[PATCH 1/2] tm_to_time_t(): allow times in year 1969

[Junio C Hamano <gitster@pobox.com>]

We used to reject anything older than January 1st 1970 regardless of the
timezone, but in order to parse UNIX epoch in zones west of GMT, we need
to allow the time without zone to be a little bit into 1969.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 date.c |   16 ++++++++--------
 1 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/date.c b/date.c
index 409a17d..5d259af 100644
--- a/date.c
+++ b/date.c
@@ -6,6 +6,7 @@
 
 #include "cache.h"
 
+#define BAD_STRUCT_TM (-400*24*60*60)
 /*
  * This is like mktime, but without normalization of tm_wday and tm_yday.
  */
@@ -18,10 +19,10 @@ time_t tm_to_time_t(const struct tm *tm)
 	int month = tm->tm_mon;
 	int day = tm->tm_mday;
 
-	if (year < 0 || year > 129) /* algo only works for 1970-2099 */
-		return -1;
+	if (year < -1 || year > 129) /* algo only works for 1969-2099 */
+		return BAD_STRUCT_TM;
 	if (month < 0 || month > 11) /* array bounds */
-		return -1;
+		return BAD_STRUCT_TM;
 	if (month < 2 || (year + 2) % 4)
 		day--;
 	return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
@@ -337,7 +338,7 @@ static int is_date(int year, int month, int day, struct tm *now_tm, time_t now,
 				return 1;
 			r->tm_year = now_tm->tm_year;
 		}
-		else if (year >= 1970 && year < 2100)
+		else if (year >= 1969 && year < 2100)
 			r->tm_year = year - 1900;
 		else if (year > 70 && year < 100)
 			r->tm_year = year;
@@ -611,12 +612,11 @@ int parse_date(const char *date, char *result, int maxlen)
 
 	/* mktime uses local timezone */
 	then = tm_to_time_t(&tm);
-	if (offset == -1)
-		offset = (then - mktime(&tm)) / 60;
-
-	if (then == -1)
+	if (then == BAD_STRUCT_TM)
 		return -1;
 
+	if (offset == -1)
+		offset = (then - mktime(&tm)) / 60;
 	if (!tm_gmt)
 		then -= offset * 60;
 	return date_string(then, offset, result, maxlen);
-- 
1.6.3.3.412.gf581d