Allow ExecError to wrap other errors. Wrap ErrTimeout during timeout failures.

PiperOrigin-RevId: 507456687

go/helpers/helpers.go

@@ -38,6 +38,7 @@ type ExecResult struct {
 type ExecError struct {
 	errmsg     string
 	procresult ExecResult
+	wraps      error
 }
 
 // ExecConfig provides flexible execution configuration.
@@ -85,6 +86,8 @@ func (e ExecError) Error() string {
 	return e.errmsg
 }
 
+func (e ExecError) Unwrap() error { return e.wraps }
+
 // Result returns any information that could be captured from the subprocess that was executed.
 func (e ExecError) Result() ExecResult {
 	return e.procresult

go/helpers/helpers_windows.go

@@ -205,9 +205,10 @@ func execute(path string, args []string, conf *ExecConfig) (ExecResult, error) {
 
 	// when the execution times out return a timeout error
 	if conf.Timeout != nil && !timer.Stop() {
-		return result, &ExecError{
+		return result, ExecError{
 			errmsg:     ErrTimeout.Error(),
 			procresult: result,
+			wraps:      ErrTimeout,
 		}
 	}