Fix nerdctl load stdin for pipes.

cmd/nerdctl/load.go

@@ -73,7 +73,7 @@ func loadAction(cmd *cobra.Command, _ []string) error {
 		if err != nil {
 			return err
 		}
-		if stdinStat.Size() == 0 {
+		if stdinStat.Size() == 0 && (stdinStat.Mode()&os.ModeNamedPipe) == 0 {
 			return errors.New("stdin is empty and input flag is not specified")
 		}
 	}
@@ -123,7 +123,7 @@ func loadImage(in io.Reader, cmd *cobra.Command, platMC platforms.MatchComparer,
 
 		// TODO: Show unpack status
 		if !quiet {
-			fmt.Fprintf(cmd.OutOrStdout(), "unpacking %s (%s)...", img.Name, img.Target.Digest)
+			fmt.Fprintf(cmd.OutOrStdout(), "unpacking %s (%s)...\n", img.Name, img.Target.Digest)
 		}
 		err = image.Unpack(ctx, sn)
 		if err != nil {
@@ -132,7 +132,7 @@ func loadImage(in io.Reader, cmd *cobra.Command, platMC platforms.MatchComparer,
 		if quiet {
 			fmt.Fprintln(cmd.OutOrStdout(), img.Target.Digest)
 		} else {
-			fmt.Fprintf(cmd.OutOrStdout(), "done\n")
+			fmt.Fprintf(cmd.OutOrStdout(), "Loaded image: %s", img.Name)
 		}
 	}
 

cmd/nerdctl/load_linux_test.go

@@ -0,0 +1,55 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/containerd/nerdctl/pkg/testutil"
+	"gotest.tools/v3/assert"
+)
+
+func TestLoadStdinFromPipe(t *testing.T) {
+	t.Parallel()
+	base := testutil.NewBase(t)
+
+	tmp := t.TempDir()
+	base.Cmd("pull", testutil.CommonImage).AssertOK()
+	base.Cmd("save", testutil.CommonImage, "-o", filepath.Join(tmp, "common.tar")).AssertOK()
+
+	loadCmd := strings.Join(base.Cmd("load").Command, " ")
+	output := filepath.Join(tmp, "output")
+
+	combined, err := exec.Command("sh", "-euxc", fmt.Sprintf("`cat %s/common.tar | %s > %s`", tmp, loadCmd, output)).CombinedOutput()
+	assert.NilError(t, err, "failed with error %s and combined output is %s", err, string(combined))
+	fb, err := os.ReadFile(output)
+	assert.NilError(t, err)
+
+	assert.Assert(t, strings.Contains(string(fb), fmt.Sprintf("Loaded image: %s", testutil.CommonImage)))
+	base.Cmd("images").AssertOutContains(strings.Split(testutil.CommonImage, ":")[0])
+}
+
+func TestLoadStdinEmpty(t *testing.T) {
+	t.Parallel()
+	base := testutil.NewBase(t)
+	base.Cmd("load").AssertFail()
+}