The
aio_write() function requests an asynchronous "n = write(fd, buf, count)"
with fd, buf, count given by
aiocbp->aio_fildes,
aiocbp->aio_buf,
aiocbp->aio_nbytes, respectively. The return status n can be retrieved upon completion using
aio_return(3).
If O_APPEND is not set, the data is written starting at the
absolute file offset
aiocbp->aio_offset, regardless of the current file position.
If O_APPEND is set, the data is written at the end of the file.
After this request, the value of the current file position is unspecified.
The "asynchronous" means that this call returns as soon as the
request has been enqueued; the write may or may not have completed
when the call returns. One tests for completion using
aio_error(3).
If _POSIX_PRIORITIZED_IO is defined, and this file supports it,
then the asynchronous operation is submitted at a priority equal
to that of the calling process minus
aiocbp->aio_reqprio.
The field
aiocbp->aio_lio_opcode is ignored.
No data is written to a regular file beyond its maximum offset.
On success, 0 is returned. On error the request is not enqueued, -1
is returned, and
errno is set appropriately. If an error is first detected later, it will
be reported via
aio_return(3)
(returns status -1) and
aio_error(3)
(error status whatever one would have gotten in
errno, such as EBADF).
It is a good idea to zero out the control block before use.
This control block must not be changed while the write operation
is in progress.
The buffer area being written out
must not be accessed during the operation or undefined results may
occur. The memory areas involved must remain valid.
