2007-08-12 20:49:01 +08:00
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from os.path import join, normcase, abspath, sep
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def safe_join(base, *paths):
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"""
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Joins one or more path components to the base path component intelligently.
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Returns a normalized, absolute version of the final path.
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The final path must be located inside of the base path component (otherwise
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a ValueError is raised).
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"""
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# We need to use normcase to ensure we don't false-negative on case
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# insensitive operating systems (like Windows).
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final_path = normcase(abspath(join(base, *paths)))
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base_path = normcase(abspath(base))
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base_path_len = len(base_path)
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# Ensure final_path starts with base_path and that the next character after
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# the final path is os.sep (or nothing, in which case final_path must be
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# equal to base_path).
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if not final_path.startswith(base_path) \
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or final_path[base_path_len:base_path_len+1] not in ('', sep):
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raise ValueError('the joined path is located outside of the base path'
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' component')
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return final_path
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