Create a module that extracts and installs compat_config.

Currently it extracts from the provided jar file compat/compat_config.xml
(generated by compat-changeid-annotation-processor) and installs on
/system/etc/sysconfig.
Future improvements:
 - Merge all the configs going for the system image into one, so that
   duplicate change ids across modules are failing the build instead of
   runtime.
 - Support uploading the config onto APEX for APEX modules.

Test: flashed device locally, config files found and read by
com.android.server.compat.CompatConfig.
Bug: 138222363

Change-Id: I64b11fdc466f746702e7e73f612794e024de2288

Android.bp

@@ -282,6 +282,7 @@ bootstrap_go_package {
         "java/jdeps.go",
         "java/java_resources.go",
         "java/kotlin.go",
+        "java/platform_compat_config.go",
         "java/plugin.go",
         "java/prebuilt_apis.go",
         "java/proto.go",

java/platform_compat_config.go

@@ -0,0 +1,92 @@
+// Copyright 2019 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 (
+	"android/soong/android"
+)
+
+func init() {
+	android.RegisterModuleType("platform_compat_config", platformCompatConfigFactory)
+}
+
+type platformCompatConfigProperties struct {
+	Src    *string `android:"path"`
+	Prefix *string
+}
+
+type platformCompatConfig struct {
+	android.ModuleBase
+
+	properties     platformCompatConfigProperties
+	installDirPath android.OutputPath
+	configFile     android.OutputPath
+}
+
+func (p *platformCompatConfig) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	rule := android.NewRuleBuilder()
+
+	configFileName := String(p.properties.Prefix) + "_platform_compat_config.xml"
+	p.configFile = android.PathForModuleOut(ctx, configFileName).OutputPath
+	path := android.PathForModuleSrc(ctx, String(p.properties.Src))
+
+	// Use the empty config if the compat config file idoesn't exist (can happen if @ChangeId
+	// annotation is not used).
+	emptyConfig := `<?xml version="1.0" encoding="UTF-8" standalone="no"?><config/>`
+	configPath := `compat/compat_config.xml`
+
+	rule.Command().
+		Text(`unzip`).
+		Flag(`-l`).
+		Input(path).
+		Text(`| grep`).
+		Flag(`-q`).
+		Text(configPath).
+		Text(`; if [ "$?" = "0" ] ; then`).
+		Text(`unzip`).
+		Flag(`-qp`).
+		Input(path).
+		Text(configPath).
+		Text(`>`).
+		Output(p.configFile).
+		Text(`; else echo '`).
+		Text(emptyConfig).
+		Text(`' >`).
+		Output(p.configFile).
+		Text(`; fi`)
+
+	p.installDirPath = android.PathForModuleInstall(ctx, "etc", "sysconfig")
+	rule.Build(pctx, ctx, configFileName, "Extract compat/compat_config.xml and install it")
+
+}
+
+func (p *platformCompatConfig) AndroidMkEntries() android.AndroidMkEntries {
+	return android.AndroidMkEntries{
+		Class:      "ETC",
+		OutputFile: android.OptionalPathForPath(p.configFile),
+		Include:    "$(BUILD_PREBUILT)",
+		AddCustomEntries: func(name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
+			entries.SetString("LOCAL_MODULE_PATH", "$(OUT_DIR)/"+p.installDirPath.RelPathString())
+			entries.SetString("LOCAL_INSTALLED_MODULE_STEM", p.configFile.Base())
+		},
+	}
+}
+
+func platformCompatConfigFactory() android.Module {
+	module := &platformCompatConfig{}
+	module.AddProperties(&module.properties)
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibFirst)
+	return module
+}