CURLOPT_HEADERDATA - Man Page
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
Returns CURLE_OK
See Also
CURLOPT_HEADERFUNCTION(3), CURLOPT_WRITEFUNCTION(3), curl_easy_header(3)
Referenced By
curl_easy_setopt(3), CURLOPT_HEADERFUNCTION(3), CURLOPT_READDATA(3), CURLOPT_WRITEDATA(3), libcurl-symbols(3), libcurl-tutorial(3).