Query: Ensure that the page parameter is scalar in WP_Query::get_posts().

The `page` query var only accepts a scalar value and passes the value through functions that assume a scalar value.

Adding an extra guard condition does not affect its functionality but does avoid a PHP fatal error for `trim()` when a non-scalar value such as an array is passed.

Follow-up to [2535], [53891].

Props brookedot, rlmc, mukesh27, SergeyBiryukov.
Fixes #56558.

git-svn-id: https://develop.svn.wordpress.org/trunk@56815 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-query.php

@@ -2020,8 +2020,7 @@ class WP_Query {
 		}
 
 		if ( isset( $q['page'] ) ) {
-			$q['page'] = trim( $q['page'], '/' );
-			$q['page'] = absint( $q['page'] );
+			$q['page'] = is_scalar( $q['page'] ) ? absint( trim( $q['page'], '/' ) ) : 0;
 		}
 
 		// If true, forcibly turns off SQL_CALC_FOUND_ROWS even when limits are present.

tests/phpunit/tests/query/invalidQueries.php

@@ -159,4 +159,20 @@ class Tests_Query_InvalidQueries extends WP_UnitTestCase {
 		// Only the published post should be returned.
 		$this->assertCount( 1, $query->posts );
 	}
+
+	/**
+	 * Ensure a non-scalar page parameter does not throw a fatal error for trim().
+	 *
+	 * @ticket 56558
+	 * @covers WP_Query::get_posts
+	 */
+	public function test_non_scalar_page_value() {
+		$query = new WP_Query(
+			array(
+				'page' => array( 1, 2, 3 ),
+			)
+		);
+
+		$this->assertSame( 0, $query->query_vars['page'] );
+	}
 }