Differential D7462 Diff 19499 head/lib/libc/sys/aio_write.2

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head/lib/libc/sys/aio_write.2

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	.\" SUCH DAMAGE.			.\" SUCH DAMAGE.
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	.\" $FreeBSD$			.\" $FreeBSD$
	.\"			.\"
	.Dd July 21, 2016			.Dd August 19, 2016
	.Dt AIO_WRITE 2			.Dt AIO_WRITE 2
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm aio_write			.Nm aio_write
	.Nd asynchronous write to a file (REALTIME)			.Nd asynchronous write to a file (REALTIME)
	.Sh LIBRARY			.Sh LIBRARY
	.Lb libc			.Lb libc
	.Sh SYNOPSIS			.Sh SYNOPSIS
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	.Pp			.Pp
	If the request is successfully enqueued, the value of			If the request is successfully enqueued, the value of
	.Fa iocb->aio_offset			.Fa iocb->aio_offset
	can be modified during the request as context, so this value must not			can be modified during the request as context, so this value must not
	be referenced after the request is enqueued.			be referenced after the request is enqueued.
	.Pp			.Pp
	The			The
	.Fa iocb->aio_sigevent			.Fa iocb->aio_sigevent
	structure can be used to request notification of the request's			structure can be used to request notification of the operation's
	completion as described in			completion as described in
	.Xr aio 4 .			.Xr aio 4 .
	.Sh RESTRICTIONS			.Sh RESTRICTIONS
	The Asynchronous I/O Control Block structure pointed to by			The Asynchronous I/O Control Block structure pointed to by
	.Fa iocb			.Fa iocb
	and the buffer that the			and the buffer that the
	.Fa iocb->aio_buf			.Fa iocb->aio_buf
	member of that structure references must remain valid until the			member of that structure references must remain valid until the
	operation has completed.			operation has completed.
	For this reason, use of auto (stack) variables
	for these objects is discouraged.
	.Pp			.Pp
	The asynchronous I/O control buffer			The asynchronous I/O control buffer
	.Fa iocb			.Fa iocb
	should be zeroed before the			should be zeroed before the
	.Fn aio_write			.Fn aio_write
	system call to avoid passing bogus context information to the kernel.			system call to avoid passing bogus context information to the kernel.
	.Pp			.Pp
	Modifications of the Asynchronous I/O Control Block structure or the			Modifications of the Asynchronous I/O Control Block structure or the
	buffer contents after the request has been enqueued, but before the			buffer contents are not allowed while the request is queued.
	request has completed, are not allowed.
	.Pp			.Pp
	If the file offset in			If the file offset in
	.Fa iocb->aio_offset			.Fa iocb->aio_offset
	is past the offset maximum for			is past the offset maximum for
	.Fa iocb->aio_fildes ,			.Fa iocb->aio_fildes ,
	no I/O will occur.			no I/O will occur.
	.Sh RETURN VALUES			.Sh RETURN VALUES
	.Rv -std aio_write			.Rv -std aio_write
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