t_rcvudata(3N)          NETWORK FUNCTIONS          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 avail-
     able.  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 indi-
     cate  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



            Last change: Networking Support Utilities           1

t_rcvudata(3N)          NETWORK FUNCTIONS          t_rcvudata(3N)



                         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 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  exe-
                         cution of this function.

SEE ALSO
     intro(3), trcvuderr(3N), tsndudata(3N).
     UNIX System V Network Programmer's Guide.

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






























            Last change: Networking Support Utilities           2