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Commit 230d6502 authored by Jared Duke's avatar Jared Duke
Browse files

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
parent b7e715d8

tools/systemfeatures/Android.bp

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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",

    ],

}

tools/systemfeatures/src/com/android/systemfeatures/SystemFeaturesGenerator.kt

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/*

 * 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?)

}

tools/systemfeatures/tests/Context.java

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/*

 * 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;

    }

}

tools/systemfeatures/tests/PackageManager.java

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/*

 * 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;

    }

}

tools/systemfeatures/tests/SystemFeaturesGeneratorTest.java

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/*

 * 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();

    }

}