diff --git a/vendor/golang.org/x/sys/unix/syscall_darwin.go b/vendor/golang.org/x/sys/unix/syscall_darwin.go
new file mode 100644
index 0000000..9a5a6ee
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/syscall_darwin.go
@@ -0,0 +1,667 @@
+// Copyright 2009,2010 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.
+
+// Darwin system calls.
+// This file is compiled as ordinary Go code,
+// but it is also input to mksyscall,
+// which parses the //sys lines and generates system call stubs.
+// Note that sometimes we use a lowercase //sys name and wrap
+// it in our own nicer implementation, either here or in
+// syscall_bsd.go or syscall_unix.go.
+
+package unix
+
+import (
+	"errors"
+	"syscall"
+	"unsafe"
+)
+
+const ImplementsGetwd = true
+
+func Getwd() (string, error) {
+	buf := make([]byte, 2048)
+	attrs, err := getAttrList(".", attrList{CommonAttr: attrCmnFullpath}, buf, 0)
+	if err == nil && len(attrs) == 1 && len(attrs[0]) >= 2 {
+		wd := string(attrs[0])
+		// Sanity check that it's an absolute path and ends
+		// in a null byte, which we then strip.
+		if wd[0] == '/' && wd[len(wd)-1] == 0 {
+			return wd[:len(wd)-1], nil
+		}
+	}
+	// If pkg/os/getwd.go gets ENOTSUP, it will fall back to the
+	// slow algorithm.
+	return "", ENOTSUP
+}
+
+// SockaddrDatalink implements the Sockaddr interface for AF_LINK type sockets.
+type SockaddrDatalink struct {
+	Len    uint8
+	Family uint8
+	Index  uint16
+	Type   uint8
+	Nlen   uint8
+	Alen   uint8
+	Slen   uint8
+	Data   [12]int8
+	raw    RawSockaddrDatalink
+}
+
+// Translate "kern.hostname" to []_C_int{0,1,2,3}.
+func nametomib(name string) (mib []_C_int, err error) {
+	const siz = unsafe.Sizeof(mib[0])
+
+	// NOTE(rsc): It seems strange to set the buffer to have
+	// size CTL_MAXNAME+2 but use only CTL_MAXNAME
+	// as the size. I don't know why the +2 is here, but the
+	// kernel uses +2 for its own implementation of this function.
+	// I am scared that if we don't include the +2 here, the kernel
+	// will silently write 2 words farther than we specify
+	// and we'll get memory corruption.
+	var buf [CTL_MAXNAME + 2]_C_int
+	n := uintptr(CTL_MAXNAME) * siz
+
+	p := (*byte)(unsafe.Pointer(&buf[0]))
+	bytes, err := ByteSliceFromString(name)
+	if err != nil {
+		return nil, err
+	}
+
+	// Magic sysctl: "setting" 0.3 to a string name
+	// lets you read back the array of integers form.
+	if err = sysctl([]_C_int{0, 3}, p, &n, &bytes[0], uintptr(len(name))); err != nil {
+		return nil, err
+	}
+	return buf[0 : n/siz], nil
+}
+
+func direntIno(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
+}
+
+func direntReclen(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
+}
+
+func direntNamlen(buf []byte) (uint64, bool) {
+	return readInt(buf, unsafe.Offsetof(Dirent{}.Namlen), unsafe.Sizeof(Dirent{}.Namlen))
+}
+
+func PtraceAttach(pid int) (err error) { return ptrace(PT_ATTACH, pid, 0, 0) }
+func PtraceDetach(pid int) (err error) { return ptrace(PT_DETACH, pid, 0, 0) }
+
+const (
+	attrBitMapCount = 5
+	attrCmnFullpath = 0x08000000
+)
+
+type attrList struct {
+	bitmapCount uint16
+	_           uint16
+	CommonAttr  uint32
+	VolAttr     uint32
+	DirAttr     uint32
+	FileAttr    uint32
+	Forkattr    uint32
+}
+
+func getAttrList(path string, attrList attrList, attrBuf []byte, options uint) (attrs [][]byte, err error) {
+	if len(attrBuf) < 4 {
+		return nil, errors.New("attrBuf too small")
+	}
+	attrList.bitmapCount = attrBitMapCount
+
+	var _p0 *byte
+	_p0, err = BytePtrFromString(path)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := getattrlist(_p0, unsafe.Pointer(&attrList), unsafe.Pointer(&attrBuf[0]), uintptr(len(attrBuf)), int(options)); err != nil {
+		return nil, err
+	}
+	size := *(*uint32)(unsafe.Pointer(&attrBuf[0]))
+
+	// dat is the section of attrBuf that contains valid data,
+	// without the 4 byte length header. All attribute offsets
+	// are relative to dat.
+	dat := attrBuf
+	if int(size) < len(attrBuf) {
+		dat = dat[:size]
+	}
+	dat = dat[4:] // remove length prefix
+
+	for i := uint32(0); int(i) < len(dat); {
+		header := dat[i:]
+		if len(header) < 8 {
+			return attrs, errors.New("truncated attribute header")
+		}
+		datOff := *(*int32)(unsafe.Pointer(&header[0]))
+		attrLen := *(*uint32)(unsafe.Pointer(&header[4]))
+		if datOff < 0 || uint32(datOff)+attrLen > uint32(len(dat)) {
+			return attrs, errors.New("truncated results; attrBuf too small")
+		}
+		end := uint32(datOff) + attrLen
+		attrs = append(attrs, dat[datOff:end])
+		i = end
+		if r := i % 4; r != 0 {
+			i += (4 - r)
+		}
+	}
+	return
+}
+
+//sys getattrlist(path *byte, list unsafe.Pointer, buf unsafe.Pointer, size uintptr, options int) (err error)
+
+//sysnb pipe() (r int, w int, err error)
+
+func Pipe(p []int) (err error) {
+	if len(p) != 2 {
+		return EINVAL
+	}
+	p[0], p[1], err = pipe()
+	return
+}
+
+func Getfsstat(buf []Statfs_t, flags int) (n int, err error) {
+	var _p0 unsafe.Pointer
+	var bufsize uintptr
+	if len(buf) > 0 {
+		_p0 = unsafe.Pointer(&buf[0])
+		bufsize = unsafe.Sizeof(Statfs_t{}) * uintptr(len(buf))
+	}
+	return getfsstat(_p0, bufsize, flags)
+}
+
+func xattrPointer(dest []byte) *byte {
+	// It's only when dest is set to NULL that the OS X implementations of
+	// getxattr() and listxattr() return the current sizes of the named attributes.
+	// An empty byte array is not sufficient. To maintain the same behaviour as the
+	// linux implementation, we wrap around the system calls and pass in NULL when
+	// dest is empty.
+	var destp *byte
+	if len(dest) > 0 {
+		destp = &dest[0]
+	}
+	return destp
+}
+
+//sys	getxattr(path string, attr string, dest *byte, size int, position uint32, options int) (sz int, err error)
+
+func Getxattr(path string, attr string, dest []byte) (sz int, err error) {
+	return getxattr(path, attr, xattrPointer(dest), len(dest), 0, 0)
+}
+
+func Lgetxattr(link string, attr string, dest []byte) (sz int, err error) {
+	return getxattr(link, attr, xattrPointer(dest), len(dest), 0, XATTR_NOFOLLOW)
+}
+
+//sys	fgetxattr(fd int, attr string, dest *byte, size int, position uint32, options int) (sz int, err error)
+
+func Fgetxattr(fd int, attr string, dest []byte) (sz int, err error) {
+	return fgetxattr(fd, attr, xattrPointer(dest), len(dest), 0, 0)
+}
+
+//sys	setxattr(path string, attr string, data *byte, size int, position uint32, options int) (err error)
+
+func Setxattr(path string, attr string, data []byte, flags int) (err error) {
+	// The parameters for the OS X implementation vary slightly compared to the
+	// linux system call, specifically the position parameter:
+	//
+	//  linux:
+	//      int setxattr(
+	//          const char *path,
+	//          const char *name,
+	//          const void *value,
+	//          size_t size,
+	//          int flags
+	//      );
+	//
+	//  darwin:
+	//      int setxattr(
+	//          const char *path,
+	//          const char *name,
+	//          void *value,
+	//          size_t size,
+	//          u_int32_t position,
+	//          int options
+	//      );
+	//
+	// position specifies the offset within the extended attribute. In the
+	// current implementation, only the resource fork extended attribute makes
+	// use of this argument. For all others, position is reserved. We simply
+	// default to setting it to zero.
+	return setxattr(path, attr, xattrPointer(data), len(data), 0, flags)
+}
+
+func Lsetxattr(link string, attr string, data []byte, flags int) (err error) {
+	return setxattr(link, attr, xattrPointer(data), len(data), 0, flags|XATTR_NOFOLLOW)
+}
+
+//sys	fsetxattr(fd int, attr string, data *byte, size int, position uint32, options int) (err error)
+
+func Fsetxattr(fd int, attr string, data []byte, flags int) (err error) {
+	return fsetxattr(fd, attr, xattrPointer(data), len(data), 0, 0)
+}
+
+//sys	removexattr(path string, attr string, options int) (err error)
+
+func Removexattr(path string, attr string) (err error) {
+	// We wrap around and explicitly zero out the options provided to the OS X
+	// implementation of removexattr, we do so for interoperability with the
+	// linux variant.
+	return removexattr(path, attr, 0)
+}
+
+func Lremovexattr(link string, attr string) (err error) {
+	return removexattr(link, attr, XATTR_NOFOLLOW)
+}
+
+//sys	fremovexattr(fd int, attr string, options int) (err error)
+
+func Fremovexattr(fd int, attr string) (err error) {
+	return fremovexattr(fd, attr, 0)
+}
+
+//sys	listxattr(path string, dest *byte, size int, options int) (sz int, err error)
+
+func Listxattr(path string, dest []byte) (sz int, err error) {
+	return listxattr(path, xattrPointer(dest), len(dest), 0)
+}
+
+func Llistxattr(link string, dest []byte) (sz int, err error) {
+	return listxattr(link, xattrPointer(dest), len(dest), XATTR_NOFOLLOW)
+}
+
+//sys	flistxattr(fd int, dest *byte, size int, options int) (sz int, err error)
+
+func Flistxattr(fd int, dest []byte) (sz int, err error) {
+	return flistxattr(fd, xattrPointer(dest), len(dest), 0)
+}
+
+func setattrlistTimes(path string, times []Timespec, flags int) error {
+	_p0, err := BytePtrFromString(path)
+	if err != nil {
+		return err
+	}
+
+	var attrList attrList
+	attrList.bitmapCount = ATTR_BIT_MAP_COUNT
+	attrList.CommonAttr = ATTR_CMN_MODTIME | ATTR_CMN_ACCTIME
+
+	// order is mtime, atime: the opposite of Chtimes
+	attributes := [2]Timespec{times[1], times[0]}
+	options := 0
+	if flags&AT_SYMLINK_NOFOLLOW != 0 {
+		options |= FSOPT_NOFOLLOW
+	}
+	return setattrlist(
+		_p0,
+		unsafe.Pointer(&attrList),
+		unsafe.Pointer(&attributes),
+		unsafe.Sizeof(attributes),
+		options)
+}
+
+//sys setattrlist(path *byte, list unsafe.Pointer, buf unsafe.Pointer, size uintptr, options int) (err error)
+
+func utimensat(dirfd int, path string, times *[2]Timespec, flags int) error {
+	// Darwin doesn't support SYS_UTIMENSAT
+	return ENOSYS
+}
+
+/*
+ * Wrapped
+ */
+
+//sys	fcntl(fd int, cmd int, arg int) (val int, err error)
+
+//sys	kill(pid int, signum int, posix int) (err error)
+
+func Kill(pid int, signum syscall.Signal) (err error) { return kill(pid, int(signum), 1) }
+
+//sys	ioctl(fd int, req uint, arg uintptr) (err error)
+
+//sys   sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) = SYS_SYSCTL
+
+func Uname(uname *Utsname) error {
+	mib := []_C_int{CTL_KERN, KERN_OSTYPE}
+	n := unsafe.Sizeof(uname.Sysname)
+	if err := sysctl(mib, &uname.Sysname[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_HOSTNAME}
+	n = unsafe.Sizeof(uname.Nodename)
+	if err := sysctl(mib, &uname.Nodename[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_OSRELEASE}
+	n = unsafe.Sizeof(uname.Release)
+	if err := sysctl(mib, &uname.Release[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	mib = []_C_int{CTL_KERN, KERN_VERSION}
+	n = unsafe.Sizeof(uname.Version)
+	if err := sysctl(mib, &uname.Version[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	// The version might have newlines or tabs in it, convert them to
+	// spaces.
+	for i, b := range uname.Version {
+		if b == '\n' || b == '\t' {
+			if i == len(uname.Version)-1 {
+				uname.Version[i] = 0
+			} else {
+				uname.Version[i] = ' '
+			}
+		}
+	}
+
+	mib = []_C_int{CTL_HW, HW_MACHINE}
+	n = unsafe.Sizeof(uname.Machine)
+	if err := sysctl(mib, &uname.Machine[0], &n, nil, 0); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	if raceenabled {
+		raceReleaseMerge(unsafe.Pointer(&ioSync))
+	}
+	var length = int64(count)
+	err = sendfile(infd, outfd, *offset, &length, nil, 0)
+	written = int(length)
+	return
+}
+
+//sys	sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error)
+
+/*
+ * Exposed directly
+ */
+//sys	Access(path string, mode uint32) (err error)
+//sys	Adjtime(delta *Timeval, olddelta *Timeval) (err error)
+//sys	Chdir(path string) (err error)
+//sys	Chflags(path string, flags int) (err error)
+//sys	Chmod(path string, mode uint32) (err error)
+//sys	Chown(path string, uid int, gid int) (err error)
+//sys	Chroot(path string) (err error)
+//sys	ClockGettime(clockid int32, time *Timespec) (err error)
+//sys	Close(fd int) (err error)
+//sys	Dup(fd int) (nfd int, err error)
+//sys	Dup2(from int, to int) (err error)
+//sys	Exchangedata(path1 string, path2 string, options int) (err error)
+//sys	Exit(code int)
+//sys	Faccessat(dirfd int, path string, mode uint32, flags int) (err error)
+//sys	Fchdir(fd int) (err error)
+//sys	Fchflags(fd int, flags int) (err error)
+//sys	Fchmod(fd int, mode uint32) (err error)
+//sys	Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)
+//sys	Fchown(fd int, uid int, gid int) (err error)
+//sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
+//sys	Flock(fd int, how int) (err error)
+//sys	Fpathconf(fd int, name int) (val int, err error)
+//sys	Fsync(fd int) (err error)
+//sys	Ftruncate(fd int, length int64) (err error)
+//sys	Getdtablesize() (size int)
+//sysnb	Getegid() (egid int)
+//sysnb	Geteuid() (uid int)
+//sysnb	Getgid() (gid int)
+//sysnb	Getpgid(pid int) (pgid int, err error)
+//sysnb	Getpgrp() (pgrp int)
+//sysnb	Getpid() (pid int)
+//sysnb	Getppid() (ppid int)
+//sys	Getpriority(which int, who int) (prio int, err error)
+//sysnb	Getrlimit(which int, lim *Rlimit) (err error)
+//sysnb	Getrusage(who int, rusage *Rusage) (err error)
+//sysnb	Getsid(pid int) (sid int, err error)
+//sysnb	Getuid() (uid int)
+//sysnb	Issetugid() (tainted bool)
+//sys	Kqueue() (fd int, err error)
+//sys	Lchown(path string, uid int, gid int) (err error)
+//sys	Link(path string, link string) (err error)
+//sys	Linkat(pathfd int, path string, linkfd int, link string, flags int) (err error)
+//sys	Listen(s int, backlog int) (err error)
+//sys	Mkdir(path string, mode uint32) (err error)
+//sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
+//sys	Mkfifo(path string, mode uint32) (err error)
+//sys	Mknod(path string, mode uint32, dev int) (err error)
+//sys	Open(path string, mode int, perm uint32) (fd int, err error)
+//sys	Openat(dirfd int, path string, mode int, perm uint32) (fd int, err error)
+//sys	Pathconf(path string, name int) (val int, err error)
+//sys	Pread(fd int, p []byte, offset int64) (n int, err error)
+//sys	Pwrite(fd int, p []byte, offset int64) (n int, err error)
+//sys	read(fd int, p []byte) (n int, err error)
+//sys	Readlink(path string, buf []byte) (n int, err error)
+//sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)
+//sys	Rename(from string, to string) (err error)
+//sys	Renameat(fromfd int, from string, tofd int, to string) (err error)
+//sys	Revoke(path string) (err error)
+//sys	Rmdir(path string) (err error)
+//sys	Seek(fd int, offset int64, whence int) (newoffset int64, err error) = SYS_LSEEK
+//sys	Select(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)
+//sys	Setegid(egid int) (err error)
+//sysnb	Seteuid(euid int) (err error)
+//sysnb	Setgid(gid int) (err error)
+//sys	Setlogin(name string) (err error)
+//sysnb	Setpgid(pid int, pgid int) (err error)
+//sys	Setpriority(which int, who int, prio int) (err error)
+//sys	Setprivexec(flag int) (err error)
+//sysnb	Setregid(rgid int, egid int) (err error)
+//sysnb	Setreuid(ruid int, euid int) (err error)
+//sysnb	Setrlimit(which int, lim *Rlimit) (err error)
+//sysnb	Setsid() (pid int, err error)
+//sysnb	Settimeofday(tp *Timeval) (err error)
+//sysnb	Setuid(uid int) (err error)
+//sys	Symlink(path string, link string) (err error)
+//sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
+//sys	Sync() (err error)
+//sys	Truncate(path string, length int64) (err error)
+//sys	Umask(newmask int) (oldmask int)
+//sys	Undelete(path string) (err error)
+//sys	Unlink(path string) (err error)
+//sys	Unlinkat(dirfd int, path string, flags int) (err error)
+//sys	Unmount(path string, flags int) (err error)
+//sys	write(fd int, p []byte) (n int, err error)
+//sys   mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
+//sys   munmap(addr uintptr, length uintptr) (err error)
+//sys	readlen(fd int, buf *byte, nbuf int) (n int, err error) = SYS_READ
+//sys	writelen(fd int, buf *byte, nbuf int) (n int, err error) = SYS_WRITE
+
+/*
+ * Unimplemented
+ */
+// Profil
+// Sigaction
+// Sigprocmask
+// Getlogin
+// Sigpending
+// Sigaltstack
+// Ioctl
+// Reboot
+// Execve
+// Vfork
+// Sbrk
+// Sstk
+// Ovadvise
+// Mincore
+// Setitimer
+// Swapon
+// Select
+// Sigsuspend
+// Readv
+// Writev
+// Nfssvc
+// Getfh
+// Quotactl
+// Mount
+// Csops
+// Waitid
+// Add_profil
+// Kdebug_trace
+// Sigreturn
+// Atsocket
+// Kqueue_from_portset_np
+// Kqueue_portset
+// Getattrlist
+// Setattrlist
+// Getdirentriesattr
+// Searchfs
+// Delete
+// Copyfile
+// Watchevent
+// Waitevent
+// Modwatch
+// Fsctl
+// Initgroups
+// Posix_spawn
+// Nfsclnt
+// Fhopen
+// Minherit
+// Semsys
+// Msgsys
+// Shmsys
+// Semctl
+// Semget
+// Semop
+// Msgctl
+// Msgget
+// Msgsnd
+// Msgrcv
+// Shmat
+// Shmctl
+// Shmdt
+// Shmget
+// Shm_open
+// Shm_unlink
+// Sem_open
+// Sem_close
+// Sem_unlink
+// Sem_wait
+// Sem_trywait
+// Sem_post
+// Sem_getvalue
+// Sem_init
+// Sem_destroy
+// Open_extended
+// Umask_extended
+// Stat_extended
+// Lstat_extended
+// Fstat_extended
+// Chmod_extended
+// Fchmod_extended
+// Access_extended
+// Settid
+// Gettid
+// Setsgroups
+// Getsgroups
+// Setwgroups
+// Getwgroups
+// Mkfifo_extended
+// Mkdir_extended
+// Identitysvc
+// Shared_region_check_np
+// Shared_region_map_np
+// __pthread_mutex_destroy
+// __pthread_mutex_init
+// __pthread_mutex_lock
+// __pthread_mutex_trylock
+// __pthread_mutex_unlock
+// __pthread_cond_init
+// __pthread_cond_destroy
+// __pthread_cond_broadcast
+// __pthread_cond_signal
+// Setsid_with_pid
+// __pthread_cond_timedwait
+// Aio_fsync
+// Aio_return
+// Aio_suspend
+// Aio_cancel
+// Aio_error
+// Aio_read
+// Aio_write
+// Lio_listio
+// __pthread_cond_wait
+// Iopolicysys
+// __pthread_kill
+// __pthread_sigmask
+// __sigwait
+// __disable_threadsignal
+// __pthread_markcancel
+// __pthread_canceled
+// __semwait_signal
+// Proc_info
+// sendfile
+// Stat64_extended
+// Lstat64_extended
+// Fstat64_extended
+// __pthread_chdir
+// __pthread_fchdir
+// Audit
+// Auditon
+// Getauid
+// Setauid
+// Getaudit
+// Setaudit
+// Getaudit_addr
+// Setaudit_addr
+// Auditctl
+// Bsdthread_create
+// Bsdthread_terminate
+// Stack_snapshot
+// Bsdthread_register
+// Workq_open
+// Workq_ops
+// __mac_execve
+// __mac_syscall
+// __mac_get_file
+// __mac_set_file
+// __mac_get_link
+// __mac_set_link
+// __mac_get_proc
+// __mac_set_proc
+// __mac_get_fd
+// __mac_set_fd
+// __mac_get_pid
+// __mac_get_lcid
+// __mac_get_lctx
+// __mac_set_lctx
+// Setlcid
+// Read_nocancel
+// Write_nocancel
+// Open_nocancel
+// Close_nocancel
+// Wait4_nocancel
+// Recvmsg_nocancel
+// Sendmsg_nocancel
+// Recvfrom_nocancel
+// Accept_nocancel
+// Fcntl_nocancel
+// Select_nocancel
+// Fsync_nocancel
+// Connect_nocancel
+// Sigsuspend_nocancel
+// Readv_nocancel
+// Writev_nocancel
+// Sendto_nocancel
+// Pread_nocancel
+// Pwrite_nocancel
+// Waitid_nocancel
+// Poll_nocancel
+// Msgsnd_nocancel
+// Msgrcv_nocancel
+// Sem_wait_nocancel
+// Aio_suspend_nocancel
+// __sigwait_nocancel
+// __semwait_signal_nocancel
+// __mac_mount
+// __mac_get_mount
+// __mac_getfsstat