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// +build dragonfly freebsd linux netbsd openbsd
6
7package unix
8
9import "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.
13var fcntl64Syscall uintptr = SYS_FCNTL
14
15func 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.
25func 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.
30func 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