Fixed a few crashes and added a FIXME for another which needs some refactoring.

git-svn-id: https://zxing.googlecode.com/svn/trunk@1814 59b500cc-1b3d-0410-9834-0bbf25fbcc57

android/src/com/google/zxing/client/android/DecodeHandler.java

@@ -38,6 +38,7 @@ final class DecodeHandler extends Handler {
 
   private final CaptureActivity activity;
   private final MultiFormatReader multiFormatReader;
+  private boolean running = true;
 
   DecodeHandler(CaptureActivity activity, Hashtable<DecodeHintType, Object> hints) {
     multiFormatReader = new MultiFormatReader();
@@ -47,11 +48,15 @@ final class DecodeHandler extends Handler {
 
   @Override
   public void handleMessage(Message message) {
+    if (!running) {
+      return;
+    }
     switch (message.what) {
       case R.id.decode:
         decode((byte[]) message.obj, message.arg1, message.arg2);
         break;
       case R.id.quit:
+        running = false;
         Looper.myLooper().quit();
         break;
     }

core/src/com/google/zxing/datamatrix/decoder/DecodedBitStreamParser.java

@@ -446,6 +446,12 @@ final class DecodedBitStreamParser {
     } else {
       count = 250 * (d1 - 249) + unrandomize255State(bits.readBits(8), codewordPosition++);
     }
+
+    // We're seeing NegativeArraySizeException errors from users.
+    if (count < 0) {
+      throw FormatException.getFormatInstance();
+    }
+
     byte[] bytes = new byte[count];
     for (int i = 0; i < count; i++) {
       // Have seen this particular error in the wild, such as at

core/src/com/google/zxing/qrcode/decoder/DecodedBitStreamParser.java

@@ -126,6 +126,11 @@ final class DecodedBitStreamParser {
   private static void decodeHanziSegment(BitSource bits,
                                          StringBuffer result,
                                          int count) throws FormatException {
+    // Don't crash trying to read more bits than we have available.
+    if (count * 13 > bits.available()) {
+      throw FormatException.getFormatInstance();
+    }
+
     // Each character will require 2 bytes. Read the characters as 2-byte pairs
     // and decode as GB2312 afterwards
     byte[] buffer = new byte[2 * count];
@@ -157,6 +162,11 @@ final class DecodedBitStreamParser {
   private static void decodeKanjiSegment(BitSource bits,
                                          StringBuffer result,
                                          int count) throws FormatException {
+    // Don't crash trying to read more bits than we have available.
+    if (count * 13 > bits.available()) {
+      throw FormatException.getFormatInstance();
+    }
+
     // Each character will require 2 bytes. Read the characters as 2-byte pairs
     // and decode as Shift_JIS afterwards
     byte[] buffer = new byte[2 * count];
@@ -191,10 +201,12 @@ final class DecodedBitStreamParser {
                                         CharacterSetECI currentCharacterSetECI,
                                         Vector byteSegments,
                                         Hashtable hints) throws FormatException {
-    byte[] readBytes = new byte[count];
+    // Don't crash trying to read more bits than we have available.
     if (count << 3 > bits.available()) {
       throw FormatException.getFormatInstance();
     }
+
+    byte[] readBytes = new byte[count];
     for (int i = 0; i < count; i++) {
       readBytes[i] = (byte) bits.readBits(8);
     }

core/src/com/google/zxing/qrcode/detector/Detector.java

@@ -308,14 +308,19 @@ public class Detector {
     int dx = Math.abs(toX - fromX);
     int dy = Math.abs(toY - fromY);
     int error = -dx >> 1;
-    int ystep = fromY < toY ? 1 : -1;
     int xstep = fromX < toX ? 1 : -1;
-    int state = 0; // In black pixels, looking for white, first or second time
+    int ystep = fromY < toY ? 1 : -1;
-    for (int x = fromX, y = fromY; x != toX; x += xstep) {
 
+    // In black pixels, looking for white, first or second time.
+    int state = 0;
+    for (int x = fromX, y = fromY; x != toX; x += xstep) {
       int realX = steep ? y : x;
       int realY = steep ? x : y;
-      if (state == 1) { // In white pixels, looking for black
+
+      // In white pixels, looking for black.
+      // FIXME(dswitkin): This method seems to assume square images, which can cause these calls to
+      // BitMatrix.get() to throw ArrayIndexOutOfBoundsException.
+      if (state == 1) {
         if (image.get(realX, realY)) {
           state++;
         }
@@ -325,7 +330,8 @@ public class Detector {
         }
       }
 
-      if (state == 3) { // Found black, white, black, and stumbled back onto white; done
+      // Found black, white, black, and stumbled back onto white, so we're done.
+      if (state == 3) {
         int diffX = x - fromX;
         int diffY = y - fromY;
         if (xstep < 0) {