dbtester/pkg/ntp/ntp.go

117 lines
2.6 KiB
Go

// Copyright 2017 CoreOS, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package ntp syncs system time with NTP server.
package ntp
import (
"bytes"
"fmt"
"io"
"os"
"os/exec"
"strings"
)
var (
DefaultNTP = "/usr/sbin/ntpdate"
DefaultServer = "time.nist.gov"
)
// DefaultSync syncs system time with NTP server.
func DefaultSync() (string, error) {
return Sync(DefaultNTP, DefaultServer)
}
var inUseErr = "NTP socket is in use"
// Sync syncs system time with NTP server.
//
// sudo service ntp stop
// sudo ntpdate time.nist.gov
// sudo service ntp start
//
func Sync(ntpPath string, server string) (string, error) {
buf := new(bytes.Buffer)
err := startNTP(ntpPath, server, buf)
o := strings.TrimSpace(buf.String())
if err == nil && strings.Contains(o, "adjust time server") {
return o, nil
}
if !strings.Contains(o, inUseErr) && (err != nil && !strings.Contains(err.Error(), inUseErr)) {
return o, err
}
so, err := serviceNTP("stop")
if err != nil {
return so, err
}
buf.Reset()
err = startNTP(ntpPath, server, buf)
o = strings.TrimSpace(buf.String())
if err != nil {
return o, err
}
so, err = serviceNTP("start")
if err != nil {
return so, err
}
if so != "" {
o += ";" + so
}
return o, nil
}
func startNTP(ntpPath string, server string, w io.Writer) error {
if !exist(ntpPath) {
return fmt.Errorf("%q does not exist", ntpPath)
}
cmd := exec.Command("sudo", ntpPath, server)
cmd.Stdout = w
cmd.Stderr = w
return cmd.Run()
}
// when 'NTP socket is in use' error is returned
func serviceNTP(command string) (string, error) {
buf := new(bytes.Buffer)
cmd := exec.Command("sudo", "service", "ntp", command)
cmd.Stdout = buf
cmd.Stderr = buf
err := cmd.Run()
return strings.TrimSpace(buf.String()), err
}
// exist returns true if the file or directory exists.
func exist(fpath string) bool {
st, err := os.Stat(fpath)
if err != nil {
if os.IsNotExist(err) {
return false
}
}
if st.IsDir() {
return true
}
if _, err := os.Stat(fpath); err != nil {
if os.IsNotExist(err) {
return false
}
}
return true
}