Restructure for 1.16 io/fs interface

fs.go

@@ -0,0 +1,89 @@
+package squashfs
+
+import (
+	"io/fs"
+	"path"
+	"strings"
+
+	"github.com/CalebQ42/squashfs/internal/directory"
+)
+
+type FS struct {
+	r       *Reader
+	parent  *FS
+	entries []*directory.Entry
+}
+
+func (f FS) Open(name string) (fs.File, error) {
+	if !fs.ValidPath(name) {
+		return nil, &fs.PathError{
+			Op:   "open",
+			Path: name,
+			Err:  fs.ErrInvalid,
+		}
+	}
+	name = path.Clean(strings.TrimPrefix(name, "/"))
+	split := strings.Split(name, "/")
+	for i := 0; i < len(f.entries); i++ {
+		if match, _ := path.Match(split[0], f.entries[i].Name); match {
+			if len(split) == 1 {
+				return f.r.newFileFromDirEntry(f.entries[i], &f)
+			}
+			sub, err := f.Sub(split[0])
+			if err != nil {
+				if pathErr, ok := err.(*fs.PathError); ok {
+					pathErr.Op = "open"
+					pathErr.Path = name
+					return nil, err
+				}
+				return nil, &fs.PathError{
+					Op:   "open",
+					Path: name,
+					Err:  err,
+				}
+			}
+			fil, err := sub.Open(strings.Join(split[1:], "/"))
+			if err != nil {
+				if pathErr, ok := err.(*fs.PathError); ok {
+					if pathErr.Err == fs.ErrNotExist {
+						continue
+					}
+					pathErr.Op = "open"
+					pathErr.Path = name
+					return nil, err
+				}
+				return nil, &fs.PathError{
+					Op:   "open",
+					Path: name,
+					Err:  err,
+				}
+			}
+			return fil, nil
+		}
+	}
+	return nil, &fs.PathError{
+		Op:   "open",
+		Path: name,
+		Err:  fs.ErrNotExist,
+	}
+}
+
+func (f FS) Glob(pattern string) ([]string, error) {
+	return nil, nil
+}
+
+func (f FS) ReadDir(name string) ([]DirEntry, error) {
+	return nil, nil
+}
+
+func (f FS) ReadFile(name string) ([]byte, error) {
+	return nil, nil
+}
+
+func (f FS) Stat(name string) ([]byte, error) {
+	return nil, nil
+}
+
+func (f FS) Sub(dir string) (fs.FS, error) {
+	return nil, nil
+}