curl / libcurl / API / curl_easy_setopt / CURLOPT_CHUNK_DATA

CURLOPT_CHUNK_DATA explained

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 and CURLOPT_CHUNK_END_FUNCTION.

Default

NULL

Protocols

This functionality affects ftp only

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 curl 7.21.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.