Opening file as shared?

Is there a way to open an InputFileStream as shared?

If a user shift+drags (?) our plugin from one insert slot in ProTools to another, then it copies the plug-in to that second insert slot. But our plugin uses an external file for some audio data that it records, and that second instance needs to access that file.

From what i see in the FileInputStream class, though, there does not appear to be a way to set the flag that this file can be shared with other readers. Here is the code in question:

void FileInputStream::openHandle()
auto f = open (file.getFullPathName().toUTF8(), O_RDONLY);

if (f != -1)
    fileHandle = fdToVoidPointer (f);
    status = getResultForErrno();


(This is on the Mac, by the way.)

I think that in order to share the file, the flag needs to be O_RDONLY| O_NONBLOCK, but this code does not allow adding that flag. Is there some way currently to allow this? Do I need to write my own InputFileStream class to allow that?