Hi Paolo
On Wed, Aug 08, 2007 at 01:59:46PM -0400, Paolo Benvenuto wrote:
> Package: cron-apt
> Version: 0.6.0
> Severity: normal
>
> I have block size of 4096, and the calculation of tmpdir size overflows,
> giving a negative value
>
> if [ "$(( $(stat --file-system --format=%S $TMPDIR) * $(stat
> --file-system --format=%a $TMPDIR) / 1024 ))" -lt "$MINTMPDIRSIZE" ];
>
> the 1st. element, stat --format=%S, gives 4096, the 2nd, stat --format=%S,
> gives 1963117, the product gives -549019648 !
>
> So cron-apt is unusable: never runs because of this incorrect calculation of
> disk space.
Not good! Do you know where the limit of the overflow is? I think it is
a 32 bit integer that is used.
1963117*4096=8040927232
2^32=4294967296
2^32*2=8589934592
8040927232-8589934592=-549007360 which is in the same magnitude at least.
A way is to calculate in a different way to avoid the overflow. For example
divide by 1024 before the multiplication. However when I try this on my
own system the calculation is correct:
echo $((1963117*4096/1024))
7852468
But with dash...
$ echo $((1963117*4096/1024))
-536140
[EMAIL PROTECTED]:~$ dash
$ echo $((4096/1024*1963117))
7852468
However the sector size can be 512 so the formula need to be
$((X/512*Y/2))
And then a check on Y >
The maximum sector size of xfs is 32768, which means 32768/512=2^6.
This means that if Y >= 33554432 then we can have an overflow
in the calculation if using the new formula.
If you change the function to the code below do it work for you then?
# Check the tmpdir size and exit if the space is too small.
checktmpsize() {
# Sector size
SSIZE=$(stat --file-system --format=%S $TMPDIR)
# Number of free sectors
FSCOUNT=$(stat --file-system --format=%a $TMPDIR)
# Check to avoid overflow in calculations when using dash 2^(32-1-6)
# The number size above is got from 32768/512=2^6
if [ "$FSCOUNT" -lt 33554432 ] ; then
if [ "$(($SSIZE / 512 * $FSCOUNT / 2))" -lt "$MINTMPDIRSIZE" ]; then
echo >&2 "Error: Not enough free space in $TMPDIR."
exit 1
fi
fi
}
If it do, I'll update the package straight away.
Regards,
// Ola
> Debian Release: lenny/sid
> APT prefers unstable
> APT policy: (990, 'unstable'), (500, 'testing')
> Architecture: i386 (i686)
>
> Kernel: Linux 2.6.22-1-686 (SMP w/1 CPU core)
> Locale: LANG=es_DO.UTF-8, LC_CTYPE=es_DO.UTF-8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
>
> Versions of packages cron-apt depends on:
> ii apt 0.7.6 Advanced front-end for dpkg
> ii debianutils 2.23.1 Miscellaneous utilities specific
> t
>
> Versions of packages cron-apt recommends:
> ii cron 3.0pl1-100 management of regular background
> p
> ii liblockfile1 1.06.2 NFS-safe locking library,
> includes
> ii mailx 1:8.1.2-0.20070424cvs-1 A simple mail user agent
>
> -- no debconf information
>
>
--
--------------------- Ola Lundqvist ---------------------------
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