filesystem/prebuilt.go

// Copyright (C) 2025 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package filesystem

import (
	"android/soong/android"

	"github.com/google/blueprint/proptools"
)

func init() {
	RegisterPrebuiltFilesystemComponents(android.InitRegistrationContext)
}

func RegisterPrebuiltFilesystemComponents(ctx android.RegistrationContext) {
	ctx.RegisterModuleType("android_system_image_prebuilt", PrebuiltSystemImageFactory)
}

type prebuiltSystemImageProperties struct {
	// A prebuilt system image file
	Src *string `android:"path"`
}

type prebuiltSystemImage struct {
	systemImage

	prebuiltProperties prebuiltSystemImageProperties
}

func (p *prebuiltSystemImage) GenerateAndroidBuildActions(ctx android.ModuleContext) {
	input := android.PathForModuleSrc(ctx, proptools.String(p.prebuiltProperties.Src))
	rootDir := android.PathForModuleOut(ctx, p.rootDirString()).OutputPath
	output := android.PathForModuleOut(ctx, p.installFileName())
	p.output = output

	// TODO: implement FilesystemInfo correctly to replace entire android_system_image.
	fsInfo := FilesystemInfo{
		ModuleName:       ctx.ModuleName(),
		PartitionName:    "system",
		RootDir:          rootDir,
		Output:           p.OutputPath(),
		SignedOutputPath: p.SignedOutputPath(),
		Prebuilt:         true,
	}
	android.SetProvider(ctx, FilesystemProvider, fsInfo)

	builder := android.NewRuleBuilder(pctx, ctx)
	rootdirTimestamp := android.PathForModuleOut(ctx, p.rootDirString()+".timestamp")

	switch p.fsType(ctx) {
	case erofsType:
		builder.Command().Textf("rm -rf %s && ", rootDir.String()).BuiltTool("fsck.erofs").Textf("--extract=%s", rootDir.String()).Input(input)
	case ext4Type:
		builder.Command().Textf("rm -rf %s && ", rootDir.String()).BuiltTool("debugfs").Flag("-R").Textf("'rdump / %s'", rootDir.String()).Input(input)
	default:
		ctx.ModuleErrorf("prebuilt system image only supports erofs and ext4 but was %q", p.fsType(ctx).String())
		return
	}

	builder.Command().Text("touch").Output(rootdirTimestamp)
	builder.Build("unpack_system_image", "unpacking prebuilt system image")

	ctx.Build(pctx, android.BuildParams{
		Rule:        android.Cp,
		Description: "install prebuilt system image",
		Output:      output,
		Input:       input,
		Implicit:    rootdirTimestamp,
	})
}

func PrebuiltSystemImageFactory() android.Module {
	module := &prebuiltSystemImage{}
	module.filesystemBuilder = module
	module.AddProperties(&module.prebuiltProperties)
	initBaseFilesystemModule(module, &module.systemImage.filesystem)
	return module
}