Add ParcelableHolder

Add the implementation of ParcelableHolder which helps Parcelable to be
extendable.

It is equivalent to ParcelableHolder.java

Bug: 146611855
Test: atest aidl_integration_test aidl_unittests
Change-Id: I581fd2c2794744d30c51bd26f2289d96f960bc67
diff --git a/libs/binder/ParcelableHolder.cpp b/libs/binder/ParcelableHolder.cpp
new file mode 100644
index 0000000..e9df279
--- /dev/null
+++ b/libs/binder/ParcelableHolder.cpp
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <binder/Parcel.h>
+#include <binder/Parcelable.h>
+#include <binder/ParcelableHolder.h>
+
+#define RETURN_ON_FAILURE(expr)                     \
+    do {                                            \
+        android::status_t _status = (expr);         \
+        if (_status != android::OK) return _status; \
+    } while (false)
+
+namespace android {
+namespace os {
+status_t ParcelableHolder::writeToParcel(Parcel* p) const {
+    std::lock_guard<std::mutex> l(mMutex);
+    RETURN_ON_FAILURE(p->writeInt32(static_cast<int32_t>(this->getStability())));
+    if (this->mParcelPtr) {
+        RETURN_ON_FAILURE(p->writeInt32(this->mParcelPtr->dataSize()));
+        RETURN_ON_FAILURE(p->appendFrom(this->mParcelPtr.get(), 0, this->mParcelPtr->dataSize()));
+        return OK;
+    }
+    if (this->mParcelable) {
+        size_t sizePos = p->dataPosition();
+        RETURN_ON_FAILURE(p->writeInt32(0));
+        size_t dataStartPos = p->dataPosition();
+        RETURN_ON_FAILURE(p->writeUtf8AsUtf16(this->mParcelableName));
+        this->mParcelable->writeToParcel(p);
+        size_t dataSize = p->dataPosition() - dataStartPos;
+
+        p->setDataPosition(sizePos);
+        RETURN_ON_FAILURE(p->writeInt32(dataSize));
+        p->setDataPosition(p->dataPosition() + dataSize);
+        return OK;
+    }
+
+    RETURN_ON_FAILURE(p->writeInt32(0));
+    return OK;
+}
+
+status_t ParcelableHolder::readFromParcel(const Parcel* p) {
+    std::lock_guard<std::mutex> l(mMutex);
+    this->mStability = static_cast<Stability>(p->readInt32());
+    this->mParcelable = nullptr;
+    this->mParcelableName = std::nullopt;
+    int32_t rawDataSize;
+
+    status_t status = p->readInt32(&rawDataSize);
+    if (status != android::OK || rawDataSize < 0) {
+        this->mParcelPtr = nullptr;
+        return status != android::OK ? status : BAD_VALUE;
+    }
+    if (rawDataSize == 0) {
+        if (this->mParcelPtr) {
+            this->mParcelPtr = nullptr;
+        }
+        return OK;
+    }
+
+    size_t dataSize = rawDataSize;
+
+    size_t dataStartPos = p->dataPosition();
+
+    if (dataStartPos > SIZE_MAX - dataSize) {
+        this->mParcelPtr = nullptr;
+        return BAD_VALUE;
+    }
+
+    if (!this->mParcelPtr) {
+        this->mParcelPtr = std::make_unique<Parcel>();
+    }
+    this->mParcelPtr->freeData();
+
+    status = this->mParcelPtr->appendFrom(p, dataStartPos, dataSize);
+    if (status != android::OK) {
+        this->mParcelPtr = nullptr;
+        return status;
+    }
+    p->setDataPosition(dataStartPos + dataSize);
+    return OK;
+}
+} // namespace os
+} // namespace android