fix: close rows after query timeout to prevent hang

Author: dlevy-msft-sql

cmd/modern/e2e_test.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -312,6 +313,23 @@ func TestE2E_PipedInput_WithBytesBuffer_NoPanic(t *testing.T) {
 	assert.NotContains(t, outputStr, "nil pointer", "should not have nil pointer error")
 }
 
+func TestE2E_QueryTimeout_NoHang(t *testing.T) {
+	skipIfNoLiveConnection(t)
+	binary := buildBinary(t)
+
+	args := append([]string{"-C", "-t", "1", "-Q", "WAITFOR DELAY '00:00:10'"}, getAuthArgs(t)...)
+	cmd := exec.Command(binary, args...)
+	cmd.Env = os.Environ()
+
+	start := time.Now()
+	output, err := cmd.CombinedOutput()
+	elapsed := time.Since(start)
+
+	assert.Error(t, err)
+	assert.Contains(t, string(output), "Timeout expired")
+	assert.Less(t, elapsed, 30*time.Second, "command hung instead of timing out")
+}
+
 // cleanupBinary removes the temporary build directory containing the test binary.
 // TestMain calls this to ensure deterministic cleanup instead of relying on
 // eventual OS temp directory maintenance.

pkg/sqlcmd/sqlcmd.go

@@ -431,6 +431,9 @@ func (s *Sqlcmd) runQuery(query string) (int, error) {
 	}
 	retmsg := &sqlexp.ReturnMessage{}
 	rows, qe := s.db.QueryContext(ctx, query, retmsg)
+	if rows != nil {
+		defer func() { _ = rows.Close() }()
+	}
 	if qe != nil {
 		s.Format.AddError(qe)
 	}