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 putmsg(2)							   putmsg(2)




 NAME
      putmsg, putpmsg - send a message on a stream

 SYNOPSIS
      #include <&lt&lt&lt;stropts.h>&gt&gt&gt;

      int putmsg(
	   int fildes,
	   struct strbuf *ctlptr,
	   struct strbuf *dataptr,
	   int flags
      );

      int putpmsg(
	   int fildes,
	   struct strbuf *ctlptr,
	   struct strbuf *dataptr,
	   int band,
	   int flags
      );

 DESCRIPTION
      The putmsg() function creates a message from a process buffer(s) and
      sends the message to a STREAMS file.  The message may contain either a
      data part, a control part, or both.  The data and control parts are
      distinguished by placement in separate buffers, as described below.
      The semantics of each part is defined by the STREAMS module that
      receives the message.

      The putpmsg() function does the same things as putmsg(), but the
      process can send messages in different priority bands.  Except where
      noted, all requirements on putmsg() also pertain to putpmsg().

      The fildes argument specifies a file descriptor referencing an open
      stream.  The ctlptr and dataptr arguments each point to a strbuf
      structure.

      The ctlptr argument points to the structure describing the control
      part, if any, to be included in the message.  The buf member in the
      strbuf structure points to the buffer where the control information
      resides, and the len member indicates the number of bytes sent.  The
      maxlen member is not used by putmsg().  In a similar manner, the
      argument dataptr specifies the data, if any, to be included in the
      message.	The flags argument indicates what type of message should be
      sent and is described further below.

      To send the data part of a message, dataptr must not be a null pointer
      and the len member of dataptr must be 0 or greater.  To send the
      control part of a message, the corresponding values must be set for
      ctlptr.  No data (control) part will be sent if either dataptr
      (ctlptr) is a null pointer or the len member of dataptr (ctlptr) is



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 putmsg(2)							   putmsg(2)




      set to -1.

      For putmsg(), if a control part is specified and flags is set to
      RS_HIPRI, a high priority message is sent.  If no control part is
      specified, and flags is set to RS_HIPRI, putmsg() fails and sets errno
      to [EINVAL].  If flags is set to 0, a normal message (priority band
      equal to 0) is sent.  If a control part and data part are not
      specified and flags is set to 0, no message is sent and 0 is returned.

      The stream head guarantees that the control part of a message
      generated by putmsg() is at least 64 bytes in length.

      For putpmsg(), the flags are different.  The flags argument is a
      bitmask with the following mutually-exclusive flags defined: MSG_HIPRI
      and MSG_BAND.  If flags is set to 0, putpmsg() fails and sets errno to
      [EINVAL].	 If a control part is specified and flags is set to
      MSG_HIPRI and band is set to 0, a high-priority message is sent.	If
      flags is set to MSG_HIPRI and either no control part is specified or
      band is set to a non-zero value, putpmsg() fails and set errno to
      [EINVAL].	 If flags is set to MSG_BAND, then a message is sent in the
      priority band specified by band.	If a control part and data part are
      not specified and flags is set to MSG_BAND, no message is sent and 0
      is returned.

      The putmsg() function blocks if the stream write queue is full due to
      internal flow control conditions.	 For high-priority messages,
      putmsg() does not block on this condition.  For other messages,
      putmsg() does not block when the write queue is full and O_NONBLOCK is
      set.

      The putmsg() function also blocks, unless prevented by lack of
      internal resources, while for the availability of message blocks in
      the stream, regardless of priority of whether O_NONBLOCK has been
      specified.  No partial message is sent.

 MULTITHREAD USAGE
      The putmsg() and putpmsg() functions are safe to be called by
      multithreaded applications, and they are thread-safe for both POSIX
      Threads and DCE User Threads.  The putmsg() and putpmsg() functions
      have cancellation points. They are async-signal safe and fork-safe.
      They are not async-cancel safe.

 RETURN VALUE
      Upon successful completion, putmsg() and putpmsg() return 0.
      Otherwise, they return -1 and set errno to indicate the error.

 ERRORS
      [EAGAIN]	     A non-priority message was specified, the O_NONBLOCK
		     flag is set, and the stream write queue is full due to
		     internal flow control conditions, or buffers could not
		     be allocated for the message that was to be created.



 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000






 putmsg(2)							   putmsg(2)




      [EBADF]	     fildes is not a valid file descriptor open for writing.

      [EINTR]	     A signal was caught during putmsg() or putpmsg().

      [EINVAL]	     An undefined value is specified in flags, or flags is
		     set to RS_HIPRI or MSG_HIPRI and no control part is
		     supplied, or the stream or multiplexor referenced by
		     fildes is linked (directly or indirectly) downstream
		     from a multiplexor, or flags is set to MSG_HIPRI and
		     band is non-zero (for putpmsg() only).

      [ENOSTR]	     A stream is not associated with fildes.

      [ENXIO]	     A hangup condition was generated downstream for the
		     specified stream.

      [EPIPE] or [EIO]
		     The fildes argument refers to a STREAMS-based pipe and
		     the other end of the pipe is closed.  A SIGPIPE signal
		     is generated for the calling process.

      [ERANGE]	     The size of the data part of the message does not fall
		     within the range specified by the maximum and minimum
		     packet sizes of the topmost STREAMS module.  This value
		     is also returned if the control part of the message is
		     larger than the maximum configured size of the control
		     part of a message, or if the data part of the message
		     is larger than the maximum configured size of the data
		     part of a message.

      In addition, putmsg() and putpmsg() will fail if the stream head had
      processed an asynchronous error before the call.	In this case, the
      value of errno does not reflect the result of putmsg() or putpmsg()
      but reflects the prior error.

 SEE ALSO
      getmsg(2), poll(2), read(2), write(2), <stropts.h>, streamio(7).

















 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000