Fixed lint issues and missing documentation

internal/logging/logging.go

@@ -1,23 +1,33 @@
 package logging
 
 import (
+	"errors"
 	"log/slog"
 	"os"
+	"path/filepath"
 
 	"github.com/lmittmann/tint"
 )
 
 // ---------- Standard log handling (terminal or file based) ----------
 
-var logLevel slog.LevelVar
-var fileLogger *os.File
+// Logger state shared by the terminal and file loggers.
+var (
+	// logLevel is the minimum level logged, read by whichever handler is
+	// installed, so changing it takes effect immediately.
+	logLevel slog.LevelVar
+	// fileLogger is the log file opened by LogToFile, or nil when logging
+	// to the terminal.
+	fileLogger *os.File
+)
 
-// Set the logging to a particular level, quietly
+// SetLevel sets the logging level without logging the change.
 func SetLevel(level slog.Level) {
 	logLevel.Set(level)
 }
 
-// Enable debug level logging
+// EnableDebug lowers the logging level to debug, if it isn't already, and
+// logs that it did.
 func EnableDebug() {
 	if logLevel.Level() > slog.LevelDebug {
 		logLevel.Set(slog.LevelDebug)
@@ -29,15 +39,15 @@ func EnableDebug() {
 // logger. The file is created if needed and appended to; any log file opened
 // by an earlier call is closed.
 func LogToFile(logfile string) error {
-	if fileLogger != nil {
-		(*fileLogger).Close()
-	}
+	closeErr := Shutdown()
 
 	// Open the log file
 	var err error
-	fileLogger, err = os.OpenFile(logfile, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600)
+	fileLogger, err = os.OpenFile(
+		filepath.Clean(logfile), os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600,
+	)
 	if err != nil {
-		return err
+		return errors.Join(err, closeErr)
 	}
 
 	opts := &slog.HandlerOptions{
@@ -47,7 +57,7 @@ func LogToFile(logfile string) error {
 	logger := slog.New(handler)
 	slog.SetDefault(logger)
 
-	return nil
+	return closeErr
 }
 
 // Shutdown closes the log file opened by LogToFile, if any.