Fd returns the integer file descriptor referencing the open file.

FSize returns the file size.

MMap calls the MMap system call.

MSync calls the msync system call.

MUnmap calls the MUnmap system call.

Offset returns the valid offset.

Open opens a MMap.

ProtFlags returns prot and flags by Prot p.

COPY represents the copy prot.

EXEC represents the exec prot.

READ represents the read prot.

WRITE represents the write prot.

Prot is the protection flag.