Merge changes from topic "reland-rust-sbox-1" into main

* changes:
  Revert^2 "conditionally escape rule builder command"
  Revert^4 "allow Ninja variables in RuleBuilder API"
  Revert^4 "add crate_root property to rust modules"
  Revert^4 "add rust_toolchain_rustc_prebuilt module type"
diff --git a/android/prebuilt_build_tool.go b/android/prebuilt_build_tool.go
index aeae20f..17b3230 100644
--- a/android/prebuilt_build_tool.go
+++ b/android/prebuilt_build_tool.go
@@ -17,7 +17,7 @@
 import "path/filepath"
 
 func init() {
-	RegisterModuleType("prebuilt_build_tool", prebuiltBuildToolFactory)
+	RegisterModuleType("prebuilt_build_tool", NewPrebuiltBuildTool)
 }
 
 type prebuiltBuildToolProperties struct {
@@ -101,10 +101,6 @@
 
 // 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)
diff --git a/android/rule_builder.go b/android/rule_builder.go
index 777c1cf..245b759 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -474,13 +474,23 @@
 		Inputs(depFiles.Paths())
 }
 
+// BuildWithNinjaVars adds the built command line to the build graph, with dependencies on Inputs and Tools, and output files for
+// Outputs. This function will not escape Ninja variables, so it may be used to write sandbox manifests using Ninja variables.
+func (r *RuleBuilder) BuildWithUnescapedNinjaVars(name string, desc string) {
+	r.build(name, desc, false)
+}
+
 // Build adds the built command line to the build graph, with dependencies on Inputs and Tools, and output files for
 // Outputs.
 func (r *RuleBuilder) Build(name string, desc string) {
+	r.build(name, desc, true)
+}
+
+func (r *RuleBuilder) build(name string, desc string, ninjaEscapeCommandString bool) {
 	name = ninjaNameEscape(name)
 
 	if len(r.missingDeps) > 0 {
-		r.ctx.Build(pctx, BuildParams{
+		r.ctx.Build(r.pctx, BuildParams{
 			Rule:        ErrorRule,
 			Outputs:     r.Outputs(),
 			Description: desc,
@@ -619,12 +629,35 @@
 				name, r.sboxManifestPath.String(), r.outDir.String())
 		}
 
-		// Create a rule to write the manifest as a the textproto.
+		// Create a rule to write the manifest as textproto.
 		pbText, err := prototext.Marshal(&manifest)
 		if err != nil {
 			ReportPathErrorf(r.ctx, "sbox manifest failed to marshal: %q", err)
 		}
-		WriteFileRule(r.ctx, r.sboxManifestPath, string(pbText))
+		if ninjaEscapeCommandString {
+			WriteFileRule(r.ctx, r.sboxManifestPath, string(pbText))
+		} else {
+			// We need  to have a rule to write files that is
+			// defined on the RuleBuilder's pctx in order to
+			// write Ninja variables in the string.
+			// The WriteFileRule function above rule can only write
+			// raw strings because it is defined on the android
+			// package's pctx, and it can't access variables defined
+			// in another context.
+			r.ctx.Build(r.pctx, BuildParams{
+				Rule: r.ctx.Rule(r.pctx, "unescapedWriteFile", blueprint.RuleParams{
+					Command:        `rm -rf ${out} && cat ${out}.rsp > ${out}`,
+					Rspfile:        "${out}.rsp",
+					RspfileContent: "${content}",
+					Description:    "write file",
+				}, "content"),
+				Output:      r.sboxManifestPath,
+				Description: "write sbox manifest " + r.sboxManifestPath.Base(),
+				Args: map[string]string{
+					"content": string(pbText),
+				},
+			})
+		}
 
 		// Generate a new string to use as the command line of the sbox rule.  This uses
 		// a RuleBuilderCommand as a convenience method of building the command line, then
@@ -723,9 +756,13 @@
 		pool = localPool
 	}
 
+	if ninjaEscapeCommandString {
+		commandString = proptools.NinjaEscape(commandString)
+	}
+
 	r.ctx.Build(r.pctx, BuildParams{
-		Rule: r.ctx.Rule(pctx, name, blueprint.RuleParams{
-			Command:        proptools.NinjaEscape(commandString),
+		Rule: r.ctx.Rule(r.pctx, name, blueprint.RuleParams{
+			Command:        commandString,
 			CommandDeps:    proptools.NinjaEscapeList(tools.Strings()),
 			Restat:         r.restat,
 			Rspfile:        proptools.NinjaEscape(rspFile),
diff --git a/android/rule_builder_test.go b/android/rule_builder_test.go
index 86647eb..a6b3a27 100644
--- a/android/rule_builder_test.go
+++ b/android/rule_builder_test.go
@@ -28,6 +28,17 @@
 	"android/soong/shared"
 )
 
+var (
+	pctx_ruleBuilderTest           = NewPackageContext("android/soong/rule_builder")
+	pctx_ruleBuilderTestSubContext = NewPackageContext("android/soong/rule_builder/config")
+)
+
+func init() {
+	pctx_ruleBuilderTest.Import("android/soong/rule_builder/config")
+	pctx_ruleBuilderTest.StaticVariable("cmdFlags", "${config.ConfigFlags}")
+	pctx_ruleBuilderTestSubContext.StaticVariable("ConfigFlags", "--some-clang-flag")
+}
+
 func builderContext() BuilderContext {
 	return BuilderContextForTesting(TestConfig("out", nil, "", map[string][]byte{
 		"ld":      nil,
@@ -496,11 +507,13 @@
 type testRuleBuilderModule struct {
 	ModuleBase
 	properties struct {
-		Srcs []string
+		Srcs  []string
+		Flags []string
 
-		Restat      bool
-		Sbox        bool
-		Sbox_inputs bool
+		Restat              bool
+		Sbox                bool
+		Sbox_inputs         bool
+		Unescape_ninja_vars bool
 	}
 }
 
@@ -518,8 +531,9 @@
 	rspFileContents2 := PathsForSource(ctx, []string{"rsp_in2"})
 	manifestPath := PathForModuleOut(ctx, "sbox.textproto")
 
-	testRuleBuilder_Build(ctx, in, implicit, orderOnly, validation, out, outDep, outDir,
-		manifestPath, t.properties.Restat, t.properties.Sbox, t.properties.Sbox_inputs,
+	testRuleBuilder_Build(ctx, in, implicit, orderOnly, validation, t.properties.Flags,
+		out, outDep, outDir,
+		manifestPath, t.properties.Restat, t.properties.Sbox, t.properties.Sbox_inputs, t.properties.Unescape_ninja_vars,
 		rspFile, rspFileContents, rspFile2, rspFileContents2)
 }
 
@@ -543,17 +557,18 @@
 	rspFileContents2 := PathsForSource(ctx, []string{"rsp_in2"})
 	manifestPath := PathForOutput(ctx, "singleton/sbox.textproto")
 
-	testRuleBuilder_Build(ctx, in, implicit, orderOnly, validation, out, outDep, outDir,
-		manifestPath, true, false, false,
+	testRuleBuilder_Build(ctx, in, implicit, orderOnly, validation, nil, out, outDep, outDir,
+		manifestPath, true, false, false, false,
 		rspFile, rspFileContents, rspFile2, rspFileContents2)
 }
 
 func testRuleBuilder_Build(ctx BuilderContext, in Paths, implicit, orderOnly, validation Path,
+	flags []string,
 	out, outDep, outDir, manifestPath WritablePath,
-	restat, sbox, sboxInputs bool,
+	restat, sbox, sboxInputs, unescapeNinjaVars bool,
 	rspFile WritablePath, rspFileContents Paths, rspFile2 WritablePath, rspFileContents2 Paths) {
 
-	rule := NewRuleBuilder(pctx, ctx)
+	rule := NewRuleBuilder(pctx_ruleBuilderTest, ctx)
 
 	if sbox {
 		rule.Sbox(outDir, manifestPath)
@@ -564,6 +579,7 @@
 
 	rule.Command().
 		Tool(PathForSource(ctx, "cp")).
+		Flags(flags).
 		Inputs(in).
 		Implicit(implicit).
 		OrderOnly(orderOnly).
@@ -577,7 +593,11 @@
 		rule.Restat()
 	}
 
-	rule.Build("rule", "desc")
+	if unescapeNinjaVars {
+		rule.BuildWithUnescapedNinjaVars("rule", "desc")
+	} else {
+		rule.Build("rule", "desc")
+	}
 }
 
 var prepareForRuleBuilderTest = FixtureRegisterWithContext(func(ctx RegistrationContext) {
@@ -792,3 +812,47 @@
 		})
 	}
 }
+
+func TestRuleBuilderWithNinjaVarEscaping(t *testing.T) {
+	bp := `
+		rule_builder_test {
+			name: "foo_sbox_escaped_ninja",
+			flags: ["${cmdFlags}"],
+			sbox: true,
+			sbox_inputs: true,
+		}
+		rule_builder_test {
+			name: "foo_sbox",
+			flags: ["${cmdFlags}"],
+			sbox: true,
+			sbox_inputs: true,
+			unescape_ninja_vars: true,
+		}
+	`
+	result := GroupFixturePreparers(
+		prepareForRuleBuilderTest,
+		FixtureWithRootAndroidBp(bp),
+	).RunTest(t)
+
+	escapedNinjaMod := result.ModuleForTests("foo_sbox_escaped_ninja", "").Rule("writeFile")
+	AssertStringDoesContain(
+		t,
+		"",
+		escapedNinjaMod.BuildParams.Args["content"],
+		"$${cmdFlags}",
+	)
+
+	unescapedNinjaMod := result.ModuleForTests("foo_sbox", "").Rule("unescapedWriteFile")
+	AssertStringDoesContain(
+		t,
+		"",
+		unescapedNinjaMod.BuildParams.Args["content"],
+		"${cmdFlags}",
+	)
+	AssertStringDoesNotContain(
+		t,
+		"",
+		unescapedNinjaMod.BuildParams.Args["content"],
+		"$${cmdFlags}",
+	)
+}
diff --git a/cc/testing.go b/cc/testing.go
index 7531f6d..71d986b 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -35,6 +35,7 @@
 
 	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)
diff --git a/cmd/sbox/sbox.go b/cmd/sbox/sbox.go
index fc56dd5..3364f50 100644
--- a/cmd/sbox/sbox.go
+++ b/cmd/sbox/sbox.go
@@ -119,6 +119,9 @@
 	}
 
 	manifest, err := readManifest(manifestFile)
+	if err != nil {
+		return err
+	}
 
 	if len(manifest.Commands) == 0 {
 		return fmt.Errorf("at least one commands entry is required in %q", manifestFile)
diff --git a/rust/binary.go b/rust/binary.go
index 1408ff1..aee4da6 100644
--- a/rust/binary.go
+++ b/rust/binary.go
@@ -138,9 +138,14 @@
 
 func (binary *binaryDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) buildOutput {
 	fileName := binary.getStem(ctx) + ctx.toolchain().ExecutableSuffix()
-	srcPath, _ := srcPathFromModuleSrcs(ctx, binary.baseCompiler.Properties.Srcs)
 	outputFile := android.PathForModuleOut(ctx, fileName)
 	ret := buildOutput{outputFile: outputFile}
+	var crateRootPath android.Path
+	if binary.baseCompiler.Properties.Crate_root == nil {
+		crateRootPath, _ = srcPathFromModuleSrcs(ctx, binary.baseCompiler.Properties.Srcs)
+	} else {
+		crateRootPath = android.PathForModuleSrc(ctx, *binary.baseCompiler.Properties.Crate_root)
+	}
 
 	flags.RustFlags = append(flags.RustFlags, deps.depFlags...)
 	flags.LinkFlags = append(flags.LinkFlags, deps.depLinkFlags...)
@@ -155,7 +160,7 @@
 	}
 	binary.baseCompiler.unstrippedOutputFile = outputFile
 
-	ret.kytheFile = TransformSrcToBinary(ctx, srcPath, deps, flags, outputFile).kytheFile
+	ret.kytheFile = TransformSrcToBinary(ctx, crateRootPath, deps, flags, outputFile).kytheFile
 	return ret
 }
 
diff --git a/rust/compiler.go b/rust/compiler.go
index e6a7a93..d6c52e8 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -73,6 +73,15 @@
 	// If no source file is defined, a single generated source module can be defined to be used as the main source.
 	Srcs []string `android:"path,arch_variant"`
 
+	// Entry point that is passed to rustc to begin the compilation. E.g. main.rs or lib.rs.
+	// When this property is set,
+	//    * sandboxing is enabled for this module, and
+	//    * the srcs attribute is interpreted as a list of all source files potentially
+	//          used in compilation, including the entrypoint, and
+	//    * compile_data can be used to add additional files used in compilation that
+	//          not directly used as source files.
+	Crate_root *string `android:"path,arch_variant"`
+
 	// name of the lint set that should be used to validate this module.
 	//
 	// Possible values are "default" (for using a sensible set of lints
@@ -511,6 +520,8 @@
 		ctx.PropertyErrorf("srcs", "only a single generated source module can be defined without a main source file.")
 	}
 
+	// TODO: b/297264540 - once all modules are sandboxed, we need to select the proper
+	// entry point file from Srcs rather than taking the first one
 	paths := android.PathsForModuleSrc(ctx, srcs)
 	return paths[srcIndex], paths[1:]
 }
diff --git a/rust/config/global.go b/rust/config/global.go
index c976617..f397ce9 100644
--- a/rust/config/global.go
+++ b/rust/config/global.go
@@ -81,13 +81,7 @@
 
 func init() {
 	pctx.SourcePathVariable("RustDefaultBase", RustDefaultBase)
-	pctx.VariableConfigMethod("HostPrebuiltTag", func(config android.Config) string {
-		if config.UseHostMusl() {
-			return "linux-musl-x86"
-		} else {
-			return config.PrebuiltOS()
-		}
-	})
+	pctx.VariableConfigMethod("HostPrebuiltTag", HostPrebuiltTag)
 
 	pctx.VariableFunc("RustBase", func(ctx android.PackageVarContext) string {
 		if override := ctx.Config().Getenv("RUST_PREBUILTS_BASE"); override != "" {
@@ -109,6 +103,14 @@
 	exportedVars.ExportStringStaticVariable("RUST_DEFAULT_VERSION", RustDefaultVersion)
 }
 
+func HostPrebuiltTag(config android.Config) string {
+	if config.UseHostMusl() {
+		return "linux-musl-x86"
+	} else {
+		return config.PrebuiltOS()
+	}
+}
+
 func getRustVersionPctx(ctx android.PackageVarContext) string {
 	return GetRustVersion(ctx)
 }
diff --git a/rust/library.go b/rust/library.go
index 0357086..f4a2b54 100644
--- a/rust/library.go
+++ b/rust/library.go
@@ -489,7 +489,7 @@
 	var outputFile android.ModuleOutPath
 	var ret buildOutput
 	var fileName string
-	srcPath := library.srcPath(ctx, deps)
+	crateRootPath := library.crateRootPath(ctx, deps)
 
 	if library.sourceProvider != nil {
 		deps.srcProviderFiles = append(deps.srcProviderFiles, library.sourceProvider.Srcs()...)
@@ -536,13 +536,13 @@
 
 	// Call the appropriate builder for this library type
 	if library.rlib() {
-		ret.kytheFile = TransformSrctoRlib(ctx, srcPath, deps, flags, outputFile).kytheFile
+		ret.kytheFile = TransformSrctoRlib(ctx, crateRootPath, deps, flags, outputFile).kytheFile
 	} else if library.dylib() {
-		ret.kytheFile = TransformSrctoDylib(ctx, srcPath, deps, flags, outputFile).kytheFile
+		ret.kytheFile = TransformSrctoDylib(ctx, crateRootPath, deps, flags, outputFile).kytheFile
 	} else if library.static() {
-		ret.kytheFile = TransformSrctoStatic(ctx, srcPath, deps, flags, outputFile).kytheFile
+		ret.kytheFile = TransformSrctoStatic(ctx, crateRootPath, deps, flags, outputFile).kytheFile
 	} else if library.shared() {
-		ret.kytheFile = TransformSrctoShared(ctx, srcPath, deps, flags, outputFile).kytheFile
+		ret.kytheFile = TransformSrctoShared(ctx, crateRootPath, deps, flags, outputFile).kytheFile
 	}
 
 	if library.rlib() || library.dylib() {
@@ -585,13 +585,15 @@
 	return ret
 }
 
-func (library *libraryDecorator) srcPath(ctx ModuleContext, _ PathDeps) android.Path {
+func (library *libraryDecorator) crateRootPath(ctx ModuleContext, _ PathDeps) android.Path {
 	if library.sourceProvider != nil {
 		// Assume the first source from the source provider is the library entry point.
 		return library.sourceProvider.Srcs()[0]
-	} else {
+	} else if library.baseCompiler.Properties.Crate_root == nil {
 		path, _ := srcPathFromModuleSrcs(ctx, library.baseCompiler.Properties.Srcs)
 		return path
+	} else {
+		return android.PathForModuleSrc(ctx, *library.baseCompiler.Properties.Crate_root)
 	}
 }
 
@@ -606,7 +608,7 @@
 		return android.OptionalPath{}
 	}
 
-	return android.OptionalPathForPath(Rustdoc(ctx, library.srcPath(ctx, deps),
+	return android.OptionalPathForPath(Rustdoc(ctx, library.crateRootPath(ctx, deps),
 		deps, flags))
 }
 
diff --git a/rust/toolchain_library.go b/rust/toolchain_library.go
index 326d529..cb345a4 100644
--- a/rust/toolchain_library.go
+++ b/rust/toolchain_library.go
@@ -18,9 +18,12 @@
 
 import (
 	"path"
+	"path/filepath"
 
 	"android/soong/android"
 	"android/soong/rust/config"
+
+	"github.com/google/blueprint/proptools"
 )
 
 // This module is used to compile the rust toolchain libraries
@@ -33,11 +36,15 @@
 		rustToolchainLibraryRlibFactory)
 	android.RegisterModuleType("rust_toolchain_library_dylib",
 		rustToolchainLibraryDylibFactory)
+	android.RegisterModuleType("rust_toolchain_rustc_prebuilt",
+		rustToolchainRustcPrebuiltFactory)
 }
 
 type toolchainLibraryProperties struct {
-	// path to the toolchain source, relative to the top of the toolchain source
-	Toolchain_src *string `android:"arch_variant"`
+	// path to the toolchain crate root, relative to the top of the toolchain source
+	Toolchain_crate_root *string `android:"arch_variant"`
+	// path to the rest of the toolchain srcs, relative to the top of the toolchain source
+	Toolchain_srcs []string `android:"arch_variant"`
 }
 
 type toolchainLibraryDecorator struct {
@@ -82,16 +89,21 @@
 
 func rustSetToolchainSource(ctx android.LoadHookContext) {
 	if toolchainLib, ok := ctx.Module().(*Module).compiler.(*toolchainLibraryDecorator); ok {
-		prefix := "linux-x86/" + GetRustPrebuiltVersion(ctx)
-		newSrcs := []string{path.Join(prefix, android.String(toolchainLib.Properties.Toolchain_src))}
+		prefix := filepath.Join(config.HostPrebuiltTag(ctx.Config()), GetRustPrebuiltVersion(ctx))
+		versionedCrateRoot := path.Join(prefix, android.String(toolchainLib.Properties.Toolchain_crate_root))
+		versionedSrcs := make([]string, len(toolchainLib.Properties.Toolchain_srcs))
+		for i, src := range toolchainLib.Properties.Toolchain_srcs {
+			versionedSrcs[i] = path.Join(prefix, src)
+		}
 
 		type props struct {
-			Srcs []string
+			Crate_root *string
+			Srcs       []string
 		}
 		p := &props{}
-		p.Srcs = newSrcs
+		p.Crate_root = &versionedCrateRoot
+		p.Srcs = versionedSrcs
 		ctx.AppendProperties(p)
-
 	} else {
 		ctx.ModuleErrorf("Called rustSetToolchainSource on a non-Rust Module.")
 	}
@@ -101,3 +113,47 @@
 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 := filepath.Join(config.HostPrebuiltTag(ctx.Config()), 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
+}