From 691daeb45d268c312bcaec409d5238435a7a7e4c Mon Sep 17 00:00:00 2001
From: Philip Rideout <philiprideout@gmail.com>
Date: Mon, 11 Feb 2019 13:03:58 -0800
Subject: [PATCH] JNI enhancement: allow mutation of non-direct buffers.

The bug was reproduced and the fix was verified by copying the following
code snippet into one of our Android samples:

    val norm = floatArrayOf(1.0f, 0.0f, 0.0f)
    val tang = floatArrayOf(0.0f, 1.0f, 0.0f, 1.0f)
    val expected = floatArrayOf(0.5f, 0.5f, 0.5f, 0.5f)
    val resultBuffer = FloatBuffer.allocate(4)
    val qtc = VertexBuffer.QuatTangentContext()
    qtc.quatCount = 1
    qtc.quatType = VertexBuffer.QuatType.FLOAT4
    qtc.outBuffer = resultBuffer
    qtc.normals = FloatBuffer.wrap(norm)
    qtc.tangents = FloatBuffer.wrap(tang)
    VertexBuffer.populateTangentQuaternions(qtc)
    Log.e("Filament", "${expected[0]} == ${resultBuffer[0]}")

Fixes #695.
---
 .../filament-android/src/main/cpp/NioUtils.cpp | 18 ++++++++++--------
 .../filament-android/src/main/cpp/NioUtils.h   |  5 ++++-
 .../src/main/cpp/VertexBuffer.cpp              |  2 +-
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/android/filament-android/src/main/cpp/NioUtils.cpp b/android/filament-android/src/main/cpp/NioUtils.cpp
index 37d77d3bee..2a69aaf812 100644
--- a/android/filament-android/src/main/cpp/NioUtils.cpp
+++ b/android/filament-android/src/main/cpp/NioUtils.cpp
@@ -26,7 +26,8 @@ struct {
     jmethodID getBufferType;
 } gNioUtils;
 
-AutoBuffer::AutoBuffer(JNIEnv *env, jobject buffer, jint size) noexcept : mEnv(env) {
+AutoBuffer::AutoBuffer(JNIEnv *env, jobject buffer, jint size, bool commit) noexcept : mEnv(env),
+        mDoCommit(commit) {
     mBuffer = env->NewGlobalRef(buffer);
 
     mType = (BufferType) env->CallStaticIntMethod(
@@ -108,27 +109,28 @@ AutoBuffer::AutoBuffer(AutoBuffer &&rhs) noexcept {
 AutoBuffer::~AutoBuffer() noexcept {
     JNIEnv *env = mEnv;
     if (mBaseArray) {
+        jint mode = mDoCommit ? 0 : JNI_ABORT;
         switch (mType) {
             case BufferType::BYTE:
-                env->ReleaseByteArrayElements((jbyteArray)mBaseArray, (jbyte *) mData, JNI_ABORT);
+                env->ReleaseByteArrayElements((jbyteArray)mBaseArray, (jbyte *) mData, mode);
                 break;
             case BufferType::CHAR:
-                env->ReleaseCharArrayElements((jcharArray)mBaseArray, (jchar *) mData, JNI_ABORT);
+                env->ReleaseCharArrayElements((jcharArray)mBaseArray, (jchar *) mData, mode);
                 break;
             case BufferType::SHORT:
-                env->ReleaseShortArrayElements((jshortArray)mBaseArray, (jshort *) mData, JNI_ABORT);
+                env->ReleaseShortArrayElements((jshortArray)mBaseArray, (jshort *) mData, mode);
                 break;
             case BufferType::INT:
-                env->ReleaseIntArrayElements((jintArray)mBaseArray, (jint *) mData, JNI_ABORT);
+                env->ReleaseIntArrayElements((jintArray)mBaseArray, (jint *) mData, mode);
                 break;
             case BufferType::LONG:
-                env->ReleaseLongArrayElements((jlongArray)mBaseArray, (jlong *) mData, JNI_ABORT);
+                env->ReleaseLongArrayElements((jlongArray)mBaseArray, (jlong *) mData, mode);
                 break;
             case BufferType::FLOAT:
-                env->ReleaseFloatArrayElements((jfloatArray)mBaseArray, (jfloat *) mData, JNI_ABORT);
+                env->ReleaseFloatArrayElements((jfloatArray)mBaseArray, (jfloat *) mData, mode);
                 break;
             case BufferType::DOUBLE:
-                env->ReleaseDoubleArrayElements((jdoubleArray)mBaseArray, (jdouble *) mData, JNI_ABORT);
+                env->ReleaseDoubleArrayElements((jdoubleArray)mBaseArray, (jdouble *) mData, mode);
                 break;
         }
         env->DeleteGlobalRef(mBaseArray);
diff --git a/android/filament-android/src/main/cpp/NioUtils.h b/android/filament-android/src/main/cpp/NioUtils.h
index b444ccb058..1ae7af4617 100644
--- a/android/filament-android/src/main/cpp/NioUtils.h
+++ b/android/filament-android/src/main/cpp/NioUtils.h
@@ -32,7 +32,9 @@ public:
         DOUBLE
     };
 
-    AutoBuffer(JNIEnv* env, jobject buffer, jint size) noexcept;
+    // Clients should pass "true" for the commit argument if they intend to mutate the buffer
+    // contents from native code.
+    AutoBuffer(JNIEnv* env, jobject buffer, jint size, bool commit = false) noexcept;
     AutoBuffer(AutoBuffer&& rhs) noexcept;
     ~AutoBuffer() noexcept;
 
@@ -62,4 +64,5 @@ private:
     void* mData = nullptr;
     jobject mBuffer = nullptr;
     jarray mBaseArray = nullptr;
+    bool mDoCommit = false;
 };
diff --git a/android/filament-android/src/main/cpp/VertexBuffer.cpp b/android/filament-android/src/main/cpp/VertexBuffer.cpp
index 5b99567540..93310e41f4 100644
--- a/android/filament-android/src/main/cpp/VertexBuffer.cpp
+++ b/android/filament-android/src/main/cpp/VertexBuffer.cpp
@@ -121,7 +121,7 @@ Java_com_google_android_filament_VertexBuffer_nPopulateTangentQuaternions(JNIEnv
         jint outStride, jobject normals, jint normalsRemaining, jint normalsStride,
         jobject tangents, jint tangentsRemaining, jint tangentsStride) {
 
-    AutoBuffer outNioBuffer(env, outBuffer, outRemaining);
+    AutoBuffer outNioBuffer(env, outBuffer, outRemaining, true);
     void* outData = outNioBuffer.getData();
 
     AutoBuffer normalsNioBuffer(env, normals, normalsRemaining);