Foreword :

Disabling of filecheck is not actually possible because btw it cause the attachment.pm to malfunction and any of pagespec that could contain a mimetype condition.

attachment.pm imports "statically" filecheck so actually disabling it should be interdicted .

sub import {
        add_underlay("attachment");
        add_underlay("javascript");
        add_underlay("jquery");
        hook(type => "getsetup", id => "attachment", call => \&getsetup);
        hook(type => "checkconfig", id => "attachment", call => \&checkconfig);
        hook(type => "formbuilder_setup", id => "attachment", call => \&formbuilder_setup);
        hook(type => "formbuilder", id => "attachment", call => \&formbuilder, last => 1);
        IkiWiki::loadplugin("filecheck");
}

How bad is it ?

So I tried on three pages to inline !mimetype(image/) while I allowed attachment of mimetype(image/)

My profiling tests in the bug report shows that most of the time is spend in the "Fallback using file" block code, I tried to comment that block and see how it'll perform. Obviously this is much much faster ... but is the mimetype discovered using only File::MimeInfo ?

Dumping some strings before return to STDERR, rebuilding . This is just a dumpdebug adding

sub match_mimetype ($$;@) {
        my $page=shift;
        my $wanted=shift;

        my %params=@_;
        my $file=exists $params{file} ? $params{file} : IkiWiki::srcfile($IkiWiki::pagesources{$page});
        if (! defined $file) {
                return IkiWiki::ErrorReason->new("file does not exist");
        }

        # Get the mime type.
        #
        # First, try File::Mimeinfo. This is fast, but doesn't recognise
        # all files.
        eval q{use File::MimeInfo::Magic};
        my $mimeinfo_ok=! $@;
        my $mimetype;
        print STDERR " --- match_mimetype (".$file.")\n";
        if ($mimeinfo_ok) {
                my $mimetype=File::MimeInfo::Magic::magic($file);
        }

        # Fall back to using file, which has a more complete
        # magic database.
        #if (! defined $mimetype) {
        #       open(my $file_h, "-|", "file", "-bi", $file);
        #       $mimetype=<$file_h>;
        #       chomp $mimetype;
        #       close $file_h;
        #}

        if (! defined $mimetype || $mimetype !~s /;.*//) {
                # Fall back to default value.
                $mimetype=File::MimeInfo::Magic::default($file)
                        if $mimeinfo_ok;
                if (! defined $mimetype) {
                        $mimetype="unknown";
                }
        }

        my $regexp=IkiWiki::glob2re($wanted);
        if ($mimetype!~$regexp) {
                 print STDERR " xxx MIME unknown ($mimetype - $wanted - $regexp ) \n";
                return IkiWiki::FailReason->new("file MIME type is $mimetype, not $wanted");
        }
        else {
                print STDERR " vvv MIME found\n";
                return IkiWiki::SuccessReason->new("file MIME type is $mimetype");
        }
}

The results dump to stderr (or a file called... 'say mime) looks like this :

--- match_mimetype (/usr/share/ikiwiki/attachment/ikiwiki/jquery.fileupload-ui.js)
 xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$) )
 --- match_mimetype (/usr/share/ikiwiki/locale/fr/directives/ikiwiki/directive/fortune.mdwn)
 xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$) )
 --- match_mimetype (/usr/share/ikiwiki/locale/fr/basewiki/shortcuts.mdwn)
 xxx MIME unknown (text/plain - image/* - (?i-xsm:^image\/.*$) 
 --- match_mimetype (/usr/share/ikiwiki/smiley/smileys/alert.png)
 xxx MIME unknown (application/octet-stream - image/* - (?i-xsm:^image\/.*$) )
 --- match_mimetype (/usr/share/ikiwiki/attachment/ikiwiki/images/ui-bg_flat_75_ffffff_40x100.png)
 xxx MIME unknown (application/octet-stream - image/* - (?i-xsm:^image\/.*$) 

--- prepend signals the file on analysis
xxx prepend signals a returns failure : mime is unknown, the match is a failure
vvv prepend signals a return success.

This is nasty-scary results ! Something missed me or this mime-filecheck is plain nuts ?

Question 1 : How many files have been analysed : 3055 (yet on a tiny tiny wiki)

grep "^ --- " mime | wc -l
3055

Question 2 : How many time it fails : all the time

 grep "^ xxx " mime | wc -l
3055

Question 1bis : Doh btw , how many files have been re-analysed ? 2835 OMG !!

grep "^ --- " mime | sort -u | wc -l
220

Conclusion

• Only the system command file -bi works. While it is should be easy on the cpu , it's also hard on the I/O -> VM
• Something nasty with the mime implementation and/or my system configuration -> Hints ?
• Need to cache during the rebuild : a same page needs not being rechecked for its mime while it's locked !

--mathdesc

   if ($mimeinfo_ok) {
           my $mimetype=File::MimeInfo::Magic::magic($file);
   }

That seems strange to me, my restricts scope of $mimetype to enclosing if block, thus, assigned value will be dropped - I think, it is the problem. Try removing that stray my.

--isbear