[Lazarus] Strange access violation

[Mattias Gaertner]

 Luca Olivetti <luca at wetron.es> hat am 4. Mai 2011 um 13:44 geschrieben:

 > Lately I'm getting a bunch of those. I thought it was because I was
 > using an old version of lazarus, but now I upgraded to 0.9.30 (self
 > compiled from http:://svn.freepascal.org/svn/lazarus/tags_lazarus_0_9_30
 > with fpc 2.4.2 under win32) and I got another strange one.
 >
 > The exception, according to the stack trace, is in line 27 of monitor.inc:
 >
 > function TMonitor.GetInfo(out Info: TMonitorInfo): Boolean;
 > begin
 >    Info.cbSize := SizeOf(TMonitorInfo);
 >    Result := GetMonitorInfo(Handle, @Info); <<--here
 > end;
 >
 >
 > Called from here:
 >
 > function TMonitor.GetBoundsRect: TRect;
 > var
 >    Info: TMonitorInfo;
 > begin
 >    if GetInfo(Info) then <<--here
 >      Result := Info.rcMonitor
 >    else
 >      Result := Rect(0, 0, 0, 0);
 > end;
 >
 > So I don't understand how an access violation is possible (unless
 > windows doesn't look at the cbSize field and tries to access past its
 > size). I suspect that the PC where the program is running has some
 > problem (maybe a virus?), since I got another access violation on the
 > same PC (actually I don't know, I didn't manage to get a stack trace,
 > the main form just "vanished" after pressing a button, a different one
 > than this time, and that prompted me to upgrade lazarus) but I'm worried.
 >
 > Of course it isn't reproducible (it happened only once, inside a
 > TOpendialog.Execute, I tried many many times after the access violation
 > with no problem).
 >
 > Any idea?
 Maybe a heap/stack corruption. Compile with many checks: -ghtl -Criot -Sa
 The problem is probably in some package you installed.

 Mattias
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