From d23917c5761b6d562160f5f03f21fca1bcf233ed Mon Sep 17 00:00:00 2001
From: Benjamin Wang <wachao@vmware.com>
Date: Thu, 16 Jun 2022 15:17:58 +0800
Subject: [PATCH] Add FileReader and FileBufReader utilities

The FileReader interface is the wrapper of io.Reader. It provides
the fs.FileInfo as well. The FileBufReader struct is the wrapper of
bufio.Reader, it also provides fs.FileInfo.

Signed-off-by: Benjamin Wang <wachao@vmware.com>
---
 client/pkg/fileutil/filereader.go      | 60 ++++++++++++++++++++++++++
 client/pkg/fileutil/filereader_test.go | 41 ++++++++++++++++++
 2 files changed, 101 insertions(+)
 create mode 100644 client/pkg/fileutil/filereader.go
 create mode 100644 client/pkg/fileutil/filereader_test.go

diff --git a/client/pkg/fileutil/filereader.go b/client/pkg/fileutil/filereader.go
new file mode 100644
index 000000000..55248888c
--- /dev/null
+++ b/client/pkg/fileutil/filereader.go
@@ -0,0 +1,60 @@
+// Copyright 2022 The etcd 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 fileutil
+
+import (
+	"bufio"
+	"io"
+	"io/fs"
+	"os"
+)
+
+// FileReader is a wrapper of io.Reader. It also provides file info.
+type FileReader interface {
+	io.Reader
+	FileInfo() (fs.FileInfo, error)
+}
+
+type fileReader struct {
+	*os.File
+}
+
+func NewFileReader(f *os.File) FileReader {
+	return &fileReader{f}
+}
+
+func (fr *fileReader) FileInfo() (fs.FileInfo, error) {
+	return fr.Stat()
+}
+
+// FileBufReader is a wrapper of bufio.Reader. It also provides file info.
+type FileBufReader struct {
+	*bufio.Reader
+	fi fs.FileInfo
+}
+
+func NewFileBufReader(fr FileReader) *FileBufReader {
+	bufReader := bufio.NewReader(fr)
+	fi, err := fr.FileInfo()
+	if err != nil {
+		// This should never happen.
+		panic(err)
+	}
+	return &FileBufReader{bufReader, fi}
+}
+
+func (fbr *FileBufReader) FileInfo() fs.FileInfo {
+	return fbr.fi
+}
diff --git a/client/pkg/fileutil/filereader_test.go b/client/pkg/fileutil/filereader_test.go
new file mode 100644
index 000000000..f64d1029e
--- /dev/null
+++ b/client/pkg/fileutil/filereader_test.go
@@ -0,0 +1,41 @@
+// Copyright 2022 The etcd 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 fileutil
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFileBufReader(t *testing.T) {
+	f, err := os.CreateTemp(t.TempDir(), "wal")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	fi, err := f.Stat()
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	fbr := NewFileBufReader(NewFileReader(f))
+
+	assert.Equal(t, fi.Name(), fbr.FileInfo().Name())
+	assert.Equal(t, fi.Size(), fbr.FileInfo().Size())
+	assert.Equal(t, fi.IsDir(), fbr.FileInfo().IsDir())
+	assert.Equal(t, fi.Mode(), fbr.FileInfo().Mode())
+	assert.Equal(t, fi.ModTime(), fbr.FileInfo().ModTime())
+}