example: add client API example

Create a small application which calls org.freedesktop.login1
to display a list of the active users.

Change-Id: I8d7879d98f6b89a9315aa0c71b928c50490dfedb
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>

2 files changed, 35 insertions, 1 deletions

diff --git a/example/Makefile.am b/example/Makefile.am
index 8d38538..ae5cdcb 100644
--- a/example/Makefile.am
+++ b/example/Makefile.am
@@ -1,4 +1,4 @@
-noinst_PROGRAMS = calculator-server
+noinst_PROGRAMS = calculator-server list-users
 
 calculator_server_generated_files = \
 	net/poettering/Calculator/server.hpp \
@@ -14,6 +14,10 @@ calculator_server_SOURCES = \
 calculator_server_CXXFLAGS = $(SYSTEMD_CFLAGS)
 calculator_server_LDADD = $(SYSTEMD_LIBS) ../libsdbusplus.la
 
+list_users_SOURCES = list-users.cpp
+list_users_CXXFLAGS = $(SYSTEMD_CFLAGS)
+list_users_LDADD = $(SYSTEMD_LIBS) ../libsdbusplus.la
+
 BUILT_SOURCES = \
 	$(calculator_server_generated_files) \
 	$(calculator_markdown_generated_files)
diff --git a/example/list-users.cpp b/example/list-users.cpp
new file mode 100644
index 0000000..245bf63
--- /dev/null
+++ b/example/list-users.cpp
@@ -0,0 +1,30 @@
+#include <sdbusplus/bus.hpp>
+#include <iostream>
+#include <cstdint>
+
+/** An example dbus client application.
+ *  Calls org.freedesktop.login1's ListUsers interface to find all active
+ *  users in the system and displays their username.
+ */
+
+int main()
+{
+    using namespace sdbusplus;
+
+    auto b = bus::new_system();
+    auto m = b.new_method_call("org.freedesktop.login1",
+                               "/org/freedesktop/login1",
+                               "org.freedesktop.login1.Manager",
+                               "ListUsers");
+    auto reply = b.call(m);
+
+    std::vector<std::tuple<uint32_t, std::string, message::object_path>> users;
+    reply.read(users);
+
+    for(auto& user : users)
+    {
+        std::cout << std::get<std::string>(user) << "\n";
+    }
+
+    return 0;
+}