NAME

       curl_multi_info_read - read multi stack information

SYNOPSIS

       #include <curl/curl.h>

       CURLMsg *curl_multi_info_read(CURLM *multi_handle, int *msgs_in_queue);

DESCRIPTION

       Ask  the  multi  handle  if  there  are  any messages from the individual transfers. Messages may include
       information such as an error code from the transfer or just the fact that a transfer is  completed.  More
       details on these should be written down as well.

       Repeated calls to this function returns a new struct each time, until a NULL is returned as a signal that
       there  is  no more to get at this point. The integer pointed to with msgs_in_queue contains the number of
       remaining messages after this function was called.

       When you fetch a message using this function, it is removed from  the  internal  queue  so  calling  this
       function again does not return the same message again. It instead returns new messages at each new invoke
       until the queue is emptied.

       WARNING:  The  data  the  returned  pointer  points  to  does  not survive calling curl_multi_cleanup(3),
       curl_multi_remove_handle(3) or curl_easy_cleanup(3).

       The CURLMsg struct is simple and only contains basic information. If more involved information is wanted,
       the particular "easy  handle"  is  present  in  that  struct  and  can  be  used  in  subsequent  regular
       curl_easy_getinfo(3) calls (or similar):

        struct CURLMsg {
          CURLMSG msg;       /* what this message means */
          CURL *easy_handle; /* the handle it concerns */
          union {
            void *whatever;    /* message-specific data */
            CURLcode result;   /* return code for transfer */
          } data;
        };
       When  msg  is  CURLMSG_DONE, the message identifies a transfer that is done, and then result contains the
       return code for the easy handle that just completed.

       At this point, there are no other msg types defined.

EXAMPLE

       int main(void)
       {
         CURLM *multi = curl_multi_init();
         CURL *curl = curl_easy_init();
         if(curl) {
           struct CURLMsg *m;

           /* call curl_multi_perform or curl_multi_socket_action first, then loop
              through and check if there are any transfers that have completed */

           do {
             int msgq = 0;
             m = curl_multi_info_read(multi, &msgq);
             if(m && (m->msg == CURLMSG_DONE)) {
               CURL *e = m->easy_handle;
               /* m->data.result holds the error code for the transfer */
               curl_multi_remove_handle(multi, e);
               curl_easy_cleanup(e);
             }
           } while(m);
         }
       }

AVAILABILITY

       Added in 7.9.6

RETURN VALUE

       A pointer to a filled-in struct, or NULL if it failed or ran out of structs. It also writes the number of
       messages left in the queue (after this read) in the integer the second argument points to.

SEE ALSO

       curl_multi_cleanup(3), curl_multi_init(3), curl_multi_perform(3)

libcurl 8.5.0                                   December 04, 2023                        curl_multi_info_read(3)