fix(exec): guard default logger access

Co-authored-by: Virgil <virgil@lethean.io>

exec/exec_test.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -138,6 +139,29 @@ func TestSetDefaultLogger(t *testing.T) {
 	}
 }
 
+func TestDefaultLogger_IsConcurrentSafe(t *testing.T) {
+	original := exec.DefaultLogger()
+	defer exec.SetDefaultLogger(original)
+
+	logger := &mockLogger{}
+
+	var wg sync.WaitGroup
+	for i := 0; i < 32; i++ {
+		wg.Add(2)
+		go func() {
+			defer wg.Done()
+			exec.SetDefaultLogger(logger)
+		}()
+		go func() {
+			defer wg.Done()
+			_ = exec.DefaultLogger()
+		}()
+	}
+	wg.Wait()
+
+	assert.NotNil(t, exec.DefaultLogger())
+}
+
 func TestCommand_UsesDefaultLogger(t *testing.T) {
 	original := exec.DefaultLogger()
 	defer exec.SetDefaultLogger(original)

exec/logger.go

@@ -1,5 +1,7 @@
 package exec
 
+import "sync"
+
 // Logger interface for command execution logging.
 // Compatible with pkg/log.Logger and other structured loggers.
 type Logger interface {
@@ -26,7 +28,10 @@ func (NopLogger) Error(string, ...any) {}
 
 var _ Logger = NopLogger{}
 
-var defaultLogger Logger = NopLogger{}
+var (
+	defaultLoggerMu sync.RWMutex
+	defaultLogger   Logger = NopLogger{}
+)
 
 // SetDefaultLogger sets the package-level default logger.
 // Commands without an explicit logger will use this.
@@ -35,6 +40,9 @@ var defaultLogger Logger = NopLogger{}
 //
 //	exec.SetDefaultLogger(logger)
 func SetDefaultLogger(l Logger) {
+	defaultLoggerMu.Lock()
+	defer defaultLoggerMu.Unlock()
+
 	if l == nil {
 		l = NopLogger{}
 	}
@@ -47,5 +55,8 @@ func SetDefaultLogger(l Logger) {
 //
 //	logger := exec.DefaultLogger()
 func DefaultLogger() Logger {
+	defaultLoggerMu.RLock()
+	defer defaultLoggerMu.RUnlock()
+
 	return defaultLogger
 }