test-boottime-adjtime.c

/* Test whether the adjtime() system call used by NTP affects the length of
 * each CLOCK_BOOTTIME second (rather than just the length of each
 * CLOCK_REALTIME second) by printing the value of CLOCK_BOOTTIME once every
 * second, using a CLOCK_BOOTTIME timer. You're expected to get NTP to do
 * adjustments externally. boottime-source.c and boottime-source.h are from
 * https://github.com/endlessm/eos-payg
 * Here are the compile commands used:
 * gcc -c boottime-source.c `pkg-config --cflags --libs glib-2.0`
 * gcc test-boottime-adjtime.c boottime-source.o `pkg-config --cflags --libs glib-2.0 gio-2.0`
 **/

#include <gio/gio.h>
#include <glib.h>
#include <glib-object.h>

#include "boottime-source.h"

gint64 prev_prev_time;
gint64 prev_time;

static gboolean
timeout_cb (gpointer data)
{
  gint64 time = epg_get_boottime ();
  prev_prev_time = prev_time;
  prev_time = time;
  g_print ("Time = %" G_GINT64_FORMAT " (%" G_GINT64_FORMAT " seconds)\n", time, time / 1000000);
  g_print ("Delta = %" G_GINT64_FORMAT "\n", (prev_time - prev_prev_time));
  return G_SOURCE_CONTINUE;
}

int main(int argc, char **argv)
{
  g_autoptr(GError) error = NULL;
  g_autoptr(GSource) s = epg_boottime_source_new (1000, &error);
  if (s == NULL)
    {
      g_warning ("%s", error->message);
      return 1;
    }
  g_source_set_callback (s, timeout_cb, NULL, NULL);
  g_source_attach (s, NULL);

  while (TRUE)
    g_main_context_iteration (NULL, TRUE);

  return 0;
}