t_rcv(3N) t_rcv(3N)
NAME
t_rcv - receive normal or expedited data sent over a
connection
SYNOPSIS
cc [options] file -lnsl
#include <xti.h>
int t_rcv(int fd, char *buf, unsigned int nbytes, int *flags);
Parameters
fd the file descriptor for the transport endpoint through
which data will arrive.
buf points to the receive buffer where user data will be
placed.
nbytes specifies the size of the receive buffer.
flags specifies optional flags on return.
DESCRIPTION
This function is a TLI/XTI connection-mode data transfer
routine which retrieves normal or expedited data received over
a connection. The messages sent to the transport user may be
0-length.
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 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.
Copyright 1994 Novell, Inc. Page 1
t_rcv(3N) t_rcv(3N)
On return from the call, if T_EXPEDITED is set in flags 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.
Return Values
On successful completion, t_rcv returns the number of bytes
received. On failure, it returns -1 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_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 transport provider.
TSYSERR A system error has occurred during execution of
this function.
TOUTSTATE The function was issued in the wrong sequence
on the transport endpoint referenced by fd.
TPROTO A communication problem has been detected with
the transport provider and there is no other
value of t_errno to describe the error
condition.
Copyright 1994 Novell, Inc. Page 2
t_rcv(3N) t_rcv(3N)
State Transitions
On entry, T_DATAXFER or T_OUTREL; unchanged (successful) on
exit.
Files
/usr/lib/libxti.so
X/Open Transport Interface Library (shared
object)
/usr/lib/libnsl.so
Network Services Library (shared object)
USAGE
t_rcv is applicable only for connection-mode transport
services.
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.
REFERENCES
fcntl(2), intro(2), t_getinfo(3N), t_look(3N), t_open(3N),
t_snd(3N)
Copyright 1994 Novell, Inc. Page 3