Tribblix: manual page: t

T_SNDVUDATA(3NSL) Networking Services Library Functions T_SNDVUDATA(3NSL)

NAME

t_sndvudata - send a data unit from one or more noncontiguous buffers

SYNOPSIS

#include <xti.h>

int t_sndvudata(int fd, struct t_unitdata *unitdata, struct t_iovec *iov,
unsigned int iovcount);

DESCRIPTION

This function is used in connectionless mode to send a data unit to
another transport user. The argument fd identifies the local
transport endpoint through which data will be sent, iovcount
contains the number of non-contiguous udata buffers and is limited
to an implementation-defined value given by T_IOV_MAX which is at
least 16, and unitdata points to a t_unitdata structure containing
the following members:

struct netbuf addr;
struct netbuf opt;
struct netbuf udata;

If the limit on iovcount is exceeded, the function fails with
TBADDATA.

In unitdata, addr specifies the protocol address of the destination
user, and opt identifies options that the user wants associated with
this request. The udata field is not used. The user may choose not
to specify what protocol options are associated with the transfer by
setting the len field of opt to zero. In this case, the provider
may use default options.

The data to be sent is identified by iov[0] through iov
[iovcount-1].

Note that the limit on the total number of bytes available in all
buffers 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
functions.

By default, t_sndvudata() operates in synchronous mode and may wait
if flow control restrictions prevent the data from being accepted by
the local transport provider at the time the call is made. However,
if O_NONBLOCK is set by means of t_open(3NSL) or fcntl(2),
t_sndvudata() executes in asynchronous mode and will fail under such
conditions. The process can arrange to be notified of the clearance
of a flow control restriction by means of either t_look(3NSL) or the
EM interface.

If the amount of data specified in iov0 through iov [iovcount-1]
exceeds the TSDU size as returned in the tsdu field of the info
argument of t_open(3NSL) or t_getinfo(3NSL), or is zero and sending
of zero octets is not supported by the underlying transport service,
a TBADDATA error is generated. If t_sndvudata() is called before
the destination user has activated its transport endpoint (see
t_bind(3NSL)), the data unit may be discarded.

If it is not possible for the transport provider to immediately
detect the conditions that cause the errors TBADADDR and TBADOPT,
these errors will alternatively be returned by t_rcvuderr(3NSL). An
application must therefore be prepared to receive these errors in
both of these ways.

RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned and t_errno is set to indicate an error.

VALID STATES

T_IDLE.

ERRORS

On failure, t_errno is set to one of the following:

TBADADDR
The specified protocol address was in an incorrect
format or contained illegal information.

TBADDATA
Illegal amount of data.

o A single send was attempted specifying a
TSDU greater than that specified in the
info argument, or a send of a zero byte
TSDU is not supported by the provider.

o iovcount is greater than T_IOV_MAX.

TBADF
The specified file descriptor does not refer to a
transport endpoint.

TBADOPT
The specified options were in an incorrect format or
contained illegal information.

TFLOW
O_NONBLOCK i was set, but the flow control mechanism
prevented the transport provider from accepting any
data at this time.

TLOOK
An asynchronous event has occurred on this transport
endpoint.

TNOTSUPPORT
This function is not supported by the underlying
transport 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