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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 differ (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 pri-
       ority 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 syn-
       chronized 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   description   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  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 con-
       ditions 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   asyn-
       chronously:
       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, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications 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 Standard, 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)