1 files changed, 72 insertions, 0 deletions
diff --git a/pkg/sentry/fs/ramfs/symlink.go b/pkg/sentry/fs/ramfs/symlink.go
new file mode 100644
index 000000000..9bbf78619
--- /dev/null
+++ b/pkg/sentry/fs/ramfs/symlink.go
@@ -0,0 +1,72 @@
+// 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 ramfs
+
+import (
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+)
+
+// Symlink represents a symlink.
+type Symlink struct {
+	Entry
+
+	mu sync.Mutex `state:"nosave"`
+
+	// Target is the symlink target.
+	Target string
+}
+
+// InitSymlink initializes a symlink, pointing to the given target.
+// A symlink is assumed to always have permissions 0777.
+func (s *Symlink) InitSymlink(ctx context.Context, owner fs.FileOwner, target string) {
+	s.InitEntry(ctx, owner, fs.FilePermsFromMode(0777))
+	s.Target = target
+}
+
+// UnstableAttr returns all attributes of this ramfs symlink.
+func (s *Symlink) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
+	uattr, _ := s.Entry.UnstableAttr(ctx, inode)
+	uattr.Size = int64(len(s.Target))
+	uattr.Usage = uattr.Size
+	return uattr, nil
+}
+
+// Check implements InodeOperations.Check.
+func (s *Symlink) Check(ctx context.Context, inode *fs.Inode, p fs.PermMask) bool {
+	return fs.ContextCanAccessFile(ctx, inode, p)
+}
+
+// SetPermissions on a symlink is always rejected.
+func (s *Symlink) SetPermissions(context.Context, *fs.Inode, fs.FilePermissions) bool {
+	return false
+}
+
+// Readlink reads the symlink value.
+func (s *Symlink) Readlink(ctx context.Context, _ *fs.Inode) (string, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.Entry.NotifyAccess(ctx)
+	return s.Target, nil
+}
+
+// Getlink returns ErrResolveViaReadlink, falling back to walking to the result
+// of Readlink().
+func (*Symlink) Getlink(context.Context, *fs.Inode) (*fs.Dirent, error) {
+	return nil, fs.ErrResolveViaReadlink
+}