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
       parameter will be ignored when seeking.

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

PROTOCOLS
       Used with HTTP

EXAMPLE
       TODO

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 7.54.0                 February 03, 2016      CURLOPT_IOCTLFUNCTION(3)