cc/ndk_library.go - platform/build/soong - Git at Google

 // 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 cc

 import (
 	"fmt"
 	"strings"
 	"sync"

 	"github.com/google/blueprint"

 	"android/soong/android"
 )

 func init() {
 	pctx.HostBinToolVariable("ndkStubGenerator", "ndkstubgen")
 	pctx.HostBinToolVariable("ndk_api_coverage_parser", "ndk_api_coverage_parser")
 }

 var (
 	genStubSrc = pctx.AndroidStaticRule("genStubSrc",
 		blueprint.RuleParams{
 			Command: "$ndkStubGenerator --arch $arch --api $apiLevel " +
 				"--api-map $apiMap $flags $in $out",
 			CommandDeps: []string{"$ndkStubGenerator"},
 		}, "arch", "apiLevel", "apiMap", "flags")

 	parseNdkApiRule = pctx.AndroidStaticRule("parseNdkApiRule",
 		blueprint.RuleParams{
 			Command:     "$ndk_api_coverage_parser $in $out --api-map $apiMap",
 			CommandDeps: []string{"$ndk_api_coverage_parser"},
 		}, "apiMap")

 	ndkLibrarySuffix = ".ndk"

 	ndkKnownLibsKey = android.NewOnceKey("ndkKnownLibsKey")
 	// protects ndkKnownLibs writes during parallel BeginMutator.
 	ndkKnownLibsLock sync.Mutex
 )

 // The First_version and Unversioned_until properties of this struct should not
 // be used directly, but rather through the ApiLevel returning methods
 // firstVersion() and unversionedUntil().

 // Creates a stub shared library based on the provided version file.
 //
 // Example:
 //
 // ndk_library {
 //     name: "libfoo",
 //     symbol_file: "libfoo.map.txt",
 //     first_version: "9",
 // }
 //
 type libraryProperties struct {
 	// Relative path to the symbol map.
 	// An example file can be seen here: TODO(danalbert): Make an example.
 	Symbol_file *string

 	// The first API level a library was available. A library will be generated
 	// for every API level beginning with this one.
 	First_version *string

 	// The first API level that library should have the version script applied.
 	// This defaults to the value of first_version, and should almost never be
 	// used. This is only needed to work around platform bugs like
 	// https://github.com/android-ndk/ndk/issues/265.
 	Unversioned_until *string

 	// True if this API is not yet ready to be shipped in the NDK. It will be
 	// available in the platform for testing, but will be excluded from the
 	// sysroot provided to the NDK proper.
 	Draft bool
 }

 type stubDecorator struct {
 	*libraryDecorator

 	properties libraryProperties

 	versionScriptPath     android.ModuleGenPath
 	parsedCoverageXmlPath android.ModuleOutPath
 	installPath           android.Path

 	apiLevel         android.ApiLevel
 	firstVersion     android.ApiLevel
 	unversionedUntil android.ApiLevel
 }

 var _ versionedInterface = (*stubDecorator)(nil)

 func shouldUseVersionScript(ctx BaseModuleContext, stub *stubDecorator) bool {
 	return stub.apiLevel.GreaterThanOrEqualTo(stub.unversionedUntil)
 }

 func (stub *stubDecorator) implementationModuleName(name string) string {
 	return strings.TrimSuffix(name, ndkLibrarySuffix)
 }

 func ndkLibraryVersions(ctx android.BaseMutatorContext, from android.ApiLevel) []string {
 	var versions []android.ApiLevel
 	versionStrs := []string{}
 	for _, version := range ctx.Config().AllSupportedApiLevels() {
 		if version.GreaterThanOrEqualTo(from) {
 			versions = append(versions, version)
 			versionStrs = append(versionStrs, version.String())
 		}
 	}
 	versionStrs = append(versionStrs, android.FutureApiLevel.String())

 	return versionStrs
 }

 func (this *stubDecorator) stubsVersions(ctx android.BaseMutatorContext) []string {
 	if !ctx.Module().Enabled() {
 		return nil
 	}
 	firstVersion, err := nativeApiLevelFromUser(ctx,
 		String(this.properties.First_version))
 	if err != nil {
 		ctx.PropertyErrorf("first_version", err.Error())
 		return nil
 	}
 	return ndkLibraryVersions(ctx, firstVersion)
 }

 func (this *stubDecorator) initializeProperties(ctx BaseModuleContext) bool {
 	this.apiLevel = nativeApiLevelOrPanic(ctx, this.stubsVersion())

 	var err error
 	this.firstVersion, err = nativeApiLevelFromUser(ctx,
 		String(this.properties.First_version))
 	if err != nil {
 		ctx.PropertyErrorf("first_version", err.Error())
 		return false
 	}

 	this.unversionedUntil, err = nativeApiLevelFromUserWithDefault(ctx,
 		String(this.properties.Unversioned_until), "minimum")
 	if err != nil {
 		ctx.PropertyErrorf("unversioned_until", err.Error())
 		return false
 	}

 	return true
 }

 func getNDKKnownLibs(config android.Config) *[]string {
 	return config.Once(ndkKnownLibsKey, func() interface{} {
 		return &[]string{}
 	}).(*[]string)
 }

 func (c *stubDecorator) compilerInit(ctx BaseModuleContext) {
 	c.baseCompiler.compilerInit(ctx)

 	name := ctx.baseModuleName()
 	if strings.HasSuffix(name, ndkLibrarySuffix) {
 		ctx.PropertyErrorf("name", "Do not append %q manually, just use the base name", ndkLibrarySuffix)
 	}

 	ndkKnownLibsLock.Lock()
 	defer ndkKnownLibsLock.Unlock()
 	ndkKnownLibs := getNDKKnownLibs(ctx.Config())
 	for _, lib := range *ndkKnownLibs {
 		if lib == name {
 			return
 		}
 	}
 	*ndkKnownLibs = append(*ndkKnownLibs, name)
 }

 func addStubLibraryCompilerFlags(flags Flags) Flags {
 	flags.Global.CFlags = append(flags.Global.CFlags,
 		// We're knowingly doing some otherwise unsightly things with builtin
 		// functions here. We're just generating stub libraries, so ignore it.
 		"-Wno-incompatible-library-redeclaration",
 		"-Wno-incomplete-setjmp-declaration",
 		"-Wno-builtin-requires-header",
 		"-Wno-invalid-noreturn",
 		"-Wall",
 		"-Werror",
 		// These libraries aren't actually used. Don't worry about unwinding
 		// (avoids the need to link an unwinder into a fake library).
 		"-fno-unwind-tables",
 	)
 	// All symbols in the stubs library should be visible.
 	if inList("-fvisibility=hidden", flags.Local.CFlags) {
 		flags.Local.CFlags = append(flags.Local.CFlags, "-fvisibility=default")
 	}
 	return flags
 }

 func (stub *stubDecorator) compilerFlags(ctx ModuleContext, flags Flags, deps PathDeps) Flags {
 	flags = stub.baseCompiler.compilerFlags(ctx, flags, deps)
 	return addStubLibraryCompilerFlags(flags)
 }

 func compileStubLibrary(ctx ModuleContext, flags Flags, symbolFile, apiLevel, genstubFlags string) (Objects, android.ModuleGenPath) {
 	arch := ctx.Arch().ArchType.String()

 	stubSrcPath := android.PathForModuleGen(ctx, "stub.c")
 	versionScriptPath := android.PathForModuleGen(ctx, "stub.map")
 	symbolFilePath := android.PathForModuleSrc(ctx, symbolFile)
 	apiLevelsJson := android.GetApiLevelsJson(ctx)
 	ctx.Build(pctx, android.BuildParams{
 		Rule:        genStubSrc,
 		Description: "generate stubs " + symbolFilePath.Rel(),
 		Outputs:     []android.WritablePath{stubSrcPath, versionScriptPath},
 		Input:       symbolFilePath,
 		Implicits:   []android.Path{apiLevelsJson},
 		Args: map[string]string{
 			"arch":     arch,
 			"apiLevel": apiLevel,
 			"apiMap":   apiLevelsJson.String(),
 			"flags":    genstubFlags,
 		},
 	})

 	subdir := ""
 	srcs := []android.Path{stubSrcPath}
 	return compileObjs(ctx, flagsToBuilderFlags(flags), subdir, srcs, nil, nil), versionScriptPath
 }

 func parseSymbolFileForCoverage(ctx ModuleContext, symbolFile string) android.ModuleOutPath {
 	apiLevelsJson := android.GetApiLevelsJson(ctx)
 	symbolFilePath := android.PathForModuleSrc(ctx, symbolFile)
 	outputFileName := strings.Split(symbolFilePath.Base(), ".")[0]
 	parsedApiCoveragePath := android.PathForModuleOut(ctx, outputFileName+".xml")
 	ctx.Build(pctx, android.BuildParams{
 		Rule:        parseNdkApiRule,
 		Description: "parse ndk api symbol file for api coverage: " + symbolFilePath.Rel(),
 		Outputs:     []android.WritablePath{parsedApiCoveragePath},
 		Input:       symbolFilePath,
 		Implicits:   []android.Path{apiLevelsJson},
 		Args: map[string]string{
 			"apiMap": apiLevelsJson.String(),
 		},
 	})
 	return parsedApiCoveragePath
 }

 func (c *stubDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) Objects {
 	if !strings.HasSuffix(String(c.properties.Symbol_file), ".map.txt") {
 		ctx.PropertyErrorf("symbol_file", "must end with .map.txt")
 	}

 	if !c.buildStubs() {
 		// NDK libraries have no implementation variant, nothing to do
 		return Objects{}
 	}

 	if !c.initializeProperties(ctx) {
 		// Emits its own errors, so we don't need to.
 		return Objects{}
 	}

 	symbolFile := String(c.properties.Symbol_file)
 	objs, versionScript := compileStubLibrary(ctx, flags, symbolFile,
 		c.apiLevel.String(), "")
 	c.versionScriptPath = versionScript
 	if c.apiLevel.IsCurrent() && ctx.PrimaryArch() {
 		c.parsedCoverageXmlPath = parseSymbolFileForCoverage(ctx, symbolFile)
 	}
 	return objs
 }

 func (linker *stubDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
 	return Deps{}
 }

 func (linker *stubDecorator) Name(name string) string {
 	return name + ndkLibrarySuffix
 }

 func (stub *stubDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
 	stub.libraryDecorator.libName = ctx.baseModuleName()
 	return stub.libraryDecorator.linkerFlags(ctx, flags)
 }

 func (stub *stubDecorator) link(ctx ModuleContext, flags Flags, deps PathDeps,
 	objs Objects) android.Path {

 	if !stub.buildStubs() {
 		// NDK libraries have no implementation variant, nothing to do
 		return nil
 	}

 	if shouldUseVersionScript(ctx, stub) {
 		linkerScriptFlag := "-Wl,--version-script," + stub.versionScriptPath.String()
 		flags.Local.LdFlags = append(flags.Local.LdFlags, linkerScriptFlag)
 		flags.LdFlagsDeps = append(flags.LdFlagsDeps, stub.versionScriptPath)
 	}

 	stub.libraryDecorator.skipAPIDefine = true
 	return stub.libraryDecorator.link(ctx, flags, deps, objs)
 }

 func (stub *stubDecorator) nativeCoverage() bool {
 	return false
 }

 func (stub *stubDecorator) install(ctx ModuleContext, path android.Path) {
 	arch := ctx.Target().Arch.ArchType.Name
 	// arm64 isn't actually a multilib toolchain, so unlike the other LP64
 	// architectures it's just installed to lib.
 	libDir := "lib"
 	if ctx.toolchain().Is64Bit() && arch != "arm64" {
 		libDir = "lib64"
 	}

 	installDir := getNdkInstallBase(ctx).Join(ctx, fmt.Sprintf(
 		"platforms/android-%s/arch-%s/usr/%s", stub.apiLevel, arch, libDir))
 	stub.installPath = ctx.InstallFile(installDir, path.Base(), path)
 }

 func newStubLibrary() *Module {
 	module, library := NewLibrary(android.DeviceSupported)
 	library.BuildOnlyShared()
 	module.stl = nil
 	module.sanitize = nil
 	library.disableStripping()

 	stub := &stubDecorator{
 		libraryDecorator: library,
 	}
 	module.compiler = stub
 	module.linker = stub
 	module.installer = stub
 	module.library = stub

 	module.Properties.AlwaysSdk = true
 	module.Properties.Sdk_version = StringPtr("current")

 	module.AddProperties(&stub.properties, &library.MutatedProperties)

 	return module
 }

 // ndk_library creates a library that exposes a stub implementation of functions
 // and variables for use at build time only.
 func NdkLibraryFactory() android.Module {
 	module := newStubLibrary()
 	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibBoth)
 	module.ModuleBase.EnableNativeBridgeSupportByDefault()
 	return module
 }
	// 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 cc

	import (
	"fmt"
	"strings"
	"sync"

	"github.com/google/blueprint"

	"android/soong/android"
	)

	func init() {
	pctx.HostBinToolVariable("ndkStubGenerator", "ndkstubgen")
	pctx.HostBinToolVariable("ndk_api_coverage_parser", "ndk_api_coverage_parser")
	}

	var (
	genStubSrc = pctx.AndroidStaticRule("genStubSrc",
	blueprint.RuleParams{
	Command: "$ndkStubGenerator --arch $arch --api $apiLevel " +
	"--api-map $apiMap $flags $in $out",
	CommandDeps: []string{"$ndkStubGenerator"},
	}, "arch", "apiLevel", "apiMap", "flags")

	parseNdkApiRule = pctx.AndroidStaticRule("parseNdkApiRule",
	blueprint.RuleParams{
	Command: "$ndk_api_coverage_parser $in $out --api-map $apiMap",
	CommandDeps: []string{"$ndk_api_coverage_parser"},
	}, "apiMap")

	ndkLibrarySuffix = ".ndk"

	ndkKnownLibsKey = android.NewOnceKey("ndkKnownLibsKey")
	// protects ndkKnownLibs writes during parallel BeginMutator.
	ndkKnownLibsLock sync.Mutex
	)

	// The First_version and Unversioned_until properties of this struct should not
	// be used directly, but rather through the ApiLevel returning methods
	// firstVersion() and unversionedUntil().

	// Creates a stub shared library based on the provided version file.
	//
	// Example:
	//
	// ndk_library {
	// name: "libfoo",
	// symbol_file: "libfoo.map.txt",
	// first_version: "9",
	// }
	//
	type libraryProperties struct {
	// Relative path to the symbol map.
	// An example file can be seen here: TODO(danalbert): Make an example.
	Symbol_file *string

	// The first API level a library was available. A library will be generated
	// for every API level beginning with this one.
	First_version *string

	// The first API level that library should have the version script applied.
	// This defaults to the value of first_version, and should almost never be
	// used. This is only needed to work around platform bugs like
	// https://github.com/android-ndk/ndk/issues/265.
	Unversioned_until *string

	// True if this API is not yet ready to be shipped in the NDK. It will be
	// available in the platform for testing, but will be excluded from the
	// sysroot provided to the NDK proper.
	Draft bool
	}

	type stubDecorator struct {
	*libraryDecorator

	properties libraryProperties

	versionScriptPath android.ModuleGenPath
	parsedCoverageXmlPath android.ModuleOutPath
	installPath android.Path

	apiLevel android.ApiLevel
	firstVersion android.ApiLevel
	unversionedUntil android.ApiLevel
	}

	var _ versionedInterface = (*stubDecorator)(nil)

	func shouldUseVersionScript(ctx BaseModuleContext, stub *stubDecorator) bool {
	return stub.apiLevel.GreaterThanOrEqualTo(stub.unversionedUntil)
	}

	func (stub *stubDecorator) implementationModuleName(name string) string {
	return strings.TrimSuffix(name, ndkLibrarySuffix)
	}

	func ndkLibraryVersions(ctx android.BaseMutatorContext, from android.ApiLevel) []string {
	var versions []android.ApiLevel
	versionStrs := []string{}
	for _, version := range ctx.Config().AllSupportedApiLevels() {
	if version.GreaterThanOrEqualTo(from) {
	versions = append(versions, version)
	versionStrs = append(versionStrs, version.String())
	}
	}
	versionStrs = append(versionStrs, android.FutureApiLevel.String())

	return versionStrs
	}

	func (this *stubDecorator) stubsVersions(ctx android.BaseMutatorContext) []string {
	if !ctx.Module().Enabled() {
	return nil
	}
	firstVersion, err := nativeApiLevelFromUser(ctx,
	String(this.properties.First_version))
	if err != nil {
	ctx.PropertyErrorf("first_version", err.Error())
	return nil
	}
	return ndkLibraryVersions(ctx, firstVersion)
	}

	func (this *stubDecorator) initializeProperties(ctx BaseModuleContext) bool {
	this.apiLevel = nativeApiLevelOrPanic(ctx, this.stubsVersion())

	var err error
	this.firstVersion, err = nativeApiLevelFromUser(ctx,
	String(this.properties.First_version))
	if err != nil {
	ctx.PropertyErrorf("first_version", err.Error())
	return false
	}

	this.unversionedUntil, err = nativeApiLevelFromUserWithDefault(ctx,
	String(this.properties.Unversioned_until), "minimum")
	if err != nil {
	ctx.PropertyErrorf("unversioned_until", err.Error())
	return false
	}

	return true
	}

	func getNDKKnownLibs(config android.Config) *[]string {
	return config.Once(ndkKnownLibsKey, func() interface{} {
	return &[]string{}
	}).(*[]string)
	}

	func (c *stubDecorator) compilerInit(ctx BaseModuleContext) {
	c.baseCompiler.compilerInit(ctx)

	name := ctx.baseModuleName()
	if strings.HasSuffix(name, ndkLibrarySuffix) {
	ctx.PropertyErrorf("name", "Do not append %q manually, just use the base name", ndkLibrarySuffix)
	}

	ndkKnownLibsLock.Lock()
	defer ndkKnownLibsLock.Unlock()
	ndkKnownLibs := getNDKKnownLibs(ctx.Config())
	for _, lib := range *ndkKnownLibs {
	if lib == name {
	return
	}
	}
	ndkKnownLibs = append(ndkKnownLibs, name)
	}

	func addStubLibraryCompilerFlags(flags Flags) Flags {
	flags.Global.CFlags = append(flags.Global.CFlags,
	// We're knowingly doing some otherwise unsightly things with builtin
	// functions here. We're just generating stub libraries, so ignore it.
	"-Wno-incompatible-library-redeclaration",
	"-Wno-incomplete-setjmp-declaration",
	"-Wno-builtin-requires-header",
	"-Wno-invalid-noreturn",
	"-Wall",
	"-Werror",
	// These libraries aren't actually used. Don't worry about unwinding
	// (avoids the need to link an unwinder into a fake library).
	"-fno-unwind-tables",
	)
	// All symbols in the stubs library should be visible.
	if inList("-fvisibility=hidden", flags.Local.CFlags) {
	flags.Local.CFlags = append(flags.Local.CFlags, "-fvisibility=default")
	}
	return flags
	}

	func (stub *stubDecorator) compilerFlags(ctx ModuleContext, flags Flags, deps PathDeps) Flags {
	flags = stub.baseCompiler.compilerFlags(ctx, flags, deps)
	return addStubLibraryCompilerFlags(flags)
	}

	func compileStubLibrary(ctx ModuleContext, flags Flags, symbolFile, apiLevel, genstubFlags string) (Objects, android.ModuleGenPath) {
	arch := ctx.Arch().ArchType.String()

	stubSrcPath := android.PathForModuleGen(ctx, "stub.c")
	versionScriptPath := android.PathForModuleGen(ctx, "stub.map")
	symbolFilePath := android.PathForModuleSrc(ctx, symbolFile)
	apiLevelsJson := android.GetApiLevelsJson(ctx)
	ctx.Build(pctx, android.BuildParams{
	Rule: genStubSrc,
	Description: "generate stubs " + symbolFilePath.Rel(),
	Outputs: []android.WritablePath{stubSrcPath, versionScriptPath},
	Input: symbolFilePath,
	Implicits: []android.Path{apiLevelsJson},
	Args: map[string]string{
	"arch": arch,
	"apiLevel": apiLevel,
	"apiMap": apiLevelsJson.String(),
	"flags": genstubFlags,
	},
	})

	subdir := ""
	srcs := []android.Path{stubSrcPath}
	return compileObjs(ctx, flagsToBuilderFlags(flags), subdir, srcs, nil, nil), versionScriptPath
	}

	func parseSymbolFileForCoverage(ctx ModuleContext, symbolFile string) android.ModuleOutPath {
	apiLevelsJson := android.GetApiLevelsJson(ctx)
	symbolFilePath := android.PathForModuleSrc(ctx, symbolFile)
	outputFileName := strings.Split(symbolFilePath.Base(), ".")[0]
	parsedApiCoveragePath := android.PathForModuleOut(ctx, outputFileName+".xml")
	ctx.Build(pctx, android.BuildParams{
	Rule: parseNdkApiRule,
	Description: "parse ndk api symbol file for api coverage: " + symbolFilePath.Rel(),
	Outputs: []android.WritablePath{parsedApiCoveragePath},
	Input: symbolFilePath,
	Implicits: []android.Path{apiLevelsJson},
	Args: map[string]string{
	"apiMap": apiLevelsJson.String(),
	},
	})
	return parsedApiCoveragePath
	}

	func (c *stubDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) Objects {
	if !strings.HasSuffix(String(c.properties.Symbol_file), ".map.txt") {
	ctx.PropertyErrorf("symbol_file", "must end with .map.txt")
	}

	if !c.buildStubs() {
	// NDK libraries have no implementation variant, nothing to do
	return Objects{}
	}

	if !c.initializeProperties(ctx) {
	// Emits its own errors, so we don't need to.
	return Objects{}
	}

	symbolFile := String(c.properties.Symbol_file)
	objs, versionScript := compileStubLibrary(ctx, flags, symbolFile,
	c.apiLevel.String(), "")
	c.versionScriptPath = versionScript
	if c.apiLevel.IsCurrent() && ctx.PrimaryArch() {
	c.parsedCoverageXmlPath = parseSymbolFileForCoverage(ctx, symbolFile)
	}
	return objs
	}

	func (linker *stubDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
	return Deps{}
	}

	func (linker *stubDecorator) Name(name string) string {
	return name + ndkLibrarySuffix
	}

	func (stub *stubDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
	stub.libraryDecorator.libName = ctx.baseModuleName()
	return stub.libraryDecorator.linkerFlags(ctx, flags)
	}

	func (stub *stubDecorator) link(ctx ModuleContext, flags Flags, deps PathDeps,
	objs Objects) android.Path {

	if !stub.buildStubs() {
	// NDK libraries have no implementation variant, nothing to do
	return nil
	}

	if shouldUseVersionScript(ctx, stub) {
	linkerScriptFlag := "-Wl,--version-script," + stub.versionScriptPath.String()
	flags.Local.LdFlags = append(flags.Local.LdFlags, linkerScriptFlag)
	flags.LdFlagsDeps = append(flags.LdFlagsDeps, stub.versionScriptPath)
	}

	stub.libraryDecorator.skipAPIDefine = true
	return stub.libraryDecorator.link(ctx, flags, deps, objs)
	}

	func (stub *stubDecorator) nativeCoverage() bool {
	return false
	}

	func (stub *stubDecorator) install(ctx ModuleContext, path android.Path) {
	arch := ctx.Target().Arch.ArchType.Name
	// arm64 isn't actually a multilib toolchain, so unlike the other LP64
	// architectures it's just installed to lib.
	libDir := "lib"
	if ctx.toolchain().Is64Bit() && arch != "arm64" {
	libDir = "lib64"
	}

	installDir := getNdkInstallBase(ctx).Join(ctx, fmt.Sprintf(
	"platforms/android-%s/arch-%s/usr/%s", stub.apiLevel, arch, libDir))
	stub.installPath = ctx.InstallFile(installDir, path.Base(), path)
	}

	func newStubLibrary() *Module {
	module, library := NewLibrary(android.DeviceSupported)
	library.BuildOnlyShared()
	module.stl = nil
	module.sanitize = nil
	library.disableStripping()

	stub := &stubDecorator{
	libraryDecorator: library,
	}
	module.compiler = stub
	module.linker = stub
	module.installer = stub
	module.library = stub

	module.Properties.AlwaysSdk = true
	module.Properties.Sdk_version = StringPtr("current")

	module.AddProperties(&stub.properties, &library.MutatedProperties)

	return module
	}

	// ndk_library creates a library that exposes a stub implementation of functions
	// and variables for use at build time only.
	func NdkLibraryFactory() android.Module {
	module := newStubLibrary()
	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibBoth)
	module.ModuleBase.EnableNativeBridgeSupportByDefault()
	return module
	}