---
name: "CURLOPT_SEEKDATA"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_SEEKDATA"
---

# CURLOPT\_SEEKDATA(3)

pointer passed to the seek callback

## NAME

CURLOPT\_SEEKDATA - pointer passed to the seek callback

## SYNOPSIS

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

## DESCRIPTION

Data *pointer* to pass to the seek callback function. If you use the *[CURLOPT\_SEEKFUNCTION(3)](/CURLOPT_SEEKFUNCTION/3.md)* option, this is the pointer you get as input.

## DEFAULT

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

## PROTOCOLS

This functionality affects ftp, http and sftp

## EXAMPLE

```
#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);
  }
}
```

## AVAILABILITY

Added in curl 7.18.0

## RETURN VALUE

## SEE ALSO

[**CURLOPT\_DEBUGFUNCTION**(3)](/CURLOPT_DEBUGFUNCTION/3.md), [**CURLOPT\_IOCTLFUNCTION**(3)](/CURLOPT_IOCTLFUNCTION/3.md), [**CURLOPT\_SEEKFUNCTION**(3)](/CURLOPT_SEEKFUNCTION/3.md), [**CURLOPT\_STDERR**(3)](/CURLOPT_STDERR/3.md)