Fix exception when GIF can't be decoded

We get a GifHeader object, but it has 0 frames
which eventually causes a divide by zero
exception. Since the real problem is that we
couldn't decode the gif, we check in the decoder
if the decode failed and then simply return null.

3 files changed, 22 insertions, 4 deletions

diff --git a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
index 4d653cb5..ac90fc70 100644
--- a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
+++ b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifDecoder.java
@@ -109,6 +109,7 @@ public class GifDecoder {
     private GifHeader header;
     private String id;
     private BitmapProvider bitmapProvider;
+    private GifHeaderParser parser = new GifHeaderParser();
 
     public interface BitmapProvider {
         public Bitmap obtain(int width, int height, Bitmap.Config config);
@@ -308,7 +309,7 @@ public class GifDecoder {
      */
     public int read(byte[] data) {
         this.data = data;
-        this.header = new GifHeaderParser(data).parseHeader();
+        this.header = parser.setData(data).parseHeader();
         if (data != null) {
             // Initialize the raw data buffer.
             rawData = ByteBuffer.wrap(data);
diff --git a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeader.java b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeader.java
index a5e556a5..c4b03491 100644
--- a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeader.java
+++ b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeader.java
@@ -42,4 +42,8 @@ public class GifHeader {
     public int getWidth() {
         return width;
     }
+
+    public int getNumFrames() {
+        return frameCount;
+    }
 }
diff --git a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
index af1844d9..5bf122ba 100644
--- a/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
+++ b/third_party/gif_decoder/src/main/java/com/bumptech/glide/gifdecoder/GifHeaderParser.java
@@ -5,6 +5,7 @@ import android.util.Log;
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.util.Arrays;
 
 import static com.bumptech.glide.gifdecoder.GifDecoder.STATUS_FORMAT_ERROR;
 
@@ -15,8 +16,8 @@ public class GifHeaderParser {
      */
     private static final int MAX_STACK_SIZE = 4096;
 
-    private final ByteBuffer rawData;
-    private GifHeader header = new GifHeader();
+    private ByteBuffer rawData;
+    private GifHeader header;
 
     // Raw data read working array.
     private byte[] block = new byte[256];
@@ -26,7 +27,8 @@ public class GifHeaderParser {
     private byte[] suffix;
     private byte[] pixelStack;
 
-    public GifHeaderParser(byte[] data) {
+    public GifHeaderParser setData(byte[] data) {
+        reset();
         if (data != null) {
             rawData = ByteBuffer.wrap(data);
             rawData.rewind();
@@ -35,6 +37,17 @@ public class GifHeaderParser {
             rawData = null;
             header.status = GifDecoder.STATUS_OPEN_ERROR;
         }
+        return this;
+    }
+
+    private void reset() {
+        rawData = null;
+        Arrays.fill(block, (byte) 0);
+        header = new GifHeader();
+        blockSize = 0;
+        prefix = null;
+        suffix = null;
+        pixelStack = null;
     }
 
     public GifHeader parseHeader() {