man*/: ffix (un-bracket tables)

[thirdparty/man-pages.git] / man3 / posix_fallocate.3

'\" t
.\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH posix_fallocate 3 (date) "Linux man-pages (unreleased)"
.SH NAME
posix_fallocate \- allocate file space
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <fcntl.h>
.PP
.BI "int posix_fallocate(int " fd ", off_t " offset ", off_t " len );
.fi
.PP
.ad l
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR posix_fallocate ():
.nf
    _POSIX_C_SOURCE >= 200112L
.fi
.SH DESCRIPTION
The function
.BR posix_fallocate ()
ensures that disk space is allocated for the file referred to by the
file descriptor
.I fd
for the bytes in the range starting at
.I offset
and continuing for
.I len
bytes.
After a successful call to
.BR posix_fallocate (),
subsequent writes to bytes in the specified range are
guaranteed not to fail because of lack of disk space.
.PP
If the size of the file is less than
.IR offset + len ,
then the file is increased to this size;
otherwise the file size is left unchanged.
.SH RETURN VALUE
.BR posix_fallocate ()
returns zero on success, or an error number on failure.
Note that
.I errno
is not set.
.SH ERRORS
.TP
.B EBADF
.I fd
is not a valid file descriptor, or is not opened for writing.
.TP
.B EFBIG
.I offset+len
exceeds the maximum file size.
.TP
.B EINTR
A signal was caught during execution.
.TP
.B EINVAL
.I offset
was less than 0, or
.I len
was less than or equal to 0, or the underlying filesystem does not
support the operation.
.TP
.B ENODEV
.I fd
does not refer to a regular file.
.TP
.B ENOSPC
There is not enough space left on the device containing the file
referred to by
.IR fd .
.TP
.B EOPNOTSUPP
The filesystem containing the file referred to by
.I fd
does not support this operation.
This error code can be returned by C libraries that don't perform the
emulation shown in NOTES, such as musl libc.
.TP
.B ESPIPE
.I fd
refers to a pipe.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lbx
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR posix_fallocate ()
T}	Thread safety	T{
.na
.nh
MT-Safe (but see NOTES)
T}
.TE
.sp 1
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
glibc 2.1.94.
POSIX.1-2001
.PP