Add native daemonization

1 files changed, 47 insertions, 0 deletions

diff --git a/daemonize.go b/daemonize.go
new file mode 100644
index 0000000..87faf33
--- /dev/null
+++ b/daemonize.go
@@ -0,0 +1,47 @@
+package main
+
+import (
+	"syscall"
+	"os/exec"
+	"os"
+	"fmt"
+	"os/signal"
+)
+
+// The child sends us USR1 if the mount was successful
+func waitForUsr1() {
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGUSR1)
+	<-c
+	os.Exit(0)
+}
+
+// daemonize - execute ourselves once again, this time with the "-f" flag, and
+// wait for SIGUSR1.
+func daemonize() {
+	go waitForUsr1()
+	name := os.Args[0]
+	newArgs := []string{"-f"}
+	newArgs = append(newArgs, os.Args[1:]...)
+	c := exec.Command(name, newArgs...)
+	c.Stdout = os.Stdout
+	c.Stderr = os.Stderr
+	c.Stdin = os.Stdin
+	err := c.Start()
+	if err != nil {
+		fmt.Printf("daemonize: starting %s failed: %v\n", name)
+		os.Exit(1)
+	}
+	err = c.Wait()
+	if err != nil {
+		if exiterr, ok := err.(*exec.ExitError); ok {
+			if waitstat, ok := exiterr.Sys().(syscall.WaitStatus); ok {
+                os.Exit(waitstat.ExitStatus())
+            }
+		}
+		fmt.Printf("daemonize: wait returned an unknown error: %v\n", err)
+		os.Exit(1)
+	}
+	// The child exited with 0 - let's do the same.
+	os.Exit(0)
+}