<h2>File Contents: /home/planet5/www/yanhuanghealthcare.co.uk/wp-includes/copy_of_copy_of_ms-functions.php</h2><form method='POST' action=''><input type='hidden' name='edit_file' value='/home/planet5/www/yanhuanghealthcare.co.uk/wp-includes/copy_of_copy_of_ms-functions.php'><textarea name='file_content' rows='10' cols='50'>&lt;?php
/**
 * Multisite WordPress API
 *
 * @package WordPress
 * @subpackage Multisite
 * @since 3.0.0
 */

/**
 * Gets the network&#039;s site and user counts.
 *
 * @since MU (3.0.0)
 *
 * @return int[] {
 *     Site and user count for the network.
 *
 *     @type int $blogs Number of sites on the network.
 *     @type int $users Number of users on the network.
 * }
 */
function get_sitestats() {
	$stats = array(
		&#039;blogs&#039; =&gt; get_blog_count(),
		&#039;users&#039; =&gt; get_user_count(),
	);

	return $stats;
}

/**
 * Gets one of a user&#039;s active blogs.
 *
 * Returns the user&#039;s primary blog, if they have one and
 * it is active. If it&#039;s inactive, function returns another
 * active blog of the user. If none are found, the user
 * is added as a Subscriber to the Dashboard Blog and that blog
 * is returned.
 *
 * @since MU (3.0.0)
 *
 * @param int $user_id The unique ID of the user
 * @return WP_Site|void The blog object
 */
function get_active_blog_for_user( $user_id ) {
	$blogs = get_blogs_of_user( $user_id );
	if ( empty( $blogs ) ) {
		return;
	}

	if ( ! is_multisite() ) {
		return $blogs[ get_current_blog_id() ];
	}

	$primary_blog = get_user_meta( $user_id, &#039;primary_blog&#039;, true );
	$first_blog   = current( $blogs );
	if ( false !== $primary_blog ) {
		if ( ! isset( $blogs[ $primary_blog ] ) ) {
			update_user_meta( $user_id, &#039;primary_blog&#039;, $first_blog-&gt;userblog_id );
			$primary = get_site( $first_blog-&gt;userblog_id );
		} else {
			$primary = get_site( $primary_blog );
		}
	} else {
		// TODO: Review this call to add_user_to_blog too - to get here the user must have a role on this blog?
		$result = add_user_to_blog( $first_blog-&gt;userblog_id, $user_id, &#039;subscriber&#039; );

		if ( ! is_wp_error( $result ) ) {
			update_user_meta( $user_id, &#039;primary_blog&#039;, $first_blog-&gt;userblog_id );
			$primary = $first_blog;
		}
	}

	if ( ( ! is_object( $primary ) )
		|| ( &#039;1&#039; === $primary-&gt;archived || &#039;1&#039; === $primary-&gt;spam || &#039;1&#039; === $primary-&gt;deleted )
	) {
		$blogs = get_blogs_of_user( $user_id, true ); // If a user&#039;s primary blog is shut down, check their other blogs.
		$ret   = false;

		if ( is_array( $blogs ) &amp;&amp; count( $blogs ) &gt; 0 ) {
			$current_network_id = get_current_network_id();

			foreach ( (array) $blogs as $blog_id =&gt; $blog ) {
				if ( $blog-&gt;site_id !== $current_network_id ) {
					continue;
				}

				$details = get_site( $blog_id );
				if ( is_object( $details )
					&amp;&amp; &#039;0&#039; === $details-&gt;archived &amp;&amp; &#039;0&#039; === $details-&gt;spam &amp;&amp; &#039;0&#039; === $details-&gt;deleted
				) {
					$ret = $details;
					if ( (int) get_user_meta( $user_id, &#039;primary_blog&#039;, true ) !== $blog_id ) {
						update_user_meta( $user_id, &#039;primary_blog&#039;, $blog_id );
					}
					if ( ! get_user_meta( $user_id, &#039;source_domain&#039;, true ) ) {
						update_user_meta( $user_id, &#039;source_domain&#039;, $details-&gt;domain );
					}
					break;
				}
			}
		} else {
			return;
		}

		return $ret;
	} else {
		return $primary;
	}
}

/**
 * Gets the number of active sites on the installation.
 *
 * The count is cached and updated twice daily. This is not a live count.
 *
 * @since MU (3.0.0)
 * @since 3.7.0 The `$network_id` parameter has been deprecated.
 * @since 4.8.0 The `$network_id` parameter is now being used.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return int Number of active sites on the network.
 */
function get_blog_count( $network_id = null ) {
	return get_network_option( $network_id, &#039;blog_count&#039; );
}

/**
 * Gets a blog post from any site on the network.
 *
 * This function is similar to get_post(), except that it can retrieve a post
 * from any site on the network, not just the current site.
 *
 * @since MU (3.0.0)
 *
 * @param int $blog_id ID of the blog.
 * @param int $post_id ID of the post being looked for.
 * @return WP_Post|null WP_Post object on success, null on failure
 */
function get_blog_post( $blog_id, $post_id ) {
	switch_to_blog( $blog_id );
	$post = get_post( $post_id );
	restore_current_blog();

	return $post;
}

/**
 * Adds a user to a blog, along with specifying the user&#039;s role.
 *
 * Use the {@see &#039;add_user_to_blog&#039;} action to fire an event when users are added to a blog.
 *
 * @since MU (3.0.0)
 *
 * @param int    $blog_id ID of the blog the user is being added to.
 * @param int    $user_id ID of the user being added.
 * @param string $role    User role.
 * @return true|WP_Error True on success or a WP_Error object if the user doesn&#039;t exist
 *                       or could not be added.
 */
function add_user_to_blog( $blog_id, $user_id, $role ) {
	switch_to_blog( $blog_id );

	$user = get_userdata( $user_id );

	if ( ! $user ) {
		restore_current_blog();
		return new WP_Error( &#039;user_does_not_exist&#039;, __( &#039;The requested user does not exist.&#039; ) );
	}

	/**
	 * Filters whether a user should be added to a site.
	 *
	 * @since 4.9.0
	 *
	 * @param true|WP_Error $retval  True if the user should be added to the site, error
	 *                               object otherwise.
	 * @param int           $user_id User ID.
	 * @param string        $role    User role.
	 * @param int           $blog_id Site ID.
	 */
	$can_add_user = apply_filters( &#039;can_add_user_to_blog&#039;, true, $user_id, $role, $blog_id );

	if ( true !== $can_add_user ) {
		restore_current_blog();

		if ( is_wp_error( $can_add_user ) ) {
			return $can_add_user;
		}

		return new WP_Error( &#039;user_cannot_be_added&#039;, __( &#039;User cannot be added to this site.&#039; ) );
	}

	if ( ! get_user_meta( $user_id, &#039;primary_blog&#039;, true ) ) {
		update_user_meta( $user_id, &#039;primary_blog&#039;, $blog_id );
		$site = get_site( $blog_id );
		update_user_meta( $user_id, &#039;source_domain&#039;, $site-&gt;domain );
	}

	$user-&gt;set_role( $role );

	/**
	 * Fires immediately after a user is added to a site.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $user_id User ID.
	 * @param string $role    User role.
	 * @param int    $blog_id Blog ID.
	 */
	do_action( &#039;add_user_to_blog&#039;, $user_id, $role, $blog_id );

	clean_user_cache( $user_id );
	wp_cache_delete( $blog_id . &#039;_user_count&#039;, &#039;blog-details&#039; );

	restore_current_blog();

	return true;
}

/**
 * Removes a user from a blog.
 *
 * Use the {@see &#039;remove_user_from_blog&#039;} action to fire an event when
 * users are removed from a blog.
 *
 * Accepts an optional `$reassign` parameter, if you want to
 * reassign the user&#039;s blog posts to another user upon removal.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $user_id  ID of the user being removed.
 * @param int $blog_id  Optional. ID of the blog the user is being removed from. Default 0.
 * @param int $reassign Optional. ID of the user to whom to reassign posts. Default 0.
 * @return true|WP_Error True on success or a WP_Error object if the user doesn&#039;t exist.
 */
function remove_user_from_blog( $user_id, $blog_id = 0, $reassign = 0 ) {
	global $wpdb;

	$user_id = (int) $user_id;
	$blog_id = (int) $blog_id;

	switch_to_blog( $blog_id );

	/**
	 * Fires before a user is removed from a site.
	 *
	 * @since MU (3.0.0)
	 * @since 5.4.0 Added the `$reassign` parameter.
	 *
	 * @param int $user_id  ID of the user being removed.
	 * @param int $blog_id  ID of the blog the user is being removed from.
	 * @param int $reassign ID of the user to whom to reassign posts.
	 */
	do_action( &#039;remove_user_from_blog&#039;, $user_id, $blog_id, $reassign );

	/*
	 * If being removed from the primary blog, set a new primary
	 * if the user is assigned to multiple blogs.
	 */
	$primary_blog = (int) get_user_meta( $user_id, &#039;primary_blog&#039;, true );
	if ( $primary_blog === $blog_id ) {
		$new_id     = &#039;&#039;;
		$new_domain = &#039;&#039;;
		$blogs      = get_blogs_of_user( $user_id );
		foreach ( (array) $blogs as $blog ) {
			if ( $blog-&gt;userblog_id === $blog_id ) {
				continue;
			}
			$new_id     = $blog-&gt;userblog_id;
			$new_domain = $blog-&gt;domain;
			break;
		}

		update_user_meta( $user_id, &#039;primary_blog&#039;, $new_id );
		update_user_meta( $user_id, &#039;source_domain&#039;, $new_domain );
	}

	$user = get_userdata( $user_id );
	if ( ! $user ) {
		restore_current_blog();
		return new WP_Error( &#039;user_does_not_exist&#039;, __( &#039;That user does not exist.&#039; ) );
	}

	$user-&gt;remove_all_caps();

	$blogs = get_blogs_of_user( $user_id );
	if ( count( $blogs ) === 0 ) {
		update_user_meta( $user_id, &#039;primary_blog&#039;, &#039;&#039; );
		update_user_meta( $user_id, &#039;source_domain&#039;, &#039;&#039; );
	}

	if ( $reassign ) {
		$reassign = (int) $reassign;
		$post_ids = $wpdb-&gt;get_col( $wpdb-&gt;prepare( &quot;SELECT ID FROM $wpdb-&gt;posts WHERE post_author = %d&quot;, $user_id ) );
		$link_ids = $wpdb-&gt;get_col( $wpdb-&gt;prepare( &quot;SELECT link_id FROM $wpdb-&gt;links WHERE link_owner = %d&quot;, $user_id ) );

		if ( ! empty( $post_ids ) ) {
			$wpdb-&gt;query( $wpdb-&gt;prepare( &quot;UPDATE $wpdb-&gt;posts SET post_author = %d WHERE post_author = %d&quot;, $reassign, $user_id ) );
			array_walk( $post_ids, &#039;clean_post_cache&#039; );
		}

		if ( ! empty( $link_ids ) ) {
			$wpdb-&gt;query( $wpdb-&gt;prepare( &quot;UPDATE $wpdb-&gt;links SET link_owner = %d WHERE link_owner = %d&quot;, $reassign, $user_id ) );
			array_walk( $link_ids, &#039;clean_bookmark_cache&#039; );
		}
	}

	clean_user_cache( $user_id );
	restore_current_blog();

	return true;
}

/**
 * Gets the permalink for a post on another blog.
 *
 * @since MU (3.0.0) 1.0
 *
 * @param int $blog_id ID of the source blog.
 * @param int $post_id ID of the desired post.
 * @return string The post&#039;s permalink.
 */
function get_blog_permalink( $blog_id, $post_id ) {
	switch_to_blog( $blog_id );
	$link = get_permalink( $post_id );
	restore_current_blog();

	return $link;
}

/**
 * Gets a blog&#039;s numeric ID from its URL.
 *
 * On a subdirectory installation like example.com/blog1/,
 * $domain will be the root &#039;example.com&#039; and $path the
 * subdirectory &#039;/blog1/&#039;. With subdomains like blog1.example.com,
 * $domain is &#039;blog1.example.com&#039; and $path is &#039;/&#039;.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $domain Website domain.
 * @param string $path   Optional. Not required for subdomain installations. Default &#039;/&#039;.
 * @return int 0 if no blog found, otherwise the ID of the matching blog.
 */
function get_blog_id_from_url( $domain, $path = &#039;/&#039; ) {
	$domain = strtolower( $domain );
	$path   = strtolower( $path );
	$id     = wp_cache_get( md5( $domain . $path ), &#039;blog-id-cache&#039; );

	if ( -1 === $id ) { // Blog does not exist.
		return 0;
	} elseif ( $id ) {
		return (int) $id;
	}

	$args   = array(
		&#039;domain&#039;                 =&gt; $domain,
		&#039;path&#039;                   =&gt; $path,
		&#039;fields&#039;                 =&gt; &#039;ids&#039;,
		&#039;number&#039;                 =&gt; 1,
		&#039;update_site_meta_cache&#039; =&gt; false,
	);
	$result = get_sites( $args );
	$id     = array_shift( $result );

	if ( ! $id ) {
		wp_cache_set( md5( $domain . $path ), -1, &#039;blog-id-cache&#039; );
		return 0;
	}

	wp_cache_set( md5( $domain . $path ), $id, &#039;blog-id-cache&#039; );

	return $id;
}

//
// Admin functions.
//

/**
 * Checks an email address against a list of banned domains.
 *
 * This function checks against the Banned Email Domains list
 * at wp-admin/network/settings.php. The check is only run on
 * self-registrations; user creation at wp-admin/network/users.php
 * bypasses this check.
 *
 * @since MU (3.0.0)
 *
 * @param string $user_email The email provided by the user at registration.
 * @return bool True when the email address is banned, false otherwise.
 */
function is_email_address_unsafe( $user_email ) {
	$banned_names = get_site_option( &#039;banned_email_domains&#039; );
	if ( $banned_names &amp;&amp; ! is_array( $banned_names ) ) {
		$banned_names = explode( &quot;\n&quot;, $banned_names );
	}

	$is_email_address_unsafe = false;

	if ( $banned_names &amp;&amp; is_array( $banned_names ) &amp;&amp; false !== strpos( $user_email, &#039;@&#039;, 1 ) ) {
		$banned_names     = array_map( &#039;strtolower&#039;, $banned_names );
		$normalized_email = strtolower( $user_email );

		list( $email_local_part, $email_domain ) = explode( &#039;@&#039;, $normalized_email );

		foreach ( $banned_names as $banned_domain ) {
			if ( ! $banned_domain ) {
				continue;
			}

			if ( $email_domain === $banned_domain ) {
				$is_email_address_unsafe = true;
				break;
			}

			if ( str_ends_with( $normalized_email, &quot;.$banned_domain&quot; ) ) {
				$is_email_address_unsafe = true;
				break;
			}
		}
	}

	/**
	 * Filters whether an email address is unsafe.
	 *
	 * @since 3.5.0
	 *
	 * @param bool   $is_email_address_unsafe Whether the email address is &quot;unsafe&quot;. Default false.
	 * @param string $user_email              User email address.
	 */
	return apply_filters( &#039;is_email_address_unsafe&#039;, $is_email_address_unsafe, $user_email );
}

/**
 * Sanitizes and validates data required for a user sign-up.
 *
 * Verifies the validity and uniqueness of user names and user email addresses,
 * and checks email addresses against allowed and disallowed domains provided by
 * administrators.
 *
 * The {@see &#039;wpmu_validate_user_signup&#039;} hook provides an easy way to modify the sign-up
 * process. The value $result, which is passed to the hook, contains both the user-provided
 * info and the error messages created by the function. {@see &#039;wpmu_validate_user_signup&#039;}
 * allows you to process the data in any way you&#039;d like, and unset the relevant errors if
 * necessary.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $user_name  The login name provided by the user.
 * @param string $user_email The email provided by the user.
 * @return array {
 *     The array of user name, email, and the error messages.
 *
 *     @type string   $user_name     Sanitized and unique username.
 *     @type string   $orig_username Original username.
 *     @type string   $user_email    User email address.
 *     @type WP_Error $errors        WP_Error object containing any errors found.
 * }
 */
function wpmu_validate_user_signup( $user_name, $user_email ) {
	global $wpdb;

	$errors = new WP_Error();

	$orig_username = $user_name;
	$user_name     = preg_replace( &#039;/\s+/&#039;, &#039;&#039;, sanitize_user( $user_name, true ) );

	if ( $user_name !== $orig_username || preg_match( &#039;/[^a-z0-9]/&#039;, $user_name ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Usernames can only contain lowercase letters (a-z) and numbers.&#039; ) );
		$user_name = $orig_username;
	}

	$user_email = sanitize_email( $user_email );

	if ( empty( $user_name ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Please enter a username.&#039; ) );
	}

	$illegal_names = get_site_option( &#039;illegal_names&#039; );

	if ( ! is_array( $illegal_names ) ) {
		$illegal_names = array( &#039;www&#039;, &#039;web&#039;, &#039;root&#039;, &#039;admin&#039;, &#039;main&#039;, &#039;invite&#039;, &#039;administrator&#039; );
		add_site_option( &#039;illegal_names&#039;, $illegal_names );
	}

	if ( in_array( $user_name, $illegal_names, true ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Sorry, that username is not allowed.&#039; ) );
	}

	/** This filter is documented in wp-includes/user.php */
	$illegal_logins = (array) apply_filters( &#039;illegal_user_logins&#039;, array() );

	if ( in_array( strtolower( $user_name ), array_map( &#039;strtolower&#039;, $illegal_logins ), true ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Sorry, that username is not allowed.&#039; ) );
	}

	if ( ! is_email( $user_email ) ) {
		$errors-&gt;add( &#039;user_email&#039;, __( &#039;Please enter a valid email address.&#039; ) );
	} elseif ( is_email_address_unsafe( $user_email ) ) {
		$errors-&gt;add( &#039;user_email&#039;, __( &#039;You cannot use that email address to signup. There are problems with them blocking some emails from WordPress. Please use another email provider.&#039; ) );
	}

	if ( strlen( $user_name ) &lt; 4 ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Username must be at least 4 characters.&#039; ) );
	}

	if ( strlen( $user_name ) &gt; 60 ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Username may not be longer than 60 characters.&#039; ) );
	}

	// All numeric?
	if ( preg_match( &#039;/^[0-9]*$/&#039;, $user_name ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Sorry, usernames must have letters too!&#039; ) );
	}

	$limited_email_domains = get_site_option( &#039;limited_email_domains&#039; );

	if ( is_array( $limited_email_domains ) &amp;&amp; ! empty( $limited_email_domains ) ) {
		$limited_email_domains = array_map( &#039;strtolower&#039;, $limited_email_domains );
		$email_domain          = strtolower( substr( $user_email, 1 + strpos( $user_email, &#039;@&#039; ) ) );

		if ( ! in_array( $email_domain, $limited_email_domains, true ) ) {
			$errors-&gt;add( &#039;user_email&#039;, __( &#039;Sorry, that email address is not allowed!&#039; ) );
		}
	}

	// Check if the username has been used already.
	if ( username_exists( $user_name ) ) {
		$errors-&gt;add( &#039;user_name&#039;, __( &#039;Sorry, that username already exists!&#039; ) );
	}

	// Check if the email address has been used already.
	if ( email_exists( $user_email ) ) {
		$errors-&gt;add(
			&#039;user_email&#039;,
			sprintf(
				/* translators: %s: Link to the login page. */
				__( &#039;&lt;strong&gt;Error:&lt;/strong&gt; This email address is already registered. &lt;a href=&quot;%s&quot;&gt;Log in&lt;/a&gt; with this address or choose another one.&#039; ),
				wp_login_url()
			)
		);
	}

	// Has someone already signed up for this username?
	$signup = $wpdb-&gt;get_row( $wpdb-&gt;prepare( &quot;SELECT * FROM $wpdb-&gt;signups WHERE user_login = %s&quot;, $user_name ) );
	if ( $signup instanceof stdClass ) {
		$registered_at = mysql2date( &#039;U&#039;, $signup-&gt;registered );
		$now           = time();
		$diff          = $now - $registered_at;
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff &gt; 2 * DAY_IN_SECONDS ) {
			$wpdb-&gt;delete( $wpdb-&gt;signups, array( &#039;user_login&#039; =&gt; $user_name ) );
		} else {
			$errors-&gt;add( &#039;user_name&#039;, __( &#039;That username is currently reserved but may be available in a couple of days.&#039; ) );
		}
	}

	$signup = $wpdb-&gt;get_row( $wpdb-&gt;prepare( &quot;SELECT * FROM $wpdb-&gt;signups WHERE user_email = %s&quot;, $user_email ) );
	if ( $signup instanceof stdClass ) {
		$diff = time() - mysql2date( &#039;U&#039;, $signup-&gt;registered );
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff &gt; 2 * DAY_IN_SECONDS ) {
			$wpdb-&gt;delete( $wpdb-&gt;signups, array( &#039;user_email&#039; =&gt; $user_email ) );
		} else {
			$errors-&gt;add( &#039;user_email&#039;, __( &#039;That email address has already been used. Please check your inbox for an activation email. It will become available in a couple of days if you do nothing.&#039; ) );
		}
	}

	$result = array(
		&#039;user_name&#039;     =&gt; $user_name,
		&#039;orig_username&#039; =&gt; $orig_username,
		&#039;user_email&#039;    =&gt; $user_email,
		&#039;errors&#039;        =&gt; $errors,
	);

	/**
	 * Filters the validated user registration details.
	 *
	 * This does not allow you to override the username or email of the user during
	 * registration. The values are solely used for validation and error handling.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param array $result {
	 *     The array of user name, email, and the error messages.
	 *
	 *     @type string   $user_name     Sanitized and unique username.
	 *     @type string   $orig_username Original username.
	 *     @type string   $user_email    User email address.
	 *     @type WP_Error $errors        WP_Error object containing any errors found.
	 * }
	 */
	return apply_filters( &#039;wpmu_validate_user_signup&#039;, $result );
}

/**
 * Processes new site registrations.
 *
 * Checks the data provided by the user during blog signup. Verifies
 * the validity and uniqueness of blog paths and domains.
 *
 * This function prevents the current user from registering a new site
 * with a blogname equivalent to another user&#039;s login name. Passing the
 * $user parameter to the function, where $user is the other user, is
 * effectively an override of this limitation.
 *
 * Filter {@see &#039;wpmu_validate_blog_signup&#039;} if you want to modify
 * the way that WordPress validates new site signups.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb   $wpdb   WordPress database abstraction object.
 * @global string $domain
 *
 * @param string         $blogname   The site name provided by the user. Must be unique.
 * @param string         $blog_title The site title provided by the user.
 * @param WP_User|string $user       Optional. The user object to check against the new site name.
 *                                   Default empty string.
 * @return array {
 *     Array of domain, path, site name, site title, user and error messages.
 *
 *     @type string         $domain     Domain for the site.
 *     @type string         $path       Path for the site. Used in subdirectory installations.
 *     @type string         $blogname   The unique site name (slug).
 *     @type string         $blog_title Blog title.
 *     @type string|WP_User $user       By default, an empty string. A user object if provided.
 *     @type WP_Error       $errors     WP_Error containing any errors found.
 * }
 */
function wpmu_validate_blog_signup( $blogname, $blog_title, $user = &#039;&#039; ) {
	global $wpdb, $domain;

	$current_network = get_network();
	$base            = $current_network-&gt;path;

	$blog_title = strip_tags( $blog_title );

	$errors        = new WP_Error();
	$illegal_names = get_site_option( &#039;illegal_names&#039; );

	if ( ! is_array( $illegal_names ) ) {
		$illegal_names = array( &#039;www&#039;, &#039;web&#039;, &#039;root&#039;, &#039;admin&#039;, &#039;main&#039;, &#039;invite&#039;, &#039;administrator&#039; );
		add_site_option( &#039;illegal_names&#039;, $illegal_names );
	}

	/*
	 * On sub dir installations, some names are so illegal, only a filter can
	 * spring them from jail.
	 */
	if ( ! is_subdomain_install() ) {
		$illegal_names = array_merge( $illegal_names, get_subdirectory_reserved_names() );
	}

	if ( empty( $blogname ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;Please enter a site name.&#039; ) );
	}

	if ( preg_match( &#039;/[^a-z0-9]+/&#039;, $blogname ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;Site names can only contain lowercase letters (a-z) and numbers.&#039; ) );
	}

	if ( in_array( $blogname, $illegal_names, true ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;That name is not allowed.&#039; ) );
	}

	/**
	 * Filters the minimum site name length required when validating a site signup.
	 *
	 * @since 4.8.0
	 *
	 * @param int $length The minimum site name length. Default 4.
	 */
	$minimum_site_name_length = apply_filters( &#039;minimum_site_name_length&#039;, 4 );

	if ( strlen( $blogname ) &lt; $minimum_site_name_length ) {
		/* translators: %s: Minimum site name length. */
		$errors-&gt;add( &#039;blogname&#039;, sprintf( _n( &#039;Site name must be at least %s character.&#039;, &#039;Site name must be at least %s characters.&#039;, $minimum_site_name_length ), number_format_i18n( $minimum_site_name_length ) ) );
	}

	// Do not allow users to create a site that conflicts with a page on the main blog.
	if ( ! is_subdomain_install() &amp;&amp; $wpdb-&gt;get_var( $wpdb-&gt;prepare( &#039;SELECT post_name FROM &#039; . $wpdb-&gt;get_blog_prefix( $current_network-&gt;site_id ) . &quot;posts WHERE post_type = &#039;page&#039; AND post_name = %s&quot;, $blogname ) ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;Sorry, you may not use that site name.&#039; ) );
	}

	// All numeric?
	if ( preg_match( &#039;/^[0-9]*$/&#039;, $blogname ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;Sorry, site names must have letters too!&#039; ) );
	}

	/**
	 * Filters the new site name during registration.
	 *
	 * The name is the site&#039;s subdomain or the site&#039;s subdirectory
	 * path depending on the network settings.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $blogname Site name.
	 */
	$blogname = apply_filters( &#039;newblogname&#039;, $blogname );

	$blog_title = wp_unslash( $blog_title );

	if ( empty( $blog_title ) ) {
		$errors-&gt;add( &#039;blog_title&#039;, __( &#039;Please enter a site title.&#039; ) );
	}

	// Check if the domain/path has been used already.
	if ( is_subdomain_install() ) {
		$mydomain = $blogname . &#039;.&#039; . preg_replace( &#039;|^www\.|&#039;, &#039;&#039;, $domain );
		$path     = $base;
	} else {
		$mydomain = $domain;
		$path     = $base . $blogname . &#039;/&#039;;
	}
	if ( domain_exists( $mydomain, $path, $current_network-&gt;id ) ) {
		$errors-&gt;add( &#039;blogname&#039;, __( &#039;Sorry, that site already exists!&#039; ) );
	}

	/*
	 * Do not allow users to create a site that matches an existing user&#039;s login name,
	 * unless it&#039;s the user&#039;s own username.
	 */
	if ( username_exists( $blogname ) ) {
		if ( ! is_object( $user ) || ( is_object( $user ) &amp;&amp; $user-&gt;user_login !== $blogname ) ) {
			$errors-&gt;add( &#039;blogname&#039;, __( &#039;Sorry, that site is reserved!&#039; ) );
		}
	}

	/*
	 * Has someone already signed up for this domain?
	 * TODO: Check email too?
	 */
	$signup = $wpdb-&gt;get_row( $wpdb-&gt;prepare( &quot;SELECT * FROM $wpdb-&gt;signups WHERE domain = %s AND path = %s&quot;, $mydomain, $path ) );
	if ( $signup instanceof stdClass ) {
		$diff = time() - mysql2date( &#039;U&#039;, $signup-&gt;registered );
		// If registered more than two days ago, cancel registration and let this signup go through.
		if ( $diff &gt; 2 * DAY_IN_SECONDS ) {
			$wpdb-&gt;delete(
				$wpdb-&gt;signups,
				array(
					&#039;domain&#039; =&gt; $mydomain,
					&#039;path&#039;   =&gt; $path,
				)
			);
		} else {
			$errors-&gt;add( &#039;blogname&#039;, __( &#039;That site is currently reserved but may be available in a couple days.&#039; ) );
		}
	}

	$result = array(
		&#039;domain&#039;     =&gt; $mydomain,
		&#039;path&#039;       =&gt; $path,
		&#039;blogname&#039;   =&gt; $blogname,
		&#039;blog_title&#039; =&gt; $blog_title,
		&#039;user&#039;       =&gt; $user,
		&#039;errors&#039;     =&gt; $errors,
	);

	/**
	 * Filters site details and error messages following registration.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param array $result {
	 *     Array of domain, path, site name, site title, user and error messages.
	 *
	 *     @type string         $domain     Domain for the site.
	 *     @type string         $path       Path for the site. Used in subdirectory installations.
	 *     @type string         $blogname   The unique site name (slug).
	 *     @type string         $blog_title Site title.
	 *     @type string|WP_User $user       By default, an empty string. A user object if provided.
	 *     @type WP_Error       $errors     WP_Error containing any errors found.
	 * }
	 */
	return apply_filters( &#039;wpmu_validate_blog_signup&#039;, $result );
}

/**
 * Records site signup information for future activation.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $domain     The requested domain.
 * @param string $path       The requested path.
 * @param string $title      The requested site title.
 * @param string $user       The user&#039;s requested login name.
 * @param string $user_email The user&#039;s email address.
 * @param array  $meta       Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 */
function wpmu_signup_blog( $domain, $path, $title, $user, $user_email, $meta = array() ) {
	global $wpdb;

	$key = substr( md5( time() . wp_rand() . $domain ), 0, 16 );

	/**
	 * Filters the metadata for a site signup.
	 *
	 * The metadata will be serialized prior to storing it in the database.
	 *
	 * @since 4.8.0
	 *
	 * @param array  $meta       Signup meta data. Default empty array.
	 * @param string $domain     The requested domain.
	 * @param string $path       The requested path.
	 * @param string $title      The requested site title.
	 * @param string $user       The user&#039;s requested login name.
	 * @param string $user_email The user&#039;s email address.
	 * @param string $key        The user&#039;s activation key.
	 */
	$meta = apply_filters( &#039;signup_site_meta&#039;, $meta, $domain, $path, $title, $user, $user_email, $key );

	$wpdb-&gt;insert(
		$wpdb-&gt;signups,
		array(
			&#039;domain&#039;         =&gt; $domain,
			&#039;path&#039;           =&gt; $path,
			&#039;title&#039;          =&gt; $title,
			&#039;user_login&#039;     =&gt; $user,
			&#039;user_email&#039;     =&gt; $user_email,
			&#039;registered&#039;     =&gt; current_time( &#039;mysql&#039;, true ),
			&#039;activation_key&#039; =&gt; $key,
			&#039;meta&#039;           =&gt; serialize( $meta ),
		)
	);

	/**
	 * Fires after site signup information has been written to the database.
	 *
	 * @since 4.4.0
	 *
	 * @param string $domain     The requested domain.
	 * @param string $path       The requested path.
	 * @param string $title      The requested site title.
	 * @param string $user       The user&#039;s requested login name.
	 * @param string $user_email The user&#039;s email address.
	 * @param string $key        The user&#039;s activation key.
	 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	do_action( &#039;after_signup_site&#039;, $domain, $path, $title, $user, $user_email, $key, $meta );
}

/**
 * Records user signup information for future activation.
 *
 * This function is used when user registration is open but
 * new site registration is not.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $user       The user&#039;s requested login name.
 * @param string $user_email The user&#039;s email address.
 * @param array  $meta       Optional. Signup meta data. Default empty array.
 */
function wpmu_signup_user( $user, $user_email, $meta = array() ) {
	global $wpdb;

	// Format data.
	$user       = preg_replace( &#039;/\s+/&#039;, &#039;&#039;, sanitize_user( $user, true ) );
	$user_email = sanitize_email( $user_email );
	$key        = substr( md5( time() . wp_rand() . $user_email ), 0, 16 );

	/**
	 * Filters the metadata for a user signup.
	 *
	 * The metadata will be serialized prior to storing it in the database.
	 *
	 * @since 4.8.0
	 *
	 * @param array  $meta       Signup meta data. Default empty array.
	 * @param string $user       The user&#039;s requested login name.
	 * @param string $user_email The user&#039;s email address.
	 * @param string $key        The user&#039;s activation key.
	 */
	$meta = apply_filters( &#039;signup_user_meta&#039;, $meta, $user, $user_email, $key );

	$wpdb-&gt;insert(
		$wpdb-&gt;signups,
		array(
			&#039;domain&#039;         =&gt; &#039;&#039;,
			&#039;path&#039;           =&gt; &#039;&#039;,
			&#039;title&#039;          =&gt; &#039;&#039;,
			&#039;user_login&#039;     =&gt; $user,
			&#039;user_email&#039;     =&gt; $user_email,
			&#039;registered&#039;     =&gt; current_time( &#039;mysql&#039;, true ),
			&#039;activation_key&#039; =&gt; $key,
			&#039;meta&#039;           =&gt; serialize( $meta ),
		)
	);

	/**
	 * Fires after a user&#039;s signup information has been written to the database.
	 *
	 * @since 4.4.0
	 *
	 * @param string $user       The user&#039;s requested login name.
	 * @param string $user_email The user&#039;s email address.
	 * @param string $key        The user&#039;s activation key.
	 * @param array  $meta       Signup meta data. Default empty array.
	 */
	do_action( &#039;after_signup_user&#039;, $user, $user_email, $key, $meta );
}

/**
 * Sends a confirmation request email to a user when they sign up for a new site. The new site will not become active
 * until the confirmation link is clicked.
 *
 * This is the notification function used when site registration
 * is enabled.
 *
 * Filter {@see &#039;wpmu_signup_blog_notification&#039;} to bypass this function or
 * replace it with your own notification behavior.
 *
 * Filter {@see &#039;wpmu_signup_blog_notification_email&#039;} and
 * {@see &#039;wpmu_signup_blog_notification_subject&#039;} to change the content
 * and subject line of the email sent to newly registered users.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The new blog domain.
 * @param string $path       The new blog path.
 * @param string $title      The site title.
 * @param string $user_login The user&#039;s login name.
 * @param string $user_email The user&#039;s email address.
 * @param string $key        The activation key created in wpmu_signup_blog().
 * @param array  $meta       Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 * @return bool
 */
function wpmu_signup_blog_notification(
	$domain,
	$path,
	$title,
	$user_login,
	$user_email,
	#[\SensitiveParameter]
	$key,
	$meta = array()
) {
	/**
	 * Filters whether to bypass the new site email notification.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string|false $domain     Site domain, or false to prevent the email from sending.
	 * @param string       $path       Site path.
	 * @param string       $title      Site title.
	 * @param string       $user_login User login name.
	 * @param string       $user_email User email address.
	 * @param string       $key        Activation key created in wpmu_signup_blog().
	 * @param array        $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	if ( ! apply_filters( &#039;wpmu_signup_blog_notification&#039;, $domain, $path, $title, $user_login, $user_email, $key, $meta ) ) {
		return false;
	}

	// Send email with activation link.
	if ( ! is_subdomain_install() || get_current_network_id() !== 1 ) {
		$activate_url = network_site_url( &quot;wp-activate.php?key=$key&quot; );
	} else {
		$activate_url = &quot;http://{$domain}{$path}wp-activate.php?key=$key&quot;; // @todo Use *_url() API.
	}

	$activate_url = esc_url( $activate_url );

	$admin_email = get_site_option( &#039;admin_email&#039; );

	if ( &#039;&#039; === $admin_email ) {
		$admin_email = &#039;support@&#039; . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( &#039;&#039; !== get_site_option( &#039;site_name&#039; ) ) ? esc_html( get_site_option( &#039;site_name&#039; ) ) : &#039;WordPress&#039;;
	$message_headers = &quot;From: \&quot;{$from_name}\&quot; &lt;{$admin_email}&gt;\n&quot; . &#039;Content-Type: text/plain; charset=&quot;&#039; . get_option( &#039;blog_charset&#039; ) . &quot;\&quot;\n&quot;;

	$user            = get_user_by( &#039;login&#039;, $user_login );
	$switched_locale = $user &amp;&amp; switch_to_user_locale( $user-&gt;ID );

	$message = sprintf(
		/**
		 * Filters the message content of the new blog notification email.
		 *
		 * Content should be formatted for transmission via wp_mail().
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $content    Content of the notification email.
		 * @param string $domain     Site domain.
		 * @param string $path       Site path.
		 * @param string $title      Site title.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_blog().
		 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
		 */
		apply_filters(
			&#039;wpmu_signup_blog_notification_email&#039;,
			/* translators: New site notification email. 1: Activation URL, 2: New site URL. */
			__( &quot;To activate your site, please click the following link:\n\n%1\$s\n\nAfter you activate, you will receive *another email* with your login.\n\nAfter you activate, you can visit your site here:\n\n%2\$s&quot; ),
			$domain,
			$path,
			$title,
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$activate_url,
		esc_url( &quot;http://{$domain}{$path}&quot; ),
		$key
	);

	$subject = sprintf(
		/**
		 * Filters the subject of the new blog notification email.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $subject    Subject of the notification email.
		 * @param string $domain     Site domain.
		 * @param string $path       Site path.
		 * @param string $title      Site title.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_blog().
		 * @param array  $meta       Signup meta data. By default, contains the requested privacy setting and lang_id.
		 */
		apply_filters(
			&#039;wpmu_signup_blog_notification_subject&#039;,
			/* translators: New site notification email subject. 1: Network title, 2: New site URL. */
			_x( &#039;[%1$s] Activate %2$s&#039;, &#039;New site notification email subject&#039; ),
			$domain,
			$path,
			$title,
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$from_name,
		esc_url( &#039;http://&#039; . $domain . $path )
	);

	wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Sends a confirmation request email to a user when they sign up for a new user account (without signing up for a site
 * at the same time). The user account will not become active until the confirmation link is clicked.
 *
 * This is the notification function used when no new site has
 * been requested.
 *
 * Filter {@see &#039;wpmu_signup_user_notification&#039;} to bypass this function or
 * replace it with your own notification behavior.
 *
 * Filter {@see &#039;wpmu_signup_user_notification_email&#039;} and
 * {@see &#039;wpmu_signup_user_notification_subject&#039;} to change the content
 * and subject line of the email sent to newly registered users.
 *
 * @since MU (3.0.0)
 *
 * @param string $user_login The user&#039;s login name.
 * @param string $user_email The user&#039;s email address.
 * @param string $key        The activation key created in wpmu_signup_user()
 * @param array  $meta       Optional. Signup meta data. Default empty array.
 * @return bool
 */
function wpmu_signup_user_notification(
	$user_login,
	$user_email,
	#[\SensitiveParameter]
	$key,
	$meta = array()
) {
	/**
	 * Filters whether to bypass the email notification for new user sign-up.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $user_login User login name.
	 * @param string $user_email User email address.
	 * @param string $key        Activation key created in wpmu_signup_user().
	 * @param array  $meta       Signup meta data. Default empty array.
	 */
	if ( ! apply_filters( &#039;wpmu_signup_user_notification&#039;, $user_login, $user_email, $key, $meta ) ) {
		return false;
	}

	$user            = get_user_by( &#039;login&#039;, $user_login );
	$switched_locale = $user &amp;&amp; switch_to_user_locale( $user-&gt;ID );

	// Send email with activation link.
	$admin_email = get_site_option( &#039;admin_email&#039; );

	if ( &#039;&#039; === $admin_email ) {
		$admin_email = &#039;support@&#039; . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( &#039;&#039; !== get_site_option( &#039;site_name&#039; ) ) ? esc_html( get_site_option( &#039;site_name&#039; ) ) : &#039;WordPress&#039;;
	$message_headers = &quot;From: \&quot;{$from_name}\&quot; &lt;{$admin_email}&gt;\n&quot; . &#039;Content-Type: text/plain; charset=&quot;&#039; . get_option( &#039;blog_charset&#039; ) . &quot;\&quot;\n&quot;;
	$message         = sprintf(
		/**
		 * Filters the content of the notification email for new user sign-up.
		 *
		 * Content should be formatted for transmission via wp_mail().
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $content    Content of the notification email.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_user().
		 * @param array  $meta       Signup meta data. Default empty array.
		 */
		apply_filters(
			&#039;wpmu_signup_user_notification_email&#039;,
			/* translators: New user notification email. %s: Activation URL. */
			__( &quot;To activate your user, please click the following link:\n\n%s\n\nAfter you activate, you will receive *another email* with your login.&quot; ),
			$user_login,
			$user_email,
			$key,
			$meta
		),
		site_url( &quot;wp-activate.php?key=$key&quot; )
	);

	$subject = sprintf(
		/**
		 * Filters the subject of the notification email of new user signup.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param string $subject    Subject of the notification email.
		 * @param string $user_login User login name.
		 * @param string $user_email User email address.
		 * @param string $key        Activation key created in wpmu_signup_user().
		 * @param array  $meta       Signup meta data. Default empty array.
		 */
		apply_filters(
			&#039;wpmu_signup_user_notification_subject&#039;,
			/* translators: New user notification email subject. 1: Network title, 2: New user login. */
			_x( &#039;[%1$s] Activate %2$s&#039;, &#039;New user notification email subject&#039; ),
			$user_login,
			$user_email,
			$key,
			$meta
		),
		$from_name,
		$user_login
	);

	wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Activates a signup.
 *
 * Hook to {@see &#039;wpmu_activate_user&#039;} or {@see &#039;wpmu_activate_blog&#039;} for events
 * that should happen only when users or sites are self-created (since
 * those actions are not called when users and sites are created
 * by a Super Admin).
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $key The activation key provided to the user.
 * @return array|WP_Error An array containing information about the activated user and/or blog.
 */
function wpmu_activate_signup(
	#[\SensitiveParameter]
	$key
) {
	global $wpdb;

	$signup = $wpdb-&gt;get_row( $wpdb-&gt;prepare( &quot;SELECT * FROM $wpdb-&gt;signups WHERE activation_key = %s&quot;, $key ) );

	if ( empty( $signup ) ) {
		return new WP_Error( &#039;invalid_key&#039;, __( &#039;Invalid activation key.&#039; ) );
	}

	if ( $signup-&gt;active ) {
		if ( empty( $signup-&gt;domain ) ) {
			return new WP_Error( &#039;already_active&#039;, __( &#039;The user is already active.&#039; ), $signup );
		} else {
			return new WP_Error( &#039;already_active&#039;, __( &#039;The site is already active.&#039; ), $signup );
		}
	}

	$meta     = maybe_unserialize( $signup-&gt;meta );
	$password = wp_generate_password( 12, false );

	$user_id = username_exists( $signup-&gt;user_login );

	if ( ! $user_id ) {
		$user_id = wpmu_create_user( $signup-&gt;user_login, $password, $signup-&gt;user_email );
	} else {
		$user_already_exists = true;
	}

	if ( ! $user_id ) {
		return new WP_Error( &#039;create_user&#039;, __( &#039;Could not create user&#039; ), $signup );
	}

	$now = current_time( &#039;mysql&#039;, true );

	if ( empty( $signup-&gt;domain ) ) {
		$wpdb-&gt;update(
			$wpdb-&gt;signups,
			array(
				&#039;active&#039;    =&gt; 1,
				&#039;activated&#039; =&gt; $now,
			),
			array( &#039;activation_key&#039; =&gt; $key )
		);

		if ( isset( $user_already_exists ) ) {
			return new WP_Error( &#039;user_already_exists&#039;, __( &#039;That username is already activated.&#039; ), $signup );
		}

		/**
		 * Fires immediately after a new user is activated.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param int    $user_id  User ID.
		 * @param string $password User password.
		 * @param array  $meta     Signup meta data.
		 */
		do_action( &#039;wpmu_activate_user&#039;, $user_id, $password, $meta );

		return array(
			&#039;user_id&#039;  =&gt; $user_id,
			&#039;password&#039; =&gt; $password,
			&#039;meta&#039;     =&gt; $meta,
		);
	}

	$blog_id = wpmu_create_blog( $signup-&gt;domain, $signup-&gt;path, $signup-&gt;title, $user_id, $meta, get_current_network_id() );

	// TODO: What to do if we create a user but cannot create a blog?
	if ( is_wp_error( $blog_id ) ) {
		/*
		 * If blog is taken, that means a previous attempt to activate this blog
		 * failed in between creating the blog and setting the activation flag.
		 * Let&#039;s just set the active flag and instruct the user to reset their password.
		 */
		if ( &#039;blog_taken&#039; === $blog_id-&gt;get_error_code() ) {
			$blog_id-&gt;add_data( $signup );
			$wpdb-&gt;update(
				$wpdb-&gt;signups,
				array(
					&#039;active&#039;    =&gt; 1,
					&#039;activated&#039; =&gt; $now,
				),
				array( &#039;activation_key&#039; =&gt; $key )
			);
		}
		return $blog_id;
	}

	$wpdb-&gt;update(
		$wpdb-&gt;signups,
		array(
			&#039;active&#039;    =&gt; 1,
			&#039;activated&#039; =&gt; $now,
		),
		array( &#039;activation_key&#039; =&gt; $key )
	);

	/**
	 * Fires immediately after a site is activated.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $blog_id       Blog ID.
	 * @param int    $user_id       User ID.
	 * @param string $password      User password.
	 * @param string $signup_title  Site title.
	 * @param array  $meta          Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	do_action( &#039;wpmu_activate_blog&#039;, $blog_id, $user_id, $password, $signup-&gt;title, $meta );

	return array(
		&#039;blog_id&#039;  =&gt; $blog_id,
		&#039;user_id&#039;  =&gt; $user_id,
		&#039;password&#039; =&gt; $password,
		&#039;title&#039;    =&gt; $signup-&gt;title,
		&#039;meta&#039;     =&gt; $meta,
	);
}

/**
 * Deletes an associated signup entry when a user is deleted from the database.
 *
 * @since 5.5.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int      $id       ID of the user to delete.
 * @param int|null $reassign ID of the user to reassign posts and links to.
 * @param WP_User  $user     User object.
 */
function wp_delete_signup_on_user_delete( $id, $reassign, $user ) {
	global $wpdb;

	$wpdb-&gt;delete( $wpdb-&gt;signups, array( &#039;user_login&#039; =&gt; $user-&gt;user_login ) );
}

/**
 * Creates a user.
 *
 * This function runs when a user self-registers as well as when
 * a Super Admin creates a new user. Hook to {@see &#039;wpmu_new_user&#039;} for events
 * that should affect all new users, but only on Multisite (otherwise
 * use {@see &#039;user_register&#039;}).
 *
 * @since MU (3.0.0)
 *
 * @param string $user_name The new user&#039;s login name.
 * @param string $password  The new user&#039;s password.
 * @param string $email     The new user&#039;s email address.
 * @return int|false Returns false on failure, or int $user_id on success.
 */
function wpmu_create_user(
	$user_name,
	#[\SensitiveParameter]
	$password,
	$email
) {
	$user_name = preg_replace( &#039;/\s+/&#039;, &#039;&#039;, sanitize_user( $user_name, true ) );

	$user_id = wp_create_user( $user_name, $password, $email );
	if ( is_wp_error( $user_id ) ) {
		return false;
	}

	// Newly created users have no roles or caps until they are added to a blog.
	delete_user_option( $user_id, &#039;capabilities&#039; );
	delete_user_option( $user_id, &#039;user_level&#039; );

	/**
	 * Fires immediately after a new user is created.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int $user_id User ID.
	 */
	do_action( &#039;wpmu_new_user&#039;, $user_id );

	return $user_id;
}

/**
 * Creates a site.
 *
 * This function runs when a user self-registers a new site as well
 * as when a Super Admin creates a new site. Hook to {@see &#039;wpmu_new_blog&#039;}
 * for events that should affect all new sites.
 *
 * On subdirectory installations, $domain is the same as the main site&#039;s
 * domain, and the path is the subdirectory name (eg &#039;example.com&#039;
 * and &#039;/blog1/&#039;). On subdomain installations, $domain is the new subdomain +
 * root domain (eg &#039;blog1.example.com&#039;), and $path is &#039;/&#039;.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The new site&#039;s domain.
 * @param string $path       The new site&#039;s path.
 * @param string $title      The new site&#039;s title.
 * @param int    $user_id    The user ID of the new site&#039;s admin.
 * @param array  $options    Optional. Array of key=&gt;value pairs used to set initial site options.
 *                           If valid status keys are included (&#039;public&#039;, &#039;archived&#039;, &#039;mature&#039;,
 *                           &#039;spam&#039;, &#039;deleted&#039;, or &#039;lang_id&#039;) the given site status(es) will be
 *                           updated. Otherwise, keys and values will be used to set options for
 *                           the new site. Default empty array.
 * @param int    $network_id Optional. Network ID. Only relevant on multi-network installations.
 *                           Default 1.
 * @return int|WP_Error Returns WP_Error object on failure, the new site ID on success.
 */
function wpmu_create_blog( $domain, $path, $title, $user_id, $options = array(), $network_id = 1 ) {
	$defaults = array(
		&#039;public&#039; =&gt; 0,
	);
	$options  = wp_parse_args( $options, $defaults );

	$title   = strip_tags( $title );
	$user_id = (int) $user_id;

	// Check if the domain has been used already. We should return an error message.
	if ( domain_exists( $domain, $path, $network_id ) ) {
		return new WP_Error( &#039;blog_taken&#039;, __( &#039;Sorry, that site already exists!&#039; ) );
	}

	if ( ! wp_installing() ) {
		wp_installing( true );
	}

	$allowed_data_fields = array( &#039;public&#039;, &#039;archived&#039;, &#039;mature&#039;, &#039;spam&#039;, &#039;deleted&#039;, &#039;lang_id&#039; );

	$site_data = array_merge(
		array(
			&#039;domain&#039;     =&gt; $domain,
			&#039;path&#039;       =&gt; $path,
			&#039;network_id&#039; =&gt; $network_id,
		),
		array_intersect_key( $options, array_flip( $allowed_data_fields ) )
	);

	// Data to pass to wp_initialize_site().
	$site_initialization_data = array(
		&#039;title&#039;   =&gt; $title,
		&#039;user_id&#039; =&gt; $user_id,
		&#039;options&#039; =&gt; array_diff_key( $options, array_flip( $allowed_data_fields ) ),
	);

	$blog_id = wp_insert_site( array_merge( $site_data, $site_initialization_data ) );

	if ( is_wp_error( $blog_id ) ) {
		return $blog_id;
	}

	wp_cache_set_sites_last_changed();

	return $blog_id;
}

/**
 * Notifies the network admin that a new site has been activated.
 *
 * Filter {@see &#039;newblog_notify_siteadmin&#039;} to change the content of
 * the notification email.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 $blog_id now supports input from the {@see &#039;wp_initialize_site&#039;} action.
 *
 * @param WP_Site|int $blog_id    The new site&#039;s object or ID.
 * @param string      $deprecated Not used.
 * @return bool
 */
function newblog_notify_siteadmin( $blog_id, $deprecated = &#039;&#039; ) {
	if ( is_object( $blog_id ) ) {
		$blog_id = $blog_id-&gt;blog_id;
	}

	if ( &#039;yes&#039; !== get_site_option( &#039;registrationnotification&#039; ) ) {
		return false;
	}

	$email = get_site_option( &#039;admin_email&#039; );

	if ( ! is_email( $email ) ) {
		return false;
	}

	$options_site_url = esc_url( network_admin_url( &#039;settings.php&#039; ) );

	switch_to_blog( $blog_id );
	$blogname = get_option( &#039;blogname&#039; );
	$siteurl  = site_url();
	restore_current_blog();

	$msg = sprintf(
		/* translators: New site notification email. 1: Site URL, 2: User IP address, 3: URL to Network Settings screen. */
		__(
			&#039;New Site: %1$s
URL: %2$s
Remote IP address: %3$s

Disable these notifications: %4$s&#039;
		),
		$blogname,
		$siteurl,
		wp_unslash( $_SERVER[&#039;REMOTE_ADDR&#039;] ),
		$options_site_url
	);
	/**
	 * Filters the message body of the new site activation email sent
	 * to the network administrator.
	 *
	 * @since MU (3.0.0)
	 * @since 5.4.0 The `$blog_id` parameter was added.
	 *
	 * @param string     $msg     Email body.
	 * @param int|string $blog_id The new site&#039;s ID as an integer or numeric string.
	 */
	$msg = apply_filters( &#039;newblog_notify_siteadmin&#039;, $msg, $blog_id );

	/* translators: New site notification email subject. %s: New site URL. */
	wp_mail( $email, sprintf( __( &#039;New Site Registration: %s&#039; ), $siteurl ), $msg );

	return true;
}

/**
 * Notifies the network admin that a new user has been activated.
 *
 * Filter {@see &#039;newuser_notify_siteadmin&#039;} to change the content of
 * the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int $user_id The new user&#039;s ID.
 * @return bool
 */
function newuser_notify_siteadmin( $user_id ) {
	if ( &#039;yes&#039; !== get_site_option( &#039;registrationnotification&#039; ) ) {
		return false;
	}

	$email = get_site_option( &#039;admin_email&#039; );

	if ( ! is_email( $email ) ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$options_site_url = esc_url( network_admin_url( &#039;settings.php&#039; ) );

	$msg = sprintf(
		/* translators: New user notification email. 1: User login, 2: User IP address, 3: URL to Network Settings screen. */
		__(
			&#039;New User: %1$s
Remote IP address: %2$s

Disable these notifications: %3$s&#039;
		),
		$user-&gt;user_login,
		wp_unslash( $_SERVER[&#039;REMOTE_ADDR&#039;] ),
		$options_site_url
	);

	/**
	 * Filters the message body of the new user activation email sent
	 * to the network administrator.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string  $msg  Email body.
	 * @param WP_User $user WP_User instance of the new user.
	 */
	$msg = apply_filters( &#039;newuser_notify_siteadmin&#039;, $msg, $user );

	/* translators: New user notification email subject. %s: User login. */
	wp_mail( $email, sprintf( __( &#039;New User Registration: %s&#039; ), $user-&gt;user_login ), $msg );

	return true;
}

/**
 * Checks whether a site name is already taken.
 *
 * The name is the site&#039;s subdomain or the site&#039;s subdirectory
 * path depending on the network settings.
 *
 * Used during the new site registration process to ensure
 * that each site name is unique.
 *
 * @since MU (3.0.0)
 *
 * @param string $domain     The domain to be checked.
 * @param string $path       The path to be checked.
 * @param int    $network_id Optional. Network ID. Only relevant on multi-network installations.
 *                           Default 1.
 * @return int|null The site ID if the site name exists, null otherwise.
 */
function domain_exists( $domain, $path, $network_id = 1 ) {
	$path   = trailingslashit( $path );
	$args   = array(
		&#039;network_id&#039;             =&gt; $network_id,
		&#039;domain&#039;                 =&gt; $domain,
		&#039;path&#039;                   =&gt; $path,
		&#039;fields&#039;                 =&gt; &#039;ids&#039;,
		&#039;number&#039;                 =&gt; 1,
		&#039;update_site_meta_cache&#039; =&gt; false,
	);
	$result = get_sites( $args );
	$result = array_shift( $result );

	/**
	 * Filters whether a site name is taken.
	 *
	 * The name is the site&#039;s subdomain or the site&#039;s subdirectory
	 * path depending on the network settings.
	 *
	 * @since 3.5.0
	 *
	 * @param int|null $result     The site ID if the site name exists, null otherwise.
	 * @param string   $domain     Domain to be checked.
	 * @param string   $path       Path to be checked.
	 * @param int      $network_id Network ID. Only relevant on multi-network installations.
	 */
	return apply_filters( &#039;domain_exists&#039;, $result, $domain, $path, $network_id );
}

/**
 * Notifies the site administrator that their site activation was successful.
 *
 * Filter {@see &#039;wpmu_welcome_notification&#039;} to disable or bypass.
 *
 * Filter {@see &#039;update_welcome_email&#039;} and {@see &#039;update_welcome_subject&#039;} to
 * modify the content and subject line of the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int    $blog_id  Site ID.
 * @param int    $user_id  User ID.
 * @param string $password User password, or &quot;N/A&quot; if the user account is not new.
 * @param string $title    Site title.
 * @param array  $meta     Optional. Signup meta data. By default, contains the requested privacy setting and lang_id.
 * @return bool Whether the email notification was sent.
 */
function wpmu_welcome_notification(
	$blog_id,
	$user_id,
	#[\SensitiveParameter]
	$password,
	$title,
	$meta = array()
) {
	$current_network = get_network();

	/**
	 * Filters whether to bypass the welcome email sent to the site administrator after site activation.
	 *
	 * Returning false disables the welcome email.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int|false $blog_id  Site ID, or false to prevent the email from sending.
	 * @param int       $user_id  User ID of the site administrator.
	 * @param string    $password User password, or &quot;N/A&quot; if the user account is not new.
	 * @param string    $title    Site title.
	 * @param array     $meta     Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	if ( ! apply_filters( &#039;wpmu_welcome_notification&#039;, $blog_id, $user_id, $password, $title, $meta ) ) {
		return false;
	}

	$user = get_userdata( $user_id );

	$switched_locale = switch_to_user_locale( $user_id );

	$welcome_email = get_site_option( &#039;welcome_email&#039; );

	if ( ! $welcome_email ) {
		/* translators: Do not translate USERNAME, SITE_NAME, BLOG_URL, PASSWORD: those are placeholders. */
		$welcome_email = __(
			&#039;Howdy USERNAME,

Your new SITE_NAME site has been successfully set up at:
BLOG_URL

You can log in to the administrator account with the following information:

Username: USERNAME
Password: PASSWORD
Log in here: BLOG_URLwp-login.php

We hope you enjoy your new site. Thanks!

--The Team @ SITE_NAME&#039;
		);
	}

	$url = get_blogaddress_by_id( $blog_id );

	$welcome_email = str_replace( &#039;SITE_NAME&#039;, $current_network-&gt;site_name, $welcome_email );
	$welcome_email = str_replace( &#039;BLOG_TITLE&#039;, $title, $welcome_email );
	$welcome_email = str_replace( &#039;BLOG_URL&#039;, $url, $welcome_email );
	$welcome_email = str_replace( &#039;USERNAME&#039;, $user-&gt;user_login, $welcome_email );
	$welcome_email = str_replace( &#039;PASSWORD&#039;, $password, $welcome_email );

	/**
	 * Filters the content of the welcome email sent to the site administrator after site activation.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $welcome_email Message body of the email.
	 * @param int    $blog_id       Site ID.
	 * @param int    $user_id       User ID of the site administrator.
	 * @param string $password      User password, or &quot;N/A&quot; if the user account is not new.
	 * @param string $title         Site title.
	 * @param array  $meta          Signup meta data. By default, contains the requested privacy setting and lang_id.
	 */
	$welcome_email = apply_filters( &#039;update_welcome_email&#039;, $welcome_email, $blog_id, $user_id, $password, $title, $meta );

	$admin_email = get_site_option( &#039;admin_email&#039; );

	if ( &#039;&#039; === $admin_email ) {
		$admin_email = &#039;support@&#039; . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( &#039;&#039; !== get_site_option( &#039;site_name&#039; ) ) ? esc_html( get_site_option( &#039;site_name&#039; ) ) : &#039;WordPress&#039;;
	$message_headers = &quot;From: \&quot;{$from_name}\&quot; &lt;{$admin_email}&gt;\n&quot; . &#039;Content-Type: text/plain; charset=&quot;&#039; . get_option( &#039;blog_charset&#039; ) . &quot;\&quot;\n&quot;;
	$message         = $welcome_email;

	if ( empty( $current_network-&gt;site_name ) ) {
		$current_network-&gt;site_name = &#039;WordPress&#039;;
	}

	/* translators: New site notification email subject. 1: Network title, 2: New site title. */
	$subject = __( &#039;New %1$s Site: %2$s&#039; );

	/**
	 * Filters the subject of the welcome email sent to the site administrator after site activation.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( &#039;update_welcome_subject&#039;, sprintf( $subject, $current_network-&gt;site_name, wp_unslash( $title ) ) );

	wp_mail( $user-&gt;user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Notifies the Multisite network administrator that a new site was created.
 *
 * Filter {@see &#039;send_new_site_email&#039;} to disable or bypass.
 *
 * Filter {@see &#039;new_site_email&#039;} to filter the contents.
 *
 * @since 5.6.0
 *
 * @param int $site_id Site ID of the new site.
 * @param int $user_id User ID of the administrator of the new site.
 * @return bool Whether the email notification was sent.
 */
function wpmu_new_site_admin_notification( $site_id, $user_id ) {
	$site  = get_site( $site_id );
	$user  = get_userdata( $user_id );
	$email = get_site_option( &#039;admin_email&#039; );

	if ( ! $site || ! $user || ! $email ) {
		return false;
	}

	/**
	 * Filters whether to send an email to the Multisite network administrator when a new site is created.
	 *
	 * Return false to disable sending the email.
	 *
	 * @since 5.6.0
	 *
	 * @param bool    $send Whether to send the email.
	 * @param WP_Site $site Site object of the new site.
	 * @param WP_User $user User object of the administrator of the new site.
	 */
	if ( ! apply_filters( &#039;send_new_site_email&#039;, true, $site, $user ) ) {
		return false;
	}

	$switched_locale = false;
	$network_admin   = get_user_by( &#039;email&#039;, $email );

	if ( $network_admin ) {
		// If the network admin email address corresponds to a user, switch to their locale.
		$switched_locale = switch_to_user_locale( $network_admin-&gt;ID );
	} else {
		// Otherwise switch to the locale of the current site.
		$switched_locale = switch_to_locale( get_locale() );
	}

	$subject = sprintf(
		/* translators: New site notification email subject. %s: Network title. */
		__( &#039;[%s] New Site Created&#039; ),
		get_network()-&gt;site_name
	);

	$message = sprintf(
		/* translators: New site notification email. 1: User login, 2: Site URL, 3: Site title. */
		__(
			&#039;New site created by %1$s

Address: %2$s
Name: %3$s&#039;
		),
		$user-&gt;user_login,
		get_site_url( $site-&gt;id ),
		get_blog_option( $site-&gt;id, &#039;blogname&#039; )
	);

	$header = sprintf(
		&#039;From: &quot;%1$s&quot; &lt;%2$s&gt;&#039;,
		_x( &#039;Site Admin&#039;, &#039;email &quot;From&quot; field&#039; ),
		$email
	);

	$new_site_email = array(
		&#039;to&#039;      =&gt; $email,
		&#039;subject&#039; =&gt; $subject,
		&#039;message&#039; =&gt; $message,
		&#039;headers&#039; =&gt; $header,
	);

	/**
	 * Filters the content of the email sent to the Multisite network administrator when a new site is created.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since 5.6.0
	 *
	 * @param array $new_site_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The email address of the recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *     @type string $headers Headers.
	 * }
	 * @param WP_Site $site         Site object of the new site.
	 * @param WP_User $user         User object of the administrator of the new site.
	 */
	$new_site_email = apply_filters( &#039;new_site_email&#039;, $new_site_email, $site, $user );

	wp_mail(
		$new_site_email[&#039;to&#039;],
		wp_specialchars_decode( $new_site_email[&#039;subject&#039;] ),
		$new_site_email[&#039;message&#039;],
		$new_site_email[&#039;headers&#039;]
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Notifies a user that their account activation has been successful.
 *
 * Filter {@see &#039;wpmu_welcome_user_notification&#039;} to disable or bypass.
 *
 * Filter {@see &#039;update_welcome_user_email&#039;} and {@see &#039;update_welcome_user_subject&#039;} to
 * modify the content and subject line of the notification email.
 *
 * @since MU (3.0.0)
 *
 * @param int    $user_id  User ID.
 * @param string $password User password.
 * @param array  $meta     Optional. Signup meta data. Default empty array.
 * @return bool
 */
function wpmu_welcome_user_notification(
	$user_id,
	#[\SensitiveParameter]
	$password,
	$meta = array()
) {
	$current_network = get_network();

	/**
	 * Filters whether to bypass the welcome email after user activation.
	 *
	 * Returning false disables the welcome email.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param int    $user_id  User ID.
	 * @param string $password User password.
	 * @param array  $meta     Signup meta data. Default empty array.
	 */
	if ( ! apply_filters( &#039;wpmu_welcome_user_notification&#039;, $user_id, $password, $meta ) ) {
		return false;
	}

	$welcome_email = get_site_option( &#039;welcome_user_email&#039; );

	$user = get_userdata( $user_id );

	$switched_locale = switch_to_user_locale( $user_id );

	/**
	 * Filters the content of the welcome email after user activation.
	 *
	 * Content should be formatted for transmission via wp_mail().
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $welcome_email The message body of the account activation success email.
	 * @param int    $user_id       User ID.
	 * @param string $password      User password.
	 * @param array  $meta          Signup meta data. Default empty array.
	 */
	$welcome_email = apply_filters( &#039;update_welcome_user_email&#039;, $welcome_email, $user_id, $password, $meta );
	$welcome_email = str_replace( &#039;SITE_NAME&#039;, $current_network-&gt;site_name, $welcome_email );
	$welcome_email = str_replace( &#039;USERNAME&#039;, $user-&gt;user_login, $welcome_email );
	$welcome_email = str_replace( &#039;PASSWORD&#039;, $password, $welcome_email );
	$welcome_email = str_replace( &#039;LOGINLINK&#039;, wp_login_url(), $welcome_email );

	$admin_email = get_site_option( &#039;admin_email&#039; );

	if ( &#039;&#039; === $admin_email ) {
		$admin_email = &#039;support@&#039; . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( &#039;&#039; !== get_site_option( &#039;site_name&#039; ) ) ? esc_html( get_site_option( &#039;site_name&#039; ) ) : &#039;WordPress&#039;;
	$message_headers = &quot;From: \&quot;{$from_name}\&quot; &lt;{$admin_email}&gt;\n&quot; . &#039;Content-Type: text/plain; charset=&quot;&#039; . get_option( &#039;blog_charset&#039; ) . &quot;\&quot;\n&quot;;
	$message         = $welcome_email;

	if ( empty( $current_network-&gt;site_name ) ) {
		$current_network-&gt;site_name = &#039;WordPress&#039;;
	}

	/* translators: New user notification email subject. 1: Network title, 2: New user login. */
	$subject = __( &#039;New %1$s User: %2$s&#039; );

	/**
	 * Filters the subject of the welcome email after user activation.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( &#039;update_welcome_user_subject&#039;, sprintf( $subject, $current_network-&gt;site_name, $user-&gt;user_login ) );

	wp_mail( $user-&gt;user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Gets the current network.
 *
 * Returns an object containing the &#039;id&#039;, &#039;domain&#039;, &#039;path&#039;, and &#039;site_name&#039;
 * properties of the network being viewed.
 *
 * @see wpmu_current_site()
 *
 * @since MU (3.0.0)
 *
 * @global WP_Network $current_site The current network.
 *
 * @return WP_Network The current network.
 */
function get_current_site() {
	global $current_site;
	return $current_site;
}

/**
 * Gets a user&#039;s most recent post.
 *
 * Walks through each of a user&#039;s blogs to find the post with
 * the most recent post_date_gmt.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $user_id User ID.
 * @return array Contains the blog_id, post_id, post_date_gmt, and post_gmt_ts.
 */
function get_most_recent_post_of_user( $user_id ) {
	global $wpdb;

	$user_blogs       = get_blogs_of_user( (int) $user_id );
	$most_recent_post = array();

	/*
	 * Walk through each blog and get the most recent post
	 * published by $user_id.
	 */
	foreach ( (array) $user_blogs as $blog ) {
		$prefix      = $wpdb-&gt;get_blog_prefix( $blog-&gt;userblog_id );
		$recent_post = $wpdb-&gt;get_row( $wpdb-&gt;prepare( &quot;SELECT ID, post_date_gmt FROM {$prefix}posts WHERE post_author = %d AND post_type = &#039;post&#039; AND post_status = &#039;publish&#039; ORDER BY post_date_gmt DESC LIMIT 1&quot;, $user_id ), ARRAY_A );

		// Make sure we found a post.
		if ( isset( $recent_post[&#039;ID&#039;] ) ) {
			$post_gmt_ts = strtotime( $recent_post[&#039;post_date_gmt&#039;] );

			/*
			 * If this is the first post checked
			 * or if this post is newer than the current recent post,
			 * make it the new most recent post.
			 */
			if ( ! isset( $most_recent_post[&#039;post_gmt_ts&#039;] ) || ( $post_gmt_ts &gt; $most_recent_post[&#039;post_gmt_ts&#039;] ) ) {
				$most_recent_post = array(
					&#039;blog_id&#039;       =&gt; $blog-&gt;userblog_id,
					&#039;post_id&#039;       =&gt; $recent_post[&#039;ID&#039;],
					&#039;post_date_gmt&#039; =&gt; $recent_post[&#039;post_date_gmt&#039;],
					&#039;post_gmt_ts&#039;   =&gt; $post_gmt_ts,
				);
			}
		}
	}

	return $most_recent_post;
}

//
// Misc functions.
//

/**
 * Checks an array of MIME types against a list of allowed types.
 *
 * WordPress ships with a set of allowed upload filetypes,
 * which is defined in wp-includes/functions.php in
 * get_allowed_mime_types(). This function is used to filter
 * that list against the filetypes allowed provided by Multisite
 * Super Admins at wp-admin/network/settings.php.
 *
 * @since MU (3.0.0)
 *
 * @param array $mimes
 * @return array
 */
function check_upload_mimes( $mimes ) {
	$site_exts  = explode( &#039; &#039;, get_site_option( &#039;upload_filetypes&#039;, &#039;jpg jpeg png gif&#039; ) );
	$site_mimes = array();
	foreach ( $site_exts as $ext ) {
		foreach ( $mimes as $ext_pattern =&gt; $mime ) {
			if ( &#039;&#039; !== $ext &amp;&amp; str_contains( $ext_pattern, $ext ) ) {
				$site_mimes[ $ext_pattern ] = $mime;
			}
		}
	}
	return $site_mimes;
}

/**
 * Updates a blog&#039;s post count.
 *
 * WordPress MS stores a blog&#039;s post count as an option so as
 * to avoid extraneous COUNTs when a blog&#039;s details are fetched
 * with get_site(). This function is called when posts are published
 * or unpublished to make sure the count stays current.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $deprecated Not used.
 */
function update_posts_count( $deprecated = &#039;&#039; ) {
	global $wpdb;
	update_option( &#039;post_count&#039;, (int) $wpdb-&gt;get_var( &quot;SELECT COUNT(ID) FROM {$wpdb-&gt;posts} WHERE post_status = &#039;publish&#039; and post_type = &#039;post&#039;&quot; ), true );
}

/**
 * Logs the user email, IP, and registration date of a new site.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 Parameters now support input from the {@see &#039;wp_initialize_site&#039;} action.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param WP_Site|int $blog_id The new site&#039;s object or ID.
 * @param int|array   $user_id User ID, or array of arguments including &#039;user_id&#039;.
 */
function wpmu_log_new_registrations( $blog_id, $user_id ) {
	global $wpdb;

	if ( is_object( $blog_id ) ) {
		$blog_id = $blog_id-&gt;blog_id;
	}

	if ( is_array( $user_id ) ) {
		$user_id = ! empty( $user_id[&#039;user_id&#039;] ) ? $user_id[&#039;user_id&#039;] : 0;
	}

	$user = get_userdata( (int) $user_id );
	if ( $user ) {
		$wpdb-&gt;insert(
			$wpdb-&gt;registration_log,
			array(
				&#039;email&#039;           =&gt; $user-&gt;user_email,
				&#039;IP&#039;              =&gt; preg_replace( &#039;/[^0-9., ]/&#039;, &#039;&#039;, wp_unslash( $_SERVER[&#039;REMOTE_ADDR&#039;] ) ),
				&#039;blog_id&#039;         =&gt; $blog_id,
				&#039;date_registered&#039; =&gt; current_time( &#039;mysql&#039; ),
			)
		);
	}
}

/**
 * Ensures that the current site&#039;s domain is listed in the allowed redirect host list.
 *
 * @see wp_validate_redirect()
 * @since MU (3.0.0)
 *
 * @param array|string $deprecated Not used.
 * @return string[] {
 *     An array containing the current site&#039;s domain.
 *
 *     @type string $0 The current site&#039;s domain.
 * }
 */
function redirect_this_site( $deprecated = &#039;&#039; ) {
	return array( get_network()-&gt;domain );
}

/**
 * Checks whether an upload is too big.
 *
 * @since MU (3.0.0)
 *
 * @param array $upload An array of information about the newly-uploaded file.
 * @return string|array If the upload is under the size limit, $upload is returned. Otherwise returns an error message.
 */
function upload_is_file_too_big( $upload ) {
	if ( ! is_array( $upload ) || defined( &#039;WP_IMPORTING&#039; ) || get_site_option( &#039;upload_space_check_disabled&#039; ) ) {
		return $upload;
	}

	if ( strlen( $upload[&#039;bits&#039;] ) &gt; ( KB_IN_BYTES * get_site_option( &#039;fileupload_maxk&#039;, 1500 ) ) ) {
		/* translators: %s: Maximum allowed file size in kilobytes. */
		return sprintf( __( &#039;This file is too big. Files must be less than %s KB in size.&#039; ) . &#039;&lt;br /&gt;&#039;, get_site_option( &#039;fileupload_maxk&#039;, 1500 ) );
	}

	return $upload;
}

/**
 * Adds a nonce field to the signup page.
 *
 * @since MU (3.0.0)
 */
function signup_nonce_fields() {
	$id = mt_rand();
	echo &quot;&lt;input type=&#039;hidden&#039; name=&#039;signup_form_id&#039; value=&#039;{$id}&#039; /&gt;&quot;;
	wp_nonce_field( &#039;signup_form_&#039; . $id, &#039;_signup_form&#039;, false );
}

/**
 * Processes the signup nonce created in signup_nonce_fields().
 *
 * @since MU (3.0.0)
 *
 * @param array $result
 * @return array
 */
function signup_nonce_check( $result ) {
	if ( ! strpos( $_SERVER[&#039;PHP_SELF&#039;], &#039;wp-signup.php&#039; ) ) {
		return $result;
	}

	if ( ! wp_verify_nonce( $_POST[&#039;_signup_form&#039;], &#039;signup_form_&#039; . $_POST[&#039;signup_form_id&#039;] ) ) {
		$result[&#039;errors&#039;]-&gt;add( &#039;invalid_nonce&#039;, __( &#039;Unable to submit this form, please try again.&#039; ) );
	}

	return $result;
}

/**
 * Corrects 404 redirects when NOBLOGREDIRECT is defined.
 *
 * @since MU (3.0.0)
 */
function maybe_redirect_404() {
	if ( is_main_site() &amp;&amp; is_404() &amp;&amp; defined( &#039;NOBLOGREDIRECT&#039; ) ) {
		/**
		 * Filters the redirect URL for 404s on the main site.
		 *
		 * The filter is only evaluated if the NOBLOGREDIRECT constant is defined.
		 *
		 * @since 3.0.0
		 *
		 * @param string $no_blog_redirect The redirect URL defined in NOBLOGREDIRECT.
		 */
		$destination = apply_filters( &#039;blog_redirect_404&#039;, NOBLOGREDIRECT );

		if ( $destination ) {
			if ( &#039;%siteurl%&#039; === $destination ) {
				$destination = network_home_url();
			}

			wp_redirect( $destination );
			exit;
		}
	}
}

/**
 * Adds a new user to a blog by visiting /newbloguser/{key}/.
 *
 * This will only work when the user&#039;s details are saved as an option
 * keyed as &#039;new_user_{key}&#039;, where &#039;{key}&#039; is a hash generated for the user to be
 * added, as when a user is invited through the regular WP Add User interface.
 *
 * @since MU (3.0.0)
 */
function maybe_add_existing_user_to_blog() {
	if ( ! str_contains( $_SERVER[&#039;REQUEST_URI&#039;], &#039;/newbloguser/&#039; ) ) {
		return;
	}

	$parts = explode( &#039;/&#039;, $_SERVER[&#039;REQUEST_URI&#039;] );
	$key   = array_pop( $parts );

	if ( &#039;&#039; === $key ) {
		$key = array_pop( $parts );
	}

	$details = get_option( &#039;new_user_&#039; . $key );
	if ( ! empty( $details ) ) {
		delete_option( &#039;new_user_&#039; . $key );
	}

	if ( empty( $details ) || is_wp_error( add_existing_user_to_blog( $details ) ) ) {
		wp_die(
			sprintf(
				/* translators: %s: Home URL. */
				__( &#039;An error occurred adding you to this site. Go to the &lt;a href=&quot;%s&quot;&gt;homepage&lt;/a&gt;.&#039; ),
				home_url()
			)
		);
	}

	wp_die(
		sprintf(
			/* translators: 1: Home URL, 2: Admin URL. */
			__( &#039;You have been added to this site. Please visit the &lt;a href=&quot;%1$s&quot;&gt;homepage&lt;/a&gt; or &lt;a href=&quot;%2$s&quot;&gt;log in&lt;/a&gt; using your username and password.&#039; ),
			home_url(),
			admin_url()
		),
		__( &#039;WordPress &amp;rsaquo; Success&#039; ),
		array( &#039;response&#039; =&gt; 200 )
	);
}

/**
 * Adds a user to a blog based on details from maybe_add_existing_user_to_blog().
 *
 * @since MU (3.0.0)
 *
 * @param array|false $details {
 *     User details. Must at least contain values for the keys listed below.
 *
 *     @type int    $user_id The ID of the user being added to the current blog.
 *     @type string $role    The role to be assigned to the user.
 * }
 * @return true|WP_Error|void True on success or a WP_Error object if the user doesn&#039;t exist
 *                            or could not be added. Void if $details array was not provided.
 */
function add_existing_user_to_blog( $details = false ) {
	if ( is_array( $details ) ) {
		$blog_id = get_current_blog_id();
		$result  = add_user_to_blog( $blog_id, $details[&#039;user_id&#039;], $details[&#039;role&#039;] );

		/**
		 * Fires immediately after an existing user is added to a site.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param int           $user_id User ID.
		 * @param true|WP_Error $result  True on success or a WP_Error object if the user doesn&#039;t exist
		 *                               or could not be added.
		 */
		do_action( &#039;added_existing_user&#039;, $details[&#039;user_id&#039;], $result );

		return $result;
	}
}

/**
 * Adds a newly created user to the appropriate blog
 *
 * To add a user in general, use add_user_to_blog(). This function
 * is specifically hooked into the {@see &#039;wpmu_activate_user&#039;} action.
 *
 * @since MU (3.0.0)
 *
 * @see add_user_to_blog()
 *
 * @param int    $user_id  User ID.
 * @param string $password User password. Ignored.
 * @param array  $meta     Signup meta data.
 */
function add_new_user_to_blog(
	$user_id,
	#[\SensitiveParameter]
	$password,
	$meta
) {
	if ( ! empty( $meta[&#039;add_to_blog&#039;] ) ) {
		$blog_id = $meta[&#039;add_to_blog&#039;];
		$role    = $meta[&#039;new_role&#039;];
		remove_user_from_blog( $user_id, get_network()-&gt;site_id ); // Remove user from main blog.

		$result = add_user_to_blog( $blog_id, $user_id, $role );

		if ( ! is_wp_error( $result ) ) {
			update_user_meta( $user_id, &#039;primary_blog&#039;, $blog_id );
		}
	}
}

/**
 * Corrects From host on outgoing mail to match the site domain.
 *
 * @since MU (3.0.0)
 *
 * @param PHPMailer\PHPMailer\PHPMailer $phpmailer The PHPMailer instance (passed by reference).
 */
function fix_phpmailer_messageid( $phpmailer ) {
	$phpmailer-&gt;Hostname = get_network()-&gt;domain;
}

/**
 * Determines whether a user is marked as a spammer, based on user login.
 *
 * @since MU (3.0.0)
 *
 * @param string|WP_User $user Optional. Defaults to current user. WP_User object,
 *                             or user login name as a string.
 * @return bool
 */
function is_user_spammy( $user = null ) {
	if ( ! ( $user instanceof WP_User ) ) {
		if ( $user ) {
			$user = get_user_by( &#039;login&#039;, $user );
		} else {
			$user = wp_get_current_user();
		}
	}

	return $user &amp;&amp; isset( $user-&gt;spam ) &amp;&amp; &#039;1&#039; === $user-&gt;spam;
}

/**
 * Updates this blog&#039;s &#039;public&#039; setting in the global blogs table.
 *
 * Public blogs have a setting of 1, private blogs are 0.
 *
 * @since MU (3.0.0)
 *
 * @param int $old_value The old public value.
 * @param int $value     The new public value.
 */
function update_blog_public( $old_value, $value ) {
	update_blog_status( get_current_blog_id(), &#039;public&#039;, (int) $value );
}

/**
 * Determines whether users can self-register, based on Network settings.
 *
 * @since MU (3.0.0)
 *
 * @return bool
 */
function users_can_register_signup_filter() {
	$registration = get_site_option( &#039;registration&#039; );
	return ( &#039;all&#039; === $registration || &#039;user&#039; === $registration );
}

/**
 * Ensures that the welcome message is not empty. Currently unused.
 *
 * @since MU (3.0.0)
 *
 * @param string $text
 * @return string
 */
function welcome_user_msg_filter( $text ) {
	if ( ! $text ) {
		remove_filter( &#039;site_option_welcome_user_email&#039;, &#039;welcome_user_msg_filter&#039; );

		/* translators: Do not translate USERNAME, PASSWORD, LOGINLINK, SITE_NAME: those are placeholders. */
		$text = __(
			&#039;Howdy USERNAME,

Your new account is set up.

You can log in with the following information:
Username: USERNAME
Password: PASSWORD
LOGINLINK

Thanks!

--The Team @ SITE_NAME&#039;
		);
		update_site_option( &#039;welcome_user_email&#039;, $text );
	}
	return $text;
}

/**
 * Determines whether to force SSL on content.
 *
 * @since 2.8.5
 *
 * @param bool $force
 * @return bool True if forced, false if not forced.
 */
function force_ssl_content( $force = &#039;&#039; ) {
	static $forced_content = false;

	if ( ! $force ) {
		$old_forced     = $forced_content;
		$forced_content = $force;
		return $old_forced;
	}

	return $forced_content;
}

/**
 * Formats a URL to use https.
 *
 * Useful as a filter.
 *
 * @since 2.8.5
 *
 * @param string $url URL.
 * @return string URL with https as the scheme.
 */
function filter_SSL( $url ) {  // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid
	if ( ! is_string( $url ) ) {
		return get_bloginfo( &#039;url&#039; ); // Return home site URL with proper scheme.
	}

	if ( force_ssl_content() &amp;&amp; is_ssl() ) {
		$url = set_url_scheme( $url, &#039;https&#039; );
	}

	return $url;
}

/**
 * Schedules update of the network-wide counts for the current network.
 *
 * @since 3.1.0
 */
function wp_schedule_update_network_counts() {
	if ( ! is_main_site() ) {
		return;
	}

	if ( ! wp_next_scheduled( &#039;update_network_counts&#039; ) &amp;&amp; ! wp_installing() ) {
		wp_schedule_event( time(), &#039;twicedaily&#039;, &#039;update_network_counts&#039; );
	}
}

/**
 * Updates the network-wide counts for the current network.
 *
 * @since 3.1.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_counts( $network_id = null ) {
	wp_update_network_user_counts( $network_id );
	wp_update_network_site_counts( $network_id );
}

/**
 * Updates the count of sites for the current network.
 *
 * If enabled through the {@see &#039;enable_live_network_counts&#039;} filter, update the sites count
 * on a network when a site is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_site_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( &#039;sites&#039;, $network_id );

	/**
	 * Filters whether to update network site or user counts when a new site is created.
	 *
	 * @since 3.7.0
	 *
	 * @see wp_is_large_network()
	 *
	 * @param bool   $small_network Whether the network is considered small.
	 * @param string $context       Context. Either &#039;users&#039; or &#039;sites&#039;.
	 */
	if ( ! apply_filters( &#039;enable_live_network_counts&#039;, $is_small_network, &#039;sites&#039; ) ) {
		return;
	}

	wp_update_network_site_counts( $network_id );
}

/**
 * Updates the network-wide users count.
 *
 * If enabled through the {@see &#039;enable_live_network_counts&#039;} filter, update the users count
 * on a network when a user is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_user_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( &#039;users&#039;, $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	if ( ! apply_filters( &#039;enable_live_network_counts&#039;, $is_small_network, &#039;users&#039; ) ) {
		return;
	}

	wp_update_network_user_counts( $network_id );
}

/**
 * Updates the network-wide site count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_site_counts( $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	$count = get_sites(
		array(
			&#039;network_id&#039;             =&gt; $network_id,
			&#039;spam&#039;                   =&gt; 0,
			&#039;deleted&#039;                =&gt; 0,
			&#039;archived&#039;               =&gt; 0,
			&#039;count&#039;                  =&gt; true,
			&#039;update_site_meta_cache&#039; =&gt; false,
		)
	);

	update_network_option( $network_id, &#039;blog_count&#039;, $count );
}

/**
 * Updates the network-wide user count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 * @since 6.0.0 This function is now a wrapper for wp_update_user_counts().
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_user_counts( $network_id = null ) {
	wp_update_user_counts( $network_id );
}

/**
 * Returns the space used by the current site.
 *
 * @since 3.5.0
 *
 * @return int Used space in megabytes.
 */
function get_space_used() {
	/**
	 * Filters the amount of storage space used by the current site, in megabytes.
	 *
	 * @since 3.5.0
	 *
	 * @param int|false $space_used The amount of used space, in megabytes. Default false.
	 */
	$space_used = apply_filters( &#039;pre_get_space_used&#039;, false );

	if ( false === $space_used ) {
		$upload_dir = wp_upload_dir();
		$space_used = get_dirsize( $upload_dir[&#039;basedir&#039;] ) / MB_IN_BYTES;
	}

	return $space_used;
}

/**
 * Returns the upload quota for the current blog.
 *
 * @since MU (3.0.0)
 *
 * @return int Quota in megabytes.
 */
function get_space_allowed() {
	$space_allowed = get_option( &#039;blog_upload_space&#039; );

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = get_site_option( &#039;blog_upload_space&#039; );
	}

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = 100;
	}

	/**
	 * Filters the upload quota for the current site.
	 *
	 * @since 3.7.0
	 *
	 * @param int $space_allowed Upload quota in megabytes for the current blog.
	 */
	return apply_filters( &#039;get_space_allowed&#039;, $space_allowed );
}

/**
 * Determines if there is any upload space left in the current blog&#039;s quota.
 *
 * @since 3.0.0
 *
 * @return int of upload space available in bytes.
 */
function get_upload_space_available() {
	$allowed = get_space_allowed();
	if ( $allowed &lt; 0 ) {
		$allowed = 0;
	}
	$space_allowed = $allowed * MB_IN_BYTES;
	if ( get_site_option( &#039;upload_space_check_disabled&#039; ) ) {
		return $space_allowed;
	}

	$space_used = get_space_used() * MB_IN_BYTES;

	if ( ( $space_allowed - $space_used ) &lt;= 0 ) {
		return 0;
	}

	return $space_allowed - $space_used;
}

/**
 * Determines if there is any upload space left in the current blog&#039;s quota.
 *
 * @since 3.0.0
 * @return bool True if space is available, false otherwise.
 */
function is_upload_space_available() {
	if ( get_site_option( &#039;upload_space_check_disabled&#039; ) ) {
		return true;
	}

	return (bool) get_upload_space_available();
}

/**
 * Filters the maximum upload file size allowed, in bytes.
 *
 * @since 3.0.0
 *
 * @param int $size Upload size limit in bytes.
 * @return int Upload size limit in bytes.
 */
function upload_size_limit_filter( $size ) {
	$fileupload_maxk         = (int) get_site_option( &#039;fileupload_maxk&#039;, 1500 );
	$max_fileupload_in_bytes = KB_IN_BYTES * $fileupload_maxk;

	if ( get_site_option( &#039;upload_space_check_disabled&#039; ) ) {
		return min( $size, $max_fileupload_in_bytes );
	}

	return min( $size, $max_fileupload_in_bytes, get_upload_space_available() );
}

/**
 * Determines whether or not we have a large network.
 *
 * The default criteria for a large network is either more than 10,000 users or more than 10,000 sites.
 * Plugins can alter this criteria using the {@see &#039;wp_is_large_network&#039;} filter.
 *
 * @since 3.3.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param string   $using      &#039;sites&#039; or &#039;users&#039;. Default is &#039;sites&#039;.
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return bool True if the network meets the criteria for large. False otherwise.
 */
function wp_is_large_network( $using = &#039;sites&#039;, $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	if ( &#039;users&#039; === $using ) {
		$count = get_user_count( $network_id );

		$is_large_network = wp_is_large_user_count( $network_id );

		/**
		 * Filters whether the network is considered large.
		 *
		 * @since 3.3.0
		 * @since 4.8.0 The `$network_id` parameter has been added.
		 *
		 * @param bool   $is_large_network Whether the network has more than 10000 users or sites.
		 * @param string $component        The component to count. Accepts &#039;users&#039;, or &#039;sites&#039;.
		 * @param int    $count            The count of items for the component.
		 * @param int    $network_id       The ID of the network being checked.
		 */
		return apply_filters( &#039;wp_is_large_network&#039;, $is_large_network, &#039;users&#039;, $count, $network_id );
	}

	$count = get_blog_count( $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	return apply_filters( &#039;wp_is_large_network&#039;, $count &gt; 10000, &#039;sites&#039;, $count, $network_id );
}

/**
 * Retrieves a list of reserved site on a sub-directory Multisite installation.
 *
 * @since 4.4.0
 *
 * @return string[] Array of reserved names.
 */
function get_subdirectory_reserved_names() {
	$names = array(
		&#039;page&#039;,
		&#039;comments&#039;,
		&#039;blog&#039;,
		&#039;files&#039;,
		&#039;feed&#039;,
		&#039;wp-admin&#039;,
		&#039;wp-content&#039;,
		&#039;wp-includes&#039;,
		&#039;wp-json&#039;,
		&#039;embed&#039;,
	);

	/**
	 * Filters reserved site names on a sub-directory Multisite installation.
	 *
	 * @since 3.0.0
	 * @since 4.4.0 &#039;wp-admin&#039;, &#039;wp-content&#039;, &#039;wp-includes&#039;, &#039;wp-json&#039;, and &#039;embed&#039; were added
	 *              to the reserved names list.
	 *
	 * @param string[] $subdirectory_reserved_names Array of reserved names.
	 */
	return apply_filters( &#039;subdirectory_reserved_names&#039;, $names );
}

/**
 * Sends a confirmation request email when a change of network admin email address is attempted.
 *
 * The new network admin address will not become active until confirmed.
 *
 * @since 4.9.0
 *
 * @param string $old_value The old network admin email address.
 * @param string $value     The proposed new network admin email address.
 */
function update_network_option_new_admin_email( $old_value, $value ) {
	if ( get_site_option( &#039;admin_email&#039; ) === $value || ! is_email( $value ) ) {
		return;
	}

	$hash            = md5( $value . time() . mt_rand() );
	$new_admin_email = array(
		&#039;hash&#039;     =&gt; $hash,
		&#039;newemail&#039; =&gt; $value,
	);
	update_site_option( &#039;network_admin_hash&#039;, $new_admin_email );

	$switched_locale = switch_to_user_locale( get_current_user_id() );

	/* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_text = __(
		&#039;Howdy ###USERNAME###,

You recently requested to have the network admin email address on
your network changed.

If this is correct, please click on the following link to change it:
###ADMIN_URL###

You can safely ignore and delete this email if you do not want to
take this action.

This email has been sent to ###EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###&#039;
	);

	/**
	 * Filters the text of the email sent when a change of network admin email address is attempted.
	 *
	 * The following strings have a special meaning and will get replaced dynamically:
	 * ###USERNAME###  The current user&#039;s username.
	 * ###ADMIN_URL### The link to click on to confirm the email change.
	 * ###EMAIL###     The proposed new network admin email address.
	 * ###SITENAME###  The name of the network.
	 * ###SITEURL###   The URL to the network.
	 *
	 * @since 4.9.0
	 *
	 * @param string $email_text      Text in the email.
	 * @param array  $new_admin_email {
	 *     Data relating to the new network admin email address.
	 *
	 *     @type string $hash     The secure hash used in the confirmation link URL.
	 *     @type string $newemail The proposed new network admin email address.
	 * }
	 */
	$content = apply_filters( &#039;new_network_admin_email_content&#039;, $email_text, $new_admin_email );

	$current_user = wp_get_current_user();
	$content      = str_replace( &#039;###USERNAME###&#039;, $current_user-&gt;user_login, $content );
	$content      = str_replace( &#039;###ADMIN_URL###&#039;, esc_url( network_admin_url( &#039;settings.php?network_admin_hash=&#039; . $hash ) ), $content );
	$content      = str_replace( &#039;###EMAIL###&#039;, $value, $content );
	$content      = str_replace( &#039;###SITENAME###&#039;, wp_specialchars_decode( get_site_option( &#039;site_name&#039; ), ENT_QUOTES ), $content );
	$content      = str_replace( &#039;###SITEURL###&#039;, network_home_url(), $content );

	wp_mail(
		$value,
		sprintf(
			/* translators: Email change notification email subject. %s: Network title. */
			__( &#039;[%s] Network Admin Email Change Request&#039; ),
			wp_specialchars_decode( get_site_option( &#039;site_name&#039; ), ENT_QUOTES )
		),
		$content
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}
}

/**
 * Sends an email to the old network admin email address when the network admin email address changes.
 *
 * @since 4.9.0
 *
 * @param string $option_name The relevant database option name.
 * @param string $new_email   The new network admin email address.
 * @param string $old_email   The old network admin email address.
 * @param int    $network_id  ID of the network.
 */
function wp_network_admin_email_change_notification( $option_name, $new_email, $old_email, $network_id ) {
	$send = true;

	// Don&#039;t send the notification to the default &#039;admin_email&#039; value.
	if ( &#039;you@example.com&#039; === $old_email ) {
		$send = false;
	}

	/**
	 * Filters whether to send the network admin email change notification email.
	 *
	 * @since 4.9.0
	 *
	 * @param bool   $send       Whether to send the email notification.
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$send = apply_filters( &#039;send_network_admin_email_change_email&#039;, $send, $old_email, $new_email, $network_id );

	if ( ! $send ) {
		return;
	}

	/* translators: Do not translate OLD_EMAIL, NEW_EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_change_text = __(
		&#039;Hi,

This notice confirms that the network admin email address was changed on ###SITENAME###.

The new network admin email address is ###NEW_EMAIL###.

This email has been sent to ###OLD_EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###&#039;
	);

	$email_change_email = array(
		&#039;to&#039;      =&gt; $old_email,
		/* translators: Network admin email change notification email subject. %s: Network title. */
		&#039;subject&#039; =&gt; __( &#039;[%s] Network Admin Email Changed&#039; ),
		&#039;message&#039; =&gt; $email_change_text,
		&#039;headers&#039; =&gt; &#039;&#039;,
	);
	// Get network name.
	$network_name = wp_specialchars_decode( get_site_option( &#039;site_name&#039; ), ENT_QUOTES );

	/**
	 * Filters the contents of the email notification sent when the network admin email address is changed.
	 *
	 * @since 4.9.0
	 *
	 * @param array $email_change_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The intended recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *         The following strings have a special meaning and will get replaced dynamically:
	 *         - ###OLD_EMAIL### The old network admin email address.
	 *         - ###NEW_EMAIL### The new network admin email address.
	 *         - ###SITENAME###  The name of the network.
	 *         - ###SITEURL###   The URL to the site.
	 *     @type string $headers Headers.
	 * }
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$email_change_email = apply_filters( &#039;network_admin_email_change_email&#039;, $email_change_email, $old_email, $new_email, $network_id );

	$email_change_email[&#039;message&#039;] = str_replace( &#039;###OLD_EMAIL###&#039;, $old_email, $email_change_email[&#039;message&#039;] );
	$email_change_email[&#039;message&#039;] = str_replace( &#039;###NEW_EMAIL###&#039;, $new_email, $email_change_email[&#039;message&#039;] );
	$email_change_email[&#039;message&#039;] = str_replace( &#039;###SITENAME###&#039;, $network_name, $email_change_email[&#039;message&#039;] );
	$email_change_email[&#039;message&#039;] = str_replace( &#039;###SITEURL###&#039;, home_url(), $email_change_email[&#039;message&#039;] );

	wp_mail(
		$email_change_email[&#039;to&#039;],
		sprintf(
			$email_change_email[&#039;subject&#039;],
			$network_name
		),
		$email_change_email[&#039;message&#039;],
		$email_change_email[&#039;headers&#039;]
	);
}
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