Allow extracton of a raw unixfs file (#284)

* Allow extracton of a raw unixfs file

Co-authored-by: Daniel Martí <[email protected]>

cmd/car/extract.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -20,6 +21,8 @@ import (
 	"github.com/urfave/cli/v2"
 )
 
+var ErrNotDir = fmt.Errorf("not a directory")
+
 // ExtractCar pulls files and directories out of a car
 func ExtractCar(c *cli.Context) error {
 	outputDir, err := os.Getwd()
@@ -92,7 +95,27 @@ func extractRoot(c *cli.Context, ls *ipld.LinkSystem, root cid.Cid, outputDir st
 		}
 	}
 	if err := extractDir(c, ls, ufn, outputResolvedDir, "/"); err != nil {
-		return fmt.Errorf("%s: %w", root, err)
+		if !errors.Is(err, ErrNotDir) {
+			return fmt.Errorf("%s: %w", root, err)
+		}
+		ufsData, err := pbnode.LookupByString("Data")
+		if err != nil {
+			return err
+		}
+		ufsBytes, err := ufsData.AsBytes()
+		if err != nil {
+			return err
+		}
+		ufsNode, err := data.DecodeUnixFSData(ufsBytes)
+		if err != nil {
+			return err
+		}
+		if ufsNode.DataType.Int() == data.Data_File || ufsNode.DataType.Int() == data.Data_Raw {
+			if err := extractFile(c, ls, pbnode, filepath.Join(outputResolvedDir, "unknown")); err != nil {
+				return err
+			}
+		}
+		return nil
 	}
 
 	return nil
@@ -208,7 +231,7 @@ func extractDir(c *cli.Context, ls *ipld.LinkSystem, n ipld.Node, outputRoot, ou
 		}
 		return nil
 	}
-	return fmt.Errorf("not a directory")
+	return ErrNotDir
 }
 
 func extractFile(c *cli.Context, ls *ipld.LinkSystem, n ipld.Node, outputName string) error {