How to programmatically get DLL dependencies

Question

How can I get the list of all DLL dependencies of a given DLL or EXE file?

In other words, I'd like to do the same as the "Dependency walker" tool, but programmatically.

What is the Windows (ideally .NET) API for that?

Answer 1

You can use EnumProcessModules function. Managed API like kaanbardak suggested won't give you a list of native modules.

For example see this page on MSDN

If you need to statically analyze your dll you have to dig into PE format and learn about import tables. See this excellent tutorial for details.

Answer 2

NOTE: Based on the comments from the post below, I suppose this might miss unmanaged dependencies as well because it relies on reflection.

Here is a small c# program written by Jon Skeet from bytes.com on a .NET Dependency Walker

using System;
using System.Reflection;
using System.Collections;

public class DependencyReporter
{
    static void Main(string[] args)
    {
        //change this line if you only need to run the code one:
        string dllToCheck = @"";

        try
        {
            if (args.Length == 0)
            {
                if (!String.IsNullOrEmpty(dllToCheck))
                {
                    args = new string[] { dllToCheck };
                }
                else
                {
                    Console.WriteLine
                        ("Usage: DependencyReporter <assembly1> [assembly2 ...]");
                }
            }

            Hashtable alreadyLoaded = new Hashtable();
            foreach (string name in args)
            {
                Assembly assm = Assembly.LoadFrom(name);
                DumpAssembly(assm, alreadyLoaded, 0);
            }
        }
        catch (Exception e)
        {
            DumpError(e);
        }

        Console.WriteLine("\nPress any key to continue...");
        Console.ReadKey();
    }

    static void DumpAssembly(Assembly assm, Hashtable alreadyLoaded, int indent)
    {
        Console.Write(new String(' ', indent));
        AssemblyName fqn = assm.GetName();
        if (alreadyLoaded.Contains(fqn.FullName))
        {
            Console.WriteLine("[{0}:{1}]", fqn.Name, fqn.Version);
            return;
        }
        alreadyLoaded[fqn.FullName] = fqn.FullName;
        Console.WriteLine(fqn.Name + ":" + fqn.Version);

        foreach (AssemblyName name in assm.GetReferencedAssemblies())
        {
            try
            {
                Assembly referenced = Assembly.Load(name);
                DumpAssembly(referenced, alreadyLoaded, indent + 2);
            }
            catch (Exception e)
            {
                DumpError(e);
            }
        }
    }

    static void DumpError(Exception e)
    {
        Console.ForegroundColor = ConsoleColor.Red;
        Console.WriteLine("Error: {0}", e.Message);
        Console.WriteLine();
        Console.ResetColor();
    }
}