On Tue, 6 Nov 2012, Andrew wrote:
On 12-11-06 02:50 AM, [email protected] wrote:
Since you can only read 2GB (Count is a longint) in a single read
operation, it makes no sense to return a 64-bit result.
Note that the operating system only allows 2Gb reads anyway, even on
64-bit
systems.
Hi Michael,
Thanks but that's not the problem. I can't even write 2bytes to a 2GB
memory/file stream.
See: http://bugs.freepascal.org/view.php?id=23284 for attached test case
shows simple math exactly like read/write in streams
This is another glitch that I must overcome. My sync app can't handle zip
files >=~2GB
The problem is with overflow. FPC raises an exception (as it should).
I realize this is going to affect a couple base classes too.
All you demonstrate is that it is possible to create overflows.
There is nothing wrong with the base classes. They work perfectly.
I've read/written 4Gb files. Probably you do something with the
result which is overflowing your variables.
Michael.
See the below program.
It writes 4Gb to disk and writes the resulting number of bytes,
which is larger than integer, but which I store in an Int64.
When I run the program:
araminta: >./testw
Wrote 4294968320 bytes
As expected. With Range checking.
-----------------------------------------------------------------------
{$mode objfpc}{$h+}
program testw;
uses classes;
var
F : TFileStream;
// 4 Mb buffer.
Buf : Array[0..4*1024*1024] of byte;
I : Integer;
S : Int64;
begin
FillChar(Buf,Sizeof(Buf),' ');
f:=TFileStream.Create('test.dat',fmCreate);
try
For I:=1 to 1024 do
S:=S+F.Write(Buf,SizeOf(Buf));
Finally
F.Free;
end;
Writeln('Wrote ',S,' bytes');
end.
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