GNU bug report logs - #21906
julian-day->date negative input breakage

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Zefram <zefram <at> fysh.org>
To: bug-guile <at> gnu.org
Subject: julian-day->date negative input breakage
Date: Fri, 13 Nov 2015 14:31:04 +0000

scheme@(guile-user)> (use-modules (srfi srfi-19))
scheme@(guile-user)> (julian-day->date 0 0)
$1 = #<date nanosecond: 0 second: 0 minute: 0 hour: 12 day: 24 month: 11 year: -4714 zone-offset: 0>
scheme@(guile-user)> (julian-day->date -1 0)
$2 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: 24 month: 11 year: -4714 zone-offset: 0>
scheme@(guile-user)> (julian-day->date -100000 0)
$3 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: -19 month: 3 year: -4987 zone-offset: 0>
scheme@(guile-user)> (julian-day->date -10000000 0)
$4 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: -30 month: 0 year: -32092 zone-offset: 0>

Observe the various erroneous field values: negative hour, negative
day-of-month, zero month.  These occur in general for various negative
JD inputs.  Not only should the conversion not produce these kinds of
values, the date structure type probably ought to reject them if they
get that far.

-zefram

Message #10 received at 21906-done <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Zefram <zefram <at> fysh.org>
Cc: 21906-done <at> debbugs.gnu.org
Subject: Re: bug#21906: julian-day->date negative input breakage
Date: Sat, 20 Oct 2018 23:20:44 -0400

Zefram <zefram <at> fysh.org> writes:

> scheme@(guile-user)> (use-modules (srfi srfi-19))
> scheme@(guile-user)> (julian-day->date 0 0)
> $1 = #<date nanosecond: 0 second: 0 minute: 0 hour: 12 day: 24 month: 11 year: -4714 zone-offset: 0>
> scheme@(guile-user)> (julian-day->date -1 0)
> $2 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: 24 month: 11 year: -4714 zone-offset: 0>
> scheme@(guile-user)> (julian-day->date -100000 0)
> $3 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: -19 month: 3 year: -4987 zone-offset: 0>
> scheme@(guile-user)> (julian-day->date -10000000 0)
> $4 = #<date nanosecond: 0 second: 0 minute: 0 hour: -12 day: -30 month: 0 year: -32092 zone-offset: 0>

This is fixed by commit a58c7abd72648f77e4ede5f62a2c4e7969bb7f95 on the
stable-2.2 branch.  I'm closing this bug, but please reopen if
appropriate.

     Thanks!
       Mark

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