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cl349@firebug.cl.cam.ac.uk
a5a8a98d1f
XendDomain.py: Handle error case where exec fails. xpopen.py: Exit with 127 if exec fails. Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
170 lines
6.6 KiB
Python
170 lines
6.6 KiB
Python
#
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# Copyright (c) 2001, 2002, 2003, 2004 Python Software Foundation; All Rights Reserved
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#
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# PSF LICENSE AGREEMENT FOR PYTHON 2.3
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# ------------------------------------
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#
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# 1. This LICENSE AGREEMENT is between the Python Software Foundation
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# ("PSF"), and the Individual or Organization ("Licensee") accessing and
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# otherwise using Python 2.3 software in source or binary form and its
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# associated documentation.
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#
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# 2. Subject to the terms and conditions of this License Agreement, PSF
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# hereby grants Licensee a nonexclusive, royalty-free, world-wide
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# license to reproduce, analyze, test, perform and/or display publicly,
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# prepare derivative works, distribute, and otherwise use Python 2.3
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# alone or in any derivative version, provided, however, that PSF's
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# License Agreement and PSF's notice of copyright, i.e., "Copyright (c)
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# 2001, 2002, 2003, 2004 Python Software Foundation; All Rights Reserved" are
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# retained in Python 2.3 alone or in any derivative version prepared by
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# Licensee.
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#
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# 3. In the event Licensee prepares a derivative work that is based on
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# or incorporates Python 2.3 or any part thereof, and wants to make
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# the derivative work available to others as provided herein, then
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# Licensee hereby agrees to include in any such work a brief summary of
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# the changes made to Python 2.3.
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#
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# 4. PSF is making Python 2.3 available to Licensee on an "AS IS"
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# basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
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# IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
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# DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
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# FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON 2.3 WILL NOT
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# INFRINGE ANY THIRD PARTY RIGHTS.
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#
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# 5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
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# 2.3 FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
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# A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON 2.3,
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# OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
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#
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# 6. This License Agreement will automatically terminate upon a material
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# breach of its terms and conditions.
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#
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# 7. Nothing in this License Agreement shall be deemed to create any
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# relationship of agency, partnership, or joint venture between PSF and
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# Licensee. This License Agreement does not grant permission to use PSF
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# trademarks or trade name in a trademark sense to endorse or promote
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# products or services of Licensee, or any third party.
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#
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# 8. By copying, installing or otherwise using Python 2.3, Licensee
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# agrees to be bound by the terms and conditions of this License
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# Agreement.
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#
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# Modifications: Copyright (c) 2005 Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
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# - add support for excluding a list of file descriptors from being
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# closed, allowing access to those file descriptors from the command.
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#
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"""Spawn a command with pipes to its stdin, stdout, and optionally stderr.
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The normal os.popen(cmd, mode) call spawns a shell command and provides a
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file interface to just the input or output of the process depending on
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whether mode is 'r' or 'w'. This module provides the functions xpopen2(cmd)
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and xpopen3(cmd) which return two or three pipes to the spawned command.
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Optionally exclude a list of file descriptors from being closed, allowing
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access to those file descriptors from the command.
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"""
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import os
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import sys
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try:
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MAXFD = os.sysconf('SC_OPEN_MAX')
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except (AttributeError, ValueError):
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MAXFD = 256
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_active = []
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def _cleanup():
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for inst in _active[:]:
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inst.poll()
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class xPopen3:
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"""Class representing a child process. Normally instances are created
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by the factory functions popen2() and popen3()."""
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sts = -1 # Child not completed yet
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def __init__(self, cmd, capturestderr=False, bufsize=-1, passfd=()):
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"""The parameter 'cmd' is the shell command to execute in a
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sub-process. The 'capturestderr' flag, if true, specifies that
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the object should capture standard error output of the child process.
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The default is false. If the 'bufsize' parameter is specified, it
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specifies the size of the I/O buffers to/from the child process."""
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_cleanup()
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self.passfd = passfd
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p2cread, p2cwrite = os.pipe()
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c2pread, c2pwrite = os.pipe()
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if capturestderr:
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errout, errin = os.pipe()
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self.pid = os.fork()
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if self.pid == 0:
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# Child
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os.dup2(p2cread, 0)
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os.dup2(c2pwrite, 1)
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if capturestderr:
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os.dup2(errin, 2)
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self._run_child(cmd)
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os.close(p2cread)
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self.tochild = os.fdopen(p2cwrite, 'w', bufsize)
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os.close(c2pwrite)
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self.fromchild = os.fdopen(c2pread, 'r', bufsize)
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if capturestderr:
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os.close(errin)
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self.childerr = os.fdopen(errout, 'r', bufsize)
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else:
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self.childerr = None
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_active.append(self)
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def _run_child(self, cmd):
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if isinstance(cmd, basestring):
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cmd = ['/bin/sh', '-c', cmd]
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for i in range(3, MAXFD):
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if i in self.passfd:
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continue
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try:
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os.close(i)
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except OSError:
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pass
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try:
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os.execvp(cmd[0], cmd)
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finally:
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os._exit(127)
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def poll(self):
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"""Return the exit status of the child process if it has finished,
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or -1 if it hasn't finished yet."""
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if self.sts < 0:
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try:
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pid, sts = os.waitpid(self.pid, os.WNOHANG)
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if pid == self.pid:
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self.sts = sts
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_active.remove(self)
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except os.error:
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pass
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return self.sts
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def wait(self):
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"""Wait for and return the exit status of the child process."""
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if self.sts < 0:
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pid, sts = os.waitpid(self.pid, 0)
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if pid == self.pid:
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self.sts = sts
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_active.remove(self)
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return self.sts
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def xpopen2(cmd, bufsize=-1, mode='t', passfd=[]):
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"""Execute the shell command 'cmd' in a sub-process. If 'bufsize' is
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specified, it sets the buffer size for the I/O pipes. The file objects
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(child_stdout, child_stdin) are returned."""
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inst = xPopen3(cmd, False, bufsize, passfd)
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return inst.fromchild, inst.tochild
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def xpopen3(cmd, bufsize=-1, mode='t', passfd=[]):
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"""Execute the shell command 'cmd' in a sub-process. If 'bufsize' is
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specified, it sets the buffer size for the I/O pipes. The file objects
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(child_stdout, child_stdin, child_stderr) are returned."""
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inst = xPopen3(cmd, True, bufsize, passfd)
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return inst.fromchild, inst.tochild, inst.childerr
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