📄 t_rcvudata.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>t_rcvudata</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_rcvudata - receive a data unit</blockquote><h4>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="xti.h.html">xti.h</a>>int t_rcvudata( int fd, struct t_unitdata *unitdata, 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>x<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>flags<td align=center>/<td align=center>x</table></pre><p>This function is used in connectionless-modeto receive a data unit from another transportuser.The argument<I>fd</I>identifies the local transport endpoint through which data will bereceived,<I>unitdata</I>holds information associated with the received data unit, and<I>flags</I>is set on return to indicate that the complete data unit was notreceived.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>,<I>opt</I>and<I>udata</I>must be set before calling this function to indicate the maximumsize of the buffer for each.If the <I>maxlen</I>field of <I>addr</I>or <I>opt</I>is set to zero, no information is returned in the <I>buf</I>field of this parameter.<p>On return from this call,<I>addr</I>specifies the protocol address of the sending user,<I>opt</I>identifies options that wereassociated with this data unit, and<I>udata</I>specifies the user data that was received.<p>By default,<i>t_rcvudata()</i>operates in synchronous mode and willwait for a data unit to arrive if none is currently available.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_rcvudata()</i>will execute in asynchronous mode and will failif no data units are available.<p>If the buffer defined in the<I>udata</I>field of<I>unitdata</I>is not large enough to hold the current data unit,the buffer will be filled and T_MORE will be set in<I>flags</I>on return to indicate that another<i>t_rcvudata()</i>should be called to retrieve the rest of the data unit. Subsequent calls to<i>t_rcvudata()</i>will return zero for the length of the address and optionsuntil the full data unit has been received.<p>If the call is interrupted,<i>t_rcvudata()</i>will return [EINTR] and no datagrams will have been removed from the endpoint.</blockquote><h4>VALID STATES</h4><blockquote>T_IDLE<br></blockquote><h4>ERRORS</h4><blockquote>On failure,<I>t_errno</I>is set to one of the following:<dl compact><dt>[TBADF]<dd>The specified file descriptor does not refer to a transport endpoint.<dt>[TBUFOVFLW]<dd>The number of bytes allocated for the incoming protocol address oroptions<I>(maxlen)</I>is greater than 0 but notsufficient to store the information.The unit data information to be returned in<I>unitdata</I>will be discarded.<dt>[TLOOK]<dd>An asynchronous event has occurred on this transport endpoint and requiresimmediate attention.<dt>[TNODATA]<dd>O_NONBLOCKwas set, butno data units are currently available from the transport provider.<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_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
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -