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# -*- test-case-name: twisted.test.test_fdesc -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Utility functions for dealing with POSIX file descriptors.
"""
import os
import errno
try:
import fcntl
except ImportError:
fcntl = None
# twisted imports
from twisted.internet.main import CONNECTION_LOST, CONNECTION_DONE
def setNonBlocking(fd):
"""
Set the file description of the given file descriptor to non-blocking.
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
flags = flags | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def setBlocking(fd):
"""
Set the file description of the given file descriptor to blocking.
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFL)
flags = flags & ~os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
if fcntl is None:
# fcntl isn't available on Windows. By default, handles aren't
# inherited on Windows, so we can do nothing here.
_setCloseOnExec = _unsetCloseOnExec = lambda fd: None
else:
def _setCloseOnExec(fd):
"""
Make a file descriptor close-on-exec.
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFD)
flags = flags | fcntl.FD_CLOEXEC
fcntl.fcntl(fd, fcntl.F_SETFD, flags)
def _unsetCloseOnExec(fd):
"""
Make a file descriptor close-on-exec.
"""
flags = fcntl.fcntl(fd, fcntl.F_GETFD)
flags = flags & ~fcntl.FD_CLOEXEC
fcntl.fcntl(fd, fcntl.F_SETFD, flags)
def readFromFD(fd, callback):
"""
Read from file descriptor, calling callback with resulting data.
If successful, call 'callback' with a single argument: the
resulting data.
Returns same thing FileDescriptor.doRead would: CONNECTION_LOST,
CONNECTION_DONE, or None.
@type fd: C{int}
@param fd: non-blocking file descriptor to be read from.
@param callback: a callable which accepts a single argument. If
data is read from the file descriptor it will be called with this
data. Handling exceptions from calling the callback is up to the
caller.
Note that if the descriptor is still connected but no data is read,
None will be returned but callback will not be called.
@return: CONNECTION_LOST on error, CONNECTION_DONE when fd is
closed, otherwise None.
"""
try:
output = os.read(fd, 8192)
except (OSError, IOError) as ioe:
if ioe.args[0] in (errno.EAGAIN, errno.EINTR):
return
else:
return CONNECTION_LOST
if not output:
return CONNECTION_DONE
callback(output)
def writeToFD(fd, data):
"""
Write data to file descriptor.
Returns same thing FileDescriptor.writeSomeData would.
@type fd: C{int}
@param fd: non-blocking file descriptor to be written to.
@type data: C{str} or C{buffer}
@param data: bytes to write to fd.
@return: number of bytes written, or CONNECTION_LOST.
"""
try:
return os.write(fd, data)
except (OSError, IOError) as io:
if io.errno in (errno.EAGAIN, errno.EINTR):
return 0
return CONNECTION_LOST
__all__ = ["setNonBlocking", "setBlocking", "readFromFD", "writeToFD"]
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