-#define MgTAINTEDDIR(mg) (mg->mg_flags & MGf_TAINTEDDIR)
-#define MgTAINTEDDIR_on(mg) (mg->mg_flags |= MGf_TAINTEDDIR)
+#define MgTAINTEDDIR(mg) (mg->mg_flags & MGf_TAINTEDDIR)
+#define MgTAINTEDDIR_on(mg) (mg->mg_flags |= MGf_TAINTEDDIR)
+#define MgTAINTEDDIR_off(mg) (mg->mg_flags &= ~MGf_TAINTEDDIR)
+
+#define MgPV(mg,lp) (((lp = (mg)->mg_len) == HEf_SVKEY) ? \
+ SvPV((SV*)((mg)->mg_ptr),lp) : \
+ (mg)->mg_ptr)
+
+#define SvTIED_mg(sv,how) \
+ (SvRMAGICAL(sv) ? mg_find((sv),(how)) : Null(MAGIC*))
+#define SvTIED_obj(sv,mg) \
+ ((mg)->mg_obj ? (mg)->mg_obj : sv_2mortal(newRV(sv)))