curl_multi_socket(3)       Library Functions Manual       curl_multi_socket(3)

NAME
       curl_multi_socket - read/write available data

SYNOPSIS
       #include <curl/curl.h>
       CURLMcode curl_multi_socket(CURLM *multi_handle, curl_socket_t sockfd,
                                   int *running_handles);

DESCRIPTION
       This function is deprecated. Use curl_multi_socket_action(3) instead
       with ev_bitmask set to 0.

       At return, the integer running_handles points to contains the number of
       still running easy handles within the multi handle. When this number
       reaches zero, all transfers are complete/done. Note that when you call
       curl_multi_socket(3) on a specific socket and the counter decreases by
       one, it DOES NOT necessarily mean that this exact socket/transfer is
       the one that completed. Use curl_multi_info_read(3) to figure out which
       easy handle that completed.

       The curl_multi_socket(3) functions inform the application about updates
       in the socket (file descriptor) status by doing none, one, or multiple
       calls to the socket callback function set with the
       CURLMOPT_SOCKETFUNCTION(3) option to curl_multi_setopt(3). They update
       the status with changes since the previous time the callback was
       called.

       Get the timeout time by setting the CURLMOPT_TIMERFUNCTION(3) option
       with curl_multi_setopt(3). Your application then gets called with
       information on how long to wait for socket actions at most before doing
       the timeout action: call the curl_multi_socket_action(3) function with
       the sockfd argument set to CURL_SOCKET_TIMEOUT. You can also use the
       curl_multi_timeout(3) function to poll the value at any given time, but
       for an event-based system using the callback is far better than relying
       on polling the timeout value.

PROTOCOLS
       This functionality affects all supported protocols

EXAMPLE
       int main(void)
       {
         /* the event-library gets told when there activity on the socket 'fd',
            which we translate to a call to curl_multi_socket_action() */
         int running;
         int rc;
         int fd = 2;
         CURLM *multi = curl_multi_init();

         rc = curl_multi_socket(multi, fd, &running);
       }

DEPRECATED
       curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3)
       instead.

AVAILABILITY
       Added in curl 7.15.4

RETURN VALUE
       This function returns a CURLMcode indicating success or error.

       CURLM_OK (0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3).

       The return code is for the whole multi stack. Problems still might have
       occurred on individual transfers even when one of these functions
       return OK.

SEE ALSO
       curl_multi_cleanup(3), curl_multi_fdset(3), curl_multi_info_read(3),
       curl_multi_init(3), thehiperfifo.cexample

libcurl                           2025-06-04              curl_multi_socket(3)