Fix bug 61713 check also that mbstring's found any internal_encoding

Author: weltling

ext/standard/html.c

@@ -785,18 +785,20 @@ static enum entity_charset determine_charset(char *charset_hint TSRMLS_DC)
 			charset_hint = Z_STRVAL_P(uf_result);
 			len = Z_STRLEN_P(uf_result);
 
-			if (len == 4) { /* sizeof(none|auto|pass)-1 */
-				if (!memcmp("pass", charset_hint, sizeof("pass") - 1) || 
-				    !memcmp("auto", charset_hint, sizeof("auto") - 1) || 
-				    !memcmp("none", charset_hint, sizeof("none") - 1)) {
-					
-					charset_hint = NULL;
-					len = 0;
+			if (charset_hint != NULL && len != 0) {
+				if (len == 4) { /* sizeof(none|auto|pass)-1 */
+					if (!memcmp("pass", charset_hint, sizeof("pass") - 1) ||
+						!memcmp("auto", charset_hint, sizeof("auto") - 1) ||
+						!memcmp("none", charset_hint, sizeof("none") - 1)) {
+
+						charset_hint = NULL;
+						len = 0;
+					}
+				} else {
+					/* Jump to det_charset only if mbstring isn't one of above eq pass, auto, none.
+					   Otherwise try default_charset next */
+					goto det_charset;
 				}
-			} else {
-				/* Jump to det_charset only if mbstring isn't one of above eq pass, auto, none.
-				   Otherwise try default_charset next */
-				goto det_charset;
 			}
 		}
 	}