linux-kernel - Re: [PATCH] checkpatch: extend author Signed-off-by check for split From: header

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Message-ID: <CABJPP5Daf0UiKjeQp71_bViAkQQh7znWrArKAS1FqnjGU1nX4A@mail.gmail.com>
Date:   Sun, 20 Sep 2020 01:08:45 +0530
From:   Dwaipayan Ray <dwaipayanray1@...il.com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>
Cc:     Joe Perches <joe@...ches.com>,
        linux-kernel-mentees@...ts.linuxfoundation.org, apw@...onical.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] checkpatch: extend author Signed-off-by check for split
 From: header

On Sun, Sep 20, 2020 at 12:06 AM Lukas Bulwahn <lukas.bulwahn@...il.com> wrote:
>
>
>
> On Sat, 19 Sep 2020, Joe Perches wrote:
>
> > On Sat, 2020-09-19 at 20:12 +0200, Lukas Bulwahn wrote:
> > >
> > > On Sat, 19 Sep 2020, Joe Perches wrote:
> > >
> > > > On Sat, 2020-09-19 at 13:42 +0530, Dwaipayan Ray wrote:
> > > > > Checkpatch did not handle cases where the author From: header
> > > > > was split into two lines. The author string went empty and
> > > > > checkpatch generated a false NO_AUTHOR_SIGN_OFF warning.
> > > >
> > > > It's good to provide an example where the current code
> > > > doesn't work.
> > > >
> > >
> > > Joe, as this is a linux-kernel-mentees patch, we discussed that before
> > > reaching out to you; you can find Dwaipayan's own evaluation here:
> > >
> > > https://lore.kernel.org/linux-kernel-mentees/CABJPP5BOTG0QLFSaRJTb2vAZ_hJf229OAQihHKG4sYd35i_WMw@mail.gmail.com/
> > >
> > > Dwaipayan, Joe's comment is still valid; it would be good to describe
> > > the reasons why patches might have split lines (as far as see, long
> > > encodings for non-ascii names).
> > >
> > > I will run my own evaluation of checkpatch.pl before and after patch
> > > application on Monday and then check if I can confirm Dwaipayan's results.
> > >
> > > > It likely would be better to do this by searching forward for
> > > > any extension lines after a "^From:' rather than searching
> > > > backwards as there can be any number of extension lines.
> > > >
> > >
> > > Just to sure what you are talking about...
> > >
> > > You mean just to access the next line through the lines array, rather
> > > than using prevheader and trying to decode that one line twice.
> > >
> > > I agree the logic is a bit redundant and complicated at the moment.
> > >
> > > Once prevheader is non-empty, it already clear that author is '' and
> > > prevheader decodes with that match, because that is the only way to
> > > make prevheader non-empty in the first place; at least as far I see it
> > > right now.
> >
> > Yeah, something like this (completely untested):
> > ---
> >  scripts/checkpatch.pl | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 3e474072aa90..2c710d05b184 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -2679,9 +2679,13 @@ sub process {
> >               }
> >
> >  # Check the patch for a From:
> > -             if (decode("MIME-Header", $line) =~ /^From:\s*(.*)/) {
> > +             if ($line =~ /^From:\s*(.*)/i) {
> >                       $author = $1;
> > -                     $author = encode("utf8", $author) if ($line =~ /=\?utf-8\?/i);
> > +                     my $curline = $linenr;
> > +                     while (defined($rawlines[$curline] && $rawlines[$curline++] =~ /^ \s*(.*)/) {
> > +                             $author .= $1;
> > +                     }
> > +                     $author = encode("utf8", $author) if ($author =~ /=\?utf-8\?/i);
> >                       $author =~ s/"//g;
> >                       $author = reformat_email($author);
> >               }
> >
>

Hi,

Yeah I think the backwards checking was pretty redundant after all. If the
extended encoding went too long, the From: header would be split into
more than two lines and my proposed solution would fail.

Thanks for the heads up, Joe!

> Yeah, I get how you would like to see that being implemented. I will work
> with Dwaipayan to get that properly implemented, properly described and
> tested.
>
> But let us keep the fun of that task to Dwaipayan... that is what a
> mentorship is all about :)
>
> Lukas

Yes definitely, the task is interesting for me, and I would like to solve
it in a proper way.

As for the fix, shouldn't we stop the author string concatenation once
an email address is found? something like:

  last if  $rawlines[$curline] = ~/^\s*(\S+\@\S+)\s*/

I will update the patch and sync up with Lukas on this.

Thanks,
Dwaipayan.