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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 dif-
       fer (consult 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 opera-
       tion  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 completion.

       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  descrip-
       tion associated 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 success-
       fully 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 asyn-
       chronously.   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 opera-
       tion 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  suc-
       cessfully  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
       implementations.

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, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions Issue 6, Copyright (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 Stan-
       dard, the original IEEE and The Open Group Standard is the referee  document.  The  original  Standard  can  be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                        AIO_WRITE(3P)