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.TH CURLOPT_IOCTLDATA 3 "November 04, 2020" "libcurl 7.78.0" "curl_easy_setopt options"

.SH NAME
CURLOPT_IOCTLDATA \- custom pointer passed to I/O callback
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IOCTLDATA, void *pointer);
.SH DESCRIPTION
Pass the \fIpointer\fP that will be untouched by libcurl and passed as the 3rd
argument in the ioctl callback set with \fICURLOPT_IOCTLFUNCTION(3)\fP.
.SH DEFAULT
By default, the value of this parameter is NULL.
.SH PROTOCOLS
Used with HTTP
.SH EXAMPLE
.nf
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);
}
.fi
.SH AVAILABILITY
Added in 7.12.3
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_IOCTLFUNCTION "(3), " CURLOPT_SEEKFUNCTION "(3), "