Source: syscall_bsd.go in package syscall

+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 syscall

import (
	"runtime"
	"unsafe"
)

const ImplementsGetwd = true

func Getwd() (string, error) {
	var buf [pathMax]byte
	_, err := getcwd(buf[:])
	if err != nil {
		return "", err
	}
	n := clen(buf[:])
	if n < 1 {
		return "", EINVAL
	}
	return string(buf[:n]), nil
}

* 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])
}

Final argument is (basep *uintptr) and the syscall doesn't take nil. 64 bits should be enough. (32 bits isn't even on 386). Since the actual system call is getdirentries64, 64 is a good guess. TODO(rsc): Can we use a single global basep for all calls?

	var base = (*uintptr)(unsafe.Pointer(new(uint64)))
	return Getdirentries(fd, buf, base)
}

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
	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() Signal {
	sig := 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 && Signal(w>>shift) != SIGSTOP }

func (w WaitStatus) Continued() bool { return w&mask == stopped && Signal(w>>shift) == SIGSTOP }

func (w WaitStatus) StopSignal() Signal {
	if !w.Stopped() {
		return -1
	}
	return 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(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++ {

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
	}

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(&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(&rsa)
}

sysnb socketpair(domain int, typ int, proto int, fd *[2]int32) (err error)


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 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
}

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

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)

source address is only specified if the socket is unconnected

	if rsa.Addr.Family != AF_UNSPEC {
		from, err = anyToSockaddr(&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

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)
}

Translate name to mib number.

	mib, err := nametomib(name)
	if err != nil {
		return "", err
	}

Find size.

	n := uintptr(0)
	if err = sysctl(mib, nil, &n, nil, 0); err != nil {
		return "", err
	}
	if n == 0 {
		return "", nil
	}

Read into buffer of that size.

	buf := make([]byte, n)
	if err = sysctl(mib, &buf[0], &n, nil, 0); err != nil {
		return "", err
	}

Throw away terminating NUL.

	if n > 0 && buf[n-1] == '\x00' {
		n--
	}
	return string(buf[0:n]), nil
}

Translate name to mib number.

	mib, err := nametomib(name)
	if err != nil {
		return 0, err
	}

Read into buffer of that size.

	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
}

sys utimes(path string, timeval *[2]Timeval) (err error)


func Utimes(path string, tv []Timeval) (err error) {
	if len(tv) != 2 {
		return EINVAL
	}
	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

func UtimesNano(path string, ts []Timespec) error {
	if len(ts) != 2 {
		return EINVAL

Darwin setattrlist can set nanosecond timestamps

	err := setattrlistTimes(path, ts)
	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])))
}

sys futimes(fd int, timeval *[2]Timeval) (err error)


func Futimes(fd int, tv []Timeval) (err error) {
	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)


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)