build: new update-license.go

This version is less clever. All names are listed in a single file,
AUTHORS. All source files have the same header. This is an improvement
over the previous version, which attempted to list copyright holders in
each source file.

1 files changed, 346 insertions, 0 deletions

diff --git a/build/update-license.go b/build/update-license.go
new file mode 100644
index 000000000..5307f12ae
--- /dev/null
+++ b/build/update-license.go
@@ -0,0 +1,346 @@
+// +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
+
+All authors (people who have contributed code) are listed in the
+AUTHORS file. The author names are mapped and deduplicated using the
+.mailmap file. You can use .mailmap to set the canonical name and
+address for each author. See git-shortlog(1) for an explanation of the
+.mailmap format.
+
+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"
+	"sort"
+	"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
+		"Godeps/", "tests/files/", "build/",
+		// don't relicense vendored packages
+		"crypto/sha3/", "crypto/ecies/", "logger/glog/",
+	}
+
+	// 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)^/\*\s*(Copyright|This file is part of) .*?\*/\n*`)
+
+	// this text appears at the start of AUTHORS
+	authorsFileHeader = "# This is the official list of go-ethereum authors for copyright purposes.\n\n"
+)
+
+// this template generates the license comment.
+// its input is an info structure.
+var licenseT = template.Must(template.New("").Parse(`
+// Copyright {{.Year}} The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum 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.
+//
+// go-ethereum 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 go-ethereum.  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"
+	} else {
+		return "Lesser General Public License"
+	}
+}
+
+func (i info) ShortLicense() string {
+	if i.gpl() {
+		return "GPL"
+	} else {
+		return "LGPL"
+	}
+}
+
+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
+	)
+
+	writeAuthors(files)
+
+	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 getFiles() []string {
+	cmd := exec.Command("git", "ls-tree", "-r", "--name-only", "HEAD")
+	var files []string
+	err := doLines(cmd, func(line string) {
+		for _, p := range skipPrefixes {
+			if strings.HasPrefix(line, p) {
+				return
+			}
+		}
+		ext := filepath.Ext(line)
+		for _, wantExt := range extensions {
+			if ext == wantExt {
+				goto keep
+			}
+		}
+		return
+	keep:
+		files = append(files, line)
+	})
+	if err != nil {
+		log.Fatalf("error getting files:", err)
+	}
+	return files
+}
+
+var authorRegexp = regexp.MustCompile(`\s*[0-9]+\s*(.*)`)
+
+func gitAuthors(files []string) []string {
+	cmds := []string{"shortlog", "-s", "-n", "-e", "HEAD", "--"}
+	cmds = append(cmds, files...)
+	cmd := exec.Command("git", cmds...)
+	var authors []string
+	err := doLines(cmd, func(line string) {
+		m := authorRegexp.FindStringSubmatch(line)
+		if len(m) > 1 {
+			authors = append(authors, m[1])
+		}
+	})
+	if err != nil {
+		log.Fatalln("error getting authors:", err)
+	}
+	return authors
+}
+
+func readAuthors() []string {
+	content, err := ioutil.ReadFile("AUTHORS")
+	if err != nil && !os.IsNotExist(err) {
+		log.Fatalln("error reading AUTHORS:", err)
+	}
+	var authors []string
+	for _, a := range bytes.Split(content, []byte("\n")) {
+		if len(a) > 0 && a[0] != '#' {
+			authors = append(authors, string(a))
+		}
+	}
+	// Retranslate existing authors through .mailmap.
+	// This should catch email address changes.
+	authors = mailmapLookup(authors)
+	return authors
+}
+
+func mailmapLookup(authors []string) []string {
+	if len(authors) == 0 {
+		return nil
+	}
+	cmds := []string{"check-mailmap", "--"}
+	cmds = append(cmds, authors...)
+	cmd := exec.Command("git", cmds...)
+	var translated []string
+	err := doLines(cmd, func(line string) {
+		translated = append(translated, line)
+	})
+	if err != nil {
+		log.Fatalln("error translating authors:", err)
+	}
+	return translated
+}
+
+func writeAuthors(files []string) {
+	merge := make(map[string]bool)
+	// Add authors that Git reports as contributorxs.
+	// This is the primary source of author information.
+	for _, a := range gitAuthors(files) {
+		merge[a] = true
+	}
+	// Add existing authors from the file. This should ensure that we
+	// never lose authors, even if Git stops listing them. We can also
+	// add authors manually this way.
+	for _, a := range readAuthors() {
+		merge[a] = true
+	}
+	// Write sorted list of authors back to the file.
+	var result []string
+	for a := range merge {
+		result = append(result, a)
+	}
+	sort.Strings(result)
+	content := new(bytes.Buffer)
+	content.WriteString(authorsFileHeader)
+	for _, a := range result {
+		content.WriteString(a)
+		content.WriteString("\n")
+	}
+	fmt.Println("writing AUTHORS")
+	if err := ioutil.WriteFile("AUTHORS", content.Bytes(), 0644); err != nil {
+		log.Fatalln(err)
+	}
+}
+
+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
+		}
+		info, err := fileInfo(file)
+		if err != nil {
+			fmt.Printf("ERROR %s: %v\n", file, err)
+			continue
+		}
+		out <- info
+	}
+	wg.Done()
+}
+
+// fileInfo finds the lowest year in which the given file was commited.
+func fileInfo(file string) (*info, error) {
+	info := &info{file: file, Year: int64(time.Now().Year())}
+	cmd := exec.Command("git", "log", "--follow", "--find-copies", "--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
+}