Drupal - imagecache problems with special characters

We came across this problem on one of our Drupal sites the other day, someone uploaded an image with an ampersand in the filename, and imagecache refused to display the image. A bit of investigating revealed that imagecache had a problem with a number of special characters in the image filenames.

The solution is a little imagecache theme override - you can see examples for both Drupal5 and Drupal6 below

Drupal 5 version

function phptemplate_imagecache($namespace, $path, $alt = '', $title = '',
    $attributes = NULL) {
    $attributes = drupal_attributes($attributes);
    $imagecache_path = file_create_url(file_directory_path() .'/imagecache/'.
    $namespace .'/'. drupal_urlencode($path));
    return '<img src="'. $imagecache_path .'" alt="'. check_plain($alt) .'" title="'. check_plain($title) .'" '. $attributes .' />';
}

Drupal 6 version

function phptemplate_imagecache($namespace, $path, $alt = '', $title = '', $attributes = NULL) {
    if ($image = image_get_info(imagecache_create_path($namespace, $path))) {
        $attributes['width'] = $image['width'];
        $attributes['height'] = $image['height'];
    }
    // check is_null so people can intentionally pass an empty 
    // array of attributes to override
    // the defaults completely... if
    if (is_null($attributes)) {
        $attributes['class'] = 'imagecache imagecache-'. $namespace;
    }
    $attributes = drupal_attributes($attributes);
    $imagecache_url = imagecache_create_url($namespace, drupal_urlencode($path));
    return '<img src="'. $imagecache_url .'" alt="'. check_plain($alt) .'" title="'. check_plain($title) .'" '. $attributes .' />';
}