[Linux-kernel-mentees] [PATCH RFC] checkpatch: improve handling of email comments

[Dwaipayan Ray]

checkpatch has limited support for parsing email comments. It only
support single name comments or single after address comments.
Whereas, RFC 5322 specifies that comments can be inserted in
between any tokens of the email fields.

On analyzing 50,000 commits from v5.4 it was found that there were
about 370 false positives resulting from wrong parsing of comments.

Improve comment parsing mechanism in checkpatch.

What is handled now:

- Multiple name/address comments
- Comments anywhere in between name/address
- Multi level comments like (John (Doe) )

Signed-off-by: Dwaipayan Ray <dwaipayanray1 at gmail.com>
---
 scripts/checkpatch.pl | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index fab38b493cef..ae8436385fc1 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1183,14 +1183,20 @@ sub parse_email {
 		}
 	}
 
-	$comment = trim($comment);
+	# Comments in between name like John(A nice chap) Doe
+	while ($name =~ s/\s*($balanced_parens)\s*/ /) {
+		$name_comment .= trim($1);
+	}
 	$name = trim($name);
 	$name =~ s/^\"|\"$//g;
-	if ($name =~ s/(\s*\([^\)]+\))\s*//) {
-		$name_comment = trim($1);
+
+	# Comments in between address like <john(his account)@doe.com>
+	while ($address =~ s/\s*($balanced_parens)\s*//) {
+		$comment .= trim($1);
 	}
 	$address = trim($address);
 	$address =~ s/^\<|\>$//g;
+	$comment = trim($comment);
 
 	if ($name =~ /[^\w \-]/i) { ##has "must quote" chars
 		$name =~ s/(?<!\\)"/\\"/g; ##escape quotes
@@ -1205,8 +1211,6 @@ sub format_email {
 
 	my $formatted_email;
 
-	$name_comment = trim($name_comment);
-	$comment = trim($comment);
 	$name = trim($name);
 	$name =~ s/^\"|\"$//g;
 	$address = trim($address);
@@ -1216,6 +1220,11 @@ sub format_email {
 		$name = "\"$name\"";
 	}
 
+	$name_comment = trim($name_comment);
+	$name_comment =~ s/(.+)/ $1/;
+	$comment = trim($comment);
+	$comment =~ s/(.+)/ $1/;
+
 	if ("$name" eq "") {
 		$formatted_email = "$address";
 	} else {
-- 
2.27.0