NSIS plugin load

Hello!

We have a program that is downloaded around 1000 users per day. Installer is NSIS based. Recently we wrote a plugin for it and it seems that in some cases plugin can't be loaded/function can't be executed on some user machines. 1 of 4 installers fails.

Here is the function from plugin.

EXTERN_C void __declspec(dllexport) __cdecl test(HWND hwndParent, int string_size,

	LPTSTR variables, stack_t **stacktop,

	extra_parameters *extra, ...)

{

	EXDLL_INIT();

	{

		pushstring("TEST");

	}

}

That is how it called

Var VAL_TEST



Function .onInit

  ourPlugin::test

  Pop $VAL_TEST

FunctionEnd

That is how it sended to the server

Section "Main"

inetc::get /SILENT "https://ourcompanyurl.com/api/?test=$VAL_TEST" $TEMP\r /END

SectionEnd

And in 1 of 4 times test is empty. It means that plugin didn't return value, but installer didn't crashed because query is successfull. What could be the problem?

Only one thought - may be something with DLL loading? All plugins examples that I saw were compiled with /NODEFAULTLIB but I compiled with default libs, because my c++ code didn't compiled without it. Could it be the problem?

Yes that can definitely be the problem.

If you have access to one of the machines where it fails you can check the .DLL with http://www.dependencywalker.com/

In general, if you are linking to a msvc####.dll then it will fail to load if the C-Run Time redist. matching that version is not installed.

You can use static linking to avoid this mess.

Thank you for answering, Anders!

To check exactly what causes the problem I tried to load plugin dll directly from the script using LoadLibrary. On machines where it failed it failed with error code 126 (ERROR_MOD_NOT_FOUND) that confirms your assumption. Also Dependecy Walker showed dependecies KERNEL32.DLL, ADVAPI32.DLL, MSVCP140.DLL, RPCRT4.DLL, VCRUNTIME140.DLL

I changed /MD to /MT and got another error on failed machines. Now LoadLibrary sometimes returns error 998 (ERROR_NOACCESS) Dependecy Walker shows only 3 dependecies now: KERNEL32.DLL, ADVAPI32.DLL, RPCRT4.DLL

Maybe you are doing something wrong in DllMain, very hard for me to tell.

You should try creating a new simple .DLL and keep adding code until it fails.