load cmd support gzip and bzip2

Signed-off-by: ye.sijun <[email protected]>

cmd/nerdctl/load.go

@@ -17,6 +17,10 @@
 package main
 
 import (
+	"bufio"
+	"bytes"
+	"compress/bzip2"
+	"compress/gzip"
 	"errors"
 	"fmt"
 	"io"
@@ -68,6 +72,16 @@ func loadAction(cmd *cobra.Command, args []string) error {
 		in = f
 	}
 
+	inbuf := bufio.NewReader(in)
+	buff, _ := inbuf.Peek(3)
+	if bytes.HasPrefix(buff, []byte("\x1f\x8b")) {
+		in, _ = gzip.NewReader(inbuf)
+	} else if bytes.HasPrefix(buff, []byte("\x42\x5a\x68")) {
+		in = bzip2.NewReader(inbuf)
+	} else {
+		in = inbuf
+	}
+
 	allPlatforms, err := cmd.Flags().GetBool("all-platforms")
 	if err != nil {
 		return err