feat: Dedicated directories for file provider domain support files.

Signed-off-by: Iva Horn <iva.horn@icloud.com>

Author: i2h3

Sources/NextcloudFileProviderKit/Database/FilesDatabaseManager.swift

@@ -66,12 +66,12 @@ public final class FilesDatabaseManager: Sendable {
     ///
     /// - Returns: The location of the database files directory.
     ///
-    private static func assertDatabaseDirectory() -> URL {
+    private static func assertDatabaseDirectory(for identifier: NSFileProviderDomainIdentifier) -> URL {
         Self.logger.debug("Asserting existence of database directory...")
 
         let manager = FileManager.default
 
-        guard let fileProviderExtensionDataDirectory = urlForFileProviderExtensionData() else {
+        guard let fileProviderExtensionDataDirectory = manager.fileProviderDomainSupportDirectory(for: identifier) else {
             Self.logger.fault("Failed to resolve the file provider extension data directory!")
             assertionFailure("Failed to resolve the file provider extension data directory!")
             return manager.temporaryDirectory // Only to satisfy the non-optional return type. The extension is unusable at this point anyway.
@@ -108,13 +108,20 @@ public final class FilesDatabaseManager: Sendable {
     ///     - account: The Nextcloud account for which the database is being created.
     ///     - customDatabaseDirectory: Optional custom directory where the database files should be stored. If not provided, the default directory will be used.
     ///
-    public init(realmConfiguration customConfiguration: Realm.Configuration? = nil, account: Account, databaseDirectory customDatabaseDirectory: URL? = nil) {
+    public init(realmConfiguration customConfiguration: Realm.Configuration? = nil, account: Account, databaseDirectory customDatabaseDirectory: URL? = nil, fileProviderDomainIdentifier: NSFileProviderDomainIdentifier) {
         self.account = account
 
         Self.logger.info("Initializing for account: \(account.ncKitAccount, privacy: .public)")
 
-        let databaseDirectory = customDatabaseDirectory ?? Self.assertDatabaseDirectory()
-        let accountDatabaseFilename = account.fileName + "-" + Self.databaseFilename
+        let databaseDirectory = customDatabaseDirectory ?? Self.assertDatabaseDirectory(for: fileProviderDomainIdentifier)
+        let accountDatabaseFilename: String
+
+        if UUID(uuidString: fileProviderDomainIdentifier.rawValue) != nil {
+            accountDatabaseFilename = "\(fileProviderDomainIdentifier.rawValue).realm"
+        } else {
+            accountDatabaseFilename = account.fileName + "-" + Self.databaseFilename
+        }
+
         let databaseLocation = databaseDirectory.appendingPathComponent(accountDatabaseFilename)
 
         let configuration = customConfiguration ?? Realm.Configuration(

Sources/NextcloudFileProviderKit/Extensions/FileManager+FileProviderDomainSupportDirectory.swift

@@ -0,0 +1,48 @@
+import FileProvider
+import Foundation
+
+public extension FileManager {
+    ///
+    /// Return the sandboxed application support directory specific to the file provider domain distinguished by the given identifier.
+    ///
+    /// If such directory does not exist yet, this attempts to create it implicitly.
+    ///
+    /// > Legacy Support: In the past, a subdirectory in the application group container was used for everything.
+    /// This caused crashes due to violations of sandbox restrictions.
+    /// If already existent, the legacy location will be used.
+    /// Otherwise the data will be stored in a new location.
+    ///
+    /// - Parameters:
+    ///     - identifier: File provider domain identifier which is used to isolate application support data for different file provider domains of the same extension.
+    ///
+    /// - Returns: A directory based on what the system returns for looking up standard directories. Likely in the sandbox containers of the file provider extension. Very unlikely to fail by returning `nil`.
+    ///
+    func fileProviderDomainSupportDirectory(for identifier: NSFileProviderDomainIdentifier) -> URL? {
+        // Legacy directory support.
+        if let containerUrl = pathForAppGroupContainer() {
+            let legacyLocation = containerUrl.appendingPathComponent("FileProviderExt")
+
+            if FileManager.default.fileExists(atPath: legacyLocation.path) {
+                return legacyLocation
+            }
+        }
+
+        // Designated file provider domain directories.
+        guard let applicationSupportDirectory = try? FileManager.default.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true) else {
+            return nil
+        }
+
+        let domainsSupportDirectory = applicationSupportDirectory.appendingPathComponent("File Provider Domains")
+        let fileProviderDomainSupportDirectory = domainsSupportDirectory.appendingPathComponent(identifier.rawValue)
+
+        if fileExists(atPath: fileProviderDomainSupportDirectory.path) == false {
+            do {
+                try createDirectory(at: fileProviderDomainSupportDirectory, withIntermediateDirectories: true)
+            } catch {
+                return nil
+            }
+        }
+
+        return fileProviderDomainSupportDirectory
+    }
+}

Sources/NextcloudFileProviderKit/Utilities/LocalFiles.swift

@@ -32,33 +32,6 @@ public func pathForAppGroupContainer() -> URL? {
     return FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroupIdentifier)
 }
 
-///
-/// Resolve the path where the file provider extension store its data.
-///
-/// In the past, this used a subdirectory in the application group container.
-/// If already existent, this will still be used.
-/// Otherwise the data will be stored in a new location.
-/// To comply with sandboxing and conventional directory structure of the platform, this uses the dedicated application support directory in the container of the file provider extension instead.
-///
-/// - Returns: The root location in which the extension can store its specific data.
-///
-public func urlForFileProviderExtensionData() -> URL? {
-    if let containerUrl = pathForAppGroupContainer() {
-        let legacyLocation = containerUrl.appendingPathComponent("FileProviderExt")
-
-        if FileManager.default.fileExists(atPath: legacyLocation.path) {
-            return legacyLocation
-        }
-    }
-
-    do {
-        return try FileManager.default.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
-    } catch {
-        lfuLogger.error("Failed to get URL for application support directory in user mask!")
-        return nil
-    }
-}
-
 public func pathForFileProviderTempFilesForDomain(_ domain: NSFileProviderDomain) throws -> URL? {
     guard let fpManager = NSFileProviderManager(for: domain) else {
         lfuLogger.error("Unable to get file provider manager for domain: \(domain.displayName, privacy: .public)")