fix(GODT-2614): Handle failed update during sync

The sync process was getting stuck since we never handled the case where
the update to Gluon failed. This caused the flush stage to exist, but
the sync process would continue until it eventually gets stuck due to
lack of progress.

internal/bridge/sync_unix_test.go

@@ -0,0 +1,81 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+//go:build !windows
+
+package bridge_test
+
+import (
+	"context"
+	"syscall"
+	"testing"
+
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/go-proton-api/server"
+	"github.com/ProtonMail/proton-bridge/v3/internal/bridge"
+	"github.com/ProtonMail/proton-bridge/v3/internal/events"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBridge_SyncExistsWithErrorWhenTooManyFilesAreOpen(t *testing.T) {
+	var rlimitCurrent syscall.Rlimit
+
+	require.NoError(t, syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimitCurrent))
+
+	// Restore RLimit for Process at the end of this test
+	defer func() {
+		require.NoError(t, syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimitCurrent))
+	}()
+
+	rlimit := syscall.Rlimit{
+		Max: 100,
+		Cur: 100,
+	}
+
+	require.NoError(t, syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit))
+
+	numMsg := 1 << 8
+
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, storeKey []byte) {
+		userID, addrID, err := s.CreateUser("imap", password)
+		require.NoError(t, err)
+
+		labelID, err := s.CreateLabel(userID, "folder", "", proton.LabelTypeFolder)
+		require.NoError(t, err)
+
+		withClient(ctx, t, s, "imap", password, func(ctx context.Context, c *proton.Client) {
+			createNumMessages(ctx, t, c, addrID, labelID, numMsg)
+		})
+
+		// The initial user should be fully synced.
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
+			syncCh, done := bridge.GetEvents(events.SyncFailed{})
+			defer done()
+
+			userID, err := bridge.LoginFull(ctx, "imap", password, nil, nil)
+			require.NoError(t, err)
+
+			evt := <-syncCh
+			switch e := evt.(type) {
+			case events.SyncFailed:
+				require.Equal(t, userID, e.UserID)
+			default:
+				require.Fail(t, "Expected events.SyncFailed{}")
+			}
+		})
+	}, server.WithTLS(false))
+}