Implement proper daemonization

The shell wrapper sends gocryptfs into the background and waits for SIGUSR1

1 files changed, 42 insertions, 0 deletions

diff --git a/gocryptfs_main/sendsig.go b/gocryptfs_main/sendsig.go
new file mode 100644
index 0000000..98bd448
--- /dev/null
+++ b/gocryptfs_main/sendsig.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"syscall"
+	"bytes"
+	"fmt"
+	"os"
+	"io/ioutil"
+)
+
+// cmdline looks like this: /bin/bash \0 /path/to/gocryptfs \0 --zerokey \0 ...
+const (
+	WRAPPER_PREFIX =  "/bin/bash\000"
+	WRAPPER_CONTAINS = "gocryptfs\000"
+)
+
+// Send USR1 to the "gocryptfs" wrapper shell script. This notifies it that the
+// mounting has completed sucessfully.
+//
+// Checks /proc/$PPID/cmdline to make sure we do not kill an unrelated process.
+func sendSig() {
+	ppid := os.Getppid()
+	fn := fmt.Sprintf("/proc/%d/cmdline", ppid)
+	cmdline, err := ioutil.ReadFile(fn)
+	if err != nil {
+		fmt.Printf("sendSig: ReadFile: %v\n", err)
+		return
+	}
+	if bytes.HasPrefix(cmdline, []byte(WRAPPER_PREFIX)) && bytes.Contains(cmdline, []byte(WRAPPER_CONTAINS)) {
+		p, err := os.FindProcess(ppid)
+		if err != nil {
+			fmt.Printf("sendSig: FindProcess: %v\n", err)
+			return
+		}
+		err = p.Signal(syscall.SIGUSR1)
+		if err != nil {
+			fmt.Printf("sendSig: Signal: %v\n", err)
+		}
+	} else {
+		fmt.Printf("Not running under the gocryptfs wrapper - will not daemonize\n")
+	}
+}