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streamio(7)
NAME
streamio - STREAMS ioctl commands
SYNOPSIS
#include <sys/types.h>
#include <sys/stropts.h>
int ioctl(
int fildes,
int command,
... /* arg */); );
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
ioctl(): XSH4.2
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
fildes
Contains the open file descriptor for the Stream to be operated on.
command
Specifies the STREAM ioctl() command function to be performed on the
Stream.
arg Contains additional information that the specified command may need for
performing its function. This is usually an integer, or a pointer to
a command-specific structure, but can be of any type.
DESCRIPTION
The STREAMS ioctl commands perform control operations on Streams. User
processes can use these commands on all STREAMS file types.
When the Stream head receives a STREAMS ioctl function, it interprets the
command parameter and arg parameter, when specified, into an M_IOCTL
message. In some cases, the command and arg parameters are passed onto a
module or driver in the Stream.
The modules or drivers in a Stream can also detect errors. When they do,
they send an error message containing an error number to the Stream head.
Subsequent calls to the functions will fail with errno set to this number.
ioctl Commands
The STREAMS ioctl commands are the following:
I_ATMARK
Lets the user process see if the message currently on the Stream head
read queue is marked by a downstream module. A message is marked when
its b_flag field has MSGMARK ORed in by a module/driver. The arg field
specifies how the checking is done when there are multiple marked
messages on the queue. The legal values of arg are:
ANYMARK
Checks if the message is marked.
LASTMARK
Checks if the message is the last one that is marked on the queue.
The command returns a value of 1 if the mark condition is satisfied;
otherwise, a 0 (zero) is returned.
I_CANPUT
Checks if the specified priority band is currently writable. The arg
parameter specifies the priority band to check.
The command returns a value of 0 (zero) if the priority band is being
flow controlled; otherwise, a value of 1 is returned.
I_CKBAND
Checks if a certain priority band's message is currently on the Stream
head read queue. The arg parameter specifies the priority band being
checked.
If a message of the priority band is on the Stream head read queue, the
command returns a value of 1; otherwise, a value of 0 (zero) is
returned.
I_FDINSERT
Creates a message from one or more user specified buffers, includes
information about another Stream, and sends the message downstream. The
message contains a control part and a data part (which is optional).
These parts are placed in separate buffers, ctlbuf and databuf, pointed
to by arg. These buffers are contained in an strfdinsert structure
(defined in the stropts.h header file), whose members are as follows:
struct strbuf ctlbuf;
struct strbuf databuf;
long flags;
int fildes;
int offset;
The strbuf structure pointed to by ctlbuf and databuf has the following
members:
int maxlen;
int len;
char *buf
The len field of the strbuf structure for ctlbuf must specify the size
of a pointer, plus the number of information control bytes to be sent
in the message.
The fildes field in the strfdinsert structure specifies the file
descriptor of the Stream in which the message will be sent.
The offset field needs to be properly aligned. This field specifies the
number of bytes after the beginning of the control buffer where the
I_FDINSERT command will store a pointer. This pointer will be the
address of the read queue structure of the device driver for the Stream
designated by fildes in the strfdinsert structure.
The len field in the strbuf structure for databuf must contain the
number of bytes of data information to be sent with the message, or to
0 (zero) if no data part is to be sent.
The flags field specifies the type of message to be created. When this
field contains 0 (zero), the I_FDINSERT command creates an ordinary
message. When the field is set to RS_HIPRI, the I_FDINSERT command
creates a high priority message. This command will block for an
ordinary message if the named Stream's read queue is full because of
internal flow control conditions. It will not block on these conditions
for a high priority message. For ordinary messages, the ioctl will not
block when the write queue is full and O_NDELAY or O_NONBLOCK (see the
open() function) is specified. It will fail instead.
I_FIND
Compares the names of all modules currently present on the Stream to
the name specified in arg. The command returns a value of 1 value if
the module is present and a value of 0 (zero) value if the the module
is not present.
I_FLUSH
Flushes the input and output queues of the Stream head and all of the
modules and drivers on the Stream, according to the value of arg. The
arg parameter value can specify one of the following operations:
FLUSHRW
Flushes write and read queues.
FLUSHW
Flushes write queues.
FLUSHR
Flushes read queues.
The command has the following effects on pipes:
· If a pipe does not have pushed modules, then, according to the
value of arg, the read queue of the Stream head at either end is
flushed.
· When arg is FLUSHRW and fildes specifies a pipe, the read queues
at both ends are flushed.
· When arg is FLUSHW and fildes specifies a pipe, and the other end
of the pipe exists (for example, the other end is not closed), the
read queue for the other end of the pipe, and the write queue for
this end, are flushed.
· When arg is FLUSHR and fildes specifies a pipe, both the read
queue for the end which issued the I_FLUSH, and the write queue
for the other end, are flushed.
The pipemod module performs flushing operations on pipes. This module
should be the first one pushed on the Stream for a pipe so that it will
be located at the midpoint of the pipe.
I_FLUSHBAND
Flushes a band of messages. The band of messages to be flushed is
defined in the bandinfo structure pointed to by arg. This structure (in
the stropts.h header file) has the following members:
unsigned char bi_pri:
int bi_flag;
The value of the bi_flag field can be FLUSHR, FLUSHW, or FLUSHRW, as
described for the I_FLUSH command.
I_GETBAND
Returns the priority of the first message on the Stream head read
queue. The arg parameter specifies the priority band being checked.
I_GETCLTIME
Returns the time delay for closing a Stream (see the I_SETCLTIME ioctl
command). The time value is returned in the long pointed to by arg.
This value may, or may not, have been set by a previously issued
I_SETCLTIME ioctl.
I_GETSIG
Returns the events for which the calling process has registered to
receive a SIGPOLL signal. Events are returned as in arg bitmask as
defined for the I_SETSIG command.
I_GRDOPT
Returns the current read mode setting of the Stream (see the read()
function reference page) in an integer pointed to by arg.
I_GWROPT
Returns the current write mode setting for a Stream in the integer
pointed to by arg. The value of the integer returned in arg is SNDZERO
as described for the I_SWROPT command.
I_LINK
Connects two Streams: the file descriptor of the Stream associated with
the multiplexing driver (where fildes is the file descriptor) and the
Stream associated with another driver (where arg is the file
descriptor). The Stream referred to by arg is connected below the
multiplexing driver.
The I_LINK ioctl requires a multiplexing driver to send an
acknowledgement message (M_IOCACK or M_IOCNAK) to the Stream head about
the linking operation. Upon successful completion, the call returns a
multiplexor ID number, which is an identifier that is used to
disconnect the link (see the I_UNLINK command). If the request fails,
a value of -1 is returned.
I_LIST
Lets the user process list the names of all the modules present on a
Stream. This includes the names up to and including the topmost driver
name. If the arg parameter is a null value, the command returns the
number of modules, plus the driver, which are present on the Stream
referred to by fildes. The user can use this information to allocate
enough space for the module and driver names in user space. If the arg
parameter is not a null value, its value should point to an str_list
structure (in the stropts.h header file), with the following members:
int sl_nmods;
struct str_mlist *sl_modlist;
The str_mlist structure (also in the stropts.h header file) has the
following member:
char 1_name[FMNAMESZ+1];
The sl_nmods field of the str_list structure indicates the number of
entries that the user process has allocated in the array and on return.
The sl_modlist field contains the list of module names.
The return value for the I_STR ioctl indicates the number of entries
that have been filled in the array.
I_LOOK
Retrieves the name of the module located just below the Stream head,
placing it in a null terminated character string pointed to by arg. The
Stream is referred to by fildes. The arg parameter should point to a
buffer, whose size is at least FMNAMESZ+1 bytes. The <sys/stropts.h>
file contains the definition for FMNAMESZ.
I_NREAD
Counts the bytes in the data blocks of the first message on the Stream
head read queue. This command places this value in the location
pointed to by arg. The command returns the number of messages on the
queue. For example, if the command call results in a value of 0 (zero)
in arg, but a return value greater than 0 (zero) is returned by the
ioctl() function, the first message on the queue contains 0 (zero)
bytes.
I_PEEK
Allows the user process to look (peek) at the contents of the first
message on the Stream head read queue. This is done without taking the
message off the queue. The I_PEEK ioctl operates the same way as the
getmsg() function, except that it does not remove the message. The arg
parameter points to a strpeek structure (in the stropts.h header file)
with the following members:
struct strbuf ctlbuf;
struct strbuf databuf;
long flags;
The strbuf structure pointed to by ctlbuf and databuf has the following
members:
int maxlen;
int len;
char *buf
The maxlen field of the strbuf structure must specify the number of
bytes of control or data information to be retrieved. The flags field
can be set to RS_HIPRI or 0 (zero). If this field is set to RS_HIPRI,
the I_PEEK ioctl looks for a high priority message on the queue. If the
field is set to 0, the I_PEEK ioctl looks at the first message on the
queue.
The I_PEEK returns a 1 if a message was retrieved, and returns a value
of 0 (zero) if no message was found; it does not wait for a message.
Upon successful completion, ctlbuf specifies control information in the
control buffer, databuf specifies data information in the data buffer,
and flags contains RS_HIPRI or 0 (zero).
I_PLINK
Connects two Streams: the file descriptor of the Stream associated with
the multiplexing driver (where fildes is the file descriptor) and the
Stream associated with another driver (where arg is the file
descriptor). The Stream referred to by arg is connected via a
persistent link below the multiplexing driver. A persistent link is a
link that can exist even if the file descriptor fildes referring to the
Stream associated with the multiplexing driver is closed.
The I_PLINK ioctl requires a multiplexing driver to send an
acknowledgement message (M_IOCACK or M_IOCNAK) to the Stream head about
the linking operation.
On successful completion, the command returns a multiplexor ID number,
which is an identifier that is used to disconnect the multiplexing
driver (see the I_PUNLINK command). Otherwise, a -1 is returned.
The I_PLINK ioctl can also fail if it is waiting for the multiplexing
driver to acknowledge the link request and an error (M_ERROR) message,
or hangup (M_HANGUP) message is received at the Stream head for fildes.
In addition, an error can be returned in an M_IOCACK or M_IOCNAK
message. When these occur, the I_PLINK ioctl will fail with errno set
to the value in the message.
I_POP
Removes the module just below the Stream head. The Stream is referred
to by the fildes parameter. The arg parameter must be set to the value
0 (zero) in the request.
In the case of pipes, the module must be popped from the side on which
it was pushed.
I_PUNLINK
Disconnects two Streams that are connected via a persistent link, where
fildes is the file descriptor of the Stream associated with a
multiplexing driver and arg is the multiplexor ID number returned by
the I_PLINK ioctl. If arg is MUXID_ALL (as defined in the stropts.h
header file), then all Streams that are connected by persistent links
to the Stream referred to by fildes are disconnected.
The I_PUNLINK ioctl requires a multiplexing driver to send an
acknowledgement message (M_IOCACK or M_IOCNAK) to the Stream head about
the unlinking operation.
I_PUSH
Pushes the module whose name is pointed to by arg on to the Stream,
just below the Stream head, then calls the open routine of the module.
In the case of pipes, the module is effectively pushed between the
Stream head at each end.
I_RECVFD
Gets the file descriptor associated with the message sent by the
I_SENDFD command over a Stream pipe.
The arg parameter points to a data buffer large enough to hold a
strrecvfd structure (in the stropts.h header file), which contains user
data. This structure has the following members:
int fd;
uid_t uid;
gid_t gid;
char fill[8]
The fd field of the strrecvfd structure contains the integer for the
file descriptor. The uid and guid fields contain the user ID and group
ID of the sending Stream. If the O_ONDELAY or O_NONBOCK flags (see the
open() function) are not set, the I_RECVFD ioctl will block until a
message is present at the Stream head. If the O_ONDELAY or O_NONBOCK
flags are set, the I_RECVFD ioctl will fail if no message is present at
the Stream head.
If the I_SENDFD command sent the message at the Stream head, the
I_RECVFD command allocates a new file descriptor for the file pointer
contained in the message. The new file descriptor is placed in the fd
field of the strrecvfd structure, and the structure is copied into the
data buffer pointed to by arg.
I_SENDFD
Requests the Stream referred to by fildes to send a message M_PASSFP to
the Stream head at the other end of a Stream pipe. The file pointer
corresponds to the value of arg, which specifies an open file
descriptor.
The I_SENDFD command changes the arg value into a system file pointer,
allocates a message data block, and inserts the file pointer in the
block. It also places the user id and group id associated with the
calling process are also placed in the block. The message is then
placed directly on the read queue of the Stream head at the other end
of the Stream pipe. It does not go through the Stream of the pipe.
I_SETCLTIME
Lets the user process set the time that the Stream head delays when the
Stream is closing and the write queues contain data. The arg parameter
contains a pointer to the number of milliseconds to delay, rounded up
to the nearest legal value on the system. The default time is 15
seconds.
Before Stream modules and drivers are closed, the Stream head will
delay for the specified amount of time. This allows the data on the
write queues to drain. If data are still present on the writes queues
after the delay, the queues are flushed.
I_SETSIG
Tells the Stream head that the user process wants a SIGPOLL signal to
be issued by the kernel for a particular event that can occur on a
Stream. This command provides support for asynchronous processing in
STREAMS.
The arg parameter contains a bitmask specifying the particular events
that SIGPOLL is to be sent for. The value is the bitwise-OR of any
combination of the following constants:
S_BANDURG
Indicates that, when used with S_RDBAND, a priority message has
reached the front of the Stream head read queue. (If only S_RDBAND
is set, only a SIGPOLL signal will be generated. If S_BANDURG is
also set, then a SIGURG signal will be generated.) However, SIGURG
is generated instead of SIGPOLL.
S_ERROR
Specifies that an M_ERROR message has reached the front of the
Stream head read queue. The SIGPROC signal is posted to the user.
S_HANGUP
Specifies that an M_HANGUP message has reached the Stream head. The
SIGPROC signal is posted, in addition to a SIGHUP signal.
S_HIPRI
Specifies a high priority message has arrived on the readd queue of
the Stream head. This bit is set even zero length messages.
S_INPUT
Specifies that a message, which is not a M_PCPROTO type message,
has arrived on the read queue of the Stream head. This bit is set
even for zero length messages. The S_INPUT event is maintained for
compatibility with SVID 2.
S_MSG
Specifies that a STREAMS signal (M_SIG) signal containing the
SIGPOLL signal has reached the front of the Stream head read queue.
The SIGPROC signal will be posted to the user. If S_MSG is not
enabled, SIGPROC will not be sent.
S_OUTPUT
Specifies that the write queue of the module just below the Stream
head is not full any more. There is room on the queue for the user
process to send (write) data to the Stream.
S_RDBAND
Specifies a priority band message (where band is greater than 0
(zero)) has arrived on the read queue of the Stream head. This bit
is set even zero length messages.
S_RDNORM
Specifies that an ordinary message has arrived on the read queue of
the Stream head. This bit is set even for zero length messages.
S_WRBAND
Specifies that a priority band (where band is greater than 0
(zero)) exists on a queue downstream. The user can send (write)a
priority data message on the queue.
S_WRNORM
Specifies that this event is the same as S_OUTPUT.
User processes must register explicitly using the I_SETSIG command to
receive SIGPOLL (or SIGURG) signals. This is noted by the Stream head.
When more than one user process registers to receive the signal for the
same event on a Stream, each is signaled when the event occurs. If the
value of arg is 0 (zero), the calling process is deregistered and does
not receive the signal.
A user process can set the arg bitmask to the S_HIPRI value, thus
allowing itself to be signaled only of high priority messages.
I_SRDOPT
Sets the read mode of the Stream (see the read() reference page)
according to the value of arg. The arg value specifies the following
read modes related to data and message boundaries:
RNORM
Byte-stream mode (the default). The read() function completes when
the byte count is satisfied, the Stream head read queue is empty,
or a zero length message is encountered. In the case of a zero
length message, the message is placed back on the queue, and a
subsequent read() returns 0 bytes.
RMSGD
Message-discard mode. The read() function completes when the byte
count is satisfied, or a message boundary is reached. Any
remaining data in the message are discarded.
RMSGN
Message-nondiscard mode. The read() function completes when the
byte count is satisfied, or a message boundary is reached. Any data
remaining in the message are put back on the read queue.
If the following value are set in arg, the Stream head treats control
(protocol) messages accordingly:
RPROTNORM
The read() function fails, returning EBADMSG, if a control message
is at the front of the read queue (the default behavior).
RPROTDAT
The read() function delivers the control portion of the message as
data to the user process.
RPROTDIS
The read() function discard the control portion of a message and
send the data portion to the user process.
I_STR
Builds a STREAMS ioctl (M_IOCTL) message from the data pointed to by
arg and sends the message downstream to a module or driver. The command
allows a user process to send data with an ioctl request, and to
receive any information that the downstream recipient of the message
returns. The I_STR ioctl blocks until the intended recipient of the
M_IOCTL message responds with a positive acknowledgement (M_IOCACK)
message or negative acknowledgement (M_IOCNAK) message, or until the
request times out (default time = 15 seconds). If the request times
out, it fails.
Only one I_STR ioctl can be active on a Stream at a time. Other
requests must wait until the active request completes at the Stream
head. The O_NDELAY and O_NONBLOCK flags (see the open() function) have
no effect on the call.
User values for the I_STR ioctl request are supplied by a strioctl
structure (in the stropts.h header file), to which the arg parameter
points. The members of strioctl structure are the following:
int ic_cmd;
int ic_timeout;
int ic_len;
char *ic_dp;
The ic_cmd field of the strioctl structure contains the ioctl command
to be sent to the downstream module or driver. The ic_timeout field
specifies the number of seconds that the I_STR request will wait for an
acknowledgement before timing out:
-1 Indicates infinite number of seconds.
0 (zero)
Indicates that the default number of seconds should be used (which
is infinite).
>0 Indicates that the specified number of seconds should be used.
On input, the ic_len field contains the length of the data argument. On
return, it contains the number of bytes being returned to the user
process, (the buffer pointed to by ic_dp). The buffer pointed to by
ic_dp should be large enough to contain the maximum amount of data able
to be returned by any module or driver in the Stream.
I_SWROPT
Sets the stream write mode according to the arg parameter value. The
legal value for arg is:
SNDZERO
When set, the Stream head sends a zero length message downstream
upon the occurrence of a write of 0 (zero) bytes. When not set, the
Stream head does not send a zero length message downstream when a
write of 0 bytes occurs, and returns 0 to the user process.
I_UNLINK
Disconnects two Streams, where fildes is the file descriptor of the
Stream associated with a multiplexing driver and arg is the multiplexor
identifier number returned by the I_LINK ioctl, which created the
multiplexing configuration. If arg is MUXID_ALL (defined in the
stropts.h header file), all Streams connected to the Stream referred to
by fildes are disconnected.
The I_UNLINK ioctl requires a multiplexing driver to send an
acknowledgement message (M_IOCACK or M_IOCNAK) to the Stream head about
the unlinking operation.
RETURN VALUES
Unless specified differently for a command, the return value for a STREAMS
ioctl() call is 0 (zero) on success and -1 (minus one) on failure.
ERRORS
A STREAMS ioctl command fails without performing the function and with
errno set to [EINVAL] if:
· The Stream referred to by fildes is linked below a multiplexing
driver.
· The command parameter is not a valid value for the Stream.
In addition, if any of the following conditions occur, the STREAMS ioctl
commands return the corresponding value:
I_ATMARK
[EINVAL]
The arg parameter has an illegal value.
I_CANPUT
[EINVAL]
The arg parameter has an illegal value.
I_CKBAND
[EINVAL]
The arg parameter has an illegal value.
I_FDINSERT
[EINVAL]
The fildes parameter in the strfdinsert structure is an invalid, open
file descriptor.
[EINVAL]
The size of the pointer plus offset exceeds the value of the len field
for the buffer specified through ctlptr.
[EINVAL]
The offset parameter does not specify a properly aligned location in
the data buffer.
[EINVAL]
The flags parameter contains an undefined value.
[EFAULT]
The arg parameter points, or ctrlbuf or databuf is, outside the
allocated address space.
[EAGAIN]
The ioctl request failed because a non-priority message was to be
created, the O_NDELAY or O_NONBLOCK flag was set, and the Stream's
write queue was full because of internal flow control conditions.
[ENOSR]
Buffers could not be allocated for the message that was to be created
due to insufficient STREAMS memory resources.
[ENXIO]
A hangup was received on the Stream specified by fildes in the
I_FDINSERT ioctl call or on the Stream specified by fildes in the
strfdinsert.
[ERANGE]
The value of the len field for the buffer specified through databuf
does not fall within the range for the minimum and maximum sizes of
packets for the topmost module on the Stream.
[ERANGE]
The value of the len field for the buffer specified through databuf is
larger the the maximum allowable size for the data part of a message.
[ERANGE]
The value of the len field for the buffer specified through ctlbuf is
larger the the maximum allowable size for the control part of a
message.
The I_FDINSERT ioctl can also fail if an error (M_ERROR) message was
received by the Stream specified by the fildes field in the strfdinsert
structure. In this case, errno is set to the error value in the error
message.
I_FIND
[EINVAL]
The arg parameter does not contain a valid module name.
[EFAULT]
The arg parameter points outside the allocated address space.
I_FLUSH
[ENOSR]
Could not allocate buffers for flush operation because of a lack of
STREAMS memory resources.
[EINVAL]
The arg parameter is an invalid value.
[ENXIO]
A hangup was received on fildes.
I_FLUSHBAND
[EINVAL]
The bi_pr parameter value exceeds the maximum band, or the bi_flag
parameter is not FLUSHR, FLUSHW, or FLUSHRW.
I_GETBAND
[ENODATA]
No message exists on the Stream head read queue.
I_GETSIG
[EINVAL]
User process is not registered to receive the SIGPOLL signal.
[EFAULT]
The arg parameter points outside the allocated address space.
GRDOPT
[EINVAL]
The arg parameter is pointing outside the allocated address space.
I_LINK
[EAGAIN]
Temporarily unable to allocate storage to perform the linking
operation.
[EBADF]
The arg parameter is an invalid, open file descriptor.
[ENXIO]
A hangup was received on fildes.
[EINVAL]
The Stream referred to by fildes does not support multiplexing.
[EINVAL]
The file referred to by arg is not a Stream, or the Stream is already
linked under a multiplexor.
[EINVAL]
The link operation would cause a "cycle" in the resulting multiplexing
configuration. In other words, the driver referred to by the arg
parameter is linked into this configuration at multiple places
[EINVAL]
The fildes parameter is the file descriptor of a pipe.
The I_LINK ioctl can also fail if it is waiting for the multiplexing
driver to acknowledge the link request and an error (M_ERROR) message,
or hangup (M_HANGUP) message is received at the Stream head for fildes.
In addition, an error can be returned in an M_IOCACK or M_IOCNAK
message. When these occur, the I_LINK ioctl will fail with errno set to
the value in the message.
I_LIST
[EINVAL]
The sl_mods number members is less than 1.
[EAGAIN]
Could not allocate buffers.
I_LOOK
[EINVAL]
The named module is not present on the Stream.
[EFAULT]
The arg parameter points outside the allocated address space.
I_NREAD
[EFAULT]
The arg parameter is pointing outside the allocated address space.
I_PEEK
[EINVAL]
The flags parameter is an illegal value.
[EFAULT]
arg points, or ctrlbuf or databuf is, outside the allocated address
space.
[EBADMSG]
Message to be looked at is not valid for the I_PEEK command.
I_PLINK
[ENXIO]
A hangup was received on the Stream referred to by the fildes
parameter.
[ETIME]
A timeout occurred before an acknowledgement message was received at
the Stream head.
[EAGAIN]
Temporarily unable to allocate storage to perform the linking
operation.
[EBADF]
The arg parameter is an invalid, open file descriptor.
[EINVAL]
The Stream referred to by the fildes parameter does not support
multiplexing.
[EINVAL]
The file referred to by the arg parameter is not a Stream, or is
already linked under a multiplexing driver.
[EINVAL]
The link operation would cause a "cycle" in the resulting multiplexing
configuration. In other words, the driver referred to by the arg
parameter is linked into the configuration at multiple places.
[EINVAL]
The fildes parameter is the file descriptor of a pipe.
I_POP
[EINVAL]
The named module is not present on the Stream.
[ENXIO]
Error value returned by the module being popped.
[ENXIO]
A hangup was received on fildes.
I_PUNLINK
[ENXIO]
A hangup was received on fildes.
[ETIME]
A timeout occurred before an acknowledgement message was received at
the Stream head.
[EAGAIN]
Temporarily unable to allocate storage to perform the linking
operation.
[EINVAL]
The arg parameter is an invalid multiplexor ID number.
[EINVAL]
fildes is the file descriptor of a pipe.
An I_PUNLINK ioctl can also fail if it is waiting for the multiplexor
to acknowledge the unlink request and an error (M_ERROR) message, or
hangup (M_HANGUP) is received at the Stream head for fildes. In
addition, an error can be returned in an M_IOCACK or M_IOCNAK message.
When these occur, the PUNI_LINK ioctl will fail with errno set to the
value in the message.
I_PUSH
[EINVAL]
An invalid module name was used.
[EFAULT]
The arg parameter points outside the allocated address space.
[ENXIO]
Error value returned by the module being pushed. The push has failed.
[ENXIO]
A hangup was received on fildes.
I_RECVFD
[EAGAIN]
The O_ONDELAY or O_NONBOCK flag was set, and a message was not present
on the Stream head read queue,
[EFAULT]
The arg parameter points outside the allocated address space.
[EBADMSG]
The message present on the Stream head read queue did not contain a
passed file descriptor.
[EMFILE]
No more file descriptors are permitted to be opened.
[ENXIO]
A hangup was received on fildes.
I_SENDFD
[EAGAIN]
The sending Stream head could not allocate a message block for the file
pointer.
[EAGAIN]
The read queue of the receiving Stream head was full and could not
accept the message.
[EBADF]
The arg parameter is an invalid, open file descriptor.
[EINVAL]
The fildes parameter does not refer to a Stream pipe.
[ENXIO]
A hangup was received on fildes.
I_SETCLTIME
[EINVAL]
The arg parameter has an illegal value.
I_SETSIG
[EINVAL]
The user process is not registered to receive the SIGPOLL signal.
[EAGAIN]
A data structure to store the signal request could not be allocated.
I_SRDOPT
[EINVAL]
The arg parameter contains an illegal value.
I_STR
[EINVAL]
The ic_len field is less than 0 (zero) bytes or larger than the maximum
allowable size of the data part of a message (ic_dp).
[EINVAL]
The ic_timeout field is less than -1.
[EFAULT]
The arg parameter points, or the buffer area specified by ic_dp or
ic_len is, outside the allocated address space.
[ENOSR]
Buffers could not be allocated for the ioctl request because of a lack
of STREAMS memory resources.
[ENXIO]
A hangup was received on the Stream referred to by fildes.
[ETIME]
The ioctl request timed out before an acknowledgement was received.
The I_STR ioctl can also fail if the Stream head receives a message
indicating an error (M_ERROR) or a hangup (M_HANGUP). In addition, an
error can be returned in an M_IOCACK or M_IOCNAK message. In these
cases, the ioctl will fail with errno set to the error value in the
message.
I_SWROPT
[EINVAL]
The arg parameter is an illegal value.
I_UNLINK
[ENXIO]
A hangup was received on fildes.
[ETIME]
A timeout occurred before an acknowledgement message was received at
the Stream head.
[EINVAL]
The arg parameter is an invalid multiplexor ID number, or the fildes
parameter is already linked under a multiplexing driver.
[EINVAL]
The fildes parameter is the file descriptor of a pipe.
An I_UNLINK ioctl can also fail if it is waiting for the multiplexor to
acknowledge the unlink request and an error (M_ERROR) message, or
hangup (M_HANGUP) is received at the Stream head for fildes. In
addition, an error can be returned in M_IOCACK or M_IOCNAK message.
When this occurs, the I_UNLINK ioctl will fail with errno set to the
value in the message.
FILES
</sys/stream.h>
The system file containing all of the structure and constant
definitions for STREAMS.
</sys/types.h>
The system file that contains type definitions used in STREAMS header
files.
</sys/stropts.hO
The system file that contains definitions of the arguments to the
STREAMS M_FLUSH message type required by users and STREAMS modules and
drivers.
SEE ALSO
Functions: close(2), fattach(3), fcntl(2), fdetach(3), getmsg(2), ioctl(2),
open(2), poll(2), putmsg(2), read(2), sigaction(2), write(2)
Files: signal(4)
Standards: standards(5)
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Index for
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Alphabetical
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