NAME
aio_cancel —
cancel an asynchronous I/O request
SYNOPSIS
#include
<aio.h>
int aio_cancel(int fildes, struct aiocb *aiocbp);
DESCRIPTION
The aio_cancel () function shall attempt
to cancel one or more asynchronous 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 outstanding cancelable asynchronous I/O requests against
fildes shall be canceled.
Normal asynchronous notification shall occur for asynchronous I/O operations that are successfully canceled. If there are requests that cannot 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 initiated, unspecified results occur.
Which operations are cancelable is implementation-defined.
RETURN VALUE
The aio_cancel () function shall return
the value AIO_CANCELED 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(3). 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.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
XBD <aio.h>
CHANGE HISTORY
First released in Issue 5. Included for alignment with the POSIX Realtime Extension.
Issue 6
The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Asynchronous Input and Output option.
The APPLICATION USAGE section is added.
IEEE Std 1003.1-2001 (“POSIX.1”)/Cor 2-2004, item XSH/TC2/D6/10 is applied, removing the words ``to the calling process'' in the RETURN VALUE section. The term was unnecessary and precluded threads.
Issue 7
The aio_cancel () function is moved from
the Asynchronous Input and Output option to the Base.