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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 may command
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.
RELATED INFORMATION
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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