X-Git-Url: https://scripts.mit.edu/gitweb/autoinstalls/wordpress.git/blobdiff_plain/1c09677af04c9e37714e09b73eb9dbc5b2e3eb13..refs/tags/wordpress-3.1-scripts:/wp-includes/capabilities.php

diff --git a/wp-includes/capabilities.php b/wp-includes/capabilities.php
index 4a5ccec0..7d8a00d7 100644
--- a/wp-includes/capabilities.php
+++ b/wp-includes/capabilities.php
@@ -85,7 +85,7 @@ class WP_Roles {
 	}
 
 	/**
-	 * Setup the object properties.
+	 * Set up the object properties.
 	 *
 	 * The role key is set to the current prefix for the $wpdb object with
 	 * 'user_roles' appended. If the $wp_user_roles global is set, then it will
@@ -97,8 +97,7 @@ class WP_Roles {
 	 * @global array $wp_user_roles Used to set the 'roles' property value.
 	 */
 	function _init () {
-		global $wpdb;
-		global $wp_user_roles;
+		global $wpdb, $wp_user_roles;
 		$this->role_key = $wpdb->prefix . 'user_roles';
 		if ( ! empty( $wp_user_roles ) ) {
 			$this->roles = $wp_user_roles;
@@ -125,7 +124,7 @@ class WP_Roles {
 	 *
 	 * The capabilities are defined in the following format `array( 'read' => true );`
 	 * To explicitly deny a role a capability you set the value for that capability to false.
-	 * 
+	 *
 	 * @since 2.0.0
 	 * @access public
 	 *
@@ -270,10 +269,10 @@ class WP_Role {
 	var $capabilities;
 
 	/**
-	 * PHP4 Constructor - Setup object properties.
+	 * PHP4 Constructor - Set up object properties.
 	 *
 	 * The list of capabilities, must have the key as the name of the capability
-	 * and the value a boolean of whether it is granted to the role or not.
+	 * and the value a boolean of whether it is granted to the role.
 	 *
 	 * @since 2.0.0
 	 * @access public
@@ -472,9 +471,10 @@ class WP_User {
 	 *
 	 * @param int|string $id User's ID or username
 	 * @param int $name Optional. User's username
+	 * @param int $blog_id Optional Blog ID, defaults to current blog.
 	 * @return WP_User
 	 */
-	function WP_User( $id, $name = '' ) {
+	function WP_User( $id, $name = '', $blog_id = '' ) {
 
 		if ( empty( $id ) && empty( $name ) )
 			return;
@@ -497,11 +497,11 @@ class WP_User {
 		}
 
 		$this->id = $this->ID;
-		$this->_init_caps();
+		$this->for_blog( $blog_id );
 	}
 
 	/**
-	 * Setup capability object properties.
+	 * Set up capability object properties.
 	 *
 	 * Will set the value for the 'cap_key' property to current database table
 	 * prefix, followed by 'capabilities'. Will then check to see if the
@@ -509,11 +509,16 @@ class WP_User {
 	 * used.
 	 *
 	 * @since 2.1.0
+	 *
+	 * @param string $cap_key Optional capability key
 	 * @access protected
 	 */
-	function _init_caps() {
+	function _init_caps( $cap_key = '' ) {
 		global $wpdb;
-		$this->cap_key = $wpdb->prefix . 'capabilities';
+		if ( empty($cap_key) )
+			$this->cap_key = $wpdb->prefix . 'capabilities';
+		else
+			$this->cap_key = $cap_key;
 		$this->caps = &$this->{$this->cap_key};
 		if ( ! is_array( $this->caps ) )
 			$this->caps = array();
@@ -545,8 +550,8 @@ class WP_User {
 		//Build $allcaps from role caps, overlay user's $caps
 		$this->allcaps = array();
 		foreach ( (array) $this->roles as $role ) {
-			$role =& $wp_roles->get_role( $role );
-			$this->allcaps = array_merge( (array) $this->allcaps, (array) $role->capabilities );
+			$the_role =& $wp_roles->get_role( $role );
+			$this->allcaps = array_merge( (array) $this->allcaps, (array) $the_role->capabilities );
 		}
 		$this->allcaps = array_merge( (array) $this->allcaps, (array) $this->caps );
 	}
@@ -563,7 +568,7 @@ class WP_User {
 	 */
 	function add_role( $role ) {
 		$this->caps[$role] = true;
-		update_usermeta( $this->ID, $this->cap_key, $this->caps );
+		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 		$this->get_role_caps();
 		$this->update_user_level_from_caps();
 	}
@@ -577,11 +582,12 @@ class WP_User {
 	 * @param string $role Role name.
 	 */
 	function remove_role( $role ) {
-		if ( empty( $this->roles[$role] ) || ( count( $this->roles ) <= 1 ) )
+		if ( !in_array($role, $this->roles) )
 			return;
 		unset( $this->caps[$role] );
-		update_usermeta( $this->ID, $this->cap_key, $this->caps );
+		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 		$this->get_role_caps();
+		$this->update_user_level_from_caps();
 	}
 
 	/**
@@ -599,13 +605,17 @@ class WP_User {
 	function set_role( $role ) {
 		foreach ( (array) $this->roles as $oldrole )
 			unset( $this->caps[$oldrole] );
+
+		if ( 1 == count( $this->roles ) && $role == $this->roles[0] )
+			return;
+
 		if ( !empty( $role ) ) {
 			$this->caps[$role] = true;
 			$this->roles = array( $role => true );
 		} else {
 			$this->roles = false;
 		}
-		update_usermeta( $this->ID, $this->cap_key, $this->caps );
+		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 		$this->get_role_caps();
 		$this->update_user_level_from_caps();
 		do_action( 'set_user_role', $this->ID, $role );
@@ -652,7 +662,7 @@ class WP_User {
 	function update_user_level_from_caps() {
 		global $wpdb;
 		$this->user_level = array_reduce( array_keys( $this->allcaps ), array( &$this, 'level_reduction' ), 0 );
-		update_usermeta( $this->ID, $wpdb->prefix.'user_level', $this->user_level );
+		update_user_meta( $this->ID, $wpdb->prefix . 'user_level', $this->user_level );
 	}
 
 	/**
@@ -666,7 +676,7 @@ class WP_User {
 	 */
 	function add_cap( $cap, $grant = true ) {
 		$this->caps[$cap] = $grant;
-		update_usermeta( $this->ID, $this->cap_key, $this->caps );
+		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 	}
 
 	/**
@@ -678,9 +688,10 @@ class WP_User {
 	 * @param string $cap Capability name.
 	 */
 	function remove_cap( $cap ) {
-		if ( empty( $this->caps[$cap] ) ) return;
+		if ( empty( $this->caps[$cap] ) )
+			return;
 		unset( $this->caps[$cap] );
-		update_usermeta( $this->ID, $this->cap_key, $this->caps );
+		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 	}
 
 	/**
@@ -692,8 +703,8 @@ class WP_User {
 	function remove_all_caps() {
 		global $wpdb;
 		$this->caps = array();
-		update_usermeta( $this->ID, $this->cap_key, '' );
-		update_usermeta( $this->ID, $wpdb->prefix.'user_level', '' );
+		delete_user_meta( $this->ID, $this->cap_key );
+		delete_user_meta( $this->ID, $wpdb->prefix . 'user_level' );
 		$this->get_role_caps();
 	}
 
@@ -712,14 +723,25 @@ class WP_User {
 	 * @return bool True, if user has capability; false, if user does not have capability.
 	 */
 	function has_cap( $cap ) {
-		if ( is_numeric( $cap ) )
+		if ( is_numeric( $cap ) ) {
+			_deprecated_argument( __FUNCTION__, '2.0', __('Usage of user levels by plugins and themes is deprecated. Use roles and capabilities instead.') );
 			$cap = $this->translate_level_to_cap( $cap );
+		}
 
 		$args = array_slice( func_get_args(), 1 );
 		$args = array_merge( array( $cap, $this->ID ), $args );
 		$caps = call_user_func_array( 'map_meta_cap', $args );
+
+		// Multisite super admin has all caps by definition, Unless specifically denied.
+		if ( is_multisite() && is_super_admin( $this->ID ) ) {
+			if ( in_array('do_not_allow', $caps) )
+				return false;
+			return true;
+		}
+
 		// Must have ALL requested caps
 		$capabilities = apply_filters( 'user_has_cap', $this->allcaps, $caps, $args );
+		$capabilities['exist'] = true; // Everyone is allowed to exist
 		foreach ( (array) $caps as $cap ) {
 			//echo "Checking cap $cap<br />";
 			if ( empty( $capabilities[$cap] ) || !$capabilities[$cap] )
@@ -744,6 +766,21 @@ class WP_User {
 		return 'level_' . $level;
 	}
 
+	/**
+	 * Set the blog to operate on. Defaults to the current blog.
+	 *
+	 * @since 3.0.0
+	 *
+	 * @param int $blog_id Optional Blog ID, defaults to current blog.
+	 */
+	function for_blog( $blog_id = '' ) {
+		global $wpdb;
+		if ( ! empty( $blog_id ) )
+			$cap_key = $wpdb->get_blog_prefix( $blog_id ) . 'capabilities';
+		else
+			$cap_key = '';
+		$this->_init_caps( $cap_key );
+	}
 }
 
 /**
@@ -751,8 +788,8 @@ class WP_User {
  *
  * This does not actually compare whether the user ID has the actual capability,
  * just what the capability or capabilities are. Meta capability list value can
- * be 'delete_user', 'edit_user', 'delete_post', 'delete_page', 'edit_post',
- * 'edit_page', 'read_post', or 'read_page'.
+ * be 'delete_user', 'edit_user', 'remove_user', 'promote_user', 'delete_post',
+ * 'delete_page', 'edit_post', 'edit_page', 'read_post', or 'read_page'.
  *
  * @since 2.0.0
  *
@@ -765,191 +802,213 @@ function map_meta_cap( $cap, $user_id ) {
 	$caps = array();
 
 	switch ( $cap ) {
-	case 'delete_user':
-		$caps[] = 'delete_users';
+	case 'remove_user':
+		$caps[] = 'remove_users';
+		break;
+	case 'promote_user':
+		$caps[] = 'promote_users';
 		break;
 	case 'edit_user':
-		if ( !isset( $args[0] ) || $user_id != $args[0] ) {
-			$caps[] = 'edit_users';
-		}
+		// Allow user to edit itself
+		if ( isset( $args[0] ) && $user_id == $args[0] )
+			break;
+		// Fall through
+	case 'edit_users':
+		// If multisite these caps are allowed only for super admins.
+		if ( is_multisite() && !is_super_admin( $user_id ) )
+			$caps[] = 'do_not_allow';
+		else
+			$caps[] = 'edit_users'; // Explicit due to primitive fall through
 		break;
 	case 'delete_post':
+	case 'delete_page':
 		$author_data = get_userdata( $user_id );
-		//echo "post ID: {$args[0]}<br />";
 		$post = get_post( $args[0] );
-		if ( 'page' == $post->post_type ) {
-			$args = array_merge( array( 'delete_page', $user_id ), $args );
-			return call_user_func_array( 'map_meta_cap', $args );
+		$post_type = get_post_type_object( $post->post_type );
+
+		if ( ! $post_type->map_meta_cap ) {
+			$caps[] = $post_type->cap->$cap;
+			// Prior to 3.1 we would re-call map_meta_cap here.
+			if ( 'delete_post' == $cap )
+				$cap = $post_type->cap->$cap;
+			break;
 		}
 
-		if ('' != $post->post_author) {
+		if ( '' != $post->post_author ) {
 			$post_author_data = get_userdata( $post->post_author );
 		} else {
-			//No author set yet so default to current user for cap checks
+			// No author set yet, so default to current user for cap checks.
 			$post_author_data = $author_data;
 		}
 
 		// If the user is the author...
-		if ( $user_id == $post_author_data->ID ) {
+		if ( is_object( $post_author_data ) && $user_id == $post_author_data->ID ) {
 			// If the post is published...
 			if ( 'publish' == $post->post_status ) {
-				$caps[] = 'delete_published_posts';
+				$caps[] = $post_type->cap->delete_published_posts;
 			} elseif ( 'trash' == $post->post_status ) {
 				if ('publish' == get_post_meta($post->ID, '_wp_trash_meta_status', true) )
-					$caps[] = 'delete_published_posts';
+					$caps[] = $post_type->cap->delete_published_posts;
 			} else {
 				// If the post is draft...
-				$caps[] = 'delete_posts';
+				$caps[] = $post_type->cap->delete_posts;
 			}
 		} else {
 			// The user is trying to edit someone else's post.
-			$caps[] = 'delete_others_posts';
+			$caps[] = $post_type->cap->delete_others_posts;
 			// The post is published, extra cap required.
 			if ( 'publish' == $post->post_status )
-				$caps[] = 'delete_published_posts';
+				$caps[] = $post_type->cap->delete_published_posts;
 			elseif ( 'private' == $post->post_status )
-				$caps[] = 'delete_private_posts';
-		}
-		break;
-	case 'delete_page':
-		$author_data = get_userdata( $user_id );
-		//echo "post ID: {$args[0]}<br />";
-		$page = get_page( $args[0] );
-		$page_author_data = get_userdata( $page->post_author );
-		//echo "current user id : $user_id, page author id: " . $page_author_data->ID . "<br />";
-		// If the user is the author...
-
-		if ('' != $page->post_author) {
-			$page_author_data = get_userdata( $page->post_author );
-		} else {
-			//No author set yet so default to current user for cap checks
-			$page_author_data = $author_data;
-		}
-
-		if ( $user_id == $page_author_data->ID ) {
-			// If the page is published...
-			if ( $page->post_status == 'publish' ) {
-				$caps[] = 'delete_published_pages';
-			} elseif ( 'trash' == $page->post_status ) {
-				if ('publish' == get_post_meta($page->ID, '_wp_trash_meta_status', true) )
-					$caps[] = 'delete_published_pages';
-			} else {
-				// If the page is draft...
-				$caps[] = 'delete_pages';
-			}
-		} else {
-			// The user is trying to edit someone else's page.
-			$caps[] = 'delete_others_pages';
-			// The page is published, extra cap required.
-			if ( $page->post_status == 'publish' )
-				$caps[] = 'delete_published_pages';
-			elseif ( $page->post_status == 'private' )
-				$caps[] = 'delete_private_pages';
+				$caps[] = $post_type->cap->delete_private_posts;
 		}
 		break;
 		// edit_post breaks down to edit_posts, edit_published_posts, or
 		// edit_others_posts
 	case 'edit_post':
+	case 'edit_page':
 		$author_data = get_userdata( $user_id );
-		//echo "post ID: {$args[0]}<br />";
 		$post = get_post( $args[0] );
-		if ( 'page' == $post->post_type ) {
-			$args = array_merge( array( 'edit_page', $user_id ), $args );
-			return call_user_func_array( 'map_meta_cap', $args );
+		$post_type = get_post_type_object( $post->post_type );
+
+		if ( ! $post_type->map_meta_cap ) {
+			$caps[] = $post_type->cap->$cap;
+			// Prior to 3.1 we would re-call map_meta_cap here.
+			if ( 'edit_post' == $cap )
+				$cap = $post_type->cap->$cap;
+			break;
 		}
-		$post_author_data = get_userdata( $post->post_author );
+
+		if ( '' != $post->post_author ) {
+			$post_author_data = get_userdata( $post->post_author );
+		} else {
+			// No author set yet, so default to current user for cap checks.
+			$post_author_data = $author_data;
+		}
+
 		//echo "current user id : $user_id, post author id: " . $post_author_data->ID . "<br />";
 		// If the user is the author...
-		if ( $user_id == $post_author_data->ID ) {
+		if ( is_object( $post_author_data ) && $user_id == $post_author_data->ID ) {
 			// If the post is published...
 			if ( 'publish' == $post->post_status ) {
-				$caps[] = 'edit_published_posts';
+				$caps[] = $post_type->cap->edit_published_posts;
 			} elseif ( 'trash' == $post->post_status ) {
 				if ('publish' == get_post_meta($post->ID, '_wp_trash_meta_status', true) )
-					$caps[] = 'edit_published_posts';
+					$caps[] = $post_type->cap->edit_published_posts;
 			} else {
 				// If the post is draft...
-				$caps[] = 'edit_posts';
+				$caps[] = $post_type->cap->edit_posts;
 			}
 		} else {
 			// The user is trying to edit someone else's post.
-			$caps[] = 'edit_others_posts';
+			$caps[] = $post_type->cap->edit_others_posts;
 			// The post is published, extra cap required.
 			if ( 'publish' == $post->post_status )
-				$caps[] = 'edit_published_posts';
+				$caps[] = $post_type->cap->edit_published_posts;
 			elseif ( 'private' == $post->post_status )
-				$caps[] = 'edit_private_posts';
-		}
-		break;
-	case 'edit_page':
-		$author_data = get_userdata( $user_id );
-		//echo "post ID: {$args[0]}<br />";
-		$page = get_page( $args[0] );
-		$page_author_data = get_userdata( $page->post_author );
-		//echo "current user id : $user_id, page author id: " . $page_author_data->ID . "<br />";
-		// If the user is the author...
-		if ( $user_id == $page_author_data->ID ) {
-			// If the page is published...
-			if ( 'publish' == $page->post_status ) {
-				$caps[] = 'edit_published_pages';
-			} elseif ( 'trash' == $page->post_status ) {
-				if ('publish' == get_post_meta($page->ID, '_wp_trash_meta_status', true) )
-					$caps[] = 'edit_published_pages';
-			} else {
-				// If the page is draft...
-				$caps[] = 'edit_pages';
-			}
-		} else {
-			// The user is trying to edit someone else's page.
-			$caps[] = 'edit_others_pages';
-			// The page is published, extra cap required.
-			if ( 'publish' == $page->post_status )
-				$caps[] = 'edit_published_pages';
-			elseif ( 'private' == $page->post_status )
-				$caps[] = 'edit_private_pages';
+				$caps[] = $post_type->cap->edit_private_posts;
 		}
 		break;
 	case 'read_post':
+	case 'read_page':
+		$author_data = get_userdata( $user_id );
 		$post = get_post( $args[0] );
-		if ( 'page' == $post->post_type ) {
-			$args = array_merge( array( 'read_page', $user_id ), $args );
-			return call_user_func_array( 'map_meta_cap', $args );
+		$post_type = get_post_type_object( $post->post_type );
+
+		if ( ! $post_type->map_meta_cap ) {
+			$caps[] = $post_type->cap->$cap;
+			// Prior to 3.1 we would re-call map_meta_cap here.
+			if ( 'read_post' == $cap )
+				$cap = $post_type->cap->$cap;
+			break;
 		}
 
 		if ( 'private' != $post->post_status ) {
-			$caps[] = 'read';
+			$caps[] = $post_type->cap->read;
 			break;
 		}
 
-		$author_data = get_userdata( $user_id );
-		$post_author_data = get_userdata( $post->post_author );
-		if ( $user_id == $post_author_data->ID )
-			$caps[] = 'read';
+		if ( '' != $post->post_author ) {
+			$post_author_data = get_userdata( $post->post_author );
+		} else {
+			// No author set yet, so default to current user for cap checks.
+			$post_author_data = $author_data;
+		}
+
+		if ( is_object( $post_author_data ) && $user_id == $post_author_data->ID )
+			$caps[] = $post_type->cap->read;
 		else
-			$caps[] = 'read_private_posts';
+			$caps[] = $post_type->cap->read_private_posts;
 		break;
-	case 'read_page':
-		$page = get_page( $args[0] );
+	case 'edit_comment':
+		$comment = get_comment( $args[0] );
+		$post = get_post( $comment->comment_post_ID );
+		$post_type_object = get_post_type_object( $post->post_type );
 
-		if ( 'private' != $page->post_status ) {
-			$caps[] = 'read';
+		$caps = map_meta_cap( $post_type_object->cap->edit_post, $user_id, $post->ID );
+		break;
+	case 'unfiltered_upload':
+		if ( defined('ALLOW_UNFILTERED_UPLOADS') && ALLOW_UNFILTERED_UPLOADS && ( !is_multisite() || is_super_admin( $user_id ) )  )
+			$caps[] = $cap;
+		else
+			$caps[] = 'do_not_allow';
+		break;
+	case 'edit_files':
+	case 'edit_plugins':
+	case 'edit_themes':
+		if ( defined('DISALLOW_FILE_EDIT') && DISALLOW_FILE_EDIT ) {
+			$caps[] = 'do_not_allow';
 			break;
 		}
-
-		$author_data = get_userdata( $user_id );
-		$page_author_data = get_userdata( $page->post_author );
-		if ( $user_id == $page_author_data->ID )
-			$caps[] = 'read';
-		else
-			$caps[] = 'read_private_pages';
+		// Fall through if not DISALLOW_FILE_EDIT.
+	case 'update_plugins':
+	case 'delete_plugins':
+	case 'install_plugins':
+	case 'update_themes':
+	case 'delete_themes':
+	case 'install_themes':
+	case 'update_core':
+		// Disallow anything that creates, deletes, or edits core, plugin, or theme files.
+		// Files in uploads are excepted.
+		if ( defined('DISALLOW_FILE_MODS') && DISALLOW_FILE_MODS ) {
+			$caps[] = 'do_not_allow';
+			break;
+		}
+		// Fall through if not DISALLOW_FILE_MODS.
+	case 'unfiltered_html':
+		// Disallow unfiltered_html for all users, even admins and super admins.
+		if ( defined('DISALLOW_UNFILTERED_HTML') && DISALLOW_UNFILTERED_HTML ) {
+			$caps[] = 'do_not_allow';
+			break;
+		}
+		// Fall through if not DISALLOW_UNFILTERED_HTML
+	case 'delete_user':
+	case 'delete_users':
+		// If multisite these caps are allowed only for super admins.
+		if ( is_multisite() && !is_super_admin( $user_id ) ) {
+			$caps[] = 'do_not_allow';
+		} else {
+			if ( 'delete_user' == $cap )
+				$cap = 'delete_users';
+			$caps[] = $cap;
+		}
 		break;
-	case 'unfiltered_upload':
-		if ( defined('ALLOW_UNFILTERED_UPLOADS') && ALLOW_UNFILTERED_UPLOADS == true )
+	case 'create_users':
+		if ( !is_multisite() )
+			$caps[] = $cap;
+		elseif ( is_super_admin() || get_site_option( 'add_new_users' ) )
 			$caps[] = $cap;
 		else
 			$caps[] = 'do_not_allow';
 		break;
 	default:
+		// Handle meta capabilities for custom post types.
+		$post_type_meta_caps = _post_type_meta_capabilities();
+		if ( isset( $post_type_meta_caps[ $cap ] ) ) {
+			$args = array_merge( array( $post_type_meta_caps[ $cap ], $user_id ), $args );
+			return call_user_func_array( 'map_meta_cap', $args );
+		}
+
 		// If no meta caps match, return the original cap.
 		$caps[] = $cap;
 	}
@@ -977,6 +1036,33 @@ function current_user_can( $capability ) {
 	return call_user_func_array( array( &$current_user, 'has_cap' ), $args );
 }
 
+/**
+ * Whether current user has a capability or role for a given blog.
+ *
+ * @since 3.0.0
+ *
+ * @param int $blog_id Blog ID
+ * @param string $capability Capability or role name.
+ * @return bool
+ */
+function current_user_can_for_blog( $blog_id, $capability ) {
+	$current_user = wp_get_current_user();
+
+	if ( empty( $current_user ) )
+		return false;
+
+	// Create new object to avoid stomping the global current_user.
+	$user = new WP_User( $current_user->id) ;
+
+	// Set the blog id.  @todo add blog id arg to WP_User constructor?
+	$user->for_blog( $blog_id );
+
+	$args = array_slice( func_get_args(), 2 );
+	$args = array_merge( array( $capability ), $args );
+
+	return call_user_func_array( array( &$user, 'has_cap' ), $args );
+}
+
 /**
  * Whether author of supplied post has capability or role.
  *
@@ -992,7 +1078,7 @@ function author_can( $post, $capability ) {
 
 	$author = new WP_User( $post->post_author );
 
-	if ( empty( $author ) )
+	if ( empty( $author->ID ) )
 		return false;
 
 	$args = array_slice( func_get_args(), 2 );
@@ -1001,6 +1087,28 @@ function author_can( $post, $capability ) {
 	return call_user_func_array( array( &$author, 'has_cap' ), $args );
 }
 
+/**
+ * Whether a particular user has capability or role.
+ *
+ * @since 3.1.0
+ *
+ * @param int|object $user User ID or object.
+ * @param string $capability Capability or role name.
+ * @return bool
+ */
+function user_can( $user, $capability ) {
+	if ( ! is_object( $user ) )
+		$user = new WP_User( $user );
+
+	if ( ! $user || ! $user->ID )
+		return false;
+
+	$args = array_slice( func_get_args(), 2 );
+	$args = array_merge( array( $capability ), $args );
+
+	return call_user_func_array( array( &$user, 'has_cap' ), $args );
+}
+
 /**
  * Retrieve role object.
  *
@@ -1027,7 +1135,7 @@ function get_role( $role ) {
  *
  * @param string $role Role name.
  * @param string $display_name Display name for role.
- * @param array $capabilities List of capabilities.
+ * @param array $capabilities List of capabilities, e.g. array( 'edit_posts' => true, 'delete_posts' => false );
  * @return null|WP_Role WP_Role object if role is added, null if already exists.
  */
 function add_role( $role, $display_name, $capabilities = array() ) {
@@ -1057,4 +1165,51 @@ function remove_role( $role ) {
 	return $wp_roles->remove_role( $role );
 }
 
+/**
+ * Retrieve a list of super admins.
+ *
+ * @since 3.0.0
+ *
+ * @uses $super_admins Super admins global variable, if set.
+ *
+ * @return array List of super admin logins
+ */
+function get_super_admins() {
+	global $super_admins;
+
+	if ( isset($super_admins) )
+		return $super_admins;
+	else
+		return get_site_option( 'site_admins', array('admin') );
+}
+
+/**
+ * Determine if user is a site admin.
+ *
+ * @since 3.0.0
+ *
+ * @param int $user_id (Optional) The ID of a user. Defaults to the current user.
+ * @return bool True if the user is a site admin.
+ */
+function is_super_admin( $user_id = false ) {
+	if ( $user_id )
+		$user = new WP_User( $user_id );
+	else
+		$user = wp_get_current_user();
+
+	if ( empty( $user->id ) )
+		return false;
+
+	if ( is_multisite() ) {
+		$super_admins = get_super_admins();
+		if ( is_array( $super_admins ) && in_array( $user->user_login, $super_admins ) )
+			return true;
+	} else {
+		if ( $user->has_cap('delete_users') )
+			return true;
+	}
+
+	return false;
+}
+
 ?>