Use the correct mountpoint to calculate

If we use the owners mount point this results in null. And then the rest
of the checks get called with null. Which doesn't work.

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

lib/private/Share20/Manager.php

@@ -298,13 +298,20 @@ class Manager implements IManager {
 
 		$isFederatedShare = $share->getNode()->getStorage()->instanceOfStorage('\OCA\Files_Sharing\External\Storage');
 		$permissions = 0;
-		$mount = $share->getNode()->getMountPoint();
+
+		$userMounts = $userFolder->getById($share->getNode()->getId());
+		$userMount = array_shift($userMounts);
+		$mount = $userMount->getMountPoint();
 		if (!$isFederatedShare && $share->getNode()->getOwner() && $share->getNode()->getOwner()->getUID() !== $share->getSharedBy()) {
 			// When it's a reshare use the parent share permissions as maximum
 			$userMountPointId = $mount->getStorageRootId();
 			$userMountPoints = $userFolder->getById($userMountPointId);
 			$userMountPoint = array_shift($userMountPoints);
 
+			if ($userMountPoint === null) {
+				throw new GenericShareException('Could not get proper user mount for ' . $userMountPointId . '. Failing since else the next calls are called with null');
+			}
+
 			/* Check if this is an incoming share */
 			$incomingShares = $this->getSharedWith($share->getSharedBy(), IShare::TYPE_USER, $userMountPoint, -1, 0);
 			$incomingShares = array_merge($incomingShares, $this->getSharedWith($share->getSharedBy(), IShare::TYPE_GROUP, $userMountPoint, -1, 0));

tests/lib/Share20/ManagerTest.php

@@ -613,6 +613,7 @@ class ManagerTest extends \Test\TestCase {
 		$limitedPermssions = $this->createMock(File::class);
 		$limitedPermssions->method('isShareable')->willReturn(true);
 		$limitedPermssions->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_READ);
+		$limitedPermssions->method('getId')->willReturn(108);
 		$limitedPermssions->method('getPath')->willReturn('path');
 		$limitedPermssions->method('getOwner')
 			->willReturn($owner);
@@ -634,6 +635,7 @@ class ManagerTest extends \Test\TestCase {
 		$nonMoveableMountPermssions = $this->createMock(Folder::class);
 		$nonMoveableMountPermssions->method('isShareable')->willReturn(true);
 		$nonMoveableMountPermssions->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_READ);
+		$nonMoveableMountPermssions->method('getId')->willReturn(108);
 		$nonMoveableMountPermssions->method('getPath')->willReturn('path');
 		$nonMoveableMountPermssions->method('getOwner')
 			->willReturn($owner);
@@ -655,6 +657,7 @@ class ManagerTest extends \Test\TestCase {
 		$allPermssions = $this->createMock(Folder::class);
 		$allPermssions->method('isShareable')->willReturn(true);
 		$allPermssions->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_ALL);
+		$allPermssions->method('getId')->willReturn(108);
 		$allPermssions->method('getOwner')
 			->willReturn($owner);
 		$allPermssions->method('getStorage')
@@ -675,6 +678,7 @@ class ManagerTest extends \Test\TestCase {
 		$remoteFile = $this->createMock(Folder::class);
 		$remoteFile->method('isShareable')->willReturn(true);
 		$remoteFile->method('getPermissions')->willReturn(\OCP\Constants::PERMISSION_READ ^ \OCP\Constants::PERMISSION_UPDATE);
+		$remoteFile->method('getId')->willReturn(108);
 		$remoteFile->method('getOwner')
 			->willReturn($owner);
 		$remoteFile->method('getStorage')
@@ -709,6 +713,11 @@ class ManagerTest extends \Test\TestCase {
 		$userFolder->expects($this->any())
 			->method('getId')
 			->willReturn(42);
+		// Id 108 is used in the data to refer to the node of the share.
+		$userFolder->expects($this->any())
+			->method('getById')
+			->with(108)
+			->willReturn([$share->getNode()]);
 		$userFolder->expects($this->any())
 			->method('getRelativePath')
 			->willReturnArgument(0);