// 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 fcntl_linux_32bit.go to be SYS_FCNTL64.

var fcntl64Syscall uintptr = SYS_FCNTL

func fcntl(fd int, cmd, arg int) (int, error) {

	valptr, _, errno := Syscall(fcntl64Syscall, uintptr(fd), uintptr(cmd), uintptr(arg))

	var err error

	if errno != 0 {

		err = errno

	}

	return int(valptr), err

}

// FcntlInt performs a fcntl syscall on fd with the provided command and argument.

func FcntlInt(fd uintptr, cmd, arg int) (int, error) {

	return fcntl(int(fd), cmd, arg)

}

// 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

}