flex_array_size(9)

📦 version 7.3.1, in nixpkgs unstable

💅 flex_array_size(9) — the Kernel API Manual, but make it make sense 🫶

okay so bestie, this page lives in the Kernel API Manual and it's literally all about not getting owned by arithmetic while you're sizing up a flexible array member. tiny function, huge slay. let's get into it ✨

💖 NAME 💖

flex_array_size — Calculate size of a flexible array member within an enclosing structure.

yes that's the whole vibe. it tells you how many bytes that trailing flexible array actually eats. iconic behaviour honestly 🎀

✨ SYNOPSIS ✨

flex_array_size (p , member , count );

look at her. three args. no notes. 💅

🌸 ARGUMENTS 🌸

  • p — Pointer to the structure. like, the actual struct, bestie, not a copy, the pointer. 👑
  • member — Name of the flexible array member. the one chilling at the end of the struct doing its thing.
  • count — Number of elements in the array. how many of them you want, fr fr.

🦋 DESCRIPTION 🦋

Calculates size of a flexible array of count number of member elements, at the end of structure p.

that's it. that's the whole bit. you hand it the struct pointer, the member name, and a count, and it hands you back the byte math. no cap, it's giving "trusted friend who does your taxes" energy 🧚

🔥 RETURN 🔥

number of bytes needed — or SIZE_MAX on overflow. 😭 so like, if the math blows up it does not just quietly wrap around and hand you a cursed number; it gives you SIZE_MAX so you can go "oh no bestie" and bail. check for it. please. 🙈

🌈 SEE ALSO 🌈

Kernel file ./include/linux/overflow.h — the mothership, honestly. 💜

and then the whole friend group, all in section (9):

the entire overflow.h cinematic universe, and every single one of them is on their grind ⭐

lowkey important: this is the whole page. that's everything it says. so don't come for me about missing lore — there isn't any. go read overflow.h if you want the director's commentary 🍓

okay and finally, the little sign-off the page carries at the bottom: it's sourced from ./include/linux, dated October 2026. so when you cite it, that's the receipt. periodt. 🫶💖

📦 where this page comes from