WordPress at a glance
function is not described

get_core_updates() WP 1.0

Get available core updates.

No Hooks.

Return

Array/false. Array of the update objects on success, false on failure.

Usage

get_core_updates( $options );
$options(array)
Set $options['dismissed'] to true to show dismissed upgrades too, set $options['available'] to false to skip not-dismissed updates.
Default: array()

Code of get core updates: wp-admin/includes/update.php VER 5.0.3

<?php
function get_core_updates( $options = array() ) {
	$options = array_merge( array( 'available' => true, 'dismissed' => false ), $options );
	$dismissed = get_site_option( 'dismissed_update_core' );

	if ( ! is_array( $dismissed ) )
		$dismissed = array();

	$from_api = get_site_transient( 'update_core' );

	if ( ! isset( $from_api->updates ) || ! is_array( $from_api->updates ) )
		return false;

	$updates = $from_api->updates;
	$result = array();
	foreach ( $updates as $update ) {
		if ( $update->response == 'autoupdate' )
			continue;

		if ( array_key_exists( $update->current . '|' . $update->locale, $dismissed ) ) {
			if ( $options['dismissed'] ) {
				$update->dismissed = true;
				$result[] = $update;
			}
		} else {
			if ( $options['available'] ) {
				$update->dismissed = false;
				$result[] = $update;
			}
		}
	}
	return $result;
}