func getLSB() (*LSB, error) {
	ret := &LSB{}
	if common.PathExists("/etc/lsb-release") {
		contents, err := common.ReadLines("/etc/lsb-release")
		if err != nil {
			return ret, err // return empty
		}
		for _, line := range contents {
			field := strings.Split(line, "=")
			if len(field) < 2 {
				continue
			}
			switch field[0] {
			case "DISTRIB_ID":
				ret.ID = field[1]
			case "DISTRIB_RELEASE":
				ret.Release = field[1]
			case "DISTRIB_CODENAME":
				ret.Codename = field[1]
			case "DISTRIB_DESCRIPTION":
				ret.Description = field[1]
			}
		}
	} else if common.PathExists("/usr/bin/lsb_release") {
		out, err := exec.Command("/usr/bin/lsb_release").Output()
		if err != nil {
			return ret, err
		}
		for _, line := range strings.Split(string(out), "\n") {
			field := strings.Split(line, ":")
			if len(field) < 2 {
				continue
			}
			switch field[0] {
			case "Distributor ID":
				ret.ID = field[1]
			case "Release":
				ret.Release = field[1]
			case "Codename":
				ret.Codename = field[1]
			case "Description":
				ret.Description = field[1]
			}
		}

	}

	return ret, nil
}
func CPUTimes(percpu bool) ([]CPUTimesStat, error) {
	var ret []CPUTimesStat
	if !common.PathExists(HELPER_PATH) {
		return nil, fmt.Errorf("could not get cpu time")
	}

	out, err := exec.Command(HELPER_PATH).Output()
	if err != nil {
		return ret, err
	}

	for _, line := range strings.Split(string(out), "\n") {
		f := strings.Split(string(line), ",")
		if len(f) != 5 {
			continue
		}
		cpu, err := strconv.ParseFloat(f[0], 64)
		if err != nil {
			return ret, err
		}
		// cpu:99 means total, so just ignore if percpu
		if (percpu && cpu == 99) || (!percpu && cpu != 99) {
			continue
		}
		user, err := strconv.ParseFloat(f[1], 64)
		if err != nil {
			return ret, err
		}
		sys, err := strconv.ParseFloat(f[2], 64)
		if err != nil {
			return ret, err
		}
		idle, err := strconv.ParseFloat(f[3], 64)
		if err != nil {
			return ret, err
		}
		nice, err := strconv.ParseFloat(f[4], 64)
		if err != nil {
			return ret, err
		}
		c := CPUTimesStat{
			User:   float64(user / ClocksPerSec),
			Nice:   float64(nice / ClocksPerSec),
			System: float64(sys / ClocksPerSec),
			Idle:   float64(idle / ClocksPerSec),
		}
		if !percpu {
			c.CPU = "cpu-total"
		} else {
			c.CPU = fmt.Sprintf("cpu%d", uint16(cpu))
		}
		ret = append(ret, c)
	}
	return ret, nil
}
func Users() ([]UserStat, error) {
	utmpfile := "/var/run/utx.active"
	if !common.PathExists(utmpfile) {
		utmpfile = "/var/run/utmp" // before 9.0
		return getUsersFromUtmp(utmpfile)
	}

	var ret []UserStat
	file, err := os.Open(utmpfile)
	if err != nil {
		return ret, err
	}

	buf, err := ioutil.ReadAll(file)
	if err != nil {
		return ret, err
	}

	u := Utmpx{}
	entrySize := int(unsafe.Sizeof(u)) - 3
	entrySize = 197 // TODO: why should 197
	count := len(buf) / entrySize

	for i := 0; i < count; i++ {
		b := buf[i*entrySize : i*entrySize+entrySize]
		var u Utmpx
		br := bytes.NewReader(b)
		err := binary.Read(br, binary.LittleEndian, &u)
		if err != nil || u.Type != 4 {
			continue
		}
		sec := (binary.LittleEndian.Uint32(u.Tv.Sec[:])) / 2 // TODO:
		user := UserStat{
			User:     common.IntToString(u.User[:]),
			Terminal: common.IntToString(u.Line[:]),
			Host:     common.IntToString(u.Host[:]),
			Started:  int(sec),
		}

		ret = append(ret, user)
	}

	return ret, nil

}
func init() {
	out, err := exec.Command("/usr/bin/getconf", "CLK_TCK").Output()
	// ignore errors
	if err == nil {
		i, err := strconv.ParseFloat(strings.TrimSpace(string(out)), 64)
		if err == nil {
			ClocksPerSec = float64(i)
		}
	}

	// adhoc compile on the host. Errors will be ignored.
	// gcc is required to compile.
	if !common.PathExists(HELPER_PATH) && os.Getenv(HELPER_ENABLE_ENV) == "yes" {
		cmd := exec.Command("gcc", "-o", HELPER_PATH, "-x", "c", "-")
		stdin, err := cmd.StdinPipe()
		if err != nil {
			return
		}
		io.WriteString(stdin, cpu_helper_src)
		stdin.Close()
		cmd.Output()
	}
}
func GetVirtualization() (string, string, error) {
	var system string
	var role string

	if common.PathExists("/proc/xen") {
		system = "xen"
		role = "guest" // assume guest

		if common.PathExists("/proc/xen/capabilities") {
			contents, err := common.ReadLines("/proc/xen/capabilities")
			if err == nil {
				if common.StringsHas(contents, "control_d") {
					role = "host"
				}
			}
		}
	}
	if common.PathExists("/proc/modules") {
		contents, err := common.ReadLines("/proc/modules")
		if err == nil {
			if common.StringsContains(contents, "kvm") {
				system = "kvm"
				role = "host"
			} else if common.StringsContains(contents, "vboxdrv") {
				system = "vbox"
				role = "host"
			} else if common.StringsContains(contents, "vboxguest") {
				system = "vbox"
				role = "guest"
			}
		}
	}

	if common.PathExists("/proc/cpuinfo") {
		contents, err := common.ReadLines("/proc/cpuinfo")
		if err == nil {
			if common.StringsHas(contents, "QEMU Virtual CPU") ||
				common.StringsHas(contents, "Common KVM processor") ||
				common.StringsHas(contents, "Common 32-bit KVM processor") {
				system = "kvm"
				role = "guest"
			}
		}
	}

	if common.PathExists("/proc/bc/0") {
		system = "openvz"
		role = "host"
	} else if common.PathExists("/proc/vz") {
		system = "openvz"
		role = "guest"
	}

	// not use dmidecode because it requires root

	if common.PathExists("/proc/self/status") {
		contents, err := common.ReadLines("/proc/self/status")
		if err == nil {

			if common.StringsHas(contents, "s_context:") ||
				common.StringsHas(contents, "VxID:") {
				system = "linux-vserver"
			}
			// TODO: guest or host
		}
	}

	if common.PathExists("/proc/self/cgroup") {
		contents, err := common.ReadLines("/proc/self/cgroup")
		if err == nil {
			if common.StringsHas(contents, "lxc") ||
				common.StringsHas(contents, "docker") {
				system = "lxc"
				role = "guest"
			} else if common.PathExists("/usr/bin/lxc-version") { // TODO: which
				system = "lxc"
				role = "host"
			}
		}
	}

	return system, role, nil
}
func GetPlatformInformation() (platform string, family string, version string, err error) {

	lsb, err := getLSB()
	if err != nil {
		lsb = &LSB{}
	}

	if common.PathExists("/etc/oracle-release") {
		platform = "oracle"
		contents, err := common.ReadLines("/etc/oracle-release")
		if err == nil {
			version = getRedhatishVersion(contents)
		}
	} else if common.PathExists("/etc/enterprise-release") {
		platform = "oracle"
		contents, err := common.ReadLines("/etc/enterprise-release")
		if err == nil {
			version = getRedhatishVersion(contents)
		}
	} else if common.PathExists("/etc/debian_version") {
		if lsb.ID == "Ubuntu" {
			platform = "ubuntu"
			version = lsb.Release
		} else if lsb.ID == "LinuxMint" {
			platform = "linuxmint"
			version = lsb.Release
		} else {
			if common.PathExists("/usr/bin/raspi-config") {
				platform = "raspbian"
			} else {
				platform = "debian"
			}
			contents, err := common.ReadLines("/etc/debian_version")
			if err == nil {
				version = contents[0]
			}
		}
	} else if common.PathExists("/etc/redhat-release") {
		contents, err := common.ReadLines("/etc/redhat-release")
		if err == nil {
			version = getRedhatishVersion(contents)
			platform = getRedhatishPlatform(contents)
		}
	} else if common.PathExists("/etc/system-release") {
		contents, err := common.ReadLines("/etc/system-release")
		if err == nil {
			version = getRedhatishVersion(contents)
			platform = getRedhatishPlatform(contents)
		}
	} else if common.PathExists("/etc/gentoo-release") {
		platform = "gentoo"
		contents, err := common.ReadLines("/etc/gentoo-release")
		if err == nil {
			version = getRedhatishVersion(contents)
		}
	} else if common.PathExists("/etc/SuSE-release") {
		contents, err := common.ReadLines("/etc/SuSE-release")
		if err == nil {
			version = getSuseVersion(contents)
			platform = getSusePlatform(contents)
		}
		// TODO: slackware detecion
	} else if common.PathExists("/etc/arch-release") {
		platform = "arch"
		// TODO: exherbo detection
	} else if lsb.ID == "RedHat" {
		platform = "redhat"
		version = lsb.Release
	} else if lsb.ID == "Amazon" {
		platform = "amazon"
		version = lsb.Release
	} else if lsb.ID == "ScientificSL" {
		platform = "scientific"
		version = lsb.Release
	} else if lsb.ID == "XenServer" {
		platform = "xenserver"
		version = lsb.Release
	} else if lsb.ID != "" {
		platform = strings.ToLower(lsb.ID)
		version = lsb.Release
	}

	switch platform {
	case "debian", "ubuntu", "linuxmint", "raspbian":
		family = "debian"
	case "fedora":
		family = "fedora"
	case "oracle", "centos", "redhat", "scientific", "enterpriseenterprise", "amazon", "xenserver", "cloudlinux", "ibm_powerkvm":
		family = "rhel"
	case "suse", "opensuse":
		family = "suse"
	case "gentoo":
		family = "gentoo"
	case "slackware":
		family = "slackware"
	case "arch":
		family = "arch"
	case "exherbo":
		family = "exherbo"
	}

	return platform, family, version, nil

}