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