<?php 

function md5check_cron()
{
	$modules = module_list( true, false );
	$updateSQL = 'UPDATE {system} SET md5check = "%s" WHERE filename = "%s"';
	foreach ( $modules as $moduleName )
	{
		$module = md5check_get_values_for_module($moduleName);
		$md5 = md5check_calculate_md5_value_for_module($module);
		if ( $module->md5check !== null )
		{
			if ( $md5 !== $module->md5check )
			{
				watchdog('security',
						 t('Security issue. Module @moduleName has changed.',
						 array('@moduleName' => $moduleName )),
						 array(),WATCHDOG_CRITICAL) ;
				db_query($updateSQL,array($md5,$module->filename));
			}
		} elseif ( $module->md5check === null )
		{
			db_query($updateSQL,array($md5,$module->filename));
		}
	}
}

function md5check_get_values_for_module( $moduleName )
{
	$sql = 'SELECT * FROM {system} WHERE name = "%s"';
	$result = db_query($sql,array($moduleName));
	$item = db_fetch_object($result) ;
	return $item ;
}

function md5check_calculate_md5_value_for_module( $module  )
{
	$modulePath = drupal_get_path('module',$module->name);
	$files = md5check_rglob($modulePath .'/*');
	$md5 = '' ;
	foreach ( $files as $file )
	{
		if ( is_file($file) ) $md5 .= md5_file($file);
	}
	$md5 = md5($md5);
	return $md5 ;
}

function md5check_rglob($pattern, $flags = 0, $path = '') {
    if (!$path && ($dir = dirname($pattern)) != '.') {
        if ($dir == '\\' || $dir == '/') $dir = '';
        return md5check_rglob(basename($pattern), $flags, $dir . '/');
    }
    $paths = glob($path . '*', GLOB_ONLYDIR | GLOB_NOSORT);
    $files = glob($path . $pattern, $flags);
    foreach ($paths as $p) $files = array_merge($files, md5check_rglob($pattern, $flags, $p . '/'));
    return $files;
}