Fonts prohibiting installable embedding

[Norbert Preining]

Hi Karl,

> Presumably the flag is the default in some tool. Clearly those font
> (designer)s do not intend to restrict embedding.

That was my idea, too!

> The string "texlive" does not appear on either page? (I guess I'm going

You are right, this is strange (and one of the reasons I recently
despise lintian). They were there when I sent the email, but in the
meantime it seems the list was regenerated, and whatever change did
trigger a different list. One never knows...

> If original fonts distributed in TL have the flag set, we should discuss
> with authors. Is there a simple cmdline tool that can check a file?

Agreed. Concerning cmdline, I fear no .. lintian does something as
follows in perl for opentype, see
https://salsa.debian.org/lintian/lintian/-/blob/master/lib/Lintian/Check/Fonts/Opentype.pm
(and Truetype.pm for a similar code)

const my $PERMISSIONS_MASK => 0x0f;
const my $NEVER_EMBED_FLAG => 0x02;
const my $PRINT_PREVIEW_ONLY_FLAG => 0x04;
const my $EDIT_ONLY_FLAG => 0x08;

sub visit_installed_files {
    my ($self, $file) = @_;

    return
      unless $file->is_file;

    return
      unless $file->file_info =~ /^OpenType font data/;

    $self->hint('opentype-font-wrong-filename', $file->name)
      unless $file->name =~ /\.otf$/i;

    my $font = Font::TTF::Font->open($file->unpacked_path);

    my $os2 = defined $font ? $font->{'OS/2'} : undef;
    my $table = defined $os2 ? $os2->read : undef;
    my $fs_type = defined $table ? $table->{fsType} : undef;

    $font->release
      if defined $font;

    return
      unless defined $fs_type;

    my @clauses;

    my $permissions = $fs_type & $PERMISSIONS_MASK;
    push(@clauses, 'never embed')
      if $permissions & $NEVER_EMBED_FLAG;
    push(@clauses, 'preview/print only')
      if $permissions & $PRINT_PREVIEW_ONLY_FLAG;
    push(@clauses, 'edit only')
      if $permissions & $EDIT_ONLY_FLAG;

    my $terms;
    $terms = join($COMMA . $SPACE, @clauses)
      if @clauses;

    $self->hint('opentype-font-prohibits-installable-embedding',
        "[$terms] " . $file->name)
      if length $terms;

    return;
}

> In any case, I would not consider this a reason to start removing fonts
> willy-nilly. I'd like to see some kind of confirmation or evidence that

100% agreed, nothing should be removed for now.

> the font designers actually intended to restrict embedding, not just an
> obscure flag that was probably not set intentionally 99% of the time. -k

That was also my reasoning.

Best

Norbert

--
PREINING Norbert                              https://www.preining.info
Fujitsu Research  +  IFMGA Guide  +  TU Wien  +  TeX Live  + Debian Dev
GPG: 0x860CDC13   fp: F7D8 A928 26E3 16A1 9FA0 ACF0 6CAC A448 860C DC13