Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 570 insertions, 0 deletions

diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
new file mode 100644
index 0000000..f4fb6bf
--- /dev/null
+++ b/src/cmd/gofmt/gofmt.go
@@ -0,0 +1,570 @@
+// 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"
+	"context"
+	"flag"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/scanner"
+	"go/token"
+	"internal/diff"
+	"io"
+	"io/fs"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"runtime"
+	"runtime/pprof"
+	"strconv"
+	"strings"
+
+	"golang.org/x/sync/semaphore"
+)
+
+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
+)
+
+// fdSem guards the number of concurrently-open file descriptors.
+//
+// For now, this is arbitrarily set to 200, based on the observation that many
+// platforms default to a kernel limit of 256. Ideally, perhaps we should derive
+// it from rlimit on platforms that support that system call.
+//
+// File descriptors opened from outside of this package are not tracked,
+// so this limit may be approximate.
+var fdSem = make(chan bool, 200)
+
+var (
+	rewrite    func(*token.FileSet, *ast.File) *ast.File
+	parserMode parser.Mode
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [path ...]\n")
+	flag.PrintDefaults()
+}
+
+func initParserMode() {
+	parserMode = parser.ParseComments
+	if *allErrors {
+		parserMode |= parser.AllErrors
+	}
+	// It's only -r that makes use of go/ast's object resolution,
+	// so avoid the unnecessary work if the flag isn't used.
+	if *rewriteRule == "" {
+		parserMode |= parser.SkipObjectResolution
+	}
+}
+
+func isGoFile(f fs.DirEntry) bool {
+	// ignore non-Go files
+	name := f.Name()
+	return !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go") && !f.IsDir()
+}
+
+// A sequencer performs concurrent tasks that may write output, but emits that
+// output in a deterministic order.
+type sequencer struct {
+	maxWeight int64
+	sem       *semaphore.Weighted   // weighted by input bytes (an approximate proxy for memory overhead)
+	prev      <-chan *reporterState // 1-buffered
+}
+
+// newSequencer returns a sequencer that allows concurrent tasks up to maxWeight
+// and writes tasks' output to out and err.
+func newSequencer(maxWeight int64, out, err io.Writer) *sequencer {
+	sem := semaphore.NewWeighted(maxWeight)
+	prev := make(chan *reporterState, 1)
+	prev <- &reporterState{out: out, err: err}
+	return &sequencer{
+		maxWeight: maxWeight,
+		sem:       sem,
+		prev:      prev,
+	}
+}
+
+// exclusive is a weight that can be passed to a sequencer to cause
+// a task to be executed without any other concurrent tasks.
+const exclusive = -1
+
+// Add blocks until the sequencer has enough weight to spare, then adds f as a
+// task to be executed concurrently.
+//
+// If the weight is either negative or larger than the sequencer's maximum
+// weight, Add blocks until all other tasks have completed, then the task
+// executes exclusively (blocking all other calls to Add until it completes).
+//
+// f may run concurrently in a goroutine, but its output to the passed-in
+// reporter will be sequential relative to the other tasks in the sequencer.
+//
+// If f invokes a method on the reporter, execution of that method may block
+// until the previous task has finished. (To maximize concurrency, f should
+// avoid invoking the reporter until it has finished any parallelizable work.)
+//
+// If f returns a non-nil error, that error will be reported after f's output
+// (if any) and will cause a nonzero final exit code.
+func (s *sequencer) Add(weight int64, f func(*reporter) error) {
+	if weight < 0 || weight > s.maxWeight {
+		weight = s.maxWeight
+	}
+	if err := s.sem.Acquire(context.TODO(), weight); err != nil {
+		// Change the task from "execute f" to "report err".
+		weight = 0
+		f = func(*reporter) error { return err }
+	}
+
+	r := &reporter{prev: s.prev}
+	next := make(chan *reporterState, 1)
+	s.prev = next
+
+	// Start f in parallel: it can run until it invokes a method on r, at which
+	// point it will block until the previous task releases the output state.
+	go func() {
+		if err := f(r); err != nil {
+			r.Report(err)
+		}
+		next <- r.getState() // Release the next task.
+		s.sem.Release(weight)
+	}()
+}
+
+// AddReport prints an error to s after the output of any previously-added
+// tasks, causing the final exit code to be nonzero.
+func (s *sequencer) AddReport(err error) {
+	s.Add(0, func(*reporter) error { return err })
+}
+
+// GetExitCode waits for all previously-added tasks to complete, then returns an
+// exit code for the sequence suitable for passing to os.Exit.
+func (s *sequencer) GetExitCode() int {
+	c := make(chan int, 1)
+	s.Add(0, func(r *reporter) error {
+		c <- r.ExitCode()
+		return nil
+	})
+	return <-c
+}
+
+// A reporter reports output, warnings, and errors.
+type reporter struct {
+	prev  <-chan *reporterState
+	state *reporterState
+}
+
+// reporterState carries the state of a reporter instance.
+//
+// Only one reporter at a time may have access to a reporterState.
+type reporterState struct {
+	out, err io.Writer
+	exitCode int
+}
+
+// getState blocks until any prior reporters are finished with the reporter
+// state, then returns the state for manipulation.
+func (r *reporter) getState() *reporterState {
+	if r.state == nil {
+		r.state = <-r.prev
+	}
+	return r.state
+}
+
+// Warnf emits a warning message to the reporter's error stream,
+// without changing its exit code.
+func (r *reporter) Warnf(format string, args ...any) {
+	fmt.Fprintf(r.getState().err, format, args...)
+}
+
+// Write emits a slice to the reporter's output stream.
+//
+// Any error is returned to the caller, and does not otherwise affect the
+// reporter's exit code.
+func (r *reporter) Write(p []byte) (int, error) {
+	return r.getState().out.Write(p)
+}
+
+// Report emits a non-nil error to the reporter's error stream,
+// changing its exit code to a nonzero value.
+func (r *reporter) Report(err error) {
+	if err == nil {
+		panic("Report with nil error")
+	}
+	st := r.getState()
+	scanner.PrintError(st.err, err)
+	st.exitCode = 2
+}
+
+func (r *reporter) ExitCode() int {
+	return r.getState().exitCode
+}
+
+// If info == nil, we are formatting stdin instead of a file.
+// If in == nil, the source is the contents of the file with the given filename.
+func processFile(filename string, info fs.FileInfo, in io.Reader, r *reporter) error {
+	src, err := readFile(filename, info, in)
+	if err != nil {
+		return err
+	}
+
+	fileSet := token.NewFileSet()
+	// If we are formatting stdin, we accept a program fragment in lieu of a
+	// complete source file.
+	fragmentOk := info == nil
+	file, sourceAdj, indentAdj, err := parse(fileSet, filename, src, fragmentOk)
+	if err != nil {
+		return err
+	}
+
+	if rewrite != nil {
+		if sourceAdj == nil {
+			file = rewrite(fileSet, file)
+		} else {
+			r.Warnf("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(r, filename)
+		}
+		if *write {
+			if info == nil {
+				panic("-w should not have been allowed with stdin")
+			}
+
+			perm := info.Mode().Perm()
+			if err := writeFile(filename, src, res, perm, info.Size()); err != nil {
+				return err
+			}
+		}
+		if *doDiff {
+			newName := filepath.ToSlash(filename)
+			oldName := newName + ".orig"
+			r.Write(diff.Diff(oldName, src, newName, res))
+		}
+	}
+
+	if !*list && !*write && !*doDiff {
+		_, err = r.Write(res)
+	}
+
+	return err
+}
+
+// readFile reads the contents of filename, described by info.
+// If in is non-nil, readFile reads directly from it.
+// Otherwise, readFile opens and reads the file itself,
+// with the number of concurrently-open files limited by fdSem.
+func readFile(filename string, info fs.FileInfo, in io.Reader) ([]byte, error) {
+	if in == nil {
+		fdSem <- true
+		var err error
+		f, err := os.Open(filename)
+		if err != nil {
+			return nil, err
+		}
+		in = f
+		defer func() {
+			f.Close()
+			<-fdSem
+		}()
+	}
+
+	// Compute the file's size and read its contents with minimal allocations.
+	//
+	// If we have the FileInfo from filepath.WalkDir, use it to make
+	// a buffer of the right size and avoid ReadAll's reallocations.
+	//
+	// If the size is unknown (or bogus, or overflows an int), fall back to
+	// a size-independent ReadAll.
+	size := -1
+	if info != nil && info.Mode().IsRegular() && int64(int(info.Size())) == info.Size() {
+		size = int(info.Size())
+	}
+	if size+1 <= 0 {
+		// The file is not known to be regular, so we don't have a reliable size for it.
+		var err error
+		src, err := io.ReadAll(in)
+		if err != nil {
+			return nil, err
+		}
+		return src, nil
+	}
+
+	// We try to read size+1 bytes so that we can detect modifications: if we
+	// read more than size bytes, then the file was modified concurrently.
+	// (If that happens, we could, say, append to src to finish the read, or
+	// proceed with a truncated buffer — but the fact that it changed at all
+	// indicates a possible race with someone editing the file, so we prefer to
+	// stop to avoid corrupting it.)
+	src := make([]byte, size+1)
+	n, err := io.ReadFull(in, src)
+	switch err {
+	case nil, io.EOF, io.ErrUnexpectedEOF:
+		// io.ReadFull returns io.EOF (for an empty file) or io.ErrUnexpectedEOF
+		// (for a non-empty file) if the file was changed unexpectedly. Continue
+		// with comparing file sizes in those cases.
+	default:
+		return nil, err
+	}
+	if n < size {
+		return nil, fmt.Errorf("error: size of %s changed during reading (from %d to %d bytes)", filename, size, n)
+	} else if n > size {
+		return nil, fmt.Errorf("error: size of %s changed during reading (from %d to >=%d bytes)", filename, size, len(src))
+	}
+	return src[:n], nil
+}
+
+func main() {
+	// Arbitrarily limit in-flight work to 2MiB times the number of threads.
+	//
+	// The actual overhead for the parse tree and output will depend on the
+	// specifics of the file, but this at least keeps the footprint of the process
+	// roughly proportional to GOMAXPROCS.
+	maxWeight := (2 << 20) * int64(runtime.GOMAXPROCS(0))
+	s := newSequencer(maxWeight, os.Stdout, os.Stderr)
+
+	// call gofmtMain in a separate function
+	// so that it can use defer and have them
+	// run before the exit.
+	gofmtMain(s)
+	os.Exit(s.GetExitCode())
+}
+
+func gofmtMain(s *sequencer) {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *cpuprofile != "" {
+		fdSem <- true
+		f, err := os.Create(*cpuprofile)
+		if err != nil {
+			s.AddReport(fmt.Errorf("creating cpu profile: %s", err))
+			return
+		}
+		defer func() {
+			f.Close()
+			<-fdSem
+		}()
+		pprof.StartCPUProfile(f)
+		defer pprof.StopCPUProfile()
+	}
+
+	initParserMode()
+	initRewrite()
+
+	args := flag.Args()
+	if len(args) == 0 {
+		if *write {
+			s.AddReport(fmt.Errorf("error: cannot use -w with standard input"))
+			return
+		}
+		s.Add(0, func(r *reporter) error {
+			return processFile("<standard input>", nil, os.Stdin, r)
+		})
+		return
+	}
+
+	for _, arg := range args {
+		switch info, err := os.Stat(arg); {
+		case err != nil:
+			s.AddReport(err)
+		case !info.IsDir():
+			// Non-directory arguments are always formatted.
+			arg := arg
+			s.Add(fileWeight(arg, info), func(r *reporter) error {
+				return processFile(arg, info, nil, r)
+			})
+		default:
+			// Directories are walked, ignoring non-Go files.
+			err := filepath.WalkDir(arg, func(path string, f fs.DirEntry, err error) error {
+				if err != nil || !isGoFile(f) {
+					return err
+				}
+				info, err := f.Info()
+				if err != nil {
+					s.AddReport(err)
+					return nil
+				}
+				s.Add(fileWeight(path, info), func(r *reporter) error {
+					return processFile(path, info, nil, r)
+				})
+				return nil
+			})
+			if err != nil {
+				s.AddReport(err)
+			}
+		}
+	}
+}
+
+func fileWeight(path string, info fs.FileInfo) int64 {
+	if info == nil {
+		return exclusive
+	}
+	if info.Mode().Type() == fs.ModeSymlink {
+		var err error
+		info, err = os.Stat(path)
+		if err != nil {
+			return exclusive
+		}
+	}
+	if !info.Mode().IsRegular() {
+		// For non-regular files, FileInfo.Size is system-dependent and thus not a
+		// reliable indicator of weight.
+		return exclusive
+	}
+	return info.Size()
+}
+
+// writeFile updates a file with the new formatted data.
+func writeFile(filename string, orig, formatted []byte, perm fs.FileMode, size int64) error {
+	// Make a temporary backup file before rewriting the original file.
+	bakname, err := backupFile(filename, orig, perm)
+	if err != nil {
+		return err
+	}
+
+	fdSem <- true
+	defer func() { <-fdSem }()
+
+	fout, err := os.OpenFile(filename, os.O_WRONLY, perm)
+	if err != nil {
+		// We couldn't even open the file, so it should
+		// not have changed.
+		os.Remove(bakname)
+		return err
+	}
+	defer fout.Close() // for error paths
+
+	restoreFail := func(err error) {
+		fmt.Fprintf(os.Stderr, "gofmt: %s: error restoring file to original: %v; backup in %s\n", filename, err, bakname)
+	}
+
+	n, err := fout.Write(formatted)
+	if err == nil && int64(n) < size {
+		err = fout.Truncate(int64(n))
+	}
+
+	if err != nil {
+		// Rewriting the file failed.
+
+		if n == 0 {
+			// Original file unchanged.
+			os.Remove(bakname)
+			return err
+		}
+
+		// Try to restore the original contents.
+
+		no, erro := fout.WriteAt(orig, 0)
+		if erro != nil {
+			// That failed too.
+			restoreFail(erro)
+			return err
+		}
+
+		if no < n {
+			// Original file is shorter. Truncate.
+			if erro = fout.Truncate(int64(no)); erro != nil {
+				restoreFail(erro)
+				return err
+			}
+		}
+
+		if erro := fout.Close(); erro != nil {
+			restoreFail(erro)
+			return err
+		}
+
+		// Original contents restored.
+		os.Remove(bakname)
+		return err
+	}
+
+	if err := fout.Close(); err != nil {
+		restoreFail(err)
+		return err
+	}
+
+	// File updated.
+	os.Remove(bakname)
+	return nil
+}
+
+// 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) {
+	fdSem <- true
+	defer func() { <-fdSem }()
+
+	nextRandom := func() string {
+		return strconv.Itoa(rand.Int())
+	}
+
+	dir, base := filepath.Split(filename)
+	var (
+		bakname string
+		f       *os.File
+	)
+	for {
+		bakname = filepath.Join(dir, base+"."+nextRandom())
+		var err error
+		f, err = os.OpenFile(bakname, os.O_RDWR|os.O_CREATE|os.O_EXCL, perm)
+		if err == nil {
+			break
+		}
+		if err != nil && !os.IsExist(err) {
+			return "", err
+		}
+	}
+
+	// write data to backup file
+	_, err := f.Write(data)
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+
+	return bakname, err
+}