MongoDBFormatter can affect passed by reference arguments when writing trace to log

[FloatingMaster]

Steps to reproduce
Error handler:

public function handleError($type, $message, $file, $line) 
{
  $exception = new \ErrorException();
  $trace = $exception->getTrace();
  array_shift($trace);

  $this->getLogger()->log($this->errorTypeToLogLevel($type), $message, $trace)
}

Next in MongoDBFormatter::formatArray we have

foreach ($record as $name => $value) {
  ...
  } elseif (is_object($value)) {
    $record[$name] = $this->formatObject($value, $nestingLevel + 1);
  }
}

If there was any pass-by-reference arguments (e.g. foo(MyObj &$obj)) the object by reference will be replaced by formatted array.

Example:

public function testFoo()
{
  $a = new \stdClass();
    	
  var_dump($a);
  $this->foo($a);

  var_dump($a);

 }

public function foo(\stdClass &$a)
{
  $b = [];
  $b = $b['non-existing'];
}

Output:

class stdClass#134 (0) {
}
array(1) {
  'class' =>
  string(8) "stdClass"
}

[Seldaek]

This probably should be fixed (or at least checked if they are affected) for all normalizers.

[juan-morales]

But, in such a case, what is adviced to do here in order to "fix" this "issue"?

As far as I know , there is no reliable way to check if a variable is a reference in PHP, and "cloning just in case" is not an option.

Am I missing something here?

[Seldaek]

It might just be about assigning things to a new array instead of the same to make sure we copy the stack trace and get rid of references.

I'm not sure either.. Doesn't seem like a super critical issue tbh, it's so unlikely to happen.

[FloatingMaster]

We solved the issue by recursivly converting record to array of simple type fields. Objects are converted to array through bsonSerialize, jsonSerialize or reflections

[juan-morales]

@FloatingMaster you applied that code on private code? Can we see it so we can better understand what was suppose to be done?