[Tcl-bugs] [ tcl-Bugs-3445787 ] Exposed file command broken in safe interps

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Bugs item #3445787, was opened at 2011-11-29 20:06
Message generated for change (Comment added) made by johannes-kuhn
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Category: 20. [interp]
Group: development: 8.6b2
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Ashok P. Nadkarni (apnadkarni)
Assigned to: Don Porter (dgp)
Summary: Exposed file command broken in safe interps

Initial Comment:
Tcl as of fossil head on 11/29/2011. Follow on to bug 3211758 which was fixed post 8.6b2

The fix in that bug made file a hidden command as was the case in older Tcl releases. However, the fix still does not allow all subcommands of file to be called even after exposing the file command.

% interp create -safe
interp0
% interp expose interp0 file
% interp0 eval {file dirname c:/tcl}
invalid command name "::tcl::file::dirname"

Aside from whether this is a good idea or not, it is a backward compatibility issue as was the case with 3211758 



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Comment By: Johannes Kuhn (johannes-kuhn)
Date: 2012-01-08 11:54

Message:
Ok, just saw that ::tcl::file::channels is never hidden, so scripts could
easily create the [file] command it if they need it, but because the safe
base defines an own [file] command, this is going to be a little bit more
complex.

Ohh, and by the way you broke my code... and it will take some of my time
to fix it..

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Comment By: Johannes Kuhn (johannes-kuhn)
Date: 2012-01-08 11:26

Message:
The file command is now a namespace ensemble (see [namespace ensemble
configure file]).
All subcommands of file are now hidden with a name like tcl:file:atime.
(Original name with all namespace seperators (::) replaced by a single
colon(:))

This change does in fact break old scripts that uses [interp invokehidden
$interp file].

The safe base uses the trused interp's file command, this is ok because the
exposed command does not have any special treatment depending on the
interp, unlike [file channels] witch displays all open channels that this
interp has access to.

This might probably only a small amout of scripts that actually 1) does not
use the safe base and 2) use safe interps with (partialy) exposed file
commands.

My advise is: make [interp hide] namespace aware, and when a hidden
namespace enseble is called (like [file]) it should _first_ check if the
target command (e.g. [::tcl::file::atime]) is there and call that command.
If there is no such hidden command  it should check if there is an exposed
command with that name.

I think this is the only possible solution to have still backward
compatibility and [file] a namespace ensemble

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Comment By: Don Porter (dgp)
Date: 2011-12-01 08:53

Message:

I believe this is related to the old, difficult
problem that [interp hide] and friends have
never really been updated to work well with
namespaces.

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