VFS_POINTER
The SQLITE_FCNTL_VFS_POINTER opcode finds a pointer to the top-level VFSes currently in use. The argument X in sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be of type "sqlite3_vfs **". This opcode will set *X to a pointer to the top-level VFS. When there are multiple VFS shims in the stack, this opcode finds the upper-most shim only.