AIO_WRITE(3P)                                       POSIX Programmer's Manual                                      AIO_WRITE(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       aio_write - asynchronous write to a file (REALTIME)

SYNOPSIS
       #include <aio.h>

       int aio_write(struct aiocb *aiocbp);


DESCRIPTION
       The  aio_write()  function  shall write aiocbp->aio_nbytes to the file associated with aiocbp->aio_fildes from the buffer
       pointed to by aiocbp->aio_buf.  The function shall return when the write request has been initiated  or,  at  a  minimum,
       queued to the file or device.

       If  prioritized I/O is supported for this file, then the asynchronous operation shall be submitted at a priority equal to
       the scheduling priority of the process minus aiocbp->aio_reqprio.

       The aiocbp argument may be used as an argument to aio_error() and aio_return() in order to determine the error status and
       return status, respectively, of the asynchronous operation while it is proceeding.

       The  aiocbp  argument  points  to  an  aiocb  structure. If the buffer pointed to by aiocbp->aio_buf or the control block
       pointed to by aiocbp becomes an illegal address prior to asynchronous I/O completion, then the behavior is undefined.

       If O_APPEND is not set for the file descriptor aio_fildes, then the requested operation shall take place at the  absolute
       position  in the file as given by aio_offset, as if lseek() were called immediately prior to the operation with an offset
       equal to aio_offset and a whence equal to SEEK_SET. If O_APPEND is set for the file descriptor, write  operations  append
       to  the  file in the same order as the calls were made. After a successful call to enqueue an asynchronous I/O operation,
       the value of the file offset for the file is unspecified.

       The aiocbp->aio_lio_opcode field shall be ignored by aio_write().

       Simultaneous asynchronous operations using the same aiocbp produce undefined results.

       If synchronized I/O is enabled on the file associated with aiocbp->aio_fildes, the behavior of  this  function  shall  be
       according  to  the definitions of synchronized I/O data integrity completion, and synchronized I/O file integrity comple-
       tion.

       For any system action that changes the process memory space while an asynchronous I/O is outstanding to the address range
       being changed, the result of that action is undefined.

       For  regular files, no data transfer shall occur past the offset maximum established in the open file description associ-
       ated with aiocbp->aio_fildes.

RETURN VALUE
       The aio_write() function shall return the value zero to the calling process if the I/O operation is successfully  queued;
       otherwise, the function shall return the value -1 and set errno to indicate the error.

ERRORS
       The aio_write() function shall fail if:

       EAGAIN The requested asynchronous I/O operation was not queued due to system resource limitations.


       Each of the following conditions may be detected synchronously at the time of the call to aio_write(), or asynchronously.
       If any of the conditions below are detected synchronously, the aio_write() function shall return -1 and set errno to  the
       corresponding  value.  If  any of the conditions below are detected asynchronously, the return status of the asynchronous
       operation shall be set to -1, and the error status of the asynchronous operation is set to the corresponding value.

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid, aiocbp->aio_reqprio is not a valid value, or
              aiocbp->aio_nbytes is an invalid value.


       In  the  case that the aio_write() successfully queues the I/O operation, the return status of the asynchronous operation
       shall be one of the values normally returned by the write() function call. If the operation is successfully queued but is
       subsequently  canceled or encounters an error, the error status for the asynchronous operation contains one of the values
       normally set by the write() function call, or one of the following:

       EBADF  The aiocbp->aio_fildes argument is not a valid file descriptor open for writing.

       EINVAL The file offset value implied by aiocbp->aio_offset would be invalid.

       ECANCELED
              The requested I/O was canceled before the I/O completed due to an explicit aio_cancel() request.


       The following condition may be detected synchronously or asynchronously:

       EFBIG  The file is a regular file, aiobcp->aio_nbytes is greater than 0, and the starting offset in aiobcp->aio_offset is
              at or beyond the offset maximum in the open file description associated with aiocbp->aio_fildes.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The aio_write() function is part of the Asynchronous Input and Output option and need not be available on all implementa-
       tions.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       aio_cancel(), aio_error(), aio_read(), aio_return(), close(), exec(), exit(), fork(), lio_listio(), lseek(), write(), the
       Base Definitions volume of IEEE Std 1003.1-2001, <aio.h>

COPYRIGHT
       Portions  of  this  text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for
       Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6,  Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open  Group
       Standard   is   the   referee   document.   The   original   Standard   can   be   obtained  online  at  http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                 AIO_WRITE(3P)