feat: Allow to check user existence outside specific user backends

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

Author: CarlSchwan

lib/private/User/Manager.php

@@ -126,19 +126,25 @@ public function clearBackends() {
 	 * @param string $uid
 	 * @return \OC\User\User|null Either the user or null if the specified user does not exist
 	 */
-	public function get($uid) {
+	public function get($uid, array $excludeBackends = []) {
 		if (is_null($uid) || $uid === '' || $uid === false) {
 			return null;
 		}
-		if (isset($this->cachedUsers[$uid])) { //check the cache first to prevent having to loop over the backends
-			return $this->cachedUsers[$uid];
-		}
 
 		if (strlen($uid) > self::MAX_USERID_LENGTH) {
 			return null;
 		}
 
+		// check the cache first to prevent having to loop over the backends
+		if ($excludeBackends === [] && isset($this->cachedUsers[$uid])) {
+			return $this->cachedUsers[$uid];
+		}
+
 		$cachedBackend = $this->cache->get(sha1($uid));
+		if (in_array($cachedBackend, $excludeBackends)) {
+			$cachedBackend = null;
+		}
+
 		if ($cachedBackend !== null && isset($this->backends[$cachedBackend])) {
 			// Cache has the info of the user backend already, so ask that one directly
 			$backend = $this->backends[$cachedBackend];
@@ -153,6 +159,10 @@ public function get($uid) {
 				continue;
 			}
 
+			if (in_array($i, $excludeBackends)) {
+				continue;
+			}
+
 			if ($backend->userExists($uid)) {
 				// Hash $uid to ensure that only valid characters are used for the cache key
 				$this->cache->set(sha1($uid), $i, 300);
@@ -196,12 +206,12 @@ public function getUserObject($uid, $backend, $cacheUser = true) {
 	 * @param string $uid
 	 * @return bool
 	 */
-	public function userExists($uid) {
+	public function userExists($uid, array $excludeBackends = []) {
 		if (strlen($uid) > self::MAX_USERID_LENGTH) {
 			return false;
 		}
 
-		$user = $this->get($uid);
+		$user = $this->get($uid, $excludeBackends);
 		return ($user !== null);
 	}
 

lib/public/IUserManager.php

@@ -77,13 +77,14 @@ public function get($uid);
 	public function getDisplayName(string $uid): ?string;
 
 	/**
-	 * check if a user exists
+	 * Check if a user exists.
 	 *
 	 * @param string $uid
+	 * @param list<string> $excludeBackends A list of IUserBackend::getBackendName() that need to be excluded from the search.
 	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function userExists($uid);
+	public function userExists($uid, array $excludeBackends = []);
 
 	/**
 	 * Check if the password is valid for the user

tests/Core/Command/User/AddTest.php

@@ -110,6 +110,11 @@ public function testAddEmail(
 		$this->mailHelper->expects($isEmailValid && $shouldSendEmail ? static::once() : static::never())
 			->method('sendMail');
 
+		$this->consoleInput->method('getArgument')
+			->willReturnMap([
+				['uid', 'JohnDoe'],
+			]);
+
 		$this->consoleInput->method('getOption')
 			->will(static::returnValueMap([
 				['generate-password', 'true'],

tests/lib/Share20/ManagerTest.php

@@ -993,10 +993,7 @@ public function dataGeneralChecks() {
 	public function testGeneralChecks($share, $exceptionMessage, $exception): void {
 		$thrown = null;
 
-		$this->userManager->method('userExists')->willReturnMap([
-			['user0', true],
-			['user1', true],
-		]);
+		$this->userManager->method('userExists')->willReturnCallBack(fn (string $userId) => $userId === 'user0' || $userId === 'user1');
 
 		$this->groupManager->method('groupExists')->willReturnMap([
 			['group0', true],