Install VNDK snapshot libraries for system build

When BOARD_VNDK_VERSION := <VNDK version>, or
PRODUCT_EXTRA_VNDK_VERSIONS includes the needed <VNDK version> list,
the prebuilt VNDK libs in prebuilts/vndk/ directory will be
installed.

Each prebuilt VNDK module uses "vndk_prebuilt_shared" for shared
VNDK/VNDK-SP libs.

Following is the sample configuration of a vndk snapshot module:
vndk_prebuilt_shared {
    name: "libfoo",
    version: "27",
    vendor_available: true,
    vndk: {
        enabled: true,
    },
    arch: {
        arm64: {
            srcs: ["arm/lib64/libfoo.so"],
        },
        arm: {
            srcs: ["arm/lib/libfoo.so"],
        },
    },
}

The Android.bp for the snapshot modules will be auto-generated by a
script.

Bug: 38304393
Bug: 65377115
Bug: 68123344
Test: set BOARD_VNDK_VERSION := 27
      copy a snapshot for v27
      build with make command

Change-Id: Ib93107530dbabb4a24583f4d6e4f0c513c9adfec

cc/vndk_prebuilt.go

@@ -0,0 +1,140 @@
+// 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 (
+	"strings"
+
+	"android/soong/android"
+)
+
+var (
+	vndkSuffix = ".vndk."
+)
+
+// Creates vndk prebuilts that include the VNDK version.
+//
+// Example:
+//
+// vndk_prebuilt_shared {
+//     name: "libfoo",
+//     version: "27.1.0",
+//     vendor_available: true,
+//     vndk: {
+//         enabled: true,
+//     },
+//     export_include_dirs: ["include/external/libfoo/vndk_include"],
+//     arch: {
+//         arm64: {
+//             srcs: ["arm/lib64/libfoo.so"],
+//         },
+//         arm: {
+//             srcs: ["arm/lib/libfoo.so"],
+//         },
+//     },
+// }
+//
+type vndkPrebuiltProperties struct {
+	// VNDK snapshot version that is formated as {SDK_ver}.{Major}.{Minor}.
+	Version string
+
+	// Prebuilt files for each arch.
+	Srcs []string `android:"arch_variant"`
+}
+
+type vndkPrebuiltLibraryDecorator struct {
+	*libraryDecorator
+	properties vndkPrebuiltProperties
+}
+
+func (p *vndkPrebuiltLibraryDecorator) Name(name string) string {
+	return name + vndkSuffix + p.version()
+}
+
+func (p *vndkPrebuiltLibraryDecorator) version() string {
+	return p.properties.Version
+}
+
+func (p *vndkPrebuiltLibraryDecorator) linkerFlags(ctx ModuleContext, flags Flags) Flags {
+	p.libraryDecorator.libName = strings.TrimSuffix(ctx.ModuleName(), vndkSuffix+p.version())
+	return p.libraryDecorator.linkerFlags(ctx, flags)
+}
+
+func (p *vndkPrebuiltLibraryDecorator) singleSourcePath(ctx ModuleContext) android.Path {
+	if len(p.properties.Srcs) == 0 {
+		ctx.PropertyErrorf("srcs", "missing prebuilt source file")
+		return nil
+	}
+
+	if len(p.properties.Srcs) > 1 {
+		ctx.PropertyErrorf("srcs", "multiple prebuilt source files")
+		return nil
+	}
+
+	return android.PathForModuleSrc(ctx, p.properties.Srcs[0])
+}
+
+func (p *vndkPrebuiltLibraryDecorator) link(ctx ModuleContext,
+	flags Flags, deps PathDeps, objs Objects) android.Path {
+	if len(p.properties.Srcs) > 0 && p.shared() {
+		// current VNDK prebuilts are only shared libs.
+		return p.singleSourcePath(ctx)
+	}
+	return nil
+}
+
+func (p *vndkPrebuiltLibraryDecorator) install(ctx ModuleContext, file android.Path) {
+	if p.shared() {
+		if ctx.Device() && ctx.useVndk() {
+			if ctx.isVndkSp() {
+				p.baseInstaller.subDir = "vndk-sp-" + p.version()
+			} else if ctx.isVndk() {
+				p.baseInstaller.subDir = "vndk-" + p.version()
+			}
+		}
+		p.baseInstaller.install(ctx, file)
+	}
+}
+
+func vndkPrebuiltSharedLibrary() *Module {
+	module, library := NewLibrary(android.DeviceSupported)
+	library.BuildOnlyShared()
+	module.stl = nil
+	module.sanitize = nil
+	library.StripProperties.Strip.None = BoolPtr(true)
+
+	prebuilt := &vndkPrebuiltLibraryDecorator{
+		libraryDecorator: library,
+	}
+
+	module.compiler = nil
+	module.linker = prebuilt
+	module.installer = prebuilt
+
+	module.AddProperties(
+		&prebuilt.properties,
+	)
+
+	return module
+}
+
+func vndkPrebuiltSharedFactory() android.Module {
+	module := vndkPrebuiltSharedLibrary()
+	return module.Init()
+}
+
+func init() {
+	android.RegisterModuleType("vndk_prebuilt_shared", vndkPrebuiltSharedFactory)
+}