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/* Copyright (C) 2000 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/statfs.h>
/* Reserve storage for the data of the file associated with FD. */
int
posix_fallocate (int fd, __off_t offset, size_t len)
{
struct stat st;
struct statfs f;
size_t step;
/* `off_t´ is a signed type. Therefore we can determine whether
OFFSET + LEN is too large if it is a negative value. */
if (offset < 0 || len == 0)
return EINVAL;
if (offset + len < 0)
return EFBIG;
/* First thing we have to make sure is that this is really a regular
file. */
if (__fxstat (_STAT_VER, fd, &st) != 0)
return EBADF;
if (S_ISFIFO (st.st_mode))
return ESPIPE;
if (! S_ISREG (st.st_mode))
return ENODEV;
/* We have to know the block size of the filesystem to get at least some
sort of performance. */
if (__fstatfs (fd, &f) != 0)
return errno;
/* Align OFFSET to block size and adjust LEN. */
step = (offset + f.f_bsize - 1) % ~f.f_bsize;
offset += step;
/* Write something to every block. */
while (len > step)
{
len -= step;
if (pwrite (fd, "", 1, offset) != 1)
return errno;
offset += step;
}
return 0;
}
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