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

[Denis V. Lunev]

On 9/29/22 13:48, Markus Armbruster wrote:
> "Denis V. Lunev" <den@openvz.org> writes:
>
> > 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 || $line =~ /^-/);
> For comparison, Linux's version:
>
>     # Check for line lengths > 75 in commit log, warn once
>                     if ($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
>                           $commit_log_possible_stack_dump)) {
>                             WARN("COMMIT_LOG_LONG_LINE",
>                                  "Possible unwrapped commit description (prefer a 
> maximum 75 chars per line)\n" . $herecurr);
>                             $commit_log_long_line = 1;
>                     }
>
> Differences:
>
> * Initial comment lost.  Let's add it back.
right. Good catch

> * One fewer line break, and spaces instead of tabs.  I think it's best
>    to stick to the original there.
right. Some places are correctly filled with tabs,
though there are some lines with spaces. This
is a bit boring as QEMU style demands spaces,
but ok. Will do.

> * We don't have $commit_log_possible_stack_dump.  Should we?
made specific check. The real question here is the following: should we
allow commits like
205ccfd7a5e hw/display/ati_2d: Fix buffer overflow in ati_2d_blt 
(CVE-2021-3638)
to be passed without this script? If yes, we should invent something
similar but a bit different as userspace callstacks are really different.

> Initial Linux version was
>
>      2a076f40d8c9 checkpatch, SubmittingPatches: suggest line wrapping
>      commit messages at 75 columns
>
> Updates since:
>
>      369c8dd390ba checkpatch: improve tests for fixes:, long lines and
>      stack dumps in commit log
>
>      27b379af6102 checkpatch: avoid COMMIT_LOG_LONG_LINE warning for
>      signature tags
>
>      36f8b348a94c checkpatch: relax regexp for COMMIT_LOG_LONG_LINE
>
> The first of these also messes with $commit_log_possible_stack_dump.
> Added before in
>
>      bf4daf12a9fb checkpatch: avoid some commit message long line warnings
>
> and updated later in
>
>      634cffcc9478 checkpatch: don't interpret stack dumps as commit IDs
wow! That is amazing thing :) I was a bit lazy doing this porting.
I will definitely update the commit message in the next submission
with this info :)

Den