1 files changed, 85 insertions, 0 deletions
diff --git a/hugofs/nosymlink_fs.go b/hugofs/nosymlink_fs.go
new file mode 100644
index 000000000..42ab94b5c
--- /dev/null
+++ b/hugofs/nosymlink_fs.go
@@ -0,0 +1,85 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// 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 hugofs
+
+import (
+	"errors"
+	"os"
+
+	"github.com/spf13/afero"
+)
+
+var (
+	ErrPermissionSymlink = errors.New("symlinks not allowed in this filesystem")
+)
+
+func NewNoSymlinkFs(fs afero.Fs) afero.Fs {
+	return &noSymlinkFs{Fs: fs}
+}
+
+// noSymlinkFs is a filesystem that prevents symlinking.
+type noSymlinkFs struct {
+	afero.Fs
+}
+
+func (fs *noSymlinkFs) LstatIfPossible(name string) (os.FileInfo, bool, error) {
+	return fs.stat(name)
+}
+
+func (fs *noSymlinkFs) Stat(name string) (os.FileInfo, error) {
+	fi, _, err := fs.stat(name)
+	return fi, err
+}
+
+func (fs *noSymlinkFs) stat(name string) (os.FileInfo, bool, error) {
+
+	var (
+		fi       os.FileInfo
+		wasLstat bool
+		err      error
+	)
+
+	if lstater, ok := fs.Fs.(afero.Lstater); ok {
+		fi, wasLstat, err = lstater.LstatIfPossible(name)
+	} else {
+
+		fi, err = fs.Fs.Stat(name)
+	}
+
+	var metaIsSymlink bool
+
+	if fim, ok := fi.(FileMetaInfo); ok {
+		metaIsSymlink = fim.Meta().IsSymlink()
+	}
+
+	if metaIsSymlink || isSymlink(fi) {
+		return nil, wasLstat, ErrPermissionSymlink
+	}
+
+	return fi, wasLstat, err
+}
+
+func (fs *noSymlinkFs) Open(name string) (afero.File, error) {
+	if _, _, err := fs.stat(name); err != nil {
+		return nil, err
+	}
+	return fs.Fs.Open(name)
+}
+
+func (fs *noSymlinkFs) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) {
+	if _, _, err := fs.stat(name); err != nil {
+		return nil, err
+	}
+	return fs.Fs.OpenFile(name, flag, perm)
+}