88 lines
2.5 KiB
Python
88 lines
2.5 KiB
Python
"""
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Helper functions for interacting with the shell, and consuming shell-style
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parameters provided in config files.
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"""
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import os
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import shlex
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import subprocess
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__all__ = ['WindowsParser', 'PosixParser', 'NativeParser']
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class CommandLineParser:
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"""
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An object that knows how to split and join command-line arguments.
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It must be true that ``argv == split(join(argv))`` for all ``argv``.
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The reverse neednt be true - `join(split(cmd))` may result in the addition
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or removal of unnecessary escaping.
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"""
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@staticmethod
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def join(argv):
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""" Join a list of arguments into a command line string """
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raise NotImplementedError
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@staticmethod
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def split(cmd):
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""" Split a command line string into a list of arguments """
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raise NotImplementedError
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class WindowsParser:
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"""
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The parsing behavior used by `subprocess.call("string")` on Windows, which
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matches the Microsoft C/C++ runtime.
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Note that this is _not_ the behavior of cmd.
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"""
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@staticmethod
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def join(argv):
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# note that list2cmdline is specific to the windows syntax
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return subprocess.list2cmdline(argv)
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@staticmethod
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def split(cmd):
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import ctypes # guarded import for systems without ctypes
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try:
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ctypes.windll
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except AttributeError:
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raise NotImplementedError
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# Windows has special parsing rules for the executable (no quotes),
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# that we do not care about - insert a dummy element
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if not cmd:
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return []
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cmd = 'dummy ' + cmd
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CommandLineToArgvW = ctypes.windll.shell32.CommandLineToArgvW
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CommandLineToArgvW.restype = ctypes.POINTER(ctypes.c_wchar_p)
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CommandLineToArgvW.argtypes = (ctypes.c_wchar_p, ctypes.POINTER(ctypes.c_int))
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nargs = ctypes.c_int()
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lpargs = CommandLineToArgvW(cmd, ctypes.byref(nargs))
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args = [lpargs[i] for i in range(nargs.value)]
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assert not ctypes.windll.kernel32.LocalFree(lpargs)
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# strip the element we inserted
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assert args[0] == "dummy"
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return args[1:]
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class PosixParser:
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"""
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The parsing behavior used by `subprocess.call("string", shell=True)` on Posix.
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"""
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@staticmethod
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def join(argv):
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return ' '.join(shlex.quote(arg) for arg in argv)
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@staticmethod
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def split(cmd):
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return shlex.split(cmd, posix=True)
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if os.name == 'nt':
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NativeParser = WindowsParser
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elif os.name == 'posix':
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NativeParser = PosixParser
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