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)