t_rcv - receive data or expedited data sent over a connection
int t_rcv (int fd, char *buf, unsigned nbytes, int *flags);
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 or
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
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 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 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.
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 linkload
On failure, t_errno may be set to one of the following:
TBADF The specified file descriptor does not refer to a
TNODATA O_NDELAY or O_NONBLOCK 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
TOUTSTATE If _XOPEN_SOURCE is defined, then this error will be
returned within t_errno when t_rcv() was issued in the
wrong sequence on the transport endpoint referenced by
TSYSERR A system error has occurred during execution of this
fcntl(2), t_getinfo(3N), t_look(3N), t_open(3N), t_snd(3N)
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.
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