int
aio_write(
struct aiocb *aiocbp
)
)
system call allows the calling process to write
aiocbp->aio_nbytes
from the buffer pointed to by
aiocbp->aio_buf
to the descriptor
aiocbp->aio_fildes
.
The call returns immediately after the write request has been enqueued
to the descriptor; the write may or may not have completed at the time
the call returns.
If the request could not be enqueued, generally due
to invalid arguments, the call returns without having enqueued the
request.
If
O_APPEND
is set for
aiocbp->aio_fildes
,
aio_write()
operations append to the file in the same order as the calls were
made.
If
O_APPEND
is not set for the file descriptor, the write operation will occur at
the absolute position from the beginning of the file plus
aiocbp->aio_offset
.
If
_POSIX_PRIORITIZED_IO
is defined, and the descriptor supports it, then the enqueued
operation is submitted at a priority equal to that of the calling
process minus
aiocbp->aio_reqprio
.
The
aiocbp
pointer may be subsequently used as an argument to
aio_return()
and
aio_error(
)
in order to determine return or error status for the enqueued operation
while it is in progress.
If the request is successfully enqueued, the value of
aiocbp->aio_offset
can be modified during the request as context, so this value must not
be referenced after the request is enqueued.
aiocbp
and the buffer that the
aiocbp->aio_buf
member of that structure references must remain valid until the
operation has completed.
For this reason, use of auto (stack) variables
for these objects is discouraged.
The asynchronous I/O control buffer
aiocbp
should be zeroed before the
aio_write()
system call to avoid passing bogus context information to the kernel.
Modifications of the Asynchronous I/O Control Block structure or the buffer contents after the request has been enqueued, but before the request has completed, are not allowed.
If the file offset in
aiocbp->aio_offset
is past the offset maximum for
aiocbp->aio_fildes
,
no I/O will occur.
)
system call will fail if:
EAGAIN
]
The following conditions may be synchronously detected when the
aio_write()
system call is made, or asynchronously, at any time thereafter.
If they
are detected at call time,
aio_write(
)
returns -1 and sets
errno
appropriately; otherwise the
aio_return(
)
system call must be called, and will return -1, and
aio_error(
)
must be called to determine the actual value that would have been
returned in
errno.
EBADF
]
aiocbp->aio_fildes
argument
is invalid, or is not opened for writing.
EINVAL
]
aiocbp->aio_offset
is not valid, the priority specified by
aiocbp->aio_reqprio
is not a valid priority, or the number of bytes specified by
aiocbp->aio_nbytes
is not valid.
If the request is successfully enqueued, but subsequently canceled
or an error occurs, the value returned by the
aio_return()
system call is per the
write(2)
system call, and the value returned by the
aio_error(
)
system call is either one of the error returns from the
write(2)
system call, or one of:
EBADF
]
aiocbp->aio_fildes
argument
is invalid for writing.
ECANCELED
]
).
EINVAL
]
aiocbp->aio_offset
would be invalid.
)
system call
is expected to conform to the
IEEE Std 1003.1-2001 (``POSIX.1'')
standard.
)
system call first appeared in
NetBSD5.0.