#include <aio.h>

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

       Link with -lrt.

       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 ECAN-
       CELED.  The control block of requests that cannot be  canceled  is  not

       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

       Which operations are cancelable is implementation-defined.

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

              All requests were successfully canceled.

              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).

              All requests had already been completed before the call.

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

       EBADF  fd is not a valid file descriptor.

       ENOSYS aio_cancel() is not implemented.

       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

                                  2012-05-08                     AIO_CANCEL(3)
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