Add LLNDK support for the VNDK

Instead of using the NDK headers and libraries, add LL-NDK specific
headers and library stubs for VNDK users. This allows us to provide an
expanded liblog interface.

Test: aosp_arm; m -j
Test: Enable BOARD_VNDK_VERSION on aosp_arm; m -j
Test: Inspect out/soong/build.ninja before/after (w/o vndk)
Change-Id: Ic85f07fa10c695b5baab10c41f5e0ad38700bf3d

cc/llndk_library.go

@@ -0,0 +1,169 @@
+// Copyright 2017 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"
+	"strings"
+
+	"github.com/google/blueprint"
+
+	"android/soong/android"
+)
+
+var (
+	llndkLibrarySuffix = ".llndk"
+)
+
+// Creates a stub shared library based on the provided version file.
+//
+// The name of the generated file will be based on the module name by stripping
+// the ".llndk" suffix from the module name. Module names must end with ".llndk"
+// (as a convention to allow soong to guess the LL-NDK name of a dependency when
+// needed). "libfoo.llndk" will generate "libfoo.so".
+//
+// Example:
+//
+// llndk_library {
+//     name: "libfoo.llndk",
+//     symbol_file: "libfoo.map.txt",
+//     export_include_dirs: ["include_vndk"],
+// }
+//
+type llndkLibraryProperties struct {
+	// Relative path to the symbol map.
+	// An example file can be seen here: TODO(danalbert): Make an example.
+	Symbol_file string
+
+	// Whether to export any headers as -isystem instead of -I. Mainly for use by
+	// bionic/libc.
+	Export_headers_as_system bool
+
+	// Which headers to process with versioner. This really only handles
+	// bionic/libc/include right now.
+	Export_preprocessed_headers []string
+
+	// Whether the system library uses symbol versions.
+	Unversioned bool
+}
+
+type llndkStubDecorator struct {
+	*libraryDecorator
+
+	Properties llndkLibraryProperties
+
+	exportHeadersTimestamp android.OptionalPath
+	versionScriptPath      android.ModuleGenPath
+}
+
+func (stub *llndkStubDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) Objects {
+	if !strings.HasSuffix(ctx.ModuleName(), llndkLibrarySuffix) {
+		ctx.ModuleErrorf("llndk_library modules names must be suffixed with %q\n",
+			llndkLibrarySuffix)
+	}
+	objs, versionScript := compileStubLibrary(ctx, flags, stub.Properties.Symbol_file, "current", "--vndk")
+	stub.versionScriptPath = versionScript
+	return objs
+}
+
+func (stub *llndkStubDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
+	return Deps{}
+}
+
+func (stub *llndkStubDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
+	stub.libraryDecorator.libName = strings.TrimSuffix(ctx.ModuleName(),
+		llndkLibrarySuffix)
+	return stub.libraryDecorator.linkerFlags(ctx, flags)
+}
+
+func (stub *llndkStubDecorator) processHeaders(ctx ModuleContext, srcHeaderDir string, outDir android.ModuleGenPath) android.Path {
+	srcDir := android.PathForModuleSrc(ctx, srcHeaderDir)
+	srcFiles := ctx.Glob(filepath.Join(srcDir.String(), "**/*.h"), nil)
+
+	var installPaths []android.WritablePath
+	for _, header := range srcFiles {
+		headerDir := filepath.Dir(header.String())
+		relHeaderDir, err := filepath.Rel(srcDir.String(), headerDir)
+		if err != nil {
+			ctx.ModuleErrorf("filepath.Rel(%q, %q) failed: %s",
+				srcDir.String(), headerDir, err)
+			continue
+		}
+
+		installPaths = append(installPaths, outDir.Join(ctx, relHeaderDir, header.Base()))
+	}
+
+	return processHeadersWithVersioner(ctx, srcDir, outDir, srcFiles, installPaths)
+}
+
+func (stub *llndkStubDecorator) link(ctx ModuleContext, flags Flags, deps PathDeps,
+	objs Objects) android.Path {
+
+	if !stub.Properties.Unversioned {
+		linkerScriptFlag := "-Wl,--version-script," + stub.versionScriptPath.String()
+		flags.LdFlags = append(flags.LdFlags, linkerScriptFlag)
+	}
+
+	if len(stub.Properties.Export_preprocessed_headers) > 0 {
+		genHeaderOutDir := android.PathForModuleGen(ctx, "include")
+
+		var timestampFiles android.Paths
+		for _, dir := range stub.Properties.Export_preprocessed_headers {
+			timestampFiles = append(timestampFiles, stub.processHeaders(ctx, dir, genHeaderOutDir))
+		}
+
+		includePrefix := "-I "
+		if stub.Properties.Export_headers_as_system {
+			includePrefix = "-isystem "
+		}
+
+		stub.reexportFlags([]string{includePrefix + " " + genHeaderOutDir.String()})
+		stub.reexportDeps(timestampFiles)
+	}
+
+	if stub.Properties.Export_headers_as_system {
+		stub.exportIncludes(ctx, "-isystem")
+		stub.libraryDecorator.flagExporter.Properties.Export_include_dirs = []string{}
+	}
+
+	return stub.libraryDecorator.link(ctx, flags, deps, objs)
+}
+
+func newLLndkStubLibrary() (*Module, []interface{}) {
+	module, library := NewLibrary(android.DeviceSupported)
+	library.BuildOnlyShared()
+	module.stl = nil
+	module.sanitize = nil
+	library.StripProperties.Strip.None = true
+
+	stub := &llndkStubDecorator{
+		libraryDecorator: library,
+	}
+	module.compiler = stub
+	module.linker = stub
+	module.installer = nil
+
+	return module, []interface{}{&stub.Properties, &library.MutatedProperties, &library.flagExporter.Properties}
+}
+
+func llndkLibraryFactory() (blueprint.Module, []interface{}) {
+	module, properties := newLLndkStubLibrary()
+	return android.InitAndroidArchModule(module, android.DeviceSupported,
+		android.MultilibBoth, properties...)
+}
+
+func init() {
+	android.RegisterModuleType("llndk_library", llndkLibraryFactory)
+}