What should I pass for $needed_dirs when calling _unzip_file_pclzip (aka PclZip)?

Question

I'm trying to create a fallback method when ZipArchive is not present. I'm seeking to use the _unzip_file_pclzip() function contained in wp-admin/includes/file.php

However, I'm not sure what is expected for the $needed_dirs argument.

My target folder for the zip will be the "styles" folder under my theme folder, so the path would be "wp-content/themes/mytheme/styles/"

Is that what's expected for $needed_dirs?

function openZip($file_to_open) { 
    global $wp_filesystem;//required if _unzip_file_pclzip is used directly
    global $target;  
    if(class_exists('ZipArchive'))
    {
        $zip = new ZipArchive();  
        $x = $zip->open($file_to_open);  
        if($x === true) 
        {  
            $zip->extractTo($target);  
            $zip->close();                
            unlink($file_to_open);  
        } else {  
            die("There was a problem. Please try again!");  
        }
    }
    else
    {
        $needed_dirs = array();
        _unzip_file_pclzip($file_to_open, $target, $needed_dirs);
    }
} 

Answer 1

@Scott B I have not tested this script, taken from inlcudes/file.php -> line 559

_unzip_file_pclzip assumes WP_Filesystem() has already been called, so you need to set up global $wp_filesystem

global $wp_filesystem;
$needed_dirs = array();
$target = trailingslashit($target);

// Determine any parent dir's needed (of the upgrade directory)
if ( ! $wp_filesystem->is_dir($target) ) { //Only do parents if no children exist
    $path = preg_split('![/\\\]!', untrailingslashit($target));
    for ( $i = count($path); $i >= 0; $i-- ) {
        if ( empty($path[$i]) )
            continue;

        $dir = implode('/', array_slice($path, 0, $i+1) );
        if ( preg_match('!^[a-z]:$!i', $dir) ) // Skip it if it looks like a Windows Drive letter.
            continue;

        if ( ! $wp_filesystem->is_dir($dir) )
            $needed_dirs[] = $dir;
        else
             break; // A folder exists, therefor, we dont need the check the levels below this
    }
}