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/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
+}