/*
 * tclTrace.c --
 *
 *	This file contains code to handle most trace management.
 *
 * Copyright (c) 1987-1993 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 1998-2000 Scriptics Corporation.
 * Copyright (c) 2002 ActiveState Corporation.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclTrace.c,v 1.26 2005/07/23 00:04:31 dkf Exp $
 * RCS: @(#) $Id: tclTrace.c,v 1.27 2005/10/29 19:16:32 msofer Exp $
 */

#include "tclInt.h"

/*
 * Structure used to hold information about variable traces:
 */

    CONST char *name2;		/* Name of element within array; NULL means
				 * scalar variable is being referenced. */
    int flags;			/* OR-ed bits giving operation and other
				 * information. */
{
    TraceVarInfo *tvarPtr = (TraceVarInfo *) clientData;
    char *result;
    int code;
    int code, destroy = 0;
    Tcl_DString cmd;

    /*
     * We might call Tcl_Eval() below, and that might evaluate [trace vdelete]
     * which might try to free tvarPtr. We want to use tvarPtr until the end
     * of this function, so we use Tcl_Preserve() and Tcl_Release() to be sure
     * it is not freed while we still need it.

	     * returns.
	     *
	     * Add the TCL_TRACE_DESTROYED flag to tvarPtr to indicate to
	     * other areas that this will be destroyed by us, otherwise a
	     * double-free might occur depending on what the eval does.
	     */

	    if (flags & TCL_TRACE_DESTROYED) {
	    if ((flags & TCL_TRACE_DESTROYED)
		    && !(tvarPtr->flags & TCL_TRACE_DESTROYED)) {
		destroy = 1;
		tvarPtr->flags |= TCL_TRACE_DESTROYED;
	    }
	    code = Tcl_EvalEx(interp, Tcl_DStringValue(&cmd),
		    Tcl_DStringLength(&cmd), 0);
	    if (code != TCL_OK) {		/* copy error msg to result */
		Tcl_Obj *errMsgObj = Tcl_GetObjResult(interp);
		Tcl_IncrRefCount(errMsgObj);
		result = (char *) errMsgObj;
	    }
	    Tcl_DStringFree(&cmd);
	}
    }
    if (flags & TCL_TRACE_DESTROYED) {
    if (destroy) {
	if (result != NULL) {
	    register Tcl_Obj *errMsgObj = (Tcl_Obj *) result;

	    Tcl_DecrRefCount(errMsgObj);
	    result = NULL;
	}
	Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);