Man page - curlopt_headerdata(3)

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Manual

CURLOPT_HEADERDATA

NAME
SYNOPSIS
DESCRIPTION
DEFAULT
PROTOCOLS
EXAMPLE
AVAILABILITY
RETURN VALUE
SEE ALSO

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(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 Windows DLL, you MUST use a CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) if you set this option or you might experience crashes.

DEFAULT

NULL

PROTOCOLS

This functionality affects all supported protocols

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 = 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);
}
}

AVAILABILITY

Added in curl 7.10

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3) .