1 files changed, 73 insertions, 0 deletions
diff --git a/unix/os/gmttolst.c b/unix/os/gmttolst.c
new file mode 100644
index 00000000..cfe7c0a4
--- /dev/null
+++ b/unix/os/gmttolst.c
@@ -0,0 +1,73 @@
+/* Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+ */
+
+#include <sys/types.h>
+#ifdef SYSV
+#include <time.h>
+#else
+#include <sys/time.h>
+#include <sys/timeb.h>
+#endif
+
+#ifdef MACOSX
+#include <time.h>
+#endif
+
+#define	SECONDS_1970_TO_1980	315532800L
+static	long get_timezone();
+
+/* GMT_TO_LST -- Convert gmt to local standard time, epoch 1980.
+ */
+time_t
+gmt_to_lst (gmt)
+time_t	gmt;
+{
+	struct	tm *localtime();
+	time_t	time_var;
+	long	gmtl;
+	
+	/* Subtract seconds westward from GMT */
+	time_var = gmt - get_timezone();
+
+	/* Correct for daylight savings time, if in effect */
+	gmtl = (long)gmt;
+
+#ifndef MACOSX
+	/* Mac systems already include the DST offset in the GMT offset */
+	if (localtime(&gmtl)->tm_isdst)
+	    time_var += 60L * 60L;
+#endif
+
+	return (time_var - SECONDS_1970_TO_1980);
+}
+
+
+/* _TIMEZONE -- Get the local timezone, measured in seconds westward
+ * from Greenwich, ignoring daylight savings time if in effect.
+ */
+static long
+get_timezone()
+{
+#ifdef CYGWIN
+	extern	long _timezone;
+	tzset();
+	return (_timezone);
+#else
+#ifdef SYSV
+	extern	long timezone;
+	tzset();
+	return (timezone);
+#else
+#ifdef MACOSX
+	struct tm *tm;
+	time_t clock = time(NULL);
+	tm = localtime (&clock);
+	return (-(tm->tm_gmtoff));
+#else
+	struct timeb time_info;
+	ftime (&time_info);
+	return (time_info.timezone * 60);
+#endif
+#endif
+#endif
+}