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curl_multi_socket(3)		libcurl	Manual		  curl_multi_socket(3)

       curl_multi_socket - reads/writes	available data

       #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);

       These  functions	 are deprecated. Do not	use! See curl_multi_socket_ac-
       tion(3) instead!

       At return, the integer running_handles points to	will contain the  num-
       ber  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	 CURL-
       MOPT_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  in-
       stead  of  just	a single one by	calling	curl_multi_socket_all(3). Note
       that there should not be	any reason to use this function!

       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

       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


       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 ser-
       vice 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.

       CURLMcode type, general libcurl multi interface error code.

       Legacy: If you receive CURLM_CALL_MULTI_PERFORM,	this  basically	 means
       that  you  should  call curl_multi_socket(3) again, before you wait for
       more actions on libcurl's sockets. You don't have to do it immediately,
       but  the	return code means that libcurl may have	more data available to
       return or that there may	be more	data to	send off before	it is  "satis-

       should not be returned and no application needs to care about them.

       NOTE that 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.

       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.

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

       curl_multi_socket(3) is deprecated, use curl_multi_socket_action(3) in-

       curl_multi_cleanup(3),	  curl_multi_init(3),	  curl_multi_fdset(3),
       curl_multi_info_read(3),	the hiperfifo.c	example

libcurl	7.72.0			 June 30, 2018		  curl_multi_socket(3)


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