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 261280 2014-01-30 05:35:12Z pluknet $
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 -1 on failure, and sets
87.Va errno
88to indicate the error.
89.Sh ERRORS
90Possible failure conditions:
91.Bl -tag -width Er
92.It Bq Er EBADF
93The
94.Fa fd
95argument is not a valid file descriptor.
96.It Bq Er EBADF
97The
98.Fa fd
99argument references a file that was opened without write permission.
100.It Bq Er EFBIG
101The value of
102.Fa offset +
103.Fa len
104is greater than the maximum file size.
105.It Bq Er EINTR
106A signal was caught during execution.
107.It Bq Er EINVAL
108The
109.Fa len
110argument was less than or equal to zero or the
111.Fa offset
112argument was less than zero.
113.It Bq Er EIO
114An I/O error occurred while reading from or writing to a file system.
115.It Bq Er ENODEV
116The
117.Fa fd
118argument does not refer to a regular file.
119.It Bq Er ENOSPC
120There is insufficient free space remaining on the file system storage
121media.
122.It Bq Er ESPIPE
123The
124.Fa fd
125argument is associated with a pipe or FIFO.
126.El
127.Sh SEE ALSO
128.Xr creat 2 ,
129.Xr ftruncate 2 ,
130.Xr open 2 ,
131.Xr unlink 2
132.Sh STANDARDS
133The
134.Fn posix_fallocate
135system call conforms to
136.St -p1003.1-2004 .
137.Sh HISTORY
138The
139.Fn posix_fallocate
140function appeared in
141.Fx 9.0 .
142.Sh AUTHORS
143.Fn posix_fallocate
144and this manual page were initially written by
145.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 261280 2014-01-30 05:35:12Z pluknet $
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 -1 on failure, and sets
87.Va errno
88to indicate the error.
89.Sh ERRORS
90Possible failure conditions:
91.Bl -tag -width Er
92.It Bq Er EBADF
93The
94.Fa fd
95argument is not a valid file descriptor.
96.It Bq Er EBADF
97The
98.Fa fd
99argument references a file that was opened without write permission.
100.It Bq Er EFBIG
101The value of
102.Fa offset +
103.Fa len
104is greater than the maximum file size.
105.It Bq Er EINTR
106A signal was caught during execution.
107.It Bq Er EINVAL
108The
109.Fa len
110argument was less than or equal to zero or the
111.Fa offset
112argument was less than zero.
113.It Bq Er EIO
114An I/O error occurred while reading from or writing to a file system.
115.It Bq Er ENODEV
116The
117.Fa fd
118argument does not refer to a regular file.
119.It Bq Er ENOSPC
120There is insufficient free space remaining on the file system storage
121media.
122.It Bq Er ESPIPE
123The
124.Fa fd
125argument is associated with a pipe or FIFO.
126.El
127.Sh SEE ALSO
128.Xr creat 2 ,
129.Xr ftruncate 2 ,
130.Xr open 2 ,
131.Xr unlink 2
132.Sh STANDARDS
133The
134.Fn posix_fallocate
135system call conforms to
136.St -p1003.1-2004 .
137.Sh HISTORY
138The
139.Fn posix_fallocate
140function appeared in
141.Fx 9.0 .
142.Sh AUTHORS
143.Fn posix_fallocate
144and this manual page were initially written by
145.An Matthew Fleming Aq mdf@FreeBSD.org .