curl / libcurl / API / curl_easy_setopt / CURLOPT_HEADERDATA

CURLOPT_HEADERDATA explained

Name

CURLOPT_HEADERDATA - pointer to pass to header callback

Synopsis

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

Description

Pass a pointer to be used to write the header part of the received data to.

If CURLOPT_WRITEFUNCTION or CURLOPT_HEADERFUNCTION is used, pointer will be passed in to the respective callback.

If neither of those options are set, pointer must be a valid FILE * and it will be used by a plain fwrite() to write headers to.

If you are using libcurl as a win32 DLL, you MUST use a CURLOPT_WRITEFUNCTION or CURLOPT_HEADERFUNCTION if you set this option or you will experience crashes.

Default

NULL

Protocols

All

Example

struct my_info {
  int shoesize;
  char *secret;
};
 
static size_t header_callback(char *buffer, size_t size,
                              size_t nitems, void *userdata)
{
  struct my_info *i = (struct my_info *)userdata;
 
  /* now this callback can access the my_info struct */
 
  return nitems * size;
}
 
CURL *curl = curl_easy_init();
if(curl) {
  struct my_info my = { 10, "the cookies are in the cupboard" };
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 
  curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, header_callback);
 
  /* pass in custom data to the callback */
  curl_easy_setopt(curl, CURLOPT_HEADERDATA, &my);
 
  curl_easy_perform(curl);
}

Availability

Always

Return value

Returns CURLE_OK