From 4d45ea496689de1a458df24ecfe8793f6c373f7a Mon Sep 17 00:00:00 2001
From: Harald Kuhr <harald.kuhr@gmail.com>
Date: Thu, 29 Apr 2021 16:55:24 +0200
Subject: [PATCH] #606: Workaround for broken JDK WBMPImageReader

(cherry picked from commit d0c4a075568304294b674de3f1d13a927e0084d0)
---
 .../stream/BufferedFileImageInputStream.java  | 34 ++++++++++++-------
 .../BufferedFileImageInputStreamTest.java     | 19 +++++++++++
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStream.java b/imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStream.java
index 50106903..91dc36f8 100644
--- a/imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStream.java
+++ b/imageio/imageio-core/src/main/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStream.java
@@ -125,27 +125,35 @@ public final class BufferedFileImageInputStream extends ImageInputStreamImpl {
     }
 
     @Override
-    public int read(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
+    public int read(final byte[] bytes, final int offset, final int length) throws IOException {
         checkClosed();
         bitOffset = 0;
 
         if (bufferEmpty()) {
             // Bypass buffer if buffer is empty for reads longer than buffer
-            if (pLength >= buffer.length) {
-                return readDirect(pBuffer, pOffset, pLength);
+            if (length >= buffer.length) {
+                return readDirect(bytes, offset, length);
             }
             else if (!fillBuffer()) {
                 return -1;
             }
         }
 
-        return readBuffered(pBuffer, pOffset, pLength);
+        int fromBuffer = readBuffered(bytes, offset, length);
+
+        if (length > fromBuffer) {
+            // Due to known bugs in certain JDK-bundled ImageIO plugins expecting read to behave as readFully,
+            // we'll read as much as possible from the buffer, and the rest directly after
+            return fromBuffer + max(0, readDirect(bytes, offset + fromBuffer, length - fromBuffer));
+        }
+
+        return fromBuffer;
     }
 
-    private int readDirect(final byte[] pBuffer, final int pOffset, final int pLength) throws IOException {
+    private int readDirect(final byte[] bytes, final int offset, final int length) throws IOException {
         // Invalidate the buffer, as its contents is no longer in sync with the stream's position.
         bufferLimit = 0;
-        int read = raf.read(pBuffer, pOffset, pLength);
+        int read = raf.read(bytes, offset, length);
 
         if (read > 0) {
             streamPos += read;
@@ -154,17 +162,17 @@ public final class BufferedFileImageInputStream extends ImageInputStreamImpl {
         return read;
     }
 
-    private int readBuffered(final byte[] pBuffer, final int pOffset, final int pLength) {
+    private int readBuffered(final byte[] bytes, final int offset, final int length) {
         // Read as much as possible from buffer
-        int length = Math.min(bufferLimit - bufferPos, pLength);
+        int available = Math.min(bufferLimit - bufferPos, length);
 
-        if (length > 0) {
-            System.arraycopy(buffer, bufferPos, pBuffer, pOffset, length);
-            bufferPos += length;
-            streamPos += length;
+        if (available > 0) {
+            System.arraycopy(buffer, bufferPos, bytes, offset, available);
+            bufferPos += available;
+            streamPos += available;
         }
 
-        return length;
+        return available;
     }
 
     public long length() {
diff --git a/imageio/imageio-core/src/test/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStreamTest.java b/imageio/imageio-core/src/test/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStreamTest.java
index 822db90e..e86c7320 100755
--- a/imageio/imageio-core/src/test/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStreamTest.java
+++ b/imageio/imageio-core/src/test/java/com/twelvemonkeys/imageio/stream/BufferedFileImageInputStreamTest.java
@@ -383,4 +383,23 @@ public class BufferedFileImageInputStreamTest {
         stream.close();
         verify(mock, only()).close();
     }
+
+    @Test
+    public void testWorkaroundForWBMPImageReaderExpectsReadToBehaveAsReadFully() throws IOException {
+        // See #606 for details.
+        // Bug in JDK WBMPImageReader, uses read(byte[], int, int) instead of readFully(byte[], int, int).
+        // Ie: Relies on read to return all bytes at once, without blocking
+        int size = BufferedFileImageInputStream.DEFAULT_BUFFER_SIZE * 7;
+        byte[] bytes = new byte[size];
+        File file = randomDataToFile(bytes);
+
+        try (BufferedFileImageInputStream stream = new BufferedFileImageInputStream(file)) {
+            byte[] result = new byte[size];
+            int head = stream.read(result, 0, 12);          // Provoke a buffered read
+            int len = stream.read(result, 12, size - 12);   // Rest of buffer + direct read
+
+            assertEquals(size, len + head);
+            assertArrayEquals(bytes, result);
+        }
+   }
 }