Valid table names are concatted with a '.' to a valid regions names is also a valid table name, and lead to the incorrect interpretation.
Notice that the table name constraints completely covers all region name constraints and true hfile name constraints. (a valid hfile name is a valid part of a table name, and a valid enc region name is a valid part of a table name.
Currently the hfilelink filename convention is <hfile>
<region><table>. Unfortunately, making a ref to this uses the name <hfile> <region><table>.<parentregion> – the contactnation of <table>.<parentregion> is a valid table name used to get interpreted as such. The fix in HBASE-7339 requires a FileNotFoundException before going down the hfile link resolution path.
Regardless of what we do, we need to add some char invalid for table names to the hfilelink or reference filename convention.
Suggestion: if we changed the order of the hfile-link name we could avoid some of the confusion – <table>@<region>-<hfile>.<parentregion> (or some other separator char than '@') could be used to avoid handling on the initial filenotfoundexception but I think we'd still need a good chunk of the logic to handle opening half-storefile reader throw a hfilelink.