AIO_CANCEL(3P)

💖 aio_cancel — the POSIX Programmer's Manual girlie's guide to cancelling async I/O 💖

okay bestie, so this page lives in the POSIX Programmer's Manual, and before we even get into it there's a little heads-up you need:

🚨 PROLOG 🚨

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go consult the corresponding Linux manual page for the deets on Linux behavior), or honestly the interface may not even be implemented on Linux at all. vibe check: POSIX said it, your system might not have done it. 🙈

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✨ NAME ✨

aio_cancel — cancel an asynchronous I/O request. yes that's the whole vibe. cancelling. bye-bye request. 👋

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🌸 SYNOPSIS 🌸

#include <aio.h>

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

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🦋 DESCRIPTION 🦋

So what does aio_cancel() actually do? It shall attempt to cancel one or more asynchronous I/O requests that are currently outstanding against the file descriptor fildes. Like, outstanding as in still out there, still pending, still doing their thing. 💅

The aiocbp argument points to the asynchronous I/O control block for a particular request that you wanna cancel. And if aiocbp is NULL? Then all the outstanding cancelable asynchronous I/O requests against fildes shall be canceled. all of them. the whole friend group. 🫶

Normal asynchronous notification shall occur for asynchronous I/O operations that are successfully canceled. And if there are requests that cannot be canceled, then the normal asynchronous completion process shall take place for those requests when they are completed. no skipping steps, they finish their little journey. ✨

For requested operations that are successfully canceled, the associated error status shall be set to [ECANCELED] and the return status shall be -1. For requested operations that are not successfully canceled, the aiocbp shall not be modified by aio_cancel(). not touched. not edited. left exactly as it was. 😌

Now, careful bestie: if aiocbp is not NULL, then if fildes does not have the same value as the file descriptor with which the asynchronous operation was initiated, unspecified results occur. 🫠 unspecified!! that's the "we literally cannot tell you what happens" zone. do not go there.

Also, which operations are cancelable is implementation-defined. so it's giving "depends on your system, babe." iykyk.

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🔥 RETURN VALUE 🔥

Here's the tea on what comes back:

• The aio_cancel() function shall return the value AIO_CANCELED if the requested operation(s) were canceled. slay. ✅
• The value AIO_NOTCANCELED shall be returned if at least one of the requested operation(s) cannot be canceled because it is in progress. In this case, the state of the other operations, if any, referenced in the call to aio_cancel() is not indicated by the return value of aio_cancel(). so like, the return value is not telling you about those other ones, okay? The application may determine the state of affairs for these operations by using aio_error(). that's your girl for that question. 🔍
• The value AIO_ALLDONE is returned if all of the operations have already completed. they're done, they finished, no notes. 👑
• Otherwise, the function shall return -1 and set errno to indicate the error. 😭

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💀 ERRORS 💀

The aio_cancel() function shall fail if:

• EBADF — The fildes argument is not a valid file descriptor. that fd is giving nothing, bestie, it's not real.

The following sections are informative.

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🎀 EXAMPLES 🎀

None.

(yes, literally none. the manpage said what it said.)

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🌈 APPLICATION USAGE 🌈

None.

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⭐ RATIONALE ⭐

None.

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🧚 FUTURE DIRECTIONS 🧚

None.

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💜 SEE ALSO 💜

• aio_read()
• aio_write()

The Base Definitions volume of POSIX.1‐2017, <aio.h>

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👑 COPYRIGHT 👑

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page bestie!! 💖 this icon of a document is brought to you by IEEE/The Open Group, dated 2017, and it goes by the name AIO_CANCEL(3P). go forth and cancel responsibly. periodt. 💅✨