1 /* Write block to given position in file without changing file pointer.
3 Copyright (C) 1997, 1998, 1999, 2002 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 <http://www.gnu.org/licenses/>. */
30 pwrite (int fd, const void *buf, size_t nbyte, off_t offset)
38 return pwrite (fd, buf, nbyte, offset);
43 # define __libc_lseek(f,o,w) lseek (f, o, w)
44 # define __set_errno(Val) errno = (Val)
45 # define __libc_write(f,b,n) write (f, b, n)
47 /* Note: This implementation of pwrite is not multithread-safe. */
50 pwrite (int fd, const void *buf, size_t nbyte, off_t offset)
52 /* Since we must not change the file pointer preserve the value so that
53 we can restore it later. */
56 off_t old_offset = __libc_lseek (fd, 0, SEEK_CUR);
57 if (old_offset == (off_t) -1)
60 /* Set to wanted position. */
61 if (__libc_lseek (fd, offset, SEEK_SET) == (off_t) -1)
64 /* Write out the data. */
65 result = __libc_write (fd, buf, nbyte);
67 /* Now we have to restore the position. If this fails we have to
68 return this as an error. But if the writing also failed we
71 if (__libc_lseek (fd, old_offset, SEEK_SET) == (off_t) -1)
74 __set_errno (save_errno);
77 __set_errno (save_errno);