I’m trying to use Lua/Moonsharp API scripting. There’s a command library, but there isn’t a function that I need. My question is, am I able to create my own function, or am I limited to what’s been written?
Specifically, for a software called BobCAD a Lua plugin is available. There are lists of commands like Bcc.SetCamObjParameter, though, there isn’t the command that I need. I’m assuming that some aspects of the BobCAD software are inaccessible to API, but am I limited to the library in this plugin, or can I add my own commands? I thought that there would be some C# file somewhere in the program directory where I can read the functions and possibly learn how to create my own, but I don’t see anything like that. (Or are scripting functions set up internally to the software, and I’m only given access to what has been provided?)
(N.b. I'm not familiar with BobCAD specifically, but this answer should be generally applicable.)
Generally speaking, for use cases like this (where Lua scripting is provided as part of a larger program, or by a plugin for a larger program), it's the developer of the program or plugin who decides what API is available to Lua. In the latter case they may also be limited by what the program's plugin API allows; in the case of BobCAD you are likely limited to what the BobCAD plugin API permits, and then further limited by what parts of that API the developers of the Lua plugin chose to make available to Lua itself.
You can of course write your own functions in Lua, but in terms of actually talking to the host program you are restricted to the API that program makes available, unless they make available some mechanism (like LuaJIT's Foreign Function Interface) for reaching into the program from Lua and calling functions that were not made explicitly available -- which most do not.
As for finding "a C# file somewhere in the program directory" -- C# is a compiled language; C# libraries are generally shipped as pre-compiled CLR binaries (with a .dll extension) and do not contain source code. If the source code for BobCAD and/or the Lua plugin is available you could always modify it and re-compile it, but as BobCAD is commercial, closed-source software, I would not expect it to be available.
At that point, your options are basically:
figure out a way to do what you need with the commands that are available;
try to reverse engineer enough of the program to do what you need without access to the source code;
or look for another program that has the features you need.
Related
I have written a UI in Electron and I would like to connect it with my C++ code. However, I will be selling this product and so I would like to know if this makes it easier for people to crack my C++ code? Obviously I know compiled C++ can be cracked anyway, but does this affect it in any way?
Additionally, what is the best way to go about this while preserving maximum possible security?
Thanks.
EDIT: How about this? Is it possible to use c++ as back-end for Electron.js?
EDIT2: To clarify, my Electron app will be showing the status of operations being performed in the C++ program. As such, I will need to send lists, dictionaries, strings etc. from C++ to JS which will then render it. Additionally, buttons on my Electron app need to trigger actions in the C++ code, such as stopping or starting certain parts of the program.
I have written a UI in Electron and I would like to connect it with my C++ code ...
I would like to know if this makes it easier for people to crack my C++ code?
Using electron does not make any meaningful difference for protecting the C++ source code. (Your intellectual property)
The Javascript code running in electron will be very easy to reverse engineer though, which gives users a head start on experimenting with your C++ binary. Using minification and obfuscation tools can at least make that harder.
For the C++ side, connecting C++ to Electron can be done in at least these two ways:
By dynamically linking to a shared library (Node.js C++ Addons)
In this case your C++ API would be functions that get exported by the shared library. There are many tools to inspect shared libraries (DLLs) and view these functions.
By communicating with another process using some sort of Inter-process communication.
In this case your API would depend on the IPC method used. If it was TCP/UDP messages you could use Wireshark to inspect the packets between the processes. There are ways to inspect messages going over any type of IPC.
Either way, your application must be delivered to the end-user with a compiled binary. Preventing reverse engineering of the binary itself is impossible if you actually give the binary to your users.
You should also expect that a savvy end-user will have access to other tools that can inspect the API and implement third-party code that talks to that API.
Additionally, what is the best way to go about this while preserving maximum possible security?
By "maximum possible security", I will assume you are referring to preventing unauthorized use of the C++ code with other applications.
You would need a licensing system that can authenticate the application that is using your C++ binary's API. Explaining what that would be exactly is probably too large of an answer for a Stack Overflow, and you will have to do some research on how licensing systems are implemented.
It may be theoretically impossible to develop a perfect licensing system though. Look at the gaming industry, it takes just a matter of days to for the licensing software become circumvented for every new game that is released. The only software architecture that cracks haven't completely conquered are cloud-based applications, which don't actually deliver compiled code with their business logic to the end-user's computer.
I am interested in integrating language from another audio programming language (ChucK) into my Delphi project. I know that maybe that is possible with dynamic-link libraries (.DLLs) but I am not familiar with this.
Does anyone know how I can configure a project to get the two languages working together?
A quick glance at the ChucK documentation suggests three possible approaches, all arising from the fact that ChucK is both a language and also a virtual machine (VM) to run the programs written in that language.
ChucK is open source, so the full source code of that VM is available but is written in C++. ChucK is available either in this source code form or as a ready-to-run executable for the supported platforms.
I could find no reference to any DLL version of the VM for use within other programs. Which isn't to say that such a DLL has not been developed by others, only that I couldn't find any reference to one and it does not appear to be part of the standard distribution of ChucK itself.
I did find some source code which references a DLL in the context of ChucK but it was not entirely clear to me whether this was a DLL API for using ChucK or part of the implementation, allowing ChucK itself to be modularised or extended via DLL's.
The three options I see before you are:
Port the Chuck VM to Delphi. That is, translate all of the ChucK VM source code to Delphi. This will give you a version of ChucK implemented entirely in Delphi which is capable of running ChucK programs.
Implement a DLL API (possibly based around or starting from that link above) for the existing ChucK VM source code in C++ in a way that enables you run ChucK programs by calling into that DLL to be run by the existing C++ implementation of ChucK.
Run ChucK programs using the ChucK exe using ShellExecute(), WinExec() or CreateProcess() etc, just as you would if you wished to run any other external program from a Delphi program.
These are presented roughly in descending order of difficulty. That is, a full port to Delphi (Opt 1) is likely to be beyond your capability.
Implementing a DLL interface around the existing C++ code (Opt 2) may be possible depending on your C++ and Windows development skills.
Calling an external program (Opt 3) is relatively straightforward.
Which approach is right for you depends on the nature of your assignment, the objectives, and your confidence/skills in the areas involved.
Good luck.
An easy way to get different systems talking to each other is use Open Sound Control (OSC). ChucK has OSC receivers and senders (search for "> OSC") built into it and Delphi looks like it implements OSC as well.
OSC works over networks but you can also just send messages to your own local machine (localhost). The ChucK examples do this referenced above do this.
It's not a tight integration but it'll get the Delphi-ChucK relationship going.
What are the typical use cases of using an embeddable programming language? Do I understand it correctly that such language should be embedded into some program environment and should be able to be executed from there?
Since you tagged the question as "Lua", I'll give you an answer in the context of this language.
Introduction
Lua is written in C (almost completely compatible with C89 standard; the incompatible features can be easily disabled, if needed, using compile-time switches) and has been designed to be easily integrated with C code. In the the context of Lua, "integrated" means two different, but related, things:
You can easily write C code that can be used as a library by Lua code. The integration is achieved either by static or dynamic linking your C code to Lua engine's code. The linked library can then be referred to in your Lua code using the Lua require function.
Lua engine can be easily embedded in a C application, i.e. linked (again either statically or dynamically) to the C application code. Then the C application can interact with the Lua code using Lua's C application programming interface (Lua C-API).
Note: this can be done, with a little more effort, also with a C++ application.
Advantages of embedding a Lua engine
If your C application embeds Lua many, if not most, operations can be delegated to the Lua engine, i.e. either to code written using the C-API functions or, better yet, Lua code. Lua code could be embedded as C strings inside your C code or be stored as external Lua scripts.
Having part of your code logic implemented using Lua code has several advantages:
Lua is simpler (less tricky) to learn and use than C, and it is much more high-level. It supports powerful abstractions, such as function closures and object orientation (in a peculiar way, using Lua tables and metamethods).
Lua is a dynamic language: it requires no "off-line" compilation. You can modify the text of your Lua script and that's all you need to modify your application behavior (no additional compilation+linking steps needed). This simplifies application development and debugging.
Lua is a safer language than C: it is really difficult to write Lua code that exhibits undefined behavior, as intended in the context of C/C++. If a Lua script fails, it fails "loudly". Moreover Lua supports an exception mechanism (although with a different syntax than C++) which can be employed to implement error management in a much easier way compared to C.
Lua, as most dynamic languages, is garbage collected. This means that the programmer is spared the pain of manually managing dynamic memory, which is a major cause of bugs, leaks, instability and security loopholes in languages that lack garbage collection.
Lua can "eat its own dog food", i.e. you can build a string at runtime (even in Lua itself) and if it is valid Lua code, your program can execute it on the fly. This is something not frequently seen even in other dynamic languages (still it is not LISP, but it gets closer, and with much more readable syntax). This enables Lua scripts to:
employ powerful text-based metaprogramming techniques, where Lua code can generate other Lua code and execute it on the fly;
implement domain specific languages (DSLs) in an easy way; Lua code can load at runtime other Lua code that is crafted so as to reflect the specific problem domain in which it is used (Lua syntax is simple, yet flexible enough to allow such things);
be used as a configuration language with ease: your application (written in a mix of C and Lua) can use some lua files as configuration files without the need to craft an ad-hoc parser for a specific configuration file format. Therefore you don't need to parse *.properties, *.csv, *.ini, or whichever other format you would choose if you hadn't the option of using Lua files for that purpose.
Lua engine has a very small memory footprint (some hundreds kBs), packing powerful capabilities. With very few C code lines and a bunch of Lua files you could create a complete application that would require thousands of C code lines otherwise. The standard Lua standalone interpreter can be seen as just an example of embedding Lua in a C application!
Lua has a very liberal open-source license, which enables its use even in commercial applications without much hassle. This also allows the modification of its source code to adapt it to special needs.
Small memory footprint and easily tweakable C sources make Lua a perfect candidate for porting it on embedded systems or small microcomputer systems (microcontrollers, etc.). Many parts of the standard Lua distributions can be stripped off, reducing the core Lua engine in the ~100kB range. As an example, take the eLua project, a modified distribution of Lua designed for embedded devices.
Lua, and other scripting languages, provide various benefits that are dependant on your needs.
Provide rapid iteration of development.
Allow run-time code changes, such as reloading your UI in World of Warcraft which re-loads all scripts without stopping the game engine itself or logging you out.
Provide a distinct API for your application for users to extend, without exposing critical parts of your system to the public. Such as text editors providing a macro language to allow you to integrate custom behaviour without giving you unfettered access to the internals of the editor itself.
The uses are really quite extensive and depends on the developer.
How can I get the meomory of any Process in Lua?
Is it possible in Lua? Is C# it is possible but I am not sure.
In C# we can use PerformanceCounter class to get the
PerformanceCounter WorkingSetMemoryCounter = new PerformanceCounter("Process",
"Working Set", ReqProcess.ProcessName);
What is equivalent of this in Lua?
Suppose there are 5 process of IE (Internet Explorer) running . How to get a List of those process?
To elaborate on what others have said, Lua is a scripting language designed for embedding. That means that it runs inside another application.
Lua.exe is one such application. But it is not the only application that Lua scripts can be written to be executed on.
When within a Lua script, you have access to exactly and only what the surrounding application environment allows. If the application does not explicitly allow you to access things like "files" or "the operating system", then you don't get to access them. Period.
Lua's standard library (which an application can forbid scripts to use. Lua.exe allows it, but there are some embedded environments that do not) is very small. It doesn't offer a lot of amenities, which make Lua ideal for embedded environments: small standard libraries mean smaller executables. Which is why you see a lot more Lua in mobile applications than, say, Python. Also, the standard library is cross-platform, so it does not access platform-specific libraries.
Modules, user-written programs (either in Lua or C/C++) can be loaded into Lua.exe's environment. Such a module could give your Lua script access to things like "processes", how much memory the process is taking, and so forth. But if you do not have access to such a module, then you're not getting that info from within a Lua script.
The most you are going to be able to do is get the size of the memory that this particular Lua environment is directly allocating and using, as #lhf said: collectgarbage "count".
To get the memory allocated by Lua in Kbytes, use collectgarbage"count".
Lua does not comes with this built-in functionality. You could write a binding to a library that provides you that or you could interface with a program to do that (like reading the output of "ps -aux | grep firefox").
I want to develop an application that can retrieve information such as, DLL version, DLL build mode(debug or release), info. regarding OS, memory, processer, processes/threads, program version etc. I am developing this mainly for Windows, but it'd be good if the application supports Linux too(wherever applicable).
I am basically a java programmer, and I know C, C++ to some extent.
Which programming language should I go for, that'd make my job easy? i.e. which language has APIs to fetch these kind of information?
Well... APIs are available regardless of the language... But the easiest way to get at what you are trying to do is going to be a C or C++ app. That doesn't mean it'll be easy (getting a DLL version is easy, getting memory and processor type is easy. The other stuff is certainly possible, but you may have to roll up your sleeves and learn the win32 API).
You might want to take a look at an application that already does exactly what you are asking about (Process Explorer) before you try to develop this yourself... It's going to be a big undertaking - and the folks at Sys Internals are really, really good at this stuff, and have already done it.
You commented on Kevin Day's answer that you would prefer to use Java for this.
Java is not very well suited for this, because the information you want to get is very platform-specific, and since Java is designed to be platform-independent, there are not a lot of ways to get at this kind of information from Java.
There are some methods in classes java.lang.System and java.lang.Runtime to get information about the platform that your Java program is running on. For example, class Runtime has a method availableProcessors() that tells you how many processors are available to the Java virtual machine. Note that this is not the same as the number of processors (or cores) that exist in the computer; the documentation even says that the number may change while the program is running.
Lookup the documentation for java.lang.System and java.lang.Runtime for more information.
Most likely you're not going to get exactly the information that you need by using pure Java - C or C++ will be better suited to get this kind of platform-specific information. If you would need this information from a Java program, you could write a small DLL or shared library and use JNI to call into it from your Java program.
Since DLLs are mentioned I presume we are talking about Windows.
I would recommend using WMI queries. They look very much like SQL and give you access to many very useful classes.
e.g. all info about the OS can be found here - in W32_OperatingSystem:
http://msdn.microsoft.com/en-us/library/aa394239(VS.85).aspx
You can use WMI classes from any language including C++.
As a side note - if you start a new application from scratch consider using PowerShell - new scripting language from Microsoft.