bp2build/build_conversion.go - platform/build/soong - Git at Google

 // Copyright 2020 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 bp2build

 import (
 	"android/soong/android"
 	"fmt"
 	"reflect"
 	"strings"

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

 type BazelAttributes struct {
 	Attrs map[string]string
 }

 type BazelTarget struct {
 	name    string
 	content string
 }

 type bpToBuildContext interface {
 	ModuleName(module blueprint.Module) string
 	ModuleDir(module blueprint.Module) string
 	ModuleSubDir(module blueprint.Module) string
 	ModuleType(module blueprint.Module) string

 	VisitAllModules(visit func(blueprint.Module))
 	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
 }

 type CodegenContext struct {
 	config  android.Config
 	context android.Context
 }

 func (ctx CodegenContext) AddNinjaFileDeps(...string) {}
 func (ctx CodegenContext) Config() android.Config     { return ctx.config }
 func (ctx CodegenContext) Context() android.Context   { return ctx.context }

 // NewCodegenContext creates a wrapper context that conforms to PathContext for
 // writing BUILD files in the output directory.
 func NewCodegenContext(config android.Config, context android.Context) CodegenContext {
 	return CodegenContext{
 		context: context,
 		config:  config,
 	}
 }

 // props is an unsorted map. This function ensures that
 // the generated attributes are sorted to ensure determinism.
 func propsToAttributes(props map[string]string) string {
 	var attributes string
 	for _, propName := range android.SortedStringKeys(props) {
 		if shouldGenerateAttribute(propName) {
 			attributes += fmt.Sprintf("    %s = %s,\n", propName, props[propName])
 		}
 	}
 	return attributes
 }

 func GenerateSoongModuleTargets(ctx bpToBuildContext) map[string][]BazelTarget {
 	buildFileToTargets := make(map[string][]BazelTarget)
 	ctx.VisitAllModules(func(m blueprint.Module) {
 		dir := ctx.ModuleDir(m)
 		t := generateSoongModuleTarget(ctx, m)
 		buildFileToTargets[ctx.ModuleDir(m)] = append(buildFileToTargets[dir], t)
 	})
 	return buildFileToTargets
 }

 // Convert a module and its deps and props into a Bazel macro/rule
 // representation in the BUILD file.
 func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) BazelTarget {
 	props := getBuildProperties(ctx, m)

 	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
 	// items, if the modules are added using different DependencyTag. Figure
 	// out the implications of that.
 	depLabels := map[string]bool{}
 	if aModule, ok := m.(android.Module); ok {
 		ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
 			depLabels[qualifiedTargetLabel(ctx, depModule)] = true
 		})
 	}
 	attributes := propsToAttributes(props.Attrs)

 	depLabelList := "[\n"
 	for depLabel, _ := range depLabels {
 		depLabelList += fmt.Sprintf("        %q,\n", depLabel)
 	}
 	depLabelList += "    ]"

 	targetName := targetNameWithVariant(ctx, m)
 	return BazelTarget{
 		name: targetName,
 		content: fmt.Sprintf(
 			soongModuleTarget,
 			targetName,
 			ctx.ModuleName(m),
 			canonicalizeModuleType(ctx.ModuleType(m)),
 			ctx.ModuleSubDir(m),
 			depLabelList,
 			attributes),
 	}
 }

 func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) BazelAttributes {
 	var allProps map[string]string
 	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
 	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
 	if aModule, ok := m.(android.Module); ok {
 		allProps = ExtractModuleProperties(aModule)
 	}

 	return BazelAttributes{
 		Attrs: allProps,
 	}
 }

 // Generically extract module properties and types into a map, keyed by the module property name.
 func ExtractModuleProperties(aModule android.Module) map[string]string {
 	ret := map[string]string{}

 	// Iterate over this android.Module's property structs.
 	for _, properties := range aModule.GetProperties() {
 		propertiesValue := reflect.ValueOf(properties)
 		// Check that propertiesValue is a pointer to the Properties struct, like
 		// *cc.BaseLinkerProperties or *java.CompilerProperties.
 		//
 		// propertiesValue can also be type-asserted to the structs to
 		// manipulate internal props, if needed.
 		if isStructPtr(propertiesValue.Type()) {
 			structValue := propertiesValue.Elem()
 			for k, v := range extractStructProperties(structValue, 0) {
 				ret[k] = v
 			}
 		} else {
 			panic(fmt.Errorf(
 				"properties must be a pointer to a struct, got %T",
 				propertiesValue.Interface()))
 		}
 	}

 	return ret
 }

 func isStructPtr(t reflect.Type) bool {
 	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
 }

 // prettyPrint a property value into the equivalent Starlark representation
 // recursively.
 func prettyPrint(propertyValue reflect.Value, indent int) (string, error) {
 	if isZero(propertyValue) {
 		// A property value being set or unset actually matters -- Soong does set default
 		// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
 		// https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
 		//
 		// In Bazel-parlance, we would use "attr.<type>(default = <default value>)" to set the default
 		// value of unset attributes.
 		return "", nil
 	}

 	var ret string
 	switch propertyValue.Kind() {
 	case reflect.String:
 		ret = fmt.Sprintf("\"%v\"", escapeString(propertyValue.String()))
 	case reflect.Bool:
 		ret = strings.Title(fmt.Sprintf("%v", propertyValue.Interface()))
 	case reflect.Int, reflect.Uint, reflect.Int64:
 		ret = fmt.Sprintf("%v", propertyValue.Interface())
 	case reflect.Ptr:
 		return prettyPrint(propertyValue.Elem(), indent)
 	case reflect.Slice:
 		ret = "[\n"
 		for i := 0; i < propertyValue.Len(); i++ {
 			indexedValue, err := prettyPrint(propertyValue.Index(i), indent+1)
 			if err != nil {
 				return "", err
 			}

 			if indexedValue != "" {
 				ret += makeIndent(indent + 1)
 				ret += indexedValue
 				ret += ",\n"
 			}
 		}
 		ret += makeIndent(indent)
 		ret += "]"
 	case reflect.Struct:
 		ret = "{\n"
 		// Sort and print the struct props by the key.
 		structProps := extractStructProperties(propertyValue, indent)
 		for _, k := range android.SortedStringKeys(structProps) {
 			ret += makeIndent(indent + 1)
 			ret += fmt.Sprintf("%q: %s,\n", k, structProps[k])
 		}
 		ret += makeIndent(indent)
 		ret += "}"
 	case reflect.Interface:
 		// TODO(b/164227191): implement pretty print for interfaces.
 		// Interfaces are used for for arch, multilib and target properties.
 		return "", nil
 	default:
 		return "", fmt.Errorf(
 			"unexpected kind for property struct field: %s", propertyValue.Kind())
 	}
 	return ret, nil
 }

 // Converts a reflected property struct value into a map of property names and property values,
 // which each property value correctly pretty-printed and indented at the right nest level,
 // since property structs can be nested. In Starlark, nested structs are represented as nested
 // dicts: https://docs.bazel.build/skylark/lib/dict.html
 func extractStructProperties(structValue reflect.Value, indent int) map[string]string {
 	if structValue.Kind() != reflect.Struct {
 		panic(fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind()))
 	}

 	ret := map[string]string{}
 	structType := structValue.Type()
 	for i := 0; i < structValue.NumField(); i++ {
 		field := structType.Field(i)
 		if shouldSkipStructField(field) {
 			continue
 		}

 		fieldValue := structValue.Field(i)
 		if isZero(fieldValue) {
 			// Ignore zero-valued fields
 			continue
 		}

 		propertyName := proptools.PropertyNameForField(field.Name)
 		prettyPrintedValue, err := prettyPrint(fieldValue, indent+1)
 		if err != nil {
 			panic(
 				fmt.Errorf(
 					"Error while parsing property: %q. %s",
 					propertyName,
 					err))
 		}
 		if prettyPrintedValue != "" {
 			ret[propertyName] = prettyPrintedValue
 		}
 	}

 	return ret
 }

 func isZero(value reflect.Value) bool {
 	switch value.Kind() {
 	case reflect.Func, reflect.Map, reflect.Slice:
 		return value.IsNil()
 	case reflect.Array:
 		valueIsZero := true
 		for i := 0; i < value.Len(); i++ {
 			valueIsZero = valueIsZero && isZero(value.Index(i))
 		}
 		return valueIsZero
 	case reflect.Struct:
 		valueIsZero := true
 		for i := 0; i < value.NumField(); i++ {
 			if value.Field(i).CanSet() {
 				valueIsZero = valueIsZero && isZero(value.Field(i))
 			}
 		}
 		return valueIsZero
 	case reflect.Ptr:
 		if !value.IsNil() {
 			return isZero(reflect.Indirect(value))
 		} else {
 			return true
 		}
 	default:
 		zeroValue := reflect.Zero(value.Type())
 		result := value.Interface() == zeroValue.Interface()
 		return result
 	}
 }

 func escapeString(s string) string {
 	s = strings.ReplaceAll(s, "\\", "\\\\")
 	return strings.ReplaceAll(s, "\"", "\\\"")
 }

 func makeIndent(indent int) string {
 	if indent < 0 {
 		panic(fmt.Errorf("indent column cannot be less than 0, but got %d", indent))
 	}
 	return strings.Repeat("    ", indent)
 }

 func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
 	name := ""
 	if c.ModuleSubDir(logicModule) != "" {
 		// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
 		name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
 	} else {
 		name = c.ModuleName(logicModule)
 	}

 	return strings.Replace(name, "//", "", 1)
 }

 func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
 	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
 }
	// Copyright 2020 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 bp2build

	import (
	"android/soong/android"
	"fmt"
	"reflect"
	"strings"

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

	type BazelAttributes struct {
	Attrs map[string]string
	}

	type BazelTarget struct {
	name string
	content string
	}

	type bpToBuildContext interface {
	ModuleName(module blueprint.Module) string
	ModuleDir(module blueprint.Module) string
	ModuleSubDir(module blueprint.Module) string
	ModuleType(module blueprint.Module) string

	VisitAllModules(visit func(blueprint.Module))
	VisitDirectDeps(module blueprint.Module, visit func(blueprint.Module))
	}

	type CodegenContext struct {
	config android.Config
	context android.Context
	}

	func (ctx CodegenContext) AddNinjaFileDeps(...string) {}
	func (ctx CodegenContext) Config() android.Config { return ctx.config }
	func (ctx CodegenContext) Context() android.Context { return ctx.context }

	// NewCodegenContext creates a wrapper context that conforms to PathContext for
	// writing BUILD files in the output directory.
	func NewCodegenContext(config android.Config, context android.Context) CodegenContext {
	return CodegenContext{
	context: context,
	config: config,
	}
	}

	// props is an unsorted map. This function ensures that
	// the generated attributes are sorted to ensure determinism.
	func propsToAttributes(props map[string]string) string {
	var attributes string
	for _, propName := range android.SortedStringKeys(props) {
	if shouldGenerateAttribute(propName) {
	attributes += fmt.Sprintf(" %s = %s,\n", propName, props[propName])
	}
	}
	return attributes
	}

	func GenerateSoongModuleTargets(ctx bpToBuildContext) map[string][]BazelTarget {
	buildFileToTargets := make(map[string][]BazelTarget)
	ctx.VisitAllModules(func(m blueprint.Module) {
	dir := ctx.ModuleDir(m)
	t := generateSoongModuleTarget(ctx, m)
	buildFileToTargets[ctx.ModuleDir(m)] = append(buildFileToTargets[dir], t)
	})
	return buildFileToTargets
	}

	// Convert a module and its deps and props into a Bazel macro/rule
	// representation in the BUILD file.
	func generateSoongModuleTarget(ctx bpToBuildContext, m blueprint.Module) BazelTarget {
	props := getBuildProperties(ctx, m)

	// TODO(b/163018919): DirectDeps can have duplicate (module, variant)
	// items, if the modules are added using different DependencyTag. Figure
	// out the implications of that.
	depLabels := map[string]bool{}
	if aModule, ok := m.(android.Module); ok {
	ctx.VisitDirectDeps(aModule, func(depModule blueprint.Module) {
	depLabels[qualifiedTargetLabel(ctx, depModule)] = true
	})
	}
	attributes := propsToAttributes(props.Attrs)

	depLabelList := "[\n"
	for depLabel, _ := range depLabels {
	depLabelList += fmt.Sprintf(" %q,\n", depLabel)
	}
	depLabelList += " ]"

	targetName := targetNameWithVariant(ctx, m)
	return BazelTarget{
	name: targetName,
	content: fmt.Sprintf(
	soongModuleTarget,
	targetName,
	ctx.ModuleName(m),
	canonicalizeModuleType(ctx.ModuleType(m)),
	ctx.ModuleSubDir(m),
	depLabelList,
	attributes),
	}
	}

	func getBuildProperties(ctx bpToBuildContext, m blueprint.Module) BazelAttributes {
	var allProps map[string]string
	// TODO: this omits properties for blueprint modules (blueprint_go_binary,
	// bootstrap_go_binary, bootstrap_go_package), which will have to be handled separately.
	if aModule, ok := m.(android.Module); ok {
	allProps = ExtractModuleProperties(aModule)
	}

	return BazelAttributes{
	Attrs: allProps,
	}
	}

	// Generically extract module properties and types into a map, keyed by the module property name.
	func ExtractModuleProperties(aModule android.Module) map[string]string {
	ret := map[string]string{}

	// Iterate over this android.Module's property structs.
	for _, properties := range aModule.GetProperties() {
	propertiesValue := reflect.ValueOf(properties)
	// Check that propertiesValue is a pointer to the Properties struct, like
	// cc.BaseLinkerProperties or java.CompilerProperties.
	//
	// propertiesValue can also be type-asserted to the structs to
	// manipulate internal props, if needed.
	if isStructPtr(propertiesValue.Type()) {
	structValue := propertiesValue.Elem()
	for k, v := range extractStructProperties(structValue, 0) {
	ret[k] = v
	}
	} else {
	panic(fmt.Errorf(
	"properties must be a pointer to a struct, got %T",
	propertiesValue.Interface()))
	}
	}

	return ret
	}

	func isStructPtr(t reflect.Type) bool {
	return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
	}

	// prettyPrint a property value into the equivalent Starlark representation
	// recursively.
	func prettyPrint(propertyValue reflect.Value, indent int) (string, error) {
	if isZero(propertyValue) {
	// A property value being set or unset actually matters -- Soong does set default
	// values for unset properties, like system_shared_libs = ["libc", "libm", "libdl"] at
	// https://cs.android.com/android/platform/superproject/+/master:build/soong/cc/linker.go;l=281-287;drc=f70926eef0b9b57faf04c17a1062ce50d209e480
	//
	// In Bazel-parlance, we would use "attr.<type>(default = <default value>)" to set the default
	// value of unset attributes.
	return "", nil
	}

	var ret string
	switch propertyValue.Kind() {
	case reflect.String:
	ret = fmt.Sprintf("\"%v\"", escapeString(propertyValue.String()))
	case reflect.Bool:
	ret = strings.Title(fmt.Sprintf("%v", propertyValue.Interface()))
	case reflect.Int, reflect.Uint, reflect.Int64:
	ret = fmt.Sprintf("%v", propertyValue.Interface())
	case reflect.Ptr:
	return prettyPrint(propertyValue.Elem(), indent)
	case reflect.Slice:
	ret = "[\n"
	for i := 0; i < propertyValue.Len(); i++ {
	indexedValue, err := prettyPrint(propertyValue.Index(i), indent+1)
	if err != nil {
	return "", err
	}

	if indexedValue != "" {
	ret += makeIndent(indent + 1)
	ret += indexedValue
	ret += ",\n"
	}
	}
	ret += makeIndent(indent)
	ret += "]"
	case reflect.Struct:
	ret = "{\n"
	// Sort and print the struct props by the key.
	structProps := extractStructProperties(propertyValue, indent)
	for _, k := range android.SortedStringKeys(structProps) {
	ret += makeIndent(indent + 1)
	ret += fmt.Sprintf("%q: %s,\n", k, structProps[k])
	}
	ret += makeIndent(indent)
	ret += "}"
	case reflect.Interface:
	// TODO(b/164227191): implement pretty print for interfaces.
	// Interfaces are used for for arch, multilib and target properties.
	return "", nil
	default:
	return "", fmt.Errorf(
	"unexpected kind for property struct field: %s", propertyValue.Kind())
	}
	return ret, nil
	}

	// Converts a reflected property struct value into a map of property names and property values,
	// which each property value correctly pretty-printed and indented at the right nest level,
	// since property structs can be nested. In Starlark, nested structs are represented as nested
	// dicts: https://docs.bazel.build/skylark/lib/dict.html
	func extractStructProperties(structValue reflect.Value, indent int) map[string]string {
	if structValue.Kind() != reflect.Struct {
	panic(fmt.Errorf("Expected a reflect.Struct type, but got %s", structValue.Kind()))
	}

	ret := map[string]string{}
	structType := structValue.Type()
	for i := 0; i < structValue.NumField(); i++ {
	field := structType.Field(i)
	if shouldSkipStructField(field) {
	continue
	}

	fieldValue := structValue.Field(i)
	if isZero(fieldValue) {
	// Ignore zero-valued fields
	continue
	}

	propertyName := proptools.PropertyNameForField(field.Name)
	prettyPrintedValue, err := prettyPrint(fieldValue, indent+1)
	if err != nil {
	panic(
	fmt.Errorf(
	"Error while parsing property: %q. %s",
	propertyName,
	err))
	}
	if prettyPrintedValue != "" {
	ret[propertyName] = prettyPrintedValue
	}
	}

	return ret
	}

	func isZero(value reflect.Value) bool {
	switch value.Kind() {
	case reflect.Func, reflect.Map, reflect.Slice:
	return value.IsNil()
	case reflect.Array:
	valueIsZero := true
	for i := 0; i < value.Len(); i++ {
	valueIsZero = valueIsZero && isZero(value.Index(i))
	}
	return valueIsZero
	case reflect.Struct:
	valueIsZero := true
	for i := 0; i < value.NumField(); i++ {
	if value.Field(i).CanSet() {
	valueIsZero = valueIsZero && isZero(value.Field(i))
	}
	}
	return valueIsZero
	case reflect.Ptr:
	if !value.IsNil() {
	return isZero(reflect.Indirect(value))
	} else {
	return true
	}
	default:
	zeroValue := reflect.Zero(value.Type())
	result := value.Interface() == zeroValue.Interface()
	return result
	}
	}

	func escapeString(s string) string {
	s = strings.ReplaceAll(s, "\\", "\\\\")
	return strings.ReplaceAll(s, "\"", "\\\"")
	}

	func makeIndent(indent int) string {
	if indent < 0 {
	panic(fmt.Errorf("indent column cannot be less than 0, but got %d", indent))
	}
	return strings.Repeat(" ", indent)
	}

	func targetNameWithVariant(c bpToBuildContext, logicModule blueprint.Module) string {
	name := ""
	if c.ModuleSubDir(logicModule) != "" {
	// TODO(b/162720883): Figure out a way to drop the "--" variant suffixes.
	name = c.ModuleName(logicModule) + "--" + c.ModuleSubDir(logicModule)
	} else {
	name = c.ModuleName(logicModule)
	}

	return strings.Replace(name, "//", "", 1)
	}

	func qualifiedTargetLabel(c bpToBuildContext, logicModule blueprint.Module) string {
	return fmt.Sprintf("//%s:%s", c.ModuleDir(logicModule), targetNameWithVariant(c, logicModule))
	}