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"""This is like pexpect, but will work on any file descriptor that you pass it.
So you are reponsible for opening and close the file descriptor.
$Id$
"""
from pexpect import *
import os
__all__ = ['fdspawn']
class fdspawn (spawn):
"""This is like pexpect.spawn but allows you to supply your own open file
descriptor. For example, you could use it to read through a file looking
for patterns, or to control a modem or serial device. """
def __init__ (self, fd, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None):
"""This takes a file descriptor (an int) or an object that support the
fileno() method (returning an int). All Python file-like objects
support fileno(). """
### TODO: Add better handling of trying to use fdspawn in place of spawn
### TODO: (overload to allow fdspawn to also handle commands as spawn does.
if type(fd) != type(0) and hasattr(fd, 'fileno'):
fd = fd.fileno()
if type(fd) != type(0):
raise ExceptionPexpect ('The fd argument is not an int. If this is a command string then maybe you want to use pexpect.spawn.')
try: # make sure fd is a valid file descriptor
os.fstat(fd)
except OSError:
raise ExceptionPexpect, 'The fd argument is not a valid file descriptor.'
self.args = None
self.command = None
spawn.__init__(self, None, args, timeout, maxread, searchwindowsize, logfile)
self.child_fd = fd
self.own_fd = False
self.closed = False
self.name = '<file descriptor %d>' % fd
def __del__ (self):
return
def close (self):
if self.child_fd == -1:
return
if self.own_fd:
self.close (self)
else:
self.flush()
os.close(self.child_fd)
self.child_fd = -1
self.closed = True
def isalive (self):
"""This checks if the file descriptor is still valid. If os.fstat()
does not raise an exception then we assume it is alive. """
if self.child_fd == -1:
return False
try:
os.fstat(self.child_fd)
return True
except:
return False
def terminate (self, force=False):
raise ExceptionPexpect ('This method is not valid for file descriptors.')
def kill (self, sig):
return
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