Resolve LDConfig path passed to nvidia-container-cli

Instead of relying solely on a static config, we resolve the path
to ldconfig. The path is checked for existence and a .real suffix is preferred.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

internal/config/cli.go

@@ -16,6 +16,11 @@
 
 package config
 
+import (
+	"os"
+	"strings"
+)
+
 // ContainerCLIConfig stores the options for the nvidia-container-cli
 type ContainerCLIConfig struct {
 	Root        string   `toml:"root"`
@@ -31,3 +36,27 @@ type ContainerCLIConfig struct {
 	User      string `toml:"user"`
 	Ldconfig  string `toml:"ldconfig"`
 }
+
+// NormalizeLDConfigPath returns the resolved path of the configured LDConfig binary.
+// This is only done for host LDConfigs and is required to handle systems where
+// /sbin/ldconfig is a wrapper around /sbin/ldconfig.real.
+func (c *ContainerCLIConfig) NormalizeLDConfigPath() string {
+	return NormalizeLDConfigPath(c.Ldconfig)
+}
+
+// NormalizeLDConfigPath returns the resolved path of the configured LDConfig binary.
+// This is only done for host LDConfigs and is required to handle systems where
+// /sbin/ldconfig is a wrapper around /sbin/ldconfig.real.
+func NormalizeLDConfigPath(path string) string {
+	if !strings.HasPrefix(path, "@") {
+		return path
+	}
+
+	trimmedPath := strings.TrimSuffix(strings.TrimPrefix(path, "@"), ".real")
+	// If the .real path exists, we return that.
+	if _, err := os.Stat(trimmedPath + ".real"); err == nil {
+		return "@" + trimmedPath + ".real"
+	}
+	// If the .real path does not exists (or cannot be read) we return the non-.real path.
+	return "@" + trimmedPath
+}

internal/config/cli_test.go

@@ -0,0 +1,83 @@
+/**
+# Copyright 2023 NVIDIA CORPORATION
+#
+# 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 config
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNormalizeLDConfigPath(t *testing.T) {
+	testDir := t.TempDir()
+
+	f, err := os.Create(filepath.Join(testDir, "exists.real"))
+	require.NoError(t, err)
+	_ = f.Close()
+
+	testCases := []struct {
+		description string
+		ldconfig    string
+		expected    string
+	}{
+		{
+			description: "empty input",
+		},
+		{
+			description: "non-host with .real suffix returns as is",
+			ldconfig:    "/some/path/ldconfig.real",
+			expected:    "/some/path/ldconfig.real",
+		},
+		{
+			description: "non-host without .real suffix returns as is",
+			ldconfig:    "/some/path/ldconfig",
+			expected:    "/some/path/ldconfig",
+		},
+		{
+			description: "host .real file exists is returned",
+			ldconfig:    "@" + filepath.Join(testDir, "exists.real"),
+			expected:    "@" + filepath.Join(testDir, "exists.real"),
+		},
+		{
+			description: "host resolves .real file",
+			ldconfig:    "@" + filepath.Join(testDir, "exists"),
+			expected:    "@" + filepath.Join(testDir, "exists.real"),
+		},
+		{
+			description: "host .real file not exists strips suffix",
+			ldconfig:    "@/does/not/exist.real",
+			expected:    "@/does/not/exist",
+		},
+		{
+			description: "host file returned as is if no .real file exsits",
+			ldconfig:    "@/does/not/exist",
+			expected:    "@/does/not/exist",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			c := ContainerCLIConfig{
+				Ldconfig: tc.ldconfig,
+			}
+
+			require.Equal(t, tc.expected, c.NormalizeLDConfigPath())
+		})
+	}
+}

internal/config/config.go

@@ -122,10 +122,7 @@ func GetDefault() (*Config, error) {
 }
 
 func getLdConfigPath() string {
-	if _, err := os.Stat("/sbin/ldconfig.real"); err == nil {
-		return "@/sbin/ldconfig.real"
-	}
-	return "@/sbin/ldconfig"
+	return NormalizeLDConfigPath("@/sbin/ldconfig")
 }
 
 // getCommentedUserGroup returns whether the nvidia-container-cli user and group config option should be commented.