android_filesystem modules can be included in APEX

android_filesystem modules can be included in APEX via the new
`filesystems` property. The filesystem images are placed at
./etc/fs/<modulename>.img.

Bug: 172413888
Test: m nothing

Change-Id: I215ca7a32ff1988a0de4e1f71397684e189839ea

apex/Android.bp

@@ -7,6 +7,7 @@ bootstrap_go_package {
         "soong-android",
         "soong-bpf",
         "soong-cc",
+        "soong-filesystem",
         "soong-java",
         "soong-python",
         "soong-rust",

apex/apex.go

@@ -30,6 +30,7 @@ import (
 	"android/soong/bpf"
 	"android/soong/cc"
 	prebuilt_etc "android/soong/etc"
+	"android/soong/filesystem"
 	"android/soong/java"
 	"android/soong/python"
 	"android/soong/rust"
@@ -96,6 +97,9 @@ type apexBundleProperties struct {
 	// List of BPF programs inside this APEX bundle.
 	Bpfs []string
 
+	// List of filesystem images that are embedded inside this APEX bundle.
+	Filesystems []string
+
 	// Name of the apex_key module that provides the private key to sign this APEX bundle.
 	Key *string
 
@@ -530,6 +534,7 @@ var (
 	bpfTag         = dependencyTag{name: "bpf", payload: true}
 	certificateTag = dependencyTag{name: "certificate"}
 	executableTag  = dependencyTag{name: "executable", payload: true}
+	fsTag          = dependencyTag{name: "filesystem", payload: true}
 	javaLibTag     = dependencyTag{name: "javaLib", payload: true}
 	jniLibTag      = dependencyTag{name: "jniLib", payload: true}
 	keyTag         = dependencyTag{name: "key"}
@@ -709,6 +714,7 @@ func (a *apexBundle) DepsMutator(ctx android.BottomUpMutatorContext) {
 	commonVariation := ctx.Config().AndroidCommonTarget.Variations()
 	ctx.AddFarVariationDependencies(commonVariation, javaLibTag, a.properties.Java_libs...)
 	ctx.AddFarVariationDependencies(commonVariation, bpfTag, a.properties.Bpfs...)
+	ctx.AddFarVariationDependencies(commonVariation, fsTag, a.properties.Filesystems...)
 
 	// With EMMA_INSTRUMENT_FRAMEWORK=true the ART boot image includes jacoco library.
 	if a.artApex && ctx.Config().IsEnvTrue("EMMA_INSTRUMENT_FRAMEWORK") {
@@ -1481,6 +1487,11 @@ func apexFileForBpfProgram(ctx android.BaseModuleContext, builtFile android.Path
 	return newApexFile(ctx, builtFile, builtFile.Base(), dirInApex, etc, bpfProgram)
 }
 
+func apexFileForFilesystem(ctx android.BaseModuleContext, buildFile android.Path, fs filesystem.Filesystem) apexFile {
+	dirInApex := filepath.Join("etc", "fs")
+	return newApexFile(ctx, buildFile, buildFile.Base(), dirInApex, etc, fs)
+}
+
 // WalyPayloadDeps visits dependencies that contributes to the payload of this APEX. For each of the
 // visited module, the `do` callback is executed. Returning true in the callback continues the visit
 // to the child modules. Returning false makes the visit to continue in the sibling or the parent
@@ -1655,6 +1666,12 @@ func (a *apexBundle) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 				} else {
 					ctx.PropertyErrorf("bpfs", "%q is not a bpf module", depName)
 				}
+			case fsTag:
+				if fs, ok := child.(filesystem.Filesystem); ok {
+					filesInfo = append(filesInfo, apexFileForFilesystem(ctx, fs.OutputPath(), fs))
+				} else {
+					ctx.PropertyErrorf("filesystems", "%q is not a filesystem module", depName)
+				}
 			case prebuiltTag:
 				if prebuilt, ok := child.(prebuilt_etc.PrebuiltEtcModule); ok {
 					filesInfo = append(filesInfo, apexFileForPrebuiltEtc(ctx, prebuilt, depName))

filesystem/filesystem.go

@@ -46,7 +46,10 @@ func filesystemFactory() android.Module {
 	return module
 }
 
-var dependencyTag = struct{ blueprint.BaseDependencyTag }{}
+var dependencyTag = struct {
+	blueprint.BaseDependencyTag
+	android.InstallAlwaysNeededDependencyTag
+}{}
 
 func (f *filesystem) DepsMutator(ctx android.BottomUpMutatorContext) {
 	f.AddDeps(ctx, dependencyTag)
@@ -80,7 +83,7 @@ func (f *filesystem) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 		Text(">").Output(propFile).
 		Implicit(mkuserimg)
 
-	f.output = android.PathForModuleOut(ctx, "filesystem.img").OutputPath
+	f.output = android.PathForModuleOut(ctx, f.installFileName()).OutputPath
 	builder.Command().BuiltTool("build_image").
 		Text(rootDir.String()). // input directory
 		Input(propFile).
@@ -109,3 +112,16 @@ func (f *filesystem) AndroidMkEntries() []android.AndroidMkEntries {
 		},
 	}}
 }
+
+// Filesystem is the public interface for the filesystem struct. Currently, it's only for the apex
+// package to have access to the output file.
+type Filesystem interface {
+	android.Module
+	OutputPath() android.Path
+}
+
+var _ Filesystem = (*filesystem)(nil)
+
+func (f *filesystem) OutputPath() android.Path {
+	return f.output
+}