_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPCNT, 5)

				// Wait time after successful probe in seconds.
				// ~ cat /proc/sys/net/ipv4/tcp_keepalive_intvl (defaults to 75 secs, we reduce it to 15 secs)
				_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, 15)
			}

	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
}

func direntType(buf []byte) FileMode {
	off := unsafe.Offsetof(syscall.Dirent{}.Type)
	if off >= uintptr(len(buf)) {
		return ^FileMode(0) // unknown
	}
	typ := buf[off]
	switch typ {
	case syscall.DT_BLK:
		return ModeDevice
	case syscall.DT_CHR:
		return ModeDevice | ModeCharDevice
	case syscall.DT_DIR:
		return ModeDir

		socketType int
		dataLen    int
	}{
		{
			syscall.SOCK_STREAM,
			1,
		}, {
			syscall.SOCK_DGRAM,
			0,
		},
	}

	for _, tt := range socketTypeTests {
		fds, err := syscall.Socketpair(syscall.AF_LOCAL, tt.socketType, 0)
		if err != nil {
			t.Fatalf("Socketpair: %v", err)
		}

		err = syscall.SetsockoptInt(fds[0], syscall.SOL_SOCKET, syscall.SO_PASSCRED, 1)
		if err != nil {
			syscall.Close(fds[0])

package net

import (
	"syscall"
	"testing"
	"time"
)

func getCurrentKeepAliveSettings(fd fdType) (cfg KeepAliveConfig, err error) {
	tcpKeepAlive, err := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE)
	if err != nil {
		return
	}
	tcpKeepAliveIdle, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
	if err != nil {
		return
	}

	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Namlen), unsafe.Sizeof(syscall.Dirent{}.Namlen))
}

func direntType(buf []byte) FileMode {
	off := unsafe.Offsetof(syscall.Dirent{}.Type)
	if off >= uintptr(len(buf)) {
		return ^FileMode(0) // unknown
	}
	typ := buf[off]
	switch typ {
	case syscall.DT_BLK:
		return ModeDevice
	case syscall.DT_CHR:
		return ModeDevice | ModeCharDevice
	case syscall.DT_DIR:
		return ModeDir

//go:build unix || windows

package net

import (
	"runtime"
	"syscall"
)

func joinIPv4Group(fd *netFD, ifi *Interface, ip IP) error {
	mreq := &syscall.IPMreq{Multiaddr: [4]byte{ip[0], ip[1], ip[2], ip[3]}}
	if err := setIPv4MreqToInterface(mreq, ifi); err != nil {
		return err
	}
	err := fd.pfd.SetsockoptIPMreq(syscall.IPPROTO_IP, syscall.IP_ADD_MEMBERSHIP, mreq)
	runtime.KeepAlive(fd)

package os

import (
	"syscall"
	"unsafe"
)

func direntIno(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Ino), unsafe.Sizeof(syscall.Dirent{}.Ino))
}

func direntReclen(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(syscall.Dirent{}.Reclen), unsafe.Sizeof(syscall.Dirent{}.Reclen))
}

func direntNamlen(buf []byte) (uint64, bool) {

	conf[2].SetLen(len(paramPersist))
	conf[3].Base = nil
	conf[3].SetLen(0)

	id, _, err1 := syscall.Syscall(syscall.SYS_JAIL_SET,
		uintptr(unsafe.Pointer(&conf[0])), uintptr(len(conf)), flagJailCreate)
	if err1 != 0 {
		t.Fatalf("jail_set: %v", err1)
	}
	t.Cleanup(func() {
		_, _, err1 := syscall.Syscall(syscall.SYS_JAIL_REMOVE, id, 0, 0)
		if err1 != 0 {
			t.Errorf("failed to cleanup jail: %v", err)
		}
	})

	return 0, 0, syscall.EPLAN9
}

func (sd *sysDialer) dialUnix(ctx context.Context, laddr, raddr *UnixAddr) (*UnixConn, error) {
	return nil, syscall.EPLAN9
}

func (ln *UnixListener) accept() (*UnixConn, error) {
	return nil, syscall.EPLAN9
}

func (ln *UnixListener) close() error {
	return syscall.EPLAN9
}

func (ln *UnixListener) file() (*os.File, error) {
	return nil, syscall.EPLAN9
}

		return -1, sa, "accept4", err
	case syscall.ENOSYS: // syscall missing
	case syscall.EINVAL: // some Linux use this instead of ENOSYS
	case syscall.EACCES: // some Linux use this instead of ENOSYS
	case syscall.EFAULT: // some Linux use this instead of ENOSYS
	}

	// See ../syscall/exec_unix.go for description of ForkLock.
	// It is probably okay to hold the lock across syscall.Accept
	// because we have put fd.sysfd into non-blocking mode.