Hi, UFFI cannot do what you want. If I understand well, you have:
Pharo -> libA.dll -> libB.dll Pharo does a LoadLibrary(libA.dll), but has no control on how libA calls libB… and is not possible for us to influence it more than the predefined platform ways. One posible workaround (just possible, no idea if it will work) is to perform a load of libB before is required by libB. Then hopefully the loader will understand is same library and will answer same handler (but not sure, because if it discriminates by path… then you’re in the same position). Anyway, if you want to try it, it would be something like this: DynamicLoader loadLibrary: 'path/to/libB.dll’. DynamicLoader loadLibrary: 'path/to/libA.dll’. then you can try to execute functions of libA… cheers, Esteban > On 15 Mar 2017, at 14:32, Raffaello Giulietti > <raffaello.giulie...@lifeware.ch> wrote: > > On 2017-03-15 13:51, Ben Coman wrote: >> >> >> On Wed, Mar 15, 2017 at 4:42 PM, Raffaello Giulietti >> <raffaello.giulie...@lifeware.ch >> <mailto:raffaello.giulie...@lifeware.ch>> wrote: >> >> Hi Ben, >> >> my understanding is that SetDllDirectory only affects the search >> path of libraries that are loaded at *run-time* with LoadLibrary. >> >> What I'm asking for is a mechanism that works at *load-time*, when a >> library I'm accessing directly depends on another one which I'm not >> targeting directly. >> >> >> I don't quite follow. I'm not intimate with Windows dynamic loading, so >> these questions are an opportunity for me to learn... >> >> You can't mean when Pharo loads, because it wouldn't know of OTHER.DLL ? >> >> Do you mean that LoadLibrary is not called explicitly by YOUR.DLL before >> its uses the function from OTHER.DLL? >> > > During the build of YOUR.DLL, you can specify that it should depend on > OTHER.LIB (kind of binary which lists function headers and static data > declarations for OTHER.DLL). Linking resolution is then done at load-time of > YOUR.DLL, not by invoking LoadLibrary("OTHER.DLL"). > > When YOUR.DLL is loaded by UFFI at run-time (here by means of LoadLibrary(), > I guess), Windows (not the UFFI) also attempts to load OTHER.DLL because of > the linking information gathered during the build. Notice that the linking > information does *not* include a specific path for OTHER.DLL. > > (You don't have to mention standard *.LIBs like Kernel32.lib because they are > included by default. But of course, Windows knows where to find the > corresponding .dll.) > > OTHER.DLL is searched using the strategy described in the MSDN page you > mention. My expectation is/was that UFFI has/had an API for specifying the > search paths where to find OTHER.DLL in a platform-independent way. In other > words, I would expect the UFFI to do the call of SetDllDirectory() or > whatever is needed on Windows for me or to use other mechanisms on other > platforms. > > > >> Do you mean you link OTHER.DLL to YOUR.DLL at compile time? >> But still, YOUR.DLL it not loaded until called via Pharo FFI, so neither >> is OTHER.DLL, >> and Dynamic-Link Library Search Order [1] says... "If a DLL with the >> same module name >> is already loaded in memory, the system uses the loaded DLL, no matter >> which directory it is in. >> The system does not search for the DLL." >> >> So maybe before calling any of YOUR.DLL, >> do a SetDllDirectory followed by a LoadLibrary(OTHER.DLL) >> and later when you call into YOUR.DLL, >> OTHER.DLL is already loaded. >> > > Yes, this might work but is rather contrived. > > > >> Otherwise it would seems(?) your options are either Manifests >> or Dynamic-Link Library Redirection, both done outside of Pharo. >> > > What if neither YOUR.DLL nor OTHER.DLL are under my control? The only thing I > know is where the .dll and the corresponding .lib + .h are. > > > > Thanks for your interest > Raffaello > > > > >> But I'll try whether SetDllDirectory also affects load-time searches. >> >> Anyway, I hope future versions of the UFFI to offer setting the >> search paths more easily. >> >> >> >> Greetings >> Raffaello >> > >
