- impl:mmapped src dst len #!key (offset 0.0)procedure
Sends a file by mapping it into the memory and do repeated writes. source is the filedescriptor of an already opened file. destination is the filedescriptor of an already opened file (can be a socket). len is the size of the file in bytes as e.g. retrieved by (file-size). offset is the offset where to start the read. This procedure returns the amount of bytes successfully written.