fix(GODT-2829): Fix new sync service bugs

* Fix wrong context use for message downloads
* Fix delete of sync data failing due ErrNotFound
* Pre-allocate attachment data buffer before download
* Fix calculation of progress if message count is higher than total

internal/user/migration.go

@@ -0,0 +1,42 @@
+// 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/>.
+
+package user
+
+import (
+	"fmt"
+
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapservice"
+	"github.com/ProtonMail/proton-bridge/v3/internal/vault"
+)
+
+func migrateSyncStatusFromVault(encVault *vault.User, syncConfigDir string, userID string) error {
+	syncStatus := encVault.SyncStatus()
+
+	migrated, err := imapservice.MigrateVaultSettings(syncConfigDir, userID, syncStatus.HasLabels, syncStatus.HasMessages, syncStatus.FailedMessageIDs)
+	if err != nil {
+		return fmt.Errorf("failed to migrate user sync settings: %w", err)
+	}
+
+	if migrated {
+		if err := encVault.ClearSyncStatus(); err != nil {
+			return fmt.Errorf("failed to clear sync settings from vault: %w", err)
+		}
+	}
+
+	return nil
+}

internal/user/user.go

@@ -156,19 +156,8 @@ func newImpl(
 	logrus.WithField("userID", apiUser.ID).Info("Creating new user")
 
 	// Migrate Sync Status from Vault.
-	{
-		syncStatus := encVault.SyncStatus()
-
-		migrated, err := imapservice.MigrateVaultSettings(syncConfigDir, apiUser.ID, syncStatus.HasLabels, syncStatus.HasMessages, syncStatus.FailedMessageIDs)
-		if err != nil {
-			return nil, fmt.Errorf("failed to migrate user sync settings: %w", err)
-		}
-
-		if migrated {
-			if err := encVault.ClearSyncStatus(); err != nil {
-				return nil, fmt.Errorf("failed to clear sync settings from vault: %w", err)
-			}
-		}
+	if err := migrateSyncStatusFromVault(encVault, syncConfigDir, apiUser.ID); err != nil {
+		return nil, err
 	}
 
 	// Get the user's API addresses.