Adding java_sdk_library

java_sdk_library is to make a Java library that implements optional
SDK APIs to apps. It is actually a wrapper for several modules: 1) stubs
library that clients are linked against to, 2) droiddoc module that
internally generates API stubs source files, 3) the real runtime shared
library that implements the API, and 4) XML file for adding the runtime
lib to the classpath at runtime if requested via <uses-library>.

Note: this is only the initial CL for the feature. Followings are features
currently missing and under development.

1) check for API consistency
2) install stubs libs as the dist artifacts
3) ensuring that apps have appropriate <uses-library> tag
4) disallowing linking to the runtime shared lib
5) HTML generation

Bug: 77575606
Test: m -j

Change-Id: I4a4ccf6e730e041703c63bb275d8860d0de96887
diff --git a/Android.bp b/Android.bp
index f2289da..5396664 100644
--- a/Android.bp
+++ b/Android.bp
@@ -57,6 +57,7 @@
         "android/package_ctx.go",
         "android/paths.go",
         "android/prebuilt.go",
+        "android/prebuilt_etc.go",
         "android/proto.go",
         "android/register.go",
         "android/singleton.go",
@@ -232,6 +233,7 @@
         "java/java.go",
         "java/java_resources.go",
         "java/proto.go",
+        "java/sdk_library.go",
         "java/system_modules.go",
     ],
     testSrcs: [
diff --git a/android/module.go b/android/module.go
index 3bd256a..552d165 100644
--- a/android/module.go
+++ b/android/module.go
@@ -501,6 +501,22 @@
 				*a.hostAndDeviceProperties.Device_supported)
 }
 
+func (a *ModuleBase) Platform() bool {
+	return !a.DeviceSpecific() && !a.SocSpecific() && !a.ProductSpecific()
+}
+
+func (a *ModuleBase) DeviceSpecific() bool {
+	return Bool(a.commonProperties.Device_specific)
+}
+
+func (a *ModuleBase) SocSpecific() bool {
+	return Bool(a.commonProperties.Vendor) || Bool(a.commonProperties.Proprietary) || Bool(a.commonProperties.Soc_specific)
+}
+
+func (a *ModuleBase) ProductSpecific() bool {
+	return Bool(a.commonProperties.Product_specific)
+}
+
 func (a *ModuleBase) Enabled() bool {
 	if a.commonProperties.Enabled == nil {
 		return !a.Os().DefaultDisabled
diff --git a/android/prebuilt_etc.go b/android/prebuilt_etc.go
new file mode 100644
index 0000000..fee2c49
--- /dev/null
+++ b/android/prebuilt_etc.go
@@ -0,0 +1,91 @@
+// Copyright 2016 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 android
+
+import (
+	"fmt"
+	"io"
+)
+
+// prebuilt_etc is for prebuilts that will be installed to
+// <partition>/etc/<subdir>
+
+func init() {
+	RegisterModuleType("prebuilt_etc", PrebuiltEtcFactory)
+}
+
+type prebuiltEtcProperties struct {
+	// Source file of this prebuilt.
+	Srcs []string `android:"arch_variant"`
+
+	// optional subdirectory under which this file is installed into
+	Sub_dir *string `android:"arch_variant"`
+}
+
+type prebuiltEtc struct {
+	ModuleBase
+	prebuilt Prebuilt
+
+	properties prebuiltEtcProperties
+
+	sourceFilePath Path
+	installDirPath OutputPath
+}
+
+func (p *prebuiltEtc) Prebuilt() *Prebuilt {
+	return &p.prebuilt
+}
+
+func (p *prebuiltEtc) DepsMutator(ctx BottomUpMutatorContext) {
+	if len(p.properties.Srcs) == 0 {
+		ctx.PropertyErrorf("srcs", "missing prebuilt source file")
+	}
+
+	if len(p.properties.Srcs) > 1 {
+		ctx.PropertyErrorf("srcs", "multiple prebuilt source files")
+	}
+
+	// To support ":modulename" in src
+	ExtractSourceDeps(ctx, &(p.properties.Srcs)[0])
+}
+
+func (p *prebuiltEtc) GenerateAndroidBuildActions(ctx ModuleContext) {
+	p.sourceFilePath = ctx.ExpandSource(p.properties.Srcs[0], "srcs")
+	p.installDirPath = PathForModuleInstall(ctx, "etc", String(p.properties.Sub_dir))
+}
+
+func (p *prebuiltEtc) AndroidMk() AndroidMkData {
+	return AndroidMkData{
+		Custom: func(w io.Writer, name, prefix, moduleDir string, data AndroidMkData) {
+			fmt.Fprintln(w, "\ninclude $(CLEAR_VARS)")
+			fmt.Fprintln(w, "LOCAL_PATH :=", moduleDir)
+			fmt.Fprintln(w, "LOCAL_MODULE :=", name)
+			fmt.Fprintln(w, "LOCAL_MODULE_CLASS := ETC")
+			fmt.Fprintln(w, "LOCAL_MODULE_TAGS := optional")
+			fmt.Fprintln(w, "LOCAL_PREBUILT_MODULE_FILE :=", p.sourceFilePath.String())
+			fmt.Fprintln(w, "LOCAL_MODULE_PATH :=", "$(OUT_DIR)/"+p.installDirPath.RelPathString())
+			fmt.Fprintln(w, "include $(BUILD_PREBUILT)")
+		},
+	}
+}
+
+func PrebuiltEtcFactory() Module {
+	module := &prebuiltEtc{}
+	module.AddProperties(&module.properties)
+
+	InitPrebuiltModule(module, &(module.properties.Srcs))
+	InitAndroidModule(module)
+	return module
+}
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 0224da5..0700487 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -306,6 +306,20 @@
 			default:
 				panic(fmt.Errorf("unknown dependency %q for %q", otherName, ctx.ModuleName()))
 			}
+		case SdkLibraryDependency:
+			switch tag {
+			case libTag:
+				sdkVersion := String(j.properties.Sdk_version)
+				linkType := javaSdk
+				if strings.HasPrefix(sdkVersion, "system_") || strings.HasPrefix(sdkVersion, "test_") {
+					linkType = javaSystem
+				} else if sdkVersion == "" {
+					linkType = javaPlatform
+				}
+				deps.classpath = append(deps.classpath, dep.HeaderJars(linkType)...)
+			default:
+				ctx.ModuleErrorf("dependency on java_sdk_library %q can only be in libs", otherName)
+			}
 		case android.SourceFileProducer:
 			switch tag {
 			case libTag:
diff --git a/java/java.go b/java/java.go
index 277cdaf..8c23124 100644
--- a/java/java.go
+++ b/java/java.go
@@ -292,6 +292,10 @@
 	AidlIncludeDirs() android.Paths
 }
 
+type SdkLibraryDependency interface {
+	HeaderJars(linkType linkType) android.Paths
+}
+
 type SrcDependency interface {
 	CompiledSrcs() android.Paths
 	CompiledSrcJars() android.Paths
@@ -729,6 +733,13 @@
 			}
 
 			deps.aidlIncludeDirs = append(deps.aidlIncludeDirs, dep.AidlIncludeDirs()...)
+		case SdkLibraryDependency:
+			switch tag {
+			case libTag:
+				deps.classpath = append(deps.classpath, dep.HeaderJars(getLinkType(j, ctx.ModuleName()))...)
+			default:
+				ctx.ModuleErrorf("dependency on java_sdk_library %q can only be in libs", otherName)
+			}
 		case android.SourceFileProducer:
 			switch tag {
 			case libTag:
diff --git a/java/java_test.go b/java/java_test.go
index d4f2be1..de514e0 100644
--- a/java/java_test.go
+++ b/java/java_test.go
@@ -83,9 +83,13 @@
 	ctx.RegisterModuleType("droiddoc", android.ModuleFactoryAdaptor(DroiddocFactory))
 	ctx.RegisterModuleType("droiddoc_host", android.ModuleFactoryAdaptor(DroiddocHostFactory))
 	ctx.RegisterModuleType("droiddoc_template", android.ModuleFactoryAdaptor(DroiddocTemplateFactory))
+	ctx.RegisterModuleType("java_sdk_library", android.ModuleFactoryAdaptor(sdkLibraryFactory))
 	ctx.PreArchMutators(android.RegisterPrebuiltsPreArchMutators)
 	ctx.PreArchMutators(android.RegisterPrebuiltsPostDepsMutators)
 	ctx.PreArchMutators(android.RegisterDefaultsPreArchMutators)
+	ctx.PreArchMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.TopDown("java_sdk_library", sdkLibraryMutator).Parallel()
+	})
 	ctx.RegisterPreSingletonType("overlay", android.SingletonFactoryAdaptor(OverlaySingletonFactory))
 	ctx.Register()
 
@@ -998,3 +1002,60 @@
 		t.Errorf(`foo inputs %v != ["java-fg/c.java"]`, javac.Inputs)
 	}
 }
+
+func TestJavaSdkLibrary(t *testing.T) {
+	ctx := testJava(t, `
+		droiddoc_template {
+			name: "droiddoc-templates-sdk",
+			path: ".",
+		}
+		java_library {
+			name: "conscrypt",
+		}
+		java_library {
+			name: "bouncycastle",
+		}
+		java_sdk_library {
+			name: "foo",
+			srcs: ["a.java", "b.java"],
+			api_packages: ["foo"],
+		}
+		java_sdk_library {
+			name: "bar",
+			srcs: ["a.java", "b.java"],
+			api_packages: ["bar"],
+		}
+		java_library {
+			name: "baz",
+			srcs: ["c.java"],
+			libs: ["foo", "bar"],
+			sdk_version: "system_current",
+		}
+		`)
+
+	// check the existence of the internal modules
+	ctx.ModuleForTests("foo", "android_common")
+	ctx.ModuleForTests("foo"+sdkStubsLibrarySuffix, "android_common")
+	ctx.ModuleForTests("foo"+sdkStubsLibrarySuffix+sdkSystemApiSuffix, "android_common")
+	ctx.ModuleForTests("foo"+sdkDocsSuffix, "android_common")
+	ctx.ModuleForTests("foo"+sdkDocsSuffix+sdkSystemApiSuffix, "android_common")
+	ctx.ModuleForTests("foo"+sdkImplLibrarySuffix, "android_common")
+	ctx.ModuleForTests("foo"+sdkXmlFileSuffix, "")
+
+	bazJavac := ctx.ModuleForTests("baz", "android_common").Rule("javac")
+	// tests if baz is actually linked to the stubs lib
+	if !strings.Contains(bazJavac.Args["classpath"], "foo.stubs.system.jar") {
+		t.Errorf("baz javac classpath %v does not contain %q", bazJavac.Args["classpath"],
+			"foo.stubs.system.jar")
+	}
+	// ... and not to the impl lib
+	if strings.Contains(bazJavac.Args["classpath"], "foo.impl.jar") {
+		t.Errorf("baz javac classpath %v should not contain %q", bazJavac.Args["classpath"],
+			"foo.impl.jar")
+	}
+	// test if baz is not linked to the system variant of foo
+	if strings.Contains(bazJavac.Args["classpath"], "foo.stubs.jar") {
+		t.Errorf("baz javac classpath %v should not contain %q", bazJavac.Args["classpath"],
+			"foo.stubs.jar")
+	}
+}
diff --git a/java/sdk_library.go b/java/sdk_library.go
new file mode 100644
index 0000000..301ec61
--- /dev/null
+++ b/java/sdk_library.go
@@ -0,0 +1,425 @@
+// Copyright 2018 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"
+	"android/soong/genrule"
+	"fmt"
+	"path"
+	"strings"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+)
+
+var (
+	sdkStubsLibrarySuffix = ".stubs"
+	sdkSystemApiSuffix    = ".system"
+	sdkDocsSuffix         = ".docs"
+	sdkImplLibrarySuffix  = ".impl"
+	sdkXmlFileSuffix      = ".xml"
+)
+
+type stubsLibraryDependencyTag struct {
+	blueprint.BaseDependencyTag
+	name string
+}
+
+var (
+	publicApiStubsTag = dependencyTag{name: "public"}
+	systemApiStubsTag = dependencyTag{name: "system"}
+)
+
+// java_sdk_library is to make a Java library that implements optional platform APIs to apps.
+// It is actually a wrapper of several modules: 1) stubs library that clients are linked against
+// to, 2) droiddoc module that internally generates API stubs source files, 3) the real runtime
+// shared library that implements the APIs, and 4) XML file for adding the runtime lib to the
+// classpath at runtime if requested via <uses-library>.
+//
+// TODO: these are big features that are currently missing
+// 1) check for API consistency
+// 2) install stubs libs as the dist artifacts
+// 3) ensuring that apps have appropriate <uses-library> tag
+// 4) disallowing linking to the runtime shared lib
+// 5) HTML generation
+
+func init() {
+	android.RegisterModuleType("java_sdk_library", sdkLibraryFactory)
+
+	android.PreArchMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.TopDown("java_sdk_library", sdkLibraryMutator).Parallel()
+	})
+}
+
+type sdkLibraryProperties struct {
+	// list of source files used to compile the Java module.  May be .java, .logtags, .proto,
+	// or .aidl files.
+	Srcs []string `android:"arch_variant"`
+
+	// list of of java libraries that will be in the classpath
+	Libs []string `android:"arch_variant"`
+
+	// list of java libraries that will be compiled into the resulting runtime jar.
+	// These libraries are not compiled into the stubs jar.
+	Static_libs []string `android:"arch_variant"`
+
+	// list of package names that will be documented and publicized as API
+	Api_packages []string
+
+	// TODO: determines whether to create HTML doc or not
+	//Html_doc *bool
+}
+
+type sdkLibrary struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	properties sdkLibraryProperties
+
+	publicApiStubsPath android.Paths
+	systemApiStubsPath android.Paths
+}
+
+func (module *sdkLibrary) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// Add dependencies to the stubs library
+	ctx.AddDependency(ctx.Module(), publicApiStubsTag, module.stubsName(false))
+	ctx.AddDependency(ctx.Module(), systemApiStubsTag, module.stubsName(true))
+}
+
+func (module *sdkLibrary) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Record the paths to the header jars of the stubs library.
+	// When this java_sdk_library is dependened from others via "libs" property,
+	// the recorded paths will be returned depending on the link type of the caller.
+	ctx.VisitDirectDeps(func(to android.Module) {
+		otherName := ctx.OtherModuleName(to)
+		tag := ctx.OtherModuleDependencyTag(to)
+
+		if stubs, ok := to.(Dependency); ok {
+			switch tag {
+			case publicApiStubsTag:
+				module.publicApiStubsPath = stubs.HeaderJars()
+			case systemApiStubsTag:
+				module.systemApiStubsPath = stubs.HeaderJars()
+			default:
+				ctx.ModuleErrorf("depends on module %q of unknown tag %q", otherName, tag)
+			}
+		}
+	})
+}
+
+// Module name of the stubs library
+func (module *sdkLibrary) stubsName(forSystemApi bool) string {
+	stubsName := module.BaseModuleName() + sdkStubsLibrarySuffix
+	if forSystemApi {
+		stubsName = stubsName + sdkSystemApiSuffix
+	}
+	return stubsName
+}
+
+// Module name of the docs
+func (module *sdkLibrary) docsName(forSystemApi bool) string {
+	docsName := module.BaseModuleName() + sdkDocsSuffix
+	if forSystemApi {
+		docsName = docsName + sdkSystemApiSuffix
+	}
+	return docsName
+}
+
+// Module name of the runtime implementation library
+func (module *sdkLibrary) implName() string {
+	return module.BaseModuleName() + sdkImplLibrarySuffix
+}
+
+// File path to the runtime implementation library
+func (module *sdkLibrary) implPath() string {
+	partition := "system"
+	if module.SocSpecific() {
+		partition = "vendor"
+	} else if module.DeviceSpecific() {
+		partition = "odm"
+	} else if module.ProductSpecific() {
+		partition = "product"
+	}
+	return "/" + partition + "/framework/" + module.implName() + ".jar"
+}
+
+// Module name of the XML file for the lib
+func (module *sdkLibrary) xmlFileName() string {
+	return module.BaseModuleName() + sdkXmlFileSuffix
+}
+
+// SDK version that the stubs library is built against. Note that this is always
+// *current. Older stubs library built with a numberd SDK version is created from
+// the prebuilt jar.
+func (module *sdkLibrary) sdkVersion(forSystemApi bool) string {
+	if forSystemApi {
+		return "system_current"
+	} else {
+		return "current"
+	}
+}
+
+// $(INTERNAL_PLATFORM_<apiTagName>_API_FILE) points to the generated
+// api file for the current source
+// TODO: remove this when apicheck is done in soong
+func (module *sdkLibrary) apiTagName(forSystemApi bool) string {
+	apiTagName := strings.Replace(strings.ToUpper(module.BaseModuleName()), ".", "_", -1)
+	if forSystemApi {
+		apiTagName = apiTagName + "_SYSTEM"
+	}
+	return apiTagName
+}
+
+// returns the path (relative to this module) to the API txt file. Files are located
+// ./<api_dir>/<api_level>.txt where <api_level> is either current, system-current, removed,
+// or system-removed.
+func (module *sdkLibrary) apiFilePath(apiLevel string, forSystemApi bool) string {
+	apiDir := "api"
+	apiFile := apiLevel
+	if forSystemApi {
+		apiFile = "system-" + apiFile
+	}
+	apiFile = apiFile + ".txt"
+
+	return path.Join(apiDir, apiFile)
+}
+
+// Creates a static java library that has API stubs
+func (module *sdkLibrary) createStubsLibrary(mctx android.TopDownMutatorContext, forSystemApi bool) {
+	props := struct {
+		Name              *string
+		Srcs              []string
+		Sdk_version       *string
+		Soc_specific      *bool
+		Device_specific   *bool
+		Product_specific  *bool
+		Product_variables struct {
+			Unbundled_build struct {
+				Enabled *bool
+			}
+		}
+	}{}
+
+	props.Name = proptools.StringPtr(module.stubsName(forSystemApi))
+	// sources are generated from the droiddoc
+	props.Srcs = []string{":" + module.docsName(forSystemApi)}
+	props.Sdk_version = proptools.StringPtr(module.sdkVersion(forSystemApi))
+	// Unbundled apps will use the prebult one from /prebuilts/sdk
+	props.Product_variables.Unbundled_build.Enabled = proptools.BoolPtr(false)
+
+	if module.SocSpecific() {
+		props.Soc_specific = proptools.BoolPtr(true)
+	} else if module.DeviceSpecific() {
+		props.Device_specific = proptools.BoolPtr(true)
+	} else if module.ProductSpecific() {
+		props.Product_specific = proptools.BoolPtr(true)
+	}
+
+	mctx.CreateModule(android.ModuleFactoryAdaptor(LibraryFactory(false)), &props)
+}
+
+// Creates a droiddoc module that creates stubs source files from the given full source
+// files
+func (module *sdkLibrary) createDocs(mctx android.TopDownMutatorContext, forSystemApi bool) {
+	props := struct {
+		Name                    *string
+		Srcs                    []string
+		Custom_template         *string
+		Installable             *bool
+		Srcs_lib                *string
+		Srcs_lib_whitelist_dirs []string
+		Srcs_lib_whitelist_pkgs []string
+		Libs                    []string
+		Args                    *string
+		Api_tag_name            *string
+		Api_filename            *string
+		Removed_api_filename    *string
+	}{}
+
+	props.Name = proptools.StringPtr(module.docsName(forSystemApi))
+	props.Srcs = module.properties.Srcs
+	props.Custom_template = proptools.StringPtr("droiddoc-templates-sdk")
+	props.Installable = proptools.BoolPtr(false)
+	props.Libs = module.properties.Libs
+
+	droiddocArgs := " -hide 110 -hide 111 -hide 113 -hide 121 -hide 125 -hide 126 -hide 127 -hide 128" +
+		" -stubpackages " + strings.Join(module.properties.Api_packages, ":") +
+		" -nodocs"
+	if forSystemApi {
+		droiddocArgs = droiddocArgs + " -showAnnotation android.annotation.SystemApi"
+	}
+	props.Args = proptools.StringPtr(droiddocArgs)
+
+	// List of APIs identified from the provided source files are created. They are later
+	// compared against to the not-yet-released (a.k.a current) list of APIs and to the
+	// last-released (a.k.a numbered) list of API.
+	// TODO: If any incompatible change is detected, break the build
+	currentApiFileName := "current.txt"
+	removedApiFileName := "removed.txt"
+	if forSystemApi {
+		currentApiFileName = "system-" + currentApiFileName
+		removedApiFileName = "system-" + removedApiFileName
+	}
+	currentApiFileName = path.Join("api", currentApiFileName)
+	removedApiFileName = path.Join("api", removedApiFileName)
+	props.Api_tag_name = proptools.StringPtr(module.apiTagName(forSystemApi))
+	// Note: the exact names of these two are not important because they are always
+	// referenced by the make variable $(INTERNAL_PLATFORM_<TAG_NAME>_API_FILE)
+	props.Api_filename = proptools.StringPtr(currentApiFileName)
+	props.Removed_api_filename = proptools.StringPtr(removedApiFileName)
+
+	// Includes the main framework source to ensure that doclava has access to the
+	// visibility information for the base classes of the mock classes. Without it
+	// otherwise hidden methods could be visible.
+	// TODO: remove the need for this
+	props.Srcs_lib = proptools.StringPtr("framework")
+	props.Srcs_lib_whitelist_dirs = []string{"core/java"}
+	props.Srcs_lib_whitelist_pkgs = []string{"android"}
+	// These libs are required by doclava to parse the sources from framework.
+	// If we don't add them to the classpath, errors messages are generated by doclava,
+	// though they don't break the build.
+	props.Libs = append(props.Libs, "conscrypt", "bouncycastle", "okhttp")
+
+	mctx.CreateModule(android.ModuleFactoryAdaptor(DroiddocFactory), &props)
+}
+
+// Creates the runtime library. This is not directly linkable from other modules.
+func (module *sdkLibrary) createImplLibrary(mctx android.TopDownMutatorContext) {
+	props := struct {
+		Name             *string
+		Srcs             []string
+		Libs             []string
+		Static_libs      []string
+		Soc_specific     *bool
+		Device_specific  *bool
+		Product_specific *bool
+		Required         []string
+	}{}
+
+	props.Name = proptools.StringPtr(module.implName())
+	props.Srcs = module.properties.Srcs
+	props.Libs = module.properties.Libs
+	props.Static_libs = module.properties.Static_libs
+	// XML file is installed along with the impl lib
+	props.Required = []string{module.xmlFileName()}
+
+	if module.SocSpecific() {
+		props.Soc_specific = proptools.BoolPtr(true)
+	} else if module.DeviceSpecific() {
+		props.Device_specific = proptools.BoolPtr(true)
+	} else if module.ProductSpecific() {
+		props.Product_specific = proptools.BoolPtr(true)
+	}
+
+	mctx.CreateModule(android.ModuleFactoryAdaptor(LibraryFactory(true)), &props)
+}
+
+// Creates the xml file that publicizes the runtime library
+func (module *sdkLibrary) createXmlFile(mctx android.TopDownMutatorContext) {
+	template := `
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2018 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.
+-->
+
+<permissions>
+    <library name="%s" file="%s"/>
+</permissions>
+`
+	// genrule to generate the xml file content from the template above
+	// TODO: preserve newlines in the generate xml file. Newlines are being squashed
+	// in the ninja file. Do we need to have an external tool for this?
+	xmlContent := fmt.Sprintf(template, module.BaseModuleName(), module.implPath())
+	genruleProps := struct {
+		Name *string
+		Cmd  *string
+		Out  []string
+	}{}
+	genruleProps.Name = proptools.StringPtr(module.xmlFileName() + "-gen")
+	genruleProps.Cmd = proptools.StringPtr("echo '" + xmlContent + "' > $(out)")
+	genruleProps.Out = []string{module.xmlFileName()}
+	mctx.CreateModule(android.ModuleFactoryAdaptor(genrule.GenRuleFactory), &genruleProps)
+
+	// creates a prebuilt_etc module to actually place the xml file under
+	// <partition>/etc/permissions
+	etcProps := struct {
+		Name             *string
+		Srcs             []string
+		Sub_dir          *string
+		Soc_specific     *bool
+		Device_specific  *bool
+		Product_specific *bool
+	}{}
+	etcProps.Name = proptools.StringPtr(module.xmlFileName())
+	etcProps.Srcs = []string{":" + module.xmlFileName() + "-gen"}
+	etcProps.Sub_dir = proptools.StringPtr("permissions")
+	if module.SocSpecific() {
+		etcProps.Soc_specific = proptools.BoolPtr(true)
+	} else if module.DeviceSpecific() {
+		etcProps.Device_specific = proptools.BoolPtr(true)
+	} else if module.ProductSpecific() {
+		etcProps.Product_specific = proptools.BoolPtr(true)
+	}
+	mctx.CreateModule(android.ModuleFactoryAdaptor(android.PrebuiltEtcFactory), &etcProps)
+}
+
+// to satisfy SdkLibraryDependency interface
+func (module *sdkLibrary) HeaderJars(linkType linkType) android.Paths {
+	// This module is just a wrapper for the stubs.
+	if linkType == javaSystem || linkType == javaPlatform {
+		return module.systemApiStubsPath
+	} else {
+		return module.publicApiStubsPath
+	}
+}
+
+// For a java_sdk_library module, create internal modules for stubs, docs,
+// runtime libs and xml file. If requested, the stubs and docs are created twice
+// once for public API level and once for system API level
+func sdkLibraryMutator(mctx android.TopDownMutatorContext) {
+	if module, ok := mctx.Module().(*sdkLibrary); ok {
+		// for public API stubs
+		module.createStubsLibrary(mctx, false)
+		module.createDocs(mctx, false)
+
+		// for system API stubs
+		module.createStubsLibrary(mctx, true)
+		module.createDocs(mctx, true)
+
+		// for runtime
+		module.createXmlFile(mctx)
+		module.createImplLibrary(mctx)
+	}
+}
+
+func sdkLibraryFactory() android.Module {
+	module := &sdkLibrary{}
+	module.AddProperties(&module.properties)
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibCommon)
+	android.InitDefaultableModule(module)
+	return module
+}