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Diffstat (limited to 'lib/libc/sys/aio_write.2')
| -rw-r--r-- | lib/libc/sys/aio_write.2 | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/lib/libc/sys/aio_write.2 b/lib/libc/sys/aio_write.2 new file mode 100644 index 0000000..231ea73c --- /dev/null +++ b/lib/libc/sys/aio_write.2 @@ -0,0 +1,192 @@ +.\" Copyright (c) 1999 Softweyr LLC. +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY Softweyr LLC AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL Softweyr LLC OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $Id$ +.\" +.Dd June 2, 1999 +.Dt AIO_WRITE 2 +.Os +.Sh NAME +.Nm aio_write +.Nd asynchronus write to a file (REALTIME) +.Sh SYNOPSIS +.Fd #include <aio.h> +.Ft int +.Fn aio_write "struct aiocb *iocb" +.Sh DESCRIPTION +The +.Fn aio_write +function allows the calling process to write +.Ar iocb->aio_nbytes +from the buffer pointed to by +.Ar iocb->aio_buf +to the descriptor +.Ar iocb->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. +.Pp +If +.Dv O_APPEND +is set for +.Ar iocb->aio_fildes , +.Fn aio_write +operations append to the file in the same order as the calls were +made. If +.Dv 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 +.Ar iocb->aio_offset . +.Pp +If +.Dv _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 +.Ar iocb->aio_reqprio . +.Pp +The +.Ar iocb +pointer may be subsequently used as an argument to +.Fn aio_return +and +.Fn aio_error +in order to determine return or error status for the enqueued operation +while it is in progress. +.Pp +If the request is successfully enqueued, the value of +.Ar iocb->aio_offset +can be modified during the request as context, so this value must not +be referenced after the request is enqueued. +.Sh RESTRICTIONS +The Asynchronous I/O Control Block structure pointed to by +.Ar iocb +and the buffer that the +.Ar iocb->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. +.Pp +The asynchronous I/O control buffer +.Ar iocb +should be zeroed before the +.Fn aio_read +call to avoid passing bogus context information to the kernel. +.Pp +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. +.Pp +If the file offset in +.Ar iocb->aio_offset +is past the offset maximum for +.Ar iocb->aio_fildes , +no I/O will occur. +.Sh RETURN VALUES +.Rv -std aio_write +.Sh ERRORS +The +.Fn aio_write +function will fail if: +.Bl -tag -width Er +.It Bq Er EAGAIN +The request was not queued because of system resource limitations. +.It Bq Er ENOSYS +The +.Fn aio_write +call is not supported. +.El +.Pp +The following conditions may be synchronously detected when the +.Fn aio_write +call is made, or asynchronously, at any time thereafter. If they +are detected at call time, +.Fn aio_write +returns -1 and sets +.Ar errno +appropriately; otherwise the +.Fn aio_return +function must be called, and will return -1, and +.Fn aio_error +must be called to determine the actual calue that would have been +returned in +.Ar errno . +.Pp +.Bl -tag -width Er +.It Bq Er EBADF +.Ar iocb->aio_fildes +is invalid, or is not opened for writing. +.It Bq Er EINVAL +The offset +.Ar iocb->aio_offset +is not valid, the priority specified by +.Ar iocb->aio_reqprio +is not a valid priority, or the number of bytes specified by +.Ar iocb->aio_nbytes +is not valid. +.El +.Pp +If the request is successfully enqueued, but subsequently cancelled +or an error occurs, the value returned by the +.Fn aio_return +function is per the +.Xr write 2 +call, and the value returned by the +.Fn aio_error +function is either one of the error returns from the +.Xr write 2 +call, or one of: +.Bl -tag -width Er +.It Bq Er EBADF +.Ar iocb->aio_fildes +is invalid for writing. +.It Bq Er ECANCELED +The request was explicitly cancelled via a call to +.Fn aio_cancel . +.It Bq Er EINVAL +The offset +.Ar iocb->aio_offset +would be invalid. +.El +.Sh STANDARDS +.Fn aio_write +is expected to conform to the +.St -p1003.2 +standard. +.Sh HISTORY +The +.Nm +Function first appeared in +.Fx 3.0 . +.Sh AUTHOR +This manual page was written by +.An Wes Peters Aq wes@softweyr.com . +.Sh BUGS +Asynchronous I/O operations cannot be cancelled in this implementation. +Invalid information in +.Ar iocb->_aiocb_private +may confuse the kernel. + |
