CURLOPT_HEADERDATA(3) libcurl 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 is passed in to the respective callback.

If neither of those options are set, pointer must be a valid FILE * and it is 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 might 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 = userdata;
printf("shoe size: %d\n", i->shoesize);
/* now this callback can access the my_info struct */
return nitems * size; } int main(void) {
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

curl_easy_header(3), CURLOPT_HEADERFUNCTION(3), CURLOPT_WRITEFUNCTION(3)

December 4, 2023 ibcurl 8.5.0