[ python-Bugs-755617 ] os module: Need a better description of " mode"
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Mon Jul 18 10:17:53 CEST 2005
Bugs item #755617, was opened at 2003-06-17 02:13
Message generated for change (Comment added) made by birkenfeld
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Category: Documentation
Group: Python 2.3
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Matthew Shomphe (mshomphe)
>Assigned to: Reinhold Birkenfeld (birkenfeld)
Summary: os module: Need a better description of "mode"
Initial Comment:
The page <http://www.python.
org/doc/current/lib/os-file-dir.html> says the following
about the function os.chmod:
chmod(path, mode)
Change the mode of path to the numeric mode.
Availability: Unix, Windows.
The "mode" values are unclear. It turns out that the
UNIX file permission set (e.g., 0666 for read/writeable)
works with the Windows set (where 0666 translates to
33206).
Is it possible to describe the file permissions in more
detail in the documentation at this point?
Attached is an email thread discussing this
documentation issue.
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>Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-07-18 10:17
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Added this note to the chmod docs:
Although Windows supports chmod, you can only set the
file's read-only flag with this function (via the
\code{S_IWRITE}
and \code{S_IREAD} constants or a corresponding integer value).
All other bits are ignored.
Doc/lib/libos.tex r1.164, r1.146.2.10.
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Comment By: Reinhold Birkenfeld (birkenfeld)
Date: 2005-06-05 20:28
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I think the wording suggested by logistix would be a good
addition to the docs.
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Comment By: logistix (logistix)
Date: 2003-06-17 21:31
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Something like:
"NOTE: Although Windows supports chmod, it incorporates
much different functionality than a typical Unix user would
expect. Please refer to Microsofts documentation for more
details."
would be nice.
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Comment By: Christopher Blunck (blunck2)
Date: 2003-06-17 17:18
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Tim-
I captured what Matthew Shomphe recommended into patch 755677
(http://www.python.org/sf/755677). Hope this helps.
-c
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Comment By: Tim Peters (tim_one)
Date: 2003-06-17 16:49
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Then please suggest the actual text you want to see in the
docs. I can't do it for you (for example, chmod has always
done exactly what I've wanted it to do on Windows -- but
then I've never wanted to do anything with it on Windows
beyond fiddling the readonly bit).
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Comment By: logistix (logistix)
Date: 2003-06-17 07:35
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All I'm saying is that although chmod is valid windows call, it
will not produce the effect that most users expect. There's
no harm in calling it, but it's not going to accomplish what
most users want it to do. This information is more important
to a user than other inconsistencies in the Windows
implementation. (i.e. os.stat returning a value that is
different than chmod set)
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Comment By: Christopher Blunck (blunck2)
Date: 2003-06-17 05:37
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see patch 755677
sheesh neal, you couldn't patch this? ;-)
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Comment By: Tim Peters (tim_one)
Date: 2003-06-17 05:28
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Well, let's not overreact here -- MS's _chmod simply calls the
Win32 SetFileAttributes(), and the only thing it can change is
the FILE_ATTRIBUTE_READONLY flag. That's all part of
Windows base services, and makes sense on FAT too.
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Comment By: logistix (logistix)
Date: 2003-06-17 04:51
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Realistically, you should NEVER intentionally use chmod to set
file permissions on Windows. The FAT filesystem has no
permissions, and NTFS has ACLs which are much too complex
to map to a chmod style call. MS only has chmod support so
they can claim some level of posix compliance.
I'm not saying you should drop the ability to call os.chmod on
windows, but perhaps the docs should say that its not the
recommended way of doing things. Unfortunately, there's not
a recommended way of setting security that'll work on all
Windows platforms either (although I'd start with os.popen
("cacls ...") Even win32security requires some serious
programming just to get started with manipulating ACLs.
Typical security looks something like this:
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\grant>xcacls "\Program files"
C:\Program Files BUILTIN\Users:R
BUILTIN\Users:(OI)(CI)(IO)(special access:)
GENERIC_READ
GENERIC_EXECUTE
BUILTIN\Power Users:C
BUILTIN\Power Users:(OI)(CI)(IO)C
BUILTIN\Administrators:F
BUILTIN\Administrators:(OI)(CI)(IO)F
NT AUTHORITY\SYSTEM:F
NT AUTHORITY\SYSTEM:(OI)(CI)(IO)F
BUILTIN\Administrators:F
CREATOR OWNER:(OI)(CI)(IO)F
C:\Documents and Settings\grant>
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Comment By: Matthew Shomphe (mshomphe)
Date: 2003-06-17 04:05
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Here's my first pass at some additional documentation. My
HTML skills are not up to par, but I've tried :) I've attached
the document separately.
m@
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Comment By: Neal Norwitz (nnorwitz)
Date: 2003-06-17 03:06
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Could you try to produce a patch to improve the
documentation? Or perhaps suggest better wording?
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