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