io_uring_reg...restrictions(3)

💖 io_uring_register_restrictions 💖

okay bestie, gather round, because we're talking about the liburing manual page for io_uring_register_restrictions, and honestly? it's giving bouncer at the club energy. 🎀

✨ NAME ✨

io_uring_register_restrictions — register restrictions with io_uring 🦋

🌸 SYNOPSIS 🌸

#include <liburing.h>

int io_uring_register_restrictions(struct io_uring *ring,
                                   struct io_uring_restriction *res,
                                   unsigned int nr_res);

💅 DESCRIPTION 💅

so. the io_uring_register_restrictions(3) function registers restrictions with the io_uring instance you point at with ring. the res argument is a pointer to an array of struct io_uring_restriction, and that array has nr_res entries in it. periodt. 💜

and like… what do restrictions even do, you ask? bestie, they let you limit which opcodes, register operations, or SQE flags are allowed on a ring. it's literally a sandbox for your io_uring usage. main character security energy fr fr. 👑

⚠️ okay but here's the catch and it is a big one: restrictions can only be registered if the io_uring ring was started in a disabled state — meaning you passed IORING_SETUP_R_DISABLED in your call to io_uring_setup(2). no disabled start, no restrictions. that's just the rules. 😤

and not only that — all restrictions have to be registered in a single call before you enable the ring with io_uring_enable_rings(3). one shot. no takebacks, no "wait let me add one more". you get one chance and it's iconic or it's nothing. 💀

if you want the full tea on the IORING_REGISTER_RESTRICTIONS operation and what the restriction structure actually looks like, go read io_uring_register(2). it's all in there, iykyk. 📖

🫶 RETURN VALUE 🫶

• returns 0 on success ✨
• on error, you get a negative errno value back 😭

🌈 SEE ALSO 🌈

• io_uring_enable_rings(3)
• io_uring_register(2)
• io_uring_setup(2)

and that's the whole page, bestie!! this one's from liburing-2.4, dated January 18, 2025, so you know it's fresh. go forth and sandbox your rings responsibly 💖✨🎀