Add prebuilt_build_tool to allow genrules to use prebuilt tools am: 13af8140bc

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1364950

Change-Id: Ia88bd5acfbe4afbbb31ceb3c681e1e24de558ec0

android/Android.bp

@@ -39,6 +39,7 @@ bootstrap_go_package {
         "paths.go",
         "phony.go",
         "prebuilt.go",
+        "prebuilt_build_tool.go",
         "proto.go",
         "register.go",
         "rule_builder.go",

android/defs.go

@@ -69,7 +69,7 @@ var (
 	// A symlink rule.
 	Symlink = pctx.AndroidStaticRule("Symlink",
 		blueprint.RuleParams{
-			Command:     "ln -f -s $fromPath $out",
+			Command:     "rm -f $out && ln -f -s $fromPath $out",
 			Description: "symlink $out",
 		},
 		"fromPath")

android/prebuilt_build_tool.go

@@ -0,0 +1,94 @@
+// Copyright 2020 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 android
+
+import (
+	"path"
+	"path/filepath"
+)
+
+func init() {
+	RegisterModuleType("prebuilt_build_tool", prebuiltBuildToolFactory)
+}
+
+type prebuiltBuildToolProperties struct {
+	// Source file to be executed for this build tool
+	Src *string `android:"path,arch_variant"`
+
+	// Extra files that should trigger rules using this tool to rebuild
+	Deps []string `android:"path,arch_variant"`
+}
+
+type prebuiltBuildTool struct {
+	ModuleBase
+	prebuilt Prebuilt
+
+	properties prebuiltBuildToolProperties
+
+	toolPath OptionalPath
+}
+
+func (t *prebuiltBuildTool) Name() string {
+	return t.prebuilt.Name(t.ModuleBase.Name())
+}
+
+func (t *prebuiltBuildTool) Prebuilt() *Prebuilt {
+	return &t.prebuilt
+}
+
+func (t *prebuiltBuildTool) DepsMutator(ctx BottomUpMutatorContext) {
+	if t.properties.Src == nil {
+		ctx.PropertyErrorf("src", "missing prebuilt source file")
+	}
+}
+
+func (t *prebuiltBuildTool) GenerateAndroidBuildActions(ctx ModuleContext) {
+	sourcePath := t.prebuilt.SingleSourcePath(ctx)
+	installedPath := PathForModuleOut(ctx, t.ModuleBase.Name())
+	deps := PathsForModuleSrc(ctx, t.properties.Deps)
+
+	relPath, err := filepath.Rel(path.Dir(installedPath.String()), sourcePath.String())
+	if err != nil {
+		ctx.ModuleErrorf("Unabled to generate symlink between %q and %q: %s", installedPath.String(), sourcePath.String())
+	}
+
+	ctx.Build(pctx, BuildParams{
+		Rule:      Symlink,
+		Output:    installedPath,
+		Input:     sourcePath,
+		Implicits: deps,
+		Args: map[string]string{
+			"fromPath": relPath,
+		},
+	})
+
+	t.toolPath = OptionalPathForPath(installedPath)
+}
+
+func (t *prebuiltBuildTool) HostToolPath() OptionalPath {
+	return t.toolPath
+}
+
+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 {
+	module := &prebuiltBuildTool{}
+	module.AddProperties(&module.properties)
+	InitSingleSourcePrebuiltModule(module, &module.properties, "Src")
+	InitAndroidArchModule(module, HostSupportedNoCross, MultilibFirst)
+	return module
+}