Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 46 insertions, 0 deletions

diff --git a/pkg/sentry/fs/anon/anon.go b/pkg/sentry/fs/anon/anon.go
new file mode 100644
index 000000000..ddc2c0985
--- /dev/null
+++ b/pkg/sentry/fs/anon/anon.go
@@ -0,0 +1,46 @@
+// Copyright 2018 Google Inc.
+//
+// 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 anon implements an anonymous inode, useful for implementing
+// inodes for pseudo filesystems.
+package anon
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+)
+
+// NewInode constructs an anonymous Inode that is not associated
+// with any real filesystem. Some types depend on completely pseudo
+// "anon" inodes (eventfds, epollfds, etc).
+func NewInode(ctx context.Context) *fs.Inode {
+	return fs.NewInode(fsutil.NewSimpleInodeOperations(fsutil.InodeSimpleAttributes{
+		FSType: linux.ANON_INODE_FS_MAGIC,
+		UAttr: fs.WithCurrentTime(ctx, fs.UnstableAttr{
+			Owner: fs.FileOwnerFromContext(ctx),
+			Perms: fs.FilePermissions{
+				User: fs.PermMask{Read: true, Write: true},
+			},
+			Links: 1,
+		}),
+	}), fs.NewNonCachingMountSource(nil, fs.MountSourceFlags{}), fs.StableAttr{
+		Type:      fs.Anonymous,
+		DeviceID:  PseudoDevice.DeviceID(),
+		InodeID:   PseudoDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+	})
+}