[PATCH v3 4/4] [BZ #16141] strptime: extend %z range to +/-9959

[James Perkins <james at loowit dot net>]

This is part of a fix for [BZ #16141] strptime %z offset restriction.

Remove limits on the strptime %z timezone range, allowing strptime to
parse time zone offsets from -9959 through +9959.

strptime supports a %z input field descriptor, which parses a time zone
offset from UTC time into the broken-out time field tm_gmtoff.  The
current implementation limits the range of valid offsets to the range
-1200 to +1200, or if only the hour digits are present, -12 to +12.
NULL is returned for offsets outside that range.

However, the limits are too small for the following use cases:

  * Present day exceeds the +1200 limit:
    - Pacific/Auckland (New Zealand) summer time is +1300.
    - Pacific/Kiritimati (Christmas Island) is +1400.
    - Pacific/Apia (Samoa) summer time is +1400.
  * Historical offsets exceeded +1500/-1500.
  * POSIX supports -2459 to +2559.
  * Offsets up to +/-9959 may occasionally be useful.
  * Paul Eggert's notes provide additional detail:
    - https://sourceware.org/ml/libc-alpha/2014-12/msg00068.html
    - https://sourceware.org/ml/libc-alpha/2014-12/msg00072.html

When 'make check' is run on glibc, tst-strptime2 will report the error
with the output:

  round 13: strptime unexpectedly failed
  round 14: strptime unexpectedly failed
  round 15: strptime unexpectedly failed
  round 16: strptime unexpectedly failed
  round 17: strptime unexpectedly failed
  round 18: strptime unexpectedly failed
  round 19: strptime unexpectedly failed
  round 20: strptime unexpectedly failed
  round 21: strptime unexpectedly failed
  round 22: strptime unexpectedly failed
  round 23: strptime unexpectedly failed
  round 24: strptime unexpectedly failed
  round 25: strptime unexpectedly failed
  round 26: strptime unexpectedly failed

The fix removes the +/-1200 range limit, permitting strptime to parse
offsets from -9959 through +9959. The tst-strptime2 test will then
succeed.

James

2014-12-03  James Perkins  james@loowit.net

	[BZ #16141]
	* time/strptime_l.c (__strptime_internal): Extend %z time zone
	offset range limits to UTC-99:59 through UTC+99:59 to parse
	current and historical use cases.

---
 time/strptime_l.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/time/strptime_l.c b/time/strptime_l.c
index be35f3b..719f757 100644
--- a/time/strptime_l.c
+++ b/time/strptime_l.c
@@ -773,8 +773,6 @@ __strptime_internal (rp, fmt, tmp, statep LOCALE_PARAM)
 	    else if (val % 100 >= 60)
 	      /* Minutes valid range is 0 through 59.  */
 	      return NULL;
-	    if (val > 1200)
-	      return NULL;
 	    tm->tm_gmtoff = (val / 100) * 3600 + (val % 100) * 60;
 	    if (neg)
 	      tm->tm_gmtoff = -tm->tm_gmtoff;
-- 
1.7.9.5