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man pages section 4: Device and Network Interfaces

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Updated: Thursday, June 13, 2019
 
 

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.