use Errno qw( :POSIX );
use Log::Log4perl;

## ...
if( open( my $fh, q{<}, $filename ) ) {
  my $frobulated_data = {};

  ## process with $fh

  close( $fh );
  return $frobulated_data;
} else {
  if( $! == ENOENT ) {
    ERROR( qq{Couldn't find file '$filename': $!} );
  } elsif( $! == EACCES ) {
    ERROR( qq{Problems with permissions for '$filename': $!} );
  } elsif( ## whatever else specific you want to handle ... ) { #...
  } else {
    ERROR( qq{Problem opening '$filename': $!} );
  }
  return;
}