Ticket #43346: patch-glib-gmain-c.diff

glib/gmain.c

@@ -2647 +2647 @@
 gint64
 g_get_monotonic_time (void)
 {
-  static mach_timebase_info_data_t timebase_info;
+  static long double mach_tick_period_usec;
 
-  if (timebase_info.denom == 0)
+  if (mach_tick_period_usec == 0.0L)
     {
+      mach_timebase_info_data_t timebase_info;
+      mach_timebase_info (&timebase_info);
       /* This is a fraction that we must use to scale
        * mach_absolute_time() by in order to reach nanoseconds.
-       *
-       * We've only ever observed this to be 1/1, but maybe it could be
-       * 1000/1 if mach time is microseconds already, or 1/1000 if
-       * picoseconds.  Try to deal nicely with that.
+       * Example value: 1000000000/33330748
        */
-      mach_timebase_info (&timebase_info);
-
-      /* We actually want microseconds... */
-      if (timebase_info.numer % 1000 == 0)
-        timebase_info.numer /= 1000;
-      else
-        timebase_info.denom *= 1000;
-
-      /* We want to make the numer 1 to avoid having to multiply... */
-      if (timebase_info.denom % timebase_info.numer == 0)
-        {
-          timebase_info.denom /= timebase_info.numer;
-          timebase_info.numer = 1;
-        }
-      else
-        {
-          /* We could just multiply by timebase_info.numer below, but why
-           * bother for a case that may never actually exist...
-           *
-           * Plus -- performing the multiplication would risk integer
-           * overflow.  If we ever actually end up in this situation, we
-           * should more carefully evaluate the correct course of action.
-           */
-          mach_timebase_info (&timebase_info); /* Get a fresh copy for a better message */
-          g_error ("Got weird mach timebase info of %d/%d.  Please file a bug against GLib.",
-                   timebase_info.numer, timebase_info.denom);
-        }
+      mach_tick_period_usec = timebase_info.numer/(1000.0L*timebase_info.denom);
     }
-
-  return mach_absolute_time () / timebase_info.denom;
+  /* Assuming long double has at least 64 mantissa bits,
+   * this computation is as accurate as it can be.
+   * Result is truncated towards zero.
+   */
+  return (gint64)(mach_absolute_time () * mach_tick_period_usec);
 }
 #else
 gint64