Rewritten to handle date ranges better which lie outside the expected…

… time of day, day of month and month.

The 'struct tm' is now properly updated to reflect the time and date information which comes out of the number of seconds calculated.

A bug reported by Andreas Falkenhahn is resolved which had the effect of distorting the number of seconds calculated.

library/time_mktime.c

@@ -1,5 +1,5 @@
 /*
- * $Id: time_mktime.c,v 1.10 2006-01-08 12:04:27 obarthel Exp $
+ * $Id: time_mktime.c,v 1.11 2015-06-26 11:22:00 obarthel Exp $
  *
  * :ts=4
  *
@@ -52,9 +52,10 @@ mktime(struct tm *tm)
 {
 	DECLARE_UTILITYBASE();
 	struct ClockData clock_data;
-	ULONG seconds, delta;
+	ULONG seconds;
 	time_t result = (time_t)-1;
-	int max_month_days;
+	LONG combined_seconds;
+	int month, year;
 
 	ENTER();
 
@@ -73,116 +74,63 @@ mktime(struct tm *tm)
 	}
 	#endif /* CHECK_FOR_NULL_POINTERS */
 
-	/* The month must be valid. */
-	if(tm->tm_mon < 0 || tm->tm_mon > 11)
-	{
-		SHOWVALUE(tm->tm_mon);
-		SHOWMSG("invalid month");
-		goto out;
-	}
-
-	/* The day of the month must be valid. */
-	if(tm->tm_mday < 1 || tm->tm_mday > 31)
-	{
-		SHOWVALUE(tm->tm_mday);
-		SHOWMSG("invalid day of month");
-		goto out;
-	}
+	/* Normalize the year and month. */
+	year = tm->tm_year + 1900;
+	month = tm->tm_mon + 1;
 
-	/* The year must be valid. */
-	if(tm->tm_year < 78)
-	{
-		SHOWVALUE(tm->tm_year);
-		SHOWMSG("invalid year");
-		goto out;
-	}
-
-	/* Is this the month of February? */
-	if(tm->tm_mon == 1)
-	{
-		int year;
-
-		/* We need to have the full year number for the
-		   leap year calculation below. */
-		year = tm->tm_year + 1900;
-
-		/* Now for the famous leap year calculation rules... In
-		   the given year, how many days are there in the month
-		   of February? */
-		if((year % 4) != 0)
-			max_month_days = 28;
-		else if ((year % 400) == 0)
-			max_month_days = 29;
-		else if ((year % 100) == 0)
-			max_month_days = 28;
-		else
-			max_month_days = 29;
-	}
-	else
+	if(month < 0 || month > 12)
 	{
-		static const char days_per_month[12] =
-		{
-			31, 0,31,
-			30,31,30,
-			31,31,30,
-			31,30,31
-		};
+		int y;
 
-		max_month_days = days_per_month[tm->tm_mon];
-	}
+		y = month / 12;
 
-	/* The day of the month must be valid. */
-	if(tm->tm_mday < 0 || tm->tm_mday > max_month_days)
-	{
-		SHOWVALUE(tm->tm_mday);
-		SHOWMSG("invalid day of month");
-		goto out;
+		month -= y * 12;
+		year += y;
 	}
 
-	/* The hour must be valid. */
-	if(tm->tm_hour < 0 || tm->tm_hour > 23)
+	if(month < 1)
 	{
-		SHOWVALUE(tm->tm_hour);
-		SHOWMSG("invalid hour");
-		goto out;
+		month += 12;
+		year -= 1;
 	}
 
-	/* The minute must be valid. */
-	if(tm->tm_min < 0 || tm->tm_min > 59)
+	/* The year must be valid. Amiga time begins with January 1st, 1978. */
+	if(year < 1978)
 	{
-		SHOWVALUE(tm->tm_min);
-		SHOWMSG("invalid minute");
+		SHOWVALUE(year);
+		SHOWMSG("invalid year");
 		goto out;
 	}
 
-	/* Note: the number of seconds can be larger than 59
-	         in order to account for leap seconds. */
-	if(tm->tm_sec < 0 || tm->tm_sec > 60)
+	/* Convert the first day of the month in the given year
+	   into the corresponding number of seconds. */
+	memset(&clock_data, 0, sizeof(clock_data));
+
+	clock_data.mday		= 1;
+	clock_data.month	= month;
+	clock_data.year		= year;
+
+	seconds = Date2Amiga(&clock_data);
+
+	/* Put the combined number of seconds involved together,
+	   covering the seconds/minutes/hours of the day as well
+	   as the number of days of the month. This will be added
+	   to the number of seconds for the date. */
+	combined_seconds = tm->tm_sec + 60 * (tm->tm_min + 60 * (tm->tm_hour + 24 * (tm->tm_mday-1)));
+
+	/* If the combined number of seconds is negative, adding it
+	 * to the number of seconds for the date should not produce
+	 * a negative value.
+	 */
+	if(combined_seconds < 0 && seconds < (ULONG)(-combined_seconds))
 	{
-		SHOWVALUE(tm->tm_sec);
-		SHOWMSG("invalid seconds");
+		SHOWVALUE(seconds);
+		SHOWVALUE(combined_seconds);
+		SHOWMSG("invalid combined number of seconds");
 		goto out;
 	}
 
-	clock_data.sec		= (tm->tm_sec > 59) ? 59 : tm->tm_sec;
-	clock_data.min		= tm->tm_min;
-	clock_data.hour		= tm->tm_hour;
-	clock_data.mday		= tm->tm_mday;
-	clock_data.month	= tm->tm_mon + 1;
-	clock_data.year		= tm->tm_year + 1900;
-
-	seconds = Date2Amiga(&clock_data) + (tm->tm_sec - 59);
-
-	/* The AmigaOS "epoch" starts with January 1st, 1978, which was
-	   a Sunday. */
-	tm->tm_wday	= (seconds / (24 * 60 * 60)) % 7;
-
-	clock_data.mday		= 1;
-	clock_data.month	= 1;
-
-	delta = Date2Amiga(&clock_data);
-
-	tm->tm_yday	= (seconds - delta) / (24 * 60 * 60);
+	seconds += combined_seconds;
 
 	__locale_lock();
 
@@ -193,10 +141,13 @@ mktime(struct tm *tm)
 
 	__locale_unlock();
 
-	/* Finally, adjust for the difference between the Unix and the
+	/* Adjust for the difference between the Unix and the
 	   AmigaOS epochs, which differ by 8 years. */
 	result = seconds + UNIX_TIME_OFFSET;
 
+	/* Finally, normalize the provided time and date information. */
+	localtime_r(&result, tm);
+
  out:
 
 	RETURN(result);