cmd/embed/main.go

// Copyright (C) 2016 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.

// The embed command is used to embed text files into Go executables as strings.
package main

import (
	"bytes"
	"flag"
	"fmt"
	"io/ioutil"
	"path/filepath"
	"strings"

	"android.googlesource.com/platform/tools/gpu/framework/app"
	"android.googlesource.com/platform/tools/gpu/framework/log"

	"golang.org/x/tools/imports"
)

var (
	pkg    string
	output string
)

const header = `
////////////////////////////////////////////////////////////////////////////////
// Do not modify!
// Generated by embed
////////////////////////////////////////////////////////////////////////////////

package %s

`

func main() {
	flag.StringVar(&pkg, "package", "", "the package to use, defaults to the dir name")
	flag.StringVar(&output, "out", "embed.go", "the file to generate")
	app.ShortHelp = "embed: A tool to embed files into go source."
	app.Run(run)
}

type embed struct {
	path     string
	filename string
	name     string
	contents []byte
}

func run(ctx log.Context) error {
	args := flag.Args()
	entries := []*embed{}
	if len(args) == 0 {
		pwd, err := filepath.Abs(".")
		if err != nil {
			return err
		}
		files, err := ioutil.ReadDir(pwd)
		if err != nil {
			return err
		}
		for _, info := range files {
			if info.IsDir() {
				continue
			}
			extension := filepath.Ext(info.Name())
			if extension == ".go" {
				continue
			}
			path := filepath.Join(pwd, info.Name())
			entries = append(entries, &embed{path: path})
		}
	} else {
		for _, arg := range args {
			path, err := filepath.Abs(arg)
			if err != nil {
				return err
			}
			entries = append(entries, &embed{path: path})
		}
	}
	var err error
	for _, entry := range entries {
		entry.filename = filepath.Base(entry.path)
		entry.name = strings.Replace(entry.filename, ".", "_", -1)
		entry.contents, err = ioutil.ReadFile(entry.path)
		if err != nil {
			return err
		}
	}
	// write the header
	out, err := filepath.Abs(output)
	if err != nil {
		return err
	}
	if pkg == "" {
		pkg = filepath.Base(filepath.Dir(out))
	}
	b := &bytes.Buffer{}
	fmt.Fprintf(b, header, pkg)
	// write the map
	fmt.Fprint(b, "var embedded = map[string]string{\n")
	for _, entry := range entries {
		fmt.Fprintf(b, "%s_file:\n%s,\n", entry.name, entry.name)
	}
	fmt.Fprint(b, "}\n")
	// write the data lumps
	for _, entry := range entries {
		fmt.Fprintf(b, "const %s_file = `%s`\n", entry.name, entry.filename)
		fmt.Fprintf(b, "const %s = `", entry.name)
		fmt.Fprint(b, strings.Replace(string(entry.contents), "`", "` + \"`\" + `", -1))
		fmt.Fprint(b, "`\n")
		ctx.Printf("Embed %s from %s\n", entry.name, entry.path)
	}
	// reformat the output
	result, err := imports.Process("", b.Bytes(), nil)
	if err != nil {
		result = b.Bytes()
	}
	if err := ioutil.WriteFile(out, result, 0666); err != nil {
		return err
	}
	return nil
}