curl / libcurl / API / curl_easy_setopt / CURLOPT_IOCTLDATA

CURLOPT_IOCTLDATA explained

Name

CURLOPT_IOCTLDATA - pointer passed to I/O callback

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IOCTLDATA, void *pointer);

Description

Pass the pointer that is untouched by libcurl and passed as the 3rd argument in the ioctl callback set with CURLOPT_IOCTLFUNCTION.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

#include <unistd.h> /* for lseek */
 
struct data {
  int fd; /* our file descriptor */
};
 
static curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp)
{
  struct data *io = (struct data *)clientp;
  if(cmd == CURLIOCMD_RESTARTREAD) {
    lseek(io->fd, 0, SEEK_SET);
    return CURLIOE_OK;
  }
  return CURLIOE_UNKNOWNCMD;
}
int main(void)
{
  struct data ioctl_data;
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_IOCTLFUNCTION, ioctl_callback);
    curl_easy_setopt(curl, CURLOPT_IOCTLDATA, &ioctl_data);
  }
}

Deprecated

Deprecated since 7.18.0.

Availability

Added in curl 7.12.3

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.