text: // Copyright 2014 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 dragonfly freebsd linux netbsd openbsd
  
  package unix
  
  import "unsafe"
  
  // fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
  // systems by flock_linux_32bit.go to be SYS_FCNTL64.
  var fcntl64Syscall uintptr = SYS_FCNTL
  
  // FcntlInt performs a fcntl syscall on fd with the provided command and argument.
  func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
  	valptr, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(arg))
  	var err error
  	if errno != 0 {
  		err = errno
  	}
  	return int(valptr), err
  }
  
  // FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
  func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
  	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
  	if errno == 0 {
  		return nil
  	}
  	return errno
  }
  