1 files changed, 45 insertions, 8 deletions

diff --git a/android/prebuilt.go b/android/prebuilt.go
index 3be10f72..48d3b68b 100644
--- a/android/prebuilt.go
+++ b/android/prebuilt.go
@@ -16,6 +16,7 @@ package android
 
 import (
 	"fmt"
+	"reflect"
 
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
@@ -43,13 +44,21 @@ type Prebuilt struct {
 	properties PrebuiltProperties
 	module     Module
 	srcs       *[]string
-	src        *string
+
+	// Metadata for single source Prebuilt modules.
+	srcProps reflect.Value
+	srcField reflect.StructField
 }
 
 func (p *Prebuilt) Name(name string) string {
 	return "prebuilt_" + name
 }
 
+// The below source-related functions and the srcs, src fields are based on an assumption that
+// prebuilt modules have a static source property at the moment. Currently there is only one
+// exception, android_app_import, which chooses a source file depending on the product's DPI
+// preference configs. We'll want to add native support for dynamic source cases if we end up having
+// more modules like this.
 func (p *Prebuilt) SingleSourcePath(ctx ModuleContext) Path {
 	if p.srcs != nil {
 		if len(*p.srcs) == 0 {
@@ -66,11 +75,16 @@ func (p *Prebuilt) SingleSourcePath(ctx ModuleContext) Path {
 		// sources.
 		return PathForModuleSrc(ctx, (*p.srcs)[0])
 	} else {
-		if proptools.String(p.src) == "" {
-			ctx.PropertyErrorf("src", "missing prebuilt source file")
+		if !p.srcProps.IsValid() {
+			ctx.ModuleErrorf("prebuilt source was not set")
+		}
+		src := p.getSingleSourceFieldValue()
+		if src == "" {
+			ctx.PropertyErrorf(proptools.FieldNameForProperty(p.srcField.Name),
+				"missing prebuilt source file")
 			return nil
 		}
-		return PathForModuleSrc(ctx, *p.src)
+		return PathForModuleSrc(ctx, src)
 	}
 }
 
@@ -84,10 +98,12 @@ func InitPrebuiltModule(module PrebuiltInterface, srcs *[]string) {
 	p.srcs = srcs
 }
 
-func InitSingleSourcePrebuiltModule(module PrebuiltInterface, src *string) {
+func InitSingleSourcePrebuiltModule(module PrebuiltInterface, srcProps interface{}, srcField string) {
 	p := module.Prebuilt()
 	module.AddProperties(&p.properties)
-	p.src = src
+	p.srcProps = reflect.ValueOf(srcProps).Elem()
+	p.srcField, _ = p.srcProps.Type().FieldByName(srcField)
+	p.checkSingleSourceProperties()
 }
 
 type PrebuiltInterface interface {
@@ -124,7 +140,7 @@ func PrebuiltMutator(ctx BottomUpMutatorContext) {
 func PrebuiltSelectModuleMutator(ctx TopDownMutatorContext) {
 	if m, ok := ctx.Module().(PrebuiltInterface); ok && m.Prebuilt() != nil {
 		p := m.Prebuilt()
-		if p.srcs == nil && p.src == nil {
+		if p.srcs == nil && !p.srcProps.IsValid() {
 			panic(fmt.Errorf("prebuilt module did not have InitPrebuiltModule called on it"))
 		}
 		if !p.properties.SourceExists {
@@ -167,7 +183,7 @@ func (p *Prebuilt) usePrebuilt(ctx TopDownMutatorContext, source Module) bool {
 		return false
 	}
 
-	if p.src != nil && *p.src == "" {
+	if p.srcProps.IsValid() && p.getSingleSourceFieldValue() == "" {
 		return false
 	}
 
@@ -182,3 +198,24 @@ func (p *Prebuilt) usePrebuilt(ctx TopDownMutatorContext, source Module) bool {
 func (p *Prebuilt) SourceExists() bool {
 	return p.properties.SourceExists
 }
+
+func (p *Prebuilt) checkSingleSourceProperties() {
+	if !p.srcProps.IsValid() || p.srcField.Name == "" {
+		panic(fmt.Errorf("invalid single source prebuilt %+v", p))
+	}
+
+	if p.srcProps.Kind() != reflect.Struct && p.srcProps.Kind() != reflect.Interface {
+		panic(fmt.Errorf("invalid single source prebuilt %+v", p.srcProps))
+	}
+}
+
+func (p *Prebuilt) getSingleSourceFieldValue() string {
+	value := p.srcProps.FieldByIndex(p.srcField.Index)
+	if value.Kind() == reflect.Ptr {
+		value = value.Elem()
+	}
+	if value.Kind() != reflect.String {
+		panic(fmt.Errorf("prebuilt src field %q should be a string or a pointer to one", p.srcField.Name))
+	}
+	return value.String()
+}