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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>t_sndudata</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4>NAME</h4><blockquote>t_sndudata - send a data unit</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="xti.h.html">xti.h</a>>int t_sndudata( int fd, const struct t_unitdata *unitdata)</code></pre></blockquote><h4>DESCRIPTION</h4><blockquote><pre><P><table bordercolor=#000000 border=1 align=center><tr valign=top><th align=center><b>Parameters</b><th align=center><b>Before call</b><th align=center><b>After call</b><tr valign=top><td align=left>fd<td align=center>x<td align=center>/<tr valign=top><td align=left>unitdata-><td align=center>addr.maxlen<td align=center>=<tr valign=top><td align=left>unitdata-><td align=center>addr.len<td align=center>x<tr valign=top><td align=left>unitdata-><td align=center>addr.buf<td align=center>x(x)<tr valign=top><td align=left>unitdata-><td align=center>opt.maxlen<td align=center>=<tr valign=top><td align=left>unitdata-><td align=center>opt.len<td align=center>x<tr valign=top><td align=left>unitdata-><td align=center>opt.buf<td align=center>?(?)<tr valign=top><td align=left>unitdata-><td align=center>udata.maxlen<td align=center>=<tr valign=top><td align=left>unitdata-><td align=center>udata.len<td align=center>x<tr valign=top><td align=left>unitdata-><td align=center>udata.buf<td align=center>x(x)</table></pre><p>This function is used in connectionless-modeto send a data unit to another transportuser.The argument<I>fd</I>identifies the local transport endpoint through which data will besent, and<I>unitdata</I>points to a<B>t_unitdata</B>structure containing the following members:<pre><code>struct netbuf addr;struct netbuf opt;struct netbuf udata;</code></pre><p>In<I>unitdata</I>,<I>addr</I>specifies the protocol address of the destination user,<I>opt</I>identifies options that the user wantsassociated with this request, and<I>udata</I>specifies the user data to be sent.The user may choose not to specify what protocoloptions are associated with the transfer by setting the<I>len</I>field of<I>opt</I>to zero.In this case, the provider uses the optionvalues currently set for the communications endpoint.<p>If the<I>len</I>field of<I>udata</I>is zero, and sending of zero octets is not supported by the underlyingtransport service, the<i>t_sndudata()</i>will return -1 with<I>t_errno</I>set to [TBADDATA].<p>By default,<i>t_sndudata()</i>operates in synchronous mode andmay wait if flow control restrictions prevent the data frombeing accepted by the local transport provider at the timethe call is made. However, if O_NONBLOCK is set (via<i><a href="t_open.html">t_open()</a></i>or<i><a href="fcntl.html">fcntl()</a></i>),<i>t_sndudata()</i>will execute in asynchronous mode and will failunder such conditions.The process can arrange to be notified of the clearance of aflow control restriction via either<i><a href="t_look.html">t_look()</a></i>or the EM interface.<p>If the amount of data specified in<I>udata</I>exceeds the TSDU size as returned in the<I>tsdu</I>field of the<I>info</I>argument of<i><a href="t_open.html">t_open()</a></i>or<i><a href="t_getinfo.html">t_getinfo()</a></i>,a [TBADDATA] error will be generated.If<i>t_sndudata()</i>is called before the destination userhas activated its transport endpoint (see<i><a href="t_bind.html">t_bind()</a></i>),the data unit may be discarded.<p>If it is not possible for the transport provider to immediately detectthe conditions that cause the errors[TBADDADDR] and [TBADOPT],these errors will alternatively be returned by<I>t_rcvuderr.</I>Therefore, an application must be prepared to receive these errorsin both of these ways.<p>If the call is interrupted,<i>t_sndudata()</i>will return [EINTR] and the datagram will not be sent.</blockquote><h4>VALID STATES</h4><blockquote>T_IDLE</blockquote><h4>ERRORS</h4><blockquote>On failure,<I>t_errno</I>is set to one of the following:<dl compact><dt>[TBADADDR]<dd>The specified protocol address was in an incorrect format or containedillegal information.<dt>[TBADDATA]<dd>Illegal amount of data. A single send was attempted specifying a TSDU greaterthan that specified in the<I>info</I>argument, or a send of a zero byte TSDU is not supported by the provider.<dt>[TBADF]<dd>The specified file descriptor does not refer to a transport endpoint.<dt>[TBADOPT]<dd>The specified options were in an incorrect format or contained illegalinformation.<dt>[TFLOW]<dd>O_NONBLOCKwas set, butthe flow control mechanism prevented the transport provider fromaccepting any data at this time.<dt>[TLOOK]<dd>An asynchronous event has occurred on this transport endpoint.<dt>[TNOTSUPPORT]<dd>This function is not supported by the underlying transportprovider.<dt>[TOUTSTATE]<dd>The communications endpoint referenced by <I>fd</I>is not in one of the states in which a call to this function is valid.<dt>[TPROTO]<dd>This error indicates that a communication problem has been detected betweenXTI and the transport provider for which there is no other suitable XTIerror<I>(t_errno)</I>.<dt>[TSYSERR]<dd>A system error has occurred during execution of this function.</dl></blockquote><h4>RETURN VALUE</h4><blockquote>Upon successful completion, a value of 0 is returned. Otherwise,a value of -1 is returned and<I>t_errno</I>is set to indicate an error.</blockquote><h4>SEE ALSO</h4><blockquote><i><a href="fcntl.html">fcntl()</a></i>,<i><a href="t_alloc.html">t_alloc()</a></i>,<i><a href="t_open.html">t_open()</a></i>,<i><a href="t_rcvudata.html">t_rcvudata()</a></i>,<i><a href="t_rcvuderr.html">t_rcvuderr()</a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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