external/gpl2/xcvs/dist/lib/fseeko.c

   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
  14 #ifdef HAVE_CONFIG_H
  15 #include "config.h"
  16 #endif
  17
  18 #include <stdio.h>
  19 #include <sys/types.h>
  20
  21 #ifdef HAVE_LIMITS_H
  22 #include <limits.h>
  23 #endif
  24 #ifndef LONG_MAX
  25 #define LONG_MAX ((long) ((unsigned long) ~0 >> 1))
  26 #endif
  27 #ifndef LONG_MIN
  28 #define LONG_MIN (-1 - LONG_MAX)
  29 #endif
  30
  31 /*
  32  * A replacement/substitute for fseeko, for hosts that don't have it.
  33  */
  34
  35 int
  36 fseeko (FILE *stream, off_t offset, int whence)
  37 {
  38     while (offset != (long) offset)
  39     {
  40         long pos = (offset < 0) ? LONG_MIN : LONG_MAX;
  41
  42         if (fseek (stream, pos, whence) != 0)
  43             return -1;
  44         offset -= pos;
  45         whence = SEEK_CUR;
  46     }
  47     return fseek (stream, (long) offset, whence);
  48 }