int t_rcv(int fd, char buf, unsigned int nbytes, int flags);
By default, t_rcv operates in synchronous mode and will wait for data to arrive if none is currently available. However, if O_NONBLOCK 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
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 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 from the call, if T_EXPEDITED is set in
the data returned is expedited data.
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 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.
In synchronous mode, t_look may alternatively be used to notify the transport user that normal or expedited data has been received or that flow control restrictions have been lifted. Additional functionality is provided by the Event Management Interface.