1.\" Copyright (c) 1980, 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 4. Neither the name of the University nor the names of its contributors
13.\" may be used to endorse or promote products derived from this software
14.\" without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" @(#)open.2 8.2 (Berkeley) 11/16/93
29.\" $FreeBSD: stable/10/lib/libc/sys/posix_fallocate.2 261560 2014-02-06 19:47:17Z kib $
30.\"
31.Dd January 23, 2014
32.Dt POSIX_FALLOCATE 2
33.Os
34.Sh NAME
35.Nm posix_fallocate
36.Nd pre-allocate storage for a range in a file
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In fcntl.h
41.Ft int
42.Fn posix_fallocate "int fd" "off_t offset" "off_t len"
43.Sh DESCRIPTION
44Required storage for the range
45.Fa offset
46to
47.Fa offset +
48.Fa len
49in the file referenced by
50.Fa fd
51is guaranteed to be allocated upon successful return.
52That is, if
53.Fn posix_fallocate
54returns successfully, subsequent writes to the specified file data
55will not fail due to lack of free space on the file system storage
56media.
57Any existing file data in the specified range is unmodified.
58If
59.Fa offset +
60.Fa len
61is beyond the current file size, then
62.Fn posix_fallocate
63will adjust the file size to
64.Fa offset +
65.Fa len .
66Otherwise, the file size will not be changed.
67.Pp
68Space allocated by
69.Fn posix_fallocate
70will be freed by a successful call to
71.Xr creat 2
72or
73.Xr open 2
74that truncates the size of the file.
75Space allocated via
76.Fn posix_fallocate
77may be freed by a successful call to
78.Xr ftruncate 2
79that reduces the file size to a size smaller than
80.Fa offset +
81.Fa len .
82.Sh RETURN VALUES
83If successful,
84.Fn posix_fallocate
85returns zero.
86It returns an error on failure, without setting
87.Va errno .
88.Sh ERRORS
89Possible failure conditions:
90.Bl -tag -width Er
91.It Bq Er EBADF
92The
93.Fa fd
94argument is not a valid file descriptor.
95.It Bq Er EBADF
96The
97.Fa fd
98argument references a file that was opened without write permission.
99.It Bq Er EFBIG
100The value of
101.Fa offset +
102.Fa len
103is greater than the maximum file size.
104.It Bq Er EINTR
105A signal was caught during execution.
106.It Bq Er EINVAL
107The
108.Fa len
109argument was less than or equal to zero or the
110.Fa offset
111argument was less than zero.
112.It Bq Er EIO
113An I/O error occurred while reading from or writing to a file system.
114.It Bq Er ENODEV
115The
116.Fa fd
117argument does not refer to a regular file.
118.It Bq Er ENOSPC
119There is insufficient free space remaining on the file system storage
120media.
121.It Bq Er ESPIPE
122The
123.Fa fd
124argument is associated with a pipe or FIFO.
125.El
126.Sh SEE ALSO
127.Xr creat 2 ,
128.Xr ftruncate 2 ,
129.Xr open 2 ,
130.Xr unlink 2
131.Sh STANDARDS
132The
133.Fn posix_fallocate
134system call conforms to
135.St -p1003.1-2004 .
136.Sh HISTORY
137The
138.Fn posix_fallocate
139function appeared in
140.Fx 9.0 .
141.Sh AUTHORS
142.Fn posix_fallocate
143and this manual page were initially written by
144.An Matthew Fleming Aq mdf@FreeBSD.org .
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 4. Neither the name of the University nor the names of its contributors
13.\" may be used to endorse or promote products derived from this software
14.\" without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" @(#)open.2 8.2 (Berkeley) 11/16/93
29.\" $FreeBSD: stable/10/lib/libc/sys/posix_fallocate.2 261560 2014-02-06 19:47:17Z kib $
30.\"
31.Dd January 23, 2014
32.Dt POSIX_FALLOCATE 2
33.Os
34.Sh NAME
35.Nm posix_fallocate
36.Nd pre-allocate storage for a range in a file
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In fcntl.h
41.Ft int
42.Fn posix_fallocate "int fd" "off_t offset" "off_t len"
43.Sh DESCRIPTION
44Required storage for the range
45.Fa offset
46to
47.Fa offset +
48.Fa len
49in the file referenced by
50.Fa fd
51is guaranteed to be allocated upon successful return.
52That is, if
53.Fn posix_fallocate
54returns successfully, subsequent writes to the specified file data
55will not fail due to lack of free space on the file system storage
56media.
57Any existing file data in the specified range is unmodified.
58If
59.Fa offset +
60.Fa len
61is beyond the current file size, then
62.Fn posix_fallocate
63will adjust the file size to
64.Fa offset +
65.Fa len .
66Otherwise, the file size will not be changed.
67.Pp
68Space allocated by
69.Fn posix_fallocate
70will be freed by a successful call to
71.Xr creat 2
72or
73.Xr open 2
74that truncates the size of the file.
75Space allocated via
76.Fn posix_fallocate
77may be freed by a successful call to
78.Xr ftruncate 2
79that reduces the file size to a size smaller than
80.Fa offset +
81.Fa len .
82.Sh RETURN VALUES
83If successful,
84.Fn posix_fallocate
85returns zero.
86It returns an error on failure, without setting
87.Va errno .
88.Sh ERRORS
89Possible failure conditions:
90.Bl -tag -width Er
91.It Bq Er EBADF
92The
93.Fa fd
94argument is not a valid file descriptor.
95.It Bq Er EBADF
96The
97.Fa fd
98argument references a file that was opened without write permission.
99.It Bq Er EFBIG
100The value of
101.Fa offset +
102.Fa len
103is greater than the maximum file size.
104.It Bq Er EINTR
105A signal was caught during execution.
106.It Bq Er EINVAL
107The
108.Fa len
109argument was less than or equal to zero or the
110.Fa offset
111argument was less than zero.
112.It Bq Er EIO
113An I/O error occurred while reading from or writing to a file system.
114.It Bq Er ENODEV
115The
116.Fa fd
117argument does not refer to a regular file.
118.It Bq Er ENOSPC
119There is insufficient free space remaining on the file system storage
120media.
121.It Bq Er ESPIPE
122The
123.Fa fd
124argument is associated with a pipe or FIFO.
125.El
126.Sh SEE ALSO
127.Xr creat 2 ,
128.Xr ftruncate 2 ,
129.Xr open 2 ,
130.Xr unlink 2
131.Sh STANDARDS
132The
133.Fn posix_fallocate
134system call conforms to
135.St -p1003.1-2004 .
136.Sh HISTORY
137The
138.Fn posix_fallocate
139function appeared in
140.Fx 9.0 .
141.Sh AUTHORS
142.Fn posix_fallocate
143and this manual page were initially written by
144.An Matthew Fleming Aq mdf@FreeBSD.org .