---
name: "CURLOPT_CHUNK_DATA"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_CHUNK_DATA"
---

# CURLOPT\_CHUNK\_DATA(3)

pointer passed to the FTP chunk callbacks

## NAME

CURLOPT\_CHUNK\_DATA - pointer passed to the FTP chunk callbacks

## SYNOPSIS

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

## DESCRIPTION

Pass a *pointer* that is untouched by libcurl and passed as the ptr argument to the *[CURLOPT\_CHUNK\_BGN\_FUNCTION(3)](/CURLOPT_CHUNK_BGN_FUNCTION/3.md)* and *[CURLOPT\_CHUNK\_END\_FUNCTION(3)](/CURLOPT_CHUNK_END_FUNCTION/3.md)*.

## DEFAULT

NULL

## PROTOCOLS

FTP

## EXAMPLE

```
#include <stdio.h>
struct callback_data {
   FILE *output;
};
static long file_is_coming(struct curl_fileinfo *finfo,
                           void *ptr,
                           int remains)
{
  struct callback_data *data = ptr;
  printf("%3d %40s %10luB ", remains, finfo->filename,
         (unsigned long)finfo->size);
  switch(finfo->filetype) {
  case CURLFILETYPE_DIRECTORY:
    printf(" DIR\n");
    break;
  case CURLFILETYPE_FILE:
    printf("FILE ");
    break;
  default:
    printf("OTHER\n");
    break;
  }
  if(finfo->filetype == CURLFILETYPE_FILE) {
    /* do not transfer files >= 50B */
    if(finfo->size > 50) {
      printf("SKIPPED\n");
      return CURL_CHUNK_BGN_FUNC_SKIP;
    }
    data->output = fopen(finfo->filename, "wb");
    if(!data->output) {
      return CURL_CHUNK_BGN_FUNC_FAIL;
    }
  }
  return CURL_CHUNK_BGN_FUNC_OK;
}
int main()
{
  /* data for callback */
  struct callback_data callback_info;
  CURL *curl = curl_easy_init();
  /* callback is called before download of concrete file started */
  curl_easy_setopt(curl, CURLOPT_CHUNK_BGN_FUNCTION, file_is_coming);
  curl_easy_setopt(curl, CURLOPT_CHUNK_DATA, &callback_info);
}
```

## AVAILABILITY

Added in 7.21.0

## RETURN VALUE

Returns CURLE\_OK if the option is supported, and CURLE\_UNKNOWN\_OPTION if not.

## SEE ALSO

[**CURLOPT\_CHUNK\_BGN\_FUNCTION**(3)](/CURLOPT_CHUNK_BGN_FUNCTION/3.md), [**CURLOPT\_WILDCARDMATCH**(3)](/CURLOPT_WILDCARDMATCH/3.md)