1curl_multi_fdset(3) libcurl Manual curl_multi_fdset(3)
2
3
4
6 curl_multi_fdset - extracts file descriptor information from a multi
7 handle
8
10 #include <curl/curl.h>
11
12 CURLMcode curl_multi_fdset(CURLM *multi_handle,
13 fd_set *read_fd_set,
14 fd_set *write_fd_set,
15 fd_set *exc_fd_set,
16 int *max_fd);
17
19 This function extracts file descriptor information from a given
20 multi_handle. libcurl returns its fd_set sets. The application can use
21 these to select() on, but be sure to FD_ZERO them before calling this
22 function as curl_multi_fdset(3) only adds its own descriptors, it
23 doesn't zero or otherwise remove any others. The curl_multi_perform(3)
24 function should be called as soon as one of them is ready to be read
25 from or written to.
26
27 If no file descriptors are set by libcurl, max_fd will contain -1 when
28 this function returns. Otherwise it will contain the higher descriptor
29 number libcurl set.
30
31 You should also be aware that when doing select(), you should consider
32 using a rather small (single-digit number of seconds) timeout and call
33 curl_multi_perform regularly - even if no activity has been seen on the
34 fd_sets - as otherwise libcurl-internal retries and timeouts may not
35 work as you'd think and want.
36
37 Starting with libcurl 7.16.0, you should use curl_multi_timeout to fig‐
38 ure out how long to wait for action.
39
41 CURLMcode type, general libcurl multi interface error code. See
42 libcurl-errors(3)
43
45 curl_multi_cleanup(3),curl_multi_init(3), curl_multi_timeout(3)
46
47
48
49libcurl 7.16.0 2 Jan 2006 curl_multi_fdset(3)