1<!-- Creator : groff version 1.22.2 --> 2<!-- CreationDate: Wed Feb 1 23:55:12 2017 --> 3<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 4"http://www.w3.org/TR/html4/loose.dtd"> 5<html> 6<head> 7<meta name="generator" content="groff -Thtml, see www.gnu.org"> 8<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> 9<meta name="Content-Style" content="text/css"> 10<style type="text/css"> 11 p { margin-top: 0; margin-bottom: 0; vertical-align: top } 12 pre { margin-top: 0; margin-bottom: 0; vertical-align: top } 13 table { margin-top: 0; margin-bottom: 0; vertical-align: top } 14 h1 { text-align: center } 15</style> 16<title>mtcp_recv</title> 17 18</head> 19<body> 20 21<h1 align="center">mtcp_recv</h1> 22 23<a href="#NAME">NAME</a><br> 24<a href="#SYNOPSIS">SYNOPSIS</a><br> 25<a href="#DESCRIPTION">DESCRIPTION</a><br> 26<a href="#RETURN VALUE">RETURN VALUE</a><br> 27<a href="#ERRORS">ERRORS</a><br> 28<a href="#AUTHORS">AUTHORS</a><br> 29<a href="#SEE ALSO">SEE ALSO</a><br> 30<a href="#COLOPHON">COLOPHON</a><br> 31 32<hr> 33 34 35<h2>NAME 36<a name="NAME"></a> 37</h2> 38 39 40<p style="margin-left:11%; margin-top: 1em">mtcp_recv 41− receive a message from a socket</p> 42 43<h2>SYNOPSIS 44<a name="SYNOPSIS"></a> 45</h2> 46 47 48<p style="margin-left:11%; margin-top: 1em"><b>#include 49<mtcp_api.h></b></p> 50 51<p style="margin-left:11%; margin-top: 1em"><b>ssize_t 52mtcp_recv(mctx_t</b> <i>mctx</i><b>, int</b> 53<i>sockid</i><b>, char *</b><i>buf</i><b>, size_t</b> 54<i>len</i><b>, int</b> <i>flags</i><b>);</b></p> 55 56<h2>DESCRIPTION 57<a name="DESCRIPTION"></a> 58</h2> 59 60 61 62<p style="margin-left:11%; margin-top: 1em"><b>mtcp_recv</b>() 63call is normally used only on a <i>connected</i> socket (see 64<b>mtcp_connect()</b>) and is identical to 65<b>mtcp_read()</b> with <i>flags</i> value set to 0. The 66function can be used to read up to <i>len</i> number of 67bytes from mTCP socket via socket descriptor <i>sockid</i> 68into the buffer starting at <i>buf.</i> It is the 69responsibility of the user to allocate memory for <i>buf</i> 70array.</p> 71 72<p style="margin-left:11%; margin-top: 1em">For cases when 73the total number of buffered unread bytes in the socket are 74less than <i>len,</i> <b>mtcp_recv()</b> copies entire data 75to <i>buf</i> and returns the actual number of bytes that 76can be used by the application.</p> 77 78<p style="margin-left:11%; margin-top: 1em">An 79<b>mtcp_recv</b>() call takes an additional argument named 80<i>mctx</i> that represents the per-core mTCP context in an 81application (see <b>mtcp_create_context()</b> for 82details).</p> 83 84<p style="margin-left:11%; margin-top: 1em">The 85<i>flags</i> argument to a <b>mtcp_recv()</b> call currently 86accepts only one non-zero value:</p> 87 88<table width="100%" border="0" rules="none" frame="void" 89 cellspacing="0" cellpadding="0"> 90<tr valign="top" align="left"> 91<td width="11%"></td> 92<td width="12%"> 93 94 95<p><b>MSG_PEEK</b></p></td> 96<td width="3%"></td> 97<td width="74%"> 98 99 100<p>This flag causes the receive operation to return data 101from the beginning of the receive queue without removing 102that data from the queue. Thus, a subsequent receive call 103will return the same data.</p></td></tr> 104</table> 105 106<h2>RETURN VALUE 107<a name="RETURN VALUE"></a> 108</h2> 109 110 111<p style="margin-left:11%; margin-top: 1em">On success, the 112number of bytes read is returned. It is not an error if this 113number is smaller than the number of bytes requested; this 114may happen when the socket has fewer number of bytes 115buffered at that moment. On all errors, -1 is returned and 116<i>errno</i> is set appropriately.</p> 117 118<h2>ERRORS 119<a name="ERRORS"></a> 120</h2> 121 122 123<table width="100%" border="0" rules="none" frame="void" 124 cellspacing="0" cellpadding="0"> 125<tr valign="top" align="left"> 126<td width="11%"></td> 127<td width="12%"> 128 129 130<p style="margin-top: 1em"><b>EBADF</b></p></td> 131<td width="3%"></td> 132<td width="74%"> 133 134 135<p style="margin-top: 1em">The socket descriptor 136<i>sockid</i> is invalid.</p></td></tr> 137<tr valign="top" align="left"> 138<td width="11%"></td> 139<td width="12%"> 140 141 142<p><b>EINVAL</b></p></td> 143<td width="3%"></td> 144<td width="74%"> 145 146 147<p>Invalid argument passed.</p></td></tr> 148<tr valign="top" align="left"> 149<td width="11%"></td> 150<td width="12%"> 151 152 153<p><b>ENOTSOCK</b></p></td> 154<td width="3%"></td> 155<td width="74%"> 156 157 158<p>The socket referred to by <i>sockid</i> has invalid 159<i>type</i></p> </td></tr> 160<tr valign="top" align="left"> 161<td width="11%"></td> 162<td width="12%"> 163 164 165<p><b>ENOTCONN</b></p></td> 166<td width="3%"></td> 167<td width="74%"> 168 169 170<p>Th socket referred to by <i>sockid</i> is in a TCP state 171that disallows read operations.</p></td></tr> 172<tr valign="top" align="left"> 173<td width="11%"></td> 174<td width="12%"> 175 176 177<p><b>EAGAIN</b></p></td> 178<td width="3%"></td> 179<td width="74%"> 180 181 182<p>The socket referred to by <i>sockid</i> does not have 183any available bytes in its buffer for reading.</p></td></tr> 184</table> 185 186<h2>AUTHORS 187<a name="AUTHORS"></a> 188</h2> 189 190 191<p style="margin-left:11%; margin-top: 1em">mOS development 192team <[email protected]></p> 193 194<h2>SEE ALSO 195<a name="SEE ALSO"></a> 196</h2> 197 198 199 200<p style="margin-left:11%; margin-top: 1em"><b>mtcp_bind</b>(), 201<b>mtcp_read</b>(), <b>mtcp_accept</b>(), 202<b>mtcp_connect</b>(), <b>mtcp_socket</b>(), 203<b>mtcp_write</b>()</p> 204 205<h2>COLOPHON 206<a name="COLOPHON"></a> 207</h2> 208 209 210<p style="margin-left:11%; margin-top: 1em">This page is 211part of mOS release 0.3 <i>docs</i> section. A description 212of the project, and information about reporting bugs, can be 213found at http://mos.kaist.edu/.</p> 214<hr> 215</body> 216</html> 217