From 01af8148442c445859aa9a3cc97e7c95c948107f Mon Sep 17 00:00:00 2001
From: Wouter Wijngaards <wouter@nlnetlabs.nl>
Date: Fri, 23 May 2008 15:43:55 +0000
Subject: [PATCH] gmtime_r threadsafe.

git-svn-id: file:///svn/unbound/trunk@1099 be551aaa-1e26-0410-a405-d3ace91eadb9
---
 compat/gmtime_r.c | 116 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 112 insertions(+), 4 deletions(-)

diff --git a/compat/gmtime_r.c b/compat/gmtime_r.c
index 2588ad85c..231d37e93 100644
--- a/compat/gmtime_r.c
+++ b/compat/gmtime_r.c
@@ -1,12 +1,120 @@
+/*
+ * Taken from FreeBSD src / lib / libc / stdtime / localtime.c 1.43 revision.
+ * localtime.c 7.78.
+ * tzfile.h 1.8
+ * adapted to be replacement gmtime_r.
+ */
 #include "config.h"
 
 #ifdef HAVE_TIME_H
 #include <time.h>
 #endif
 
-struct tm *gmtime_r(const time_t *timep, struct tm *result)
+#define MONSPERYEAR 12
+#define DAYSPERNYEAR 365
+#define DAYSPERLYEAR 366
+#define SECSPERMIN 60
+#define SECSPERHOUR (60*60)
+#define SECSPERDAY (24*60*60)
+#define DAYSPERWEEK 7
+#define TM_SUNDAY	0
+#define TM_MONDAY	1
+#define TM_TUESDAY	2
+#define TM_WEDNESDAY	3
+#define TM_THURSDAY	4
+#define TM_FRIDAY	5
+#define TM_SATURDAY	6
+
+#define TM_JANUARY	0
+#define TM_FEBRUARY	1
+#define TM_MARCH	2
+#define TM_APRIL	3
+#define TM_MAY		4
+#define TM_JUNE		5
+#define TM_JULY		6
+#define TM_AUGUST	7
+#define TM_SEPTEMBER	8
+#define TM_OCTOBER	9
+#define TM_NOVEMBER	10
+#define TM_DECEMBER	11
+
+#define TM_YEAR_BASE	1900
+
+#define EPOCH_YEAR	1970
+#define EPOCH_WDAY	TM_THURSDAY
+
+#define isleap(y) (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
+
+static const int	mon_lengths[2][MONSPERYEAR] = {
+	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+};
+
+static const int	year_lengths[2] = {
+	DAYSPERNYEAR, DAYSPERLYEAR
+};
+
+static void
+timesub(timep, offset, tmp)
+const time_t * const			timep;
+const long				offset;
+struct tm * const		tmp;
+{
+	long			days;
+	long			rem;
+	long			y;
+	int			yleap;
+	const int *		ip;
+
+	days = *timep / SECSPERDAY;
+	rem = *timep % SECSPERDAY;
+	rem += (offset);
+	while (rem < 0) {
+		rem += SECSPERDAY;
+		--days;
+	}
+	while (rem >= SECSPERDAY) {
+		rem -= SECSPERDAY;
+		++days;
+	}
+	tmp->tm_hour = (int) (rem / SECSPERHOUR);
+	rem = rem % SECSPERHOUR;
+	tmp->tm_min = (int) (rem / SECSPERMIN);
+	/*
+	** A positive leap second requires a special
+	** representation.  This uses "... ??:59:60" et seq.
+	*/
+	tmp->tm_sec = (int) (rem % SECSPERMIN) ;
+	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
+	if (tmp->tm_wday < 0)
+		tmp->tm_wday += DAYSPERWEEK;
+	y = EPOCH_YEAR;
+#define LEAPS_THRU_END_OF(y)	((y) / 4 - (y) / 100 + (y) / 400)
+	while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
+		long	newy;
+
+		newy = y + days / DAYSPERNYEAR;
+		if (days < 0)
+			--newy;
+		days -= (newy - y) * DAYSPERNYEAR +
+			LEAPS_THRU_END_OF(newy - 1) -
+			LEAPS_THRU_END_OF(y - 1);
+		y = newy;
+	}
+	tmp->tm_year = y - TM_YEAR_BASE;
+	tmp->tm_yday = (int) days;
+	ip = mon_lengths[yleap];
+	for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
+		days = days - (long) ip[tmp->tm_mon];
+	tmp->tm_mday = (int) (days + 1);
+	tmp->tm_isdst = 0;
+}
+
+/*
+* Re-entrant version of gmtime.
+*/
+struct tm * gmtime_r(const time_t* timep, struct tm *tm)
 {
-	/* no thread safety. */
-	*result = *gmtime(timep);
-	return result;
+	timesub(timep, 0L, tm);
+	return tm;
 }
-- 
2.47.2