AIO_CANCEL(2)

✨ AIO_CANCEL 💅 — the aio_cancel system call, from the System Calls Manual

okay bestie, buckle up 🎀 this is aio_cancel(2), and it's here to ✨ cancel an outstanding asynchronous I/O operation (REALTIME) ✨. yes, REALTIME. that's the vibe.

📚 LIBRARY

Standard C Library (libc, -lc) 🫶

---

🌸 SYNOPSIS

#include <aio.h>

int
aio_cancel(int fildes, struct aiocb *iocb);

---

💖 DESCRIPTION

so the aio_cancel() system call does exactly what it says on the tin, no cap: it cancels the outstanding asynchronous I/O request for the file descriptor you passed in as fildes. iconic behaviour, honestly.

and if you also hand it an iocb? then it's picky — only that specific asynchronous I/O request gets cancelled. main character energy, it knows what it wants. 👑

Normal asynchronous notification occurs for cancelled requests — so like, the notification system still does its thing, don't worry. and those requests complete with an error result of ECANCELED. so yeah, they end, but they end sad. 😭

---

🚧 RESTRICTIONS

okay lowkey important, listen up:

The aio_cancel() system call does not cancel asynchronous I/O requests for raw disk devices. nope. not happening. not today. 🙈

The aio_cancel() system call will always return AIO_NOTCANCELED for file descriptors associated with raw disk devices. always. every single time. it's giving "we said no."

---

🌈 RETURN VALUES

The aio_cancel() system call returns -1 to indicate an error, or one of the following:

• [AIO_CANCELED] — all outstanding requests meeting the criteria specified were cancelled. slay, we ate. 💅✨
• [AIO_NOTCANCELED] — some requests were not cancelled, status for the requests should be checked with aio_error(2). so go check, bestie, don't just sit there 🫶
• [AIO_ALLDONE] — all of the requests meeting the criteria have finished. like, they were already done before you even asked. awkward but okay 💀

---

💀 ERRORS

An error return from aio_cancel() indicates:

• [EBADF] — the fildes argument is an invalid file descriptor. bestie that fd is not real, that fd is a ghost 👻

---

🔗 SEE ALSO

aio_error(2), aio_read(2), aio_return(2), aio_suspend(2), aio_write(2), aio(4) — the whole friend group, go read them all 🎀

---

📏 STANDARDS

The aio_cancel() system call is expected to conform to the IEEE Std 1003.1 (“POSIX.1”) standard. certified, official, legit, no cap. ⭐

---

🦋 HISTORY

The aio_cancel() system call first appeared in FreeBSD 3.0. The first functional implementation of aio_cancel() appeared in FreeBSD 4.0. so like, it existed, then it actually existed. character development. 🌸

---

👑 AUTHORS

This manual page was originally written by Wes Peters <wes@softweyr.com>. Christopher M Sedore <cmsedore@maxwell.syr.edu> updated it when aio_cancel() was implemented for FreeBSD 4.0. legends, both of them, we stan 💜

---

and that's the whole page, bestie!! this one's from the Debian crew, dated January 19, 2000, and it lives in section 2 of the manual (AIO_CANCEL(2)). go cancel something (responsibly) 💖✨