Add //pkg/sentry/devices/memdev.

PiperOrigin-RevId: 292165063

1 files changed, 59 insertions, 0 deletions

diff --git a/pkg/sentry/devices/memdev/memdev.go b/pkg/sentry/devices/memdev/memdev.go
new file mode 100644
index 000000000..5759900c4
--- /dev/null
+++ b/pkg/sentry/devices/memdev/memdev.go
@@ -0,0 +1,59 @@
+// Copyright 2020 The gVisor Authors.
+//
+// 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 memdev implements "mem" character devices, as implemented in Linux
+// by drivers/char/mem.c and drivers/char/random.c.
+package memdev
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/devtmpfs"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// Register registers all devices implemented by this package in vfsObj.
+func Register(vfsObj *vfs.VirtualFilesystem) error {
+	for minor, dev := range map[uint32]vfs.Device{
+		nullDevMinor:    nullDevice{},
+		zeroDevMinor:    zeroDevice{},
+		fullDevMinor:    fullDevice{},
+		randomDevMinor:  randomDevice{},
+		urandomDevMinor: randomDevice{},
+	} {
+		if err := vfsObj.RegisterDevice(vfs.CharDevice, linux.MEM_MAJOR, minor, dev, &vfs.RegisterDeviceOptions{
+			GroupName: "mem",
+		}); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// CreateDevtmpfsFiles creates device special files in dev representing all
+// devices implemented by this package.
+func CreateDevtmpfsFiles(ctx context.Context, dev *devtmpfs.Accessor) error {
+	for minor, name := range map[uint32]string{
+		nullDevMinor:    "null",
+		zeroDevMinor:    "zero",
+		fullDevMinor:    "full",
+		randomDevMinor:  "random",
+		urandomDevMinor: "urandom",
+	} {
+		if err := dev.CreateDeviceFile(ctx, name, vfs.CharDevice, linux.MEM_MAJOR, minor, 0666 /* mode */); err != nil {
+			return err
+		}
+	}
+	return nil
+}