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<title>[52370] trunk: Formatting: Use `is_scalar()` in `sanitize_key()`.</title>
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<dt style="float: left; width: 6em; font-weight: bold">Revision</dt> <dd><a style="font-weight: bold" href="https://core.trac.wordpress.org/changeset/52370">52370</a><script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","description":"Review this Commit","action":{"@type":"ViewAction","url":"https://core.trac.wordpress.org/changeset/52370","name":"Review Commit"}}</script></dd>
<dt style="float: left; width: 6em; font-weight: bold">Author</dt> <dd>hellofromTonya</dd>
<dt style="float: left; width: 6em; font-weight: bold">Date</dt> <dd>2021-12-14 14:59:33 +0000 (Tue, 14 Dec 2021)</dd>
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<pre style='padding-left: 1em; margin: 2em 0; border-left: 2px solid #ccc; line-height: 1.25; font-size: 105%; font-family: sans-serif'>Formatting: Use `is_scalar()` in `sanitize_key()`.

This is a follow-up to <a href="https://core.trac.wordpress.org/changeset/52292">[52292]</a> which introduced `is_string()` to check the given key is a string to be sanitized, else the key is set to an empty string. 

`sanitize_key()` is clearly identified (in the documentation) to only work with ''string'' keys. However, it had a bug in it that allowed non-strings to pass through it:
* A non-scalar "key" would throw a PHP Warning (which was resolved in <a href="https://core.trac.wordpress.org/changeset/52292">[52292]</a>. 
* A non-string scalar "key" was handled by the PHP native `strtolower()` which converted it into a string.

While `is_string()` is valid, non-string scalar types passed as the key to be sanitized were being set to an empty string. Given that `strtolower()` handles these without error or deprecation as of PHP 8.1, `is_scalar()` protects the website from issues while retaining the past behavior of converting integer keys (for example) into a string.

Changes include:
* Using `is_scalar()` instead of `is_string()`
* Refactor for readability and less code
* More tests

Please note, this does not change the behavior of the function, nor redefine it to now accept non-string scalars.

References:
* https://developer.wordpress.org/reference/functions/sanitize_key/
* https://www.php.net/manual/en/function.strtolower.php

Follow-up <a href="https://core.trac.wordpress.org/changeset/52292">[52292]</a>.

Props wppunk, hellofromTonya, costdev, jrf.
Fixes <a href="https://core.trac.wordpress.org/ticket/54160">#54160</a>.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpincludesformattingphp">trunk/src/wp-includes/formatting.php</a></li>
<li><a href="#trunktestsphpunittestsformattingsanitizeKeyphp">trunk/tests/phpunit/tests/formatting/sanitizeKey.php</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunksrcwpincludesformattingphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/src/wp-includes/formatting.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/src/wp-includes/formatting.php      2021-12-14 09:47:51 UTC (rev 52369)
+++ trunk/src/wp-includes/formatting.php        2021-12-14 14:59:33 UTC (rev 52370)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -2132,30 +2132,26 @@
</span><span class="cx" style="display: block; padding: 0 10px">  *
</span><span class="cx" style="display: block; padding: 0 10px">  * @since 3.0.0
</span><span class="cx" style="display: block; padding: 0 10px">  *
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">- * @param string $key String key
- * @return string Sanitized key
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ * @param string $key String key.
+ * @return string Sanitized key.
</ins><span class="cx" style="display: block; padding: 0 10px">  */
</span><span class="cx" style="display: block; padding: 0 10px"> function sanitize_key( $key ) {
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-        $raw_key = $key;
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ $sanitized_key = '';
</ins><span class="cx" style="display: block; padding: 0 10px"> 
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-        if ( ! is_string( $key ) ) {
-               $key = '';
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ if ( is_scalar( $key ) ) {
+               $sanitized_key = strtolower( $key );
+               $sanitized_key = preg_replace( '/[^a-z0-9_\-]/', '', $sanitized_key );
</ins><span class="cx" style="display: block; padding: 0 10px">         }
</span><span class="cx" style="display: block; padding: 0 10px"> 
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-        if ( '' !== $key ) {
-               $key = strtolower( $key );
-               $key = preg_replace( '/[^a-z0-9_\-]/', '', $key );
-       }
-
</del><span class="cx" style="display: block; padding: 0 10px">         /**
</span><span class="cx" style="display: block; padding: 0 10px">         * Filters a sanitized key string.
</span><span class="cx" style="display: block; padding: 0 10px">         *
</span><span class="cx" style="display: block; padding: 0 10px">         * @since 3.0.0
</span><span class="cx" style="display: block; padding: 0 10px">         *
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-         * @param string $key     Sanitized key.
-        * @param string $raw_key The key prior to sanitization.
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+  * @param string $sanitized_key Sanitized key.
+        * @param string $key           The key prior to sanitization.
</ins><span class="cx" style="display: block; padding: 0 10px">          */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-        return apply_filters( 'sanitize_key', $key, $raw_key );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ return apply_filters( 'sanitize_key', $sanitized_key, $key );
</ins><span class="cx" style="display: block; padding: 0 10px"> }
</span><span class="cx" style="display: block; padding: 0 10px"> 
</span><span class="cx" style="display: block; padding: 0 10px"> /**
</span></span></pre></div>
<a id="trunktestsphpunittestsformattingsanitizeKeyphp"></a>
<div class="modfile"><h4 style="background-color: #eee; color: inherit; margin: 1em 0; padding: 1.3em; font-size: 115%">Modified: trunk/tests/phpunit/tests/formatting/sanitizeKey.php</h4>
<pre class="diff"><span>
<span class="info" style="display: block; padding: 0 10px; color: #888">--- trunk/tests/phpunit/tests/formatting/sanitizeKey.php      2021-12-14 09:47:51 UTC (rev 52369)
+++ trunk/tests/phpunit/tests/formatting/sanitizeKey.php        2021-12-14 14:59:33 UTC (rev 52370)
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -7,16 +7,21 @@
</span><span class="cx" style="display: block; padding: 0 10px"> class Tests_Formatting_SanitizeKey extends WP_UnitTestCase {
</span><span class="cx" style="display: block; padding: 0 10px"> 
</span><span class="cx" style="display: block; padding: 0 10px">        /**
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-         * @ticket 54160
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+  * @ticket       54160
</ins><span class="cx" style="display: block; padding: 0 10px">          * @dataProvider data_sanitize_key
</span><span class="cx" style="display: block; padding: 0 10px">         *
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-         * @param mixed $key       The key to sanitize.
-        * @param mixed $expected  The expected value.
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+  * @param string $key      The key to sanitize.
+        * @param string $expected The expected value.
</ins><span class="cx" style="display: block; padding: 0 10px">          */
</span><span class="cx" style="display: block; padding: 0 10px">        public function test_sanitize_key( $key, $expected ) {
</span><span class="cx" style="display: block; padding: 0 10px">                $this->assertSame( $expected, sanitize_key( $key ) );
</span><span class="cx" style="display: block; padding: 0 10px">        }
</span><span class="cx" style="display: block; padding: 0 10px"> 
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+        /**
+        * Data provider.
+        *
+        * @return array
+        */
</ins><span class="cx" style="display: block; padding: 0 10px">         public function data_sanitize_key() {
</span><span class="cx" style="display: block; padding: 0 10px">                return array(
</span><span class="cx" style="display: block; padding: 0 10px">                        'an empty string key'            => array(
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -23,22 +28,6 @@
</span><span class="cx" style="display: block; padding: 0 10px">                                'key'      => '',
</span><span class="cx" style="display: block; padding: 0 10px">                                'expected' => '',
</span><span class="cx" style="display: block; padding: 0 10px">                        ),
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-                        'a null key'                     => array(
-                               'key'      => null,
-                               'expected' => '',
-                       ),
-                       'an int 0 key'                   => array(
-                               'key'      => 0,
-                               'expected' => '',
-                       ),
-                       'a true key'                     => array(
-                               'key'      => true,
-                               'expected' => '',
-                       ),
-                       'an array key'                   => array(
-                               'key'      => array( 'Howdy, admin!' ),
-                               'expected' => '',
-                       ),
</del><span class="cx" style="display: block; padding: 0 10px">                         'a lowercase key with commas'    => array(
</span><span class="cx" style="display: block; padding: 0 10px">                                'key'      => 'howdy,admin',
</span><span class="cx" style="display: block; padding: 0 10px">                                'expected' => 'howdyadmin',
</span><span class="lines" style="display: block; padding: 0 10px; color: #888">@@ -71,20 +60,81 @@
</span><span class="cx" style="display: block; padding: 0 10px">        }
</span><span class="cx" style="display: block; padding: 0 10px"> 
</span><span class="cx" style="display: block; padding: 0 10px">        /**
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-         * @ticket 54160
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+  * @ticket       54160
+        * @dataProvider data_sanitize_key_nonstring_scalar
</ins><span class="cx" style="display: block; padding: 0 10px">          *
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-         * @covers WP_Hook::sanitize_key
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+  * @param mixed  $key      The key to sanitize.
+        * @param string $expected The expected value.
</ins><span class="cx" style="display: block; padding: 0 10px">          */
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-        public function test_filter_sanitize_key() {
-               $key = 'Howdy, admin!';
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ public function test_sanitize_key_nonstring_scalar( $key, $expected ) {
+               $this->assertSame( $expected, sanitize_key( $key ) );
+       }
</ins><span class="cx" style="display: block; padding: 0 10px"> 
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+        /**
+        * Data provider.
+        *
+        * @return array
+        */
+       public function data_sanitize_key_nonstring_scalar() {
+               return array(
+                       'integer type'  => array(
+                               'key'      => 0,
+                               'expected' => '0',
+                       ),
+                       'boolean true'  => array(
+                               'key'      => true,
+                               'expected' => '1',
+                       ),
+                       'boolean false' => array(
+                               'key'      => false,
+                               'expected' => '',
+                       ),
+                       'float type'    => array(
+                               'key'      => 0.123,
+                               'expected' => '0123',
+                       ),
+               );
+       }
+
+       /**
+        * @ticket       54160
+        * @dataProvider data_sanitize_key_with_non_scalars
+        *
+        * @param mixed $nonscalar_key A non-scalar data type given as a key.
+        */
+       public function test_sanitize_key_with_non_scalars( $nonscalar_key ) {
</ins><span class="cx" style="display: block; padding: 0 10px">                 add_filter(
</span><span class="cx" style="display: block; padding: 0 10px">                        'sanitize_key',
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-                        static function( $key ) {
-                               return 'Howdy, admin!';
-                       }
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+                 function ( $sanitized_key, $key ) use ( $nonscalar_key ) {
+                               $this->assertEmpty( $sanitized_key, 'Empty string not passed as first filtered argument' );
+                               $this->assertSame( $nonscalar_key, $key, 'Given unsanitized key not passed as second filtered argument' );
+                               return $sanitized_key;
+                       },
+                       10,
+                       2
</ins><span class="cx" style="display: block; padding: 0 10px">                 );
</span><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+                $this->assertEmpty( sanitize_key( $nonscalar_key ), 'Non-scalar key did not return empty string' );
+       }
</ins><span class="cx" style="display: block; padding: 0 10px"> 
</span><del style="background-color: #fdd; text-decoration:none; display:block; padding: 0 10px">-                $this->assertSame( $key, sanitize_key( $key ) );
</del><ins style="background-color: #dfd; text-decoration:none; display:block; padding: 0 10px">+ /**
+        * Data provider.
+        *
+        * @return array
+        */
+       public function data_sanitize_key_with_non_scalars() {
+               return array(
+                       'array type' => array(
+                               'key'      => array( 'key' ),
+                               'expected' => '',
+                       ),
+                       'null'       => array(
+                               'key'      => null,
+                               'expected' => '',
+                       ),
+                       'object'     => array(
+                               'key'      => new stdClass(),
+                               'expected' => '',
+                       ),
+               );
</ins><span class="cx" style="display: block; padding: 0 10px">         }
</span><span class="cx" style="display: block; padding: 0 10px"> }
</span></span></pre>
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