How can one prevent unauthorized access to files outside the user directory in PHP scripts?

To prevent unauthorized access to files outside the user directory in PHP scripts, you can use the realpath() function to get the absolute path of the requested file and compare it against a predefined base directory. If the requested file is outside the base directory, you can deny access by throwing an exception or redirecting the user to an error page. 

$baseDirectory = '/path/to/user/directory/';

$requestedFile = realpath($_GET['file']);

if (strpos($requestedFile, $baseDirectory) !== 0) {
    // File is outside the user directory, deny access
    throw new Exception('Unauthorized access to file.');
}

// Continue processing the file

Keywords

PHP file access user directory security authorization

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