New. Like mktime(3), but assumes the input time is UTC.

	* e-time-utils.c (e_mktime_utc): New. Like mktime(3), but assumes
	the input time is UTC.
	(e_localtime_with_offset): New. Like localtime_r(3), but also
	returns an offset from UTC.

svn path=/trunk/; revision=17971

3 files changed, 68 insertions, 5 deletions

diff --git a/e-util/ChangeLog b/e-util/ChangeLog
index 47b9bf138e..c58ab2ef73 100644
--- a/e-util/ChangeLog
+++ b/e-util/ChangeLog
@@ -1,3 +1,10 @@
+2002-09-04  Dan Winship  <danw@ximian.com>
+
+	* e-time-utils.c (e_mktime_utc): New. Like mktime(3), but assumes
+	the input time is UTC.
+	(e_localtime_with_offset): New. Like localtime_r(3), but also
+	returns an offset from UTC.
+
 2002-08-29  Dan Winship  <danw@ximian.com>
 
 	* e-list.c (e_list_destroy): Don't call g_list_foreach with the
diff --git a/e-util/e-time-utils.c b/e-util/e-time-utils.c
index f91695f977..ecc3fc9602 100644
--- a/e-util/e-time-utils.c
+++ b/e-util/e-time-utils.c
@@ -10,13 +10,17 @@
 
 #include <config.h>
 
-/* We need this for strptime. */
-#define _XOPEN_SOURCE 500
-#define __USE_XOPEN
+#ifdef __linux__
+/* We need this to get a prototype for strptime. */
+#define _GNU_SOURCE
+#endif /* __linux__ */
+
 #include <time.h>
 #include <sys/time.h>
-#undef _XOPEN_SOURCE
-#undef __USE_XOPEN
+
+#ifdef __linux__
+#undef _GNU_SOURCE
+#endif /* __linux__ */
 
 #include <string.h>
 #include <ctype.h>
@@ -426,3 +430,50 @@ e_time_format_time			(struct tm	*date_tm,
 	if (strftime (buffer, buffer_size, format, date_tm) == 0)
 		buffer[0] = '\0';
 }
+
+
+/* Like mktime(3), but assumes UTC instead of local timezone. */
+time_t
+e_mktime_utc (struct tm *tm)
+{
+	time_t tt;
+
+	tm->tm_isdst = -1;
+	tt = mktime (tm);
+
+#if defined (HAVE_TM_GMTOFF)
+	tt += tm->tm_gmtoff;
+#elif defined (HAVE_TIMEZONE)
+	if (tm->tm_isdst > 0) {
+  #if defined (HAVE_ALTZONE)
+		tt -= altzone;
+  #else /* !defined (HAVE_ALTZONE) */
+		tt -= (timezone - 3600);
+  #endif
+	} else
+		tt -= timezone;
+#endif
+
+	return tt;
+}
+
+/* Like localtime_r(3), but also returns an offset in minutes after UTC.
+   (Calling gmtime with tt + offset would generate the same tm) */
+void
+e_localtime_with_offset (time_t tt, struct tm *tm, int *offset)
+{
+	localtime_r (&tt, tm);
+
+#if defined (HAVE_TM_GMTOFF)
+	*offset = tm->tm_gmtoff;
+#elif defined (HAVE_TIMEZONE)
+	if (tm->tm_isdst > 0) {
+  #if defined (HAVE_ALTZONE)
+		*offset = -altzone;
+  #else /* !defined (HAVE_ALTZONE) */
+		*offset = -(timezone - 3600);
+  #endif
+	} else
+		*offset = -timezone;
+#endif
+}
diff --git a/e-util/e-time-utils.h b/e-util/e-time-utils.h
index f6d85df5ac..0b081dadd4 100644
--- a/e-util/e-time-utils.h
+++ b/e-util/e-time-utils.h
@@ -48,6 +48,11 @@ void e_time_format_time				(struct tm	*date_tm,
 						 int		 buffer_size);
 
 
+/* Like mktime(3), but assumes UTC instead of local timezone. */
+time_t e_mktime_utc (struct tm *timeptr);
 
+/* Like localtime_r(3), but also returns an offset in minutes after UTC.
+   (Calling gmtime with tt + offset would generate the same tm) */
+void e_localtime_with_offset (time_t tt, struct tm *tm, int *offset);
 
 #endif /* E_TIME_UTILS */