WFS

Writable filesystem abstraction in Go.

WFS provides an interface that abstracts the OS filesystem, enabling support for custom writable filesystems and improved testing.

Why Use WFS?

The Go standard library provides powerful filesystem primitives, but handling files across different storage backends can be cumbersome. While fs.FS is a flexible and useful abstraction, it is inherently read-only by design. wfs extends this concept by providing a writable filesystem interface, allowing seamless integration with custom backends, such as in-memory filesystems for testing.

Installation

go get github.com/eriicafes/wfs

Usage

wfs provides interfaces and top-level functions for working with files and directories.

Create an OS writable filesystem or an in-memory writable filesystem for use in tests.

// os filesystem
fsys := wfs.OS()

// in-memory filesystem
fsys := wfs.Map(fstest.MapFS{})

Interfaces

FS

A wfs.FS implements fs.FS, wfs.FileFS and wfs.DirFS. A wfs.FS implementation can read, write, create and delete files and directories.

type FS interface {
    fs.FS
    FileFS
    DirFS
}

FileFS

A wfs.FileFS implementation can create, read, write and delete files.

type FileFS interface {
    OpenFile(name string, flag int, perm fs.FileMode) (File, error)
    Rename(oldpath, newpath string) error
    Remove(name string) error
    RemoveAll(path string) error
}

DirFS

A wfs.DirFS implementation can create directories.

type DirFS interface {
    Mkdir(name string, perm fs.FileMode) error
    MkdirAll(path string, perm fs.FileMode) error
}

File

A wfs.File implementation extends fs.File with additional methods.

type File interface {
    fs.File
    io.WriteSeeker
    io.ReaderAt
    io.WriterAt
    Truncate(size int64) error
    Name() string
}

Top-level Functions

Create

Creates a new file or truncates an existing one, returning a writable file handle.

f, err := wfs.Create(fsys, "filename")

WriteFile

Writes data to a file, creating or replacing it while preserving file permissions.

err := wfs.WriteFile(fsys, "filename", []byte(`data`), fs.ModePerm)