Symfony version(s) affected

6.2.4

Description

Hi, the new extensions config for the File Constraint does not normalize the checked extensions, nor the configured ones). So for example, when I allow the 'xml' extension and someone uploads a valid XML-file called 'MY.XML', that is considered as invalid.

As a workaround, I can also configure XML as a second allowed extension, but then someone will come and upload a 'My.Xml' next and so forth. Many smartphones name their camera files with uppercased extensions, so more often that should affect the jpg or m4v extensions.

How to reproduce

Configure a File Constraint and set the extensions config:

new File(
    extensions: ['xml'],
),

Then upload an XML-file with a non-lowercase file-extension like xml.XML and observe that it is considered as a not allowed file-extension. Validate that by renaming it to xml.xml, upload it again and observe that it is considered as an allowed file-extension.

Or just have a look into the code of the FileValidator.php inside the block starting with if ($constraint->extensions) { to see how the check is currently implemented.

Possible Solution

From my point of view, the check should instead of if ($fileExtension !== $k) do something like if (mb_strtolower($fileExtension) !== mb_strtolower($k)) or normalize the checked (and configured) extensions in any other way so that the check is case-insensitive.

I could send a PR for that, if that would be an accepted solution.

Additional Context

No response