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CURLOPT_IOCTLFUNCTION(3)   curl_easy_setopt options   CURLOPT_IOCTLFUNCTION(3)

NAME
       CURLOPT_IOCTLFUNCTION - callback	for I/O	operations

SYNOPSIS
       #include	<curl/curl.h>

       typedef enum {
	 CURLIOE_OK,		/* I/O operation successful */
	 CURLIOE_UNKNOWNCMD,	/* command was unknown to callback */
	 CURLIOE_FAILRESTART,	/* failed to restart the read */
	 CURLIOE_LAST		/* never use */
       } curlioerr;

       typedef enum  {
	 CURLIOCMD_NOP,		/* no operation	*/
	 CURLIOCMD_RESTARTREAD,	/* restart the read stream from	start */
	 CURLIOCMD_LAST		/* never use */
       } curliocmd;

       curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp);

       CURLcode	curl_easy_setopt(CURL *handle, CURLOPT_IOCTLFUNCTION, ioctl_callback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the	proto-
       type shown above.

       This callback function gets called by libcurl  when  something  special
       I/O-related  needs  to be done that the library can't do	by itself. For
       now, rewinding the read data stream is the only action it can  request.
       The  rewinding  of  the	read data stream may be	necessary when doing a
       HTTP PUT	or POST	with a multi-pass authentication method.

       The callback MUST return	CURLIOE_UNKNOWNCMD if the  input  cmd  is  not
       CURLIOCMD_RESTARTREAD.

       The  clientp  argument  to  the callback	is set with the	CURLOPT_IOCTL-
       DATA(3) option.

       This option is deprecated! Do not use it.  Use  CURLOPT_SEEKFUNCTION(3)
       instead to provide seeking! If CURLOPT_SEEKFUNCTION(3) is set, this pa-
       rameter will be ignored when seeking.

DEFAULT
       By default, this	parameter is set to NULL. Not used.

PROTOCOLS
       Used with HTTP

EXAMPLE
       static curlioerr	ioctl_callback(CURL *handle, int cmd, void *clientp)
       {
	 struct	data *io = (struct data	*)clientp;
	 if(cmd	== CURLIOCMD_RESTARTREAD) {
	   lseek(fd, 0,	SEEK_SET);
	   current_offset = 0;
	   return CURLIOE_OK;
	 }
	 return	CURLIOE_UNKNOWNCMD;
       }
       {
	 struct	data ioctl_data;
	 curl_easy_setopt(curl,	CURLOPT_IOCTLFUNCTION, ioctl_callback);
	 curl_easy_setopt(curl,	CURLOPT_IOCTLDATA, &ioctl_data);
       }

AVAILABILITY
       Added in	7.12.3

RETURN VALUE
       Returns CURLE_OK	if the option is supported,  and  CURLE_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLOPT_IOCTLDATA(3), CURLOPT_SEEKFUNCTION(3),

libcurl	7.54.1			 May 31, 2017	      CURLOPT_IOCTLFUNCTION(3)

NAME | SYNOPSIS | DESCRIPTION | DEFAULT | PROTOCOLS | EXAMPLE | AVAILABILITY | RETURN VALUE | SEE ALSO

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