[osg-submissions] Plugin DLL search order fix for Win32

[Jean-Sébastien Guay]

Hello Robert,

As discussed yesterday on the osg-users list, I have altered  
src/osgDB/FileUtils.cpp to implement the official Windows DLL search  
order as described on the page  
http://msdn2.microsoft.com/en-us/library/ms682586.aspx . As mentioned,  
the search order is now:
     1. The directory from which the application loaded.
     2. The system directory. (C:\Windows\System32 by default, gotten using the
        GetSystemDirectory function)
     3. The 16-bit system directory. (C:\Windows\System by default, gotten by
        adding "\System" to the path gotten in the next step...)
     4. The Windows directory. (C:\Windows by default, gotten using the
        GetWindowsDirectory function)
     5. The current directory. (".")
     6. The directories that are listed in the PATH environment variable. (as
        before)

The first four directories are obtained using Win32 API calls, so they  
should work correctly even on non-standard Windows installs.

The changes are well commented and should be clear, even to someone  
not familiar with the Win32 API.

I have tested in a few scenarios and it works as expected. Serge Lages  
has also tested the changes and confirmed they worked as described. I  
have not had any other reports though (positive or negative).

I also fixed the issue with a trailing semicolon on the PATH adding an  
empty string to the end of the search paths, as this was an  
inconsistent side effect rather than a desirable effect. This change  
will take effect on other platforms as well, but since it tests for an  
empty string in the last item added to the search paths, it should  
have no adverse effect.

Attached is the modified src/osgDB/FileUtils.cpp , zipped up just to be sure.

Thanks,

J-S
-- 
______________________________________________________
Jean-Sebastien Guay     jean-sebastien.guay at polymtl.ca
                         http://whitestar02.webhop.org/

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