[PATCH] Accept the timezone specifiers [+-]hh:mm and [+-]hh in addition to [+-]hhmm

[Marcus Comstedt <marcus@mc.pp.se>]

ISO 8601 specifies three syntaxes for timezones other than "Z".
git already supports the +-hhmm syntax.  This patch adds support
for the other two: +-hh:mm and +-hh.

Signed-off-by: Marcus Comstedt <marcus@mc.pp.se>
---
 date.c |   39 ++++++++++++++++++++++++++-------------
 1 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/date.c b/date.c
index 6bae49c..f2cad1f 100644
--- a/date.c
+++ b/date.c
@@ -555,21 +555,34 @@ static int match_tz(const char *date, int *offp)
 	int min, hour;
 	int n = end - date - 1;
 
-	min = offset % 100;
-	hour = offset / 100;
+	if (n == 2 && offset <= 14) {
+		/* +HH:MM (ISO 8601) or +HH (ISO 8601 abbreviated) */
+		hour = offset;
+		if (date[3] == ':') {
+			min = strtoul(date + 4, &end, 10);
+			if (end != date + 6) {
+				/* there was no minute field, but we're
+				   fine with just the hour */
+				end = (char *)date + 3;
+				min = 0;
+			}
+		} else {
+			min = 0;
+		}
+	} else if (n < 3) {
+		return end - date; /* we want at least 3 digits */
+	} else {
+		min = offset % 100;
+		hour = offset / 100;
+	}
 
-	/*
-	 * Don't accept any random crap.. At least 3 digits, and
-	 * a valid minute. We might want to check that the minutes
-	 * are divisible by 30 or something too.
-	 */
-	if (min < 60 && n > 2) {
-		offset = hour*60+min;
-		if (*date == '-')
-			offset = -offset;
+	if (60 <= min)
+		return end - date; /* invalid minute */
 
-		*offp = offset;
-	}
+	offset = hour * 60 + min;
+	if (*date == '-')
+		offset = -offset;
+	*offp = offset;
 	return end - date;
 }
 
-- 
1.7.0.4