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: common_freebsd.go
    path of file: ./repos/cf-tool/vendor/github.com/shirou/gopsutil/internal/common
    
    the code of the file until where you have to start completion: // +build freebsd openbsd

package common

import (
	"fmt"
	"os"
	"os/exec"
	"strings"
	"unsafe"

	"golang.org/x/sys/unix"
)

func SysctlUint(mib string) (uint64, error) {
	buf, err := unix.SysctlRaw(mib)
	if err != nil {
		return 0, err
	}
	if len(buf) == 8 { // 64 bit
		return *(*uint64)(unsafe.Pointer(&buf[0])), nil
	}
	if len(buf) == 4 { // 32bit
		t := *(*uint32)(unsafe.Pointer(&buf[0]))
		return uint64(t), nil
	}
	return 0, fmt.Errorf("unexpected size: %s, %d", mib, len(buf))
}

func DoSysctrl(mib string) ([]string, error) {
	sysctl, err := exec.LookPath(
    
func CallSyscall(mib []int32) ([]byte, uint64, error) {
	mibptr := unsafe.Pointer(&mib[0])
	miblen := uint64(len(mib))

	// get required buffer size
	length := uint64(0)
	_, _, err := unix.Syscall6(
		unix.SYS___SYSCTL,
		uintptr(mibptr),
		uintptr(miblen),
		0,
		uintptr(unsafe.Pointer(&length)),
		0,
		0)
	if err != 0 {
		var b []byte
		return b, length, err
	}
	if length == 0 {
		var b []byte
		return b, length, err
	}
	// get proc info itself
	buf := make([]byte, length)
	_, _, err = unix.Syscall6(
		unix.SYS___SYSCTL,
		uintptr(mibptr),
		uintptr(miblen),
		uintptr(unsafe.Pointer(&buf[0])),
		uintptr(unsafe.Pointer(&length)),
		0,
		0)
	if err != 0 {
		return buf, length, err
	}

	return buf, length, nil
}