Re: kern/41494

[Antti Kantee <pooka%NetBSD.org@localhost>]

On Wed May 27 2009 at 18:50:17 +0200, Nicolas Joly wrote:
> >  Try if this helps this:
> 
> No luck ... But this slightly modified version make the following
> command successful.
> 
>       find /mnt -type f | xargs cat

Duh, I meant "strlen(localbuf) == offset+1".  But I soon did realize
that the check should be "<", since the file might shrink in size between
two reads.

It's still a little busted, since there's a race where the artificial \n
doesn't get included.  But I doubt that's worth caring about, since it
requires modifying the underlying sysctl in the middle of two operations.

> Index: sysctlfs.c
> ===================================================================
> RCS file: /cvsroot/src/usr.sbin/puffs/mount_sysctlfs/sysctlfs.c,v
> retrieving revision 1.10
> diff -u -p -r1.10 sysctlfs.c
> --- sysctlfs.c        18 Jan 2009 10:10:47 -0000      1.10
> +++ sysctlfs.c        27 May 2009 16:41:29 -0000
> @@ -627,7 +627,10 @@ sysctlfs_node_read(struct puffs_usermoun
>               return EISDIR;
>  
>       doprint(sfs, &pn->pn_po, localbuf, sizeof(localbuf));
> -     xfer = MIN(*resid, strlen(localbuf) - offset);
> +     if (strlen(localbuf) < offset)
> +             xfer = 0;
> +     else
> +             xfer = MIN(*resid, strlen(localbuf) - offset);
>  
>       if (xfer <= 0)
>               return 0;
> 
> 
> -- 
> Nicolas Joly
> 
> Biological Software and Databanks.
> Institut Pasteur, Paris.