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

[Michael Kerrisk]

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

--- linux-2.4.18/kernel/time.c	Fri Jun 14 10:17:46 2002
+++ linux-2.4.18-adjtimex/kernel/time.c	Fri Jun 14 09:48:59 2002
@@ -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)