YACL (Yet Another C# Library) is a simple C# library for reading and writing C# binaries. Leveraging Mono.Cecilin, YACL provides an easy-to-use API for manipulating .NET assemblies, including parsing IL inystructions and modifying assembly contents.

Features

Load and Save Assemblies: Easily load existing assemblies and save modifications.

Parse IL Instructions: Extract and display Intermediate Language (IL) instructions from methods.

Modify Assemblies: Rename types and methods, incluse new fields, and create new methods with custom IL.

Usage

Loading an Assembly

var loader = new AssemblyLoader();
AssemblyDefinition assembly = loader.LoadAssembly("path/to/your/assembly.dll");
Console.WriteLine($"Loaded assembly: {assembly.Name.FullName}");

Parsing IL Instructions

var parser = new ILParser();
var typesInfo = parser.ParseIL(assembly);

foreach (var type in typesInfo)
{
    Console.WriteLine($"Type: {type.FullName}");
    foreach (var method in type.Methods)
    {
        Console.WriteLine($"\tMethod: {method.Name}");
        if (method.HasBody)
        {
            foreach (var instruction in method.ILInstructions)
            {
                Console.WriteLine($"\t\t{instruction.Offset:X4}: {instruction.OpCode} {instruction.Operand}");
            }
        }
    }
}

Modifying an Assembly

Renaming a Type

var modifier = new BinaryModifier(assembly);
modifier.RenameType("OldNamespace.OldTypeName", "NewNamespace.NewTypeName");

Renaming a Method

var modifier = new BinaryModifier(assembly);
modifier.RenameMethod("Namespace.TypeName", "OldMethodName", "NewMethodName");

Inserting a New Field

var modifier = new BinaryModifier(assembly);
modifier.InsertField("Namespace.TypeName", "NewField", "System.Int32");

Creating a New Method

var modifier = new BinaryModifier(assembly);
var parameters = new ParameterDefinition[]
{
    new ParameterDefinition("name", ParameterAttributes.None, assembly.MainModule.TypeSystem.String)
};

var newMethod = modifier.CreateMethod("Namespace.TypeName", "Greet", "System.Void", parameters);

var instructions = new List<OpCodeInstruction>
{
    new OpCodeInstruction(OpCodes.Ldarg_1),
    new OpCodeInstruction(OpCodes.Ldstr, "Hello, "),
    new OpCodeInstruction(OpCodes.Call, assembly.MainModule.ImportReference(typeof(string).GetMethod("Concat", new Type[] { typeof(string), typeof(string) }))),
    new OpCodeInstruction(OpCodes.Call, assembly.MainModule.ImportReference(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }))),
    new OpCodeInstruction(OpCodes.Ret)
};

modifier.WriteMethodIL("Namespace.TypeName", "Greet", instructions.ToArray());

Saving the Modified Assembly

var modifier = new BinaryModifier(assembly);
modifier.SaveAssembly("path/to/save/ModifiedAssembly.dll");
Console.WriteLine("Modified assembly saved successfully.");

Example

class Example
{
    static void Main()
    {
        var loader = new AssemblyLoader();
        var assembly = loader.LoadAssembly("MyApp.exe");

        var parser = new ILParser();
        var typesInfo = parser.ParseIL(assembly);
        // Display types and methods...

        var modifier = new BinaryModifier(assembly);
        modifier.RenameType("MyApp.Program", "MyApp.MainProgram");
        modifier.SaveAssembly("Modified_MyApp.exe");
    }
}