AIO_WRITE(P) POSIX Programmer's Manual AIO_WRITE(P)NAMEaio_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 ALSOaio_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(P)
