[fpc-devel] Memory Streams unable to handle reads past 2GB

[Andrew]

On 12-11-06 05:07 PM, Michael Van Canneyt wrote:

Please re-open the issue and I will post an updated program that fails 
EVERY TIME.

Or just use the attached Widen.lpr... :-)
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program Widen;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes,SysUtils;

  function Test_2(Count:LongInt; Factor:Byte):LongInt;
  var
    FSize:Int64;
    FPosition:Int64;
  begin
    FPosition:=0;
    FSize:=(1024*1024*1024)*Factor;
    Result:=FSize-FPosition;
  end;

  function Test_1(Count:LongInt; Factor:Byte):Int64;
  var
    FSize:Int64;
    FPosition:Int64;
  begin
    FPosition:=0;
    FSize:=(1024*1024*1024)*Factor;
    Result:=FSize-FPosition;
  end;

  function Test_3(Count:LongInt; Factor:Byte):LongInt;
  const
    MyBuffer:Array[0..1] of byte=(0,0);
  var
    FSize:Int64;
    FPosition:Int64;
    FS:TMemoryStream;
    FWrote:LongInt;
    FRead:LongInt;
  begin
    FS:=TMemoryStream.Create();
    Try
      FPosition:=0;
      FSize:=(1024*1024*1024)*Factor;
      While FPosition<FSize do begin
        FWrote:=FS.Write(MyBuffer[0],2);
        inc(FPosition,2);
      end;
      // Stream is filled
      FS.Position:=0;
      MyBuffer[0]:=1;
      MyBuffer[1]:=2;
      FRead:=FS.Read(MyBuffer[0],2);
      If (FRead<>2) or (MyBuffer[0]<>0) or (MyBuffer[1]<>0) then
        raise Exception.Create('Test_3 Failed');
    Finally
      FS.Free();
    end;

  end;

begin
  Test_1(1024,1); //OK
  Test_1(1024,2); //OK
  Test_2(1024,1); //OK
  //Test_2(1024,2); //Will always fail with range checking on
  Test_3(1028,2); //will always fail with range checking on
end.