[libdbus-1][c++] NameHasOwner

dbus-has-owner.cpp

#include <iostream>
#include <string>

#include <dbus/dbus.h>

DBusMessage *sendDBusMessage(DBusMessage *msg)
{
    DBusError err;
    DBusConnection *con;

    dbus_error_init(&err);
    con = dbus_bus_get(DBUS_BUS_SYSTEM, &err);
    if (dbus_error_is_set(&err)) {
        std::cerr << err.message << std::endl;
        dbus_error_free(&err);
        return nullptr;
    }
    if (con == nullptr)
        return nullptr;

    DBusMessage *ret = dbus_connection_send_with_reply_and_block(
            con, msg, -1, &err);
    dbus_connection_unref(con);
    if (dbus_error_is_set(&err)) {
        std::cerr << err.message << std::endl;
        dbus_error_free(&err);
        return nullptr;
    }

    return ret;
}

bool nameHasOwner(const char *name)
{
    DBusMessage *msg = dbus_message_new_method_call(
            "org.freedesktop.DBus",
            "/org/freedesktop/dbus",
            "org.freedesktop.DBus",
            "NameHasOwner");

    dbus_message_append_args(
            msg,
            DBUS_TYPE_STRING, &name,
            DBUS_TYPE_INVALID);

    DBusMessage *reply = sendDBusMessage(msg);
    dbus_message_unref(msg);
    if (reply == nullptr)
        return false;

    DBusError err;
    dbus_error_init(&err);
    if (dbus_set_error_from_message(&err, reply)) {
        std::cerr << err.message << std::endl;
        dbus_error_free(&err);
        return false;
    }

    dbus_bool_t ret;
    dbus_message_get_args(
            reply, &err,
            DBUS_TYPE_BOOLEAN, &ret,
            DBUS_TYPE_INVALID);
    dbus_message_unref(reply);

    if (dbus_error_is_set(&err)) {
        std::cerr << err.message << std::endl;
        dbus_error_free(&err);
        return false;
    }

    return ret == TRUE;
}

int main(int argc, char *argv[])
{
    if (argc != 2) {
        std::cerr << "usage: " << argv[0] << " NAME\n";
        return 1;
    }

    std::cout
        << std::boolalpha
        << argv[1] << ": " << nameHasOwner(argv[1]) << std::endl;
    return 0;
}

Makefile

CXXFLAGS = -Wall -Wextra $(shell pkg-config --cflags --libs dbus-1) -std=c++11
TGT = dbus-has-owner

$(TGT): $(TGT).cpp
	$(CXX) $(TGT).cpp $(CXXFLAGS) -o $(TGT)

clean:
	rm -f $(TGT)