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[PATCH] mktime: systematically normalize tm_isdst comparisons
From: |
Paul Eggert |
Subject: |
[PATCH] mktime: systematically normalize tm_isdst comparisons |
Date: |
Sat, 29 Jan 2011 23:02:40 -0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7 |
---
ChangeLog | 8 ++++++++
lib/mktime.c | 18 ++++++++++++------
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 362c33f..0277dcd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
2011-01-29 Paul Eggert <address@hidden>
+ mktime: systematically normalize tm_isdst comparisons
+ * lib/mktime.c (isdst_differ): New function.
+ (__mktime_internal): Use it systematically for all isdst comparisons.
+ This completes the fix for libc BZ #6723, and removes the need for
+ normalizing tm_isdst. See
+ <http://sourceware.org/bugzilla/show_bug.cgi?id=6723>
+ (not_equal_tm) [DEBUG]: Use isdst_differ here, too.
+
mktime: fix some integer overflow issues and sidestep the rest
This was prompted by a bug report by Benjamin Lindner for MinGW
diff --git a/lib/mktime.c b/lib/mktime.c
index 6eb9bfc..ef49814 100644
--- a/lib/mktime.c
+++ b/lib/mktime.c
@@ -171,6 +171,14 @@ 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.
@@ -356,9 +364,7 @@ __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;
@@ -488,7 +494,7 @@ __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.
@@ -526,7 +532,7 @@ __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. */
@@ -602,7 +608,7 @@ 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
--
1.7.3
- [PATCH] mktime: systematically normalize tm_isdst comparisons,
Paul Eggert <=