Man pages sections > man3 > CURLOPT_CHUNK_BGN_FUNCTION

CURLOPT_CHUNK_BGN_FUNCTION - callback before a transfer with FTP wildcardmatch

CURLOPT_CHUNK_BGN_FUNCTION(3) curl_easy_setopt options CURLOPT_CHUNK_BGN_FUNCTION(3)

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),
May 31, 2017 libcurl 7.55.1