[Plplot-cvs] SF.net SVN: plplot:[9461] trunk/lib/qsastime

[<ai...@us...>]

Revision: 9461
          http://plplot.svn.sourceforge.net/plplot/?rev=9461&view=rev
Author:   airwin
Date:     2009-02-06 00:03:55 +0000 (Fri, 06 Feb 2009)

Log Message:
-----------
Put in some precautions against overflowing MJD.

Modified Paths:
--------------
    trunk/lib/qsastime/qsastime.c
    trunk/lib/qsastime/qsastime.h

Modified: trunk/lib/qsastime/qsastime.c
===================================================================
--- trunk/lib/qsastime/qsastime.c	2009-02-05 21:08:32 UTC (rev 9460)
+++ trunk/lib/qsastime/qsastime.c	2009-02-06 00:03:55 UTC (rev 9461)
@@ -45,7 +45,7 @@
 static const int MonthStartDOY[] = {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
 static const int MonthStartDOY_L[] = {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335};
 	
-void setFromUT(int year, int month, int day, int hour, int min, double sec, MJDtime *MJD, int forceJulian)
+int setFromUT(int year, int month, int day, int hour, int min, double sec, MJDtime *MJD, int forceJulian)
 {	
 	/* convert Gregorian date plus time to MJD */
 	/* MJD measures from the start of 17 Nov 1858 */
@@ -56,6 +56,14 @@
 
         int leaps, lastyear;
 
+	/* Approximate precaution to avoid overflowing integer portion of 
+	   MJD.  MJD epoch is 1858-11-17.  The months, days, etc., portion
+	   of this calculation are only included to guard against
+	   extremely large values being used for some/all of them. */
+	if(abs(365.25*(year-1858) + 12.*(month-10) + (day-17) + hour/24. 
+	       + min/1440. + sec/86400.) > 2.e9)
+	  return 1;
+	
 	if(year <= 0)
 	{
 		/* count leap years on Julian Calendar */
@@ -104,7 +112,7 @@
 		MJD->time_sec -= extraDays * SecInDay;
 	}
 	
-	return;
+	return 0;
 }
 
 const char * getDayOfWeek( const MJDtime *MJD)

Modified: trunk/lib/qsastime/qsastime.h
===================================================================
--- trunk/lib/qsastime/qsastime.h	2009-02-05 21:08:32 UTC (rev 9460)
+++ trunk/lib/qsastime/qsastime.h	2009-02-06 00:03:55 UTC (rev 9461)
@@ -60,7 +60,7 @@
 }MJDtime;
 
 
-QSASTIMEDLLIMPEXP void setFromUT(int year, int month, int day, int hour, int min, double sec, MJDtime *MJD, int forceJulian);
+QSASTIMEDLLIMPEXP int setFromUT(int year, int month, int day, int hour, int min, double sec, MJDtime *MJD, int forceJulian);
 QSASTIMEDLLIMPEXP void breakDownMJD(int *year, int *month, int *day, int *hour, int *min, double *sec, const MJDtime *MJD, int forceJulian);
 QSASTIMEDLLIMPEXP size_t strfMJD(char * buf, size_t len, const char *format, const MJDtime *MJD, int forceJulian);
 


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