FileNameLengthConstraintValidator.php

<?php

namespace Drupal\file\Plugin\Validation\Constraint;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

/**
 * Validates the file name length constraint.
 */
class FileNameLengthConstraintValidator extends BaseFileConstraintValidator {
    
    /**
     * {@inheritdoc}
     */
    public function validate(mixed $value, Constraint $constraint) : void {
        $file = $this->assertValueIsFile($value);
        if (!$constraint instanceof FileNameLengthConstraint) {
            throw new UnexpectedTypeException($constraint, FileNameLengthConstraint::class);
        }
        if (!$file->getFilename()) {
            $this->context
                ->addViolation($constraint->messageEmpty);
        }
        if (mb_strlen($file->getFilename()) > $constraint->maxLength) {
            $this->context
                ->addViolation($constraint->messageTooLong, [
                '%maxLength' => $constraint->maxLength,
            ]);
        }
    }

}