| <html lang="en"> |
| <head> |
| <title>Receiving Data - The GNU C Library</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The GNU C Library"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Transferring-Data.html#Transferring-Data" title="Transferring Data"> |
| <link rel="prev" href="Sending-Data.html#Sending-Data" title="Sending Data"> |
| <link rel="next" href="Socket-Data-Options.html#Socket-Data-Options" title="Socket Data Options"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU C library. |
| |
| This is Edition 0.12, last updated 2007-10-27, |
| of `The GNU C Library Reference Manual', for version |
| 2.8 (Sourcery G++ Lite 2011.03-41). |
| |
| Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, |
| 2003, 2007, 2008, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Free Software Needs Free Documentation'' |
| and ``GNU Lesser General Public License'', the Front-Cover texts being |
| ``A GNU Manual'', and with the Back-Cover Texts as in (a) below. A |
| copy of the license is included in the section entitled "GNU Free |
| Documentation License". |
| |
| (a) The FSF's Back-Cover Text is: ``You have the freedom to |
| copy and modify this GNU manual. Buying copies from the FSF |
| supports it in developing GNU and promoting software freedom.''--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Receiving-Data"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Socket-Data-Options.html#Socket-Data-Options">Socket Data Options</a>, |
| Previous: <a rel="previous" accesskey="p" href="Sending-Data.html#Sending-Data">Sending Data</a>, |
| Up: <a rel="up" accesskey="u" href="Transferring-Data.html#Transferring-Data">Transferring Data</a> |
| <hr> |
| </div> |
| |
| <h5 class="subsubsection">16.9.5.2 Receiving Data</h5> |
| |
| <p><a name="index-sys_002fsocket_002eh-1808"></a>The <code>recv</code> function is declared in the header file |
| <samp><span class="file">sys/socket.h</span></samp>. If your <var>flags</var> argument is zero, you can |
| just as well use <code>read</code> instead of <code>recv</code>; see <a href="I_002fO-Primitives.html#I_002fO-Primitives">I/O Primitives</a>. |
| |
| <!-- sys/socket.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>recv</b> (<var>int socket, void *buffer, size_t size, int flags</var>)<var><a name="index-recv-1809"></a></var><br> |
| <blockquote><p>The <code>recv</code> function is like <code>read</code>, but with the additional |
| flags <var>flags</var>. The possible values of <var>flags</var> are described |
| in <a href="Socket-Data-Options.html#Socket-Data-Options">Socket Data Options</a>. |
| |
| <p>If nonblocking mode is set for <var>socket</var>, and no data are available to |
| be read, <code>recv</code> fails immediately rather than waiting. See <a href="File-Status-Flags.html#File-Status-Flags">File Status Flags</a>, for information about nonblocking mode. |
| |
| <p>This function returns the number of bytes received, or <code>-1</code> on failure. |
| The following <code>errno</code> error conditions are defined for this function: |
| |
| <dl> |
| <dt><code>EBADF</code><dd>The <var>socket</var> argument is not a valid file descriptor. |
| |
| <br><dt><code>ENOTSOCK</code><dd>The descriptor <var>socket</var> is not a socket. |
| |
| <br><dt><code>EWOULDBLOCK</code><dd>Nonblocking mode has been set on the socket, and the read operation |
| would block. (Normally, <code>recv</code> blocks until there is input |
| available to be read.) |
| |
| <br><dt><code>EINTR</code><dd>The operation was interrupted by a signal before any data was read. |
| See <a href="Interrupted-Primitives.html#Interrupted-Primitives">Interrupted Primitives</a>. |
| |
| <br><dt><code>ENOTCONN</code><dd>You never connected this socket. |
| </dl> |
| |
| <p>This function is defined as a cancellation point in multi-threaded |
| programs, so one has to be prepared for this and make sure that |
| allocated resources (like memory, files descriptors, semaphores or |
| whatever) are freed even if the thread is canceled. |
| <!-- @xref{pthread_cleanup_push}, for a method how to do this. --> |
| </p></blockquote></div> |
| |
| </body></html> |
| |
