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78 lines
2.8 KiB
78 lines
2.8 KiB
# -*- coding: utf-8 -*-
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__author__ = "Daniel Roy Greenfeld"
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__email__ = "pydanny@gmail.com"
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__version__ = "0.5.2"
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import os
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import sys
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try: # Forced testing
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from shutil import which
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except ImportError: # Forced testing
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# Versions prior to Python 3.3 don't have shutil.which
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def which(cmd, mode=os.F_OK | os.X_OK, path=None):
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"""Given a command, mode, and a PATH string, return the path which
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conforms to the given mode on the PATH, or None if there is no such
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file.
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`mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
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of os.environ.get("PATH"), or can be overridden with a custom search
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path.
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Note: This function was backported from the Python 3 source code.
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"""
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# Check that a given file can be accessed with the correct mode.
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# Additionally check that `file` is not a directory, as on Windows
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# directories pass the os.access check.
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def _access_check(fn, mode):
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return os.path.exists(fn) and os.access(fn, mode) and not os.path.isdir(fn)
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# If we're given a path with a directory part, look it up directly
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# rather than referring to PATH directories. This includes checking
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# relative to the current directory, e.g. ./script
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if os.path.dirname(cmd):
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if _access_check(cmd, mode):
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return cmd
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return None
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if path is None:
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path = os.environ.get("PATH", os.defpath)
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if not path:
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return None
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path = path.split(os.pathsep)
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if sys.platform == "win32":
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# The current directory takes precedence on Windows.
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if os.curdir not in path:
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path.insert(0, os.curdir)
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# PATHEXT is necessary to check on Windows.
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pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
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# See if the given file matches any of the expected path
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# extensions. This will allow us to short circuit when given
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# "python.exe". If it does match, only test that one, otherwise we
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# have to try others.
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if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
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files = [cmd]
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else:
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files = [cmd + ext for ext in pathext]
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else:
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# On other platforms you don't have things like PATHEXT to tell you
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# what file suffixes are executable, so just pass on cmd as-is.
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files = [cmd]
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seen = set()
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for dir in path:
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normdir = os.path.normcase(dir)
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if normdir not in seen:
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seen.add(normdir)
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for thefile in files:
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name = os.path.join(dir, thefile)
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if _access_check(name, mode):
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return name
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return None
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