Handle hook arguments for creation of symlinks

Signed-off-by: Christopher Desiniotis <cdesiniotis@nvidia.com>

pkg/nvcdi/transform/no-op.go

@@ -0,0 +1,35 @@
+/**
+# Copyright (c) NVIDIA CORPORATION.  All rights reserved.
+#
+# 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 transform
+
+import (
+	"github.com/container-orchestrated-devices/container-device-interface/specs-go"
+)
+
+type noop struct{}
+
+var _ Transformer = (*noop)(nil)
+
+// NewNoopTransformer returns a no-op transformer
+func NewNoopTransformer() Transformer {
+	return noop{}
+}
+
+// Transform is a no-op
+func (n noop) Transform(spec *specs.Spec) error {
+	return nil
+}

pkg/nvcdi/transform/root.go

@@ -32,8 +32,13 @@ type rootTransformer struct {
 var _ Transformer = (*rootTransformer)(nil)
 
 // NewRootTransformer creates a new transformer for modifying
-// the root for paths in a CDI spec.
+// the root for paths in a CDI spec. If both roots are identical,
+// this tranformer is a no-op.
 func NewRootTransformer(root string, targetRoot string) Transformer {
+	if root == targetRoot {
+		return NewNoopTransformer()
+	}
+
 	t := rootTransformer{
 		root:       root,
 		targetRoot: targetRoot,
@@ -69,10 +74,23 @@ func (t rootTransformer) applyToEdits(edits *specs.ContainerEdits) error {
 	for i, hook := range edits.Hooks {
 		hook.Path = t.transformPath(hook.Path)
 
-		// TODO: The args need more attention. For the hooks that create symlinks we would have to transform these too.
 		var args []string
 		for _, arg := range hook.Args {
+			if !strings.Contains(arg, "::") {
 				args = append(args, t.transformPath(arg))
+				continue
+			}
+
+			// For the 'create-symlinks' hook, special care is taken for the
+			// '--link' flag argument which takes the form <target>::<link>.
+			// Both paths, the target and link paths, are transformed.
+			split := strings.Split(arg, "::")
+			if len(split) != 2 {
+				return fmt.Errorf("unexpected number of '::' separators in hook argument")
+			}
+			split[0] = t.transformPath(split[0])
+			split[1] = t.transformPath(split[1])
+			args = append(args, strings.Join(split, "::"))
 		}
 		hook.Args = args
 		edits.Hooks[i] = hook

pkg/nvcdi/transform/root_test.go

@@ -98,18 +98,54 @@ func TestRootTransformer(t *testing.T) {
 			spec: &specs.Spec{
 				ContainerEdits: specs.ContainerEdits{
 					Hooks: []*specs.Hook{
-						{Path: "/root/usr/bin/nvidia-ctk"},
-						{Path: "/target-root/usr/bin/nvidia-ctk"},
-						{Path: "/different-root/usr/bin/nvidia-ctk"},
+						{
+							Path: "/root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/root/path/to/target::/root/path/to/link",
+							},
+						},
+						{
+							Path: "/target-root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/target-root/path/to/target::/target-root/path/to/link",
+							},
+						},
+						{
+							Path: "/different-root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/different-root/path/to/target::/different-root/path/to/link",
+							},
+						},
 					},
 				},
 			},
 			expectedSpec: &specs.Spec{
 				ContainerEdits: specs.ContainerEdits{
 					Hooks: []*specs.Hook{
-						{Path: "/target-root/usr/bin/nvidia-ctk"},
-						{Path: "/target-root/usr/bin/nvidia-ctk"},
-						{Path: "/different-root/usr/bin/nvidia-ctk"},
+						{
+							Path: "/target-root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/target-root/path/to/target::/target-root/path/to/link",
+							},
+						},
+						{
+							Path: "/target-root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/target-root/path/to/target::/target-root/path/to/link",
+							},
+						},
+						{
+							Path: "/different-root/usr/bin/nvidia-ctk",
+							Args: []string{
+								"--link",
+								"/different-root/path/to/target::/different-root/path/to/link",
+							},
+						},
 					},
 				},
 			},