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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_sndvudata</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_sndvudata - send a data unit from one or more noncontiguous buffers</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="xti.h.html">xti.h</a>>int t_sndvudata( int fd, struct t_unitdata *unitdata, struct t_iovec *iov, unsigned int iovcount) </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>/<tr valign=top><td align=left>unitdata-><td align=center>udata.buf<td align=center>/<tr valign=top><td align=left>iov[0].iov_base<td align=center>x(x)<td align=center>=(=)<tr valign=top><td align=left>iov[0].iov_len<td align=center>x<td align=center>=<tr valign=top><td align=left> . . . .<tr valign=top><td align=left>iov[iovcount-1].iov_base<td align=center>x(x)<td align=center>=(=)<tr valign=top><td align=left>iov[iovcount-1].iov_len<td align=center>x<td align=center>=<tr valign=top><td align=left>iovcount<td align=center>x<td align=center>/</table></pre><p>This function is used in connectionless mode to send a dataunit to another transport user. The argument <I>fd</I>identifies the local transport endpoint through which data will besent, <I>iovcount</I>contains the number of non-contiguous <I>udata</I>buffers and is limited to an implementation-defined valuegiven by T_IOV_MAX which is at least 16, 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>If the limit on <I>iovcount</I>is exceeded, the function fails with [TBADDATA].<p>In <B>unitdata</B>,<I>addr</I>specifies the protocol address of thedestination user, and <I>opt</I>identifies options that the userwants associated with this request. The <I>udata</I>field is notused. 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 may use default options.<p>The data to be sent is identified by <I>iov[0]</I>through<I>iov[iovcount-1]</I>.<p><dl><dt><b>Note:</b><dd>The limit on the total number of bytes availablein all buffers passed (that is:<I>iov(0).iov_len + . . + iov(iovcount-1).iov_len ) </I>may be constrained byimplementation limits. If no other constraint applies,it will be limited by [INT_MAX]. In practice, theavailability of memory to an application is likely toimpose a lower limit on the amount of data that can besent or received using scatter/gather functions.</dl><p>By default, <i>t_sndvudata()</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_sndvudata()</i>executes inasynchronous mode and will fail under such conditions. Theprocess 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>iov[0]</I>through<I>iov[iovcount-1]</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>,or iszero and sending of zero octets is not supported by theunderlying transport service, a [TBADDATA] error isgenerated. If <i>t_sndvudata()</i>is called before the destinationuser has 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 toimmediately detect the conditions that cause the errors[TBADDADDR] and [TBADOPT], these errors will alternativelybe returned by <i><a href="t_rcvuderr.html">t_rcvuderr()</a></i>.An application must thereforebe prepared to receive these errors in both of these ways.</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 anincorrect format or contained illegal information.<dt>[TBADDATA]<dd>Illegal amount of data.<ul><li>A single send was attempted specifying aTSDU greater than that specified in the<I>info</I>argument, or a send of a zero byteTSDU is not supported by the provider.<li><I>iovcount</I>is greater than T_IOV_MAX.</ul><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 illegal information.<dt>[TFLOW]<dd>O_NONBLOCK was set, but the flow controlmechanism prevented the transport providerfrom accepting 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 transport provider.<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 communicationproblem has been detected between XTI andthe transport provider for which there is no other suitable XTI error<I>(t_errno)</I>.<dt>[TSYSERR]<dd>A system error has occurred during execution of this function.</dl><br></blockquote><h4>RETURN VALUES</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_rcvvudata.html">t_rcvvudata()</a></i>,<i><a href="t_rcvuderr.html">t_rcvuderr()</a></i>,<i><a href="t_sndudata.html">t_sndudata()</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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