[libxslt] Switch to xmlUTF8Strsize in EXSLT string functions

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 8a1d5b6a5aefce69a9dc4f7ec7425a76b323bc48
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu May 18 17:35:03 2017 +0200

    Switch to xmlUTF8Strsize in EXSLT string functions
    
    When encountering invalid UTF-8, xmlUTF8Size can return a size greater
    than the actual string length or -1. Switch to xmlUTF8Strsize which
    returns a sensible size even with invalid UTF-8.
    
    Under normal conditions, libxslt should never receive invalid UTF-8.
    But this change helps when fuzzing and hardens security.

 libexslt/strings.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/libexslt/strings.c b/libexslt/strings.c
index 8c8ed1d..0fdbe3b 100644
--- a/libexslt/strings.c
+++ b/libexslt/strings.c
@@ -75,7 +75,7 @@ exsltStrTokenizeFunction(xmlXPathParserContextPtr ctxt, int nargs)
         ret = xmlXPathNewNodeSet(NULL);
         if (ret != NULL) {
             for (cur = str, token = str; *cur != 0; cur += clen) {
-               clen = xmlUTF8Size(cur);
+               clen = xmlUTF8Strsize(cur, 1);
                if (*delimiters == 0) { /* empty string case */
                    xmlChar ctmp;
                    ctmp = *(cur+clen);
@@ -87,7 +87,7 @@ exsltStrTokenizeFunction(xmlXPathParserContextPtr ctxt, int nargs)
                     *(cur+clen) = ctmp; /* restore the changed byte */
                     token = cur + clen;
                 } else for (delimiter = delimiters; *delimiter != 0;
-                               delimiter += xmlUTF8Size(delimiter)) {
+                               delimiter += xmlUTF8Strsize(delimiter, 1)) {
                     if (!xmlUTF8Charcmp(cur, delimiter)) {
                         if (cur == token) {
                             /* discard empty tokens */
@@ -729,7 +729,7 @@ exsltStrReplaceFunction (xmlXPathParserContextPtr ctxt, int nargs) {
                 start = src;
             }
 
-            src += xmlUTF8Size(src);
+            src += xmlUTF8Strsize(src, 1);
         }
         else {
             if ((start < src &&