copyright: test that all files in the repo have copyright notices

Adapted the script that I used to automatically add copyright notices
into a test that all files in the repository currently have appropriate
copyrights. Caught a few typos and extra spaces, which I decided to fix
rather than adjust regular expression.

Change-Id: Ifdbad969eca482e25c89afc5a2ddd5968c6661a6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/282592
Trust: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

blog/atom/atom.go

@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

blog/blog.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/compilebench/main.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/cover/cover_test.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/godoc/godoc_test.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/gomvpkg/main.go

@@ -1,6 +1,6 @@
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// licence that can be found in the LICENSE file.
+// license that can be found in the LICENSE file.
 
 // The gomvpkg command moves go packages, updating import declarations.
 // See the -help message or Usage constant for details.

cmd/html2article/conv.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/present/main.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/present/play.go

@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/toolstash/cmp.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

cmd/toolstash/main.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

container/intsets/popcnt_gccgo.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go 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/copyright.go

@@ -0,0 +1,107 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package copyright checks that files have the correct copyright notices.
+package copyright
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+func checkCopyright(dir string) ([]string, error) {
+	var files []string
+	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			// Skip directories like ".git".
+			if strings.HasPrefix(info.Name(), ".") {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		needsCopyright, err := checkFile(dir, path)
+		if err != nil {
+			return err
+		}
+		if needsCopyright {
+			files = append(files, path)
+		}
+		return nil
+	})
+	return files, err
+}
+
+var copyrightRe = regexp.MustCompile(`Copyright \d{4} The Go Authors. All rights reserved.
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file.`)
+
+func checkFile(toolsDir, filename string) (bool, error) {
+	// Only check Go files.
+	if !strings.HasSuffix(filename, "go") {
+		return false, nil
+	}
+	// Don't check testdata files.
+	normalized := strings.TrimPrefix(filepath.ToSlash(filename), filepath.ToSlash(toolsDir))
+	if strings.Contains(normalized, "/testdata/") {
+		return false, nil
+	}
+	// goyacc is the only file with a different copyright header.
+	if strings.HasSuffix(normalized, "cmd/goyacc/yacc.go") {
+		return false, nil
+	}
+	content, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return false, err
+	}
+	fset := token.NewFileSet()
+	parsed, err := parser.ParseFile(fset, filename, content, parser.ParseComments)
+	if err != nil {
+		return false, err
+	}
+	// Don't require headers on generated files.
+	if isGenerated(fset, parsed) {
+		return false, nil
+	}
+	shouldAddCopyright := true
+	for _, c := range parsed.Comments {
+		// The copyright should appear before the package declaration.
+		if c.Pos() > parsed.Package {
+			break
+		}
+		if copyrightRe.MatchString(c.Text()) {
+			shouldAddCopyright = false
+			break
+		}
+	}
+	return shouldAddCopyright, nil
+}
+
+// Copied from golang.org/x/tools/internal/lsp/source/util.go.
+// Matches cgo generated comment as well as the proposed standard:
+//	https://golang.org/s/generatedcode
+var generatedRx = regexp.MustCompile(`// .*DO NOT EDIT\.?`)
+
+func isGenerated(fset *token.FileSet, file *ast.File) bool {
+	for _, commentGroup := range file.Comments {
+		for _, comment := range commentGroup.List {
+			if matched := generatedRx.MatchString(comment.Text); !matched {
+				continue
+			}
+			// Check if comment is at the beginning of the line in source.
+			if pos := fset.Position(comment.Slash); pos.Column == 1 {
+				return true
+			}
+		}
+	}
+	return false
+}

copyright/copyright_test.go

@@ -0,0 +1,30 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package copyright
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestToolsCopyright(t *testing.T) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	tools := filepath.Dir(cwd)
+	if !strings.HasSuffix(filepath.Base(tools), "tools") {
+		t.Fatalf("current working directory is %s, expected tools", tools)
+	}
+	files, err := checkCopyright(tools)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(files) > 0 {
+		t.Errorf("The following files are missing copyright notices:\n%s", strings.Join(files, "\n"))
+	}
+}

go/ssa/interp/external.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

go/vcs/discovery.go

@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

go/vcs/env.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

go/vcs/http.go

@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

go/vcs/vcs.go

@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

go/vcs/vcs_test.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

playground/playground.go

@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

playground/socket/socket.go

@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

playground/socket/socket_test.go

@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 

refactor/rename/mvpkg.go

@@ -1,6 +1,6 @@
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// licence that can be found in the LICENSE file.
+// license that can be found in the LICENSE file.
 
 // This file contains the implementation of the 'gomvpkg' command
 // whose main function is in golang.org/x/tools/cmd/gomvpkg.

refactor/rename/mvpkg_test.go

@@ -1,6 +1,6 @@
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
-// licence that can be found in the LICENSE file.
+// license that can be found in the LICENSE file.
 
 package rename