// Every vfs.Filesystem could be easily wrapped
func ExampleReadOnlyOS() {
// Create a readonly vfs accessing the filesystem of the underlying OS
roFS := vfs.ReadOnly(vfs.OS())
// Mkdir is disabled on ReadOnly vfs, will return vfs.ErrReadOnly
// See vfs.ReadOnly for all disabled operations
err := roFS.Mkdir("/tmp/vfs", 0777)
if err != nil {
fatal("Error creating directory: %s\n", err)
}
// OpenFile is controlled to support read-only functionality. os.O_CREATE or os.O_APPEND will fail.
// Flags like os.O_RDWR are supported but the returned file is protected e.g. from Write(..).
f, err := roFS.OpenFile("/tmp/vfs/example.txt", os.O_RDWR, 0)
if err != nil {
fatal("Could not create file: %s\n", err)
}
defer f.Close()
// Will fail and return vfs.ErrReadOnly
_, err = f.Write([]byte("VFS working on your filesystem"))
if err != nil {
fatal("Could not write file on read only filesystem: %s", err)
}
}
func Example() {
// 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)
}