From 947c14793a9a9e0ff5e0984fe40b3cf7c79f240e Mon Sep 17 00:00:00 2001
From: Will Norris <will@tailscale.com>
Date: Fri, 27 Jan 2023 13:36:46 -0800
Subject: [PATCH] all: update tools that manage copyright headers

Update all code generation tools, and those that check for license
headers to use the new standard header.

Also update copyright statement in LICENSE file.

Fixes #6865

Signed-off-by: Will Norris <will@tailscale.com>
---
 LICENSE                                    |  3 +-
 cmd/addlicense/main.go                     | 15 ++---
 cmd/cloner/cloner.go                       |  2 +-
 cmd/viewer/viewer.go                       |  2 +-
 derp/derp_server.go                        |  2 +-
 net/portmapper/pcp.go                      |  2 +-
 net/portmapper/portmapper.go               |  2 +-
 scripts/check_license_headers.sh           | 19 +++---
 tstest/integration/gen_deps.go             |  5 +-
 tstest/integration/vms/gen/test_codegen.go |  7 +--
 util/codegen/codegen.go                    | 68 ++--------------------
 wgengine/magicsock/magicsock.go            |  2 +-
 12 files changed, 31 insertions(+), 98 deletions(-)

diff --git a/LICENSE b/LICENSE
index 66284d31a..394db19e4 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,7 +1,6 @@
 BSD 3-Clause License
 
-Copyright (c) 2020 Tailscale & AUTHORS.
-All rights reserved.
+Copyright (c) 2020 Tailscale Inc & AUTHORS.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
diff --git a/cmd/addlicense/main.go b/cmd/addlicense/main.go
index 856bc8b86..a8fd9dd4a 100644
--- a/cmd/addlicense/main.go
+++ b/cmd/addlicense/main.go
@@ -14,26 +14,24 @@ import (
 )
 
 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...>
+usage: addlicense -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.
+addlicense adds a Tailscale license to the beginning of file.
 
 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
+addlicense -file pull_strings.go stringer -type=pull
 `[1:])
 	os.Exit(2)
 }
@@ -53,7 +51,7 @@ func main() {
 	check(err)
 	f, err := os.OpenFile(*file, os.O_TRUNC|os.O_WRONLY, 0644)
 	check(err)
-	_, err = fmt.Fprintf(f, license, *year)
+	_, err = fmt.Fprint(f, license)
 	check(err)
 	_, err = f.Write(b)
 	check(err)
@@ -69,8 +67,7 @@ func check(err error) {
 }
 
 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.
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
 
 `[1:]
diff --git a/cmd/cloner/cloner.go b/cmd/cloner/cloner.go
index 37c8a30a5..11ee55078 100644
--- a/cmd/cloner/cloner.go
+++ b/cmd/cloner/cloner.go
@@ -79,7 +79,7 @@ func main() {
 		w("}")
 	}
 	cloneOutput := pkg.Name + "_clone.go"
-	if err := codegen.WritePackageFile("tailscale.com/cmd/cloner", pkg, cloneOutput, codegen.CopyrightYear("."), it, buf); err != nil {
+	if err := codegen.WritePackageFile("tailscale.com/cmd/cloner", pkg, cloneOutput, it, buf); err != nil {
 		log.Fatal(err)
 	}
 }
diff --git a/cmd/viewer/viewer.go b/cmd/viewer/viewer.go
index 058d107fc..0dc0b1dfb 100644
--- a/cmd/viewer/viewer.go
+++ b/cmd/viewer/viewer.go
@@ -383,7 +383,7 @@ func main() {
 		genView(buf, it, typ, pkg.Types)
 	}
 	out := pkg.Name + "_view.go"
-	if err := codegen.WritePackageFile("tailscale/cmd/viewer", pkg, out, codegen.CopyrightYear("."), it, buf); err != nil {
+	if err := codegen.WritePackageFile("tailscale/cmd/viewer", pkg, out, it, buf); err != nil {
 		log.Fatal(err)
 	}
 	if runCloner {
diff --git a/derp/derp_server.go b/derp/derp_server.go
index 1f1c22650..7714943cb 100644
--- a/derp/derp_server.go
+++ b/derp/derp_server.go
@@ -955,7 +955,7 @@ func (c *sclient) handleFrameSendPacket(ft frameType, fl uint32) error {
 // dropReason is why we dropped a DERP frame.
 type dropReason int
 
-//go:generate go run tailscale.com/cmd/addlicense -year 2021 -file dropreason_string.go go run golang.org/x/tools/cmd/stringer -type=dropReason -trimprefix=dropReason
+//go:generate go run tailscale.com/cmd/addlicense -file dropreason_string.go go run golang.org/x/tools/cmd/stringer -type=dropReason -trimprefix=dropReason
 
 const (
 	dropReasonUnknownDest      dropReason = iota // unknown destination pubkey
diff --git a/net/portmapper/pcp.go b/net/portmapper/pcp.go
index 455b7f471..c1d62b02b 100644
--- a/net/portmapper/pcp.go
+++ b/net/portmapper/pcp.go
@@ -17,7 +17,7 @@ import (
 // https://www.rfc-editor.org/rfc/pdfrfc/rfc6887.txt.pdf
 // https://tools.ietf.org/html/rfc6887
 
-//go:generate go run tailscale.com/cmd/addlicense -year 2021 -file pcpresultcode_string.go go run golang.org/x/tools/cmd/stringer -type=pcpResultCode -trimprefix=pcpCode
+//go:generate go run tailscale.com/cmd/addlicense -file pcpresultcode_string.go go run golang.org/x/tools/cmd/stringer -type=pcpResultCode -trimprefix=pcpCode
 
 type pcpResultCode uint8
 
diff --git a/net/portmapper/portmapper.go b/net/portmapper/portmapper.go
index 2e3fdacf1..8cb565b68 100644
--- a/net/portmapper/portmapper.go
+++ b/net/portmapper/portmapper.go
@@ -586,7 +586,7 @@ func (c *Client) createOrGetMapping(ctx context.Context) (external netip.AddrPor
 	}
 }
 
-//go:generate go run tailscale.com/cmd/addlicense -year 2021 -file pmpresultcode_string.go go run golang.org/x/tools/cmd/stringer -type=pmpResultCode -trimprefix=pmpCode
+//go:generate go run tailscale.com/cmd/addlicense -file pmpresultcode_string.go go run golang.org/x/tools/cmd/stringer -type=pmpResultCode -trimprefix=pmpCode
 
 type pmpResultCode uint16
 
diff --git a/scripts/check_license_headers.sh b/scripts/check_license_headers.sh
index 8b9cbbc30..89a243b63 100755
--- a/scripts/check_license_headers.sh
+++ b/scripts/check_license_headers.sh
@@ -9,17 +9,14 @@
 check_file() {
     got=$1
 
-    for year in `seq 2019 2023`; do
-        want=$(cat <<EOF
-// Copyright (c) $year Tailscale Inc & AUTHORS All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
+    want=$(cat <<EOF
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
 EOF
-        )
-        if [ "$got" = "$want" ]; then
-            return 0
-        fi
-    done
+    )
+    if [ "$got" = "$want" ]; then
+        return 0
+    fi
     return 1
 }
 
@@ -50,7 +47,7 @@ for file in $(find $1 -name '*.go' -not -path '*/.git/*'); do
             # Generated syscall wrappers
         ;;
         *)
-            header="$(head -3 $file)"
+            header="$(head -2 $file)"
             if ! check_file "$header"; then
                 fail=1
                 echo "${file#$1/} doesn't have the right copyright header:"
diff --git a/tstest/integration/gen_deps.go b/tstest/integration/gen_deps.go
index d31f175d6..23bb95ee5 100644
--- a/tstest/integration/gen_deps.go
+++ b/tstest/integration/gen_deps.go
@@ -35,9 +35,8 @@ func generate(goos string) {
 		log.Fatal(err)
 	}
 	var out bytes.Buffer
-	out.WriteString(`// 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.
+	out.WriteString(`// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
 
 // Code generated by gen_deps.go; DO NOT EDIT.
 
diff --git a/tstest/integration/vms/gen/test_codegen.go b/tstest/integration/vms/gen/test_codegen.go
index a7bc596c9..4fc108c73 100644
--- a/tstest/integration/vms/gen/test_codegen.go
+++ b/tstest/integration/vms/gen/test_codegen.go
@@ -7,10 +7,8 @@ package main
 
 import (
 	_ "embed"
-	"fmt"
 	"log"
 	"os"
-	"time"
 
 	"github.com/dave/jennifer/jen"
 	"github.com/iancoleman/strcase"
@@ -41,9 +39,8 @@ func main() {
 	}
 	defer fout.Close()
 
-	fmt.Fprintf(fout, "// Copyright (c) %d Tailscale Inc & AUTHORS All rights reserved.\n", time.Now().Year())
-	fout.WriteString("// Use of this source code is governed by a BSD-style\n")
-	fout.WriteString("// license that can be found in the LICENSE file.\n")
+	fout.WriteString("// Copyright (c) Tailscale Inc & AUTHORS\n")
+	fout.WriteString("// SPDX-License-Identifier: BSD-3-Clause\n")
 	fout.WriteString("\n")
 	fout.WriteString("// +build linux\n\n")
 
diff --git a/util/codegen/codegen.go b/util/codegen/codegen.go
index f35450810..364a9b69e 100644
--- a/util/codegen/codegen.go
+++ b/util/codegen/codegen.go
@@ -5,7 +5,6 @@
 package codegen
 
 import (
-	"bufio"
 	"bytes"
 	"fmt"
 	"go/ast"
@@ -13,16 +12,12 @@ import (
 	"go/types"
 	"io"
 	"os"
-	"path/filepath"
 	"reflect"
-	"regexp"
-	"strconv"
 	"strings"
 
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/imports"
 	"tailscale.com/util/mak"
-	"tailscale.com/util/must"
 )
 
 // LoadTypes returns all named types in pkgName, keyed by their type name.
@@ -57,9 +52,8 @@ func HasNoClone(structTag string) bool {
 	return false
 }
 
-const copyrightHeader = `// 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.
+const copyrightHeader = `// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
 
 `
 
@@ -109,18 +103,16 @@ func (it *ImportTracker) Write(w io.Writer) {
 	fmt.Fprintf(w, ")\n\n")
 }
 
-func writeHeader(w io.Writer, tool, pkg string, copyrightYear int) {
-	if copyrightYear != 0 {
-		fmt.Fprintf(w, copyrightHeader, copyrightYear)
-	}
+func writeHeader(w io.Writer, tool, pkg string) {
+	fmt.Fprint(w, copyrightHeader)
 	fmt.Fprintf(w, genAndPackageHeader, tool, pkg)
 }
 
 // WritePackageFile adds a file with the provided imports and contents to package.
 // The tool param is used to identify the tool that generated package file.
-func WritePackageFile(tool string, pkg *packages.Package, path string, copyrightYear int, it *ImportTracker, contents *bytes.Buffer) error {
+func WritePackageFile(tool string, pkg *packages.Package, path string, it *ImportTracker, contents *bytes.Buffer) error {
 	buf := new(bytes.Buffer)
-	writeHeader(buf, tool, pkg.Name, copyrightYear)
+	writeHeader(buf, tool, pkg.Name)
 	it.Write(buf)
 	if _, err := buf.Write(contents.Bytes()); err != nil {
 		return err
@@ -271,51 +263,3 @@ func IsViewType(typ types.Type) bool {
 	}
 	return t.Field(0).Name() == "ж"
 }
-
-// CopyrightYear reports the greatest copyright year in non-generated *.go files
-// in the current directory, for use in the copyright line of generated code.
-//
-// It panics on I/O error, as it's assumed this is only being used by "go
-// generate" or GitHub actions.
-//
-// TODO(bradfitz,dgentry): determine what heuristic to use for all this: latest
-// year, earliest, none? don't list years at all? IANAL. Get advice of others.
-// For now we just want to unbreak the tree. See Issue 6865.
-func CopyrightYear(dir string) (year int) {
-	files, err := os.ReadDir(dir)
-	if err != nil {
-		panic(err)
-	}
-	rxYear := regexp.MustCompile(`^// Copyright \(c\) (20\d{2}) `)
-	rxGenerated := regexp.MustCompile(`^// Code generated .* DO NOT EDIT\.$`)
-Files:
-	for _, f := range files {
-		name := f.Name()
-		if !f.Type().IsRegular() ||
-			strings.HasPrefix(name, ".") || // includes emacs noise
-			!strings.HasSuffix(name, ".go") ||
-			strings.HasSuffix(name, "_clone.go") ||
-			strings.HasSuffix(name, "_view.go") ||
-			strings.HasSuffix(name, "_test.go") {
-			continue
-		}
-		src, err := os.ReadFile(filepath.Join(dir, name))
-		if err != nil {
-			panic(err)
-		}
-		bs := bufio.NewScanner(bytes.NewReader(src))
-		for bs.Scan() {
-			line := bs.Bytes()
-			if m := rxYear.FindSubmatch(line); m != nil {
-				if y := must.Get(strconv.Atoi(string(m[1]))); y > year {
-					year = y
-				}
-				continue
-			}
-			if rxGenerated.Match(line) {
-				continue Files
-			}
-		}
-	}
-	return year
-}
diff --git a/wgengine/magicsock/magicsock.go b/wgengine/magicsock/magicsock.go
index 5fb428f71..da756150a 100644
--- a/wgengine/magicsock/magicsock.go
+++ b/wgengine/magicsock/magicsock.go
@@ -4061,7 +4061,7 @@ func (de *endpoint) sendDiscoPing(ep netip.AddrPort, discoKey key.DiscoPublic, t
 // discoPingPurpose is the reason why a discovery ping message was sent.
 type discoPingPurpose int
 
-//go:generate go run tailscale.com/cmd/addlicense -year 2020 -file discopingpurpose_string.go go run golang.org/x/tools/cmd/stringer -type=discoPingPurpose -trimprefix=ping
+//go:generate go run tailscale.com/cmd/addlicense -file discopingpurpose_string.go go run golang.org/x/tools/cmd/stringer -type=discoPingPurpose -trimprefix=ping
 const (
 	// pingDiscovery means that purpose of a ping was to see if a
 	// path was valid.