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// 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"
"path/filepath"
"github.com/gohugoio/hugo/common/loggers"
"github.com/spf13/afero"
)
var ErrPermissionSymlink = errors.New("symlinks not allowed in this filesystem")
// NewNoSymlinkFs creates a new filesystem that prevents symlinks.
func NewNoSymlinkFs(fs afero.Fs, logger loggers.Logger, allowFiles bool) afero.Fs {
return &noSymlinkFs{Fs: fs, logger: logger, allowFiles: allowFiles}
}
var (
_ FilesystemUnwrapper = (*noSymlinkFs)(nil)
)
// noSymlinkFs is a filesystem that prevents symlinking.
type noSymlinkFs struct {
allowFiles bool // block dirs only
logger loggers.Logger
afero.Fs
}
type noSymlinkFile struct {
fs *noSymlinkFs
afero.File
}
func (f *noSymlinkFile) Readdir(count int) ([]os.FileInfo, error) {
fis, err := f.File.Readdir(count)
filtered := fis[:0]
for _, x := range fis {
filename := filepath.Join(f.Name(), x.Name())
if _, err := f.fs.checkSymlinkStatus(filename, x); err != nil {
// Log a warning and drop the file from the list
logUnsupportedSymlink(filename, f.fs.logger)
} else {
filtered = append(filtered, x)
}
}
return filtered, err
}
func (f *noSymlinkFile) Readdirnames(count int) ([]string, error) {
dirs, err := f.Readdir(count)
if err != nil {
return nil, err
}
return fileInfosToNames(dirs), nil
}
func (fs *noSymlinkFs) UnwrapFilesystem() afero.Fs {
return fs.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)
}
if err != nil {
return nil, false, err
}
fi, err = fs.checkSymlinkStatus(name, fi)
return fi, wasLstat, err
}
func (fs *noSymlinkFs) checkSymlinkStatus(name string, fi os.FileInfo) (os.FileInfo, error) {
var metaIsSymlink bool
if fim, ok := fi.(FileMetaInfo); ok {
meta := fim.Meta()
metaIsSymlink = meta.IsSymlink
}
if metaIsSymlink {
if fs.allowFiles && !fi.IsDir() {
return fi, nil
}
return nil, ErrPermissionSymlink
}
// Also support non-decorated filesystems, e.g. the Os fs.
if isSymlink(fi) {
// Need to determine if this is a directory or not.
_, sfi, err := evalSymlinks(fs.Fs, name)
if err != nil {
return nil, err
}
if fs.allowFiles && !sfi.IsDir() {
// Return the original FileInfo to get the expected Name.
return fi, nil
}
return nil, ErrPermissionSymlink
}
return fi, nil
}
func (fs *noSymlinkFs) Open(name string) (afero.File, error) {
if _, _, err := fs.stat(name); err != nil {
return nil, err
}
return fs.wrapFile(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.wrapFile(fs.Fs.OpenFile(name, flag, perm))
}
func (fs *noSymlinkFs) wrapFile(f afero.File, err error) (afero.File, error) {
if err != nil {
return nil, err
}
return &noSymlinkFile{File: f, fs: fs}, nil
}
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