feat: correctly report the size of symlinks

Also, symlinks don't use stat.

go.mod

 module github.com/ipfs/go-ipfs-files
 
 require golang.org/x/sys v0.0.0-20190302025703-b6889370fb10
+
+go 1.12

linkfile.go

 package files
 
 import (
-	"io"
-	"os"
 	"strings"
 )
 
 type Symlink struct {
 	Target string
-	stat   os.FileInfo
 
-	reader io.Reader
+	reader strings.Reader
 }
 
-func NewLinkFile(target string, stat os.FileInfo) File {
-	return &Symlink{
-		Target: target,
-		stat:   stat,
-		reader: strings.NewReader(target),
-	}
+func NewLinkFile(target string) File {
+	lf := &Symlink{Target: target}
+	lf.reader.Reset(lf.Target)
+	return lf
 }
 
 func (lf *Symlink) Close() error {
-	if c, ok := lf.reader.(io.Closer); ok {
-		return c.Close()
-	}
-
 	return nil
 }
 
@@ -34,15 +25,11 @@ func (lf *Symlink) Read(b []byte) (int, error) {
 }
 
 func (lf *Symlink) Seek(offset int64, whence int) (int64, error) {
-	if s, ok := lf.reader.(io.Seeker); ok {
-		return s.Seek(offset, whence)
-	}
-
-	return 0, ErrNotSupported
+	return lf.reader.Seek(offset, whence)
 }
 
 func (lf *Symlink) Size() (int64, error) {
-	return 0, ErrNotSupported
+	return lf.reader.Size(), nil
 }
 
 func ToSymlink(n Node) *Symlink {

multipartfile.go

@@ -99,7 +99,7 @@ func (w *multipartWalker) nextFile() (Node, error) {
 			return nil, err
 		}
 
-		return NewLinkFile(string(out), nil), nil
+		return NewLinkFile(string(out)), nil
 	default:
 		return &ReaderFile{
 			reader:  part,

serialfile.go

@@ -53,7 +53,7 @@ func NewSerialFile(path string, hidden bool, stat os.FileInfo) (Node, error) {
 		if err != nil {
 			return nil, err
 		}
-		return NewLinkFile(target, stat), nil
+		return NewLinkFile(target), nil
 	default:
 		return nil, fmt.Errorf("unrecognized file type for %s: %s", path, mode.String())
 	}