gistfile1.pl

package Plack::Middleware::Sendfile;
use strict;
use warnings;
use base qw( Plack::Middleware );

use IO::File::WithPath;

sub call {
    my $self = shift;
    my $env  = shift;

    my $res = $self->app->($env);

    if ( ref $res->[2] eq 'IO::File::WithPath' ) {
        $env->{'psgix.sendfile''} = $res->[2]->path;
    }

    return $res->finalize;
}

1;