Re: Using FFI as a plugin
- From: Coda Highland <chighland@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 17 May 2012 12:50:17 -0500
On Thu, May 17, 2012 at 12:37 PM, Dimiter 'malkia' Stanev
<malkia@xxxxxxxxx> wrote:
>> Yes, I had considered this, but that requires knowing exactly where
>> the host decided to install my plugin, which can and will vary from
>> system to system. If the plugin could somehow resolve its own path,
>> that would do the trick, but at present I don't think there's a way to
>> do that.
>>
>> /s/ Adam
>>
>
> On Windows, there are three ways for your module to get it's own path:
>
> Here are the first two, unfortunately I don't think they can work in luajit,
> not unless you link or
> know specific symbol that is part of your DLL - for example it might work if
> you link statically to
> luajit, but you are still DLL, then instead of using __ImageBase (this is
> MSVC specific, or
> &get_module_filename, use it, for example lua_open, or something like it)
>
> extern "C" IMAGE_DOS_HEADER __ImageBase;
> static std::string get_module_filename()
> {
> MEMORY_BASIC_INFORMATION mbi;
> VirtualQuery(&get_module_filename,&mbi, sizeof(mbi) );
> HMODULE mod1 = (HMODULE)mbi.AllocationBase;
> HMODULE mod2 = (HMODULE)&__ImageBase;
> assert( mod1 == mod2 );
> char buf[ _MAX_PATH ];
> GetModuleFileNameA( mod1, buf, sizeof( buf ) );
> return buf;
> }
>
>
> But there is a better way, and I think LuaJIT is already using it, it should
> work on anything XP+:
>
> http://msdn.microsoft.com/en-us/library/windows/desktop/ms683200(v=vs.85).aspx
> <http://msdn.microsoft.com/en-us/library/windows/desktop/ms683200%28v=vs.85%29.aspx>
>
> static std::string get_module_filename()
> {
> HMODULE hModule = 0;
> GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
> get_module_filename,&hModule);
> char buf[ _MAX_PATH ];
> GetModuleFileNameA(hModule, buf, sizeof( buf ) );
> return buf;
> }
>
>
> Sorry for giving out C, instead of luajit/ffi examples, but these should be
> easy to translate
> (I just copied them from a forum, where I posted the original suggestion,
> and was given the
> latter which is much better)
>
> I don't think how this is done on UNIX* like systems, but there is probably
> a way...
>
I don't mind looking up a symbol from my library. That's no problem at all.
It's perfectly fine to get C -- possibly even preferable for the sake
of sandboxing.
I do appreciate this, although it's Mac I'm really worried about at
the moment. If I can find a solution there, then this is half of the
battle -- the other being the other thread I posted.
/s/ Adam
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