streamio(7) streamio(7)
NAME [Toc] [Back]
streamio - STREAMS ioctl commands
SYNOPSIS [Toc] [Back]
#include <sys/types.h>
#include <stropts.h>
int ioctl(int fildes, int command, ... /* arg */);
DESCRIPTION [Toc] [Back]
STREAMS ioctl commands are a subset of the ioctl() system calls which
perform a variety of control functions on streams.
fildes is an open file descriptor that refers to a stream. command
determines the control function to be performed as described below.
arg 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 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 a subset of ioctl, they are subject
to the errors described there. 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, 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
system calls to fail with errno set to this value.
The following ioctl commands, with error values indicated, are
applicable to all STREAMS files:
I_ATMARK Allows the user to see if the current message on
the stream head read queue is "marked" by some
module downstream. arg determines how the checking
is done when there are multiple marked messages on
the stream head read queue. It may take the
following values:
ANYMARK Checks if the message is marked.
LASTMARK Checks if the message is the last
one that is marked on the queue.
If both ANYMARK and LASTMARK are set, ANYMARK
supersedes LASTMARK.
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The return value is 1 if the mark condition is
satisfied and 0 otherwise.
I_CANPUT Checks 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.
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,
or -1 on error. arg should be an integer
containing the value of the priority band in
question.
I_FDINSERT Creates a message from user 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.
arg points to a strfdinsert structure which
contains the following members:
struct strbuf ctlbuf;
struct strbuf databuf;
long options;
int fildes;
int offset;
The len field in the ctlbuf strbuf structure (see
putmsg(2)) must be set to the size of a pointer
plus the number of bytes of control information to
be sent with the message. fildes in the
strfdinsert structure specifies the file
descriptor of the other stream. offset, which
must be word-aligned, specifies the number of
bytes beyond the beginning of the control buffer
where I_FDINSERT will store a pointer. This
pointer will be the address of the read queue
structure of the driver for the streams
corresponding to fildes in the strfdinsert
structure. The len field in the databuf strbuf
structure must be set to the number of bytes of
data information to be sent with the message or
zero if no data part is to be sent.
flags specifies the type of message to be created.
An ordinary (non-priority) message is created if
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flags is set to 0, a high priority message is
created if flags is set to RS_HIPRI. For normal
messages, I_FDINSERT will block if the stream
write queue is full due to internal flow control
conditions. For high priority messages,
I_FDINSERT does not block on this condition. For
normal messages, I_FDINSERT does not block when
the write queue is full and the O_NONBLOCK is set.
Instead, it fails and sets errno to [EAGAIN].
I_FDINSERT also blocks, unless prevented by the
lack of internal resources, waiting for the
availability of message blocks, regardless of
priority or whether O_NONBLOCK has been specified.
No partial message is sent.
I_FDINSERT can also fail if an error message was
received by the stream head of the stream
corresponding to fildes in the strfdinsert
structure. In this case, errno will be set to the
value in the message.
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 if the
module is present and a value of 0 (zero) if the
module is not present.
I_FLUSH This request flushes all input and/or output
queues, depending on the value of arg. Valid arg
values are:
FLUSHRW Flush write and read queues.
FLUSHW Flush write queues.
FLUSHR Flush read queues.
If a pipe or FIFO does not have any modules
pushed, the read queue of the streams 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
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queue for this end is flushed. If fildes is a
FIFO, both queues of the FIFO are flushed.
If FLUSHRW is set, all read queues are flushed,
that is the read queue for the FIFO and the read
queue of boths ends of the pipe are flushed.
Correct flushing 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.
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_option;
The value of the bi_option field can be FLUSHR,
FLUSHW, or FLUSHRW as described for the I_FLUSH
command.
I_GETBAND Returns the priority band of the first message on
the stream head read queue in the integer
referenced by arg.
I_GETCLTIME Returns the close time delay in the long pointed
by arg.
I_SETCLTIME Allows the user to set the time that the stream
head will delay when a stream is closing, and
there is 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. If, after the delay, data is still
present, data will be flushed. arg is a pointer to
the number of milliseconds to delay, rounded up to
the nearest valid value on the system. The
default is fifteen seconds.
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 in an int
pointed to by the argument arg. Read modes are
described in read(2).
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I_GWROPT Returns the current write mode setting, as
described in I_SWROPT, in the int that is pointed
to by the argument arg.
I_LINK Connects two streams, where fildes is the file
descriptor of the stream connected to the
multiplexing driver, and arg is the file
descriptor 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
acknowledgement message to the stream head
regarding the linking operation. This call
returns a multiplexor ID number (an identifier
used to disconnect the multiplexor, see I_UNLINK)
on success, and -1 on failure.
I_LIST Allows the user to list all the module names on
the stream, up to and including the topmost 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 not NULL, it should point to a
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];
sl_nmods indicates the number of entries the user
has allocated in the array. On success, the
return value is 0, sl_modlist contains the list of
module names, and sl_nmods indicates the number of
entries that have been filled in.
I_LOOK Retrieves the name of the module located just
below the streams 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 FNAMESZ+1
bytes long. A #include <stropts.h> declaration is
required.
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
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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.
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 options;
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 options 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
options contains RS_HIPRI or 0 (zero).
I_PLINK Connects two streams, where fildes is the file
descriptor of the stream connected to the
multiplexing driver, and arg is the file
descriptor 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
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message to the stream head regarding the linking
operation. This call creates a persistent link
which can exist even if the file descriptor
associated with the upper stream to the
multiplexing driver is closed. This call returns
a multiplexor ID number (an identifier that may be
used to disconnect the multiplexor, see I_PUNLINK)
on success and -1 on failure.
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_IOACK or M_IONAK message.
When these occur, the I_PLINK fails with errno set
to the value in the message.
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.
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. 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
which are persistent links to fildes are
disconnected. As in I_PLINK, this command
requires the multiplexing driver to acknowledge
the unlink.
I_PUSH Pushes the module whose name is pointed 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 streams heads of both
ends of the pipe. It then calls the open routine
of the newly-pushed module.
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 a strrecvfd data structure
containing the following members:
int fd;
uid_t uid;
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gid_t gid;
char fill[8]
fd is an integer file descriptor. uid and gid are
the user ID and group ID, respectively, of the
sending stream.
If O_NONBLOCK is clear, I_RECVFD will block until
a message is present at the stream head. If
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 message
sent by a 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.
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 of the stream head at
the other end of the stream pipe to which it is
connected.
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 STREAMS modules and drivers are closed, the
stream head delays for the specified amount of
time. This allows the data on the write queues to
drain. If data is still present on the writes
queues after the delay, the queues are flushed.
I_SETSIG Informs the stream head that the user wants the
kernel to issue the SIGPOLL signal (see signal(2))
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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, except where
noted, of the following constants:
S_BANDURG When used in conjunction with
S_RDBAND, SIGURG is generated
instead of SIGPOLL when a
priority message reaches the
front of the stream head read
queue.
S_ERROR An M_ERROR message has reached
the stream head.
S_HANGUP An M_HANGUP message has
reached the stream head.
S_HIPRI A high priority message is
present on the stream head
read queue. This is set even
if the message is of zero
length.
S_INPUT Any message other than an
M_PCPROTO has arrived on a
stream head read queue. This
event is maintained for
compatibility with prior
releases. This is set even if
the message is of zero length.
S_MSG A STREAMS signal message that
contains the SIGPOLL signal
has reached the front of the
stream head read queue.
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
downstream.
S_RDBAND A priority band message (band
> 0) has arrived on a stream
head read queue. This is set
even if the message is of
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zero-length.
S_RDNORM An ordinary (non-priority)
message has arrived on a
stream head read queue. This
is set even if the message is
of zero-length.
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_WRNORM This event is the same as
S_OUTPUT.
A user process may choose to be signaled only of
high priority messages by setting arg bitmask to
the value S_HIPRI.
Processes that want to receive SIGPOLL signals
must explicitly register to receive them using
I_SETSIG. If several processes register to
receive the signal for the same event on the same
stream, each process will be signaled when the
event occurs.
If the value of arg is zero, the calling process
will be unregistered and will not receive further
SIGPOLL signals.
I_SRDOPT Sets the read mode (see read(2)) using the value
of the argument arg. Valid arg values are:
RNORM Byte-stream mode (default).
RMSGD Message-discard mode.
RMSGN Message-nondiscard mode.
Setting both RMSGD and RMSGN is an error. RMSGD
and RMSGN override NORM.
In addition, treatment of control messages by the
stream head may be changed by setting the
following flags in arg:
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RPROTNORM Fail read with EBADMSG if a
control message is at the
front of the stream head read
queue. This is the default
behavior.
RPROTDAT Deliver the control portion of
a message as data when a user
issues read.
RPROTDIS Discard the control portion of
a message, delivering any data
portion, when a user issues a
read.
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. It
allows information to be sent with the ioctl, and
will return to the user any information sent
upstream by the downstream recipient. I_STR blocks
until the system responds with either a positive
or negative acknowledgement message, or until the
request "times out" after some period of time. If
the request times out, it fails with errno set to
ETIME.
At most, one I_STR can be active on a stream.
Further I_STR calls will block until the active
I_STR completes at the stream head. The default
timeout intervals for these requests is 15
seconds. The O_NONBLOCK (see open(2)) flags have
no effect on this call.
To send requests downstream, arg must point to a
strioctl structure which contains the following
members:
int ic_cmd;
int ic_timeout;
int ic_len;
char *ic_dp;
ic_cmd is the internal ioctl command intended for
the downstream module or driver and ic_timeout is
the number of seconds (-1 =infinite, 0 = use
default, >0 = as specified) an I_STR request will
wait for acknowledgement before timing out. The
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default timeout is infinite. 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 driver
in the stream can return). The stream head will
convert the information pointed to by strioctl
structure to an internal ioctl command message and
send it downstream.
I_SWROPT Sets the write mode using the value of the
argument arg. Legal bit settings for arg are:
SNDZERO Sends a zero-length message
downstream 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.
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 MUXID_ALL, then all streams
which were linked to fildes are disconnected. As
in I_LINK, this command requires the multiplexing
driver to acknowledge the unlink.
RETURN VALUE [Toc] [Back]
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 [Toc] [Back]
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:
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I_ATMARK [Toc] [Back]
[EINVAL] arg has an illegal value.
I_CANPUT [Toc] [Back]
[EINVAL] arg has an illegal value.
I_CKBAND [Toc] [Back]
[EINVAL] arg has an illegal value.
I_FDINSERT [Toc] [Back]
[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] offset does not specify a properly aligned
location in the data buffer.
[EINVAL] options contains an undefined value.
[EFAULT] arg 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_NONBLOCK option
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 top-most module on the stream.
[ERANGE] The value of the len field for the buffer
specified through databuf is larger than the
maximum allowable size for the data part of a
message.
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[ERANGE] The value of the len field for the buffer
specified through ctlbuf is larger than 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 [Toc] [Back]
[EINVAL] arg does not contain a valid module name.
[EFAULT] arg points outside the allocated address space.
I_FLUSH [Toc] [Back]
[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 [Toc] [Back]
[EINVAL] The bi_pr parameter value exceeds the maximum
band, or the bi_option parameter is not FLUSHR,
FLUSHW, or FLUSHRW.
I_GETBAND [Toc] [Back]
[ENODATA] No message exists on the stream head read queue.
I_GETSIG [Toc] [Back]
[EINVAL] User process is not registered to receive the
SIGPOLL signal.
[EFAULT] arg points outside the allocated address space.
I_GRDOPT [Toc] [Back]
[EFAULT] arg is pointing outside the allocated address
space.
I_LINK [Toc] [Back]
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[EAGAIN] Temporarily unable to allocate storage to perform
the linking operation.
[EBADF] The arg parameter not a valid 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
[ENOSR] Not enough STREAMS memory resources to allocate
storage for this command.
[ETIME] Acknowledgement message not received at stream
head before timeout.
The I_LINK ioctl can also fail if an M_ERROR or M_HANGUP
message is received at the stream head for fildes before
receiving the driver acknowledgement. In addition, an error
can be returned in an M_IOCACK or M_IOCNAK message. When
these occur, the I_LINK ioctl fails with errno set to the
value in the message.
I_LIST [Toc] [Back]
[EINVAL] sl_nmods is less than 1.
[EAGAIN] Could not allocate buffers.
I_LOOK [Toc] [Back]
[EINVAL] There are no modules in the stream.
[EFAULT] arg points outside the allocated address space.
I_NREAD [Toc] [Back]
[EFAULT] arg is pointing outside the allocated address
space.
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I_PEEK [Toc] [Back]
[EINVAL] The options 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 [Toc] [Back]
[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] arg is not a valid open file descriptor.
[EINVAL] The stream referred to by fildes does not support
multiplexing.
[EINVAL] The file referred to by arg 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 arg is linked
into the configuration at multiple places.
I_POP [Toc] [Back]
[EINVAL] There are not modules in the stream.
[ENXIO] Error value returned by the module being popped.
[ENXIO] A hangup was received on fildes.
I_PUNLINK [Toc] [Back]
[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.
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[EINVAL] arg 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 P_UNLINK ioctl fails with errno set to the value
in the message.
I_PUSH [Toc] [Back]
[EINVAL] An invalid module name was used.
[EFAULT] arg 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 [Toc] [Back]
[EAGAIN] The O_NONBLOCK option 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] Too many open files. No more file descriptors are
permitted to be opened.
[ENXIO] A hangup was received on fildes.
I_SENDFD [Toc] [Back]
[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 not a valid open file
descriptor.
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streamio(7) streamio(7)
[EINVAL] The fildes parameter does not refer to a stream.
[ENXIO] A hangup was received on fildes.
I_SETCLTIME [Toc] [Back]
[EINVAL] arg has an illegal value.
I_SETSIG [Toc] [Back]
[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 [Toc] [Back]
[EINVAL] arg contains an illegal value.
I_STR [Toc] [Back]
[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] arg 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
fails with errno set to the error value in the message.
I_SWROPT [Toc] [Back]
[EINVAL] The arg parameter is an illegal value.
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streamio(7) streamio(7)
I_UNLINK [Toc] [Back]
[ENXIO] A hangup was received on fildes.
[ETIME] A timeout occurred before an acknowledgement
message was received at the stream head.
[EINVAL] arg is an invalid multiplexor ID number, or
fildes is already linked under a multiplexing
driver.
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 fails with errno set to the value in the
message.
SEE ALSO [Toc] [Back]
close(2), fcntl(2), getmsg(2), ioctl(2), open(2), poll(2), putmsg(2),
read(2), write(2), signal(5).
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