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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 .