README.md

FileFS C++20 Port

This directory contains a pure C++20 implementation of FileFS, matching the on-disk format and core semantics of the C and Go ports.

Highlights

• Pure C++20 rewrite in the filefs:: namespace
• STL-style public API with move-only File and Directory handles
• 512-byte block format compatible with the other ports
• Transaction and journal behavior matching the Go implementation
• Self-contained test runner with no external test dependency

Layout

cpp/
├── CMakeLists.txt
├── README.md
├── include/filefs/filefs.hpp
├── src/
│   ├── block.cpp
│   ├── copy.cpp
│   ├── exist.cpp
│   ├── fopen.cpp
│   ├── fopen_helpers.cpp
│   ├── journal.cpp
│   ├── mkdir.cpp
│   ├── mount.cpp
│   ├── move.cpp
│   ├── pwd.cpp
│   ├── readwrite.cpp
│   ├── readdir.cpp
│   ├── remove.cpp
│   ├── rename.cpp
│   ├── rmdir.cpp
│   ├── seek.cpp
│   ├── txn.cpp
│   ├── types.hpp
│   ├── util.cpp
│   └── util.hpp
└── tests/
    └── test_filefs.cpp

Build

cmake -S cpp -B cpp/build -DCMAKE_BUILD_TYPE=Release
cmake --build cpp/build -j
ctest --test-dir cpp/build --output-on-failure

CMakeLists.txt prefers /usr/bin/g++ automatically on environments where the default /usr/bin/c++ does not have a working standard library link setup.

Public API

The public header is include/filefs/filefs.hpp. The main entry point is filefs::FileSystem.

Example:

#include "filefs/filefs.hpp"

filefs::FileSystem fs;
filefs::FileSystem::mkfs("demo.ffs");
fs.mount("demo.ffs");
fs.mkdir("docs");

auto file = fs.fopen("/docs/note.txt", "w");
if (file) {
  const std::string text = "hello";
  fs.fwrite(*file, std::as_bytes(std::span(text.data(), text.size())));
  fs.fclose(*file);
}

Notes

• fread/fwrite provide span overloads plus void*/size/nmemb overloads for C-style parity.
• Mutating operations preserve the original return-code conventions from c/FileFS.h.
• File and Directory destructors mark handles closed, while explicit fclose and closedir remain available for parity.