TYPO3 Core

Please don't wonder if you have seen this on stackoverflow first. But I think this here is the better place :)

I'm a little bit confused about the identifier of a FAL driver. I try to write a driver but the delivered identifier from storage is not always consistent. Currently the problem is to hide the _processed_ folder in listing. So I found out, the condition ask for _processed_/. But shouldn't it be /_processed_/ with beginning slash?

So when I fetch the files from my storage I use for all identifiers a beginning and tailing slash:

/my/directory/
/my/directory/file.ext

But when e.g. the file is processing it will be saved in the DB as

_processed_/preview_test122_4f666b3c4b.jpg

not as expected as

/_processed_/preview_test122_4f666b3c4b.jpg

When I remove the beginning slash at fetching, then some functions work, but other not without canonical the path.

How can I found out, when the incoming $identifier of my driver is correct or must be canonicalized? I don't whant to overload the extension with the function canonicalizeAndCheckFileIdentifier()...

using TYPO3 v6.2.4

More debugging:

1. Deleted the processing directory on storage
2. do listing
3. debug "createFolder" function to get returned identifier: -> /_processed_/
4. debug returned identifier in getProcessingFolder in ResourceStorage.php: -> /_processed_/
   everthing correct so far
5. do linsting again
6. debug getProcessingFolder: -> _processed_/
   missing beginning slash