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

[Joe Perches]

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);
 		}