[wp-trac] [WordPress Trac] #22252: register_theme_directory() usage can break the current theme

[WordPress Trac]

#22252: register_theme_directory() usage can break the current theme
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 Reporter:  johnjamesjacoby  |       Type:  defect (bug)
   Status:  new              |   Priority:  normal
Milestone:  Awaiting Review  |  Component:  Themes
  Version:  trunk            |   Severity:  normal
 Keywords:  has-patch        |
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 '''Problem:'''
 It's possible for the active theme and it's roots to become out of sync
 when performing a specific set of actions, resulting in the site white-
 screening because of the active theme directory being incorrect.

 Hard to explain, so I've included more information below.

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 '''Steps to reproduce:'''
 1. Activate !BuddyPress.
 2. Activate bp-default theme.
 3. Deactivate !BuddyPress.
 4. Visit Appearance > Themes.
 5. Check DB: stylesheet and template are changed to 'twentytwelve'.
 6. Check DB: stylesheet_root and template_root still point to
 '/plugins/buddypress/bp-themes/'.
 7. Reactivate !BuddyPress.
 8. Visit Appearance > Themes.
 9. twentytwelve reports back as broken
 ----
 '''Stack:'''

 * wp-admin/themes.php:line 107 calls validate_current_theme()
 * wp-includes/theme.php:719 calls switch_theme()
 * wp-includes/theme.php 682 counts $wp_theme_directories, and skips the
 roots.
 * This results in the _root options pointing to 'wp-
 content/plugins/buddypress/bp-themes', and the current stylesheet and
 template being set as 'twentyeleven'.
 * If you re-activate !BuddyPress, $wp_theme_directories will now be
 greater than 1, and the _root options will not get updated.
 ----
 '''Possible fixes:'''
 * Remove count( $wp_theme_directories ) check from switch_theme(). This
 forces the theme root to be accurate every time the theme switches,
 regardless of how many directories are ever registered. In my opinion,
 this is the most sensible option. (Patch attached)
 * Improve search_theme_directories() to update 'stylesheet_root' and
 'template_root' when 'theme_roots' transient doesn't match up. This works
 because we're already looping through the $cached_roots to make sure each
 theme is valid. The problem here is we're depending on the expiration of
 the transient, and doing additional logic each time that happens. (No
 patch attached)

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Ticket URL: <http://core.trac.wordpress.org/ticket/22252>
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