tailscale/cmd/addlicense/main.go

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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Program addlicense adds a license header to a file.
// It is intended for use with 'go generate',
// so it has a slightly weird usage.
package main
import (
"flag"
"fmt"
"os"
"os/exec"
)
var (
year = flag.Int("year", 0, "copyright year")
file = flag.String("file", "", "file to modify")
)
func usage() {
fmt.Fprintf(os.Stderr, `
usage: addlicense -year YEAR -file FILE <subcommand args...>
`[1:])
flag.PrintDefaults()
fmt.Fprintf(os.Stderr, `
addlicense adds a Tailscale license to the beginning of file,
using year as the copyright year.
It is intended for use with 'go generate', so it also runs a subcommand,
which presumably creates the file.
Sample usage:
addlicense -year 2021 -file pull_strings.go stringer -type=pull
`[1:])
os.Exit(2)
}
func main() {
flag.Usage = usage
flag.Parse()
if len(flag.Args()) == 0 {
flag.Usage()
}
cmd := exec.Command(flag.Arg(0), flag.Args()[1:]...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
check(err)
b, err := os.ReadFile(*file)
check(err)
f, err := os.OpenFile(*file, os.O_TRUNC|os.O_WRONLY, 0644)
check(err)
_, err = fmt.Fprintf(f, license, *year)
check(err)
_, err = f.Write(b)
check(err)
err = f.Close()
check(err)
}
func check(err error) {
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
var license = `
// Copyright (c) %d Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
`[1:]