Re: [ANNOUNCEMENT] TEST RELEASE: Cygwin 1.7.33-0.1

[Christian Franke <Christian dot Franke at t-online dot de>]

Corinna Vinschen wrote:
> [Christian, please chime in]
>
> On Oct 24 20:41, Denis Excoffier wrote:
> > >  From Cygwin's POV {/usr}/bin is a system dir.  For security reasons it
> > > makes sense that the system DLLs in /bin cannot be overridden, unless
> > > it's an installation issue which should be covered by looking into the
> > > application installation dir first.
> > Instead of adding the lookup of /usr/bin before the PATH, you could add
> > it afterwards?
> No.  You don't expect this kind of flexibility in the Win32 API, do you?

[The *LIBPATH variables from MS OS/2 (1987) never made it to Win API :-]


> The way it works is, there's a call SetDllDirectory which replaces the "."
> in the DLL search path with the directory given as argument.  The search
> order is always this:
>
>    application dir
>    dir given in SetDllDirecory (Cygwin's bin)
>    system dirs
>    $PATH
>
> > Or do you mean that my use is bad practice for security
> > reasons? That there might be some unexpected DLL somewhere in the PATH?
> > IIRC, in linux/solaris, LD_LIBRARY_PATH is not honored when you are root,
> > not otherwise.
> Not quite.  LD_LIBRARY_PATH is only ignored if the excutable is a
> suid/sgid executable.  Unfortunately we don't have LD_LIBRARY_PATH at
> all when running execve (but we have in dlopen).
>
> > > Having said that, moving your DLLs into the application dir is really
> > > not an option?
> > Oh yes, i use it all the time. It is the job of 'make install' to also
> > install the appropriate DLLs. The point here is for 'make check'.
> Yeah.
>
> Sigh.
>
> I don't like the idea either that this simple change breaks existing
> scenarios.  I'm inclined to revert this change.
>
> Christian, would you mind terribly to re-add the tweak to postfix
> to set $PATH?

No problem.

Another possible solution:
Check for e.g. CYGWIN_DLLPATH environment variable before calling 
SetDllDirectory().

If unset or empty, call SetDllDirectory("X:\path_to_cygwin\bin");
else if set to ".", do nothing.
else call SetDllDirectory(CYGWIN_DLLPATH);

The above 'make check' should then work again as 'CYGWIN_DLLPATH=. make 
check'.

Possible enhancement: If AddDllDirectory() is available (>= Win8), 
accept a real search path in CYGWIN_DLLPATH.

Christian


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