[WP] wp-signup.php custom profile meta

<?php

/**
 * Add additional custom fields to profile page
 */

add_action ( 'show_user_profile', 'my_show_extra_profile_fields' );
add_action ( 'edit_user_profile', 'my_show_extra_profile_fields' );

function my_show_extra_profile_fields ( $profileuser ) {
?>

    <h3>Extra profile information</h3>
    <table class="form-table">
        <tr>
            <th>E-mail updates</th>
            <td>
                <label for="e_mail_updates"><input type="checkbox" name="e_mail_updates" id="e_mail_updates" <?php checked('true', $profileuser->e_mail_updates); ?> value="true" /> I would like to receive e-mail updates</label>
            </td>
        </tr>
    </table>

<?php
}

/**
 * Save data input from custom field on profile page
 */

add_action ( 'personal_options_update', 'my_save_extra_profile_fields' );
add_action ( 'edit_user_profile_update', 'my_save_extra_profile_fields' );

function my_save_extra_profile_fields( $user_id ) {

    if ( !current_user_can( 'edit_user', $user_id ) )
        return false;

    /* Copy and paste this line for additional fields. Make sure to change 'e_mail_updates' to the field ID. */
    update_usermeta( $user_id, 'e_mail_updates', $_POST['e_mail_updates'] );

}


/**
 * Add cutom field to WPMU registration form
 */
add_action('signup_extra_fields','custom_signup_extra_fields', $errors);

// this in an example with a text input
function custom_signup_extra_fields($errors) {
?>

    <label for="e_mail_updates"><input type="checkbox" name="e_mail_updates" id="e_mail_updates" <?php if(isset($_POST['e_mail_updates'])) checked('true', $_POST['e_mail_updates']); ?> value="true" /> I would like to receive e-mail updates
    </label>
    <br />

<?php
}


/**
 * Save custom field input to wp_signups table
 */
add_filter( 'add_signup_meta', 'custom_add_signup_meta' );

function custom_add_signup_meta ( $meta = array() ) {

    // create an array of custom meta fields
    $meta['custom_usermeta'] = array(
        // 'meta_key' => $_POST['input_field'],
        'e_mail_updates' => $_POST['e_mail_updates']
        );

    return $meta;

}


/**
 * Set new usermeta upon new user activation
 */
add_action( 'wpmu_activate_user', 'custom_add_new_user_meta', 10, 3 );

function custom_add_new_user_meta( $user_id, $email, $meta ) {

    if ( $meta['custom_usermeta'] ) {
        // loop through array of custom meta fields
        foreach ( $meta['custom_usermeta'] as $key => $value ) {
            // and set each one as a meta field
            update_user_meta( $user_id, $key, $value );
        }
    }

}