Add back to overview block

custom.module

/**
 * Implementation of hook_block_info().
 */
function custom_block_info() {
  $blocks = array();
	// back to overview
  	$blocks['back-to-overview'] = array(
    	'info' => t('Back to overview'),
  	);
  return $blocks;
}

/**
 * Implementation of hook_block_view().
 */
function custom_block_view($delta='') {
  $block = array();
	global $language;
  	switch ($delta) {
  		
			case 'back-to-overview':
				// get url
				$path = array_filter(explode('/', $_SERVER['REQUEST_URI']));			
				
				// remove the last item (news detail)
				array_pop($path);
				
				// if language is fr remove the first item
				if($language->language != 'nl') {
					array_shift($path);
				}

				
				// get source url								
				$source = implode('/', $path);
									
				// get the node id for the url
				$nodeid = drupal_lookup_path('source', $source);
							
				// make link
				$content = l(t('Back to overview'), $nodeid, array('attributes' => array('title' => t('Back to overview'))));
				
				// assign block content
				$block['content'] = $content;
				 						
		  break;
    }
  return $block;
}