42 lines
1.8 KiB
Groff
42 lines
1.8 KiB
Groff
.\"
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.TH curl_multi_fdset 3 "2 Jan 2006" "libcurl 7.16.0" "libcurl Manual"
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.SH NAME
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curl_multi_fdset - extracts file descriptor information from a multi handle
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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CURLMcode curl_multi_fdset(CURLM *multi_handle,
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fd_set *read_fd_set,
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fd_set *write_fd_set,
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fd_set *exc_fd_set,
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int *max_fd);
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.ad
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.SH DESCRIPTION
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This function extracts file descriptor information from a given multi_handle.
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libcurl returns its fd_set sets. The application can use these to select() on,
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but be sure to FD_ZERO them before calling this function as
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\fIcurl_multi_fdset(3)\fP only adds its own descriptors, it doesn't zero or
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otherwise remove any others. The \fIcurl_multi_perform(3)\fP function should be
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called as soon as one of them is ready to be read from or written to.
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To be sure to have up-to-date results, you should call
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\fIcurl_multi_perform\fP until it does not return CURLM_CALL_MULTI_PERFORM
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prior to calling \fIcurl_multi_fdset\fP. This will make sure that libcurl has
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updated the handles' socket states.
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If no file descriptors are set by libcurl, \fImax_fd\fP will contain -1 when
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this function returns. Otherwise it will contain the higher descriptor number
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libcurl set.
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When doing select(), you should use \fBcurl_multi_timeout\fP to figure out how
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long to wait for action. Call \fIcurl_multi_perform\fP even if no activity has
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been seen on the fd_sets after the timeout expires as otherwise internal
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retries and timeouts may not work as you'd think and want.
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.SH RETURN VALUE
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CURLMcode type, general libcurl multi interface error code. See
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\fIlibcurl-errors(3)\fP
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.SH "SEE ALSO"
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.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
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.BR curl_multi_timeout "(3), " curl_multi_perform "(3) "
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