1 files changed, 27 insertions, 10 deletions

diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index d63a985..a3a79f8 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -2353,7 +2353,7 @@ StringRplcCmd(
     Tcl_Obj *const objv[])	/* Argument objects. */
 {
     Tcl_UniChar *ustring;
-    int first, last, length;
+    int first, last, length, end;
 
     if (objc < 4 || objc > 5) {
 	Tcl_WrongNumArgs(interp, 1, objv, "string first last ?string?");
@@ -2361,20 +2361,38 @@ StringRplcCmd(
     }
 
     ustring = Tcl_GetUnicodeFromObj(objv[1], &length);
-    length--;
+    end = length - 1;
 
-    if (TclGetIntForIndexM(interp, objv[2], length, &first) != TCL_OK ||
-	    TclGetIntForIndexM(interp, objv[3], length, &last) != TCL_OK){
+    if (TclGetIntForIndexM(interp, objv[2], end, &first) != TCL_OK ||
+	    TclGetIntForIndexM(interp, objv[3], end, &last) != TCL_OK){
 	return TCL_ERROR;
     }
 
-    if ((last < first) || (last < 0) || (first > length)) {
+    /*
+     * The following test screens out most empty substrings as
+     * candidates for replacement. When they are detected, no
+     * replacement is done, and the result is the original string,
+     */
+    if ((last < 0) ||		/* Range ends before start of string */
+	    (first > end) ||	/* Range begins after end of string */
+	    (last < first)) {	/* Range begins after it starts */
+
+	/*
+	 * BUT!!! when (end < 0) -- an empty original string -- we can
+	 * have (first <= end < 0 <= last) and an empty string is permitted
+	 * to be replaced.
+	 */
 	Tcl_SetObjResult(interp, objv[1]);
     } else {
 	Tcl_Obj *resultPtr;
 
+	/*
+	 * We are re-fetching in case the string argument is same value as 
+	 * an index argument, and shimmering cost us our ustring.
+	 */
+
 	ustring = Tcl_GetUnicodeFromObj(objv[1], &length);
-	length--;
+	end = length-1;
 
 	if (first < 0) {
 	    first = 0;
@@ -2384,9 +2402,9 @@ StringRplcCmd(
 	if (objc == 5) {
 	    Tcl_AppendObjToObj(resultPtr, objv[4]);
 	}
-	if (last < length) {
+	if (last < end) {
 	    Tcl_AppendUnicodeToObj(resultPtr, ustring + last + 1,
-		    length - last);
+		    end - last);
 	}
 	Tcl_SetObjResult(interp, resultPtr);
     }
@@ -3267,8 +3285,7 @@ StringTrimCmd(
     }
     string1 = TclGetStringFromObj(objv[1], &length1);
 
-    triml = TclTrimLeft(string1, length1, string2, length2);
-    trimr = TclTrimRight(string1 + triml, length1 - triml, string2, length2);
+    triml = TclTrim(string1, length1, string2, length2, &trimr);
 
     Tcl_SetObjResult(interp,
 	    Tcl_NewStringObj(string1 + triml, length1 - triml - trimr));