oracular (3) curl_multi_assign.3.gz

Provided by: libcurl4-doc_8.9.1-2ubuntu2.2_all bug

NAME
       curl_multi_assign - set data to associate with an internal socket


SYNOPSIS
       #include <curl/curl.h>

       CURLMcode curl_multi_assign(CURLM *multi_handle, curl_socket_t sockfd,
                                   void *sockptr);


DESCRIPTION
       This  function  creates an association in the multi handle between the given socket and a private pointer
       of the application. This is designed for curl_multi_socket_action(3) uses.

       When set, the sockptr pointer is passed to all future socket callbacks for the specific sockfd socket.

       If the given sockfd is not already in use by libcurl, this function returns an error.

       libcurl only keeps one single pointer associated with a socket, so calling this  function  several  times
       for the same socket makes the last set pointer get used.

       The  idea here being that this association (socket to private pointer) is something that just about every
       application that uses this API needs and then libcurl can just as well do it since  it  already  has  the
       necessary functionality.

       It is acceptable to call this function from your multi callback functions.


PROTOCOLS
       This functionality affects all supported protocols


EXAMPLE
       int main(void)
       {
         CURLM *multi = curl_multi_init();
         void *ourstructp; /* pointer to our data */
         curl_socket_t fd; /* file descriptor to associate our data with */

         /* make our struct pointer associated with socket fd */
         CURLMcode mc = curl_multi_assign(multi, fd, ourstructp);
         if(mc)
           printf("error: %s\n", curl_multi_strerror(mc));
       }


TYPICAL USAGE
       In  a  typical  application you allocate a struct or at least use some kind of semi-dynamic data for each
       socket that we must wait for action on when using the curl_multi_socket_action(3) approach.

       When our socket-callback gets called by libcurl and we get to know about yet another socket to wait  for,
       we  can  use curl_multi_assign(3) to point out the particular data so that when we get updates about this
       same socket again, we do not have to find the struct associated with this socket by ourselves.


AVAILABILITY
       Added in curl 7.15.5


RETURN VALUE
       The standard CURLMcode for multi interface error codes.


SEE ALSO
       curl_multi_setopt(3), curl_multi_socket_action(3)