T_RCV(3N)                            SysV                            T_RCV(3N)



NAME
     t_rcv - receive data or expedited data sent over a connection

SYNOPSIS
     int t_rcv(fd, buf, nbytes, flags)
     int fd;
     char *buf;
     unsigned nbytes;
     int *flags;

DESCRIPTION
     This function receives either normal or expedited data.  fd identifies
     the local transport endpoint through which data will arrive, buf points
     to a receive buffer where user data will be placed, and nbytes specifies
     the size of the receive buffer.  flags may be set on return from t_rcv
     and specifies optional flags as described below.

     By default, t_rcv operates in synchronous mode and will wait for data to
     arrive if none is currently available.  However, if O_NDELAY is set (via
     t_open or fcntl), t_rcv will execute in asynchronous mode and will fail
     if no data is available.  (See TNODATA below.)

     On return from the call, if T_MORE is set in flags this indicates that
     there is more data and the current transport service data unit (TSDU) or
     expedited transport service data unit (ETSDU) must be received in
     multiple t_rcv calls.  Each t_rcv with the T_MORE flag set indicates that
     another t_rcv must follow immediately to get more data for the current
     TSDU.  The end of the TSDU is identified by the return of a t_rcv call
     with the T_MORE flag not set.  If the transport provider does not support
     the concept of a TSDU as indicated in the info argument on return from
     t_open or t_getinfo, the T_MORE flag is not meaningful and should be
     ignored.

     On return, the data returned is expedited data if T_EXPEDITED is set in
     flags.  If the number of bytes of expedited data exceeds nbytes, t_rcv
     will set T_EXPEDITED and T_MORE on return from the initial call.
     Subsequent calls to retrieve the remaining ETSDU will not have
     T_EXPEDITED set on return.  The end of the ETSDU is identified by the
     return of a t_rcv call with the T_MORE flag not set.

     If expedited data arrives after part of a TSDU has been retrieved,
     receipt of the remainder of the TSDU will be suspended until the ETSDU
     has been processed.  Only after the full ETSDU has been retrieved (T_MORE
     not set) will the remainder of the TSDU be available to the user.

DIAGNOSTICS
     On successful completion, t_rcv returns the number of bytes received, and
     it returns -1 on failure and t_errno is set to indicate the error.

ERRORS
     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 was set, but no data is currently available
                        from the transport provider.

     [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
     t_open(3N), t_snd(3N)
     Programming with the SysV Transport Interface