GNURLOPT_WRITEDATA(3)

📦 version 7.72.0, in nixos 26.05, nixpkgs unstable

💅 GNURLOPT_WRITEDATA(3) — the glow-up edition 💅

ok so real talk, this page lives in the gnurl manual (the curl_easy_setopt options corner of it), and it's about that one little pointer bestie. let's get into it ✨

🌸 NAME 🌸

CURLOPT_WRITEDATA — the custom pointer you pass to the write callback, no cap 🫶

✨ SYNOPSIS ✨

#include <gnurl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_WRITEDATA, void *pointer);

💖 DESCRIPTION 💖

okay so picture this: it's just a data pointer, right? but it gets handed straight to the write callback. and if you're using the CURLOPT_WRITEFUNCTION(3) option, this is literally the pointer you'll get in that callback's 4th argument 👑 that's the whole vibe.

but if you're not using a write callback? then you must make pointer a FILE * (cast to void *), because libcurl will pass it to fwrite(3) when it's writing data. that's not optional, bestie, that's the rule 💅

and the internal CURLOPT_WRITEFUNCTION(3) will write the data to the FILE * you gave it with this option — or to stdout if you haven't set this option at all. easy.

💀 win32 DLL girlies listen up: if you're using libcurl as a win32 DLL, you MUST use a CURLOPT_WRITEFUNCTION(3) if you set this option, otherwise you will experience crashes. not a vibe. not a drill. 😭

🎀 DEFAULT 🎀

by default, this is a FILE * to stdout. that's it, that's the default.

🦋 PROTOCOLS 🦋

used for all protocols, periodt 🌈

🍓 EXAMPLE 🍓

so the classic iconic technique? use the write callback to store the incoming data into a dynamically growing allocated buffer, and then this CURLOPT_WRITEDATA(3) is used to point to a struct or the buffer to store data in. literally main character energy ✨ like in the getinmemory example:

https://curl.haxx.se/libcurl/c/getinmemory.html

💜 AVAILABILITY 💜

available in all libcurl versions, no gatekeeping 🌸 this option was formerly known as CURLOPT_FILE, and the name CURLOPT_WRITEDATA(3) was introduced in 7.9.7 — so she's been around a minute 💅

⭐ RETURN VALUE ⭐

this will return CURLE_OK. short, sweet, slay.

🔥 SEE ALSO 🔥

and that's the whole page, bestie 🧚💖 — brought to you by libcurl 7.37.0, dated 16 Jun 2014, from the gnurl curl_easy_setopt options fam. iykyk 🫶

📦 where this page comes from