NAME

       io_cancel - cancel an outstanding asynchronous I/O operation

SYNOPSIS

       #include <linux/aio_abi.h>          /* Defines needed types */

       int io_cancel(aio_context_t ctx_id, struct iocb *iocb,
                     struct io_event *result);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION

       The  io_cancel()  system  call attempts to cancel an asynchronous I/O operation previously
       submitted with io_submit(2).  The iocb argument describes the operation to be canceled and
       the  ctx_id  argument  is  the  AIO  context to which the operation was submitted.  If the
       operation is successfully canceled, the event will be copied into the memory pointed to by
       result without being placed into the completion queue.

RETURN VALUE

       On success, io_cancel() returns 0.  For the failure return, see NOTES.

ERRORS

       EAGAIN The iocb specified was not canceled.

       EFAULT One of the data structures points to invalid data.

       EINVAL The AIO context specified by ctx_id is invalid.

       ENOSYS io_cancel() is not implemented on this architecture.

VERSIONS

       The asynchronous I/O system calls first appeared in Linux 2.5.

CONFORMING TO

       io_cancel()  is  Linux-specific and should not be used in programs that are intended to be
       portable.

NOTES

       Glibc does not provide a wrapper function for this system call.  You could invoke it using
       syscall(2).   But  instead,  you  probably  want  to  use the io_cancel() wrapper function
       provided by libaio.

       Note that the libaio wrapper function uses a different type (io_context_t) for the  ctx_id
       argument.   Note  also  that  the  libaio  wrapper  does  not  follow  the usual C library
       conventions for indicating errors: on  error  it  returns  a  negated  error  number  (the
       negative  of  one  of  the  values  listed  in ERRORS).  If the system call is invoked via
       syscall(2), then the return value follows the usual conventions for indicating  an  error:
       -1, with errno set to a (positive) value that indicates the error.

SEE ALSO

       io_destroy(2), io_getevents(2), io_setup(2), io_submit(2), aio(7)

COLOPHON

       This  page  is  part of release 4.04 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.