1 files changed, 238 insertions, 0 deletions
diff --git a/rust/protobuf.go b/rust/protobuf.go
new file mode 100644
index 000000000..b91fea86e
--- /dev/null
+++ b/rust/protobuf.go
@@ -0,0 +1,238 @@
+// Copyright 2020 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 (
+	"fmt"
+	"strings"
+
+	"android/soong/android"
+)
+
+var (
+	defaultProtobufFlags = []string{""}
+)
+
+const (
+	grpcSuffix = "_grpc"
+)
+
+type PluginType int
+
+func init() {
+	android.RegisterModuleType("rust_protobuf", RustProtobufFactory)
+	android.RegisterModuleType("rust_protobuf_host", RustProtobufHostFactory)
+}
+
+var _ SourceProvider = (*protobufDecorator)(nil)
+
+type ProtobufProperties struct {
+	// List of relative paths to proto files that will be used to generate the source.
+	// Either this or grpc_protos must be defined.
+	Protos []string `android:"path,arch_variant"`
+
+	// List of relative paths to GRPC-containing proto files that will be used to generate the source.
+	// Either this or protos must be defined.
+	Grpc_protos []string `android:"path,arch_variant"`
+
+	// List of additional flags to pass to aprotoc
+	Proto_flags []string `android:"arch_variant"`
+
+	// List of libraries which export include paths required for this module
+	Header_libs []string `android:"arch_variant,variant_prepend"`
+}
+
+type protobufDecorator struct {
+	*BaseSourceProvider
+
+	Properties ProtobufProperties
+	protoNames []string
+	grpcNames  []string
+
+	grpcProtoFlags android.ProtoFlags
+	protoFlags     android.ProtoFlags
+}
+
+func (proto *protobufDecorator) GenerateSource(ctx ModuleContext, deps PathDeps) android.Path {
+	var protoFlags android.ProtoFlags
+	var grpcProtoFlags android.ProtoFlags
+	var commonProtoFlags []string
+
+	outDir := android.PathForModuleOut(ctx)
+	protoFiles := android.PathsForModuleSrc(ctx, proto.Properties.Protos)
+	grpcFiles := android.PathsForModuleSrc(ctx, proto.Properties.Grpc_protos)
+	protoPluginPath := ctx.Config().HostToolPath(ctx, "protoc-gen-rust")
+
+	commonProtoFlags = append(commonProtoFlags, defaultProtobufFlags...)
+	commonProtoFlags = append(commonProtoFlags, proto.Properties.Proto_flags...)
+	commonProtoFlags = append(commonProtoFlags, "--plugin=protoc-gen-rust="+protoPluginPath.String())
+
+	if len(protoFiles) > 0 {
+		protoFlags.OutTypeFlag = "--rust_out"
+		protoFlags.Flags = append(protoFlags.Flags, commonProtoFlags...)
+
+		protoFlags.Deps = append(protoFlags.Deps, protoPluginPath)
+	}
+
+	if len(grpcFiles) > 0 {
+		grpcPath := ctx.Config().HostToolPath(ctx, "grpc_rust_plugin")
+
+		grpcProtoFlags.OutTypeFlag = "--rust_out"
+		grpcProtoFlags.Flags = append(grpcProtoFlags.Flags, "--grpc_out="+outDir.String())
+		grpcProtoFlags.Flags = append(grpcProtoFlags.Flags, "--plugin=protoc-gen-grpc="+grpcPath.String())
+		grpcProtoFlags.Flags = append(grpcProtoFlags.Flags, commonProtoFlags...)
+
+		grpcProtoFlags.Deps = append(grpcProtoFlags.Deps, grpcPath, protoPluginPath)
+	}
+
+	if len(protoFiles) == 0 && len(grpcFiles) == 0 {
+		ctx.PropertyErrorf("protos",
+			"at least one protobuf must be defined in either protos or grpc_protos.")
+	}
+
+	// Add exported dependency include paths
+	for _, include := range deps.depIncludePaths {
+		protoFlags.Flags = append(protoFlags.Flags, "-I"+include.String())
+		grpcProtoFlags.Flags = append(grpcProtoFlags.Flags, "-I"+include.String())
+	}
+
+	stem := proto.BaseSourceProvider.getStem(ctx)
+
+	// The mod_stem.rs file is used to avoid collisions if this is not included as a crate.
+	stemFile := android.PathForModuleOut(ctx, "mod_"+stem+".rs")
+
+	// stemFile must be first here as the first path in BaseSourceProvider.OutputFiles is the library entry-point.
+	var outputs android.WritablePaths
+
+	rule := android.NewRuleBuilder(pctx, ctx)
+
+	for _, protoFile := range protoFiles {
+		// Since we're iterating over the protoFiles already, make sure they're not redeclared in grpcFiles
+		if android.InList(protoFile.String(), grpcFiles.Strings()) {
+			ctx.PropertyErrorf("protos",
+				"A proto can only be added once to either grpc_protos or protos. %q is declared in both properties",
+				protoFile.String())
+		}
+
+		protoName := strings.TrimSuffix(protoFile.Base(), ".proto")
+		proto.protoNames = append(proto.protoNames, protoName)
+
+		protoOut := android.PathForModuleOut(ctx, protoName+".rs")
+		depFile := android.PathForModuleOut(ctx, protoName+".d")
+
+		ruleOutputs := android.WritablePaths{protoOut, depFile}
+
+		android.ProtoRule(rule, protoFile, protoFlags, protoFlags.Deps, outDir, depFile, ruleOutputs)
+		outputs = append(outputs, ruleOutputs...)
+	}
+
+	for _, grpcFile := range grpcFiles {
+		grpcName := strings.TrimSuffix(grpcFile.Base(), ".proto")
+		proto.grpcNames = append(proto.grpcNames, grpcName)
+
+		// GRPC protos produce two files, a proto.rs and a proto_grpc.rs
+		protoOut := android.WritablePath(android.PathForModuleOut(ctx, grpcName+".rs"))
+		grpcOut := android.WritablePath(android.PathForModuleOut(ctx, grpcName+grpcSuffix+".rs"))
+		depFile := android.PathForModuleOut(ctx, grpcName+".d")
+
+		ruleOutputs := android.WritablePaths{protoOut, grpcOut, depFile}
+
+		android.ProtoRule(rule, grpcFile, grpcProtoFlags, grpcProtoFlags.Deps, outDir, depFile, ruleOutputs)
+		outputs = append(outputs, ruleOutputs...)
+	}
+
+	// Check that all proto base filenames are unique as outputs are written to the same directory.
+	baseFilenames := append(proto.protoNames, proto.grpcNames...)
+	if len(baseFilenames) != len(android.FirstUniqueStrings(baseFilenames)) {
+		ctx.PropertyErrorf("protos", "proto filenames must be unique across  'protos' and 'grpc_protos' "+
+			"to be used in the same rust_protobuf module. For example, foo.proto and src/foo.proto will conflict.")
+	}
+
+	android.WriteFileRule(ctx, stemFile, proto.genModFileContents())
+
+	rule.Build("protoc_"+ctx.ModuleName(), "protoc "+ctx.ModuleName())
+
+	// stemFile must be first here as the first path in BaseSourceProvider.OutputFiles is the library entry-point.
+	proto.BaseSourceProvider.OutputFiles = append(android.Paths{stemFile}, outputs.Paths()...)
+
+	// mod_stem.rs is the entry-point for our library modules, so this is what we return.
+	return stemFile
+}
+
+func (proto *protobufDecorator) genModFileContents() string {
+	lines := []string{
+		"// @Soong generated Source",
+	}
+	for _, protoName := range proto.protoNames {
+		lines = append(lines, fmt.Sprintf("pub mod %s;", protoName))
+	}
+
+	for _, grpcName := range proto.grpcNames {
+		lines = append(lines, fmt.Sprintf("pub mod %s;", grpcName))
+		lines = append(lines, fmt.Sprintf("pub mod %s%s;", grpcName, grpcSuffix))
+	}
+	if len(proto.grpcNames) > 0 {
+		lines = append(
+			lines,
+			"pub mod empty {",
+			"    pub use protobuf::well_known_types::Empty;",
+			"}")
+	}
+
+	return strings.Join(lines, "\n")
+}
+
+func (proto *protobufDecorator) SourceProviderProps() []interface{} {
+	return append(proto.BaseSourceProvider.SourceProviderProps(), &proto.Properties)
+}
+
+func (proto *protobufDecorator) SourceProviderDeps(ctx DepsContext, deps Deps) Deps {
+	deps = proto.BaseSourceProvider.SourceProviderDeps(ctx, deps)
+	deps.Rustlibs = append(deps.Rustlibs, "libprotobuf")
+	deps.HeaderLibs = append(deps.SharedLibs, proto.Properties.Header_libs...)
+
+	if len(proto.Properties.Grpc_protos) > 0 {
+		deps.Rustlibs = append(deps.Rustlibs, "libgrpcio", "libfutures")
+		deps.HeaderLibs = append(deps.HeaderLibs, "libprotobuf-cpp-full")
+	}
+
+	return deps
+}
+
+// rust_protobuf generates protobuf rust code from the provided proto file. This uses the protoc-gen-rust plugin for
+// protoc. Additional flags to the protoc command can be passed via the proto_flags property. This module type will
+// create library variants that can be used as a crate dependency by adding it to the rlibs, dylibs, and rustlibs
+// properties of other modules.
+func RustProtobufFactory() android.Module {
+	module, _ := NewRustProtobuf(android.HostAndDeviceSupported)
+	return module.Init()
+}
+
+// A host-only variant of rust_protobuf. Refer to rust_protobuf for more details.
+func RustProtobufHostFactory() android.Module {
+	module, _ := NewRustProtobuf(android.HostSupported)
+	return module.Init()
+}
+
+func NewRustProtobuf(hod android.HostOrDeviceSupported) (*Module, *protobufDecorator) {
+	protobuf := &protobufDecorator{
+		BaseSourceProvider: NewSourceProvider(),
+		Properties:         ProtobufProperties{},
+	}
+
+	module := NewSourceProviderModule(hod, protobuf, false)
+
+	return module, protobuf
+}