text: // 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 darwin dragonfly freebsd netbsd openbsd
  
  // BSD system call wrappers shared by *BSD based systems
  // including OS X (Darwin) and FreeBSD.  Like the other
  // syscall_*.go files it is compiled as Go code but also
  // used as input to mksyscall which parses the //sys
  // lines and generates system call stubs.
  
  package unix
  
  import (
  	"runtime"
  	"syscall"
  	"unsafe"
  )
  
  /*
   * Wrapped
   */
  
  //sysnb	getgroups(ngid int, gid *_Gid_t) (n int, err error)
  //sysnb	setgroups(ngid int, gid *_Gid_t) (err error)
  
  func Getgroups() (gids []int, err error) {
  	n, err := getgroups(0, nil)
  	if err != nil {
  		return nil, err
  	}
  	if n == 0 {
  		return nil, nil
  	}
  
  	// Sanity check group count. Max is 16 on BSD.
  	if n < 0 || n > 1000 {
  		return nil, EINVAL
  	}
  
  	a := make([]_Gid_t, n)
  	n, err = getgroups(n, &a[0])
  	if err != nil {
  		return nil, err
  	}
  	gids = make([]int, n)
  	for i, v := range a[0:n] {
  		gids[i] = int(v)
  	}
  	return
  }
  
  func Setgroups(gids []int) (err error) {
  	if len(gids) == 0 {
  		return setgroups(0, nil)
  	}
  
  	a := make([]_Gid_t, len(gids))
  	for i, v := range gids {
  		a[i] = _Gid_t(v)
  	}
  	return setgroups(len(a), &a[0])
  }
  
  // Wait status is 7 bits at bottom, either 0 (exited),
  // 0x7F (stopped), or a signal number that caused an exit.
  // The 0x80 bit is whether there was a core dump.
  // An extra number (exit code, signal causing a stop)
  // is in the high bits.
  
  type WaitStatus uint32
  
  const (
  	mask  = 0x7F
  	core  = 0x80
  	shift = 8
  
  	exited  = 0
  	killed  = 9
  	stopped = 0x7F
  )
  
  func (w WaitStatus) Exited() bool { return w&mask == exited }
  
  func (w WaitStatus) ExitStatus() int {
  	if w&mask != exited {
  		return -1
  	}
  	return int(w >> shift)
  }
  
  func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != 0 }
  
  func (w WaitStatus) Signal() syscall.Signal {
  	sig := syscall.Signal(w & mask)
  	if sig == stopped || sig == 0 {
  		return -1
  	}
  	return sig
  }
  
  func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }
  
  func (w WaitStatus) Stopped() bool { return w&mask == stopped && syscall.Signal(w>>shift) != SIGSTOP }
  
  func (w WaitStatus) Killed() bool { return w&mask == killed && syscall.Signal(w>>shift) != SIGKILL }
  
  func (w WaitStatus) Continued() bool { return w&mask == stopped && syscall.Signal(w>>shift) == SIGSTOP }
  
  func (w WaitStatus) StopSignal() syscall.Signal {
  	if !w.Stopped() {
  		return -1
  	}
  	return syscall.Signal(w>>shift) & 0xFF
  }
  
  func (w WaitStatus) TrapCause() int { return -1 }
  
  //sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)
  
  func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
  	var status _C_int
  	wpid, err = wait4(pid, &status, options, rusage)
  	if wstatus != nil {
  		*wstatus = WaitStatus(status)
  	}
  	return
  }
  
  //sys	accept(s int, rsa *RawSockaddrAny, addrlen *_Socklen) (fd int, err error)
  //sys	bind(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
  //sys	connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error)
  //sysnb	socket(domain int, typ int, proto int) (fd int, err error)
  //sys	getsockopt(s int, level int, name int, val unsafe.Pointer, vallen *_Socklen) (err error)
  //sys	setsockopt(s int, level int, name int, val unsafe.Pointer, vallen uintptr) (err error)
  //sysnb	getpeername(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
  //sysnb	getsockname(fd int, rsa *RawSockaddrAny, addrlen *_Socklen) (err error)
  //sys	Shutdown(s int, how int) (err error)
  
  func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
  	if sa.Port < 0 || sa.Port > 0xFFFF {
  		return nil, 0, EINVAL
  	}
  	sa.raw.Len = SizeofSockaddrInet4
  	sa.raw.Family = AF_INET
  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
  	p[0] = byte(sa.Port >> 8)
  	p[1] = byte(sa.Port)
  	for i := 0; i < len(sa.Addr); i++ {
  		sa.raw.Addr[i] = sa.Addr[i]
  	}
  	return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
  }
  
  func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
  	if sa.Port < 0 || sa.Port > 0xFFFF {
  		return nil, 0, EINVAL
  	}
  	sa.raw.Len = SizeofSockaddrInet6
  	sa.raw.Family = AF_INET6
  	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
  	p[0] = byte(sa.Port >> 8)
  	p[1] = byte(sa.Port)
  	sa.raw.Scope_id = sa.ZoneId
  	for i := 0; i < len(sa.Addr); i++ {
  		sa.raw.Addr[i] = sa.Addr[i]
  	}
  	return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
  }
  
  func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
  	name := sa.Name
  	n := len(name)
  	if n >= len(sa.raw.Path) || n == 0 {
  		return nil, 0, EINVAL
  	}
  	sa.raw.Len = byte(3 + n) // 2 for Family, Len; 1 for NUL
  	sa.raw.Family = AF_UNIX
  	for i := 0; i < n; i++ {
  		sa.raw.Path[i] = int8(name[i])
  	}
  	return unsafe.Pointer(&sa.raw), _Socklen(sa.raw.Len), nil
  }
  
  func (sa *SockaddrDatalink) sockaddr() (unsafe.Pointer, _Socklen, error) {
  	if sa.Index == 0 {
  		return nil, 0, EINVAL
  	}
  	sa.raw.Len = sa.Len
  	sa.raw.Family = AF_LINK
  	sa.raw.Index = sa.Index
  	sa.raw.Type = sa.Type
  	sa.raw.Nlen = sa.Nlen
  	sa.raw.Alen = sa.Alen
  	sa.raw.Slen = sa.Slen
  	for i := 0; i < len(sa.raw.Data); i++ {
  		sa.raw.Data[i] = sa.Data[i]
  	}
  	return unsafe.Pointer(&sa.raw), SizeofSockaddrDatalink, nil
  }
  
  func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
  	switch rsa.Addr.Family {
  	case AF_LINK:
  		pp := (*RawSockaddrDatalink)(unsafe.Pointer(rsa))
  		sa := new(SockaddrDatalink)
  		sa.Len = pp.Len
  		sa.Family = pp.Family
  		sa.Index = pp.Index
  		sa.Type = pp.Type
  		sa.Nlen = pp.Nlen
  		sa.Alen = pp.Alen
  		sa.Slen = pp.Slen
  		for i := 0; i < len(sa.Data); i++ {
  			sa.Data[i] = pp.Data[i]
  		}
  		return sa, nil
  
  	case AF_UNIX:
  		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
  		if pp.Len < 2 || pp.Len > SizeofSockaddrUnix {
  			return nil, EINVAL
  		}
  		sa := new(SockaddrUnix)
  
  		// Some BSDs include the trailing NUL in the length, whereas
  		// others do not. Work around this by subtracting the leading
  		// family and len. The path is then scanned to see if a NUL
  		// terminator still exists within the length.
  		n := int(pp.Len) - 2 // subtract leading Family, Len
  		for i := 0; i < n; i++ {
  			if pp.Path[i] == 0 {
  				// found early NUL; assume Len included the NUL
  				// or was overestimating.
  				n = i
  				break
  			}
  		}
  		bytes := (*[len(pp.Path)]byte)(unsafe.Pointer(&pp.Path[0]))[0:n]
  		sa.Name = string(bytes)
  		return sa, nil
  
  	case AF_INET:
  		pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
  		sa := new(SockaddrInet4)
  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  		sa.Port = int(p[0])<<8 + int(p[1])
  		for i := 0; i < len(sa.Addr); i++ {
  			sa.Addr[i] = pp.Addr[i]
  		}
  		return sa, nil
  
  	case AF_INET6:
  		pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
  		sa := new(SockaddrInet6)
  		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
  		sa.Port = int(p[0])<<8 + int(p[1])
  		sa.ZoneId = pp.Scope_id
  		for i := 0; i < len(sa.Addr); i++ {
  			sa.Addr[i] = pp.Addr[i]
  		}
  		return sa, nil
  	}
  	return nil, EAFNOSUPPORT
  }
  
  func Accept(fd int) (nfd int, sa Sockaddr, err error) {
  	var rsa RawSockaddrAny
  	var len _Socklen = SizeofSockaddrAny
  	nfd, err = accept(fd, &rsa, &len)
  	if err != nil {
  		return
  	}
  	if runtime.GOOS == "darwin" && len == 0 {
  		// Accepted socket has no address.
  		// This is likely due to a bug in xnu kernels,
  		// where instead of ECONNABORTED error socket
  		// is accepted, but has no address.
  		Close(nfd)
  		return 0, nil, ECONNABORTED
  	}
  	sa, err = anyToSockaddr(fd, &rsa)
  	if err != nil {
  		Close(nfd)
  		nfd = 0
  	}
  	return
  }
  
  func Getsockname(fd int) (sa Sockaddr, err error) {
  	var rsa RawSockaddrAny
  	var len _Socklen = SizeofSockaddrAny
  	if err = getsockname(fd, &rsa, &len); err != nil {
  		return
  	}
  	// TODO(jsing): DragonFly has a "bug" (see issue 3349), which should be
  	// reported upstream.
  	if runtime.GOOS == "dragonfly" && rsa.Addr.Family == AF_UNSPEC && rsa.Addr.Len == 0 {
  		rsa.Addr.Family = AF_UNIX
  		rsa.Addr.Len = SizeofSockaddrUnix
  	}
  	return anyToSockaddr(fd, &rsa)
  }
  
  //sysnb socketpair(domain int, typ int, proto int, fd *[2]int32) (err error)
  
  // GetsockoptString returns the string value of the socket option opt for the
  // socket associated with fd at the given socket level.
  func GetsockoptString(fd, level, opt int) (string, error) {
  	buf := make([]byte, 256)
  	vallen := _Socklen(len(buf))
  	err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
  	if err != nil {
  		return "", err
  	}
  	return string(buf[:vallen-1]), nil
  }
  
  //sys   recvfrom(fd int, p []byte, flags int, from *RawSockaddrAny, fromlen *_Socklen) (n int, err error)
  //sys   sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error)
  //sys	recvmsg(s int, msg *Msghdr, flags int) (n int, err error)
  
  func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
  	var msg Msghdr
  	var rsa RawSockaddrAny
  	msg.Name = (*byte)(unsafe.Pointer(&rsa))
  	msg.Namelen = uint32(SizeofSockaddrAny)
  	var iov Iovec
  	if len(p) > 0 {
  		iov.Base = (*byte)(unsafe.Pointer(&p[0]))
  		iov.SetLen(len(p))
  	}
  	var dummy byte
  	if len(oob) > 0 {
  		// receive at least one normal byte
  		if len(p) == 0 {
  			iov.Base = &dummy
  			iov.SetLen(1)
  		}
  		msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
  		msg.SetControllen(len(oob))
  	}
  	msg.Iov = &iov
  	msg.Iovlen = 1
  	if n, err = recvmsg(fd, &msg, flags); err != nil {
  		return
  	}
  	oobn = int(msg.Controllen)
  	recvflags = int(msg.Flags)
  	// source address is only specified if the socket is unconnected
  	if rsa.Addr.Family != AF_UNSPEC {
  		from, err = anyToSockaddr(fd, &rsa)
  	}
  	return
  }
  
  //sys	sendmsg(s int, msg *Msghdr, flags int) (n int, err error)
  
  func Sendmsg(fd int, p, oob []byte, to Sockaddr, flags int) (err error) {
  	_, err = SendmsgN(fd, p, oob, to, flags)
  	return
  }
  
  func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error) {
  	var ptr unsafe.Pointer
  	var salen _Socklen
  	if to != nil {
  		ptr, salen, err = to.sockaddr()
  		if err != nil {
  			return 0, err
  		}
  	}
  	var msg Msghdr
  	msg.Name = (*byte)(unsafe.Pointer(ptr))
  	msg.Namelen = uint32(salen)
  	var iov Iovec
  	if len(p) > 0 {
  		iov.Base = (*byte)(unsafe.Pointer(&p[0]))
  		iov.SetLen(len(p))
  	}
  	var dummy byte
  	if len(oob) > 0 {
  		// send at least one normal byte
  		if len(p) == 0 {
  			iov.Base = &dummy
  			iov.SetLen(1)
  		}
  		msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
  		msg.SetControllen(len(oob))
  	}
  	msg.Iov = &iov
  	msg.Iovlen = 1
  	if n, err = sendmsg(fd, &msg, flags); err != nil {
  		return 0, err
  	}
  	if len(oob) > 0 && len(p) == 0 {
  		n = 0
  	}
  	return n, nil
  }
  
  //sys	kevent(kq int, change unsafe.Pointer, nchange int, event unsafe.Pointer, nevent int, timeout *Timespec) (n int, err error)
  
  func Kevent(kq int, changes, events []Kevent_t, timeout *Timespec) (n int, err error) {
  	var change, event unsafe.Pointer
  	if len(changes) > 0 {
  		change = unsafe.Pointer(&changes[0])
  	}
  	if len(events) > 0 {
  		event = unsafe.Pointer(&events[0])
  	}
  	return kevent(kq, change, len(changes), event, len(events), timeout)
  }
  
  // sysctlmib translates name to mib number and appends any additional args.
  func sysctlmib(name string, args ...int) ([]_C_int, error) {
  	// Translate name to mib number.
  	mib, err := nametomib(name)
  	if err != nil {
  		return nil, err
  	}
  
  	for _, a := range args {
  		mib = append(mib, _C_int(a))
  	}
  
  	return mib, nil
  }
  
  func Sysctl(name string) (string, error) {
  	return SysctlArgs(name)
  }
  
  func SysctlArgs(name string, args ...int) (string, error) {
  	buf, err := SysctlRaw(name, args...)
  	if err != nil {
  		return "", err
  	}
  	n := len(buf)
  
  	// Throw away terminating NUL.
  	if n > 0 && buf[n-1] == '\x00' {
  		n--
  	}
  	return string(buf[0:n]), nil
  }
  
  func SysctlUint32(name string) (uint32, error) {
  	return SysctlUint32Args(name)
  }
  
  func SysctlUint32Args(name string, args ...int) (uint32, error) {
  	mib, err := sysctlmib(name, args...)
  	if err != nil {
  		return 0, err
  	}
  
  	n := uintptr(4)
  	buf := make([]byte, 4)
  	if err := sysctl(mib, &buf[0], &n, nil, 0); err != nil {
  		return 0, err
  	}
  	if n != 4 {
  		return 0, EIO
  	}
  	return *(*uint32)(unsafe.Pointer(&buf[0])), nil
  }
  
  func SysctlUint64(name string, args ...int) (uint64, error) {
  	mib, err := sysctlmib(name, args...)
  	if err != nil {
  		return 0, err
  	}
  
  	n := uintptr(8)
  	buf := make([]byte, 8)
  	if err := sysctl(mib, &buf[0], &n, nil, 0); err != nil {
  		return 0, err
  	}
  	if n != 8 {
  		return 0, EIO
  	}
  	return *(*uint64)(unsafe.Pointer(&buf[0])), nil
  }
  
  func SysctlRaw(name string, args ...int) ([]byte, error) {
  	mib, err := sysctlmib(name, args...)
  	if err != nil {
  		return nil, err
  	}
  
  	// Find size.
  	n := uintptr(0)
  	if err := sysctl(mib, nil, &n, nil, 0); err != nil {
  		return nil, err
  	}
  	if n == 0 {
  		return nil, nil
  	}
  
  	// Read into buffer of that size.
  	buf := make([]byte, n)
  	if err := sysctl(mib, &buf[0], &n, nil, 0); err != nil {
  		return nil, err
  	}
  
  	// The actual call may return less than the original reported required
  	// size so ensure we deal with that.
  	return buf[:n], nil
  }
  
  //sys	utimes(path string, timeval *[2]Timeval) (err error)
  
  func Utimes(path string, tv []Timeval) error {
  	if tv == nil {
  		return utimes(path, nil)
  	}
  	if len(tv) != 2 {
  		return EINVAL
  	}
  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
  }
  
  func UtimesNano(path string, ts []Timespec) error {
  	if ts == nil {
  		err := utimensat(AT_FDCWD, path, nil, 0)
  		if err != ENOSYS {
  			return err
  		}
  		return utimes(path, nil)
  	}
  	if len(ts) != 2 {
  		return EINVAL
  	}
  	// Darwin setattrlist can set nanosecond timestamps
  	err := setattrlistTimes(path, ts, 0)
  	if err != ENOSYS {
  		return err
  	}
  	err = utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
  	if err != ENOSYS {
  		return err
  	}
  	// Not as efficient as it could be because Timespec and
  	// Timeval have different types in the different OSes
  	tv := [2]Timeval{
  		NsecToTimeval(TimespecToNsec(ts[0])),
  		NsecToTimeval(TimespecToNsec(ts[1])),
  	}
  	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
  }
  
  func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
  	if ts == nil {
  		return utimensat(dirfd, path, nil, flags)
  	}
  	if len(ts) != 2 {
  		return EINVAL
  	}
  	err := setattrlistTimes(path, ts, flags)
  	if err != ENOSYS {
  		return err
  	}
  	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
  }
  
  //sys	futimes(fd int, timeval *[2]Timeval) (err error)
  
  func Futimes(fd int, tv []Timeval) error {
  	if tv == nil {
  		return futimes(fd, nil)
  	}
  	if len(tv) != 2 {
  		return EINVAL
  	}
  	return futimes(fd, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
  }
  
  //sys	fcntl(fd int, cmd int, arg int) (val int, err error)
  
  //sys   poll(fds *PollFd, nfds int, timeout int) (n int, err error)
  
  func Poll(fds []PollFd, timeout int) (n int, err error) {
  	if len(fds) == 0 {
  		return poll(nil, 0, timeout)
  	}
  	return poll(&fds[0], len(fds), timeout)
  }
  
  // TODO: wrap
  //	Acct(name nil-string) (err error)
  //	Gethostuuid(uuid *byte, timeout *Timespec) (err error)
  //	Ptrace(req int, pid int, addr uintptr, data int) (ret uintptr, err error)
  
  var mapper = &mmapper{
  	active: make(map[*byte][]byte),
  	mmap:   mmap,
  	munmap: munmap,
  }
  
  func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
  	return mapper.Mmap(fd, offset, length, prot, flags)
  }
  
  func Munmap(b []byte) (err error) {
  	return mapper.Munmap(b)
  }
  
  //sys	Madvise(b []byte, behav int) (err error)
  //sys	Mlock(b []byte) (err error)
  //sys	Mlockall(flags int) (err error)
  //sys	Mprotect(b []byte, prot int) (err error)
  //sys	Msync(b []byte, flags int) (err error)
  //sys	Munlock(b []byte) (err error)
  //sys	Munlockall() (err error)
  