[openssl-dev] Question about dynamically loadable engines on Cygwin / Mingw

[Richard Levitte]

Hi Corinna,

In message <20160215105045.GA7601 at calimero.vinschen.de> on Mon, 15 Feb 2016 11:50:45 +0100, Corinna Vinschen <vinschen at redhat.com> said:

vinschen> >   Cygwin: cygcapi.dll
vinschen> 
vinschen> I can't speak for Mingw, but on Cygwin the modules are called libFOO.so,
vinschen> e.g.
vinschen> 
vinschen>   /usr/lib/openssl-1.0.2/engines/libcapi.so

Really?  I don't understand how that can be.  The link_o.cygwin target
in Makefile.shared tells me a very different story, with these lines:

	SHLIB=cyg$(LIBNAME); \
	...
	SHLIB_SUFFIX=.dll; \

vinschen> I hope the changes to the build system will keep this intact.

May I ask why?  The only thing I can see that would depend on the name
of engines in practice is the DSO module (and that one has no support
for .dll files in a POSIX context).  I plan on fixing that one to
match changes I make.

(and, should it come to that, I can see the possibility of making
backward compatibility copies if someone needs it)

vinschen> > This is assuming, btw, that no one mixes the different Windows POSIX
vinschen> > layers on top of each other.  If such mixes are commonplace, it's
vinschen> > worth considering, of course...
vinschen> 
vinschen> No such mixing is possible due to dependency issues, nor is it
vinschen> supported.  You can try but it will not work as desired.  Ideally just
vinschen> handle Cygwin as a POSIX system with a few quirks (like having the DLLs
vinschen> in /usr/bin instead of /usr/lib), but otherwise disjunct from native
vinschen> Windows environments.  POSIX, not Windows.

Good.  Someone else told me "It would take a brave man to mix Cygwin
plugins (engines) with non-Cygwin host or vice versa"...  message
received, I don't need to worry about that.

Cheers,
Richard

-- 
Richard Levitte         levitte at openssl.org
OpenSSL Project         http://www.openssl.org/~levitte/