AIO_CANCEL(P) POSIX Programmer's Manual AIO_CANCEL(P)NAMEaio_cancel - cancel an asynchronous I/O request (REALTIME)
SYNOPSIS
#include <aio.h>
int aio_cancel(int fildes, struct aiocb *aiocbp);
DESCRIPTION
The aio_cancel() function shall attempt to cancel one or more asynchro‐
nous I/O requests currently outstanding against file descriptor fildes.
The aiocbp argument points to the asynchronous I/O control block for a
particular request to be canceled. If aiocbp is NULL, then all out‐
standing cancelable asynchronous I/O requests against fildes shall be
canceled.
Normal asynchronous notification shall occur for asynchronous I/O oper‐
ations that are successfully canceled. If there are requests that can‐
not be canceled, then the normal asynchronous completion process shall
take place for those requests when they are completed.
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().
If aiocbp is not NULL, then if fildes does not have the same value as
the file descriptor with which the asynchronous operation was initi‐
ated, unspecified results occur.
Which operations are cancelable is implementation-defined.
RETURN VALUE
The aio_cancel() function shall return the value AIO_CANCELED to the
calling process if the requested operation(s) were canceled. 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().
The application may determine the state of affairs for these operations
by using aio_error(). The value AIO_ALLDONE is returned if all of the
operations have already completed. Otherwise, the function shall return
-1 and set errno to indicate the error.
ERRORS
The aio_cancel() function shall fail if:
EBADF The fildes argument is not a valid file descriptor.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The aio_cancel() function is part of the Asynchronous Input and Output
option and need not be available on all implementations.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOaio_read() , aio_write() , the Base Definitions volume of
IEEE Std 1003.1-2001, <aio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
IEEE/The Open Group 2003 AIO_CANCEL(P)
