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1"""This is like pexpect, but will work on any file descriptor that you pass it.
2So you are reponsible for opening and close the file descriptor.
3
4$Id: fdpexpect.py 505 2007-12-26 21:33:50Z noah $
5"""
6
7from pexpect import *
8import os
9
10__all__ = ['fdspawn']
11
12class fdspawn (spawn):
13
14    """This is like pexpect.spawn but allows you to supply your own open file
15    descriptor. For example, you could use it to read through a file looking
16    for patterns, or to control a modem or serial device. """
17
18    def __init__ (self, fd, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None):
19
20        """This takes a file descriptor (an int) or an object that support the
21        fileno() method (returning an int). All Python file-like objects
22        support fileno(). """
23
24        ### TODO: Add better handling of trying to use fdspawn in place of spawn
25        ### TODO: (overload to allow fdspawn to also handle commands as spawn does.
26
27        if type(fd) != type(0) and hasattr(fd, 'fileno'):
28            fd = fd.fileno()
29
30        if type(fd) != type(0):
31            raise ExceptionPexpect ('The fd argument is not an int. If this is a command string then maybe you want to use pexpect.spawn.')
32
33        try: # make sure fd is a valid file descriptor
34            os.fstat(fd)
35        except OSError:
36            raise ExceptionPexpect, 'The fd argument is not a valid file descriptor.'
37
38        self.args = None
39        self.command = None
40        spawn.__init__(self, None, args, timeout, maxread, searchwindowsize, logfile)
41        self.child_fd = fd
42        self.own_fd = False
43        self.closed = False
44        self.name = '<file descriptor %d>' % fd
45
46    def __del__ (self):
47
48        return
49
50    def close (self):
51
52        if self.child_fd == -1:
53            return
54        if self.own_fd:
55            self.close (self)
56        else:
57            self.flush()
58            os.close(self.child_fd)
59            self.child_fd = -1
60            self.closed = True
61
62    def isalive (self):
63
64        """This checks if the file descriptor is still valid. If os.fstat()
65        does not raise an exception then we assume it is alive. """
66
67        if self.child_fd == -1:
68            return False
69        try:
70            os.fstat(self.child_fd)
71            return True
72        except:
73            return False
74
75    def terminate (self, force=False):
76
77        raise ExceptionPexpect ('This method is not valid for file descriptors.')
78
79    def kill (self, sig):
80
81        return
82
83