curl_multi_fdset(3)

NAME

       curl_multi_fdset  -  extracts  file descriptor information from a multi
       handle

SYNOPSIS

       #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);

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  curl_multi_fdset(3)  only  adds  its  own  descriptors it
       doesn't zero or otherwise remove any other.  The  curl_multi_perform(3)
       function  should  be called as soon as one of them are ready to be read
       from or written to.

       If no file descriptors are set by libcurl, max_fd will contain -1  when
       this  function returns. Otherwise it will contain the higher descriptor
       number libcurl set.

       You should also be aware that when doing select(), you should  consider
       using  a rather small (single-digit number of seconds) timeout and call
       curl_multi_perform 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.

       Starting with libcurl 7.16.0, you should use curl_multi_timeout to fig-
       ure out how long to wait for action.

RETURN VALUE

       CURLMcode  type,  general  libcurl  multi  interface  error  code.  See
       libcurl-errors(3)

SEE ALSO

       curl_multi_cleanup(3),curl_multi_init(3), curl_multi_timeout(3)

libcurl 7.16.0                    2 Jan 2006               curl_multi_fdset(3)