Certain characters in folder name cause image upload to fail

[bassplayer7]

Overview

If a ? character is added to Advanced -> Folder Name, it will cause errors to be thrown when uploading images. The images appear after removing the ? from the folder name. It is possible that other characters cause issues as well.

Steps to Reproduce:

1. Create a modular with a folder name containing a ? along with other alpha-numeric characters.
2. Save the page and attempt to upload images.
3. An error appears: move_uploaded_file([path to file *without* a ?]/image.jpg): failed to open stream: No such file or directory
4. Remove ? from Folder Name
5. Images upload smoothly.

[flaviocopes]

The problem is ? is a special character. We should disallow changing a folder name (or creating a new one) to contain ? in the first place, as it's going to be interpreted by the browser unless urlencoded. The problem seems linked to the fact you can first save as yourfolder? but then saving a second time, without any other change, the folder is back to yourfolder.

[bassplayer7]

Obviously someone could set the folder name to include a ? but in this case everything was done through the admin panel. It seemed to me that it shouldn't let any invalid characters be saved.

[flaviocopes]

Yes if we state ? (as with & or other special chars reserved in URIs) are not supported, it should be denied when saving.

[bassplayer7]

Or, as a possible alternative, what about automatically swapping any unacceptable characters out for - to make it URL friendly. I'm thinking of something like this:

$url = str_replace(' ', '-', strtolower($url));
$url = preg_replace('/[^\da-z\-]/i', '-', $url);
$url = preg_replace('/-+/', '-', $url);
$url = rtrim(ltrim($url, '-'), '-');

The end goal would be to turn My(?) Folder Name! into my-folder-name.