[tcljava-user] ExitCmd

[Justin R. <ju...@ha...>]

I run Tcl scripts inside of a larger long-running Java system (along
the lines of JSR-223, but using tcl.lang classes directly), and I've
found some behavior which I found a little odd in Jacl. The tcl exit
command calls System.exit(), which makes sense when running a single
script. But it proves to be prohibitive when I'm containing the
Interpreter inside a larger system. I'm looking for an exit command to
kindly exit the evalFile/eval method or throw an exception indicating
that the Interp in now invalid.  This might already be taken of when
putting the Interpreter into safe mode, is this true and is there
documentation concerning the state of the Safe Interpreter in
tcljava/jacl?

My workaround, in case anyone is interested is to overwrite the exit
command. I prep the Interpreter before running any untrusted code:

interp.eval("rename exit ::tcl::exit");
interp.createCommand("exit", new SafeExitCommand() );

My new exit command looks like this:

        public class SafeExitCommand implements Command {
                public void cmdProc(Interp interp, TclObject argv[])
throws TclException {
                        int code = 0;

                        if (argv.length > 2)
                                throw new TclNumArgsException(interp,
1, argv, "?returnCode?");

                        if (argv.length == 2) {
                                code = TclInteger.get(interp, argv[1]);
                        }

                        throw new TclException(interp, "ExitCommand "
+ Integer.toString(code) );
                }
        }

I then look for a TclException with a message (e.getMessage()) with
the word ExitCommand. It's definitely hacky, but it works for me. An
alternative would be to set the ccode of TclException to something
like TCL.EXIT, and then look for that code like TCL.RETURN is looked
for. Is that a valid idea to persue and contribute?

justin