Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1000
diff -u -p -r1.1000 common.inc
--- includes/common.inc	29 Sep 2009 17:52:46 -0000	1.1000
+++ includes/common.inc	30 Sep 2009 16:53:00 -0000
@@ -2318,6 +2318,33 @@ function _format_date_callback(array $ma
 }
 
 /**
+ * Format a username.
+ *
+ * By default, the passed in object's 'name' property is used if it exists, or
+ * else, the site-defined value for the 'anonymous' variable. However, a module
+ * may override this by implementing hook_username_alter(&$name, $account).
+ *
+ * @see hook_username_alter()
+ *
+ * @param $account
+ *   The account object for the user whose name is to be formatted.
+ *
+ * @return
+ *   An unsanitized string with the username to display. The code receiving
+ *   this result must ensure that check_plain() is called on it before it is
+ *   printed to the page.
+ */
+function format_username($account) {
+  $name = !empty($account->name) ? $account->name : variable_get('anonymous', t('Anonymous'));
+  // Faster than drupal_alter(), and format_username() gets called a lot.
+  foreach (module_implements('username_alter') as $module) {
+    $function = $module . '_username_alter';
+    $function($name, $account);
+  }
+  return $name;
+}
+
+/**
  * @} End of "defgroup format".
  */
 
Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.526
diff -u -p -r1.526 theme.inc
--- includes/theme.inc	21 Sep 2009 06:36:54 -0000	1.526
+++ includes/theme.inc	30 Sep 2009 16:53:00 -0000
@@ -1885,12 +1885,17 @@ function template_preprocess_username(&$
   else {
     $variables['object']->uid = (int)$account->uid;
   }
-  if (empty($account->name)) {
-    $variables['object']->name = variable_get('anonymous', t('Anonymous'));
-  }
-  else {
-    $variables['object']->name = $account->name;
+
+  // Set the name property to a formatted name that is safe for printing and
+  // that won't break tables by being too long. Keep an unshortened,
+  // unsanitized version, in case other preproces functions want to implement
+  // their own shortening logic or add markup. If they do so, they must ensure
+  // that $variables['object']->name is safe for printing.
+  $name = $variables['object']->name_unsafe = format_username($account);
+  if (drupal_strlen($name) > 20) {
+    $name = drupal_substr($name, 0, 15) . '...';
   }
+  $variables['object']->name = check_plain($name);
 
   $variables['object']->profile_access = user_access('access user profiles');
   $variables['object']->link_attributes = array();
@@ -1909,12 +1914,6 @@ function template_preprocess_username(&$
   $variables['object']->link_options['html'] = TRUE;
   // Set a default class.
   $variables['object']->attributes = array('class' => array('username'));
-  // Shorten the name when it is too long or it will break many tables.
-  if (drupal_strlen($variables['object']->name) > 20) {
-    $variables['object']->name = drupal_substr($variables['object']->name, 0, 15) . '...';
-  }
-  // Make sure name is safe for use in the theme function.
-  $variables['object']->name = check_plain($variables['object']->name);
 }
 
 /**
@@ -2108,7 +2107,7 @@ function template_preprocess_html(&$vari
   else {
     $variables['classes_array'][] = 'no-sidebars';
   }
-  
+
   // Populate the body classes.
   if ($suggestions = template_page_suggestions(arg(), 'page')) {
     foreach ($suggestions as $suggestion) {
@@ -2122,7 +2121,7 @@ function template_preprocess_html(&$vari
       }
     }
   }
-  
+
   if ($node = menu_get_object()) {
     $variables['classes_array'][] = 'node-type-' . form_clean_id($node->type);
   }
@@ -2154,7 +2153,7 @@ function template_preprocess_html(&$vari
     }
   }
   $variables['head_title'] = implode(' | ', $head_title);
-  
+
   // Populate the page template suggestions.
   if ($suggestions = template_page_suggestions(arg(), 'html')) {
     $variables['template_files'] = $suggestions;
Index: modules/blog/blog.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/blog/blog.module,v
retrieving revision 1.335
diff -u -p -r1.335 blog.module
--- modules/blog/blog.module	29 Aug 2009 05:46:02 -0000	1.335
+++ modules/blog/blog.module	30 Sep 2009 16:53:00 -0000
@@ -27,7 +27,7 @@ function blog_user_view($account) {
     $account->content['summary']['blog'] =  array(
       '#type' => 'user_profile_item',
       '#title' => t('Blog'),
-      '#markup' => l(t('View recent blog entries'), "blog/$account->uid", array('attributes' => array('title' => t("Read !username's latest blog entries.", array('!username' => $account->name))))),
+      '#markup' => l(t('View recent blog entries'), "blog/$account->uid", array('attributes' => array('title' => t("Read !username's latest blog entries.", array('!username' => format_username($account)))))),
       '#attributes' => array('class' => array('blog')),
     );
   }
@@ -60,7 +60,7 @@ function blog_form($node, $form_state) {
 function blog_view($node, $build_mode) {
   if ((bool)menu_get_object()) {
     // Breadcrumb navigation.
-    drupal_set_breadcrumb(array(l(t('Home'), NULL), l(t('Blogs'), 'blog'), l(t("!name's blog", array('!name' => $node->name)), 'blog/' . $node->uid)));
+    drupal_set_breadcrumb(array(l(t('Home'), NULL), l(t('Blogs'), 'blog'), l(t("!name's blog", array('!name' => format_username($node))), 'blog/' . $node->uid)));
   }
   return $node;
 }
@@ -72,9 +72,9 @@ function blog_node_view($node, $build_mo
   if ($build_mode != 'rss') {
     if ($node->type == 'blog' && arg(0) != 'blog' || arg(1) != $node->uid) {
       $links['blog_usernames_blog'] = array(
-        'title' => t("!username's blog", array('!username' => $node->name)),
+        'title' => t("!username's blog", array('!username' => format_username($node))),
         'href' => "blog/$node->uid",
-        'attributes' => array('title' => t("Read !username's latest blog entries.", array('!username' => $node->name))),
+        'attributes' => array('title' => t("Read !username's latest blog entries.", array('!username' => format_username($node)))),
       );
       $node->content['links']['blog'] = array(
         '#theme' => 'links',
Index: modules/blog/blog.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/blog/blog.pages.inc,v
retrieving revision 1.22
diff -u -p -r1.22 blog.pages.inc
--- modules/blog/blog.pages.inc	10 Aug 2009 22:39:24 -0000	1.22
+++ modules/blog/blog.pages.inc	30 Sep 2009 16:53:00 -0000
@@ -12,7 +12,7 @@
 function blog_page_user($account) {
   global $user;
 
-  drupal_set_title($title = t("@name's blog", array('@name' => $account->name)), PASS_THROUGH);
+  drupal_set_title($title = t("@name's blog", array('@name' => format_username($account))), PASS_THROUGH);
 
   $items = array();
 
@@ -123,7 +123,7 @@ function blog_feed_user($account) {
     ->execute()
     ->fetchCol();
 
-  $channel['title'] = t("!name's blog", array('!name' => $account->name));
+  $channel['title'] = t("!name's blog", array('!name' => format_username($account)));
   $channel['link'] = url('blog/' . $account->uid, array('absolute' => TRUE));
 
   node_feed($nids, $channel);
Index: modules/blog/blog.test
===================================================================
RCS file: /cvs/drupal/drupal/modules/blog/blog.test,v
retrieving revision 1.18
diff -u -p -r1.18 blog.test
--- modules/blog/blog.test	22 Aug 2009 00:58:52 -0000	1.18
+++ modules/blog/blog.test	30 Sep 2009 16:53:00 -0000
@@ -38,7 +38,7 @@ class BlogTestCase extends DrupalWebTest
 
     $this->drupalGet('blog/' . $this->big_user->uid);
     $this->assertResponse(200);
-    $this->assertTitle(t("@name's blog", array('@name' => $this->big_user->name)) . ' | Drupal', t('Blog title was displayed'));
+    $this->assertTitle(t("@name's blog", array('@name' => format_username($this->big_user))) . ' | Drupal', t('Blog title was displayed'));
     $this->assertText(t('You are not allowed to post a new blog entry.'), t('No new entries can be posted without the right permission'));
   }
 
@@ -50,7 +50,7 @@ class BlogTestCase extends DrupalWebTest
 
     $this->drupalGet('blog/' . $this->own_user->uid);
     $this->assertResponse(200);
-    $this->assertTitle(t("@name's blog", array('@name' => $this->own_user->name)) . ' | Drupal', t('Blog title was displayed'));
+    $this->assertTitle(t("@name's blog", array('@name' => format_username($this->own_user))) . ' | Drupal', t('Blog title was displayed'));
     $this->assertText(t('!author has not created any blog entries.', array('!author' => $this->own_user->name)), t('Users blog displayed with no entries'));
   }
 
@@ -180,7 +180,7 @@ class BlogTestCase extends DrupalWebTest
 
     // Confirm the recent blog entries link goes to the user's blog page.
     $this->clickLink('View recent blog entries');
-    $this->assertTitle(t("@name's blog | Drupal", array('@name' => $user->name)), t('View recent blog entries link target was correct'));
+    $this->assertTitle(t("@name's blog | Drupal", array('@name' => format_username($user))), t('View recent blog entries link target was correct'));
 
     // Confirm a blog page was displayed.
     $this->drupalGet('blog');
@@ -191,7 +191,7 @@ class BlogTestCase extends DrupalWebTest
 
     // Confirm a blog page was displayed per user.
     $this->drupalGet('blog/' . $user->uid);
-    $this->assertTitle(t("@name's blog | Drupal", array('@name' => $user->name)), t('User blog node was displayed'));
+    $this->assertTitle(t("@name's blog | Drupal", array('@name' => format_username($user))), t('User blog node was displayed'));
 
     // Confirm a blog feed was displayed.
     $this->drupalGet('blog/feed');
@@ -199,6 +199,6 @@ class BlogTestCase extends DrupalWebTest
 
     // Confirm a blog feed was displayed per user.
     $this->drupalGet('blog/' . $user->uid . '/feed');
-    $this->assertTitle(t("@name's blog", array('@name' => $user->name)), t('User blog feed was displayed'));
+    $this->assertTitle(t("@name's blog", array('@name' => format_username($user))), t('User blog feed was displayed'));
   }
 }
Index: modules/contact/contact.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/contact/contact.pages.inc,v
retrieving revision 1.26
diff -u -p -r1.26 contact.pages.inc
--- modules/contact/contact.pages.inc	29 Sep 2009 15:31:14 -0000	1.26
+++ modules/contact/contact.pages.inc	30 Sep 2009 16:53:00 -0000
@@ -54,7 +54,7 @@ function contact_site_form() {
     '#type' => 'textfield',
     '#title' => t('Your name'),
     '#maxlength' => 255,
-    '#default_value' => $user->uid ? $user->name : '',
+    '#default_value' => format_username($user),
     '#required' => TRUE,
   );
   $form['mail'] = array(
@@ -161,7 +161,7 @@ function contact_personal_page($account)
     $output = t("You cannot send more than %number messages in @interval. Please try again later.", array('%number' => variable_get('contact_threshold_limit', 3), '@interval' => format_interval(variable_get('contact_threshold_window', 3600))));
   }
   else {
-    drupal_set_title($account->name);
+    drupal_set_title(format_username($account));
     $output = drupal_get_form('contact_personal_form', $account);
   }
 
Index: modules/openid/openid.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/openid/openid.pages.inc,v
retrieving revision 1.22
diff -u -p -r1.22 openid.pages.inc
--- modules/openid/openid.pages.inc	21 Sep 2009 06:44:14 -0000	1.22
+++ modules/openid/openid.pages.inc	30 Sep 2009 16:53:00 -0000
@@ -28,7 +28,7 @@ function openid_authentication_page() {
  * Menu callback; Manage OpenID identities for the specified user.
  */
 function openid_user_identities($account) {
-  drupal_set_title($account->name);
+  drupal_set_title(format_username($account));
   drupal_add_css(drupal_get_path('module', 'openid') . '/openid.css');
 
   // Check to see if we got a response
@@ -54,8 +54,8 @@ function openid_user_identities($account
   }
 
   $build['openid_table'] = array(
-    '#theme' => 'table', 
-    '#header' => $header, 
+    '#theme' => 'table',
+    '#header' => $header,
     '#rows' => $rows,
   );
   $build['openid_user_add'] = drupal_get_form('openid_user_add');
Index: modules/system/system.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.api.php,v
retrieving revision 1.79
diff -u -p -r1.79 system.api.php
--- modules/system/system.api.php	29 Sep 2009 15:13:56 -0000	1.79
+++ modules/system/system.api.php	30 Sep 2009 16:53:00 -0000
@@ -2361,5 +2361,27 @@ function hook_action_info_alter(&$action
 }
 
 /**
+ * Alter the username that is displayed for a user.
+ *
+ * Called by format_username() to allow modules to alter the username that's
+ * displayed. Can be used to ensure user privacy in situations where
+ * $account->name is too revealing.
+ *
+ * @param &$name
+ *   The string that format_username() will return.
+ *
+ * @param $account
+ *   The account object passed to format_username().
+ *
+ * @see format_username()
+ */
+function hook_username_alter(&$name, $account) {
+  // Display the user's uid instead of name.
+  if (isset($account->uid)) {
+    $name = t('User !uid', array('!uid' => $account->uid));
+  }
+}
+
+/**
  * @} End of "addtogroup hooks".
  */
Index: modules/tracker/tracker.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/tracker/tracker.pages.inc,v
retrieving revision 1.25
diff -u -p -r1.25 tracker.pages.inc
--- modules/tracker/tracker.pages.inc	5 Sep 2009 15:05:05 -0000	1.25
+++ modules/tracker/tracker.pages.inc	30 Sep 2009 16:53:00 -0000
@@ -19,7 +19,7 @@ function tracker_page($account = NULL, $
       // When viewed from user/%user/track, display the name of the user
       // as page title -- the tab title remains Track so this needs to be done
       // here and not in the menu definition.
-      drupal_set_title($account->name);
+      drupal_set_title(format_username($account));
     }
   }
   else {
Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.1054
diff -u -p -r1.1054 user.module
--- modules/user/user.module	29 Sep 2009 15:31:16 -0000	1.1054
+++ modules/user/user.module	30 Sep 2009 16:53:01 -0000
@@ -817,7 +817,7 @@ function user_search_execute($keys = NUL
     ->limit(15)
     ->execute();
   foreach ($result as $account) {
-    $find[] = array('title' => $account->name . ' (' . $account->mail . ')', 'link' => url('user/' . $account->uid, array('absolute' => TRUE)));
+    $find[] = array('title' => format_username($account) . ' (' . $account->mail . ')', 'link' => url('user/' . $account->uid, array('absolute' => TRUE)));
   }
   return $find;
 }
@@ -1473,7 +1473,7 @@ function user_uid_optional_to_arg($arg) 
  * Menu item title callback - use the user name.
  */
 function user_page_title($account) {
-  return $account->name;
+  return format_username($account);
 }
 
 /**
@@ -2057,7 +2057,7 @@ function _user_cancel($edit, $account, $
  *   The user account of the profile being viewed.
  *
  * To theme user profiles, copy modules/user/user-profile.tpl.php
- * to your theme directory, and edit it as instructed in that file's comments. 
+ * to your theme directory, and edit it as instructed in that file's comments.
  *
  * @param $account
  *   A user object.
@@ -2072,7 +2072,7 @@ function user_build($account) {
   $build = $account->content;
   // We don't need duplicate rendering info in account->content.
   unset($account->content);
-  
+
   $build += array(
     '#theme' => 'user_profile',
     '#account' => $account,
Index: modules/user/user.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.pages.inc,v
retrieving revision 1.57
diff -u -p -r1.57 user.pages.inc
--- modules/user/user.pages.inc	29 Sep 2009 15:31:17 -0000	1.57
+++ modules/user/user.pages.inc	30 Sep 2009 16:53:01 -0000
@@ -213,7 +213,7 @@ function template_preprocess_user_profil
  * Menu callback; Present the form to edit a given user or profile category.
  */
 function user_edit($account, $category = 'account') {
-  drupal_set_title($account->name);
+  drupal_set_title(format_username($account));
   return drupal_get_form('user_profile_form', $account, $category);
 }