fcntl.go raw

   1  // Copyright 2014 The Go Authors. All rights reserved.
   2  // Use of this source code is governed by a BSD-style
   3  // license that can be found in the LICENSE file.
   4  
   5  //go:build dragonfly || freebsd || linux || netbsd
   6  
   7  package unix
   8  
   9  import "unsafe"
  10  
  11  // fcntl64Syscall is usually SYS_FCNTL, but is overridden on 32-bit Linux
  12  // systems by fcntl_linux_32bit.go to be SYS_FCNTL64.
  13  var fcntl64Syscall uintptr = SYS_FCNTL
  14  
  15  func fcntl(fd int, cmd, arg int) (int, error) {
  16  	valptr, _, errno := Syscall(fcntl64Syscall, uintptr(fd), uintptr(cmd), uintptr(arg))
  17  	var err error
  18  	if errno != 0 {
  19  		err = errno
  20  	}
  21  	return int(valptr), err
  22  }
  23  
  24  // FcntlInt performs a fcntl syscall on fd with the provided command and argument.
  25  func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
  26  	return fcntl(int(fd), cmd, arg)
  27  }
  28  
  29  // FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
  30  func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
  31  	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
  32  	if errno == 0 {
  33  		return nil
  34  	}
  35  	return errno
  36  }
  37