Function GetDllProcAddress

source/script2.cpp:10852–10942

}

void *GetDllProcAddress(LPCTSTR aDllFileFunc, HMODULE *hmodule_to_free) // L31: Contains code extracted from BIF_DllCall for reuse in ExpressionToPostfix.
{
	int i;
	void *function = NULL;
	TCHAR param1_buf[MAX_PATH*2], *_tfunction_name, *dll_name; // Must use MAX_PATH*2 because the function name is INSIDE the Dll file, and thus MAX_PATH can be exceeded.
#ifndef UNICODE
	char *function_name;
#endif

	// Define the standard libraries here. If they reside in %SYSTEMROOT%\system32 it is not
	// necessary to specify the full path (it wouldn't make sense anyway).
	static HMODULE sStdModule[] = {GetModuleHandle(_T("user32")), GetModuleHandle(_T("kernel32"))
		, GetModuleHandle(_T("comctl32")), GetModuleHandle(_T("gdi32"))}; // user32 is listed first for performance.
	static const int sStdModule_count = _countof(sStdModule);

	// Make a modifiable copy of param1 so that the DLL name and function name can be parsed out easily, and so that "A" or "W" can be appended if necessary (e.g. MessageBoxA):
	tcslcpy(param1_buf, aDllFileFunc, _countof(param1_buf) - 1); // -1 to reserve space for the "A" or "W" suffix later below.
	if (   !(_tfunction_name = _tcsrchr(param1_buf, '\\'))   ) // No DLL name specified, so a search among standard defaults will be done.
	{
		dll_name = NULL;
#ifdef UNICODE
		char function_name[MAX_PATH];
		WideCharToMultiByte(CP_ACP, 0, param1_buf, -1, function_name, _countof(function_name), NULL, NULL);
#else
		function_name = param1_buf;
#endif

		// Since no DLL was specified, search for the specified function among the standard modules.
		for (i = 0; i < sStdModule_count; ++i)
			if (   sStdModule[i] && (function = (void *)GetProcAddress(sStdModule[i], function_name))   )
				break;
		if (!function)
		{
			// Since the absence of the "A" suffix (e.g. MessageBoxA) is so common, try it that way
			// but only here with the standard libraries since the risk of ambiguity (calling the wrong
			// function) seems unacceptably high in a custom DLL.  For example, a custom DLL might have
			// function called "AA" but not one called "A".
			strcat(function_name, WINAPI_SUFFIX); // 1 byte of memory was already reserved above for the 'A'.
			for (i = 0; i < sStdModule_count; ++i)
				if (   sStdModule[i] && (function = (void *)GetProcAddress(sStdModule[i], function_name))   )
					break;
		}
	}
	else // DLL file name is explicitly present.
	{
		dll_name = param1_buf;
		*_tfunction_name = '\0';  // Terminate dll_name to split it off from function_name.
		++_tfunction_name; // Set it to the character after the last backslash.
#ifdef UNICODE
		char function_name[MAX_PATH];
		WideCharToMultiByte(CP_ACP, 0, _tfunction_name, -1, function_name, _countof(function_name), NULL, NULL);
#else
		function_name = _tfunction_name;
#endif

		// Get module handle. This will work when DLL is already loaded and might improve performance if
		// LoadLibrary is a high-overhead call even when the library already being loaded.  If
		// GetModuleHandle() fails, fall back to LoadLibrary().