On Jan 23 22:12, Richard Levitte wrote: > In message <20160123210116.gb13...@calimero.vinschen.de> on Sat, 23 Jan 2016 > 22:01:16 +0100, Corinna Vinschen <vinsc...@redhat.com> said: > > vinschen> On Jan 23 21:35, Kurt Roeckx wrote: > vinschen> > On Sat, Jan 23, 2016 at 09:27:58PM +0100, Corinna Vinschen wrote: > vinschen> > > > vinschen> > > Last but not least, we have another problem with enginesdir. > To allow a > vinschen> > > rolling release cycle, we have to support multiple versions of > openssl > vinschen> > > in parallel. The problem here is that the enginesdir needs to > be > vinschen> > > versioned to allow per-openssl version engines. The build > scripts don't > vinschen> > > allow for this. Right now we're using a patch as the below one > to tweak > vinschen> > > the configury to allow specifying the engines dir during build > time. > vinschen> > > Would it hurt terribly to include something like the below > patch? > vinschen> > > vinschen> > In general, I would like to have a directory for the engines that > vinschen> > relates to OSSL_DYNAMIC_OLDEST. > vinschen> > vinschen> That probably won't work for Cygwin. The engines are linked > against the > vinschen> versioned DLLs of the OpenSSL version they have been built for, > Even > vinschen> assuming binary compatibility, an engine linked against openssl-1.0 > will > vinschen> pull in openssl-1.0 DLLs, even when loaded from openssl-1.1. We > have to > vinschen> keep the engines separate. > > This is interesting, actually. OSSL_DYNAMIC_OLDEST has some design > around it that's meant to permit EXACTLY that kind of mixture. It's > in the macro IMPLEMENT_DYNAMIC_BIND_FN. However, it's possible it's > not doing enough, and figuring out what else it needs to do is a > venture I think is worth spending some time on.
The problem here is Windows and how DLL dependencies are resolved. We're using versioned DLLs, e.g. /usr/bin/cygcrypto-0.9.8.dll /usr/bin/cygcrypto-1.0.0.dll /usr/bin/cygcrypto-1.1.dll When building engines, the engines are shared libs linking against the crypto DLL. This creates a hard dependency to the DLL the engine has been linked against. So, consider using an application linked against cygcrypto-1.1.dll. It loads an engine built with and thus linked against cygcrypto-1.0.0.dll. While the application will use functions from cygcrypto-1.1.dll, the engine will use functions from cygcrypto-1.0.0.dll. Hilarity ensues. Unless cygcrypto-1.0.0.dll has been deprecated and removed. In which case loading the engine fails. To decouple an engine from a DLL version, what we would have to do is to change the engines not to link against libcrypto, but rather to load *all* functions dynamically at runtime (dlload/dlsym(*)). Only this would allow to decouple the engines from a specific versioned DLL. Corinna (*) On Windows (but NOT Cygwin): LoadLibrary/GetProcAddress.
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