.. _structures-possibleinfiniteloop:

.. _possible-infinite-loop:

Possible Infinite Loop
++++++++++++++++++++++

  Loops on files that can't be open results in infinite loop.

`fgets() <https://www.php.net/fgets>`_, and functions like `fgetss() <https://www.php.net/fgetss>`_, `fgetcsv() <https://www.php.net/fgetcsv>`_, `fread() <https://www.php.net/fread>`_, return false when they finish reading, or can't access the file. 

In case the file is not accessible, comparing the `result <https://www.php.net/result>`_ of the reading to something that is falsy, leads to a permanent valid condition. The execution will only finish when the ``max_execution_time`` is reached. 
It is recommended to check the file resources when they are opened, and always use === or !== to compare readings. `feof() <https://www.php.net/feof>`_ is also a reliable function here.

.. code-block:: php
   
   <?php
   
   $file = fopen('/path/to/file.txt', 'r');
   // when fopen() fails, the next loops is infinite
   // fgets() will always return false, and while will always be true. 
   while($line = fgets($file) != 'a') {
       doSomething();
   }
   
   ?>
Connex PHP features
-------------------

  + `loop <https://php-dictionary.readthedocs.io/en/latest/dictionary/loop.ini.html>`_


Suggestions
___________

* Add a check before using the result of the method.
* Add a counter to break the loop after a limit of loops.




Specs
_____

+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Short name   | Structures/PossibleInfiniteLoop                                                                                         |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Rulesets     | :ref:`All <ruleset-All>`, :ref:`Analyze <ruleset-Analyze>`, :ref:`Changed Behavior <ruleset-Changed-Behavior>`          |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Exakat since | 1.1.5                                                                                                                   |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| PHP Version  | All                                                                                                                     |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Severity     | Critical                                                                                                                |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Time To Fix  | Quick (30 mins)                                                                                                         |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Precision    | Very high                                                                                                               |
+--------------+-------------------------------------------------------------------------------------------------------------------------+
| Available in | `Entreprise Edition <https://www.exakat.io/entreprise-edition>`_, `Exakat Cloud <https://www.exakat.io/exakat-cloud/>`_ |
+--------------+-------------------------------------------------------------------------------------------------------------------------+