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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_rcvvudata</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_rcvvudata - receive a data unit into one or more noncontiguous buffers</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="xti.h.html">xti.h</a>>int t_rcvvudata( int fd, struct t_unitdata *unitdata, struct t_iovec *iov, unsigned int iovcount, int *flags)</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>x<tr valign=top><td align=left>unitdata-><td align=center>addr.len<td align=center>/<tr valign=top><td align=left>unitdata-><td align=center>addr.buf<td align=center>?(/)<tr valign=top><td align=left>unitdata-><td align=center>opt.maxlen<td align=center>x<tr valign=top><td align=left>unitdata-><td align=center>opt.len<td align=center>/<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<td align=center>=(x)<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(/)<td align=center>=(x)<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>/<tr valign=top><td align=left>flags<td align=center>/<td align=center>/</table></pre><p>This function is used in connectionless mode to receive adata unit from another transport user. The argument <I>fd</I>identifies the local transport endpoint through which datawill be received, <I>unitdata</I>holds information associated withthe received data unit, <I>iovcount</I>contains the number ofnon-contiguous udata buffers which is limited to T_IOV_MAX(an implementation-defined value of at least 16), and <I>flags</I>is set on return to indicate that the complete data unitwas not received. If the limit on <I>iovcount</I>is exceeded, thefunction fails with [TBADDATA]. The argument <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>The <I>maxlen</I>field of <I>addr</I>and <I>opt</I>must be set before calling thisfunction to indicate the maximum size of the buffer for each.The <I>udata</I>field of <B>t_unitdata</B>is not used. The <I>iov_len</I>and<I>iov_base</I>fields of <I>iov[0]</I>through <I>iov[iovcount-1]</I>must be setbefore calling <i>t_rcvvudata()</i>to define the buffer where the userdata will be placed. If the maxlen field of <I>addr</I>or <I>opt</I>is set to zero thenno information is returned in the <I>buf</I>field for this parameter.<p>On return from this call, <I>addr</I>specifies the protocoladdress of the sending user, <I>opt</I>identifies options thatwere associated with this data unit, and <I>iov[0].iov_base</I>through<I>iov[iovcount-1].iov_base</I>contains the user data that was received.The return value of <i>t_rcvvudata()</i>is the number of bytes of user data given to the user.<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_rcvvudata()</i>operates in synchronous mode andwaits for a data unit to arrive if none is currentlyavailable. 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_rcvvudata()</i>executes in asynchronous mode andfails if no data units are available.<p>If the buffers defined in the <I>iov[]</I>array are notlarge enough to hold the current data unit, the buffers willbe filled and T_MORE will be set in flags on return toindicate that another <i>t_rcvvudata()</i>should be called toretrieve the rest of the data unit. Subsequent calls to<i>t_rcvvudata()</i>will return zero for the length of the addressand options, until the full data unit has been received.</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>[TBADDATA]<dd><I>iovcount</I>is greater than T_IOV_MAX.<dt>[TBADF]<dd>The specified file descriptor does not refer to a transport endpoint.<dt>[TBUFOVFLW]<dd>The number of bytes allocated for theincoming protocol address or options(<I>maxlen</I>) is greater than 0 but notsufficient to store the information. Theunit data information to be returned in<I>unitdata</I>will be discarded.<dt>[TLOOK]<dd>An asynchronous event has occurred on thistransport endpoint and requires immediate attention.<dt>[TNODATA]<dd>O_NONBLOCK was set, but no data units arecurrently available from the transport provider.<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 noother suitable XTI error<I>(t_errno)</I>.<dt>[TSYSERR]<dd>A system error has occurred during execution of this function.</dl></blockquote><h4>RETURN VALUES</h4><blockquote>On successful completion, <i>t_rcvvudata()</i>returns the number ofbytes received. Otherwise, it returns -1 on failure and<I>t_errno</I>is set to indicate the 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>,<i><a href="t_sndudata.html">t_sndudata()</a></i>,<i><a href="t_sndvudata.html">t_sndvudata()</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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