pckt(7)                          DG/UX R4.11                         pckt(7)


NAME
       pckt - STREAMS Packet Mode module

DESCRIPTION
       pckt is a STREAMS module that may be used with a pseudo terminal to
       packetize certain messages.  The pckt module should be pushed [see
       IPUSH, streamio(7)] onto the master side of a pseudo terminal.

       Packetizing is performed by prefixing a message with an MPROTO
       message.  The original message type is stored in the one byte data
       portion of the MPROTO message.

       On the read-side, only the MPROTO, MPCPROTO, MSTOP, MSTART,
       MSTOPI, MSTARTI, MIOCTL, MDATA, MFLUSH, and MREAD messages are
       packetized.  All other message types are passed upstream unmodified.

       Since all unread state information is held in the master's stream
       head read queue, flushing of this queue is disabled.

       On the write-side, all messages are sent down unmodified.

       With this module in place, all reads from the master side of the
       pseudo terminal should be performed with the getmsg(2) or getpmsg()
       system call.  The control part of the message contains the message
       type.  The data part contains the actual data associated with that
       message type.  The onus is on the application to separate the data
       into its component parts.

SEE ALSO
       crash(1M), getmsg(2), ioctl(2),
       ldterm(7), ptem(7), streamio(7), termio(7).
       Programmer's Guide: STREAMS.


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