linux-kernel - Re: [PATCH] checkpatch: Avoid missing typo suggestions

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Message-ID: <202006041503.C9BFD40255@keescook>
Date:   Thu, 4 Jun 2020 15:08:22 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Joe Perches <joe@...ches.com>
Cc:     Andy Whitcroft <apw@...onical.com>, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Maxim Uvarov <maxim.uvarov@...aro.org>
Subject: Re: [PATCH] checkpatch: Avoid missing typo suggestions

On Wed, Jun 03, 2020 at 05:39:47PM -0700, Joe Perches wrote:
> On Wed, 2020-06-03 at 16:19 -0700, Kees Cook wrote:
> > My codespell dictionary has a lot of capitalized words. For example:
> > 
> > MSDOS->MS-DOS
> > 
> > Since checkpatch uses case-insensitive matching, I get an undefined
> > variable warning and then empty suggestions for things like this:
> > 
> > Use of uninitialized value $typo_fix in concatenation (.) or string at ./scripts/checkpatch.pl line 2958.
> > 
> > WARNING: 'msdos' may be misspelled - perhaps ''?
> > +       struct msdos_dir_entry *de;
> > 
> > This fixes the matcher to avoid the warning, but it's still a rather
> > silly suggestion:
> > 
> > WARNING: 'msdos' may be misspelled - perhaps 'MS-DOS'?
> > +       struct msdos_dir_entry *de;
> > 
> > So I'm not really sure what to do with this ... filter out bad
> > suggestions instead?
> 
> Hey Kees.
> 
> Maybe this?
> 
> btw: My codespell dictionary file moved to
> /usr/lib/python3/dist-packages/codespell_lib/data/dictionary.txt

Yeah, mine too. I think I may have added a symlink to my filesystem to
work around this.

> and I had to use --codespell --codespellfile=(above) so
> maybe there should be multiple lookups for this file
> like the array below.

That seems like a good idea.

> 
> Are there other standard codespell dictionary locations?
> ---
>  scripts/checkpatch.pl | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 5f00df2c3f59..52aa0dd53d80 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -59,7 +59,7 @@ my $minimum_perl_version = 5.10.0;
>  my $min_conf_desc_length = 4;
>  my $spelling_file = "$D/spelling.txt";
>  my $codespell = 0;
> -my $codespellfile = "/usr/share/codespell/dictionary.txt";
> +my $codespellfile;
>  my $conststructsfile = "$D/const_structs.checkpatch";
>  my $typedefsfile = "";
>  my $color = "auto";
> @@ -716,7 +716,20 @@ if (open(my $spelling, '<', $spelling_file)) {
>  }
>  
>  if ($codespell) {
> -	if (open(my $spelling, '<', $codespellfile)) {
> +	if (!defined($codespellfile)) {
> +		my @csfiles = ("/usr/share/codespell/dictionary.txt",
> +			       "/usr/lib/python3/dist-packages/codespell_lib/data/dictionary.txt");
> +		foreach my $csfile (@csfiles) {
> +			if (-f $csfile) {
> +				$codespellfile = $csfile;
> +				last;
> +			}
> +		}
> +	}
> +
> +	if (!defined($codespellfile)) {
> +		warn "No codespell typos will be found - codespell dictionary not found\n";
> +	} elsif (open(my $spelling, '<', $codespellfile)) {
>  		while (<$spelling>) {
>  			my $line = $_;
>  
> @@ -2963,13 +2976,21 @@ sub process {
>  			while ($rawline =~ /(?:^|[^a-z@])($misspellings)(?:\b|$|[^a-z@])/gi) {
>  				my $typo = $1;
>  				my $typo_fix = $spelling_fix{lc($typo)};
> -				$typo_fix = ucfirst($typo_fix) if ($typo =~ /^[A-Z]/);
> -				$typo_fix = uc($typo_fix) if ($typo =~ /^[A-Z]+$/);
> +				$typo_fix = $spelling_fix{$typo} if (!defined($typo_fix));
> +				$typo_fix = $spelling_fix{uc($typo)} if (!defined($typo_fix));

This won't catch stuff like:

Cambrige->Cambridge

because neither "cambrige" nor "CAMBRIGE" is in %spelling_fix. And the
original text is lost due to the //i. :( I'm really not sure what to do
with these things in codespell. Lower case everything? Throw away
anything not all lower case?

-- 
Kees Cook