3 files changed, 30 insertions, 0 deletions
diff --git a/lib/private/User/LazyUser.php b/lib/private/User/LazyUser.php
index 396d3c252f1..ae10937a66b 100644
--- a/lib/private/User/LazyUser.php
+++ b/lib/private/User/LazyUser.php
@@ -51,6 +51,11 @@ class LazyUser implements IUser {
 				$this->user = $this->userManager->get($this->uid);
 			}
 		}
+
+		if ($this->user === null) {
+			throw new \Exception('User not found');
+		}
+		
 		/** @var IUser */
 		$user = $this->user;
 		return $user;
@@ -167,4 +172,16 @@ class LazyUser implements IUser {
 	public function setManagerUids(array $uids): void {
 		$this->getUser()->setManagerUids($uids);
 	}
+
+	public function isFederated(): bool {
+		try {
+			// If getUser succeeds then user is definitely not federated
+			// This could fail for other reasons (especially a race condition where a user is deleted)
+			// But it's what we have now
+			$this->getUser();
+			return false;
+		} catch (\Exception $e) {
+			return true;
+		}
+	}
 }
diff --git a/lib/private/User/User.php b/lib/private/User/User.php
index daa78011007..398ea9e1a19 100644
--- a/lib/private/User/User.php
+++ b/lib/private/User/User.php
@@ -619,4 +619,9 @@ class User implements IUser {
 			$this->emitter->emit('\OC\User', 'changeUser', [$this, $feature, $value, $oldValue]);
 		}
 	}
+
+	public function isFederated(): bool {
+		// Federated users only use LazyUser
+		return 0;
+	}
 }
diff --git a/lib/public/IUser.php b/lib/public/IUser.php
index b326e6192c0..61ecb5d2f21 100644
--- a/lib/public/IUser.php
+++ b/lib/public/IUser.php
@@ -287,4 +287,12 @@ interface IUser {
 	 * @since 27.0.0
 	 */
 	public function setManagerUids(array $uids): void;
+
+	/**
+	 * Check if the user is federated (from another server)
+	 *
+	 * @return boll
+	 * @since 28.0.11
+	 */
+	public function isFederated(): bool;
 }