vfs for golang

vfs is library to support virtual filesystems. It provides basic abstractions of filesystems and implementations, like OS accessing the file system of the underlying OS and memfs a full filesystem in-memory.

Usage

$ go get github.com/blang/vfs

Note: Always vendor your dependencies or fix on a specific version tag.

import github.com/blang/vfs

// Create a vfs accessing the filesystem of the underlying OS
var osfs vfs.Filesystem = vfs.OS()
osfs.Mkdir("/tmp", 0777)

// Make the filesystem read-only:
osfs = vfs.ReadOnly(osfs) // Simply wrap filesystems to change its behaviour

// os.O_CREATE will fail and return vfs.ErrReadOnly
// os.O_RDWR is supported but Write(..) on the file is disabled
f, _ := osfs.OpenFile("/tmp/example.txt", os.O_RDWR, 0)

// Return vfs.ErrReadOnly
_, err := f.Write([]byte("Write on readonly fs?"))
if err != nil {
    fmt.Errorf("Filesystem is read only!\n")
}

// Create a fully writable filesystem in memory
mfs := memfs.Create()
mfs.Mkdir("/root", 0777)

// Create a vfs supporting mounts
// The root fs is accessing the filesystem of the underlying OS
fs := mountfs.Create(osfs)

// Mount a memfs inside /memfs
// /memfs may not exist
fs.Mount(mfs, "/memfs")

// This will create /testdir inside the memfs
fs.Mkdir("/memfs/testdir", 0777)

// This would create /tmp/testdir inside your OS fs
// But the rootfs `osfs` is read-only
fs.Mkdir("/tmp/testdir", 0777)

Check detailed examples below. Also check the GoDocs.

Why should I use this lib?

• Only Stdlib
• (Nearly) Fully tested (Coverage >90%)
• Easy to create your own filesystem
• Mock a full filesystem for testing (or use included memfs)
• Compose/Wrap Filesystems ReadOnly(OS()) and write simple Wrappers
• Many features, see GoDocs and examples below

Features and Examples

• OS Filesystem support
• ReadOnly Wrapper
• DummyFS for quick mocking
• MemFS - full in-memory filesystem
• MountFS - support mounts across filesystems

Current state: ALPHA

While the functionality is quite stable and heavily tested, interfaces are subject to change.

You need more/less abstraction? Let me know by creating a Issue, thank you.

Motivation

I simply couldn't find any lib supporting this wide range of variation and adaptability.

Contribution

Feel free to make a pull request. For bigger changes create a issue first to discuss about it.

License

See LICENSE file.