os: new FileInfo, FileMode types + update tree

R=golang-dev, r, r, gri, bradfitz, iant, iant, nigeltao, n13m3y3r
CC=golang-dev
https://golang.org/cl/5416060

50 files changed, 620 insertions, 525 deletions

diff --git a/misc/dashboard/builder/main.go b/misc/dashboard/builder/main.go
index baffc807dc..101b77ed76 100644
--- a/misc/dashboard/builder/main.go
+++ b/misc/dashboard/builder/main.go
@@ -410,12 +410,12 @@ func (b *Builder) envvWindows() []string {
 
 func isDirectory(name string) bool {
 	s, err := os.Stat(name)
-	return err == nil && s.IsDirectory()
+	return err == nil && s.IsDir()
 }
 
 func isFile(name string) bool {
 	s, err := os.Stat(name)
-	return err == nil && (s.IsRegular() || s.IsSymlink())
+	return err == nil && !s.IsDir()
 }
 
 // commitWatcher polls hg for new commits and tells the dashboard about them.
diff --git a/misc/dashboard/builder/package.go b/misc/dashboard/builder/package.go
index 565fec614e..c7708472c2 100644
--- a/misc/dashboard/builder/package.go
+++ b/misc/dashboard/builder/package.go
@@ -81,11 +81,11 @@ func (b *Builder) buildPackages(workpath string, hash string) error {
 	return nil
 }
 
-func isGoFile(fi *os.FileInfo) bool {
-	return fi.IsRegular() && // exclude directories
-		!strings.HasPrefix(fi.Name, ".") && // ignore .files
-		!strings.HasSuffix(fi.Name, "_test.go") && // ignore tests
-		filepath.Ext(fi.Name) == ".go"
+func isGoFile(fi os.FileInfo) bool {
+	return !fi.IsDir() && // exclude directories
+		!strings.HasPrefix(fi.Name(), ".") && // ignore .files
+		!strings.HasSuffix(fi.Name(), "_test.go") && // ignore tests
+		filepath.Ext(fi.Name()) == ".go"
 }
 
 func packageComment(pkg, pkgpath string) (info string, err error) {
diff --git a/src/cmd/godoc/codewalk.go b/src/cmd/godoc/codewalk.go
index 0162dc55d7..7eaad2f94c 100644
--- a/src/cmd/godoc/codewalk.go
+++ b/src/cmd/godoc/codewalk.go
@@ -41,7 +41,7 @@ func codewalk(w http.ResponseWriter, r *http.Request) {
 
 	// If directory exists, serve list of code walks.
 	dir, err := fs.Lstat(abspath)
-	if err == nil && dir.IsDirectory() {
+	if err == nil && dir.IsDir() {
 		codewalkDir(w, r, relpath, abspath)
 		return
 	}
@@ -186,7 +186,7 @@ func codewalkDir(w http.ResponseWriter, r *http.Request, relpath, abspath string
 	var v []interface{}
 	for _, fi := range dir {
 		name := fi.Name()
-		if fi.IsDirectory() {
+		if fi.IsDir() {
 			v = append(v, &elem{name + "/", ""})
 		} else if strings.HasSuffix(name, ".xml") {
 			cw, err := loadCodewalk(abspath + "/" + name)
diff --git a/src/cmd/godoc/dirtrees.go b/src/cmd/godoc/dirtrees.go
index 7a9abdd83a..7f06348938 100644
--- a/src/cmd/godoc/dirtrees.go
+++ b/src/cmd/godoc/dirtrees.go
@@ -12,6 +12,7 @@ import (
 	"go/parser"
 	"go/token"
 	"log"
+	"os"
 	"path/filepath"
 	"strings"
 	"unicode"
@@ -25,21 +26,21 @@ type Directory struct {
 	Dirs  []*Directory // subdirectories
 }
 
-func isGoFile(fi FileInfo) bool {
+func isGoFile(fi os.FileInfo) bool {
 	name := fi.Name()
-	return fi.IsRegular() &&
+	return !fi.IsDir() &&
 		len(name) > 0 && name[0] != '.' && // ignore .files
 		filepath.Ext(name) == ".go"
 }
 
-func isPkgFile(fi FileInfo) bool {
+func isPkgFile(fi os.FileInfo) bool {
 	return isGoFile(fi) &&
 		!strings.HasSuffix(fi.Name(), "_test.go") // ignore test files
 }
 
-func isPkgDir(fi FileInfo) bool {
+func isPkgDir(fi os.FileInfo) bool {
 	name := fi.Name()
-	return fi.IsDirectory() && len(name) > 0 &&
+	return fi.IsDir() && len(name) > 0 &&
 		name[0] != '_' && name[0] != '.' // ignore _files and .files
 }
 
diff --git a/src/cmd/godoc/filesystem.go b/src/cmd/godoc/filesystem.go
index aa79b3693f..4e48c9e683 100644
--- a/src/cmd/godoc/filesystem.go
+++ b/src/cmd/godoc/filesystem.go
@@ -13,25 +13,15 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
-	"time"
 )
 
-// The FileInfo interface provides access to file information.
-type FileInfo interface {
-	Name() string
-	Size() int64
-	ModTime() time.Time
-	IsRegular() bool
-	IsDirectory() bool
-}
-
 // The FileSystem interface specifies the methods godoc is using
 // to access the file system for which it serves documentation.
 type FileSystem interface {
 	Open(path string) (io.ReadCloser, error)
-	Lstat(path string) (FileInfo, error)
-	Stat(path string) (FileInfo, error)
-	ReadDir(path string) ([]FileInfo, error)
+	Lstat(path string) (os.FileInfo, error)
+	Stat(path string) (os.FileInfo, error)
+	ReadDir(path string) ([]os.FileInfo, error)
 }
 
 // ReadFile reads the file named by path from fs and returns the contents.
@@ -49,26 +39,6 @@ func ReadFile(fs FileSystem, path string) ([]byte, error) {
 
 var OS FileSystem = osFS{}
 
-// osFI is the OS-specific implementation of FileInfo.
-type osFI struct {
-	*os.FileInfo
-}
-
-func (fi osFI) Name() string {
-	return fi.FileInfo.Name
-}
-
-func (fi osFI) Size() int64 {
-	if fi.IsDirectory() {
-		return 0
-	}
-	return fi.FileInfo.Size
-}
-
-func (fi osFI) ModTime() time.Time {
-	return fi.FileInfo.ModTime
-}
-
 // osFS is the OS-specific implementation of FileSystem
 type osFS struct{}
 
@@ -81,30 +51,20 @@ func (osFS) Open(path string) (io.ReadCloser, error) {
 	if err != nil {
 		return nil, err
 	}
-	if fi.IsDirectory() {
+	if fi.IsDir() {
 		return nil, fmt.Errorf("Open: %s is a directory", path)
 	}
 	return f, nil
 }
 
-func (osFS) Lstat(path string) (FileInfo, error) {
-	fi, err := os.Lstat(path)
-	return osFI{fi}, err
+func (osFS) Lstat(path string) (os.FileInfo, error) {
+	return os.Lstat(path)
 }
 
-func (osFS) Stat(path string) (FileInfo, error) {
-	fi, err := os.Stat(path)
-	return osFI{fi}, err
+func (osFS) Stat(path string) (os.FileInfo, error) {
+	return os.Stat(path)
 }
 
-func (osFS) ReadDir(path string) ([]FileInfo, error) {
-	l0, err := ioutil.ReadDir(path) // l0 is sorted
-	if err != nil {
-		return nil, err
-	}
-	l1 := make([]FileInfo, len(l0))
-	for i, e := range l0 {
-		l1[i] = osFI{e}
-	}
-	return l1, nil
+func (osFS) ReadDir(path string) ([]os.FileInfo, error) {
+	return ioutil.ReadDir(path) // is sorted
 }
diff --git a/src/cmd/godoc/godoc.go b/src/cmd/godoc/godoc.go
index e3413544a9..1ce4c9679a 100644
--- a/src/cmd/godoc/godoc.go
+++ b/src/cmd/godoc/godoc.go
@@ -381,15 +381,15 @@ func filenameFunc(path string) string {
 	return localname
 }
 
-func fileInfoNameFunc(fi FileInfo) string {
+func fileInfoNameFunc(fi os.FileInfo) string {
 	name := fi.Name()
-	if fi.IsDirectory() {
+	if fi.IsDir() {
 		name += "/"
 	}
 	return name
 }
 
-func fileInfoTimeFunc(fi FileInfo) string {
+func fileInfoTimeFunc(fi os.FileInfo) string {
 	if t := fi.ModTime(); t.Unix() != 0 {
 		return t.Local().String()
 	}
@@ -789,7 +789,7 @@ func serveFile(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if dir != nil && dir.IsDirectory() {
+	if dir != nil && dir.IsDir() {
 		if redirect(w, r) {
 			return
 		}
@@ -894,22 +894,8 @@ type httpHandler struct {
 }
 
 // fsReadDir implements ReadDir for the go/build package.
-func fsReadDir(dir string) ([]*os.FileInfo, error) {
-	fi, err := fs.ReadDir(dir)
-	if err != nil {
-		return nil, err
-	}
-
-	// Convert []FileInfo to []*os.FileInfo.
-	osfi := make([]*os.FileInfo, len(fi))
-	for i, f := range fi {
-		mode := uint32(S_IFREG)
-		if f.IsDirectory() {
-			mode = S_IFDIR
-		}
-		osfi[i] = &os.FileInfo{Name: f.Name(), Size: f.Size(), ModTime: f.ModTime(), Mode: mode}
-	}
-	return osfi, nil
+func fsReadDir(dir string) ([]os.FileInfo, error) {
+	return fs.ReadDir(dir)
 }
 
 // fsReadFile implements ReadFile for the go/build package.
@@ -969,7 +955,7 @@ func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInf
 	}
 
 	// filter function to select the desired .go files
-	filter := func(d FileInfo) bool {
+	filter := func(d os.FileInfo) bool {
 		// Only Go files.
 		if !isPkgFile(d) {
 			return false
@@ -1048,7 +1034,7 @@ func (h *httpHandler) getPageInfo(abspath, relpath, pkgname string, mode PageInf
 
 	// get examples from *_test.go files
 	var examples []*doc.Example
-	filter = func(d FileInfo) bool {
+	filter = func(d os.FileInfo) bool {
 		return isGoFile(d) && strings.HasSuffix(d.Name(), "_test.go")
 	}
 	if testpkgs, err := parseDir(fset, abspath, filter); err != nil {
diff --git a/src/cmd/godoc/httpzip.go b/src/cmd/godoc/httpzip.go
index 88b2e8f423..198a348cbf 100644
--- a/src/cmd/godoc/httpzip.go
+++ b/src/cmd/godoc/httpzip.go
@@ -35,13 +35,18 @@ import (
 	"time"
 )
 
-// We cannot import syscall on app engine.
-// TODO(gri) Once we have a truly abstract FileInfo implementation
-//           this won't be needed anymore.
-const (
-	S_IFDIR = 0x4000 // == syscall.S_IFDIR
-	S_IFREG = 0x8000 // == syscall.S_IFREG
-)
+type fileInfo struct {
+	name  string
+	mode  os.FileMode
+	size  int64
+	mtime time.Time
+}
+
+func (fi *fileInfo) Name() string       { return fi.name }
+func (fi *fileInfo) Mode() os.FileMode  { return fi.mode }
+func (fi *fileInfo) Size() int64        { return fi.size }
+func (fi *fileInfo) ModTime() time.Time { return fi.mtime }
+func (fi *fileInfo) IsDir() bool        { return fi.mode.IsDir() }
 
 // httpZipFile is the zip-file based implementation of http.File
 type httpZipFile struct {
@@ -52,15 +57,15 @@ type httpZipFile struct {
 }
 
 func (f *httpZipFile) Close() error {
-	if f.info.IsRegular() {
+	if !f.info.IsDir() {
 		return f.ReadCloser.Close()
 	}
 	f.list = nil
 	return nil
 }
 
-func (f *httpZipFile) Stat() (*os.FileInfo, error) {
-	return &f.info, nil
+func (f *httpZipFile) Stat() (os.FileInfo, error) {
+	return f.info, nil
 }
 
 func (f *httpZipFile) Readdir(count int) ([]os.FileInfo, error) {
@@ -77,17 +82,17 @@ func (f *httpZipFile) Readdir(count int) ([]os.FileInfo, error) {
 			break // not in the same directory anymore
 		}
 		name := e.Name[len(dirname):] // local name
-		var mode uint32
+		var mode os.FileMode
 		var size int64
 		var mtime time.Time
 		if i := strings.IndexRune(name, '/'); i >= 0 {
 			// We infer directories from files in subdirectories.
 			// If we have x/y, return a directory entry for x.
 			name = name[0:i] // keep local directory name only
-			mode = S_IFDIR
+			mode = os.ModeDir
 			// no size or mtime for directories
 		} else {
-			mode = S_IFREG
+			mode = 0
 			size = int64(e.UncompressedSize)
 			mtime = e.ModTime()
 		}
@@ -96,11 +101,11 @@ func (f *httpZipFile) Readdir(count int) ([]os.FileInfo, error) {
 		// by determining the (fs.list) range of local directory entries
 		// (via two binary searches).
 		if name != prevname {
-			list = append(list, os.FileInfo{
-				Name:    name,
-				Mode:    mode,
-				Size:    size,
-				ModTime: mtime,
+			list = append(list, &fileInfo{
+				name,
+				mode,
+				size,
+				mtime,
 			})
 			prevname = name
 			count--
@@ -115,7 +120,7 @@ func (f *httpZipFile) Readdir(count int) ([]os.FileInfo, error) {
 }
 
 func (f *httpZipFile) Seek(offset int64, whence int) (int64, error) {
-	return 0, fmt.Errorf("Seek not implemented for zip file entry: %s", f.info.Name)
+	return 0, fmt.Errorf("Seek not implemented for zip file entry: %s", f.info.Name())
 }
 
 // httpZipFS is the zip-file based implementation of http.FileSystem
@@ -143,11 +148,11 @@ func (fs *httpZipFS) Open(name string) (http.File, error) {
 		}
 		return &httpZipFile{
 			path,
-			os.FileInfo{
-				Name:    name,
-				Mode:    S_IFREG,
-				Size:    int64(f.UncompressedSize),
-				ModTime: f.ModTime(),
+			&fileInfo{
+				name,
+				0,
+				int64(f.UncompressedSize),
+				f.ModTime(),
 			},
 			rc,
 			nil,
@@ -157,10 +162,11 @@ func (fs *httpZipFS) Open(name string) (http.File, error) {
 	// not an exact match - must be a directory
 	return &httpZipFile{
 		path,
-		os.FileInfo{
-			Name: name,
-			Mode: S_IFDIR,
-			// no size or mtime for directories
+		&fileInfo{
+			name,
+			os.ModeDir,
+			0,  // no size for directory
+			time.Time{},  // no mtime for directory
 		},
 		nil,
 		fs.list[index:],
diff --git a/src/cmd/godoc/index.go b/src/cmd/godoc/index.go
index 27dd4feec1..e07cc2b0db 100644
--- a/src/cmd/godoc/index.go
+++ b/src/cmd/godoc/index.go
@@ -48,6 +48,7 @@ import (
 	"go/token"
 	"index/suffixarray"
 	"io"
+	"os"
 	"path/filepath"
 	"regexp"
 	"sort"
@@ -701,8 +702,8 @@ func isWhitelisted(filename string) bool {
 	return whitelisted[key]
 }
 
-func (x *Indexer) visitFile(dirname string, f FileInfo, fulltextIndex bool) {
-	if !f.IsRegular() {
+func (x *Indexer) visitFile(dirname string, f os.FileInfo, fulltextIndex bool) {
+	if f.IsDir() {
 		return
 	}
 
@@ -781,7 +782,7 @@ func NewIndex(dirnames <-chan string, fulltextIndex bool, throttle float64) *Ind
 			continue // ignore this directory
 		}
 		for _, f := range list {
-			if !f.IsDirectory() {
+			if !f.IsDir() {
 				x.visitFile(dirname, f, fulltextIndex)
 			}
 			th.Throttle()
diff --git a/src/cmd/godoc/parser.go b/src/cmd/godoc/parser.go
index 7597a00e79..fa303e904e 100644
--- a/src/cmd/godoc/parser.go
+++ b/src/cmd/godoc/parser.go
@@ -13,6 +13,7 @@ import (
 	"go/ast"
 	"go/parser"
 	"go/token"
+	"os"
 	"path/filepath"
 )
 
@@ -47,7 +48,7 @@ func parseFiles(fset *token.FileSet, filenames []string) (pkgs map[string]*ast.P
 	return
 }
 
-func parseDir(fset *token.FileSet, path string, filter func(FileInfo) bool) (map[string]*ast.Package, error) {
+func parseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool) (map[string]*ast.Package, error) {
 	list, err := fs.ReadDir(path)
 	if err != nil {
 		return nil, err
diff --git a/src/cmd/godoc/zip.go b/src/cmd/godoc/zip.go
index 274999ba00..cd38ed92bc 100644
--- a/src/cmd/godoc/zip.go
+++ b/src/cmd/godoc/zip.go
@@ -22,6 +22,7 @@ import (
 	"archive/zip"
 	"fmt"
 	"io"
+	"os"
 	"path"
 	"sort"
 	"strings"
@@ -52,12 +53,16 @@ func (fi zipFI) ModTime() time.Time {
 	return time.Time{} // directory has no modified time entry
 }
 
-func (fi zipFI) IsDirectory() bool {
-	return fi.file == nil
+func (fi zipFI) Mode() os.FileMode {
+	if fi.file == nil {
+		// Unix directories typically are executable, hence 555.
+		return os.ModeDir | 0555
+	}
+	return 0444
 }
 
-func (fi zipFI) IsRegular() bool {
-	return fi.file != nil
+func (fi zipFI) IsDir() bool {
+	return fi.file == nil
 }
 
 // zipFS is the zip-file based implementation of FileSystem
@@ -98,33 +103,33 @@ func (fs *zipFS) Open(abspath string) (io.ReadCloser, error) {
 	if err != nil {
 		return nil, err
 	}
-	if fi.IsDirectory() {
+	if fi.IsDir() {
 		return nil, fmt.Errorf("Open: %s is a directory", abspath)
 	}
 	return fi.file.Open()
 }
 
-func (fs *zipFS) Lstat(abspath string) (FileInfo, error) {
+func (fs *zipFS) Lstat(abspath string) (os.FileInfo, error) {
 	_, fi, err := fs.stat(zipPath(abspath))
 	return fi, err
 }
 
-func (fs *zipFS) Stat(abspath string) (FileInfo, error) {
+func (fs *zipFS) Stat(abspath string) (os.FileInfo, error) {
 	_, fi, err := fs.stat(zipPath(abspath))
 	return fi, err
 }
 
-func (fs *zipFS) ReadDir(abspath string) ([]FileInfo, error) {
+func (fs *zipFS) ReadDir(abspath string) ([]os.FileInfo, error) {
 	path := zipPath(abspath)
 	i, fi, err := fs.stat(path)
 	if err != nil {
 		return nil, err
 	}
-	if !fi.IsDirectory() {
+	if !fi.IsDir() {
 		return nil, fmt.Errorf("ReadDir: %s is not a directory", abspath)
 	}
 
-	var list []FileInfo
+	var list []os.FileInfo
 	dirname := path + "/"
 	prevname := ""
 	for _, e := range fs.list[i:] {
diff --git a/src/cmd/gofix/main.go b/src/cmd/gofix/main.go
index c8096b3976..dfa756799a 100644
--- a/src/cmd/gofix/main.go
+++ b/src/cmd/gofix/main.go
@@ -82,12 +82,12 @@ func main() {
 		switch dir, err := os.Stat(path); {
 		case err != nil:
 			report(err)
-		case dir.IsRegular():
+		case dir.IsDir():
+			walkDir(path)
+		default:
 			if err := processFile(path, false); err != nil {
 				report(err)
 			}
-		case dir.IsDirectory():
-			walkDir(path)
 		}
 	}
 
@@ -219,7 +219,7 @@ func walkDir(path string) {
 	filepath.Walk(path, visitFile)
 }
 
-func visitFile(path string, f *os.FileInfo, err error) error {
+func visitFile(path string, f os.FileInfo, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, false)
 	}
@@ -229,9 +229,10 @@ func visitFile(path string, f *os.FileInfo, err error) error {
 	return nil
 }
 
-func isGoFile(f *os.FileInfo) bool {
+func isGoFile(f os.FileInfo) bool {
 	// ignore non-Go files
-	return f.IsRegular() && !strings.HasPrefix(f.Name, ".") && strings.HasSuffix(f.Name, ".go")
+	name := f.Name()
+	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
 }
 
 func diff(b1, b2 []byte) (data []byte, err error) {
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index 2c52250c2e..b9042271ab 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -80,9 +80,10 @@ func initPrinterMode() {
 	}
 }
 
-func isGoFile(f *os.FileInfo) bool {
+func isGoFile(f os.FileInfo) bool {
 	// ignore non-Go files
-	return f.IsRegular() && !strings.HasPrefix(f.Name, ".") && strings.HasSuffix(f.Name, ".go")
+	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.
@@ -158,7 +159,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 	return err
 }
 
-func visitFile(path string, f *os.FileInfo, err error) error {
+func visitFile(path string, f os.FileInfo, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, nil, os.Stdout, false)
 	}
@@ -217,12 +218,12 @@ func gofmtMain() {
 		switch dir, err := os.Stat(path); {
 		case err != nil:
 			report(err)
-		case dir.IsRegular():
+		case dir.IsDir():
+			walkDir(path)
+		default:
 			if err := processFile(path, nil, os.Stdout, false); err != nil {
 				report(err)
 			}
-		case dir.IsDirectory():
-			walkDir(path)
 		}
 	}
 }
diff --git a/src/cmd/goinstall/download.go b/src/cmd/goinstall/download.go
index 0954439e38..13f7f2b251 100644
--- a/src/cmd/goinstall/download.go
+++ b/src/cmd/goinstall/download.go
@@ -525,5 +525,5 @@ func selectTag(goVersion string, tags []string) (match string) {
 
 func isDir(dir string) bool {
 	fi, err := os.Stat(dir)
-	return err == nil && fi.IsDirectory()
+	return err == nil && fi.IsDir()
 }
diff --git a/src/cmd/govet/govet.go b/src/cmd/govet/govet.go
index ae00e49a64..fccf08ffcf 100644
--- a/src/cmd/govet/govet.go
+++ b/src/cmd/govet/govet.go
@@ -82,7 +82,7 @@ func main() {
 	} else {
 		for _, name := range flag.Args() {
 			// Is it a directory?
-			if fi, err := os.Stat(name); err == nil && fi.IsDirectory() {
+			if fi, err := os.Stat(name); err == nil && fi.IsDir() {
 				walkDir(name)
 			} else {
 				doFile(name, nil)
@@ -105,12 +105,12 @@ func doFile(name string, reader io.Reader) {
 	file.checkFile(name, parsedFile)
 }
 
-func visit(path string, f *os.FileInfo, err error) error {
+func visit(path string, f os.FileInfo, err error) error {
 	if err != nil {
 		errorf("walk error: %s", err)
 		return nil
 	}
-	if f.IsRegular() && strings.HasSuffix(path, ".go") {
+	if !f.IsDir() && strings.HasSuffix(path, ".go") {
 		doFile(path, nil)
 	}
 	return nil
diff --git a/src/cmd/hgpatch/main.go b/src/cmd/hgpatch/main.go
index edde6cba08..05dc61eb95 100644
--- a/src/cmd/hgpatch/main.go
+++ b/src/cmd/hgpatch/main.go
@@ -192,7 +192,7 @@ func makeParent(name string) {
 func mkdirAll(path string, perm uint32) error {
 	dir, err := os.Lstat(path)
 	if err == nil {
-		if dir.IsDirectory() {
+		if dir.IsDir() {
 			return nil
 		}
 		return &os.PathError{"mkdir", path, os.ENOTDIR}
@@ -220,7 +220,7 @@ func mkdirAll(path string, perm uint32) error {
 		// Handle arguments like "foo/." by
 		// double-checking that directory doesn't exist.
 		dir, err1 := os.Lstat(path)
-		if err1 == nil && dir.IsDirectory() {
+		if err1 == nil && dir.IsDir() {
 			return nil
 		}
 		return err
diff --git a/src/pkg/archive/zip/reader.go b/src/pkg/archive/zip/reader.go
index cfbe5498a1..4365009a30 100644
--- a/src/pkg/archive/zip/reader.go
+++ b/src/pkg/archive/zip/reader.go
@@ -56,7 +56,7 @@ func OpenReader(name string) (*ReadCloser, error) {
 		return nil, err
 	}
 	r := new(ReadCloser)
-	if err := r.init(f, fi.Size); err != nil {
+	if err := r.init(f, fi.Size()); err != nil {
 		f.Close()
 		return nil, err
 	}
diff --git a/src/pkg/exp/gotype/gotype.go b/src/pkg/exp/gotype/gotype.go
index bc4a112c98..a2a9361866 100644
--- a/src/pkg/exp/gotype/gotype.go
+++ b/src/pkg/exp/gotype/gotype.go
@@ -150,15 +150,15 @@ func processFiles(filenames []string, allFiles bool) {
 		switch info, err := os.Stat(filename); {
 		case err != nil:
 			report(err)
-		case info.IsRegular():
-			if allFiles || isGoFilename(info.Name) {
-				filenames[i] = filename
-				i++
-			}
-		case info.IsDirectory():
+		case info.IsDir():
 			if allFiles || *recursive {
 				processDirectory(filename)
 			}
+		default:
+			if allFiles || isGoFilename(info.Name()) {
+				filenames[i] = filename
+				i++
+			}
 		}
 	}
 	fset := token.NewFileSet()
diff --git a/src/pkg/exp/types/check_test.go b/src/pkg/exp/types/check_test.go
index 4a30acf231..35535ea406 100644
--- a/src/pkg/exp/types/check_test.go
+++ b/src/pkg/exp/types/check_test.go
@@ -202,7 +202,7 @@ func TestCheck(t *testing.T) {
 	// For easy debugging w/o changing the testing code,
 	// if there is a local test file, only test that file.
 	const testfile = "test.go"
-	if fi, err := os.Stat(testfile); err == nil && fi.IsRegular() {
+	if fi, err := os.Stat(testfile); err == nil && !fi.IsDir() {
 		fmt.Printf("WARNING: Testing only %s (remove it to run all tests)\n", testfile)
 		check(t, testfile, []string{testfile})
 		return
diff --git a/src/pkg/exp/types/gcimporter.go b/src/pkg/exp/types/gcimporter.go
index 4167caf3f0..16a8667ff6 100644
--- a/src/pkg/exp/types/gcimporter.go
+++ b/src/pkg/exp/types/gcimporter.go
@@ -59,7 +59,7 @@ func findPkg(path string) (filename, id string) {
 	// try extensions
 	for _, ext := range pkgExts {
 		filename = noext + ext
-		if f, err := os.Stat(filename); err == nil && f.IsRegular() {
+		if f, err := os.Stat(filename); err == nil && !f.IsDir() {
 			return
 		}
 	}
diff --git a/src/pkg/exp/types/gcimporter_test.go b/src/pkg/exp/types/gcimporter_test.go
index adac072f85..7475d35220 100644
--- a/src/pkg/exp/types/gcimporter_test.go
+++ b/src/pkg/exp/types/gcimporter_test.go
@@ -72,18 +72,18 @@ func testDir(t *testing.T, dir string, endTime time.Time) (nimports int) {
 			return
 		}
 		switch {
-		case f.IsRegular():
+		case !f.IsDir():
 			// try extensions
 			for _, ext := range pkgExts {
-				if strings.HasSuffix(f.Name, ext) {
-					name := f.Name[0 : len(f.Name)-len(ext)] // remove extension
+				if strings.HasSuffix(f.Name(), ext) {
+					name := f.Name()[0 : len(f.Name())-len(ext)] // remove extension
 					if testPath(t, filepath.Join(dir, name)) {
 						nimports++
 					}
 				}
 			}
-		case f.IsDirectory():
-			nimports += testDir(t, filepath.Join(dir, f.Name), endTime)
+		case f.IsDir():
+			nimports += testDir(t, filepath.Join(dir, f.Name()), endTime)
 		}
 	}
 	return
diff --git a/src/pkg/go/build/build.go b/src/pkg/go/build/build.go
index 9b3ab02d1d..5301ab53e5 100644
--- a/src/pkg/go/build/build.go
+++ b/src/pkg/go/build/build.go
@@ -159,13 +159,13 @@ func (s *Script) Stale() bool {
 			// any error reading output files means stale
 			return true
 		}
-		if fi.ModTime.After(latest) {
-			latest = fi.ModTime
+		if mtime := fi.ModTime(); mtime.After(latest) {
+			latest = mtime
 		}
 	}
 	for _, file := range s.Input {
 		fi, err := os.Stat(file)
-		if err != nil || fi.ModTime.After(latest) {
+		if err != nil || fi.ModTime().After(latest) {
 			// any error reading input files means stale
 			// (attempt to rebuild to figure out why)
 			return true
diff --git a/src/pkg/go/build/dir.go b/src/pkg/go/build/dir.go
index 0d175c75de..12dc99942a 100644
--- a/src/pkg/go/build/dir.go
+++ b/src/pkg/go/build/dir.go
@@ -38,16 +38,16 @@ type Context struct {
 	// format of the strings dir and file: they can be
 	// slash-separated, backslash-separated, even URLs.
 
-	// ReadDir returns a slice of *os.FileInfo, sorted by Name,
+	// ReadDir returns a slice of os.FileInfo, sorted by Name,
 	// describing the content of the named directory.
 	// The dir argument is the argument to ScanDir.
 	// If ReadDir is nil, ScanDir uses io.ReadDir.
-	ReadDir func(dir string) (fi []*os.FileInfo, err error)
+	ReadDir func(dir string) (fi []os.FileInfo, err error)
 
 	// ReadFile returns the content of the file named file
 	// in the directory named dir.  The dir argument is the
 	// argument to ScanDir, and the file argument is the
-	// Name field from an *os.FileInfo returned by ReadDir.
+	// Name field from an os.FileInfo returned by ReadDir.
 	// The returned path is the full name of the file, to be
 	// used in error messages.
 	//
@@ -56,7 +56,7 @@ type Context struct {
 	ReadFile func(dir, file string) (path string, content []byte, err error)
 }
 
-func (ctxt *Context) readDir(dir string) ([]*os.FileInfo, error) {
+func (ctxt *Context) readDir(dir string) ([]os.FileInfo, error) {
 	if f := ctxt.ReadDir; f != nil {
 		return f(dir)
 	}
@@ -140,18 +140,19 @@ func (ctxt *Context) ScanDir(dir string) (info *DirInfo, err error) {
 	testImported := make(map[string]bool)
 	fset := token.NewFileSet()
 	for _, d := range dirs {
-		if !d.IsRegular() {
+		if d.IsDir() {
 			continue
 		}
-		if strings.HasPrefix(d.Name, "_") ||
-			strings.HasPrefix(d.Name, ".") {
+		name := d.Name()
+		if strings.HasPrefix(name, "_") ||
+			strings.HasPrefix(name, ".") {
 			continue
 		}
-		if !ctxt.goodOSArchFile(d.Name) {
+		if !ctxt.goodOSArchFile(name) {
 			continue
 		}
 
-		ext := path.Ext(d.Name)
+		ext := path.Ext(name)
 		switch ext {
 		case ".go", ".c", ".s":
 			// tentatively okay
@@ -161,7 +162,7 @@ func (ctxt *Context) ScanDir(dir string) (info *DirInfo, err error) {
 		}
 
 		// Look for +build comments to accept or reject the file.
-		filename, data, err := ctxt.readFile(dir, d.Name)
+		filename, data, err := ctxt.readFile(dir, name)
 		if err != nil {
 			return nil, err
 		}
@@ -172,10 +173,10 @@ func (ctxt *Context) ScanDir(dir string) (info *DirInfo, err error) {
 		// Going to save the file.  For non-Go files, can stop here.
 		switch ext {
 		case ".c":
-			di.CFiles = append(di.CFiles, d.Name)
+			di.CFiles = append(di.CFiles, name)
 			continue
 		case ".s":
-			di.SFiles = append(di.SFiles, d.Name)
+			di.SFiles = append(di.SFiles, name)
 			continue
 		}
 
@@ -192,7 +193,7 @@ func (ctxt *Context) ScanDir(dir string) (info *DirInfo, err error) {
 			continue
 		}
 
-		isTest := strings.HasSuffix(d.Name, "_test.go")
+		isTest := strings.HasSuffix(name, "_test.go")
 		if isTest && strings.HasSuffix(pkg, "_test") {
 			pkg = pkg[:len(pkg)-len("_test")]
 		}
@@ -255,15 +256,15 @@ func (ctxt *Context) ScanDir(dir string) (info *DirInfo, err error) {
 			}
 		}
 		if isCgo {
-			di.CgoFiles = append(di.CgoFiles, d.Name)
+			di.CgoFiles = append(di.CgoFiles, name)
 		} else if isTest {
 			if pkg == string(pf.Name.Name) {
-				di.TestGoFiles = append(di.TestGoFiles, d.Name)
+				di.TestGoFiles = append(di.TestGoFiles, name)
 			} else {
-				di.XTestGoFiles = append(di.XTestGoFiles, d.Name)
+				di.XTestGoFiles = append(di.XTestGoFiles, name)
 			}
 		} else {
-			di.GoFiles = append(di.GoFiles, d.Name)
+			di.GoFiles = append(di.GoFiles, name)
 		}
 	}
 	if di.Package == "" {
diff --git a/src/pkg/go/build/path.go b/src/pkg/go/build/path.go
index 7ccb12993b..91d6c430a9 100644
--- a/src/pkg/go/build/path.go
+++ b/src/pkg/go/build/path.go
@@ -70,7 +70,7 @@ func (t *Tree) HasSrc(pkg string) bool {
 	if err != nil {
 		return false
 	}
-	return fi.IsDirectory()
+	return fi.IsDir()
 }
 
 // HasPkg returns whether the given package's
@@ -80,7 +80,7 @@ func (t *Tree) HasPkg(pkg string) bool {
 	if err != nil {
 		return false
 	}
-	return fi.IsRegular()
+	return !fi.IsDir()
 	// TODO(adg): check object version is consistent
 }
 
diff --git a/src/pkg/go/parser/interface.go b/src/pkg/go/parser/interface.go
index d3bab31c5a..be11f461c3 100644
--- a/src/pkg/go/parser/interface.go
+++ b/src/pkg/go/parser/interface.go
@@ -188,7 +188,7 @@ func ParseFiles(fset *token.FileSet, filenames []string, mode uint) (pkgs map[st
 // returned. If a parse error occurred, a non-nil but incomplete map and the
 // error are returned.
 //
-func ParseDir(fset *token.FileSet, path string, filter func(*os.FileInfo) bool, mode uint) (map[string]*ast.Package, error) {
+func ParseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool, mode uint) (map[string]*ast.Package, error) {
 	fd, err := os.Open(path)
 	if err != nil {
 		return nil, err
@@ -202,10 +202,9 @@ func ParseDir(fset *token.FileSet, path string, filter func(*os.FileInfo) bool,
 
 	filenames := make([]string, len(list))
 	n := 0
-	for i := 0; i < len(list); i++ {
-		d := &list[i]
+	for _, d := range list {
 		if filter == nil || filter(d) {
-			filenames[n] = filepath.Join(path, d.Name)
+			filenames[n] = filepath.Join(path, d.Name())
 			n++
 		}
 	}
diff --git a/src/pkg/go/parser/parser_test.go b/src/pkg/go/parser/parser_test.go
index dee90fbcf4..f602db8896 100644
--- a/src/pkg/go/parser/parser_test.go
+++ b/src/pkg/go/parser/parser_test.go
@@ -113,7 +113,7 @@ func nameFilter(filename string) bool {
 	return true
 }
 
-func dirFilter(f *os.FileInfo) bool { return nameFilter(f.Name) }
+func dirFilter(f os.FileInfo) bool { return nameFilter(f.Name()) }
 
 func TestParse4(t *testing.T) {
 	path := "."
diff --git a/src/pkg/io/ioutil/ioutil.go b/src/pkg/io/ioutil/ioutil.go
index f6c8cd8a87..be7fa5f2bc 100644
--- a/src/pkg/io/ioutil/ioutil.go
+++ b/src/pkg/io/ioutil/ioutil.go
@@ -36,8 +36,8 @@ func ReadFile(filename string) ([]byte, error) {
 	// read, so let's try it but be prepared for the answer to be wrong.
 	fi, err := f.Stat()
 	var n int64
-	if err == nil && fi.Size < 2e9 { // Don't preallocate a huge buffer, just in case.
-		n = fi.Size
+	if size := fi.Size(); err == nil && size < 2e9 { // Don't preallocate a huge buffer, just in case.
+		n = size
 	}
 	// As initial capacity for readAll, use n + a little extra in case Size is zero,
 	// and to avoid another allocation after Read has filled the buffer.  The readAll
@@ -63,16 +63,16 @@ func WriteFile(filename string, data []byte, perm uint32) error {
 	return err
 }
 
-// A fileInfoList implements sort.Interface.
-type fileInfoList []*os.FileInfo
+// byName implements sort.Interface.
+type byName []os.FileInfo
 
-func (f fileInfoList) Len() int           { return len(f) }
-func (f fileInfoList) Less(i, j int) bool { return f[i].Name < f[j].Name }
-func (f fileInfoList) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
+func (f byName) Len() int           { return len(f) }
+func (f byName) Less(i, j int) bool { return f[i].Name() < f[j].Name() }
+func (f byName) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
 
 // ReadDir reads the directory named by dirname and returns
 // a list of sorted directory entries.
-func ReadDir(dirname string) ([]*os.FileInfo, error) {
+func ReadDir(dirname string) ([]os.FileInfo, error) {
 	f, err := os.Open(dirname)
 	if err != nil {
 		return nil, err
@@ -82,12 +82,8 @@ func ReadDir(dirname string) ([]*os.FileInfo, error) {
 	if err != nil {
 		return nil, err
 	}
-	fi := make(fileInfoList, len(list))
-	for i := range list {
-		fi[i] = &list[i]
-	}
-	sort.Sort(fi)
-	return fi, nil
+	sort.Sort(byName(list))
+	return list, nil
 }
 
 type nopCloser struct {
diff --git a/src/pkg/io/ioutil/ioutil_test.go b/src/pkg/io/ioutil/ioutil_test.go
index 55e4b2c2bc..89d6815ad5 100644
--- a/src/pkg/io/ioutil/ioutil_test.go
+++ b/src/pkg/io/ioutil/ioutil_test.go
@@ -15,8 +15,8 @@ func checkSize(t *testing.T, path string, size int64) {
 	if err != nil {
 		t.Fatalf("Stat %q (looking for size %d): %s", path, size, err)
 	}
-	if dir.Size != size {
-		t.Errorf("Stat %q: size %d want %d", path, dir.Size, size)
+	if dir.Size() != size {
+		t.Errorf("Stat %q: size %d want %d", path, dir.Size(), size)
 	}
 }
 
@@ -76,9 +76,9 @@ func TestReadDir(t *testing.T) {
 	foundTestDir := false
 	for _, dir := range list {
 		switch {
-		case dir.IsRegular() && dir.Name == "ioutil_test.go":
+		case !dir.IsDir() && dir.Name() == "ioutil_test.go":
 			foundTest = true
-		case dir.IsDirectory() && dir.Name == "_test":
+		case dir.IsDir() && dir.Name() == "_test":
 			foundTestDir = true
 		}
 	}
diff --git a/src/pkg/net/http/fs.go b/src/pkg/net/http/fs.go
index 7f22188653..70e7849f16 100644
--- a/src/pkg/net/http/fs.go
+++ b/src/pkg/net/http/fs.go
@@ -52,7 +52,7 @@ type FileSystem interface {
 // served by the FileServer implementation.
 type File interface {
 	Close() error
-	Stat() (*os.FileInfo, error)
+	Stat() (os.FileInfo, error)
 	Readdir(count int) ([]os.FileInfo, error)
 	Read([]byte) (int, error)
 	Seek(offset int64, whence int) (int64, error)
@@ -93,8 +93,8 @@ func dirList(w ResponseWriter, f File) {
 			break
 		}
 		for _, d := range dirs {
-			name := d.Name
-			if d.IsDirectory() {
+			name := d.Name()
+			if d.IsDir() {
 				name += "/"
 			}
 			// TODO htmlescape
@@ -135,7 +135,7 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 		// redirect to canonical path: / at end of directory url
 		// r.URL.Path always begins with /
 		url := r.URL.Path
-		if d.IsDirectory() {
+		if d.IsDir() {
 			if url[len(url)-1] != '/' {
 				localRedirect(w, r, path.Base(url)+"/")
 				return
@@ -148,14 +148,14 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 		}
 	}
 
-	if t, err := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); err == nil && !d.ModTime.After(t) {
+	if t, err := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); err == nil && !d.ModTime().After(t) {
 		w.WriteHeader(StatusNotModified)
 		return
 	}
-	w.Header().Set("Last-Modified", d.ModTime.UTC().Format(TimeFormat))
+	w.Header().Set("Last-Modified", d.ModTime().UTC().Format(TimeFormat))
 
 	// use contents of index.html for directory, if present
-	if d.IsDirectory() {
+	if d.IsDir() {
 		index := name + indexPage
 		ff, err := fs.Open(index)
 		if err == nil {
@@ -169,13 +169,13 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 		}
 	}
 
-	if d.IsDirectory() {
+	if d.IsDir() {
 		dirList(w, f)
 		return
 	}
 
 	// serve file
-	size := d.Size
+	size := d.Size()
 	code := StatusOK
 
 	// If Content-Type isn't set, use the file's extension to find it.
@@ -215,7 +215,7 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 		}
 		size = ra.length
 		code = StatusPartialContent
-		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
+		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size()))
 	}
 
 	w.Header().Set("Accept-Ranges", "bytes")
diff --git a/src/pkg/net/http/fs_test.go b/src/pkg/net/http/fs_test.go
index 6697189900..976ee75c7d 100644
--- a/src/pkg/net/http/fs_test.go
+++ b/src/pkg/net/http/fs_test.go
@@ -190,8 +190,8 @@ func TestDirJoin(t *testing.T) {
 		if err != nil {
 			t.Fatalf("stat of %s: %v", name, err)
 		}
-		if gfi.Ino != wfi.Ino {
-			t.Errorf("%s got different inode", name)
+		if !gfi.(*os.FileStat).SameFile(wfi.(*os.FileStat)) {
+			t.Errorf("%s got different file", name)
 		}
 	}
 	test(Dir("/etc/"), "/hosts")
diff --git a/src/pkg/os/dir_windows.go b/src/pkg/os/dir_windows.go
index ec06d24168..6f999c0b0d 100644
--- a/src/pkg/os/dir_windows.go
+++ b/src/pkg/os/dir_windows.go
@@ -8,7 +8,7 @@ func (file *File) Readdirnames(n int) (names []string, err error) {
 	fis, err := file.Readdir(n)
 	names = make([]string, len(fis))
 	for i, fi := range fis {
-		names[i] = fi.Name
+		names[i] = fi.Name()
 	}
 	return names, err
 }
diff --git a/src/pkg/os/exec/lp_unix.go b/src/pkg/os/exec/lp_unix.go
index d234641acc..9665ea8f41 100644
--- a/src/pkg/os/exec/lp_unix.go
+++ b/src/pkg/os/exec/lp_unix.go
@@ -20,7 +20,7 @@ func findExecutable(file string) error {
 	if err != nil {
 		return err
 	}
-	if d.IsRegular() && d.Permission()&0111 != 0 {
+	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
 		return nil
 	}
 	return os.EPERM
diff --git a/src/pkg/os/exec/lp_windows.go b/src/pkg/os/exec/lp_windows.go
index db326236ee..ef5bd92166 100644
--- a/src/pkg/os/exec/lp_windows.go
+++ b/src/pkg/os/exec/lp_windows.go
@@ -18,10 +18,10 @@ func chkStat(file string) error {
 	if err != nil {
 		return err
 	}
-	if d.IsRegular() {
-		return nil
+	if d.IsDir() {
+		return os.EPERM
 	}
-	return os.EPERM
+	return nil
 }
 
 func findExecutable(file string, exts []string) (string, error) {
diff --git a/src/pkg/os/export_test.go b/src/pkg/os/export_test.go
new file mode 100644
index 0000000000..29f051162a
--- /dev/null
+++ b/src/pkg/os/export_test.go
@@ -0,0 +1,10 @@
+// Copyright 2011 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 os
+
+// Export for testing.
+
+var TimespecToTime = timespecToTime
+var Atime = atime
diff --git a/src/pkg/os/file_unix.go b/src/pkg/os/file_unix.go
index f3e0d1f9be..6e08eb6134 100644
--- a/src/pkg/os/file_unix.go
+++ b/src/pkg/os/file_unix.go
@@ -99,50 +99,43 @@ func (file *file) close() error {
 
 // Stat returns the FileInfo structure describing file.
 // It returns the FileInfo and an error, if any.
-func (file *File) Stat() (fi *FileInfo, err error) {
+func (file *File) Stat() (fi FileInfo, err error) {
 	var stat syscall.Stat_t
-	e := syscall.Fstat(file.fd, &stat)
-	if e != nil {
-		return nil, &PathError{"stat", file.name, e}
+	err = syscall.Fstat(file.fd, &stat)
+	if err != nil {
+		return nil, &PathError{"stat", file.name, err}
 	}
-	return fileInfoFromStat(file.name, new(FileInfo), &stat, &stat), nil
+	return fileInfoFromStat(&stat, file.name), nil
 }
 
-// Stat returns a FileInfo structure describing the named file and an error, if any.
+// Stat returns a FileInfo describing the named file and an error, if any.
 // If name names a valid symbolic link, the returned FileInfo describes
 // the file pointed at by the link and has fi.FollowedSymlink set to true.
 // If name names an invalid symbolic link, the returned FileInfo describes
 // the link itself and has fi.FollowedSymlink set to false.
-func Stat(name string) (fi *FileInfo, err error) {
-	var lstat, stat syscall.Stat_t
-	e := syscall.Lstat(name, &lstat)
-	if e != nil {
-		return nil, &PathError{"stat", name, e}
-	}
-	statp := &lstat
-	if lstat.Mode&syscall.S_IFMT == syscall.S_IFLNK {
-		e := syscall.Stat(name, &stat)
-		if e == nil {
-			statp = &stat
-		}
+func Stat(name string) (fi FileInfo, err error) {
+	var stat syscall.Stat_t
+	err = syscall.Stat(name, &stat)
+	if err != nil {
+		return nil, &PathError{"stat", name, err}
 	}
-	return fileInfoFromStat(name, new(FileInfo), &lstat, statp), nil
+	return fileInfoFromStat(&stat, name), nil
 }
 
-// Lstat returns the FileInfo structure describing the named file and an
+// Lstat returns a FileInfo describing the named file and an
 // error, if any.  If the file is a symbolic link, the returned FileInfo
 // describes the symbolic link.  Lstat makes no attempt to follow the link.
-func Lstat(name string) (fi *FileInfo, err error) {
+func Lstat(name string) (fi FileInfo, err error) {
 	var stat syscall.Stat_t
-	e := syscall.Lstat(name, &stat)
-	if e != nil {
-		return nil, &PathError{"lstat", name, e}
+	err = syscall.Lstat(name, &stat)
+	if err != nil {
+		return nil, &PathError{"lstat", name, err}
 	}
-	return fileInfoFromStat(name, new(FileInfo), &stat, &stat), nil
+	return fileInfoFromStat(&stat, name), nil
 }
 
 // Readdir reads the contents of the directory associated with file and
-// returns an array of up to n FileInfo structures, as would be returned
+// returns an array of up to n FileInfo values, as would be returned
 // by Lstat, in directory order. Subsequent calls on the same file will yield
 // further FileInfos.
 //
@@ -166,13 +159,13 @@ func (file *File) Readdir(n int) (fi []FileInfo, err error) {
 	fi = make([]FileInfo, len(names))
 	for i, filename := range names {
 		fip, err := Lstat(dirname + filename)
-		if fip == nil || err != nil {
-			fi[i].Name = filename // rest is already zeroed out
+		if err == nil {
+			fi[i] = fip
 		} else {
-			fi[i] = *fip
+			fi[i] = &FileStat{name: filename}
 		}
 	}
-	return
+	return fi, err
 }
 
 // read reads up to len(b) bytes from the File.
diff --git a/src/pkg/os/file_windows.go b/src/pkg/os/file_windows.go
index 81fdbe3051..bdb5d1d29c 100644
--- a/src/pkg/os/file_windows.go
+++ b/src/pkg/os/file_windows.go
@@ -180,12 +180,12 @@ func (file *File) Readdir(n int) (fi []FileInfo, err error) {
 				}
 			}
 		}
-		var f FileInfo
-		setFileInfo(&f, string(syscall.UTF16ToString(d.FileName[0:])), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
 		file.dirinfo.needdata = true
-		if f.Name == "." || f.Name == ".." { // Useless names
+		name := string(syscall.UTF16ToString(d.FileName[0:]))
+		if name == "." || name == ".." { // Useless names
 			continue
 		}
+		f := toFileInfo(name, d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
 		n--
 		fi = append(fi, f)
 	}
diff --git a/src/pkg/os/getwd.go b/src/pkg/os/getwd.go
index d5f5ae6bed..a0d3c99a50 100644
--- a/src/pkg/os/getwd.go
+++ b/src/pkg/os/getwd.go
@@ -12,7 +12,7 @@ import (
 // current directory.  If the current directory can be
 // reached via multiple paths (due to symbolic links),
 // Getwd may return any one of them.
-func Getwd() (string, error) {
+func Getwd() (pwd string, err error) {
 	// If the operating system provides a Getwd call, use it.
 	if syscall.ImplementsGetwd {
 		s, e := syscall.Getwd()
@@ -27,10 +27,10 @@ func Getwd() (string, error) {
 
 	// Clumsy but widespread kludge:
 	// if $PWD is set and matches ".", use it.
-	pwd := Getenv("PWD")
+	pwd = Getenv("PWD")
 	if len(pwd) > 0 && pwd[0] == '/' {
 		d, err := Stat(pwd)
-		if err == nil && d.Dev == dot.Dev && d.Ino == dot.Ino {
+		if err == nil && dot.(*FileStat).SameFile(d.(*FileStat)) {
 			return pwd, nil
 		}
 	}
@@ -42,7 +42,7 @@ func Getwd() (string, error) {
 		// Can't stat root - no hope.
 		return "", err
 	}
-	if root.Dev == dot.Dev && root.Ino == dot.Ino {
+	if root.(*FileStat).SameFile(dot.(*FileStat)) {
 		return "/", nil
 	}
 
@@ -67,7 +67,7 @@ func Getwd() (string, error) {
 			}
 			for _, name := range names {
 				d, _ := Lstat(parent + "/" + name)
-				if d.Dev == dot.Dev && d.Ino == dot.Ino {
+				if d.(*FileStat).SameFile(dot.(*FileStat)) {
 					pwd = "/" + name + pwd
 					goto Found
 				}
@@ -82,7 +82,7 @@ func Getwd() (string, error) {
 			return "", err
 		}
 		fd.Close()
-		if pd.Dev == root.Dev && pd.Ino == root.Ino {
+		if pd.(*FileStat).SameFile(root.(*FileStat)) {
 			break
 		}
 		// Set up for next round.
diff --git a/src/pkg/os/os_test.go b/src/pkg/os/os_test.go
index 2439f03348..d107020449 100644
--- a/src/pkg/os/os_test.go
+++ b/src/pkg/os/os_test.go
@@ -122,12 +122,12 @@ func TestStat(t *testing.T) {
 	if err != nil {
 		t.Fatal("stat failed:", err)
 	}
-	if !equal(sfname, dir.Name) {
-		t.Error("name should be ", sfname, "; is", dir.Name)
+	if !equal(sfname, dir.Name()) {
+		t.Error("name should be ", sfname, "; is", dir.Name())
 	}
 	filesize := size(path, t)
-	if dir.Size != filesize {
-		t.Error("size should be", filesize, "; is", dir.Size)
+	if dir.Size() != filesize {
+		t.Error("size should be", filesize, "; is", dir.Size())
 	}
 }
 
@@ -142,12 +142,12 @@ func TestFstat(t *testing.T) {
 	if err2 != nil {
 		t.Fatal("fstat failed:", err2)
 	}
-	if !equal(sfname, dir.Name) {
-		t.Error("name should be ", sfname, "; is", dir.Name)
+	if !equal(sfname, dir.Name()) {
+		t.Error("name should be ", sfname, "; is", dir.Name())
 	}
 	filesize := size(path, t)
-	if dir.Size != filesize {
-		t.Error("size should be", filesize, "; is", dir.Size)
+	if dir.Size() != filesize {
+		t.Error("size should be", filesize, "; is", dir.Size())
 	}
 }
 
@@ -157,12 +157,12 @@ func TestLstat(t *testing.T) {
 	if err != nil {
 		t.Fatal("lstat failed:", err)
 	}
-	if !equal(sfname, dir.Name) {
-		t.Error("name should be ", sfname, "; is", dir.Name)
+	if !equal(sfname, dir.Name()) {
+		t.Error("name should be ", sfname, "; is", dir.Name())
 	}
 	filesize := size(path, t)
-	if dir.Size != filesize {
-		t.Error("size should be", filesize, "; is", dir.Size)
+	if dir.Size() != filesize {
+		t.Error("size should be", filesize, "; is", dir.Size())
 	}
 }
 
@@ -229,7 +229,7 @@ func testReaddir(dir string, contents []string, t *testing.T) {
 	for _, m := range contents {
 		found := false
 		for _, n := range s {
-			if equal(m, n.Name) {
+			if equal(m, n.Name()) {
 				if found {
 					t.Error("present twice:", m)
 				}
@@ -408,7 +408,7 @@ func TestHardLink(t *testing.T) {
 	if err != nil {
 		t.Fatalf("stat %q failed: %v", from, err)
 	}
-	if tostat.Dev != fromstat.Dev || tostat.Ino != fromstat.Ino {
+	if !tostat.(*FileStat).SameFile(fromstat.(*FileStat)) {
 		t.Errorf("link %q, %q did not create hard link", to, from)
 	}
 }
@@ -433,32 +433,32 @@ func TestSymLink(t *testing.T) {
 		t.Fatalf("symlink %q, %q failed: %v", to, from, err)
 	}
 	defer Remove(from)
-	tostat, err := Stat(to)
+	tostat, err := Lstat(to)
 	if err != nil {
 		t.Fatalf("stat %q failed: %v", to, err)
 	}
-	if tostat.FollowedSymlink {
-		t.Fatalf("stat %q claims to have followed a symlink", to)
+	if tostat.Mode()&ModeSymlink != 0 {
+		t.Fatalf("stat %q claims to have found a symlink", to)
 	}
 	fromstat, err := Stat(from)
 	if err != nil {
 		t.Fatalf("stat %q failed: %v", from, err)
 	}
-	if tostat.Dev != fromstat.Dev || tostat.Ino != fromstat.Ino {
+	if !tostat.(*FileStat).SameFile(fromstat.(*FileStat)) {
 		t.Errorf("symlink %q, %q did not create symlink", to, from)
 	}
 	fromstat, err = Lstat(from)
 	if err != nil {
 		t.Fatalf("lstat %q failed: %v", from, err)
 	}
-	if !fromstat.IsSymlink() {
+	if fromstat.Mode()&ModeSymlink == 0 {
 		t.Fatalf("symlink %q, %q did not create symlink", to, from)
 	}
 	fromstat, err = Stat(from)
 	if err != nil {
 		t.Fatalf("stat %q failed: %v", from, err)
 	}
-	if !fromstat.FollowedSymlink {
+	if fromstat.Mode()&ModeSymlink != 0 {
 		t.Fatalf("stat %q did not follow symlink", from)
 	}
 	s, err := Readlink(from)
@@ -566,13 +566,13 @@ func TestStartProcess(t *testing.T) {
 	exec(t, cmddir, cmdbase, args, filepath.Clean(cmddir)+le)
 }
 
-func checkMode(t *testing.T, path string, mode uint32) {
+func checkMode(t *testing.T, path string, mode FileMode) {
 	dir, err := Stat(path)
 	if err != nil {
 		t.Fatalf("Stat %q (looking for mode %#o): %s", path, mode, err)
 	}
-	if dir.Mode&0777 != mode {
-		t.Errorf("Stat %q: mode %#o want %#o", path, dir.Mode, mode)
+	if dir.Mode()&0777 != mode {
+		t.Errorf("Stat %q: mode %#o want %#o", path, dir.Mode(), mode)
 	}
 }
 
@@ -596,73 +596,13 @@ func TestChmod(t *testing.T) {
 	checkMode(t, f.Name(), 0123)
 }
 
-func checkUidGid(t *testing.T, path string, uid, gid int) {
-	dir, err := Stat(path)
-	if err != nil {
-		t.Fatalf("Stat %q (looking for uid/gid %d/%d): %s", path, uid, gid, err)
-	}
-	if dir.Uid != uid {
-		t.Errorf("Stat %q: uid %d want %d", path, dir.Uid, uid)
-	}
-	if dir.Gid != gid {
-		t.Errorf("Stat %q: gid %d want %d", path, dir.Gid, gid)
-	}
-}
-
-func TestChown(t *testing.T) {
-	// Chown is not supported under windows or Plan 9.
-	// Plan9 provides a native ChownPlan9 version instead.
-	if syscall.OS == "windows" || syscall.OS == "plan9" {
-		return
-	}
-	// Use TempDir() to make sure we're on a local file system,
-	// so that the group ids returned by Getgroups will be allowed
-	// on the file.  On NFS, the Getgroups groups are
-	// basically useless.
-	f := newFile("TestChown", t)
-	defer Remove(f.Name())
-	defer f.Close()
-	dir, err := f.Stat()
-	if err != nil {
-		t.Fatalf("stat %s: %s", f.Name(), err)
-	}
-
-	// Can't change uid unless root, but can try
-	// changing the group id.  First try our current group.
-	gid := Getgid()
-	t.Log("gid:", gid)
-	if err = Chown(f.Name(), -1, gid); err != nil {
-		t.Fatalf("chown %s -1 %d: %s", f.Name(), gid, err)
-	}
-	checkUidGid(t, f.Name(), dir.Uid, gid)
-
-	// Then try all the auxiliary groups.
-	groups, err := Getgroups()
-	if err != nil {
-		t.Fatalf("getgroups: %s", err)
-	}
-	t.Log("groups: ", groups)
-	for _, g := range groups {
-		if err = Chown(f.Name(), -1, g); err != nil {
-			t.Fatalf("chown %s -1 %d: %s", f.Name(), g, err)
-		}
-		checkUidGid(t, f.Name(), dir.Uid, g)
-
-		// change back to gid to test fd.Chown
-		if err = f.Chown(-1, gid); err != nil {
-			t.Fatalf("fchown %s -1 %d: %s", f.Name(), gid, err)
-		}
-		checkUidGid(t, f.Name(), dir.Uid, gid)
-	}
-}
-
 func checkSize(t *testing.T, f *File, size int64) {
 	dir, err := f.Stat()
 	if err != nil {
 		t.Fatalf("Stat %q (looking for size %d): %s", f.Name(), size, err)
 	}
-	if dir.Size != size {
-		t.Errorf("Stat %q: size %d want %d", f.Name(), dir.Size, size)
+	if dir.Size() != size {
+		t.Errorf("Stat %q: size %d want %d", f.Name(), dir.Size(), size)
 	}
 }
 
@@ -714,36 +654,38 @@ func TestChtimes(t *testing.T) {
 	f.Write([]byte("hello, world\n"))
 	f.Close()
 
-	preStat, err := Stat(f.Name())
+	st, err := Stat(f.Name())
 	if err != nil {
 		t.Fatalf("Stat %s: %s", f.Name(), err)
 	}
+	preStat := st.(*FileStat)
 
 	// Move access and modification time back a second
-	err = Chtimes(f.Name(), preStat.AccessTime.Add(-time.Second), preStat.ModTime.Add(-time.Second))
+	at := Atime(preStat)
+	mt := preStat.ModTime()
+	err = Chtimes(f.Name(), at.Add(-time.Second), mt.Add(-time.Second))
 	if err != nil {
 		t.Fatalf("Chtimes %s: %s", f.Name(), err)
 	}
 
-	postStat, err := Stat(f.Name())
+	st, err = Stat(f.Name())
 	if err != nil {
 		t.Fatalf("second Stat %s: %s", f.Name(), err)
 	}
+	postStat := st.(*FileStat)
 
 	/* Plan 9:
 		Mtime is the time of the last change of content.  Similarly, atime is set whenever the
 	    contents are accessed; also, it is set whenever mtime is set.
 	*/
-	if !postStat.AccessTime.Before(preStat.AccessTime) && syscall.OS != "plan9" {
-		t.Errorf("AccessTime didn't go backwards; was=%d, after=%d",
-			preStat.AccessTime,
-			postStat.AccessTime)
+	pat := Atime(postStat)
+	pmt := postStat.ModTime()
+	if !pat.Before(at) && syscall.OS != "plan9" {
+		t.Errorf("AccessTime didn't go backwards; was=%d, after=%d", at, pat)
 	}
 
-	if !postStat.ModTime.Before(preStat.ModTime) {
-		t.Errorf("ModTime didn't go backwards; was=%d, after=%d",
-			preStat.ModTime,
-			postStat.ModTime)
+	if !pmt.Before(mt) {
+		t.Errorf("ModTime didn't go backwards; was=%d, after=%d", mt, pmt)
 	}
 }
 
@@ -885,7 +827,7 @@ func TestOpenError(t *testing.T) {
 		}
 		perr, ok := err.(*PathError)
 		if !ok {
-			t.Errorf("Open(%q, %d) returns error of %T type; want *os.PathError", tt.path, tt.mode, err)
+			t.Errorf("Open(%q, %d) returns error of %T type; want *PathError", tt.path, tt.mode, err)
 		}
 		if perr.Err != tt.error {
 			if syscall.OS == "plan9" {
diff --git a/src/pkg/os/os_unix_test.go b/src/pkg/os/os_unix_test.go
new file mode 100644
index 0000000000..3109a8171a
--- /dev/null
+++ b/src/pkg/os/os_unix_test.go
@@ -0,0 +1,75 @@
+// 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.
+
+// +build darwin freebsd linux openbsd
+
+package os_test
+
+import (
+	. "os"
+	"syscall"
+	"testing"
+)
+
+func checkUidGid(t *testing.T, path string, uid, gid int) {
+	dir, err := Stat(path)
+	if err != nil {
+		t.Fatalf("Stat %q (looking for uid/gid %d/%d): %s", path, uid, gid, err)
+	}
+	sys := dir.(*FileStat).Sys.(*syscall.Stat_t)
+	if int(sys.Uid) != uid {
+		t.Errorf("Stat %q: uid %d want %d", path, sys.Uid, uid)
+	}
+	if int(sys.Gid) != gid {
+		t.Errorf("Stat %q: gid %d want %d", path, sys.Gid, gid)
+	}
+}
+
+func TestChown(t *testing.T) {
+	// Chown is not supported under windows or Plan 9.
+	// Plan9 provides a native ChownPlan9 version instead.
+	if syscall.OS == "windows" || syscall.OS == "plan9" {
+		return
+	}
+	// Use TempDir() to make sure we're on a local file system,
+	// so that the group ids returned by Getgroups will be allowed
+	// on the file.  On NFS, the Getgroups groups are
+	// basically useless.
+	f := newFile("TestChown", t)
+	defer Remove(f.Name())
+	defer f.Close()
+	dir, err := f.Stat()
+	if err != nil {
+		t.Fatalf("stat %s: %s", f.Name(), err)
+	}
+
+	// Can't change uid unless root, but can try
+	// changing the group id.  First try our current group.
+	gid := Getgid()
+	t.Log("gid:", gid)
+	if err = Chown(f.Name(), -1, gid); err != nil {
+		t.Fatalf("chown %s -1 %d: %s", f.Name(), gid, err)
+	}
+	sys := dir.(*FileStat).Sys.(*syscall.Stat_t)
+	checkUidGid(t, f.Name(), int(sys.Uid), gid)
+
+	// Then try all the auxiliary groups.
+	groups, err := Getgroups()
+	if err != nil {
+		t.Fatalf("getgroups: %s", err)
+	}
+	t.Log("groups: ", groups)
+	for _, g := range groups {
+		if err = Chown(f.Name(), -1, g); err != nil {
+			t.Fatalf("chown %s -1 %d: %s", f.Name(), g, err)
+		}
+		checkUidGid(t, f.Name(), int(sys.Uid), g)
+
+		// change back to gid to test fd.Chown
+		if err = f.Chown(-1, gid); err != nil {
+			t.Fatalf("fchown %s -1 %d: %s", f.Name(), gid, err)
+		}
+		checkUidGid(t, f.Name(), int(sys.Uid), gid)
+	}
+}
diff --git a/src/pkg/os/path.go b/src/pkg/os/path.go
index 82fade63ae..bc14a78318 100644
--- a/src/pkg/os/path.go
+++ b/src/pkg/os/path.go
@@ -17,7 +17,7 @@ func MkdirAll(path string, perm uint32) error {
 	// If path exists, stop with success or error.
 	dir, err := Stat(path)
 	if err == nil {
-		if dir.IsDirectory() {
+		if dir.IsDir() {
 			return nil
 		}
 		return &PathError{"mkdir", path, ENOTDIR}
@@ -48,7 +48,7 @@ func MkdirAll(path string, perm uint32) error {
 		// Handle arguments like "foo/." by
 		// double-checking that directory doesn't exist.
 		dir, err1 := Lstat(path)
-		if err1 == nil && dir.IsDirectory() {
+		if err1 == nil && dir.IsDir() {
 			return nil
 		}
 		return err
@@ -75,7 +75,7 @@ func RemoveAll(path string) error {
 		}
 		return serr
 	}
-	if !dir.IsDirectory() {
+	if !dir.IsDir() {
 		// Not a directory; return the error from Remove.
 		return err
 	}
diff --git a/src/pkg/os/stat_darwin.go b/src/pkg/os/stat_darwin.go
index 00bf612746..81d6cd57c7 100644
--- a/src/pkg/os/stat_darwin.go
+++ b/src/pkg/os/stat_darwin.go
@@ -9,31 +9,48 @@ import (
 	"time"
 )
 
-func isSymlink(stat *syscall.Stat_t) bool {
-	return stat.Mode&syscall.S_IFMT == syscall.S_IFLNK
+func sameFile(fs1, fs2 *FileStat) bool {
+	sys1 := fs1.Sys.(*syscall.Stat_t)
+	sys2 := fs2.Sys.(*syscall.Stat_t)
+	return sys1.Dev == sys2.Dev && sys1.Ino == sys2.Ino
 }
 
-func fileInfoFromStat(name string, fi *FileInfo, lstat, stat *syscall.Stat_t) *FileInfo {
-	fi.Dev = uint64(stat.Dev)
-	fi.Ino = stat.Ino
-	fi.Nlink = uint64(stat.Nlink)
-	fi.Mode = uint32(stat.Mode)
-	fi.Uid = int(stat.Uid)
-	fi.Gid = int(stat.Gid)
-	fi.Rdev = uint64(stat.Rdev)
-	fi.Size = stat.Size
-	fi.Blksize = int64(stat.Blksize)
-	fi.Blocks = stat.Blocks
-	fi.AccessTime = timespecToTime(stat.Atimespec)
-	fi.ModTime = timespecToTime(stat.Mtimespec)
-	fi.ChangeTime = timespecToTime(stat.Ctimespec)
-	fi.Name = basename(name)
-	if isSymlink(lstat) && !isSymlink(stat) {
-		fi.FollowedSymlink = true
+func fileInfoFromStat(st *syscall.Stat_t, name string) FileInfo {
+	fs := &FileStat{
+		name:    basename(name),
+		size:    int64(st.Size),
+		modTime: timespecToTime(st.Mtimespec),
+		Sys:     st,
 	}
-	return fi
+	fs.mode = FileMode(st.Mode & 0777)
+	switch st.Mode & syscall.S_IFMT {
+	case syscall.S_IFBLK, syscall.S_IFCHR, syscall.S_IFWHT:
+		fs.mode |= ModeDevice
+	case syscall.S_IFDIR:
+		fs.mode |= ModeDir
+	case syscall.S_IFIFO:
+		fs.mode |= ModeNamedPipe
+	case syscall.S_IFLNK:
+		fs.mode |= ModeSymlink
+	case syscall.S_IFREG:
+		// nothing to do
+	case syscall.S_IFSOCK:
+		fs.mode |= ModeSocket
+	}
+	if st.Mode&syscall.S_ISGID != 0 {
+		fs.mode |= ModeSetgid
+	}
+	if st.Mode&syscall.S_ISUID != 0 {
+		fs.mode |= ModeSetuid
+	}
+	return fs
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
 	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
 }
+
+// For testing.
+func atime(fi FileInfo) time.Time {
+	return timespecToTime(fi.(*FileStat).Sys.(*syscall.Stat_t).Atimespec)
+}
diff --git a/src/pkg/os/stat_freebsd.go b/src/pkg/os/stat_freebsd.go
index a82a0b7bb1..c142edffab 100644
--- a/src/pkg/os/stat_freebsd.go
+++ b/src/pkg/os/stat_freebsd.go
@@ -9,31 +9,48 @@ import (
 	"time"
 )
 
-func isSymlink(stat *syscall.Stat_t) bool {
-	return stat.Mode&syscall.S_IFMT == syscall.S_IFLNK
+func sameFile(fs1, fs2 *FileStat) bool {
+	sys1 := fs1.Sys.(*syscall.Stat_t)
+	sys2 := fs2.Sys.(*syscall.Stat_t)
+	return sys1.Dev == sys2.Dev && sys1.Ino == sys2.Ino
 }
 
-func fileInfoFromStat(name string, fi *FileInfo, lstat, stat *syscall.Stat_t) *FileInfo {
-	fi.Dev = uint64(stat.Dev)
-	fi.Ino = uint64(stat.Ino)
-	fi.Nlink = uint64(stat.Nlink)
-	fi.Mode = uint32(stat.Mode)
-	fi.Uid = int(stat.Uid)
-	fi.Gid = int(stat.Gid)
-	fi.Rdev = uint64(stat.Rdev)
-	fi.Size = int64(stat.Size)
-	fi.Blksize = int64(stat.Blksize)
-	fi.Blocks = stat.Blocks
-	fi.AccessTime = timespecToTime(stat.Atimespec)
-	fi.ModTime = timespecToTime(stat.Mtimespec)
-	fi.ChangeTime = timespecToTime(stat.Ctimespec)
-	fi.Name = basename(name)
-	if isSymlink(lstat) && !isSymlink(stat) {
-		fi.FollowedSymlink = true
+func fileInfoFromStat(st *syscall.Stat_t, name string) FileInfo {
+	fs := &FileStat{
+		name:    basename(name),
+		size:    int64(st.Size),
+		modTime: timespecToTime(st.Mtimespec),
+		Sys:     st,
 	}
-	return fi
+	fs.mode = FileMode(st.Mode & 0777)
+	switch st.Mode & syscall.S_IFMT {
+	case syscall.S_IFBLK, syscall.S_IFCHR:
+		fs.mode |= ModeDevice
+	case syscall.S_IFDIR:
+		fs.mode |= ModeDir
+	case syscall.S_IFIFO:
+		fs.mode |= ModeNamedPipe
+	case syscall.S_IFLNK:
+		fs.mode |= ModeSymlink
+	case syscall.S_IFREG:
+		// nothing to do
+	case syscall.S_IFSOCK:
+		fs.mode |= ModeSocket
+	}
+	if st.Mode&syscall.S_ISGID != 0 {
+		fs.mode |= ModeSetgid
+	}
+	if st.Mode&syscall.S_ISUID != 0 {
+		fs.mode |= ModeSetuid
+	}
+	return fs
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
 	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
 }
+
+// For testing.
+func atime(fi FileInfo) time.Time {
+	return timespecToTime(fi.(*FileStat).Sys.(*syscall.Stat_t).Atimespec)
+}
diff --git a/src/pkg/os/stat_linux.go b/src/pkg/os/stat_linux.go
index 5f9c115e29..66189a6b9b 100644
--- a/src/pkg/os/stat_linux.go
+++ b/src/pkg/os/stat_linux.go
@@ -9,31 +9,48 @@ import (
 	"time"
 )
 
-func isSymlink(stat *syscall.Stat_t) bool {
-	return stat.Mode&syscall.S_IFMT == syscall.S_IFLNK
+func sameFile(fs1, fs2 *FileStat) bool {
+	sys1 := fs1.Sys.(*syscall.Stat_t)
+	sys2 := fs2.Sys.(*syscall.Stat_t)
+	return sys1.Dev == sys2.Dev && sys1.Ino == sys2.Ino
 }
 
-func fileInfoFromStat(name string, fi *FileInfo, lstat, stat *syscall.Stat_t) *FileInfo {
-	fi.Dev = stat.Dev
-	fi.Ino = stat.Ino
-	fi.Nlink = uint64(stat.Nlink)
-	fi.Mode = stat.Mode
-	fi.Uid = int(stat.Uid)
-	fi.Gid = int(stat.Gid)
-	fi.Rdev = stat.Rdev
-	fi.Size = stat.Size
-	fi.Blksize = int64(stat.Blksize)
-	fi.Blocks = stat.Blocks
-	fi.AccessTime = timespecToTime(stat.Atim)
-	fi.ModTime = timespecToTime(stat.Mtim)
-	fi.ChangeTime = timespecToTime(stat.Ctim)
-	fi.Name = basename(name)
-	if isSymlink(lstat) && !isSymlink(stat) {
-		fi.FollowedSymlink = true
+func fileInfoFromStat(st *syscall.Stat_t, name string) FileInfo {
+	fs := &FileStat{
+		name:    basename(name),
+		size:    int64(st.Size),
+		modTime: timespecToTime(st.Mtim),
+		Sys:     st,
 	}
-	return fi
+	fs.mode = FileMode(st.Mode & 0777)
+	switch st.Mode & syscall.S_IFMT {
+	case syscall.S_IFBLK, syscall.S_IFCHR:
+		fs.mode |= ModeDevice
+	case syscall.S_IFDIR:
+		fs.mode |= ModeDir
+	case syscall.S_IFIFO:
+		fs.mode |= ModeNamedPipe
+	case syscall.S_IFLNK:
+		fs.mode |= ModeSymlink
+	case syscall.S_IFREG:
+		// nothing to do
+	case syscall.S_IFSOCK:
+		fs.mode |= ModeSocket
+	}
+	if st.Mode&syscall.S_ISGID != 0 {
+		fs.mode |= ModeSetgid
+	}
+	if st.Mode&syscall.S_ISUID != 0 {
+		fs.mode |= ModeSetuid
+	}
+	return fs
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
 	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
 }
+
+// For testing.
+func atime(fi FileInfo) time.Time {
+	return timespecToTime(fi.(*FileStat).Sys.(*syscall.Stat_t).Atim)
+}
diff --git a/src/pkg/os/stat_openbsd.go b/src/pkg/os/stat_openbsd.go
index 943d34c402..66189a6b9b 100644
--- a/src/pkg/os/stat_openbsd.go
+++ b/src/pkg/os/stat_openbsd.go
@@ -9,31 +9,48 @@ import (
 	"time"
 )
 
-func isSymlink(stat *syscall.Stat_t) bool {
-	return stat.Mode&syscall.S_IFMT == syscall.S_IFLNK
+func sameFile(fs1, fs2 *FileStat) bool {
+	sys1 := fs1.Sys.(*syscall.Stat_t)
+	sys2 := fs2.Sys.(*syscall.Stat_t)
+	return sys1.Dev == sys2.Dev && sys1.Ino == sys2.Ino
 }
 
-func fileInfoFromStat(name string, fi *FileInfo, lstat, stat *syscall.Stat_t) *FileInfo {
-	fi.Dev = uint64(stat.Dev)
-	fi.Ino = uint64(stat.Ino)
-	fi.Nlink = uint64(stat.Nlink)
-	fi.Mode = uint32(stat.Mode)
-	fi.Uid = int(stat.Uid)
-	fi.Gid = int(stat.Gid)
-	fi.Rdev = uint64(stat.Rdev)
-	fi.Size = int64(stat.Size)
-	fi.Blksize = int64(stat.Blksize)
-	fi.Blocks = stat.Blocks
-	fi.AccessTime = timespecToTime(stat.Atim)
-	fi.ModTime = timespecToTime(stat.Mtim)
-	fi.ChangeTime = timespecToTime(stat.Ctim)
-	fi.Name = basename(name)
-	if isSymlink(lstat) && !isSymlink(stat) {
-		fi.FollowedSymlink = true
+func fileInfoFromStat(st *syscall.Stat_t, name string) FileInfo {
+	fs := &FileStat{
+		name:    basename(name),
+		size:    int64(st.Size),
+		modTime: timespecToTime(st.Mtim),
+		Sys:     st,
 	}
-	return fi
+	fs.mode = FileMode(st.Mode & 0777)
+	switch st.Mode & syscall.S_IFMT {
+	case syscall.S_IFBLK, syscall.S_IFCHR:
+		fs.mode |= ModeDevice
+	case syscall.S_IFDIR:
+		fs.mode |= ModeDir
+	case syscall.S_IFIFO:
+		fs.mode |= ModeNamedPipe
+	case syscall.S_IFLNK:
+		fs.mode |= ModeSymlink
+	case syscall.S_IFREG:
+		// nothing to do
+	case syscall.S_IFSOCK:
+		fs.mode |= ModeSocket
+	}
+	if st.Mode&syscall.S_ISGID != 0 {
+		fs.mode |= ModeSetgid
+	}
+	if st.Mode&syscall.S_ISUID != 0 {
+		fs.mode |= ModeSetuid
+	}
+	return fs
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
 	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
 }
+
+// For testing.
+func atime(fi FileInfo) time.Time {
+	return timespecToTime(fi.(*FileStat).Sys.(*syscall.Stat_t).Atim)
+}
diff --git a/src/pkg/os/stat_windows.go b/src/pkg/os/stat_windows.go
index b226b2913b..d024915ee0 100644
--- a/src/pkg/os/stat_windows.go
+++ b/src/pkg/os/stat_windows.go
@@ -12,7 +12,7 @@ import (
 
 // Stat returns the FileInfo structure describing file.
 // It returns the FileInfo and an error, if any.
-func (file *File) Stat() (fi *FileInfo, err error) {
+func (file *File) Stat() (fi FileInfo, err error) {
 	if file == nil || file.fd < 0 {
 		return nil, EINVAL
 	}
@@ -25,7 +25,7 @@ func (file *File) Stat() (fi *FileInfo, err error) {
 	if e != nil {
 		return nil, &PathError{"GetFileInformationByHandle", file.name, e}
 	}
-	return setFileInfo(new(FileInfo), basename(file.name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
+	return toFileInfo(basename(file.name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
 }
 
 // Stat returns a FileInfo structure describing the named file and an error, if any.
@@ -33,7 +33,7 @@ func (file *File) Stat() (fi *FileInfo, err error) {
 // the file pointed at by the link and has fi.FollowedSymlink set to true.
 // If name names an invalid symbolic link, the returned FileInfo describes
 // the link itself and has fi.FollowedSymlink set to false.
-func Stat(name string) (fi *FileInfo, err error) {
+func Stat(name string) (fi FileInfo, err error) {
 	if len(name) == 0 {
 		return nil, &PathError{"Stat", name, syscall.Errno(syscall.ERROR_PATH_NOT_FOUND)}
 	}
@@ -42,13 +42,13 @@ func Stat(name string) (fi *FileInfo, err error) {
 	if e != nil {
 		return nil, &PathError{"GetFileAttributesEx", name, e}
 	}
-	return setFileInfo(new(FileInfo), basename(name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
+	return toFileInfo(basename(name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
 }
 
 // Lstat returns the FileInfo structure describing the named file and an
 // error, if any.  If the file is a symbolic link, the returned FileInfo
 // describes the symbolic link.  Lstat makes no attempt to follow the link.
-func Lstat(name string) (fi *FileInfo, err error) {
+func Lstat(name string) (fi FileInfo, err error) {
 	// No links on Windows
 	return Stat(name)
 }
@@ -77,23 +77,23 @@ func basename(name string) string {
 	return name
 }
 
-func setFileInfo(fi *FileInfo, name string, fa, sizehi, sizelo uint32, ctime, atime, wtime syscall.Filetime) *FileInfo {
-	fi.Mode = 0
+func toFileInfo(name string, fa, sizehi, sizelo uint32, ctime, atime, wtime syscall.Filetime) FileInfo {
+	fs := new(FileStat)
+	fs.mode = 0
 	if fa&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
-		fi.Mode = fi.Mode | syscall.S_IFDIR
-	} else {
-		fi.Mode = fi.Mode | syscall.S_IFREG
+		fs.mode |= ModeDir
 	}
 	if fa&syscall.FILE_ATTRIBUTE_READONLY != 0 {
-		fi.Mode = fi.Mode | 0444
+		fs.mode |= 0444
 	} else {
-		fi.Mode = fi.Mode | 0666
+		fs.mode |= 0666
 	}
-	fi.Size = int64(sizehi)<<32 + int64(sizelo)
-	fi.Name = name
-	fi.FollowedSymlink = false
-	fi.AccessTime = time.Unix(0, atime.Nanoseconds())
-	fi.ModTime = time.Unix(0, wtime.Nanoseconds())
-	fi.ChangeTime = time.Unix(0, ctime.Nanoseconds())
-	return fi
+	fs.size = int64(sizehi)<<32 + int64(sizelo)
+	fs.name = name
+	fs.modTime = time.Unix(0, wtime.Nanoseconds())
+	return fs
+}
+
+func sameFile(fs1, fs2 *FileStat) bool {
+	return false
 }
diff --git a/src/pkg/os/types.go b/src/pkg/os/types.go
index 3f8ac78350..dff7090cdb 100644
--- a/src/pkg/os/types.go
+++ b/src/pkg/os/types.go
@@ -9,51 +9,103 @@ import (
 	"time"
 )
 
-// An operating-system independent representation of Unix data structures.
-// OS-specific routines in this directory convert the OS-local versions to these.
-
 // Getpagesize returns the underlying system's memory page size.
 func Getpagesize() int { return syscall.Getpagesize() }
 
-// A FileInfo describes a file and is returned by Stat, Fstat, and Lstat
-type FileInfo struct {
-	Dev             uint64    // device number of file system holding file.
-	Ino             uint64    // inode number.
-	Nlink           uint64    // number of hard links.
-	Mode            uint32    // permission and mode bits.
-	Uid             int       // user id of owner.
-	Gid             int       // group id of owner.
-	Rdev            uint64    // device type for special file.
-	Size            int64     // length in bytes.
-	Blksize         int64     // size of blocks, in bytes.
-	Blocks          int64     // number of blocks allocated for file.
-	AccessTime      time.Time // access time
-	ModTime         time.Time // modification time
-	ChangeTime      time.Time // status change time
-	Name            string    // base name of the file name provided in Open, Stat, etc.
-	FollowedSymlink bool      // followed a symlink to get this information
+// A FileInfo describes a file and is returned by Stat and Lstat
+type FileInfo interface {
+	Name() string       // base name of the file
+	Size() int64        // length in bytes
+	Mode() FileMode     // file mode bits
+	ModTime() time.Time // modification time
+	IsDir() bool        // abbreviation for Mode().IsDir()
 }
 
-// IsFifo reports whether the FileInfo describes a FIFO file.
-func (f *FileInfo) IsFifo() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFIFO }
+// A FileMode represents a file's mode and permission bits.
+// The bits have the same definition on all systems, so that
+// information about files can be moved from one system
+// to another portably.  Not all bits apply to all systems.
+// The only required bit is ModeDir for directories.
+type FileMode uint32
 
-// IsChar reports whether the FileInfo describes a character special file.
-func (f *FileInfo) IsChar() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFCHR }
+// The defined file mode bits are the most significant bits of the FileMode.
+// The nine least-significant bits are the standard Unix rwxrwxrwx permissions.
+const (
+	// The single letters are the abbreviations
+	// used by the String method's formatting.
+	ModeDir       FileMode = 1 << (32 - 1 - iota) // d: is a directory
+	ModeAppend                                    // a: append-only
+	ModeExclusive                                 // l: exclusive use
+	ModeTemporary                                 // t: temporary file (not backed up)
+	ModeSymlink                                   // L: symbolic link
+	ModeDevice                                    // D: device file
+	ModeNamedPipe                                 // p: named pipe (FIFO)
+	ModeSocket                                    // S: Unix domain socket
+	ModeSetuid                                    // u: setuid
+	ModeSetgid                                    // g: setgid
 
-// IsDirectory reports whether the FileInfo describes a directory.
-func (f *FileInfo) IsDirectory() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFDIR }
+	ModePerm FileMode = 0777 // permission bits
+)
 
-// IsBlock reports whether the FileInfo describes a block special file.
-func (f *FileInfo) IsBlock() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFBLK }
+func (m FileMode) String() string {
+	const str = "daltLDpSug"
+	var buf [20]byte
+	w := 0
+	for i, c := range str {
+		if m&(1<<uint(32-1-i)) != 0 {
+			buf[w] = byte(c)
+			w++
+		}
+	}
+	if w == 0 {
+		buf[w] = '-'
+		w++
+	}
+	const rwx = "rwxrwxrwx"
+	for i, c := range rwx {
+		if m&(1<<uint(9-1-i)) != 0 {
+			buf[w] = byte(c)
+		} else {
+			buf[w] = '-'
+		}
+		w++
+	}
+	return string(buf[:w])
+}
 
-// IsRegular reports whether the FileInfo describes a regular file.
-func (f *FileInfo) IsRegular() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFREG }
+// IsDir reports whether m describes a directory.
+// That is, it tests for the ModeDir bit being set in m.
+func (m FileMode) IsDir() bool {
+	return m&ModeDir != 0
+}
 
-// IsSymlink reports whether the FileInfo describes a symbolic link.
-func (f *FileInfo) IsSymlink() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFLNK }
+// Perm returns the Unix permission bits in m.
+func (m FileMode) Perm() FileMode {
+	return m & ModePerm
+}
 
-// IsSocket reports whether the FileInfo describes a socket.
-func (f *FileInfo) IsSocket() bool { return (f.Mode & syscall.S_IFMT) == syscall.S_IFSOCK }
+// A FileStat is the implementation of FileInfo returned by Stat and Lstat.
+// Clients that need access to the underlying system-specific stat information
+// can test for *os.FileStat and then consult the Sys field.
+type FileStat struct {
+	name    string
+	size    int64
+	mode    FileMode
+	modTime time.Time
 
-// Permission returns the file permission bits.
-func (f *FileInfo) Permission() uint32 { return f.Mode & 0777 }
+	Sys interface{}
+}
+
+func (fs *FileStat) Name() string       { return fs.name }
+func (fs *FileStat) Size() int64        { return fs.size }
+func (fs *FileStat) Mode() FileMode     { return fs.mode }
+func (fs *FileStat) ModTime() time.Time { return fs.modTime }
+func (fs *FileStat) IsDir() bool        { return fs.mode.IsDir() }
+
+// SameFile reports whether fs and other describe the same file.
+// For example, on Unix this means that the device and inode fields
+// of the two underlying structures are identical; on other systems
+// the decision may be based on the path names.
+func (fs *FileStat) SameFile(other *FileStat) bool {
+	return sameFile(fs, other)
+}
diff --git a/src/pkg/os/user/user_test.go b/src/pkg/os/user/user_test.go
index 59f15e4c67..f9f44af8a9 100644
--- a/src/pkg/os/user/user_test.go
+++ b/src/pkg/os/user/user_test.go
@@ -41,8 +41,8 @@ func TestLookup(t *testing.T) {
 		t.Errorf("expected Uid of %d; got %d", e, g)
 	}
 	fi, err := os.Stat(u.HomeDir)
-	if err != nil || !fi.IsDirectory() {
-		t.Errorf("expected a valid HomeDir; stat(%q): err=%v, IsDirectory=%v", u.HomeDir, err, fi.IsDirectory())
+	if err != nil || !fi.IsDir() {
+		t.Errorf("expected a valid HomeDir; stat(%q): err=%v, IsDir=%v", u.HomeDir, err, fi.IsDir())
 	}
 	if u.Username == "" {
 		t.Fatalf("didn't get a username")
diff --git a/src/pkg/path/filepath/match.go b/src/pkg/path/filepath/match.go
index 8cf1f9ad10..c3678f541d 100644
--- a/src/pkg/path/filepath/match.go
+++ b/src/pkg/path/filepath/match.go
@@ -260,7 +260,7 @@ func glob(dir, pattern string, matches []string) (m []string, e error) {
 	if err != nil {
 		return
 	}
-	if !fi.IsDirectory() {
+	if !fi.IsDir() {
 		return
 	}
 	d, err := os.Open(dir)
diff --git a/src/pkg/path/filepath/path.go b/src/pkg/path/filepath/path.go
index 3656227ff0..e3d6c342ca 100644
--- a/src/pkg/path/filepath/path.go
+++ b/src/pkg/path/filepath/path.go
@@ -223,7 +223,7 @@ func EvalSymlinks(path string) (string, error) {
 		if err != nil {
 			return "", err
 		}
-		if !fi.IsSymlink() {
+		if fi.Mode()&os.ModeSymlink == 0 {
 			b.WriteString(p)
 			if path != "" {
 				b.WriteRune(Separator)
@@ -345,19 +345,19 @@ var SkipDir = errors.New("skip this directory")
 // sole exception is that if path is a directory and the function returns the
 // special value SkipDir, the contents of the directory are skipped
 // and processing continues as usual on the next file.
-type WalkFunc func(path string, info *os.FileInfo, err error) error
+type WalkFunc func(path string, info os.FileInfo, err error) error
 
 // walk recursively descends path, calling w.
-func walk(path string, info *os.FileInfo, walkFn WalkFunc) error {
+func walk(path string, info os.FileInfo, walkFn WalkFunc) error {
 	err := walkFn(path, info, nil)
 	if err != nil {
-		if info.IsDirectory() && err == SkipDir {
+		if info.IsDir() && err == SkipDir {
 			return nil
 		}
 		return err
 	}
 
-	if !info.IsDirectory() {
+	if !info.IsDir() {
 		return nil
 	}
 
@@ -367,7 +367,7 @@ func walk(path string, info *os.FileInfo, walkFn WalkFunc) error {
 	}
 
 	for _, fileInfo := range list {
-		if err = walk(Join(path, fileInfo.Name), fileInfo, walkFn); err != nil {
+		if err = walk(Join(path, fileInfo.Name()), fileInfo, walkFn); err != nil {
 			return err
 		}
 	}
@@ -390,7 +390,7 @@ func Walk(root string, walkFn WalkFunc) error {
 // readDir reads the directory named by dirname and returns
 // a sorted list of directory entries.
 // Copied from io/ioutil to avoid the circular import.
-func readDir(dirname string) ([]*os.FileInfo, error) {
+func readDir(dirname string) ([]os.FileInfo, error) {
 	f, err := os.Open(dirname)
 	if err != nil {
 		return nil, err
@@ -400,20 +400,16 @@ func readDir(dirname string) ([]*os.FileInfo, error) {
 	if err != nil {
 		return nil, err
 	}
-	fi := make(fileInfoList, len(list))
-	for i := range list {
-		fi[i] = &list[i]
-	}
-	sort.Sort(fi)
-	return fi, nil
+	sort.Sort(byName(list))
+	return list, nil
 }
 
-// A dirList implements sort.Interface.
-type fileInfoList []*os.FileInfo
+// byName implements sort.Interface.
+type byName []os.FileInfo
 
-func (f fileInfoList) Len() int           { return len(f) }
-func (f fileInfoList) Less(i, j int) bool { return f[i].Name < f[j].Name }
-func (f fileInfoList) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
+func (f byName) Len() int           { return len(f) }
+func (f byName) Less(i, j int) bool { return f[i].Name() < f[j].Name() }
+func (f byName) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
 
 // Base returns the last element of path.
 // Trailing path separators are removed before extracting the last element.
diff --git a/src/pkg/path/filepath/path_test.go b/src/pkg/path/filepath/path_test.go
index 983cc85c8e..fab5adc102 100644
--- a/src/pkg/path/filepath/path_test.go
+++ b/src/pkg/path/filepath/path_test.go
@@ -318,7 +318,7 @@ func checkMarks(t *testing.T, report bool) {
 // Assumes that each node name is unique. Good enough for a test.
 // If clear is true, any incoming error is cleared before return. The errors
 // are always accumulated, though.
-func mark(path string, info *os.FileInfo, err error, errors *[]error, clear bool) error {
+func mark(path string, info os.FileInfo, err error, errors *[]error, clear bool) error {
 	if err != nil {
 		*errors = append(*errors, err)
 		if clear {
@@ -326,8 +326,9 @@ func mark(path string, info *os.FileInfo, err error, errors *[]error, clear bool
 		}
 		return err
 	}
+	name := info.Name()
 	walkTree(tree, tree.name, func(path string, n *Node) {
-		if n.name == info.Name {
+		if n.name == name {
 			n.mark++
 		}
 	})
@@ -338,7 +339,7 @@ func TestWalk(t *testing.T) {
 	makeTree(t)
 	errors := make([]error, 0, 10)
 	clear := true
-	markFn := func(path string, info *os.FileInfo, err error) error {
+	markFn := func(path string, info os.FileInfo, err error) error {
 		return mark(path, info, err, &errors, clear)
 	}
 	// Expect no errors.
@@ -600,7 +601,7 @@ func TestAbs(t *testing.T) {
 			t.Errorf("Abs(%q) error: %v", path, err)
 		}
 		absinfo, err := os.Stat(abspath)
-		if err != nil || absinfo.Ino != info.Ino {
+		if err != nil || !absinfo.(*os.FileStat).SameFile(info.(*os.FileStat)) {
 			t.Errorf("Abs(%q)=%q, not the same file", path, abspath)
 		}
 		if !filepath.IsAbs(abspath) {
diff --git a/src/pkg/time/zoneinfo_plan9.go b/src/pkg/time/zoneinfo_plan9.go
index 915303b926..38aefc7a97 100644
--- a/src/pkg/time/zoneinfo_plan9.go
+++ b/src/pkg/time/zoneinfo_plan9.go
@@ -6,10 +6,10 @@
 
 package time
 
-import (
-	"strconv"
-	"strings"
-)
+//import (
+//	"strconv"
+//	"strings"
+//)
 
 func parseZones(s string) (zt []zonetime) {
 	f := strings.Fields(s)