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8269e7673c
Remove core system call implementations and documentation to lib/libsys and lib/libsys/<arch> from lib/libc/sys and lib/libc/<arch>/<sys>. Update paths to allow libc to find them in their new home. Reviewed by: kib, emaste, imp Pull Request: https://github.com/freebsd/freebsd-src/pull/908
182 lines
4.8 KiB
Groff
182 lines
4.8 KiB
Groff
.\" Copyright (c) 2013 Sergey Kandaurov
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd November 15, 2023
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.Dt AIO_FSYNC 2
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.Os
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.Sh NAME
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.Nm aio_fsync
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.Nd asynchronous file synchronization (REALTIME)
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In aio.h
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.Ft int
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.Fn aio_fsync "int op" "struct aiocb *iocb"
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.Sh DESCRIPTION
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The
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.Fn aio_fsync
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system call allows the calling process to move all modified data
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associated with the descriptor
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.Fa iocb->aio_fildes
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to a permanent storage device.
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The call returns immediately after the synchronization request has been
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enqueued to the descriptor; the synchronization may or may not have
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completed at the time the call returns.
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.Pp
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The
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.Fa op
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argument can be set to
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.Dv O_SYNC
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to cause all currently queued I/O operations to be completed
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as if by a call to
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.Xr fsync 2 ,
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or
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.Dv O_DSYNC
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for the behavior of
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.Xr fdatasync 2 .
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.Pp
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The
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.Fa iocb
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pointer may be subsequently used as an argument to
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.Fn aio_return
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and
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.Fn aio_error
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in order to determine return or error status for the enqueued operation
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while it is in progress.
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.Pp
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If the request could not be enqueued (generally due to invalid arguments),
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the call returns without having enqueued the request.
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.Pp
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The
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.Fa iocb->aio_sigevent
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structure can be used to request notification of the operation's
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completion as described in
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.Xr aio 4 .
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.Sh RESTRICTIONS
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The Asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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must remain valid until the
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operation has completed.
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.Pp
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The asynchronous I/O control buffer
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.Fa iocb
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should be zeroed before the
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.Fn aio_fsync
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call to avoid passing bogus context information to the kernel.
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.Pp
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Modification of the Asynchronous I/O Control Block structure is not allowed
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while the request is queued.
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.Sh RETURN VALUES
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.Rv -std aio_fsync
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.Sh ERRORS
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The
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.Fn aio_fsync
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system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa iocb->aio_sigevent.sigev_notify
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is invalid or not supported.
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.It Bq Er EOPNOTSUPP
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Asynchronous file synchronization operations on the file descriptor
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.Fa iocb->aio_fildes
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are unsafe and unsafe asynchronous I/O operations are disabled.
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.It Bq Er EINVAL
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A value of the
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.Fa op
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argument is not set to
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.Dv O_SYNC
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or
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.Dv O_DSYNC .
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.El
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.Pp
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The following conditions may be synchronously detected when the
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.Fn aio_fsync
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system call is made, or asynchronously, at any time thereafter.
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If they are detected at call time,
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.Fn aio_fsync
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returns -1 and sets
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.Va errno
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appropriately; otherwise the
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.Fn aio_return
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system call must be called, and will return -1, and
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.Fn aio_error
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must be called to determine the actual value that would have been
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returned in
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.Va errno .
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa iocb->aio_fildes
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argument
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is not a valid descriptor.
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.It Bq Er EINVAL
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This implementation does not support synchronized I/O for this file.
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.El
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.Pp
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If the request is successfully enqueued, but subsequently cancelled
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or an error occurs, the value returned by the
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.Fn aio_return
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system call is per the
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.Xr read 2
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and
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.Xr write 2
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system calls, and the value returned by the
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.Fn aio_error
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system call is one of the error returns from the
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.Xr read 2
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or
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.Xr write 2
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system calls.
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.Sh SEE ALSO
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.Xr aio_cancel 2 ,
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.Xr aio_error 2 ,
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.Xr aio_read 2 ,
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.Xr aio_return 2 ,
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.Xr aio_suspend 2 ,
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.Xr aio_waitcomplete 2 ,
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.Xr aio_write 2 ,
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.Xr fsync 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3 ,
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.Xr aio 4
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.Sh STANDARDS
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The
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.Fn aio_fsync
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system call is expected to conform to the
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.St -p1003.1
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standard.
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.Sh HISTORY
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The
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.Fn aio_fsync
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system call first appeared in
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.Fx 7.0 .
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The
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.Dv O_DSYNC
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option appeared in
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.Fx 13.0 .
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