Compilers

[The-Futurist]

I'm in the early stages of developing a compiler (for a new systems programming language), written in C# which generates unmanaged code and will eventually target ELF but initially I want to target Windows.

I want to be able to generate windows COFF output OBJ/DLL files programmatically, the compiler generates unmanaged code.

I did this many years ago and wrote a COFF generator in C, part of the backend of a compiler that worked and produced linkable outputs.

But that code is all C and I'd rather avoid writing a C# version of that code if I can. So can AsmResolver be used for this?

FYI this is the compiler I did years ago and this is the source and header for the "cofflib" COFF file generator.

[Washi1337]

AsmResolver can create new PE files, which includes DLLs. Creating and writing a PE can be as simple as:

using AsmResolver;
using AsmResolver.PE.File;

// Create a new empty PE file (default target arch is i386).
var file = new PEFile();

// Add a section.
var section = new PESection(
   name: ".text",
   characteristics: SectionFlags.MemoryRead | SectionFlags.MemoryExecute | SectionFlags.ContentCode,
   contents: new DataSegment([1, 2, 3, 4, 5])
);
file.Sections.Add(section);

// Save it to the disk.
file.Write(@"C:\output.dll");

You probably want to start here or here for documentation for setting up the headers, creating sections, and interacting with standard data directories found in PE.

AsmResolver does not have support for .obj specific structures found in COFF. It also does not feature a native instruction encoder/decoder so you will have to facilitate native code generation yourself (or use libraries such as iced or capstone).

[The-Futurist]

@Washi1337

Thanks. Sure I don't expect code to be generated, I will do that, but I do have a few questions:

1. OBJ's are relatively simple compared to DLL/EXE so perhaps that could be added - I could even look at that if I needed to.
2. I'm assuming I can create DLL files though is that supported or does the library focus on .EXE files?

[Washi1337]

1. Sounds good, I'm open to the idea.
2. Yes, DLLs are just PE files with some flags set in its headers. They are identical to normal executables in practically every other way.