Update offset correction errors only when needed

local.c

@@ -349,13 +349,8 @@ LCL_CookTime(struct timeval *raw, struct timeval *cooked, double *err)
 void
 LCL_GetOffsetCorrection(struct timeval *raw, double *correction, double *err)
 {
-  double e;
-
   /* Call system specific driver to get correction */
-  (*drv_offset_convert)(raw, correction, &e);
-
-  if (err)
-    *err = e;
+  (*drv_offset_convert)(raw, correction, err);
 }
 
 /* ================================================== */

sys_linux.c

@@ -800,7 +800,6 @@ get_offset_correction(struct timeval *raw,
       slow_slewing = 0;
     }
   }
-  update_slow_slew_error(offset);
 
   if (!nano_slewing) {
     noffset = 0;
@@ -812,7 +811,6 @@ get_offset_correction(struct timeval *raw,
       nano_slewing = 0;
     }
   }
-  update_nano_slew_error(noffset, 0);
 
   if (fast_slewing) {
     UTI_DiffTimevalsToDouble(&fast_slew_duration, raw, &slew_start_tv);
@@ -824,7 +822,12 @@ get_offset_correction(struct timeval *raw,
   }  
 
   *corr = - (offset_register + fast_slew_remaining) + offset / 1.0e6 + noffset / 1.0e9;
+
+  if (err) {
+    update_slow_slew_error(offset);
+    update_nano_slew_error(noffset, 0);
     *err = get_slow_slew_error(raw) + get_fast_slew_error(raw) + get_nano_slew_error();;
+  }
 
   return;
 }

sys_netbsd.c

@@ -271,6 +271,7 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
+  if (err)
     *err = 0.0;
 }
 

sys_solaris.c

@@ -300,6 +300,7 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
+  if (err)
     *err = 0.0;
   return;
 }

sys_sunos.c

@@ -287,6 +287,7 @@ get_offset_correction(struct timeval *raw,
   stop_adjust();
   *corr = -offset_register;
   start_adjust();
+  if (err)
     *err = 0.0;
   return;
 }