CAM(3) BSD Library Functions Manual CAM(3)NAME
cam_open_device, cam_open_spec_device, cam_open_btl, cam_open_pass,
cam_close_device, cam_close_spec_device, cam_getccb, cam_send_ccb,
cam_freeccb, cam_path_string, cam_device_dup, cam_device_copy,
cam_get_device — CAM user library
LIBRARY
library “libcam”
SYNOPSIS
#include <stdio.h>
#include <camlib.h>
struct cam_device *
cam_open_device(const char *path, int flags);
struct cam_device *
cam_open_spec_device(const char *dev_name, int unit, int flags,
struct cam_device *device);
struct cam_device *
cam_open_btl(path_id_t path_id, target_id_t target_id,
lun_id_t target_lun, int flags, struct cam_device *device);
struct cam_device *
cam_open_pass(const char *path, int flags, struct cam_device *device);
void
cam_close_device(struct cam_device *dev);
void
cam_close_spec_device(struct cam_device *dev);
union ccb *
cam_getccb(struct cam_device *dev);
int
cam_send_ccb(struct cam_device *device, union ccb *ccb);
void
cam_freeccb(union ccb *ccb);
char *
cam_path_string(struct cam_device *dev, char *str, int len);
struct cam_device *
cam_device_dup(struct cam_device *device);
void
cam_device_copy(struct cam_device *src, struct cam_device *dst);
int
cam_get_device(const char *path, char *dev_name, int devnamelen,
int *unit);
DESCRIPTION
The CAM library consists of a number of functions designed to aid in pro‐
gramming with the CAM subsystem. This man page covers the basic set of
library functions. More functions are documented in the man pages listed
below.
Many of the CAM library functions use the cam_device structure:
struct cam_device {
char device_path[MAXPATHLEN+1];/*
* Pathname of the
* device given by the
* user. This may be
* null if the user
* states the device
* name and unit number
* separately.
*/
char given_dev_name[DEV_IDLEN+1];/*
* Device name given by
* the user.
*/
u_int32_t given_unit_number; /*
* Unit number given by
* the user.
*/
char device_name[DEV_IDLEN+1];/*
* Name of the device,
* e.g. 'pass'
*/
u_int32_t dev_unit_num; /* Unit number of the passthrough
* device associated with this
* particular device.
*/
char sim_name[SIM_IDLEN+1];/*
* Controller name, e.g.'ahc'
*/
u_int32_t sim_unit_number; /* Controller unit number */
u_int32_t bus_id; /* Controller bus number */
lun_id_t target_lun; /* Logical Unit Number */
target_id_t target_id; /* Target ID */
path_id_t path_id; /* System SCSI bus number */
u_int16_t pd_type; /* type of peripheral device */
struct scsi_inquiry_data inq_data; /* SCSI Inquiry data */
u_int8_t serial_num[252]; /* device serial number */
u_int8_t serial_num_len; /* length of the serial number */
u_int8_t sync_period; /* Negotiated sync period */
u_int8_t sync_offset; /* Negotiated sync offset */
u_int8_t bus_width; /* Negotiated bus width */
int fd; /* file descriptor for device */
};
cam_open_device() takes as arguments a string describing the device it is
to open, and flags suitable for passing to open(2). The "path" passed in
may actually be most any type of string that contains a device name and
unit number to be opened. The string will be parsed by cam_get_device()
into a device name and unit number. Once the device name and unit number
are determined, a lookup is performed to determine the passthrough device
that corresponds to the given device. cam_open_device() is rather simple
to use, but it is not really suitable for general use because its behav‐
ior is not necessarily deterministic. Programmers writing new applica‐
tions should make the extra effort to use one of the other open routines
documented below.
cam_open_spec_device() opens the pass(4) device that corresponds to the
device name and unit number passed in. The flags should be flags suit‐
able for passing to open(2). The device argument is optional. The user
may supply pre-allocated space for the cam_device structure. If the
device argument is NULL, cam_open_spec_device() will allocate space for
the cam_device structure using malloc(3).
cam_open_btl() is similar to cam_open_spec_device(), except that it takes
a SCSI bus, target and logical unit instead of a device name and unit
number as arguments. The path_id argument is the CAM equivalent of a
SCSI bus number. It represents the logical bus number in the system.
The flags should be flags suitable for passing to open(2). As with
cam_open_spec_device(), the device argument is optional.
cam_open_pass() takes as an argument the path of a pass(4) device to
open. No translation or lookup is performed, so the path passed in must
be that of a CAM pass(4) device. The flags should be flags suitable for
passing to open(2). The device argument, as with cam_open_spec_device()
and cam_open_btl(), should be NULL if the user wants the CAM library to
allocate space for the cam_device structure. cam_close_device() frees
the cam_device structure allocated by one of the above open() calls, and
closes the file descriptor to the passthrough device. This routine
should not be called if the user allocated space for the cam_device
structure. Instead, the user should call cam_close_spec_device().
cam_close_spec_device() merely closes the file descriptor opened in one
of the open() routines described above. This function should be called
when the cam_device structure was allocated by the caller, rather than
the CAM library.
cam_getccb() allocates a CCB using malloc(3) and sets fields in the CCB
header using values from the cam_device structure.
cam_send_ccb() sends the given ccb to the device described in the
cam_device structure.
cam_freeccb() frees CCBs allocated by cam_getccb().
cam_path_string() takes as arguments a cam_device structure, and a string
with length len. It creates a colon-terminated printing prefix string
similar to the ones used by the kernel. e.g.: "(cd0:ahc1:0:4:0): ".
cam_path_string() will place at most len-1 characters into str. The
len'th character will be the terminating ‘\0’.
cam_device_dup() operates in a fashion similar to strdup(3). It allo‐
cates space for a cam_device structure and copies the contents of the
passed-in device structure to the newly allocated structure.
cam_device_copy() copies the src structure to dst.
cam_get_device() takes a path argument containing a string with a device
name followed by a unit number. It then breaks the string down into a
device name and unit number, and passes them back in dev_name and unit,
respectively. cam_get_device() can handle strings of the following
forms, at least:
/dev/foo0a
/dev/foo1s2c
foo0
foo0a
nfoo0
cam_get_device() is provided as a convenience function for applications
that need to provide functionality similar to cam_open_device(). Pro‐
grammers are encouraged to use more deterministic methods of obtaining
device names and unit numbers if possible.
RETURN VALUEScam_open_device(), cam_open_spec_device(), cam_open_btl(), and
cam_open_pass() return a pointer to a cam_device structure, or NULL if
there was an error.
cam_getccb() returns an allocated and partially initialized CCB, or NULL
if allocation of the CCB failed.
cam_send_ccb() returns a value of -1 if an error occured, and errno is
set to indicate the error.
cam_path_string() returns a filled printing prefix string as a conve‐
nience. This is the same str that is passed into cam_path_string().
cam_device_dup() returns a copy of the device passed in, or NULL if an
error occurred.
cam_get_device() returns 0 for success, and -1 to indicate failure.
If an error is returned from one of the base CAM library functions
described here, the reason for the error is generally printed in the
global string cam_errbuf which is CAM_ERRBUF_SIZE characters long.
SEE ALSOcam_cdbparse(3), pass(4), camcontrol(8)HISTORY
The CAM library first appeared in FreeBSD 3.0.
AUTHORS
Kenneth Merry ⟨ken@FreeBSD.org⟩
BUGScam_open_device() does not check to see if the path passed in is a sym‐
link to something. It also does not check to see if the path passed in
is an actual pass(4) device. The former would be rather easy to imple‐
ment, but the latter would require a definitive way to identify a device
node as a pass(4) device.
Some of the functions are possibly mis-named or poorly named.
BSD October 10, 1998 BSD
