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 darwin 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 flock_linux_32bit.go to be SYS_FCNTL64.
13var fcntl64Syscall uintptr = SYS_FCNTL
14
15// FcntlInt performs a fcntl syscall on fd with the provided command and argument.
16func FcntlInt(fd uintptr, cmd, arg int) (int, error) {
17	valptr, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(arg))
18	var err error
19	if errno != 0 {
20		err = errno
21	}
22	return int(valptr), err
23}
24
25// FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
26func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
27	_, _, errno := Syscall(fcntl64Syscall, fd, uintptr(cmd), uintptr(unsafe.Pointer(lk)))
28	if errno == 0 {
29		return nil
30	}
31	return errno
32}
33