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author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2021-03-22 12:51:47 +0100 |
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committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2021-03-23 10:01:29 +0100 |
commit | e5cf86ff98a21b427e1439a001d8e6b81c07b19c (patch) | |
tree | a4f31c684e2898382166f6de180ddcf0a7107c3e | |
parent | f14b80e09e225ccf7cfd8a85578b7e64c3fdebb9 (diff) | |
download | systemd-e5cf86ff98a21b427e1439a001d8e6b81c07b19c.tar.gz |
shared/calendarspec: when mktime() moves us backwards, jump forward
When trying to calculate the next firing of 'Sun *-*-* 01:00:00', we'd fall
into an infinite loop, because mktime() moves us "backwards":
Before this patch:
tm_within_bounds: good=0 2021-03-29 01:00:00 → 2021-03-29 00:00:00
tm_within_bounds: good=0 2021-03-29 01:00:00 → 2021-03-29 00:00:00
tm_within_bounds: good=0 2021-03-29 01:00:00 → 2021-03-29 00:00:00
...
We rely on mktime() normalizing the time. The man page does not say that it'll
move the time forward, but our algorithm relies on this. So let's catch this
case explicitly.
With this patch:
$ TZ=Europe/Dublin faketime 2021-03-21 build/systemd-analyze calendar --iterations=5 'Sun *-*-* 01:00:00'
Normalized form: Sun *-*-* 01:00:00
Next elapse: Sun 2021-03-21 01:00:00 GMT
(in UTC): Sun 2021-03-21 01:00:00 UTC
From now: 59min left
Iter. #2: Sun 2021-04-04 01:00:00 IST
(in UTC): Sun 2021-04-04 00:00:00 UTC
From now: 1 weeks 6 days left <---- note the 2 week jump here
Iter. #3: Sun 2021-04-11 01:00:00 IST
(in UTC): Sun 2021-04-11 00:00:00 UTC
From now: 2 weeks 6 days left
Iter. #4: Sun 2021-04-18 01:00:00 IST
(in UTC): Sun 2021-04-18 00:00:00 UTC
From now: 3 weeks 6 days left
Iter. #5: Sun 2021-04-25 01:00:00 IST
(in UTC): Sun 2021-04-25 00:00:00 UTC
From now: 1 months 4 days left
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1941335.
(cherry picked from commit 129cb6e249bef30dc33e08f98f0b27a6de976f6f)
-rw-r--r-- | src/shared/calendarspec.c | 19 | ||||
-rw-r--r-- | src/test/test-calendarspec.c | 3 | ||||
-rw-r--r-- | test/test-functions | 1 |
3 files changed, 15 insertions, 8 deletions
diff --git a/src/shared/calendarspec.c b/src/shared/calendarspec.c index 80acc57800..c8d97c3da1 100644 --- a/src/shared/calendarspec.c +++ b/src/shared/calendarspec.c @@ -1185,15 +1185,18 @@ static int tm_within_bounds(struct tm *tm, bool utc) { return negative_errno(); /* Did any normalization take place? If so, it was out of bounds before */ - bool good = t.tm_year == tm->tm_year && - t.tm_mon == tm->tm_mon && - t.tm_mday == tm->tm_mday && - t.tm_hour == tm->tm_hour && - t.tm_min == tm->tm_min && - t.tm_sec == tm->tm_sec; - if (!good) + int cmp = CMP(t.tm_year, tm->tm_year) ?: + CMP(t.tm_mon, tm->tm_mon) ?: + CMP(t.tm_mday, tm->tm_mday) ?: + CMP(t.tm_hour, tm->tm_hour) ?: + CMP(t.tm_min, tm->tm_min) ?: + CMP(t.tm_sec, tm->tm_sec); + + if (cmp < 0) + return -EDEADLK; /* Refuse to go backward */ + if (cmp > 0) *tm = t; - return good; + return cmp == 0; } static bool matches_weekday(int weekdays_bits, const struct tm *tm, bool utc) { diff --git a/src/test/test-calendarspec.c b/src/test/test-calendarspec.c index e0b7f22808..1b04186a23 100644 --- a/src/test/test-calendarspec.c +++ b/src/test/test-calendarspec.c @@ -218,6 +218,9 @@ int main(int argc, char* argv[]) { // Confirm that timezones in the Spec work regardless of current timezone test_next("2017-09-09 20:42:00 Pacific/Auckland", "", 12345, 1504946520000000); test_next("2017-09-09 20:42:00 Pacific/Auckland", "EET", 12345, 1504946520000000); + /* Check that we don't start looping if mktime() moves us backwards */ + test_next("Sun *-*-* 01:00:00 Europe/Dublin", "", 1616412478000000, 1617494400000000); + test_next("Sun *-*-* 01:00:00 Europe/Dublin", "IST", 1616412478000000, 1617494400000000); assert_se(calendar_spec_from_string("test", &c) < 0); assert_se(calendar_spec_from_string(" utc", &c) < 0); diff --git a/test/test-functions b/test/test-functions index 52b52bf29e..beaf4fae2f 100644 --- a/test/test-functions +++ b/test/test-functions @@ -1120,6 +1120,7 @@ install_zoneinfo() { inst_any /usr/share/zoneinfo/Asia/Vladivostok inst_any /usr/share/zoneinfo/Australia/Sydney inst_any /usr/share/zoneinfo/Europe/Berlin + inst_any /usr/share/zoneinfo/Europe/Dublin inst_any /usr/share/zoneinfo/Europe/Kiev inst_any /usr/share/zoneinfo/Pacific/Auckland inst_any /usr/share/zoneinfo/Pacific/Honolulu |