pckt(7)                          UNIX System V                          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 4 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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