Date: Wed, 28 Feb 2007 09:52:44 +0200 From: Vasil Dimov <vd@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Daniel Crandall <dcrandall@simplestar.com>, bug-followup@FreeBSD.org, freebsd-amd64@freebsd.org, rwatson@freebsd.org, wollman@freebsd.org, kensmith@freebsd.org Subject: Re: amd64/109584: zdump doesn't work Message-ID: <20070228075244.GA36076@qlovarnika.bg.datamax> In-Reply-To: <20070228064337.GA34966@qlovarnika.bg.datamax> References: <200702271920.l1RJK8fo042824@freefall.freebsd.org> <200702271454.14774.jhb@freebsd.org> <20070228064337.GA34966@qlovarnika.bg.datamax>
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On Wed, Feb 28, 2007 at 08:43:37 +0200, Vasil Dimov wrote:
[...]
> it hangs in this loop:
>
> src/lib/libc/stdtime/localtime.c:
> 1320 y = EPOCH_YEAR;
> 1321 #define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
> 1322 while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
> 1323 long newy;
> 1324
> 1325 newy = y + days / DAYSPERNYEAR;
> 1326 if (days < 0)
> 1327 --newy;
> 1328 days -= (newy - y) * DAYSPERNYEAR +
> 1329 LEAPS_THRU_END_OF(newy - 1) -
> 1330 LEAPS_THRU_END_OF(y - 1);
> 1331 y = newy;
> 1332 }
>
> where days oscillates between -1 and 365, y and newy between
> -292277022654 and -292277022655. E.g. try so see what happens if you
> enter the loop with days=365 and y=-292277022655.
What about this patch:
--- localtime.c_infloop.diff begins here ---
Index: localtime.c
===================================================================
RCS file: /home/ncvs/src/lib/libc/stdtime/localtime.c,v
retrieving revision 1.41
diff -u -r1.41 localtime.c
--- localtime.c 19 Jan 2007 01:16:35 -0000 1.41
+++ localtime.c 28 Feb 2007 07:40:24 -0000
@@ -1326,8 +1326,8 @@
if (days < 0)
--newy;
days -= (newy - y) * DAYSPERNYEAR +
- LEAPS_THRU_END_OF(newy - 1) -
- LEAPS_THRU_END_OF(y - 1);
+ LEAPS_THRU_END_OF(newy - (newy > 0 ? 1 : -1)) -
+ LEAPS_THRU_END_OF(y - (y > 0 ? 1 : -1));
y = newy;
}
tmp->tm_year = y - TM_YEAR_BASE;
--- localtime.c_infloop.diff ends here ---
--
Vasil Dimov
gro.DSBeerF@dv
%
Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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