os: use FileMode instead of uint32 in various functions

Fixes #2733

R=chickencha, ality, rsc
CC=golang-dev
https://golang.org/cl/5553064

src/cmd/go/build.go

@@ -618,7 +618,7 @@ func (b *builder) build(a *action) error {
 // install is the action for installing a single package or executable.
 func (b *builder) install(a *action) error {
 	a1 := a.deps[0]
-	perm := uint32(0666)
+	perm := os.FileMode(0666)
 	if a1.link {
 		perm = 0777
 	}
@@ -697,7 +697,7 @@ func removeByRenaming(name string) error {
 }
 
 // copyFile is like 'cp src dst'.
-func (b *builder) copyFile(dst, src string, perm uint32) error {
+func (b *builder) copyFile(dst, src string, perm os.FileMode) error {
 	if buildN || buildX {
 		b.showcmd("", "cp %s %s", src, dst)
 		if buildN {

src/cmd/hgpatch/main.go

@@ -151,7 +151,7 @@ func main() {
 			changed[o.Dst] = 1
 		}
 		if o.Mode != 0 {
-			chk(os.Chmod(o.Dst, uint32(o.Mode&0755)))
+			chk(os.Chmod(o.Dst, os.FileMode(o.Mode&0755)))
 			undoRevert(o.Dst)
 			changed[o.Dst] = 1
 		}
@@ -189,7 +189,7 @@ func makeParent(name string) {
 
 // Copy of os.MkdirAll but adds to undo log after
 // creating a directory.
-func mkdirAll(path string, perm uint32) error {
+func mkdirAll(path string, perm os.FileMode) error {
 	dir, err := os.Lstat(path)
 	if err == nil {
 		if dir.IsDir() {

src/pkg/io/ioutil/ioutil.go

@@ -50,7 +50,7 @@ func ReadFile(filename string) ([]byte, error) {
 // WriteFile writes data to a file named by filename.
 // If the file does not exist, WriteFile creates it with permissions perm;
 // otherwise WriteFile truncates it before writing.
-func WriteFile(filename string, data []byte, perm uint32) error {
+func WriteFile(filename string, data []byte, perm os.FileMode) error {
 	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
 	if err != nil {
 		return err

src/pkg/os/file.go

@@ -158,8 +158,8 @@ func (f *File) WriteString(s string) (ret int, err error) {
 
 // Mkdir creates a new directory with the specified name and permission bits.
 // It returns an error, if any.
-func Mkdir(name string, perm uint32) error {
+func Mkdir(name string, perm FileMode) error {
-	e := syscall.Mkdir(name, perm)
+	e := syscall.Mkdir(name, syscallMode(perm))
 	if e != nil {
 		return &PathError{"mkdir", name, e}
 	}

src/pkg/os/file_posix.go

@@ -81,18 +81,34 @@ func Rename(oldname, newname string) error {
 	return nil
 }
 
+// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
+func syscallMode(i FileMode) (o uint32) {
+	o |= uint32(i.Perm())
+	if i&ModeSetuid != 0 {
+		o |= syscall.S_ISUID
+	}
+	if i&ModeSetgid != 0 {
+		o |= syscall.S_ISGID
+	}
+	if i&ModeSticky != 0 {
+		o |= syscall.S_ISVTX
+	}
+	// No mapping for Go's ModeTemporary (plan9 only).
+	return
+}
+
 // Chmod changes the mode of the named file to mode.
 // If the file is a symbolic link, it changes the mode of the link's target.
-func Chmod(name string, mode uint32) error {
+func Chmod(name string, mode FileMode) error {
-	if e := syscall.Chmod(name, mode); e != nil {
+	if e := syscall.Chmod(name, syscallMode(mode)); e != nil {
 		return &PathError{"chmod", name, e}
 	}
 	return nil
 }
 
 // Chmod changes the mode of the file to mode.
-func (f *File) Chmod(mode uint32) error {
+func (f *File) Chmod(mode FileMode) error {
-	if e := syscall.Fchmod(f.fd, mode); e != nil {
+	if e := syscall.Fchmod(f.fd, syscallMode(mode)); e != nil {
 		return &PathError{"chmod", f.name, e}
 	}
 	return nil

src/pkg/os/file_unix.go

@@ -61,8 +61,8 @@ const DevNull = "/dev/null"
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
 // methods on the returned File can be used for I/O.
 // It returns the File and an error, if any.
-func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
+func OpenFile(name string, flag int, perm FileMode) (file *File, err error) {
-	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
+	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
 	if e != nil {
 		return nil, &PathError{"open", name, e}
 	}

src/pkg/os/file_windows.go

@@ -57,8 +57,8 @@ const DevNull = "NUL"
 
 func (f *file) isdir() bool { return f != nil && f.dirinfo != nil }
 
-func openFile(name string, flag int, perm uint32) (file *File, err error) {
+func openFile(name string, flag int, perm FileMode) (file *File, err error) {
-	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
+	r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
 	if e != nil {
 		return nil, &PathError{"open", name, e}
 	}
@@ -88,7 +88,7 @@ func openDir(name string) (file *File, err error) {
 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
 // methods on the returned File can be used for I/O.
 // It returns the File and an error, if any.
-func OpenFile(name string, flag int, perm uint32) (file *File, err error) {
+func OpenFile(name string, flag int, perm FileMode) (file *File, err error) {
 	if name == "" {
 		return nil, &PathError{"open", name, syscall.ENOENT}
 	}

src/pkg/os/path.go

@@ -13,7 +13,7 @@ import "io"
 // directories that MkdirAll creates.
 // If path is already a directory, MkdirAll does nothing
 // and returns nil.
-func MkdirAll(path string, perm uint32) error {
+func MkdirAll(path string, perm FileMode) error {
 	// If path exists, stop with success or error.
 	dir, err := Stat(path)
 	if err == nil {