[wp-trac] [WordPress Trac] #64612: WP_Duotone: Fatal error when duotone attribute is an array instead of a string

[WordPress Trac]

#64612: WP_Duotone: Fatal error when duotone attribute is an array instead of a
string
------------------------------+--------------------------------------
 Reporter:  jorgefilipecosta  |      Owner:  (none)
     Type:  defect (bug)      |     Status:  new
 Priority:  normal            |  Milestone:  Awaiting Review
Component:  Editor            |    Version:  trunk
 Severity:  normal            |   Keywords:  has-patch has-unit-tests
  Focuses:                    |
------------------------------+--------------------------------------
 A fatal error occurs in `WP_Duotone::get_slug_from_attribute()` when the
 `$duotone_attr` parameter is an array (custom colors) instead of a string
 (preset reference).

 == Description ==

 When a theme's `theme.json` defines duotone with an array of custom colors
 rather than a preset reference string, a fatal error is thrown:

 {{{
 Fatal error: Uncaught TypeError: preg_match(): Argument #2 ($subject) must
 be of type string, array given in wp-includes/class-wp-duotone.php
 }}}

 The duotone attribute can be:
 1. A preset reference string: `var:preset|duotone|blue-orange` or
 `var(--wp--preset--duotone--blue-orange)`
 2. An array of custom colors: `['#000000', '#ffffff']`
 3. A CSS string: `unset`

 The current code assumes the attribute is always a string when checking
 for presets, which causes a fatal error when an array of custom colors is
 passed.

 == Steps to Reproduce ==

 1. Create a theme with a `theme.json` that uses an array value for
 duotone:
 {{{
 {
   "styles": {
     "blocks": {
       "core/image": {
         "filter": {
           "duotone": ["#000000", "#ffffff"]
         }
       }
     }
   }
 }
 }}}
 2. Activate the theme
 3. Load any page - fatal error occurs

 == Expected Results ==

 No fatal error. Custom duotone colors should be processed correctly.

 == Actual Results ==

 Fatal error is thrown due to `preg_match()` receiving an array instead of
 a string.

 == Solution ==

 Add type checks to ensure `$duotone_attr` is a string before attempting to
 parse it:

 1. `get_slug_from_attribute()` - Returns empty string for non-string input
 2. `is_preset()` - Returns false for non-string input
 3. `get_all_global_style_block_names()` - Skips non-string duotone
 attributes

 == Related ==

 * Gutenberg PR: https://github.com/WordPress/gutenberg/pull/75283
 * Props: xavier-lc

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64612>
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