# ELFIO and ARIO: header-only ELF and archive handling for C++

> ELFIO reads and writes ELF binaries and ARIO handles UNIX ar archives, both as header-only C++ libraries with no dependencies and no build step, aimed at compiler, linker, binary analysis and build system authors. The judgement is that the zero-friction integration is exactly right for small tools, and that the manual copying of headers and the gap between the last tag and the current branch are what you accept in exchange.

**serge1/ELFIO** — ELFIO and ARIO are robust, header-only C++ libraries designed to make binary file and archive manipulation effortless, efficient, and portable. Whether you are building compilers, linkers, binary analysis tools, or custom build systems, these libraries provide the foundation you need for working with ELF files and UNIX archives.

- Repository: https://github.com/serge1/ELFIO
- Website: http://serge1.github.io/ELFIO
- Stars: 897 · Forks: 188
- Language: C++
- License: MIT
- Published: 2026-10-20 · Updated: 2026-10-20 · Language: en
- Canonical page: https://hysenlabs.com/projects/serge1-elfio

## Two libraries, one header-only model

This repository holds two related C++ libraries rather than a single tool. ELFIO handles ELF object and executable files, and ARIO handles UNIX ar archives, the format used for static libraries. Both are header-only, which means there is nothing to build and nothing to link: you copy the source directories into your project and include a header. Neither has external dependencies, and both are written to ISO C++ standards so they behave the same across compilers and architectures. The stated audience is specific. The README names compiler and linker authors, people building binary analysis tools, and engineers writing custom build systems, and the list of who uses them covers open-source projects, commercial toolchains, academic research, embedded systems and reverse engineering tools. The project structure is correspondingly flat, with elfio/ and ario/ holding the headers, examples/ holding sample programs and tools, and the repository root carrying a CMakeLists.txt, a cmake directory, a doc directory and a tests directory.

## ELFIO reads, creates and modifies ELF files

ELFIO is described as a lightweight, header-only library for reading and generating ELF binaries, and it is completely standalone. The feature list draws the line at the ELF structures themselves, since the library can read, create and modify ELF files including sections, segments and symbols. That is a meaningful boundary to note, because it means the library operates on the container rather than on the compiled code inside it, so it will happily rewrite a section table, strip or rewrite symbols, or add a section to an existing binary, but it will not decompile anything. The README also frames it as easy to integrate, designed both for small utilities and for large-scale applications, and states that the cross-platform target covers Windows, Linux and macOS. A PDF tutorial and user manual is linked from the README and hosted on SourceForge, and the ELF specification itself is linked from the resources section for readers who need to check the format rather than the library.

## ARIO covers the static library side of a toolchain

ARIO is the newer half of the pair, a header-only C++ library for reading, creating and modifying UNIX ar files, and it is designed to work alongside ELFIO. The access model is the part that sets it apart, since it can read and write to files, to memory and to custom streams, which means an archive can be manipulated in a pipeline without ever touching the disk. The use cases the README lists are the ones a toolchain actually needs: building and modifying static libraries, extracting or replacing object files inside an archive, analysing and manipulating symbol tables in archives, and writing custom build tools and binary utilities, including automated toolchains and CI systems. Because both libraries expose the same style of interface and use the same header-only distribution model, a tool that has to read an object file out of an archive and then patch it can do that with one mental model rather than two.

## Two includes and no build system

Installation is a copy, not a package manager step. You copy the elfio and ario directories into your project and include the relevant header, and no build or linking steps are required. Reading an ELF file looks like this, where the load call reports success and then the sections, segments and symbols are available:

```cpp
#include <elfio/elfio.hpp>
ELFIO::elfio reader;
if (reader.load("my_binary.elf")) {
    // Access ELF sections, segments, symbols, etc.
}
```

The archive side follows the same shape, and the load call returns a result object whose ok method tells you whether the file was read, after which the members are iterated:

```cpp
#include <ario/ario.hpp>
ARIO::ario archive;
if (archive.load("libmylib.a").ok()) {
    for (const auto& member : archive.members) {
        std::cout << "Member: " << member.name << std::endl;
    }
}
```

What you should see in practice is a program that links nothing extra and compiles with the same flags as the rest of your project.

## The examples directory is the API tour

The examples/ directory carries a set of sample programs, and the names describe the surface area better than any feature list. There is a tutorial, a writer example, a write_obj example for producing object files, an add_section example, an elfdump example for dumping the contents of a binary, an elfio_ldd example, an anonymizer for stripping identifying information out of binaries, an arion example and an arioso example for the archive side, a c_wrapper for using the library from C, and a proc_mem example alongside a sudo_gdb.sh helper script. The README describes the purpose of the examples as illustrating typical usage, providing ready-to-use code for common binary and archive operations, and helping users get started, and it says the examples double as practical tutorials and as a starting point for your own tools. The presence of the c_wrapper example is worth a second look for anyone integrating with a C codebase, and the anonymizer is the interesting one for anyone who ships binaries and needs to remove build paths and debug information.

## The friction is in upgrades, not in the first build

There is no awkwardness in getting started, and the trade-off is entirely in what happens eighteen months later. Because installation is a manual copy of two directories, there is no version constraint in your build system, no lock file, and no way to receive a fix without copying files again by hand, which means tracking which version of ELFIO a binary was built against is your problem. The header-only design has a second cost that shows up in development rather than in the artefact, since changing a header rebuilds every translation unit that includes it, and ELFIO is a single large header by design. The README's own claims deserve a sober reading, because it calls the libraries actively maintained and trusted by open-source and commercial projects worldwide, and it also lists the newest tagged releases as 3.12 on 2023-08-28, 3.11 on 2022-11-18 and 3.10 on 2022-02-07. The last push to the branch was on 2026-08-07 and the repository is not archived, so the work continues, but the released versions and the branch are not the same thing, and the README does not document a policy for that gap. Support is offered through GitHub issues, and the documentation is a single PDF manual.

## MIT, cross-platform CI and the shape of the tree

The licence is MIT, which is the permissive choice you want for a library that will be compiled into other people's products, and the repository ships the text in LICENSE.txt. The build and test infrastructure is visible in the tree rather than hidden. There is a CMakeLists.txt at the root and a cmake directory, a tests directory, an examples directory with its own CMakeLists.txt, a .clang-format file that defines the formatting the project expects, and .github workflows whose badges show a C/C++ CI run and a CodeQL analysis job, so the code is both compiled and scanned on every change. The examples set includes the c_wrapper mentioned earlier, which is a reminder that the library is meant to be usable outside a C++ only codebase. There is also a doc directory and a .vscode directory for editor settings. In short, the project is small, permissively licensed, dependency-free and actively pushed, and the only real decision for an adopter is whether manual header management fits the way your team ships dependencies.

## Conclusion

ELFIO is worth adopting for a compiler, linker, binary analysis tool or build system that needs to read, create or patch ELF files without pulling in a platform library, and ARIO is the natural companion when those tools also have to touch static libraries, since the two are designed to sit in the same toolchain. It is the wrong choice for a codebase that wants a package manager dependency and automatic upgrades, since the installation is a manual copy of the elfio and ario directories and the tagged releases stop at 3.12 from 2023. Before you commit, read the ELFIO tutorial PDF linked from the README, compile one of the examples against your toolchain, and check the current state of the main branch, since the last push was on 2026-08-07 while the newest release tag is older.

## FAQ

### How do I add ELFIO to a C++ project?

Copy the elfio and ario directories into your project and include the relevant header, for example #include <elfio/elfio.hpp> for ELFIO or #include <ario/ario.hpp> for ARIO. No build or linking steps are required because both libraries are header-only.

### Can ELFIO create and modify ELF files, or only read them?

Both. The README states the library can read, create and modify ELF files including sections, segments and symbols, and the examples directory includes an add_section example, a writer example and a write_obj example alongside the reading tools such as elfdump.

### Does ELFIO and ARIO work outside Linux?

Yes. The README describes both libraries as cross-platform, working on Windows, Linux and macOS, built to ISO C++ standards, and ARIO additionally offers universal access to files, to memory and to custom streams.

## Sources

- [License: MIT](https://github.com/serge1/ELFIO/blob/main/LICENSE)
- [Project website](http://serge1.github.io/ELFIO)
- [README](https://github.com/serge1/ELFIO/blob/main/README.md)
- [Releases](https://github.com/serge1/ELFIO/releases)
- [serge1/ELFIO on GitHub](https://github.com/serge1/ELFIO)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/serge1-elfio