otherlibs/win32unix/lseek.c

   1 /***********************************************************************/
   2 /*                                                                     */
   3 /*                           Objective Caml                            */
   4 /*                                                                     */
   5 /*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
   6 /*                                                                     */
   7 /*  Copyright 1996 Institut National de Recherche en Informatique et   */
   8 /*  en Automatique.  All rights reserved.  This file is distributed    */
   9 /*  under the terms of the GNU Library General Public License, with    */
  10 /*  the special exception on linking described in file ../../LICENSE.  */
  11 /*                                                                     */
  12 /***********************************************************************/
  13
  14 /* $Id$ */
  15
  16 #include <mlvalues.h>
  17 #include <alloc.h>
  18 #include "unixsupport.h"
  19
  20 #ifdef HAS_UNISTD
  21 #include <unistd.h>
  22 #else
  23 #define SEEK_SET 0
  24 #define SEEK_CUR 1
  25 #define SEEK_END 2
  26 #endif
  27
  28 static DWORD seek_command_table[] = {
  29   FILE_BEGIN, FILE_CURRENT, FILE_END
  30 };
  31
  32 #ifndef INVALID_SET_FILE_POINTER
  33 #define INVALID_SET_FILE_POINTER (-1)
  34 #endif
  35
  36 static __int64 caml_set_file_pointer(HANDLE h, __int64 dist, DWORD mode)
  37 {
  38   LARGE_INTEGER i;
  39   DWORD err;
  40
  41   i.QuadPart = dist;
  42   i.LowPart = SetFilePointer(h, i.LowPart, &i.HighPart, mode);
  43   if (i.LowPart == INVALID_SET_FILE_POINTER) {
  44     err = GetLastError();
  45     if (err != NO_ERROR) { win32_maperr(err); uerror("lseek", Nothing); }
  46   }
  47   return i.QuadPart;
  48 }
  49
  50 CAMLprim value unix_lseek(value fd, value ofs, value cmd)
  51 {
  52   __int64 ret;
  53
  54   ret = caml_set_file_pointer(Handle_val(fd), Long_val(ofs),
  55                               seek_command_table[Int_val(cmd)]);
  56   if (ret > Max_long) {
  57     win32_maperr(ERROR_ARITHMETIC_OVERFLOW);
  58     uerror("lseek", Nothing);
  59   }
  60   return Val_long(ret);
  61 }
  62
  63 CAMLprim value unix_lseek_64(value fd, value ofs, value cmd)
  64 {
  65   __int64 ret;
  66
  67   ret = caml_set_file_pointer(Handle_val(fd), Int64_val(ofs),
  68                               seek_command_table[Int_val(cmd)]);
  69   return copy_int64(ret);
  70 }