Add native daemonization

2 files changed, 52 insertions, 1 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)
+}
diff --git a/main.go b/main.go
index 89f3723..2d6da05 100644
--- a/main.go
+++ b/main.go
@@ -66,7 +66,7 @@ func main() {
 	runtime.GOMAXPROCS(4)
 
 	// Parse command line arguments
-	var debug, init, zerokey, fusedebug, openssl, passwd bool
+	var debug, init, zerokey, fusedebug, openssl, passwd, foreground bool
 	var masterkey string
 
 	flag.Usage = usageText
@@ -76,10 +76,14 @@ func main() {
 	flag.BoolVar(&zerokey, "zerokey", false, "Use all-zero dummy master key")
 	flag.BoolVar(&openssl, "openssl", true, "Use OpenSSL instead of built-in Go crypto")
 	flag.BoolVar(&passwd, "passwd", false, "Change password")
+	flag.BoolVar(&foreground, "f", false, "Stay in the foreground")
 	flag.StringVar(&masterkey, "masterkey", "", "Mount with explicit master key")
 	var cpuprofile = flag.String("cpuprofile", "", "Write cpu profile to specified file")
 
 	flag.Parse()
+	if ! foreground {
+		daemonize() // does not return
+	}
 	if *cpuprofile != "" {
 		f, err := os.Create(*cpuprofile)
 		if err != nil {