Attach to the X server on the active VT and keep a retryable DXGI frame from tearing down the capturer

Claude-Session: https://claude.ai/code/session_01QKDYfH4WKLbpNQHccpVo3P
2026-10-13 17:09:07 +02:00 · 2026-08-29 16:59:05 +02:00
parent 15d6e3bea9
commit fecd7cfff5
17 changed files with 476 additions and 85 deletions
@@ -0,0 +1,94 @@
+//go:build (linux && !android) || freebsd
+
+package server
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestPickXorgCandidate covers which X server a service-mode capturer attaches
+// to when several are running. Picking the wrong one shows a remote user
+// another local user's screen, so the active VT wins whenever it is known.
+func TestPickXorgCandidate(t *testing.T) {
+	tests := []struct {
+		name       string
+		candidates []xorgCandidate
+		activeVT   int
+		want       string
+		wantOK     bool
+	}{
+		{
+			name:   "no X server found",
+			wantOK: false,
+		},
+		{
+			name:       "single server is used whatever its VT",
+			candidates: []xorgCandidate{{display: ":3", vt: 9}},
+			activeVT:   2,
+			want:       ":3",
+			wantOK:     true,
+		},
+		{
+			name: "active VT wins over the lower display number",
+			candidates: []xorgCandidate{
+				{display: ":0", vt: 2},
+				{display: ":1", vt: 7},
+			},
+			activeVT: 7,
+			want:     ":1",
+			wantOK:   true,
+		},
+		{
+			name: "unknown active VT falls back to the lowest display",
+			candidates: []xorgCandidate{
+				{display: ":1", vt: 7},
+				{display: ":0", vt: 2},
+			},
+			activeVT: -1,
+			want:     ":0",
+			wantOK:   true,
+		},
+		{
+			name: "display numbers compare numerically, not lexically",
+			candidates: []xorgCandidate{
+				{display: ":10", vt: -1},
+				{display: ":2", vt: -1},
+			},
+			activeVT: -1,
+			want:     ":2",
+			wantOK:   true,
+		},
+		{
+			name: "an unparseable display is only picked when it is alone",
+			candidates: []xorgCandidate{
+				{display: ":bogus", vt: -1},
+				{display: ":4", vt: -1},
+			},
+			activeVT: -1,
+			want:     ":4",
+			wantOK:   true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, ok := pickXorgCandidate(tc.candidates, tc.activeVT)
+			require.Equal(t, tc.wantOK, ok)
+			if !tc.wantOK {
+				return
+			}
+			assert.Equal(t, tc.want, got.display)
+		})
+	}
+}
+
+// TestParseXorgVT confirms the bare "vt7" token X servers carry in argv is the
+// one read, and that nothing else in the command line is mistaken for it.
+func TestParseXorgVT(t *testing.T) {
+	assert.Equal(t, 7, parseXorgVT([]string{"/usr/lib/Xorg", ":0", "-auth", "/run/x.auth", "vt7", "-novtswitch"}))
+	assert.Equal(t, -1, parseXorgVT([]string{"/usr/bin/Xvfb", ":99", "-screen", "0", "1920x1080x24"}))
+	assert.Equal(t, -1, parseXorgVT([]string{"/usr/lib/Xorg", ":0", "vtconsole"}))
+}