file storage

Author: chlowell

extensions/accessor/file/file.go

@@ -0,0 +1,52 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+package file
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/AzureAD/microsoft-authentication-extensions-for-go/extensions/accessor"
+)
+
+// Storage stores data in an unencrypted file.
+type Storage struct {
+	m *sync.RWMutex
+	p string
+}
+
+// New is the constructor for Storage. "p" is the path to the file in which to store data.
+func New(p string) (*Storage, error) {
+	return &Storage{m: &sync.RWMutex{}, p: p}, nil
+}
+
+// Read returns the file's content or, if the file doesn't exist, a nil slice and error.
+func (s *Storage) Read(context.Context) ([]byte, error) {
+	s.m.RLock()
+	defer s.m.RUnlock()
+	b, err := os.ReadFile(s.p)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, nil
+	}
+	return b, err
+}
+
+// Write stores data in the file, overwriting any content, and creates the file if necessary.
+func (s *Storage) Write(ctx context.Context, data []byte) error {
+	s.m.Lock()
+	defer s.m.Unlock()
+	err := os.WriteFile(s.p, data, 0600)
+	if errors.Is(err, os.ErrNotExist) {
+		dir := filepath.Dir(s.p)
+		if err = os.MkdirAll(dir, 0700); err == nil {
+			err = os.WriteFile(s.p, data, 0600)
+		}
+	}
+	return err
+}
+
+var _ accessor.Accessor = (*Storage)(nil)

extensions/accessor/file/file_test.go

@@ -0,0 +1,70 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+package file
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var ctx = context.Background()
+
+func TestRead(t *testing.T) {
+	p := filepath.Join(t.TempDir(), t.Name())
+	a, err := New(p)
+	require.NoError(t, err)
+
+	expected := []byte("expected")
+	require.NoError(t, os.WriteFile(p, expected, 0600))
+
+	actual, err := a.Read(ctx)
+	require.NoError(t, err)
+	require.Equal(t, expected, actual)
+}
+
+func TestRoundTrip(t *testing.T) {
+	p := filepath.Join(t.TempDir(), "nonexistent", t.Name())
+	a, err := New(p)
+	require.NoError(t, err)
+
+	var expected []byte
+	for i := 0; i < 4; i++ {
+		actual, err := a.Read(ctx)
+		require.NoError(t, err)
+		require.Equal(t, expected, actual)
+
+		expected = append(expected, byte(i))
+		require.NoError(t, a.Write(ctx, expected))
+	}
+}
+
+func TestWrite(t *testing.T) {
+	p := filepath.Join(t.TempDir(), t.Name())
+	for _, create := range []bool{true, false} {
+		name := "file exists"
+		if create {
+			name = "new file"
+		}
+		t.Run(name, func(t *testing.T) {
+			if create {
+				f, err := os.OpenFile(p, os.O_CREATE|os.O_EXCL, 0600)
+				require.NoError(t, err)
+				require.NoError(t, f.Close())
+			}
+			a, err := New(p)
+			require.NoError(t, err)
+
+			expected := []byte("expected")
+			require.NoError(t, a.Write(ctx, expected))
+
+			actual, err := os.ReadFile(p)
+			require.NoError(t, err)
+			require.Equal(t, expected, actual)
+		})
+	}
+}