Add Rust support to Soong.

Adds support to Soong for building rust modules. This currently only
supports x86_64 device and x86 linux host targets. The functionality
is sufficient to build crosvm.

Bug: 136189233
Test: Test module builds.
Test: crosvm builds.
Change-Id: I6ea04615834a6d673578ab10ea1a2eb04259fe09
diff --git a/rust/rust.go b/rust/rust.go
new file mode 100644
index 0000000..5a2514e
--- /dev/null
+++ b/rust/rust.go
@@ -0,0 +1,498 @@
+// Copyright 2019 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 rust
+
+import (
+	"strings"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+	"android/soong/cc"
+	"android/soong/rust/config"
+)
+
+var pctx = android.NewPackageContext("android/soong/rust")
+
+func init() {
+	// Only allow rust modules to be defined for certain projects
+	rustModuleTypes := []string{
+		"rust_binary",
+		"rust_binary_host",
+		"rust_library",
+		"rust_library_dylib",
+		"rust_library_rlib",
+		"rust_library_host",
+		"rust_library_host_dylib",
+		"rust_library_host_rlib",
+		"rust_proc_macro",
+	}
+
+	rustAllowedPaths := []string{
+		"external/rust/crates",
+		"external/crosvm",
+		"external/adhd",
+	}
+
+	android.AddNeverAllowRules(
+		android.NeverAllow().
+			NotIn(rustAllowedPaths...).
+			ModuleType(rustModuleTypes...))
+
+	android.RegisterModuleType("rust_defaults", defaultsFactory)
+	android.PreDepsMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.BottomUp("rust_libraries", LibraryMutator).Parallel()
+	})
+	pctx.Import("android/soong/rust/config")
+}
+
+type Flags struct {
+	GlobalFlags   []string      // Flags that apply globally
+	RustFlags     []string      // Flags that apply to rust
+	LinkFlags     []string      // Flags that apply to linker
+	RustFlagsDeps android.Paths // Files depended on by compiler flags
+	Toolchain     config.Toolchain
+}
+
+type BaseProperties struct {
+	AndroidMkRlibs         []string
+	AndroidMkDylibs        []string
+	AndroidMkProcMacroLibs []string
+	AndroidMkSharedLibs    []string
+	AndroidMkStaticLibs    []string
+}
+
+type Module struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	Properties BaseProperties
+
+	hod      android.HostOrDeviceSupported
+	multilib android.Multilib
+
+	compiler         compiler
+	cachedToolchain  config.Toolchain
+	subAndroidMkOnce map[subAndroidMkProvider]bool
+	outputFile       android.OptionalPath
+}
+
+type Deps struct {
+	Dylibs     []string
+	Rlibs      []string
+	ProcMacros []string
+	SharedLibs []string
+	StaticLibs []string
+
+	CrtBegin, CrtEnd string
+}
+
+type PathDeps struct {
+	DyLibs     RustLibraries
+	RLibs      RustLibraries
+	SharedLibs android.Paths
+	StaticLibs android.Paths
+	ProcMacros RustLibraries
+	linkDirs   []string
+	depFlags   []string
+	//ReexportedDeps android.Paths
+}
+
+type RustLibraries []RustLibrary
+
+type RustLibrary struct {
+	Path      android.Path
+	CrateName string
+}
+
+type compiler interface {
+	compilerFlags(ctx ModuleContext, flags Flags) Flags
+	compilerProps() []interface{}
+	compile(ctx ModuleContext, flags Flags, deps PathDeps) android.Path
+	compilerDeps(ctx DepsContext, deps Deps) Deps
+	crateName() string
+
+	install(ctx ModuleContext, path android.Path)
+	relativeInstallPath() string
+}
+
+func defaultsFactory() android.Module {
+	return DefaultsFactory()
+}
+
+type Defaults struct {
+	android.ModuleBase
+	android.DefaultsModuleBase
+}
+
+func DefaultsFactory(props ...interface{}) android.Module {
+	module := &Defaults{}
+
+	module.AddProperties(props...)
+	module.AddProperties(
+		&BaseProperties{},
+		&BaseCompilerProperties{},
+		&BinaryCompilerProperties{},
+		&LibraryCompilerProperties{},
+		&ProcMacroCompilerProperties{},
+		&PrebuiltProperties{},
+	)
+
+	android.InitDefaultsModule(module)
+	return module
+}
+
+func (mod *Module) CrateName() string {
+	if mod.compiler != nil && mod.compiler.crateName() != "" {
+		return mod.compiler.crateName()
+	}
+	// Default crate names replace '-' in the name to '_'
+	return strings.Replace(mod.BaseModuleName(), "-", "_", -1)
+}
+
+func (mod *Module) Init() android.Module {
+	mod.AddProperties(&mod.Properties)
+
+	if mod.compiler != nil {
+		mod.AddProperties(mod.compiler.compilerProps()...)
+	}
+	android.InitAndroidArchModule(mod, mod.hod, mod.multilib)
+
+	android.InitDefaultableModule(mod)
+
+	return mod
+}
+
+func newBaseModule(hod android.HostOrDeviceSupported, multilib android.Multilib) *Module {
+	return &Module{
+		hod:      hod,
+		multilib: multilib,
+	}
+}
+func newModule(hod android.HostOrDeviceSupported, multilib android.Multilib) *Module {
+	module := newBaseModule(hod, multilib)
+	return module
+}
+
+type ModuleContext interface {
+	android.ModuleContext
+	ModuleContextIntf
+}
+
+type BaseModuleContext interface {
+	android.BaseModuleContext
+	ModuleContextIntf
+}
+
+type DepsContext interface {
+	android.BottomUpMutatorContext
+	ModuleContextIntf
+}
+
+type ModuleContextIntf interface {
+	toolchain() config.Toolchain
+	baseModuleName() string
+	CrateName() string
+}
+
+type depsContext struct {
+	android.BottomUpMutatorContext
+	moduleContextImpl
+}
+
+type moduleContext struct {
+	android.ModuleContext
+	moduleContextImpl
+}
+
+type moduleContextImpl struct {
+	mod *Module
+	ctx BaseModuleContext
+}
+
+func (ctx *moduleContextImpl) toolchain() config.Toolchain {
+	return ctx.mod.toolchain(ctx.ctx)
+}
+
+func (mod *Module) toolchain(ctx android.BaseModuleContext) config.Toolchain {
+	if mod.cachedToolchain == nil {
+		mod.cachedToolchain = config.FindToolchain(ctx.Os(), ctx.Arch())
+	}
+	return mod.cachedToolchain
+}
+
+func (d *Defaults) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+}
+
+func (mod *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
+	ctx := &moduleContext{
+		ModuleContext: actx,
+		moduleContextImpl: moduleContextImpl{
+			mod: mod,
+		},
+	}
+	ctx.ctx = ctx
+
+	toolchain := mod.toolchain(ctx)
+
+	if !toolchain.Supported() {
+		// This toolchain's unsupported, there's nothing to do for this mod.
+		return
+	}
+
+	deps := mod.depsToPaths(ctx)
+	flags := Flags{
+		Toolchain: toolchain,
+	}
+
+	if mod.compiler != nil {
+		flags = mod.compiler.compilerFlags(ctx, flags)
+		outputFile := mod.compiler.compile(ctx, flags, deps)
+		mod.outputFile = android.OptionalPathForPath(outputFile)
+		mod.compiler.install(ctx, mod.outputFile.Path())
+	}
+}
+
+func (mod *Module) deps(ctx DepsContext) Deps {
+	deps := Deps{}
+
+	if mod.compiler != nil {
+		deps = mod.compiler.compilerDeps(ctx, deps)
+	}
+
+	deps.Rlibs = android.LastUniqueStrings(deps.Rlibs)
+	deps.Dylibs = android.LastUniqueStrings(deps.Dylibs)
+	deps.ProcMacros = android.LastUniqueStrings(deps.ProcMacros)
+	deps.SharedLibs = android.LastUniqueStrings(deps.SharedLibs)
+	deps.StaticLibs = android.LastUniqueStrings(deps.StaticLibs)
+
+	return deps
+
+}
+
+func (ctx *moduleContextImpl) baseModuleName() string {
+	return ctx.mod.ModuleBase.BaseModuleName()
+}
+
+func (ctx *moduleContextImpl) CrateName() string {
+	return ctx.mod.CrateName()
+}
+
+type dependencyTag struct {
+	blueprint.BaseDependencyTag
+	name       string
+	library    bool
+	proc_macro bool
+}
+
+var (
+	rlibDepTag      = dependencyTag{name: "rlibTag", library: true}
+	dylibDepTag     = dependencyTag{name: "dylib", library: true}
+	procMacroDepTag = dependencyTag{name: "procMacro", proc_macro: true}
+)
+
+func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
+	var depPaths PathDeps
+
+	directRlibDeps := []*Module{}
+	directDylibDeps := []*Module{}
+	directProcMacroDeps := []*Module{}
+	directSharedLibDeps := []*(cc.Module){}
+	directStaticLibDeps := []*(cc.Module){}
+
+	ctx.VisitDirectDeps(func(dep android.Module) {
+		depName := ctx.OtherModuleName(dep)
+		depTag := ctx.OtherModuleDependencyTag(dep)
+		if dep.Target().Os != ctx.Os() {
+			ctx.ModuleErrorf("OS mismatch between %q and %q", ctx.ModuleName(), depName)
+			return
+		}
+		if dep.Target().Arch.ArchType != ctx.Arch().ArchType {
+			ctx.ModuleErrorf("Arch mismatch between %q and %q", ctx.ModuleName(), depName)
+			return
+		}
+
+		if rustDep, ok := dep.(*Module); ok {
+			//Handle Rust Modules
+			linkFile := rustDep.outputFile
+			if !linkFile.Valid() {
+				ctx.ModuleErrorf("Invalid output file when adding dep %q to %q", depName, ctx.ModuleName())
+			}
+
+			switch depTag {
+			case dylibDepTag:
+				dylib, ok := rustDep.compiler.(libraryInterface)
+				if !ok || !dylib.dylib() {
+					ctx.ModuleErrorf("mod %q not an dylib library", depName)
+					return
+				}
+				directDylibDeps = append(directDylibDeps, rustDep)
+				mod.Properties.AndroidMkDylibs = append(mod.Properties.AndroidMkDylibs, depName)
+			case rlibDepTag:
+				rlib, ok := rustDep.compiler.(libraryInterface)
+				if !ok || !rlib.rlib() {
+					ctx.ModuleErrorf("mod %q not an rlib library", depName)
+					return
+				}
+				directRlibDeps = append(directRlibDeps, rustDep)
+				mod.Properties.AndroidMkRlibs = append(mod.Properties.AndroidMkRlibs, depName)
+			case procMacroDepTag:
+				directProcMacroDeps = append(directProcMacroDeps, rustDep)
+				mod.Properties.AndroidMkProcMacroLibs = append(mod.Properties.AndroidMkProcMacroLibs, depName)
+			}
+
+			//Append the dependencies exportedDirs
+			if lib, ok := rustDep.compiler.(*libraryDecorator); ok {
+				depPaths.linkDirs = append(depPaths.linkDirs, lib.exportedDirs()...)
+				depPaths.depFlags = append(depPaths.depFlags, lib.exportedDepFlags()...)
+			} else if procMacro, ok := rustDep.compiler.(*libraryDecorator); ok {
+				depPaths.linkDirs = append(depPaths.linkDirs, procMacro.exportedDirs()...)
+				depPaths.depFlags = append(depPaths.depFlags, procMacro.exportedDepFlags()...)
+			}
+
+			// Append this dependencies output to this mod's linkDirs so they can be exported to dependencies
+			// This can be probably be refactored by defining a common exporter interface similar to cc's
+			if depTag == dylibDepTag || depTag == rlibDepTag || depTag == procMacroDepTag {
+				linkDir := linkPathFromFilePath(linkFile.Path())
+				if lib, ok := mod.compiler.(*libraryDecorator); ok {
+					lib.linkDirs = append(lib.linkDirs, linkDir)
+				} else if procMacro, ok := mod.compiler.(*procMacroDecorator); ok {
+					procMacro.linkDirs = append(procMacro.linkDirs, linkDir)
+				}
+			}
+
+		} else if ccDep, ok := dep.(*cc.Module); ok {
+
+			//Handle C dependencies
+			linkFile := ccDep.OutputFile()
+			linkPath := linkPathFromFilePath(linkFile.Path())
+			libName := libNameFromFilePath(linkFile.Path())
+			if !linkFile.Valid() {
+				ctx.ModuleErrorf("Invalid output file when adding dep %q to %q", depName, ctx.ModuleName())
+			}
+
+			exportDep := false
+
+			switch depTag {
+			case cc.StaticDepTag():
+				depPaths.linkDirs = append(depPaths.linkDirs, linkPath)
+				depPaths.depFlags = append(depPaths.depFlags, "-l"+libName)
+				directStaticLibDeps = append(directStaticLibDeps, ccDep)
+				mod.Properties.AndroidMkStaticLibs = append(mod.Properties.AndroidMkStaticLibs, depName)
+			case cc.SharedDepTag():
+				depPaths.linkDirs = append(depPaths.linkDirs, linkPath)
+				depPaths.depFlags = append(depPaths.depFlags, "-l"+libName)
+				directSharedLibDeps = append(directSharedLibDeps, ccDep)
+				mod.Properties.AndroidMkSharedLibs = append(mod.Properties.AndroidMkSharedLibs, depName)
+				exportDep = true
+			}
+
+			// Make sure these dependencies are propagated
+			if lib, ok := mod.compiler.(*libraryDecorator); ok && (exportDep || lib.rlib()) {
+				lib.linkDirs = append(lib.linkDirs, linkPath)
+				lib.depFlags = append(lib.depFlags, "-l"+libName)
+			} else if procMacro, ok := mod.compiler.(*procMacroDecorator); ok && exportDep {
+				procMacro.linkDirs = append(procMacro.linkDirs, linkPath)
+				procMacro.depFlags = append(procMacro.depFlags, "-l"+libName)
+			}
+
+		}
+	})
+
+	var rlibDepFiles RustLibraries
+	for _, dep := range directRlibDeps {
+		rlibDepFiles = append(rlibDepFiles, RustLibrary{Path: dep.outputFile.Path(), CrateName: dep.CrateName()})
+	}
+	var dylibDepFiles RustLibraries
+	for _, dep := range directDylibDeps {
+		dylibDepFiles = append(dylibDepFiles, RustLibrary{Path: dep.outputFile.Path(), CrateName: dep.CrateName()})
+	}
+	var procMacroDepFiles RustLibraries
+	for _, dep := range directProcMacroDeps {
+		procMacroDepFiles = append(procMacroDepFiles, RustLibrary{Path: dep.outputFile.Path(), CrateName: dep.CrateName()})
+	}
+
+	var staticLibDepFiles android.Paths
+	for _, dep := range directStaticLibDeps {
+		staticLibDepFiles = append(staticLibDepFiles, dep.OutputFile().Path())
+	}
+
+	var sharedLibDepFiles android.Paths
+	for _, dep := range directSharedLibDeps {
+		sharedLibDepFiles = append(sharedLibDepFiles, dep.OutputFile().Path())
+	}
+
+	depPaths.RLibs = append(depPaths.RLibs, rlibDepFiles...)
+	depPaths.DyLibs = append(depPaths.DyLibs, dylibDepFiles...)
+	depPaths.SharedLibs = append(depPaths.SharedLibs, sharedLibDepFiles...)
+	depPaths.StaticLibs = append(depPaths.StaticLibs, staticLibDepFiles...)
+	depPaths.ProcMacros = append(depPaths.ProcMacros, procMacroDepFiles...)
+
+	// Dedup exported flags from dependencies
+	depPaths.linkDirs = android.FirstUniqueStrings(depPaths.linkDirs)
+	depPaths.depFlags = android.FirstUniqueStrings(depPaths.depFlags)
+
+	return depPaths
+}
+
+func linkPathFromFilePath(filepath android.Path) string {
+	return strings.Split(filepath.String(), filepath.Base())[0]
+}
+func libNameFromFilePath(filepath android.Path) string {
+	libName := strings.Split(filepath.Base(), filepath.Ext())[0]
+	if strings.Contains(libName, "lib") {
+		libName = strings.Split(libName, "lib")[1]
+	}
+	return libName
+}
+func (mod *Module) DepsMutator(actx android.BottomUpMutatorContext) {
+	ctx := &depsContext{
+		BottomUpMutatorContext: actx,
+		moduleContextImpl: moduleContextImpl{
+			mod: mod,
+		},
+	}
+	ctx.ctx = ctx
+
+	deps := mod.deps(ctx)
+
+	actx.AddVariationDependencies([]blueprint.Variation{{Mutator: "rust_libraries", Variation: "rlib"}}, rlibDepTag, deps.Rlibs...)
+	actx.AddVariationDependencies([]blueprint.Variation{{Mutator: "rust_libraries", Variation: "dylib"}}, dylibDepTag, deps.Dylibs...)
+
+	ccDepVariations := []blueprint.Variation{}
+	ccDepVariations = append(ccDepVariations, blueprint.Variation{Mutator: "version", Variation: ""})
+	if !mod.Host() {
+		ccDepVariations = append(ccDepVariations, blueprint.Variation{Mutator: "image", Variation: "core"})
+	}
+	actx.AddVariationDependencies(append(ccDepVariations, blueprint.Variation{Mutator: "link", Variation: "shared"}), cc.SharedDepTag(), deps.SharedLibs...)
+	actx.AddVariationDependencies(append(ccDepVariations, blueprint.Variation{Mutator: "link", Variation: "static"}), cc.StaticDepTag(), deps.StaticLibs...)
+	actx.AddDependency(mod, procMacroDepTag, deps.ProcMacros...)
+}
+
+func (mod *Module) Name() string {
+	name := mod.ModuleBase.Name()
+	if p, ok := mod.compiler.(interface {
+		Name(string) string
+	}); ok {
+		name = p.Name(name)
+	}
+	return name
+}
+
+var Bool = proptools.Bool
+var BoolDefault = proptools.BoolDefault
+var String = proptools.String
+var StringPtr = proptools.StringPtr