Generate wrapper lib.rs with one module per sysprop file.

This required moving to a SourceProvider for the Rust library. With the
previous approach only the first input file was being used.

Bug: 270547306
Test: Built libplatformproperties_rust, looked at output
Change-Id: I1070655abc071e099a42bc4be61cc080902e31c1
diff --git a/sysprop/sysprop_library.go b/sysprop/sysprop_library.go
index 698aaf2..b9b68be 100644
--- a/sysprop/sysprop_library.go
+++ b/sysprop/sysprop_library.go
@@ -54,15 +54,13 @@
 }
 
 type syspropRustGenRule struct {
-	android.ModuleBase
+	*rust.BaseSourceProvider
 
-	properties syspropGenProperties
-
-	genSrcs android.Paths
+	properties rustLibraryProperties
 }
 
 var _ android.OutputFileProducer = (*syspropJavaGenRule)(nil)
-var _ android.OutputFileProducer = (*syspropRustGenRule)(nil)
+var _ rust.SourceProvider = (*syspropRustGenRule)(nil)
 
 var (
 	syspropJava = pctx.AndroidStaticRule("syspropJava",
@@ -144,7 +142,7 @@
 
 // syspropRustGenRule module generates rust source files containing generated rust APIs.
 // It also depends on check api rule, so api check has to pass to use sysprop_library.
-func (g *syspropRustGenRule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+func (g *syspropRustGenRule) GenerateSource(ctx rust.ModuleContext, deps rust.PathDeps) android.Path {
 	var checkApiFileTimeStamp android.WritablePath
 
 	ctx.VisitDirectDeps(func(dep android.Module) {
@@ -153,25 +151,47 @@
 		}
 	})
 
-	for _, syspropFile := range android.PathsForModuleSrc(ctx, g.properties.Srcs) {
-		syspropDir := android.GenPathWithExt(ctx, "sysprop", syspropFile, "srcrust")
-		outputDir := syspropDir.Join(ctx, "src")
-		libPath := syspropDir.Join(ctx, "src", "lib.rs")
+	outputDir := android.PathForModuleOut(ctx, "src")
+	libFile := outputDir.Join(ctx, "lib.rs")
+	g.BaseSourceProvider.OutputFiles = append(g.BaseSourceProvider.OutputFiles, libFile)
+	libFileLines := []string{"//! Autogenerated system property accessors."}
+
+	for _, syspropFile := range android.PathsForModuleSrc(ctx, g.properties.Sysprop_srcs) {
+		moduleName := syspropPathToRustModule(syspropFile)
+		moduleDir := outputDir.Join(ctx, moduleName)
+		modulePath := moduleDir.Join(ctx, "mod.rs")
 
 		ctx.Build(pctx, android.BuildParams{
 			Rule:        syspropRust,
 			Description: "sysprop_rust " + syspropFile.Rel(),
-			Outputs:     android.WritablePaths{libPath},
+			Output:      modulePath,
 			Input:       syspropFile,
 			Implicit:    checkApiFileTimeStamp,
 			Args: map[string]string{
 				"scope":   g.properties.Scope,
-				"out_dir": outputDir.String(),
+				"out_dir": moduleDir.String(),
 			},
 		})
 
-		g.genSrcs = append(g.genSrcs, libPath)
+		g.BaseSourceProvider.OutputFiles = append(g.BaseSourceProvider.OutputFiles, modulePath)
+		libFileLines = append(libFileLines, fmt.Sprintf("pub mod %s;", moduleName))
 	}
+
+	libFileSource := strings.Join(libFileLines, "\n")
+	android.WriteFileRule(ctx, libFile, libFileSource)
+
+	return libFile
+}
+
+func (g *syspropRustGenRule) SourceProviderProps() []interface{} {
+	return append(g.BaseSourceProvider.SourceProviderProps(), &g.Properties)
+}
+
+// syspropPathToRustModule takes a path to a .sysprop file and returns the name to use for the
+// corresponding Rust module.
+func syspropPathToRustModule(syspropFilename android.Path) string {
+	filenameBase := strings.TrimSuffix(syspropFilename.Base(), ".sysprop")
+	return strings.ToLower(filenameBase)
 }
 
 func (g *syspropRustGenRule) DepsMutator(ctx android.BottomUpMutatorContext) {
@@ -180,15 +200,13 @@
 	ctx.AddFarVariationDependencies(nil, nil, proptools.String(g.properties.Check_api))
 }
 
-func (g *syspropRustGenRule) OutputFiles(_ string) (android.Paths, error) {
-	return g.genSrcs, nil
-}
-
 func syspropRustGenFactory() android.Module {
-	g := &syspropRustGenRule{}
-	g.AddProperties(&g.properties)
-	android.InitAndroidModule(g)
-	return g
+	g := &syspropRustGenRule{
+		BaseSourceProvider: rust.NewSourceProvider(),
+	}
+	sourceProvider := rust.NewSourceProviderModule(android.DeviceSupported, g, false, false)
+	sourceProvider.AddProperties(&g.properties)
+	return sourceProvider.Init()
 }
 
 type syspropLibrary struct {
@@ -308,10 +326,6 @@
 	return m.BaseModuleName() + "_java_gen_public"
 }
 
-func (m *syspropLibrary) rustGenModuleName() string {
-	return m.rustCrateName() + "_rust_gen"
-}
-
 func (m *syspropLibrary) rustGenStubName() string {
 	return "lib" + m.rustCrateName() + "_rust"
 }
@@ -528,6 +542,9 @@
 
 type rustLibraryProperties struct {
 	Name              *string
+	Sysprop_srcs      []string `android:"path"`
+	Scope             string
+	Check_api         *string
 	Srcs              []string
 	Installable       *bool
 	Crate_name        string
@@ -667,18 +684,15 @@
 	}
 
 	// Generate a Rust implementation library.
-	ctx.CreateModule(syspropRustGenFactory, &syspropGenProperties{
-		Srcs:      m.properties.Srcs,
-		Scope:     scope,
-		Name:      proptools.StringPtr(m.rustGenModuleName()),
-		Check_api: proptools.StringPtr(ctx.ModuleName()),
-	})
 	rustProps := rustLibraryProperties{
-		Name:        proptools.StringPtr(m.rustGenStubName()),
-		Srcs:        []string{":" + m.rustGenModuleName()},
-		Installable: proptools.BoolPtr(false),
-		Crate_name:  m.rustCrateName(),
+		Name:         proptools.StringPtr(m.rustGenStubName()),
+		Sysprop_srcs: m.properties.Srcs,
+		Scope:        scope,
+		Check_api:    proptools.StringPtr(ctx.ModuleName()),
+		Installable:  proptools.BoolPtr(false),
+		Crate_name:   m.rustCrateName(),
 		Rustlibs: []string{
+			"liblog_rust",
 			"librustutils",
 		},
 		Vendor_available:  m.properties.Vendor_available,
@@ -686,7 +700,7 @@
 		Apex_available:    m.ApexProperties.Apex_available,
 		Min_sdk_version:   proptools.StringPtr("29"),
 	}
-	ctx.CreateModule(rust.RustLibraryFactory, &rustProps)
+	ctx.CreateModule(syspropRustGenFactory, &rustProps)
 
 	// syspropLibraries will be used by property_contexts to check types.
 	// Record absolute paths of sysprop_library to prevent soong_namespace problem.
diff --git a/sysprop/sysprop_test.go b/sysprop/sysprop_test.go
index 9dd696f..dfbbe7d 100644
--- a/sysprop/sysprop_test.go
+++ b/sysprop/sysprop_test.go
@@ -72,6 +72,15 @@
 			vendor_available: true,
 			min_sdk_version: "29",
 		}
+
+		rust_library {
+			name: "liblog_rust",
+			crate_name: "log",
+			srcs: ["log/src/lib.rs"],
+			product_available: true,
+			vendor_available: true,
+			min_sdk_version: "29",
+		}
 	`
 
 	mockFS := android.MockFS{
@@ -115,6 +124,7 @@
 		"com/android2/OdmProperties.sysprop":         nil,
 
 		"librustutils/lib.rs": nil,
+		"log/src/lib.rs":      nil,
 	}
 
 	result := android.GroupFixturePreparers(