stropts.h(7POSIX)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME
stropts.h — STREAMS interface (STREAMS)

SYNOPSIS

#include <stropts.h>

DESCRIPTION
The <stropts.h> header shall define the bandinfo structure, which shall include at least the following members:

    int            bi_flag  Flushing type.
    unsigned char  bi_pri   Priority band.

The <stropts.h> header shall define the strpeek structure, which shall include at least the following members:

    struct strbuf  ctlbuf   The control portion of the message.
    struct strbuf  databuf  The data portion of the message.
    t_uscalar_t    flags    RS_HIPRI or 0.

The <stropts.h> header shall define the strbuf structure, which shall include at least the following members:

    char  *buf     Pointer to buffer.
    int    len     Length of data.
    int    maxlen  Maximum buffer length.

The <stropts.h> header shall define the strfdinsert structure, which shall include at least the following members:

    struct strbuf  ctlbuf   The control portion of the message.
    struct strbuf  databuf  The data portion of the message.
    int            fildes   File descriptor of the other STREAM.
    t_uscalar_t    flags    RS_HIPRI or 0.
    int            offset   Relative location of the stored value.

The <stropts.h> header shall define the strioctl structure, which shall include at least the following members:

    int    ic_cmd     ioctl() command.
    char  *ic_dp      Pointer to buffer.
    int    ic_len     Length of data.
    int    ic_timout  Timeout for response.

The <stropts.h> header shall define the strrecvfd structure, which shall include at least the following members:

    int    fd   Received file descriptor.
    gid_t  gid  GID of sender.
    uid_t  uid  UID of sender.

The <stropts.h> header shall define the uid_t and gid_t types through typedef, as described in <sys/types.h>.

The <stropts.h> header shall define the t_scalar_t and t_uscalar_t types, respectively, as signed and unsigned opaque types of equal length of at least 32 bits.

The <stropts.h> header shall define the str_list structure, which shall include at least the following members:

    struct str_mlist  *sl_modlist  STREAMS module names.
    int                sl_nmods    Number of STREAMS module names.

The <stropts.h> header shall define the str_mlist structure, which shall include at least the following member:

    char  l_name[FMNAMESZ+1]  A STREAMS module name.

The <stropts.h> header shall define at least the following symbolic constants for use as the request argument to ioctl():

I_ATMARK
    Is the top message ``marked''?

I_CANPUT
    Is a band writable?

I_CKBAND
    See if any messages exist in a band.

I_FDINSERT
    Send implementation-defined information about another STREAM.

I_FIND
    Look for a STREAMS module.

I_FLUSH
    Flush a STREAM.

I_FLUSHBAND
    Flush one band of a STREAM.

I_GETBAND
    Get the band of the top message on a STREAM.

I_GETCLTIME
    Get close time delay.

I_GETSIG
    Retrieve current notification signals.

I_GRDOPT
    Get the read mode.

I_GWROPT
    Get the write mode.

I_LINK
    Connect two STREAMs.

I_LIST
    Get all the module names on a STREAM.

I_LOOK
    Get the top module name.

I_NREAD
    Size the top message.

I_PEEK
    Peek at the top message on a STREAM.

I_PLINK
    Persistently connect two STREAMs.

I_POP
    Pop a STREAMS module.

I_PUNLINK
    Dismantle a persistent STREAMS link.

I_PUSH
    Push a STREAMS module.

I_RECVFD
    Get a file descriptor sent via I_SENDFD.

I_SENDFD
    Pass a file descriptor through a STREAMS pipe.

I_SETCLTIME
    Set close time delay.

I_SETSIG
    Ask for notification signals.

I_SRDOPT
    Set the read mode.

I_STR
    Send a STREAMS ioctl().

I_SWROPT
    Set the write mode.

I_UNLINK
    Disconnect two STREAMs.

The <stropts.h> header shall define at least the following symbolic constant for use with I_LOOK:

FMNAMESZ
    The minimum size in bytes of the buffer referred to by the arg argument.

The <stropts.h> header shall define at least the following symbolic constants for use with I_FLUSH:

FLUSHR
    Flush read queues.

FLUSHRW
    Flush read and write queues.

FLUSHW
    Flush write queues.

The <stropts.h> header shall define at least the following symbolic constants for use with I_SETSIG:

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
    Notification of an error condition reaches the STREAM head.

S_HANGUP
    Notification of a hangup reaches the STREAM head.

S_HIPRI
    A high-priority message is present on a STREAM head read queue.

S_INPUT
    A message, other than a high-priority message, has arrived at the head of a STREAM head read queue.

S_MSG
    A STREAMS signal message that contains the SIGPOLL signal reaches the front of the STREAM head read queue.

S_OUTPUT
    The write queue for normal data (priority band 0) just below the STREAM head is no longer full. This notifies the process that there is room on the queue for sending (or writing) normal data downstream.

S_RDBAND
    A message with a non-zero priority band has arrived at the head of a STREAM head read queue.

S_RDNORM
    A normal (priority band set to 0) message has arrived at the head of a STREAM head read queue.

S_WRBAND
    The write queue for a non-zero priority band just below the STREAM head is no longer full.

S_WRNORM
    Equivalent to S_OUTPUT.

The <stropts.h> header shall define at least the following symbolic constant for use with I_PEEK:

RS_HIPRI
    Only look for high-priority messages.

The <stropts.h> header shall define at least the following symbolic constants for use with I_SRDOPT:

RMSGD
    Message-discard mode.

RMSGN
    Message-non-discard mode.

RNORM
    Byte-STREAM mode, the default.

RPROTDAT
    Deliver the control part of a message as data when a process issues a read().

RPROTDIS
    Discard the control part of a message, delivering any data part, when a process issues a read().

RPROTNORM
    Fail read() with [EBADMSG] if a message containing a control part is at the front of the STREAM head read queue.

The <stropts.h> header shall define at least the following symbolic constant for use with I_SWOPT:

SNDZERO
    Send a zero-length message downstream when a write() of 0 bytes occurs.

The <stropts.h> header shall define at least the following symbolic constants for use with I_ATMARK:

ANYMARK
    Check if the message is marked.

LASTMARK
    Check if the message is the last one marked on the queue.

The <stropts.h> header shall define at least the following symbolic constant for use with I_UNLINK:

MUXID_ALL
    Unlink all STREAMs linked to the STREAM associated with fildes.

The <stropts.h> header shall define the following symbolic constants for getmsg(), getpmsg(), putmsg(), and putpmsg():

MORECTL
    More control information is left in message.

MOREDATA
    More data is left in message.

MSG_ANY
    Receive any message.

MSG_BAND
    Receive message from specified band.

MSG_HIPRI
    Send/receive high-priority message.

The <stropts.h> header may make visible all of the symbols from <unistd.h>.

The <stropts.h> header may also define macros for message types using names that start with M_.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

    int    fattach(int, const char *);
    int    fdetach(const char *);
    int    getmsg(int, struct strbuf *restrict, struct strbuf *restrict,
               int *restrict);
    int    getpmsg(int, struct strbuf *restrict, struct strbuf *restrict,
               int *restrict, int *restrict);
    int    ioctl(int, int, ...);
    int    isastream(int);
    int    putmsg(int, const struct strbuf *, const struct strbuf *, int);
    int    putpmsg(int, const struct strbuf *, const struct strbuf *, int,
               int);

The following sections are informative.

APPLICATION USAGE
None.

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
<sys_types.h>, <unistd.h>

The System Interfaces volume of POSIX.1-2017, close(), fattach(), fcntl(), fdetach(), getmsg(), ioctl(), isastream(), open(), pipe(), read(), poll(), putmsg(), signal(), write()

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .