Merge branch 'jk/tzoffset-fix' into maint

The internal code used to show local timezone offset is not
prepared to handle timestamps beyond year 2100, and gave a
bogus offset value to the caller.  Use a more benign looking
+0000 instead and let "git log" going in such a case, instead
of aborting.

* jk/tzoffset-fix:
  local_tzoffset: detect errors from tm_to_time_t
  t0006: test various date formats
  t0006: rename test-date's "show" to "relative"

date.c

@@ -74,6 +74,8 @@ static int local_tzoffset(unsigned long time)
 	localtime_r(&t, &tm);
 	t_local = tm_to_time_t(&tm);
 
+	if (t_local == -1)
+		return 0; /* error; just use +0000 */
 	if (t_local < t) {
 		eastwest = -1;
 		offset = t - t_local;

t/helper/test-date.c

@@ -1,11 +1,12 @@
 #include "cache.h"
 
 static const char *usage_msg = "\n"
-"  test-date show [time_t]...\n"
+"  test-date relative [time_t]...\n"
+"  test-date show:<format> [time_t]...\n"
 "  test-date parse [date]...\n"
 "  test-date approxidate [date]...\n";
 
-static void show_dates(char **argv, struct timeval *now)
+static void show_relative_dates(char **argv, struct timeval *now)
 {
 	struct strbuf buf = STRBUF_INIT;
 
@@ -17,6 +18,29 @@ static void show_dates(char **argv, struct timeval *now)
 	strbuf_release(&buf);
 }
 
+static void show_dates(char **argv, const char *format)
+{
+	struct date_mode mode;
+
+	parse_date_format(format, &mode);
+	for (; *argv; argv++) {
+		char *arg = *argv;
+		time_t t;
+		int tz;
+
+		/*
+		 * Do not use our normal timestamp parsing here, as the point
+		 * is to test the formatting code in isolation.
+		 */
+		t = strtol(arg, &arg, 10);
+		while (*arg == ' ')
+			arg++;
+		tz = atoi(arg);
+
+		printf("%s -> %s\n", *argv, show_date(t, tz, &mode));
+	}
+}
+
 static void parse_dates(char **argv, struct timeval *now)
 {
 	struct strbuf result = STRBUF_INIT;
@@ -61,8 +85,10 @@ int main(int argc, char **argv)
 	argv++;
 	if (!*argv)
 		usage(usage_msg);
-	if (!strcmp(*argv, "show"))
-		show_dates(argv+1, &now);
+	if (!strcmp(*argv, "relative"))
+		show_relative_dates(argv+1, &now);
+	else if (skip_prefix(*argv, "show:", &x))
+		show_dates(argv+1, x);
 	else if (!strcmp(*argv, "parse"))
 		parse_dates(argv+1, &now);
 	else if (!strcmp(*argv, "approxidate"))

t/t0006-date.sh

@@ -6,26 +6,52 @@ test_description='test date parsing and printing'
 # arbitrary reference time: 2009-08-30 19:20:00
 TEST_DATE_NOW=1251660000; export TEST_DATE_NOW
 
-check_show() {
+check_relative() {
 	t=$(($TEST_DATE_NOW - $1))
 	echo "$t -> $2" >expect
 	test_expect_${3:-success} "relative date ($2)" "
-	test-date show $t >actual &&
+	test-date relative $t >actual &&
 	test_i18ncmp expect actual
 	"
 }
 
-check_show 5 '5 seconds ago'
-check_show 300 '5 minutes ago'
-check_show 18000 '5 hours ago'
-check_show 432000 '5 days ago'
-check_show 1728000 '3 weeks ago'
-check_show 13000000 '5 months ago'
-check_show 37500000 '1 year, 2 months ago'
-check_show 55188000 '1 year, 9 months ago'
-check_show 630000000 '20 years ago'
-check_show 31449600 '12 months ago'
-check_show 62985600 '2 years ago'
+check_relative 5 '5 seconds ago'
+check_relative 300 '5 minutes ago'
+check_relative 18000 '5 hours ago'
+check_relative 432000 '5 days ago'
+check_relative 1728000 '3 weeks ago'
+check_relative 13000000 '5 months ago'
+check_relative 37500000 '1 year, 2 months ago'
+check_relative 55188000 '1 year, 9 months ago'
+check_relative 630000000 '20 years ago'
+check_relative 31449600 '12 months ago'
+check_relative 62985600 '2 years ago'
+
+check_show () {
+	format=$1
+	time=$2
+	expect=$3
+	test_expect_${4:-success} "show date ($format:$time)" '
+		echo "$time -> $expect" >expect &&
+		test-date show:$format "$time" >actual &&
+		test_cmp expect actual
+	'
+}
+
+# arbitrary but sensible time for examples
+TIME='1466000000 +0200'
+check_show iso8601 "$TIME" '2016-06-15 16:13:20 +0200'
+check_show iso8601-strict "$TIME" '2016-06-15T16:13:20+02:00'
+check_show rfc2822 "$TIME" 'Wed, 15 Jun 2016 16:13:20 +0200'
+check_show short "$TIME" '2016-06-15'
+check_show default "$TIME" 'Wed Jun 15 16:13:20 2016 +0200'
+check_show raw "$TIME" '1466000000 +0200'
+check_show iso-local "$TIME" '2016-06-15 14:13:20 +0000'
+
+# arbitrary time absurdly far in the future
+FUTURE="5758122296 -0400"
+check_show iso       "$FUTURE" "2152-06-19 18:24:56 -0400"
+check_show iso-local "$FUTURE" "2152-06-19 22:24:56 +0000"
 
 check_parse() {
 	echo "$1 -> $2" >expect