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Leaving zeroing to the clients leads to error-prone pointer tricks (zeroing needs to preserve the CCB header), and this code is not performance-critical, so there's really no reason to not do it. Reviewed By: imp, rpokala (manpages) Sponsored by: NetApp, Inc. Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D27333
440 lines
10 KiB
Groff
440 lines
10 KiB
Groff
.\"
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.\" Copyright (c) 1998 Kenneth D. Merry.
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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. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd November 23, 2020
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.Dt CAM 3
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.Os
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.Sh NAME
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.Nm cam_open_device ,
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.Nm cam_open_spec_device ,
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.Nm cam_open_btl ,
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.Nm cam_open_pass ,
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.Nm cam_close_device ,
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.Nm cam_close_spec_device ,
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.Nm cam_getccb ,
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.Nm cam_send_ccb ,
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.Nm cam_freeccb ,
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.Nm cam_path_string ,
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.Nm cam_device_dup ,
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.Nm cam_device_copy ,
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.Nm cam_get_device
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.Nd CAM user library
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.Sh LIBRARY
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.Lb libcam
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.Sh SYNOPSIS
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.In stdio.h
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.In camlib.h
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.Ft struct cam_device *
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.Fo cam_open_device
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.Fa "const char *path"
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.Fa "int flags"
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.Fc
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.Ft struct cam_device *
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.Fo cam_open_spec_device
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.Fa "const char *dev_name"
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.Fa "int unit"
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.Fa "int flags"
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.Fa "struct cam_device *device"
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.Fc
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.Ft struct cam_device *
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.Fo cam_open_btl
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.Fa "path_id_t path_id"
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.Fa "target_id_t target_id"
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.Fa "lun_id_t target_lun"
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.Fa "int flags"
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.Fa "struct cam_device *device"
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.Fc
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.Ft struct cam_device *
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.Fo cam_open_pass
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.Fa "const char *path"
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.Fa "int flags"
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.Fa "struct cam_device *device"
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.Fc
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.Ft void
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.Fo cam_close_device
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.Fa "struct cam_device *dev"
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.Fc
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.Ft void
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.Fo cam_close_spec_device
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.Fa "struct cam_device *dev"
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.Fc
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.Ft union ccb *
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.Fo cam_getccb
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.Fa "struct cam_device *dev"
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.Fc
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.Ft int
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.Fo cam_send_ccb
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.Fa "struct cam_device *device"
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.Fa "union ccb *ccb"
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.Fc
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.Ft void
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.Fo cam_freeccb
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.Fa "union ccb *ccb"
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.Fc
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.Ft char *
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.Fo cam_path_string
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.Fa "struct cam_device *dev"
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.Fa "char *str"
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.Fa "int len"
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.Fc
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.Ft struct cam_device *
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.Fo cam_device_dup
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.Fa "struct cam_device *device"
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.Fc
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.Ft void
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.Fo cam_device_copy
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.Fa "struct cam_device *src"
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.Fa "struct cam_device *dst"
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.Fc
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.Ft int
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.Fo cam_get_device
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.Fa "const char *path"
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.Fa "char *dev_name"
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.Fa "int devnamelen"
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.Fa "int *unit"
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.Fc
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.Sh DESCRIPTION
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The CAM library consists of a number of functions designed to aid in
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programming with the CAM subsystem.
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This man page covers the basic set of
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library functions.
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More functions are documented in the man pages listed
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below.
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.Pp
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Many of the CAM library functions use the
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.Va cam_device
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structure:
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.Bd -literal
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struct cam_device {
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char device_path[MAXPATHLEN+1];/*
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* Pathname of the
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* device given by the
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* user. This may be
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* null if the user
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* states the device
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* name and unit number
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* separately.
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*/
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char given_dev_name[DEV_IDLEN+1];/*
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* Device name given by
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* the user.
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*/
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uint32_t given_unit_number; /*
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* Unit number given by
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* the user.
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*/
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char device_name[DEV_IDLEN+1];/*
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* Name of the device,
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* e.g., 'pass'
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*/
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uint32_t dev_unit_num; /* Unit number of the passthrough
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* device associated with this
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* particular device.
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*/
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char sim_name[SIM_IDLEN+1];/*
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* Controller name, e.g., 'ahc'
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*/
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uint32_t sim_unit_number; /* Controller unit number */
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uint32_t bus_id; /* Controller bus number */
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lun_id_t target_lun; /* Logical Unit Number */
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target_id_t target_id; /* Target ID */
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path_id_t path_id; /* System SCSI bus number */
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uint16_t pd_type; /* type of peripheral device */
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struct scsi_inquiry_data inq_data; /* SCSI Inquiry data */
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uint8_t serial_num[252]; /* device serial number */
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uint8_t serial_num_len; /* length of the serial number */
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uint8_t sync_period; /* Negotiated sync period */
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uint8_t sync_offset; /* Negotiated sync offset */
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uint8_t bus_width; /* Negotiated bus width */
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int fd; /* file descriptor for device */
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};
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.Ed
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.Pp
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.Fn cam_open_device
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takes as arguments a string describing the device it is to open, and
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.Ar flags
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suitable for passing to
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.Xr open 2 .
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The "path" passed in may actually be most any type of string that contains
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a device name and unit number to be opened.
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The string will be parsed by
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.Fn cam_get_device
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into a device name and unit number.
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Once the device name and unit number
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are determined, a lookup is performed to determine the passthrough device
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that corresponds to the given device.
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.Pp
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.Fn cam_open_spec_device
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opens the
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.Xr pass 4
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device that corresponds to the device name and unit number passed in.
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The
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.Ar flags
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should be flags suitable for passing to
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.Xr open 2 .
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The
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.Ar device
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argument is optional.
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The user may supply pre-allocated space for the
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.Va cam_device
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structure.
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If the
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.Ar device
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argument is
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.Dv NULL ,
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.Fn cam_open_spec_device
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will allocate space for the
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.Va cam_device
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structure using
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.Xr malloc 3 .
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.Pp
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.Fn cam_open_btl
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is similar to
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.Fn cam_open_spec_device ,
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except that it takes a SCSI bus,
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target and logical unit instead of a device name and unit number as
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arguments.
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The
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.Va path_id
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argument is the CAM equivalent of a SCSI bus number.
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It represents the logical bus number in the system.
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The
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.Ar flags
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should be flags suitable for passing to
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.Xr open 2 .
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As with
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.Fn cam_open_spec_device ,
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the
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.Fa device
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argument is optional.
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.Pp
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.Fn cam_open_pass
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takes as an argument the
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.Fa path
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of a
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.Xr pass 4
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device to open.
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No translation or lookup is performed, so the path passed
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in must be that of a CAM
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.Xr pass 4
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device.
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The
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.Fa flags
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should be flags suitable for passing to
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.Xr open 2 .
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The
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.Fa device
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argument, as with
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.Fn cam_open_spec_device
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and
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.Fn cam_open_btl ,
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should be
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.Dv NULL
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if the user wants the CAM library to allocate space for the
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.Va cam_device
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structure.
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.Pp
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.Fn cam_close_device
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frees the
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.Va cam_device
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structure allocated by one of the above
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.Xr open 2
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calls, and closes the file
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descriptor to the passthrough device.
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This routine should not be called if
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the user allocated space for the
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.Va cam_device
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structure.
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Instead, the user should call
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.Fn cam_close_spec_device .
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.Pp
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.Fn cam_close_spec_device
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merely closes the file descriptor opened in one of the
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.Xr open 2
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routines
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described above.
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This function should be called when the
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.Va cam_device
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structure was allocated by the caller, rather than the CAM library.
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.Pp
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.Fn cam_getccb
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allocates a prezeroed CCB
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using
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.Xr calloc 3
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and sets fields in the CCB header using values from the
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.Va cam_device
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structure.
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.Pp
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.Fn cam_send_ccb
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sends the given
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.Va ccb
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to the
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.Fa device
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described in the
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.Va cam_device
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structure.
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.Pp
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.Fn cam_freeccb
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frees CCBs allocated by
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.Fn cam_getccb .
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If
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.Va ccb
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is
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.Dv NULL ,
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no action is taken.
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.Pp
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.Fn cam_path_string
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takes as arguments a
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.Va cam_device
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structure, and a string with length
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.Fa len .
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It creates a colon-terminated printing prefix string similar to the ones
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used by the kernel.
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e.g.: "(cd0:ahc1:0:4:0): ".
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.Fn cam_path_string
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will place at most
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.Fa len Ns \-1
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characters into
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.Ar str .
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The
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.Ar len Ns 'th
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character will be the terminating
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.Ql \e0 .
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.Pp
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.Fn cam_device_dup
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operates in a fashion similar to
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.Xr strdup 3 .
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It allocates space for a
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.Va cam_device
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structure and copies the contents of the passed-in
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.Fa device
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structure to the newly allocated structure.
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.Pp
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.Fn cam_device_copy
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copies the
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.Fa src
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structure to
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.Fa dst .
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.Pp
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.Fn cam_get_device
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takes a
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.Fa path
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argument containing a string with a device name followed by a unit number.
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It then breaks the string down into a device name and unit number, and
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passes them back in
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.Fa dev_name
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and
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.Fa unit ,
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respectively.
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.Fn cam_get_device
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can handle strings of the following forms, at least:
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.Pp
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.Bl -tag -width 1234 -compact
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.It /dev/foo1
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.It foo0
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.It nsa2
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.El
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.Pp
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.Fn cam_get_device
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is provided as a convenience function for applications that need to provide
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functionality similar to
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.Fn cam_open_device .
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.Sh RETURN VALUES
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.Fn cam_open_device ,
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.Fn cam_open_spec_device ,
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.Fn cam_open_btl ,
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and
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.Fn cam_open_pass
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return a pointer to a
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.Va cam_device
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structure, or
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.Dv NULL
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if there was an error.
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.Pp
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.Fn cam_getccb
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returns an allocated and partially initialized CCB, or
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.Dv NULL
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if allocation of the CCB failed.
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.Pp
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.Fn cam_send_ccb
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returns a value of -1 if an error occurred, and
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.Va errno
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is set to indicate the error.
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.Pp
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.Fn cam_path_string
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returns a filled printing prefix string as a convenience.
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This is the same
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.Fa str
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that is passed into
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.Fn cam_path_string .
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.Pp
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.Fn cam_device_dup
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returns a copy of the
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.Va device
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passed in, or
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.Dv NULL
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if an error occurred.
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.Pp
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.Fn cam_get_device
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returns 0 for success, and -1 to indicate failure.
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.Pp
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If an error is returned from one of the base CAM library functions
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described here, the reason for the error is generally printed in the global
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string
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.Va cam_errbuf
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which is
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.Dv CAM_ERRBUF_SIZE
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characters long.
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.Sh SEE ALSO
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.Xr cam_cdbparse 3 ,
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.Xr pass 4 ,
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.Xr camcontrol 8
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.Sh HISTORY
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The CAM library first appeared in
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.Fx 3.0 .
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.Sh AUTHORS
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.An Kenneth Merry Aq Mt ken@FreeBSD.org
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.Sh BUGS
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.Fn cam_open_device
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does not check to see if the
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.Fa path
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passed in is a symlink to something.
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It also does not check to see if the
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.Fa path
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passed in is an actual
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.Xr pass 4
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device.
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The former would be rather easy to implement, but the latter would
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require a definitive way to identify a device node as a
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.Xr pass 4
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device.
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.Pp
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Some of the functions are possibly misnamed or poorly named.
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