Following Setup:
Ubuntu 8.10 x64
FPC 2.2.3 (latest and greatest)
Lazarus (Latest and greatest)

I'm seeing an anomaly with reading/writing to an Array[THandle] of Pointers.

TMyStruct=record
  Index:integer;
end;
PMyStruct=^TMyStruct;
TMyList = Array[THandle] of PMyStruct;
If I declare a localized variable
procedure Test();
var
  MyTest:TMyList;
  hThread:THandle;
begin
  hThread:=getCurrentThreadID;
  if (MyTest[hThread])=nil then begin // <---- CRASH HERE EXTERNAL SIGBUS
  end;
end;

This should not crash here. It should have been nil.

Any work being done in this area or should I report another bug?

thandle is a longint on fpc/linux, so you're declaring an array of 2^32 * 8 bytes (32GB) on the stack here. That may be valid on linux/ x86_64, but it also may not be (I don't know what Linux' stack limits are). It's definitely not something that would seem advisable to me.

I'm surprised this is supposed work with Delphi since thandle is a dword for Windows, so you're still ending up with an array of 2^32 * 4 bytes (16 GB) on Win32. There's simply no way to map that much memory at once in 32 bit process' address space.

Jonas

I'm surprised it crashes there. A THandle is IIRC a Cardinal on unix, so by defining a variable MyTest:TMyList, you allocate 4GB * SizeOf(TMyStruct) = 16GB on your stack. Usually a process doens't have that much space and I wonder if you wanted this.

(You may want to look at the lcl Maps unit)

Marc

Hehehehe....

I know. I didn't realize that the map was that large. It's for Indexing memory objects to threads. I did something similar under Delphi but now recall limiting the size from [-1..99999] or something like that. But that's in a 32 bit OS. Doing it that way isn't going to work.

I've got another way already. I just didn't relate the size of the actual structure.