I understand I can use either the CodeDOM or Mono for compiling and executing C# code on the fly. Which of these are suggested given the security concerns of executing code and flexibility?
EDIT: I need to create an editor in which any user can enter code and choose to execute it. My concern is that if they have malicious code (accessing the file system for example) then I need to take precautions to prevent this from happening. How would I do this using CodeDOM or Mono?
For maximum flexibility, Mono C# compiler should be the choice.
I don't think both provide any security protection inside, as that should be something you do in your own code.
You could use CodeDom anyways, compile and run the code in another AppDomain. My suggestion would be to insert the code as a CodeSnippetStatement into a CodeMemberMethod, that way they can't break out or are constrained by what you provide.
Related
I want to learn if there is any library in .net to write c# scripts. Let me describe you with more detail, for example I have an application. When I run it, a c# editor will be opened end user will write some c# codes and when click run, this code should be evaluated and dom should be created after interpret my run time c# code will run. this is brief description of my mind...
I put together a little app called SimpleDevelop which uses CSharpCodeProvider to do what you describe. My understanding is that this (CodeDom) is deprecated and generally discouraged; however, it seems to work just fine for simple scenarios.
Basically, you want to use something like the CSharpCodeProvider. The Razor view engine in MVC essentially uses this to compile your code into an executable to run. If you want your user to be able to write code and then have it interpreted, you would start here. Please note though, this is an incredibly complicated and time intensive feat to get right; plus, linking in and executing foreign code dynamically is a security nightmare. Just be safe.
Are you looking for a test bench sort of?
I use LinqPad for that.
It is mostly a test bench for Linq queries, but I find it very useful for C# statements and mini programs and such.
Check out the System.CodeDom namespace.
This article contains lots of useful information: http://www.developerfusion.com/article/4529/using-net-to-make-your-application-scriptable/2/
You can use the Compiler namespace and compilate the code at runtime. Take a look here for an explanation on how to do it.
I have created an application which will run c# like script without using visual studio.
It is on https://sourceforge.net/projects/csharpquickcode/
I am designing a desktop application in C#, which automatically generates code
based on the requirement provided.
Now I want to check the syntax of the code that is generated.
In the earlier stages we can feed the system some possibilities.
Is there some thing i can do here rather than feeding the system for
every possibility?
Thanks.
Providing you generate the code yourself, the best way to ensure it's syntactically correct is to generate a syntactically correct code at the first place.
Otherwise, besides creating a custom C# parser and semantic analyzer (a “half-compiler”), you can consider calling the command-line C# compiler, which is part of the .NET framework, and analyze its textual output.
The command-line C# compiler usage and output is described here in MSDN. Have a look on Process.Start on how to start a new process from your code.
The easiest way to check the syntax of generated code would be to compile it. Let the compiler handle this for you.
Since you're generating it, once you get it correctly generated, it should be fine (provided the design is done nicely).
Just run the command-line C# compiler, csc.exe, and look at it's output. The syntax is "csc Desktop\MyProgram.cs". For a .dll, the syntax is "csc.exe /target:library Desktop\MyProgram.cs". The csc.exe executable is usually located in Windows\Microsoft.NET\Framework\\csc.exe.
I would like to build an application framework that is mainly interpreted.
Say that the source code would be stored in the database that could be edited by the users and always the latest version would be executed.
Can anyone give me some ideas how does one implement sth like this !
cheers,
gabor
In .Net, you can use reflection and CodeDOM to compile code on the fly. But neither approach is really very simple or practical. Mono has some ability to interpret c# on the fly as well, but I haven't looked closely at it yet.
Another alternative is to go with an interpreted .Net language like Boo or IronPython as the language for your database code.
Either way, make sure you think long and hard about the security of your platform. Allowing users to execute arbitrary code is always an exercise fraught with peril. It's often too tempting to look for a simple eval() method, and even if one exists, that is not good enough for this kind of scenario.
Try Mono ( http://www.monoproject.org ). It supports many scripting languages including JavaScript.
If you don't want to use any scripting you can use CodeDOM or Reflection (see Reflection.Emit).
Here are really useful links on the topic :
Dynamically executing code in .Net (Here you can find a tool which can be very helpul)
Late Binding and On-the-Fly Code
Generation Using Reflection in C#
Dynamic Source Code Generation and
Compilation
Usually the Program uses a scripting language for the scriptable parts, i.e. Lua or Javascript.
To answer your technical question: You don't want to write your own language and interpreter. That's too much work for you to do. So pick some other language, say Python or Lua, and look for the documentation that lets your C program hand it blocks of code to execute. Of course, the script needs to be able to do something, so you'll need to find how to expose your program's objects to the script. Also, what will happen if a client is running the program when you update its source code in the database? Should the client restart? Are you going to store the entire program as a single row in this database, or did you want to store individual functions? That affects how you structure your updates.
To address other issues with your question: Why do you want to do this? Making "interpreted language" part of your design spec for a system is not often a good sign. Is the real requirement something like this: "I update the program often and I want users to always have the latest copy?" If so, there are other, better ways to go about this (just give us your actual scenario and requirements).
I'm making a Genetic Program, but I'm hitting a limitation with C# where I want to present new functions to the algorithm but I can't do it without recompiling the program. In essence I want the user of the program to provide the allowed functions and the GP will automatically use them. It would be great if the user is required to know as little about programming as possible.
I want to plug in the new functions without compiling them into the program. In Python this is easy, since it's all interpreted, but I have no clue how to do it with C#. Does anybody know how to achieve this in C#? Are there any libraries, techniques, etc?
It depends on how you want the user of the program to "provide the allowed functions."
If the user is choosing functions that you've already implemented, you can pass these around as delegates or expression trees.
If the user is going to write their own methods in C# or another .NET language, and compile them into an assembly, you can load them using Reflection.
If you want the user to be able to type C# source code into your program, you can compile that using CodeDom, then call the resulting assembly using Reflection.
If you want to provide a custom expression language for the user, e.g. a simple mathematical language, then (assuming you can parse the language) you can use Reflection.Emit to generate a dynamic assembly and call that using -- you guessed it -- Reflection. Or you can construct an expression tree from the user code and compile that using LINQ -- depends on how much flexibility you need. (And if you can afford to wait, expression trees in .NET 4.0 remove many of the limitations that were in 3.5, so you may be able to avoid Reflection.Emit altogether.)
If you are happy for the user to enter expressions using Python, Ruby or another DLR language, you can host the Dynamic Language Runtime, which will interpret the user's code for you.
Hosting the DLR (and IronPython or IronRuby) could be a good choice here because you get a well tested environment and all the optimisations the DLR provides. Here's a how-to using IronPython.
Added in response to your performance question: The DLR is reasonably smart about optimisation. It doesn't blindly re-interpret the source code every time: once it has transformed the source code (or, specifically, a given function or class) to MSIL, it will keep reusing that compiled representation until the source code changes (e.g. the function is redefined). So if the user keeps using the same function but over different data sets, then as long as you can keep the same ScriptScope around, you should get decent perf; ditto if your concern is just that you're going to run the same function zillions of times during the genetic algorithm. Hosting the DLR is pretty easy to do, so it shouldn't be hard to do a proof of concept and measure to see if it's up to your needs.
You can try to create and manipulate Expression Trees. Use Linq to evaluate expression trees.
You can also use CodeDom to compile and run a function.
For sure you can google to see some examples that might fit your needs.
It seems that this article "How to dynamically compile C# code" and this article "Dynamically executing code in .Net" could help you.
You have access to the Compiler from within code, you can then create instances of the compiled code and use them without restarting the application. There are examples of it around
Here
and
Here
The second one is a javascript evaluator but could be adapted easily enough.
You can take a look at System.Reflection.Emit to generate code at the IL level.
Or generate C#, compile into a library and load that dynamically. Not nearly as flexible.
It is in fact very easy to generate IL. See this tutorial: http://www.meta-alternative.net/calc.pdf
For business reasons, I want to create a C# application that would take a C++ file / snippet as input, compile it (probably invoking a C++ compiler under the hood) and output compilation results.
Do you know how this could be done?
Thanks in advance.
Using CL.exe
Look in to the Process class.
It provides all of the functionality required to start an external application, including a compiler.
Now, depending on the compiler you choose, you will need to specify the start arguments of the process carefully in order to compile in a predictable way.
Most compilers support command-line parameters.
You just need to build the right command and execute it through the shell like advised here.
che
If you want to not just build a single file, but a whole .vcproj file - check the command line parameters for devenv.exe. If I remember correct it is:
devenv.exe /build my.vcproj
You can shell out to any number of command-line C++ compilers (like gcc) using Process.Start.
You could do this by calling any C++ compiler on the command line. I'm sure the compilation results can be redirected so that you can grab it after the compile finished.
If you are trying to achieve something like SnippetCompiler for C++, you might want to look at one of the C/C++ scripting languages. I have always liked CInt.
Sure its possible, it is actually common practice nmake and other make-like utilities call the compiler all the time.
OTOH if you are thinking of deploying this solution to a customer you may be in for a bit of rough ride cause of all the details like settings, location where files are, how to react on the result, license, which c++ compiler to deploy etc.
Another option which is much simpler (IMHO) is instead of C++ to invoke the C# compiler directly from your C# program for compiling a C# snippet. Files can then stay in memory and you don't need to save any files before you compile. There are numerous examples on the web that show how to do that. Another advantage with this solution is that you already have the C# compiler there so there is no need to install a C++ compiler as well.