skip directories when resolving the nvml library path

cmd/nvidia-device-plugin/root.go

@@ -67,6 +67,12 @@ func (r root) tryResolveLibrary(libraryName string) string {
 		if err != nil {
 			continue
 		}
+		// EvalSymlinks succeeds for directories too, so a directory named after
+		// the library in an earlier search path would shadow the real one.
+		info, err := os.Stat(resolved)
+		if err != nil || !info.Mode().IsRegular() {
+			continue
+		}
 		return resolved
 	}
 

cmd/nvidia-device-plugin/root_test.go

@@ -0,0 +1,96 @@
+/**
+# 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 main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestTryResolveLibrary(t *testing.T) {
+	const libraryName = "libnvidia-ml.so.1"
+
+	testCases := []struct {
+		description string
+		// dirs, files and target are created relative to the test root before resolving.
+		dirs   []string
+		files  []string
+		link   string
+		target string
+		// expected is the resolved path relative to the test root, or "" if
+		// the input library name is expected to be returned as is.
+		expected string
+	}{
+		{
+			description: "library in first search path",
+			files:       []string{"usr/lib64/" + libraryName},
+			expected:    "usr/lib64/" + libraryName,
+		},
+		{
+			description: "directory in earlier search path does not shadow library",
+			dirs:        []string{"usr/lib64/" + libraryName},
+			files:       []string{"usr/lib/x86_64-linux-gnu/" + libraryName},
+			expected:    "usr/lib/x86_64-linux-gnu/" + libraryName,
+		},
+		{
+			description: "only directories found",
+			dirs:        []string{"usr/lib64/" + libraryName},
+			expected:    "",
+		},
+		{
+			description: "symlink to a library is resolved",
+			files:       []string{"usr/lib/x86_64-linux-gnu/" + libraryName + ".580.126.09"},
+			link:        "usr/lib64/" + libraryName,
+			target:      "usr/lib/x86_64-linux-gnu/" + libraryName + ".580.126.09",
+			expected:    "usr/lib/x86_64-linux-gnu/" + libraryName + ".580.126.09",
+		},
+		{
+			description: "library not found",
+			expected:    "",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			rootDir := t.TempDir()
+
+			for _, d := range tc.dirs {
+				require.NoError(t, os.MkdirAll(filepath.Join(rootDir, d), 0755))
+			}
+			for _, f := range tc.files {
+				require.NoError(t, os.MkdirAll(filepath.Dir(filepath.Join(rootDir, f)), 0755))
+				require.NoError(t, os.WriteFile(filepath.Join(rootDir, f), []byte{}, 0644))
+			}
+			if tc.link != "" {
+				require.NoError(t, os.MkdirAll(filepath.Dir(filepath.Join(rootDir, tc.link)), 0755))
+				require.NoError(t, os.Symlink(filepath.Join(rootDir, tc.target), filepath.Join(rootDir, tc.link)))
+			}
+
+			r := root(rootDir)
+			resolved := r.tryResolveLibrary(libraryName)
+
+			if tc.expected == "" {
+				require.Equal(t, libraryName, resolved)
+				return
+			}
+			require.Equal(t, filepath.Join(rootDir, tc.expected), resolved)
+		})
+	}
+}