runtime: Move the resourcecontrol package one layer up

And try to reduce the number of virtcontainers packages, step by step.

Signed-off-by: Samuel Ortiz <s.ortiz@apple.com>

src/runtime/pkg/resourcecontrol/utils.go

@@ -0,0 +1,59 @@
+// Copyright (c) 2020 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package resourcecontrol
+
+import (
+	"fmt"
+
+	"github.com/opencontainers/runc/libcontainer/devices"
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"golang.org/x/sys/unix"
+)
+
+func DeviceToCgroupDeviceRule(device string) (*devices.Rule, error) {
+	var st unix.Stat_t
+	deviceRule := devices.Rule{
+		Allow:       true,
+		Permissions: "rwm",
+	}
+
+	if err := unix.Stat(device, &st); err != nil {
+		return nil, err
+	}
+
+	devType := st.Mode & unix.S_IFMT
+
+	switch devType {
+	case unix.S_IFCHR:
+		deviceRule.Type = 'c'
+	case unix.S_IFBLK:
+		deviceRule.Type = 'b'
+	default:
+		return nil, fmt.Errorf("unsupported device type: %v", devType)
+	}
+
+	major := int64(unix.Major(st.Rdev))
+	minor := int64(unix.Minor(st.Rdev))
+	deviceRule.Major = major
+	deviceRule.Minor = minor
+
+	return &deviceRule, nil
+}
+
+func DeviceToLinuxDevice(device string) (specs.LinuxDeviceCgroup, error) {
+	dev, err := DeviceToCgroupDeviceRule(device)
+	if err != nil {
+		return specs.LinuxDeviceCgroup{}, err
+	}
+
+	return specs.LinuxDeviceCgroup{
+		Allow:  dev.Allow,
+		Type:   string(dev.Type),
+		Major:  &dev.Major,
+		Minor:  &dev.Minor,
+		Access: string(dev.Permissions),
+	}, nil
+}