NAME

       CURLOPT_CHUNK_BGN_FUNCTION - callback before a transfer with FTP wildcard match

SYNOPSIS

       #include <curl/curl.h>

       struct curl_fileinfo {
         char *filename;
         curlfiletype filetype;
         time_t time;   /* always zero! */
         unsigned int perm;
         int uid;
         int gid;
         curl_off_t size;
         long int hardlinks;

         struct {
           /* If some of these fields is not NULL, it is a pointer to b_data. */
           char *time;
           char *perm;
           char *user;
           char *group;
           char *target; /* pointer to the target filename of a symlink */
         } strings;

         unsigned int flags;

         /* used internally */
         char *b_data;
         size_t b_size;
         size_t b_used;
       };

       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 points to a curl_fileinfo struct 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

       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.

SEE ALSO

       CURLOPT_CHUNK_END_FUNCTION(3), CURLOPT_WILDCARDMATCH(3)