[Pkg-tcltk-devel] Bug#502304: Tcl_Main should quit (exiting nonzero) if appInitProc fails

[Ian Jackskon]

Package: tcl8.4
Version: 8.4.12-1.1
Tags: patch

This report is regarding the error behaviour of:
       Tcl_Main(int argc, char *argv[], Tcl_AppInitProc *appInitProc)
with respect to appInitProc which has this type:
       int Tcl_AppInit(Tcl_Interp *interp)

The documentation says that appInitProc may return TCL_OK or _ERROR.
The implication of TCL_ERROR is that the initialisation failed.  Under
these conditions continuing to execute the program or shell is not
appropriate.

As a demonstration:
  mariner:~> DISPLAY=: wish
  Application initialization failed: couldn't connect to display ":"
  % mariner:~> 
  mariner:~> cat >t.tcl
  vwait variable
  mariner:~> DISPLAY=: wish -f t.tcl 
  Application initialization failed: couldn't connect to display ":"
  [hangs]
Similar behaviour will appear with any program which uses Tcl_Main and
has an appInitProc which can fail.  (Obviously the test cases above
are simple tests, but a more complicated program involving vwait is
quite conceivable.)

The code in Tcl_Main seems to suggest that if the appInitProc were to
call Tcl_DeleteInterp, the execution would be safely abandoned.  But
this is a quite unreasonable thing to expect the appInitProc hook to
do and is not documented.  In any case if the appInitProc merely wants
to issue a warning and carry on it can do so itself.  The exit code
should be reserved for ordinary (fatal) errors.

I think this patch will fix it but I haven't compiled or tested it.

--- generic/tclMain.c~	2005-10-23 23:01:30.000000000 +0100
+++ generic/tclMain.c	2008-10-15 13:18:39.000000000 +0100
@@ -281,6 +281,8 @@
 	    Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
 	    Tcl_WriteChars(errChannel, "\n", 1);
 	}
+	exitCode = 1;
+	goto done;
     }
     if (Tcl_InterpDeleted(interp)) {
 	goto done;

--