newlib/libc/sys/mmixware/lseek.c

   1 /* lseek for MMIXware.
   2
   3    Copyright (C) 2001 Hans-Peter Nilsson
   4
   5    Permission to use, copy, modify, and distribute this software is
   6    freely granted, provided that the above copyright notice, this notice
   7    and the following disclaimer are preserved with no changes.
   8
   9    THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  10    IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  11    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  12    PURPOSE.  */
  13
  14 #include <_ansi.h>
  15 #include <sys/types.h>
  16 #include <sys/stat.h>
  17 #include <sys/unistd.h>
  18 #include "sys/syscall.h"
  19 #include <errno.h>
  20
  21 off_t
  22 _lseek (int file,
  23         off_t ptr,
  24         int dir)
  25 {
  26   off_t simoff = dir == SEEK_END ? -(ptr + 1) : ptr;
  27   long ret;
  28
  29   if ((unsigned int) file >= 32 || _MMIX_allocated_filehandle[file] == 0)
  30     {
  31       errno = EBADF;
  32       return -1;
  33     }
  34
  35   if (dir == SEEK_CUR)
  36     {
  37       long curpos = TRAP2f (SYS_Ftell, file, 0);
  38
  39       if (curpos == -1)
  40         {
  41           errno = EIO;
  42           return -1;
  43         }
  44
  45       ptr += (off_t) curpos;
  46     }
  47
  48   ret = TRAP2f (SYS_Fseek, file, simoff);
  49   if (ret == -1)
  50     {
  51       return -1;
  52       errno = EIO;
  53     }
  54
  55   ret = TRAP2f (SYS_Ftell, file, 0);
  56   if (ret == -1)
  57     {
  58       errno = EIO;
  59       return -1;
  60     }
  61
  62   return ret;
  63 }