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NAME

       io_setup - create an asynchronous I/O context

SYNOPSIS

       #include <libaio.h>

       int io_setup(unsigned nr_events, aio_context_t *ctxp);

       Link with -laio.

DESCRIPTION

       io_setup()  creates an asynchronous I/O context capable of receiving at
       least nr_events.  ctxp must not point to an AIO  context  that  already
       exists,  and must be initialized to 0 prior to the call.  On successful
       creation of the AIO context, *ctxp is  filled  in  with  the  resulting
       handle.

RETURN VALUE

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

       io_setup()  returns  0  on  success;  on failure, it returns one of the
       errors listed under ERRORS.

ERRORS

       EAGAIN The specified nr_events exceeds the user’s  limit  of  available
              events.

       EFAULT An invalid pointer is passed for ctxp.

       EINVAL ctxp  is  not  initialized,  or  the specified nr_events exceeds
              internal limits. nr_events should be greater than 0.

       ENOMEM Insufficient kernel resources are available.

       ENOSYS io_setup() is not implemented on this architecture.

VERSIONS

       The asynchronous I/O system calls first appeared in Linux  2.5,  August
       2002.

CONFORMING TO

       io_setup()  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_setup() 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_cancel(2), io_destroy(2), io_getevents(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/.