1 /* Write block to given position in file without changing file pointer.
3 Copyright (C) 1997-1999, 2002, 2011-2019 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
7 This program is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <https://www.gnu.org/licenses/>. */
27 #define __libc_lseek(f,o,w) lseek (f, o, w)
28 #define __set_errno(Val) errno = (Val)
29 #define __libc_write(f,b,n) write (f, b, n)
31 /* Note: This implementation of pwrite is not multithread-safe. */
34 pwrite (int fd
, const void *buf
, size_t nbyte
, off_t offset
)
36 /* Since we must not change the file pointer preserve the value so that
37 we can restore it later. */
40 off_t old_offset
= __libc_lseek (fd
, 0, SEEK_CUR
);
41 if (old_offset
== (off_t
) -1)
44 /* Set to wanted position. */
45 if (__libc_lseek (fd
, offset
, SEEK_SET
) == (off_t
) -1)
48 /* Write out the data. */
49 result
= __libc_write (fd
, buf
, nbyte
);
51 /* Now we have to restore the position. If this fails we have to
52 return this as an error. But if the writing also failed we
55 if (__libc_lseek (fd
, old_offset
, SEEK_SET
) == (off_t
) -1)
58 __set_errno (save_errno
);
61 __set_errno (save_errno
);