How to repair malformed XML?

What is best practice to repair malformed XML files with PHP? For example CDATA part contains illegal chars. With regul开发者_运维问答ar expressions? Or execute some Linux command line tools?

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Tidy

Tidy is a binding for the Tidy HTML clean and repair utility which allows you to not only clean and otherwise manipulate HTML documents, but also traverse the document tree.

// Specify configuration
$config = array(
           'indent'     => true,
           'input-xml'  => true,
           'output-xml' => true,
           'wrap'       => false);
// Tidy
$tidy = new tidy;
$tidy->parseFile('sample.xml', $config);
$tidy->cleanRepair();
// Output
echo $tidy;