Merge "Add custom Error Prone check for rethrowing." into rvc-dev am: 971448af

    plugins: [

        "//external/dagger2:dagger2-auto-service",

    ],

    javacflags: ["-verbose"],

}

/*

 * 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.

 */

package com.google.errorprone.bugpatterns.android;

import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;

import static com.google.errorprone.matchers.Matchers.enclosingClass;

import static com.google.errorprone.matchers.Matchers.hasAnnotation;

import static com.google.errorprone.matchers.Matchers.instanceMethod;

import static com.google.errorprone.matchers.Matchers.isSameType;

import static com.google.errorprone.matchers.Matchers.methodInvocation;

import static com.google.errorprone.matchers.Matchers.throwStatement;

import static com.google.errorprone.matchers.Matchers.variableType;

import com.google.auto.service.AutoService;

import com.google.errorprone.BugPattern;

import com.google.errorprone.VisitorState;

import com.google.errorprone.bugpatterns.BugChecker;

import com.google.errorprone.bugpatterns.BugChecker.CatchTreeMatcher;

import com.google.errorprone.matchers.Description;

import com.google.errorprone.matchers.Matcher;

import com.sun.source.tree.CatchTree;

import com.sun.source.tree.StatementTree;

import com.sun.source.tree.Tree;

import com.sun.source.tree.VariableTree;

import java.util.List;

/**

 * Apps making calls into the system server may end up persisting internal state

 * or making security decisions based on the perceived success or failure of a

 * call, or any default values returned. For this reason, we want to strongly

 * throw when there was trouble with the transaction.

 * <p>

 * The rethrowFromSystemServer() method is the best-practice way of doing this

 * correctly, so that we don't clutter logs with misleading stack traces, and

 * this checker verifies that best-practice is used.

 */

@AutoService(BugChecker.class)

@BugPattern(

    name = "AndroidFrameworkRethrowFromSystem",

    summary = "Verifies that system_server calls use rethrowFromSystemServer()",

    severity = WARNING)

public final class RethrowFromSystemChecker extends BugChecker implements CatchTreeMatcher {

    private static final Matcher<Tree> INSIDE_MANAGER =

            enclosingClass(hasAnnotation("android.annotation.SystemService"));

    private static final Matcher<VariableTree> REMOTE_EXCEPTION = variableType(

            isSameType("android.os.RemoteException"));

    private static final Matcher<StatementTree> RETHROW_FROM_SYSTEM = throwStatement(

            methodInvocation(instanceMethod().onExactClass("android.os.RemoteException")

                    .named("rethrowFromSystemServer")));

    @Override

    public Description matchCatch(CatchTree tree, VisitorState state) {

        if (INSIDE_MANAGER.matches(tree, state)

                && REMOTE_EXCEPTION.matches(tree.getParameter(), state)) {

            final List<? extends StatementTree> statements = tree.getBlock().getStatements();

            if (statements.size() != 1 || !RETHROW_FROM_SYSTEM.matches(statements.get(0), state)) {

                return buildDescription(tree)

                        .setMessage("Must contain single "

                                + "'throw e.rethrowFromSystemServer()' statement")

                        .build();

            }

        }

        return Description.NO_MATCH;

    }

}

import com.sun.source.tree.ExpressionTree;

import com.sun.source.tree.Tree.Kind;

/**

 * Over the years we've had several obscure bugs related to how SDK level

 * comparisons are performed, specifically during the window of time where we've

 * started distributing the "frankenbuild" to developers.

 * <p>

 * Consider the case where a framework developer shipping release "R" wants to

 * only grant a specific behavior to modern apps; they could write this in two

 * different ways:

 * <ol>

 * <li>if (targetSdkVersion > Build.VERSION_CODES.Q) {

 * <li>if (targetSdkVersion >= Build.VERSION_CODES.R) {

 * </ol>

 * The safer of these two options is (2), which will ensure that developers only

 * get the behavior when <em>both</em> the app and the platform agree on the

 * specific SDK level having shipped.

 * <p>

 * Consider the breakage that would happen with option (1) if we started

 * shipping APKs that are based on the final R SDK, but are then installed on

 * earlier preview releases which still consider R to be CUR_DEVELOPMENT; they'd

 * risk crashing due to behaviors that were never part of the official R SDK.

 */

@AutoService(BugChecker.class)

@BugPattern(

    name = "AndroidFrameworkTargetSdk",