add rust_toolchain_rustc_prebuilt module type

Sandboxing the rust rules requires having explicit inputs for the rust
toolchain. This module type makes the rustc prebuilt and its
dependencies explicit as a module that can be depended on by all rust
rules.

Bug: 286077158
Test: rust sandboxing topic + go test
Change-Id: If2b80b32e329e6a6ee11ba824de868cf04714553

android/prebuilt_build_tool.go

@@ -17,7 +17,7 @@ package android
 import "path/filepath"
 
 func init() {
-	RegisterModuleType("prebuilt_build_tool", prebuiltBuildToolFactory)
+	RegisterModuleType("prebuilt_build_tool", NewPrebuiltBuildTool)
 }
 
 type prebuiltBuildToolProperties struct {
@@ -101,10 +101,6 @@ var _ HostToolProvider = &prebuiltBuildTool{}
 
 // prebuilt_build_tool is to declare prebuilts to be used during the build, particularly for use
 // in genrules with the "tools" property.
-func prebuiltBuildToolFactory() Module {
-	return NewPrebuiltBuildTool()
-}
-
 func NewPrebuiltBuildTool() Module {
 	module := &prebuiltBuildTool{}
 	module.AddProperties(&module.properties)

cc/testing.go

@@ -35,6 +35,7 @@ func RegisterRequiredBuildComponentsForTest(ctx android.RegistrationContext) {
 
 	multitree.RegisterApiImportsModule(ctx)
 
+	ctx.RegisterModuleType("prebuilt_build_tool", android.NewPrebuiltBuildTool)
 	ctx.RegisterModuleType("cc_benchmark", BenchmarkFactory)
 	ctx.RegisterModuleType("cc_object", ObjectFactory)
 	ctx.RegisterModuleType("cc_genrule", GenRuleFactory)

rust/toolchain_library.go

@@ -21,6 +21,8 @@ import (
 
 	"android/soong/android"
 	"android/soong/rust/config"
+
+	"github.com/google/blueprint/proptools"
 )
 
 // This module is used to compile the rust toolchain libraries
@@ -33,6 +35,8 @@ func init() {
 		rustToolchainLibraryRlibFactory)
 	android.RegisterModuleType("rust_toolchain_library_dylib",
 		rustToolchainLibraryDylibFactory)
+	android.RegisterModuleType("rust_toolchain_rustc_prebuilt",
+		rustToolchainRustcPrebuiltFactory)
 }
 
 type toolchainLibraryProperties struct {
@@ -101,3 +105,47 @@ func rustSetToolchainSource(ctx android.LoadHookContext) {
 func GetRustPrebuiltVersion(ctx android.LoadHookContext) string {
 	return ctx.AConfig().GetenvWithDefault("RUST_PREBUILTS_VERSION", config.RustDefaultVersion)
 }
+
+type toolchainRustcPrebuiltProperties struct {
+	// path to rustc prebuilt, relative to the top of the toolchain source
+	Toolchain_prebuilt_src *string
+	// path to deps, relative to the top of the toolchain source
+	Toolchain_deps []string
+	// path to deps, relative to module directory
+	Deps []string
+}
+
+func rustToolchainRustcPrebuiltFactory() android.Module {
+	module := android.NewPrebuiltBuildTool()
+	module.AddProperties(&toolchainRustcPrebuiltProperties{})
+	android.AddLoadHook(module, func(ctx android.LoadHookContext) {
+		var toolchainProps *toolchainRustcPrebuiltProperties
+		for _, p := range ctx.Module().GetProperties() {
+			toolchainProperties, ok := p.(*toolchainRustcPrebuiltProperties)
+			if ok {
+				toolchainProps = toolchainProperties
+			}
+		}
+
+		if toolchainProps.Toolchain_prebuilt_src == nil {
+			ctx.PropertyErrorf("toolchain_prebuilt_src", "must set path to rustc prebuilt")
+		}
+
+		prefix := "linux-x86/" + GetRustPrebuiltVersion(ctx)
+		deps := make([]string, 0, len(toolchainProps.Toolchain_deps)+len(toolchainProps.Deps))
+		for _, d := range toolchainProps.Toolchain_deps {
+			deps = append(deps, path.Join(prefix, d))
+		}
+		deps = append(deps, toolchainProps.Deps...)
+
+		props := struct {
+			Src  *string
+			Deps []string
+		}{
+			Src:  proptools.StringPtr(path.Join(prefix, *toolchainProps.Toolchain_prebuilt_src)),
+			Deps: deps,
+		}
+		ctx.AppendProperties(&props)
+	})
+	return module
+}