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