[2.4.18] Fix adjtimex when txc->modes == 0

The glibc implementation of adjtime(delta, old_delta) should return the remaining time adjustment value from adjtimex() in old_delta if that argument is non-NULL.

This is broken in the case that delta is NULL (i.e., we don't want a change, but just to find out the current time_adjust). The breakage occurs because adjtime specifies txc->modes as 0 (so that no change is made to the current offset) and in this case do_adjtimex() does not correctly return the required information in txc->offset.

The patch below (against 2.4.18pre10) seems to me the simplest way to fix the problem.

Cheers,

Michael

@@ -357,7 +357,9 @@
 	    /* p. 24, (d) */
 		result = TIME_ERROR;
 	
-	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
+	if (!txc->modes)
+	    txc->offset	   = time_adjust;
+	else if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
 	    txc->offset	   = save_adjust;
 	else {
 	    if (time_offset < 0)