wp/wp-includes/user.php
changeset 7 cf61fcea0001
parent 5 5e2f62d02dcd
child 9 177826044cd9
--- a/wp/wp-includes/user.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/user.php	Mon Oct 14 17:39:30 2019 +0200
@@ -1,13 +1,13 @@
 <?php
 /**
- * WordPress User API
+ * Core User API
  *
  * @package WordPress
  * @subpackage Users
  */
 
 /**
- * Authenticate user with remember capability.
+ * Authenticates and logs a user in with 'remember' capability.
  *
  * The credentials is an array that has 'user_login', 'user_password', and
  * 'remember' indices. If the credentials is not given, then the log in form
@@ -17,14 +17,23 @@
  * set for a longer period depending on if the 'remember' credential is set to
  * true.
  *
+ * Note: wp_signon() doesn't handle setting the current user. This means that if the
+ * function is called before the {@see 'init'} hook is fired, is_user_logged_in() will
+ * evaluate as false until that point. If is_user_logged_in() is needed in conjunction
+ * with wp_signon(), wp_set_current_user() should be called explicitly.
+ *
  * @since 2.5.0
  *
+ * @global string $auth_secure_cookie
+ *
  * @param array       $credentials   Optional. User info in order to sign on.
  * @param string|bool $secure_cookie Optional. Whether to use secure cookie.
  * @return WP_User|WP_Error WP_User on success, WP_Error on failure.
  */
 function wp_signon( $credentials = array(), $secure_cookie = '' ) {
 	if ( empty($credentials) ) {
+		$credentials = array(); // Back-compat for plugins passing an empty string.
+
 		if ( ! empty($_POST['log']) )
 			$credentials['user_login'] = $_POST['log'];
 		if ( ! empty($_POST['pwd']) )
@@ -48,8 +57,8 @@
 	 *
 	 * @todo Decide whether to deprecate the wp_authenticate action.
 	 *
-	 * @param string $user_login    Username, passed by reference.
-	 * @param string $user_password User password, passed by reference.
+	 * @param string $user_login    Username (passed by reference).
+	 * @param string $user_password User password (passed by reference).
 	 */
 	do_action_ref_array( 'wp_authenticate', array( &$credentials['user_login'], &$credentials['user_password'] ) );
 
@@ -57,7 +66,7 @@
 		$secure_cookie = is_ssl();
 
 	/**
-	 * Filter whether to use a secure sign-on cookie.
+	 * Filters whether to use a secure sign-on cookie.
 	 *
 	 * @since 3.1.0
 	 *
@@ -102,7 +111,7 @@
 }
 
 /**
- * Authenticate the user using the username and password.
+ * Authenticate a user, confirming the username and password are valid.
  *
  * @since 2.8.0
  *
@@ -133,11 +142,17 @@
 
 	$user = get_user_by('login', $username);
 
-	if ( !$user )
-		return new WP_Error( 'invalid_username', sprintf( __( '<strong>ERROR</strong>: Invalid username. <a href="%s">Lost your password?</a>' ), wp_lostpassword_url() ) );
+	if ( !$user ) {
+		return new WP_Error( 'invalid_username',
+			__( '<strong>ERROR</strong>: Invalid username.' ) .
+			' <a href="' . wp_lostpassword_url() . '">' .
+			__( 'Lost your password?' ) .
+			'</a>'
+		);
+	}
 
 	/**
-	 * Filter whether the given user can be authenticated with the provided $password.
+	 * Filters whether the given user can be authenticated with the provided $password.
 	 *
 	 * @since 2.5.0
 	 *
@@ -149,9 +164,90 @@
 	if ( is_wp_error($user) )
 		return $user;
 
-	if ( !wp_check_password($password, $user->user_pass, $user->ID) )
-		return new WP_Error( 'incorrect_password', sprintf( __( '<strong>ERROR</strong>: The password you entered for the username <strong>%1$s</strong> is incorrect. <a href="%2$s">Lost your password?</a>' ),
-		$username, wp_lostpassword_url() ) );
+	if ( ! wp_check_password( $password, $user->user_pass, $user->ID ) ) {
+		return new WP_Error( 'incorrect_password',
+			sprintf(
+				/* translators: %s: user name */
+				__( '<strong>ERROR</strong>: The password you entered for the username %s is incorrect.' ),
+				'<strong>' . $username . '</strong>'
+			) .
+			' <a href="' . wp_lostpassword_url() . '">' .
+			__( 'Lost your password?' ) .
+			'</a>'
+		);
+	}
+
+	return $user;
+}
+
+/**
+ * Authenticates a user using the email and password.
+ *
+ * @since 4.5.0
+ *
+ * @param WP_User|WP_Error|null $user     WP_User or WP_Error object if a previous
+ *                                        callback failed authentication.
+ * @param string                $email    Email address for authentication.
+ * @param string                $password Password for authentication.
+ * @return WP_User|WP_Error WP_User on success, WP_Error on failure.
+ */
+function wp_authenticate_email_password( $user, $email, $password ) {
+	if ( $user instanceof WP_User ) {
+		return $user;
+	}
+
+	if ( empty( $email ) || empty( $password ) ) {
+		if ( is_wp_error( $user ) ) {
+			return $user;
+		}
+
+		$error = new WP_Error();
+
+		if ( empty( $email ) ) {
+			$error->add( 'empty_username', __( '<strong>ERROR</strong>: The email field is empty.' ) ); // Uses 'empty_username' for back-compat with wp_signon()
+		}
+
+		if ( empty( $password ) ) {
+			$error->add( 'empty_password', __( '<strong>ERROR</strong>: The password field is empty.' ) );
+		}
+
+		return $error;
+	}
+
+	if ( ! is_email( $email ) ) {
+		return $user;
+	}
+
+	$user = get_user_by( 'email', $email );
+
+	if ( ! $user ) {
+		return new WP_Error( 'invalid_email',
+			__( '<strong>ERROR</strong>: Invalid email address.' ) .
+			' <a href="' . wp_lostpassword_url() . '">' .
+			__( 'Lost your password?' ) .
+			'</a>'
+		);
+	}
+
+	/** This filter is documented in wp-includes/user.php */
+	$user = apply_filters( 'wp_authenticate_user', $user, $password );
+
+	if ( is_wp_error( $user ) ) {
+		return $user;
+	}
+
+	if ( ! wp_check_password( $password, $user->user_pass, $user->ID ) ) {
+		return new WP_Error( 'incorrect_password',
+			sprintf(
+				/* translators: %s: email address */
+				__( '<strong>ERROR</strong>: The password you entered for the email address %s is incorrect.' ),
+				'<strong>' . $email . '</strong>'
+			) .
+			' <a href="' . wp_lostpassword_url() . '">' .
+			__( 'Lost your password?' ) .
+			'</a>'
+		);
+	}
 
 	return $user;
 }
@@ -161,6 +257,8 @@
  *
  * @since 2.8.0
  *
+ * @global string $auth_secure_cookie
+ *
  * @param WP_User|WP_Error|null $user     WP_User or WP_Error object from a previous callback. Default null.
  * @param string                $username Username. If not empty, cancels the cookie authentication.
  * @param string                $password Password. If not empty, cancels the cookie authentication.
@@ -204,14 +302,14 @@
 function wp_authenticate_spam_check( $user ) {
 	if ( $user instanceof WP_User && is_multisite() ) {
 		/**
-		 * Filter whether the user has been marked as a spammer.
+		 * Filters whether the user has been marked as a spammer.
 		 *
 		 * @since 3.7.0
 		 *
 		 * @param bool    $spammed Whether the user is considered a spammer.
 		 * @param WP_User $user    User to check against.
 		 */
-		$spammed = apply_filters( 'check_is_user_spammed', is_user_spammy(), $user );
+		$spammed = apply_filters( 'check_is_user_spammed', is_user_spammy( $user ), $user );
 
 		if ( $spammed )
 			return new WP_Error( 'spammer_account', __( '<strong>ERROR</strong>: Your account has been marked as a spammer.' ) );
@@ -220,19 +318,19 @@
 }
 
 /**
- * Validate the logged-in cookie.
+ * Validates the logged-in cookie.
  *
  * Checks the logged-in cookie if the previous auth cookie could not be
  * validated and parsed.
  *
- * This is a callback for the determine_current_user filter, rather than API.
+ * This is a callback for the {@see 'determine_current_user'} filter, rather than API.
  *
  * @since 3.9.0
  *
  * @param int|bool $user_id The user ID (or false) as received from the
  *                       determine_current_user filter.
- * @return int|bool User ID if validated, false otherwise. If a user ID from
- *                  an earlier filter callback is received, that value is returned.
+ * @return int|false User ID if validated, false otherwise. If a user ID from
+ *                   an earlier filter callback is received, that value is returned.
  */
 function wp_validate_logged_in_cookie( $user_id ) {
 	if ( $user_id ) {
@@ -251,31 +349,36 @@
  *
  * @since 3.0.0
  * @since 4.1.0 Added `$post_type` argument.
+ * @since 4.3.0 Added `$public_only` argument. Added the ability to pass an array
+ *              of post types to `$post_type`.
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
- * @param int    $userid    User ID.
- * @param string $post_type Optional. Post type to count the number of posts for. Default 'post'.
- * @return int Number of posts the user has written in this post type.
+ * @param int          $userid      User ID.
+ * @param array|string $post_type   Optional. Single post type or array of post types to count the number of posts for. Default 'post'.
+ * @param bool         $public_only Optional. Whether to only return counts for public posts. Default false.
+ * @return string Number of posts the user has written in this post type.
  */
-function count_user_posts( $userid, $post_type = 'post' ) {
+function count_user_posts( $userid, $post_type = 'post', $public_only = false ) {
 	global $wpdb;
 
-	$where = get_posts_by_author_sql( $post_type, true, $userid );
+	$where = get_posts_by_author_sql( $post_type, true, $userid, $public_only );
 
 	$count = $wpdb->get_var( "SELECT COUNT(*) FROM $wpdb->posts $where" );
 
 	/**
-	 * Filter the number of posts a user has written.
+	 * Filters the number of posts a user has written.
 	 *
 	 * @since 2.7.0
 	 * @since 4.1.0 Added `$post_type` argument.
+	 * @since 4.3.1 Added `$public_only` argument.
 	 *
-	 * @param int    $count     The user's post count.
-	 * @param int    $userid    User ID.
-	 * @param string $post_type Post type to count the number of posts for.
+	 * @param int          $count       The user's post count.
+	 * @param int          $userid      User ID.
+	 * @param string|array $post_type   Single post type or array of post types to count the number of posts for.
+	 * @param bool         $public_only Whether to limit counted posts to public posts.
 	 */
-	return apply_filters( 'get_usernumposts', $count, $userid, $post_type );
+	return apply_filters( 'get_usernumposts', $count, $userid, $post_type, $public_only );
 }
 
 /**
@@ -283,9 +386,11 @@
  *
  * @since 3.0.0
  *
- * @param array $users Array of user IDs.
- * @param string $post_type Optional. Post type to check. Defaults to post.
- * @param bool $public_only Optional. Only return counts for public posts.  Defaults to false.
+ * @global wpdb $wpdb WordPress database abstraction object.
+ *
+ * @param array        $users       Array of user IDs.
+ * @param string|array $post_type   Optional. Single post type or array of post types to check. Defaults to 'post'.
+ * @param bool         $public_only Optional. Only return counts for public posts.  Defaults to false.
  * @return array Amount of posts each user has written.
  */
 function count_many_users_posts( $users, $post_type = 'post', $public_only = false ) {
@@ -318,9 +423,9 @@
 /**
  * Get the current user's ID
  *
- * @since MU
+ * @since MU (3.0.0)
  *
- * @return int The current user's ID
+ * @return int The current user's ID, or 0 if no user is logged in.
  */
 function get_current_user_id() {
 	if ( ! function_exists( 'wp_get_current_user' ) )
@@ -341,7 +446,7 @@
  *
  * @since 2.0.0
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param string $option     User option name.
  * @param int    $user       Optional. User ID.
@@ -352,7 +457,7 @@
 	global $wpdb;
 
 	if ( !empty( $deprecated ) )
-		_deprecated_argument( __FUNCTION__, '3.0' );
+		_deprecated_argument( __FUNCTION__, '3.0.0' );
 
 	if ( empty( $user ) )
 		$user = get_current_user_id();
@@ -369,7 +474,7 @@
 		$result = false;
 
 	/**
-	 * Filter a specific user option value.
+	 * Filters a specific user option value.
 	 *
 	 * The dynamic portion of the hook name, `$option`, refers to the user option name.
 	 *
@@ -393,7 +498,7 @@
  *
  * @since 2.0.0
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param int    $user_id     User ID.
  * @param string $option_name User option name.
@@ -421,7 +526,7 @@
  *
  * @since 3.0.0
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param int    $user_id     User ID
  * @param string $option_name User option name.
@@ -438,673 +543,13 @@
 }
 
 /**
- * WordPress User Query class.
- *
- * @since 3.1.0
- *
- * @see WP_User_Query::prepare_query() for information on accepted arguments.
- */
-class WP_User_Query {
-
-	/**
-	 * Query vars, after parsing
-	 *
-	 * @since 3.5.0
-	 * @access public
-	 * @var array
-	 */
-	public $query_vars = array();
-
-	/**
-	 * List of found user ids
-	 *
-	 * @since 3.1.0
-	 * @access private
-	 * @var array
-	 */
-	private $results;
-
-	/**
-	 * Total number of found users for the current query
-	 *
-	 * @since 3.1.0
-	 * @access private
-	 * @var int
-	 */
-	private $total_users = 0;
-
-	/**
-	 * Metadata query container.
-	 *
-	 * @since 4.2.0
-	 * @access public
-	 * @var object WP_Meta_Query
-	 */
-	public $meta_query = false;
-
-	private $compat_fields = array( 'results', 'total_users' );
-
-	// SQL clauses
-	public $query_fields;
-	public $query_from;
-	public $query_where;
-	public $query_orderby;
-	public $query_limit;
-
-	/**
-	 * PHP5 constructor.
-	 *
-	 * @since 3.1.0
-	 *
-	 * @param null|string|array $args Optional. The query variables.
-	 */
-	public function __construct( $query = null ) {
-		if ( ! empty( $query ) ) {
-			$this->prepare_query( $query );
-			$this->query();
-		}
-	}
-
-	/**
-	 * Prepare the query variables.
-	 *
-	 * @since 3.1.0
-	 * @since 4.2.0 Added 'meta_value_num' support for `$orderby` parameter. Added multi-dimensional array syntax
-	 *              for `$orderby` parameter.
-	 * @access public
-	 *
-	 * @param string|array $query {
-	 *     Optional. Array or string of Query parameters.
-	 *
-	 *     @type int          $blog_id         The site ID. Default is the global blog id.
-	 *     @type string       $role            Role name. Default empty.
-	 *     @type string       $meta_key        User meta key. Default empty.
-	 *     @type string       $meta_value      User meta value. Default empty.
-	 *     @type string       $meta_compare    Comparison operator to test the `$meta_value`. Accepts '=', '!=',
-	 *                                         '>', '>=', '<', '<=', 'LIKE', 'NOT LIKE', 'IN', 'NOT IN', 'BETWEEN',
-	 *                                         'NOT BETWEEN', 'EXISTS', 'NOT EXISTS', 'REGEXP', 'NOT REGEXP',
-	 *                                         or 'RLIKE'. Default '='.
-	 *     @type array        $include         An array of user IDs to include. Default empty array.
-	 *     @type array        $exclude         An array of user IDs to exclude. Default empty array.
-	 *     @type string       $search          Search keyword. Searches for possible string matches on columns.
-	 *                                         When `$search_columns` is left empty, it tries to determine which
-	 *                                         column to search in based on search string. Default empty.
-	 *     @type array        $search_columns  Array of column names to be searched. Accepts 'ID', 'login',
-	 *                                         'nicename', 'email', 'url'. Default empty array.
-	 *     @type string|array $orderby         Field(s) to sort the retrieved users by. May be a single value,
-	 *                                         an array of values, or a multi-dimensional array with fields as keys
-	 *                                         and orders ('ASC' or 'DESC') as values. Accepted values are'ID',
-	 *                                         'display_name' (or 'name'), 'user_login' (or 'login'),
-	 *                                         'user_nicename' (or 'nicename'), 'user_email' (or 'email'),
-	 *                                         'user_url' (or 'url'), 'user_registered' (or 'registered'),
-	 *                                         'post_count', 'meta_value', 'meta_value_num', the value of
-	 *                                         `$meta_key`, or an array key of `$meta_query`. To use 'meta_value'
-	 *                                         or 'meta_value_num', `$meta_key` must be also be defined.
-	 *                                         Default 'user_login'.
-	 *     @type string       $order           Designates ascending or descending order of users. Order values
-	 *                                         passed as part of an `$orderby` array take precedence over this
-	 *                                         parameter. Accepts 'ASC', 'DESC'. Default 'ASC'.
-	 *     @type int          $offset          Number of users to offset in retrieved results. Can be used in
-	 *                                         conjunction with pagination. Default 0.
-	 *     @type int          $number          Number of users to limit the query for. Can be used in conjunction
-	 *                                         with pagination. Value -1 (all) is not supported.
-	 *                                         Default empty (all users).
-	 *     @type bool         $count_total     Whether to count the total number of users found. If pagination is not
-	 *                                         needed, setting this to false can improve performance. Default true.
-	 *     @type string|array $fields          Which fields to return. Single or all fields (string), or array
-	 *                                         of fields. Accepts 'ID', 'display_name', 'login', 'nicename', 'email',
-	 *                                         'url', 'registered'. Use 'all' for all fields and 'all_with_meta' to
-	 *                                         include meta fields. Default 'all'.
-	 *     @type string       $who             Type of users to query. Accepts 'authors'. Default empty (all users).
-	 * }
-	 */
-	public function prepare_query( $query = array() ) {
-		global $wpdb;
-
-		if ( empty( $this->query_vars ) || ! empty( $query ) ) {
-			$this->query_limit = null;
-			$this->query_vars = wp_parse_args( $query, array(
-				'blog_id' => $GLOBALS['blog_id'],
-				'role' => '',
-				'meta_key' => '',
-				'meta_value' => '',
-				'meta_compare' => '',
-				'include' => array(),
-				'exclude' => array(),
-				'search' => '',
-				'search_columns' => array(),
-				'orderby' => 'login',
-				'order' => 'ASC',
-				'offset' => '',
-				'number' => '',
-				'count_total' => true,
-				'fields' => 'all',
-				'who' => ''
-			) );
-		}
-
-		/**
-		 * Fires before the WP_User_Query has been parsed.
-		 *
-		 * The passed WP_User_Query object contains the query variables, not
-		 * yet passed into SQL.
-		 *
-		 * @since 4.0.0
-		 *
-		 * @param WP_User_Query $this The current WP_User_Query instance,
-		 *                            passed by reference.
-		 */
-		do_action( 'pre_get_users', $this );
-
-		$qv =& $this->query_vars;
-
-		if ( is_array( $qv['fields'] ) ) {
-			$qv['fields'] = array_unique( $qv['fields'] );
-
-			$this->query_fields = array();
-			foreach ( $qv['fields'] as $field ) {
-				$field = 'ID' === $field ? 'ID' : sanitize_key( $field );
-				$this->query_fields[] = "$wpdb->users.$field";
-			}
-			$this->query_fields = implode( ',', $this->query_fields );
-		} elseif ( 'all' == $qv['fields'] ) {
-			$this->query_fields = "$wpdb->users.*";
-		} else {
-			$this->query_fields = "$wpdb->users.ID";
-		}
-
-		if ( isset( $qv['count_total'] ) && $qv['count_total'] )
-			$this->query_fields = 'SQL_CALC_FOUND_ROWS ' . $this->query_fields;
-
-		$this->query_from = "FROM $wpdb->users";
-		$this->query_where = "WHERE 1=1";
-
-		// Parse and sanitize 'include', for use by 'orderby' as well as 'include' below.
-		if ( ! empty( $qv['include'] ) ) {
-			$include = wp_parse_id_list( $qv['include'] );
-		} else {
-			$include = false;
-		}
-
-		$blog_id = 0;
-		if ( isset( $qv['blog_id'] ) ) {
-			$blog_id = absint( $qv['blog_id'] );
-		}
-
-		if ( isset( $qv['who'] ) && 'authors' == $qv['who'] && $blog_id ) {
-			$qv['meta_key'] = $wpdb->get_blog_prefix( $blog_id ) . 'user_level';
-			$qv['meta_value'] = 0;
-			$qv['meta_compare'] = '!=';
-			$qv['blog_id'] = $blog_id = 0; // Prevent extra meta query
-		}
-
-		// Meta query.
-		$this->meta_query = new WP_Meta_Query();
-		$this->meta_query->parse_query_vars( $qv );
-
-		$role = '';
-		if ( isset( $qv['role'] ) ) {
-			$role = trim( $qv['role'] );
-		}
-
-		if ( $blog_id && ( $role || is_multisite() ) ) {
-			$cap_meta_query = array();
-			$cap_meta_query['key'] = $wpdb->get_blog_prefix( $blog_id ) . 'capabilities';
-
-			if ( $role ) {
-				$cap_meta_query['value'] = '"' . $role . '"';
-				$cap_meta_query['compare'] = 'like';
-			}
-
-			if ( empty( $this->meta_query->queries ) ) {
-				$this->meta_query->queries = array( $cap_meta_query );
-			} elseif ( ! in_array( $cap_meta_query, $this->meta_query->queries, true ) ) {
-				// Append the cap query to the original queries and reparse the query.
-				$this->meta_query->queries = array(
-					'relation' => 'AND',
-					array( $this->meta_query->queries, $cap_meta_query ),
-				);
-			}
-
-			$this->meta_query->parse_query_vars( $this->meta_query->queries );
-		}
-
-		if ( ! empty( $this->meta_query->queries ) ) {
-			$clauses = $this->meta_query->get_sql( 'user', $wpdb->users, 'ID', $this );
-			$this->query_from .= $clauses['join'];
-			$this->query_where .= $clauses['where'];
-
-			if ( 'OR' == $this->meta_query->relation ) {
-				$this->query_fields = 'DISTINCT ' . $this->query_fields;
-			}
-		}
-
-		// sorting
-		$qv['order'] = isset( $qv['order'] ) ? strtoupper( $qv['order'] ) : '';
-		$order = $this->parse_order( $qv['order'] );
-
-		if ( empty( $qv['orderby'] ) ) {
-			// Default order is by 'user_login'.
-			$ordersby = array( 'user_login' => $order );
-		} else if ( is_array( $qv['orderby'] ) ) {
-			$ordersby = $qv['orderby'];
-		} else {
-			// 'orderby' values may be a comma- or space-separated list.
-			$ordersby = preg_split( '/[,\s]+/', $qv['orderby'] );
-		}
-
-		$orderby_array = array();
-		foreach ( $ordersby as $_key => $_value ) {
-			if ( ! $_value ) {
-				continue;
-			}
-
-			if ( is_int( $_key ) ) {
-				// Integer key means this is a flat array of 'orderby' fields.
-				$_orderby = $_value;
-				$_order = $order;
-			} else {
-				// Non-integer key means this the key is the field and the value is ASC/DESC.
-				$_orderby = $_key;
-				$_order = $_value;
-			}
-
-			$parsed = $this->parse_orderby( $_orderby );
-
-			if ( ! $parsed ) {
-				continue;
-			}
-
-			$orderby_array[] = $parsed . ' ' . $this->parse_order( $_order );
-		}
-
-		// If no valid clauses were found, order by user_login.
-		if ( empty( $orderby_array ) ) {
-			$orderby_array[] = "user_login $order";
-		}
-
-		$this->query_orderby = 'ORDER BY ' . implode( ', ', $orderby_array );
-
-		// limit
-		if ( isset( $qv['number'] ) && $qv['number'] ) {
-			if ( $qv['offset'] )
-				$this->query_limit = $wpdb->prepare("LIMIT %d, %d", $qv['offset'], $qv['number']);
-			else
-				$this->query_limit = $wpdb->prepare("LIMIT %d", $qv['number']);
-		}
-
-		$search = '';
-		if ( isset( $qv['search'] ) )
-			$search = trim( $qv['search'] );
-
-		if ( $search ) {
-			$leading_wild = ( ltrim($search, '*') != $search );
-			$trailing_wild = ( rtrim($search, '*') != $search );
-			if ( $leading_wild && $trailing_wild )
-				$wild = 'both';
-			elseif ( $leading_wild )
-				$wild = 'leading';
-			elseif ( $trailing_wild )
-				$wild = 'trailing';
-			else
-				$wild = false;
-			if ( $wild )
-				$search = trim($search, '*');
-
-			$search_columns = array();
-			if ( $qv['search_columns'] )
-				$search_columns = array_intersect( $qv['search_columns'], array( 'ID', 'user_login', 'user_email', 'user_url', 'user_nicename' ) );
-			if ( ! $search_columns ) {
-				if ( false !== strpos( $search, '@') )
-					$search_columns = array('user_email');
-				elseif ( is_numeric($search) )
-					$search_columns = array('user_login', 'ID');
-				elseif ( preg_match('|^https?://|', $search) && ! ( is_multisite() && wp_is_large_network( 'users' ) ) )
-					$search_columns = array('user_url');
-				else
-					$search_columns = array('user_login', 'user_nicename');
-			}
-
-			/**
-			 * Filter the columns to search in a WP_User_Query search.
-			 *
-			 * The default columns depend on the search term, and include 'user_email',
-			 * 'user_login', 'ID', 'user_url', and 'user_nicename'.
-			 *
-			 * @since 3.6.0
-			 *
-			 * @param array         $search_columns Array of column names to be searched.
-			 * @param string        $search         Text being searched.
-			 * @param WP_User_Query $this           The current WP_User_Query instance.
-			 */
-			$search_columns = apply_filters( 'user_search_columns', $search_columns, $search, $this );
-
-			$this->query_where .= $this->get_search_sql( $search, $search_columns, $wild );
-		}
-
-		if ( ! empty( $include ) ) {
-			// Sanitized earlier.
-			$ids = implode( ',', $include );
-			$this->query_where .= " AND $wpdb->users.ID IN ($ids)";
-		} elseif ( ! empty( $qv['exclude'] ) ) {
-			$ids = implode( ',', wp_parse_id_list( $qv['exclude'] ) );
-			$this->query_where .= " AND $wpdb->users.ID NOT IN ($ids)";
-		}
-
-		// Date queries are allowed for the user_registered field.
-		if ( ! empty( $qv['date_query'] ) && is_array( $qv['date_query'] ) ) {
-			$date_query = new WP_Date_Query( $qv['date_query'], 'user_registered' );
-			$this->query_where .= $date_query->get_sql();
-		}
-
-		/**
-		 * Fires after the WP_User_Query has been parsed, and before
-		 * the query is executed.
-		 *
-		 * The passed WP_User_Query object contains SQL parts formed
-		 * from parsing the given query.
-		 *
-		 * @since 3.1.0
-		 *
-		 * @param WP_User_Query $this The current WP_User_Query instance,
-		 *                            passed by reference.
-		 */
-		do_action_ref_array( 'pre_user_query', array( &$this ) );
-	}
-
-	/**
-	 * Execute the query, with the current variables.
-	 *
-	 * @since 3.1.0
-	 *
-	 * @global wpdb $wpdb WordPress database object for queries.
-	 */
-	public function query() {
-		global $wpdb;
-
-		$qv =& $this->query_vars;
-
-		$query = "SELECT $this->query_fields $this->query_from $this->query_where $this->query_orderby $this->query_limit";
-
-		if ( is_array( $qv['fields'] ) || 'all' == $qv['fields'] ) {
-			$this->results = $wpdb->get_results( $query );
-		} else {
-			$this->results = $wpdb->get_col( $query );
-		}
-
-		/**
-		 * Filter SELECT FOUND_ROWS() query for the current WP_User_Query instance.
-		 *
-		 * @since 3.2.0
-		 *
-		 * @global wpdb $wpdb WordPress database abstraction object.
-		 *
-		 * @param string $sql The SELECT FOUND_ROWS() query for the current WP_User_Query.
-		 */
-		if ( isset( $qv['count_total'] ) && $qv['count_total'] )
-			$this->total_users = $wpdb->get_var( apply_filters( 'found_users_query', 'SELECT FOUND_ROWS()' ) );
-
-		if ( !$this->results )
-			return;
-
-		if ( 'all_with_meta' == $qv['fields'] ) {
-			cache_users( $this->results );
-
-			$r = array();
-			foreach ( $this->results as $userid )
-				$r[ $userid ] = new WP_User( $userid, '', $qv['blog_id'] );
-
-			$this->results = $r;
-		} elseif ( 'all' == $qv['fields'] ) {
-			foreach ( $this->results as $key => $user ) {
-				$this->results[ $key ] = new WP_User( $user, '', $qv['blog_id'] );
-			}
-		}
-	}
-
-	/**
-	 * Retrieve query variable.
-	 *
-	 * @since 3.5.0
-	 * @access public
-	 *
-	 * @param string $query_var Query variable key.
-	 * @return mixed
-	 */
-	public function get( $query_var ) {
-		if ( isset( $this->query_vars[$query_var] ) )
-			return $this->query_vars[$query_var];
-
-		return null;
-	}
-
-	/**
-	 * Set query variable.
-	 *
-	 * @since 3.5.0
-	 * @access public
-	 *
-	 * @param string $query_var Query variable key.
-	 * @param mixed $value Query variable value.
-	 */
-	public function set( $query_var, $value ) {
-		$this->query_vars[$query_var] = $value;
-	}
-
-	/**
-	 * Used internally to generate an SQL string for searching across multiple columns
-	 *
-	 * @access protected
-	 * @since 3.1.0
-	 *
-	 * @param string $string
-	 * @param array $cols
-	 * @param bool $wild Whether to allow wildcard searches. Default is false for Network Admin, true for
-	 *  single site. Single site allows leading and trailing wildcards, Network Admin only trailing.
-	 * @return string
-	 */
-	protected function get_search_sql( $string, $cols, $wild = false ) {
-		global $wpdb;
-
-		$searches = array();
-		$leading_wild = ( 'leading' == $wild || 'both' == $wild ) ? '%' : '';
-		$trailing_wild = ( 'trailing' == $wild || 'both' == $wild ) ? '%' : '';
-		$like = $leading_wild . $wpdb->esc_like( $string ) . $trailing_wild;
-
-		foreach ( $cols as $col ) {
-			if ( 'ID' == $col ) {
-				$searches[] = $wpdb->prepare( "$col = %s", $string );
-			} else {
-				$searches[] = $wpdb->prepare( "$col LIKE %s", $like );
-			}
-		}
-
-		return ' AND (' . implode(' OR ', $searches) . ')';
-	}
-
-	/**
-	 * Return the list of users.
-	 *
-	 * @since 3.1.0
-	 * @access public
-	 *
-	 * @return array Array of results.
-	 */
-	public function get_results() {
-		return $this->results;
-	}
-
-	/**
-	 * Return the total number of users for the current query.
-	 *
-	 * @since 3.1.0
-	 * @access public
-	 *
-	 * @return int Number of total users.
-	 */
-	public function get_total() {
-		return $this->total_users;
-	}
-
-	/**
-	 * Parse and sanitize 'orderby' keys passed to the user query.
-	 *
-	 * @since 4.2.0
-	 * @access protected
-	 *
-	 * @global wpdb $wpdb WordPress database abstraction object.
-	 *
-	 * @param string $orderby Alias for the field to order by.
-	 * @return string|bool Value to used in the ORDER clause, if `$orderby` is valid. False otherwise.
-	 */
-	protected function parse_orderby( $orderby ) {
-		global $wpdb;
-
-		$meta_query_clauses = $this->meta_query->get_clauses();
-
-		$_orderby = '';
-		if ( in_array( $orderby, array( 'login', 'nicename', 'email', 'url', 'registered' ) ) ) {
-			$_orderby = 'user_' . $orderby;
-		} elseif ( in_array( $orderby, array( 'user_login', 'user_nicename', 'user_email', 'user_url', 'user_registered' ) ) ) {
-			$_orderby = $orderby;
-		} elseif ( 'name' == $orderby || 'display_name' == $orderby ) {
-			$_orderby = 'display_name';
-		} elseif ( 'post_count' == $orderby ) {
-			// todo: avoid the JOIN
-			$where = get_posts_by_author_sql( 'post' );
-			$this->query_from .= " LEFT OUTER JOIN (
-				SELECT post_author, COUNT(*) as post_count
-				FROM $wpdb->posts
-				$where
-				GROUP BY post_author
-			) p ON ({$wpdb->users}.ID = p.post_author)
-			";
-			$_orderby = 'post_count';
-		} elseif ( 'ID' == $orderby || 'id' == $orderby ) {
-			$_orderby = 'ID';
-		} elseif ( 'meta_value' == $orderby || $this->get( 'meta_key' ) == $orderby ) {
-			$_orderby = "$wpdb->usermeta.meta_value";
-		} elseif ( 'meta_value_num' == $orderby ) {
-			$_orderby = "$wpdb->usermeta.meta_value+0";
-		} elseif ( 'include' === $orderby && ! empty( $this->query_vars['include'] ) ) {
-			$include = wp_parse_id_list( $this->query_vars['include'] );
-			$include_sql = implode( ',', $include );
-			$_orderby = "FIELD( $wpdb->users.ID, $include_sql )";
-		} elseif ( isset( $meta_query_clauses[ $orderby ] ) ) {
-			$meta_clause = $meta_query_clauses[ $orderby ];
-			$_orderby = sprintf( "CAST(%s.meta_value AS %s)", esc_sql( $meta_clause['alias'] ), esc_sql( $meta_clause['cast'] ) );
-		}
-
-		return $_orderby;
-	}
-
-	/**
-	 * Parse an 'order' query variable and cast it to ASC or DESC as necessary.
-	 *
-	 * @since 4.2.0
-	 * @access protected
-	 *
-	 * @param string $order The 'order' query variable.
-	 * @return string The sanitized 'order' query variable.
-	 */
-	protected function parse_order( $order ) {
-		if ( ! is_string( $order ) || empty( $order ) ) {
-			return 'DESC';
-		}
-
-		if ( 'ASC' === strtoupper( $order ) ) {
-			return 'ASC';
-		} else {
-			return 'DESC';
-		}
-	}
-
-	/**
-	 * Make private properties readable for backwards compatibility.
-	 *
-	 * @since 4.0.0
-	 * @access public
-	 *
-	 * @param string $name Property to get.
-	 * @return mixed Property.
-	 */
-	public function __get( $name ) {
-		if ( in_array( $name, $this->compat_fields ) ) {
-			return $this->$name;
-		}
-	}
-
-	/**
-	 * Make private properties settable for backwards compatibility.
-	 *
-	 * @since 4.0.0
-	 * @access public
-	 *
-	 * @param string $name  Property to check if set.
-	 * @param mixed  $value Property value.
-	 * @return mixed Newly-set property.
-	 */
-	public function __set( $name, $value ) {
-		if ( in_array( $name, $this->compat_fields ) ) {
-			return $this->$name = $value;
-		}
-	}
-
-	/**
-	 * Make private properties checkable for backwards compatibility.
-	 *
-	 * @since 4.0.0
-	 * @access public
-	 *
-	 * @param string $name Property to check if set.
-	 * @return bool Whether the property is set.
-	 */
-	public function __isset( $name ) {
-		if ( in_array( $name, $this->compat_fields ) ) {
-			return isset( $this->$name );
-		}
-	}
-
-	/**
-	 * Make private properties un-settable for backwards compatibility.
-	 *
-	 * @since 4.0.0
-	 * @access public
-	 *
-	 * @param string $name Property to unset.
-	 */
-	public function __unset( $name ) {
-		if ( in_array( $name, $this->compat_fields ) ) {
-			unset( $this->$name );
-		}
-	}
-
-	/**
-	 * Make private/protected methods readable for backwards compatibility.
-	 *
-	 * @since 4.0.0
-	 * @access public
-	 *
-	 * @param callable $name      Method to call.
-	 * @param array    $arguments Arguments to pass when calling.
-	 * @return mixed|bool Return value of the callback, false otherwise.
-	 */
-	public function __call( $name, $arguments ) {
-		if ( 'get_search_sql' === $name ) {
-			return call_user_func_array( array( $this, $name ), $arguments );
-		}
-		return false;
-	}
-}
-
-/**
  * Retrieve list of users matching criteria.
  *
  * @since 3.1.0
  *
  * @see WP_User_Query
  *
- * @param array $args Optional. Arguments to retrieve users. See {@see WP_User_Query::prepare_query()}
+ * @param array $args Optional. Arguments to retrieve users. See WP_User_Query::prepare_query().
  *                    for more information on accepted arguments.
  * @return array List of users.
  */
@@ -1119,63 +564,70 @@
 }
 
 /**
- * Get the blogs a user belongs to.
+ * Get the sites a user belongs to.
  *
  * @since 3.0.0
+ * @since 4.7.0 Converted to use get_sites().
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param int  $user_id User ID
- * @param bool $all     Whether to retrieve all blogs, or only blogs that are not
+ * @param bool $all     Whether to retrieve all sites, or only sites that are not
  *                      marked as deleted, archived, or spam.
- * @return array A list of the user's blogs. An empty array if the user doesn't exist
- *               or belongs to no blogs.
+ * @return array A list of the user's sites. An empty array if the user doesn't exist
+ *               or belongs to no sites.
  */
 function get_blogs_of_user( $user_id, $all = false ) {
 	global $wpdb;
 
 	$user_id = (int) $user_id;
 
-	// Logged out users can't have blogs
+	// Logged out users can't have sites
 	if ( empty( $user_id ) )
 		return array();
 
+	/**
+	 * Filters the list of a user's sites before it is populated.
+	 *
+	 * Passing a non-null value to the filter will effectively short circuit
+	 * get_blogs_of_user(), returning that value instead.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param null|array $sites   An array of site objects of which the user is a member.
+	 * @param int        $user_id User ID.
+	 * @param bool       $all     Whether the returned array should contain all sites, including
+	 *                            those marked 'deleted', 'archived', or 'spam'. Default false.
+	 */
+	$sites = apply_filters( 'pre_get_blogs_of_user', null, $user_id, $all );
+
+	if ( null !== $sites ) {
+		return $sites;
+	}
+
 	$keys = get_user_meta( $user_id );
 	if ( empty( $keys ) )
 		return array();
 
 	if ( ! is_multisite() ) {
-		$blog_id = get_current_blog_id();
-		$blogs = array( $blog_id => new stdClass );
-		$blogs[ $blog_id ]->userblog_id = $blog_id;
-		$blogs[ $blog_id ]->blogname = get_option('blogname');
-		$blogs[ $blog_id ]->domain = '';
-		$blogs[ $blog_id ]->path = '';
-		$blogs[ $blog_id ]->site_id = 1;
-		$blogs[ $blog_id ]->siteurl = get_option('siteurl');
-		$blogs[ $blog_id ]->archived = 0;
-		$blogs[ $blog_id ]->spam = 0;
-		$blogs[ $blog_id ]->deleted = 0;
-		return $blogs;
+		$site_id = get_current_blog_id();
+		$sites = array( $site_id => new stdClass );
+		$sites[ $site_id ]->userblog_id = $site_id;
+		$sites[ $site_id ]->blogname = get_option('blogname');
+		$sites[ $site_id ]->domain = '';
+		$sites[ $site_id ]->path = '';
+		$sites[ $site_id ]->site_id = 1;
+		$sites[ $site_id ]->siteurl = get_option('siteurl');
+		$sites[ $site_id ]->archived = 0;
+		$sites[ $site_id ]->spam = 0;
+		$sites[ $site_id ]->deleted = 0;
+		return $sites;
 	}
 
-	$blogs = array();
+	$site_ids = array();
 
 	if ( isset( $keys[ $wpdb->base_prefix . 'capabilities' ] ) && defined( 'MULTISITE' ) ) {
-		$blog = get_blog_details( 1 );
-		if ( $blog && isset( $blog->domain ) && ( $all || ( ! $blog->archived && ! $blog->spam && ! $blog->deleted ) ) ) {
-			$blogs[ 1 ] = (object) array(
-				'userblog_id' => 1,
-				'blogname'    => $blog->blogname,
-				'domain'      => $blog->domain,
-				'path'        => $blog->path,
-				'site_id'     => $blog->site_id,
-				'siteurl'     => $blog->siteurl,
-				'archived'    => 0,
-				'spam'        => 0,
-				'deleted'     => 0
-			);
-		}
+		$site_ids[] = 1;
 		unset( $keys[ $wpdb->base_prefix . 'capabilities' ] );
 	}
 
@@ -1186,76 +638,133 @@
 			continue;
 		if ( $wpdb->base_prefix && 0 !== strpos( $key, $wpdb->base_prefix ) )
 			continue;
-		$blog_id = str_replace( array( $wpdb->base_prefix, '_capabilities' ), '', $key );
-		if ( ! is_numeric( $blog_id ) )
+		$site_id = str_replace( array( $wpdb->base_prefix, '_capabilities' ), '', $key );
+		if ( ! is_numeric( $site_id ) )
 			continue;
 
-		$blog_id = (int) $blog_id;
-		$blog = get_blog_details( $blog_id );
-		if ( $blog && isset( $blog->domain ) && ( $all || ( ! $blog->archived && ! $blog->spam && ! $blog->deleted ) ) ) {
-			$blogs[ $blog_id ] = (object) array(
-				'userblog_id' => $blog_id,
-				'blogname'    => $blog->blogname,
-				'domain'      => $blog->domain,
-				'path'        => $blog->path,
-				'site_id'     => $blog->site_id,
-				'siteurl'     => $blog->siteurl,
-				'archived'    => 0,
-				'spam'        => 0,
-				'deleted'     => 0
+		$site_ids[] = (int) $site_id;
+	}
+
+	$sites = array();
+
+	if ( ! empty( $site_ids ) ) {
+		$args = array(
+			'number'   => '',
+			'site__in' => $site_ids,
+		);
+		if ( ! $all ) {
+			$args['archived'] = 0;
+			$args['spam']     = 0;
+			$args['deleted']  = 0;
+		}
+
+		$_sites = get_sites( $args );
+
+		foreach ( $_sites as $site ) {
+			$sites[ $site->id ] = (object) array(
+				'userblog_id' => $site->id,
+				'blogname'    => $site->blogname,
+				'domain'      => $site->domain,
+				'path'        => $site->path,
+				'site_id'     => $site->network_id,
+				'siteurl'     => $site->siteurl,
+				'archived'    => $site->archived,
+				'mature'      => $site->mature,
+				'spam'        => $site->spam,
+				'deleted'     => $site->deleted,
 			);
 		}
 	}
 
 	/**
-	 * Filter the list of blogs a user belongs to.
+	 * Filters the list of sites a user belongs to.
 	 *
-	 * @since MU
+	 * @since MU (3.0.0)
 	 *
-	 * @param array $blogs   An array of blog objects belonging to the user.
+	 * @param array $sites   An array of site objects belonging to the user.
 	 * @param int   $user_id User ID.
-	 * @param bool  $all     Whether the returned blogs array should contain all blogs, including
+	 * @param bool  $all     Whether the returned sites array should contain all sites, including
 	 *                       those marked 'deleted', 'archived', or 'spam'. Default false.
 	 */
-	return apply_filters( 'get_blogs_of_user', $blogs, $user_id, $all );
+	return apply_filters( 'get_blogs_of_user', $sites, $user_id, $all );
 }
 
 /**
  * Find out whether a user is a member of a given blog.
  *
- * @since MU 1.1
+ * @since MU (3.0.0)
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
  * @param int $user_id Optional. The unique ID of the user. Defaults to the current user.
  * @param int $blog_id Optional. ID of the blog to check. Defaults to the current site.
  * @return bool
  */
 function is_user_member_of_blog( $user_id = 0, $blog_id = 0 ) {
+	global $wpdb;
+
 	$user_id = (int) $user_id;
 	$blog_id = (int) $blog_id;
 
-	if ( empty( $user_id ) )
+	if ( empty( $user_id ) ) {
 		$user_id = get_current_user_id();
-
-	if ( empty( $blog_id ) )
+	}
+
+	// Technically not needed, but does save calls to get_site and get_user_meta
+	// in the event that the function is called when a user isn't logged in
+	if ( empty( $user_id ) ) {
+		return false;
+	} else {
+		$user = get_userdata( $user_id );
+		if ( ! $user instanceof WP_User ) {
+			return false;
+		}
+	}
+
+	if ( ! is_multisite() ) {
+		return true;
+	}
+
+	if ( empty( $blog_id ) ) {
 		$blog_id = get_current_blog_id();
-
-	$blogs = get_blogs_of_user( $user_id );
-	return array_key_exists( $blog_id, $blogs );
+	}
+
+	$blog = get_site( $blog_id );
+
+	if ( ! $blog || ! isset( $blog->domain ) || $blog->archived || $blog->spam || $blog->deleted ) {
+		return false;
+	}
+
+	$keys = get_user_meta( $user_id );
+	if ( empty( $keys ) ) {
+		return false;
+	}
+
+	// no underscore before capabilities in $base_capabilities_key
+	$base_capabilities_key = $wpdb->base_prefix . 'capabilities';
+	$site_capabilities_key = $wpdb->base_prefix . $blog_id . '_capabilities';
+
+	if ( isset( $keys[ $base_capabilities_key ] ) && $blog_id == 1 ) {
+		return true;
+	}
+
+	if ( isset( $keys[ $site_capabilities_key ] ) ) {
+		return true;
+	}
+
+	return false;
 }
 
 /**
- * Add meta data field to a user.
- *
- * Post meta data is called "Custom Fields" on the Administration Screens.
+ * Adds meta data to a user.
  *
  * @since 3.0.0
- * @link https://codex.wordpress.org/Function_Reference/add_user_meta
  *
- * @param int $user_id User ID.
- * @param string $meta_key Metadata name.
- * @param mixed $meta_value Metadata value.
- * @param bool $unique Optional, default is false. Whether the same key should not be added.
- * @return int|bool Meta ID on success, false on failure.
+ * @param int    $user_id    User ID.
+ * @param string $meta_key   Metadata name.
+ * @param mixed  $meta_value Metadata value.
+ * @param bool   $unique     Optional. Whether the same key should not be added. Default false.
+ * @return int|false Meta ID on success, false on failure.
  */
 function add_user_meta($user_id, $meta_key, $meta_value, $unique = false) {
 	return add_metadata('user', $user_id, $meta_key, $meta_value, $unique);
@@ -1271,9 +780,9 @@
  * @since 3.0.0
  * @link https://codex.wordpress.org/Function_Reference/delete_user_meta
  *
- * @param int $user_id user ID
- * @param string $meta_key Metadata name.
- * @param mixed $meta_value Optional. Metadata value.
+ * @param int    $user_id    User ID
+ * @param string $meta_key   Metadata name.
+ * @param mixed  $meta_value Optional. Metadata value.
  * @return bool True on success, false on failure.
  */
 function delete_user_meta($user_id, $meta_key, $meta_value = '') {
@@ -1286,11 +795,10 @@
  * @since 3.0.0
  * @link https://codex.wordpress.org/Function_Reference/get_user_meta
  *
- * @param int $user_id User ID.
- * @param string $key Optional. The meta key to retrieve. By default, returns data for all keys.
- * @param bool $single Whether to return a single value.
- * @return mixed Will be an array if $single is false. Will be value of meta data field if $single
- *  is true.
+ * @param int    $user_id User ID.
+ * @param string $key     Optional. The meta key to retrieve. By default, returns data for all keys.
+ * @param bool   $single  Whether to return a single value.
+ * @return mixed Will be an array if $single is false. Will be value of meta data field if $single is true.
  */
 function get_user_meta($user_id, $key = '', $single = false) {
 	return get_metadata('user', $user_id, $key, $single);
@@ -1307,10 +815,10 @@
  * @since 3.0.0
  * @link https://codex.wordpress.org/Function_Reference/update_user_meta
  *
- * @param int $user_id User ID.
- * @param string $meta_key Metadata key.
- * @param mixed $meta_value Metadata value.
- * @param mixed $prev_value Optional. Previous value to check before removing.
+ * @param int    $user_id    User ID.
+ * @param string $meta_key   Metadata key.
+ * @param mixed  $meta_value Metadata value.
+ * @param mixed  $prev_value Optional. Previous value to check before removing.
  * @return int|bool Meta ID if the key didn't exist, true on successful update, false on failure.
  */
 function update_user_meta($user_id, $meta_key, $meta_value, $prev_value = '') {
@@ -1326,34 +834,50 @@
  * Using $strategy = 'memory' this is memory-intensive and should handle around 10^5 users, but see WP Bug #12257.
  *
  * @since 3.0.0
- * @param string $strategy 'time' or 'memory'
+ * @since 4.4.0 The number of users with no role is now included in the `none` element.
+ * @since 4.9.0 The `$site_id` parameter was added to support multisite.
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
+ *
+ * @param string   $strategy Optional. The computational strategy to use when counting the users.
+ *                           Accepts either 'time' or 'memory'. Default 'time'.
+ * @param int|null $site_id  Optional. The site ID to count users for. Defaults to the current site.
  * @return array Includes a grand total and an array of counts indexed by role strings.
  */
-function count_users($strategy = 'time') {
-	global $wpdb, $wp_roles;
+function count_users( $strategy = 'time', $site_id = null ) {
+	global $wpdb;
 
 	// Initialize
-	$id = get_current_blog_id();
-	$blog_prefix = $wpdb->get_blog_prefix($id);
+	if ( ! $site_id ) {
+		$site_id = get_current_blog_id();
+	}
+	$blog_prefix = $wpdb->get_blog_prefix( $site_id );
 	$result = array();
 
 	if ( 'time' == $strategy ) {
-		global $wp_roles;
-
-		if ( ! isset( $wp_roles ) )
-			$wp_roles = new WP_Roles();
-
-		$avail_roles = $wp_roles->get_names();
+		if ( is_multisite() && $site_id != get_current_blog_id() ) {
+			switch_to_blog( $site_id );
+			$avail_roles = wp_roles()->get_names();
+			restore_current_blog();
+		} else {
+			$avail_roles = wp_roles()->get_names();
+		}
 
 		// Build a CPU-intensive query that will return concise information.
 		$select_count = array();
 		foreach ( $avail_roles as $this_role => $name ) {
 			$select_count[] = $wpdb->prepare( "COUNT(NULLIF(`meta_value` LIKE %s, false))", '%' . $wpdb->esc_like( '"' . $this_role . '"' ) . '%');
 		}
+		$select_count[] = "COUNT(NULLIF(`meta_value` = 'a:0:{}', false))";
 		$select_count = implode(', ', $select_count);
 
 		// Add the meta_value index to the selection list, then run the query.
-		$row = $wpdb->get_row( "SELECT $select_count, COUNT(*) FROM $wpdb->usermeta WHERE meta_key = '{$blog_prefix}capabilities'", ARRAY_N );
+		$row = $wpdb->get_row( "
+			SELECT {$select_count}, COUNT(*)
+			FROM {$wpdb->usermeta}
+			INNER JOIN {$wpdb->users} ON user_id = ID
+			WHERE meta_key = '{$blog_prefix}capabilities'
+		", ARRAY_N );
 
 		// Run the previous loop again to associate results with role names.
 		$col = 0;
@@ -1365,20 +889,32 @@
 			}
 		}
 
+		$role_counts['none'] = (int) $row[$col++];
+
 		// Get the meta_value index from the end of the result set.
 		$total_users = (int) $row[$col];
 
 		$result['total_users'] = $total_users;
 		$result['avail_roles'] =& $role_counts;
 	} else {
-		$avail_roles = array();
-
-		$users_of_blog = $wpdb->get_col( "SELECT meta_value FROM $wpdb->usermeta WHERE meta_key = '{$blog_prefix}capabilities'" );
+		$avail_roles = array(
+			'none' => 0,
+		);
+
+		$users_of_blog = $wpdb->get_col( "
+			SELECT meta_value
+			FROM {$wpdb->usermeta}
+			INNER JOIN {$wpdb->users} ON user_id = ID
+			WHERE meta_key = '{$blog_prefix}capabilities'
+		" );
 
 		foreach ( $users_of_blog as $caps_meta ) {
 			$b_roles = maybe_unserialize($caps_meta);
 			if ( ! is_array( $b_roles ) )
 				continue;
+			if ( empty( $b_roles ) ) {
+				$avail_roles['none']++;
+			}
 			foreach ( $b_roles as $b_role => $val ) {
 				if ( isset($avail_roles[$b_role]) ) {
 					$avail_roles[$b_role]++;
@@ -1405,13 +941,14 @@
  * Used by wp_set_current_user() for back compat. Might be deprecated in the future.
  *
  * @since 2.0.4
- * @global string $userdata User description.
- * @global string $user_login The user username for logging in
- * @global int $user_level The level of the user
- * @global int $user_ID The ID of the user
- * @global string $user_email The email address of the user
- * @global string $user_url The url in the user's profile
- * @global string $user_identity The display name of the user
+ *
+ * @global string  $user_login    The user username for logging in
+ * @global WP_User $userdata      User data.
+ * @global int     $user_level    The level of the user
+ * @global int     $user_ID       The ID of the user
+ * @global string  $user_email    The email address of the user
+ * @global string  $user_url      The url in the user's profile
+ * @global string  $user_identity The display name of the user
  *
  * @param int $for_user_id Optional. User ID to set up global data.
  */
@@ -1450,12 +987,12 @@
  * The available arguments are as follows:
  *
  * @since 2.3.0
- *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @since 4.5.0 Added the 'display_name_with_login' value for 'show'.
+ * @since 4.7.0 Added the `$role`, `$role__in`, and `$role__not_in` parameters.
  *
  * @param array|string $args {
  *     Optional. Array or string of arguments to generate a drop-down of users.
- *     {@see WP_User_Query::prepare_query() for additional available arguments.
+ *     See WP_User_Query::prepare_query() for additional available arguments.
  *
  *     @type string       $show_option_all         Text to show as the drop-down default (all).
  *                                                 Default empty.
@@ -1476,9 +1013,11 @@
  *                                                 Default empty.
  *     @type bool|int     $multi                   Whether to skip the ID attribute on the 'select' element.
  *                                                 Accepts 1|true or 0|false. Default 0|false.
- *     @type string       $show                    User table column to display. If the selected item is empty
+ *     @type string       $show                    User data to display. If the selected item is empty
  *                                                 then the 'user_login' will be displayed in parentheses.
- *                                                 Accepts user fields. Default 'display_name'.
+ *                                                 Accepts any user field, or 'display_name_with_login' to show
+ *                                                 the display name with user_login in parentheses.
+ *                                                 Default 'display_name'.
  *     @type int|bool     $echo                    Whether to echo or return the drop-down. Accepts 1|true (echo)
  *                                                 or 0|false (return). Default 1|true.
  *     @type int          $selected                Which user ID should be selected. Default 0.
@@ -1490,8 +1029,15 @@
  *     @type int          $blog_id                 ID of blog (Multisite only). Default is ID of the current blog.
  *     @type string       $who                     Which type of users to query. Accepts only an empty string or
  *                                                 'authors'. Default empty.
+ *     @type string|array $role                    An array or a comma-separated list of role names that users must
+ *                                                 match to be included in results. Note that this is an inclusive
+ *                                                 list: users must match *each* role. Default empty.
+ *     @type array        $role__in                An array of role names. Matched users must have at least one of
+ *                                                 these roles. Default empty array.
+ *     @type array        $role__not_in            An array of role names to exclude. Users matching one or more of
+ *                                                 these roles will not be included in results. Default empty array.
  * }
- * @return string|null Null on display. String of HTML content on retrieve.
+ * @return string String of HTML content.
  */
 function wp_dropdown_users( $args = '' ) {
 	$defaults = array(
@@ -1500,20 +1046,44 @@
 		'include' => '', 'exclude' => '', 'multi' => 0,
 		'show' => 'display_name', 'echo' => 1,
 		'selected' => 0, 'name' => 'user', 'class' => '', 'id' => '',
-		'blog_id' => $GLOBALS['blog_id'], 'who' => '', 'include_selected' => false,
-		'option_none_value' => -1
+		'blog_id' => get_current_blog_id(), 'who' => '', 'include_selected' => false,
+		'option_none_value' => -1,
+		'role' => '',
+		'role__in' => array(),
+		'role__not_in' => array(),
 	);
 
 	$defaults['selected'] = is_author() ? get_query_var( 'author' ) : 0;
 
 	$r = wp_parse_args( $args, $defaults );
-	$show = $r['show'];
+
+	$query_args = wp_array_slice_assoc( $r, array( 'blog_id', 'include', 'exclude', 'orderby', 'order', 'who', 'role', 'role__in', 'role__not_in' ) );
+
+	$fields = array( 'ID', 'user_login' );
+
+	$show = ! empty( $r['show'] ) ? $r['show'] : 'display_name';
+	if ( 'display_name_with_login' === $show ) {
+		$fields[] = 'display_name';
+	} else {
+		$fields[] = $show;
+	}
+
+	$query_args['fields'] = $fields;
+
 	$show_option_all = $r['show_option_all'];
 	$show_option_none = $r['show_option_none'];
 	$option_none_value = $r['option_none_value'];
 
-	$query_args = wp_array_slice_assoc( $r, array( 'blog_id', 'include', 'exclude', 'orderby', 'order', 'who' ) );
-	$query_args['fields'] = array( 'ID', 'user_login', $show );
+	/**
+	 * Filters the query arguments for the list of users in the dropdown.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param array $query_args The query arguments for get_users().
+	 * @param array $r          The arguments passed to wp_dropdown_users() combined with the defaults.
+	 */
+	$query_args = apply_filters( 'wp_dropdown_users_args', $query_args, $r );
+
 	$users = get_users( $query_args );
 
 	$output = '';
@@ -1535,21 +1105,32 @@
 			$output .= "\t<option value='" . esc_attr( $option_none_value ) . "'$_selected>$show_option_none</option>\n";
 		}
 
-		$found_selected = false;
-		foreach ( (array) $users as $user ) {
-			$user->ID = (int) $user->ID;
-			$_selected = selected( $user->ID, $r['selected'], false );
-			if ( $_selected ) {
-				$found_selected = true;
+		if ( $r['include_selected'] && ( $r['selected'] > 0 ) ) {
+			$found_selected = false;
+			$r['selected'] = (int) $r['selected'];
+			foreach ( (array) $users as $user ) {
+				$user->ID = (int) $user->ID;
+				if ( $user->ID === $r['selected'] ) {
+					$found_selected = true;
+				}
+			}
+
+			if ( ! $found_selected ) {
+				$users[] = get_userdata( $r['selected'] );
 			}
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
-			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}
 
-		if ( $r['include_selected'] && ! $found_selected && ( $r['selected'] > 0 ) ) {
-			$user = get_userdata( $r['selected'] );
+		foreach ( (array) $users as $user ) {
+			if ( 'display_name_with_login' === $show ) {
+				/* translators: 1: display name, 2: user_login */
+				$display = sprintf( _x( '%1$s (%2$s)', 'user dropdown' ), $user->display_name, $user->user_login );
+			} elseif ( ! empty( $user->$show ) ) {
+				$display = $user->$show;
+			} else {
+				$display = '(' . $user->user_login . ')';
+			}
+
 			$_selected = selected( $user->ID, $r['selected'], false );
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
 			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}
 
@@ -1557,7 +1138,7 @@
 	}
 
 	/**
-	 * Filter the wp_dropdown_users() HTML output.
+	 * Filters the wp_dropdown_users() HTML output.
 	 *
 	 * @since 2.3.0
 	 *
@@ -1580,11 +1161,11 @@
  *
  * @since 2.3.0
  *
- * @param string $field The user Object field name.
- * @param mixed $value The user Object value.
- * @param int $user_id user ID.
+ * @param string $field   The user Object field name.
+ * @param mixed  $value   The user Object value.
+ * @param int    $user_id User ID.
  * @param string $context How to sanitize user fields. Looks for 'raw', 'edit', 'db', 'display',
- *               'attribute' and 'js'.
+ *                        'attribute' and 'js'.
  * @return mixed Sanitized value.
  */
 function sanitize_user_field($field, $value, $user_id, $context) {
@@ -1608,7 +1189,7 @@
 		} else {
 
 			/**
-			 * Filter a user field value in the 'edit' context.
+			 * Filters a user field value in the 'edit' context.
 			 *
 			 * The dynamic portion of the hook name, `$field`, refers to the prefixed user
 			 * field being filtered, such as 'user_login', 'user_email', 'first_name', etc.
@@ -1632,7 +1213,7 @@
 		} else {
 
 			/**
-			 * Filter the value of a user field in the 'db' context.
+			 * Filters the value of a user field in the 'db' context.
 			 *
 			 * The dynamic portion of the hook name, `$field`, refers to the prefixed user
 			 * field being filtered, such as 'user_login', 'user_email', 'first_name', etc.
@@ -1648,11 +1229,11 @@
 		if ( $prefixed ) {
 
 			/** This filter is documented in wp-includes/post.php */
-			$value = apply_filters( $field, $value, $user_id, $context );
+			$value = apply_filters( "{$field}", $value, $user_id, $context );
 		} else {
 
 			/**
-			 * Filter the value of a user field in a standard context.
+			 * Filters the value of a user field in a standard context.
 			 *
 			 * The dynamic portion of the hook name, `$field`, refers to the prefixed user
 			 * field being filtered, such as 'user_login', 'user_email', 'first_name', etc.
@@ -1683,9 +1264,18 @@
  *
  * @since 3.0.0
  *
- * @param object $user User object to be cached
+ * @param WP_User $user User object to be cached
+ * @return bool|null Returns false on failure.
  */
-function update_user_caches($user) {
+function update_user_caches( $user ) {
+	if ( $user instanceof WP_User ) {
+		if ( ! $user->exists() ) {
+			return false;
+		}
+
+		$user = $user->data;
+	}
+
 	wp_cache_add($user->ID, $user, 'users');
 	wp_cache_add($user->user_login, $user->ID, 'userlogins');
 	wp_cache_add($user->user_email, $user->ID, 'useremail');
@@ -1696,6 +1286,7 @@
  * Clean all user caches
  *
  * @since 3.0.0
+ * @since 4.4.0 'clean_user_cache' action was added.
  *
  * @param WP_User|int $user User object or ID to be cleaned from the cache
  */
@@ -1710,6 +1301,16 @@
 	wp_cache_delete( $user->user_login, 'userlogins' );
 	wp_cache_delete( $user->user_email, 'useremail' );
 	wp_cache_delete( $user->user_nicename, 'userslugs' );
+
+	/**
+	 * Fires immediately after the given user's cache is cleaned.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param int     $user_id User ID.
+	 * @param WP_User $user    User object.
+	 */
+	do_action( 'clean_user_cache', $user->ID, $user );
 }
 
 /**
@@ -1718,14 +1319,24 @@
  * @since 2.0.0
  *
  * @param string $username Username.
- * @return null|int The user's ID on success, and null on failure.
+ * @return int|false The user's ID on success, and false on failure.
  */
 function username_exists( $username ) {
-	if ( $user = get_user_by('login', $username ) ) {
-		return $user->ID;
+	if ( $user = get_user_by( 'login', $username ) ) {
+		$user_id = $user->ID;
 	} else {
-		return null;
+		$user_id = false;
 	}
+
+	/**
+	 * Filters whether the given username exists or not.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param int|false $user_id  The user's ID on success, and false on failure.
+	 * @param string    $username Username to check.
+	 */
+	return apply_filters( 'username_exists', $user_id, $username );
 }
 
 /**
@@ -1734,12 +1345,12 @@
  * @since 2.1.0
  *
  * @param string $email Email.
- * @return bool|int The user's ID on success, and false on failure.
+ * @return int|false The user's ID on success, and false on failure.
  */
 function email_exists( $email ) {
-	if ( $user = get_user_by('email', $email) )
+	if ( $user = get_user_by( 'email', $email) ) {
 		return $user->ID;
-
+	}
 	return false;
 }
 
@@ -1747,15 +1358,17 @@
  * Checks whether a username is valid.
  *
  * @since 2.0.1
+ * @since 4.4.0 Empty sanitized usernames are now considered invalid
  *
  * @param string $username Username.
  * @return bool Whether username given is valid
  */
 function validate_username( $username ) {
 	$sanitized = sanitize_user( $username, true );
-	$valid = ( $sanitized == $username );
+	$valid = ( $sanitized == $username && ! empty( $sanitized ) );
+
 	/**
-	 * Filter whether the provided username is valid or not.
+	 * Filters whether the provided username is valid or not.
 	 *
 	 * @since 2.0.1
 	 *
@@ -1768,40 +1381,53 @@
 /**
  * Insert a user into the database.
  *
- * Most of the $userdata array fields have filters associated with the values.
- * The exceptions are 'rich_editing', 'role', 'jabber', 'aim', 'yim',
- * 'user_registered', and 'ID'. The filters have the prefix 'pre_user_' followed
- * by the field name. An example using 'description' would have the filter
- * called, 'pre_user_description' that can be hooked into.
+ * Most of the `$userdata` array fields have filters associated with the values. Exceptions are
+ * 'ID', 'rich_editing', 'syntax_highlighting', 'comment_shortcuts', 'admin_color', 'use_ssl',
+ * 'user_registered', and 'role'. The filters have the prefix 'pre_user_' followed by the field
+ * name. An example using 'description' would have the filter called, 'pre_user_description' that
+ * can be hooked into.
  *
  * @since 2.0.0
+ * @since 3.6.0 The `aim`, `jabber`, and `yim` fields were removed as default user contact
+ *              methods for new installations. See wp_get_user_contact_methods().
+ * @since 4.7.0 The user's locale can be passed to `$userdata`.
  *
- * @global wpdb $wpdb WordPress database object for queries.
+ * @global wpdb $wpdb WordPress database abstraction object.
  *
- * @param array $userdata {
+ * @param array|object|WP_User $userdata {
  *     An array, object, or WP_User object of user data arguments.
  *
- *     @type int         $ID              User ID. If supplied, the user will be updated.
- *     @type string      $user_pass       The plain-text user password.
- *     @type string      $user_login      The user's login username.
- *     @type string      $user_nicename   The URL-friendly user name.
- *     @type string      $user_url        The user URL.
- *     @type string      $user_email      The user email address.
- *     @type string      $display_name    The user's display name.
- *                                        Default is the the user's username.
- *     @type string      $nickname        The user's nickname. Default
- *                                        Default is the the user's username.
- *     @type string      $first_name      The user's first name. For new users, will be used
- *                                        to build $display_name if unspecified.
- *     @type stirng      $last_name       The user's last name. For new users, will be used
- *                                        to build $display_name if unspecified.
- *     @type string|bool $rich_editing    Whether to enable the rich-editor for the user. False
- *                                        if not empty.
- *     @type string      $user_registered Date the user registered. Format is 'Y-m-d H:i:s'.
- *     @type string      $role            User's role.
- *     @type string      $jabber          User's Jabber account username.
- *     @type string      $aim             User's AIM account username.
- *     @type string      $yim             User's Yahoo! messenger username.
+ *     @type int         $ID                   User ID. If supplied, the user will be updated.
+ *     @type string      $user_pass            The plain-text user password.
+ *     @type string      $user_login           The user's login username.
+ *     @type string      $user_nicename        The URL-friendly user name.
+ *     @type string      $user_url             The user URL.
+ *     @type string      $user_email           The user email address.
+ *     @type string      $display_name         The user's display name.
+ *                                             Default is the user's username.
+ *     @type string      $nickname             The user's nickname.
+ *                                             Default is the user's username.
+ *     @type string      $first_name           The user's first name. For new users, will be used
+ *                                             to build the first part of the user's display name
+ *                                             if `$display_name` is not specified.
+ *     @type string      $last_name            The user's last name. For new users, will be used
+ *                                             to build the second part of the user's display name
+ *                                             if `$display_name` is not specified.
+ *     @type string      $description          The user's biographical description.
+ *     @type string|bool $rich_editing         Whether to enable the rich-editor for the user.
+ *                                             False if not empty.
+ *     @type string|bool $syntax_highlighting  Whether to enable the rich code editor for the user.
+ *                                             False if not empty.
+ *     @type string|bool $comment_shortcuts    Whether to enable comment moderation keyboard
+ *                                             shortcuts for the user. Default false.
+ *     @type string      $admin_color          Admin color scheme for the user. Default 'fresh'.
+ *     @type bool        $use_ssl              Whether the user should always access the admin over
+ *                                             https. Default false.
+ *     @type string      $user_registered      Date the user registered. Format is 'Y-m-d H:i:s'.
+ *     @type string|bool $show_admin_bar_front Whether to display the Admin Bar for the user on the
+ *                                             site's front end. Default true.
+ *     @type string      $role                 User's role.
+ *     @type string      $locale               User's locale. Default empty.
  * }
  * @return int|WP_Error The newly created user's ID or a WP_Error object if the user could not
  *                      be created.
@@ -1814,13 +1440,19 @@
 	} elseif ( $userdata instanceof WP_User ) {
 		$userdata = $userdata->to_array();
 	}
+
 	// Are we updating or creating?
 	if ( ! empty( $userdata['ID'] ) ) {
 		$ID = (int) $userdata['ID'];
 		$update = true;
-		$old_user_data = WP_User::get_data_by( 'id', $ID );
+		$old_user_data = get_userdata( $ID );
+
+		if ( ! $old_user_data ) {
+			return new WP_Error( 'invalid_user_id', __( 'Invalid user ID.' ) );
+		}
+
 		// hashed in wp_update_user(), plaintext if called directly
-		$user_pass = $userdata['user_pass'];
+		$user_pass = ! empty( $userdata['user_pass'] ) ? $userdata['user_pass'] : $old_user_data->user_pass;
 	} else {
 		$update = false;
 		// Hash the password
@@ -1830,7 +1462,7 @@
 	$sanitized_user_login = sanitize_user( $userdata['user_login'], true );
 
 	/**
-	 * Filter a username after it has been sanitized.
+	 * Filters a username after it has been sanitized.
 	 *
 	 * This filter is called before the user is created or updated.
 	 *
@@ -1843,19 +1475,41 @@
 	//Remove any non-printable chars from the login string to see if we have ended up with an empty username
 	$user_login = trim( $pre_user_login );
 
+	// user_login must be between 0 and 60 characters.
 	if ( empty( $user_login ) ) {
 		return new WP_Error('empty_user_login', __('Cannot create a user with an empty login name.') );
+	} elseif ( mb_strlen( $user_login ) > 60 ) {
+		return new WP_Error( 'user_login_too_long', __( 'Username may not be longer than 60 characters.' ) );
 	}
+
 	if ( ! $update && username_exists( $user_login ) ) {
 		return new WP_Error( 'existing_user_login', __( 'Sorry, that username already exists!' ) );
 	}
 
-	// If a nicename is provided, remove unsafe user characters before
-	// using it. Otherwise build a nicename from the user_login.
+	/**
+	 * Filters the list of blacklisted usernames.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param array $usernames Array of blacklisted usernames.
+	 */
+	$illegal_logins = (array) apply_filters( 'illegal_user_logins', array() );
+
+	if ( in_array( strtolower( $user_login ), array_map( 'strtolower', $illegal_logins ) ) ) {
+		return new WP_Error( 'invalid_username', __( 'Sorry, that username is not allowed.' ) );
+	}
+
+	/*
+	 * If a nicename is provided, remove unsafe user characters before using it.
+	 * Otherwise build a nicename from the user_login.
+	 */
 	if ( ! empty( $userdata['user_nicename'] ) ) {
 		$user_nicename = sanitize_user( $userdata['user_nicename'], true );
+		if ( mb_strlen( $user_nicename ) > 50 ) {
+			return new WP_Error( 'user_nicename_too_long', __( 'Nicename may not be longer than 50 characters.' ) );
+		}
 	} else {
-		$user_nicename = $user_login;
+		$user_nicename = mb_substr( $user_login, 0, 50 );
 	}
 
 	$user_nicename = sanitize_title( $user_nicename );
@@ -1864,7 +1518,7 @@
 	$meta = array();
 
 	/**
-	 * Filter a user's nicename before the user is created or updated.
+	 * Filters a user's nicename before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1875,7 +1529,7 @@
 	$raw_user_url = empty( $userdata['user_url'] ) ? '' : $userdata['user_url'];
 
 	/**
-	 * Filter a user's URL before the user is created or updated.
+	 * Filters a user's URL before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1886,7 +1540,7 @@
 	$raw_user_email = empty( $userdata['user_email'] ) ? '' : $userdata['user_email'];
 
 	/**
-	 * Filter a user's email before the user is created or updated.
+	 * Filters a user's email before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1899,7 +1553,7 @@
 	 * check if current email and new email are the same, or not, and check `email_exists`
 	 * accordingly.
 	 */
-	if ( ( ! $update || ( ! empty( $old_user_data ) && $user_email !== $old_user_data->user_email ) )
+	if ( ( ! $update || ( ! empty( $old_user_data ) && 0 !== strcasecmp( $user_email, $old_user_data->user_email ) ) )
 		&& ! defined( 'WP_IMPORTING' )
 		&& email_exists( $user_email )
 	) {
@@ -1908,7 +1562,7 @@
 	$nickname = empty( $userdata['nickname'] ) ? $user_login : $userdata['nickname'];
 
 	/**
-	 * Filter a user's nickname before the user is created or updated.
+	 * Filters a user's nickname before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1919,7 +1573,7 @@
 	$first_name = empty( $userdata['first_name'] ) ? '' : $userdata['first_name'];
 
 	/**
-	 * Filter a user's first name before the user is created or updated.
+	 * Filters a user's first name before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1930,7 +1584,7 @@
 	$last_name = empty( $userdata['last_name'] ) ? '' : $userdata['last_name'];
 
 	/**
-	 * Filter a user's last name before the user is created or updated.
+	 * Filters a user's last name before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1956,7 +1610,7 @@
 	}
 
 	/**
-	 * Filter a user's display name before the user is created or updated.
+	 * Filters a user's display name before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1967,7 +1621,7 @@
 	$description = empty( $userdata['description'] ) ? '' : $userdata['description'];
 
 	/**
-	 * Filter a user's description before the user is created or updated.
+	 * Filters a user's description before the user is created or updated.
 	 *
 	 * @since 2.0.3
 	 *
@@ -1977,7 +1631,9 @@
 
 	$meta['rich_editing'] = empty( $userdata['rich_editing'] ) ? 'true' : $userdata['rich_editing'];
 
-	$meta['comment_shortcuts'] = empty( $userdata['comment_shortcuts'] ) ? 'false' : $userdata['comment_shortcuts'];
+	$meta['syntax_highlighting'] = empty( $userdata['syntax_highlighting'] ) ? 'true' : $userdata['syntax_highlighting'];
+
+	$meta['comment_shortcuts'] = empty( $userdata['comment_shortcuts'] ) || 'false' === $userdata['comment_shortcuts'] ? 'false' : 'true';
 
 	$admin_color = empty( $userdata['admin_color'] ) ? 'fresh' : $userdata['admin_color'];
 	$meta['admin_color'] = preg_replace( '|[^a-z0-9 _.\-@]|i', '', $admin_color );
@@ -1988,12 +1644,16 @@
 
 	$meta['show_admin_bar_front'] = empty( $userdata['show_admin_bar_front'] ) ? 'true' : $userdata['show_admin_bar_front'];
 
+	$meta['locale'] = isset( $userdata['locale'] ) ? $userdata['locale'] : '';
+
 	$user_nicename_check = $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->users WHERE user_nicename = %s AND user_login != %s LIMIT 1" , $user_nicename, $user_login));
 
 	if ( $user_nicename_check ) {
 		$suffix = 2;
 		while ($user_nicename_check) {
-			$alt_user_nicename = $user_nicename . "-$suffix";
+			// user_nicename allows 50 chars. Subtract one for a hyphen, plus the length of the suffix.
+			$base_length = 49 - mb_strlen( $suffix );
+			$alt_user_nicename = mb_substr( $user_nicename, 0, $base_length ) . "-$suffix";
 			$user_nicename_check = $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->users WHERE user_nicename = %s AND user_login != %s LIMIT 1" , $alt_user_nicename, $user_login));
 			$suffix++;
 		}
@@ -2003,6 +1663,34 @@
 	$compacted = compact( 'user_pass', 'user_email', 'user_url', 'user_nicename', 'display_name', 'user_registered' );
 	$data = wp_unslash( $compacted );
 
+	if ( ! $update ) {
+		$data = $data + compact( 'user_login' );
+	}
+
+	/**
+	 * Filters user data before the record is created or updated.
+	 *
+	 * It only includes data in the wp_users table wp_user, not any user metadata.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param array    $data {
+	 *     Values and keys for the user.
+	 *
+	 *     @type string $user_login      The user's login. Only included if $update == false
+	 *     @type string $user_pass       The user's password.
+	 *     @type string $user_email      The user's email.
+	 *     @type string $user_url        The user's url.
+	 *     @type string $user_nicename   The user's nice name. Defaults to a URL-safe version of user's login
+	 *     @type string $display_name    The user's display name.
+	 *     @type string $user_registered MySQL timestamp describing the moment when the user registered. Defaults to
+	 *                                   the current UTC timestamp.
+	 * }
+	 * @param bool     $update Whether the user is being updated rather than created.
+	 * @param int|null $id     ID of the user to be updated, or NULL if the user is being created.
+	 */
+	$data = apply_filters( 'wp_pre_insert_user_data', $data, $update, $update ? (int) $ID : null );
+
 	if ( $update ) {
 		if ( $user_email !== $old_user_data->user_email ) {
 			$data['user_activation_key'] = '';
@@ -2010,12 +1698,41 @@
 		$wpdb->update( $wpdb->users, $data, compact( 'ID' ) );
 		$user_id = (int) $ID;
 	} else {
-		$wpdb->insert( $wpdb->users, $data + compact( 'user_login' ) );
+		$wpdb->insert( $wpdb->users, $data );
 		$user_id = (int) $wpdb->insert_id;
 	}
 
 	$user = new WP_User( $user_id );
 
+	/**
+ 	 * Filters a user's meta values and keys immediately after the user is created or updated
+ 	 * and before any user meta is inserted or updated.
+ 	 *
+ 	 * Does not include contact methods. These are added using `wp_get_user_contact_methods( $user )`.
+ 	 *
+ 	 * @since 4.4.0
+ 	 *
+ 	 * @param array $meta {
+ 	 *     Default meta values and keys for the user.
+ 	 *
+ 	 *     @type string   $nickname             The user's nickname. Default is the user's username.
+	 *     @type string   $first_name           The user's first name.
+	 *     @type string   $last_name            The user's last name.
+	 *     @type string   $description          The user's description.
+	 *     @type bool     $rich_editing         Whether to enable the rich-editor for the user. False if not empty.
+	 *     @type bool     $syntax_highlighting  Whether to enable the rich code editor for the user. False if not empty.
+	 *     @type bool     $comment_shortcuts    Whether to enable keyboard shortcuts for the user. Default false.
+	 *     @type string   $admin_color          The color scheme for a user's admin screen. Default 'fresh'.
+	 *     @type int|bool $use_ssl              Whether to force SSL on the user's admin area. 0|false if SSL is
+	 *                                          not forced.
+	 *     @type bool     $show_admin_bar_front Whether to show the admin bar on the front end for the user.
+	 *                                          Default true.
+ 	 * }
+	 * @param WP_User $user   User object.
+	 * @param bool    $update Whether the user is being updated rather than created.
+ 	 */
+	$meta = apply_filters( 'insert_user_meta', $meta, $user, $update );
+
 	// Update user meta.
 	foreach ( $meta as $key => $value ) {
 		update_user_meta( $user_id, $key, $value );
@@ -2041,8 +1758,8 @@
 		 *
 		 * @since 2.0.0
 		 *
-		 * @param int    $user_id       User ID.
-		 * @param object $old_user_data Object containing user's data prior to update.
+		 * @param int     $user_id       User ID.
+		 * @param WP_User $old_user_data Object containing user's data prior to update.
 		 */
 		do_action( 'profile_update', $user_id, $old_user_data );
 	} else {
@@ -2072,7 +1789,7 @@
  *
  * @see wp_insert_user() For what fields can be set in $userdata.
  *
- * @param mixed $userdata An array of user data or a user object of type stdClass or WP_User.
+ * @param object|WP_User $userdata An array of user data or a user object of type stdClass or WP_User.
  * @return int|WP_Error The updated user's ID or a WP_Error object if the user could not be updated.
  */
 function wp_update_user($userdata) {
@@ -2103,17 +1820,175 @@
 	// Escape data pulled from DB.
 	$user = add_magic_quotes( $user );
 
-	// If password is changing, hash it now.
-	if ( ! empty($userdata['user_pass']) ) {
+	if ( ! empty( $userdata['user_pass'] ) && $userdata['user_pass'] !== $user_obj->user_pass ) {
+		// If password is changing, hash it now
 		$plaintext_pass = $userdata['user_pass'];
-		$userdata['user_pass'] = wp_hash_password($userdata['user_pass']);
+		$userdata['user_pass'] = wp_hash_password( $userdata['user_pass'] );
+
+		/**
+		 * Filters whether to send the password change email.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @see wp_insert_user() For `$user` and `$userdata` fields.
+		 *
+		 * @param bool  $send     Whether to send the email.
+		 * @param array $user     The original user array.
+		 * @param array $userdata The updated user array.
+		 *
+		 */
+		$send_password_change_email = apply_filters( 'send_password_change_email', true, $user, $userdata );
 	}
 
-	wp_cache_delete($user[ 'user_email' ], 'useremail');
+	if ( isset( $userdata['user_email'] ) && $user['user_email'] !== $userdata['user_email'] ) {
+		/**
+		 * Filters whether to send the email change email.
+		 *
+		 * @since 4.3.0
+		 *
+		 * @see wp_insert_user() For `$user` and `$userdata` fields.
+		 *
+		 * @param bool  $send     Whether to send the email.
+		 * @param array $user     The original user array.
+		 * @param array $userdata The updated user array.
+		 *
+		 */
+		$send_email_change_email = apply_filters( 'send_email_change_email', true, $user, $userdata );
+	}
+
+	wp_cache_delete( $user['user_email'], 'useremail' );
+	wp_cache_delete( $user['user_nicename'], 'userslugs' );
 
 	// Merge old and new fields with new fields overwriting old ones.
-	$userdata = array_merge($user, $userdata);
-	$user_id = wp_insert_user($userdata);
+	$userdata = array_merge( $user, $userdata );
+	$user_id = wp_insert_user( $userdata );
+
+	if ( ! is_wp_error( $user_id ) ) {
+
+		$blog_name = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
+
+		$switched_locale = false;
+		if ( ! empty( $send_password_change_email ) || ! empty( $send_email_change_email ) ) {
+			$switched_locale = switch_to_locale( get_user_locale( $user_id ) );
+		}
+
+		if ( ! empty( $send_password_change_email ) ) {
+			/* translators: Do not translate USERNAME, ADMIN_EMAIL, EMAIL, SITENAME, SITEURL: those are placeholders. */
+			$pass_change_text = __( 'Hi ###USERNAME###,
+
+This notice confirms that your password was changed on ###SITENAME###.
+
+If you did not change your password, please contact the Site Administrator at
+###ADMIN_EMAIL###
+
+This email has been sent to ###EMAIL###
+
+Regards,
+All at ###SITENAME###
+###SITEURL###' );
+
+			$pass_change_email = array(
+				'to'      => $user['user_email'],
+				/* translators: User password change notification email subject. 1: Site name */
+				'subject' => __( '[%s] Notice of Password Change' ),
+				'message' => $pass_change_text,
+				'headers' => '',
+			);
+
+			/**
+			 * Filters the contents of the email sent when the user's password is changed.
+			 *
+			 * @since 4.3.0
+			 *
+			 * @param array $pass_change_email {
+			 *            Used to build wp_mail().
+			 *            @type string $to      The intended recipients. Add emails in a comma separated string.
+			 *            @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:
+			 *                - ###USERNAME###    The current user's username.
+			 *                - ###ADMIN_EMAIL### The admin email in case this was unexpected.
+			 *                - ###EMAIL###       The user's email address.
+			 *                - ###SITENAME###    The name of the site.
+			 *                - ###SITEURL###     The URL to the site.
+			 *            @type string $headers Headers. Add headers in a newline (\r\n) separated string.
+			 *        }
+			 * @param array $user     The original user array.
+			 * @param array $userdata The updated user array.
+			 *
+			 */
+			$pass_change_email = apply_filters( 'password_change_email', $pass_change_email, $user, $userdata );
+
+			$pass_change_email['message'] = str_replace( '###USERNAME###', $user['user_login'], $pass_change_email['message'] );
+			$pass_change_email['message'] = str_replace( '###ADMIN_EMAIL###', get_option( 'admin_email' ), $pass_change_email['message'] );
+			$pass_change_email['message'] = str_replace( '###EMAIL###', $user['user_email'], $pass_change_email['message'] );
+			$pass_change_email['message'] = str_replace( '###SITENAME###', $blog_name, $pass_change_email['message'] );
+			$pass_change_email['message'] = str_replace( '###SITEURL###', home_url(), $pass_change_email['message'] );
+
+			wp_mail( $pass_change_email['to'], sprintf( $pass_change_email['subject'], $blog_name ), $pass_change_email['message'], $pass_change_email['headers'] );
+		}
+
+		if ( ! empty( $send_email_change_email ) ) {
+			/* translators: Do not translate USERNAME, ADMIN_EMAIL, NEW_EMAIL, EMAIL, SITENAME, SITEURL: those are placeholders. */
+			$email_change_text = __( 'Hi ###USERNAME###,
+
+This notice confirms that your email address on ###SITENAME### was changed to ###NEW_EMAIL###.
+
+If you did not change your email, please contact the Site Administrator at
+###ADMIN_EMAIL###
+
+This email has been sent to ###EMAIL###
+
+Regards,
+All at ###SITENAME###
+###SITEURL###' );
+
+			$email_change_email = array(
+				'to'      => $user['user_email'],
+				/* translators: User email change notification email subject. 1: Site name */
+				'subject' => __( '[%s] Notice of Email Change' ),
+				'message' => $email_change_text,
+				'headers' => '',
+			);
+
+			/**
+			 * Filters the contents of the email sent when the user's email is changed.
+			 *
+			 * @since 4.3.0
+			 *
+			 * @param array $email_change_email {
+			 *            Used to build wp_mail().
+			 *            @type string $to      The intended recipients.
+			 *            @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:
+			 *                - ###USERNAME###    The current user's username.
+			 *                - ###ADMIN_EMAIL### The admin email in case this was unexpected.
+			 *                - ###NEW_EMAIL###   The new email address.
+			 *                - ###EMAIL###       The old email address.
+			 *                - ###SITENAME###    The name of the site.
+			 *                - ###SITEURL###     The URL to the site.
+			 *            @type string $headers Headers.
+			 *        }
+			 * @param array $user The original user array.
+			 * @param array $userdata The updated user array.
+			 */
+			$email_change_email = apply_filters( 'email_change_email', $email_change_email, $user, $userdata );
+
+			$email_change_email['message'] = str_replace( '###USERNAME###', $user['user_login'], $email_change_email['message'] );
+			$email_change_email['message'] = str_replace( '###ADMIN_EMAIL###', get_option( 'admin_email' ), $email_change_email['message'] );
+			$email_change_email['message'] = str_replace( '###NEW_EMAIL###', $userdata['user_email'], $email_change_email['message'] );
+			$email_change_email['message'] = str_replace( '###EMAIL###', $user['user_email'], $email_change_email['message'] );
+			$email_change_email['message'] = str_replace( '###SITENAME###', $blog_name, $email_change_email['message'] );
+			$email_change_email['message'] = str_replace( '###SITEURL###', home_url(), $email_change_email['message'] );
+
+			wp_mail( $email_change_email['to'], sprintf( $email_change_email['subject'], $blog_name ), $email_change_email['message'], $email_change_email['headers'] );
+		}
+
+		if ( $switched_locale ) {
+			restore_previous_locale();
+		}
+	}
 
 	// Update the cookies if the password changed.
 	$current_user = wp_get_current_user();
@@ -2139,7 +2014,7 @@
  * A simpler way of inserting a user into the database.
  *
  * Creates a new user with just the username, password, and email. For more
- * complex user creation use {@see wp_insert_user()} to specify more information.
+ * complex user creation use wp_insert_user() to specify more information.
  *
  * @since 2.0.0
  * @see wp_insert_user() More complete way to create a new user
@@ -2147,7 +2022,8 @@
  * @param string $username The user's username.
  * @param string $password The user's password.
  * @param string $email    Optional. The user's email. Default empty.
- * @return int The new user's ID.
+ * @return int|WP_Error The newly created user's ID or a WP_Error object if the user could not
+ *                      be created.
  */
 function wp_create_user($username, $password, $email = '') {
 	$user_login = wp_slash( $username );
@@ -2159,16 +2035,19 @@
 }
 
 /**
- * Return a list of meta keys that wp_insert_user() is supposed to set.
+ * Returns a list of meta keys to be (maybe) populated in wp_update_user().
+ *
+ * The list of keys returned via this function are dependent on the presence
+ * of those keys in the user meta data to be set.
  *
  * @since 3.3.0
  * @access private
  *
  * @param WP_User $user WP_User instance.
- * @return array
+ * @return array List of user keys to be populated in wp_update_user().
  */
 function _get_additional_user_keys( $user ) {
-	$keys = array( 'first_name', 'last_name', 'nickname', 'description', 'rich_editing', 'comment_shortcuts', 'admin_color', 'use_ssl', 'show_admin_bar_front' );
+	$keys = array( 'first_name', 'last_name', 'nickname', 'description', 'rich_editing', 'syntax_highlighting', 'comment_shortcuts', 'admin_color', 'use_ssl', 'show_admin_bar_front', 'locale' );
 	return array_merge( $keys, array_keys( wp_get_user_contact_methods( $user ) ) );
 }
 
@@ -2193,7 +2072,7 @@
 	}
 
 	/**
-	 * Filter the user contact methods.
+	 * Filters the user contact methods.
 	 *
 	 * @since 2.9.0
 	 *
@@ -2206,8 +2085,13 @@
 /**
  * The old private function for setting up user contact methods.
  *
+ * Use wp_get_user_contact_methods() instead.
+ *
  * @since 2.9.0
  * @access private
+ *
+ * @param WP_User $user Optional. WP_User object. Default null.
+ * @return array Array of contact methods and their labels.
  */
 function _wp_get_user_contactmethods( $user = null ) {
 	return wp_get_user_contact_methods( $user );
@@ -2221,10 +2105,10 @@
  * @return string The password hint text.
  */
 function wp_get_password_hint() {
-	$hint = __( 'Hint: The password should be at least seven characters long. To make it stronger, use upper and lower case letters, numbers, and symbols like ! " ? $ % ^ &amp; ).' );
+	$hint = __( 'Hint: The password should be at least twelve characters long. To make it stronger, use upper and lower case letters, numbers, and symbols like ! " ? $ % ^ &amp; ).' );
 
 	/**
-	 * Filter the text describing the site's password complexity policy.
+	 * Filters the text describing the site's password complexity policy.
 	 *
 	 * @since 4.1.0
 	 *
@@ -2234,6 +2118,90 @@
 }
 
 /**
+ * Creates, stores, then returns a password reset key for user.
+ *
+ * @since 4.4.0
+ *
+ * @global wpdb         $wpdb      WordPress database abstraction object.
+ * @global PasswordHash $wp_hasher Portable PHP password hashing framework.
+ *
+ * @param WP_User $user User to retrieve password reset key for.
+ *
+ * @return string|WP_Error Password reset key on success. WP_Error on error.
+ */
+function get_password_reset_key( $user ) {
+	global $wpdb, $wp_hasher;
+
+	/**
+	 * Fires before a new password is retrieved.
+	 *
+	 * Use the {@see 'retrieve_password'} hook instead.
+	 *
+	 * @since 1.5.0
+	 * @deprecated 1.5.1 Misspelled. Use 'retrieve_password' hook instead.
+	 *
+	 * @param string $user_login The user login name.
+	 */
+	do_action( 'retreive_password', $user->user_login );
+
+	/**
+	 * Fires before a new password is retrieved.
+	 *
+	 * @since 1.5.1
+	 *
+	 * @param string $user_login The user login name.
+	 */
+	do_action( 'retrieve_password', $user->user_login );
+
+	$allow = true;
+	if ( is_multisite() && is_user_spammy( $user ) ) {
+		$allow = false;
+	}
+
+	/**
+	 * Filters whether to allow a password to be reset.
+	 *
+	 * @since 2.7.0
+	 *
+	 * @param bool $allow         Whether to allow the password to be reset. Default true.
+	 * @param int  $user_data->ID The ID of the user attempting to reset a password.
+	 */
+	$allow = apply_filters( 'allow_password_reset', $allow, $user->ID );
+
+	if ( ! $allow ) {
+		return new WP_Error( 'no_password_reset', __( 'Password reset is not allowed for this user' ) );
+	} elseif ( is_wp_error( $allow ) ) {
+		return $allow;
+	}
+
+	// Generate something random for a password reset key.
+	$key = wp_generate_password( 20, false );
+
+	/**
+	 * Fires when a password reset key is generated.
+	 *
+	 * @since 2.5.0
+	 *
+	 * @param string $user_login The username for the user.
+	 * @param string $key        The generated password reset key.
+	 */
+	do_action( 'retrieve_password_key', $user->user_login, $key );
+
+	// Now insert the key, hashed, into the DB.
+	if ( empty( $wp_hasher ) ) {
+		require_once ABSPATH . WPINC . '/class-phpass.php';
+		$wp_hasher = new PasswordHash( 8, true );
+	}
+	$hashed = time() . ':' . $wp_hasher->HashPassword( $key );
+	$key_saved = $wpdb->update( $wpdb->users, array( 'user_activation_key' => $hashed ), array( 'user_login' => $user->user_login ) );
+	if ( false === $key_saved ) {
+		return new WP_Error( 'no_password_key_update', __( 'Could not save password reset key to database.' ) );
+	}
+
+	return $key;
+}
+
+/**
  * Retrieves a user row based on password reset key and login
  *
  * A key is considered 'expired' if it exactly matches the value of the
@@ -2241,6 +2209,8 @@
  * hashing process. This field is now hashed; old values are no longer accepted
  * but have a different WP_Error code so good user feedback can be provided.
  *
+ * @since 3.1.0
+ *
  * @global wpdb         $wpdb      WordPress database object for queries.
  * @global PasswordHash $wp_hasher Portable PHP password hashing framework instance.
  *
@@ -2268,18 +2238,46 @@
 		$wp_hasher = new PasswordHash( 8, true );
 	}
 
-	if ( $wp_hasher->CheckPassword( $key, $row->user_activation_key ) )
+	/**
+	 * Filters the expiration time of password reset keys.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param int $expiration The expiration time in seconds.
+	 */
+	$expiration_duration = apply_filters( 'password_reset_expiration', DAY_IN_SECONDS );
+
+	if ( false !== strpos( $row->user_activation_key, ':' ) ) {
+		list( $pass_request_time, $pass_key ) = explode( ':', $row->user_activation_key, 2 );
+		$expiration_time = $pass_request_time + $expiration_duration;
+	} else {
+		$pass_key = $row->user_activation_key;
+		$expiration_time = false;
+	}
+
+	if ( ! $pass_key ) {
+		return new WP_Error( 'invalid_key', __( 'Invalid key' ) );
+	}
+
+	$hash_is_correct = $wp_hasher->CheckPassword( $key, $pass_key );
+
+	if ( $hash_is_correct && $expiration_time && time() < $expiration_time ) {
 		return get_userdata( $row->ID );
-
-	if ( $key === $row->user_activation_key ) {
+	} elseif ( $hash_is_correct && $expiration_time ) {
+		// Key has an expiration time that's passed
+		return new WP_Error( 'expired_key', __( 'Invalid key' ) );
+	}
+
+	if ( hash_equals( $row->user_activation_key, $key ) || ( $hash_is_correct && ! $expiration_time ) ) {
 		$return = new WP_Error( 'expired_key', __( 'Invalid key' ) );
 		$user_id = $row->ID;
 
 		/**
-		 * Filter the return value of check_password_reset_key() when an
-		 * old-style key is used (plain-text key was stored in the database).
+		 * Filters the return value of check_password_reset_key() when an
+		 * old-style key is used.
 		 *
-		 * @since 3.7.0
+		 * @since 3.7.0 Previously plain-text keys were stored in the database.
+		 * @since 4.3.0 Previously key hashes were stored without an expiration time.
 		 *
 		 * @param WP_Error $return  A WP_Error object denoting an expired key.
 		 *                          Return a WP_User object to validate the key.
@@ -2294,7 +2292,9 @@
 /**
  * Handles resetting the user's password.
  *
- * @param object $user The user
+ * @since 2.5.0
+ *
+ * @param WP_User $user     The user
  * @param string $new_pass New password for the user in plaintext
  */
 function reset_password( $user, $new_pass ) {
@@ -2311,12 +2311,22 @@
 	wp_set_password( $new_pass, $user->ID );
 	update_user_option( $user->ID, 'default_password_nag', false, true );
 
-	wp_password_change_notification( $user );
+	/**
+	 * Fires after the user's password is reset.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param WP_User $user     The user.
+	 * @param string  $new_pass New user password.
+	 */
+	do_action( 'after_password_reset', $user, $new_pass );
 }
 
 /**
  * Handles registering a new user.
  *
+ * @since 2.5.0
+ *
  * @param string $user_login User's username for logging in
  * @param string $user_email User's email address to send password and add
  * @return int|WP_Error Either user's ID or error on failure.
@@ -2326,7 +2336,7 @@
 
 	$sanitized_user_login = sanitize_user( $user_login );
 	/**
-	 * Filter the email address of a user being registered.
+	 * Filters the email address of a user being registered.
 	 *
 	 * @since 2.1.0
 	 *
@@ -2342,11 +2352,18 @@
 		$sanitized_user_login = '';
 	} elseif ( username_exists( $sanitized_user_login ) ) {
 		$errors->add( 'username_exists', __( '<strong>ERROR</strong>: This username is already registered. Please choose another one.' ) );
+
+	} else {
+		/** This filter is documented in wp-includes/user.php */
+		$illegal_user_logins = array_map( 'strtolower', (array) apply_filters( 'illegal_user_logins', array() ) );
+		if ( in_array( strtolower( $sanitized_user_login ), $illegal_user_logins ) ) {
+			$errors->add( 'invalid_username', __( '<strong>ERROR</strong>: Sorry, that username is not allowed.' ) );
+		}
 	}
 
-	// Check the e-mail address
+	// Check the email address
 	if ( $user_email == '' ) {
-		$errors->add( 'empty_email', __( '<strong>ERROR</strong>: Please type your e-mail address.' ) );
+		$errors->add( 'empty_email', __( '<strong>ERROR</strong>: Please type your email address.' ) );
 	} elseif ( ! is_email( $user_email ) ) {
 		$errors->add( 'invalid_email', __( '<strong>ERROR</strong>: The email address isn&#8217;t correct.' ) );
 		$user_email = '';
@@ -2368,7 +2385,7 @@
 	do_action( 'register_post', $sanitized_user_login, $user_email, $errors );
 
 	/**
-	 * Filter the errors encountered when a new user is being registered.
+	 * Filters the errors encountered when a new user is being registered.
 	 *
 	 * The filtered WP_Error object may, for example, contain errors for an invalid
 	 * or existing username or email address. A WP_Error object should always returned,
@@ -2397,12 +2414,37 @@
 
 	update_user_option( $user_id, 'default_password_nag', true, true ); //Set up the Password change nag.
 
-	wp_new_user_notification( $user_id, $user_pass );
+	/**
+	 * Fires after a new user registration has been recorded.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param int $user_id ID of the newly registered user.
+	 */
+	do_action( 'register_new_user', $user_id );
 
 	return $user_id;
 }
 
 /**
+ * Initiates email notifications related to the creation of new users.
+ *
+ * Notifications are sent both to the site admin and to the newly created user.
+ *
+ * @since 4.4.0
+ * @since 4.6.0 Converted the `$notify` parameter to accept 'user' for sending
+ *              notifications only to the user created.
+ *
+ * @param int    $user_id ID of the newly created user.
+ * @param string $notify  Optional. Type of notification that should happen. Accepts 'admin'
+ *                        or an empty string (admin only), 'user', or 'both' (admin and user).
+ *                        Default 'both'.
+ */
+function wp_send_new_user_notifications( $user_id, $notify = 'both' ) {
+	wp_new_user_notification( $user_id, null, $notify );
+}
+
+/**
  * Retrieve the current session token from the logged_in cookie.
  *
  * @since 4.0.0
@@ -2460,3 +2502,1101 @@
 	$manager = WP_Session_Tokens::get_instance( get_current_user_id() );
 	$manager->destroy_all();
 }
+
+/**
+ * Get the user IDs of all users with no role on this site.
+ *
+ * @since 4.4.0
+ * @since 4.9.0 The `$site_id` parameter was added to support multisite.
+ *
+ * @param int|null $site_id Optional. The site ID to get users with no role for. Defaults to the current site.
+ * @return array Array of user IDs.
+ */
+function wp_get_users_with_no_role( $site_id = null ) {
+	global $wpdb;
+
+	if ( ! $site_id ) {
+		$site_id = get_current_blog_id();
+	}
+
+	$prefix = $wpdb->get_blog_prefix( $site_id );
+
+	if ( is_multisite() && $site_id != get_current_blog_id() ) {
+		switch_to_blog( $site_id );
+		$role_names = wp_roles()->get_names();
+		restore_current_blog();
+	} else {
+		$role_names = wp_roles()->get_names();
+	}
+
+	$regex  = implode( '|', array_keys( $role_names ) );
+	$regex  = preg_replace( '/[^a-zA-Z_\|-]/', '', $regex );
+	$users  = $wpdb->get_col( $wpdb->prepare( "
+		SELECT user_id
+		FROM $wpdb->usermeta
+		WHERE meta_key = '{$prefix}capabilities'
+		AND meta_value NOT REGEXP %s
+	", $regex ) );
+
+	return $users;
+}
+
+/**
+ * Retrieves the current user object.
+ *
+ * Will set the current user, if the current user is not set. The current user
+ * will be set to the logged-in person. If no user is logged-in, then it will
+ * set the current user to 0, which is invalid and won't have any permissions.
+ *
+ * This function is used by the pluggable functions wp_get_current_user() and
+ * get_currentuserinfo(), the latter of which is deprecated but used for backward
+ * compatibility.
+ *
+ * @since 4.5.0
+ * @access private
+ *
+ * @see wp_get_current_user()
+ * @global WP_User $current_user Checks if the current user is set.
+ *
+ * @return WP_User Current WP_User instance.
+ */
+function _wp_get_current_user() {
+	global $current_user;
+
+	if ( ! empty( $current_user ) ) {
+		if ( $current_user instanceof WP_User ) {
+			return $current_user;
+		}
+
+		// Upgrade stdClass to WP_User
+		if ( is_object( $current_user ) && isset( $current_user->ID ) ) {
+			$cur_id = $current_user->ID;
+			$current_user = null;
+			wp_set_current_user( $cur_id );
+			return $current_user;
+		}
+
+		// $current_user has a junk value. Force to WP_User with ID 0.
+		$current_user = null;
+		wp_set_current_user( 0 );
+		return $current_user;
+	}
+
+	if ( defined('XMLRPC_REQUEST') && XMLRPC_REQUEST ) {
+		wp_set_current_user( 0 );
+		return $current_user;
+	}
+
+	/**
+	 * Filters the current user.
+	 *
+	 * The default filters use this to determine the current user from the
+	 * request's cookies, if available.
+	 *
+	 * Returning a value of false will effectively short-circuit setting
+	 * the current user.
+	 *
+	 * @since 3.9.0
+	 *
+	 * @param int|bool $user_id User ID if one has been determined, false otherwise.
+	 */
+	$user_id = apply_filters( 'determine_current_user', false );
+	if ( ! $user_id ) {
+		wp_set_current_user( 0 );
+		return $current_user;
+	}
+
+	wp_set_current_user( $user_id );
+
+	return $current_user;
+}
+
+/**
+ * Send a confirmation request email when a change of user email address is attempted.
+ *
+ * @since 3.0.0
+ * @since 4.9.0 This function was moved from wp-admin/includes/ms.php so it's no longer Multisite specific.
+ *
+ * @global WP_Error $errors WP_Error object.
+ * @global wpdb     $wpdb   WordPress database object.
+ */
+function send_confirmation_on_profile_email() {
+	global $errors, $wpdb;
+
+	$current_user = wp_get_current_user();
+	if ( ! is_object( $errors ) ) {
+		$errors = new WP_Error();
+	}
+
+	if ( $current_user->ID != $_POST['user_id'] ) {
+		return false;
+	}
+
+	if ( $current_user->user_email != $_POST['email'] ) {
+		if ( ! is_email( $_POST['email'] ) ) {
+			$errors->add( 'user_email', __( "<strong>ERROR</strong>: The email address isn&#8217;t correct." ), array(
+				'form-field' => 'email',
+			) );
+
+			return;
+		}
+
+		if ( $wpdb->get_var( $wpdb->prepare( "SELECT user_email FROM {$wpdb->users} WHERE user_email=%s", $_POST['email'] ) ) ) {
+			$errors->add( 'user_email', __( "<strong>ERROR</strong>: The email address is already used." ), array(
+				'form-field' => 'email',
+			) );
+			delete_user_meta( $current_user->ID, '_new_email' );
+
+			return;
+		}
+
+		$hash           = md5( $_POST['email'] . time() . wp_rand() );
+		$new_user_email = array(
+			'hash'     => $hash,
+			'newemail' => $_POST['email'],
+		);
+		update_user_meta( $current_user->ID, '_new_email', $new_user_email );
+
+		$sitename = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
+
+		/* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
+		$email_text = __( 'Howdy ###USERNAME###,
+
+You recently requested to have the email address on your account 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###' );
+
+		/**
+		 * Filters the text of the email sent when a change of user email address is attempted.
+		 *
+		 * The following strings have a special meaning and will get replaced dynamically:
+		 * ###USERNAME###  The current user's username.
+		 * ###ADMIN_URL### The link to click on to confirm the email change.
+		 * ###EMAIL###     The new email.
+		 * ###SITENAME###  The name of the site.
+		 * ###SITEURL###   The URL to the site.
+		 *
+		 * @since MU (3.0.0)
+		 * @since 4.9.0 This filter is no longer Multisite specific.
+		 *
+		 * @param string $email_text     Text in the email.
+		 * @param array  $new_user_email {
+		 *     Data relating to the new user email address.
+		 *
+		 *     @type string $hash     The secure hash used in the confirmation link URL.
+		 *     @type string $newemail The proposed new email address.
+		 * }
+		 */
+		$content = apply_filters( 'new_user_email_content', $email_text, $new_user_email );
+
+		$content = str_replace( '###USERNAME###', $current_user->user_login, $content );
+		$content = str_replace( '###ADMIN_URL###', esc_url( admin_url( 'profile.php?newuseremail=' . $hash ) ), $content );
+		$content = str_replace( '###EMAIL###', $_POST['email'], $content );
+		$content = str_replace( '###SITENAME###', $sitename, $content );
+		$content = str_replace( '###SITEURL###', home_url(), $content );
+
+		wp_mail( $_POST['email'], sprintf( __( '[%s] New Email Address' ), $sitename ), $content );
+
+		$_POST['email'] = $current_user->user_email;
+	}
+}
+
+/**
+ * Adds an admin notice alerting the user to check for confirmation request email
+ * after email address change.
+ *
+ * @since 3.0.0
+ * @since 4.9.0 This function was moved from wp-admin/includes/ms.php so it's no longer Multisite specific.
+ *
+ * @global string $pagenow
+ */
+function new_user_email_admin_notice() {
+	global $pagenow;
+	if ( 'profile.php' === $pagenow && isset( $_GET['updated'] ) && $email = get_user_meta( get_current_user_id(), '_new_email', true ) ) {
+		/* translators: %s: New email address */
+		echo '<div class="notice notice-info"><p>' . sprintf( __( 'Your email address has not been updated yet. Please check your inbox at %s for a confirmation email.' ), '<code>' . esc_html( $email['newemail'] ) . '</code>' ) . '</p></div>';
+	}
+}
+
+/**
+ * Get all user privacy request types.
+ *
+ * @since 4.9.6
+ * @access private
+ *
+ * @return array List of core privacy action types.
+ */
+function _wp_privacy_action_request_types() {
+	return array(
+		'export_personal_data',
+		'remove_personal_data',
+	);
+}
+
+/**
+ * Registers the personal data exporter for users.
+ *
+ * @since 4.9.6
+ *
+ * @param array $exporters  An array of personal data exporters.
+ * @return array An array of personal data exporters.
+ */
+function wp_register_user_personal_data_exporter( $exporters ) {
+	$exporters['wordpress-user'] = array(
+		'exporter_friendly_name' => __( 'WordPress User' ),
+		'callback'               => 'wp_user_personal_data_exporter',
+	);
+
+	return $exporters;
+}
+
+/**
+ * Finds and exports personal data associated with an email address from the user and user_meta table.
+ *
+ * @since 4.9.6
+ *
+ * @param string $email_address  The users email address.
+ * @return array An array of personal data.
+ */
+function wp_user_personal_data_exporter( $email_address ) {
+	$email_address = trim( $email_address );
+
+	$data_to_export = array();
+
+	$user = get_user_by( 'email', $email_address );
+
+	if ( ! $user ) {
+		return array(
+			'data' => array(),
+			'done' => true,
+		);
+	}
+
+	$user_meta = get_user_meta( $user->ID );
+
+	$user_prop_to_export = array(
+		'ID'              => __( 'User ID' ),
+		'user_login'      => __( 'User Login Name' ),
+		'user_nicename'   => __( 'User Nice Name' ),
+		'user_email'      => __( 'User Email' ),
+		'user_url'        => __( 'User URL' ),
+		'user_registered' => __( 'User Registration Date' ),
+		'display_name'    => __( 'User Display Name' ),
+		'nickname'        => __( 'User Nickname' ),
+		'first_name'      => __( 'User First Name' ),
+		'last_name'       => __( 'User Last Name' ),
+		'description'     => __( 'User Description' ),
+	);
+
+	$user_data_to_export = array();
+
+	foreach ( $user_prop_to_export as $key => $name ) {
+		$value = '';
+
+		switch ( $key ) {
+			case 'ID':
+			case 'user_login':
+			case 'user_nicename':
+			case 'user_email':
+			case 'user_url':
+			case 'user_registered':
+			case 'display_name':
+				$value = $user->data->$key;
+				break;
+			case 'nickname':
+			case 'first_name':
+			case 'last_name':
+			case 'description':
+				$value = $user_meta[ $key ][0];
+				break;
+		}
+
+		if ( ! empty( $value ) ) {
+			$user_data_to_export[] = array(
+				'name'  => $name,
+				'value' => $value,
+			);
+		}
+	}
+
+	$data_to_export[] = array(
+		'group_id'    => 'user',
+		'group_label' => __( 'User' ),
+		'item_id'     => "user-{$user->ID}",
+		'data'        => $user_data_to_export,
+	);
+
+	return array(
+		'data' => $data_to_export,
+		'done' => true,
+	);
+}
+
+/**
+ * Update log when privacy request is confirmed.
+ *
+ * @since 4.9.6
+ * @access private
+ *
+ * @param int $request_id ID of the request.
+ */
+function _wp_privacy_account_request_confirmed( $request_id ) {
+	$request_data = wp_get_user_request_data( $request_id );
+
+	if ( ! $request_data ) {
+		return;
+	}
+
+	if ( ! in_array( $request_data->status, array( 'request-pending', 'request-failed' ), true ) ) {
+		return;
+	}
+
+	update_post_meta( $request_id, '_wp_user_request_confirmed_timestamp', time() );
+	wp_update_post( array(
+		'ID'          => $request_id,
+		'post_status' => 'request-confirmed',
+	) );
+}
+
+/**
+ * Notify the site administrator via email when a request is confirmed.
+ *
+ * Without this, the admin would have to manually check the site to see if any
+ * action was needed on their part yet.
+ *
+ * @since 4.9.6
+ *
+ * @param int $request_id The ID of the request.
+ */
+function _wp_privacy_send_request_confirmation_notification( $request_id ) {
+	$request_data = wp_get_user_request_data( $request_id );
+
+	if ( ! is_a( $request_data, 'WP_User_Request' ) || 'request-confirmed' !== $request_data->status ) {
+		return;
+	}
+
+	$already_notified = (bool) get_post_meta( $request_id, '_wp_admin_notified', true );
+
+	if ( $already_notified ) {
+		return;
+	}
+
+	$manage_url         = add_query_arg( 'page', $request_data->action_name, admin_url( 'tools.php' ) );
+	$action_description = wp_user_request_action_description( $request_data->action_name );
+
+	/**
+	 * Filters the recipient of the data request confirmation notification.
+	 *
+	 * In a Multisite environment, this will default to the email address of the
+	 * network admin because, by default, single site admins do not have the
+	 * capabilities required to process requests. Some networks may wish to
+	 * delegate those capabilities to a single-site admin, or a dedicated person
+	 * responsible for managing privacy requests.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string          $admin_email  The email address of the notification recipient.
+	 * @param WP_User_Request $request_data The request that is initiating the notification.
+	 */
+	$admin_email = apply_filters( 'user_request_confirmed_email_to', get_site_option( 'admin_email' ), $request_data );
+
+	$email_data = array(
+		'request'     => $request_data,
+		'user_email'  => $request_data->email,
+		'description' => $action_description,
+		'manage_url'  => $manage_url,
+		'sitename'    => wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES ),
+		'siteurl'     => home_url(),
+		'admin_email' => $admin_email,
+	);
+
+	/* translators: Do not translate SITENAME, USER_EMAIL, DESCRIPTION, MANAGE_URL, SITEURL; those are placeholders. */
+	$email_text = __(
+		'Howdy,
+
+A user data privacy request has been confirmed on ###SITENAME###:
+
+User: ###USER_EMAIL###
+Request: ###DESCRIPTION###
+
+You can view and manage these data privacy requests here:
+
+###MANAGE_URL###
+
+Regards,
+All at ###SITENAME###
+###SITEURL###'
+	);
+
+	/**
+	 * Filters the body of the user request confirmation email.
+	 *
+	 * The email is sent to an administrator when an user request is confirmed.
+	 * The following strings have a special meaning and will get replaced dynamically:
+	 *
+	 * ###SITENAME###    The name of the site.
+	 * ###USER_EMAIL###  The user email for the request.
+	 * ###DESCRIPTION### Description of the action being performed so the user knows what the email is for.
+	 * ###MANAGE_URL###  The URL to manage requests.
+	 * ###SITEURL###     The URL to the site.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $email_text Text in the email.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request     User request object.
+	 *     @type string          $user_email  The email address confirming a request
+	 *     @type string          $description Description of the action being performed so the user knows what the email is for.
+	 *     @type string          $manage_url  The link to click manage privacy requests of this type.
+	 *     @type string          $sitename    The site name sending the mail.
+	 *     @type string          $siteurl     The site URL sending the mail.
+	 *     @type string          $admin_email The administrator email receiving the mail.
+	 * }
+	 */
+	$content = apply_filters( 'user_confirmed_action_email_content', $email_text, $email_data );
+
+	$content = str_replace( '###SITENAME###', $email_data['sitename'], $content );
+	$content = str_replace( '###USER_EMAIL###', $email_data['user_email'], $content );
+	$content = str_replace( '###DESCRIPTION###', $email_data['description'], $content );
+	$content = str_replace( '###MANAGE_URL###', esc_url_raw( $email_data['manage_url'] ), $content );
+	$content = str_replace( '###SITEURL###', esc_url_raw( $email_data['siteurl'] ), $content );
+
+	$subject = sprintf(
+		/* translators: 1: Site name. 2: Name of the confirmed action. */
+		__( '[%1$s] Action Confirmed: %2$s' ),
+		$email_data['sitename'],
+		$action_description
+	);
+
+	/**
+	 * Filters the subject of the user request confirmation email.
+	 *
+	 * @since 4.9.8
+	 *
+	 * @param string $subject    The email subject.
+	 * @param string $sitename   The name of the site.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request     User request object.
+	 *     @type string          $user_email  The email address confirming a request
+	 *     @type string          $description Description of the action being performed so the user knows what the email is for.
+	 *     @type string          $manage_url  The link to click manage privacy requests of this type.
+	 *     @type string          $sitename    The site name sending the mail.
+	 *     @type string          $siteurl     The site URL sending the mail.
+	 *     @type string          $admin_email The administrator email receiving the mail.
+	 * }
+	 */
+	$subject = apply_filters( 'user_request_confirmed_email_subject', $subject, $email_data['sitename'], $email_data );
+
+	$email_sent = wp_mail( $email_data['admin_email'], $subject, $content );
+
+	if ( $email_sent ) {
+		update_post_meta( $request_id, '_wp_admin_notified', true );
+	}
+}
+
+/**
+ * Notify the user when their erasure request is fulfilled.
+ *
+ * Without this, the user would never know if their data was actually erased.
+ *
+ * @since 4.9.6
+ *
+ * @param int $request_id The privacy request post ID associated with this request.
+ */
+function _wp_privacy_send_erasure_fulfillment_notification( $request_id ) {
+	$request_data = wp_get_user_request_data( $request_id );
+
+	if ( ! is_a( $request_data, 'WP_User_Request' ) || 'request-completed' !== $request_data->status ) {
+		return;
+	}
+
+	$already_notified = (bool) get_post_meta( $request_id, '_wp_user_notified', true );
+
+	if ( $already_notified ) {
+		return;
+	}
+
+	/**
+	 * Filters the recipient of the data erasure fulfillment notification.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string          $user_email   The email address of the notification recipient.
+	 * @param WP_User_Request $request_data The request that is initiating the notification.
+	 */
+	$user_email = apply_filters( 'user_erasure_fulfillment_email_to', $request_data->email, $request_data );
+
+	$email_data = array(
+		'request'            => $request_data,
+		'message_recipient'  => $user_email,
+		'privacy_policy_url' => get_privacy_policy_url(),
+		'sitename'           => wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES ),
+		'siteurl'            => home_url(),
+	);
+
+	$subject  = sprintf(
+		/* translators: %s: Site name. */
+		__( '[%s] Erasure Request Fulfilled' ),
+		$email_data['sitename']
+	);
+
+	/**
+	 * Filters the subject of the email sent when an erasure request is completed.
+	 *
+	 * @since 4.9.8
+	 *
+	 * @param string $subject    The email subject.
+	 * @param string $sitename   The name of the site.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request            User request object.
+	 *     @type string          $message_recipient  The address that the email will be sent to. Defaults
+	 *                                               to the value of `$request->email`, but can be changed
+	 *                                               by the `user_erasure_fulfillment_email_to` filter.
+	 *     @type string          $privacy_policy_url Privacy policy URL.
+	 *     @type string          $sitename           The site name sending the mail.
+	 *     @type string          $siteurl            The site URL sending the mail.
+	 * }
+	 */
+	$subject = apply_filters( 'user_erasure_complete_email_subject', $subject, $email_data['sitename'], $email_data );
+
+	if ( empty( $email_data['privacy_policy_url'] ) ) {
+		/* translators: Do not translate SITENAME, SITEURL; those are placeholders. */
+		$email_text = __(
+			'Howdy,
+
+Your request to erase your personal data on ###SITENAME### has been completed.
+
+If you have any follow-up questions or concerns, please contact the site administrator.
+
+Regards,
+All at ###SITENAME###
+###SITEURL###'
+		);
+	} else {
+		/* translators: Do not translate SITENAME, SITEURL, PRIVACY_POLICY_URL; those are placeholders. */
+		$email_text = __(
+			'Howdy,
+
+Your request to erase your personal data on ###SITENAME### has been completed.
+
+If you have any follow-up questions or concerns, please contact the site administrator.
+
+For more information, you can also read our privacy policy: ###PRIVACY_POLICY_URL###
+
+Regards,
+All at ###SITENAME###
+###SITEURL###'
+		);
+	}
+
+	/**
+	 * Filters the body of the data erasure fulfillment notification.
+	 *
+	 * The email is sent to a user when a their data erasure request is fulfilled
+	 * by an administrator.
+	 *
+	 * The following strings have a special meaning and will get replaced dynamically:
+	 *
+	 * ###SITENAME###           The name of the site.
+	 * ###PRIVACY_POLICY_URL### Privacy policy page URL.
+	 * ###SITEURL###            The URL to the site.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $email_text Text in the email.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request            User request object.
+	 *     @type string          $message_recipient  The address that the email will be sent to. Defaults
+	 *                                               to the value of `$request->email`, but can be changed
+	 *                                               by the `user_erasure_fulfillment_email_to` filter.
+	 *     @type string          $privacy_policy_url Privacy policy URL.
+	 *     @type string          $sitename           The site name sending the mail.
+	 *     @type string          $siteurl            The site URL sending the mail.
+	 * }
+	 */
+	$content = apply_filters( 'user_confirmed_action_email_content', $email_text, $email_data );
+
+	$content = str_replace( '###SITENAME###', $email_data['sitename'], $content );
+	$content = str_replace( '###PRIVACY_POLICY_URL###', $email_data['privacy_policy_url'], $content );
+	$content = str_replace( '###SITEURL###', esc_url_raw( $email_data['siteurl'] ), $content );
+
+	$email_sent = wp_mail( $user_email, $subject, $content );
+
+	if ( $email_sent ) {
+		update_post_meta( $request_id, '_wp_user_notified', true );
+	}
+}
+
+/**
+ * Return request confirmation message HTML.
+ *
+ * @since 4.9.6
+ * @access private
+ *
+ * @param int $request_id The request ID being confirmed.
+ * @return string $message The confirmation message.
+ */
+function _wp_privacy_account_request_confirmed_message( $request_id ) {
+	$request = wp_get_user_request_data( $request_id );
+
+	$message = '<p class="success">' . __( 'Action has been confirmed.' ) . '</p>';
+	$message .= '<p>' . __( 'The site administrator has been notified and will fulfill your request as soon as possible.' ) . '</p>';
+
+	if ( $request && in_array( $request->action_name, _wp_privacy_action_request_types(), true ) ) {
+		if ( 'export_personal_data' === $request->action_name ) {
+			$message = '<p class="success">' . __( 'Thanks for confirming your export request.' ) . '</p>';
+			$message .= '<p>' . __( 'The site administrator has been notified. You will receive a link to download your export via email when they fulfill your request.' ) . '</p>';
+		} elseif ( 'remove_personal_data' === $request->action_name ) {
+			$message = '<p class="success">' . __( 'Thanks for confirming your erasure request.' ) . '</p>';
+			$message .= '<p>' . __( 'The site administrator has been notified. You will receive an email confirmation when they erase your data.' ) . '</p>';
+		}
+	}
+
+	/**
+	 * Filters the message displayed to a user when they confirm a data request.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $message    The message to the user.
+	 * @param int    $request_id The ID of the request being confirmed.
+	 */
+	$message = apply_filters( 'user_request_action_confirmed_message', $message, $request_id );
+
+	return $message;
+}
+
+/**
+ * Create and log a user request to perform a specific action.
+ *
+ * Requests are stored inside a post type named `user_request` since they can apply to both
+ * users on the site, or guests without a user account.
+ *
+ * @since 4.9.6
+ *
+ * @param string $email_address User email address. This can be the address of a registered or non-registered user.
+ * @param string $action_name   Name of the action that is being confirmed. Required.
+ * @param array  $request_data  Misc data you want to send with the verification request and pass to the actions once the request is confirmed.
+ * @return int|WP_Error Returns the request ID if successful, or a WP_Error object on failure.
+ */
+function wp_create_user_request( $email_address = '', $action_name = '', $request_data = array() ) {
+	$email_address = sanitize_email( $email_address );
+	$action_name   = sanitize_key( $action_name );
+
+	if ( ! is_email( $email_address ) ) {
+		return new WP_Error( 'invalid_email', __( 'Invalid email address.' ) );
+	}
+
+	if ( ! $action_name ) {
+		return new WP_Error( 'invalid_action', __( 'Invalid action name.' ) );
+	}
+
+	$user    = get_user_by( 'email', $email_address );
+	$user_id = $user && ! is_wp_error( $user ) ? $user->ID : 0;
+
+	// Check for duplicates.
+	$requests_query = new WP_Query( array(
+		'post_type'     => 'user_request',
+		'post_name__in' => array( $action_name ),  // Action name stored in post_name column.
+		'title'         => $email_address, // Email address stored in post_title column.
+		'post_status'   => 'any',
+		'fields'        => 'ids',
+	) );
+
+	if ( $requests_query->found_posts ) {
+		return new WP_Error( 'duplicate_request', __( 'A request for this email address already exists.' ) );
+	}
+
+	$request_id = wp_insert_post( array(
+		'post_author'   => $user_id,
+		'post_name'     => $action_name,
+		'post_title'    => $email_address,
+		'post_content'  => wp_json_encode( $request_data ),
+		'post_status'   => 'request-pending',
+		'post_type'     => 'user_request',
+		'post_date'     => current_time( 'mysql', false ),
+		'post_date_gmt' => current_time( 'mysql', true ),
+	), true );
+
+	return $request_id;
+}
+
+/**
+ * Get action description from the name and return a string.
+ *
+ * @since 4.9.6
+ *
+ * @param string $action_name Action name of the request.
+ * @return string Human readable action name.
+ */
+function wp_user_request_action_description( $action_name ) {
+	switch ( $action_name ) {
+		case 'export_personal_data':
+			$description = __( 'Export Personal Data' );
+			break;
+		case 'remove_personal_data':
+			$description = __( 'Erase Personal Data' );
+			break;
+		default:
+			/* translators: %s: action name */
+			$description = sprintf( __( 'Confirm the "%s" action' ), $action_name );
+			break;
+	}
+
+	/**
+	 * Filters the user action description.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $description The default description.
+	 * @param string $action_name The name of the request.
+	 */
+	return apply_filters( 'user_request_action_description', $description, $action_name );
+}
+
+/**
+ * Send a confirmation request email to confirm an action.
+ *
+ * If the request is not already pending, it will be updated.
+ *
+ * @since 4.9.6
+ *
+ * @param string $request_id ID of the request created via wp_create_user_request().
+ * @return WP_Error|bool Will return true/false based on the success of sending the email, or a WP_Error object.
+ */
+function wp_send_user_request( $request_id ) {
+	$request_id = absint( $request_id );
+	$request    = wp_get_user_request_data( $request_id );
+
+	if ( ! $request ) {
+		return new WP_Error( 'user_request_error', __( 'Invalid request.' ) );
+	}
+
+	$email_data = array(
+		'request'     => $request,
+		'email'       => $request->email,
+		'description' => wp_user_request_action_description( $request->action_name ),
+		'confirm_url' => add_query_arg( array(
+			'action'      => 'confirmaction',
+			'request_id'  => $request_id,
+			'confirm_key' => wp_generate_user_request_key( $request_id ),
+		), wp_login_url() ),
+		'sitename'    => wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES ),
+		'siteurl'     => home_url(),
+	);
+
+	/* translators: Do not translate DESCRIPTION, CONFIRM_URL, SITENAME, SITEURL: those are placeholders. */
+	$email_text = __(
+		'Howdy,
+
+A request has been made to perform the following action on your account:
+
+     ###DESCRIPTION###
+
+To confirm this, please click on the following link:
+###CONFIRM_URL###
+
+You can safely ignore and delete this email if you do not want to
+take this action.
+
+Regards,
+All at ###SITENAME###
+###SITEURL###'
+	);
+
+	/**
+	 * Filters the text of the email sent when an account action is attempted.
+	 *
+	 * The following strings have a special meaning and will get replaced dynamically:
+	 *
+	 * ###DESCRIPTION### Description of the action being performed so the user knows what the email is for.
+	 * ###CONFIRM_URL### The link to click on to confirm the account action.
+	 * ###SITENAME###    The name of the site.
+	 * ###SITEURL###     The URL to the site.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $email_text Text in the email.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request     User request object.
+	 *     @type string          $email       The email address this is being sent to.
+	 *     @type string          $description Description of the action being performed so the user knows what the email is for.
+	 *     @type string          $confirm_url The link to click on to confirm the account action.
+	 *     @type string          $sitename    The site name sending the mail.
+	 *     @type string          $siteurl     The site URL sending the mail.
+	 * }
+	 */
+	$content = apply_filters( 'user_request_action_email_content', $email_text, $email_data );
+
+	$content = str_replace( '###DESCRIPTION###', $email_data['description'], $content );
+	$content = str_replace( '###CONFIRM_URL###', esc_url_raw( $email_data['confirm_url'] ), $content );
+	$content = str_replace( '###EMAIL###', $email_data['email'], $content );
+	$content = str_replace( '###SITENAME###', $email_data['sitename'], $content );
+	$content = str_replace( '###SITEURL###', esc_url_raw( $email_data['siteurl'] ), $content );
+
+	/* translators: Privacy data request subject. 1: Site name, 2: Name of the action */
+	$subject = sprintf( __( '[%1$s] Confirm Action: %2$s' ), $email_data['sitename'], $email_data['description'] );
+
+	/**
+	 * Filters the subject of the email sent when an account action is attempted.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param string $subject    The email subject.
+	 * @param string $sitename   The name of the site.
+	 * @param array  $email_data {
+	 *     Data relating to the account action email.
+	 *
+	 *     @type WP_User_Request $request     User request object.
+	 *     @type string          $email       The email address this is being sent to.
+	 *     @type string          $description Description of the action being performed so the user knows what the email is for.
+	 *     @type string          $confirm_url The link to click on to confirm the account action.
+	 *     @type string          $sitename    The site name sending the mail.
+	 *     @type string          $siteurl     The site URL sending the mail.
+	 * }
+	 */
+	$subject = apply_filters( 'user_request_action_email_subject', $subject, $email_data['sitename'], $email_data );
+
+	return wp_mail( $email_data['email'], $subject, $content );
+}
+
+/**
+ * Returns a confirmation key for a user action and stores the hashed version for future comparison.
+ *
+ * @since 4.9.6
+ *
+ * @param int $request_id Request ID.
+ * @return string Confirmation key.
+ */
+function wp_generate_user_request_key( $request_id ) {
+	global $wp_hasher;
+
+	// Generate something random for a confirmation key.
+	$key = wp_generate_password( 20, false );
+
+	// Return the key, hashed.
+	if ( empty( $wp_hasher ) ) {
+		require_once ABSPATH . WPINC . '/class-phpass.php';
+		$wp_hasher = new PasswordHash( 8, true );
+	}
+
+	wp_update_post( array(
+		'ID'                => $request_id,
+		'post_status'       => 'request-pending',
+		'post_password'     => $wp_hasher->HashPassword( $key ),
+		'post_modified'     => current_time( 'mysql', false ),
+		'post_modified_gmt' => current_time( 'mysql', true ),
+	) );
+
+	return $key;
+}
+
+/**
+ * Validate a user request by comparing the key with the request's key.
+ *
+ * @since 4.9.6
+ *
+ * @param string $request_id ID of the request being confirmed.
+ * @param string $key        Provided key to validate.
+ * @return bool|WP_Error WP_Error on failure, true on success.
+ */
+function wp_validate_user_request_key( $request_id, $key ) {
+	global $wp_hasher;
+
+	$request_id = absint( $request_id );
+	$request    = wp_get_user_request_data( $request_id );
+
+	if ( ! $request ) {
+		return new WP_Error( 'user_request_error', __( 'Invalid request.' ) );
+	}
+
+	if ( ! in_array( $request->status, array( 'request-pending', 'request-failed' ), true ) ) {
+		return __( 'This link has expired.' );
+	}
+
+	if ( empty( $key ) ) {
+		return new WP_Error( 'invalid_key', __( 'Invalid key' ) );
+	}
+
+	if ( empty( $wp_hasher ) ) {
+		require_once ABSPATH . WPINC . '/class-phpass.php';
+		$wp_hasher = new PasswordHash( 8, true );
+	}
+
+	$key_request_time = $request->modified_timestamp;
+	$saved_key        = $request->confirm_key;
+
+	if ( ! $saved_key ) {
+		return new WP_Error( 'invalid_key', __( 'Invalid key' ) );
+	}
+
+	if ( ! $key_request_time ) {
+		return new WP_Error( 'invalid_key', __( 'Invalid action' ) );
+	}
+
+	/**
+	 * Filters the expiration time of confirm keys.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param int $expiration The expiration time in seconds.
+	 */
+	$expiration_duration = (int) apply_filters( 'user_request_key_expiration', DAY_IN_SECONDS );
+	$expiration_time     = $key_request_time + $expiration_duration;
+
+	if ( ! $wp_hasher->CheckPassword( $key, $saved_key ) ) {
+		return new WP_Error( 'invalid_key', __( 'Invalid key' ) );
+	}
+
+	if ( ! $expiration_time || time() > $expiration_time ) {
+		return new WP_Error( 'expired_key', __( 'The confirmation email has expired.' ) );
+	}
+
+	return true;
+}
+
+/**
+ * Return data about a user request.
+ *
+ * @since 4.9.6
+ *
+ * @param int $request_id Request ID to get data about.
+ * @return WP_User_Request|false
+ */
+function wp_get_user_request_data( $request_id ) {
+	$request_id = absint( $request_id );
+	$post       = get_post( $request_id );
+
+	if ( ! $post || 'user_request' !== $post->post_type ) {
+		return false;
+	}
+
+	return new WP_User_Request( $post );
+}
+
+/**
+ * WP_User_Request class.
+ *
+ * Represents user request data loaded from a WP_Post object.
+ *
+ * @since 4.9.6
+ */
+final class WP_User_Request {
+	/**
+	 * Request ID.
+	 *
+	 * @var int
+	 */
+	public $ID = 0;
+
+	/**
+	 * User ID.
+	 *
+	 * @var int
+	 */
+
+	public $user_id = 0;
+
+	/**
+	 * User email.
+	 *
+	 * @var int
+	 */
+	public $email = '';
+
+	/**
+	 * Action name.
+	 *
+	 * @var string
+	 */
+	public $action_name = '';
+
+	/**
+	 * Current status.
+	 *
+	 * @var string
+	 */
+	public $status = '';
+
+	/**
+	 * Timestamp this request was created.
+	 *
+	 * @var int|null
+	 */
+	public $created_timestamp = null;
+
+	/**
+	 * Timestamp this request was last modified.
+	 *
+	 * @var int|null
+	 */
+	public $modified_timestamp = null;
+
+	/**
+	 * Timestamp this request was confirmed.
+	 *
+	 * @var int
+	 */
+	public $confirmed_timestamp = null;
+
+	/**
+	 * Timestamp this request was completed.
+	 *
+	 * @var int
+	 */
+	public $completed_timestamp = null;
+
+	/**
+	 * Misc data assigned to this request.
+	 *
+	 * @var array
+	 */
+	public $request_data = array();
+
+	/**
+	 * Key used to confirm this request.
+	 *
+	 * @var string
+	 */
+	public $confirm_key = '';
+
+	/**
+	 * Constructor.
+	 *
+	 * @since 4.9.6
+	 *
+	 * @param WP_Post|object $post Post object.
+	 */
+	public function __construct( $post ) {
+		$this->ID                  = $post->ID;
+		$this->user_id             = $post->post_author;
+		$this->email               = $post->post_title;
+		$this->action_name         = $post->post_name;
+		$this->status              = $post->post_status;
+		$this->created_timestamp   = strtotime( $post->post_date_gmt );
+		$this->modified_timestamp  = strtotime( $post->post_modified_gmt );
+		$this->confirmed_timestamp = (int) get_post_meta( $post->ID, '_wp_user_request_confirmed_timestamp', true );
+		$this->completed_timestamp = (int) get_post_meta( $post->ID, '_wp_user_request_completed_timestamp', true );
+		$this->request_data        = json_decode( $post->post_content, true );
+		$this->confirm_key         = $post->post_password;
+	}
+}