1 files changed, 301 insertions, 0 deletions
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
new file mode 100644
index 0000000..2793c2c
--- /dev/null
+++ b/src/cmd/gofmt/gofmt.go
@@ -0,0 +1,301 @@
+// 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.
+
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/scanner"
+	"go/token"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+	"runtime/pprof"
+	"strings"
+
+	"cmd/internal/diff"
+)
+
+var (
+	// main operation modes
+	list        = flag.Bool("l", false, "list files whose formatting differs from gofmt's")
+	write       = flag.Bool("w", false, "write result to (source) file instead of stdout")
+	rewriteRule = flag.String("r", "", "rewrite rule (e.g., 'a[b:len(a)] -> a[b:]')")
+	simplifyAST = flag.Bool("s", false, "simplify code")
+	doDiff      = flag.Bool("d", false, "display diffs instead of rewriting files")
+	allErrors   = flag.Bool("e", false, "report all errors (not just the first 10 on different lines)")
+
+	// debugging
+	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
+)
+
+// Keep these in sync with go/format/format.go.
+const (
+	tabWidth    = 8
+	printerMode = printer.UseSpaces | printer.TabIndent | printerNormalizeNumbers
+
+	// printerNormalizeNumbers means to canonicalize number literal prefixes
+	// and exponents while printing. See https://golang.org/doc/go1.13#gofmt.
+	//
+	// This value is defined in go/printer specifically for go/format and cmd/gofmt.
+	printerNormalizeNumbers = 1 << 30
+)
+
+var (
+	fileSet    = token.NewFileSet() // per process FileSet
+	exitCode   = 0
+	rewrite    func(*ast.File) *ast.File
+	parserMode parser.Mode
+)
+
+func report(err error) {
+	scanner.PrintError(os.Stderr, err)
+	exitCode = 2
+}
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [path ...]\n")
+	flag.PrintDefaults()
+}
+
+func initParserMode() {
+	parserMode = parser.ParseComments
+	if *allErrors {
+		parserMode |= parser.AllErrors
+	}
+}
+
+func isGoFile(f fs.DirEntry) bool {
+	// ignore non-Go files
+	name := f.Name()
+	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
+}
+
+// If in == nil, the source is the contents of the file with the given filename.
+func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error {
+	var perm fs.FileMode = 0644
+	if in == nil {
+		f, err := os.Open(filename)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		fi, err := f.Stat()
+		if err != nil {
+			return err
+		}
+		in = f
+		perm = fi.Mode().Perm()
+	}
+
+	src, err := io.ReadAll(in)
+	if err != nil {
+		return err
+	}
+
+	file, sourceAdj, indentAdj, err := parse(fileSet, filename, src, stdin)
+	if err != nil {
+		return err
+	}
+
+	if rewrite != nil {
+		if sourceAdj == nil {
+			file = rewrite(file)
+		} else {
+			fmt.Fprintf(os.Stderr, "warning: rewrite ignored for incomplete programs\n")
+		}
+	}
+
+	ast.SortImports(fileSet, file)
+
+	if *simplifyAST {
+		simplify(file)
+	}
+
+	res, err := format(fileSet, file, sourceAdj, indentAdj, src, printer.Config{Mode: printerMode, Tabwidth: tabWidth})
+	if err != nil {
+		return err
+	}
+
+	if !bytes.Equal(src, res) {
+		// formatting has changed
+		if *list {
+			fmt.Fprintln(out, filename)
+		}
+		if *write {
+			// make a temporary backup before overwriting original
+			bakname, err := backupFile(filename+".", src, perm)
+			if err != nil {
+				return err
+			}
+			err = os.WriteFile(filename, res, perm)
+			if err != nil {
+				os.Rename(bakname, filename)
+				return err
+			}
+			err = os.Remove(bakname)
+			if err != nil {
+				return err
+			}
+		}
+		if *doDiff {
+			data, err := diffWithReplaceTempFile(src, res, filename)
+			if err != nil {
+				return fmt.Errorf("computing diff: %s", err)
+			}
+			fmt.Printf("diff -u %s %s\n", filepath.ToSlash(filename+".orig"), filepath.ToSlash(filename))
+			out.Write(data)
+		}
+	}
+
+	if !*list && !*write && !*doDiff {
+		_, err = out.Write(res)
+	}
+
+	return err
+}
+
+func visitFile(path string, f fs.DirEntry, err error) error {
+	if err == nil && isGoFile(f) {
+		err = processFile(path, nil, os.Stdout, false)
+	}
+	// Don't complain if a file was deleted in the meantime (i.e.
+	// the directory changed concurrently while running gofmt).
+	if err != nil && !os.IsNotExist(err) {
+		report(err)
+	}
+	return nil
+}
+
+func walkDir(path string) {
+	filepath.WalkDir(path, visitFile)
+}
+
+func main() {
+	// call gofmtMain in a separate function
+	// so that it can use defer and have them
+	// run before the exit.
+	gofmtMain()
+	os.Exit(exitCode)
+}
+
+func gofmtMain() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *cpuprofile != "" {
+		f, err := os.Create(*cpuprofile)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "creating cpu profile: %s\n", err)
+			exitCode = 2
+			return
+		}
+		defer f.Close()
+		pprof.StartCPUProfile(f)
+		defer pprof.StopCPUProfile()
+	}
+
+	initParserMode()
+	initRewrite()
+
+	if flag.NArg() == 0 {
+		if *write {
+			fmt.Fprintln(os.Stderr, "error: cannot use -w with standard input")
+			exitCode = 2
+			return
+		}
+		if err := processFile("<standard input>", os.Stdin, os.Stdout, true); err != nil {
+			report(err)
+		}
+		return
+	}
+
+	for i := 0; i < flag.NArg(); i++ {
+		path := flag.Arg(i)
+		switch dir, err := os.Stat(path); {
+		case err != nil:
+			report(err)
+		case dir.IsDir():
+			walkDir(path)
+		default:
+			if err := processFile(path, nil, os.Stdout, false); err != nil {
+				report(err)
+			}
+		}
+	}
+}
+
+func diffWithReplaceTempFile(b1, b2 []byte, filename string) ([]byte, error) {
+	data, err := diff.Diff("gofmt", b1, b2)
+	if len(data) > 0 {
+		return replaceTempFilename(data, filename)
+	}
+	return data, err
+}
+
+// replaceTempFilename replaces temporary filenames in diff with actual one.
+//
+// --- /tmp/gofmt316145376	2017-02-03 19:13:00.280468375 -0500
+// +++ /tmp/gofmt617882815	2017-02-03 19:13:00.280468375 -0500
+// ...
+// ->
+// --- path/to/file.go.orig	2017-02-03 19:13:00.280468375 -0500
+// +++ path/to/file.go	2017-02-03 19:13:00.280468375 -0500
+// ...
+func replaceTempFilename(diff []byte, filename string) ([]byte, error) {
+	bs := bytes.SplitN(diff, []byte{'\n'}, 3)
+	if len(bs) < 3 {
+		return nil, fmt.Errorf("got unexpected diff for %s", filename)
+	}
+	// Preserve timestamps.
+	var t0, t1 []byte
+	if i := bytes.LastIndexByte(bs[0], '\t'); i != -1 {
+		t0 = bs[0][i:]
+	}
+	if i := bytes.LastIndexByte(bs[1], '\t'); i != -1 {
+		t1 = bs[1][i:]
+	}
+	// Always print filepath with slash separator.
+	f := filepath.ToSlash(filename)
+	bs[0] = []byte(fmt.Sprintf("--- %s%s", f+".orig", t0))
+	bs[1] = []byte(fmt.Sprintf("+++ %s%s", f, t1))
+	return bytes.Join(bs, []byte{'\n'}), nil
+}
+
+const chmodSupported = runtime.GOOS != "windows"
+
+// backupFile writes data to a new file named filename<number> with permissions perm,
+// with <number randomly chosen such that the file name is unique. backupFile returns
+// the chosen file name.
+func backupFile(filename string, data []byte, perm fs.FileMode) (string, error) {
+	// create backup file
+	f, err := os.CreateTemp(filepath.Dir(filename), filepath.Base(filename))
+	if err != nil {
+		return "", err
+	}
+	bakname := f.Name()
+	if chmodSupported {
+		err = f.Chmod(perm)
+		if err != nil {
+			f.Close()
+			os.Remove(bakname)
+			return bakname, err
+		}
+	}
+
+	// write data to backup file
+	_, err = f.Write(data)
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+
+	return bakname, err
+}