unzip_file( string $file, string $to )

function unzip_file($file, $to) {
	global $wp_filesystem;

	if ( ! $wp_filesystem || !is_object($wp_filesystem) )
		return new WP_Error('fs_unavailable', __('Could not access filesystem.'));

	// Unzip can use a lot of memory, but not this much hopefully.
	wp_raise_memory_limit( 'admin' );

	$needed_dirs = array();
	$to = trailingslashit($to);

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

	/**
	 * Filters whether to use ZipArchive to unzip archives.
	 *
	 * @since WP-3.0.0
	 *
	 * @param bool $ziparchive Whether to use ZipArchive. Default true.
	 */
	if ( class_exists( 'ZipArchive', false ) && apply_filters( 'unzip_file_use_ziparchive', true ) ) {
		$result = _unzip_file_ziparchive($file, $to, $needed_dirs);
		if ( true === $result ) {
			return $result;
		} elseif ( is_wp_error($result) ) {
			if ( 'incompatible_archive' != $result->get_error_code() )
				return $result;
		}
	}
	// Fall through to PclZip if ZipArchive is not available, or encountered an error opening the file.
	return _unzip_file_pclzip($file, $to, $needed_dirs);
}