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

4 files changed, 240 insertions, 1 deletions

diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 9675a5321e..d363ee9ea4 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -99,6 +99,7 @@ cc_library {
         "MemoryDealer.cpp",
         "MemoryHeapBase.cpp",
         "Parcel.cpp",
+        "ParcelableHolder.cpp",
         "ParcelFileDescriptor.cpp",
         "PersistableBundle.cpp",
         "ProcessState.cpp",
diff --git a/libs/binder/ParcelableHolder.cpp b/libs/binder/ParcelableHolder.cpp
new file mode 100644
index 0000000000..e9df27976c
--- /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
diff --git a/libs/binder/include/binder/Parcelable.h b/libs/binder/include/binder/Parcelable.h
index 83c2f1991d..a6e610ca19 100644
--- a/libs/binder/include/binder/Parcelable.h
+++ b/libs/binder/include/binder/Parcelable.h
@@ -56,7 +56,7 @@ public:
     // WARNING: for use by auto-generated code only (AIDL). Should not be used
     // manually, or there is a risk of breaking CTS, GTS, VTS, or CTS-on-GSI
     // tests.
-    enum class Stability {
+    enum class Stability : int32_t {
         STABILITY_LOCAL,
         STABILITY_VINTF, // corresponds to @VintfStability
     };
diff --git a/libs/binder/include/binder/ParcelableHolder.h b/libs/binder/include/binder/ParcelableHolder.h
new file mode 100644
index 0000000000..b6814aa5fe
--- /dev/null
+++ b/libs/binder/include/binder/ParcelableHolder.h
@@ -0,0 +1,141 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <binder/Parcel.h>
+#include <binder/Parcelable.h>
+#include <mutex>
+#include <optional>
+#include <tuple>
+
+namespace android {
+namespace os {
+/*
+ * C++ implementation of the Java class android.os.ParcelableHolder
+ */
+class ParcelableHolder : public android::Parcelable {
+public:
+    ParcelableHolder() = delete;
+    explicit ParcelableHolder(Stability stability) : mStability(stability){};
+    virtual ~ParcelableHolder() = default;
+    ParcelableHolder(const ParcelableHolder& other) {
+        mParcelable = other.mParcelable;
+        mParcelableName = other.mParcelableName;
+        if (other.mParcelPtr) {
+            mParcelPtr = std::make_unique<Parcel>();
+            mParcelPtr->appendFrom(other.mParcelPtr.get(), 0, other.mParcelPtr->dataSize());
+        }
+        mStability = other.mStability;
+    };
+
+    status_t writeToParcel(Parcel* parcel) const override;
+    status_t readFromParcel(const Parcel* parcel) override;
+
+    void reset() {
+        this->mParcelable = nullptr;
+        this->mParcelableName = std::nullopt;
+        this->mParcelPtr = nullptr;
+    }
+
+    template <typename T>
+    bool setParcelable(T&& p) {
+        using Tt = typename std::decay<T>::type;
+        return setParcelable<Tt>(std::make_shared<Tt>(std::forward<T>(p)));
+    }
+
+    template <typename T>
+    bool setParcelable(std::shared_ptr<T> p) {
+        std::lock_guard<std::mutex> l(mMutex);
+        static_assert(std::is_base_of<Parcelable, T>::value, "T must be derived from Parcelable");
+        if (p && this->getStability() > p->getStability()) {
+            return false;
+        }
+        this->mParcelable = p;
+        this->mParcelableName = T::getParcelableDescriptor();
+        this->mParcelPtr = nullptr;
+        return true;
+    }
+
+    template <typename T>
+    std::shared_ptr<T> getParcelable() const {
+        static_assert(std::is_base_of<Parcelable, T>::value, "T must be derived from Parcelable");
+        std::lock_guard<std::mutex> l(mMutex);
+        const std::string& parcelableDesc = T::getParcelableDescriptor();
+        if (!this->mParcelPtr) {
+            if (!this->mParcelable || !this->mParcelableName) {
+                ALOGD("empty ParcelableHolder");
+                return nullptr;
+            } else if (parcelableDesc != *mParcelableName) {
+                ALOGD("extension class name mismatch expected:%s actual:%s",
+                      mParcelableName->c_str(), parcelableDesc.c_str());
+                return nullptr;
+            }
+            return std::shared_ptr<T>(mParcelable, reinterpret_cast<T*>(mParcelable.get()));
+        }
+        this->mParcelPtr->setDataPosition(0);
+        status_t status = this->mParcelPtr->readUtf8FromUtf16(&this->mParcelableName);
+        if (status != android::OK || parcelableDesc != this->mParcelableName) {
+            this->mParcelableName = std::nullopt;
+            return nullptr;
+        }
+        this->mParcelable = std::make_shared<T>();
+        status = mParcelable.get()->readFromParcel(this->mParcelPtr.get());
+        if (status != android::OK) {
+            this->mParcelableName = std::nullopt;
+            this->mParcelable = nullptr;
+            return nullptr;
+        }
+        this->mParcelPtr = nullptr;
+        return std::shared_ptr<T>(mParcelable, reinterpret_cast<T*>(mParcelable.get()));
+    }
+
+    Stability getStability() const override { return mStability; };
+
+    inline bool operator!=(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) !=
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+    inline bool operator<(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) <
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+    inline bool operator<=(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) <=
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+    inline bool operator==(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) ==
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+    inline bool operator>(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) >
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+    inline bool operator>=(const ParcelableHolder& rhs) const {
+        return std::tie(mParcelable, mParcelPtr, mStability) >=
+                std::tie(rhs.mParcelable, rhs.mParcelPtr, rhs.mStability);
+    }
+
+private:
+    mutable std::shared_ptr<Parcelable> mParcelable;
+    mutable std::optional<std::string> mParcelableName;
+    mutable std::unique_ptr<Parcel> mParcelPtr;
+    Stability mStability;
+    mutable std::mutex mMutex;
+};
+} // namespace os
+} // namespace android