Bootstrap IInputFlingerRust - the Rust component of inputflinger
When inputflinger boots, we create the Rust component of inputflinger,
which we interact with from C++ through the local AIDL interface
IInputFlingerRust.
After we have access to the IInputFlingerRust binder object in C++, all
communication between C++ and Rust can take place purely through AIDL
interfaces.
To initialize the interface, we must first pass a raw pointer to an AIDL
implementation across the language barrier through some other means. In
this CL, we use cxxbridge to bootstrap the local AIDL interface for
IInputFlingerRust.
Bug: 278783893
Test: manual, boot
Change-Id: Ifbd0168ae4fadaa5b357f6064113f1691e6cf5a7
diff --git a/services/inputflinger/Android.bp b/services/inputflinger/Android.bp
index 18f6dbc..d551213 100644
--- a/services/inputflinger/Android.bp
+++ b/services/inputflinger/Android.bp
@@ -87,6 +87,7 @@
srcs: [":libinputflinger_sources"],
shared_libs: [
"android.hardware.input.processor-V1-ndk",
+ "com.android.server.inputflinger-ndk",
"libbase",
"libbinder",
"libbinder_ndk",
@@ -107,6 +108,14 @@
"libpalmrejection",
"libui-types",
],
+ generated_headers: [
+ "cxx-bridge-header",
+ "inputflinger_rs_bootstrap_bridge_header",
+ ],
+ header_libs: ["inputflinger_rs_bootstrap_cxx_headers"],
+ generated_sources: ["inputflinger_rs_bootstrap_bridge_code"],
+ whole_static_libs: ["libinputflinger_rs"],
+ export_shared_lib_headers: ["com.android.server.inputflinger-ndk"],
target: {
android: {
shared_libs: [
diff --git a/services/inputflinger/InputManager.cpp b/services/inputflinger/InputManager.cpp
index c903564..da79ae3 100644
--- a/services/inputflinger/InputManager.cpp
+++ b/services/inputflinger/InputManager.cpp
@@ -23,22 +23,22 @@
#include "InputReaderFactory.h"
#include "UnwantedInteractionBlocker.h"
+#include <aidl/com/android/server/inputflinger/IInputFlingerRust.h>
+#include <android/binder_interface_utils.h>
#include <android/sysprop/InputProperties.sysprop.h>
#include <binder/IPCThreadState.h>
-
+#include <inputflinger_bootstrap.rs.h>
#include <log/log.h>
-#include <unordered_map>
-
#include <private/android_filesystem_config.h>
namespace android {
-static const bool ENABLE_INPUT_DEVICE_USAGE_METRICS =
+namespace {
+
+const bool ENABLE_INPUT_DEVICE_USAGE_METRICS =
sysprop::InputProperties::enable_input_device_usage_metrics().value_or(true);
-using gui::FocusRequest;
-
-static int32_t exceptionCodeFromStatusT(status_t status) {
+int32_t exceptionCodeFromStatusT(status_t status) {
switch (status) {
case OK:
return binder::Status::EX_NONE;
@@ -57,6 +57,58 @@
}
}
+// Convert a binder interface into a raw pointer to an AIBinder.
+using IInputFlingerRustBootstrapCallback = aidl::com::android::server::inputflinger::
+ IInputFlingerRust::IInputFlingerRustBootstrapCallback;
+IInputFlingerRustBootstrapCallbackAIBinder* binderToPointer(
+ IInputFlingerRustBootstrapCallback& interface) {
+ ndk::SpAIBinder spAIBinder = interface.asBinder();
+ auto* ptr = spAIBinder.get();
+ AIBinder_incStrong(ptr);
+ return ptr;
+}
+
+// Create the Rust component of InputFlinger that uses AIDL interfaces as a the foreign function
+// interface (FFI). The bootstraping process for IInputFlingerRust is as follows:
+// - Create BnInputFlingerRustBootstrapCallback in C++.
+// - Use the cxxbridge ffi interface to call the Rust function `create_inputflinger_rust()`, and
+// pass the callback binder object as a raw pointer.
+// - The Rust implementation will create the implementation of IInputFlingerRust, and pass it
+// to C++ through the callback.
+// - After the Rust function returns, the binder interface provided to the callback will be the
+// only strong reference to the IInputFlingerRust.
+std::shared_ptr<IInputFlingerRust> createInputFlingerRust() {
+ using namespace aidl::com::android::server::inputflinger;
+
+ class Callback : public IInputFlingerRust::BnInputFlingerRustBootstrapCallback {
+ ndk::ScopedAStatus onProvideInputFlingerRust(
+ const std::shared_ptr<IInputFlingerRust>& inputFlingerRust) override {
+ mService = inputFlingerRust;
+ return ndk::ScopedAStatus::ok();
+ }
+
+ public:
+ std::shared_ptr<IInputFlingerRust> consumeInputFlingerRust() {
+ auto service = mService;
+ mService.reset();
+ return service;
+ }
+
+ private:
+ std::shared_ptr<IInputFlingerRust> mService;
+ };
+
+ auto callback = ndk::SharedRefBase::make<Callback>();
+ create_inputflinger_rust(binderToPointer(*callback));
+ auto service = callback->consumeInputFlingerRust();
+ LOG_ALWAYS_FATAL_IF(!service,
+ "create_inputflinger_rust did not provide the IInputFlingerRust "
+ "implementation through the callback.");
+ return service;
+}
+
+} // namespace
+
/**
* The event flow is via the "InputListener" interface, as follows:
* InputReader
@@ -67,6 +119,8 @@
*/
InputManager::InputManager(const sp<InputReaderPolicyInterface>& readerPolicy,
InputDispatcherPolicyInterface& dispatcherPolicy) {
+ mInputFlingerRust = createInputFlingerRust();
+
mDispatcher = createInputDispatcher(dispatcherPolicy);
if (ENABLE_INPUT_DEVICE_USAGE_METRICS) {
@@ -190,7 +244,7 @@
return NO_ERROR;
}
-binder::Status InputManager::setFocusedWindow(const FocusRequest& request) {
+binder::Status InputManager::setFocusedWindow(const gui::FocusRequest& request) {
mDispatcher->setFocusedWindow(request);
return binder::Status::ok();
}
diff --git a/services/inputflinger/InputManager.h b/services/inputflinger/InputManager.h
index 9dc285f..528d2aa 100644
--- a/services/inputflinger/InputManager.h
+++ b/services/inputflinger/InputManager.h
@@ -30,6 +30,7 @@
#include <input/Input.h>
#include <input/InputTransport.h>
+#include <aidl/com/android/server/inputflinger/IInputFlingerRust.h>
#include <android/os/BnInputFlinger.h>
#include <utils/Errors.h>
#include <utils/RefBase.h>
@@ -37,6 +38,8 @@
using android::os::BnInputFlinger;
+using aidl::com::android::server::inputflinger::IInputFlingerRust;
+
namespace android {
class InputChannel;
class InputDispatcherThread;
@@ -132,6 +135,8 @@
std::unique_ptr<InputDeviceMetricsCollectorInterface> mCollector;
std::unique_ptr<InputDispatcherInterface> mDispatcher;
+
+ std::shared_ptr<IInputFlingerRust> mInputFlingerRust;
};
} // namespace android
diff --git a/services/inputflinger/aidl/Android.bp b/services/inputflinger/aidl/Android.bp
new file mode 100644
index 0000000..314c433
--- /dev/null
+++ b/services/inputflinger/aidl/Android.bp
@@ -0,0 +1,31 @@
+// Copyright 2023 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.
+
+aidl_interface {
+ name: "com.android.server.inputflinger",
+ srcs: ["**/*.aidl"],
+ unstable: true,
+ host_supported: true,
+ backend: {
+ cpp: {
+ enabled: false,
+ },
+ java: {
+ enabled: false,
+ },
+ rust: {
+ enabled: true,
+ },
+ },
+}
diff --git a/services/inputflinger/aidl/com/android/server/inputflinger/IInputFlingerRust.aidl b/services/inputflinger/aidl/com/android/server/inputflinger/IInputFlingerRust.aidl
new file mode 100644
index 0000000..8e826fd
--- /dev/null
+++ b/services/inputflinger/aidl/com/android/server/inputflinger/IInputFlingerRust.aidl
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2023 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.
+ */
+
+package com.android.server.inputflinger;
+
+/**
+ * A local AIDL interface used as a foreign function interface (ffi) to
+ * communicate with the Rust component of inputflinger.
+ *
+ * NOTE: Since we use this as a local interface, all processing happens on the
+ * calling thread.
+ */
+interface IInputFlingerRust {
+
+ /**
+ * An interface used to get a strong reference to IInputFlingerRust on boot.
+ */
+ interface IInputFlingerRustBootstrapCallback {
+ void onProvideInputFlingerRust(in IInputFlingerRust inputFlingerRust);
+ }
+}
diff --git a/services/inputflinger/rust/Android.bp b/services/inputflinger/rust/Android.bp
new file mode 100644
index 0000000..23c1691
--- /dev/null
+++ b/services/inputflinger/rust/Android.bp
@@ -0,0 +1,52 @@
+// Copyright 2023 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.
+
+// Generate the C++ code that Rust calls into.
+genrule {
+ name: "inputflinger_rs_bootstrap_bridge_code",
+ tools: ["cxxbridge"],
+ cmd: "$(location cxxbridge) $(in) >> $(out)",
+ srcs: ["lib.rs"],
+ out: ["inputflinger_rs_bootstrap_cxx_generated.cc"],
+}
+
+// Generate a C++ header containing the C++ bindings
+// to the Rust exported functions in lib.rs.
+genrule {
+ name: "inputflinger_rs_bootstrap_bridge_header",
+ tools: ["cxxbridge"],
+ cmd: "$(location cxxbridge) $(in) --header >> $(out)",
+ srcs: ["lib.rs"],
+ out: ["inputflinger_bootstrap.rs.h"],
+}
+
+rust_ffi_static {
+ name: "libinputflinger_rs",
+ crate_name: "inputflinger",
+ srcs: ["lib.rs"],
+ rustlibs: [
+ "libcxx",
+ "com.android.server.inputflinger-rust",
+ "libbinder_rs",
+ "liblog_rust",
+ "liblogger",
+ ],
+ host_supported: true,
+}
+
+cc_library_headers {
+ name: "inputflinger_rs_bootstrap_cxx_headers",
+ host_supported: true,
+ export_include_dirs: ["ffi"],
+}
diff --git a/services/inputflinger/rust/ffi/InputFlingerBootstrap.h b/services/inputflinger/rust/ffi/InputFlingerBootstrap.h
new file mode 100644
index 0000000..eb79ab5
--- /dev/null
+++ b/services/inputflinger/rust/ffi/InputFlingerBootstrap.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2023 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 <android/binder_parcel.h>
+
+using IInputFlingerRustBootstrapCallbackAIBinder = AIBinder;
diff --git a/services/inputflinger/rust/lib.rs b/services/inputflinger/rust/lib.rs
new file mode 100644
index 0000000..c0561d7
--- /dev/null
+++ b/services/inputflinger/rust/lib.rs
@@ -0,0 +1,99 @@
+/*
+ * Copyright 2023 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.
+ */
+
+//! # The rust component of InputFlinger
+//!
+//! We use cxxbridge to create IInputFlingerRust - the Rust component of inputflinger - and
+//! pass it back to C++ as a local AIDL interface.
+
+use binder::{
+ unstable_api::{AIBinder, new_spibinder,},
+ BinderFeatures, Interface, StatusCode, Strong,
+};
+use com_android_server_inputflinger::aidl::com::android::server::inputflinger::IInputFlingerRust::{
+ BnInputFlingerRust, IInputFlingerRust,
+ IInputFlingerRustBootstrapCallback::IInputFlingerRustBootstrapCallback,
+};
+use log::debug;
+
+const LOG_TAG: &str = "inputflinger_bootstrap";
+
+#[cxx::bridge]
+mod ffi {
+ extern "C++" {
+ include!("InputFlingerBootstrap.h");
+ type IInputFlingerRustBootstrapCallbackAIBinder;
+ }
+
+ extern "Rust" {
+ unsafe fn create_inputflinger_rust(
+ callback: *mut IInputFlingerRustBootstrapCallbackAIBinder,
+ );
+ }
+}
+
+/// Create the IInputFlingerRust implementation.
+/// This is the singular entry point from C++ into Rust.
+/// The `callback` parameter must be a valid pointer to an AIBinder implementation of
+/// the `IInputFlingerRustBootstrapCallback` interface. The IInputFlingerRust implementation that
+/// is created will be passed back through the callback from within this function.
+/// NOTE: This function must not hold a strong reference to the callback beyond its scope.
+///
+/// # Safety
+///
+/// This function is safe iff `callback` is a valid pointer to an `AIBinder` interface of type
+/// `IInputFlingerRustBootstrapCallback`. The pointer must have had its reference count manually
+/// incremented using `AIBinder_incStrong`. See `binder::unstable_api::new_spibinder`.
+unsafe fn create_inputflinger_rust(callback: *mut ffi::IInputFlingerRustBootstrapCallbackAIBinder) {
+ logger::init(
+ logger::Config::default().with_tag_on_device(LOG_TAG).with_min_level(log::Level::Trace),
+ );
+
+ let callback = callback as *mut AIBinder;
+ if callback.is_null() {
+ panic!("create_inputflinger_rust cannot be called with a null callback");
+ }
+
+ let Some(callback) = new_spibinder(callback) else {
+ panic!("Failed to get SpAIBinder from raw callback pointer");
+ };
+
+ let callback: Result<Strong<dyn IInputFlingerRustBootstrapCallback>, StatusCode> =
+ callback.into_interface();
+ match callback {
+ Ok(callback) => {
+ debug!("Creating InputFlingerRust");
+ let service =
+ BnInputFlingerRust::new_binder(InputFlingerRust {}, BinderFeatures::default());
+ callback.onProvideInputFlingerRust(&service).unwrap();
+ }
+ Err(status) => {
+ panic!("Failed to convert AIBinder into the callback interface: {}", status);
+ }
+ }
+}
+
+struct InputFlingerRust {}
+
+impl Interface for InputFlingerRust {}
+
+impl IInputFlingerRust for InputFlingerRust {}
+
+impl Drop for InputFlingerRust {
+ fn drop(&mut self) {
+ debug!("Destroying InputFlingerRust");
+ }
+}