Extract device information from host path if possible

This change extracts the required information from the host device
node if available.

Signed-off-by: Evan Lezar <[email protected]>

Author: elezar

go.mod

@@ -29,6 +29,7 @@ require (
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/moby/sys/capability v0.4.0 // indirect
+	github.com/opencontainers/cgroups v0.0.4 // indirect
 	github.com/opencontainers/runtime-tools v0.9.1-0.20251114084447-edf4cb3d2116 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.11.0 // indirect

go.sum

@@ -34,6 +34,8 @@ github.com/moby/sys/reexec v0.1.0 h1:RrBi8e0EBTLEgfruBOFcxtElzRGTEUkeIFaVXgU7wok
 github.com/moby/sys/reexec v0.1.0/go.mod h1:EqjBg8F3X7iZe5pU6nRZnYCMUTXoxsjiIfHup5wYIN8=
 github.com/moby/sys/symlink v0.3.0 h1:GZX89mEZ9u53f97npBy4Rc3vJKj7JBDj/PN2I22GrNU=
 github.com/moby/sys/symlink v0.3.0/go.mod h1:3eNdhduHmYPcgsJtZXW1W4XUJdZGBIkttZ8xKqPUJq0=
+github.com/opencontainers/cgroups v0.0.4 h1:XVj8P/IHVms/j+7eh8ggdkTLAxjz84ZzuFyGoE28DR4=
+github.com/opencontainers/cgroups v0.0.4/go.mod h1:s8lktyhlGUqM7OSRL5P7eAW6Wb+kWPNvt4qvVfzA5vs=
 github.com/opencontainers/runc v1.3.3 h1:qlmBbbhu+yY0QM7jqfuat7M1H3/iXjju3VkP9lkFQr4=
 github.com/opencontainers/runc v1.3.3/go.mod h1:D7rL72gfWxVs9cJ2/AayxB0Hlvn9g0gaF1R7uunumSI=
 github.com/opencontainers/runtime-spec v1.3.0 h1:YZupQUdctfhpZy3TM39nN9Ika5CBWT5diQ8ibYCRkxg=

internal/edits/device.go

@@ -20,6 +20,8 @@ import (
 	"tags.cncf.io/container-device-interface/pkg/cdi"
 	"tags.cncf.io/container-device-interface/specs-go"
 
+	"github.com/opencontainers/runc/libcontainer/devices"
+
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/discover"
 )
 
@@ -43,19 +45,37 @@ func (d device) toEdits() (*cdi.ContainerEdits, error) {
 // toSpec converts a discovered Device to a CDI Spec Device. Note
 // that missing info is filled in when edits are applied by querying the Device node.
 func (d device) toSpec() (*specs.DeviceNode, error) {
+	s := d.fromPathOrDefault()
 	// The HostPath field was added in the v0.5.0 CDI specification.
 	// The cdi package uses strict unmarshalling when loading specs from file causing failures for
 	// unexpected fields.
 	// Since the behaviour for HostPath == "" and HostPath == Path are equivalent, we clear HostPath
 	// if it is equal to Path to ensure compatibility with the widest range of specs.
-	hostPath := d.HostPath
-	if hostPath == d.Path {
-		hostPath = ""
+	if s.HostPath == d.Path {
+		s.HostPath = ""
 	}
-	s := specs.DeviceNode{
-		HostPath: hostPath,
-		Path:     d.Path,
+
+	return s, nil
+}
+
+// fromPathOrDefault attempts to return the returns the information about the
+// CDI device from the specified host path.
+// If this fails a minimal device is returned so that this information can be
+// queried by the container runtime such as containerd.
+func (d device) fromPathOrDefault() *specs.DeviceNode {
+	dn, err := devices.DeviceFromPath(d.HostPath, "rwm")
+	if err != nil {
+		return &specs.DeviceNode{
+			HostPath: d.HostPath,
+			Path:     d.Path,
+		}
 	}
 
-	return &s, nil
+	return &specs.DeviceNode{
+		HostPath: d.HostPath,
+		Path:     d.Path,
+		Major:    dn.Major,
+		Minor:    dn.Minor,
+		FileMode: &dn.FileMode,
+	}
 }