ILSpy，如何解析依赖关系？

Question

我想用ILSpy反汇编整个.NET程序集。

我使用以下代码作为基础：

http://skysigal.xact-solutions.com/Blog/tabid/427/entryid/2488/Default.aspx

它工作得很好，只是当我有一个引用Npgsql.dll的程序集(或任何其他非gac程序集)时，我就会得到一个AssemblyResolutionException。

无法解析程序集：'Npgsql，Version=2.0.11.92，Culture=neutral，PublicKeyToken=5d8b90d52f46fda7‘

我知道如何获取引用的程序集，但如何将它们添加到ast？

    // SqlWebAdmin.Models.Decompiler.DecompileAssembly("xy.dll");
    public static string DecompileAssembly(string pathToAssembly)
    {
        //Assembly assembly = Assembly.LoadFrom(pathToAssembly);
        System.Reflection.Assembly assembly = System.Reflection.Assembly.ReflectionOnlyLoadFrom(pathToAssembly);
        //assembly.GetReferencedAssemblies();

        //assembly.GetReferencedAssemblies(assembly);
        Mono.Cecil.AssemblyDefinition assemblyDefinition =
            Mono.Cecil.AssemblyDefinition.ReadAssembly(pathToAssembly);



        ICSharpCode.Decompiler.Ast.AstBuilder astBuilder = new ICSharpCode.Decompiler.Ast.AstBuilder(new ICSharpCode.Decompiler.DecompilerContext(assemblyDefinition.MainModule));
        astBuilder.AddAssembly(assemblyDefinition);


        //new Helpers.RemoveCompilerAttribute().Run(decompiler.CompilationUnit);
        using (System.IO.StringWriter output = new System.IO.StringWriter())
        {
            astBuilder.GenerateCode(new ICSharpCode.Decompiler.PlainTextOutput(output));
            string result = output.ToString();
            return result;
        }

        return "";
    } // End Function DecompileAssembly

Answer 1

您需要告诉ILSpy正在使用的底层元数据读取器Cecil，您的程序集在哪里。你可以这样写：

var resolver = new DefaultAssemblyResolver();
resolver.AddSearchDirectory("path/to/my/assemblies");

var parameters = new ReaderParameters
{
    AssemblyResolver = resolver,
};

var assembly = AssemblyDefinition.ReadAssembly(pathToAssembly, parameters);

这是告诉Cecil在哪里解析引用的程序集的最自然的方式。这样，您可以删除使用System.Reflection加载程序集的行，并且只使用ILSpy堆栈。

Answer 2

这是经过改进的@Nayan回答。如果要忽略缺少的程序集，请复制此类：

using Mono.Cecil;

public class IgnoringExceptionsAssemblyResolver : DefaultAssemblyResolver
{
    public override AssemblyDefinition Resolve(AssemblyNameReference name)
    {
        try
        {
            return base.Resolve(name);
        }
        catch
        {
            return null;
        }
    }
}

并像这样使用它：

var assembly = AssemblyDefinition.ReadAssembly(path, new ReaderParameters() {
    AssemblyResolver = new IgnoringExceptionsAssemblyResolver()
});

Answer 3

除了JB Evain的建议之外，此代码还将帮助避免异常。你所要做的就是在解决程序中处理异常。

我承认，这不是最好的方法。但它适用于这个场景："If I am decompiling a DLL on a system where the referred assemblies are not present, the decompilation fails (with exception.) At least, i would like to see the decompile code, for whatever has been resolved."

using System;
using System.Collections.Generic;
using Mono.Cecil;

public class MyAssemblyResolver : BaseAssemblyResolver
{
    private readonly IDictionary<string, AssemblyDefinition> cache;
    public MyAssemblyResolver()
    {
        this.cache = new Dictionary<string, AssemblyDefinition>(StringComparer.Ordinal);
    }
    public override AssemblyDefinition Resolve(AssemblyNameReference name)
    {
        if (name == null)
            throw new ArgumentNullException("name");
        AssemblyDefinition assemblyDefinition = null;
        if (this.cache.TryGetValue(name.FullName, out assemblyDefinition))
            return assemblyDefinition;
        try  //< -------- My addition to the code.
        {
            assemblyDefinition = base.Resolve(name);
            this.cache[name.FullName] = assemblyDefinition;
        }
        catch { } //< -------- My addition to the code.
        return assemblyDefinition;
    }
    protected void RegisterAssembly(AssemblyDefinition assembly)
    {
        if (assembly == null)
            throw new ArgumentNullException("assembly");
        string fullName = assembly.Name.FullName;
        if (this.cache.ContainsKey(fullName))
            return;
        this.cache[fullName] = assembly;
    }
}

并像这样使用它：

var rp = new Mono.Cecil.ReaderParameters() { AssemblyResolver = new MyAssemblyResolver() };
var assemblyDefinition = Mono.Cecil.AssemblyDefinition.ReadAssembly(assemblyStream, rp);
var astBuilder = new ICSharpCode.Decompiler.Ast.AstBuilder(
     new ICSharpCode.Decompiler.DecompilerContext(assemblyDefinition.MainModule));
astBuilder.AddAssembly(assemblyDefinition);

实际上，我希望看到反编译器中的一个增强:它目前忽略了DefaultAssemblyResolver类中用户设置的ReaderParameters。

用法：

var rp = new Mono.Cecil.ReaderParameters();
var assemblyDefinition = Mono.Cecil.AssemblyDefinition.ReadAssembly(assemblyStream, rp);

当前DefaultAssemblyResolver代码：

public override AssemblyDefinition Resolve(AssemblyNameReference name)
{
    if (name == null)
    {
        throw new ArgumentNullException("name");
    }
    AssemblyDefinition assemblyDefinition;
    if (this.cache.TryGetValue(name.FullName, out assemblyDefinition))
    {
        return assemblyDefinition;
    }
    assemblyDefinition = base.Resolve(name); // <---------
// Is the `ReaderParameters` object set by user, used to resolve in `base` class?

    this.cache[name.FullName] = assemblyDefinition;
    return assemblyDefinition;
}