FVNever.AppDirs

FVNever.AppDirs

A .NET library providing XDG-like base-directory resolution for application config, data, cache, and state directories in a cross-platform way.

Motivation

Many applications need to store files that outlive a single run — logs, command history, recent-files lists, window layout — but the correct place for them is different on each operating system, and encoded in platform-specific conventions that are easy to get subtly wrong. FVNever.AppDirs encapsulates these conventions so that you never assemble platform paths by hand.

Different ecosystems have different conventions on where to store different kinds of data:

• Linux has XDG Base Directory Specification,
• Windows provides Known Folders,
• macOS documents its Standard Directories.

This library brings access to these standards from .NET, in a portable manner (so you can find a location for any supported kind of data for every supported operating system).

Usage

using FVNever.AppDirs;

var dirs = new ApplicationDirectories("MyApp");
AbsolutePath state = dirs.StateDirectory();
// Windows: %LOCALAPPDATA%\MyApp\.state
// macOS:   throws unless a bundle identifier or compatibility mode is supplied (see below)
// Linux:   $XDG_STATE_HOME/MyApp (or ~/.local/state/MyApp)

AbsolutePath roamable = dirs.StateDirectory(roamable: true);
// Windows: %APPDATA%\MyApp\.state (the Roaming profile)
// macOS:   throws unless a bundle identifier or compatibility mode is supplied (see below)
// Linux:   $XDG_CONFIG_HOME/MyApp/.roamableState (or ~/.config/MyApp/.roamableState)

StateDirectory is a method taking an optional bool roamable = false. The default (roamable: false) resolves a machine-local, non-roaming location; roamable: true resolves a location intended to roam or sync between machines (for example the Windows Roaming profile).

You can also supply optional identity data to shape the per-OS paths:

var dirs = new ApplicationDirectories(
    "MyApp",
    vendorName: "Acme",
    macOsBundleIdentifier: "com.acme.MyApp",
    allowCompatMode: true);
AbsolutePath state = dirs.StateDirectory();
// Windows: %LOCALAPPDATA%\Acme\MyApp\.state       (vendorName is an intermediate segment)
// macOS:   ~/Library/Application Support/com.acme.MyApp/.state

• vendorName (optional): used as an intermediate path segment on Windows, and to reconstruct the macOS bundle identifier in compatibility mode.
• macOsBundleIdentifier (optional): used verbatim as the macOS Application Support segment.
• allowCompatMode (optional): when no explicit macOsBundleIdentifier is given, reconstructs it as <Vendor>.<App> (or <App>); otherwise macOS resolution throws instead of guessing.

All three inputs are ignored on Linux.

Both variants of StateDirectory return a leaf directory: a location your application writes into directly. AppDirs guarantees no leaf directory contains another AppDirs-generated leaf on any OS. See the documentation site for larger examples and the full explanation of the leaf/base convention and the fail-fast behavior.

References

The per-OS mappings follow the authoritative platform conventions:

• XDG Base Directory Specification (Linux)
• Known Folders (Windows)
• macOS Standard Directories (macOS)

Documentation

• Project Documentation Site (API Reference)
• Changelog
• Contributor Guide
• Maintainer Guide

License

The project is distributed under the terms of the MIT license.

The license indication in the project's sources is compliant with the REUSE specification v3.3.