CURLOPT_STREAM_DEPENDS_E(3)

📦
version 8.18.0 · 25 versions
, in fedora 44

💅 CURLOPT_STREAM_DEPENDS_E(3) — like, the exclusive-stream-dependency one, bestie

okay so this is a page from the Library Functions Manual and honestly? it's giving "iconic feature that got canceled" 😭 but we're gonna learn it anyway because knowledge is free ✨ the function is CURLOPT_STREAM_DEPENDS_E and its whole personality is "stream this transfer depends on exclusively" — and yes, the _E stands for Exclusive, we love a dramatic capital letter 💅

✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_DEPENDS_E,
                          CURL *dephandle);

🌸 DESCRIPTION 🌸

so basically you pass a CURL pointer in dephandle and that's you telling curl "hey bestie, this stream depends on that stream — exclusively — within the same connection." 🫶 that means it depends on it and it sets the Exclusive bit. both things. at once. main character energy fr fr 👑

the spec is out here saying, and I quote directly:

"Including a dependency expresses a preference to allocate resources to the identified stream rather than to the dependent stream."

like yes, the spec said preference, we love a polite king 🌈

and okay, here's the tea on what exclusive actually does: setting a dependency with the exclusive flag for a reprioritized stream causes all the dependencies of the new parent stream to become dependent on the reprioritized stream. so like... the whole family tree gets rearranged. it's giving reprioritization arc 💀

this option can be set during transfer — no need to finish anything first, go off ✨

now the rules, because there are always rules 🙈:

  • dephandle must not be the same as handle. if you do that? the function returns an error. not it.
  • it must be another easy handle
  • and it also needs to be a handle of a transfer that is about to be sent over the same HTTP/2 connection — otherwise this option doesn't actually do anything, it's just vibes 💅
⚠️ and now for the sad part 😭 — since version 8.21.0, setting this option no longer has an effect. HTTP/2 stream dependencies were introduced in RFC 7540 and then later deprecated in RFC 9113. it was iconic, then it was deprecated. we've all been there 🎀

🎀 DEFAULT 🎀

NULL

(obviously. no dependency, no drama. a clean slate. a fresh face. 🦋)

🦋 PROTOCOLS 🦋

this functionality affects http only — that's it, that's the tweet 💜

🔥 EXAMPLE 🔥

here's the actual example, character for character, because we do not mess with code in this house:

int main(void)
{
  CURL *curl = curl_easy_init();
  CURL *curl2 = curl_easy_init(); /* a second handle */
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/one");

    /* the second depends on the first */
    curl_easy_setopt(curl2, CURLOPT_URL, "https://example.com/two");
    curl_easy_setopt(curl2, CURLOPT_STREAM_DEPENDS_E, curl);

    /* then add both to a multi handle and transfer them */
  }
}

see how curl2 is like "I'm nothing without curl" 😭 obsessed. the comment literally says /* the second depends on the first */ — the way that comment ate 💀

💀 DEPRECATED 💀

Deprecated since 8.21.0. yeah. we know. it's fine. it's fine. 🥲

⭐ AVAILABILITY ⭐

Added in curl 7.46.0 — a vintage. an icon. a legend, even 🌟

🌈 RETURN VALUE 🌈

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

CURLE_OK (0) means everything was OK — slay 🎉 non-zero means an error occurred, so go check libcurl-errors(3) for the whole lore dump 📖

👑 SEE ALSO 👑

(yes go read those too, we're nothing if not thorough 🫶)

and that's the whole page, bestie 💖 brought to you by libcurl, dated 2026-10-12, with love from the Library Functions Manual — stay exclusive, stay deprecated, stay iconic ✨ 🎀 🦋 💅

📦 where this page comes from