T_RCVV(3NSL)T_RCVV(3NSL)NAMEt_rcvv - receive data or expedited data sent over a connection and put
the data into one or more non-contiguous buffers
SYNOPSIS
#include <xti.h>
int t_rcvv(int fd, struct t_iovec *iov, unsigned int iovcount, int *flags);
DESCRIPTION
This function receives either normal or expedited data. The argument
fd identifies the local transport endpoint through which data will
arrive, iov points to an array of buffer address/buffer size pairs
(iov_base, iov_len). The t_rcvv() function receives data into the buf‐
fers specified by iov0.iov_base, iov1.iov_base, through iov [iov‐
count-1].iov_base, always filling one buffer before proceeding to the
next.
Note that the limit on the total number of bytes available in all buf‐
fers passed:
iov(0).iov_len + . . + iov(iovcount-1).iov_len)
may be constrained by implementation limits. If no other constraint
applies, it will be limited by INT_MAX. In practice, the availability
of memory to an application is likely to impose a lower limit on the
amount of data that can be sent or received using scatter/gather func‐
tions.
The argument iovcount contains the number of buffers which is limited
to T_IOV_MAX, which is an implementation-defined value of at least 16.
If the limit is exceeded, the function will fail with TBADDATA.
The argument flags may be set on return from t_rcvv() and specifies
optional flags as described below.
By default, t_rcvv() operates in synchronous mode and will wait for
data to arrive if none is currently available. However, if O_NONBLOCK
is set by means of t_open(3NSL) or fcntl(2), t_rcvv() 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_rcvv() or t_rcv(3NSL) calls. In the asynchro‐
nous mode, or under unusual conditions (for example, the arrival of a
signal or T_EXDATA event), the T_MORE flag may be set on return from
the t_rcvv() call even when the number of bytes received is less than
the total size of all the receive buffers. Each t_rcvv() with the
T_MORE flag set indicates that another t_rcvv() must follow to get
more data for the current TSDU. The end of the TSDU is identified by
the return of a t_rcvv() 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(3NSL) or t_getinfo(3NSL),
the T_MORE flag is not meaningful and should be ignored. If the amount
of buffer space passed in iov is greater than zero on the call to
t_rcvv(), then t_rcvv() will return 0 only if the end of a TSDU is
being returned to the user.
On return, the data is expedited if T_EXPEDITED is set in flags. If
T_MORE is also set, it indicates that the number of expedited bytes
exceeded nbytes, a signal has interrupted the call, or that an entire
ETSDU was not available (only for transport protocols that support
fragmentation of ETSDUs). The rest of the ETSDU will be returned by
subsequent calls to t_rcvv() which will return with T_EXPEDITED set in
flags. The end of the ETSDU is identified by the return of a t_rcvv()
call with T_EXPEDITED set and T_MORE cleared. If the entire ETSDU is
not available it is possible for normal data fragments to be returned
between the initial and final fragments of an ETSDU.
If a signal arrives, t_rcvv() returns, giving the user any data cur‐
rently available. If no data is available, t_rcvv() returns -1, sets
t_errno to TSYSERR and errno to EINTR. If some data is available,
t_rcvv() returns the number of bytes received and T_MORE is set in
flags.
In synchronous mode, the only way for the user to be notified of the
arrival of normal or expedited data is to issue this function or check
for the T_DATA or T_EXDATA events using the t_look(3NSL) function.
Additionally, the process can arrange to be notified via the EM inter‐
face.
RETURN VALUES
On successful completion, t_rcvv() returns the number of bytes
received. Otherwise, it returns -1 on failure and t_errno is set to
indicate the error.
VALID STATES
T_DATAXFER, T_OUTREL.
ERRORS
On failure, t_errno is set to one of the following:
TBADDATA
iovcount is greater than T_IOV_MAX.
TBADF
The specified file descriptor does not refer to a trans‐
port endpoint.
TLOOK
An asynchronous event has occurred on this transport
endpoint and requires immediate attention.
TNODATA
O_NONBLOCK was set, but no data is currently available
from the transport provider.
TNOTSUPPORT
This function is not supported by the underlying trans‐
port provider.
TOUTSTATE
The communications endpoint referenced by fd is not in
one of the states in which a call to this function is
valid.
TPROTO
This error indicates that a communication problem has
been detected between XTI and the transport provider for
which there is no other suitable XTI error (t_errno).
TSYSERR
A system error has occurred during execution of this
function.
TLI COMPATIBILITY
In the TLI interface definition, no counterpart of this routine was
defined.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌───────────────┬─────────────────┐
│ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├───────────────┼─────────────────┤
│MT Level │ Safe │
└───────────────┴─────────────────┘
SEE ALSOfcntl(2), t_getinfo(3NSL), t_look(3NSL), t_open(3NSL), t_rcv(3NSL),
t_snd(3NSL), t_sndv(3NSL), attributes(5)
May 7, 1998 T_RCVV(3NSL)
