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