t_rcvudata(3N)        (Networking Support Utilities)         t_rcvudata(3N)


   NAME
         trcvudata - receive a data unit

   SYNOPSIS
         #include <tiuser.h>

         int trcvudata (int fd, struct tunitdata *unitdata, int *flags);

   DESCRIPTION
         This function is used in connectionless mode to receive a data unit
         from another transport user.  fd identifies the local transport
         endpoint through which data will be received, unitdata holds
         information associated with the received data unit, and flags is set
         on return to indicate that the complete data unit was not received.
         unitdata points to a tunitdata structure containing the following
         members:

               struct netbuf addr;
               struct netbuf opt;
               struct netbuf udata;

         The maxlen [see netbuf in intro(3)] field of addr, opt, and udata
         must be set before issuing this function to indicate the maximum size
         of the buffer for each.

         On return from this call, addr specifies the protocol address of the
         sending user, opt identifies protocol-specific options that were
         associated with this data unit, and udata specifies the user data
         that was received.

         By default, trcvudata operates in synchronous mode and will wait for
         a data unit to arrive if none is currently available.  However, if
         ONDELAY or ONONBLOCK is set (via topen or fcntl), trcvudata will
         execute in asynchronous mode and will fail if no data units are
         available.

         If the buffer defined in the udata field of unitdata is not large
         enough to hold the current data unit, the buffer will be filled and
         TMORE will be set in flags on return to indicate that another
         trcvudata should be issued to retrieve the rest of the data unit.
         Subsequent trcvudata call(s) will return zero for the length of the
         address and options until the full data unit has been received.

         On failure, terrno may be set to one of the following:

         [TBADF]             The specified file descriptor does not refer to a
                             transport endpoint.

         [TNODATA]           ONDELAY or ONONBLOCK was set, but no data units
                             are currently available from the transport
                             provider.


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   t_rcvudata(3N)        (Networking Support Utilities)         t_rcvudata(3N)


         [TBUFOVFLW]         The number of bytes allocated for the incoming
                             protocol address or options is not sufficient to
                             store the information.  The unit data information
                             to be returned in unitdata will be discarded.

         [TLOOK]             An asynchronous event has occurred on this
                             transport endpoint and requires immediate
                             attention.

         [TNOTSUPPORT]       This function is not supported by the underlying
                             transport provider.

         [TSYSERR]           A system error has occurred during execution of
                             this function.

   SEE ALSO
         intro(3), trcvuderr(3N), tsndudata(3N).
         Programmer's Guide: Networking Interface.

   DIAGNOSTICS
         trcvudata returns 0 on successful completion and -1 on failure and
         terrno is set to indicate the error.































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