classification
Title: Accepting of os functions of (path, dir_fd) pair as argument
Type: Stage: resolved
Components: Library (Lib) Versions: Python 3.3
process
Status: closed Resolution: rejected
Dependencies: Superseder:
Assigned To: Nosy List: Arfrever, larry, ncoghlan, serhiy.storchaka
Priority: normal Keywords:

Created on 2012-06-27 09:27 by serhiy.storchaka, last changed 2012-06-28 07:08 by ncoghlan. This issue is now closed.

Messages (3)
msg164132 - (view) Author: Serhiy Storchaka (serhiy.storchaka) * (Python committer) Date: 2012-06-27 09:27
Since many of os functions were polymorphic in its first argument (path or fd), the logical continuation is to add a (path, dir_fd) pair as yet one case of this argument. In any case dir_fd is incopatible with fd. This simplifies the code of certain functions which takes patch and dir_fd and pass them to lower level without changes, or that use same patch and dir_fd in calls of several functions. This freely adds support of dir_fd to many functions, such as os.path.isdir. This solves the problem of naming multiple dir_fd arguments (src_dir_fd/dst_dir_fd looks ugly). This saves a pre-3.3 signature of some functions, which will facilitate the use of decorators and improve compatibility with alternative implementations.
msg164138 - (view) Author: Larry Hastings (larry) * (Python committer) Date: 2012-06-27 09:59
I dislike this and always have.  I think it would look ugly and be obnoxious to use.

If you really think you can get this in for 3.3, you will have to bring it up with Georg.  I think your chances are about zero.
msg164223 - (view) Author: Nick Coghlan (ncoghlan) * (Python committer) Date: 2012-06-28 07:08
Correctly avoiding symlink attacks, which is the whole reason the POSIX *at variants and the dir_fd parameters were added, is not trivial in general. os.fwalk and shutil.rmtree went through many iterations before reaching a state where they should successfully avoid the problem.

Simply passing a (path, dir_fd) 2-tuple instead of a string and calling it done is highly unlikely to produce a secure result, thus rather missing the point of the exercise.
History
Date User Action Args
2012-06-28 07:08:16ncoghlansetstatus: open -> closed

nosy: + ncoghlan
messages: + msg164223

resolution: rejected
stage: resolved
2012-06-27 15:51:48Arfreversetnosy: + Arfrever
2012-06-27 09:59:44larrysetmessages: + msg164138
2012-06-27 09:34:18serhiy.storchakasetnosy: + larry
2012-06-27 09:27:19serhiy.storchakacreate