Ensure shim propagates errors over gRPC correctly

This change wraps containerd's errdefs.ToGRPC function with one that
understands Go 1.13-style error wrapping style, which is used
pervasively throughout the shim. With this change, errors that have been
marked with, e.g., `errdefs.ErrNotFound`, will be correctly propagated
back to the containerd server.

1 files changed, 47 insertions, 0 deletions

diff --git a/pkg/shim/errors_test.go b/pkg/shim/errors_test.go
new file mode 100644
index 000000000..3c10866cc
--- /dev/null
+++ b/pkg/shim/errors_test.go
@@ -0,0 +1,47 @@
+// Copyright 2021 The gVisor 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
+//
+//     https://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 shim
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/containerd/containerd/errdefs"
+)
+
+func TestGRPCRoundTripsErrors(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		err  error
+		test func(err error) bool
+	}{
+		{
+			name: "passthrough",
+			err:  errdefs.ErrNotFound,
+			test: errdefs.IsNotFound,
+		},
+		{
+			name: "wrapped",
+			err:  fmt.Errorf("oh no: %w", errdefs.ErrNotFound),
+			test: errdefs.IsNotFound,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := errdefs.FromGRPC(errToGRPC(tc.err)); !tc.test(err) {
+				t.Errorf("got %+v", err)
+			}
+		})
+	}
+}