[PATCH 3/3] local_tzoffset: detect errors from tm_to_time_t
- From
Jeff King <peff@peff.net>
- Date
- Jun 20, 2016, 21:14 UTC
- Message-ID
- <20160620211413.GB15521@sigill.intra.peff.net>
- In-Reply-To
- <20160620210901.GE3631@sigill.intra.peff.net>
When we want to know the local timezone offset at a given timestamp, we compute it by asking for localtime() at the given time, and comparing the offset to GMT at that time. However, there's some juggling between time_t and "struct tm" which happens, which involves calling our own tm_to_time_t().
If that function returns an error (e.g., because it only handles dates up to the year 2099), it returns "-1", which we treat as a time_t, and is clearly bogus, leading to bizarre timestamps (that seem to always adjust the time back to (time_t)(uint32_t)-1, in the year 2106).
It's not a good idea for local_tzoffset() to simply die here; it would make it hard to run "git log" on a repository with funny timestamps. Instead, let's just treat such cases as "zero offset".
Reported-by: Norbert Kiesel <nkiesel@gmail.com> Signed-off-by: Jeff King <peff@peff.net> --- date.c | 2 ++ t/t0006-date.sh | 5 +++++ 2 files changed, 7 insertions(+)
diff --git a/date.c b/date.c index 7c9f769..4c7aa9b 100644 --- a/date.c +++ b/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; diff --git a/t/t0006-date.sh b/t/t0006-date.sh index 57033dd..04ce535 100755 --- a/t/t0006-date.sh +++ b/t/t0006-date.sh @@ -48,6 +48,11 @@ 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 -> $2" >expect test_expect_${4:-success} "parse date ($1${3:+ TZ=$3})" "
-- 2.9.0.167.g9e4667c