all: sync with master; upd chlog

internal/aghrenameio/renameio.go

@@ -0,0 +1,52 @@
+// Package aghrenameio is a wrapper around package github.com/google/renameio/v2
+// that provides a similar stream-based API for both Unix and Windows systems.
+// While the Windows API is not technically atomic, it still provides a
+// consistent stream-based interface, and atomic renames of files do not seem to
+// be possible in all cases anyway.
+//
+// See https://github.com/google/renameio/issues/1.
+//
+// TODO(a.garipov): Consider moving to golibs/renameioutil once tried and
+// tested.
+package aghrenameio
+
+import (
+	"io/fs"
+
+	"github.com/AdguardTeam/golibs/errors"
+)
+
+// PendingFile is the interface for pending temporary files.
+type PendingFile interface {
+	// Cleanup closes the file, and removes it without performing the renaming.
+	// To close and rename the file, use CloseReplace.
+	Cleanup() (err error)
+
+	// CloseReplace closes the temporary file and replaces the destination file
+	// with it, possibly atomically.
+	//
+	// This method is not safe for concurrent use by multiple goroutines.
+	CloseReplace() (err error)
+
+	// Write writes len(b) bytes from b to the File.  It returns the number of
+	// bytes written and an error, if any.  Write returns a non-nil error when n
+	// != len(b).
+	Write(b []byte) (n int, err error)
+}
+
+// NewPendingFile is a wrapper around [renameio.NewPendingFile] on Unix systems
+// and [os.CreateTemp] on Windows.
+func NewPendingFile(filePath string, mode fs.FileMode) (f PendingFile, err error) {
+	return newPendingFile(filePath, mode)
+}
+
+// WithDeferredCleanup is a helper that performs the necessary cleanups and
+// finalizations of the temporary files based on the returned error.
+func WithDeferredCleanup(returned error, file PendingFile) (err error) {
+	// Make sure that any error returned from here is marked as a deferred one.
+	if returned != nil {
+		return errors.WithDeferred(returned, file.Cleanup())
+	}
+
+	return errors.WithDeferred(nil, file.CloseReplace())
+}

internal/aghrenameio/renameio_test.go

@@ -0,0 +1,101 @@
+package aghrenameio_test
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/aghrenameio"
+	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// testPerm is the common permission mode for tests.
+const testPerm fs.FileMode = 0o644
+
+// Common file data for tests.
+var (
+	initialData = []byte("initial data\n")
+	newData     = []byte("new data\n")
+)
+
+func TestPendingFile(t *testing.T) {
+	t.Parallel()
+
+	targetPath := newInitialFile(t)
+	f, err := aghrenameio.NewPendingFile(targetPath, testPerm)
+	require.NoError(t, err)
+
+	_, err = f.Write(newData)
+	require.NoError(t, err)
+
+	err = f.CloseReplace()
+	require.NoError(t, err)
+
+	gotData, err := os.ReadFile(targetPath)
+	require.NoError(t, err)
+
+	assert.Equal(t, newData, gotData)
+}
+
+// newInitialFile is a test helper that returns the path to the file containing
+// [initialData].
+func newInitialFile(t *testing.T) (targetPath string) {
+	t.Helper()
+
+	dir := t.TempDir()
+	targetPath = filepath.Join(dir, "target")
+
+	err := os.WriteFile(targetPath, initialData, 0o644)
+	require.NoError(t, err)
+
+	return targetPath
+}
+
+func TestWithDeferredCleanup(t *testing.T) {
+	t.Parallel()
+
+	const testError errors.Error = "test error"
+
+	testCases := []struct {
+		error      error
+		name       string
+		wantErrMsg string
+		wantData   []byte
+	}{{
+		name:       "success",
+		error:      nil,
+		wantErrMsg: "",
+		wantData:   newData,
+	}, {
+		name:       "error",
+		error:      testError,
+		wantErrMsg: testError.Error(),
+		wantData:   initialData,
+	}}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			targetPath := newInitialFile(t)
+			f, err := aghrenameio.NewPendingFile(targetPath, testPerm)
+			require.NoError(t, err)
+
+			_, err = f.Write(newData)
+			require.NoError(t, err)
+
+			err = aghrenameio.WithDeferredCleanup(tc.error, f)
+			testutil.AssertErrorMsg(t, tc.wantErrMsg, err)
+
+			gotData, err := os.ReadFile(targetPath)
+			require.NoError(t, err)
+
+			assert.Equal(t, tc.wantData, gotData)
+		})
+	}
+}

internal/aghrenameio/renameio_unix.go

@@ -0,0 +1,48 @@
+//go:build unix
+
+package aghrenameio
+
+import (
+	"io/fs"
+
+	"github.com/google/renameio/v2"
+)
+
+// pendingFile is a wrapper around [*renameio.PendingFile] making it an
+// [io.WriteCloser].
+type pendingFile struct {
+	file *renameio.PendingFile
+}
+
+// type check
+var _ PendingFile = pendingFile{}
+
+// Cleanup implements the [PendingFile] interface for pendingFile.
+func (f pendingFile) Cleanup() (err error) {
+	return f.file.Cleanup()
+}
+
+// CloseReplace implements the [PendingFile] interface for pendingFile.
+func (f pendingFile) CloseReplace() (err error) {
+	return f.file.CloseAtomicallyReplace()
+}
+
+// Write implements the [PendingFile] interface for pendingFile.
+func (f pendingFile) Write(b []byte) (n int, err error) {
+	return f.file.Write(b)
+}
+
+// NewPendingFile is a wrapper around [renameio.NewPendingFile].
+//
+// f.Close must be called to finish the renaming.
+func newPendingFile(filePath string, mode fs.FileMode) (f PendingFile, err error) {
+	file, err := renameio.NewPendingFile(filePath, renameio.WithPermissions(mode))
+	if err != nil {
+		// Don't wrap the error since it's informative enough as is.
+		return nil, err
+	}
+
+	return pendingFile{
+		file: file,
+	}, nil
+}

internal/aghrenameio/renameio_windows.go

@@ -0,0 +1,74 @@
+//go:build windows
+
+package aghrenameio
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	"github.com/AdguardTeam/golibs/errors"
+)
+
+// pendingFile is a wrapper around [*os.File] calling [os.Rename] in its Close
+// method.
+type pendingFile struct {
+	file       *os.File
+	targetPath string
+}
+
+// type check
+var _ PendingFile = (*pendingFile)(nil)
+
+// Cleanup implements the [PendingFile] interface for *pendingFile.
+func (f *pendingFile) Cleanup() (err error) {
+	closeErr := f.file.Close()
+	err = os.Remove(f.file.Name())
+
+	// Put closeErr into the deferred error because that's where it is usually
+	// expected.
+	return errors.WithDeferred(err, closeErr)
+}
+
+// CloseReplace implements the [PendingFile] interface for *pendingFile.
+func (f *pendingFile) CloseReplace() (err error) {
+	err = f.file.Close()
+	if err != nil {
+		return fmt.Errorf("closing: %w", err)
+	}
+
+	err = os.Rename(f.file.Name(), f.targetPath)
+	if err != nil {
+		return fmt.Errorf("renaming: %w", err)
+	}
+
+	return nil
+}
+
+// Write implements the [PendingFile] interface for *pendingFile.
+func (f *pendingFile) Write(b []byte) (n int, err error) {
+	return f.file.Write(b)
+}
+
+// NewPendingFile is a wrapper around [os.CreateTemp].
+//
+// f.Close must be called to finish the renaming.
+func newPendingFile(filePath string, mode fs.FileMode) (f PendingFile, err error) {
+	// Use the same directory as the file itself, because moves across
+	// filesystems can be especially problematic.
+	file, err := os.CreateTemp(filepath.Dir(filePath), "")
+	if err != nil {
+		return nil, fmt.Errorf("opening pending file: %w", err)
+	}
+
+	err = file.Chmod(mode)
+	if err != nil {
+		return nil, fmt.Errorf("preparing pending file: %w", err)
+	}
+
+	return &pendingFile{
+		file:       file,
+		targetPath: filePath,
+	}, nil
+}