This library is meant for userland access to SCSI devices.  The
library is part of the FreeBSD distribution but works for
NetBSD as well.

The functions of the library use the SCIOCCOMMAND ioctl(2) of
the NetBSD SCSI subsystem to provide user level access to SCSI
commands.  The programmer must know the SCSI CDB (Command
Descriptor Block) to perform the desired command.  These
functions assist in building up the CDB, submitting it to the
SCSI subsystem, and decoding the result.