validate_blog_signup() WordPress Function

function validate_blog_signup() {
	// Re-validate user info.
	$user_result = wpmu_validate_user_signup( $_POST['user_name'], $_POST['user_email'] );
	$user_name   = $user_result['user_name'];
	$user_email  = $user_result['user_email'];
	$user_errors = $user_result['errors'];

	if ( $user_errors->has_errors() ) {
		signup_user( $user_name, $user_email, $user_errors );
		return false;
	}

	$result     = wpmu_validate_blog_signup( $_POST['blogname'], $_POST['blog_title'] );
	$domain     = $result['domain'];
	$path       = $result['path'];
	$blogname   = $result['blogname'];
	$blog_title = $result['blog_title'];
	$errors     = $result['errors'];

	if ( $errors->has_errors() ) {
		signup_blog( $user_name, $user_email, $blogname, $blog_title, $errors );
		return false;
	}

	$public      = (int) $_POST['blog_public'];
	$signup_meta = array(
		'lang_id' => 1,
		'public'  => $public,
	);

	// Handle the language setting for the new site.
	if ( ! empty( $_POST['WPLANG'] ) ) {

		$languages = signup_get_available_languages();

		if ( in_array( $_POST['WPLANG'], $languages, true ) ) {
			$language = wp_unslash( sanitize_text_field( $_POST['WPLANG'] ) );

			if ( $language ) {
				$signup_meta['WPLANG'] = $language;
			}
		}
	}

	/** This filter is documented in wp-signup.php */
	$meta = apply_filters( 'add_signup_meta', $signup_meta );

	wpmu_signup_blog( $domain, $path, $blog_title, $user_name, $user_email, $meta );
	confirm_blog_signup( $domain, $path, $blog_title, $user_name, $user_email, $meta );
	return true;
}
Uses	Description
wp-signup.php:signup_get_available_languages()	Retrieves languages available during the site/user sign-up process.
wp-signup.php:signup_user()	Shows a form for a visitor to sign up for a new user account.
wp-signup.php:signup_blog()	Shows a form for a user or visitor to sign up for a new site.
wp-signup.php:confirm_blog_signup()	Shows a message confirming that the new site has been registered and is awaiting activation.
wp-signup.php:add_signup_meta	Filters the new default site meta variables.
wp-includes/formatting.php:wp_unslash()	Removes slashes from a string or recursively removes slashes from strings within an array.
wp-includes/formatting.php:sanitize_text_field()	Sanitizes a string from user input or from the database.
wp-includes/plugin.php:apply_filters()	Calls the callback functions that have been added to a filter hook.
wp-includes/ms-functions.php:wpmu_validate_user_signup()	Sanitizes and validates data required for a user sign-up.
wp-includes/ms-functions.php:wpmu_validate_blog_signup()	Processes new site registrations.
wp-includes/ms-functions.php:wpmu_signup_blog()	Records site signup information for future activation.