@matheusbsbs / matheus-bagliano / commits / bab748371a

local_tzoffset: detect errors from tm_to_time_t

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> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jun 20, 2016 at 17:14 UTC bab748371a104c58058c0eff9f4073b710ce0355
2 files changed +7
date.c
+2
@@ -74,6 +74,8 @@ static int local_tzoffset(unsigned long time)
74 localtime_r(&t, &tm);
75 t_local = tm_to_time_t(&tm);
76
77 + if (t_local == -1)
78 + return 0; /* error; just use +0000 */
79 if (t_local < t) {
80 eastwest = -1;
81 offset = t - t_local;
t/t0006-date.sh
+5
@@ -48,6 +48,11 @@ check_show default "$TIME" 'Wed Jun 15 16:13:20 2016 +0200'
48 check_show raw "$TIME" '1466000000 +0200'
49 check_show iso-local "$TIME" '2016-06-15 14:13:20 +0000'
50
51 +# arbitrary time absurdly far in the future
52 +FUTURE="5758122296 -0400"
53 +check_show iso "$FUTURE" "2152-06-19 18:24:56 -0400"
54 +check_show iso-local "$FUTURE" "2152-06-19 22:24:56 +0000"
55 +
56 check_parse() {
57 echo "$1 -> $2" >expect
58 test_expect_${4:-success} "parse date ($1${3:+ TZ=$3})" "