Initial system feature codegen prototype
Add a simple codegen utility for system features that:
* Exports a `hasFeatureX` method for each defined system feature
* Hardcodes the result if readonly system features are enabled
* Falls back to a runtime query otherwise
Note that this tool is not yet used, referenced, or enabled in any
production code. Follow-up changes will route build flags into
inputs for the codegen, and the outputs will be wired into the
framework.
Test: atest systemfeatures-gen-tests --host
Bug: 203143243
Change-Id: I059a38b11305c759662ea6c74c11d3cfdb058c40
diff --git a/tools/systemfeatures/Android.bp b/tools/systemfeatures/Android.bp
new file mode 100644
index 0000000..2cebfe9
--- /dev/null
+++ b/tools/systemfeatures/Android.bp
@@ -0,0 +1,63 @@
+package {
+ // See: http://go/android-license-faq
+ // A large-scale-change added 'default_applicable_licenses' to import
+ // all of the 'license_kinds' from "frameworks_base_license"
+ // to get the below license kinds:
+ // SPDX-license-identifier-Apache-2.0
+ default_applicable_licenses: ["frameworks_base_license"],
+}
+
+java_library_host {
+ name: "systemfeatures-gen-lib",
+ srcs: [
+ "src/**/*.java",
+ "src/**/*.kt",
+ ],
+ static_libs: [
+ "guava",
+ "javapoet",
+ ],
+}
+
+java_binary_host {
+ name: "systemfeatures-gen-tool",
+ main_class: "com.android.systemfeatures.SystemFeaturesGenerator",
+ static_libs: ["systemfeatures-gen-lib"],
+}
+
+// TODO(b/203143243): Add golden diff test for generated sources.
+// Functional runtime behavior is covered in systemfeatures-gen-tests.
+genrule {
+ name: "systemfeatures-gen-tests-srcs",
+ cmd: "$(location systemfeatures-gen-tool) com.android.systemfeatures.RwNoFeatures --readonly=false > $(location RwNoFeatures.java) && " +
+ "$(location systemfeatures-gen-tool) com.android.systemfeatures.RoNoFeatures --readonly=true > $(location RoNoFeatures.java) && " +
+ "$(location systemfeatures-gen-tool) com.android.systemfeatures.RwFeatures --readonly=false --feature=WATCH:1 --feature=WIFI:0 --feature=VULKAN:-1 --feature=AUTO: > $(location RwFeatures.java) && " +
+ "$(location systemfeatures-gen-tool) com.android.systemfeatures.RoFeatures --readonly=true --feature=WATCH:1 --feature=WIFI:0 --feature=VULKAN:-1 --feature=AUTO: > $(location RoFeatures.java)",
+ out: [
+ "RwNoFeatures.java",
+ "RoNoFeatures.java",
+ "RwFeatures.java",
+ "RoFeatures.java",
+ ],
+ tools: ["systemfeatures-gen-tool"],
+}
+
+java_test_host {
+ name: "systemfeatures-gen-tests",
+ test_suites: ["general-tests"],
+ srcs: [
+ "tests/**/*.java",
+ ":systemfeatures-gen-tests-srcs",
+ ],
+ test_options: {
+ unit_test: true,
+ },
+ static_libs: [
+ "aconfig-annotations-lib",
+ "framework-annotations-lib",
+ "junit",
+ "objenesis",
+ "mockito",
+ "truth",
+ ],
+}
diff --git a/tools/systemfeatures/src/com/android/systemfeatures/SystemFeaturesGenerator.kt b/tools/systemfeatures/src/com/android/systemfeatures/SystemFeaturesGenerator.kt
new file mode 100644
index 0000000..9bfda45
--- /dev/null
+++ b/tools/systemfeatures/src/com/android/systemfeatures/SystemFeaturesGenerator.kt
@@ -0,0 +1,218 @@
+/*
+ * Copyright (C) 2024 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.systemfeatures
+
+import com.google.common.base.CaseFormat
+import com.squareup.javapoet.ClassName
+import com.squareup.javapoet.JavaFile
+import com.squareup.javapoet.MethodSpec
+import com.squareup.javapoet.TypeSpec
+import javax.lang.model.element.Modifier
+
+/*
+ * Simple Java code generator that takes as input a list of defined features and generates an
+ * accessory class based on the provided versions.
+ *
+ * <p>Example:
+ *
+ * <pre>
+ * <cmd> com.foo.RoSystemFeatures --readonly=true \
+ * --feature=WATCH:0 --feature=AUTOMOTIVE: --feature=VULKAN:9348
+ * </pre>
+ *
+ * This generates a class that has the following signature:
+ *
+ * <pre>
+ * package com.foo;
+ * public final class RoSystemFeatures {
+ * @AssumeTrueForR8
+ * public static boolean hasFeatureWatch(Context context);
+ * @AssumeFalseForR8
+ * public static boolean hasFeatureAutomotive(Context context);
+ * @AssumeTrueForR8
+ * public static boolean hasFeatureVulkan(Context context);
+ * public static Boolean maybeHasFeature(String feature, int version);
+ * }
+ * </pre>
+ */
+object SystemFeaturesGenerator {
+ private const val FEATURE_ARG = "--feature="
+ private const val READONLY_ARG = "--readonly="
+ private val PACKAGEMANAGER_CLASS = ClassName.get("android.content.pm", "PackageManager")
+ private val CONTEXT_CLASS = ClassName.get("android.content", "Context")
+ private val ASSUME_TRUE_CLASS =
+ ClassName.get("com.android.aconfig.annotations", "AssumeTrueForR8")
+ private val ASSUME_FALSE_CLASS =
+ ClassName.get("com.android.aconfig.annotations", "AssumeFalseForR8")
+
+ private fun usage() {
+ println("Usage: SystemFeaturesGenerator <outputClassName> [options]")
+ println(" Options:")
+ println(" --readonly=true|false Whether to encode features as build-time constants")
+ println(" --feature=\$NAME:\$VER A feature+version pair (blank version == disabled)")
+ }
+
+ /** Main entrypoint for build-time system feature codegen. */
+ @JvmStatic
+ fun main(args: Array<String>) {
+ if (args.size < 1) {
+ usage()
+ return
+ }
+
+ var readonly = false
+ var outputClassName: ClassName? = null
+ val features = mutableListOf<FeatureInfo>()
+ for (arg in args) {
+ when {
+ arg.startsWith(READONLY_ARG) ->
+ readonly = arg.substring(READONLY_ARG.length).toBoolean()
+ arg.startsWith(FEATURE_ARG) -> {
+ features.add(parseFeatureArg(arg))
+ }
+ else -> outputClassName = ClassName.bestGuess(arg)
+ }
+ }
+
+ outputClassName
+ ?: run {
+ println("Output class name must be provided.")
+ usage()
+ return
+ }
+
+ val classBuilder =
+ TypeSpec.classBuilder(outputClassName)
+ .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+ .addJavadoc("@hide")
+
+ addFeatureMethodsToClass(classBuilder, readonly, features)
+ addMaybeFeatureMethodToClass(classBuilder, readonly, features)
+
+ // TODO(b/203143243): Add validation of build vs runtime values to ensure consistency.
+ JavaFile.builder(outputClassName.packageName(), classBuilder.build())
+ .build()
+ .writeTo(System.out)
+ }
+
+ /*
+ * Parses a feature argument of the form "--feature=$NAME:$VER", where "$VER" is optional.
+ * * "--feature=WATCH:0" -> Feature enabled w/ version 0 (default version when enabled)
+ * * "--feature=WATCH:7" -> Feature enabled w/ version 7
+ * * "--feature=WATCH:" -> Feature disabled
+ */
+ private fun parseFeatureArg(arg: String): FeatureInfo {
+ val featureArgs = arg.substring(FEATURE_ARG.length).split(":")
+ val name = featureArgs[0].let { if (!it.startsWith("FEATURE_")) "FEATURE_$it" else it }
+ val version = featureArgs.getOrNull(1)?.toIntOrNull()
+ return FeatureInfo(name, version)
+ }
+
+ /*
+ * Adds per-feature query methods to the class with the form:
+ * {@code public static boolean hasFeatureX(Context context)},
+ * returning the fallback value from PackageManager if not readonly.
+ */
+ private fun addFeatureMethodsToClass(
+ builder: TypeSpec.Builder,
+ readonly: Boolean,
+ features: List<FeatureInfo>
+ ) {
+ for (feature in features) {
+ // Turn "FEATURE_FOO" into "hasFeatureFoo".
+ val methodName =
+ "has" + CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, feature.name)
+ val methodBuilder =
+ MethodSpec.methodBuilder(methodName)
+ .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+ .returns(Boolean::class.java)
+ .addParameter(CONTEXT_CLASS, "context")
+
+ if (readonly) {
+ val featureEnabled = compareValues(feature.version, 0) >= 0
+ methodBuilder.addAnnotation(
+ if (featureEnabled) ASSUME_TRUE_CLASS else ASSUME_FALSE_CLASS
+ )
+ methodBuilder.addStatement("return $featureEnabled")
+ } else {
+ methodBuilder.addStatement(
+ "return hasFeatureFallback(context, \$T.\$N)",
+ PACKAGEMANAGER_CLASS,
+ feature.name
+ )
+ }
+ builder.addMethod(methodBuilder.build())
+ }
+
+ if (!readonly) {
+ builder.addMethod(
+ MethodSpec.methodBuilder("hasFeatureFallback")
+ .addModifiers(Modifier.PRIVATE, Modifier.STATIC)
+ .returns(Boolean::class.java)
+ .addParameter(CONTEXT_CLASS, "context")
+ .addParameter(String::class.java, "featureName")
+ .addStatement(
+ "return context.getPackageManager().hasSystemFeature(featureName, 0)"
+ )
+ .build()
+ )
+ }
+ }
+
+ /*
+ * Adds a generic query method to the class with the form: {@code public static boolean
+ * maybeHasFeature(String featureName, int version)}, returning null if the feature version is
+ * undefined or not readonly.
+ *
+ * This method is useful for internal usage within the framework, e.g., from the implementation
+ * of {@link android.content.pm.PackageManager#hasSystemFeature(Context)}, when we may only
+ * want a valid result if it's defined as readonly, and we want a custom fallback otherwise
+ * (e.g., to the existing runtime binder query).
+ */
+ private fun addMaybeFeatureMethodToClass(
+ builder: TypeSpec.Builder,
+ readonly: Boolean,
+ features: List<FeatureInfo>
+ ) {
+ val methodBuilder =
+ MethodSpec.methodBuilder("maybeHasFeature")
+ .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
+ .addAnnotation(ClassName.get("android.annotation", "Nullable"))
+ .returns(Boolean::class.javaObjectType) // Use object type for nullability
+ .addParameter(String::class.java, "featureName")
+ .addParameter(Int::class.java, "version")
+
+ if (readonly) {
+ methodBuilder.beginControlFlow("switch (featureName)")
+ for (feature in features) {
+ methodBuilder.addCode("case \$T.\$N: ", PACKAGEMANAGER_CLASS, feature.name)
+ if (feature.version != null) {
+ methodBuilder.addStatement("return \$L >= version", feature.version)
+ } else {
+ methodBuilder.addStatement("return false")
+ }
+ }
+ methodBuilder.addCode("default: ")
+ methodBuilder.addStatement("break")
+ methodBuilder.endControlFlow()
+ }
+ methodBuilder.addStatement("return null")
+ builder.addMethod(methodBuilder.build())
+ }
+
+ private data class FeatureInfo(val name: String, val version: Int?)
+}
diff --git a/tools/systemfeatures/tests/Context.java b/tools/systemfeatures/tests/Context.java
new file mode 100644
index 0000000..630bc07
--- /dev/null
+++ b/tools/systemfeatures/tests/Context.java
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2024 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 android.content;
+
+import android.content.pm.PackageManager;
+
+/** Stub for testing. */
+public class Context {
+ /** @hide */
+ public PackageManager getPackageManager() {
+ return null;
+ }
+}
diff --git a/tools/systemfeatures/tests/PackageManager.java b/tools/systemfeatures/tests/PackageManager.java
new file mode 100644
index 0000000..645d500
--- /dev/null
+++ b/tools/systemfeatures/tests/PackageManager.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2024 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 android.content.pm;
+
+/** Stub for testing */
+public class PackageManager {
+ public static final String FEATURE_AUTO = "automotive";
+ public static final String FEATURE_VULKAN = "vulkan";
+ public static final String FEATURE_WATCH = "watch";
+ public static final String FEATURE_WIFI = "wifi";
+
+ /** @hide */
+ public boolean hasSystemFeature(String featureName, int version) {
+ return false;
+ }
+}
diff --git a/tools/systemfeatures/tests/SystemFeaturesGeneratorTest.java b/tools/systemfeatures/tests/SystemFeaturesGeneratorTest.java
new file mode 100644
index 0000000..547d2cb
--- /dev/null
+++ b/tools/systemfeatures/tests/SystemFeaturesGeneratorTest.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2024 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.systemfeatures;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.anyString;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.content.pm.PackageManager;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+
+@RunWith(JUnit4.class)
+public class SystemFeaturesGeneratorTest {
+
+ @Rule public final MockitoRule mockito = MockitoJUnit.rule();
+
+ @Mock private Context mContext;
+ @Mock private PackageManager mPackageManager;
+
+ @Before
+ public void setUp() {
+ when(mContext.getPackageManager()).thenReturn(mPackageManager);
+ }
+
+ @Test
+ public void testReadonlyDisabledNoDefinedFeatures() {
+ // Always report null for conditional queries if readonly codegen is disabled.
+ assertThat(RwNoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 0)).isNull();
+ assertThat(RwNoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 0)).isNull();
+ assertThat(RwNoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 0)).isNull();
+ assertThat(RwNoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isNull();
+ assertThat(RwNoFeatures.maybeHasFeature("com.arbitrary.feature", 0)).isNull();
+ }
+
+ @Test
+ public void testReadonlyNoDefinedFeatures() {
+ // If no features are explicitly declared as readonly available, always report
+ // null for conditional queries.
+ assertThat(RoNoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 0)).isNull();
+ assertThat(RoNoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 0)).isNull();
+ assertThat(RoNoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 0)).isNull();
+ assertThat(RoNoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isNull();
+ assertThat(RoNoFeatures.maybeHasFeature("com.arbitrary.feature", 0)).isNull();
+ }
+
+ @Test
+ public void testReadonlyDisabledWithDefinedFeatures() {
+ // Always fall back to the PackageManager for defined, explicit features queries.
+ when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_WATCH, 0)).thenReturn(true);
+ assertThat(RwFeatures.hasFeatureWatch(mContext)).isTrue();
+
+ when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_WATCH, 0)).thenReturn(false);
+ assertThat(RwFeatures.hasFeatureWatch(mContext)).isFalse();
+
+ when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_WIFI, 0)).thenReturn(true);
+ assertThat(RwFeatures.hasFeatureWifi(mContext)).isTrue();
+
+ when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_VULKAN, 0)).thenReturn(false);
+ assertThat(RwFeatures.hasFeatureVulkan(mContext)).isFalse();
+
+ when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTO, 0)).thenReturn(false);
+ assertThat(RwFeatures.hasFeatureAuto(mContext)).isFalse();
+
+ // For defined and undefined features, conditional queries should report null (unknown).
+ assertThat(RwFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 0)).isNull();
+ assertThat(RwFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 0)).isNull();
+ assertThat(RwFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 0)).isNull();
+ assertThat(RwFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isNull();
+ assertThat(RwFeatures.maybeHasFeature("com.arbitrary.feature", 0)).isNull();
+ }
+
+ @Test
+ public void testReadonlyWithDefinedFeatures() {
+ // Always use the build-time feature version for defined, explicit feature queries, never
+ // falling back to the runtime query.
+ assertThat(RoFeatures.hasFeatureWatch(mContext)).isTrue();
+ assertThat(RoFeatures.hasFeatureWifi(mContext)).isTrue();
+ assertThat(RoFeatures.hasFeatureVulkan(mContext)).isFalse();
+ assertThat(RoFeatures.hasFeatureAuto(mContext)).isFalse();
+ verify(mPackageManager, never()).hasSystemFeature(anyString(), anyInt());
+
+ // For defined feature types, conditional queries should reflect the build-time versions.
+ // VERSION=1
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, -1)).isTrue();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 0)).isTrue();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 100)).isFalse();
+
+ // VERSION=0
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, -1)).isTrue();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 0)).isTrue();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 100)).isFalse();
+
+ // VERSION=-1
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, -1)).isTrue();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 0)).isFalse();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 100)).isFalse();
+
+ // DISABLED
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, -1)).isFalse();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isFalse();
+ assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 100)).isFalse();
+
+ // For undefined types, conditional queries should report null (unknown).
+ assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", -1)).isNull();
+ assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", 0)).isNull();
+ assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", 100)).isNull();
+ }
+}