Separate sdk membership support out of cc/library.go

Bug: 142918168
Test: m checkbuild
Change-Id: I4a7f2af8e0b41feca2b5a431b42ad03bbfe94b0c
diff --git a/cc/library_sdk_member.go b/cc/library_sdk_member.go
new file mode 100644
index 0000000..6b09c12
--- /dev/null
+++ b/cc/library_sdk_member.go
@@ -0,0 +1,320 @@
+// Copyright 2019 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 (
+	"path/filepath"
+	"reflect"
+
+	"android/soong/android"
+	"github.com/google/blueprint"
+)
+
+// This file contains support for using cc library modules within an sdk.
+
+var SharedLibrarySdkMemberType = &librarySdkMemberType{
+	prebuiltModuleType: "cc_prebuilt_library_shared",
+	linkTypes:          []string{"shared"},
+}
+
+var StaticLibrarySdkMemberType = &librarySdkMemberType{
+	prebuiltModuleType: "cc_prebuilt_library_static",
+	linkTypes:          []string{"static"},
+}
+
+type librarySdkMemberType struct {
+	prebuiltModuleType string
+
+	// The set of link types supported, set of "static", "shared".
+	linkTypes []string
+}
+
+func (mt *librarySdkMemberType) AddDependencies(mctx android.BottomUpMutatorContext, dependencyTag blueprint.DependencyTag, names []string) {
+	targets := mctx.MultiTargets()
+	for _, lib := range names {
+		for _, target := range targets {
+			name, version := StubsLibNameAndVersion(lib)
+			if version == "" {
+				version = LatestStubsVersionFor(mctx.Config(), name)
+			}
+			for _, linkType := range mt.linkTypes {
+				mctx.AddFarVariationDependencies(append(target.Variations(), []blueprint.Variation{
+					{Mutator: "image", Variation: android.CoreVariation},
+					{Mutator: "link", Variation: linkType},
+					{Mutator: "version", Variation: version},
+				}...), dependencyTag, name)
+			}
+		}
+	}
+}
+
+func (mt *librarySdkMemberType) IsInstance(module android.Module) bool {
+	_, ok := module.(*Module)
+	return ok
+}
+
+// copy exported header files and stub *.so files
+func (mt *librarySdkMemberType) BuildSnapshot(sdkModuleContext android.ModuleContext, builder android.SnapshotBuilder, member android.SdkMember) {
+	info := mt.organizeVariants(member)
+	buildSharedNativeLibSnapshot(sdkModuleContext, info, builder, member)
+}
+
+// Organize the variants by architecture.
+func (mt *librarySdkMemberType) organizeVariants(member android.SdkMember) *nativeLibInfo {
+	memberName := member.Name()
+	info := &nativeLibInfo{
+		name:       memberName,
+		memberType: mt,
+	}
+
+	for _, variant := range member.Variants() {
+		ccModule := variant.(*Module)
+
+		// Separate out the generated include dirs (which are arch specific) from the
+		// include dirs (which may not be).
+		exportedIncludeDirs, exportedGeneratedIncludeDirs := android.FilterPathListPredicate(
+			ccModule.ExportedIncludeDirs(), isGeneratedHeaderDirectory)
+
+		info.archVariantProperties = append(info.archVariantProperties, nativeLibInfoProperties{
+			name:                         memberName,
+			archType:                     ccModule.Target().Arch.ArchType.String(),
+			ExportedIncludeDirs:          exportedIncludeDirs,
+			ExportedGeneratedIncludeDirs: exportedGeneratedIncludeDirs,
+			ExportedSystemIncludeDirs:    ccModule.ExportedSystemIncludeDirs(),
+			ExportedFlags:                ccModule.ExportedFlags(),
+			exportedGeneratedHeaders:     ccModule.ExportedGeneratedHeaders(),
+			outputFile:                   ccModule.OutputFile().Path(),
+		})
+	}
+
+	// Initialize the unexported properties that will not be set during the
+	// extraction process.
+	info.commonProperties.name = memberName
+
+	// Extract common properties from the arch specific properties.
+	extractCommonProperties(&info.commonProperties, info.archVariantProperties)
+
+	return info
+}
+
+func isGeneratedHeaderDirectory(p android.Path) bool {
+	_, gen := p.(android.WritablePath)
+	return gen
+}
+
+// Extract common properties from a slice of property structures of the same type.
+//
+// All the property structures must be of the same type.
+// commonProperties - must be a pointer to the structure into which common properties will be added.
+// inputPropertiesSlice - must be a slice of input properties structures.
+//
+// Iterates over each exported field (capitalized name) and checks to see whether they
+// have the same value (using DeepEquals) across all the input properties. If it does not then no
+// change is made. Otherwise, the common value is stored in the field in the commonProperties
+// and the field in each of the input properties structure is set to its default value.
+func extractCommonProperties(commonProperties interface{}, inputPropertiesSlice interface{}) {
+	commonStructValue := reflect.ValueOf(commonProperties).Elem()
+	propertiesStructType := commonStructValue.Type()
+
+	// Create an empty structure from which default values for the field can be copied.
+	emptyStructValue := reflect.New(propertiesStructType).Elem()
+
+	for f := 0; f < propertiesStructType.NumField(); f++ {
+		// Check to see if all the structures have the same value for the field. The commonValue
+		// is nil on entry to the loop and if it is nil on exit then there is no common value,
+		// otherwise it points to the common value.
+		var commonValue *reflect.Value
+		sliceValue := reflect.ValueOf(inputPropertiesSlice)
+
+		for i := 0; i < sliceValue.Len(); i++ {
+			structValue := sliceValue.Index(i)
+			fieldValue := structValue.Field(f)
+			if !fieldValue.CanInterface() {
+				// The field is not exported so ignore it.
+				continue
+			}
+
+			if commonValue == nil {
+				// Use the first value as the commonProperties value.
+				commonValue = &fieldValue
+			} else {
+				// If the value does not match the current common value then there is
+				// no value in common so break out.
+				if !reflect.DeepEqual(fieldValue.Interface(), commonValue.Interface()) {
+					commonValue = nil
+					break
+				}
+			}
+		}
+
+		// If the fields all have a common value then store it in the common struct field
+		// and set the input struct's field to the empty value.
+		if commonValue != nil {
+			emptyValue := emptyStructValue.Field(f)
+			commonStructValue.Field(f).Set(*commonValue)
+			for i := 0; i < sliceValue.Len(); i++ {
+				structValue := sliceValue.Index(i)
+				fieldValue := structValue.Field(f)
+				fieldValue.Set(emptyValue)
+			}
+		}
+	}
+}
+
+func buildSharedNativeLibSnapshot(sdkModuleContext android.ModuleContext, info *nativeLibInfo, builder android.SnapshotBuilder, member android.SdkMember) {
+	// a function for emitting include dirs
+	addExportedDirCopyCommandsForNativeLibs := func(lib nativeLibInfoProperties) {
+		// Do not include ExportedGeneratedIncludeDirs in the list of directories whose
+		// contents are copied as they are copied from exportedGeneratedHeaders below.
+		includeDirs := lib.ExportedIncludeDirs
+		includeDirs = append(includeDirs, lib.ExportedSystemIncludeDirs...)
+		for _, dir := range includeDirs {
+			// lib.ArchType is "" for common properties.
+			targetDir := filepath.Join(lib.archType, nativeIncludeDir)
+
+			// TODO(jiyong) copy headers having other suffixes
+			headers, _ := sdkModuleContext.GlobWithDeps(dir.String()+"/**/*.h", nil)
+			for _, file := range headers {
+				src := android.PathForSource(sdkModuleContext, file)
+				dest := filepath.Join(targetDir, file)
+				builder.CopyToSnapshot(src, dest)
+			}
+		}
+
+		genHeaders := lib.exportedGeneratedHeaders
+		for _, file := range genHeaders {
+			// lib.ArchType is "" for common properties.
+			targetDir := filepath.Join(lib.archType, nativeGeneratedIncludeDir)
+
+			dest := filepath.Join(targetDir, lib.name, file.Rel())
+			builder.CopyToSnapshot(file, dest)
+		}
+	}
+
+	addExportedDirCopyCommandsForNativeLibs(info.commonProperties)
+
+	// for each architecture
+	for _, av := range info.archVariantProperties {
+		builder.CopyToSnapshot(av.outputFile, nativeLibraryPathFor(av))
+
+		addExportedDirCopyCommandsForNativeLibs(av)
+	}
+
+	info.generatePrebuiltLibrary(sdkModuleContext, builder, member)
+}
+
+func (info *nativeLibInfo) generatePrebuiltLibrary(sdkModuleContext android.ModuleContext, builder android.SnapshotBuilder, member android.SdkMember) {
+
+	// a function for emitting include dirs
+	addExportedDirsForNativeLibs := func(lib nativeLibInfoProperties, properties android.BpPropertySet, systemInclude bool) {
+		includeDirs := nativeIncludeDirPathsFor(lib, systemInclude)
+		if len(includeDirs) == 0 {
+			return
+		}
+		var propertyName string
+		if !systemInclude {
+			propertyName = "export_include_dirs"
+		} else {
+			propertyName = "export_system_include_dirs"
+		}
+		properties.AddProperty(propertyName, includeDirs)
+	}
+
+	pbm := builder.AddPrebuiltModule(member, info.memberType.prebuiltModuleType)
+
+	addExportedDirsForNativeLibs(info.commonProperties, pbm, false /*systemInclude*/)
+	addExportedDirsForNativeLibs(info.commonProperties, pbm, true /*systemInclude*/)
+
+	archProperties := pbm.AddPropertySet("arch")
+	for _, av := range info.archVariantProperties {
+		archTypeProperties := archProperties.AddPropertySet(av.archType)
+		archTypeProperties.AddProperty("srcs", []string{nativeLibraryPathFor(av)})
+
+		// export_* properties are added inside the arch: {<arch>: {...}} block
+		addExportedDirsForNativeLibs(av, archTypeProperties, false /*systemInclude*/)
+		addExportedDirsForNativeLibs(av, archTypeProperties, true /*systemInclude*/)
+	}
+	pbm.AddProperty("stl", "none")
+	pbm.AddProperty("system_shared_libs", []string{})
+}
+
+const (
+	nativeIncludeDir          = "include"
+	nativeGeneratedIncludeDir = "include_gen"
+	nativeStubDir             = "lib"
+)
+
+// path to the native library. Relative to <sdk_root>/<api_dir>
+func nativeLibraryPathFor(lib nativeLibInfoProperties) string {
+	return filepath.Join(lib.archType,
+		nativeStubDir, lib.outputFile.Base())
+}
+
+// paths to the include dirs of a native shared library. Relative to <sdk_root>/<api_dir>
+func nativeIncludeDirPathsFor(lib nativeLibInfoProperties, systemInclude bool) []string {
+	var result []string
+	var includeDirs []android.Path
+	if !systemInclude {
+		// Include the generated include dirs in the exported include dirs.
+		includeDirs = append(lib.ExportedIncludeDirs, lib.ExportedGeneratedIncludeDirs...)
+	} else {
+		includeDirs = lib.ExportedSystemIncludeDirs
+	}
+	for _, dir := range includeDirs {
+		var path string
+		if isGeneratedHeaderDirectory(dir) {
+			path = filepath.Join(nativeGeneratedIncludeDir, lib.name)
+		} else {
+			path = filepath.Join(nativeIncludeDir, dir.String())
+		}
+
+		// lib.ArchType is "" for common properties.
+		path = filepath.Join(lib.archType, path)
+		result = append(result, path)
+	}
+	return result
+}
+
+// nativeLibInfoProperties represents properties of a native lib
+//
+// The exported (capitalized) fields will be examined and may be changed during common value extraction.
+// The unexported fields will be left untouched.
+type nativeLibInfoProperties struct {
+	// The name of the library, is not exported as this must not be changed during optimization.
+	name string
+
+	// archType is not exported as if set (to a non default value) it is always arch specific.
+	// This is "" for common properties.
+	archType string
+
+	ExportedIncludeDirs          android.Paths
+	ExportedGeneratedIncludeDirs android.Paths
+	ExportedSystemIncludeDirs    android.Paths
+	ExportedFlags                []string
+
+	// exportedGeneratedHeaders is not exported as if set it is always arch specific.
+	exportedGeneratedHeaders android.Paths
+
+	// outputFile is not exported as it is always arch specific.
+	outputFile android.Path
+}
+
+// nativeLibInfo represents a collection of arch-specific modules having the same name
+type nativeLibInfo struct {
+	name                  string
+	memberType            *librarySdkMemberType
+	archVariantProperties []nativeLibInfoProperties
+	commonProperties      nativeLibInfoProperties
+}