Jason R. Coombs <jar...@jaraco.com> added the comment: I've now completed all of the aforementioned tasks.
1) Kernel32 does not need to be freed. It is not freed by other calls after which this additional code was modeled. Additionally, the MSDN indicates that it should only be freed by the module that loaded the handle (which is not this one). 2) Functions that could be made inline have been made inline. 3) The todo, detection of whether a symlink target is a directory, has been implemented. 4) A unit test with three tests has been added. This test has not been integrated into the larger test suite, but must be run explicitly (for now). The unit test passes with no failures on Windows Vista as written. Some issues still remain. A) In general, there is a implementation mismatch between Posix and Windows symlinks. In particular, Windows maintains that a symlink is either for a directory or for a file, regardless of the existence of the target. Posix instead treats all symlinks like (special) files but determines the directory status based on the target. This mismatch causes more specific problems. B) Existing unit tests in test_os.py are going to fail (and maybe others). In particular, they will fail because they attempt to remove symlinks to directories using os.remove. Windows expects the use of os.rmdir for directory-like symlinks (that is, symlinks who's original destination was a directory or who's target_is_directory was set to true at the time it was created). The unit test included with the patch illustrates some of these nuances. C) Because lstat hides the directory status of a symlink (i.e. clears S_IFLNK), it is not always possible to determine whether a symlink should be removed using os.remove or os.rmdir. Specifically, if the symlink has no target or a directory symlink references a file, the user will only know to call os.rmdir when os.remove fails with a WindowsError. I see these issues break down into two categories: I) How to remove a symlink? (a) Should os.remove be rewritten to handle directory symlinks on Windows? This method would provide the best compatibility with existing code. (b) Or, do we require python authors to manually determine which method to call to remove a symlink? This approach is less intrusive, but really doesn't provide an effective solution, as it's only partly compatible with Posix implementations. II) How to detect a directory symlink? In either case of (I), there needs to be an implementation to detect directoryness of a symlink. (a) Create a new function in posixmodule that exposes the directory bit of a symlink, perhaps "is_symlink_directory", which always returns false except on Windows. (b) Change win_lstat to leave the S_IFDIR bit in tact and modify S_ISLNK to ignore that bit. Then is_symlink_directory becomes S_ISDIR(lstat_mode) and S_ISLNK(lstat_mode). Alternately, maybe trying to fit the Windows APIs into Posix compatibility is the wrong approach. Maybe instead there should be a Python abstraction layer for symlink handling. I think we're close with the existing approach, but I'm somewhat worried that we will continue to find edge cases that break because of the differences in assumptions about the two implementations. I think this is getting very close. I appreciate all the help and support. ---------- Added file: http://bugs.python.org/file14195/windows symlink draft 5.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue1578269> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
