cc/vendor_snapshot.go

// Copyright 2020 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.
package cc

import (
	"encoding/json"
	"path/filepath"
	"sort"
	"strings"
	"sync"

	"github.com/google/blueprint/proptools"

	"android/soong/android"
)

const (
	vendorSnapshotHeaderSuffix = ".vendor_header."
	vendorSnapshotSharedSuffix = ".vendor_shared."
	vendorSnapshotStaticSuffix = ".vendor_static."
	vendorSnapshotBinarySuffix = ".vendor_binary."
)

var (
	vendorSnapshotsLock         sync.Mutex
	vendorSuffixModulesKey      = android.NewOnceKey("vendorSuffixModules")
	vendorSnapshotHeaderLibsKey = android.NewOnceKey("vendorSnapshotHeaderLibs")
	vendorSnapshotStaticLibsKey = android.NewOnceKey("vendorSnapshotStaticLibs")
	vendorSnapshotSharedLibsKey = android.NewOnceKey("vendorSnapshotSharedLibs")
	vendorSnapshotBinariesKey   = android.NewOnceKey("vendorSnapshotBinaries")
)

// vendor snapshot maps hold names of vendor snapshot modules per arch
func vendorSuffixModules(config android.Config) map[string]bool {
	return config.Once(vendorSuffixModulesKey, func() interface{} {
		return make(map[string]bool)
	}).(map[string]bool)
}

func vendorSnapshotHeaderLibs(config android.Config) *snapshotMap {
	return config.Once(vendorSnapshotHeaderLibsKey, func() interface{} {
		return newSnapshotMap()
	}).(*snapshotMap)
}

func vendorSnapshotSharedLibs(config android.Config) *snapshotMap {
	return config.Once(vendorSnapshotSharedLibsKey, func() interface{} {
		return newSnapshotMap()
	}).(*snapshotMap)
}

func vendorSnapshotStaticLibs(config android.Config) *snapshotMap {
	return config.Once(vendorSnapshotStaticLibsKey, func() interface{} {
		return newSnapshotMap()
	}).(*snapshotMap)
}

func vendorSnapshotBinaries(config android.Config) *snapshotMap {
	return config.Once(vendorSnapshotBinariesKey, func() interface{} {
		return newSnapshotMap()
	}).(*snapshotMap)
}

type vendorSnapshotLibraryProperties struct {
	// snapshot version.
	Version string

	// Target arch name of the snapshot (e.g. 'arm64' for variant 'aosp_arm64')
	Target_arch string

	// Prebuilt file for each arch.
	Src *string `android:"arch_variant"`

	// list of flags that will be used for any module that links against this module.
	Export_flags []string `android:"arch_variant"`

	// Check the prebuilt ELF files (e.g. DT_SONAME, DT_NEEDED, resolution of undefined symbols,
	// etc).
	Check_elf_files *bool

	// Whether this prebuilt needs to depend on sanitize ubsan runtime or not.
	Sanitize_ubsan_dep *bool `android:"arch_variant"`

	// Whether this prebuilt needs to depend on sanitize minimal runtime or not.
	Sanitize_minimal_dep *bool `android:"arch_variant"`
}

type vendorSnapshotLibraryDecorator struct {
	*libraryDecorator
	properties            vendorSnapshotLibraryProperties
	androidMkVendorSuffix bool
}

func (p *vendorSnapshotLibraryDecorator) Name(name string) string {
	return name + p.NameSuffix()
}

func (p *vendorSnapshotLibraryDecorator) NameSuffix() string {
	versionSuffix := p.version()
	if p.arch() != "" {
		versionSuffix += "." + p.arch()
	}

	var linkageSuffix string
	if p.buildShared() {
		linkageSuffix = vendorSnapshotSharedSuffix
	} else if p.buildStatic() {
		linkageSuffix = vendorSnapshotStaticSuffix
	} else {
		linkageSuffix = vendorSnapshotHeaderSuffix
	}

	return linkageSuffix + versionSuffix
}

func (p *vendorSnapshotLibraryDecorator) version() string {
	return p.properties.Version
}

func (p *vendorSnapshotLibraryDecorator) arch() string {
	return p.properties.Target_arch
}

func (p *vendorSnapshotLibraryDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
	p.libraryDecorator.libName = strings.TrimSuffix(ctx.ModuleName(), p.NameSuffix())
	return p.libraryDecorator.linkerFlags(ctx, flags)
}

func (p *vendorSnapshotLibraryDecorator) matchesWithDevice(config android.DeviceConfig) bool {
	arches := config.Arches()
	if len(arches) == 0 || arches[0].ArchType.String() != p.arch() {
		return false
	}
	if !p.header() && p.properties.Src == nil {
		return false
	}
	return true
}

func (p *vendorSnapshotLibraryDecorator) link(ctx ModuleContext,
	flags Flags, deps PathDeps, objs Objects) android.Path {
	m := ctx.Module().(*Module)
	p.androidMkVendorSuffix = vendorSuffixModules(ctx.Config())[m.BaseModuleName()]

	if p.header() {
		return p.libraryDecorator.link(ctx, flags, deps, objs)
	}

	if !p.matchesWithDevice(ctx.DeviceConfig()) {
		return nil
	}

	p.libraryDecorator.exportIncludes(ctx)
	p.libraryDecorator.reexportFlags(p.properties.Export_flags...)

	in := android.PathForModuleSrc(ctx, *p.properties.Src)
	p.unstrippedOutputFile = in

	if p.shared() {
		libName := in.Base()
		builderFlags := flagsToBuilderFlags(flags)

		// Optimize out relinking against shared libraries whose interface hasn't changed by
		// depending on a table of contents file instead of the library itself.
		tocFile := android.PathForModuleOut(ctx, libName+".toc")
		p.tocFile = android.OptionalPathForPath(tocFile)
		TransformSharedObjectToToc(ctx, in, tocFile, builderFlags)
	}

	return in
}

func (p *vendorSnapshotLibraryDecorator) nativeCoverage() bool {
	return false
}

func (p *vendorSnapshotLibraryDecorator) install(ctx ModuleContext, file android.Path) {
	if p.matchesWithDevice(ctx.DeviceConfig()) && (p.shared() || p.static()) {
		p.baseInstaller.install(ctx, file)
	}
}

type vendorSnapshotInterface interface {
	version() string
}

func vendorSnapshotLoadHook(ctx android.LoadHookContext, p vendorSnapshotInterface) {
	if p.version() != ctx.DeviceConfig().VndkVersion() {
		ctx.Module().Disable()
		return
	}
}

func vendorSnapshotLibrary() (*Module, *vendorSnapshotLibraryDecorator) {
	module, library := NewLibrary(android.DeviceSupported)

	module.stl = nil
	module.sanitize = nil
	library.StripProperties.Strip.None = BoolPtr(true)

	prebuilt := &vendorSnapshotLibraryDecorator{
		libraryDecorator: library,
	}

	prebuilt.baseLinker.Properties.No_libcrt = BoolPtr(true)
	prebuilt.baseLinker.Properties.Nocrt = BoolPtr(true)

	// Prevent default system libs (libc, libm, and libdl) from being linked
	if prebuilt.baseLinker.Properties.System_shared_libs == nil {
		prebuilt.baseLinker.Properties.System_shared_libs = []string{}
	}

	module.compiler = nil
	module.linker = prebuilt
	module.installer = prebuilt

	module.AddProperties(
		&prebuilt.properties,
	)

	return module, prebuilt
}

func VendorSnapshotSharedFactory() android.Module {
	module, prebuilt := vendorSnapshotLibrary()
	prebuilt.libraryDecorator.BuildOnlyShared()
	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
		vendorSnapshotLoadHook(ctx, prebuilt)
	})
	return module.Init()
}

func VendorSnapshotStaticFactory() android.Module {
	module, prebuilt := vendorSnapshotLibrary()
	prebuilt.libraryDecorator.BuildOnlyStatic()
	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
		vendorSnapshotLoadHook(ctx, prebuilt)
	})
	return module.Init()
}

func VendorSnapshotHeaderFactory() android.Module {
	module, prebuilt := vendorSnapshotLibrary()
	prebuilt.libraryDecorator.HeaderOnly()
	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
		vendorSnapshotLoadHook(ctx, prebuilt)
	})
	return module.Init()
}

type vendorSnapshotBinaryProperties struct {
	// snapshot version.
	Version string

	// Target arch name of the snapshot (e.g. 'arm64' for variant 'aosp_arm64_ab')
	Target_arch string

	// Prebuilt file for each arch.
	Src *string `android:"arch_variant"`
}

type vendorSnapshotBinaryDecorator struct {
	*binaryDecorator
	properties            vendorSnapshotBinaryProperties
	androidMkVendorSuffix bool
}

func (p *vendorSnapshotBinaryDecorator) Name(name string) string {
	return name + p.NameSuffix()
}

func (p *vendorSnapshotBinaryDecorator) NameSuffix() string {
	versionSuffix := p.version()
	if p.arch() != "" {
		versionSuffix += "." + p.arch()
	}
	return vendorSnapshotBinarySuffix + versionSuffix
}

func (p *vendorSnapshotBinaryDecorator) version() string {
	return p.properties.Version
}

func (p *vendorSnapshotBinaryDecorator) arch() string {
	return p.properties.Target_arch
}

func (p *vendorSnapshotBinaryDecorator) matchesWithDevice(config android.DeviceConfig) bool {
	if config.DeviceArch() != p.arch() {
		return false
	}
	if p.properties.Src == nil {
		return false
	}
	return true
}

func (p *vendorSnapshotBinaryDecorator) link(ctx ModuleContext,
	flags Flags, deps PathDeps, objs Objects) android.Path {
	if !p.matchesWithDevice(ctx.DeviceConfig()) {
		return nil
	}

	in := android.PathForModuleSrc(ctx, *p.properties.Src)
	builderFlags := flagsToBuilderFlags(flags)
	p.unstrippedOutputFile = in
	binName := in.Base()
	if p.needsStrip(ctx) {
		stripped := android.PathForModuleOut(ctx, "stripped", binName)
		p.stripExecutableOrSharedLib(ctx, in, stripped, builderFlags)
		in = stripped
	}

	m := ctx.Module().(*Module)
	p.androidMkVendorSuffix = vendorSuffixModules(ctx.Config())[m.BaseModuleName()]

	// use cpExecutable to make it executable
	outputFile := android.PathForModuleOut(ctx, binName)
	ctx.Build(pctx, android.BuildParams{
		Rule:        android.CpExecutable,
		Description: "prebuilt",
		Output:      outputFile,
		Input:       in,
	})

	return outputFile
}

func VendorSnapshotBinaryFactory() android.Module {
	module, binary := NewBinary(android.DeviceSupported)
	binary.baseLinker.Properties.No_libcrt = BoolPtr(true)
	binary.baseLinker.Properties.Nocrt = BoolPtr(true)

	// Prevent default system libs (libc, libm, and libdl) from being linked
	if binary.baseLinker.Properties.System_shared_libs == nil {
		binary.baseLinker.Properties.System_shared_libs = []string{}
	}

	prebuilt := &vendorSnapshotBinaryDecorator{
		binaryDecorator: binary,
	}

	module.compiler = nil
	module.sanitize = nil
	module.stl = nil
	module.linker = prebuilt

	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
		vendorSnapshotLoadHook(ctx, prebuilt)
	})

	module.AddProperties(&prebuilt.properties)
	return module.Init()
}

func init() {
	android.RegisterSingletonType("vendor-snapshot", VendorSnapshotSingleton)
	android.RegisterModuleType("vendor_snapshot_shared", VendorSnapshotSharedFactory)
	android.RegisterModuleType("vendor_snapshot_static", VendorSnapshotStaticFactory)
	android.RegisterModuleType("vendor_snapshot_header", VendorSnapshotHeaderFactory)
	android.RegisterModuleType("vendor_snapshot_binary", VendorSnapshotBinaryFactory)
}

func VendorSnapshotSingleton() android.Singleton {
	return &vendorSnapshotSingleton{}
}

type vendorSnapshotSingleton struct {
	vendorSnapshotZipFile android.OptionalPath
}

var (
	// Modules under following directories are ignored. They are OEM's and vendor's
	// proprietary modules(device/, vendor/, and hardware/).
	// TODO(b/65377115): Clean up these with more maintainable way
	vendorProprietaryDirs = []string{
		"device",
		"vendor",
		"hardware",
	}

	// Modules under following directories are included as they are in AOSP,
	// although hardware/ is normally for vendor's own.
	// TODO(b/65377115): Clean up these with more maintainable way
	aospDirsUnderProprietary = []string{
		"hardware/interfaces",
		"hardware/libhardware",
		"hardware/libhardware_legacy",
		"hardware/ril",
	}
)

// Determine if a dir under source tree is an SoC-owned proprietary directory, such as
// device/, vendor/, etc.
func isVendorProprietaryPath(dir string) bool {
	for _, p := range vendorProprietaryDirs {
		if strings.HasPrefix(dir, p) {
			// filter out AOSP defined directories, e.g. hardware/interfaces/
			aosp := false
			for _, p := range aospDirsUnderProprietary {
				if strings.HasPrefix(dir, p) {
					aosp = true
					break
				}
			}
			if !aosp {
				return true
			}
		}
	}
	return false
}

// Determine if a module is going to be included in vendor snapshot or not.
//
// Targets of vendor snapshot are "vendor: true" or "vendor_available: true" modules in
// AOSP. They are not guaranteed to be compatible with older vendor images. (e.g. might
// depend on newer VNDK) So they are captured as vendor snapshot To build older vendor
// image and newer system image altogether.
func isVendorSnapshotModule(ctx android.SingletonContext, m *Module) bool {
	if !m.Enabled() {
		return false
	}
	// skip proprietary modules, but include all VNDK (static)
	if isVendorProprietaryPath(ctx.ModuleDir(m)) && !m.IsVndk() {
		return false
	}
	if m.Target().Os.Class != android.Device {
		return false
	}
	if m.Target().NativeBridge == android.NativeBridgeEnabled {
		return false
	}
	// the module must be installed in /vendor
	if !m.installable() || m.isSnapshotPrebuilt() || !m.inVendor() {
		return false
	}
	// exclude test modules
	if _, ok := m.linker.(interface{ gtest() bool }); ok {
		return false
	}
	// TODO(b/65377115): add full support for sanitizer
	if m.sanitize != nil && !m.sanitize.isUnsanitizedVariant() {
		return false
	}

	// Libraries
	if l, ok := m.linker.(snapshotLibraryInterface); ok {
		if l.static() {
			return proptools.BoolDefault(m.VendorProperties.Vendor_available, true)
		}
		if l.shared() {
			return !m.IsVndk()
		}
		return true
	}

	// Binaries
	_, ok := m.linker.(*binaryDecorator)
	if !ok {
		if _, ok := m.linker.(*prebuiltBinaryLinker); !ok {
			return false
		}
	}
	return proptools.BoolDefault(m.VendorProperties.Vendor_available, true)
}

func (c *vendorSnapshotSingleton) GenerateBuildActions(ctx android.SingletonContext) {
	// BOARD_VNDK_VERSION must be set to 'current' in order to generate a vendor snapshot.
	if ctx.DeviceConfig().VndkVersion() != "current" {
		return
	}

	var snapshotOutputs android.Paths

	/*
		Vendor snapshot zipped artifacts directory structure:
		{SNAPSHOT_ARCH}/
			arch-{TARGET_ARCH}-{TARGET_ARCH_VARIANT}/
				shared/
					(.so shared libraries)
				static/
					(.a static libraries)
				header/
					(header only libraries)
				binary/
					(executable binaries)
			arch-{TARGET_2ND_ARCH}-{TARGET_2ND_ARCH_VARIANT}/
				shared/
					(.so shared libraries)
				static/
					(.a static libraries)
				header/
					(header only libraries)
				binary/
					(executable binaries)
			NOTICE_FILES/
				(notice files, e.g. libbase.txt)
			configs/
				(config files, e.g. init.rc files, vintf_fragments.xml files, etc.)
			include/
				(header files of same directory structure with source tree)
	*/

	snapshotDir := "vendor-snapshot"
	snapshotArchDir := filepath.Join(snapshotDir, ctx.DeviceConfig().DeviceArch())

	includeDir := filepath.Join(snapshotArchDir, "include")
	configsDir := filepath.Join(snapshotArchDir, "configs")
	noticeDir := filepath.Join(snapshotArchDir, "NOTICE_FILES")

	installedNotices := make(map[string]bool)
	installedConfigs := make(map[string]bool)

	var headers android.Paths

	type vendorSnapshotLibraryInterface interface {
		exportedFlagsProducer
		libraryInterface
	}

	var _ vendorSnapshotLibraryInterface = (*prebuiltLibraryLinker)(nil)
	var _ vendorSnapshotLibraryInterface = (*libraryDecorator)(nil)

	installSnapshot := func(m *Module) android.Paths {
		targetArch := "arch-" + m.Target().Arch.ArchType.String()
		if m.Target().Arch.ArchVariant != "" {
			targetArch += "-" + m.Target().Arch.ArchVariant
		}

		var ret android.Paths

		prop := struct {
			ModuleName          string `json:",omitempty"`
			RelativeInstallPath string `json:",omitempty"`

			// library flags
			ExportedDirs       []string `json:",omitempty"`
			ExportedSystemDirs []string `json:",omitempty"`
			ExportedFlags      []string `json:",omitempty"`
			SanitizeMinimalDep bool     `json:",omitempty"`
			SanitizeUbsanDep   bool     `json:",omitempty"`

			// binary flags
			Symlinks []string `json:",omitempty"`

			// dependencies
			SharedLibs  []string `json:",omitempty"`
			RuntimeLibs []string `json:",omitempty"`
			Required    []string `json:",omitempty"`

			// extra config files
			InitRc         []string `json:",omitempty"`
			VintfFragments []string `json:",omitempty"`
		}{}

		// Common properties among snapshots.
		prop.ModuleName = ctx.ModuleName(m)
		prop.RelativeInstallPath = m.RelativeInstallPath()
		prop.RuntimeLibs = m.Properties.SnapshotRuntimeLibs
		prop.Required = m.RequiredModuleNames()
		for _, path := range m.InitRc() {
			prop.InitRc = append(prop.InitRc, filepath.Join("configs", path.Base()))
		}
		for _, path := range m.VintfFragments() {
			prop.VintfFragments = append(prop.VintfFragments, filepath.Join("configs", path.Base()))
		}

		// install config files. ignores any duplicates.
		for _, path := range append(m.InitRc(), m.VintfFragments()...) {
			out := filepath.Join(configsDir, path.Base())
			if !installedConfigs[out] {
				installedConfigs[out] = true
				ret = append(ret, copyFile(ctx, path, out))
			}
		}

		var propOut string

		if l, ok := m.linker.(vendorSnapshotLibraryInterface); ok {
			// library flags
			prop.ExportedFlags = l.exportedFlags()
			for _, dir := range l.exportedDirs() {
				prop.ExportedDirs = append(prop.ExportedDirs, filepath.Join("include", dir.String()))
			}
			for _, dir := range l.exportedSystemDirs() {
				prop.ExportedSystemDirs = append(prop.ExportedSystemDirs, filepath.Join("include", dir.String()))
			}
			// shared libs dependencies aren't meaningful on static or header libs
			if l.shared() {
				prop.SharedLibs = m.Properties.SnapshotSharedLibs
			}
			if l.static() && m.sanitize != nil {
				prop.SanitizeMinimalDep = m.sanitize.Properties.MinimalRuntimeDep || enableMinimalRuntime(m.sanitize)
				prop.SanitizeUbsanDep = m.sanitize.Properties.UbsanRuntimeDep || enableUbsanRuntime(m.sanitize)
			}

			var libType string
			if l.static() {
				libType = "static"
			} else if l.shared() {
				libType = "shared"
			} else {
				libType = "header"
			}

			var stem string

			// install .a or .so
			if libType != "header" {
				libPath := m.outputFile.Path()
				stem = libPath.Base()
				snapshotLibOut := filepath.Join(snapshotArchDir, targetArch, libType, stem)
				ret = append(ret, copyFile(ctx, libPath, snapshotLibOut))
			} else {
				stem = ctx.ModuleName(m)
			}

			propOut = filepath.Join(snapshotArchDir, targetArch, libType, stem+".json")
		} else {
			// binary flags
			prop.Symlinks = m.Symlinks()
			prop.SharedLibs = m.Properties.SnapshotSharedLibs

			// install bin
			binPath := m.outputFile.Path()
			snapshotBinOut := filepath.Join(snapshotArchDir, targetArch, "binary", binPath.Base())
			ret = append(ret, copyFile(ctx, binPath, snapshotBinOut))
			propOut = snapshotBinOut + ".json"
		}

		j, err := json.Marshal(prop)
		if err != nil {
			ctx.Errorf("json marshal to %q failed: %#v", propOut, err)
			return nil
		}
		ret = append(ret, writeStringToFile(ctx, string(j), propOut))

		return ret
	}

	ctx.VisitAllModules(func(module android.Module) {
		m, ok := module.(*Module)
		if !ok || !isVendorSnapshotModule(ctx, m) {
			return
		}

		snapshotOutputs = append(snapshotOutputs, installSnapshot(m)...)
		if l, ok := m.linker.(vendorSnapshotLibraryInterface); ok {
			headers = append(headers, exportedHeaders(ctx, l)...)
		}

		if m.NoticeFile().Valid() {
			noticeName := ctx.ModuleName(m) + ".txt"
			noticeOut := filepath.Join(noticeDir, noticeName)
			// skip already copied notice file
			if !installedNotices[noticeOut] {
				installedNotices[noticeOut] = true
				snapshotOutputs = append(snapshotOutputs, copyFile(
					ctx, m.NoticeFile().Path(), noticeOut))
			}
		}
	})

	// install all headers after removing duplicates
	for _, header := range android.FirstUniquePaths(headers) {
		snapshotOutputs = append(snapshotOutputs, copyFile(
			ctx, header, filepath.Join(includeDir, header.String())))
	}

	// All artifacts are ready. Sort them to normalize ninja and then zip.
	sort.Slice(snapshotOutputs, func(i, j int) bool {
		return snapshotOutputs[i].String() < snapshotOutputs[j].String()
	})

	zipPath := android.PathForOutput(ctx, snapshotDir, "vendor-"+ctx.Config().DeviceName()+".zip")
	zipRule := android.NewRuleBuilder()

	// filenames in rspfile from FlagWithRspFileInputList might be single-quoted. Remove it with tr
	snapshotOutputList := android.PathForOutput(ctx, snapshotDir, "vendor-"+ctx.Config().DeviceName()+"_list")
	zipRule.Command().
		Text("tr").
		FlagWithArg("-d ", "\\'").
		FlagWithRspFileInputList("< ", snapshotOutputs).
		FlagWithOutput("> ", snapshotOutputList)

	zipRule.Temporary(snapshotOutputList)

	zipRule.Command().
		BuiltTool(ctx, "soong_zip").
		FlagWithOutput("-o ", zipPath).
		FlagWithArg("-C ", android.PathForOutput(ctx, snapshotDir).String()).
		FlagWithInput("-l ", snapshotOutputList)

	zipRule.Build(pctx, ctx, zipPath.String(), "vendor snapshot "+zipPath.String())
	zipRule.DeleteTemporaryFiles()
	c.vendorSnapshotZipFile = android.OptionalPathForPath(zipPath)
}

func (c *vendorSnapshotSingleton) MakeVars(ctx android.MakeVarsContext) {
	ctx.Strict("SOONG_VENDOR_SNAPSHOT_ZIP", c.vendorSnapshotZipFile.String())
}

type snapshotInterface interface {
	matchesWithDevice(config android.DeviceConfig) bool
}

var _ snapshotInterface = (*vndkPrebuiltLibraryDecorator)(nil)
var _ snapshotInterface = (*vendorSnapshotLibraryDecorator)(nil)
var _ snapshotInterface = (*vendorSnapshotBinaryDecorator)(nil)

// gathers all snapshot modules for vendor, and disable unnecessary snapshots
// TODO(b/145966707): remove mutator and utilize android.Prebuilt to override source modules
func VendorSnapshotMutator(ctx android.BottomUpMutatorContext) {
	vndkVersion := ctx.DeviceConfig().VndkVersion()
	// don't need snapshot if current
	if vndkVersion == "current" || vndkVersion == "" {
		return
	}

	module, ok := ctx.Module().(*Module)
	if !ok || !module.Enabled() || module.VndkVersion() != vndkVersion {
		return
	}

	snapshot, ok := module.linker.(snapshotInterface)
	if !ok {
		return
	}

	if !snapshot.matchesWithDevice(ctx.DeviceConfig()) {
		// Disable unnecessary snapshot module, but do not disable
		// vndk_prebuilt_shared because they might be packed into vndk APEX
		if !module.IsVndk() {
			module.Disable()
		}
		return
	}

	var snapshotMap *snapshotMap

	if lib, ok := module.linker.(libraryInterface); ok {
		if lib.static() {
			snapshotMap = vendorSnapshotStaticLibs(ctx.Config())
		} else if lib.shared() {
			snapshotMap = vendorSnapshotSharedLibs(ctx.Config())
		} else {
			// header
			snapshotMap = vendorSnapshotHeaderLibs(ctx.Config())
		}
	} else if _, ok := module.linker.(*vendorSnapshotBinaryDecorator); ok {
		snapshotMap = vendorSnapshotBinaries(ctx.Config())
	} else {
		return
	}

	vendorSnapshotsLock.Lock()
	defer vendorSnapshotsLock.Unlock()
	snapshotMap.add(module.BaseModuleName(), ctx.Arch().ArchType, ctx.ModuleName())
}

// Disables source modules which have snapshots
func VendorSnapshotSourceMutator(ctx android.BottomUpMutatorContext) {
	if !ctx.Device() {
		return
	}

	vndkVersion := ctx.DeviceConfig().VndkVersion()
	// don't need snapshot if current
	if vndkVersion == "current" || vndkVersion == "" {
		return
	}

	module, ok := ctx.Module().(*Module)
	if !ok {
		return
	}

	// vendor suffix should be added to snapshots if the source module isn't vendor: true.
	if !module.SocSpecific() {
		// But we can't just check SocSpecific() since we already passed the image mutator.
		// Check ramdisk and recovery to see if we are real "vendor: true" module.
		ramdisk_available := module.InRamdisk() && !module.OnlyInRamdisk()
		recovery_available := module.InRecovery() && !module.OnlyInRecovery()

		if !ramdisk_available && !recovery_available {
			vendorSnapshotsLock.Lock()
			defer vendorSnapshotsLock.Unlock()

			vendorSuffixModules(ctx.Config())[ctx.ModuleName()] = true
		}
	}

	if module.isSnapshotPrebuilt() || module.VndkVersion() != ctx.DeviceConfig().VndkVersion() {
		// only non-snapshot modules with BOARD_VNDK_VERSION
		return
	}

	var snapshotMap *snapshotMap

	if lib, ok := module.linker.(libraryInterface); ok {
		if lib.static() {
			snapshotMap = vendorSnapshotStaticLibs(ctx.Config())
		} else if lib.shared() {
			snapshotMap = vendorSnapshotSharedLibs(ctx.Config())
		} else {
			// header
			snapshotMap = vendorSnapshotHeaderLibs(ctx.Config())
		}
	} else if _, ok := module.linker.(*binaryDecorator); ok {
		snapshotMap = vendorSnapshotBinaries(ctx.Config())
	} else if _, ok := module.linker.(*prebuiltBinaryLinker); ok {
		snapshotMap = vendorSnapshotBinaries(ctx.Config())
	} else {
		return
	}

	if _, ok := snapshotMap.get(ctx.ModuleName(), ctx.Arch().ArchType); !ok {
		// Corresponding snapshot doesn't exist
		return
	}

	// Disables source modules if corresponding snapshot exists.
	if lib, ok := module.linker.(libraryInterface); ok && lib.buildStatic() && lib.buildShared() {
		// But do not disable because the shared variant depends on the static variant.
		module.SkipInstall()
		module.Properties.HideFromMake = true
	} else {
		module.Disable()
	}
}