Date: Sat, 18 Apr 1998 22:03:14 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: Bruce Evans <bde@zeta.org.au> Cc: cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-lib@FreeBSD.ORG, cvs-sys@FreeBSD.ORG, des@FreeBSD.ORG Subject: Re: cvs commit: src/lib/libc/sys lseek.2 src/sys/kern vfs_syscalls.c Message-ID: <Pine.BSF.3.95.980418220215.22408A-100000@current1.whistle.com> In-Reply-To: <199804190300.NAA15945@godzilla.zeta.org.au>
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If this is truely 'common' then that's unfortunate.
what do POSIX and friends have to say about it?
On Sun, 19 Apr 1998, Bruce Evans wrote:
> >des 1998/04/18 12:24:45 PDT
> >
> > Modified files:
> > lib/libc/sys lseek.2
> > Log:
> > Return EINVAL and do not changefile pointer if resulting offset is negative.
> > PR: kern/6184
> >
> > Revision Changes Path
> > 1.7 +2 -2 src/lib/libc/sys/lseek.2
> >
> > Modified files:
> > sys/kern vfs_syscalls.c
> > Log:
> > Return EINVAL and do not change file pointer if resulting offset is negative.
> > PR: kern/6184
>
> This is wrong. Please back it out. It breaks at least the ability to
> seek to high addresses in /dev/[k]mem on 64 bit systems. Not long ago
> when off_t was 32 bits, it was normal to seek to "negative" addresses in
> /dev/kmem, so portable programs should be able to handle such addresses
> at least if they actually request them. libkvm/kvm_proc.c:kvm_uread()
> shows how to handle them:
>
> errno = 0;
> if (lseek(fd, (off_t)uva, 0) == -1 && errno != 0) {
> /* Error. */
> ...
> }
> /* No error. */
> ...
>
> This allows seeking to (off_t)-1 provided the system supports it.
>
> I replied to the PR, but for some reason the followup didn't get attached
> to the PR.
>
> Bruce
>
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