Add java_fuzz module to build java fuzzers

This change adds a new module to soong to be able to build Java fuzz
targets be able to run using Jazzer. Jazzer is an open source fuzzing engine
supported by OSS-Fuzz.

Bug: 211671266
Test: go test -run TestJavaFuzz
Change-Id: Id7c346694f5986f6e15210c359fd533fbb7001eb

java/Android.bp

@@ -44,6 +44,7 @@ bootstrap_go_package {
         "dexpreopt_config.go",
         "droiddoc.go",
         "droidstubs.go",
+        "fuzz.go",
         "gen.go",
         "genrule.go",
         "hiddenapi.go",

java/fuzz.go

@@ -0,0 +1,72 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// 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 java
+
+import (
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+	"android/soong/fuzz"
+)
+
+func init() {
+	RegisterJavaFuzzBuildComponents(android.InitRegistrationContext)
+}
+
+func RegisterJavaFuzzBuildComponents(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("java_fuzz_host", FuzzFactory)
+}
+
+type JavaFuzzLibrary struct {
+	Library
+	fuzzPackagedModule fuzz.FuzzPackagedModule
+}
+
+func (j *JavaFuzzLibrary) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	j.Library.GenerateAndroidBuildActions(ctx)
+
+	if j.fuzzPackagedModule.FuzzProperties.Corpus != nil {
+		j.fuzzPackagedModule.Corpus = android.PathsForModuleSrc(ctx, j.fuzzPackagedModule.FuzzProperties.Corpus)
+	}
+	if j.fuzzPackagedModule.FuzzProperties.Data != nil {
+		j.fuzzPackagedModule.Data = android.PathsForModuleSrc(ctx, j.fuzzPackagedModule.FuzzProperties.Data)
+	}
+	if j.fuzzPackagedModule.FuzzProperties.Dictionary != nil {
+		j.fuzzPackagedModule.Dictionary = android.PathForModuleSrc(ctx, *j.fuzzPackagedModule.FuzzProperties.Dictionary)
+	}
+
+	if j.fuzzPackagedModule.FuzzProperties.Fuzz_config != nil {
+		configPath := android.PathForModuleOut(ctx, "config").Join(ctx, "config.json")
+		android.WriteFileRule(ctx, configPath, j.fuzzPackagedModule.FuzzProperties.Fuzz_config.String())
+		j.fuzzPackagedModule.Config = configPath
+	}
+}
+
+// java_fuzz builds and links sources into a `.jar` file for the host.
+//
+// By default, a java_fuzz produces a `.jar` file containing `.class` files.
+// This jar is not suitable for installing on a device.
+func FuzzFactory() android.Module {
+	module := &JavaFuzzLibrary{}
+
+	module.addHostProperties()
+	module.Module.properties.Installable = proptools.BoolPtr(false)
+	module.AddProperties(&module.fuzzPackagedModule.FuzzProperties)
+
+	module.initModuleAndImport(module)
+	android.InitSdkAwareModule(module)
+	InitJavaModule(module, android.HostSupported)
+	return module
+}

java/fuzz_test.go

@@ -0,0 +1,65 @@
+// Copyright 2021 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 java
+
+import (
+	"android/soong/android"
+	"path/filepath"
+	"testing"
+)
+
+var prepForJavaFuzzTest = android.GroupFixturePreparers(
+	PrepareForTestWithJavaDefaultModules,
+	android.FixtureRegisterWithContext(RegisterJavaFuzzBuildComponents),
+)
+
+func TestJavaFuzz(t *testing.T) {
+	result := prepForJavaFuzzTest.RunTestWithBp(t, `
+		java_fuzz_host {
+			name: "foo",
+			srcs: ["a.java"],
+			libs: ["bar"],
+			static_libs: ["baz"],
+		}
+
+		java_library_host {
+			name: "bar",
+			srcs: ["b.java"],
+		}
+
+		java_library_host {
+			name: "baz",
+			srcs: ["c.java"],
+		}`)
+
+	osCommonTarget := result.Config.BuildOSCommonTarget.String()
+	javac := result.ModuleForTests("foo", osCommonTarget).Rule("javac")
+	combineJar := result.ModuleForTests("foo", osCommonTarget).Description("for javac")
+
+	if len(javac.Inputs) != 1 || javac.Inputs[0].String() != "a.java" {
+		t.Errorf(`foo inputs %v != ["a.java"]`, javac.Inputs)
+	}
+
+	baz := result.ModuleForTests("baz", osCommonTarget).Rule("javac").Output.String()
+	barOut := filepath.Join("out", "soong", ".intermediates", "bar", osCommonTarget, "javac", "bar.jar")
+	bazOut := filepath.Join("out", "soong", ".intermediates", "baz", osCommonTarget, "javac", "baz.jar")
+
+	android.AssertStringDoesContain(t, "foo classpath", javac.Args["classpath"], barOut)
+	android.AssertStringDoesContain(t, "foo classpath", javac.Args["classpath"], bazOut)
+
+	if len(combineJar.Inputs) != 2 || combineJar.Inputs[1].String() != baz {
+		t.Errorf("foo combineJar inputs %v does not contain %q", combineJar.Inputs, baz)
+	}
+}