CURLOPT_XFERINFODATA explained

Name

CURLOPT_XFERINFODATA - pointer passed to the progress callback

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_XFERINFODATA, void *pointer);

Description

Pass a pointer that is untouched by libcurl and passed as the first argument in the progress callback set with CURLOPT_XFERINFOFUNCTION.

This is an alias for CURLOPT_PROGRESSDATA.

Default

NULL

Protocols

This functionality affects all supported protocols

Example

struct progress {
  char *private;
  size_t size;
};
 
static int progress_cb(void *clientp,
                       curl_off_t dltotal,
                       curl_off_t dlnow,
                       curl_off_t ultotal,
                       curl_off_t ulnow)
{
  struct progress *memory = clientp;
  printf("private ptr: %p\n", memory->private);
  /* use the values */
 
  return 0; /* all is good */
}
 
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    struct progress data;
 
    /* pass struct to callback  */
    curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &data);
    curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, progress_cb);
  }
}

Availability

Added in curl 7.32.0

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

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