JsonResponse::setData with JSON_THROW_ON_ERROR can throw when there is no error

[lt]

Symfony version(s) affected: 4.2.5

Description

JsonResponse::setData checks json_last_error to determine whether or not encoding was successful, however when JSON_THROW_ON_ERROR is set as an encoding option, the error state is not cleared.

This means when a previous JSON operation that does not use JSON_THROW_ON_ERROR has failed, JsonResponse::setData will throw an exception even when the encode operation was successful.

How to reproduce

<?php declare(strict_types=1);

require 'vendor/autoload.php';

$response = new \Symfony\Component\HttpFoundation\JsonResponse();
$response->setEncodingOptions(JSON_THROW_ON_ERROR);

// Commenting this out prevents the exception from setData
json_decode('bad data, but carry on');

$response->setData('this is fine');

PHP Fatal error:  Uncaught InvalidArgumentException: Syntax error in /var/www/html/vendor/symfony/http-foundation/JsonResponse.php:152                                                                                                       
Stack trace:
#0 /var/www/html/test.php(12): Symfony\Component\HttpFoundation\JsonResponse->setData('"this is fine"')
#1 {main}
  thrown in /var/www/html/vendor/symfony/http-foundation/JsonResponse.php on line 152

Possible Solution

Check encoding options for JSON_THROW_ON_ERROR when checking json_last_error()

Additional context

https://bugs.php.net/bug.php?id=77997

[nicolas-grekas]

Related to https://externals.io/message/105653

[joris-ati4]

I am currently looking into this issue and am not sure we can prevent this behaviour because it would be impossible to know if the user did a json_(encode / decode) before calling setData with JSON_THROW_ERROR as encodingOption.

Even if the user set the encodingOption to JSON_THROW_ERROR and we added a check before doing json_last_error(), we cannot now which json function has thrown the error. Another problem is that the try catch only works for php7.3 and we have to use json_last_error() for php7.2 and php7.1

Any suggestions on what to do with this issue ?

[JJarrie]

What about just fixing by internal flag's checking? Just to have explicit errors catching in the component, waiting the discussion about the behavior of the global error state be finished.

        if (!($this->encodingOptions & 4194304) && JSON_ERROR_NONE !== json_last_error()) {
            throw new \InvalidArgumentException(json_last_error_msg());
        }

[nicolas-grekas]

Please check #31860

[nicolas-grekas]

Better fix in #31869