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How can I allow users to write C# lambda in config and load them dynamically

I have a set of data which is not particularly clean, and I have written functions for LINQ queries that filter out what I think is unnecessary data. I have written these as lambdas. However I would like to be able to put the lambdas in the .config file so they can be fiddled with without having to recompile the entire application. I was sure that this could be done, and I have managed to find some code online which takes C# source code and compiles it:
internal static class DynamicDelegates
{
internal static Assembly CompileAssembly(string source)
{
var compilerParameters = new CompilerParameters()
{
GenerateExecutable = false,
GenerateInMemory = true,
ReferencedAssemblies =
{
"System.Core.dll", // needed for linq + expressions to compile
"PatchDataLibrary.dll" // A dependency on the main application.
},
};
var providerOptions = new Dictionary<string, string>();
providerOptions.Add("CompilerVersion", "v4.5.2");
var compileProvider = new CSharpCodeProvider(providerOptions);
var results = compileProvider.CompileAssemblyFromSource(compilerParameters, source);
if (results.Errors.HasErrors)
{
Console.Error.WriteLine("{0} errors during compilation of rules", results.Errors.Count);
foreach (CompilerError error in results.Errors)
{
Console.Error.WriteLine(error.ErrorText);
}
throw new InvalidOperationException("Broken rules configuration, please fix");
}
var assembly = results.CompiledAssembly;
return assembly;
}
}
The code following leverages this to return the delegate (ReleaseType.ProductBelongs):
namespace Shibboleth.ReleaseHandoverUtility.Configuration
{
internal class ProductBelongsDelegateElement : ConfigurationElement
{
private const string _classTemplate = #"
using System;
using System.Linq.Expressions;
using PatchDataLibrary.Models.ReleaseModel;
namespace Shibboleth.ReleaseHandoverUtility
{{
public static class ProductBelongsLib
{{
public static Shibboleth.ReleaseHandoverUtility.ReleaseType.ProductBelongs ProductBelongs {{ get {{ return {0}; }} }}
}}
}}
";
private ProductBelongs _value;
protected override void DeserializeElement(XmlReader reader, bool serializeCollectionKey)
{
string value = (reader.ReadElementContentAsString());
var tempAssembly = DynamicDelegates.CompileAssembly(string.Format(_classTemplate, value));
var type = tempAssembly.GetTypes().Single();
var property = type.GetRuntimeProperties().Single();
var propertyValue = property.GetValue(null, null);
_value = (ProductBelongs)propertyValue;
}
public ProductBelongs Value { get { return _value; } }
}
The problem is that I am targeting Framework 4.5.2, but when it compiles the code, I get the exception:
System.InvalidOperationException occurred
HResult=-2146233079
Message=Compiler executable file csc.exe cannot be found.
Looking online, it seems that this is because this is used to construct the path, and v4.5.2 is in the v4.0 path. Fair enough, so I change:
providerOptions.Add("CompilerVersion", "v4.5.2");
to
providerOptions.Add("CompilerVersion", "v4.0");
This time I get an error in the errors collection of the compiler:
[0] = {c:\Users\Mark.Bertenshaw\AppData\Local\Temp\nyposo3b.0.cs(10,74) : error CS0234: The type or namespace name 'ReleaseType' does not exist in the namespace 'Shibboleth.ReleaseHandoverUtility' (are you missing an assembly reference?)}
Taking the code that causes this compilation error and putting it into a new project for framework v4.5.2 doesn't get an error. However, when as an experiment I change it to v4.0 I reproduce the error.
So can anyone suggest how I can force the framework to be 4.5.2? Or maybe there is an alternative way of doing this? Ideally, this doesn't involve downloading extra compilers and scripting frameworks.

Get all methods from C# source code

I am looking forward to get all method names used in C# using following code:
CompilerParameters parameters = new CompilerParameters()
{
GenerateExecutable = false,
GenerateInMemory = true
};
var provider = new CSharpCodeProvider();
foreach (string path_file in files)
{
string source = File.ReadAllText(path_file);
Console.Out.WriteLine(source);
CompilerResults results = provider.CompileAssemblyFromSource(parameters, source);
if (results.Errors.HasErrors)
{
foreach (var error in results.Errors)
Console.Out.WriteLine(error.ToString());
return;
}
}
I am trying to read the source code in a variable source and passing this in CompileAssemblyFromSource method of CSharpCodeProvider class.
I am getting the following error under result variable.
c:\Users\username\AppData\Local\Temp\2rdqotiv.0.cs(3,14) : error CS0234: The type or namespace name 'Linq' does not exist in the namespace 'System' (are you missing an assembly reference?).
Can anyone please help me to solve this error? I am using MVS 15.

You have to add the referenced assemblies, for example:
parameters.ReferencedAssemblies.Add(typeof(Enumerable).Assembly.Location);
You can also add assemblies manually, as follows:
string exDir = $#"C:\WINDOWS\Microsoft.NET\Framework\v{ver}";
parameters.CompilerOptions = $"/lib:{exDir}";
And BTW, you could also use CompileAssemblyFromFile instead of having to open the files manually.

C# Loading assemblies dynamically

I'm having an issue when compiling text into dynamic objects at runtime.
I wrote a simple piece of code to compile the text:
public class CompileFactory
{
public dynamic Compile(String classCode, String mainClass, Object[] requiredAssemblies)
{
CSharpCodeProvider provider = new CSharpCodeProvider(new Dictionary<string, string>
{
{ "CompilerVersion", "v4.0" }
});
CompilerParameters parameters = new CompilerParameters
{
GenerateExecutable = true, // Create a dll
GenerateInMemory = true, // Create it in memory
WarningLevel = 3, // Default warning level
CompilerOptions = "/optimize", // Optimize code
TreatWarningsAsErrors = false // Better be false to avoid break in warnings
};
// Add all extra assemblies required
foreach (var extraAsm in requiredAssemblies)
{
parameters.ReferencedAssemblies.Add(extraAsm as string);
}
CompilerResults results = provider.CompileAssemblyFromSource(parameters, classCode);
if (results.Errors.Count != 0)
{
return "FAILED";
}
return results.CompiledAssembly.CreateInstance(mainClass); ;
}
}
This is how I am using the Compile method.
List<string> assemblies = new List<string>{"System.Net.Mail.dll", "System.Net.dll"};
dynamic obj = compile.Compile(fileText, pluginName, assemblies.ToArray());
As you can see I'm adding references to extra assemblies at some point. For some reason when I add using System.Net; to the text file, it will not be referenced and I get errors. The text I'm compiling is literally a .cs file saved as text. I thought of working around this by extracting the using * and adding them separately, however for when adding System.Net.Mail.dll, the metadata file cannot be found.
Has anyone experienced something similar? I really would like to just add the using * to the file and be ready with it.
Any input would be greatly appreciated.

The issue here is that System.Net.dll does not exist. You can check in which assembly a .Net type is by right clicking somewhere it is referenced and choosing "Go to definition". This will bring up a tab with the class definition "from metadata". At the top of this file, you've got a #region showing where this type comes from. In the case of a TcpClient, we can see this:
#region Assembly System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
// C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5.2\System.dll
#endregion
Change your call to Compile with "System.dll" instead of "System.Net.dll" and it should work just fine
Edit/Clarification: It is not possible to get an assembly name from a using statement.

Running a runtime compiled C# script in a sandbox AppDomain

My application should be scriptable by the users in C#, but the user's script should run in a restricted AppDomain to prevent scripts accidentally causing damage, but I can't really get it to work, and since my understanding of AppDomains is sadly limited, I can't really tell why.
The solution I am currently trying is based on this answer https://stackoverflow.com/a/5998886/276070.
This is a model of my situation (everything except Script.cs residing in a strongly named assembly). Please excuse the wall of code, I could not condense the problem any further.
class Program
{
static void Main(string[] args)
{
// Compile the script
CodeDomProvider codeProvider = CodeDomProvider.CreateProvider("CSharp");
CompilerParameters parameters = new CompilerParameters()
{
GenerateExecutable = false,
OutputAssembly = System.IO.Path.GetTempFileName() + ".dll",
};
parameters.ReferencedAssemblies.Add(Assembly.GetEntryAssembly().Location);
CompilerResults results = codeProvider.CompileAssemblyFromFile(parameters, "Script.cs");
// ... here error checks happen ....//
var sandbox = Sandbox.Create();
var script = (IExecutable)sandbox.CreateInstance(results.PathToAssembly, "Script");
if(script != null)
script.Execute();
}
}
public interface IExecutable
{
void Execute();
}
The Sandbox class:
public class Sandbox : MarshalByRefObject
{
const string BaseDirectory = "Untrusted";
const string DomainName = "Sandbox";
public static Sandbox Create()
{
var setup = new AppDomainSetup()
{
ApplicationBase = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, BaseDirectory),
ApplicationName = DomainName,
DisallowBindingRedirects = true,
DisallowCodeDownload = true,
DisallowPublisherPolicy = true
};
var permissions = new PermissionSet(PermissionState.None);
permissions.AddPermission(new ReflectionPermission(ReflectionPermissionFlag.RestrictedMemberAccess));
permissions.AddPermission(new SecurityPermission(SecurityPermissionFlag.Execution));
var domain = AppDomain.CreateDomain(DomainName, null, setup, permissions,
typeof(Sandbox).Assembly.Evidence.GetHostEvidence<StrongName>());
return (Sandbox)Activator.CreateInstanceFrom(domain, typeof(Sandbox).Assembly.ManifestModule.FullyQualifiedName, typeof(Sandbox).FullName).Unwrap();
}
public object CreateInstance(string assemblyPath, string typeName)
{
new FileIOPermission(FileIOPermissionAccess.Read | FileIOPermissionAccess.PathDiscovery, assemblyPath).Assert();
var assembly = Assembly.LoadFile(assemblyPath);
CodeAccessPermission.RevertAssert();
Type type = assembly.GetType(typeName); // ****** I get null here
if (type == null)
return null;
return Activator.CreateInstance(type);
}
}
The loaded Script:
using System;
public class Script : IExecutable
{
public void Execute()
{
Console.WriteLine("Boo");
}
}
In CreateInstance of SandBox, I always get null at the marked line. I tried various forms of giving the name, including reading the type name (or fuly qualified name) from results.CompiledAssembly using reflection.
What am I doing wrong here?

The first thing that i'll check is if there are compilation errors (i had several headache caused by this issues)
The second idea is about the resolution of assemblies. I always add as a security check an event handler for AppDomain.CurrentDomain.AssemblyResolve, where i seek on my known path for the missing Assemblies. When the not found assembly is the one i just compiled i add a static reference to it and return it.
What I usually do is this:
Create the new Assembly on file system with the compiler
Load its content with the File.ReadAllBytes
Load the dll with the Assembly.Load in the AppDomain in which i will be using the object
Add the AppDomain.CurrentDomain.AssemblyResolve event
Just in case (since i use this a lot) i created a small library to accomply this kind of things
The code and documentation are here: Kendar Expression Builder
While the nuget package is here: Nuget Sharp Template

CodeDomProvider Code Generation Fails With Certain Linq Syntax

I'm using the CodeDomProvider to compile some Linq code and execute queries dynamically. However, I'm hitting a very strange issue.
If my Linq query in the generated code looks like this everything works:
namespace Dynamic
{
using System.Linq;
using System.Collections.Generic;
public static class Query
{
public static int GetRecords()
{
MyData.Data.DataMart container = new MyData.Data.DataMart();
return (container.EventDetails).Count();
}
}
}
This compiles and runs just fine. However, if I change the linq query to the following then it fails to compile:
return (from e in container.EventDetails select e).Count();
It works fine if I put this as static code, but if I try to compile it with the CodeDomProvider it fails (and I haven't found any good method to get error messages on why it fails). I would like to use the from-in-select style of syntax since this will make it easier for me to generate the linq queries but I can't figure out why they are not compiling.
You can see some of the code I use to compile this snippet at the link on the top of this post.
Thanks!
Edit: Copying the code from the post I linked to:
CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");
CompilerParameters cp = new CompilerParameters();
cp.GenerateInMemory = true;
cp.ReferencedAssemblies.Add("mscorlib.dll");
cp.ReferencedAssemblies.Add("System.dll");
cp.ReferencedAssemblies.Add("System.Core.dll");
cp.ReferencedAssemblies.Add("System.Data.Linq.dll");
cp.ReferencedAssemblies.Add("System.Data.Entity.dll");
cp.ReferencedAssemblies.Add("MyApp.Data.dll");
var results = provider.CompileAssemblyFromSource(cp, source);
var assm = results.CompiledAssembly;
Edit2: As far as the exception goes, I get an exception on the second to last line of code (var results = ...). The exception is a BadImageFormatException:
Could not load file or assembly '0 bytes loaded from System,
Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or
one of its dependencies. An attempt was made to load a program with an
incorrect format

This seems to work for me:
static void Main(string[] args)
{
string sourceCode = #"namespace Dynamic {
using System.Linq;
using System.Collections.Generic;
public static class Query
{
public static int GetRecords()
{
MyApp.Data.DataMart container = new MyApp.Data.DataMart();
//return (container.EventDetails).Count();
return (from e in container.EventDetails select e).Count();
}
} }";
string sDynamDll = "Dynamic.dll";
string sDynamClass = "Query";
string sDynamMethod = "GetRecords";
System.CodeDom.Compiler.CompilerParameters cp = new CompilerParameters();
cp.GenerateExecutable = false;
cp.GenerateInMemory = true;
cp.OutputAssembly = sDynamDll;
cp.ReferencedAssemblies.Add("mscorlib.dll");
cp.ReferencedAssemblies.Add("System.dll");
cp.ReferencedAssemblies.Add("System.Core.dll");
cp.ReferencedAssemblies.Add("System.Data.Linq.dll");
cp.ReferencedAssemblies.Add("System.Data.Entity.dll");
cp.ReferencedAssemblies.Add("MyApp.Data.dll");
var providerOptions = new Dictionary<string, string>();
providerOptions.Add("CompilerVersion", "v4.0");
CodeDomProvider compiler = CodeDomProvider.CreateProvider("C#", providerOptions);
CompilerResults cr = compiler.CompileAssemblyFromSource(cp, sourceCode);
if (cr.Errors.HasErrors)
{
StringBuilder errors = new StringBuilder("Compiler Errors :\r\n");
foreach (CompilerError error in cr.Errors)
{
errors.AppendFormat("Line {0},{1}\t: {2}\n", error.Line, error.Column, error.ErrorText);
}
}
// verify assembly
Assembly theDllAssembly = null;
if (cp.GenerateInMemory)
theDllAssembly = cr.CompiledAssembly;
else
theDllAssembly = Assembly.LoadFrom(sDynamDll);
Type theClassType = theDllAssembly.GetType(sDynamClass);
foreach (Type type in theDllAssembly.GetTypes())
{
if (type.IsClass == true)
{
if (type.FullName.EndsWith("." + sDynamClass))
{
theClassType = type;
break;
}
}
}
// invoke the method
if (theClassType != null)
{
object[] method_args = new object[] { };
Object rslt = theClassType.InvokeMember(
sDynamMethod,
BindingFlags.Default | BindingFlags.InvokeMethod,
null,
null, // for static class
method_args);
Console.WriteLine("Results are: " + rslt.ToString());
}
Console.ReadKey();
}

You're probably getting BadImageFormatException because your code isn't actually compiling to a valid assembly. This might be because the old 2.0 compiler is used by default. Check the link below for enabling the C# the 3.5 version (I don't know if 4.0 is supported, but you don't need it):
http://blogs.msdn.com/b/lukeh/archive/2007/07/11/c-3-0-and-codedom.aspx
Also check the Errors collection on the CompilerResult that is returned from the CompileAssemblyFromSource() method. Failure to compile does not throw an exception, you must manually check for compile errors.

I didn't find an answer of how to get good exception information, however, I did solve this problem. The class library that contained the compiler code above was set to AnyCpu but the context it was running in under ASP.Net was x86. So this was causing it to fail when it tried to load System.dll since it was loading the wrong version (or something silly like that).
I'll be happy to give someone else the answer checkmark if you can (a) figure out how to get a real error message from this or (b) load the right reference type.