From 65ec1ae3b83f27031adbc962765efdd11bdddeb2 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Thu, 5 Jul 2012 07:45:35 +0000
Subject: protect Tcl_GetIndexFromObjStruct from empty strings in table

---
 generic/tclIndexObj.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/generic/tclIndexObj.c b/generic/tclIndexObj.c
index 79fc262..1076e32 100644
--- a/generic/tclIndexObj.c
+++ b/generic/tclIndexObj.c
@@ -207,6 +207,10 @@ Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags,
 	    entryPtr = NEXT_ENTRY(entryPtr, offset), i++) {
 	for (p1 = key, p2 = *entryPtr; *p1 == *p2; p1++, p2++) {
 	    if (*p1 == '\0') {
+		if (p1 == key) {
+		    /* empty keys never match */
+		    continue;
+		}
 		index = i;
 		goto done;
 	    }
@@ -260,24 +264,29 @@ Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags,
 	/*
 	 * Produce a fancy error message.
 	 */
-	int count;
+	int count = 0;
 
 	TclNewObj(resultPtr);
 	Tcl_SetObjResult(interp, resultPtr);
+	entryPtr = tablePtr;
+	while ((*entryPtr != NULL) && !**entryPtr) {
+	    entryPtr = NEXT_ENTRY(entryPtr, offset);
+	}
 	Tcl_AppendStringsToObj(resultPtr, (numAbbrev > 1) &&
 		!(flags & TCL_EXACT) ? "ambiguous " : "bad ", msg, " \"",
-		key, "\": must be ", STRING_AT(tablePtr,offset,0), (char*)NULL);
-	for (entryPtr = NEXT_ENTRY(tablePtr, offset), count = 0;
-		*entryPtr != NULL;
-		entryPtr = NEXT_ENTRY(entryPtr, offset), count++) {
+		key, "\": must be ", *entryPtr, (char*)NULL);
+	entryPtr = NEXT_ENTRY(entryPtr, offset);
+	while (*entryPtr != NULL) {
 	    if (*NEXT_ENTRY(entryPtr, offset) == NULL) {
 		Tcl_AppendStringsToObj(resultPtr,
 			(count > 0) ? ", or " : " or ", *entryPtr,
 			(char *) NULL);
-	    } else {
+	    } else if (**entryPtr) {
 		Tcl_AppendStringsToObj(resultPtr, ", ", *entryPtr,
 			(char *) NULL);
+		count++;
 	    }
+	    entryPtr = NEXT_ENTRY(entryPtr, offset);
 	}
     }
     return TCL_ERROR;
-- 
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