On Fri, 08 Oct 2021 at 15:12:58 +0000, Thorsten Glaser wrote:
>>, so I completed your patch with 2373709bb461a71a7af46e7e9c59355fce63e52e.
>
> -blkid="$(/sbin/blkid -o value -s TYPE -p ${offset:+-O "$offset"} -- "$dev")"
> +blkid="$(/sbin/blkid -o value -s TYPE -p ${offset:+-O "$((offset*512))"} --
> "$dev")"
>
> That’s only good for offset ≤ 4194303 though and invokes C “Undefined
> Behaviour” on larger values. (More on LP64 of course.)Ah right, thanks. Given #-1 is a 12 years old bug and AFAICT you're the first to report it I suppose nobody uses large offset= values. Don't think adding ‘Depends: bc’ is justified here :-P. Also in practice I was able to use offset=2⁵⁹ with bash, dash, klibc's sh and busybox's sh on a stock 32 bytes platform, so I'll just ignore the potential overflow. I'll just make the script choke when the arithmetic operation fails. -- Guilhem.
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