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/* Copyright (C) 2000-2014 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#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, __off_t len)
{
struct stat64 st;
struct statfs f;
/* `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 (__fxstat64 (_STAT_VER, fd, &st) != 0)
return EBADF;
if (S_ISFIFO (st.st_mode))
return ESPIPE;
if (! S_ISREG (st.st_mode))
return ENODEV;
if (len == 0)
{
if (st.st_size < offset)
{
int ret = __ftruncate (fd, offset);
if (ret != 0)
ret = errno;
return ret;
}
return 0;
}
/* 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;
/* Try to play safe. */
if (f.f_bsize == 0)
f.f_bsize = 512;
/* Write something to every block. */
for (offset += (len - 1) % f.f_bsize; len > 0; offset += f.f_bsize)
{
len -= f.f_bsize;
if (offset < st.st_size)
{
unsigned char c;
ssize_t rsize = __pread (fd, &c, 1, offset);
if (rsize < 0)
return errno;
/* If there is a non-zero byte, the block must have been
allocated already. */
else if (rsize == 1 && c != 0)
continue;
}
if (__pwrite (fd, "", 1, offset) != 1)
return errno;
}
return 0;
}
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