cc/ndk_library.go - SHIFTPHONES/android_build_soong - Gitiles

 // 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"
 	"strconv"
 	"strings"
 	"sync"

 	"github.com/google/blueprint"

 	"android/soong/android"
 )

 var (
 	toolPath = pctx.SourcePathVariable("toolPath", "build/soong/cc/gen_stub_libs.py")

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

 	ndkLibrarySuffix = ".ndk"

 	ndkPrebuiltSharedLibs = []string{
 		"aaudio",
 		"amidi",
 		"android",
 		"binder_ndk",
 		"c",
 		"camera2ndk",
 		"dl",
 		"EGL",
 		"GLESv1_CM",
 		"GLESv2",
 		"GLESv3",
 		"jnigraphics",
 		"log",
 		"mediandk",
 		"nativewindow",
 		"m",
 		"OpenMAXAL",
 		"OpenSLES",
 		"stdc++",
 		"sync",
 		"vulkan",
 		"z",
 	}
 	ndkPrebuiltSharedLibraries = addPrefix(append([]string(nil), ndkPrebuiltSharedLibs...), "lib")

 	// These libraries have migrated over to the new ndk_library, which is added
 	// as a variation dependency via depsMutator.
 	ndkMigratedLibs     = []string{}
 	ndkMigratedLibsLock sync.Mutex // protects ndkMigratedLibs writes during parallel BeginMutator
 )

 // 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

 	// Private property for use by the mutator that splits per-API level.
 	ApiLevel string `blueprint:"mutated"`

 	// 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
 	installPath       android.Path
 }

 // OMG GO
 func intMax(a int, b int) int {
 	if a > b {
 		return a
 	} else {
 		return b
 	}
 }

 func normalizeNdkApiLevel(ctx android.BaseContext, apiLevel string,
 	arch android.Arch) (string, error) {

 	if apiLevel == "current" {
 		return apiLevel, nil
 	}

 	minVersion := ctx.Config().MinSupportedSdkVersion()
 	firstArchVersions := map[android.ArchType]int{
 		android.Arm:    minVersion,
 		android.Arm64:  21,
 		android.Mips:   minVersion,
 		android.Mips64: 21,
 		android.X86:    minVersion,
 		android.X86_64: 21,
 	}

 	firstArchVersion, ok := firstArchVersions[arch.ArchType]
 	if !ok {
 		panic(fmt.Errorf("Arch %q not found in firstArchVersions", arch.ArchType))
 	}

 	if apiLevel == "minimum" {
 		return strconv.Itoa(firstArchVersion), nil
 	}

 	// If the NDK drops support for a platform version, we don't want to have to
 	// fix up every module that was using it as its SDK version. Clip to the
 	// supported version here instead.
 	version, err := strconv.Atoi(apiLevel)
 	if err != nil {
 		return "", fmt.Errorf("API level must be an integer (is %q)", apiLevel)
 	}
 	version = intMax(version, minVersion)

 	return strconv.Itoa(intMax(version, firstArchVersion)), nil
 }

 func getFirstGeneratedVersion(firstSupportedVersion string, platformVersion int) (int, error) {
 	if firstSupportedVersion == "current" {
 		return platformVersion + 1, nil
 	}

 	return strconv.Atoi(firstSupportedVersion)
 }

 func shouldUseVersionScript(ctx android.BaseContext, stub *stubDecorator) (bool, error) {
 	// unversioned_until is normally empty, in which case we should use the version script.
 	if String(stub.properties.Unversioned_until) == "" {
 		return true, nil
 	}

 	if String(stub.properties.Unversioned_until) == "current" {
 		if stub.properties.ApiLevel == "current" {
 			return true, nil
 		} else {
 			return false, nil
 		}
 	}

 	if stub.properties.ApiLevel == "current" {
 		return true, nil
 	}

 	unversionedUntil, err := android.ApiStrToNum(ctx, String(stub.properties.Unversioned_until))
 	if err != nil {
 		return true, err
 	}

 	version, err := android.ApiStrToNum(ctx, stub.properties.ApiLevel)
 	if err != nil {
 		return true, err
 	}

 	return version >= unversionedUntil, nil
 }

 func generateStubApiVariants(mctx android.BottomUpMutatorContext, c *stubDecorator) {
 	platformVersion := mctx.Config().PlatformSdkVersionInt()

 	firstSupportedVersion, err := normalizeNdkApiLevel(mctx, String(c.properties.First_version),
 		mctx.Arch())
 	if err != nil {
 		mctx.PropertyErrorf("first_version", err.Error())
 	}

 	firstGenVersion, err := getFirstGeneratedVersion(firstSupportedVersion, platformVersion)
 	if err != nil {
 		// In theory this is impossible because we've already run this through
 		// normalizeNdkApiLevel above.
 		mctx.PropertyErrorf("first_version", err.Error())
 	}

 	var versionStrs []string
 	for version := firstGenVersion; version <= platformVersion; version++ {
 		versionStrs = append(versionStrs, strconv.Itoa(version))
 	}
 	versionStrs = append(versionStrs, mctx.Config().PlatformVersionActiveCodenames()...)
 	versionStrs = append(versionStrs, "current")

 	modules := mctx.CreateVariations(versionStrs...)
 	for i, module := range modules {
 		module.(*Module).compiler.(*stubDecorator).properties.ApiLevel = versionStrs[i]
 	}
 }

 func ndkApiMutator(mctx android.BottomUpMutatorContext) {
 	if m, ok := mctx.Module().(*Module); ok {
 		if m.Enabled() {
 			if compiler, ok := m.compiler.(*stubDecorator); ok {
 				generateStubApiVariants(mctx, compiler)
 			}
 		}
 	}
 }

 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)
 	}

 	ndkMigratedLibsLock.Lock()
 	defer ndkMigratedLibsLock.Unlock()
 	for _, lib := range ndkMigratedLibs {
 		if lib == name {
 			return
 		}
 	}
 	ndkMigratedLibs = append(ndkMigratedLibs, name)
 }

 func addStubLibraryCompilerFlags(flags Flags) Flags {
 	flags.CFlags = append(flags.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-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",
 	)
 	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 (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")
 	}

 	objs, versionScript := compileStubLibrary(ctx, flags, String(c.properties.Symbol_file),
 		c.properties.ApiLevel, "")
 	c.versionScriptPath = versionScript
 	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 {

 	useVersionScript, err := shouldUseVersionScript(ctx, stub)
 	if err != nil {
 		ctx.ModuleErrorf(err.Error())
 	}

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

 	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
 	apiLevel := stub.properties.ApiLevel

 	// 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", 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.StripProperties.Strip.None = BoolPtr(true)

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

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

 	return module
 }

 // ndk_library creates a stub library that exposes dummy 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"
	"strconv"
	"strings"
	"sync"

	"github.com/google/blueprint"

	"android/soong/android"
	)

	var (
	toolPath = pctx.SourcePathVariable("toolPath", "build/soong/cc/gen_stub_libs.py")

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

	ndkLibrarySuffix = ".ndk"

	ndkPrebuiltSharedLibs = []string{
	"aaudio",
	"amidi",
	"android",
	"binder_ndk",
	"c",
	"camera2ndk",
	"dl",
	"EGL",
	"GLESv1_CM",
	"GLESv2",
	"GLESv3",
	"jnigraphics",
	"log",
	"mediandk",
	"nativewindow",
	"m",
	"OpenMAXAL",
	"OpenSLES",
	"stdc++",
	"sync",
	"vulkan",
	"z",
	}
	ndkPrebuiltSharedLibraries = addPrefix(append([]string(nil), ndkPrebuiltSharedLibs...), "lib")

	// These libraries have migrated over to the new ndk_library, which is added
	// as a variation dependency via depsMutator.
	ndkMigratedLibs = []string{}
	ndkMigratedLibsLock sync.Mutex // protects ndkMigratedLibs writes during parallel BeginMutator
	)

	// 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

	// Private property for use by the mutator that splits per-API level.
	ApiLevel string `blueprint:"mutated"`

	// 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
	installPath android.Path
	}

	// OMG GO
	func intMax(a int, b int) int {
	if a > b {
	return a
	} else {
	return b
	}
	}

	func normalizeNdkApiLevel(ctx android.BaseContext, apiLevel string,
	arch android.Arch) (string, error) {

	if apiLevel == "current" {
	return apiLevel, nil
	}

	minVersion := ctx.Config().MinSupportedSdkVersion()
	firstArchVersions := map[android.ArchType]int{
	android.Arm: minVersion,
	android.Arm64: 21,
	android.Mips: minVersion,
	android.Mips64: 21,
	android.X86: minVersion,
	android.X86_64: 21,
	}

	firstArchVersion, ok := firstArchVersions[arch.ArchType]
	if !ok {
	panic(fmt.Errorf("Arch %q not found in firstArchVersions", arch.ArchType))
	}

	if apiLevel == "minimum" {
	return strconv.Itoa(firstArchVersion), nil
	}

	// If the NDK drops support for a platform version, we don't want to have to
	// fix up every module that was using it as its SDK version. Clip to the
	// supported version here instead.
	version, err := strconv.Atoi(apiLevel)
	if err != nil {
	return "", fmt.Errorf("API level must be an integer (is %q)", apiLevel)
	}
	version = intMax(version, minVersion)

	return strconv.Itoa(intMax(version, firstArchVersion)), nil
	}

	func getFirstGeneratedVersion(firstSupportedVersion string, platformVersion int) (int, error) {
	if firstSupportedVersion == "current" {
	return platformVersion + 1, nil
	}

	return strconv.Atoi(firstSupportedVersion)
	}

	func shouldUseVersionScript(ctx android.BaseContext, stub *stubDecorator) (bool, error) {
	// unversioned_until is normally empty, in which case we should use the version script.
	if String(stub.properties.Unversioned_until) == "" {
	return true, nil
	}

	if String(stub.properties.Unversioned_until) == "current" {
	if stub.properties.ApiLevel == "current" {
	return true, nil
	} else {
	return false, nil
	}
	}

	if stub.properties.ApiLevel == "current" {
	return true, nil
	}

	unversionedUntil, err := android.ApiStrToNum(ctx, String(stub.properties.Unversioned_until))
	if err != nil {
	return true, err
	}

	version, err := android.ApiStrToNum(ctx, stub.properties.ApiLevel)
	if err != nil {
	return true, err
	}

	return version >= unversionedUntil, nil
	}

	func generateStubApiVariants(mctx android.BottomUpMutatorContext, c *stubDecorator) {
	platformVersion := mctx.Config().PlatformSdkVersionInt()

	firstSupportedVersion, err := normalizeNdkApiLevel(mctx, String(c.properties.First_version),
	mctx.Arch())
	if err != nil {
	mctx.PropertyErrorf("first_version", err.Error())
	}

	firstGenVersion, err := getFirstGeneratedVersion(firstSupportedVersion, platformVersion)
	if err != nil {
	// In theory this is impossible because we've already run this through
	// normalizeNdkApiLevel above.
	mctx.PropertyErrorf("first_version", err.Error())
	}

	var versionStrs []string
	for version := firstGenVersion; version <= platformVersion; version++ {
	versionStrs = append(versionStrs, strconv.Itoa(version))
	}
	versionStrs = append(versionStrs, mctx.Config().PlatformVersionActiveCodenames()...)
	versionStrs = append(versionStrs, "current")

	modules := mctx.CreateVariations(versionStrs...)
	for i, module := range modules {
	module.(Module).compiler.(stubDecorator).properties.ApiLevel = versionStrs[i]
	}
	}

	func ndkApiMutator(mctx android.BottomUpMutatorContext) {
	if m, ok := mctx.Module().(*Module); ok {
	if m.Enabled() {
	if compiler, ok := m.compiler.(*stubDecorator); ok {
	generateStubApiVariants(mctx, compiler)
	}
	}
	}
	}

	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)
	}

	ndkMigratedLibsLock.Lock()
	defer ndkMigratedLibsLock.Unlock()
	for _, lib := range ndkMigratedLibs {
	if lib == name {
	return
	}
	}
	ndkMigratedLibs = append(ndkMigratedLibs, name)
	}

	func addStubLibraryCompilerFlags(flags Flags) Flags {
	flags.CFlags = append(flags.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-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",
	)
	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 (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")
	}

	objs, versionScript := compileStubLibrary(ctx, flags, String(c.properties.Symbol_file),
	c.properties.ApiLevel, "")
	c.versionScriptPath = versionScript
	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 {

	useVersionScript, err := shouldUseVersionScript(ctx, stub)
	if err != nil {
	ctx.ModuleErrorf(err.Error())
	}

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

	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
	apiLevel := stub.properties.ApiLevel

	// 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", 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.StripProperties.Strip.None = BoolPtr(true)

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

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

	return module
	}

	// ndk_library creates a stub library that exposes dummy 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
	}