```
           pass[](#l2.37)
```

def _pipe(self):
```
   pipe_fds = os.pipe()[](#l2.40)
```
```
   self.fds.extend(pipe_fds)[](#l2.41)
```
```
   return pipe_fds[](#l2.42)
```

def _mock_select(self, rfds, wfds, xfds):

   # This will raise IndexError when no more expected calls exist.[](#l2.45)

   self.assertEqual(self.select_rfds_lengths.pop(0), len(rfds))[](#l2.46)

   return self.select_rfds_results.pop(0), [], [][](#l2.47)

def test__copy_to_each(self):

   """Test the normal data case on both master_fd and stdin."""[](#l2.50)

   read_from_stdout_fd, mock_stdout_fd = self._pipe()[](#l2.51)

   pty.STDOUT_FILENO = mock_stdout_fd[](#l2.52)

   mock_stdin_fd, write_to_stdin_fd = self._pipe()[](#l2.53)

   pty.STDIN_FILENO = mock_stdin_fd[](#l2.54)

   socketpair = socket.socketpair()[](#l2.55)

   masters = [s.fileno() for s in socketpair][](#l2.56)

```
   self.fds.extend(masters)[](#l2.57)
```

   # Feed data.  Smaller than PIPEBUF.  These writes will not block.[](#l2.59)

   os.write(masters[1], b'from master')[](#l2.60)

   os.write(write_to_stdin_fd, b'from stdin')[](#l2.61)

   # Expect two select calls, the last one will cause IndexError[](#l2.63)

   pty.select = self._mock_select[](#l2.64)

   self.select_rfds_lengths.append(2)[](#l2.65)

   self.select_rfds_results.append([mock_stdin_fd, masters[0]])[](#l2.66)

   self.select_rfds_lengths.append(2)[](#l2.67)

   with self.assertRaises(IndexError):[](#l2.69)

```
       pty._copy(masters[0])[](#l2.70)
```

   # Test that the right data went to the right places.[](#l2.72)

   rfds = select.select([read_from_stdout_fd, masters[1]], [], [], 0)[0][](#l2.73)

   self.assertSameElements([read_from_stdout_fd, masters[1]], rfds)[](#l2.74)

   self.assertEqual(os.read(read_from_stdout_fd, 20), b'from master')[](#l2.75)

   self.assertEqual(os.read(masters[1], 20), b'from stdin')[](#l2.76)

def test__copy_eof_on_all(self):

   """Test the empty read EOF case on both master_fd and stdin."""[](#l2.79)

   read_from_stdout_fd, mock_stdout_fd = self._pipe()[](#l2.80)

   pty.STDOUT_FILENO = mock_stdout_fd[](#l2.81)

   mock_stdin_fd, write_to_stdin_fd = self._pipe()[](#l2.82)

   pty.STDIN_FILENO = mock_stdin_fd[](#l2.83)

   socketpair = socket.socketpair()[](#l2.84)

   masters = [s.fileno() for s in socketpair][](#l2.85)

```
   self.fds.extend(masters)[](#l2.86)
```

```
   os.close(masters[1])[](#l2.88)
```
```
   socketpair[1].close()[](#l2.89)
```

   os.close(write_to_stdin_fd)[](#l2.90)

   # Expect two select calls, the last one will cause IndexError[](#l2.92)

   pty.select = self._mock_select[](#l2.93)

   self.select_rfds_lengths.append(2)[](#l2.94)

   self.select_rfds_results.append([mock_stdin_fd, masters[0]])[](#l2.95)

   # We expect that both fds were removed from the fds list as they[](#l2.96)

   # both encountered an EOF before the second select call.[](#l2.97)

   self.select_rfds_lengths.append(0)[](#l2.98)

   with self.assertRaises(IndexError):[](#l2.100)

```
       pty._copy(masters[0])[](#l2.101)
```

+ + def test_main(verbose=None): try:

```
   run_unittest(PtyTest)[](#l2.106)
```

   run_unittest(SmallPtyTests, PtyTest)[](#l2.107)

finally: reap_children()