NAME

       curl_multi_socket - reads/writes available data

SYNOPSIS

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

       CURLMcode curl_multi_socket_all(CURLM *multi_handle,
                                       int *running_handles);

DESCRIPTION

       These functions are deprecated. Do not use. See curl_multi_socket_action(3) instead.

       At  return, the integer running_handles points to will contain 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_action(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_action(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 will then get 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.

       Usage  of  curl_multi_socket(3)  is  deprecated,  whereas  the  function  is equivalent to
       curl_multi_socket_action(3) with ev_bitmask set to 0.

       Force libcurl to (re-)check all its internal sockets  and  transfers  instead  of  just  a
       single  one  by calling curl_multi_socket_all(3). Note that there should not be any reason
       to use this function.

CALLBACK

       The socket callback function uses a prototype like this
         int curl_socket_callback(CURL *easy,      /* easy handle */
                                  curl_socket_t s, /* socket */
                                  int action,      /* see values below */
                                  void *userp,    /* private callback pointer */
                                  void *socketp); /* private socket pointer */
       The callback MUST return 0.

       The easy argument is a pointer to the easy handle that deals with this particular  socket.
       Note that a single handle may work with several sockets simultaneously.

       The s argument is the actual socket value as you use it within your system.

       The action argument to the callback has one of five values:

              CURL_POLL_NONE (0)
                     register, not interested in readiness (yet)

              CURL_POLL_IN (1)
                     register, interested in read readiness

              CURL_POLL_OUT (2)
                     register, interested in write readiness

              CURL_POLL_INOUT (3)
                     register, interested in both read and write readiness

              CURL_POLL_REMOVE (4)
                     unregister

       The   socketp   argument   is   a   private   pointer   you   have   previously  set  with
       curl_multi_assign(3) to be associated with the s socket.  If  no  pointer  has  been  set,
       socketp  will  be  NULL. This argument is of course a service to applications that want to
       keep certain data or structs that are strictly associated to the given socket.

       The userp argument is a private pointer you have previously set with  curl_multi_setopt(3)
       and the CURLMOPT_SOCKETDATA(3) option.

TYPICAL USAGE

       1. Create a multi handle

       2. Set the socket callback with CURLMOPT_SOCKETFUNCTION(3)

       3.  Set  the  timeout callback with CURLMOPT_TIMERFUNCTION(3), to get to know what timeout
       value to use when waiting for socket activities.

       4. Add easy handles with curl_multi_add_handle()

       5. Provide some means to manage the sockets libcurl is using, so you can  check  them  for
       activity. This can be done through your application code, or by way of an external library
       such as libevent or glib.

       6. Wait for activity on any of libcurl's sockets, use the timeout value your callback  has
       been told

       7,  When  activity is detected, call curl_multi_socket_action() for the socket(s) that got
       action.   If   no   activity   is    detected    and    the    timeout    expires,    call
       curl_multi_socket_action(3) with CURL_SOCKET_TIMEOUT

       8. Go back to step 6.

EXAMPLE

       /* 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;
       rc = curl_multi_socket(multi_handle, fd, &running);

AVAILABILITY

       This function was added in libcurl 7.15.4, and is deemed stable since 7.16.0.

       curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3) instead!

RETURN VALUE

       CURLMcode type, general libcurl multi interface error code.

       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_init(3),  curl_multi_fdset(3),  curl_multi_info_read(3),
       the hiperfifo.c example