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[PATCH 2/2] parse_date_basic(): let the system handle DST conversion

From
Junio C Hamano <gitster@pobox.com>
Date
Apr 15, 2015, 16:24 UTC
Message-ID
<xmqq618xmka9.fsf_-_@gitster.dls.corp.google.com>
In-Reply-To
<xmqqk2xdmp0e.fsf@gitster.dls.corp.google.com>

The function parses the input to compute the broken-down time in "struct tm", and the GMT timezone offset. If the timezone offset does not exist in the input, the broken-down time is turned into the number of seconds since epoch both in the current timezone and in GMT and the offset is computed as their difference.

However, we forgot to make sure tm.tm_isdst is set to -1 (i.e. let the system figure out if DST is in effect in the current timezone when turning the broken-down time to the number of seconds since epoch); it is done so at the beginning of the function, but a call to match_digit() in the function can lead to a call to gmtime_r() to clobber the field.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Diagnosed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 date.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/date.c b/date.c
index 01fd73f..8ad6cef 100644
--- a/date.c
+++ b/date.c
@@ -700,7 +700,11 @@ int parse_date_basic(const char *date, unsigned long *timestamp, int *offset)
 		return -1;
 
 	if (*offset == -1) {
-		time_t temp_time = mktime(&tm);
+		time_t temp_time;
+
+		/* gmtime_r() in match_digit() may have clobbered it */
+		tm.tm_isdst = -1;
+		temp_time = mktime(&tm);
 		if ((time_t)*timestamp > temp_time) {
 			*offset = ((time_t)*timestamp - temp_time) / 60;
 		} else {
-- 
2.4.0-rc2-165-g862640d
Previous: Junio C HamanoNext: Eric Sunshine
Message 6 of 10 in “Odd broken "--date=now" behavior in current git”
  1. Linus TorvaldsApr 15, 2015
  2. Junio C HamanoApr 15, 2015
  3. Eric SunshineApr 15, 2015
  4. Junio C HamanoApr 15, 2015
  5. 1/2 parse_date_basic(): return early when given a bogus timestampJunio C Hamano, Apr 15, 2015
  6. 2/2 parse_date_basic(): let the system handle DST conversionJunio C Hamano, Apr 15, 2015
  7. Eric SunshineApr 15, 2015
  8. Linus TorvaldsApr 15, 2015
  9. Junio C HamanoApr 15, 2015
  10. Peter KreftingApr 15, 2015

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