SCSI(2) SCSI(2)
NAME
openscsi, scsiready, scsi, scsicmd, scsierror - SCSI device
operations
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <disk.h>
typedef struct Scsi {
char *inquire;
int rawfd;
int nchange;
ulong changetime;
};
Scsi* openscsi(char *devdir)
void closescsi(Scsi *s)
int scsiready(Scsi *s)
int scsi(Scsi *s, uchar *cmd, int ncmd,
void *data, int ndata, int dir)
int scsicmd(Scsi *s, uchar *cmd, int ncmd,
void *data, int ndata, int dir)
char* scsierror(int asc, int ascq)
int scsiverbose;
DESCRIPTION
These routines provide an interface to a SCSI or ATAPI
device via sd(3).
Openscsi attempts to open the file devdir/raw and use it to
send raw SCSI commands. On success, it reads the device's
inquiry string and stores it in in returned Scsi structure.
Closescsi closes the connection and frees the Scsi struc-
ture.
Scsiready sends the ``unit ready'' command up to three
times, returning zero if the unit responds that it is ready,
or -1 on error.
Scsierror returns a textual description of the SCSI status
denoted by the ASC and ASCQ sense codes. The description is
found by consulting /sys/lib/scsicodes. The returned string
will be overwritten by the next call to scsierror.
Page 1 Plan 9 (printed 11/23/24)
SCSI(2) SCSI(2)
Scsi and scsicmd execute a single SCSI command on the named
device. There should be ncmd bytes of command data in cmd;
if dir is Sread, a successful operation will store up to
ndata bytes into data, returning the number of bytes stored.
If dir is Swrite, the ndata bytes beginning at data are
transmitted as the data argument to the command, and the
number of bytes written is returned. If dir is Snone, data
and ndata are ignored. On error, scsi and scsicmd return
-1. Scsicmd simply issues the command and returns the
result; scsi works a bit harder and is the more commonly
used routine. Scsi attempts to send the command; if it is
successful, scsi returns what scsicmd returned. Otherwise,
scsi sends a request sense command to obtain the reason for
the failure, sends a unit ready command in an attempt to
bring the unit out of any inconsistent states, and tries
again. If the second try fails, scsi sends the request
sense and unit ready commands again and then uses scsierror
to set errstr with a reason for failure.
The nchange and changetime fields in the Scsi structure
record the number of times a media change has been detected,
and the time when the current media was inserted into the
drive (really the first time a SCSI command was issued after
it was inserted). They are maintained by scsi.
If scsiverbose is set, these commands will produce a fair
amount of debugging output on file descriptor 2 when SCSI
commands fail.
FILES
/sys/lib/scsicodes
List of textual messages corresponding to SCSI error
codes; consulted by scsierror.
SOURCE
/sys/src/libdisk/scsi.c
SEE ALSO
sd(3), scuzz(8)
Page 2 Plan 9 (printed 11/23/24)