T_SNDVUDATA(3NSL)T_SNDVUDATA(3NSL)NAMEt_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 trans‐
port endpoint through which data will be sent, iovcount contains the
number of non-contiguous udata buffers and is limited to an implemen‐
tation-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 TBAD‐
DATA.
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 set‐
ting 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 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.
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 argu‐
ment 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 TBADDADDR and TBADOPT, these
errors will alternatively be returned by t_rcvuderr(3NSL). An applica‐
tion 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 for‐
mat 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 argu‐
ment, 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 trans‐
port 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 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_alloc(3NSL), t_open(3NSL), t_rcvudata(3NSL), t_rcvvu‐
data(3NSL)t_rcvuderr(3NSL), t_sndudata(3NSL), attributes(5)
Aug 23, 2001 T_SNDVUDATA(3NSL)
