Source Code for Module paramiko.pipe

  1  # Copyright (C) 2003-2007  Robey Pointer <robey@lag.net> 
  2  # 
  3  # This file is part of paramiko. 
  4  # 
  5  # Paramiko is free software; you can redistribute it and/or modify it under the 
  6  # terms of the GNU Lesser General Public License as published by the Free 
  7  # Software Foundation; either version 2.1 of the License, or (at your option) 
  8  # any later version. 
  9  # 
 10  # Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY 
 11  # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR 
 12  # A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more 
 13  # details. 
 14  # 
 15  # You should have received a copy of the GNU Lesser General Public License 
 16  # along with Paramiko; if not, write to the Free Software Foundation, Inc., 
 17  # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA. 
 18   
 19  """ 
 20  Abstraction of a one-way pipe where the read end can be used in select(). 
 21  Normally this is trivial, but Windows makes it nearly impossible. 
 22   
 23  The pipe acts like an Event, which can be set or cleared. When set, the pipe 
 24  will trigger as readable in select(). 
 25  """ 
 26   
 27  import sys 
 28  import os 
 29  import socket 
 30   
 31   
 32 -def make_pipe (): 
 33      if sys.platform[:3] != 'win': 
 34          p = PosixPipe() 
 35      else: 
 36          p = WindowsPipe() 
 37      return p 
 38   
 39   
 40 -class PosixPipe (object): 
 41 -    def __init__ (self): 
 42          self._rfd, self._wfd = os.pipe() 
 43          self._set = False 
 44          self._forever = False 
 45          self._closed = False 
 46       
 47 -    def close (self): 
 48          os.close(self._rfd) 
 49          os.close(self._wfd) 
 50          # used for unit tests: 
 51          self._closed = True 
 52       
 53 -    def fileno (self): 
 54          return self._rfd 
 55   
 56 -    def clear (self): 
 57          if not self._set or self._forever: 
 58              return 
 59          os.read(self._rfd, 1) 
 60          self._set = False 
 61       
 62 -    def set (self): 
 63          if self._set or self._closed: 
 64              return 
 65          self._set = True 
 66          os.write(self._wfd, '*') 
 67       
 68 -    def set_forever (self): 
 69          self._forever = True 
 70          self.set() 
 71   
 72   
 73 -class WindowsPipe (object): 
 74      """ 
 75      On Windows, only an OS-level "WinSock" may be used in select(), but reads 
 76      and writes must be to the actual socket object. 
 77      """ 
 78 -    def __init__ (self): 
 79          serv = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
 80          serv.bind(('127.0.0.1', 0)) 
 81          serv.listen(1) 
 82       
 83          # need to save sockets in _rsock/_wsock so they don't get closed 
 84          self._rsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
 85          self._rsock.connect(('127.0.0.1', serv.getsockname()[1])) 
 86       
 87          self._wsock, addr = serv.accept() 
 88          serv.close() 
 89          self._set = False 
 90          self._forever = False 
 91          self._closed = False 
 92       
 93 -    def close (self): 
 94          self._rsock.close() 
 95          self._wsock.close() 
 96          # used for unit tests: 
 97          self._closed = True 
 98       
 99 -    def fileno (self): 
100          return self._rsock.fileno() 
101   
102 -    def clear (self): 
103          if not self._set or self._forever: 
104              return 
105          self._rsock.recv(1) 
106          self._set = False 
107       
108 -    def set (self): 
109          if self._set or self._closed: 
110              return 
111          self._set = True 
112          self._wsock.send('*') 
113   
114 -    def set_forever (self): 
115          self._forever = True 
116          self.set() 
117   
118   
119 -class OrPipe (object): 
120 -    def __init__(self, pipe): 
121          self._set = False 
122          self._partner = None 
123          self._pipe = pipe 
124       
125 -    def set(self): 
126          self._set = True 
127          if not self._partner._set: 
128              self._pipe.set() 
129       
130 -    def clear(self): 
131          self._set = False 
132          if not self._partner._set: 
133              self._pipe.clear() 
134   
135   
136 -def make_or_pipe(pipe): 
137      """ 
138      wraps a pipe into two pipe-like objects which are "or"d together to 
139      affect the real pipe. if either returned pipe is set, the wrapped pipe 
140      is set. when both are cleared, the wrapped pipe is cleared. 
141      """ 
142      p1 = OrPipe(pipe) 
143      p2 = OrPipe(pipe) 
144      p1._partner = p2 
145      p2._partner = p1 
146      return p1, p2 
147