os/file: add file.Chmod

Signed-off-by: leongross <leon.gross@9elements.com>

src/os/file.go

@@ -307,6 +307,17 @@ func (f *File) Sync() (err error) {
 	return
 }
 
+// Chmod changes the mode of the file to mode. If there is an error, it will be
+// of type *PathError.
+func (f *File) Chmod(mode FileMode) (err error) {
+	if f.handle == nil {
+		err = ErrClosed
+	} else {
+		err = f.chmod(mode)
+	}
+	return
+}
+
 // LinkError records an error during a link or symlink or rename system call and
 // the paths that caused it.
 type LinkError struct {

src/os/file_other.go

@@ -149,3 +149,7 @@ func (f *File) Truncate(size int64) (err error) {
 
 	return Truncate(f.name, size)
 }
+
+func (f *File) chmod(mode FileMode) error {
+	return ErrUnsupported
+}

src/os/file_unix.go

@@ -151,6 +151,21 @@ func (f *File) Truncate(size int64) (err error) {
 	return Truncate(f.name, size)
 }
 
+func (f *File) chmod(mode FileMode) error {
+	if f.handle == nil {
+		return ErrClosed
+	}
+
+	longName := fixLongPath(f.name)
+	e := ignoringEINTR(func() error {
+		return syscall.Chmod(longName, syscallMode(mode))
+	})
+	if e != nil {
+		return &PathError{Op: "chmod", Path: f.name, Err: e}
+	}
+	return nil
+}
+
 // ReadAt reads up to len(b) bytes from the File starting at the given absolute offset.
 // It returns the number of bytes read and any error encountered, possibly io.EOF.
 // At end of file, Pread returns 0, io.EOF.

src/os/file_windows.go

@@ -142,3 +142,7 @@ func isWindowsNulName(name string) bool {
 	}
 	return true
 }
+
+func (f *File) chmod(mode FileMode) error {
+	return ErrNotImplemented
+}