TStream.Seek(Int64) problem in Delphi XE2

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TStream.Seek(Int64) problem in Delphi XE2

I've just discovered a condition in which I'm sending a INT64 value to a variable of type TStream, but it seems to use a 32-bit version of the function?

Specifically, When I use TStream.Seek(MyInt64, soFromBeginning) it seems to be calling the 32-bit version of the function and "eff'ing" up the seek when the value is over 32-bit.  I've swapped it to use the TStream.Position property and it seems to use the 64-bit correctly.

Any idea why?

Stack Trace URL added for more documentation.

== System.Classes ==
== START CUT ==
function TStream.Seek(const Offset: Int64; Origin: TSeekOrigin): Int64;
begin
{ Default implementation of 64 bit seek is to deflect to existing 32 bit seek.
  Descendents that override 64 bit seek must not call this default implementation. }
  if (Offset < Low(Longint)) or (Offset > High(Longint)) then
    raise ERangeError.CreateRes(@SRangeError);
  Result := Seek(Longint(Offset), Ord(Origin));
end;
== END CUT==
http://stackoverflow.com/questions/3882212/tstream-position-compared-to-tstream-seek

Comments

  1. mezenFebruary 26, 2014 at 11:05 PM

    Because of Longint(Offset). Longint is a signed 32bit Integer -> just like Integer.

    ReplyDelete
  2. Vin ColginFebruary 26, 2014 at 11:09 PM

    Yes, that is true. But there is an overloaded version that is int64. But the code from the sources show it restraining the number to int32 values. That's weird right?

    ReplyDelete
  3. Sergey KasandrovFebruary 27, 2014 at 5:01 AM

    Use TStream.Seek(MyInt64, soBeginning) for 64-bit Seek overload; soFromBeginning calls 32-bit Seek.

    ReplyDelete

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