stropts.h(0P)		   POSIX Programmer's Manual		 stropts.h(0P)

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 .

IEEE/The Open Group		     2017			 stropts.h(0P)