mirror of
https://github.com/moparisthebest/curl
synced 2024-11-17 15:05:02 -05:00
2d6796aac5
If a socket is larger than FD_SETSIZE, avoid using FD_SET() on the platforms where this is possible. Bug: http://curl.haxx.se/bug/view.cgi?id=3413274 Reported by: Tim Starling
70 lines
3.3 KiB
Groff
70 lines
3.3 KiB
Groff
.\" **************************************************************************
|
|
.\" * _ _ ____ _
|
|
.\" * Project ___| | | | _ \| |
|
|
.\" * / __| | | | |_) | |
|
|
.\" * | (__| |_| | _ <| |___
|
|
.\" * \___|\___/|_| \_\_____|
|
|
.\" *
|
|
.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
|
|
.\" *
|
|
.\" * This software is licensed as described in the file COPYING, which
|
|
.\" * you should have received as part of this distribution. The terms
|
|
.\" * are also available at http://curl.haxx.se/docs/copyright.html.
|
|
.\" *
|
|
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
|
|
.\" * copies of the Software, and permit persons to whom the Software is
|
|
.\" * furnished to do so, under the terms of the COPYING file.
|
|
.\" *
|
|
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
|
|
.\" * KIND, either express or implied.
|
|
.\" *
|
|
.\" **************************************************************************
|
|
.TH curl_multi_fdset 3 "2 Jan 2006" "libcurl 7.16.0" "libcurl Manual"
|
|
.SH NAME
|
|
curl_multi_fdset - extracts file descriptor information from a multi handle
|
|
.SH SYNOPSIS
|
|
.nf
|
|
#include <curl/curl.h>
|
|
|
|
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);
|
|
.ad
|
|
.SH DESCRIPTION
|
|
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
|
|
\fIcurl_multi_fdset(3)\fP only adds its own descriptors, it doesn't zero or
|
|
otherwise remove any others. The \fIcurl_multi_perform(3)\fP function should be
|
|
called as soon as one of them is ready to be read from or written to.
|
|
|
|
To be sure to have up-to-date results, you should call
|
|
\fIcurl_multi_perform\fP until it does not return CURLM_CALL_MULTI_PERFORM
|
|
prior to calling \fIcurl_multi_fdset\fP. This will make sure that libcurl has
|
|
updated the handles' socket states.
|
|
|
|
If no file descriptors are set by libcurl, \fImax_fd\fP will contain -1 when
|
|
this function returns. Otherwise it will contain the higher descriptor number
|
|
libcurl set.
|
|
|
|
When doing select(), you should use \fBcurl_multi_timeout\fP to figure out how
|
|
long to wait for action. Call \fIcurl_multi_perform\fP even if no activity has
|
|
been seen on the fd_sets after the timeout expires as otherwise internal
|
|
retries and timeouts may not work as you'd think and want.
|
|
|
|
If one of the sockets used by libcurl happens to be larger than what can be
|
|
set in an fd_set, which on POSIX systems means that the file descriptor is
|
|
larger than FD_SETSIZE, then libcurl will try to not set it. Setting a too
|
|
large file descriptor in an fd_set implies an out of bounds write which can
|
|
cause crashes, or worse. The effect of NOT storing it will possibly save you
|
|
from the crash, but will make your program NOT wait for sockets it should wait
|
|
for...
|
|
.SH RETURN VALUE
|
|
CURLMcode type, general libcurl multi interface error code. See
|
|
\fIlibcurl-errors(3)\fP
|
|
.SH "SEE ALSO"
|
|
.BR curl_multi_cleanup "(3), " curl_multi_init "(3), "
|
|
.BR curl_multi_timeout "(3), " curl_multi_perform "(3) "
|