feat: add support for session bus connection at custom address (#273)

* Add methods to initiate custom session bus connection

The new function helper `createSessionBusConnectionWithAddress` allows to create connection to session bus with custom address.

Signed-off-by: Alexander Livenets <a.livenets@gmail.com>

* feat: add support for session bus connection at custom address

Co-authored-by: Stanislav Angelovic <stanislav.angelovic@siemens.com>

src/SdBus.cpp

@@ -166,14 +166,46 @@ int SdBus::sd_bus_open(sd_bus **ret)
     return ::sd_bus_open(ret);
 }
 
+int SdBus::sd_bus_open_system(sd_bus **ret)
+{
+    return ::sd_bus_open_system(ret);
+}
+
 int SdBus::sd_bus_open_user(sd_bus **ret)
 {
     return ::sd_bus_open_user(ret);
 }
 
-int SdBus::sd_bus_open_system(sd_bus **ret)
+int SdBus::sd_bus_open_user_with_address(sd_bus **ret, const char* address)
 {
-    return ::sd_bus_open_system(ret);
+    sd_bus* bus = nullptr;
+
+    int r = sd_bus_new(&bus);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_set_address(bus, address);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_set_bus_client(bus, true);
+    if (r < 0)
+        return r;
+
+    // Copying behavior from
+    // https://github.com/systemd/systemd/blob/fee6441601c979165ebcbb35472036439f8dad5f/src/libsystemd/sd-bus/sd-bus.c#L1381
+    // Here, we make the bus as trusted
+    r = sd_bus_set_trusted(bus, true);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_start(bus);
+    if (r < 0)
+        return r;
+
+    *ret = bus;
+
+    return 0;
 }
 
 int SdBus::sd_bus_open_system_remote(sd_bus **ret, const char *host)