github.com/core-coin/go-core/v2@v2.1.9/build/update-license.go

// Copyright 2015 by The go-core Authors
// This file is part of the go-core library.
//
// The go-core library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-core library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-core library. If not, see <http://www.gnu.org/licenses/>.

//go:build none
// +build none

/*
This command generates GPL license headers on top of all source files.
You can run it once per month, before cutting a release or just
whenever you feel like it.

	go run update-license.go

Please review the resulting diff to check whether the correct
copyright assignments are performed.
*/

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"text/template"
	"time"
)

var (
	// only files with these extensions will be considered
	extensions = []string{".go", ".js", ".qml"}

	// paths with any of these prefixes will be skipped
	skipPrefixes = []string{
		// boring stuff
		"vendor/", "tests/testdata/", "build/",

		// don't relicense vendored sources
		"cmd/internal/browser",
		"common/bitutil/bitutil",
		"common/prque/",
		"crypto/bn256/",
		"crypto/ecies/",
		"graphql/graphiql.go",
		"internal/jsre/deps",
		"log/",
		"metrics/",
		"signer/rules/deps",
	}

	// paths with this prefix are licensed as GPL. all other files are LGPL.
	gplPrefixes = []string{"cmd/"}

	// this regexp must match the entire license comment at the
	// beginning of each file.
	licenseCommentRE = regexp.MustCompile(`^//\s*(Copyright|This file is part of).*?\n(?://.*?\n)*\n*`)
)

// this template generates the license comment.
// its input is an info structure.
var licenseT = template.Must(template.New("").Parse(`
// Copyright {{.Year}} by the Authors
// This file is part of {{.Whole false}}.
//
// {{.Whole true}} is free software: you can redistribute it and/or modify
// it under the terms of the GNU {{.License}} as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// {{.Whole true}} is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU {{.License}} for more details.
//
// You should have received a copy of the GNU {{.License}}
// along with {{.Whole false}}. If not, see <http://www.gnu.org/licenses/>.

`[1:]))

type info struct {
	file string
	Year int64
}

func (i info) License() string {
	if i.gpl() {
		return "General Public License"
	}
	return "Lesser General Public License"
}

func (i info) ShortLicense() string {
	if i.gpl() {
		return "GPL"
	}
	return "LGPL"
}

func (i info) Whole(startOfSentence bool) string {
	if i.gpl() {
		return "go-core"
	}
	if startOfSentence {
		return "The go-core library"
	}
	return "the go-core library"
}

func (i info) gpl() bool {
	for _, p := range gplPrefixes {
		if strings.HasPrefix(i.file, p) {
			return true
		}
	}
	return false
}

func main() {
	var (
		files = getFiles()
		filec = make(chan string)
		infoc = make(chan *info, 20)
		wg    sync.WaitGroup
	)

	go func() {
		for _, f := range files {
			filec <- f
		}
		close(filec)
	}()
	for i := runtime.NumCPU(); i >= 0; i-- {
		// getting file info is slow and needs to be parallel.
		// it traverses git history for each file.
		wg.Add(1)
		go getInfo(filec, infoc, &wg)
	}
	go func() {
		wg.Wait()
		close(infoc)
	}()
	writeLicenses(infoc)
}

func skipFile(path string) bool {
	if strings.Contains(path, "/testdata/") {
		return true
	}
	for _, p := range skipPrefixes {
		if strings.HasPrefix(path, p) {
			return true
		}
	}
	return false
}

func getFiles() []string {
	cmd := exec.Command("git", "ls-tree", "-r", "--name-only", "HEAD")
	var files []string
	err := doLines(cmd, func(line string) {
		if skipFile(line) {
			return
		}
		ext := filepath.Ext(line)
		for _, wantExt := range extensions {
			if ext == wantExt {
				goto keep
			}
		}
		return
	keep:
		files = append(files, line)
	})
	if err != nil {
		log.Fatal("error getting files:", err)
	}
	return files
}

func getInfo(files <-chan string, out chan<- *info, wg *sync.WaitGroup) {
	for file := range files {
		stat, err := os.Lstat(file)
		if err != nil {
			fmt.Printf("ERROR %s: %v\n", file, err)
			continue
		}
		if !stat.Mode().IsRegular() {
			continue
		}
		if isGenerated(file) {
			continue
		}
		info, err := fileInfo(file)
		if err != nil {
			fmt.Printf("ERROR %s: %v\n", file, err)
			continue
		}
		out <- info
	}
	wg.Done()
}

func isGenerated(file string) bool {
	fd, err := os.Open(file)
	if err != nil {
		return false
	}
	defer fd.Close()
	buf := make([]byte, 2048)
	n, _ := fd.Read(buf)
	buf = buf[:n]
	for _, l := range bytes.Split(buf, []byte("\n")) {
		if bytes.HasPrefix(l, []byte("// Code generated")) {
			return true
		}
	}
	return false
}

// fileInfo finds the lowest year in which the given file was committed.
func fileInfo(file string) (*info, error) {
	info := &info{file: file, Year: int64(time.Now().Year())}
	cmd := exec.Command("git", "log", "--follow", "--find-renames=80", "--find-copies=80", "--pretty=format:%ai", "--", file)
	err := doLines(cmd, func(line string) {
		y, err := strconv.ParseInt(line[:4], 10, 64)
		if err != nil {
			fmt.Printf("cannot parse year: %q", line[:4])
		}
		if y < info.Year {
			info.Year = y
		}
	})
	return info, err
}

func writeLicenses(infos <-chan *info) {
	for i := range infos {
		writeLicense(i)
	}
}

func writeLicense(info *info) {
	fi, err := os.Stat(info.file)
	if os.IsNotExist(err) {
		fmt.Println("skipping (does not exist)", info.file)
		return
	}
	if err != nil {
		log.Fatalf("error stat'ing %s: %v\n", info.file, err)
	}
	content, err := ioutil.ReadFile(info.file)
	if err != nil {
		log.Fatalf("error reading %s: %v\n", info.file, err)
	}
	// Construct new file content.
	buf := new(bytes.Buffer)
	licenseT.Execute(buf, info)
	if m := licenseCommentRE.FindIndex(content); m != nil && m[0] == 0 {
		buf.Write(content[:m[0]])
		buf.Write(content[m[1]:])
	} else {
		buf.Write(content)
	}
	// Write it to the file.
	if bytes.Equal(content, buf.Bytes()) {
		fmt.Println("skipping (no changes)", info.file)
		return
	}
	fmt.Println("writing", info.ShortLicense(), info.file)
	if err := ioutil.WriteFile(info.file, buf.Bytes(), fi.Mode()); err != nil {
		log.Fatalf("error writing %s: %v", info.file, err)
	}
}

func doLines(cmd *exec.Cmd, f func(string)) error {
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return err
	}
	if err := cmd.Start(); err != nil {
		return err
	}
	s := bufio.NewScanner(stdout)
	for s.Scan() {
		f(s.Text())
	}
	if s.Err() != nil {
		return s.Err()
	}
	if err := cmd.Wait(); err != nil {
		return fmt.Errorf("%v (for %s)", err, strings.Join(cmd.Args, " "))
	}
	return nil
}