Allow locator to be marked as optional

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

cmd/nvidia-ctk/cdi/generate/common.go

@@ -30,7 +30,10 @@ import (
 func NewCommonDiscoverer(logger *logrus.Logger, root string, nvidiaCTKPath string, nvmllib nvml.Interface) (discover.Discover, error) {
 	metaDevices := discover.NewDeviceDiscoverer(
 		logger,
-		lookup.NewCharDeviceLocator(logger, root),
+		lookup.NewCharDeviceLocator(
+			lookup.WithLogger(logger),
+			lookup.WithRoot(root),
+		),
 		root,
 		[]string{
 			"/dev/nvidia-modeset",

internal/discover/char_devices.go

@@ -28,7 +28,10 @@ var _ Discover = (*charDevices)(nil)
 
 // NewCharDeviceDiscoverer creates a discoverer which locates the specified set of device nodes.
 func NewCharDeviceDiscoverer(logger *logrus.Logger, devices []string, root string) Discover {
-	locator := lookup.NewCharDeviceLocator(logger, root)
+	locator := lookup.NewCharDeviceLocator(
+		lookup.WithLogger(logger),
+		lookup.WithRoot(root),
+	)
 
 	return NewDeviceDiscoverer(logger, locator, root, devices)
 }

internal/discover/csv.go

@@ -35,7 +35,7 @@ func NewFromCSVFiles(logger *logrus.Logger, files []string, root string) (Discov
 
 	symlinkLocator := lookup.NewSymlinkLocator(logger, root)
 	locators := map[csv.MountSpecType]lookup.Locator{
-		csv.MountSpecDev: lookup.NewCharDeviceLocator(logger, root),
+		csv.MountSpecDev: lookup.NewCharDeviceLocator(lookup.WithLogger(logger), lookup.WithRoot(root)),
 		csv.MountSpecDir: lookup.NewDirectoryLocator(logger, root),
 		// Libraries and symlinks are handled in the same way
 		csv.MountSpecLib: symlinkLocator,

internal/discover/graphics.go

@@ -181,7 +181,10 @@ func (d drmDevicesByPath) getSpecificLinkArgs(devices []Device) ([]string, error
 func newDRMDeviceDiscoverer(logger *logrus.Logger, devices image.VisibleDevices, root string) (Discover, error) {
 	allDevices := NewDeviceDiscoverer(
 		logger,
-		lookup.NewCharDeviceLocator(logger, root),
+		lookup.NewCharDeviceLocator(
+			lookup.WithLogger(logger),
+			lookup.WithRoot(root),
+		),
 		root,
 		[]string{
 			"/dev/dri/card*",

internal/lookup/device.go

@@ -19,8 +19,6 @@ package lookup
 import (
 	"fmt"
 	"os"
-
-	"github.com/sirupsen/logrus"
 )
 
 const (
@@ -29,13 +27,14 @@ const (
 
 // NewCharDeviceLocator creates a Locator that can be used to find char devices at the specified root. A logger is
 // also specified.
-func NewCharDeviceLocator(logger *logrus.Logger, root string) Locator {
+func NewCharDeviceLocator(opts ...Option) Locator {
-	return NewFileLocator(
+	opts = append(opts,
-		WithLogger(logger),
-		WithRoot(root),
 		WithSearchPaths("", devRoot),
 		WithFilter(assertCharDevice),
 	)
+	return NewFileLocator(
+		opts...,
+	)
 }
 
 // assertCharDevice checks whether the specified path is a char device and returns an error if this is not the case.

internal/lookup/device_test.go

@@ -47,7 +47,10 @@ func TestCharDeviceLocator(t *testing.T) {
 
 	for i, tc := range testCases {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
-			f := NewCharDeviceLocator(logger, tc.root).(*file)
+			f := NewCharDeviceLocator(
+				WithLogger(logger),
+				WithRoot(tc.root),
+			).(*file)
 
 			require.EqualValues(t, tc.expectedPrefixes, f.prefixes)
 		})

internal/lookup/file.go

@@ -27,11 +27,12 @@ import (
 // file can be used to locate file (or file-like elements) at a specified set of
 // prefixes. The validity of a file is determined by a filter function.
 type file struct {
-	logger   *log.Logger
+	logger     *log.Logger
-	root     string
+	root       string
-	prefixes []string
+	prefixes   []string
-	filter   func(string) error
+	filter     func(string) error
-	count    int
+	count      int
+	isOptional bool
 }
 
 // Option defines a function for passing options to the NewFileLocator() call
@@ -73,6 +74,14 @@ func WithCount(count int) Option {
 	}
 }
 
+// WithOptional sets the optional flag for the file locator
+// If the optional flag is set, the locator will not return an error if the file is not found.
+func WithOptional(optional bool) Option {
+	return func(f *file) {
+		f.isOptional = optional
+	}
+}
+
 // NewFileLocator creates a Locator that can be used to find files with the specified options.
 func NewFileLocator(opts ...Option) Locator {
 	return newFileLocator(opts...)
@@ -158,7 +167,7 @@ visit:
 		}
 	}
 
-	if len(filenames) == 0 {
+	if !p.isOptional && len(filenames) == 0 {
 		return nil, fmt.Errorf("pattern %v not found", pattern)
 	}
 	return filenames, nil