[Tcl-bugs] [ tcl-Bugs-749876 ] NTFS: [file writable $directory] lies

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Bugs item #749876, was opened at 2003-06-05 19:20
Message generated for change (Comment added) made by dgp
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Category: 35. Pathname Management
Group: = 8.4.2
Status: Open
Resolution: None
Priority: 5
Submitted By: Don Porter (dgp)
Assigned to: Vince Darley (vincentdarley)
Summary: NTFS: [file writable $directory] lies

Initial Comment:

[file writable $directory] returns 1, yet
[open [file join $directory newFile] w] fails.

More detail from original user report:

"On Windows, with the NTFS file system,
there appears to be two ways to
set file permissions.  You can use the old FAT
based system, where you can set a read-only
attribute bit.  It looks like this is what is
checked by the Tcl 'file writable' command.
Alternatively, there is a "security" tab in the file
properties dialog box, which allows you to
grant various access on a group-by-group basis.
I've been testing this against Tcl 8.4.2 (Active
Tcl release), and haven't found any way to
detect the latter restriction, other than trying the
access directly."

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>Comment By: Don Porter (dgp)
Date: 2003-06-23 14:24

Message:
Logged In: YES 
user_id=80530


"[file stat] was the first thing I tried.  On my Win2K
laptop, I create
two files, one with write access enabled, one without. 
Other than the
timestamps, the file stat arrays are identical."

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Comment By: Vince Darley (vincentdarley)
Date: 2003-06-23 03:51

Message:
Logged In: YES 
user_id=32170

This all filters through to 'NativeAccess' in tclWinFile.c, which 
in turn calls:

    attr = (*tclWinProcs->getFileAttributesProc)(nativePath);

so presumably that call isn't aware of the NTFS permissions. 
Tcl also has a tclWinProcs->getFileAttributesExProc available, 
which might return more information.  In fact 'file stat' uses it, 
so perhaps that could be used to test something of this, even 
from pure Tcl.



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