From 0be299fbd09713f4622ab5df476ea512693a7a87 Mon Sep 17 00:00:00 2001
From: Koji Arai <jca02266@gmail.com>
Date: Tue, 20 Nov 2012 00:05:59 +0900
Subject: [PATCH] =?UTF-8?q?Avoid=20StringIndexOutOfBoundsException=20when?=
 =?UTF-8?q?=20the=20header=20is=20broken=20like=20"=3D=3Fus-ascii=3Fq=3Fab?=
 =?UTF-8?q?c=3F=3D=20=3D=3F"?=

---
 .../fsck/k9/mail/internet/DecoderUtil.java    | 26 +++++++++++--------
 .../k9/mail/internet/DecoderUtilTest.java     |  6 ++---
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/com/fsck/k9/mail/internet/DecoderUtil.java b/src/com/fsck/k9/mail/internet/DecoderUtil.java
index 137ba5e7e..28abeed84 100644
--- a/src/com/fsck/k9/mail/internet/DecoderUtil.java
+++ b/src/com/fsck/k9/mail/internet/DecoderUtil.java
@@ -110,24 +110,28 @@ public class DecoderUtil {
 
         while (true) {
             int begin = body.indexOf("=?", previousEnd);
+            if (begin == -1) {
+                sb.append(body.substring(previousEnd));
+                return sb.toString();
+            }
 
             // ANDROID:  The mime4j original version has an error here.  It gets confused if
             // the encoded string begins with an '=' (just after "?Q?").  This patch seeks forward
             // to find the two '?' in the "header", before looking for the final "?=".
-            int endScan = begin + 2;
-            if (begin != -1) {
-                int qm1 = body.indexOf('?', endScan + 2);
-                int qm2 = body.indexOf('?', qm1 + 1);
-                if (qm2 != -1) {
-                    endScan = qm2 + 1;
-                }
+            int qm1 = body.indexOf('?', begin + 2);
+            if (qm1 == -1) {
+                sb.append(body.substring(previousEnd));
+                return sb.toString();
             }
 
-            int end = begin == -1 ? -1 : body.indexOf("?=", endScan);
-            if (end == -1) {
-                if (previousEnd == 0)
-                    return body;
+            int qm2 = body.indexOf('?', qm1 + 1);
+            if (qm2 == -1) {
+                sb.append(body.substring(previousEnd));
+                return sb.toString();
+            }
 
+            int end = body.indexOf("?=", qm2 + 1);
+            if (end == -1) {
                 sb.append(body.substring(previousEnd));
                 return sb.toString();
             }
diff --git a/tests/src/com/fsck/k9/mail/internet/DecoderUtilTest.java b/tests/src/com/fsck/k9/mail/internet/DecoderUtilTest.java
index e9c7d62c6..b1d25c873 100644
--- a/tests/src/com/fsck/k9/mail/internet/DecoderUtilTest.java
+++ b/tests/src/com/fsck/k9/mail/internet/DecoderUtilTest.java
@@ -57,8 +57,7 @@ public class DecoderUtilTest extends TestCase {
         assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
 
         body = "=??q?a?=";
-        expect = "=??q?a?=";
-        //expect = "a";
+        expect = "a";
         message = null;
         assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
 
@@ -88,8 +87,7 @@ public class DecoderUtilTest extends TestCase {
         assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
 
         body = "=?x?q?X?=";
-        expect = "=?x?q?X?=";
-        //expect = "X";
+        expect = "X";
         message = null;
         assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));