aaudio: initialize the callback buffer

This can prevent some loud noises during unit tests.

Also use std::unique_ptr

Bug: 154342174
Test: libaaudio/tests/test_various.cpp
Change-Id: I1c1dc0f4a6a29cf7d7a656392a81a325847de22d

media/libaaudio/src/client/AudioStreamInternal.cpp

@@ -230,7 +230,7 @@ aaudio_result_t AudioStreamInternal::open(const AudioStreamBuilder &builder) {
         }
 
         const int32_t callbackBufferSize = mCallbackFrames * getBytesPerFrame();
-        mCallbackBuffer = new uint8_t[callbackBufferSize];
+        mCallbackBuffer = std::make_unique<uint8_t[]>(callbackBufferSize);
     }
 
     // For debugging and analyzing the distribution of MMAP timestamps.
@@ -279,8 +279,7 @@ aaudio_result_t AudioStreamInternal::release_l() {
         mServiceStreamHandle = AAUDIO_HANDLE_INVALID;
 
         mServiceInterface.closeStream(serviceStreamHandle);
-        delete[] mCallbackBuffer;
-        mCallbackBuffer = nullptr;
+        mCallbackBuffer.reset();
         result = mEndPointParcelable.close();
         aaudio_result_t result2 = AudioStream::release_l();
         return (result != AAUDIO_OK) ? result : result2;

media/libaaudio/src/client/AudioStreamInternal.h

@@ -164,7 +164,7 @@ protected:
     // Offset from underlying frame position.
     int64_t                  mFramesOffsetFromService = 0; // offset for timestamps
 
-    uint8_t                 *mCallbackBuffer = nullptr;
+    std::unique_ptr<uint8_t[]> mCallbackBuffer;
     int32_t                  mCallbackFrames = 0;
 
     // The service uses this for SHARED mode.

media/libaaudio/src/client/AudioStreamInternalCapture.cpp

@@ -243,7 +243,7 @@ void *AudioStreamInternalCapture::callbackLoop() {
         int64_t timeoutNanos = calculateReasonableTimeout(mCallbackFrames);
 
         // This is a BLOCKING READ!
-        result = read(mCallbackBuffer, mCallbackFrames, timeoutNanos);
+        result = read(mCallbackBuffer.get(), mCallbackFrames, timeoutNanos);
         if ((result != mCallbackFrames)) {
             ALOGE("callbackLoop: read() returned %d", result);
             if (result >= 0) {
@@ -255,7 +255,7 @@ void *AudioStreamInternalCapture::callbackLoop() {
         }
 
         // Call application using the AAudio callback interface.
-        callbackResult = maybeCallDataCallback(mCallbackBuffer, mCallbackFrames);
+        callbackResult = maybeCallDataCallback(mCallbackBuffer.get(), mCallbackFrames);
 
         if (callbackResult == AAUDIO_CALLBACK_RESULT_STOP) {
             ALOGD("%s(): callback returned AAUDIO_CALLBACK_RESULT_STOP", __func__);

media/libaaudio/src/client/AudioStreamInternalPlay.cpp

@@ -268,11 +268,11 @@ void *AudioStreamInternalPlay::callbackLoop() {
     // result might be a frame count
     while (mCallbackEnabled.load() && isActive() && (result >= 0)) {
         // Call application using the AAudio callback interface.
-        callbackResult = maybeCallDataCallback(mCallbackBuffer, mCallbackFrames);
+        callbackResult = maybeCallDataCallback(mCallbackBuffer.get(), mCallbackFrames);
 
         if (callbackResult == AAUDIO_CALLBACK_RESULT_CONTINUE) {
             // Write audio data to stream. This is a BLOCKING WRITE!
-            result = write(mCallbackBuffer, mCallbackFrames, timeoutNanos);
+            result = write(mCallbackBuffer.get(), mCallbackFrames, timeoutNanos);
             if ((result != mCallbackFrames)) {
                 if (result >= 0) {
                     // Only wrote some of the frames requested. Must have timed out.