platform_build_soong/cc/ndk_library.go

// 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"
	"github.com/google/blueprint/proptools"

	"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
}

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
	}

	str := proptools.StringDefault(this.properties.Unversioned_until, "minimum")
	this.unversionedUntil, err = nativeApiLevelFromUser(ctx, str)
	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)
	return module
}