NAME

       CURLOPT_CHUNK_BGN_FUNCTION - callback before a transfer with FTP wildcardmatch

SYNOPSIS

       #include <curl/curl.h>

       long chunk_bgn_callback(const void *transfer_info, void *ptr,
                               int remains);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CHUNK_BGN_FUNCTION,
                                 chunk_bgn_callback);

DESCRIPTION

       Pass a pointer to your callback function, which should match the prototype shown above.

       This  callback function gets called by libcurl before a part of the stream is going to be transferred (if
       the transfer supports chunks).

       The transfer_info pointer will point to a struct curl_fileinfo with details about the file that is  about
       to get transferred.

       This callback makes sense only when using the CURLOPT_WILDCARDMATCH(3) option for now.

       The  target  of transfer_info parameter is a "feature depended" structure. For the FTP wildcard download,
       the target is curl_fileinfo structure (see curl/curl.h).   The  parameter  ptr  is  a  pointer  given  by
       CURLOPT_CHUNK_DATA(3). The parameter remains contains number of chunks remaining per the transfer. If the
       feature is not available, the parameter has zero value.

       Return CURL_CHUNK_BGN_FUNC_OK if everything is fine, CURL_CHUNK_BGN_FUNC_SKIP if you  want  to  skip  the
       concrete chunk or CURL_CHUNK_BGN_FUNC_FAIL to tell libcurl to stop if some error occurred.

DEFAULT

       NULL

PROTOCOLS

       FTP

EXAMPLE

       static long file_is_coming(struct curl_fileinfo *finfo,
                                  struct callback_data *data,
                                  int remains)
       {
         printf("%3d %40s %10luB ", remains, finfo->filename,
                (unsigned long)finfo->size);

         switch(finfo->filetype) {
         case CURLFILETYPE_DIRECTORY:
           printf(" DIR0);
           break;
         case CURLFILETYPE_FILE:
           printf("FILE ");
           break;
         default:
           printf("OTHER0);
           break;
         }

         if(finfo->filetype == CURLFILETYPE_FILE) {
           /* do not transfer files >= 50B */
           if(finfo->size > 50) {
             printf("SKIPPED0);
             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;

         /* 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

       This was 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_END_FUNCTION(3), CURLOPT_WILDCARDMATCH(3),