If doing achunked upload the mimetype of the folder would otherwise be
guessed from the path. Which always returned application/octet-stream.
If an access control rule to block that is in place this means that all
chunked uploads fail hard in directories as the isCreatable on the
directory always fails.
Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>
PHPDoc (of the public API) says that this method returns string but it also returns null, which is not allowed in some method calls. This fixes that behaviour and returns an empty string and fixes all code paths that explicitly checked for null to be still compliant.
Found while enabling the strict_typing for lib/private for the PHP7+ migration.
Signed-off-by: Morris Jobke <hey@morrisjobke.de>
