t_sndvudata(3)t_sndvudata(3)NAMEt_sndvudata - Send a data unit from one or more non-contiguous buffers
SYNOPSIS
#include <xti.h>
int t_sndvudata(
int fd,
struct t_unitdata *unitdata,
struct t_iovec *iov,
unsigned int iovcount );
LIBRARY
XTI Library (libxti.a)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
t_sndvudata(): XNS5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
The following table summarizes the relevance of input and output param‐
eters before and after t_sndvudata() is called:
───────────────────────────────────────────────────
Parameters Before Call After Call
───────────────────────────────────────────────────
fd y n
unitdata->addr.maxlen n e
unitdata->addr.len y e
unitdata->addr.buf y(y)e(e)
unitdata->opt.maxlen n e
unitdata->opt.len y e
unitdata->opt.buf o(o)e(e)
unitdata->udata.maxlen n e
unitdata->udata.len n e
unitdata->udata.buf n e
iov[0].iov_base y(y)e(e)
iov[0].iov_len y e
...
iov[iov‐ y(y)e(e)
count-1].iov_base
iov[iovcount-1].iov_len y e
iovcount y n
───────────────────────────────────────────────────
Notes to Table: This is a meaningful parameter. The content of the
object pointed to by y is meaningful. This is a meaningful but
optional parameter. The content of the object pointed to by o is mean‐
ingful. The parameter value after the call is the same as before the
call. The content of the object pointed to by e is the same as before
the call. This is not a meaningful parameter. Identifies the local
transport endpoint through which data is sent. Points to a type
t_unitdata structure used to specify a data unit being sent through the
transport endpoint specified by the fd parameter. The t_unitdata
structure has the following members: References a buffer for protocol
address information of the remote transport user. The type netbuf
structure referenced by this member is defined in the xti.h include
file and has the following members: Specifies a maximum byte length of
the data buffer. Specifies the actual byte length of the data written
to the buffer. Points to the buffer location. Identifies options that
the user wants associated with this request. 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. Specifies the user data unit that is being sent
to the remote transport user. (Not used) Points to the data to be sent.
Contains the number of non-contiguous udata buffers, which is limited
to T_IOV_MAX (16).
DESCRIPTION
The t_sndvudata() function is an XTI connectionless service
The data to be sent is identified by iov[0] through iov[iovcount-1].
Note
The limit on the total number of bytes available in all buffers passed
(that is, iov(0).iov_len + ... + iov(iovcount-1).iov_len) may be con‐
strained 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 waits if
flow control restrictions prevent the data from being accepted by the
local transport provider at the time of the call. However, if O_NON‐
BLOCK is set (via t_open() or fcntl()), t_sndvudata() executes in asyn‐
chronous mode and fails under such conditions. The process can arrange
to be notified of the clearance of a flow control restriction via
either t_look() or the EM interface.
If the amount of data specified in iov[0] through iov[iovcount-1]
exceeds the TSDU size as returned in the tsdu field of the info argu‐
ment of t_open() or t_getinfo(), 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(3)), the data
unit may be discarded.
If the transport provider cannot immediately detect the conditions that
cause the [TBADDADDR] and [TBADOPT] errors, these errors will alterna‐
tively be returned by t_rcvuderr(). An application must therefore be
prepared to receive these errors in both of these ways.
ERRORS
If the t_sndvudata() function fails, t_errno may be set to one of the
following values: The specified protocol address was in an incorrect
format or contained illegal information. An attempt to send once,
specifying a TSDU (ETSDU) greater than that specified by the current
value in the info argument, or an attempt to send zero-byte TSDU
(ETSDU) is not supported by the provider.
The iovcount parameter is greater than T_IOV_MAX. File descrip‐
tor (fd) is not a valid transport endpoint. The specified
options were in an incorrect format or contained illegal infor‐
mation. Asynchronous mode is indicated because O_NONBLOCK was
set, but the transport provider cannot accept the data because
of flow-control restrictions. An asynchronous event occurred on
this transport endpoint and requires immediate attention. This
function is not supported by the underlying transport provider.
The communications endpoint referenced by fd is not in a valid
state in which a call to this function. A communication problem
has been detected between XTI and the transport provider for
which there is no other suitable XTI error (t_errno). A system
error occurred during execution of this function.
VALID STATES
The t_sndvudata() function can be called only in the T_IDLE transport
provider state.
RETURN VALUE
Upon successful completion, t_sndvudata() returns a value of 0 (zero).
Otherwise, it returns a value of -1 and sets t_errno to indicate the
error.
SEE ALSO
Functions: fcntl(2), t_alloc(3), t_open(3), t_rcvudata(3), t_rcvud‐
err(3), t_rcvvudata(3), t_sndudata(3).
Standards: standards(5)
Network Programmer's Guide
t_sndvudata(3)
