NAME

       aio_cancel - cancel an outstanding asynchronous I/O request

SYNOPSIS

       #include <aio.h>

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

       Link with -lrt.

DESCRIPTION

       The  aio_cancel()  function  attempts  to  cancel  outstanding  asynchronous  I/O  requests  for the file
       descriptor fd.  If aiocbp is NULL, all such requests are canceled.  Otherwise, only the request described
       by the control block pointed to by aiocbp is canceled.  (See  aio(7)  for  a  description  of  the  aiocb
       structure.)

       Normal  asynchronous notification occurs for canceled requests (see aio(7) and sigevent(7)).  The request
       return status (aio_return(3)) is set to -1, and  the  request  error  status  (aio_error(3))  is  set  to
       ECANCELED.  The control block of requests that cannot be canceled is not changed.

       If  the  request  could not be canceled, then it will terminate in the usual way after performing the I/O
       operation.  (In this case, aio_error(3) will return the status EINPROGRESSS.)

       If aiocbp is not NULL, and fd differs from 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 returns one of the following values:

       AIO_CANCELED
              All requests were successfully canceled.

       AIO_NOTCANCELED
              At least one of the requests specified was not canceled because it was in progress.  In this case,
              one may check the status of individual requests using aio_error(3).

       AIO_ALLDONE
              All requests had already been completed before the call.

       -1     An error occurred.  The cause of the error can be found by inspecting errno.

ERRORS

       EBADF  fd is not a valid file descriptor.

       ENOSYS aio_cancel() is not implemented.

VERSIONS

       The aio_cancel() function is available since glibc 2.1.

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008.

EXAMPLE

       See aio(7).

SEE ALSO

       aio_error(3),  aio_fsync(3),  aio_read(3),  aio_return(3),  aio_suspend(3),  aio_write(3), lio_listio(3),
       aio(7)

COLOPHON

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

                                                   2012-05-08                                      AIO_CANCEL(3)