[wp-trac] [WordPress Trac] #51913: Potential `unsupported operand types` dashboard fatal on PHP8 + multisite + upload space check

[WordPress Trac]

#51913: Potential `unsupported operand types` dashboard fatal on PHP8 + multisite +
upload space check
-------------------------------------+-------------------------------------
 Reporter:  iandunn                  |       Owner:  iandunn
     Type:  defect (bug)             |      Status:  closed
 Priority:  highest omg bbq          |   Milestone:  5.6
Component:  Administration           |     Version:  trunk
 Severity:  blocker                  |  Resolution:  fixed
 Keywords:  php8 has-patch needs-    |     Focuses:  administration,
  testing                            |  multisite
-------------------------------------+-------------------------------------
Changes (by iandunn):

 * status:  accepted => closed
 * resolution:   => fixed


Comment:

 In [changeset:"49744" 49744]:
 {{{
 #!CommitTicketReference repository="" revision="49744"
 Multisite: Cache absolute `dirsize` paths to avoid PHP 8 fatal.

 r49212 greatly improved the performance of `get_dirsize()`, but also
 changed the structure of the data stored in the `dirsize_cache` transient.
 It stored relative paths instead of absolute ones, and also removed the
 unnecessary `size` array.

 That difference in data structures led to a fatal error in the following
 environment:

 * PHP 8
 * Multisite
 * A custom `WP_CONTENT_DIR` which is not a child of WP's `ABSPATH` folder
 (e.g., [https://roots.io/bedrock/ Bedrock])
 * The `upload_space_check_disabled` option set to `0`

 After upgrading to WP 5.6, the `dirsize_cache` transient still had data in
 the old format. When `wp-admin.php/index.php` was visited,
 `get_space_used()` received an `array` instead of an `int`, and tried to
 divide it by another `int`. PHP 7 would silently cast the arguments to
 match data types, but
 [https://wiki.php.net/rfc/arithmetic_operator_type_checks PHP 8 throws a
 fatal error]:

 `Uncaught TypeError: Unsupported operand types: array / int`

 `recurse_dirsize()` was using `ABSPATH` to convert the absolute paths to
 relative ones, but some upload locations are not located under `ABSPATH`.
 In those cases, `$directory` and `$cache_path` were identical, and that
 triggered the early return of the old `array`, instead of the expected
 `int`.

 In order to avoid that, this commit restores the absolute paths, but
 without the `size` array. It also adds a type check when returning cached
 values. Using absolute paths without `size` has the result of overwriting
 the old data, so that it matches the new format. The type check and
 upgrade routine are additional safety measures.

 Props peterwilsoncc, janthiel, helen, hellofromtonya, francina, pbiron.
 Fixes #51913. See #19879.
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/51913#comment:19>
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