bug#64392: cksum: escaping issues of --check output

[Pádraig Brady]

On 01/07/2023 01:10, Christoph Anton Mitterer wrote:
> Hey.
>
> It seems to me that the output of --check mode in cksum (and likely
> also in md5sum and friends) suffers from improper escaping (which,
> IIRC, is not even documented for that output... but may be wrong):
>
> $ touch a $'new\nline' '\n' z
> $ ls -al
> total 0
> drwxr-xr-x 1 calestyo calestyo  24 Jul  1 02:01  .
> drwxr-xr-x 1 calestyo calestyo 176 Jul  1 01:48  ..
> -rw-r--r-- 1 calestyo calestyo   0 Jul  1 02:01  a
> -rw-r--r-- 1 calestyo calestyo   0 Jul  1 02:01 'new'$'\n''line'
> -rw-r--r-- 1 calestyo calestyo   0 Jul  1 02:01  z
> -rw-r--r-- 1 calestyo calestyo   0 Jul  1 02:01 '\n'
>
> $ cksum -a sha512 --tag * > sums.tagged

> $ cksum -c sums.tagged
> a: OK
> \n: OK
> \new\nline: OK
> z: OK

> Assuming the same rules for the --check output as for the sums files, a
> leading \ should serve as the escaping indicator.
>
> So for:
>     \new\nline: OK
> that would be fine but for:
>     \n: OK
> it's not but would rather need to be:
>     \\\n: OK

Right. We traditionally didn't escape any chars in the --check output,
but that changed with https://github.com/coreutils/coreutils/commit/646902b30
To minimize escaping, that patch only considered the '\n' character,
but we should also have considered file names with a leading '\'.

The attached should address this.

Marking this as done.

thanks,
Pádraig

cksum-leading-backslash.patch
Description: Text Data