Date: Thu, 8 Jun 2006 23:00:43 GMT From: Rostislav Krasny <rosti.bsd@gmail.com> To: freebsd-rc@FreeBSD.org Subject: Re: conf/94377 : [patch] /etc/rc.d/sshd improperly tests random dev state Message-ID: <200606082300.k58N0hv8075410@freefall.freebsd.org>
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The following reply was made to PR conf/94377; it has been noted by GNATS.
From: Rostislav Krasny <rosti.bsd@gmail.com>
To: Doug White <dwhite@gumbysoft.com>
Cc: Florent Thoumie <flz@FreeBSD.org>, bug-followup@FreeBSD.org
Subject: Re: conf/94377 : [patch] /etc/rc.d/sshd improperly tests random dev
state
Date: Thu, 8 Jun 2006 22:03:58 +0300
On Thu, 8 Jun 2006 10:36:05 -0700 (PDT)
Doug White <dwhite@gumbysoft.com> wrote:
> On Thu, 8 Jun 2006, Rostislav Krasny wrote:
>
> > I've seen that patch just today, when it is already MFCed. I think it
> > could be simpler. Instead of
> >
> > [ "x${seeded}" != "x" ] && [ ${seeded} -eq 0 ]
> >
> > you can write just
> >
> > [ "${seeded}" = "0" ]
> >
> > and it will be still correct against sysctl failing and returning an
> > empty string.
>
> No, because if ${seeded} is empty, the shell interprets the test as
>
> [ = "0" ]
>
> which results in a syntax error. The 'x' in the first test is significant.
No, if ${seeded} is empty, the shell interprets the
[ "${seeded}" = "0" ]
as
[ "" = "0" ]
which has no syntax error because the ${seeded} is between the double
quotes. Try following simple script to test it:
#!/bin/sh
seeded=`sysctl -n kern.random.sys.seededdd 2>/dev/null`
echo ${seeded}
if [ "${seeded}" = "0" ]
then
echo true
else
echo false
fi
The sysctl will fail because of a wrong variable name, but no syntax
error will occur. If you remove the double quotes around the ${seeded}
only then a syntaxt error will happen.
If on CURRENT it works differently then most likely it has a bug
in sh(1).
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