90 lines
1.7 KiB
Markdown
90 lines
1.7 KiB
Markdown
---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_HEADERDATA
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_HEADERFUNCTION (3)
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- CURLOPT_WRITEFUNCTION (3)
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- curl_easy_header (3)
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---
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# NAME
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CURLOPT_HEADERDATA - pointer to pass to header callback
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADERDATA, void *pointer);
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~~~
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# DESCRIPTION
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Pass a *pointer* to be used to write the header part of the received data
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to.
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If CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) is used,
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*pointer* is passed in to the respective callback.
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If neither of those options are set, *pointer* must be a valid FILE * and
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it is used by a plain fwrite() to write headers to.
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If you are using libcurl as a win32 DLL, you **MUST** use a
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CURLOPT_WRITEFUNCTION(3) or CURLOPT_HEADERFUNCTION(3) if you set
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this option or you might experience crashes.
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# DEFAULT
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NULL
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# PROTOCOLS
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All
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# EXAMPLE
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~~~c
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struct my_info {
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int shoesize;
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char *secret;
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};
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static size_t header_callback(char *buffer, size_t size,
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size_t nitems, void *userdata)
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{
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struct my_info *i = userdata;
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printf("shoe size: %d\n", i->shoesize);
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/* now this callback can access the my_info struct */
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return nitems * size;
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}
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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struct my_info my = { 10, "the cookies are in the cupboard" };
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curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
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curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, header_callback);
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/* pass in custom data to the callback */
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curl_easy_setopt(curl, CURLOPT_HEADERDATA, &my);
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curl_easy_perform(curl);
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}
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}
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~~~
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# AVAILABILITY
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Always
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# RETURN VALUE
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Returns CURLE_OK
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