backend: include rotated logs in export

CHANGELOG.md

@@ -4,6 +4,7 @@
 - Add a dropdown on the "Receiver address" input in the send screen to select an account
 - Add feedback link to guide and about settings
 - Move active currencies to top of currency dropdown
+- Export logs now includes rotated log file (log.txt.1) when present
 - Android: fix connectivity misdetection when switching between WIFI and cellular network.
 - Android: dropped support for Android versions lower than 7.
 - Sort backups from newest to oldest in manage backups

backend/backend.go

@@ -18,7 +18,6 @@ package backend
 import (
 	"encoding/hex"
 	"fmt"
-	"io"
 	"net/http"
 	"net/url"
 	"os"
@@ -1102,28 +1101,20 @@ func (backend *Backend) ExportLogs() error {
 	}
 	backend.log.Infof("Export logs to %s.", path)
 
-	file, err := os.Create(path)
+	exportFile, err := os.Create(path)
 	if err != nil {
 		backend.log.WithError(err).Error("error creating new log file")
 		return err
 	}
 	logFilePath := filepath.Join(utilConfig.AppDir(), "log.txt")
 
-	existingLogFile, err := os.Open(logFilePath)
-	if err != nil {
-		backend.log.WithError(err).Error("error opening existing log file")
+	if err := logging.WriteCombinedLog(exportFile, logFilePath); err != nil {
+		backend.log.WithError(err).Error("error copying existing logs to new file")
+		_ = exportFile.Close()
 		return err
 	}
-
-	defer func() {
-		if err := existingLogFile.Close(); err != nil {
-			backend.log.WithError(err).Error("error closing existing log file")
-		}
-	}()
-
-	_, err = io.Copy(file, existingLogFile)
-	if err != nil {
-		backend.log.WithError(err).Error("error copying existing log to new file")
+	if err := exportFile.Close(); err != nil {
+		backend.log.WithError(err).Error("error closing new log file")
 		return err
 	}
 	backend.log.Infof("Exported logs copied to %s.", path)

util/logging/export.go

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package logging
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// WriteCombinedLog writes the current log file and, if it exists, the rotated-out log file
+// (with ".1" appended) into dst, in chronological order (rotated file first).
+func WriteCombinedLog(dst io.Writer, logFilePath string) error {
+	paths := []string{}
+
+	rotatedLogFilePath := logFilePath + rotatedSuffix
+	if _, err := os.Stat(rotatedLogFilePath); err == nil {
+		paths = append(paths, rotatedLogFilePath)
+	} else if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+
+	if _, err := os.Stat(logFilePath); err == nil {
+		paths = append(paths, logFilePath)
+	} else if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+
+	if len(paths) == 0 {
+		return fmt.Errorf("no log files found at %s", logFilePath)
+	}
+
+	for idx, path := range paths {
+		if idx > 0 {
+			if _, err := io.WriteString(dst, "\n\n"); err != nil {
+				return err
+			}
+		}
+		if _, err := io.WriteString(dst, fmt.Sprintf("----- %s -----\n", filepath.Base(path))); err != nil {
+			return err
+		}
+		file, err := os.Open(path)
+		if err != nil {
+			return err
+		}
+		_, copyErr := io.Copy(dst, file)
+		closeErr := file.Close()
+		if copyErr != nil {
+			return copyErr
+		}
+		if closeErr != nil {
+			return closeErr
+		}
+	}
+	return nil
+}

util/logging/export_test.go

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package logging
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestWriteCombinedLog(t *testing.T) {
+	tempdir := t.TempDir()
+
+	logfile := filepath.Join(tempdir, "log.txt")
+	require.NoError(t, os.WriteFile(logfile, []byte("new\n"), 0600))
+	require.NoError(t, os.WriteFile(logfile+".1", []byte("old\n"), 0600))
+
+	var buf bytes.Buffer
+	require.NoError(t, WriteCombinedLog(&buf, logfile))
+	require.Equal(t, "----- log.txt.1 -----\nold\n\n\n----- log.txt -----\nnew\n", buf.String())
+}
+
+func TestWriteCombinedLogNoRotatedFile(t *testing.T) {
+	tempdir := t.TempDir()
+
+	logfile := filepath.Join(tempdir, "log.txt")
+	require.NoError(t, os.WriteFile(logfile, []byte("new\n"), 0600))
+
+	var buf bytes.Buffer
+	require.NoError(t, WriteCombinedLog(&buf, logfile))
+	require.Equal(t, "----- log.txt -----\nnew\n", buf.String())
+}
+
+func TestWriteCombinedLogNoFiles(t *testing.T) {
+	tempdir := t.TempDir()
+	logfile := filepath.Join(tempdir, "log.txt")
+
+	var buf bytes.Buffer
+	require.Error(t, WriteCombinedLog(&buf, logfile))
+}