sad - STREAMS Administrative Driver
int ioctl(int fildes, int command, int arg);
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
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.
The autopush facility (see autopush(1M)) allows one to con-
figure a list of modules to be automatically pushed on a
stream when a driver is first opened. Autopush is con-
trolled by the following commands:
Allows the administrator to configure the given
device's autopush information. arg points to a
strapush structure, which contains the following
unit_t sap_list [MAXAPUSH] [FMNAMESZ + 1];
The sap_cmd field indicates the type of confi-
guration being done. It may take on one of the
Configure one minor device of a driver.
Configure a range of minor devices of a
Configure all minor devices of a driver.
Undo configuration information for a
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 configura-
tion 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 config-
ured 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:
arg points outside the allocated address
The major device number is invalid, the
number of modules is invalid, or the list
of module names is invalid.
The major device number does not represent
a STREAMS driver.
The major-minor device pair is already con-
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.
The command is SAP_CLEAR and the device is
not configured for autopush.
ENOSR An internal autopush data structure cannot
Allows any user to query the sad driver to get the
autopush configuration information for a given dev-
ice. 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 config-
ure the device. Unused entries in the module list will
On failure, errno is set to one of the following
arg points outside the allocated address space.
The major device number is invalid.
The major device number does not represent a
The device is not configured for autopush.
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 follow-
struct str_mlist *sl_modlist;
The str_mlist structure has the following member:
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:
arg points outside the allocated
The sl_nmods field of the str_list
structure is less than or equal to
intro(2), ioctl(2), open(2)
STREAMS Programming Guide
Unless otherwise specified, the return value from ioctl()
is 0 upon success and -1 upon failure with errno set as
Man(1) output converted with