Assembler library for .NET, assembling runtime-variable strings into machine code for injection

Question

Is there such a thing as an x86 assembler that I can call through C#? I want to be able to pass x86 instructions as a string and get a byte array back. If one doesn\'t exist

Answer 1

Cosmos also has some interesting support for generating x86 code:

http://www.gocosmos.org/blog/20080428.en.aspx

Answer 2

Take a look at this: CodeProject: Using unmanaged code and assembly in C#.

Answer 3

As part of some early prototyping I did on a personal project, I wrote quite a bit of code to do something like this. It doesn't take strings -- x86 opcodes are methods on an X86Writer class. Its not documented at all, and has nowhere near complete coverage, but if it would be of interest, I would be willing to open-source it under the New BSD license.

UPDATE: Ok, I've created that project -- Managed.X86

Answer 4

I think you would be best off writing a native Win32 dll. You can then write a function in assembler that is exported from the dll. You can then use C# to dynamically link to the dll.

This is not quite the same as passing in a string and returning a byte array. To do this you would need an x86 assembler component, or a wrapper around masm.exe.

Answer 5

i don't know if this is how it works but you could just shellexecute an external compiler then loading the object generated in your byte array.

Answer 6

See this project:

https://github.com/ZenLulz/MemorySharp

This project wraps the FASM assembler, which is written in assembly and as a compiled as Microsoft coff object, wrapped by a C++ project, and then again wrapped in C#. This can do exactly what you want: given a string of x86/x64 assembly, this will produce the bytes needed.

If you require the opposite, there is a port of the Udis86 disassembler, fully ported to C#, here:

https://github.com/spazzarama/SharpDisasm

This will convert an array of bytes into the instruction strings for x86/x64