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| author | Paul Eggert <eggert@cs.ucla.edu> | 2012-03-16 03:14:03 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2012-05-23 14:36:24 -0700 |
| commit | ce73d683974b3efc9e477cecb62d178e12cd1421 (patch) | |
| tree | d4cbc6e969953e3e43c917892c28f4cb6a908d31 /time | |
| parent | 72a22e596cb1359fc7e05de6d5de6f35f3eb5785 (diff) | |
| download | glibc-ce73d683974b3efc9e477cecb62d178e12cd1421.tar.gz glibc-ce73d683974b3efc9e477cecb62d178e12cd1421.tar.xz glibc-ce73d683974b3efc9e477cecb62d178e12cd1421.zip | |
mktime: do not assume signed right shift propagates sign bit
* time/mktime.c (isdst_differ): New static function. (__mktime_internal): No need to normalize tm_isdst now. (__mktime_internal, not_equal_tm): Use isdst_differ to compare tm_isdst values.
Diffstat (limited to 'time')
| -rw-r--r-- | time/mktime.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/time/mktime.c b/time/mktime.c index 61b230833e..dd7daaf948 100644 --- a/time/mktime.c +++ b/time/mktime.c @@ -177,6 +177,14 @@ const unsigned short int __mon_yday[2][13] = # include "mktime-internal.h" #endif +/* Return 1 if the values A and B differ according to the rules for + tm_isdst: A and B differ if one is zero and the other positive. */ +static int +isdst_differ (int a, int b) +{ + return (!a != !b) && (0 <= a) && (0 <= b); +} + /* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) - (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks were not adjusted between the time stamps. @@ -362,9 +370,7 @@ __mktime_internal (struct tm *tp, int mday = tp->tm_mday; int mon = tp->tm_mon; int year_requested = tp->tm_year; - /* Normalize the value. */ - int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1)) - | (tp->tm_isdst != 0)); + int isdst = tp->tm_isdst; /* 1 if the previous probe was DST. */ int dst2; @@ -494,7 +500,7 @@ __mktime_internal (struct tm *tp, /* We have a match. Check whether tm.tm_isdst has the requested value, if any. */ - if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst) + if (isdst_differ (isdst, tm.tm_isdst)) { /* tm.tm_isdst has the wrong value. Look for a neighboring time with the right value, and use its UTC offset. @@ -532,7 +538,7 @@ __mktime_internal (struct tm *tp, time_t ot = t + delta * direction; struct tm otm; ranged_convert (convert, &ot, &otm); - if (otm.tm_isdst == isdst) + if (! isdst_differ (isdst, otm.tm_isdst)) { /* We found the desired tm_isdst. Extrapolate back to the desired time. */ @@ -608,7 +614,7 @@ not_equal_tm (const struct tm *a, const struct tm *b) | (a->tm_mon ^ b->tm_mon) | (a->tm_year ^ b->tm_year) | (a->tm_yday ^ b->tm_yday) - | (a->tm_isdst ^ b->tm_isdst)); + | isdst_differ (a->tm_isdst, b->tm_isdst)); } static void |