Rust rlib vendor snapshot support.

Adds support for snapshotting Rust rlibs. This allows us
vendor-specific code that uses rlib-only linkage until dylib
snapshot support is added.

Bug: 184042776
Test: m nothing # new Soong tests pass
Test: Example test Rust vendor module builds
Test: m dist vendor-snapshot # includes rlibs
Change-Id: I4976d3e1efec0ee778cc97730d45be471dffb678

rust/snapshot_prebuilt.go

@@ -0,0 +1,121 @@
+// Copyright 2021 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 (
+	"android/soong/android"
+	"android/soong/cc"
+	"github.com/google/blueprint/proptools"
+)
+
+const (
+	snapshotRlibSuffix = "_rlib."
+)
+
+type snapshotLibraryDecorator struct {
+	cc.BaseSnapshotDecorator
+	*libraryDecorator
+	properties          cc.SnapshotLibraryProperties
+	sanitizerProperties struct {
+		CfiEnabled bool `blueprint:"mutated"`
+
+		// Library flags for cfi variant.
+		Cfi cc.SnapshotLibraryProperties `android:"arch_variant"`
+	}
+}
+
+func init() {
+	registerRustSnapshotModules(android.InitRegistrationContext)
+}
+
+func registerRustSnapshotModules(ctx android.RegistrationContext) {
+	cc.VendorSnapshotImageSingleton.RegisterAdditionalModule(ctx,
+		"vendor_snapshot_rlib", VendorSnapshotRlibFactory)
+}
+
+func snapshotLibraryFactory(image cc.SnapshotImage, moduleSuffix string) (*Module, *snapshotLibraryDecorator) {
+	module, library := NewRustLibrary(android.DeviceSupported)
+
+	module.sanitize = nil
+	library.stripper.StripProperties.Strip.None = proptools.BoolPtr(true)
+
+	prebuilt := &snapshotLibraryDecorator{
+		libraryDecorator: library,
+	}
+
+	module.compiler = prebuilt
+
+	prebuilt.Init(module, image, moduleSuffix)
+	module.AddProperties(
+		&prebuilt.properties,
+		&prebuilt.sanitizerProperties,
+	)
+
+	return module, prebuilt
+}
+
+func (library *snapshotLibraryDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) android.Path {
+	var variant string
+	if library.static() {
+		variant = cc.SnapshotStaticSuffix
+	} else if library.shared() {
+		variant = cc.SnapshotSharedSuffix
+	} else if library.rlib() {
+		variant = cc.SnapshotRlibSuffix
+	}
+
+	if !library.dylib() {
+		// TODO(184042776): Remove this check when dylibs are supported in snapshots.
+		library.SetSnapshotAndroidMkSuffix(ctx, variant)
+	}
+
+	if !library.MatchesWithDevice(ctx.DeviceConfig()) {
+		return nil
+	}
+
+	return android.PathForModuleSrc(ctx, *library.properties.Src)
+}
+
+func (library *snapshotLibraryDecorator) rustdoc(ctx ModuleContext, flags Flags, deps PathDeps) android.OptionalPath {
+	return android.OptionalPath{}
+}
+
+// vendor_snapshot_rlib is a special prebuilt rlib library which is auto-generated by
+// development/vendor_snapshot/update.py. As a part of vendor snapshot, vendor_snapshot_rlib
+// overrides the vendor variant of the rust rlib library with the same name, if BOARD_VNDK_VERSION
+// is set.
+func VendorSnapshotRlibFactory() android.Module {
+	module, prebuilt := snapshotLibraryFactory(cc.VendorSnapshotImageSingleton, cc.SnapshotRlibSuffix)
+	prebuilt.libraryDecorator.BuildOnlyRlib()
+	prebuilt.libraryDecorator.setNoStdlibs()
+	return module.Init()
+}
+
+func (library *snapshotLibraryDecorator) MatchesWithDevice(config android.DeviceConfig) bool {
+	arches := config.Arches()
+	if len(arches) == 0 || arches[0].ArchType.String() != library.Arch() {
+		return false
+	}
+	if library.properties.Src == nil {
+		return false
+	}
+	return true
+}
+
+func (library *snapshotLibraryDecorator) IsSnapshotPrebuilt() bool {
+	return true
+}
+
+var _ cc.SnapshotInterface = (*snapshotLibraryDecorator)(nil)