Platform mapping-based product config

This allows us to set product variables as build settings instead
of loading them from a target's provider, which further allows us
to read product config variables in transitions.

Bug: 287539062
Bug: 269577299
Test: Presubmits
Change-Id: I8497703f706162572ceb3486240e1eb02a37f5f6

12 files changed, 134 insertions, 40 deletions

diff --git a/android/config.go b/android/config.go
index fa439625d..f95010e05 100644
--- a/android/config.go
+++ b/android/config.go
@@ -202,10 +202,10 @@ type VendorConfig soongconfig.SoongConfig
 // product configuration values are read from Kati-generated soong.variables.
 type config struct {
 	// Options configurable with soong.variables
-	productVariables productVariables
+	productVariables ProductVariables
 
 	// Only available on configs created by TestConfig
-	TestProductVariables *productVariables
+	TestProductVariables *ProductVariables
 
 	// A specialized context object for Bazel/Soong mixed builds and migration
 	// purposes.
@@ -321,7 +321,7 @@ func loadConfig(config *config) error {
 
 // loadFromConfigFile loads and decodes configuration options from a JSON file
 // in the current working directory.
-func loadFromConfigFile(configurable *productVariables, filename string) error {
+func loadFromConfigFile(configurable *ProductVariables, filename string) error {
 	// Try to open the file
 	configFileReader, err := os.Open(filename)
 	defer configFileReader.Close()
@@ -373,7 +373,7 @@ func loadFromConfigFile(configurable *productVariables, filename string) error {
 
 // atomically writes the config file in case two copies of soong_build are running simultaneously
 // (for example, docs generation and ninja manifest generation)
-func saveToConfigFile(config *productVariables, filename string) error {
+func saveToConfigFile(config *ProductVariables, filename string) error {
 	data, err := json.MarshalIndent(&config, "", "    ")
 	if err != nil {
 		return fmt.Errorf("cannot marshal config data: %s", err.Error())
@@ -402,7 +402,7 @@ func saveToConfigFile(config *productVariables, filename string) error {
 	return nil
 }
 
-func saveToBazelConfigFile(config *productVariables, outDir string) error {
+func saveToBazelConfigFile(config *ProductVariables, outDir string) error {
 	dir := filepath.Join(outDir, bazel.SoongInjectionDirName, "product_config")
 	err := createDirIfNonexistent(dir, os.ModePerm)
 	if err != nil {
diff --git a/android/config_test.go b/android/config_test.go
index 9df5288a1..7d327a27e 100644
--- a/android/config_test.go
+++ b/android/config_test.go
@@ -75,7 +75,7 @@ Did you mean to use an annotation of ",omitempty"?
 
 // run validateConfigAnnotations against each type that might have json annotations
 func TestProductConfigAnnotations(t *testing.T) {
-	err := validateConfigAnnotations(&productVariables{})
+	err := validateConfigAnnotations(&ProductVariables{})
 	if err != nil {
 		t.Errorf(err.Error())
 	}
@@ -88,7 +88,7 @@ func TestMissingVendorConfig(t *testing.T) {
 	}
 }
 
-func verifyProductVariableMarshaling(t *testing.T, v productVariables) {
+func verifyProductVariableMarshaling(t *testing.T, v ProductVariables) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "test.variables")
 	err := saveToConfigFile(&v, path)
@@ -96,20 +96,20 @@ func verifyProductVariableMarshaling(t *testing.T, v productVariables) {
 		t.Errorf("Couldn't save default product config: %q", err)
 	}
 
-	var v2 productVariables
+	var v2 ProductVariables
 	err = loadFromConfigFile(&v2, path)
 	if err != nil {
 		t.Errorf("Couldn't load default product config: %q", err)
 	}
 }
 func TestDefaultProductVariableMarshaling(t *testing.T) {
-	v := productVariables{}
+	v := ProductVariables{}
 	v.SetDefaultConfig()
 	verifyProductVariableMarshaling(t, v)
 }
 
 func TestBootJarsMarshaling(t *testing.T) {
-	v := productVariables{}
+	v := ProductVariables{}
 	v.SetDefaultConfig()
 	v.BootJars = ConfiguredJarList{
 		apexes: []string{"apex"},
diff --git a/android/configured_jars_test.go b/android/configured_jars_test.go
index 32c3613f7..4b586e4d7 100644
--- a/android/configured_jars_test.go
+++ b/android/configured_jars_test.go
@@ -21,7 +21,7 @@ import (
 func TestOverrideConfiguredJarLocationFor(t *testing.T) {
 	cfg := NullConfig("", "")
 
-	cfg.productVariables = productVariables{
+	cfg.productVariables = ProductVariables{
 		ConfiguredJarLocationOverrides: []string{
 			"platform:libfoo-old:com.android.foo:libfoo-new",
 			"com.android.bar:libbar-old:platform:libbar-new",
diff --git a/android/fixture.go b/android/fixture.go
index dbc3bc5e0..6660afd65 100644
--- a/android/fixture.go
+++ b/android/fixture.go
@@ -369,7 +369,7 @@ func FixtureModifyEnv(mutator func(env map[string]string)) FixturePreparer {
 
 // Allow access to the product variables when preparing the fixture.
 type FixtureProductVariables struct {
-	*productVariables
+	*ProductVariables
 }
 
 // Modify product variables.
diff --git a/android/sdk_version_test.go b/android/sdk_version_test.go
index ea99c4d62..30bd002c2 100644
--- a/android/sdk_version_test.go
+++ b/android/sdk_version_test.go
@@ -75,7 +75,7 @@ func TestSdkSpecFrom(t *testing.T) {
 
 	config := NullConfig("", "")
 
-	config.productVariables = productVariables{
+	config.productVariables = ProductVariables{
 		Platform_sdk_version:              intPtr(31),
 		Platform_sdk_codename:             stringPtr("Tiramisu"),
 		Platform_version_active_codenames: []string{"Tiramisu"},
diff --git a/android/test_config.go b/android/test_config.go
index 28d9ec403..2a59d9228 100644
--- a/android/test_config.go
+++ b/android/test_config.go
@@ -35,7 +35,7 @@ func TestConfig(buildDir string, env map[string]string, bp string, fs map[string
 	envCopy["PATH"] = os.Getenv("PATH")
 
 	config := &config{
-		productVariables: productVariables{
+		productVariables: ProductVariables{
 			DeviceName:                          stringPtr("test_device"),
 			DeviceProduct:                       stringPtr("test_product"),
 			Platform_sdk_version:                intPtr(30),
diff --git a/android/variable.go b/android/variable.go
index 4442a09eb..f5dddafd8 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -185,7 +185,7 @@ type variableProperties struct {
 
 var defaultProductVariables interface{} = variableProperties{}
 
-type productVariables struct {
+type ProductVariables struct {
 	// Suffix to add to generated Makefiles
 	Make_suffix *string `json:",omitempty"`
 
@@ -489,8 +489,8 @@ func stringPtr(v string) *string {
 	return &v
 }
 
-func (v *productVariables) SetDefaultConfig() {
-	*v = productVariables{
+func (v *ProductVariables) SetDefaultConfig() {
+	*v = ProductVariables{
 		BuildNumberFile: stringPtr("build_number.txt"),
 
 		Platform_version_name:                  stringPtr("S"),
diff --git a/bp2build/bp2build.go b/bp2build/bp2build.go
index b22cb2861..cfe52db47 100644
--- a/bp2build/bp2build.go
+++ b/bp2build/bp2build.go
@@ -80,6 +80,12 @@ func Codegen(ctx *CodegenContext) *CodegenMetrics {
 		os.Exit(1)
 	}
 	bp2buildFiles := CreateBazelFiles(ctx.Config(), nil, res.buildFileToTargets, ctx.mode)
+	injectionFiles, additionalBp2buildFiles, err := CreateSoongInjectionDirFiles(ctx, res.metrics)
+	if err != nil {
+		fmt.Printf("%s\n", err.Error())
+		os.Exit(1)
+	}
+	bp2buildFiles = append(bp2buildFiles, additionalBp2buildFiles...)
 	writeFiles(ctx, bp2buildDir, bp2buildFiles)
 	// Delete files under the bp2build root which weren't just written. An
 	// alternative would have been to delete the whole directory and write these
@@ -88,11 +94,6 @@ func Codegen(ctx *CodegenContext) *CodegenMetrics {
 	// performance implications.
 	deleteFilesExcept(ctx, bp2buildDir, bp2buildFiles)
 
-	injectionFiles, err := CreateSoongInjectionDirFiles(ctx, res.metrics)
-	if err != nil {
-		fmt.Printf("%s\n", err.Error())
-		os.Exit(1)
-	}
 	writeFiles(ctx, android.PathForOutput(ctx, bazel.SoongInjectionDirName), injectionFiles)
 	starlarkDeps, err := starlark_import.GetNinjaDeps()
 	if err != nil {
@@ -107,20 +108,20 @@ func Codegen(ctx *CodegenContext) *CodegenMetrics {
 // This includes
 // 1. config value(s) that are hardcoded in Soong
 // 2. product_config variables
-func CreateSoongInjectionDirFiles(ctx *CodegenContext, metrics CodegenMetrics) ([]BazelFile, error) {
+func CreateSoongInjectionDirFiles(ctx *CodegenContext, metrics CodegenMetrics) ([]BazelFile, []BazelFile, error) {
 	var ret []BazelFile
 
-	productConfigFiles, err := CreateProductConfigFiles(ctx)
+	productConfigInjectionFiles, productConfigBp2BuildDirFiles, err := CreateProductConfigFiles(ctx)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	ret = append(ret, productConfigFiles...)
+	ret = append(ret, productConfigInjectionFiles...)
 	injectionFiles, err := soongInjectionFiles(ctx.Config(), metrics)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	ret = append(ret, injectionFiles...)
-	return ret, nil
+	ret = append(injectionFiles, ret...)
+	return ret, productConfigBp2BuildDirFiles, nil
 }
 
 // Get the output directory and create it if it doesn't exist.
diff --git a/bp2build/bp2build_product_config.go b/bp2build/bp2build_product_config.go
index 72244961d..8d5c99c28 100644
--- a/bp2build/bp2build_product_config.go
+++ b/bp2build/bp2build_product_config.go
@@ -1,14 +1,20 @@
 package bp2build
 
 import (
+	"android/soong/android"
+	"android/soong/starlark_import"
+	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/google/blueprint/proptools"
+	"go.starlark.net/starlark"
 )
 
 func CreateProductConfigFiles(
-	ctx *CodegenContext) ([]BazelFile, error) {
+	ctx *CodegenContext) ([]BazelFile, []BazelFile, error) {
 	cfg := &ctx.config
 	targetProduct := "unknown"
 	if cfg.HasDeviceProduct() {
@@ -25,9 +31,14 @@ func CreateProductConfigFiles(
 	if !strings.HasPrefix(productVariablesFileName, "/") {
 		productVariablesFileName = filepath.Join(ctx.topDir, productVariablesFileName)
 	}
-	bytes, err := os.ReadFile(productVariablesFileName)
+	productVariablesBytes, err := os.ReadFile(productVariablesFileName)
+	if err != nil {
+		return nil, nil, err
+	}
+	productVariables := android.ProductVariables{}
+	err = json.Unmarshal(productVariablesBytes, &productVariables)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	// TODO(b/249685973): the name is product_config_platforms because product_config
@@ -39,11 +50,16 @@ func CreateProductConfigFiles(
 		"{VARIANT}", targetBuildVariant,
 		"{PRODUCT_FOLDER}", currentProductFolder)
 
-	result := []BazelFile{
+	platformMappingContent, err := platformMappingContent(productReplacer.Replace("@soong_injection//{PRODUCT_FOLDER}:{PRODUCT}-{VARIANT}"), &productVariables)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	injectionDirFiles := []BazelFile{
 		newFile(
 			currentProductFolder,
 			"soong.variables.bzl",
-			`variables = json.decode("""`+strings.ReplaceAll(string(bytes), "\\", "\\\\")+`""")`),
+			`variables = json.decode("""`+strings.ReplaceAll(string(productVariablesBytes), "\\", "\\\\")+`""")`),
 		newFile(
 			currentProductFolder,
 			"BUILD",
@@ -99,6 +115,7 @@ product_labels = [
 			"product_config_platforms",
 			"common.bazelrc",
 			productReplacer.Replace(`
+build --platform_mappings=platform_mappings
 build --platforms @soong_injection//{PRODUCT_FOLDER}:{PRODUCT}-{VARIANT}_linux_x86_64
 
 build:android --platforms=@soong_injection//{PRODUCT_FOLDER}:{PRODUCT}-{VARIANT}
@@ -120,6 +137,48 @@ build --host_platform @soong_injection//{PRODUCT_FOLDER}:{PRODUCT}-{VARIANT}_lin
 build --host_platform @soong_injection//{PRODUCT_FOLDER}:{PRODUCT}-{VARIANT}_darwin_x86_64
 `)),
 	}
+	bp2buildDirFiles := []BazelFile{
+		newFile(
+			"",
+			"platform_mappings",
+			platformMappingContent),
+	}
+	return injectionDirFiles, bp2buildDirFiles, nil
+}
+
+func platformMappingContent(mainProductLabel string, mainProductVariables *android.ProductVariables) (string, error) {
+	productsForTesting, err := starlark_import.GetStarlarkValue[map[string]map[string]starlark.Value]("products_for_testing")
+	if err != nil {
+		return "", err
+	}
+	result := "platforms:\n"
+	result += platformMappingSingleProduct(mainProductLabel, mainProductVariables)
+	for product, productVariablesStarlark := range productsForTesting {
+		productVariables, err := starlarkMapToProductVariables(productVariablesStarlark)
+		if err != nil {
+			return "", err
+		}
+		result += platformMappingSingleProduct("@//build/bazel/tests/products:"+product, &productVariables)
+	}
+	return result, nil
+}
+
+func platformMappingSingleProduct(label string, productVariables *android.ProductVariables) string {
+	buildSettings := ""
+	buildSettings += fmt.Sprintf("    --//build/bazel/product_config:apex_global_min_sdk_version_override=%s\n", proptools.String(productVariables.ApexGlobalMinSdkVersionOverride))
+	result := ""
+	for _, extension := range []string{"", "_linux_x86_64", "_linux_bionic_x86_64", "_linux_musl_x86", "_linux_musl_x86_64"} {
+		result += "  " + label + extension + "\n" + buildSettings
+	}
+	return result
+}
 
+func starlarkMapToProductVariables(in map[string]starlark.Value) (android.ProductVariables, error) {
+	var err error
+	result := android.ProductVariables{}
+	result.ApexGlobalMinSdkVersionOverride, err = starlark_import.NoneableString(in["ApexGlobalMinSdkVersionOverride"])
+	if err != nil {
+		return result, err
+	}
 	return result, nil
 }
diff --git a/cmd/soong_build/main.go b/cmd/soong_build/main.go
index 22d64a2ed..5ea84bcba 100644
--- a/cmd/soong_build/main.go
+++ b/cmd/soong_build/main.go
@@ -225,7 +225,7 @@ func runApiBp2build(ctx *android.Context, extraNinjaDeps []string) string {
 	ninjaDeps = append(ninjaDeps, codegenContext.AdditionalNinjaDeps()...)
 
 	// Create soong_injection repository
-	soongInjectionFiles, err := bp2build.CreateSoongInjectionDirFiles(codegenContext, bp2build.CreateCodegenMetrics())
+	soongInjectionFiles, workspaceFiles, err := bp2build.CreateSoongInjectionDirFiles(codegenContext, bp2build.CreateCodegenMetrics())
 	maybeQuit(err, "")
 	absoluteSoongInjectionDir := shared.JoinPath(topDir, ctx.Config().SoongOutDir(), bazel.SoongInjectionDirName)
 	for _, file := range soongInjectionFiles {
@@ -236,6 +236,9 @@ func runApiBp2build(ctx *android.Context, extraNinjaDeps []string) string {
 		// to allow users to edit/experiment in the synthetic workspace.
 		writeReadWriteFile(absoluteSoongInjectionDir, file)
 	}
+	for _, file := range workspaceFiles {
+		writeReadWriteFile(absoluteApiBp2buildDir, file)
+	}
 
 	workspace := shared.JoinPath(ctx.Config().SoongOutDir(), "api_bp2build")
 	// Create the symlink forest
diff --git a/starlark_import/unmarshal.go b/starlark_import/unmarshal.go
index 1b5443782..0e6f13030 100644
--- a/starlark_import/unmarshal.go
+++ b/starlark_import/unmarshal.go
@@ -25,12 +25,14 @@ import (
 )
 
 func Unmarshal[T any](value starlark.Value) (T, error) {
-	var zero T
-	x, err := UnmarshalReflect(value, reflect.TypeOf(zero))
+	x, err := UnmarshalReflect(value, reflect.TypeOf((*T)(nil)).Elem())
 	return x.Interface().(T), err
 }
 
 func UnmarshalReflect(value starlark.Value, ty reflect.Type) (reflect.Value, error) {
+	if ty == reflect.TypeOf((*starlark.Value)(nil)).Elem() {
+		return reflect.ValueOf(value), nil
+	}
 	zero := reflect.Zero(ty)
 	var result reflect.Value
 	if ty.Kind() == reflect.Interface {
@@ -286,3 +288,17 @@ func typeOfStarlarkValue(value starlark.Value) (reflect.Type, error) {
 		return nil, fmt.Errorf("unimplemented starlark type: %s", value.Type())
 	}
 }
+
+// NoneableString converts a starlark.Value to a string pointer. If the starlark.Value is NoneType,
+// a nil pointer will be returned instead. All other types of starlark values are errors.
+func NoneableString(value starlark.Value) (*string, error) {
+	switch v := value.(type) {
+	case starlark.String:
+		result := v.GoString()
+		return &result, nil
+	case starlark.NoneType:
+		return nil, nil
+	default:
+		return nil, fmt.Errorf("expected string or none, got %q", value.Type())
+	}
+}
diff --git a/starlark_import/unmarshal_test.go b/starlark_import/unmarshal_test.go
index ee7a9e340..bc0ea4c49 100644
--- a/starlark_import/unmarshal_test.go
+++ b/starlark_import/unmarshal_test.go
@@ -30,7 +30,7 @@ func createStarlarkValue(t *testing.T, code string) starlark.Value {
 	return result["x"]
 }
 
-func TestUnmarshallConcreteType(t *testing.T) {
+func TestUnmarshalConcreteType(t *testing.T) {
 	x, err := Unmarshal[string](createStarlarkValue(t, `"foo"`))
 	if err != nil {
 		t.Error(err)
@@ -41,7 +41,7 @@ func TestUnmarshallConcreteType(t *testing.T) {
 	}
 }
 
-func TestUnmarshallConcreteTypeWithInterfaces(t *testing.T) {
+func TestUnmarshalConcreteTypeWithInterfaces(t *testing.T) {
 	x, err := Unmarshal[map[string]map[string]interface{}](createStarlarkValue(t,
 		`{"foo": {"foo2": "foo3"}, "bar": {"bar2": ["bar3"]}}`))
 	if err != nil {
@@ -57,7 +57,22 @@ func TestUnmarshallConcreteTypeWithInterfaces(t *testing.T) {
 	}
 }
 
-func TestUnmarshall(t *testing.T) {
+func TestUnmarshalToStarlarkValue(t *testing.T) {
+	x, err := Unmarshal[map[string]starlark.Value](createStarlarkValue(t,
+		`{"foo": "Hi", "bar": None}`))
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	if x["foo"].(starlark.String).GoString() != "Hi" {
+		t.Errorf("Expected \"Hi\", got: %q", x["foo"].(starlark.String).GoString())
+	}
+	if x["bar"].Type() != "NoneType" {
+		t.Errorf("Expected \"NoneType\", got: %q", x["bar"].Type())
+	}
+}
+
+func TestUnmarshal(t *testing.T) {
 	testCases := []struct {
 		input    string
 		expected interface{}