<html><head> <title>curl_multi_fdset man page</title> <meta name="generator" content="roffit 0.7"> <STYLE type="text/css"> P.level0 { padding-left: 2em; } P.level1 { padding-left: 4em; } P.level2 { padding-left: 6em; } span.emphasis { font-style: italic; } span.bold { font-weight: bold; } span.manpage { font-weight: bold; } h2.nroffsh { background-color: #e0e0e0; } span.nroffip { font-weight: bold; font-size: 120%; font-family: monospace; } p.roffit { text-align: center; font-size: 80%; } </STYLE> </head><body> <p class="level0"><a name="NAME"></a><h2 class="nroffsh">NAME</h2> <p class="level0">curl_multi_fdset - extracts file descriptor information from a multi handle <a name="SYNOPSIS"></a><h2 class="nroffsh">SYNOPSIS</h2> <p class="level0"><pre> <p class="level0">#include <curl/curl.h> <p class="level0">CURLMcode curl_multi_fdset(CURLM *multi_handle, fd_set *read_fd_set, fd_set *write_fd_set, fd_set *exc_fd_set, int *max_fd); <p class="level0"></pre> <a name="DESCRIPTION"></a><h2 class="nroffsh">DESCRIPTION</h2> <p class="level0">This function extracts file descriptor information from a given multi_handle. libcurl returns its fd_set sets. The application can use these to select() on, but be sure to FD_ZERO them before calling this function as <a class="emphasis" href="./curl_multi_fdset.html">curl_multi_fdset(3)</a> only adds its own descriptors it doesn't zero or otherwise remove any other. The <a class="emphasis" href="./curl_multi_perform.html">curl_multi_perform(3)</a> function should be called as soon as one of them are ready to be read from or written to. <p class="level0">If no file descriptors are set by libcurl, <span Class="emphasis">max_fd</span> will contain -1 when this function returns. Otherwise it will contain the higher descriptor number libcurl set. <p class="level0">You should also be aware that when doing select(), you should consider using a rather small (single-digit number of seconds) timeout and call <span Class="emphasis">curl_multi_perform</span> regularly - even if no activity has been seen on the fd_sets - as otherwise libcurl-internal retries and timeouts may not work as you'd think and want. <p class="level0">Starting with libcurl 7.16.0, you should use <span Class="bold">curl_multi_timeout</span> to figure out how long to wait for action. <a name="RETURN"></a><h2 class="nroffsh">RETURN VALUE</h2> <p class="level0">CURLMcode type, general libcurl multi interface error code. See <span Class="emphasis">libcurl-errors(3)</span> <a name="SEE"></a><h2 class="nroffsh">SEE ALSO</h2> <p class="level0"><a class="manpage" href="./curl_multi_cleanup.html">curl_multi_cleanup (3)</a> <a class="manpage" href="./curl_multi_init.html"> curl_multi_init (3)</a> <span Class="manpage"> </span> <a class="manpage" href="./curl_multi_timeout.html">curl_multi_timeout (3) </a> <p class="roffit"> This HTML page was made with <a href="http://daniel.haxx.se/projects/roffit/">roffit</a>. </body></html>