[wp-trac] [WordPress Trac] #48199: Check for whether the themes directory writable is incorrect when the current theme is symlinked into the theme directory

[WordPress Trac]

#48199: Check for whether the themes directory writable is incorrect when the
current theme is symlinked into the theme directory
--------------------------+-----------------------------
 Reporter:  pbiron        |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Site Health   |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 To test whether the theme directory is
 writable,[https://core.trac.wordpress.org/browser/trunk/src/wp-
 admin/includes/class-wp-debug-data.php#L322 WP_Debug_Data::debug_data(),
 L322] does:

 {{{#!php
 $is_writable_template_directory = wp_is_writable( get_template_directory()
 . '/..' );
 }}}

 If the current theme exists outside of `ABSPATH` and is symlink'd into
 `ABSPATH . 'wp-content/themes` (which I do for all the bundled themes for
 all sites on my local dev machine) then what is actually being checked is
 whether that directory outside of `ABSPATH` is writable, not whether the
 theme directory is writable.

 Changing that line to:

 {{{#!php
 $is_writable_template_directory = wp_is_writable( dirname(
 get_template_directory() ) );
 }}}

 correctly tests whether the theme directory is writable.

 Additionally, when running on a Windows machine, `wp_is_writable()` calls
 `win_is_writable()`, which creates and then unlinks a tmp file.  Because
 of the directory traversal in the path, the unlink fails when the template
 directory is a symlink...which leaves the tmp file in the parent directory
 of the symlink'd theme resides outside of `ABSPATH`.  Changing the
 argument to `wp_is_writable()` to use `dirname()` instead of directory
 traversal also fixes that problem.

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Ticket URL: <https://core.trac.wordpress.org/ticket/48199>
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