CasperSecurity
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Tests for L{twisted.internet.fdesc}.
"""
import errno
import os
import sys
try:
import fcntl
except ImportError:
skip = "not supported on this platform"
else:
from twisted.internet import fdesc
from twisted.python.util import untilConcludes
from twisted.trial import unittest
class NonBlockingTests(unittest.SynchronousTestCase):
"""
Tests for L{fdesc.setNonBlocking} and L{fdesc.setBlocking}.
"""
def test_setNonBlocking(self):
"""
L{fdesc.setNonBlocking} sets a file description to non-blocking.
"""
r, w = os.pipe()
self.addCleanup(os.close, r)
self.addCleanup(os.close, w)
self.assertFalse(fcntl.fcntl(r, fcntl.F_GETFL) & os.O_NONBLOCK)
fdesc.setNonBlocking(r)
self.assertTrue(fcntl.fcntl(r, fcntl.F_GETFL) & os.O_NONBLOCK)
def test_setBlocking(self):
"""
L{fdesc.setBlocking} sets a file description to blocking.
"""
r, w = os.pipe()
self.addCleanup(os.close, r)
self.addCleanup(os.close, w)
fdesc.setNonBlocking(r)
fdesc.setBlocking(r)
self.assertFalse(fcntl.fcntl(r, fcntl.F_GETFL) & os.O_NONBLOCK)
class ReadWriteTests(unittest.SynchronousTestCase):
"""
Tests for L{fdesc.readFromFD}, L{fdesc.writeToFD}.
"""
def setUp(self):
"""
Create a non-blocking pipe that can be used in tests.
"""
self.r, self.w = os.pipe()
fdesc.setNonBlocking(self.r)
fdesc.setNonBlocking(self.w)
def tearDown(self):
"""
Close pipes.
"""
try:
os.close(self.w)
except OSError:
pass
try:
os.close(self.r)
except OSError:
pass
def write(self, d):
"""
Write data to the pipe.
"""
return fdesc.writeToFD(self.w, d)
def read(self):
"""
Read data from the pipe.
"""
l = []
res = fdesc.readFromFD(self.r, l.append)
if res is None:
if l:
return l[0]
else:
return b""
else:
return res
def test_writeAndRead(self):
"""
Test that the number of bytes L{fdesc.writeToFD} reports as written
with its return value are seen by L{fdesc.readFromFD}.
"""
n = self.write(b"hello")
self.assertTrue(n > 0)
s = self.read()
self.assertEqual(len(s), n)
self.assertEqual(b"hello"[:n], s)
def test_writeAndReadLarge(self):
"""
Similar to L{test_writeAndRead}, but use a much larger string to verify
the behavior for that case.
"""
orig = b"0123456879" * 10000
written = self.write(orig)
self.assertTrue(written > 0)
result = []
resultlength = 0
i = 0
while resultlength < written or i < 50:
result.append(self.read())
resultlength += len(result[-1])
# Increment a counter to be sure we'll exit at some point
i += 1
result = b"".join(result)
self.assertEqual(len(result), written)
self.assertEqual(orig[:written], result)
def test_readFromEmpty(self):
"""
Verify that reading from a file descriptor with no data does not raise
an exception and does not result in the callback function being called.
"""
l = []
result = fdesc.readFromFD(self.r, l.append)
self.assertEqual(l, [])
self.assertIsNone(result)
def test_readFromCleanClose(self):
"""
Test that using L{fdesc.readFromFD} on a cleanly closed file descriptor
returns a connection done indicator.
"""
os.close(self.w)
self.assertEqual(self.read(), fdesc.CONNECTION_DONE)
def test_writeToClosed(self):
"""
Verify that writing with L{fdesc.writeToFD} when the read end is closed
results in a connection lost indicator.
"""
os.close(self.r)
self.assertEqual(self.write(b"s"), fdesc.CONNECTION_LOST)
def test_readFromInvalid(self):
"""
Verify that reading with L{fdesc.readFromFD} when the read end is
closed results in a connection lost indicator.
"""
os.close(self.r)
self.assertEqual(self.read(), fdesc.CONNECTION_LOST)
def test_writeToInvalid(self):
"""
Verify that writing with L{fdesc.writeToFD} when the write end is
closed results in a connection lost indicator.
"""
os.close(self.w)
self.assertEqual(self.write(b"s"), fdesc.CONNECTION_LOST)
def test_writeErrors(self):
"""
Test error path for L{fdesc.writeTod}.
"""
oldOsWrite = os.write
def eagainWrite(fd, data):
err = OSError()
err.errno = errno.EAGAIN
raise err
os.write = eagainWrite
try:
self.assertEqual(self.write(b"s"), 0)
finally:
os.write = oldOsWrite
def eintrWrite(fd, data):
err = OSError()
err.errno = errno.EINTR
raise err
os.write = eintrWrite
try:
self.assertEqual(self.write(b"s"), 0)
finally:
os.write = oldOsWrite
class CloseOnExecTests(unittest.SynchronousTestCase):
"""
Tests for L{fdesc._setCloseOnExec} and L{fdesc._unsetCloseOnExec}.
"""
program = """
import os, errno
try:
os.write(%d, b'lul')
except OSError as e:
if e.errno == errno.EBADF:
os._exit(0)
os._exit(5)
except BaseException:
os._exit(10)
else:
os._exit(20)
"""
def _execWithFileDescriptor(self, fObj):
pid = os.fork()
if pid == 0:
try:
os.execv(
sys.executable,
[sys.executable, "-c", self.program % (fObj.fileno(),)],
)
except BaseException:
import traceback
traceback.print_exc()
os._exit(30)
else:
# On Linux wait(2) doesn't seem ever able to fail with EINTR but
# POSIX seems to allow it and on macOS it happens quite a lot.
return untilConcludes(os.waitpid, pid, 0)[1]
def test_setCloseOnExec(self):
"""
A file descriptor passed to L{fdesc._setCloseOnExec} is not inherited
by a new process image created with one of the exec family of
functions.
"""
with open(self.mktemp(), "wb") as fObj:
fdesc._setCloseOnExec(fObj.fileno())
status = self._execWithFileDescriptor(fObj)
self.assertTrue(os.WIFEXITED(status))
self.assertEqual(os.WEXITSTATUS(status), 0)
def test_unsetCloseOnExec(self):
"""
A file descriptor passed to L{fdesc._unsetCloseOnExec} is inherited by
a new process image created with one of the exec family of functions.
"""
with open(self.mktemp(), "wb") as fObj:
fdesc._setCloseOnExec(fObj.fileno())
fdesc._unsetCloseOnExec(fObj.fileno())
status = self._execWithFileDescriptor(fObj)
self.assertTrue(os.WIFEXITED(status))
self.assertEqual(os.WEXITSTATUS(status), 20)