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

["Denis V. Lunev" <den@virtuozzo.com>]

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