350 lines
11 KiB
Groff
350 lines
11 KiB
Groff
.\" Copyright (c) 1994 HD Associates (hd@world.std.com)
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by HD Associates
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.\" 4. Neither the name of the HD Associaates nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\"
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.Dd November 20, 1994
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.Dt SCSI 3
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.Os
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.Sh NAME
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.Nm scsireq_buff_decode ,
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.Nm scsireq_build ,
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.Nm scsireq_decode ,
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.Nm scsireq_encode
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.Nm scsireq_enter
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.Nm scsireq_new ,
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.Nm scsireq_reset ,
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.Nm SCSIREQ_ERROR ,
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.Nm scsi_open
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.Nm scsi_debug
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.Nm scsi_debug_output
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.Nd SCSI User library
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/scsiio.h>
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.Fd #include <libscsi.h>
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.Ft int
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.Fn scsireq_buff_decode "u_char *ptr, size_t len, char *fmt, ..."
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.Ft struct scsireq *
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.Fn scsireq_build "struct scsireq *s, u_long len, caddr_t buf, u_long flags, char *fmt, ..."
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.Ft int
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.Fn scsireq_decode "struct scsireq *, char *fmt, ..."
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.Ft int
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.Fn scsireq_encode "struct scsireq *, char *fmt, ..."
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.Ft int
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.Fn scsireq_enter "int fid, struct scsireq *s"
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.Ft struct scsireq *
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.Fn scsireq_new void
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.Ft struct scsireq *
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.Fn scsireq_reset "struct scsireq *"
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.Ft int
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.Fn SCSIREQ_ERROR "struct scsireq *"
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.Ft int
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.Fn scsi_open "const char *path, int flags"
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.Ft void
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.Fn scsi_debug "FILE *f, int ret, struct scsireq *s"
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.Ft FILE *
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.Fn scsi_debug_output "char *s"
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.Sh DESCRIPTION
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These functions
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use the SCIOCCOMMAND
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.Xr ioctl 2
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of the FreeBSD SCSI subsystem
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to provide user level access to SCSI commands.
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The programmer must know the SCSI CDB (Command Descriptor
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Block) to perform the desired command. These functions assist in
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building up the CDB, submitting it to the SCSI subsystem, and decoding
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the result.
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.Pp
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Look at the
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.Xr scsi 8
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command before using the library directly - simple programs are
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best implemented as scripts using that facility.
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.Pp
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To provide for security,
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not all devices accept the SCIOCCOMAND ioctl. It is accepted by the
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control device for tape drives, partition D for disk drives, partition C
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for CD ROM drives, and any "unknown" device.
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The "super scsi"
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.Xr ssc 4
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device also accepts the ioctl.
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.Pp
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Most of the SCSI library functions build up and manipulate the
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.Ar scsireq
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structure found in the include file
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.Aq Pa sys/scsiio.h :
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.Bd -literal -offset indent
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#define SENSEBUFLEN 48
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.Pp
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typedef struct scsireq {
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u_long flags; /* info about the request status and type */
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u_long timeout;
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u_char cmd[16]; /* 12 is actually the max */
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u_char cmdlen;
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caddr_t databuf; /* address in user space of buffer */
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u_long datalen; /* size of user buffer (request) */
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u_long datalen_used; /* size of user buffer (used)*/
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u_char sense[SENSEBUFLEN]; /* returned sense will be in here */
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u_char senselen; /* sensedata request size (MAX of SENSEBUFLEN)*/
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u_char senselen_used; /* return value only */
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u_char status; /* what the scsi status was from the adapter */
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u_char retsts; /* the return status for the command */
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int error; /* error bits */
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} scsireq_t;
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.Ed
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.Pp
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.Fn scsireq_new
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allocates a new
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.Ar scsireq
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structure and returns a pointer to it or NULL if it can't allocate
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memory.
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.Pp
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.Fn scsireq_reset
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resets the structure to reasonable values and returns the same pointer passed
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in to it.
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It gracefully handles the NULL pointer passed in to it so that you can
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unconditionally use
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.Ar scsireq_new .
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.Pp
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.Fn scsireq_build
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builds up a scsireq structure based on the information provided in
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the variable argument list.
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It gracefully handles a NULL pointer passed to it.
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.Pp
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.Fr len
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is the length of the data phase; the data transfer direction is
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determined by the
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.Ar flags
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argument.
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.Pp
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.Fr buf
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is the data buffer used during the SCSI data phase. If it is NULL it
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is allocated via malloc and
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.Ar scsireq->databuf
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is set to point to the newly allocated memory.
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.Pp
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.Fr flags
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are the flags defined in
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.Aq Pa sys/scsiio.h :
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.Bd -literal -offset indent
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/* bit defintions for flags */
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#define SCCMD_READ 0x00000001
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#define SCCMD_WRITE 0x00000002
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#define SCCMD_IOV 0x00000004
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#define SCCMD_ESCAPE 0x00000010
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#define SCCMD_TARGET 0x00000020
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.Ed
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Only two of these flags are supported in this release of the software:
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.Fr SCCMD_READ
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indicates a data in phase (a transfer into the user buffer at
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.Ar scsireg->databuf
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), and
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.Fr SCCMD_WRITE
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indicates a data out phase (a transfer out of the user buffer).
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.Pp
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.Fr fmt
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is a CDB format specifier used to build up the SCSI CDB.
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This text string is made up of a list of field specifiers. Field
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specifiers specify the value for each CDB field (including indicating
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that the value be taken from the next argument in the
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variable argument list), the width
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of the field in bits or bytes, and an optional name. White space is
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ignored, and the pound sign ('#') introduces a comment that ends at the
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end of the current line.
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.Pp
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The optional name is the first part of a field specifier and
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is in curly braces. The text in curly braces in this example are
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the names:
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.Bd -literal -offset indent
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.Fr "{PS} v:b1 {Reserved} 0:b1 {Page Code} v:b6 # Mode select page"
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.Ed
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.Pp
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This field specifier has two one bit fields and one six bit field.
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The second one bit field is the constant value 0 and the first
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one bit field and the six bit field are taken from the variable
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argument list.
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Multi byte fields are swapped into the SCSI byte order in the
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CDB and white space is ignored.
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.Pp
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When the field is a hex value or the letter v, (e.g.,
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.Fr "1A"
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or
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.Fr "v" )
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then a single byte value
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is copied to the next unused byte of the CDB.
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When the letter
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.Fr v
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is used the next integer argument is taken from the variable argument list
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and that value used.
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.Pp
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A constant hex value followed by a field width specifier or the letter
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.Fr v
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followed by a field width specifier (e.g.,
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.Fr 3:4 ,
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.Fr 3:b4 ,
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.Fr 3:i3 ,
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.FR v:i3 )
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specifies a field of a given bit or byte width.
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Either the constant value or (for the V specifier) the next integer value from
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the variable argument list is copied to the next unused
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bits or bytes of the CDB.
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.Pp
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A decimal number or the letter
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.Fr b
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followed by a decimal number field width indicates a bit field of that width.
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The bit fields are packed as tightly as possible beginning with the
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high bit (so that it reads the same as the SCSI spec), and a new byte of
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the CDB is started whenever a byte fills completely or when an
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.Fr i
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field is encountered.
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.Pp
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A field width specifier consisting of the letter
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.Fr i
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followed by either
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1, 2, 3 or 4 indicates a 1, 2, 3 or 4 byte integral value that must
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be swapped into SCSI byte order (MSB first).
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.Pp
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For the
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.Fr v
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field specifier the next integer argument is taken from the variable argument
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list and that value is used swapped into SCSI byte order.
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.Pp
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.Fn scsireq_decode
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is used to decode information from the data in phase of the SCSI
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transfer.
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.Pp
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The decoding is similar to
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the command specifier processing of
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.Fn scsireq_build
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except that the data is extracted from the data pointed to by
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.Fr scsireq->databuf.
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The stdarg list should be pointers to integers instead of integer
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values.
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A seek field type and a suppression modifier are added.
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The
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.Fr *
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suppression modifier (e.g.,
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.Fr *i3
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or
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.Fr *b4 )
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suppresses assignment from the field and can be used to skip
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over bytes or bits in the data, without having to copy
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them to a dummy variable in the arg list.
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.Pp
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The seek field type
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.Fr s
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permits you to skip over data.
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This seeks to an absolute position (
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.Fr s3 )
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or a relative position (
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.Fr s+3 )
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in the data, based on whether or not the presence of the '+' sign.
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The seek value can be specified as
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.Fr v
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and the next integer value from the argument list will be
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used as the seek value.
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.Pp
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.Fn scsireq_buff_decode
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decodes an arbitrary data buffer using the method
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described above in
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.Fn scsireq_decode .
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.Pp
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.Fn scsireq_encode
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encodes the data phase section of the structure. The encoding is
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handled identically as the encoding of the CDB structure by
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.Fn scsireq_build
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.Pp
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.Fn scsireq_enter
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submits the built up structure for processing using
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the SCIOCCOMMAND ioctl.
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.Pp
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.Fn SCSIREQ_ERROR
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is a macro that determines if the result of the SCIOCCOMMAND ioctl may
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have been
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in error by examining the host adapter return code, whether sense was sent
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or not, and so on.
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.Pp
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.Fn scsi_open
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checks environment variables and initializes the library for
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consistent library use and then calls the regular open system call.
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.Pp
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.Fn scsi_debug
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prints the results of a scsireq_enter function to the specified stdio
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stream.
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.Pp
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.Fn scsi_debug_output
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requests that the results of all transactions be debugged to the
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supplied file using
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.Fn scsi_debug .
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.Sh RETURN VALUES
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The function
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.Fn scsireq_new
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returns a pointer to storage allocated from malloc, and therefore
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potentially a NULL.
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.Pp
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The functions
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.Fn scsireq_build
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and
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.Fn scsireq_reset
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return the same pointer as the one passed in.
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.Pp
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The functions
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.Fn scsireq_buff_decode and
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.Fn scsireq_decode
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return the number of assignments performed.
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.Pp
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.Fn scsireq_encode
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returns the number of fields processed.
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.Pp
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The function
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.Fn scsireq_enter
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returns the result of the ioctl call.
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.Sh SEE ALSO
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.Xr scsi 8 ,
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.Xr scsi 4
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.Sh BUGS
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This only works completely for the 1542C. The host adapter code
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that sets up the residual amount of data transfer has to be added
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to each individual adapter. This library is usable on the other
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host adapters, however, the SCSI driver pretends that the proper
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amount of data is always transferred. If you have an Adaptec 174x
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and can hack contact dufault@hda.com and you can have the code to
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calculate residual data for the 174x series to integrate and test.
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.Sh HISTORY
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Many systems have comparable interfaces to permit a user to construct a
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SCSI command in user space.
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.Pp
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The data structure is almost identical to the SGI /dev/scsi data
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structure. If anyone knows the name of the authors it should
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go here; Peter Dufault first read about it in a 1989 Sun Expert magazine.
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.Pp
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Peter Dufault implemented a clone of SGI's interface in 386bsd that
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led to this library and the related kernel ioctl.
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If anyone needs that for compatability contact dufault@hda.com.
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