NOTE: Currently LibObjectFile supports the following file format:

PE image file format (Portable Executable / DLL)

ELF object-file format

Mach-O object-file format, including universal binaries

DWARF debugging format (version 4)

Archive ar file format (Common, GNU and BSD variants)

There is a longer term plan to support other file formats (e.g COFF, .lib) but as I don't have a need for them right now, it is left as an exercise for PR contributors! ;)

Usage

// Reads an ELF file
using var inStream = File.OpenRead("helloworld");
var elf = ElfFile.Read(inStream);
foreach(var section in elf.Sections)
{
    Console.WriteLine(section.Name);
}
// Print the content of the ELF as readelf output
elf.Print(Console.Out);
// Write the ElfFile to another file on the disk
using var outStream = File.OpenWrite("helloworld2");
elf.Write(outStream);

Features

Full support of Archive ar file format including Common, GNU and BSD variants.
Full support for the PE file format
- Support byte-to-byte roundtrip
- Read and write from/to a System.IO.Stream
- All PE Directories are supported
- PEFile.Relocate to relocate the image base of a PE file
- PEFile.Print to print the content of a PE file to a textual representation
- Support for calculating the checksum of a PE file
Good support for the ELF file format:
- Support byte-to-byte roundtrip
- Read and write from/to a System.IO.Stream
- Handling of LSB/MSB
- Support the following sections:
  - String Table
  - Symbol Table
  - Relocation Table: supported I386, X86_64, ARM and AARCH64 relocations (others can be exposed by adding some mappings)
  - Note Table
  - Dynamic Linking Table (SHT_DYNAMIC)
  - Other sections fallback to ElfCustomSection
- Program headers with or without sections
- ElfFile.AddNeededLibrary injects a DT_NEEDED dependency into an existing image without moving any section (address-preserving, patchelf-style)
- Print with readelf similar output
Good support for the Mach-O file format:
- Support byte-to-byte roundtrip
- Read and write from/to a System.IO.Stream
- 32 and 64 bit, i386, x86_64 and arm64
- Universal (fat) binaries via MachOFatFile
- The load commands a linked image is built from are decoded; the rest round-trip verbatim
- Symbol table, indirect symbol table and relocations
- MachOFile.AddLoadDylib, AddRPath, RemoveRPath, ChangeDylibName and SetInstallName edit an existing image without moving any section (address-preserving, install_name_tool-style)
- MachOFile.AdHocSign writes an ad-hoc code signature, which Apple Silicon requires in order to execute an image
- MachOFile.Print to print the content of a Mach-O file with otool similar output
Support for DWARF debugging format:
- Partial support of Version 4 (currently still the default for GCC)
- Support for the sections: .debug_info, .debug_line, .debug_aranges, .debug_abbrev and .debug_str
- Support for Dwarf expressions
- High level interface, automatic layout/offsets between sections.
- Integration with ELF to support easy reading/writing back
- Support for relocatable sections
Use of a Diagnostics API to validate file format (on read/before write)
Library requiring net8.0
- If you are looking for netstandard2.1 support you will need to use 0.4.0 version

Documentation

The doc/readme.md explains how the library is designed and can be used.

Download

LibObjectFile is available as a NuGet package:

Build

In order to build LibObjectFile, you need to have installed the .NET 8 SDK.

Running the tests require Ubuntu 22.04. dotnet test will work on Windows (via WSL) and on that version of Ubuntu. If you're using macOS or another Linux, there's a Dockerfile and a helper script under src to run tests in the right OS version.