CURLOPT_CHUNK_DATA(3) - Man pages

CURLOPT_CHUNK_DATA(3)       Library Functions Manual      CURLOPT_CHUNK_DATA(3)

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 argu-
       ment to the  CURLOPT_CHUNK_BGN_FUNCTION(3)  and  CURLOPT_CHUNK_END_FUNC-
       TION(3).

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
       curl_easy_setopt(3) returns a CURLcode indicating success or error.

       CURLE_OK  (0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3).

SEE ALSO
       CURLOPT_CHUNK_BGN_FUNCTION(3), CURLOPT_WILDCARDMATCH(3)

libcurl                            2026-07-12             CURLOPT_CHUNK_DATA(3)

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