unix/syscall_unix.go - sys - Git at Google

 // Copyright 2009 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 aix darwin dragonfly freebsd linux netbsd openbsd solaris

 package unix

 import (
 	"bytes"
 	"sort"
 	"sync"
 	"syscall"
 	"unsafe"
 )

 var (
 	Stdin  = 0
 	Stdout = 1
 	Stderr = 2
 )

 // Do the interface allocations only once for common
 // Errno values.
 var (
 	errEAGAIN error = syscall.EAGAIN
 	errEINVAL error = syscall.EINVAL
 	errENOENT error = syscall.ENOENT
 )

 var (
 	signalNameMapOnce sync.Once
 	signalNameMap     map[string]syscall.Signal
 )

 // errnoErr returns common boxed Errno values, to prevent
 // allocations at runtime.
 func errnoErr(e syscall.Errno) error {
 	switch e {
 	case 0:
 		return nil
 	case EAGAIN:
 		return errEAGAIN
 	case EINVAL:
 		return errEINVAL
 	case ENOENT:
 		return errENOENT
 	}
 	return e
 }

 // ErrnoName returns the error name for error number e.
 func ErrnoName(e syscall.Errno) string {
 	i := sort.Search(len(errorList), func(i int) bool {
 		return errorList[i].num >= e
 	})
 	if i < len(errorList) && errorList[i].num == e {
 		return errorList[i].name
 	}
 	return ""
 }

 // SignalName returns the signal name for signal number s.
 func SignalName(s syscall.Signal) string {
 	i := sort.Search(len(signalList), func(i int) bool {
 		return signalList[i].num >= s
 	})
 	if i < len(signalList) && signalList[i].num == s {
 		return signalList[i].name
 	}
 	return ""
 }

 // SignalNum returns the syscall.Signal for signal named s,
 // or 0 if a signal with such name is not found.
 // The signal name should start with "SIG".
 func SignalNum(s string) syscall.Signal {
 	signalNameMapOnce.Do(func() {
 		signalNameMap = make(map[string]syscall.Signal)
 		for _, signal := range signalList {
 			signalNameMap[signal.name] = signal.num
 		}
 	})
 	return signalNameMap[s]
 }

 // clen returns the index of the first NULL byte in n or len(n) if n contains no NULL byte.
 func clen(n []byte) int {
 	i := bytes.IndexByte(n, 0)
 	if i == -1 {
 		i = len(n)
 	}
 	return i
 }

 // Mmap manager, for use by operating system-specific implementations.

 type mmapper struct {
 	sync.Mutex
 	active map[*byte][]byte // active mappings; key is last byte in mapping
 	mmap   func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, error)
 	munmap func(addr uintptr, length uintptr) error
 }

 func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
 	if length <= 0 {
 		return nil, EINVAL
 	}

 	// Map the requested memory.
 	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
 	if errno != nil {
 		return nil, errno
 	}

 	// Slice memory layout
 	var sl = struct {
 		addr uintptr
 		len  int
 		cap  int
 	}{addr, length, length}

 	// Use unsafe to turn sl into a []byte.
 	b := *(*[]byte)(unsafe.Pointer(&sl))

 	// Register mapping in m and return it.
 	p := &b[cap(b)-1]
 	m.Lock()
 	defer m.Unlock()
 	m.active[p] = b
 	return b, nil
 }

 func (m *mmapper) Munmap(data []byte) (err error) {
 	if len(data) == 0 || len(data) != cap(data) {
 		return EINVAL
 	}

 	// Find the base of the mapping.
 	p := &data[cap(data)-1]
 	m.Lock()
 	defer m.Unlock()
 	b := m.active[p]
 	if b == nil || &b[0] != &data[0] {
 		return EINVAL
 	}

 	// Unmap the memory and update m.
 	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != nil {
 		return errno
 	}
 	delete(m.active, p)
 	return nil
 }

 func Read(fd int, p []byte) (n int, err error) {
 	n, err = read(fd, p)
 	if raceenabled {
 		if n > 0 {
 			raceWriteRange(unsafe.Pointer(&p[0]), n)
 		}
 		if err == nil {
 			raceAcquire(unsafe.Pointer(&ioSync))
 		}
 	}
 	return
 }

 func Write(fd int, p []byte) (n int, err error) {
 	if raceenabled {
 		raceReleaseMerge(unsafe.Pointer(&ioSync))
 	}
 	n, err = write(fd, p)
 	if raceenabled && n > 0 {
 		raceReadRange(unsafe.Pointer(&p[0]), n)
 	}
 	return
 }

 // For testing: clients can set this flag to force
 // creation of IPv6 sockets to return EAFNOSUPPORT.
 var SocketDisableIPv6 bool

 // Sockaddr represents a socket address.
 type Sockaddr interface {
 	sockaddr() (ptr unsafe.Pointer, len _Socklen, err error) // lowercase; only we can define Sockaddrs
 }

 // SockaddrInet4 implements the Sockaddr interface for AF_INET type sockets.
 type SockaddrInet4 struct {
 	Port int
 	Addr [4]byte
 	raw  RawSockaddrInet4
 }

 // SockaddrInet6 implements the Sockaddr interface for AF_INET6 type sockets.
 type SockaddrInet6 struct {
 	Port   int
 	ZoneId uint32
 	Addr   [16]byte
 	raw    RawSockaddrInet6
 }

 // SockaddrUnix implements the Sockaddr interface for AF_UNIX type sockets.
 type SockaddrUnix struct {
 	Name string
 	raw  RawSockaddrUnix
 }

 func Bind(fd int, sa Sockaddr) (err error) {
 	ptr, n, err := sa.sockaddr()
 	if err != nil {
 		return err
 	}
 	return bind(fd, ptr, n)
 }

 func Connect(fd int, sa Sockaddr) (err error) {
 	ptr, n, err := sa.sockaddr()
 	if err != nil {
 		return err
 	}
 	return connect(fd, ptr, n)
 }

 func Getpeername(fd int) (sa Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	var len _Socklen = SizeofSockaddrAny
 	if err = getpeername(fd, &rsa, &len); err != nil {
 		return
 	}
 	return anyToSockaddr(fd, &rsa)
 }

 func GetsockoptByte(fd, level, opt int) (value byte, err error) {
 	var n byte
 	vallen := _Socklen(1)
 	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
 	return n, err
 }

 func GetsockoptInt(fd, level, opt int) (value int, err error) {
 	var n int32
 	vallen := _Socklen(4)
 	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
 	return int(n), err
 }

 func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
 	vallen := _Socklen(4)
 	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
 	return value, err
 }

 func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
 	var value IPMreq
 	vallen := _Socklen(SizeofIPMreq)
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
 	return &value, err
 }

 func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
 	var value IPv6Mreq
 	vallen := _Socklen(SizeofIPv6Mreq)
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
 	return &value, err
 }

 func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
 	var value IPv6MTUInfo
 	vallen := _Socklen(SizeofIPv6MTUInfo)
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
 	return &value, err
 }

 func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
 	var value ICMPv6Filter
 	vallen := _Socklen(SizeofICMPv6Filter)
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
 	return &value, err
 }

 func GetsockoptLinger(fd, level, opt int) (*Linger, error) {
 	var linger Linger
 	vallen := _Socklen(SizeofLinger)
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&linger), &vallen)
 	return &linger, err
 }

 func GetsockoptTimeval(fd, level, opt int) (*Timeval, error) {
 	var tv Timeval
 	vallen := _Socklen(unsafe.Sizeof(tv))
 	err := getsockopt(fd, level, opt, unsafe.Pointer(&tv), &vallen)
 	return &tv, err
 }

 func GetsockoptUint64(fd, level, opt int) (value uint64, err error) {
 	var n uint64
 	vallen := _Socklen(8)
 	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
 	return n, err
 }

 func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	var len _Socklen = SizeofSockaddrAny
 	if n, err = recvfrom(fd, p, flags, &rsa, &len); err != nil {
 		return
 	}
 	if rsa.Addr.Family != AF_UNSPEC {
 		from, err = anyToSockaddr(fd, &rsa)
 	}
 	return
 }

 func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
 	ptr, n, err := to.sockaddr()
 	if err != nil {
 		return err
 	}
 	return sendto(fd, p, flags, ptr, n)
 }

 func SetsockoptByte(fd, level, opt int, value byte) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 1)
 }

 func SetsockoptInt(fd, level, opt int, value int) (err error) {
 	var n = int32(value)
 	return setsockopt(fd, level, opt, unsafe.Pointer(&n), 4)
 }

 func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&value[0]), 4)
 }

 func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPMreq)
 }

 func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPv6Mreq)
 }

 func SetsockoptICMPv6Filter(fd, level, opt int, filter *ICMPv6Filter) error {
 	return setsockopt(fd, level, opt, unsafe.Pointer(filter), SizeofICMPv6Filter)
 }

 func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(l), SizeofLinger)
 }

 func SetsockoptString(fd, level, opt int, s string) (err error) {
 	var p unsafe.Pointer
 	if len(s) > 0 {
 		p = unsafe.Pointer(&[]byte(s)[0])
 	}
 	return setsockopt(fd, level, opt, p, uintptr(len(s)))
 }

 func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(tv), unsafe.Sizeof(*tv))
 }

 func SetsockoptUint64(fd, level, opt int, value uint64) (err error) {
 	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 8)
 }

 func Socket(domain, typ, proto int) (fd int, err error) {
 	if domain == AF_INET6 && SocketDisableIPv6 {
 		return -1, EAFNOSUPPORT
 	}
 	fd, err = socket(domain, typ, proto)
 	return
 }

 func Socketpair(domain, typ, proto int) (fd [2]int, err error) {
 	var fdx [2]int32
 	err = socketpair(domain, typ, proto, &fdx)
 	if err == nil {
 		fd[0] = int(fdx[0])
 		fd[1] = int(fdx[1])
 	}
 	return
 }

 var ioSync int64

 func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }

 func SetNonblock(fd int, nonblocking bool) (err error) {
 	flag, err := fcntl(fd, F_GETFL, 0)
 	if err != nil {
 		return err
 	}
 	if nonblocking {
 		flag |= O_NONBLOCK
 	} else {
 		flag &= ^O_NONBLOCK
 	}
 	_, err = fcntl(fd, F_SETFL, flag)
 	return err
 }

 // Exec calls execve(2), which replaces the calling executable in the process
 // tree. argv0 should be the full path to an executable ("/bin/ls") and the
 // executable name should also be the first argument in argv (["ls", "-l"]).
 // envv are the environment variables that should be passed to the new
 // process (["USER=go", "PWD=/tmp"]).
 func Exec(argv0 string, argv []string, envv []string) error {
 	return syscall.Exec(argv0, argv, envv)
 }

 // Lutimes sets the access and modification times tv on path. If path refers to
 // a symlink, it is not dereferenced and the timestamps are set on the symlink.
 // If tv is nil, the access and modification times are set to the current time.
 // Otherwise tv must contain exactly 2 elements, with access time as the first
 // element and modification time as the second element.
 func Lutimes(path string, tv []Timeval) error {
 	if tv == nil {
 		return UtimesNanoAt(AT_FDCWD, path, nil, AT_SYMLINK_NOFOLLOW)
 	}
 	if len(tv) != 2 {
 		return EINVAL
 	}
 	ts := []Timespec{
 		NsecToTimespec(TimevalToNsec(tv[0])),
 		NsecToTimespec(TimevalToNsec(tv[1])),
 	}
 	return UtimesNanoAt(AT_FDCWD, path, ts, AT_SYMLINK_NOFOLLOW)
 }
	// Copyright 2009 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 aix darwin dragonfly freebsd linux netbsd openbsd solaris

	package unix

	import (
	"bytes"
	"sort"
	"sync"
	"syscall"
	"unsafe"
	)

	var (
	Stdin = 0
	Stdout = 1
	Stderr = 2
	)

	// Do the interface allocations only once for common
	// Errno values.
	var (
	errEAGAIN error = syscall.EAGAIN
	errEINVAL error = syscall.EINVAL
	errENOENT error = syscall.ENOENT
	)

	var (
	signalNameMapOnce sync.Once
	signalNameMap map[string]syscall.Signal
	)

	// errnoErr returns common boxed Errno values, to prevent
	// allocations at runtime.
	func errnoErr(e syscall.Errno) error {
	switch e {
	case 0:
	return nil
	case EAGAIN:
	return errEAGAIN
	case EINVAL:
	return errEINVAL
	case ENOENT:
	return errENOENT
	}
	return e
	}

	// ErrnoName returns the error name for error number e.
	func ErrnoName(e syscall.Errno) string {
	i := sort.Search(len(errorList), func(i int) bool {
	return errorList[i].num >= e
	})
	if i < len(errorList) && errorList[i].num == e {
	return errorList[i].name
	}
	return ""
	}

	// SignalName returns the signal name for signal number s.
	func SignalName(s syscall.Signal) string {
	i := sort.Search(len(signalList), func(i int) bool {
	return signalList[i].num >= s
	})
	if i < len(signalList) && signalList[i].num == s {
	return signalList[i].name
	}
	return ""
	}

	// SignalNum returns the syscall.Signal for signal named s,
	// or 0 if a signal with such name is not found.
	// The signal name should start with "SIG".
	func SignalNum(s string) syscall.Signal {
	signalNameMapOnce.Do(func() {
	signalNameMap = make(map[string]syscall.Signal)
	for _, signal := range signalList {
	signalNameMap[signal.name] = signal.num
	}
	})
	return signalNameMap[s]
	}

	// clen returns the index of the first NULL byte in n or len(n) if n contains no NULL byte.
	func clen(n []byte) int {
	i := bytes.IndexByte(n, 0)
	if i == -1 {
	i = len(n)
	}
	return i
	}

	// Mmap manager, for use by operating system-specific implementations.

	type mmapper struct {
	sync.Mutex
	active map[*byte][]byte // active mappings; key is last byte in mapping
	mmap func(addr, length uintptr, prot, flags, fd int, offset int64) (uintptr, error)
	munmap func(addr uintptr, length uintptr) error
	}

	func (m *mmapper) Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
	if length <= 0 {
	return nil, EINVAL
	}

	// Map the requested memory.
	addr, errno := m.mmap(0, uintptr(length), prot, flags, fd, offset)
	if errno != nil {
	return nil, errno
	}

	// Slice memory layout
	var sl = struct {
	addr uintptr
	len int
	cap int
	}{addr, length, length}

	// Use unsafe to turn sl into a []byte.
	b := ([]byte)(unsafe.Pointer(&sl))

	// Register mapping in m and return it.
	p := &b[cap(b)-1]
	m.Lock()
	defer m.Unlock()
	m.active[p] = b
	return b, nil
	}

	func (m *mmapper) Munmap(data []byte) (err error) {
	if len(data) == 0 \|\| len(data) != cap(data) {
	return EINVAL
	}

	// Find the base of the mapping.
	p := &data[cap(data)-1]
	m.Lock()
	defer m.Unlock()
	b := m.active[p]
	if b == nil \|\| &b[0] != &data[0] {
	return EINVAL
	}

	// Unmap the memory and update m.
	if errno := m.munmap(uintptr(unsafe.Pointer(&b[0])), uintptr(len(b))); errno != nil {
	return errno
	}
	delete(m.active, p)
	return nil
	}

	func Read(fd int, p []byte) (n int, err error) {
	n, err = read(fd, p)
	if raceenabled {
	if n > 0 {
	raceWriteRange(unsafe.Pointer(&p[0]), n)
	}
	if err == nil {
	raceAcquire(unsafe.Pointer(&ioSync))
	}
	}
	return
	}

	func Write(fd int, p []byte) (n int, err error) {
	if raceenabled {
	raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	n, err = write(fd, p)
	if raceenabled && n > 0 {
	raceReadRange(unsafe.Pointer(&p[0]), n)
	}
	return
	}

	// For testing: clients can set this flag to force
	// creation of IPv6 sockets to return EAFNOSUPPORT.
	var SocketDisableIPv6 bool

	// Sockaddr represents a socket address.
	type Sockaddr interface {
	sockaddr() (ptr unsafe.Pointer, len _Socklen, err error) // lowercase; only we can define Sockaddrs
	}

	// SockaddrInet4 implements the Sockaddr interface for AF_INET type sockets.
	type SockaddrInet4 struct {
	Port int
	Addr [4]byte
	raw RawSockaddrInet4
	}

	// SockaddrInet6 implements the Sockaddr interface for AF_INET6 type sockets.
	type SockaddrInet6 struct {
	Port int
	ZoneId uint32
	Addr [16]byte
	raw RawSockaddrInet6
	}

	// SockaddrUnix implements the Sockaddr interface for AF_UNIX type sockets.
	type SockaddrUnix struct {
	Name string
	raw RawSockaddrUnix
	}

	func Bind(fd int, sa Sockaddr) (err error) {
	ptr, n, err := sa.sockaddr()
	if err != nil {
	return err
	}
	return bind(fd, ptr, n)
	}

	func Connect(fd int, sa Sockaddr) (err error) {
	ptr, n, err := sa.sockaddr()
	if err != nil {
	return err
	}
	return connect(fd, ptr, n)
	}

	func Getpeername(fd int) (sa Sockaddr, err error) {
	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	if err = getpeername(fd, &rsa, &len); err != nil {
	return
	}
	return anyToSockaddr(fd, &rsa)
	}

	func GetsockoptByte(fd, level, opt int) (value byte, err error) {
	var n byte
	vallen := _Socklen(1)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return n, err
	}

	func GetsockoptInt(fd, level, opt int) (value int, err error) {
	var n int32
	vallen := _Socklen(4)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return int(n), err
	}

	func GetsockoptInet4Addr(fd, level, opt int) (value [4]byte, err error) {
	vallen := _Socklen(4)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&value[0]), &vallen)
	return value, err
	}

	func GetsockoptIPMreq(fd, level, opt int) (*IPMreq, error) {
	var value IPMreq
	vallen := _Socklen(SizeofIPMreq)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
	}

	func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
	var value IPv6Mreq
	vallen := _Socklen(SizeofIPv6Mreq)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
	}

	func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
	var value IPv6MTUInfo
	vallen := _Socklen(SizeofIPv6MTUInfo)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
	}

	func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
	var value ICMPv6Filter
	vallen := _Socklen(SizeofICMPv6Filter)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
	}

	func GetsockoptLinger(fd, level, opt int) (*Linger, error) {
	var linger Linger
	vallen := _Socklen(SizeofLinger)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&linger), &vallen)
	return &linger, err
	}

	func GetsockoptTimeval(fd, level, opt int) (*Timeval, error) {
	var tv Timeval
	vallen := _Socklen(unsafe.Sizeof(tv))
	err := getsockopt(fd, level, opt, unsafe.Pointer(&tv), &vallen)
	return &tv, err
	}

	func GetsockoptUint64(fd, level, opt int) (value uint64, err error) {
	var n uint64
	vallen := _Socklen(8)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return n, err
	}

	func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	if n, err = recvfrom(fd, p, flags, &rsa, &len); err != nil {
	return
	}
	if rsa.Addr.Family != AF_UNSPEC {
	from, err = anyToSockaddr(fd, &rsa)
	}
	return
	}

	func Sendto(fd int, p []byte, flags int, to Sockaddr) (err error) {
	ptr, n, err := to.sockaddr()
	if err != nil {
	return err
	}
	return sendto(fd, p, flags, ptr, n)
	}

	func SetsockoptByte(fd, level, opt int, value byte) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 1)
	}

	func SetsockoptInt(fd, level, opt int, value int) (err error) {
	var n = int32(value)
	return setsockopt(fd, level, opt, unsafe.Pointer(&n), 4)
	}

	func SetsockoptInet4Addr(fd, level, opt int, value [4]byte) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(&value[0]), 4)
	}

	func SetsockoptIPMreq(fd, level, opt int, mreq *IPMreq) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPMreq)
	}

	func SetsockoptIPv6Mreq(fd, level, opt int, mreq *IPv6Mreq) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), SizeofIPv6Mreq)
	}

	func SetsockoptICMPv6Filter(fd, level, opt int, filter *ICMPv6Filter) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(filter), SizeofICMPv6Filter)
	}

	func SetsockoptLinger(fd, level, opt int, l *Linger) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(l), SizeofLinger)
	}

	func SetsockoptString(fd, level, opt int, s string) (err error) {
	var p unsafe.Pointer
	if len(s) > 0 {
	p = unsafe.Pointer(&[]byte(s)[0])
	}
	return setsockopt(fd, level, opt, p, uintptr(len(s)))
	}

	func SetsockoptTimeval(fd, level, opt int, tv *Timeval) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(tv), unsafe.Sizeof(*tv))
	}

	func SetsockoptUint64(fd, level, opt int, value uint64) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(&value), 8)
	}

	func Socket(domain, typ, proto int) (fd int, err error) {
	if domain == AF_INET6 && SocketDisableIPv6 {
	return -1, EAFNOSUPPORT
	}
	fd, err = socket(domain, typ, proto)
	return
	}

	func Socketpair(domain, typ, proto int) (fd [2]int, err error) {
	var fdx [2]int32
	err = socketpair(domain, typ, proto, &fdx)
	if err == nil {
	fd[0] = int(fdx[0])
	fd[1] = int(fdx[1])
	}
	return
	}

	var ioSync int64

	func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }

	func SetNonblock(fd int, nonblocking bool) (err error) {
	flag, err := fcntl(fd, F_GETFL, 0)
	if err != nil {
	return err
	}
	if nonblocking {
	flag \|= O_NONBLOCK
	} else {
	flag &= ^O_NONBLOCK
	}
	_, err = fcntl(fd, F_SETFL, flag)
	return err
	}

	// Exec calls execve(2), which replaces the calling executable in the process
	// tree. argv0 should be the full path to an executable ("/bin/ls") and the
	// executable name should also be the first argument in argv (["ls", "-l"]).
	// envv are the environment variables that should be passed to the new
	// process (["USER=go", "PWD=/tmp"]).
	func Exec(argv0 string, argv []string, envv []string) error {
	return syscall.Exec(argv0, argv, envv)
	}

	// Lutimes sets the access and modification times tv on path. If path refers to
	// a symlink, it is not dereferenced and the timestamps are set on the symlink.
	// If tv is nil, the access and modification times are set to the current time.
	// Otherwise tv must contain exactly 2 elements, with access time as the first
	// element and modification time as the second element.
	func Lutimes(path string, tv []Timeval) error {
	if tv == nil {
	return UtimesNanoAt(AT_FDCWD, path, nil, AT_SYMLINK_NOFOLLOW)
	}
	if len(tv) != 2 {
	return EINVAL
	}
	ts := []Timespec{
	NsecToTimespec(TimevalToNsec(tv[0])),
	NsecToTimespec(TimevalToNsec(tv[1])),
	}
	return UtimesNanoAt(AT_FDCWD, path, ts, AT_SYMLINK_NOFOLLOW)
	}