[Linux-kernel-mentees] [PATCH v2] checkpatch: add fix and improve warning msg for Non-standard signature

[Aditya Srivastava <yashsri421@gmail.com>]

Currently checkpatch warns for BAD_SIGN_OFF on non-standard signature
styles.

A large number of these warnings occur because of typo mistakes in
signoffs. An evaluation over v4.13..v5.8 revealed that out of 539
warnings due to Non-standard signatures, 85 are due to typo mistakes.

Provide a fix by calculating levenshtein distance for the signature tag
over all the standard signatures and suggest a fix with signature, whose
edit distance is less than or equal to 2.

According to evaluation over v4.13..v5.8, following are the incorrect
signature tags with typos and their corresponding suggested fixes
(according to edit distace approach):

1)Reviwed-by (count: 19) => Reviewed-by

2)Reviewd-by (count: 9) => Reviewed-by

3)Singed-off-by (count: 8) => Signed-off-by

4)Signed-of-by (count: 6) => Signed-off-by

5)Rewieved-by (count: 3) => Reviewed-by

6)Signed-off--by (count: 3) => Signed-off-by

7)Revieved-by (count: 3) => Reviewed-by

8)Reivewed-by (count: 2) => Reviewed-by

9)Signef-off-by (count: 2) => Signed-off-by

10)Test-by (count: 2) => Tested-by

11)Acked_by (count: 2) => Acked-by

12)Signed-off-by-by (count: 2) => Signed-off-by

13)Reported-by-by (count: 1) => Reported-by

14)Reporetd-by (count: 1) => Reported-by

15)Reviewed--by (count: 1) => Reviewed-by

16)Sugested-by (count: 1) => Suggested-by

17)Suggested--by (count: 1) => Suggested-by

18)Repoted-by (count: 1) => Reported-by

19)Rported-by (count: 1) => Reported-by

20)eigned-off-by (count: 1) => Signed-off-by

21)Reveiwed-by (count: 1) => Reviewed-by

22)igned-off-by (count: 1) => Signed-off-by

23)Tested-by-by (count: 1) => Tested-by

24)Sugessted-by (count: 1) => Suggested-by

25)Rewiewed-by (count: 1) => Reviewed-by

26)Teste-by (count: 1) => Tested-by

27)Signee-off-by (count: 1) => Signed-off-by

28)-By (count: 1) => To

29)Signen-off-by (count: 1) => Signed-off-by

30)eported-by (count: 1) => Reported-by

31)Reviewedy-by (count: 1) => Signed-off-by

32)Siganed-off-by (count: 1) => Signed-off-by

33)Ackedy-by (count: 1) => Acked-by

34)Review-by (count: 1) => Reviewed-by

35)Tweeted-by (count: 1) => Tested-by

36)Ack-by (count: 1) => Acked-by

37)Reorted-by (count: 1) => Reported-by

38)Suggsted-by (count: 1) => Suggested-by

39)Reviwed-By (count: 1) => Reviewed-by

Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
---
changes in v2: modify commit message: replace specific example with overall evaluation, minor changes
patch applies on next-20201120

 scripts/checkpatch.pl | 85 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index fdfd5ec09be6..775a49a06179 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -506,6 +506,77 @@ our $signature_tags = qr{(?xi:
 	Cc:
 )};
 
+sub get_min {
+	my (@arr) = @_;
+	my $len = scalar @arr;
+	if((scalar @arr) < 1) {
+		# if underflow, return
+		return;
+	}
+	my $min = $arr[0];
+	for my $i (0 .. ($len-1)) {
+		if ($arr[$i] < $min) {
+			$min = $arr[$i];
+		}
+	}
+	return $min;
+}
+
+sub get_edit_distance {
+	my ($str1, $str2) = @_;
+	my $len1 = length($str1);
+	my $len2 = length($str2);
+	# two dimensional array storing minimum edit distance
+	my @distance;
+	for my $i (0 .. $len1) {
+		for my $j (0 .. $len2) {
+			if ($i == 0) {
+				$distance[$i][$j] = $j;
+			}
+			elsif ($j == 0) {
+				$distance[$i][$j] = $i;
+			}
+			elsif (substr($str1, $i-1, 1) eq substr($str2, $j-1, 1)) {
+				$distance[$i][$j] = $distance[$i - 1][$j - 1];
+			}
+			else {
+				my $dist1 = $distance[$i][$j - 1]; #insert distance
+				my $dist2 = $distance[$i - 1][$j]; # remove
+				my $dist3 = $distance[$i - 1][$j - 1]; #replace
+				$distance[$i][$j] = 1 + get_min($dist1, $dist2, $dist3);
+			}
+		}
+	}
+	return $distance[$len1][$len2];
+}
+
+sub get_standard_signature {
+	my ($sign_off) = @_;
+	$sign_off = lc($sign_off);
+	$sign_off =~ s/\-//g; # to match with formed hash
+	my @standard_signature_tags = (
+		'signed-off-by:', 'co-developed-by:', 'acked-by:', 'tested-by:',
+		'reviewed-by:', 'reported-by:', 'suggested-by:', 'to:', 'cc:'
+	);
+	# setting default values
+	my $standard_signature = 'signed-off-by';
+	my $min_edit_distance = 20;
+	my $edit_distance;
+	foreach (@standard_signature_tags) {
+		my $signature = $_;
+		$_ =~ s/\-//g;
+		$edit_distance = get_edit_distance($sign_off, $_);
+		if ($edit_distance < $min_edit_distance) {
+			$min_edit_distance = $edit_distance;
+			$standard_signature = $signature;
+		}
+	}
+        if($min_edit_distance<=2) {
+		return ucfirst($standard_signature);
+        }
+	return "";
+}
+
 our @typeListMisordered = (
 	qr{char\s+(?:un)?signed},
 	qr{int\s+(?:(?:un)?signed\s+)?short\s},
@@ -2773,8 +2844,18 @@ sub process {
 			my $ucfirst_sign_off = ucfirst(lc($sign_off));
 
 			if ($sign_off !~ /$signature_tags/) {
-				WARN("BAD_SIGN_OFF",
-				     "Non-standard signature: $sign_off\n" . $herecurr);
+				my $suggested_signature = get_standard_signature($sign_off);
+				if ($suggested_signature eq "") {
+					WARN("BAD_SIGN_OFF",
+					"Non-standard signature: $sign_off\n" . $herecurr);
+				}
+				else {
+					if (WARN("BAD_SIGN_OFF",
+						 "Non-standard signature: $sign_off. Please use '$suggested_signature' instead\n" . $herecurr) &&
+					    $fix) {
+						$fixed[$fixlinenr] =~ s/$sign_off/$suggested_signature/;
+					}
+				}
 			}
 			if (defined $space_before && $space_before ne "") {
 				if (WARN("BAD_SIGN_OFF",
-- 
2.17.1

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