wp-includes/class-wp-customize-manager.php:515Starts preview and customize theme.
public function setup_theme() { global $pagenow; // Check permissions for customize.php access since this method is called before customize.php can run any code. if ( 'customize.php' === $pagenow && ! current_user_can( 'customize' ) ) { if ( ! is_user_logged_in() ) { auth_redirect(); } else { wp_die( '<h1>' . __( 'You need a higher level of permission.' ) . '</h1>' . '<p>' . __( 'Sorry, you are not allowed to customize this site.' ) . '</p>', 403 ); } return; } // If a changeset was provided is invalid. if ( isset( $this->_changeset_uuid ) && false !== $this->_changeset_uuid && ! wp_is_uuid( $this->_changeset_uuid ) ) { $this->wp_die( -1, __( 'Invalid changeset UUID' ) ); } /* * Clear incoming post data if the user lacks a CSRF token (nonce). Note that the customizer * application will inject the customize_preview_nonce query parameter into all Ajax requests. * For similar behavior elsewhere in WordPress, see rest_cookie_check_errors() which logs out * a user when a valid nonce isn't present. */ $has_post_data_nonce = ( check_ajax_referer( 'preview-customize_' . $this->get_stylesheet(), 'nonce', false ) || check_ajax_referer( 'save-customize_' . $this->get_stylesheet(), 'nonce', false ) || check_ajax_referer( 'preview-customize_' . $this->get_stylesheet(), 'customize_preview_nonce', false ) ); if ( ! current_user_can( 'customize' ) || ! $has_post_data_nonce ) { unset( $_POST['customized'] ); unset( $_REQUEST['customized'] ); } /* * If unauthenticated then require a valid changeset UUID to load the preview. * In this way, the UUID serves as a secret key. If the messenger channel is present, * then send unauthenticated code to prompt re-auth. */ if ( ! current_user_can( 'customize' ) && ! $this->changeset_post_id() ) { $this->wp_die( $this->messenger_channel ? 0 : -1, __( 'Non-existent changeset UUID.' ) ); } if ( ! headers_sent() ) { send_origin_headers(); } // Hide the admin bar if we're embedded in the customizer iframe. if ( $this->messenger_channel ) { show_admin_bar( false ); } if ( $this->is_theme_active() ) { // Once the theme is loaded, we'll validate it. add_action( 'after_setup_theme', array( $this, 'after_setup_theme' ) ); } else { /* * If the requested theme is not the active theme and the user doesn't have * the switch_themes cap, bail. */ if ( ! current_user_can( 'switch_themes' ) ) { $this->wp_die( -1, __( 'Sorry, you are not allowed to edit theme options on this site.' ) ); } // If the theme has errors while loading, bail. if ( $this->theme()->errors() ) { $this->wp_die( -1, $this->theme()->errors()->get_error_message() ); } // If the theme isn't allowed per multisite settings, bail. if ( ! $this->theme()->is_allowed() ) { $this->wp_die( -1, __( 'The requested theme does not exist.' ) ); } }Introduced in 3.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-customize-manager.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.