t_rcvudata(3N)

NAME
     t_rcvudata - receive a data unit

SYNOPSIS
     #ifdef _XOPEN_SOURCE
     #include <xti.h>
     #else
     #include <tiuser.h>
     #endif

     int t_rcvudata (int fd, struct t_unitdata *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 t_unitdata 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, t_rcvudata operates in synchronous mode and will wait for a
     data unit to arrive if none is currently available.  However, if O_NDELAY
     or O_NONBLOCK is set (via t_open or fcntl), t_rcvudata 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 T_MORE will
     be set in flags on return to indicate that another t_rcvudata should be
     issued to retrieve the rest of the data unit.  Subsequent t_rcvudata
     call(s) will return zero for the length of the address and options until
     the full data unit has been received.

     This function resides within both the X/Open compliant libxnet and the
     SVR4 compliant libnsl Network Services libraries.  Network Services
     applications which require X/Open compliance must link-load with -lxnet.
     Network Services applications which require SVR4 compliance must link-
     load with -lnsl.
     On failure, t_errno may be set to one of the following:

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

     TNODATA             O_NDELAY or O_NONBLOCK was set, but no data units are
                         currently available from the transport provider.

     TBUFOVFLW           There are two different conditions in which TBUFOVFLW
                         will be returned.  If _XOPEN_SOURCE is defined and
                         the number of bytes allocated for incoming data is
                         greater than zero and is not sufficient to store the
                         data.  If _XOPEN_SOURCE is not defined and the number
                         of bytes allocated for incoming data is not
                         sufficient to store the data.  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.

     TOUTSTATE           If _XOPEN_SOURCE is defined and t_rcvudata() is
                         issued in the wrong sequence on the transport
                         endpoint referenced by fd, the TOUTSTATE error value
                         is returned within the variable t_errno.

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

SEE ALSO
     intro(3N), fcntl(2), t_alloc(3N), t_open(3N), t_rcvuderr(3N),
     t_sndudata(3N)

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