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