Adding os/daemon library

README.md

@@ -4,6 +4,7 @@ GO libraries
 Libraries
 ---------
 
-    fs/inotify  - inotify library for go
+    fs/inotify  - inotify library
     net/cluster - simple network cluster
+    os/daemon   - daemonize library
 

os/daemon/daemon.go

+package daemon
+
+import (
+	"errors"
+	"flag"
+	//"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+type Daemon struct {
+	ConfigFile    string
+	LogFile       string
+	PidFile       string
+	startServer   bool
+	stopServer    bool
+	restartServer bool
+	args          []string
+	flagSet       *flag.FlagSet
+}
+
+func New(AppName string, ConfigFile string, LogFile string, PidFile string) *Daemon {
+	args := os.Args
+	daemon := &Daemon{
+		args: args,
+	}
+
+	flagset := flag.NewFlagSet(AppName, flag.ExitOnError)
+
+	flagset.StringVar(&daemon.PidFile,
+		"pid",
+		PidFile,
+		"\tServer PID File",
+	)
+
+	flagset.StringVar(&daemon.ConfigFile,
+		"config",
+		ConfigFile,
+		"\tConfig file",
+	)
+
+	flagset.StringVar(&daemon.LogFile,
+		"log",
+		LogFile,
+		"\tServer log File",
+	)
+
+	flagset.BoolVar(&daemon.startServer,
+		"start",
+		false,
+		"\tStart application and daemonize",
+	)
+
+	flagset.BoolVar(&daemon.stopServer,
+		"stop",
+		false,
+		"\tStop application",
+	)
+
+	flagset.BoolVar(&daemon.restartServer,
+		"restart",
+		false,
+		"\tRestart application",
+	)
+
+	flagset.Usage = func() {
+		flagset.PrintDefaults()
+		os.Exit(2)
+	}
+
+	daemon.flagSet = flagset
+	daemon.flagSet.Parse(args[1:])
+
+	return daemon
+}
+
+func (d *Daemon) Run() error {
+
+	if d.stopServer || d.restartServer {
+		d.stopProcess()
+	}
+
+	if d.startServer || d.restartServer {
+		if pid := d.getPid(); pid == 0 {
+			d.startProcess()
+			os.Exit(0)
+		}
+		return errors.New("Process allready running")
+	}
+
+	if d.stopServer {
+		os.Exit(0)
+	}
+
+	err := d.setPid()
+	if err != nil {
+		return err
+	}
+
+	err = d.setLog()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Read pid from file , check if process is running
+func (d *Daemon) getPid() int {
+	var pid int
+	f, err := os.Open(d.PidFile)
+	if err != nil {
+		return 0
+	}
+	defer f.Close()
+
+	buf := make([]byte, 10)
+
+	lpid, err := f.Read(buf)
+	if err == nil {
+		pid, err = strconv.Atoi(string(buf[:lpid]))
+		if err != nil {
+			return 0
+		}
+		if err = syscall.Kill(pid, 0); err == nil {
+			return pid
+		}
+	}
+	return 0
+}
+
+// Write pid to file
+func (d *Daemon) setPid() error {
+	pidfile, err := os.OpenFile(
+		d.PidFile,
+		os.O_CREATE|os.O_RDWR,
+		0666,
+	)
+
+	if err != nil {
+		return err
+	}
+	defer pidfile.Close()
+	pid := os.Getpid()
+
+	pidfile.Write([]byte(strconv.Itoa(pid)))
+
+	pidfile.Close()
+	return nil
+}
+
+func (d *Daemon) setLog() error {
+
+	if os.Getenv("go-daemon-child") == "" {
+		return nil
+	}
+
+	logfile, err := os.OpenFile(
+		d.LogFile,
+		os.O_APPEND|os.O_CREATE|os.O_RDWR,
+		0666,
+	)
+	if err != nil {
+		return err
+	}
+	// Redirect Stdout and Stderr to log
+	syscall.Dup2(int(logfile.Fd()), 1)
+	syscall.Dup2(int(logfile.Fd()), 2)
+
+	return nil
+}
+
+func (d *Daemon) startProcess() error {
+	procArgs := []string{}
+	opt := ""
+
+	for _, arg := range d.args {
+		if strings.HasPrefix(arg, "-") {
+			opt = arg
+		}
+		if opt != "-start" && opt != "-stop" && opt != "-restart" {
+			procArgs = append(procArgs, arg)
+		}
+	}
+	procName := filepath.Base(procArgs[0])
+	procPath := filepath.Dir(procArgs[0])
+	procArgs[0] = procName
+	env := os.Environ()
+	env = append(env, "go-daemon-child=running")
+	procAttr := &os.ProcAttr{
+		Dir:   procPath,
+		Env:   env,
+		Files: []*os.File{nil, nil, nil},
+	}
+
+	_, err := os.StartProcess(procName, procArgs, procAttr)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (d *Daemon) stopProcess() error {
+	return nil
+}