SAD(4D) Devices SAD(4D)

NAME

sad - STREAMS Administrative Driver

SYNOPSIS

#include <sys/types.h>


#include <sys/conf.h>


#include <sys/sad.h>


#include <sys/stropts.h>


int ioctl(int fildes, int command, int arg);

DESCRIPTION

The STREAMS Administrative Driver provides an interface for
applications to perform administrative operations on STREAMS modules
and drivers. The interface is provided through ioctl(2) commands.
Privileged operations may access the sad driver using /dev/sad/admin.
Unprivileged operations may access the sad driver using
/dev/sad/user.


The fildes argument is an open file descriptor that refers to the sad
driver. The command argument determines the control function to be
performed as described below. The arg argument represents additional
information that is needed by this command. The type of arg depends
upon the command, but it is generally an integer or a pointer to a
command-specific data structure.

COMMAND FUNCTIONS

The autopush facility (see autopush(8)) allows one to configure a
list of modules to be automatically pushed on a stream when a driver
is first opened. Autopush is controlled by the following commands:

SAD_SAP
Allows the administrator to configure the given device's
autopush information. arg points to a strapush structure,
which contains the following members:

unit_t ap_cmd;
major_t sap_major;
minor_t sap_minor;
minor_t sap_lastminor;
unit_t sap_npush;
unit_t sap_list [MAXAPUSH] [FMNAMESZ + 1];

The sap_cmd field indicates the type of configuration
being done. It may take on one of the following values:

SAP_ONE
Configure one minor device of a driver.


SAP_RANGE
Configure a range of minor devices of a
driver.


SAP_ALL
Configure all minor devices of a driver.


SAP_CLEAR
Undo configuration information for a driver.

The sap_major field is the major device number of the
device to be configured. The sap_minor field is the minor
device number of the device to be configured. The
sap_lastminor field is used only with the SAP_RANGE
command, which configures a range of minor devices between
sap_minor and sap_lastminor, inclusive. The minor fields
have no meaning for the SAP_ALL command. The sap_npush
field indicates the number of modules to be automatically
pushed when the device is opened. It must be less than or
equal to MAXAPUSH, defined in sad.h. It must also be less
than or equal to NSTRPUSH, the maximum number of modules
that can be pushed on a stream, defined in the kernel
master file. The field sap_list is an array of NULL-
terminated module names to be pushed in the order in which
they appear in the list.

When using the SAP_CLEAR command, the user sets only
sap_major and sap_minor. This will undo the configuration
information for any of the other commands. If a previous
entry was configured as SAP_ALL, sap_minor should be set
to zero. If a previous entry was configured as SAP_RANGE,
sap_minor should be set to the lowest minor device number
in the range configured.

On failure, errno is set to the following value:

EFAULT
arg points outside the allocated address space.


EINVAL
The major device number is invalid, the number
of modules is invalid, or the list of module
names is invalid.


ENOSTR
The major device number does not represent a
STREAMS driver.


EEXIST
The major-minor device pair is already
configured.


ERANGE
The command is SAP_RANGE and sap_lastminor is
not greater than sap_minor, or the command is
SAP_CLEAR and sap_minor is not equal to the
first minor in the range.


ENODEV
The command is SAP_CLEAR and the device is not
configured for autopush.


ENOSR
An internal autopush data structure cannot be
allocated.


SAD_GAP
Allows any user to query the sad driver to get the
autopush configuration information for a given device. arg
points to a strapush structure as described in the
previous command.

The user should set the sap_major and sap_minor fields of
the strapush structure to the major and minor device
numbers, respectively, of the device in question. On
return, the strapush structure will be filled in with the
entire information used to configure the device. Unused
entries in the module list will be zero-filled.

On failure, errno is set to one of the following values:

EFAULT
arg points outside the allocated address space.


EINVAL
The major device number is invalid.


ENOSTR
The major device number does not represent a
STREAMS driver.


ENODEV
The device is not configured for autopush.


SAD_VML
Allows any user to validate a list of modules (that is, to
see if they are installed on the system). arg is a pointer
to a str_list structure with the following members:

int sl_nmods;
struct str_mlist *sl_modlist;

The str_mlist structure has the following member:

char l_name[FMNAMESZ+1];

sl_nmods indicates the number of entries the user has
allocated in the array and sl_modlist points to the array
of module names. The return value is 0 if the list is
valid, 1 if the list contains an invalid module name, or
-1 on failure. On failure, errno is set to one of the
following values:

EFAULT
arg points outside the allocated address space.


EINVAL
The sl_nmods field of the str_list structure is
less than or equal to zero.

SEE ALSO

Intro(2), ioctl(2), open(2)


STREAMS Programming Guide

DIAGNOSTICS

Unless otherwise specified, the return value from ioctl() is 0 upon
success and -1 upon failure with errno set as indicated.

February 17, 2023 SAD(4D)