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ExamineLibrary : Invalid Access Memory
Posted: Tue Apr 11, 2006 9:12 am
by Flype
On WinXP, if i try to parse the functions of this dll, PB crash...
Code: Select all
If OpenLibrary(0, "msw3prt.dll")
If ExamineLibraryFunctions(0)
While NextLibraryFunction()
func$ = LibraryFunctionName() : Debug func$
Wend
EndIf
CloseLibrary(0)
EndIf
Posted: Tue Apr 11, 2006 9:23 am
by walker
Strange... crashes here on Closelibrary()..
but with a delay(1) before the CloseLibrary() all runs well
Code: Select all
If OpenLibrary(0, "msw3prt.dll")
If ExamineLibraryFunctions(0)
While NextLibraryFunction()
func$ = LibraryFunctionName() : Debug func$
Wend
EndIf
Delay(1)
CloseLibrary(0)
EndIf
Btw.:
@Fred: IMHO should the
CloseLibrary() command contain the number of the opened Library like
CloseLibrary(0) to be conform with all other PB-Commands..
Posted: Tue Apr 11, 2006 9:41 am
by Flype
just tried with PB3.94 - exactly the same behaviour.
maybe it's the dll itself that is strange (?)
@walker
agree, i was also thinking of this.
NextLibraryFunction(#library)
LibraryFunctionName(#library)
LibraryFunctionAddress(#library)
to be more consistent and safer...
Posted: Tue Apr 11, 2006 5:28 pm
by netmaestro
From the help file:
Syntax
CloseLibrary(#Library)
As the NextLibraryFunction(), LibraryFunctionName() and LibraryFunctionAddress() are all subordinate to the ExamineLibraryFunctions(#Library) command, repeating it for them would be redundant typing. The other Examine... command that takes a parameter also treats its subordinate commands this way - ExamineDirectory(#Directory)... followed by NextDirectoryEntry() etc.
Posted: Tue Apr 11, 2006 5:50 pm
by Flype
not really netmaestro.
now NextDirectoryEntry() is NextDirectoryEntry(#Directory)
and when ExamineLibraryFunctions() is called from multiples threads what's happened ? There might be a conflict. But those are really rare cases... I never be myself in such case...
Posted: Tue Apr 11, 2006 5:57 pm
by Fred
This function rely on very lowlevel access, so if there is something corrupted in the dll, the function will probably crash
.
Posted: Tue Apr 11, 2006 6:14 pm
by Flype
does it crash for you to with this windows built-in dll ?
is it normal that the OnErrorGosub doesn't catch it ?
Code: Select all
Procedure ErrorHandler()
MessageRequester("Crash","Crash")
EndProcedure
OnErrorGosub(@ErrorHandler())
If OpenLibrary(0, "msw3prt.dll")
If ExamineLibraryFunctions(0)
While NextLibraryFunction()
func$ = LibraryFunctionName() : Debug func$
Wend
EndIf
CloseLibrary(0)
EndIf
Posted: Fri Sep 12, 2008 12:19 am
by Fred
I looked closely to this problem and it seems to be the fault of the DLL as even an API only PB code crash:
Code: Select all
a = LoadLibrary_("msw3prt.dll")
If a
FreeLibrary_(a)
MessageBox_(0, "ok", "", 0)
EndIf
It crashes after the display of the MessageBox(). To be sure it wasn't a PureBasic problem, i tested it in VisualC++ 2005 with the following code, and it keeps crashing.
Code: Select all
#include <Windows.h>
int main(int argc, TCHAR* argv[])
{
HMODULE a = LoadLibrary("msw3prt.dll");
if (a)
{
FreeLibrary(a);
MessageBox(NULL, "ok", "", MB_ICONINFORMATION);
}
return 0;
}
My guess is the library has something wrong in its freeing code, may be it should be reported to Microsoft, as it's very unlikely to be a coding fault here
.
Posted: Sun Nov 02, 2008 1:11 pm
by Flype
hi fred, yes you are right.
it works as i said before with a Delay(1) before freeing the library (initializations delay ?), so in a real use there's no problem.
win32 code, tested ok.
Code: Select all
#include "Windows.h"
int _tmain(int argc, TCHAR* argv[])
{
HMODULE a = LoadLibrary("msw3prt.dll");
if (a)
{
Sleep(1);
FreeLibrary(a);
MessageBox(NULL, "ok", "", MB_ICONINFORMATION);
}
return 0;
}
api pb code, tested ok.
Code: Select all
a = LoadLibrary_("msw3prt.dll")
If a
Sleep_(1)
FreeLibrary_(a)
MessageBox_(0, "ok", "", 0)
EndIf
pb only, tested ok.
Code: Select all
If OpenLibrary(0,"msw3prt.dll")
Delay(1)
CloseLibrary(0)
MessageRequester("", "ok")
EndIf
So, no purebasic bug here.