You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: osext_sysctl.go
    path of file: ./repos/cloud-torrent/vendor/github.com/kardianos/osext
    
    the code of the file until where you have to start completion: // Copyright 2012 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 freebsd openbsd

package osext

import (
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"syscall"
	"unsafe"
)

var initCwd, initCwdErr = os.Getwd()

func executable() (string, error) {
	var mib [4]int32
	switch runtime.GOOS {
	case "freebsd":
		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
	case "darwin":
		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
	case "openbsd":
		mib = [4]int32{1 /* CTL_KERN */, 55 /* KERN_PROC_ARGS */, int32(os.Getpid()), 1 /* KERN_PROC_ARGV */}
	}

	n := uintptr(0)
	// Get length.
	_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
	if errNum != 0 {
		return "", errNum
	}
	if n == 0 { // 
    
func executable() (string, error) {
	var mib [4]int32
	switch runtime.GOOS {
	case "freebsd":
		mib = [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
	case "darwin":
		mib = [4]int32{1 /* CTL_KERN */, 38 /* KERN_PROCARGS */, int32(os.Getpid()), -1}
	case "openbsd":
		mib = [4]int32{1 /* CTL_KERN */, 55 /* KERN_PROC_ARGS */, int32(os.Getpid()), 1 /* KERN_PROC_ARGV */}
	}

	n := uintptr(0)
	// Get length.
	_, _, errNum := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
	if errNum != 0 {
		return "", errNum
	}
	if n == 0 { // This shouldn't happen.
		return "", nil
	}
	buf := make([]byte, n)
	_, _, errNum = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
	if errNum != 0 {
		return "", errNum
	}
	if n == 0 { // This shouldn't happen.
		return "", nil
	}

	var execPath string
	switch runtime.GOOS {
	case "openbsd":
		// buf now contains **argv, with pointers to each of the C-style
		// NULL terminated arguments.
		var args []string
		argv := uintptr(unsafe.Pointer(&buf[0]))
	Loop:
		for {
			argp := *(**[1 << 20]byte)(unsafe.Pointer(argv))
			if argp == nil {
				break
			}
			for i := 0; uintptr(i) < n; i++ {
				// we don't want the full arguments list
				if string(argp[i]) == " " {
					break Loop
				}
				if argp[i] != 0 {
					continue
				}
				args = append(args, string(argp[:i]))
				n -= uintptr(i)
				break
			}
			if n < unsafe.Sizeof(argv) {
				break
			}
			argv += unsafe.Sizeof(argv)
			n -= unsafe.Sizeof(argv)
		}
		execPath = args[0]
		// There is no canonical way to get an executable path on
		// OpenBSD, so check PATH in case we are called directly
		if execPath[0] != '/' && execPath[0] != '.' {
			execIsInPath, err := exec.LookPath(execPath)
			if err == nil {
				execPath = execIsInPath
			}
		}
	default:
		for i, v := range buf {
			if v == 0 {
				buf = buf[:i]
				break
			}
		}
		execPath = string(buf)
	}

	var err error
	// execPath will not be empty due to above checks.
	// Try to get the absolute path if the execPath is not rooted.
	if execPath[0] != '/' {
		execPath, err = getAbs(execPath)
		if err != nil {
			return execPath, err
		}
	}
	// For darwin KERN_PROCARGS may return the path to a symlink rather than the
	// actual executable.
	if runtime.GOOS == "darwin" {
		if execPath, err = filepath.EvalSymlinks(execPath); err != nil {
			return execPath, err
		}
	}
	return execPath, nil
}