IN: File access property list identifier. For most drivers, the value will be H5P_DEFAULT. For the FAMILY or MULTI drivers, this value should be defined through the property list functions: H5Pset_family_offset for the FAMILY driver and H5Pset_multi_type for theMULTI driver.
OUT: Pointer to the file handle being used by the low-level virtual file driver.
Given the file identifier file_id and the file access property list fapl_id, H5Fget_vfd_handle returns a pointer to the file handle from the low-level file driver currently being used by the HDF5 library for file I/O.
Returns a non-negative value if successful; otherwise returns a negative value.