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Manual Pages for UNIX Operating System command usage for man streamio

Ioctl Requests streamio(7I)

NAME

streamio - STREAMS ioctl commands

SYNOPSIS

#include

int ioctl(int fildes, int command, ... /*arg*/);

DESCRIPTION

STREAMS (see Intro(3)) ioctl commands are a subset of the ioctl(2) commands and perform a variety of control functions on streams. The fildes argument is an open file descriptor that refers to a stream. The command argument determines the control

function to be performed as described below. The arg argu-

ment 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 command and arg arguments are interpreted by the STREAM head. Certain combinations of these arguments may be passed to a module or driver in the stream. Since these STREAMS commands are ioctls, they are subject to the errors described in ioctl(2). In addition to those errors, the call will fail with errno set to EINVAL, without processing a control function, if the STREAM referenced by fildes is linked below a multiplexor, or if command is not a valid value for a stream. Also, as described in ioctl(2), STREAMS modules and drivers can detect errors. In this case, the module or driver sends an error message to the STREAM head containing an error value. This causes subsequent calls to fail with errno set to this value. IOCTLS The following ioctl commands, with error values indicated, are applicable to all STREAMS files:

I_PUSH Pushes the module whose name is pointed to by

arg onto the top of the current stream, just below the STREAM head. If the STREAM is a pipe, the module will be inserted between the stream heads of both ends of the pipe. It

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then calls the open routine of the newly-

pushed module. On failure, errno is set to one of the following values: EINVAL Invalid module name. EFAULT arg points outside the allocated address space. ENXIO Open routine of new module failed. ENXIO Hangup received on fildes. ENOTSUP Pushing a module is not supported on this stream.

I_POP Removes the module just below the STREAM head

of the STREAM pointed to by fildes. To remove a module from a pipe requires that the module was pushed on the side it is being removed

from. arg should be 0 in an I_POP request.

On failure, errno is set to one of the fol-

lowing values: EINVAL No module present in the stream. ENXIO Hangup received on fildes. EPERM Attempt to pop through an anchor by an unprivileged process. ENOTSUP Removal is not supported.

I_ANCHOR Positions the stream anchor to be at the

stream's module directly below the stream head. Once this has been done, only a privileged process may pop modules below the anchor on the stream. arg must be 0 in an

I_ANCHOR request. On failure, errno is set to

the following value:

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EINVAL Request to put an anchor on a pipe.

I_LOOK Retrieves the name of the module just below

the stream head of the stream pointed to by fildes, and places it in a null terminated character string pointed at by arg. The buffer pointed to by arg should be at least

FMNAMESZ+1 bytes long. This requires the

declaration #include . On

failure, errno is set to one of the following values: EFAULT arg points outside the allocated address space. EINVAL No module present in stream.

I_FLUSH This request flushes all input and/or output

queues, depending on the value of arg. Legal arg values are: FLUSHR Flush read queues. FLUSHW Flush write queues. FLUSHRW Flush read and write queues. If a pipe or FIFO does not have any modules pushed, the read queue of the stream head on either end is flushed depending on the value of arg. If FLUSHR is set and fildes is a pipe, the read queue for that end of the pipe is flushed and the write queue for the other end is flushed. If fildes is a FIFO, both queues are flushed. If FLUSHW is set and fildes is a pipe and the other end of the pipe exists, the read queue for the other end of the pipe is flushed and the write queue for this end is flushed. If fildes is a FIFO, both queues of the FIFO are flushed.

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If FLUSHRW is set, all read queues are flushed, that is, the read queue for the FIFO and the read queue on both ends of the pipe are flushed. Correct flush handling of a pipe or FIFO with modules pushed is achieved via the pipemod module. This module should be the first module pushed onto a pipe so that it is at the midpoint of the pipe itself.

On failure, errno is set to one of the fol-

lowing values: ENOSR Unable to allocate buffers for flush message due to insufficient stream memory resources. EINVAL Invalid arg value. ENXIO Hangup received on fildes.

I_FLUSHBAND Flushes a particular band of messages. arg

points to a bandinfo structure that has the following members:

unsigned char bi_pri;

int bi_flag;

The bi_flag field may be one of FLUSHR,

FLUSHW, or FLUSHRW as described earlier.

I_SETSIG Informs the stream head that the user wishes

the kernel to issue the SIGPOLL signal (see signal(3C)) when a particular event has occurred on the stream associated with

fildes. I_SETSIG supports an asynchronous

processing capability in streams. The value of arg is a bitmask that specifies the events for which the user should be signaled. It is

the bitwise OR of any combination of the fol-

lowing constants:

S_INPUT Any message other than an

M_PCPROTO has arrived on a

stream head read queue. This event is maintained for

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compatibility with previous

releases. This event is trig-

gered even if the message is of zero length.

S_RDNORM An ordinary (non-priority) mes-

sage has arrived on a stream head read queue. This event is triggered even if the message is of zero length.

S_RDBAND A priority band message (band >

0) has arrived on a stream head

read queue. This event is trig-

gered even if the message is of zero length.

S_HIPRI A high priority message is

present on the stream head read queue. This event is triggered even if the message is of zero length.

S_OUTPUT The write queue just below the

stream head is no longer full. This notifies the user that there is room on the queue for

sending (or writing) data down-

stream.

S_WRNORM This event is the same as

S_OUTPUT.

S_WRBAND A priority band greater than 0

of a queue downstream exists and is writable. This notifies the user that there is room on the queue for sending (or writing) priority data downstream.

S_MSG A STREAMS signal message that

contains the SIGPOLL signal has reached the front of the stream head read queue.

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S_ERROR An M_ERROR message has reached

the stream head.

S_HANGUP An M_HANGUP message has reached

the stream head.

S_BANDURG When used in conjunction with

S_RDBAND, SIGURG is generated

instead of SIGPOLL when a prior-

ity message reaches the front of the stream head read queue. A user process may choose to be signaled only of high priority messages by setting the arg

bitmask to the value S_HIPRI.

Processes that wish to receive SIGPOLL sig-

nals must explicitly register to receive them

using I_SETSIG. If several processes register

to receive this signal for the same event on

the same stream, each process will be sig-

naled when the event occurs.

If the value of arg is zero, the calling pro-

cess will be unregistered and will not receive further SIGPOLL signals. On failure, errno is set to one of the following values: EINVAL arg value is invalid or arg is zero and process is not registered to receive the SIGPOLL signal. EAGAIN Allocation of a data structure to store the signal request failed.

I_GETSIG Returns the events for which the calling pro-

cess is currently registered to be sent a SIGPOLL signal. The events are returned as a bitmask pointed to by arg, where the events are those specified in the description of

I_SETSIG above. On failure, errno is set to

one of the following values: EINVAL Process not registered to receive the SIGPOLL signal.

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EFAULT arg points outside the allocated address space.

I_FIND Compares the names of all modules currently

present in the stream to the name pointed to by arg, and returns 1 if the named module is present in the stream. It returns 0 if the named module is not present. On failure, errno is set to one of the following values: EFAULT arg points outside the allocated address space. EINVAL arg does not contain a valid module name.

I_PEEK Allows a user to retrieve the information in

the first message on the stream head read queue without taking the message off the

queue. I_PEEK is analogous to getmsg(2)

except that it does not remove the message from the queue. arg points to a strpeek structure, which contains the following members: struct strbuf ctlbuf; struct strbuf databuf; long flags; The maxlen field in the ctlbuf and databuf strbuf structures (see getmsg(2)) must be set to the number of bytes of control information and/or data information, respectively, to

retrieve. flags may be set to RS_HIPRI or 0.

If RS_HIPRI is set, I_PEEK will look for a

high priority message on the stream head read

queue. Otherwise, I_PEEK will look for the

first message on the stream head read queue.

I_PEEK returns 1 if a message was retrieved,

and returns 0 if no message was found on the stream head read queue. It does not wait for

a message to arrive. On return, ctlbuf speci-

fies information in the control buffer, data-

buf specifies information in the data buffer,

and flags contains the value RS_HIPRI or 0.

On failure, errno is set to the following

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value: EFAULT arg points, or the buffer area specified in ctlbuf or databuf is, outside the allocated address space. EBADMSG Queued message to be read is not

valid for I_PEEK.

EINVAL Illegal value for flags.

ENOSR Unable to allocate buffers to per-

form the I_PEEK due to insuffi-

cient STREAMS memory resources.

I_SRDOPT Sets the read mode (see read(2)) using the

value of the argument arg. Legal arg values are:

RNORM Byte-stream mode, the default.

RMSGD Message-discard mode.

RMSGN Message-nondiscard mode.

In addition, the stream head's treatment of control messages may be changed by setting the following flags in arg: RPROTNORM Reject read() with EBADMSG if a control message is at the front of the stream head read queue. RPROTDAT Deliver the control portion of a message as data when a user issues read(). This is the default behavior. RPROTDIS Discard the control portion of a message, delivering any data portion, when a user issues a read().

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On failure, errno is set to the following value: EINVAL arg is not one of the above legal values, or arg is the bitwise inclusive OR of RMSGD and RMSGN.

I_GRDOPT Returns the current read mode setting in an

int pointed to by the argument arg. Read modes are described in read(). On failure, errno is set to the following value: EFAULT arg points outside the allocated address space.

I_NREAD Counts the number of data bytes in data

blocks in the first message on the stream head read queue, and places this value in the location pointed to by arg. The return value for the command is the number of messages on the stream head read queue. For example, if zero is returned in arg, but the ioctl return value is greater than zero, this indicates

that a zero-length message is next on the

queue. On failure, errno is set to the fol-

lowing value: EFAULT arg points outside the allocated address space.

I_FDINSERT Creates a message from specified buffer(s),

adds information about another stream and sends the message downstream. The message contains a control part and an optional data part. The data and control parts to be sent are distinguished by placement in separate buffers, as described below. The arg argument points to a strfdinsert structure, which contains the following members: struct strbuf ctlbuf; struct strbuf databuf;

t_uscalar_t flags;

int fildes;

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int offset; The len member in the ctlbuf strbuf structure (see putmsg(2)) must be set to the size of a

t_uscalar_t plus the number of bytes of con-

trol information to be sent with the message.

The fildes member specifies the file descrip-

tor of the other stream, and the offset member, which must be suitably aligned for

use as a t_uscalar_t, specifies the offset

from the start of the control buffer where

I_FDINSERT will store a t_uscalar_t whose

interpretation is specific to the stream end.

The len member in the databuf strbuf struc-

ture must be set to the number of bytes of data information to be sent with the message, or to 0 if no data part is to be sent.

The flags member specifies the type of mes-

sage to be created. A normal message is

created if flags is set to 0, and a high-

priority message is created if flags is set

to RS_HIPRI. For non-priority messages,

I_FDINSERT will block if the stream write

queue is full due to internal flow control conditions. For priority messages,

I_FDINSERT does not block on this condition.

For non-priority messages, I_FDINSERT does

not block when the write queue is full and

O_NDELAY or O_NONBLOCK is set. Instead, it

fails and sets errno to EAGAIN.

I_FDINSERT also blocks, unless prevented by

lack of internal resources, waiting for the availability of message blocks in the stream,

regardless of priority or whether O_NDELAY or

O_NONBLOCK has been specified. No partial

message is sent.

The ioctl() function with the I_FDINSERT com-

mand will fail if:

EAGAIN A non-priority message is speci-

fied, the O_NDELAY or O_NONBLOCK

flag is set, and the stream write queue is full due to internal flow control conditions. ENOSR Buffers can not be allocated for the message that is to be created.

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EFAULT The arg argument points, or the buffer area specified in ctlbuf or databuf is, outside the allocated address space. EINVAL One of the following: The fildes member of the strfdinsert structure is not a valid, open stream file descriptor; the size of a

t_uscalar_t plus offset is greater

than the len member for the buffer specified through ctlptr; the offset member does not specify a

properly-aligned location in the

data buffer; or an undefined value is stored in flags.

ENXIO Hangup received on the fildes argu-

ment of the ioctl call or the fildes member of the strfdinsert structure.

ERANGE The len field for the buffer speci-

fied through databuf does not fall within the range specified by the maximum and minimum packet sizes of the topmost stream module; or the len member for the buffer specified through databuf is larger than the maximum configured size of the data part of a message; or the len member for the buffer specified through ctlbuf is larger than the

maximum configured size of the con-

trol part of a message.

I_FDINSERT can also fail if an error message

was received by the stream head of the stream corresponding to the fildes member of the strfdinsert structure. In this case, errno will be set to the value in the message.

I_STR Constructs an internal STREAMS ioctl message

from the data pointed to by arg, and sends that message downstream. This mechanism is provided to send user ioctl requests to downstream modules and drivers.

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It allows information to be sent with the

ioctl, and will return to the user any infor-

mation sent upstream by the downstream reci-

pient. I_STR blocks until the system responds

with either a positive or negative ack-

nowledgement message, or until the request times out after some period of time. If the request times out, it fails with errno set to ETIME. To send requests downstream, arg must point to a strioctl structure which contains the following members:

int ic_cmd;

int ic_timout;

int ic_len;

char *ic_dp;

ic_cmd is the internal ioctl command intended

for a downstream module or driver and

ic_timout is the number of seconds (-1 =

infinite, 0 = use default, >0 = as specified)

an I_STR request will wait for acknowledge-

ment before timing out. ic_len is the number

of bytes in the data argument and ic_dp is a

pointer to the data argument. The ic_len

field has two uses: on input, it contains the length of the data argument passed in, and on return from the command, it contains the number of bytes being returned to the user

(the buffer pointed to by ic_dp should be

large enough to contain the maximum amount of data that any module or the driver in the stream can return).

At most one I_STR can be active on a stream.

Further I_STR calls will block until the

active I_STR completes via a positive or

negative acknowlegment, a timeout, or an

error condition at the stream head. By set-

ting the ic_timout field to 0, the user

is requesting STREAMS to provide the DEFAULT timeout. The default timeout is specific to the STREAMS implementation and may vary depending on which release of Solaris you are using. For Solaris 8 (and earlier versions), the default timeout is

fifteen seconds. The O_NDELAY and O_NONBLOCK

(see open(2)) flags have no effect on this call.

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The stream head will convert the information pointed to by the strioctl structure to an internal ioctl command message and send it downstream. On failure, errno is set to one of the following values: ENOSR Unable to allocate buffers for the ioctl message due to insufficient STREAMS memory resources.

EFAULT Either arg points outside the allo-

cated address space, or the buffer

area specified by ic_dp and ic_len

(separately for data sent and data returned) is outside the allocated address space.

EINVAL ic_len is less than 0 or ic_len is

larger than the maximum configured size of the data part of a message

or ic_timout is less than -1.

ENXIO Hangup received on fildes. ETIME A downstream ioctl timed out before acknowledgement was received.

An I_STR can also fail while waiting for an

acknowledgement if a message indicating an error or a hangup is received at the stream head. In addition, an error code can be

returned in the positive or negative ack-

nowledgement message, in the event the ioctl command sent downstream fails. For these

cases, I_STR will fail with errno set to the

value in the message.

I_SWROPT Sets the write mode using the value of the

argument arg. Legal bit settings for arg are:

SNDZERO Send a zero-length message down-

stream when a write of 0 bytes occurs.

To not send a zero-length message when a

write of 0 bytes occurs, this bit must not be set in arg.

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On failure, errno may be set to the following value: EINVAL arg is not the above legal value.

I_GWROPT Returns the current write mode setting, as

described above, in the int that is pointed to by the argument arg.

I_SENDFD Requests the stream associated with fildes to

send a message, containing a file pointer, to the stream head at the other end of a stream pipe. The file pointer corresponds to arg, which must be an open file descriptor.

I_SENDFD converts arg into the corresponding

system file pointer. It allocates a message block and inserts the file pointer in the block. The user id and group id associated with the sending process are also inserted. This message is placed directly on the read queue (see Intro(3)) of the stream head at the other end of the stream pipe to which it is connected. On failure, errno is set to one of the following values: EAGAIN The sending stream is unable to allocate a message block to contain the file pointer. EAGAIN The read queue of the receiving stream head is full and cannot accept the message sent by

I_SENDFD.

EBADF arg is not a valid, open file descriptor. EINVAL fildes is not connected to a stream pipe. ENXIO Hangup received on fildes.

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I_RECVFD Retrieves the file descriptor associated with

the message sent by an I_SENDFD ioctl over a

stream pipe. arg is a pointer to a data buffer large enough to hold an strrecvfd data structure containing the following members: int fd;

uid_t uid;

gid_t gid;

fd is an integer file descriptor. uid and gid are the user id and group id, respectively, of the sending stream.

If O_NDELAY and O_NONBLOCK are clear (see

open(2)), I_RECVFD will block until a message

is present at the stream head. If O_NDELAY or

O_NONBLOCK is set, I_RECVFD will fail with

errno set to EAGAIN if no message is present at the stream head.

If the message at the stream head is a mes-

sage sent by an I_SENDFD, a new user file

descriptor is allocated for the file pointer contained in the message. The new file descriptor is placed in the fd field of the strrecvfd structure. The structure is copied into the user data buffer pointed to by arg.

On failure, errno is set to one of the fol-

lowing values: EAGAIN A message is not present at the stream head read queue, and the

O_NDELAY or O_NONBLOCK flag is

set. EBADMSG The message at the stream head

read queue is not a message con-

taining a passed file descrip-

tor. EFAULT arg points outside the allocated address space. EMFILE NOFILES file descriptors are currently open.

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ENXIO Hangup received on fildes. EOVERFLOW uid or gid is too large to be stored in the structure pointed to by arg.

I_LIST Allows the user to list all the module names

on the stream, up to and including the top-

most driver name. If arg is NULL, the return value is the number of modules, including the driver, that are on the stream pointed to by fildes. This allows the user to allocate enough space for the module names. If arg is

non-null, it should point to an str_list

structure that has the following members:

int sl_nmods;

struct str_mlist *sl_modlist;

The str_mlist structure has the following

member:

char l_name[FMNAMESZ+1];

The sl_nmods member indicates the number of

entries the process has allocated in the

array. Upon return, the sl_modlist member of

the str_list structure contains the list of

module names, and the number of entries that

have been filled into the sl_modlist array is

found in the sl_nmods member (the number

includes the number of modules including the driver). The return value from ioctl() is 0. The entries are filled in starting at the top of the stream and continuing downstream until either the end of the stream is reached, or

the number of requested modules (sl_nmods) is

satisfied. On failure, errno may be set to one of the following values:

EINVAL The sl_nmods member is less than 1.

EAGAIN Unable to allocate buffers

I_ATMARK Allows the user to see if the current message

on the stream head read queue is ``marked''

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by some module downstream. arg determines how

the checking is done when there may be multi-

ple marked messages on the stream head read queue. It may take the following values: ANYMARK Check if the message is marked. LASTMARK Check if the message is the last one marked on the queue. The return value is 1 if the mark condition is satisfied and 0 otherwise. On failure, errno is set to the following value: EINVAL Invalid arg value.

I_CKBAND Check if the message of a given priority band

exists on the stream head read queue. This returns 1 if a message of a given priority

exists, 0 if not, or -1 on error. arg should

be an integer containing the value of the priority band in question. On failure, errno is set to the following value: EINVAL Invalid arg value.

I_GETBAND Returns the priority band of the first mes-

sage on the stream head read queue in the integer referenced by arg. On failure, errno is set to the following value: ENODATA No message on the stream head read queue.

I_CANPUT Check if a certain band is writable. arg is

set to the priority band in question. The return value is 0 if the priority band arg is flow controlled, 1 if the band is writable,

or -1 on error. On failure, errno is set to

the following value: EINVAL Invalid arg value.

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Ioctl Requests streamio(7I)

I_SETCLTIME Allows the user to set the time the stream

head will delay when a stream is closing and there are data on the write queues. Before closing each module and driver, the stream head will delay for the specified amount of

time to allow the data to drain. Note, how-

ever, that the module or driver may itself delay in its close routine; this delay is independent of the stream head's delay and is not settable. If, after the delay, data are still present, data will be flushed. arg is a pointer to an integer containing the number of milliseconds to delay, rounded up to the nearest legal value on the system. The default is fifteen seconds. On failure, errno is set to the following value: EINVAL Invalid arg value.

I_GETCLTIME Returns the close time delay in the integer

pointed by arg.

I_SERROPT Sets the error mode using the value of the

argument arg. Normally stream head errors are persistent;

once they are set due to an M_ERROR or

M_HANGUP, the error condition will remain

until the stream is closed. This option can

be used to set the stream head into non-

persistent error mode i.e. once the error has been returned in response to a read(2), getmsg(2), ioctl(2), write(2), or putmsg(2) call the error condition will be cleared. The error mode can be controlled independently for read and write side errors. Legal arg values are either none or one of: RERRNORM Persistent read errors, the default.

RERRNONPERSIST Non-persistent read errors.

OR'ed with either none or one of: WERRNORM Persistent write errors, the default.

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WERRNONPERSIST Non-persistent write

errors. When no value is specified e.g. for the read side error behavior then the behavior for that side will be left unchanged. On failure, errno is set to the following value: EINVAL arg is not one of the above legal values.

I_GERROPT Returns the current error mode setting in an

int pointed to by the argument arg. Error

modes are described above for I_SERROPT. On

failure,errno is set to the following value: EFAULT arg points outside the allocated address space. The following four commands are used for connecting and disconnecting multiplexed STREAMS configurations.

I_LINK Connects two streams, where fildes is the file

descriptor of the stream connected to the mul-

tiplexing driver, and arg is the file descrip-

tor of the stream connected to another driver. The stream designated by arg gets connected

below the multiplexing driver. I_LINK requires

the multiplexing driver to send an acknowledge-

ment message to the stream head regarding the

linking operation. This call returns a multi-

plexor ID number (an identifier used to discon-

nect the multiplexor, see I_UNLINK) on success,

and -1 on failure. On failure, errno is set to

one of the following values: ENXIO Hangup received on fildes.

ETIME Time out before acknowledgement mes-

sage was received at stream head.

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EAGAIN Temporarily unable to allocate

storage to perform the I_LINK.

ENOSR Unable to allocate storage to perform

the I_LINK due to insufficient

STREAMS memory resources. EBADF arg is not a valid, open file descriptor.

EINVAL fildes stream does not support multi-

plexing. EINVAL arg is not a stream, or is already linked under a multiplexor. EINVAL The specified link operation would cause a ``cycle'' in the resulting configuration; that is, a driver would be linked into the multiplexing configuration in more than one place. EINVAL fildes is the file descriptor of a pipe or FIFO. EINVAL Either the upper or lower stream has a major number >= the maximum major number on the system.

An I_LINK can also fail while waiting for the

multiplexing driver to acknowledge the link request, if a message indicating an error or a hangup is received at the stream head of fildes. In addition, an error code can be

returned in the positive or negative ack-

nowledgement message. For these cases, I_LINK

will fail with errno set to the value in the message.

I_UNLINK Disconnects the two streams specified by fildes

and arg. fildes is the file descriptor of the stream connected to the multiplexing driver. arg is the multiplexor ID number that was

returned by the I_LINK. If arg is -1, then all

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streams that were linked to fildes are discon-

nected. As in I_LINK, this command requires

the multiplexing driver to acknowledge the unlink. On failure, errno is set to one of the following values: ENXIO Hangup received on fildes.

ETIME Time out before acknowledgement mes-

sage was received at stream head. ENOSR Unable to allocate storage to perform

the I_UNLINK due to insufficient

STREAMS memory resources. EINVAL arg is an invalid multiplexor ID number or fildes is not the stream on

which the I_LINK that returned arg

was performed. EINVAL fildes is the file descriptor of a pipe or FIFO.

An I_UNLINK can also fail while waiting for

the multiplexing driver to acknowledge the link request, if a message indicating an error or a hangup is received at the stream head of fildes. In addition, an error code can be

returned in the positive or negative ack-

nowledgement message. For these cases,

I_UNLINK will fail with errno set to the value

in the message.

I_PLINK Connects two streams, where fildes is the file

descriptor of the stream connected to the mul-

tiplexing driver, and arg is the file descrip-

tor of the stream connected to another driver. The stream designated by arg gets connected via a persistent link below the multiplexing

driver. I_PLINK requires the multiplexing

driver to send an acknowledgement message to

the stream head regarding the linking opera-

tion. This call creates a persistent link that continues to exist even if the file descriptor fildes associated with the upper stream to the multiplexing driver is closed. This call returns a multiplexor ID number (an identifier

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Ioctl Requests streamio(7I)

that may be used to disconnect the multiplexor,

see I_PUNLINK) on success, and -1 on failure.

On failure, errno is set to one of the follow-

ing values: ENXIO Hangup received on fildes.

ETIME Time out before acknowledgement mes-

sage was received at the stream head. EAGAIN Unable to allocate STREAMS storage to

perform the I_PLINK.

EBADF arg is not a valid, open file descriptor. EINVAL fildes does not support multiplexing. EINVAL arg is not a stream or is already linked under a multiplexor. EINVAL The specified link operation would cause a ``cycle'' in the resulting configuration; that is, if a driver would be linked into the multiplexing configuration in more than one place. EINVAL fildes is the file descriptor of a pipe or FIFO.

An I_PLINK can also fail while waiting for the

multiplexing driver to acknowledge the link request, if a message indicating an error on a hangup is received at the stream head of fildes. In addition, an error code can be

returned in the positive or negative ack-

nowledgement message. For these cases, I_PLINK

will fail with errno set to the value in the message.

I_PUNLINK Disconnects the two streams specified by fildes

and arg that are connected with a persistent link. fildes is the file descriptor of the stream connected to the multiplexing driver.

SunOS 5.11 Last change: 12 Jul 2010 22

Ioctl Requests streamio(7I)

arg is the multiplexor ID number that was

returned by I_PLINK when a stream was linked

below the multiplexing driver. If arg is

MUXID_ALL then all streams that are persistent

links to fildes are disconnected. As in

I_PLINK, this command requires the multiplexing

driver to acknowledge the unlink. On failure, errno is set to one of the following values: ENXIO Hangup received on fildes.

ETIME Time out before acknowledgement mes-

sage was received at the stream head. EAGAIN Unable to allocate buffers for the acknowledgement message. EINVAL Invalid multiplexor ID number. EINVAL fildes is the file descriptor of a pipe or FIFO.

An I_PUNLINK can also fail while waiting for

the multiplexing driver to acknowledge the link request if a message indicating an error or a hangup is received at the stream head of fildes. In addition, an error code can be

returned in the positive or negative ack-

nowledgement message. For these cases,

I_PUNLINK will fail with errno set to the value

in the message.

RETURN VALUES

Unless specified otherwise above, the return value from

ioctl() is 0 upon success and -1 upon failure, with errno

set as indicated.

Manual Pages for UNIX Operating System command usage for man streamio

Ioctl Requests streamio(7I)

NAME

streamio - STREAMS ioctl commands

SYNOPSIS

DESCRIPTION

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

FMNAMESZ+1 bytes long. This requires the

Ioctl Requests streamio(7I)

S_INPUT Any message other than an

Ioctl Requests streamio(7I)

S_OUTPUT The write queue just below the

S_OUTPUT.

Ioctl Requests streamio(7I)

S_ERROR An M_ERROR message has reached

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

char l_name[FMNAMESZ+1];

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

once they are set due to an M_ERROR or

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

Ioctl Requests streamio(7I)

RETURN VALUES

SEE ALSO