feat: wip files.Node to fs.File adapter

Author: Alan Shaw

fs/adapter/unixfs.go

@@ -0,0 +1,113 @@
+package adapter
+
+import (
+	"errors"
+	"io/fs"
+	"time"
+
+	files "github.com/ipfs/go-ipfs-files"
+)
+
+type unixFsFile struct {
+	path string
+	info fs.FileInfo
+	node files.Node
+}
+
+// NewFile creates an fs.File that is backed by an IPFS files.Node.
+func NewFile(name string, node files.Node) (fs.File, error) {
+	size, err := node.Size()
+	if err != nil {
+		return nil, err
+	}
+	_, isDir := node.(files.Directory)
+	return &unixFsFile{
+		info: &unixFsFileInfo{
+			name:    name,
+			size:    size,
+			modTime: time.Now(),
+			isDir:   isDir,
+		},
+		node: node,
+	}, nil
+}
+
+func (f *unixFsFile) Stat() (fs.FileInfo, error) {
+	return f.info, nil
+}
+
+func (f *unixFsFile) Read(p []byte) (int, error) {
+	if ff, ok := f.node.(files.File); ok {
+		return ff.Read(p)
+	}
+	return 0, errors.New("file not readable")
+}
+
+func (f *unixFsFile) Close() error {
+	return f.node.Close()
+}
+
+func (f *unixFsFile) ReadDir(n int) ([]fs.DirEntry, error) {
+	fd, isDir := f.node.(files.Directory)
+	if !isDir {
+		return nil, errors.New("not a directory")
+	}
+
+	var ents []fs.DirEntry
+	it := fd.Entries()
+	for it.Next() {
+		node := it.Node()
+		NewFile(it.Name(), node)
+	}
+	if it.Err() != nil {
+		return nil, it.Err()
+	}
+
+	fl := len(d.files)
+	if n <= 0 || n > fl {
+		n = fl
+	}
+	var ents []fs.DirEntry
+	for i := 0; i < n; i++ {
+		inf, err := d.files[i].Stat()
+		if err != nil {
+			return nil, err
+		}
+		ents = append(ents, &DirEntry{file: d.files[i], info: inf})
+	}
+	return ents, nil
+}
+
+type unixFsFileInfo struct {
+	name    string
+	size    int64
+	modTime time.Time
+	isDir   bool
+}
+
+func (i *unixFsFileInfo) Name() string {
+	return i.name
+}
+
+func (i *unixFsFileInfo) Size() int64 {
+	return i.size
+}
+
+func (i *unixFsFileInfo) Mode() fs.FileMode {
+	if i.isDir {
+		return fs.ModeDir | 0555
+	}
+	return fs.ModePerm
+}
+
+func (i *unixFsFileInfo) ModTime() time.Time {
+	return i.modTime
+}
+
+func (i *unixFsFileInfo) IsDir() bool {
+	return i.Mode().IsDir()
+}
+
+func (i *unixFsFileInfo) Sys() interface{} {
+	return nil
+}