code review 5336045: os: fixes for error (plan9)

src/pkg/os/error_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 syscall "syscall"
+import (
+        "errors"
+        "syscall"
+)
 
 // SyscallError records an error from a specific system call.
 type SyscallError struct {
         Syscall string
         Err     string
 }
 
 func (e *SyscallError) Error() string { return e.Syscall + ": " + e.Err }
 
 // Note: If the name of the function NewSyscallError changes,
 // pkg/go/doc/doc.go should be adjusted since it hardwires
 // this name in a heuristic.
 
 // NewSyscallError returns, as an error, a new SyscallError
 // with the given system call name and error details.
 // As a convenience, if err is nil, NewSyscallError returns nil.
 func NewSyscallError(syscall string, err syscall.Error) error {
         if err == nil {
                 return nil
         }
         return &SyscallError{syscall, err.String()}
 }
 
 var (
-        Eshortstat = NewError("stat buffer too small")
-        Ebadstat   = NewError("malformed stat buffer")
-        Ebadfd     = NewError("fd out of range or not open")
-        Ebadarg    = NewError("bad arg in system call")
-        Enotdir    = NewError("not a directory")
-        Enonexist  = NewError("file does not exist")
-        Eexist     = NewError("file already exists")
-        Eio        = NewError("i/o error")
-        Eperm      = NewError("permission denied")
+        Eshortstat = errors.New("stat buffer too small")
+        Ebadstat   = errors.New("malformed stat buffer")
+        Ebadfd     = errors.New("fd out of range or not open")
+        Ebadarg    = errors.New("bad arg in system call")
+        Enotdir    = errors.New("not a directory")
+        Enonexist  = errors.New("file does not exist")
+        Eexist     = errors.New("file already exists")
+        Eio        = errors.New("i/o error")
+        Eperm      = errors.New("permission denied")
 
         EINVAL  = Ebadarg
         ENOTDIR = Enotdir
         ENOENT  = Enonexist
         EEXIST  = Eexist
         EIO     = Eio
         EACCES  = Eperm
         EPERM   = Eperm
         EISDIR  = syscall.EISDIR
 
-        EBADF        = NewError("bad file descriptor")
-        ENAMETOOLONG = NewError("file name too long")
-        ERANGE       = NewError("math result not representable")
-        EPIPE        = NewError("Broken Pipe")
-        EPLAN9       = NewError("not supported by plan 9")
+        EBADF        = errors.New("bad file descriptor")
+        ENAMETOOLONG = errors.New("file name too long")
+        ERANGE       = errors.New("math result not representable")
+        EPIPE        = errors.New("Broken Pipe")
+        EPLAN9       = errors.New("not supported by plan 9")
 )
 
 func iserror(err syscall.Error) bool {
         return err != nil
 }
 
 func Errno(e syscall.Error) syscall.Error { return e }