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

[Dwaipayan Ray]

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.

Support split From: headers in AUTHOR_SIGN_OFF check by adding
an additional clause to resolve author identity in such cases.

Signed-off-by: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>
---
 scripts/checkpatch.pl | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 504d2e431c60..86975baead22 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1210,6 +1210,16 @@ sub reformat_email {
 	return format_email($email_name, $email_address);
 }
 
+sub format_author_email {
+	my ($email, $from) = @_;
+
+	$email = encode("utf8", $email) if ($from =~ /=\?utf-8\?/i);
+	$email =~ s/"//g;
+	$email = reformat_email($email);
+
+	return $email;
+}
+
 sub same_email_addresses {
 	my ($email1, $email2) = @_;
 
@@ -2347,6 +2357,7 @@ sub process {
 	my $signoff = 0;
 	my $author = '';
 	my $authorsignoff = 0;
+	my $prevheader = '';
 	my $is_patch = 0;
 	my $is_binding_patch = -1;
 	my $in_header_lines = $file ? 0 : 1;
@@ -2658,12 +2669,21 @@ sub process {
 			}
 		}
 
+# Check the patch for a split From:
+		if($prevheader ne '') {
+			if ($author eq '' && decode("MIME-Header", $prevheader) =~ /^From:\s*(.*)/) {
+				my $email = $1.$line;
+				$author = format_author_email($email, $prevheader);
+			}
+			$prevheader = '';
+		}
+
 # Check the patch for a From:
 		if (decode("MIME-Header", $line) =~ /^From:\s*(.*)/) {
-			$author = $1;
-			$author = encode("utf8", $author) if ($line =~ /=\?utf-8\?/i);
-			$author =~ s/"//g;
-			$author = reformat_email($author);
+			$author = format_author_email($1, $line);
+			if($author eq '') {
+				$prevheader = $line;
+			}
 		}
 
 # Check the patch for a signoff:
-- 
2.27.0