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Fully refactored subprocess handling on all platforms....
Fully refactored subprocess handling on all platforms. Now we have all process-related code in utils.process, which itself imports from platform-specific files as needed. On posix, we have reliable asynchronous delivery of stdout and stderr, and on win32 at least we have the basics that subprocess.py provides, since pexpect is not available. We also now support robust killing of subprocesses that may capture SIGINT: one SIGINT on our end is sent to the subprocess, but then we kill it, to prevent a rogue subprocess from hijacking the ipython console. Note that on posix, we now depend on pexpect, but we ship our own copy to users which we'll use if there's no system pexpect installed. UNC path handling for windows was implemented as a context manager called AvoidUNCPath.

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_process_win32.py
137 lines | 4.1 KiB | text/x-python | PythonLexer
"""Windows-specific implementation of process utilities.
This file is only meant to be imported by process.py, not by end-users.
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2010 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from __future__ import print_function
# stdlib
import os
import sys
from subprocess import STDOUT
# our own imports
from ._process_common import read_no_interrupt, process_handler
#-----------------------------------------------------------------------------
# Function definitions
#-----------------------------------------------------------------------------
class AvoidUNCPath(object):
"""A context manager to protect command execution from UNC paths.
In the Win32 API, commands can't be invoked with the cwd being a UNC path.
This context manager temporarily changes directory to the 'C:' drive on
entering, and restores the original working directory on exit.
The context manager returns the starting working directory *if* it made a
change and None otherwise, so that users can apply the necessary adjustment
to their system calls in the event of a change.
Example
-------
::
cmd = 'dir'
with AvoidUNCPath() as path:
if path is not None:
cmd = '"pushd %s &&"%s' % (path, cmd)
os.system(cmd)
"""
def __enter__(self):
self.path = os.getcwd()
self.is_unc_path = self.path.startswith(r"\\")
if self.is_unc_path:
# change to c drive (as cmd.exe cannot handle UNC addresses)
os.chdir("C:")
return self.path
def __exit__(self, exc_type, exc_value, traceback):
if self.is_unc_path:
os.chdir(self.path)
def _find_cmd(cmd):
"""Find the full path to a .bat or .exe using the win32api module."""
try:
from win32api import SearchPath
except ImportError:
raise ImportError('you need to have pywin32 installed for this to work')
else:
PATH = os.environ['PATH']
extensions = ['.exe', '.com', '.bat', '.py']
path = None
for ext in extensions:
try:
path = SearchPath(PATH, cmd + ext)[0]
except:
pass
if path is None:
raise OSError("command %r not found" % cmd)
else:
return path
def _system_body(p):
"""Callback for _system."""
for line in read_no_interrupt(p.stdout).splitlines():
print(line, file=sys.stdout)
for line in read_no_interrupt(p.stderr).splitlines():
print(line, file=sys.stderr)
def system(cmd):
"""Win32 version of os.system() that works with network shares.
Note that this implementation returns None, as meant for use in IPython.
Parameters
----------
cmd : str
A command to be executed in the system shell.
Returns
-------
None : we explicitly do NOT return the subprocess status code, as this
utility is meant to be used extensively in IPython, where any return value
would trigger :func:`sys.displayhook` calls.
"""
with AvoidUNCPath() as path:
if path is not None:
cmd = '"pushd %s &&"%s' % (path, cmd)
process_handler(cmd, _system_body)
def getoutput(cmd):
"""Return standard output of executing cmd in a shell.
Accepts the same arguments as os.system().
Parameters
----------
cmd : str
A command to be executed in the system shell.
Returns
-------
stdout : str
"""
with AvoidUNCPath() as path:
if path is not None:
cmd = '"pushd %s &&"%s' % (path, cmd)
out = process_handler(cmd, lambda p: p.communicate()[0], STDOUT)
if out is None:
out = ''
return out