1 /* fseeko.c -- an implementation of fseek() with an off_t argument.
2 Copyright (C) 2003, Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details. */
13 #include <sys/cdefs.h>
14 __RCSID("$NetBSD: fseeko.c,v 1.2 2016/05/17 14:00:09 christos Exp $");
15
16 #ifdef HAVE_CONFIG_H
17 #include "config.h"
18 #endif
19
20 #include <stdio.h>
21 #include <sys/types.h>
22
23 #ifdef HAVE_LIMITS_H
24 #include <limits.h>
25 #endif
26 #ifndef LONG_MAX
27 #define LONG_MAX ((long) ((unsigned long) ~0 >> 1))
28 #endif
29 #ifndef LONG_MIN
30 #define LONG_MIN (-1 - LONG_MAX)
31 #endif
32
33 /*
34 * A replacement/substitute for fseeko, for hosts that don't have it.
35 */
36
37 int
fseeko(FILE * stream,off_t offset,int whence)38 fseeko (FILE *stream, off_t offset, int whence)
39 {
40 while (offset != (long) offset)
41 {
42 long pos = (offset < 0) ? LONG_MIN : LONG_MAX;
43
44 if (fseek (stream, pos, whence) != 0)
45 return -1;
46 offset -= pos;
47 whence = SEEK_CUR;
48 }
49 return fseek (stream, (long) offset, whence);
50 }
51