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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>
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 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(" 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;
/* 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),

November 4, 2020 libcurl 7.79.1