DOKK / manpages / debian 12 / libcurl4-doc / CURLOPT_HEADERDATA.3.en
CURLOPT_HEADERDATA(3) curl_easy_setopt options CURLOPT_HEADERDATA(3)

CURLOPT_HEADERDATA - pointer to pass to header callback

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

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

If CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) 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(3) or CURLOPT_HEADERFUNCTION(3) if you set this option or you will experience crashes.

NULL

All

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); }

Always

Returns CURLE_OK

CURLOPT_HEADERFUNCTION(3), CURLOPT_WRITEFUNCTION(3),

January 5, 2023 libcurl 7.88.1