newlib/libc/sys/rdos/lseek.c

   1 /*#######################################################################
   2 # RDOS operating system
   3 # Copyright (C) 1988-2006, Leif Ekblad
   4 #
   5 # This library is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU Lesser General Public License as published
   7 # by the Free Software Foundation; either version 2.1 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This library is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU Lesser General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU Lesser General Public
  16 # License along with this library; if not, write to the Free Software
  17 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18 #
  19 # The author of this program may be contacted at leif@rdos.net
  20 #
  21 # lseek.c
  22 # lseek function implementation
  23 #
  24 ##########################################################################*/
  25
  26 #include "config.h"
  27 #include <_ansi.h>
  28 #include <_syslist.h>
  29 #include <unistd.h>
  30 #include <errno.h>
  31 #include <rdos.h>
  32
  33 off_t lseek(int file, off_t pos, int whence)
  34 {
  35         off_t temp;
  36
  37         switch (whence)
  38         {
  39                 case SEEK_CUR:
  40                         temp = RdosGetFilePos(file);
  41                         temp += pos;
  42                         RdosSetFilePos(file, temp);
  43                         return temp;
  44
  45                 case SEEK_SET:
  46                         RdosSetFilePos(file, pos);
  47                         return pos;
  48
  49                 case SEEK_END:
  50                         temp = RdosGetFilePos(file);
  51                         temp += pos;
  52                         RdosSetFilePos(file, temp);
  53                         return temp;
  54
  55                 default:
  56                         errno = EINVAL;
  57                         return - 1;
  58         }
  59 }