checkCloseonexec(t, w, "writer")

	// Test that fcntl returns an error as expected.
	if runtime.Close(r) != 0 {
		t.Fatalf("Close(%d) failed", r)
	}
	val, errno := runtime.Fcntl(r, syscall.F_GETFD, 0)
	if val != -1 {
		t.Errorf("Fcntl succeeded unexpectedly")
	} else if syscall.Errno(errno) != syscall.EBADF {
		t.Errorf("Fcntl failed with error %v, expected %v", syscall.Errno(errno), syscall.EBADF)
	}
}

// license that can be found in the LICENSE file.

package ld

import (
	"syscall"
	"unsafe"
)

// Implemented in the syscall package.
//
//go:linkname fcntl syscall.fcntl
func fcntl(fd int, cmd int, arg int) (int, error)

func (out *OutBuf) fallocate(size uint64) error {
	stat, err := out.f.Stat()
	if err != nil {
		return err
	}

// descriptors.
func forkExecPipe(p []int) error {
	err := Pipe(p)
	if err != nil {
		return err
	}
	_, err = fcntl(p[0], F_SETFD, FD_CLOEXEC)
	if err != nil {
		return err
	}
	_, err = fcntl(p[1], F_SETFD, FD_CLOEXEC)
	return err
}

func acquireForkLock() {
	ForkLock.Lock()
}

func releaseForkLock() {
	ForkLock.Unlock()

// license that can be found in the LICENSE file.

//go:build (linux && 386) || (linux && arm) || (linux && mips) || (linux && mipsle) || (linux && ppc)

package unix

func init() {
	// On 32-bit Linux systems, the fcntl syscall that matches Go's
	// Flock_t type is SYS_FCNTL64, not SYS_FCNTL.
	fcntl64Syscall = SYS_FCNTL64

// license that can be found in the LICENSE file.

//go:build darwin || dragonfly || freebsd || netbsd || openbsd

package syscall

import "unsafe"

// 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 {
	_, err := fcntlPtr(int(fd), cmd, unsafe.Pointer(lk))
	return err

// Copyright 2023 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.

//go:build wasip1

package unix

import "syscall"

func Fcntl(fd int, cmd int, arg int) (int, error) {
	if cmd == syscall.F_GETFL {
		flags, err := fd_fdstat_get_flags(fd)
		return int(flags), err
	}
	return 0, syscall.ENOSYS

// license that can be found in the LICENSE file.

//go:build (linux && 386) || (linux && arm) || (linux && mips) || (linux && mipsle)

package syscall

func init() {
	// On 32-bit Linux systems, the fcntl syscall that matches Go's
	// Flock_t type is SYS_FCNTL64, not SYS_FCNTL.
	fcntl64Syscall = SYS_FCNTL64

// used by internal/poll
//go:linkname fdopendir

// used by internal/syscall/unix
//go:linkname unlinkat
//go:linkname openat
//go:linkname fstatat

// used by cmd/link
//go:linkname msync

//sys	ioctlPtr(fd int, req int, arg unsafe.Pointer) (err error) = ioctl

// fcntl must never be called with cmd=F_DUP2FD because it doesn't work on AIX
// There is no way to create a custom fcntl and to keep //sys fcntl easily,
// Therefore, the programmer must call dup2 instead of fcntl in this case.

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

const (
	// These values are the same on all known Unix systems.
	// If we find a discrepancy some day, we can split them out.
	_F_SETFD    = 2
	_FD_CLOEXEC = 1
)

//go:nosplit
func closeonexec(fd int32) {
	fcntl(fd, _F_SETFD, _FD_CLOEXEC)