wp-signup.php:260Validates the new site sign-up.
arrayfunction validate_blog_form() { $user = ''; if ( is_user_logged_in() ) { $user = wp_get_current_user(); } return wpmu_validate_blog_signup( $_POST['blogname'], $_POST['blog_title'], $user );}Introduced in MU (3.0.0). Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-signup.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.