added generic user lookup and foreground processes

lookup_cgo.go

@@ -0,0 +1,23 @@
+// Copyright (C) 2017 Marius Schellenberger
+
+// +build cgo
+
+package godrop
+
+import "os/user"
+
+func lookupUID(username string) (string, error) {
+	u, err := user.Lookup(username)
+	if err != nil {
+		return "", err
+	}
+	return u.Uid, err
+}
+
+func lookupGID(name string) (string, error) {
+	g, err := user.LookupGroup(name)
+	if err != nil {
+		return "", err
+	}
+	return g.Gid, err
+}