CURLOPT_SEEKDATA - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SEEKDATA, void *pointer);

Data pointer to pass to the seek callback function. If you use the CURLOPT_SEEKFUNCTION(3) option, this is the pointer you get as input.

If you do not set this, NULL is passed to the callback.

This functionality affects ftp, http and sftp

#include <unistd.h> /* for lseek() */

struct data {
  int our_fd;
};

static int seek_cb(void *clientp, curl_off_t offset, int origin)
{
  struct data *d = (struct data *)clientp;
  lseek(d->our_fd, offset, origin);
  return CURL_SEEKFUNC_OK;
}

int main(void)
{
  struct data seek_data;
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_SEEKFUNCTION, seek_cb);
    curl_easy_setopt(curl, CURLOPT_SEEKDATA, &seek_data);
  }
}

Added in curl 7.18.0

CURLOPT_DEBUGFUNCTION(3), CURLOPT_IOCTLFUNCTION(3), CURLOPT_SEEKFUNCTION(3), CURLOPT_STDERR(3)

curl_easy_setopt(3), CURLOPT_SEEKFUNCTION(3), libcurl-symbols(3).