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# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
"""
Abstraction of a one-way pipe where the read end can be used in select().
Normally this is trivial, but Windows makes it nearly impossible.
The pipe acts like an Event, which can be set or cleared. When set, the pipe
will trigger as readable in select().
"""
import sys
import os
import socket
def make_pipe ():
if sys.platform[:3] != 'win':
p = PosixPipe()
else:
p = WindowsPipe()
return p
class PosixPipe (object):
def __init__ (self):
self._rfd, self._wfd = os.pipe()
self._set = False
self._forever = False
self._closed = False
def close (self):
os.close(self._rfd)
os.close(self._wfd)
# used for unit tests:
self._closed = True
def fileno (self):
return self._rfd
def clear (self):
if not self._set or self._forever:
return
os.read(self._rfd, 1)
self._set = False
def set (self):
if self._set or self._closed:
return
self._set = True
os.write(self._wfd, '*')
def set_forever (self):
self._forever = True
self.set()
class WindowsPipe (object):
"""
On Windows, only an OS-level "WinSock" may be used in select(), but reads
and writes must be to the actual socket object.
"""
def __init__ (self):
serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serv.bind(('127.0.0.1', 0))
serv.listen(1)
# need to save sockets in _rsock/_wsock so they don't get closed
self._rsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._rsock.connect(('127.0.0.1', serv.getsockname()[1]))
self._wsock, addr = serv.accept()
serv.close()
self._set = False
self._forever = False
self._closed = False
def close (self):
self._rsock.close()
self._wsock.close()
# used for unit tests:
self._closed = True
def fileno (self):
return self._rsock.fileno()
def clear (self):
if not self._set or self._forever:
return
self._rsock.recv(1)
self._set = False
def set (self):
if self._set or self._closed:
return
self._set = True
self._wsock.send('*')
def set_forever (self):
self._forever = True
self.set()
class OrPipe (object):
def __init__(self, pipe):
self._set = False
self._partner = None
self._pipe = pipe
def set(self):
self._set = True
if not self._partner._set:
self._pipe.set()
def clear(self):
self._set = False
if not self._partner._set:
self._pipe.clear()
def make_or_pipe(pipe):
"""
wraps a pipe into two pipe-like objects which are "or"d together to
affect the real pipe. if either returned pipe is set, the wrapped pipe
is set. when both are cleared, the wrapped pipe is cleared.
"""
p1 = OrPipe(pipe)
p2 = OrPipe(pipe)
p1._partner = p2
p2._partner = p1
return p1, p2
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