fix(GODT-2442): Use rename instead of remove for db files

Unfortunately, closing the Ent database clients doesn't guarantee that
all the SQLite db files are closed. This causes issues on Windows where
the files are locked, making it impossible to remove and re-add the same
user.

builder.go

@@ -2,6 +2,8 @@ package gluon
 
 import (
 	"crypto/tls"
+	"github.com/ProtonMail/gluon/internal/db"
+	"github.com/sirupsen/logrus"
 	"io"
 	"os"
 	"time"
@@ -86,6 +88,12 @@ func (builder *serverBuilder) build() (*Server, error) {
 		return nil, err
 	}
 
+	// Defer delete all the previous databases from removed user accounts. This is required since we can't
+	// close ent databases on demand.
+	if err := db.DeleteDeferredDBFiles(builder.databaseDir); err != nil {
+		logrus.WithError(err).Error("Failed to remove old database files")
+	}
+
 	return &Server{
 		dataDir:              builder.dataDir,
 		databaseDir:          builder.databaseDir,

internal/db/db.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"github.com/ProtonMail/gluon/internal/utils"
+	"github.com/google/uuid"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -109,6 +110,10 @@ func getDatabasePath(dir, userID string) string {
 	return filepath.Join(dir, fmt.Sprintf("%v.db", userID))
 }
 
+func getDeferredDeleteDBPath(dir string) string {
+	return filepath.Join(dir, "deferred_delete")
+}
+
 // NewDB creates a new database instance.
 // If the database does not exist, it will be created and the second return value will be true.
 func NewDB(dir, userID string) (*DB, bool, error) {
@@ -132,8 +137,42 @@ func NewDB(dir, userID string) (*DB, bool, error) {
 	return &DB{db: client}, !exists, nil
 }
 
+// DeleteDB will rename all the database files for the given user to a directory within the same folder to avoid
+// issues with ent not being able to close the database on demand. The database will be cleaned up on the next
+// run on the Gluon server.
 func DeleteDB(dir, userID string) error {
-	return os.Remove(getDatabasePath(dir, userID))
+	// Rather than deleting the files immediately move them to a directory to be cleaned up later.
+	deferredDeletePath := getDeferredDeleteDBPath(dir)
+
+	if err := os.MkdirAll(deferredDeletePath, 0o700); err != nil {
+		return fmt.Errorf("failed to create deferred delete dir: %w", err)
+	}
+
+	matchingFiles, err := filepath.Glob(filepath.Join(dir, userID))
+	if err != nil {
+		return fmt.Errorf("failed to match db files:%w", err)
+	}
+
+	for _, file := range matchingFiles {
+		// Use new UUID to avoid conflict with existing files
+		if err := os.Rename(file, filepath.Join(deferredDeletePath, uuid.NewString())); err != nil {
+			return fmt.Errorf("failed to move db file '%v' :%w", file, err)
+		}
+	}
+
+	return nil
+}
+
+// DeleteDeferredDBFiles deletes all data from previous databases that were scheduled for removal.
+func DeleteDeferredDBFiles(dir string) error {
+	deferredDeleteDir := getDeferredDeleteDBPath(dir)
+	if err := os.RemoveAll(deferredDeleteDir); err != nil {
+		if !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+	}
+
+	return nil
 }
 
 // pathExists returns whether the given file exists.