sd-bus API, sd_bus_request_name returns Permission denied

Question

bus APIs in systemd 221. When I request a name for an object in system bus it prints out an error saying "Permission denied". I am running the output file as root. The line "sd_bus_request_name(bus, "net.poettering.Calculator", 0)" throws an error : "Failed to acquire servie name..: Permission denied"

I think root should have a permission to acquire a name for an object. Does any one know how to solve this?

thank you in advance.

Here is the example code from http://0pointer.net/blog/the-new-sd-bus-api-of-systemd.html :

int main(int argc, char *argv[]) {
sd_bus_slot *slot = NULL;
sd_bus *bus = NULL;
int r;

r = sd_bus_default_system(&bus);
if (r < 0) {
    fprintf(stderr, "Failed to connect to system bus: %s\n", strerror(-r));
    goto finish;
}

/* Install the object */
r = sd_bus_add_object_vtable(bus,
                             &slot,
                             "/net/poettering/Calculator",
                             "net.poettering.Calculator",   /* interface name                             */calculator_vtable,
                             NULL);
if (r < 0) {
    fprintf(stderr, "Failed to issue method call: %s\n", strerror(-r));
    goto finish;
}

/* Take a well-known service name so that clients can find us */
r = sd_bus_request_name(bus, "net.poettering.Calculator", 0);
if (r < 0) {
    fprintf(stderr, "Failed to acquire service name: %s\n", strerror(-r));
    goto finish;
} 

Answer 1

Typical default D-Bus configuration does not allow to register services except explicitly allowed. You need to allow root to register your service. Create /etc/dbus-1/system.d/net.poettering.Calculator.conf:

<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy user="root">
    <allow own="net.poettering.Calculator"/>
  </policy>
</busconfig>

Read man dbus-daemon for details.