add method to check if a share provider for a given type is loaded

Signed-off-by: Bjoern Schiessle <bjoern@schiessle.org>

lib/private/Share20/Manager.php

@@ -30,6 +30,7 @@ namespace OC\Share20;
 use OC\Cache\CappedMemoryCache;
 use OC\Files\Mount\MoveableMount;
 use OC\HintException;
+use OC\Share20\Exception\ProviderException;
 use OCP\Files\File;
 use OCP\Files\Folder;
 use OCP\Files\IRootFolder;
@@ -1291,4 +1292,17 @@ class Manager implements IManager {
 		return $this->config->getAppValue('files_sharing', 'outgoing_server2server_share_enabled', 'yes') === 'yes';
 	}
 
+	/**
+	 * @inheritdoc
+	 */
+	public function shareProviderExists($shareType) {
+		try {
+			$this->factory->getProviderForType($shareType);
+		} catch (ProviderException $e) {
+			return false;
+		}
+
+		return true;
+	}
+
 }

lib/public/Share/IManager.php

@@ -286,4 +286,12 @@ interface IManager {
 	 */
 	public function outgoingServer2ServerSharesAllowed();
 
+	/**
+	 * Check if a given share provider exists
+	 * @param int $shareType
+	 * @return bool
+	 * @since 9.2.0
+	 */
+	public function shareProviderExists($shareType);
+
 }

tests/lib/Share20/ManagerTest.php

@@ -2530,6 +2530,46 @@ class ManagerTest extends \Test\TestCase {
 		$this->manager->moveShare($share, 'recipient');
 	}
 
+
+	/**
+	 * @dataProvider dataTestShareProviderExists
+	 */
+	public function testShareProviderExists($shareType, $expected) {
+
+		$factory = $this->getMockBuilder('OCP\Share\IProviderFactory')->getMock();
+		$factory->expects($this->any())->method('getProviderForType')
+			->willReturnCallback(function ($id) {
+				if ($id === \OCP\Share::SHARE_TYPE_USER) {
+					return true;
+				}
+				throw new Exception\ProviderException();
+			});
+
+		$manager = new Manager(
+			$this->logger,
+			$this->config,
+			$this->secureRandom,
+			$this->hasher,
+			$this->mountManager,
+			$this->groupManager,
+			$this->l,
+			$factory,
+			$this->userManager,
+			$this->rootFolder,
+			$this->eventDispatcher
+		);
+		$this->assertSame($expected,
+			$manager->shareProviderExists($shareType)
+		);
+	}
+
+	public function dataTestShareProviderExists() {
+		return [
+			[\OCP\Share::SHARE_TYPE_USER, true],
+			[42, false],
+		];
+	}
+
 	public function testGetSharesInFolder() {
 		$factory = new DummyFactory2($this->createMock(IServerContainer::class));