>Number:         5830
>Category:       bin
>Synopsis:       [PATCH] Broken date calculation in adventure
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people (Utility Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 24 10:05:01 1998
>Last-Modified:
>Originator:     Joseph Samuel Myers
>Organization:
Trinity College, University of Cambridge, UK
>Release:        NetBSD-current of 1998-07-11
>Environment:
	
[
System: Linux octomino 2.0.35 #1 Tue Jul 14 19:09:50 UTC 1998 i586 unknown
Architecture: i586
]

>Description:

This bug was found in year 2000 compliance checks on the Linux port of
the NetBSD games.  adventure computes the number of days since the
start of 1977 using a formula that completely ignores leap years:
while not specifically a year 2000 issue this is clearly broken.  The
patch below fixes this.

>How-To-Repeat:

The bug could cause problems if you save at the end of a leap year and
try to restore the next day (untested).

>Fix:

--- adventure/wizard.c	Sat Oct 11 11:49:28 1997
+++ adventure+/wizard.c	Fri Jul 24 14:06:01 1998
@@ -65,9 +65,11 @@
 
 	time(&tvec);
 	tptr = localtime(&tvec);
-	/* day since 1977  (mod leap)   */
-	*d = tptr->tm_yday + 365 * (tptr->tm_year - 77);
-	/* bug: this will overflow in the year 2066 AD                  */
+	/* day since 1977 */
+	*d = (tptr->tm_yday + 365 * (tptr->tm_year - 77)
+	      + (tptr->tm_year - 77) / 4 - (tptr->tm_year - 1) / 100
+	      + (tptr->tm_year + 299) / 400);
+	/* bug: this will overflow in the year 2066 AD (with 16 bit int) */
 	/* it will be attributed to Wm the C's millenial celebration    */
 	/* and minutes since midnite */
 	*t = tptr->tm_hour * 60 + tptr->tm_min;
>Audit-Trail:
>Unformatted: