From 77ad336da790dc522216300bfb20d74b779a9d62 Mon Sep 17 00:00:00 2001
From: Don Jeba <donjeba@yahoo.com>
Date: Fri, 16 Nov 2018 01:01:23 +0530
Subject: [PATCH] LANG-1406 StringIndexOutOfBoundsException in
 StringUtils.replaceIgnoreCase

---
 .../java/org/apache/commons/lang3/StringUtils.java    | 11 ++++++++++-
 .../org/apache/commons/lang3/StringUtilsTest.java     |  9 +++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/apache/commons/lang3/StringUtils.java b/src/main/java/org/apache/commons/lang3/StringUtils.java
index 12dfcdca70d..8a47ce0c56c 100644
--- a/src/main/java/org/apache/commons/lang3/StringUtils.java
+++ b/src/main/java/org/apache/commons/lang3/StringUtils.java
@@ -5596,7 +5596,16 @@ private static String replace(final String text, String searchString, final Stri
          }
          String searchText = text;
          if (ignoreCase) {
-             searchText = text.toLowerCase();
+             StringBuilder buf = new StringBuilder(text.length());
+             for (int i = 0; i < text.length(); i++) {
+                 char c = text.charAt(i);
+                 if (Character.UnicodeBlock.of(c) != Character.UnicodeBlock.BASIC_LATIN) {
+                     buf.append(c);
+                 } else {
+                     buf.append(Character.toLowerCase(c));
+                 }
+             }
+             searchText = buf.toString();
              searchString = searchString.toLowerCase();
          }
          int start = 0;
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index afcd6b2f9f4..501e10ead38 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -1213,6 +1213,15 @@ public void testReplaceIgnoreCase_StringStringString() {
         assertEquals("farfarfar", StringUtils.replaceIgnoreCase("foofOOfoo", "OO", "ar"));
     }
 
+    @Test
+    public void testReplaceIgnoreCase_LANG_1406() {
+        assertEquals("\u0130", StringUtils.replaceIgnoreCase("\u0130x", "x", ""));
+        assertEquals("\u0130", StringUtils.replaceIgnoreCase("X\u0130x", "x", ""));
+        assertEquals("yz\u0130yz", StringUtils.replaceIgnoreCase("X\u0130x", "x", "yz"));
+        assertEquals("yzyz\u0130yz", StringUtils.replaceIgnoreCase("xX\u0130x", "x", "yz"));
+        assertEquals("\u0130\u0131", StringUtils.replaceIgnoreCase("\u0130x\u0131", "x", ""));
+    }
+
     @Test
     public void testReplacePattern_StringStringString() {
         assertNull(StringUtils.replacePattern(null, "", ""));