code review 4657074: os: fix build for Plan 9

src/pkg/os/file_plan9.go

 // 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
 
 import (
         "runtime"
+        "sync"
         "syscall"
 )
 
+// File represents an open file descriptor.
+type File struct {
+        fd      int
+        name    string
+        dirinfo *dirInfo   // nil unless directory being read
+        nepipe  int        // number of consecutive EPIPE in Write
+        l       sync.Mutex // used to implement windows pread/pwrite

[brainman, 2011/07/05 05:11:42]

This lock is for windows only. I don't think you need it. If you agree, perhaps,
you could change file_unix.go file as well. Thank you.

+}
+
+// Fd returns the integer Unix file descriptor referencing the open file.
+func (file *File) Fd() int {
+        if file == nil {
+                return -1
+        }
+        return file.fd
+}
+
+// NewFile returns a new File with the given file descriptor and name.
+func NewFile(fd int, name string) *File {
+        if fd < 0 {
+                return nil
+        }
+        f := &File{fd: fd, name: name}
+        runtime.SetFinalizer(f, (*File).Close)
+        return f
+}
+
 // Auxiliary information if the File describes a directory
 type dirInfo struct {
         buf  [syscall.STATMAX]byte // buffer for directory I/O
         nbuf int                   // length of buf; return value from Read
         bufp int                   // location of next record in buf.
 }
 
 func epipecheck(file *File, e syscall.Error) {
 }
 
@@ skipping 291 matching lines @@
         return EPLAN9
 }
 
 func Lchown(name string, uid, gid int) Error {
         return EPLAN9
 }
 
 func (f *File) Chown(uid, gid int) Error {
         return EPLAN9
 }