WordPress/wp-includes/capabilities.php

<?php
/**
 * Core User Role & Capabilities API
 *
 * @package WordPress
 * @subpackage Users
 */

/**
 * Map meta capabilities to primitive capabilities.
 *
 * This does not actually compare whether the user ID has the actual capability,
 * just what the capability or capabilities are. Meta capability list value can
 * be 'delete_user', 'edit_user', 'remove_user', 'promote_user', 'delete_post',
 * 'delete_page', 'edit_post', 'edit_page', 'read_post', or 'read_page'.
 *
 * @since 2.0.0
 *
 * @global array $post_type_meta_caps Used to get post type meta capabilities.
 *
 * @param string $cap       Capability name.
 * @param int    $user_id   User ID.
 * @param int    $object_id Optional. ID of the specific object to check against if `$cap` is a "meta" cap.
 *                          "Meta" capabilities, e.g. 'edit_post', 'edit_user', etc., are capabilities used
 *                          by map_meta_cap() to map to other "primitive" capabilities, e.g. 'edit_posts',
 *                          'edit_others_posts', etc. The parameter is accessed via func_get_args().
 * @return array Actual capabilities for meta capability.
 */
function map_meta_cap( $cap, $user_id ) {
	$args = array_slice( func_get_args(), 2 );
	$caps = array();

	switch ( $cap ) {
	case 'remove_user':
		// In multisite the user must be a super admin to remove themselves.
		if ( isset( $args[0] ) && $user_id == $args[0] && ! is_super_admin( $user_id ) ) {
			$caps[] = 'do_not_allow';
		} else {
			$caps[] = 'remove_users';
		}
		break;
	case 'promote_user':
	case 'add_users':
		$caps[] = 'promote_users';
		break;
	case 'edit_user':
	case 'edit_users':
		// Allow user to edit itself
		if ( 'edit_user' == $cap && isset( $args[0] ) && $user_id == $args[0] )
			break;

		// In multisite the user must have manage_network_users caps. If editing a super admin, the user must be a super admin.
		if ( is_multisite() && ( ( ! is_super_admin( $user_id ) && 'edit_user' === $cap && is_super_admin( $args[0] ) ) || ! user_can( $user_id, 'manage_network_users' ) ) ) {
			$caps[] = 'do_not_allow';
		} else {
			$caps[] = 'edit_users'; // edit_user maps to edit_users.
		}
		break;
	case 'delete_post':
	case 'delete_page':
		$post = get_post( $args[0] );
		if ( ! $post ) {
			$caps[] = 'do_not_allow';
			break;
		}

		if ( 'revision' == $post->post_type ) {
			$post = get_post( $post->post_parent );
			if ( ! $post ) {
				$caps[] = 'do_not_allow';
				break;
			}
		}

		if ( ( get_option( 'page_for_posts' ) == $post->ID ) || ( get_option( 'page_on_front' ) == $post->ID ) ) {
			$caps[] = 'manage_options';
			break;
		}

		$post_type = get_post_type_object( $post->post_type );
		if ( ! $post_type ) {
			/* translators: 1: post type, 2: capability name */
			_doing_it_wrong( __FUNCTION__, sprintf( __( 'The post type %1$s is not registered, so it may not be reliable to check the capability "%2$s" against a post of that type.' ), $post->post_type, $cap ), '4.4.0' );
			$caps[] = 'edit_others_posts';
			break;
		}

		if ( ! $post_type->map_meta_cap ) {
			$caps[] = $post_type->cap->$cap;
			// Prior to 3.1 we would re-call map_meta_cap here.
			if ( 'delete_post' == $cap )
				$cap = $post_type->cap->$cap;
			break;
		}

		// If the post author is set and the user is the author...
		if ( $post->post_author && $user_id == $post->post_author ) {
			// If the post is published or scheduled...
			if ( in_array( $post->post_status, array( 'publish', 'future' ), true ) ) {
				$caps[] = $post_type->cap->delete_published_posts;
			} elseif ( 'trash' == $post->post_status ) {
				$status = get_post_meta( $post->ID, '_wp_trash_meta_status', true );
				if ( in_array( $status, array( 'publish', 'future' ), true ) ) {
					$caps[] = $post_type->cap->delete_published_posts;
				} else {
					$caps[] = $post_type->cap->delete_posts;
				}
			} else {
				// If the post is draft...
				$caps[] = $post_type->cap->delete_posts;
			}
		} else {
			// The user is trying to edit someone else's post.
			$caps[] = $post_type->cap->delete_others_posts;
			// The post is published or scheduled, extra cap required.
			if ( in_array( $post->post_status, array( 'publish', 'future' ), true ) ) {
				$caps[] = $post_type->cap->delete_published_posts;
			} elseif ( 'private' == $post->post_status ) {
				$caps[] = $post_type->cap->delete_private_posts;
			}
		}
		break;
		// edit_post breaks down to edit_posts, edit_published_posts, or
		// edit_others_posts
	case 'edit_post':
	case 'edit_page':
		$post = get_post( $args[0] );
		if ( ! $post ) {
			$caps[] = 'do_not_allow';
			break;
		}

		if ( 'revision' == $post->post_type ) {
			$post = get_post( $post->post_parent );
			if ( ! $post ) {
				$caps[] = 'do_not_allow';
				break;
			}
		}

		$post_type = get_post_type_object( $post->post_type );
		if ( ! $post_type ) {
			/* translators: 1: post type, 2: capability name */
			_doing_it_wrong( __FUNCTION__, sprintf( __( 'The post type %1$s is not registered, so it may not be reliable to check the capability "%2$s" against a post of that type.' ), $post->post_type, $cap ), '4.4.0' );
			$caps[] = 'edit_others_posts';
			break;
		}

		if ( ! $post_type->map_meta_cap ) {
			$caps[] = $post_type->cap->$cap;
			// Prior to 3.1 we would re-call map_meta_cap here.
			if ( 'edit_post' == $cap )
				$cap = $post_type->cap->$cap;
			break;
		}

		// If the post author is set and the user is the author...
		if ( $post->post_author && $user_id == $post->post_author ) {
			// If the post is published or scheduled...
			if ( in_array( $post->post_status, array( 'publish', 'future' ), true ) ) {
				$caps[] = $post_type->cap->edit_published_posts;
			} elseif ( 'trash' == $post->post_status ) {
				$status = get_post_meta( $post->ID, '_wp_trash_meta_status', true );
				if ( in_array( $status, array( 'publish', 'future' ), true ) ) {
					$caps[] = $post_type->cap->edit_published_posts;
				} else {
					$caps[] = $post_type->cap->edit_posts;
				}
			} else {
				// If the post is draft...
				$caps[] = $post_type->cap->edit_posts;
			}
		} else {
			// The user is trying to edit someone else's post.
			$caps[] = $post_type->cap->edit_others_posts;
			// The post is published or scheduled, extra cap required.
			if ( in_array( $post->post_status, array( 'publish', 'future' ), true ) ) {
				$caps[] = $post_type->cap->edit_published_posts;
			} elseif ( 'private' == $post->post_status ) {
				$caps[] = $post_type->cap->edit_private_posts;
			}
		}
		break;
	case 'read_post':
	case 'read_page':
		$post = get_post( $args[0] );
		if ( ! $post ) {
			$caps[] = 'do_not_allow';
			break;
		}

		if ( 'revision' == $post->post_type ) {
			$post = get_post( $post->post_parent );
			if ( ! $post ) {
				$caps[] = 'do_not_allow';
				break;
			}
		}

		$post_type = get_post_type_object( $post->post_type );
		if ( ! $post_type ) {
			/* translators: 1: post type, 2: capability name */
			_doing_it_wrong( __FUNCTION__, sprintf( __( 'The post type %1$s is not registered, so it may not be reliable to check the capability "%2$s" against a post of that type.' ), $post->post_type, $cap ), '4.4.0' );
			$caps[] = 'edit_others_posts';
			break;
		}

		if ( ! $post_type->map_meta_cap ) {
			$caps[] = $post_type->cap->$cap;
			// Prior to 3.1 we would re-call map_meta_cap here.
			if ( 'read_post' == $cap )
				$cap = $post_type->cap->$cap;
			break;
		}

		$status_obj = get_post_status_object( $post->post_status );
		if ( $status_obj->public ) {
			$caps[] = $post_type->cap->read;
			break;
		}

		if ( $post->post_author && $user_id == $post->post_author ) {
			$caps[] = $post_type->cap->read;
		} elseif ( $status_obj->private ) {
			$caps[] = $post_type->cap->read_private_posts;
		} else {
			$caps = map_meta_cap( 'edit_post', $user_id, $post->ID );
		}
		break;
	case 'publish_post':
		$post = get_post( $args[0] );
		if ( ! $post ) {
			$caps[] = 'do_not_allow';
			break;
		}

		$post_type = get_post_type_object( $post->post_type );
		if ( ! $post_type ) {
			/* translators: 1: post type, 2: capability name */
			_doing_it_wrong( __FUNCTION__, sprintf( __( 'The post type %1$s is not registered, so it may not be reliable to check the capability "%2$s" against a post of that type.' ), $post->post_type, $cap ), '4.4.0' );
			$caps[] = 'edit_others_posts';
			break;
		}

		$caps[] = $post_type->cap->publish_posts;
		break;
	case 'edit_post_meta':
	case 'delete_post_meta':
	case 'add_post_meta':
	case 'edit_comment_meta':
	case 'delete_comment_meta':
	case 'add_comment_meta':
	case 'edit_term_meta':
	case 'delete_term_meta':
	case 'add_term_meta':
	case 'edit_user_meta':
	case 'delete_user_meta':
	case 'add_user_meta':
		list( $_, $object_type, $_ ) = explode( '_', $cap );
		$object_id = (int) $args[0];

		switch ( $object_type ) {
			case 'post':
				$post = get_post( $object_id );
				if ( ! $post ) {
					break;
				}

				$sub_type = get_post_type( $post );
				break;

			case 'comment':
				$comment = get_comment( $object_id );
				if ( ! $comment ) {
					break;
				}

				$sub_type = empty( $comment->comment_type ) ? 'comment' : $comment->comment_type;
				break;

			case 'term':
				$term = get_term( $object_id );
				if ( ! $term ) {
					break;
				}

				$sub_type = $term->taxonomy;
				break;

			case 'user':
				$user = get_user_by( 'id', $object_id );
				if ( ! $user ) {
					break;
				}

				$sub_type = 'user';
				break;
		}

		if ( empty( $sub_type ) ) {
			$caps[] = 'do_not_allow';
			break;
		}

		$caps = map_meta_cap( "edit_{$object_type}", $user_id, $object_id );

		$meta_key = isset( $args[1] ) ? $args[1] : false;

		$has_filter = has_filter( "auth_{$object_type}_meta_{$meta_key}" ) || has_filter( "auth_{$object_type}_{$sub_type}_meta_{$meta_key}" );
		if ( $meta_key && $has_filter ) {
			/** This filter is documented in wp-includes/meta.php */
			$allowed = apply_filters( "auth_{$object_type}_meta_{$meta_key}", false, $meta_key, $object_id, $user_id, $cap, $caps );

			/** This filter is documented in wp-includes/meta.php */
			$allowed = apply_filters( "auth_{$object_type}_{$sub_type}_meta_{$meta_key}", $allowed, $meta_key, $object_id, $user_id, $cap, $caps );

			if ( ! $allowed ) {
				$caps[] = $cap;
			}
		} elseif ( $meta_key && is_protected_meta( $meta_key, $object_type ) ) {
			$caps[] = $cap;
		}
		break;
	case 'edit_comment':
		$comment = get_comment( $args[0] );
		if ( ! $comment ) {
			$caps[] = 'do_not_allow';
			break;
		}

		$post = get_post( $comment->comment_post_ID );

		/*
		 * If the post doesn't exist, we have an orphaned comment.
		 * Fall back to the edit_posts capability, instead.
		 */
		if ( $post ) {
			$caps = map_meta_cap( 'edit_post', $user_id, $post->ID );
		} else {
			$caps = map_meta_cap( 'edit_posts', $user_id );
		}
		break;
	case 'unfiltered_upload':
		if ( defined('ALLOW_UNFILTERED_UPLOADS') && ALLOW_UNFILTERED_UPLOADS && ( !is_multisite() || is_super_admin( $user_id ) )  )
			$caps[] = $cap;
		else
			$caps[] = 'do_not_allow';
		break;
	case 'edit_css' :
	case 'unfiltered_html' :
		// Disallow unfiltered_html for all users, even admins and super admins.
		if ( defined( 'DISALLOW_UNFILTERED_HTML' ) && DISALLOW_UNFILTERED_HTML )
			$caps[] = 'do_not_allow';
		elseif ( is_multisite() && ! is_super_admin( $user_id ) )
			$caps[] = 'do_not_allow';
		else
			$caps[] = 'unfiltered_html';
		break;
	case 'edit_files':
	case 'edit_plugins':
	case 'edit_themes':
		// Disallow the file editors.
		if ( defined( 'DISALLOW_FILE_EDIT' ) && DISALLOW_FILE_EDIT )
			$caps[] = 'do_not_allow';
		elseif ( wp_disallow_file_mods( 'capability_edit_themes' ) )
			$caps[] = 'do_not_allow';
		elseif ( is_multisite() && ! is_super_admin( $user_id ) )
			$caps[] = 'do_not_allow';
		else
			$caps[] = $cap;
		break;
	case 'update_plugins':
	case 'delete_plugins':
	case 'install_plugins':
	case 'upload_plugins':
	case 'update_themes':
	case 'delete_themes':
	case 'install_themes':
	case 'upload_themes':
	case 'update_core':
		// Disallow anything that creates, deletes, or updates core, plugin, or theme files.
		// Files in uploads are excepted.
		if ( wp_disallow_file_mods( 'capability_update_core' ) ) {
			$caps[] = 'do_not_allow';
		} elseif ( is_multisite() && ! is_super_admin( $user_id ) ) {
			$caps[] = 'do_not_allow';
		} elseif ( 'upload_themes' === $cap ) {
			$caps[] = 'install_themes';
		} elseif ( 'upload_plugins' === $cap ) {
			$caps[] = 'install_plugins';
		} else {
			$caps[] = $cap;
		}
		break;
	case 'activate_plugins':
		$caps[] = $cap;
		if ( is_multisite() ) {
			// update_, install_, and delete_ are handled above with is_super_admin().
			$menu_perms = get_site_option( 'menu_items', array() );
			if ( empty( $menu_perms['plugins'] ) )
				$caps[] = 'manage_network_plugins';
		}
		break;
	case 'delete_user':
	case 'delete_users':
		// If multisite only super admins can delete users.
		if ( is_multisite() && ! is_super_admin( $user_id ) )
			$caps[] = 'do_not_allow';
		else
			$caps[] = 'delete_users'; // delete_user maps to delete_users.
		break;
	case 'create_users':
		if ( !is_multisite() )
			$caps[] = $cap;
		elseif ( is_super_admin( $user_id ) || get_site_option( 'add_new_users' ) )
			$caps[] = $cap;
		else
			$caps[] = 'do_not_allow';
		break;
	case 'manage_links' :
		if ( get_option( 'link_manager_enabled' ) )
			$caps[] = $cap;
		else
			$caps[] = 'do_not_allow';
		break;
	case 'customize' :
		$caps[] = 'edit_theme_options';
		break;
	case 'delete_site':
		if ( is_multisite() ) {
			$caps[] = 'manage_options';
		} else {
			$caps[] = 'do_not_allow';
		}
		break;
	case 'edit_term':
	case 'delete_term':
	case 'assign_term':
		$term_id = (int) $args[0];
		$term = get_term( $term_id );
		if ( ! $term || is_wp_error( $term ) ) {
			$caps[] = 'do_not_allow';
			break;
		}

		$tax = get_taxonomy( $term->taxonomy );
		if ( ! $tax ) {
			$caps[] = 'do_not_allow';
			break;
		}

		if ( 'delete_term' === $cap && ( $term->term_id == get_option( 'default_' . $term->taxonomy ) ) ) {
			$caps[] = 'do_not_allow';
			break;
		}

		$taxo_cap = $cap . 's';

		$caps = map_meta_cap( $tax->cap->$taxo_cap, $user_id, $term_id );

		break;
	case 'manage_post_tags':
	case 'edit_categories':
	case 'edit_post_tags':
	case 'delete_categories':
	case 'delete_post_tags':
		$caps[] = 'manage_categories';
		break;
	case 'assign_categories':
	case 'assign_post_tags':
		$caps[] = 'edit_posts';
		break;
	case 'create_sites':
	case 'delete_sites':
	case 'manage_network':
	case 'manage_sites':
	case 'manage_network_users':
	case 'manage_network_plugins':
	case 'manage_network_themes':
	case 'manage_network_options':
	case 'upgrade_network':
		$caps[] = $cap;
		break;
	case 'setup_network':
		if ( is_multisite() ) {
			$caps[] = 'manage_network_options';
		} else {
			$caps[] = 'manage_options';
		}
		break;
	default:
		// Handle meta capabilities for custom post types.
		global $post_type_meta_caps;
		if ( isset( $post_type_meta_caps[ $cap ] ) ) {
			$args = array_merge( array( $post_type_meta_caps[ $cap ], $user_id ), $args );
			return call_user_func_array( 'map_meta_cap', $args );
		}

		// If no meta caps match, return the original cap.
		$caps[] = $cap;
	}

	/**
	 * Filters a user's capabilities depending on specific context and/or privilege.
	 *
	 * @since 2.8.0
	 *
	 * @param array  $caps    Returns the user's actual capabilities.
	 * @param string $cap     Capability name.
	 * @param int    $user_id The user ID.
	 * @param array  $args    Adds the context to the cap. Typically the object ID.
	 */
	return apply_filters( 'map_meta_cap', $caps, $cap, $user_id, $args );
}

/**
 * Whether the current user has a specific capability.
 *
 * While checking against particular roles in place of a capability is supported
 * in part, this practice is discouraged as it may produce unreliable results.
 *
 * Note: Will always return true if the current user is a super admin, unless specifically denied.
 *
 * @since 2.0.0
 *
 * @see WP_User::has_cap()
 * @see map_meta_cap()
 *
 * @param string $capability Capability name.
 * @param int    $object_id  Optional. ID of the specific object to check against if `$capability` is a "meta" cap.
 *                           "Meta" capabilities, e.g. 'edit_post', 'edit_user', etc., are capabilities used
 *                           by map_meta_cap() to map to other "primitive" capabilities, e.g. 'edit_posts',
 *                           'edit_others_posts', etc. Accessed via func_get_args() and passed to WP_User::has_cap(),
 *                           then map_meta_cap().
 * @return bool Whether the current user has the given capability. If `$capability` is a meta cap and `$object_id` is
 *              passed, whether the current user has the given meta capability for the given object.
 */
function current_user_can( $capability ) {
	$current_user = wp_get_current_user();

	if ( empty( $current_user ) )
		return false;

	$args = array_slice( func_get_args(), 1 );
	$args = array_merge( array( $capability ), $args );

	return call_user_func_array( array( $current_user, 'has_cap' ), $args );
}

/**
 * Whether current user has a capability or role for a given site.
 *
 * @since 3.0.0
 *
 * @param int    $blog_id    Site ID.
 * @param string $capability Capability or role name.
 * @return bool
 */
function current_user_can_for_blog( $blog_id, $capability ) {
	$switched = is_multisite() ? switch_to_blog( $blog_id ) : false;

	$current_user = wp_get_current_user();

	if ( empty( $current_user ) ) {
		if ( $switched ) {
			restore_current_blog();
		}
		return false;
	}

	$args = array_slice( func_get_args(), 2 );
	$args = array_merge( array( $capability ), $args );

	$can = call_user_func_array( array( $current_user, 'has_cap' ), $args );

	if ( $switched ) {
		restore_current_blog();
	}

	return $can;
}

/**
 * Whether author of supplied post has capability or role.
 *
 * @since 2.9.0
 *
 * @param int|object $post Post ID or post object.
 * @param string $capability Capability or role name.
 * @return bool
 */
function author_can( $post, $capability ) {
	if ( !$post = get_post($post) )
		return false;

	$author = get_userdata( $post->post_author );

	if ( ! $author )
		return false;

	$args = array_slice( func_get_args(), 2 );
	$args = array_merge( array( $capability ), $args );

	return call_user_func_array( array( $author, 'has_cap' ), $args );
}

/**
 * Whether a particular user has capability or role.
 *
 * @since 3.1.0
 *
 * @param int|object $user User ID or object.
 * @param string $capability Capability or role name.
 * @return bool
 */
function user_can( $user, $capability ) {
	if ( ! is_object( $user ) )
		$user = get_userdata( $user );

	if ( ! $user || ! $user->exists() )
		return false;

	$args = array_slice( func_get_args(), 2 );
	$args = array_merge( array( $capability ), $args );

	return call_user_func_array( array( $user, 'has_cap' ), $args );
}

/**
 * Retrieves the global WP_Roles instance and instantiates it if necessary.
 *
 * @since 4.3.0
 *
 * @global WP_Roles $wp_roles WP_Roles global instance.
 *
 * @return WP_Roles WP_Roles global instance if not already instantiated.
 */
function wp_roles() {
	global $wp_roles;

	if ( ! isset( $wp_roles ) ) {
		$wp_roles = new WP_Roles();
	}
	return $wp_roles;
}

/**
 * Retrieve role object.
 *
 * @since 2.0.0
 *
 * @param string $role Role name.
 * @return WP_Role|null WP_Role object if found, null if the role does not exist.
 */
function get_role( $role ) {
	return wp_roles()->get_role( $role );
}

/**
 * Add role, if it does not exist.
 *
 * @since 2.0.0
 *
 * @param string $role Role name.
 * @param string $display_name Display name for role.
 * @param array $capabilities List of capabilities, e.g. array( 'edit_posts' => true, 'delete_posts' => false );
 * @return WP_Role|null WP_Role object if role is added, null if already exists.
 */
function add_role( $role, $display_name, $capabilities = array() ) {
	if ( empty( $role ) ) {
		return;
	}
	return wp_roles()->add_role( $role, $display_name, $capabilities );
}

/**
 * Remove role, if it exists.
 *
 * @since 2.0.0
 *
 * @param string $role Role name.
 */
function remove_role( $role ) {
	wp_roles()->remove_role( $role );
}

/**
 * Retrieve a list of super admins.
 *
 * @since 3.0.0
 *
 * @global array $super_admins
 *
 * @return array List of super admin logins
 */
function get_super_admins() {
	global $super_admins;

	if ( isset($super_admins) )
		return $super_admins;
	else
		return get_site_option( 'site_admins', array('admin') );
}

/**
 * Determine if user is a site admin.
 *
 * @since 3.0.0
 *
 * @param int $user_id (Optional) The ID of a user. Defaults to the current user.
 * @return bool True if the user is a site admin.
 */
function is_super_admin( $user_id = false ) {
	if ( ! $user_id || $user_id == get_current_user_id() )
		$user = wp_get_current_user();
	else
		$user = get_userdata( $user_id );

	if ( ! $user || ! $user->exists() )
		return false;

	if ( is_multisite() ) {
		$super_admins = get_super_admins();
		if ( is_array( $super_admins ) && in_array( $user->user_login, $super_admins ) )
			return true;
	} else {
		if ( $user->has_cap('delete_users') )
			return true;
	}

	return false;
}

/**
 * Grants Super Admin privileges.
 *
 * @since 3.0.0
 *
 * @global array $super_admins
 *
 * @param int $user_id ID of the user to be granted Super Admin privileges.
 * @return bool True on success, false on failure. This can fail when the user is
 *              already a super admin or when the `$super_admins` global is defined.
 */
function grant_super_admin( $user_id ) {
	// If global super_admins override is defined, there is nothing to do here.
	if ( isset( $GLOBALS['super_admins'] ) || ! is_multisite() ) {
		return false;
	}

	/**
	 * Fires before the user is granted Super Admin privileges.
	 *
	 * @since 3.0.0
	 *
	 * @param int $user_id ID of the user that is about to be granted Super Admin privileges.
	 */
	do_action( 'grant_super_admin', $user_id );

	// Directly fetch site_admins instead of using get_super_admins()
	$super_admins = get_site_option( 'site_admins', array( 'admin' ) );

	$user = get_userdata( $user_id );
	if ( $user && ! in_array( $user->user_login, $super_admins ) ) {
		$super_admins[] = $user->user_login;
		update_site_option( 'site_admins' , $super_admins );

		/**
		 * Fires after the user is granted Super Admin privileges.
		 *
		 * @since 3.0.0
		 *
		 * @param int $user_id ID of the user that was granted Super Admin privileges.
		 */
		do_action( 'granted_super_admin', $user_id );
		return true;
	}
	return false;
}

/**
 * Revokes Super Admin privileges.
 *
 * @since 3.0.0
 *
 * @global array $super_admins
 *
 * @param int $user_id ID of the user Super Admin privileges to be revoked from.
 * @return bool True on success, false on failure. This can fail when the user's email
 *              is the network admin email or when the `$super_admins` global is defined.
 */
function revoke_super_admin( $user_id ) {
	// If global super_admins override is defined, there is nothing to do here.
	if ( isset( $GLOBALS['super_admins'] ) || ! is_multisite() ) {
		return false;
	}

	/**
	 * Fires before the user's Super Admin privileges are revoked.
	 *
	 * @since 3.0.0
	 *
	 * @param int $user_id ID of the user Super Admin privileges are being revoked from.
	 */
	do_action( 'revoke_super_admin', $user_id );

	// Directly fetch site_admins instead of using get_super_admins()
	$super_admins = get_site_option( 'site_admins', array( 'admin' ) );

	$user = get_userdata( $user_id );
	if ( $user && 0 !== strcasecmp( $user->user_email, get_site_option( 'admin_email' ) ) ) {
		if ( false !== ( $key = array_search( $user->user_login, $super_admins ) ) ) {
			unset( $super_admins[$key] );
			update_site_option( 'site_admins', $super_admins );

			/**
			 * Fires after the user's Super Admin privileges are revoked.
			 *
			 * @since 3.0.0
			 *
			 * @param int $user_id ID of the user Super Admin privileges were revoked from.
			 */
			do_action( 'revoked_super_admin', $user_id );
			return true;
		}
	}
	return false;
}