HP-UX Reference (11i v3 07/02) - 2 System Calls (vol 5)

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aio_cancel(2) aio_cancel(2)

NAME

aio_cancel() - cancel an asynchronous I/O operation

SYNOPSIS

#include <aio.h>

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

DESCRIPTION

The aio_cancel() function attempts to cancel the asynchronous I/O request currently outstanding for

the aiocb referenced by aiocbp or, if aiocbp is

NULL, any asynchronous I/O operations currently out-

standing for the ﬁle descriptor ﬁldes.

If an asynchronous I/O operation is successfully canceled as a result of

aio_cancel , its status is set to

ECANCELED, and any signal delivery speciﬁed for that operation is performed. Any outstanding requests

that cannot be canceled as a result of the

aio_cancel() remain enqueued and are unaffected by the

cancellation request.

Asynchronous I/O operations that are requested as a single logical operation are either completed or can-

celed atomically. Once any portion of the operation has started, it cannot be canceled. Whether or not and

when an asynchronous I/O operation can be canceled depends on the nature of the request.

If aiocbp is not

NULL, ﬁldes is ignored.

To use this function, link in the realtime library by specifying -lrt on the compiler or linker command

line.

RETURN VALUE

The aio_cancel() function returns one of the following values:

AIO_CANCELED

The asynchronous I/O operation enqueued for the aiocb referenced by aiocbp or all

asynchronous I/O operations enqueued for the ﬁle referenced by ﬁldes have been suc-

cessfully canceled.

AIO_NOTCANCELED

The asynchronous I/O operation enqueued for the aiocb referenced by aiocbp or at

least one of the asynchronous I/O operations enqueued for the ﬁle referenced by ﬁldes

have not been canceled. (The

aio_error() function must be used to determine the

status of individual operations.)

AIO_ALLDONE

The asynchronous I/O operation enqueued for the aiocb referenced by aiocbp or all

of the asynchronous I/O operations enqueued for the ﬁle referenced by ﬁldes com-

pleted before cancellation could be attempted.

-1 Failure. The requested cancellation could not be initiated. errno

is set to indicate

the error.

ERRORS

aio_cancel() detects one of the following error conditions, errno is set to the indicated value:

[EBADF] The aiocbp argument is NULL and the ﬁldes argument is not a valid ﬁle descriptor.

[EINVAL] There was no asynchronous I/O operation enqueued for the aiocb referenced by

aiocbp.