1 files changed, 106 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..21c246169
--- /dev/null
+++ b/pkg/sentry/fs/ramfs/symlink.go
@@ -0,0 +1,106 @@
+// Copyright 2018 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 ramfs
+
+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/waiter"
+)
+
+// Symlink represents a symlink.
+//
+// +stateify savable
+type Symlink struct {
+	fsutil.InodeGenericChecker `state:"nosave"`
+	fsutil.InodeNoopRelease    `state:"nosave"`
+	fsutil.InodeNoopWriteOut   `state:"nosave"`
+	fsutil.InodeNotAllocatable `state:"nosave"`
+	fsutil.InodeNotDirectory   `state:"nosave"`
+	fsutil.InodeNotMappable    `state:"nosave"`
+	fsutil.InodeNotSocket      `state:"nosave"`
+	fsutil.InodeNotTruncatable `state:"nosave"`
+	fsutil.InodeVirtual        `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
+	fsutil.InodeSimpleExtendedAttributes
+
+	// Target is the symlink target.
+	Target string
+}
+
+var _ fs.InodeOperations = (*Symlink)(nil)
+
+// NewSymlink returns a new Symlink.
+func NewSymlink(ctx context.Context, owner fs.FileOwner, target string) *Symlink {
+	// A symlink is assumed to always have permissions 0777.
+	return &Symlink{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(0777), linux.RAMFS_MAGIC),
+		Target:                target,
+	}
+}
+
+// UnstableAttr returns all attributes of this ramfs symlink.
+func (s *Symlink) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
+	uattr, err := s.InodeSimpleAttributes.UnstableAttr(ctx, inode)
+	if err != nil {
+		return fs.UnstableAttr{}, err
+	}
+	uattr.Size = int64(len(s.Target))
+	uattr.Usage = uattr.Size
+	return uattr, nil
+}
+
+// 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.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
+}
+
+// GetFile implements fs.FileOperations.GetFile.
+func (s *Symlink) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, dirent, flags, &symlinkFileOperations{}), nil
+}
+
+// +stateify savable
+type symlinkFileOperations struct {
+	fsutil.FileNoIoctl              `state:"nosave"`
+	fsutil.FileNoMMap               `state:"nosave"`
+	fsutil.FileNoRead               `state:"nosave"`
+	fsutil.FileNoSeek               `state:"nosave"`
+	fsutil.FileNoSplice             `state:"nosave"`
+	fsutil.FileNoWrite              `state:"nosave"`
+	fsutil.FileNoopFlush            `state:"nosave"`
+	fsutil.FileNoopFsync            `state:"nosave"`
+	fsutil.FileNoopRelease          `state:"nosave"`
+	fsutil.FileNotDirReaddir        `state:"nosave"`
+	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+	waiter.AlwaysReady              `state:"nosave"`
+}
+
+var _ fs.FileOperations = (*symlinkFileOperations)(nil)