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/*
* Copyright 2016 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/IInterface.h>
#include <binder/Parcel.h>
#include <cutils/compiler.h>
// Set to 1 to enable CallStacks when logging errors
#define SI_DUMP_CALLSTACKS 0
#if SI_DUMP_CALLSTACKS
#include <utils/CallStack.h>
#endif
#include <utils/NativeHandle.h>
#include <functional>
#include <type_traits>
namespace android {
namespace SafeInterface {
// ParcelHandler is responsible for writing/reading various types to/from a Parcel in a generic way
class ParcelHandler {
public:
explicit ParcelHandler(const char* logTag) : mLogTag(logTag) {}
// Specializations for types with dedicated handling in Parcel
status_t read(const Parcel& parcel, bool* b) const {
return callParcel("readBool", [&]() { return parcel.readBool(b); });
}
status_t write(Parcel* parcel, bool b) const {
return callParcel("writeBool", [&]() { return parcel->writeBool(b); });
}
template <typename E>
typename std::enable_if<std::is_enum<E>::value, status_t>::type read(const Parcel& parcel,
E* e) const {
typename std::underlying_type<E>::type u{};
status_t result = read(parcel, &u);
*e = static_cast<E>(u);
return result;
}
template <typename E>
typename std::enable_if<std::is_enum<E>::value, status_t>::type write(Parcel* parcel,
E e) const {
return write(parcel, static_cast<typename std::underlying_type<E>::type>(e));
}
template <typename T>
typename std::enable_if<std::is_base_of<Flattenable<T>, T>::value, status_t>::type read(
const Parcel& parcel, T* t) const {
return callParcel("read(Flattenable)", [&]() { return parcel.read(*t); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Flattenable<T>, T>::value, status_t>::type write(
Parcel* parcel, const T& t) const {
return callParcel("write(Flattenable)", [&]() { return parcel->write(t); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Flattenable<T>, T>::value, status_t>::type read(
const Parcel& parcel, sp<T>* t) const {
*t = new T{};
return callParcel("read(sp<Flattenable>)", [&]() { return parcel.read(*(t->get())); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Flattenable<T>, T>::value, status_t>::type write(
Parcel* parcel, const sp<T>& t) const {
return callParcel("write(sp<Flattenable>)", [&]() { return parcel->write(*(t.get())); });
}
template <typename T>
typename std::enable_if<std::is_base_of<LightFlattenable<T>, T>::value, status_t>::type read(
const Parcel& parcel, T* t) const {
return callParcel("read(LightFlattenable)", [&]() { return parcel.read(*t); });
}
template <typename T>
typename std::enable_if<std::is_base_of<LightFlattenable<T>, T>::value, status_t>::type write(
Parcel* parcel, const T& t) const {
return callParcel("write(LightFlattenable)", [&]() { return parcel->write(t); });
}
template <typename NH>
typename std::enable_if<std::is_same<NH, sp<NativeHandle>>::value, status_t>::type read(
const Parcel& parcel, NH* nh) {
*nh = NativeHandle::create(parcel.readNativeHandle(), true);
return NO_ERROR;
}
template <typename NH>
typename std::enable_if<std::is_same<NH, sp<NativeHandle>>::value, status_t>::type write(
Parcel* parcel, const NH& nh) {
return callParcel("write(sp<NativeHandle>)",
[&]() { return parcel->writeNativeHandle(nh->handle()); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Parcelable, T>::value, status_t>::type read(
const Parcel& parcel, T* t) const {
return callParcel("readParcelable", [&]() { return parcel.readParcelable(t); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Parcelable, T>::value, status_t>::type write(
Parcel* parcel, const T& t) const {
return callParcel("writeParcelable", [&]() { return parcel->writeParcelable(t); });
}
status_t read(const Parcel& parcel, String8* str) const {
return callParcel("readString8", [&]() { return parcel.readString8(str); });
}
status_t write(Parcel* parcel, const String8& str) const {
return callParcel("writeString8", [&]() { return parcel->writeString8(str); });
}
template <typename T>
typename std::enable_if<std::is_same<IBinder, T>::value, status_t>::type read(
const Parcel& parcel, sp<T>* pointer) const {
return callParcel("readNullableStrongBinder",
[&]() { return parcel.readNullableStrongBinder(pointer); });
}
template <typename T>
typename std::enable_if<std::is_same<IBinder, T>::value, status_t>::type write(
Parcel* parcel, const sp<T>& pointer) const {
return callParcel("writeStrongBinder",
[&]() { return parcel->writeStrongBinder(pointer); });
}
template <typename T>
typename std::enable_if<std::is_base_of<IInterface, T>::value, status_t>::type read(
const Parcel& parcel, sp<T>* pointer) const {
return callParcel("readNullableStrongBinder[IInterface]",
[&]() { return parcel.readNullableStrongBinder(pointer); });
}
template <typename T>
typename std::enable_if<std::is_base_of<IInterface, T>::value, status_t>::type write(
Parcel* parcel, const sp<T>& interface) const {
return write(parcel, IInterface::asBinder(interface));
}
template <typename T>
typename std::enable_if<std::is_base_of<Parcelable, T>::value, status_t>::type read(
const Parcel& parcel, std::vector<T>* v) const {
return callParcel("readParcelableVector", [&]() { return parcel.readParcelableVector(v); });
}
template <typename T>
typename std::enable_if<std::is_base_of<Parcelable, T>::value, status_t>::type write(
Parcel* parcel, const std::vector<T>& v) const {
return callParcel("writeParcelableVector",
[&]() { return parcel->writeParcelableVector(v); });
}
// Templates to handle integral types. We use a struct template to require that the called
// function exactly matches the signedness and size of the argument (e.g., the argument isn't
// silently widened).
template <bool isSigned, size_t size, typename I>
struct HandleInt;
template <typename I>
struct HandleInt<true, 4, I> {
static status_t read(const ParcelHandler& handler, const Parcel& parcel, I* i) {
return handler.callParcel("readInt32", [&]() { return parcel.readInt32(i); });
}
static status_t write(const ParcelHandler& handler, Parcel* parcel, I i) {
return handler.callParcel("writeInt32", [&]() { return parcel->writeInt32(i); });
}
};
template <typename I>
struct HandleInt<false, 4, I> {
static status_t read(const ParcelHandler& handler, const Parcel& parcel, I* i) {
return handler.callParcel("readUint32", [&]() { return parcel.readUint32(i); });
}
static status_t write(const ParcelHandler& handler, Parcel* parcel, I i) {
return handler.callParcel("writeUint32", [&]() { return parcel->writeUint32(i); });
}
};
template <typename I>
struct HandleInt<true, 8, I> {
static status_t read(const ParcelHandler& handler, const Parcel& parcel, I* i) {
return handler.callParcel("readInt64", [&]() { return parcel.readInt64(i); });
}
static status_t write(const ParcelHandler& handler, Parcel* parcel, I i) {
return handler.callParcel("writeInt64", [&]() { return parcel->writeInt64(i); });
}
};
template <typename I>
struct HandleInt<false, 8, I> {
static status_t read(const ParcelHandler& handler, const Parcel& parcel, I* i) {
return handler.callParcel("readUint64", [&]() { return parcel.readUint64(i); });
}
static status_t write(const ParcelHandler& handler, Parcel* parcel, I i) {
return handler.callParcel("writeUint64", [&]() { return parcel->writeUint64(i); });
}
};
template <typename I>
typename std::enable_if<std::is_integral<I>::value, status_t>::type read(const Parcel& parcel,
I* i) const {
return HandleInt<std::is_signed<I>::value, sizeof(I), I>::read(*this, parcel, i);
}
template <typename I>
typename std::enable_if<std::is_integral<I>::value, status_t>::type write(Parcel* parcel,
I i) const {
return HandleInt<std::is_signed<I>::value, sizeof(I), I>::write(*this, parcel, i);
}
private:
const char* const mLogTag;
// Helper to encapsulate error handling while calling the various Parcel methods
template <typename Function>
status_t callParcel(const char* name, Function f) const {
status_t error = f();
if (CC_UNLIKELY(error != NO_ERROR)) {
ALOG(LOG_ERROR, mLogTag, "Failed to %s, (%d: %s)", name, error, strerror(-error));
#if SI_DUMP_CALLSTACKS
CallStack callStack(mLogTag);
#endif
}
return error;
}
};
// Utility struct template which allows us to retrieve the types of the parameters of a member
// function pointer
template <typename T>
struct ParamExtractor;
template <typename Class, typename Return, typename... Params>
struct ParamExtractor<Return (Class::*)(Params...)> {
using ParamTuple = std::tuple<Params...>;
};
template <typename Class, typename Return, typename... Params>
struct ParamExtractor<Return (Class::*)(Params...) const> {
using ParamTuple = std::tuple<Params...>;
};
} // namespace SafeInterface
template <typename Interface>
class SafeBpInterface : public BpInterface<Interface> {
protected:
SafeBpInterface(const sp<IBinder>& impl, const char* logTag)
: BpInterface<Interface>(impl), mLogTag(logTag) {}
~SafeBpInterface() override = default;
// callRemote is used to invoke a synchronous procedure call over Binder
template <typename Method, typename TagType, typename... Args>
status_t callRemote(TagType tag, Args&&... args) const {
static_assert(sizeof(TagType) <= sizeof(uint32_t), "Tag must fit inside uint32_t");
// Verify that the arguments are compatible with the parameters
using ParamTuple = typename SafeInterface::ParamExtractor<Method>::ParamTuple;
static_assert(ArgsMatchParams<std::tuple<Args...>, ParamTuple>::value,
"Invalid argument type");
// Write the input arguments to the data Parcel
Parcel data;
data.writeInterfaceToken(this->getInterfaceDescriptor());
status_t error = writeInputs(&data, std::forward<Args>(args)...);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by writeInputs
return error;
}
// Send the data Parcel to the remote and retrieve the reply parcel
Parcel reply;
error = this->remote()->transact(static_cast<uint32_t>(tag), data, &reply);
if (CC_UNLIKELY(error != NO_ERROR)) {
ALOG(LOG_ERROR, mLogTag, "Failed to transact (%d)", error);
#if SI_DUMP_CALLSTACKS
CallStack callStack(mLogTag);
#endif
return error;
}
// Read the outputs from the reply Parcel into the output arguments
error = readOutputs(reply, std::forward<Args>(args)...);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by readOutputs
return error;
}
// Retrieve the result code from the reply Parcel
status_t result = NO_ERROR;
error = reply.readInt32(&result);
if (CC_UNLIKELY(error != NO_ERROR)) {
ALOG(LOG_ERROR, mLogTag, "Failed to obtain result");
#if SI_DUMP_CALLSTACKS
CallStack callStack(mLogTag);
#endif
return error;
}
return result;
}
// callRemoteAsync is used to invoke an asynchronous procedure call over Binder
template <typename Method, typename TagType, typename... Args>
void callRemoteAsync(TagType tag, Args&&... args) const {
static_assert(sizeof(TagType) <= sizeof(uint32_t), "Tag must fit inside uint32_t");
// Verify that the arguments are compatible with the parameters
using ParamTuple = typename SafeInterface::ParamExtractor<Method>::ParamTuple;
static_assert(ArgsMatchParams<std::tuple<Args...>, ParamTuple>::value,
"Invalid argument type");
// Write the input arguments to the data Parcel
Parcel data;
data.writeInterfaceToken(this->getInterfaceDescriptor());
status_t error = writeInputs(&data, std::forward<Args>(args)...);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by writeInputs
return;
}
// There will be no data in the reply Parcel since the call is one-way
Parcel reply;
error = this->remote()->transact(static_cast<uint32_t>(tag), data, &reply,
IBinder::FLAG_ONEWAY);
if (CC_UNLIKELY(error != NO_ERROR)) {
ALOG(LOG_ERROR, mLogTag, "Failed to transact (%d)", error);
#if SI_DUMP_CALLSTACKS
CallStack callStack(mLogTag);
#endif
}
}
private:
const char* const mLogTag;
// This struct provides information on whether the decayed types of the elements at Index in the
// tuple types T and U (that is, the types after stripping cv-qualifiers, removing references,
// and a few other less common operations) are the same
template <size_t Index, typename T, typename U>
struct DecayedElementsMatch {
private:
using FirstT = typename std::tuple_element<Index, T>::type;
using DecayedT = typename std::decay<FirstT>::type;
using FirstU = typename std::tuple_element<Index, U>::type;
using DecayedU = typename std::decay<FirstU>::type;
public:
static constexpr bool value = std::is_same<DecayedT, DecayedU>::value;
};
// When comparing whether the argument types match the parameter types, we first decay them (see
// DecayedElementsMatch) to avoid falsely flagging, say, T&& against T even though they are
// equivalent enough for our purposes
template <typename T, typename U>
struct ArgsMatchParams {};
template <typename... Args, typename... Params>
struct ArgsMatchParams<std::tuple<Args...>, std::tuple<Params...>> {
static_assert(sizeof...(Args) <= sizeof...(Params), "Too many arguments");
static_assert(sizeof...(Args) >= sizeof...(Params), "Not enough arguments");
private:
template <size_t Index>
static constexpr typename std::enable_if<(Index < sizeof...(Args)), bool>::type
elementsMatch() {
if (!DecayedElementsMatch<Index, std::tuple<Args...>, std::tuple<Params...>>::value) {
return false;
}
return elementsMatch<Index + 1>();
}
template <size_t Index>
static constexpr typename std::enable_if<(Index >= sizeof...(Args)), bool>::type
elementsMatch() {
return true;
}
public:
static constexpr bool value = elementsMatch<0>();
};
// Since we assume that pointer arguments are outputs, we can use this template struct to
// determine whether or not a given argument is fundamentally a pointer type and thus an output
template <typename T>
struct IsPointerIfDecayed {
private:
using Decayed = typename std::decay<T>::type;
public:
static constexpr bool value = std::is_pointer<Decayed>::value;
};
template <typename T>
typename std::enable_if<!IsPointerIfDecayed<T>::value, status_t>::type writeIfInput(
Parcel* data, T&& t) const {
return SafeInterface::ParcelHandler{mLogTag}.write(data, std::forward<T>(t));
}
template <typename T>
typename std::enable_if<IsPointerIfDecayed<T>::value, status_t>::type writeIfInput(
Parcel* /*data*/, T&& /*t*/) const {
return NO_ERROR;
}
// This method iterates through all of the arguments, writing them to the data Parcel if they
// are an input (i.e., if they are not a pointer type)
template <typename T, typename... Remaining>
status_t writeInputs(Parcel* data, T&& t, Remaining&&... remaining) const {
status_t error = writeIfInput(data, std::forward<T>(t));
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by writeIfInput
return error;
}
return writeInputs(data, std::forward<Remaining>(remaining)...);
}
static status_t writeInputs(Parcel* /*data*/) { return NO_ERROR; }
template <typename T>
typename std::enable_if<IsPointerIfDecayed<T>::value, status_t>::type readIfOutput(
const Parcel& reply, T&& t) const {
return SafeInterface::ParcelHandler{mLogTag}.read(reply, std::forward<T>(t));
}
template <typename T>
static typename std::enable_if<!IsPointerIfDecayed<T>::value, status_t>::type readIfOutput(
const Parcel& /*reply*/, T&& /*t*/) {
return NO_ERROR;
}
// Similar to writeInputs except that it reads output arguments from the reply Parcel
template <typename T, typename... Remaining>
status_t readOutputs(const Parcel& reply, T&& t, Remaining&&... remaining) const {
status_t error = readIfOutput(reply, std::forward<T>(t));
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by readIfOutput
return error;
}
return readOutputs(reply, std::forward<Remaining>(remaining)...);
}
static status_t readOutputs(const Parcel& /*data*/) { return NO_ERROR; }
};
template <typename Interface>
class SafeBnInterface : public BnInterface<Interface> {
public:
explicit SafeBnInterface(const char* logTag) : mLogTag(logTag) {}
protected:
template <typename Method>
status_t callLocal(const Parcel& data, Parcel* reply, Method method) {
CHECK_INTERFACE(this, data, reply);
// Since we need to both pass inputs into the call as well as retrieve outputs, we create a
// "raw" tuple, where the inputs are interleaved with actual, non-pointer versions of the
// outputs. When we ultimately call into the method, we will pass the addresses of the
// output arguments instead of their tuple members directly, but the storage will live in
// the tuple.
using ParamTuple = typename SafeInterface::ParamExtractor<Method>::ParamTuple;
typename RawConverter<std::tuple<>, ParamTuple>::type rawArgs{};
// Read the inputs from the data Parcel into the argument tuple
status_t error = InputReader<ParamTuple>{mLogTag}.readInputs(data, &rawArgs);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by read
return error;
}
// Call the local method
status_t result = MethodCaller<ParamTuple>::call(this, method, &rawArgs);
// Extract the outputs from the argument tuple and write them into the reply Parcel
error = OutputWriter<ParamTuple>{mLogTag}.writeOutputs(reply, &rawArgs);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by write
return error;
}
// Return the result code in the reply Parcel
error = reply->writeInt32(result);
if (CC_UNLIKELY(error != NO_ERROR)) {
ALOG(LOG_ERROR, mLogTag, "Failed to write result");
#if SI_DUMP_CALLSTACKS
CallStack callStack(mLogTag);
#endif
return error;
}
return NO_ERROR;
}
template <typename Method>
status_t callLocalAsync(const Parcel& data, Parcel* /*reply*/, Method method) {
// reply is not actually used by CHECK_INTERFACE
CHECK_INTERFACE(this, data, reply);
// Since we need to both pass inputs into the call as well as retrieve outputs, we create a
// "raw" tuple, where the inputs are interleaved with actual, non-pointer versions of the
// outputs. When we ultimately call into the method, we will pass the addresses of the
// output arguments instead of their tuple members directly, but the storage will live in
// the tuple.
using ParamTuple = typename SafeInterface::ParamExtractor<Method>::ParamTuple;
typename RawConverter<std::tuple<>, ParamTuple>::type rawArgs{};
// Read the inputs from the data Parcel into the argument tuple
status_t error = InputReader<ParamTuple>{mLogTag}.readInputs(data, &rawArgs);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged by read
return error;
}
// Call the local method
MethodCaller<ParamTuple>::callVoid(this, method, &rawArgs);
// After calling, there is nothing more to do since asynchronous calls do not return a value
// to the caller
return NO_ERROR;
}
private:
const char* const mLogTag;
// RemoveFirst strips the first element from a tuple.
// For example, given T = std::tuple<A, B, C>, RemoveFirst<T>::type = std::tuple<B, C>
template <typename T, typename... Args>
struct RemoveFirst;
template <typename T, typename... Args>
struct RemoveFirst<std::tuple<T, Args...>> {
using type = std::tuple<Args...>;
};
// RawConverter strips a tuple down to its fundamental types, discarding both pointers and
// references. This allows us to allocate storage for both input (non-pointer) arguments and
// output (pointer) arguments in one tuple.
// For example, given T = std::tuple<const A&, B*>, RawConverter<T>::type = std::tuple<A, B>
template <typename Unconverted, typename... Converted>
struct RawConverter;
template <typename Unconverted, typename... Converted>
struct RawConverter<std::tuple<Converted...>, Unconverted> {
private:
using ElementType = typename std::tuple_element<0, Unconverted>::type;
using Decayed = typename std::decay<ElementType>::type;
using WithoutPointer = typename std::remove_pointer<Decayed>::type;
public:
using type = typename RawConverter<std::tuple<Converted..., WithoutPointer>,
typename RemoveFirst<Unconverted>::type>::type;
};
template <typename... Converted>
struct RawConverter<std::tuple<Converted...>, std::tuple<>> {
using type = std::tuple<Converted...>;
};
// This provides a simple way to determine whether the indexed element of Args... is a pointer
template <size_t I, typename... Args>
struct ElementIsPointer {
private:
using ElementType = typename std::tuple_element<I, std::tuple<Args...>>::type;
public:
static constexpr bool value = std::is_pointer<ElementType>::value;
};
// This class iterates over the parameter types, and if a given parameter is an input
// (i.e., is not a pointer), reads the corresponding argument tuple element from the data Parcel
template <typename... Params>
class InputReader;
template <typename... Params>
class InputReader<std::tuple<Params...>> {
public:
explicit InputReader(const char* logTag) : mLogTag(logTag) {}
// Note that in this case (as opposed to in SafeBpInterface), we iterate using an explicit
// index (starting with 0 here) instead of using recursion and stripping the first element.
// This is because in SafeBpInterface we aren't actually operating on a real tuple, but are
// instead just using a tuple as a convenient container for variadic types, whereas here we
// can't modify the argument tuple without causing unnecessary copies or moves of the data
// contained therein.
template <typename RawTuple>
status_t readInputs(const Parcel& data, RawTuple* args) {
return dispatchArg<0>(data, args);
}
private:
const char* const mLogTag;
template <std::size_t I, typename RawTuple>
typename std::enable_if<!ElementIsPointer<I, Params...>::value, status_t>::type readIfInput(
const Parcel& data, RawTuple* args) {
return SafeInterface::ParcelHandler{mLogTag}.read(data, &std::get<I>(*args));
}
template <std::size_t I, typename RawTuple>
typename std::enable_if<ElementIsPointer<I, Params...>::value, status_t>::type readIfInput(
const Parcel& /*data*/, RawTuple* /*args*/) {
return NO_ERROR;
}
// Recursively iterate through the arguments
template <std::size_t I, typename RawTuple>
typename std::enable_if<(I < sizeof...(Params)), status_t>::type dispatchArg(
const Parcel& data, RawTuple* args) {
status_t error = readIfInput<I>(data, args);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged in read
return error;
}
return dispatchArg<I + 1>(data, args);
}
template <std::size_t I, typename RawTuple>
typename std::enable_if<(I >= sizeof...(Params)), status_t>::type dispatchArg(
const Parcel& /*data*/, RawTuple* /*args*/) {
return NO_ERROR;
}
};
// getForCall uses the types of the parameters to determine whether a given element of the
// argument tuple is an input, which should be passed directly into the call, or an output, for
// which its address should be passed into the call
template <size_t I, typename RawTuple, typename... Params>
static typename std::enable_if<
ElementIsPointer<I, Params...>::value,
typename std::tuple_element<I, std::tuple<Params...>>::type>::type
getForCall(RawTuple* args) {
return &std::get<I>(*args);
}
template <size_t I, typename RawTuple, typename... Params>
static typename std::enable_if<
!ElementIsPointer<I, Params...>::value,
typename std::tuple_element<I, std::tuple<Params...>>::type>::type&
getForCall(RawTuple* args) {
return std::get<I>(*args);
}
// This template class uses std::index_sequence and parameter pack expansion to call the given
// method using the elements of the argument tuple (after those arguments are passed through
// getForCall to get addresses instead of values for output arguments)
template <typename... Params>
struct MethodCaller;
template <typename... Params>
struct MethodCaller<std::tuple<Params...>> {
public:
// The calls through these to the helper methods are necessary to generate the
// std::index_sequences used to unpack the argument tuple into the method call
template <typename Class, typename MemberFunction, typename RawTuple>
static status_t call(Class* instance, MemberFunction function, RawTuple* args) {
return callHelper(instance, function, args, std::index_sequence_for<Params...>{});
}
template <typename Class, typename MemberFunction, typename RawTuple>
static void callVoid(Class* instance, MemberFunction function, RawTuple* args) {
callVoidHelper(instance, function, args, std::index_sequence_for<Params...>{});
}
private:
template <typename Class, typename MemberFunction, typename RawTuple, std::size_t... I>
static status_t callHelper(Class* instance, MemberFunction function, RawTuple* args,
std::index_sequence<I...> /*unused*/) {
return (instance->*function)(getForCall<I, RawTuple, Params...>(args)...);
}
template <typename Class, typename MemberFunction, typename RawTuple, std::size_t... I>
static void callVoidHelper(Class* instance, MemberFunction function, RawTuple* args,
std::index_sequence<I...> /*unused*/) {
(instance->*function)(getForCall<I, RawTuple, Params...>(args)...);
}
};
// This class iterates over the parameter types, and if a given parameter is an output
// (i.e., is a pointer), writes the corresponding argument tuple element into the reply Parcel
template <typename... Params>
struct OutputWriter;
template <typename... Params>
struct OutputWriter<std::tuple<Params...>> {
public:
explicit OutputWriter(const char* logTag) : mLogTag(logTag) {}
// See the note on InputReader::readInputs for why this differs from the arguably simpler
// RemoveFirst approach in SafeBpInterface
template <typename RawTuple>
status_t writeOutputs(Parcel* reply, RawTuple* args) {
return dispatchArg<0>(reply, args);
}
private:
const char* const mLogTag;
template <std::size_t I, typename RawTuple>
typename std::enable_if<ElementIsPointer<I, Params...>::value, status_t>::type
writeIfOutput(Parcel* reply, RawTuple* args) {
return SafeInterface::ParcelHandler{mLogTag}.write(reply, std::get<I>(*args));
}
template <std::size_t I, typename RawTuple>
typename std::enable_if<!ElementIsPointer<I, Params...>::value, status_t>::type
writeIfOutput(Parcel* /*reply*/, RawTuple* /*args*/) {
return NO_ERROR;
}
// Recursively iterate through the arguments
template <std::size_t I, typename RawTuple>
typename std::enable_if<(I < sizeof...(Params)), status_t>::type dispatchArg(
Parcel* reply, RawTuple* args) {
status_t error = writeIfOutput<I>(reply, args);
if (CC_UNLIKELY(error != NO_ERROR)) {
// A message will have been logged in read
return error;
}
return dispatchArg<I + 1>(reply, args);
}
template <std::size_t I, typename RawTuple>
typename std::enable_if<(I >= sizeof...(Params)), status_t>::type dispatchArg(
Parcel* /*reply*/, RawTuple* /*args*/) {
return NO_ERROR;
}
};
};
} // namespace android