Add unit tests for create-symlinks hook

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

Author: cdesiniotis

cmd/nvidia-cdi-hook/create-symlinks/create-symlinks.go

@@ -107,6 +107,17 @@ func (m command) run(c *cli.Context, cfg *config) error {
 	return nil
 }
 
+// createLink creates a symbolic link in the specified container root.
+// This is equivalent to:
+//
+//	chroot {{ .containerRoot }} ln -s {{ .target }} {{ .link }}
+//
+// If the specified link already exists and points to the same target, this
+// operation is a no-op. If the link points to a different target, an error is
+// returned.
+//
+// Note that if the link path resolves to an absolute path oudside of the
+// specified root, this is treated as an absolute path in this root.
 func (m command) createLink(containerRoot string, targetPath string, link string) error {
 	linkPath := filepath.Join(containerRoot, link)
 

cmd/nvidia-cdi-hook/create-symlinks/create-symlinks_test.go

@@ -0,0 +1,96 @@
+package symlinks
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	testlog "github.com/sirupsen/logrus/hooks/test"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup/symlinks"
+)
+
+func TestCreateLinkRelativePath(t *testing.T) {
+	tmpDir := t.TempDir()
+	hostRoot := filepath.Join(tmpDir, "/host-root/")
+	containerRoot := filepath.Join(tmpDir, "/container-root")
+
+	require.NoError(t, makeFs(hostRoot))
+	require.NoError(t, makeFs(containerRoot, dirOrLink{path: "/lib/"}))
+
+	// nvidia-cdi-hook create-symlinks --link libfoo.so.1::/lib/libfoo.so
+	err := getTestCommand().createLink(containerRoot, "libfoo.so.1", "/lib/libfoo.so")
+	require.NoError(t, err)
+
+	target, err := symlinks.Resolve(filepath.Join(containerRoot, "/lib/libfoo.so"))
+	require.NoError(t, err)
+	require.Equal(t, "libfoo.so.1", target)
+}
+
+func TestCreateLinkAbsolutePath(t *testing.T) {
+	tmpDir := t.TempDir()
+	hostRoot := filepath.Join(tmpDir, "/host-root/")
+	containerRoot := filepath.Join(tmpDir, "/container-root")
+
+	require.NoError(t, makeFs(hostRoot))
+	require.NoError(t, makeFs(containerRoot, dirOrLink{path: "/lib/"}))
+
+	// nvidia-cdi-hook create-symlinks --link /lib/libfoo.so.1::/lib/libfoo.so
+	err := getTestCommand().createLink(containerRoot, "/lib/libfoo.so.1", "/lib/libfoo.so")
+	require.NoError(t, err)
+
+	target, err := symlinks.Resolve(filepath.Join(containerRoot, "/lib/libfoo.so"))
+	require.NoError(t, err)
+	require.Equal(t, "/lib/libfoo.so.1", target)
+}
+
+func TestCreateLinkAlreadyExists(t *testing.T) {
+	tmpDir := t.TempDir()
+	hostRoot := filepath.Join(tmpDir, "/host-root/")
+	containerRoot := filepath.Join(tmpDir, "/container-root")
+
+	require.NoError(t, makeFs(hostRoot))
+	require.NoError(t, makeFs(containerRoot, dirOrLink{path: "/lib/libfoo.so", target: "libfoo.so.1"}))
+
+	// nvidia-cdi-hook create-symlinks --link libfoo.so.1::/lib/libfoo.so
+	err := getTestCommand().createLink(containerRoot, "libfoo.so.1", "/lib/libfoo.so")
+	require.Error(t, err)
+	target, err := symlinks.Resolve(filepath.Join(containerRoot, "lib/libfoo.so"))
+	require.NoError(t, err)
+	require.Equal(t, "libfoo.so.1", target)
+}
+
+type dirOrLink struct {
+	path   string
+	target string
+}
+
+func makeFs(tmpdir string, fs ...dirOrLink) error {
+	if err := os.MkdirAll(tmpdir, 0o755); err != nil {
+		return err
+	}
+	for _, s := range fs {
+		s.path = filepath.Join(tmpdir, s.path)
+		if s.target == "" {
+			_ = os.MkdirAll(s.path, 0o755)
+			continue
+		}
+		if err := os.MkdirAll(filepath.Dir(s.path), 0o755); err != nil {
+			return err
+		}
+		if err := os.Symlink(s.target, s.path); err != nil && !os.IsExist(err) {
+			return err
+		}
+	}
+	return nil
+}
+
+// getTestCommand creates a command for running tests against.
+func getTestCommand() *command {
+	logger, _ := testlog.NewNullLogger()
+	return &command{
+		logger: logger,
+	}
+}