rust/bindgen.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 rust

import (
	"github.com/google/blueprint"
	"strings"

	"android/soong/android"
	"android/soong/cc"
	ccConfig "android/soong/cc/config"
)

var (
	defaultBindgenFlags = []string{""}

	// bindgen should specify its own Clang revision so updating Clang isn't potentially blocked on bindgen failures.
	bindgenClangVersion  = "clang-r383902c"
	bindgenLibClangSoGit = "11git"

	//TODO(b/160803703) Use a prebuilt bindgen instead of the built bindgen.
	_ = pctx.SourcePathVariable("bindgenCmd", "out/host/${config.HostPrebuiltTag}/bin/bindgen")
	_ = pctx.SourcePathVariable("bindgenClang",
		"${ccConfig.ClangBase}/${config.HostPrebuiltTag}/"+bindgenClangVersion+"/bin/clang")
	_ = pctx.SourcePathVariable("bindgenLibClang",
		"${ccConfig.ClangBase}/${config.HostPrebuiltTag}/"+bindgenClangVersion+"/lib64/libclang.so."+bindgenLibClangSoGit)

	//TODO(ivanlozano) Switch this to RuleBuilder
	bindgen = pctx.AndroidStaticRule("bindgen",
		blueprint.RuleParams{
			Command: "CLANG_PATH=$bindgenClang LIBCLANG_PATH=$bindgenLibClang RUSTFMT=${config.RustBin}/rustfmt " +
				"$bindgenCmd $flags $in -o $out -- -MD -MF $out.d $cflags",
			CommandDeps: []string{"$bindgenCmd"},
			Deps:        blueprint.DepsGCC,
			Depfile:     "$out.d",
		},
		"flags", "cflags")
)

func init() {
	android.RegisterModuleType("rust_bindgen", RustBindgenFactory)
}

var _ SourceProvider = (*bindgenDecorator)(nil)

type BindgenProperties struct {
	// The wrapper header file
	Wrapper_src *string `android:"path,arch_variant"`

	// list of bindgen-specific flags and options
	Flags []string `android:"arch_variant"`

	// list of clang flags required to correctly interpret the headers.
	Cflags []string `android:"arch_variant"`

	// list of directories relative to the Blueprints file that will
	// be added to the include path using -I
	Local_include_dirs []string `android:"arch_variant,variant_prepend"`

	// list of static libraries that provide headers for this binding.
	Static_libs []string `android:"arch_variant,variant_prepend"`

	// list of shared libraries that provide headers for this binding.
	Shared_libs []string `android:"arch_variant"`

	//TODO(b/161141999) Add support for headers from cc_library_header modules.
}

type bindgenDecorator struct {
	*baseSourceProvider

	Properties BindgenProperties
}

func (b *bindgenDecorator) libraryExports(ctx android.ModuleContext) (android.Paths, []string) {
	var libraryPaths android.Paths
	var libraryFlags []string

	for _, static_lib := range b.Properties.Static_libs {
		if dep, ok := ctx.GetDirectDepWithTag(static_lib, cc.StaticDepTag).(*cc.Module); ok {
			libraryPaths = append(libraryPaths, dep.ExportedIncludeDirs()...)
			libraryFlags = append(libraryFlags, dep.ExportedFlags()...)
		}
	}
	for _, shared_lib := range b.Properties.Shared_libs {
		if dep, ok := ctx.GetDirectDepWithTag(shared_lib, cc.SharedDepTag).(*cc.Module); ok {
			libraryPaths = append(libraryPaths, dep.ExportedIncludeDirs()...)
			libraryFlags = append(libraryFlags, dep.ExportedFlags()...)
		}
	}

	return libraryPaths, libraryFlags
}

func (b *bindgenDecorator) generateSource(ctx android.ModuleContext) android.Path {
	ccToolchain := ccConfig.FindToolchain(ctx.Os(), ctx.Arch())
	includes, exportedFlags := b.libraryExports(ctx)

	var cflags []string
	cflags = append(cflags, b.Properties.Cflags...)
	cflags = append(cflags, "-target "+ccToolchain.ClangTriple())
	cflags = append(cflags, strings.ReplaceAll(ccToolchain.ToolchainClangCflags(), "${config.", "${ccConfig."))
	cflags = append(cflags, exportedFlags...)
	for _, include := range includes {
		cflags = append(cflags, "-I"+include.String())
	}
	for _, include := range b.Properties.Local_include_dirs {
		cflags = append(cflags, "-I"+android.PathForModuleSrc(ctx, include).String())
	}

	bindgenFlags := defaultBindgenFlags
	bindgenFlags = append(bindgenFlags, strings.Join(b.Properties.Flags, " "))

	wrapperFile := android.OptionalPathForModuleSrc(ctx, b.Properties.Wrapper_src)
	if !wrapperFile.Valid() {
		ctx.PropertyErrorf("wrapper_src", "invalid path to wrapper source")
	}

	outputFile := android.PathForModuleOut(ctx, b.baseSourceProvider.getStem(ctx)+".rs")

	ctx.Build(pctx, android.BuildParams{
		Rule:        bindgen,
		Description: "bindgen " + wrapperFile.Path().Rel(),
		Output:      outputFile,
		Input:       wrapperFile.Path(),
		Implicits:   includes,
		Args: map[string]string{
			"flags":  strings.Join(bindgenFlags, " "),
			"cflags": strings.Join(cflags, " "),
		},
	})
	b.baseSourceProvider.outputFile = outputFile
	return outputFile
}

func (b *bindgenDecorator) sourceProviderProps() []interface{} {
	return append(b.baseSourceProvider.sourceProviderProps(),
		&b.Properties)
}

// rust_bindgen generates Rust FFI bindings to C libraries using bindgen given a wrapper header as the primary input.
// Bindgen has a number of flags to control the generated source, and additional flags can be passed to clang to ensure
// the header and generated source is appropriately handled.
func RustBindgenFactory() android.Module {
	module, _ := NewRustBindgen(android.HostAndDeviceSupported)
	return module.Init()
}

func NewRustBindgen(hod android.HostOrDeviceSupported) (*Module, *bindgenDecorator) {
	module := newModule(hod, android.MultilibBoth)

	bindgen := &bindgenDecorator{
		baseSourceProvider: NewSourceProvider(),
		Properties:         BindgenProperties{},
	}
	module.sourceProvider = bindgen

	return module, bindgen
}

func (b *bindgenDecorator) sourceProviderDeps(ctx DepsContext, deps Deps) Deps {
	deps = b.baseSourceProvider.sourceProviderDeps(ctx, deps)
	deps.SharedLibs = append(deps.SharedLibs, b.Properties.Shared_libs...)
	deps.StaticLibs = append(deps.StaticLibs, b.Properties.Static_libs...)
	return deps
}