Taxonomy: Return a descriptive WP_Error when a term name exceeds the DB column length

src/wp-includes/taxonomy.php

@@ -2401,6 +2401,41 @@ function wp_get_object_terms( $object_ids, $taxonomies, $args = array() ) {
 	return apply_filters( 'wp_get_object_terms', $terms, $object_ids, $taxonomies, $args );
 }
 
+/**
+ * Checks a term name against the maximum length allowed by the `wp_terms` table's `name` column.
+ *
+ * @since 7.2.0
+ * @access private
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
+ *
+ * @param string $name Term name to check.
+ * @return true|WP_Error True if the name fits the column, WP_Error otherwise.
+ */
+function _wp_check_term_name_length( $name ) {
+	global $wpdb;
+
+	$max_length = 200;
+	$col_length = $wpdb->get_col_length( $wpdb->terms, 'name' );
+
+	if ( is_array( $col_length ) && ! empty( $col_length['length'] ) ) {
+		$max_length = (int) $col_length['length'];
+	}
+
+	if ( mb_strlen( $name ) > $max_length ) {
+		return new WP_Error(
+			'term_name_too_long',
+			sprintf(
+				/* translators: %d: Maximum number of characters. */
+				__( 'Term name may not be longer than %d characters.' ),
+				$max_length
+			)
+		);
+	}
+
+	return true;
+}
+
 /**
  * Adds a new term to the database.
  *
@@ -2520,6 +2555,11 @@ function wp_insert_term( $term, $taxonomy, $args = array() ) {
 		return new WP_Error( 'invalid_term_name', __( 'Invalid term name.' ) );
 	}
 
+	$name_length_error = _wp_check_term_name_length( $name );
+	if ( is_wp_error( $name_length_error ) ) {
+		return $name_length_error;
+	}
+
 	$slug_provided = ! empty( $args['slug'] );
 	if ( ! $slug_provided ) {
 		$slug = sanitize_title( $name );
@@ -3312,6 +3352,11 @@ function wp_update_term( $term_id, $taxonomy, $args = array() ) {
 		return new WP_Error( 'empty_term_name', __( 'A name is required for this term.' ) );
 	}
 
+	$name_length_error = _wp_check_term_name_length( $name );
+	if ( is_wp_error( $name_length_error ) ) {
+		return $name_length_error;
+	}
+
 	if ( (int) $parsed_args['parent'] > 0 && ! term_exists( (int) $parsed_args['parent'] ) ) {
 		return new WP_Error( 'missing_parent', __( 'Parent term does not exist.' ) );
 	}

tests/phpunit/tests/term/wpInsertTerm.php

@@ -907,6 +907,39 @@ public function test_wp_insert_term_with_empty_name_after_db_sanitization() {
 		$this->assertSame( 'invalid_term_name', $term->get_error_code() );
 	}
 
+	/**
+	 * @ticket 36610
+	 */
+	public function test_wp_insert_term_name_too_long_should_return_wp_error() {
+		register_taxonomy( 'wptests_tax', 'post' );
+		$found = wp_insert_term( str_repeat( 'a', 201 ), 'wptests_tax' );
+
+		$this->assertWPError( $found );
+		$this->assertSame( 'term_name_too_long', $found->get_error_code() );
+	}
+
+	/**
+	 * @ticket 36610
+	 */
+	public function test_wp_insert_term_name_at_max_length_should_succeed() {
+		register_taxonomy( 'wptests_tax', 'post' );
+		$found = wp_insert_term( str_repeat( 'a', 200 ), 'wptests_tax' );
+
+		$this->assertNotWPError( $found );
+	}
+
+	/**
+	 * @ticket 36610
+	 */
+	public function test_wp_insert_term_name_length_should_be_counted_in_characters_not_bytes() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		// 200 multibyte characters fit the column, even though their byte length is far greater than 200.
+		$found = wp_insert_term( str_repeat( 'é', 200 ), 'wptests_tax' );
+
+		$this->assertNotWPError( $found );
+	}
+
 	/** Helpers */
 
 	public function deleted_term_cb( $term, $tt_id, $taxonomy, $deleted_term, $object_ids ) {

tests/phpunit/tests/term/wpUpdateTerm.php

@@ -802,4 +802,45 @@ public function test_wp_update_term_with_null_get_term() {
 		$this->assertWPError( $found );
 		$this->assertSame( 'invalid_term', $found->get_error_code() );
 	}
+
+	/**
+	 * @ticket 36610
+	 */
+	public function test_wp_update_term_name_too_long_should_return_wp_error() {
+		register_taxonomy( 'wptests_tax', 'post' );
+		$t = self::factory()->term->create( array( 'taxonomy' => 'wptests_tax' ) );
+
+		$found = wp_update_term(
+			$t,
+			'wptests_tax',
+			array(
+				'name' => str_repeat( 'a', 201 ),
+			)
+		);
+
+		_unregister_taxonomy( 'wptests_tax' );
+
+		$this->assertWPError( $found );
+		$this->assertSame( 'term_name_too_long', $found->get_error_code() );
+	}
+
+	/**
+	 * @ticket 36610
+	 */
+	public function test_wp_update_term_name_at_max_length_should_succeed() {
+		register_taxonomy( 'wptests_tax', 'post' );
+		$t = self::factory()->term->create( array( 'taxonomy' => 'wptests_tax' ) );
+
+		$found = wp_update_term(
+			$t,
+			'wptests_tax',
+			array(
+				'name' => str_repeat( 'a', 200 ),
+			)
+		);
+
+		_unregister_taxonomy( 'wptests_tax' );
+
+		$this->assertNotWPError( $found );
+	}
 }