+/* Compute Y - X and return the result in milliseconds.
+ * Approximately the same as this code:
+ * http://www.mpp.mpg.de/~huber/util/timevaldiff.c
+ */
+static int64_t
+timeval_diff (const struct timeval *x, const struct timeval *y)
+{
+ int64_t msec;
+
+ msec = (y->tv_sec - x->tv_sec) * 1000;
+ msec += (y->tv_usec - x->tv_usec) / 1000;
+ return msec;
+}
+
+static void
+print_timestamped_message (guestfs_h *g, const char *fs, ...)
+{
+ va_list args;
+ char *msg;
+ int err;
+ struct timeval tv, diff;
+
+ va_start (args, fs);
+ err = vasprintf (&msg, fs, args);
+ va_end (args);
+
+ if (err < 0) return;
+
+ gettimeofday (&tv, NULL);
+
+ fprintf (stderr, "[%05" PRIi64 "ms] %s\n",
+ timeval_diff (&g->launch_t, &tv), msg);
+
+ free (msg);
+}
+