[PATCH v2 1/1] scripts: check commit message length to fit 75 characters

[Denis V. Lunev]

There are a lot of commits descriptions which are rendered in the
'git log' with line wrap. Apparently, this is looking awkward. Let us
add check into checkpatch.pl for that.

I am not very good Perl developer, but there is an implementation in
Linux kernel's checkpatch.pl. Linux kernel people have faced a lot of
obstacles here thus direct port from them looks beneficial.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Alexey Kardashevskiy <aik@ozlabs.ru>
CC: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
CC: "Marc-André Lureau" <marcandre.lureau@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
---
Changes from v1:
- fixed formatting to match one in the checkpatch.pl file. That was not
  obvious :(

 scripts/checkpatch.pl | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d900d18048..fe1ff6c97d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -36,6 +36,18 @@ my $root;
 my %debug;
 my $help = 0;
 
+our $signature_tags = qr{(?xi:
+       Signed-off-by:|
+       Co-developed-by:|
+       Acked-by:|
+       Tested-by:|
+       Reviewed-by:|
+       Reported-by:|
+       Suggested-by:|
+       To:|
+       Cc:
+)};
+
 sub help {
        my ($exitcode) = @_;
 
@@ -1303,6 +1315,7 @@ sub process {
 
        my $in_header_lines = $file ? 0 : 1;
        my $in_commit_log = 0;          #Scanning lines before patch
+       my $commit_log_long_line = 0;
        my $reported_maintainer_file = 0;
        my $non_utf8_charset = 0;
 
@@ -1585,6 +1598,19 @@ sub process {
                        WARN("8-bit UTF-8 used in possible commit log\n" . 
$herecurr);
                }
 
+               if ($in_commit_log && !$commit_log_long_line && length($line) > 
75 &&
+                   !($line =~ /^\s*[a-zA-Z0-9_\/\.]+\s+\|\s+\d+/ ||
+                            # file delta changes
+                     $line =~ /^\s*(?:[\w\.\-\+]*\/)++[\w\.\-\+]+:/ ||
+                            # filename then :
+                     $line =~ /^\s*(?:Fixes:|Link:|$signature_tags)/i
+                            # A Fixes: or Link: line or signature tag line
+                     )) {
+                       WARN("Possible unwrapped commit description (prefer a 
maximum " .
+                            "75 chars per line)\n" . $herecurr);
+                       $commit_log_long_line = 1;
+               }
+
 # ignore non-hunk lines and lines being removed
                next if (!$hunk_line || $line =~ /^-/);
 
-- 
2.34.1