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NAME

       io_cancel - cancel an outstanding asynchronous I/O operation

SYNOPSIS

       #include <libaio.h>

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

       Link with -laio.

DESCRIPTION

       io_cancel() attempts to cancel an asynchronous I/O operation previously
       submitted with io_submit(2).  ctx_id is  the  AIO  context  ID  of  the
       operation  to be canceled.  If the AIO context is found, the event will
       be canceled and then 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,  August
       2002.

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.

       The wrapper provided in libaio for  io_cancel()  does  not  follow  the
       usual C library conventions for indicating error: 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)

COLOPHON

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       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.