t_rcvudata(3N)    UNIX System V(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(3N)] 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.

      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


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t_rcvudata(3N)    UNIX System V(Networking Support Utilities)    t_rcvudata(3N)


                          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(3N), trcvuderr(3N), tsndudata(3N)
      Programmer's Guide:  Networking Interfaces

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




































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