Lua Proxy Dll Two

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The utility requires using of MinGW development system.

Prerequisites:

1. mkproxy.lua (below on this page)

2. liblua5.1.def (definition file, generated when lua5.1.dll is built)

3. lua5.1.dll

mkproxy.lua:

-- Goal:         Create a proxy dll that redirects all calls to the "real" dll
-- Written by:   Shmuel Zeigerman

-- CONFIGURATION
local DEFFILE   = "liblua5.1.def" -- name of definition file
local REALPATH  = "c:\\exe"       -- path of forwarded DLL
local REALNAME  = "lua5.1"        -- name of forwarded DLL (without extension)
local PROXYNAME = "lua51"         -- name of forwarder (proxy) DLL
-- END OF CONFIGURATION

local cfile = assert(io.open("temp.c", "w"))
cfile:write[[
  #include <windows.h>
  BOOL WINAPI DllMain (HINSTANCE hinstDLL, DWORD Reason, LPVOID Reserved)
  { return TRUE; }
]]
cfile:close()

local cmdline = table.concat ({
	"gcc --add-stdcall-alias -shared -s -nostdlib temp.o",
	DEFFILE,
	"-L" .. REALPATH,
	"-l" .. REALNAME,
	"-o" .. PROXYNAME .. ".dll",
}, " ")

os.execute("gcc -c temp.c -o temp.o")
os.execute(cmdline)
----------------------------------------------------------------------

-- ShmuelZeigerman

Comments

--I've wondered why LuaBinaries renames lua51.dll as lua5.1.dll, or, if this is a better approach, why Lua itself doesn't follow. This all just makes things needlessly more complicated for new users and for module authors not familiar with the rules. It's not a Good Thing(TM), for we come to the above. I see LuaBinaries is now distributed with such a wrapper too. --DavidManura

This was already discussed on the mailing list: [1] --ShmuelZeigerman

The following build is for MSVC2005. It uses the "nodefaultlib" linker option. The final proxy DLL was about 9 KB.

local DEFFILE  = "lua5.1.def" -- .def file for lua5.1.dll
local LIBFILE  = "lua5.1.lib" -- .lib file for lua5.1.dll
local CFILE   = "luaproxy.c"-- output file
local MAKFILE = "luaproxy.mak"  -- output file
----------------------------------------------------------------------
local cfile = assert(io.open(CFILE, "w"))
cfile:write [=[
#include <windows.h>
    BOOL APIENTRY
DllMain(HANDLE module, DWORD reason, LPVOID reserved)
    { return TRUE; }
]=]
cfile:close()
----------------------------------------------------------------------
local makfile = assert(io.open(MAKFILE, "w"))
makfile:write(string.format([=[
lua51.dll : luaproxy.c
	cl -I../lua/src /O2 /LD /GS- luaproxy.c /link /def:%s %s \
	   /out:lua51.dll /nodefaultlib /entry:DllMain
]=], DEFFILE, LIBFILE))
makfile:close()
----------------------------------------------------------------------

--DavidManura

It seems that what you are doing is building an empty C file which links to the stubs in the import library, and reexposing those stubs as a dll interface. This would mean that the DLL you generate:

1. does contain code (DllMain?, and the import library)

2. add a function call overhead to each API call

Tell me if I misunderstood your code.

-- JeromeVuarand

See Also

• LuaProxyDll | LuaProxyDllTwo | LuaProxyDllThree