Source: syscall_bsd.go in package golang.org/x/sys/unix

+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"
)

const ImplementsGetwd = true

func Getwd() (string, error) {
	var buf [PathMax]byte
	_, err := Getcwd(buf[0:])
	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])
}

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++ {

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 anyToSockaddrGOOS(fd, rsa)
}

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(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

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(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

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.

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
}

func SysctlClockinfo(name string) (*Clockinfo, error) {
	mib, err := sysctlmib(name)
	if err != nil {
		return nil, err
	}

	n := uintptr(SizeofClockinfo)
	var ci Clockinfo
	if err := sysctl(mib, (*byte)(unsafe.Pointer(&ci)), &n, nil, 0); err != nil {
		return nil, err
	}
	if n != SizeofClockinfo {
		return nil, EIO
	}
	return &ci, nil
}

func SysctlTimeval(name string) (*Timeval, error) {
	mib, err := sysctlmib(name)
	if err != nil {
		return nil, err
	}

	var tv Timeval
	n := uintptr(unsafe.Sizeof(tv))
	if err := sysctl(mib, (*byte)(unsafe.Pointer(&tv)), &n, nil, 0); err != nil {
		return nil, err
	}
	if n != unsafe.Sizeof(tv) {
		return nil, EIO
	}
	return &tv, 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 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)