fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
145 lines
4.0 KiB
Groff
145 lines
4.0 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. 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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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)open.2 8.2 (Berkeley) 11/16/93
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.\" $FreeBSD$
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.\"
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.Dd January 23, 2014
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.Dt POSIX_FALLOCATE 2
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.Os
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.Sh NAME
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.Nm posix_fallocate
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.Nd pre-allocate storage for a range in a file
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In fcntl.h
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.Ft int
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.Fn posix_fallocate "int fd" "off_t offset" "off_t len"
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.Sh DESCRIPTION
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Required storage for the range
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.Fa offset
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to
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.Fa offset +
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.Fa len
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in the file referenced by
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.Fa fd
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is guaranteed to be allocated upon successful return.
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That is, if
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.Fn posix_fallocate
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returns successfully, subsequent writes to the specified file data
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will not fail due to lack of free space on the file system storage
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media.
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Any existing file data in the specified range is unmodified.
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If
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.Fa offset +
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.Fa len
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is beyond the current file size, then
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.Fn posix_fallocate
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will adjust the file size to
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.Fa offset +
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.Fa len .
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Otherwise, the file size will not be changed.
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.Pp
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Space allocated by
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.Fn posix_fallocate
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will be freed by a successful call to
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.Xr creat 2
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or
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.Xr open 2
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that truncates the size of the file.
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Space allocated via
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.Fn posix_fallocate
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may be freed by a successful call to
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.Xr ftruncate 2
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that reduces the file size to a size smaller than
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.Fa offset +
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.Fa len .
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.Sh RETURN VALUES
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If successful,
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.Fn posix_fallocate
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returns zero.
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It returns an error on failure, without setting
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.Va errno .
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.Sh ERRORS
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Possible failure conditions:
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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 fd
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argument is not a valid file descriptor.
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.It Bq Er EBADF
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The
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.Fa fd
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argument references a file that was opened without write permission.
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.It Bq Er EFBIG
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The value of
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.Fa offset +
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.Fa len
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is greater than the maximum file size.
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.It Bq Er EINTR
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A signal was caught during execution.
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.It Bq Er EINVAL
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The
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.Fa len
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argument was less than or equal to zero or the
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.Fa offset
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argument was less than zero.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to a file system.
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.It Bq Er ENODEV
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The
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.Fa fd
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argument does not refer to a regular file.
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.It Bq Er ENOSPC
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There is insufficient free space remaining on the file system storage
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media.
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.It Bq Er ESPIPE
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The
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.Fa fd
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argument is associated with a pipe or FIFO.
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.El
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.Sh SEE ALSO
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.Xr creat 2 ,
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.Xr ftruncate 2 ,
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.Xr open 2 ,
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.Xr unlink 2
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.Sh STANDARDS
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The
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.Fn posix_fallocate
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system call conforms to
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.St -p1003.1-2004 .
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.Sh HISTORY
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The
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.Fn posix_fallocate
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function appeared in
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.Fx 9.0 .
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.Sh AUTHORS
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.Fn posix_fallocate
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and this manual page were initially written by
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.An Matthew Fleming Aq Mt mdf@FreeBSD.org .
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